WO2016209942A1 - Composite gypsum board and methods related thereto - Google Patents
Composite gypsum board and methods related thereto Download PDFInfo
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- WO2016209942A1 WO2016209942A1 PCT/US2016/038737 US2016038737W WO2016209942A1 WO 2016209942 A1 WO2016209942 A1 WO 2016209942A1 US 2016038737 W US2016038737 W US 2016038737W WO 2016209942 A1 WO2016209942 A1 WO 2016209942A1
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- concentrated layer
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- composite gypsum
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/02—Physical, chemical or physicochemical properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B13/00—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material
- B32B13/02—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material with fibres or particles being present as additives in the layer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B13/00—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material
- B32B13/04—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material comprising such water setting substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B13/00—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material
- B32B13/04—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material comprising such water setting substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B13/08—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material comprising such water setting substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of paper or cardboard
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B13/00—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material
- B32B13/14—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material next to a fibrous or filamentary layer
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
- E04C2/02—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials
- E04C2/04—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of concrete or other stone-like material; of asbestos cement; of cement and other mineral fibres
- E04C2/043—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of concrete or other stone-like material; of asbestos cement; of cement and other mineral fibres of plaster
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2250/00—Layers arrangement
- B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/536—Hardness
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/54—Yield strength; Tensile strength
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/718—Weight, e.g. weight per square meter
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/72—Density
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2419/00—Buildings or parts thereof
- B32B2419/06—Roofs, roof membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2607/00—Walls, panels
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00241—Physical properties of the materials not provided for elsewhere in C04B2111/00
- C04B2111/00413—Materials having an inhomogeneous concentration of ingredients or irregular properties in different layers
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00612—Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
- C04B2111/0062—Gypsum-paper board like materials
Definitions
- Set gypsum i.e., calcium sulfate dihydrate
- gypsum board is in the form of a set gypsum core sandwiched between two cover sheets (e.g.. paper-faced board) and is commonly used in drywall construction of interior walls and ceilings of buildings.
- cover sheets e.g.. paper-faced board
- skim coats may be included on either side of the core, usually at the paper-core interface.
- stucco i.e., calcined gypsum in the form of calcium sulfate hemihydrate and/or calcium sulfate anhydrite
- water typically in a pin mixer as the term is used in the art.
- a slurry is formed and discharged from die mixer onto a moving conveyor carrying a cover sheet with one of the skim coats (if present) already applied (often upstream of the mixer). The slurry is spread over die paper (with skim coat optionally included on the paper).
- Another cover sheet, with or without skim coat, is applied onto the slurry to form die sandwich structure of desired thickness with the aid of e.g., a forming plate or the like.
- the mixture is cast and al lowed to harden to form set (i.e., rehydrated) gypsum by reaction of die calcined gypsum with water to form a matrix of crystalline hydrated gypsum (i.e., calcium sulfate dihydrate). It is the desired hydration of die calcined gypsum that enables the formation of the interlocking matrix of set gypsum crystals, thereby imparting strength to the gypsum structure in the product.
- Heat is required (e.g., in a kiln) to drive off the remaining free (i.e., unreacted) water to yield a dry product. 10004 J
- the excess water thai is driven off represents inefficiency in the system. Energy input is required to remove the water, and the manufacturing process is slowed to
- gypsum hoard e.g., commercial gypsum board product, including board weight and strength.
- Another challenge is reducing the weight of gypsum board while maintaining strength.
- One measure of the strength of board is "nail pull resistance,” sometimes simply referred to as “nail pull.”
- foaming agent can be introduced into the slurry to form air voids in the final product.
- Replacing solid mass with air in the gypsum board envelope reduces weight, but that loss of solid mass can also result in less strength. Compensating for loss in strength is a significant obstacle in weight reduction efforts in the art.
- the disclosure provides a composite gypsum board.
- the composite board comprises a board core comprising set gypsum formed from at least water, stucco, and optionally, an enhancing additive.
- the board core defines first and second core faces in opposing relation and a concentrated layer.
- the concentrated layer is disposed in bonding relation to the first core lace.
- the concentrated layer is formed from the enhancing additive, water, and. e.g., a eementitious material, such as stucco, to form a bydrated cementitious material such as set gypsum in a continuous crystalline matrix.
- the enhancing additive is preferably more concentrated (by weight percentage) in the concentrated layer than in the board core.
- any reference to the enhancing additive being "more
- the concentrated in die slurry for forming the concentrated layer than i the slurry for forming board core includes the situations where (a) both the concentrated layer and the board core are formed from enhancing additive, and (b) the concentrated layer is formed from the enhancing addiiive but the board core contains zero, or no, enhancing additive.
- the concentrated layer has a density of at least about 1 , 1 times higher than a density of the board core and has a thickness of from about 0.02 inches (about 0.05 cm) to about 0.2 inches (about 0.5 era) in some embodiments.
- the board core preferably has a thickness greater than the thickness of the concentrated layer,
- the enhancing addiiive includes a strength -imparting additive as described herein that helps produce desired strength properties as described herein.
- Board formed from a concentrated layer slurry containing higher weight percentage of the enhancing additive than contained in the board core slurry allows for one or more efficiencies or process benefits.
- the overall use of enhancing additive in the board can be reduced by focusing the enhancing additive in forming a smaller weight section of smaller thickness (i.e., the concentrated layer) and using less or no enhancing additive in forming a larger weight section of larger thickness (i.e., the board core).
- the concentrated layer formed from a higher weight percentage of the enhancing additive, is able to distribute the desired resulting properties throughout the board core, such that the board exhibits the strength properties.
- the board core can be made with less overall enhancing additive, and in some embodiments can be lighter and less dense than conventional board cores, in turn, overall board weight can be reduced as the density in a large weight section of the board (i.e., the core) is reduced.
- some enhancing additives such as certain pregeiatinized starches, they can require water in a slurry, i.e., they increase water demand.
- the water demand in the slurry for forming the core can be reduced in some embodiments.
- overall water usage in preparing the board can be reduced, which further can improve efficiencies as less water is used in the system such that less water is required to be driveii off by heating in the kiln.
- manufacturing line speed can be improved and drying costs can be reduced.
- the composite gypsum board can be within a range of desired densities.
- the board can be made at ultra-light weights, such as at a board density of about 33 pcf or less. It will be understood that board weight is a function of density and thickness. Thus, density can be used as a measure of board weight as will be understood in the art. Such ultra-light weights can be achieved without compromising desired strength properties.
- the composite gypsum board can. exhibit a nail pull resistance of at least about 65 lbs of feree (e.g., at least about 72 lbs of force, at least about 77 lbs of feree, etc.) according to ASTM C473-10, Method B.
- the disclosure provides a method of making composite gypsum hoard.
- the method comprises preparing a concentrated layer slurry comprising water and the enhancing additive.
- the concentrated layer slurry can also include a base material to impart, e.g., a primary source of mass and density, such as a cernentitious material, e.g., stucco that can hydrate to form an interlocking matrix of set gypsum.
- the concentrated layer slurry is applied in a bonding relation to a first cover sheet to form a concentrated layer having a first face and a second face. The first face of the concentrated layer faces the first cover sheet.
- the method also comprises mixing at least water, stucco, and optionally the enhancing additive, to form a hoard core slurry.
- the board core slurry is applied in a bonding relation to the concentrated layer to form a board core.
- the board core has a first face and a second face, wherein the first board core face faces the concentrated layer second face.
- a second cover sheet is applied in bonding relation to the second board core face to form a board precursor.
- the hoard precursor is dried to form the board.
- the concentrated layer slurry contains a higher weight percentage of the enhancing slurry than the board core slurry.
- the concentrated layer has a thickness of from about 0.02 inches (about 0.05 cm) to about 0.2 inches (about 0.5 cm). When dried, the hoard core has a thickness greater than the thickness of the concentrated layer.
- the disclosure provides another method of making composite gypsum board.
- the method comprises preparing a concentrated layer slurry comprising water and the enhancing additive.
- the concentrated layer slurry can also include a base material to impart, e.g., a primary source of mass and density, such as a cernentitious material, e.g., stucco that can hydrate to form an interlocking matrix of set gypsum.
- the concentrated layer slurry is applied in a bonding relation to a first cover sheet to form a concentrated layer having a first face and a second face. The first face of the concentrated layer faces the first cover sheet.
- the method also comprises mixing at least water, stucco, and optionally the enhancing additive, to form a board core slurry.
- the board core slurry is applied in a bonding relation to the concentrated layer to form a board core.
- the board core has a first face and a second face, wherein the first board core face faces the concentrated layer second face.
- a second cover sheet is applied in bonding relation to the second hoard core face to form a board precursor.
- the board precursor is dried to form die board.
- the concentrated layer slurry contains a higher weight percentage of the enhancing slurry than the board core slurry.
- the board core has a thickness greater than the thickness of the concentrated layer.
- Processes according to the disclosure can be used to produce composite board at any suitable density.
- the board can be made at ultra-light weights, such as at a board density of about 33 pcf (about 530 kg m 3 ) or less. Such ultra-light weights can be achieved without compromising desired strength properties.
- the composite gypsum board can exhibit a nail pull resistance of at least about 65 lbs of feree (e.g., at least about 72 lbs of feree, at least about 77 lbs of force, etc.) according to ASTM C473-10, Method B.
- Other aspects and embodiments will be apparent from the full description herein.
- FIG. 1 is a schematic sectional view of a composite gypsum board constructed in accordance with principles of the present disclosure.
- FIG. 2 illustrates schematic flow diagrams of three alternate process arrangements
- FIG. 3 is an illustration depicting a slurry head upstream of a roller used in forming a concentrated layer on a manufacturing line for gypsum vvallboard in a trial as discussed in Example 3 herein, wherein the slurry is absent glass fiber,
- FIG. 4 is an il lustration depicting a slurry head upstream of a roller used in forming a concentrated layer on a manufacturing line for gypsum wall board in a trial as discussed in Example 3 herein, wherein the slurry contains glass fiber.
- FIG. 5 is an illustration depicting the slurry forming an edge around the roller of the trial depicted in FIG. 3 as discussed in Example 3 herein, wherein the slurry is absent glass fiber.
- FIG. 6 is an illustration depicting the slurry forming an edge around the roller of the trial depicted in FIG. 4 as discussed in Example 3 herein, wherein the slurry contains glass fiber.
- Embodiments of the disclosure provide a novel construction for a composite board (e.g., gypsum board, such as wallboard) and a method of making such board.
- gypsum wallboard (often referred to as drywali), can encompass such board used not only for walls but also for ceilings and other locations as understood in the art.
- the composite board contains multiple layers which contain dilferent cementitious compositions, e.g., in the form of a continuous crystalline matrix of set gypsum in the final product.
- One layer forms the board core and another layer forms a concentrated layer of substantial thickness (e.g., at least about 0.02 inches, or about 0.05 cm).
- the board core is generally thicker than the concentrated layer in preferred embodiments and makes up the bulk (e.g., over about 60%, such as over about 70%, over about 75%, etc) of the volume of the board' s envelope.
- the board also includes top (face) and bottom (back) cover sheets.
- the board core and the concentrated layer are both formed from cementitious material and water.
- the concentrated layer is formulated to have a higher density than the board core has (e.g., at least about 1.1 times higher).
- foaming agents as known in the art can be used in the board core, although other materials for reducing density can be included in the slurry for forming the board core, as an alternative or additional ingredient, such as lightweight filler including, tor example, lightweight aggregate or perlite, particularly if the additional expense can be accepted.
- the concentrated layer can include less or no foaming agent and/or less or no lightweight filler in order to achieve the desired higher density in that layer.
- compositions of, and inter-relationships between, the respective layers in the composite board impart surprising and unexpected properties in the product.
- the targeted use of enhancing additive- in the concentrated layer can be used to impart desired board properties, and enhance process efficiencies as desired, hi addition, in some embodiments, aspects such as (a) the thickness, density, and/or strength of the concentrated layer, and/or (b) the properties of the concentrated layer relative to the paper and the board core, respectively, can be used to optimize board properties as desired.
- the dry concentrated layer has a stiffness value that is closer to a stiffness value of the top cover sheet to which it is generally adjacent, The concentrated layer has a higher stiffness value than the board core in some embodiments, Tims, the concentrated layer can be disposed between a material with relatively good stiffness and strength (i.e., the top cover sheet) and a material with less stiffness and strength (i.e., the board core) in some embodiments. It will be understood that stiffness value can be measured according to Young's modulus as known in the art.
- the concentrated layer is disposed between a top cover sheet and a preferably lighter and weaker board core.
- the concentrated layer serves to absorb energy from a load and more uniformly distribute the load into the board core and throughout the board such that the load desirably will more readily attenuate and dissipate.
- the inventive composite gypsum board will demonstrate good strength properties and allow for lower weiglii board to be produced by targeting enhanced strength in the concentrated layer where the property can be distributed into the board core. For example, this advantage can be illustrated via good results on a nail pull resistance and flexura! strength tests in some embodiments, as is understood in the art in accordance with ASTM 473-10, Method B.
- the composite gypsum board is tailored to include an enhancing additive in a higher concentration than the enhancing additive is included (if at all) in the board core.
- the resulting board can be formed to achieve a composite gypsum board with desired strength properties
- the higher concentration of the enhancing additive in the concentrated layer relative to the board core results in efficient board performance with respect to desired strength properties, e.g., nail pull resistance, compressive strength, flexura! strength, etc.
- desired strength properties e.g., nail pull resistance, compressive strength, flexura! strength, etc.
- the present inventors have found thai, the usage of the enhancing additives can be optimized in accordance with preferred embodiments by tailoring the formulations of the compositions of the respective board core and concentrated layers to include enhancing additives where their effect can provide more of an impact to achieve desired strength properties (i.e., in a higher weight percentage in the concentrated layer than in the board core), and a lower overall water demand.
- This discovery imparts a considerable advantage including, but not limited to, reducing overall enhancing additive usage and, hence, cost of the raw material, enhancing manufacturing efficiency, and enhancing product strength, e.g., allowing for lower weight product with sufficient strength properties.
- the slurry for forming the concentrated layer contains at least about 1 .2 times the concentration of the enhancing additive as compared with the slurry for forming board core, such as, for example, at least about 1 ,5 times, at least about 1.7 times, at least about 2 times, at least about 2.5 times, at least about 3 times, at least about 3.5 times, at least about 4 times, at least about 4.5 times, at least about 5 times, at least about 6 times, etc., wherein each of these ranges can ha ve any suitable upper limit as appropriate, such as, for example, about 60, about 50, about 40, about 30, about 20, about 10, about 9, about 8, about 7, about 6.5, about 6, about 5.5, about 5, about 4.5, about 4, about 3.5, about 3, about 2.5, about 2, about 1.5, etc.
- “higher concentration,” as used herein, refers to relative amounts of an enhancing additive (by weight of the stucco), as opposed to gross amounts of ingredients. Since the board core provides a higher bulk volume and thickness contribution to the board, as compared with such contribution by the concentrated layer, it is possible that any particular additive may be provided in a higher total gross amount in the board core slurry, e.g., in pounds or kilograms, yet be provided in a lower weight concentration as compared with the slurry for the concentrated layer, i.e., in a lower relative amount, e.g., in weight percentage (wt.%),
- some embodiments of the disclosure are effective in reducing the overall water usage in making the composite gypsum board.
- the total amount of water used to make the board can be reduced such that water usage is optimized since the water is present in a higher concentration where it is needed more (e.g., in the concentrated layer) and reduced where it is needed less (e.g., in the board core),
- set gypsum is formed from a stucco slurry (sometimes cal led a gypsum slurry) containing water and stucco
- WSR water-to-stucco ratio
- the board core which can form the bulk of the board volume, can be formed from a lower WSR as compared with the WSR used to form the concentrated layer.
- the overall water usage and WSR in the composite gypsum board as a whole can advantageously be brought down in some embodiments since the contribution to the overall board volume by the concentrated layer is less than the contribution to the overall board volume by the bo'ard core.
- the board core and concentrated layer can be formed from any suitable WSR, in some embodiments, the concentrated layer is formed from slurry having a WSR that is higher than the WSR of the slurry used to form the board core.
- the concentrated layer is formed from a slurry having a WSR that is at least about 1.2 times higher than the WSR of the slurry used to form the board core (e.g., at least about 1 ,5 times higher, at least about 1.7 times higher, at least about 2 times higher, at least about 2.2 times higher, at least about 2.5 times higher, at least about 2.7 times higher, at least about 3 times higher, at least about 3.2 times higher, at least about 3.5 times higher, at least about 3.7 times higher, at least about 4 times higher etc., wherein each of these ranges can have any suitable upper limit as appropriate, such as, for example, about 7, about 6.5, about 6, about 5.5, about 5, about 4.5, about 4, about 3,5, about 3, about 2,5, about 2, about 1 ,
- the board core is formed from stucco slurry having a water-stucco ratio from about 0.3 to about 1.3, e.g., from about 0.3 to about 1.2, from about 0.3 to about 1.2, from about 0,3 to about 1.2, from about 0.3 to about 1.2, from about 0.3 to about 1.1 , from about 0.3 to about 1 , from about 0.3 to about 0.9, from about 0.4 to about 1.3, from, about 0.4 to about 1.2, from about 0.4 to about 1 ,1 , from about 0.4 to about 1 , from about 0.4 to about 0.9, from about 0.5 to about 1.3, from about 0.5 to about 1.2, from about 0.5 to about.
- lower water-stucco ratios are preferred, e.g., from about 0.3 to about 0,8, such as, for example, from about 0.3 to about 0.7, from about 0.3 to about 0.6, from about. 0.3 to about 0.5, from about 0.3 to about 0.4, from about 0.4 to about 0.8, from about 0.4 to about 0.7, from about 0.4 to about 0.6, from about 0,4 to about 0.5, from about 0.5 to about 0,8, from about 0,5 to about 0.7, from about 0.5 to about 0.6, from about 0.6 to about 0,8, from about 0.6 to about 0.7, etc.
- about 0.3 to about 0,8 such as, for example, from about 0.3 to about 0.7, from about 0.3 to about 0.6, from about. 0.3 to about 0.5, from about 0.3 to about 0.4, from about 0.4 to about 0.8, from about 0.4 to about 0.7, from about 0.4 to about 0.6, from about 0,4 to about 0.5, from about 0.5 to about 0,8, from about 0,5 to about 0.7
- the concentrated layer is formed from a slurry having a water-stucco ratio from about 0.7 to about 2, such as, for example, from about 0.7 to about 1.7, from about 0.7 to about 1.4, from about 0.7 to about 1.2, from about 0,7 to about 1 , from about 0.8 to about 2, from about 0.8 to about 1 .7, from about 0.8 to about 1.4, from about 0.8 to about 1.2, from about 0.8 to about 1 , from about 1 to about 2, from about 1 to about 1.7, from about 1 to about 1.4, from about 1 to about 1.2, from about 1.2 to about 2, from about 1 ,2 to about 1.7.
- a slurry having a water-stucco ratio from about 0.7 to about 2, such as, for example, from about 0.7 to about 1.7, from about 0.7 to about 1.4, from about 0.7 to about 1.2, from about 0,7 to about 1 , from about 0.8 to about 2, from about 0.8 to about 1 .7, from about 0.8 to about
- the concentrated layer can have a higher water content to satisfy the water demand of enhancing additives. Since the enhancing additive content is more concentrated in the concentrated layer in some embodiments, the higher water demand can be more isolated to the concentrated layer, thereby allowing for a lower WSR in the board core, and, advantageously, a lower water usage overall, particularly in view of the board core's large contribution to the volume bulk of the composite board.
- the composite gypsum board according to embodiments of the disclosure has utility in a variety of desired densities for gypsum board, i.e.,, drywall or wallboard (which can encompass such board used not only for walls but also for ceilings and other locations as understood in the art).
- board weight is a function of thickness. Since boards are commonly made at varying thicknesses (e.g., 3/8 inch, 1 ⁇ 2 inch, 3 ⁇ 4 inch, one inch, etc.), board density is used herein as a measure of board weight.
- the advantages of the composite gypsum board in accordance with embodiments of the disclosure can be seen at a range of dry densities, including up to heavier board densities, e.g., about 43 pef (about 690 kg m 3 ) or less, such as from about 18 pcf (about 290 kg m " ") to about 43 pet, from about 20 pef (about 320 kg m 3 ) to about 43 pcf, from about 20 pcf to about 40 pcf (about 640 kg/nr'), from about 24 pcf (about 380 kg m 3 ) to about 43 pcf, from about 27 pef (about 430 kg m 3 ) to about 43 pcf, from about 20 pcf to about 38 pcf (about 610 kg/m 3 ), from about 24 pcf to about 40 pcf, from about 27 pcf to about 40 pcf, from about 20 pef to about.
- dry board density can be from about 16 pcf to about 33 pef, e.g., from about 16 pcf to about 27 pcf, from about 16 pcf to about 24 pcf, from about 18 pcf to about 33 pef (about 530 kg ⁇ ), from about 18 pet to about 31 pcf, from about 18 pet to about 30 pcf, from about !
- 31 pcf (about 500 kg/ ' m 3 ), from about 20 pcf to about 30 pcf (about 480 kg/m '' ), from about 20 pcf to about 30 pcf, from about 20 pcf to about 29 pcf (about 460 kg/m ⁇ ), from about 20 pcf to about 28 pcf (about 450 kg/m 3 ), from about 21 pcf (about 340 kg m "5 ) to about 33 pcf, from about 21 pcf to about 32 pc from about 21 pcf to about 33 pcf, from about 21 pcf to about 32 pci, from about.
- FIG, 1 shows a schematic cross-sectional view of a composite gypsum board 10.
- a face paper 12 serves as a top cover sheet.
- the face paper 12 has a first face 14 and a second face 16.
- a concentrated layer 18 is in bonding relation to face paper 12.
- the concentrated layer 18 has a first face 20 and a second face 22.
- a board core 24 has a first face 26 and a second face 28.
- a back paper 30 serves as a bottom cover sheet.
- the back paper 30 has a first face 32 and a second face 34.
- the composite gypsum board 10 is arranged such that face 16 of the face paper 12 faces the first face 20 of the concentrated layer 18 and the second face 22 of the concentrated layer 18 faces the first face 26 of the core 24.
- the second face 28 of the core 24 faces the first face 32 of the back paper 30.
- composite gypsum board in accordance with some embodiments can be constructed and used in an assembly as will be understood in the art.
- the composite boards can be affixed in any suitable arrangement to studs formed of any suitable material such as wood, metal or the like.
- the top or face cover sheet of the board faces out and is generally decorated (e.g., with paint, texture, wallpaper, etc.) in use while the bottom or back cover sheet faces the studs,
- a cavity is normally present behind the stud, facing the back paper, in use.
- insulation material as known in the art optionally can be placed in the cavity, in one embodiment, the assembly comprises two composite boards connected by studs with a cavity there between, facing the bottom cover sheets of the respective boards.
- the board core forms the majority of the volume of the composite gypsum board, In some embodiments, the board core forms at least about 60% of the board volume, e.g., at least about 70% of the board volume, at least about 80% of th board volume, at least about 90% of the board volume, at least about 92%, at least about 95%, at least about 97%, etc. While the concentrated layer has substantial thickness, the board core can be considerably thicker.
- the dry board core can be from about 2.5 times to about 35 times as thick as the dry concentrated layer, e.g., from about 2.5 times to about 30 times, from about 2.5 times to about 25 times, from about 2.5 times to about 20 times, from about 2.5 times to about 1 5 times, from about 2.5 times to about 10 times, from about 2.5 times to about 5 times, from about 2.8 times to about 35 times, from about 2,8 times to about 30 times, from about 2.8 times to about 25 times, from about 2,8 times to about 20 times, from about 2.8 times to about 15 times, from about 2.8 times to about 10 times, from about 2.8 times to about 5 times, from about 5 times to about 35 times, from about 5 times to about 30 times, from about 5 times to about 25 times, from about 5 times to about 20 times, from about 5 times to about 1.5 times, or from about 5 times to about 10 times as thick as the concentrated layer.
- the dry board core can be from about 2.5 times to about 35 times as thick as the dry concentrated layer, e.g., from about 2.5 times to about 30 times, from
- the board core is from about 8 times to about 16 times as thick as the concentrated layer, e.g., from about 8 times to about 12 times, from about 9 times to about 16 times, from about 9 times to about 1 times, from about 9 times to about 12 times, from about 10 times to about 16 times, from about 10 times to about 14 times as thick as the concentrated layer, etc,
- the board core is formed from at least water and stucco.
- stucco can be in the form of calcium sulfate alpha hemihydrate, calcium sulfate beta hemihydrate, and/or calcium sulfate anhydrite.
- the stucco can be fibrous or non-fibrous, in addition to the stucco and water, the board core is formed from an agent that contributes to its lower density, such as a low density filler (e.g., perlite, low density aggregate or the like), or foaming agents.
- a low density filler e.g., perlite, low density aggregate or the like
- foaming agents e.g., perlite, low density aggregate or the like
- foaming agent e.g., perlite, low density aggregate or the like
- the foaming agent comprises a major weight portion of unstable component, and a minor weight portion of stable component (e.g., where unstable and blend of stable/unstable are combined).
- the weight ratio of unstable component to stable component is effective to form an air void distribution within the set gypsum core. See, e.g., U.S. Patents 5,643,510; 6,342,284; and 6,632,550.
- the foaming agent comprises an alkyl sulfate surfactant.
- foaming agents are available and can be used in accordance with embodiments of the disclosure, such as the HYONIC line (e.g., 25AS) of soap products from GEO Specialty Chemicals, Ambler, PA.
- Other commercially available soaps include the Polystep B25, from Stepan Company, Northfleld, Illinois.
- the foaming agents described herein can be used alone or in combination with other foaming agents.
- the foam can be pregenerated and then added to the stucco slurry. The pregeneration can occur by inserting air into the aqueous foaming agent. Methods and apparatus for generating foam are well known. See, e.g., U.S. Patents 4,518,652; 2,080,009; and 2,017,022.
- the foaming agent comprises, consists of, or consists essentially of at least one alkyl sulfate, at least one alkyl ether sulfate, or any combination thereof but is essentially free of an olefin (e.g., olefin sulfate) and/or alkyne, Essentially free of olefin or alkyne means that the foaming agent contains either (i) 0 wt.% based on the weight of stucco, or no olefin and/or alkyne, or (ii) a ineffective or (iii) an immaterial amount of olefin and/or alkyne.
- an olefin e.g., olefin sulfate
- an ineffective amount is an amount below the threshold amount to achieve the intended purpose of using olefin and/or alkyne foaming agent, as one of ordinary skill in the art will appreciate.
- An immaterial amount may be, e.g., below about 0.001 wt.%, such as below about 0.0005 wt.%, below about 0,001 wt.%, below about O.OOOOl wt.%, etc., based on the weight of stucco, as one of ordinary skill in the art will appreciate.
- Some types of unstable soaps are alkyl sulfate surfactants with varying chain length and varying cations.
- Suitable chain lengths can be, for example, Cg-C ⁇ , e.g., Cg-Cjo, or C(o-C; 2.
- Suitable cations include, for example, sodium, ammonium, magnesium, or potassium.
- unstable soaps include, for example, sodium dodecyl sulfate, magnesium dodecyl sulfate, sodium decyl sulfate, ammonium dodecyl sulfate, potassium dodecyl sulfate, potassium decyl sulfate, sodium octyl sulfate, magnesium decyl sulfate, ammonium decyl sulfate, blends thereof, and any combination thereof.
- Some types of stable soaps are a!koxylaied (e.g., ethoxylated) alkyl sulfate surfactants with varying (generally longer) chain length and varying cations.
- Suitable chain lengths can be, for example, CIO-CH, e.g., Cj 2 - Cj.i, or C[o-C i2.
- Suitable cations include, for example, sodium, ammonium, magnesium, or potassium.
- stable soaps include, for example, sodium laureih sulfate, potassium laureih sulfate, magnesium laureih sulfate, ammonium laureth sulfate, blends thereof, and any combination thereof. In some embodiments, any combination of stable and unstable soaps from these lists can be used.
- a first foaming agent which forms a stable foam and a second foaming agent which forms an unstable foam can be combined, hi some embodiments, the first foaming agent is soap, e.g., with an alkoxylated alkyl sulfate soap with an alkyl chain length of 8-12 carhon atoms and an alkoxy (e.g., ethoxy) group chain length of 1-4 units,
- the second foaming agent is optionally an unalkoxylated (e.g., unethoxylated) alkyl sulfate soap with an alkyl chain length of 6-20 carbon atoms, e.g., 6-18 or 6-16 carbon atoms. Regulating the respective amounts of these two soaps, in accordance with some embodiments, is believed to allow for control of the board foam structure until about 100% stable soap
- a fatty alcohol optionally can be included with th foaming agent, e.g., in a pre-mix to prepare the foam. This can result in an improvement in the stability of the foam, thereby allowing better control of foam (air) void size and distribution.
- the fatty alcohol can be any suitable aliphatic fatty alcohol. It will be understood that, as defined herein throughout, "aliphatic" refers to alkyl, alkenyl, or alkynyl, and can be substituted or unsubstituted.
- the fatty alcohol can be a single compound, or can be a combination of two or more compounds.
- the optional fatty alcohol is a C6-C20 fatty alcohol (e.g., ,-
- the C ;o ⁇ C 2 o fatty alcohol comprises a linear or branched C , ⁇ Oji ⁇ carbon chain and at least one hydroxyl group.
- the hydroxyl group can be attached at any suitable position on the carbon chain but is preferably at or near either terminal carbon. In certain embodiments, the hydroxyl group can be attached at the ⁇ -, ⁇ -, or ⁇ -position of the carbon chain, for example, the C -Cao fatty
- alcohol can comprise the following structural subunits: " '-' ⁇ ⁇ ⁇ , OH ?: or
- a desired optional tatty alcohol in accordance with some embodiments are 1 -dodecanol, 1 -undeeanol, 1 -deeanol, 1 -nonanol, 1 -octanol, or any combination thereof.
- the optional foam stabilizing agent comprises the fatty alcohol and is essentially free of fatty acid alkyloamides or carboxylie acid taurides.
- the optional foam stabilizing agent is essentially free of a glycol, although glycols can be included in some embodiments, e.g., to allow for higher surfactant content.
- Essentially free of any of the aforementioned ingredients means that the foam stabilizer contains either (i) 0 wt.% based on the weight of any of these ingredients, or (ii) an ineffective or (iii) an immaterial amount of any of these ingredients.
- an ineffective amount is an amount below the threshold amount to achieve the intended purpose of using any of these ingredients, as one of ordinary skill in the art will appreciate.
- An immaterial amount may be, e.g., below about 0.0001 wt.%, such as below about 0.00005 wt.%, below about 0.00001 wt.%, below about 0.000001 wt.%, etc, based on the weight of stucco, as one of ordinary skill in the art will appreciate.
- Evaporative water voids generally having voids of about 5 pm or less in diameter, also contribute to the total void distribution along with the aforementioned air (foam) voids, in some embodiments, the volume ratio of voids with a pore size greater than about 5 microns to the voids with a pore size of about 5 microns or less, is from about 0.5: 1 to about 9: 1 , such as, for example, from about 0.7: 1 to about 9: 1 , from about 0.8: 1 to about 9: 1 , from about 1 .4: 1 to about 9: 1 , from about 1 .8: 1 to about 9: 1 , from about 2.3 : 1 to about 9: 1 , from about 0.7: 1 to about 6: 1 , from about 1 .4: 1 to
- a void size is calculated from the largest diameter of an individual void in the core.
- the largest diameter is the same as the Feret diameter.
- the largest diameter of each defined void can be obtained from an image of a sample, images can be taken using any suitable technique, such as scanning electron microscopy (SEM), which provides two- dimensional images.
- SEM scanning electron microscopy
- a large number of pore sizes of voids can be measured in an SEM image, such that the randomness of the cross sections (pores) of the voids can provide the average diameter. Taking measurements of voids in multiple images randomly situated throughout the eore of a sample can improve this calculation.
- XMT X-ray CT-scanning analysis
- optical microscopy where light contrasting can be used to assist in determining, e.g., the depth of voids.
- the voids can be measured either manually or by using image analysis software, e.g., ImageJ, developed by N1H.
- image analysis software e.g., ImageJ, developed by N1H.
- manual determination of void, sizes and distribution from the images can be determined by visual observation of dimensions of each void.
- the sample can be obtained by sectioning a gypsum board,
- the foaming agent can be included in the core slurry in any suitable amount, e.g., depending on the desired density.
- the foaming agent is present in the slurry for forming the board core, e.g., in an amount of less than about 0.5% by weight of the stucco such as about 0.01% to about 0.5%, about 0.01 % to about 0.4%, about 0.01 % to about 0.3%, about 0.01 % to about 0.25%, about 0.01 % to about 0.2%, about 0.01 % to about 0, 15% , about 0.01 % to about 0.1 %, about 0.02% to about 0.4%, about 0.02% to about 0.3%, about 0.02% to about 0.2%, etc., all by weight of the stucco.
- the slurry for forming the concentrated layer can be made with less (or no) foam, e.g., in an amount from about 0,0001 % to about 0.05% by weight of the stucco, e.g., from about 0.0001 % to about 0.025% by weight of the stucco, from about 0,0001 % to about 0.02% by weight of the stucco, or from about 0.001 % to about 0.015% by weight of the stucco.
- the fatty alcohol can be present, if included, in the core slurry in any suitable amount, in some embodiments, the fatty alcohol is present in the core slurry in an amount of from about 0.0001 % to about 0.03% by weight of the stucco, e.g., from about 0.0001% to about 0.025% by weight of the stucco, from about 0.0001 % to about 0.02% by weight of the stucco, or from about 0.0001% to about 0,01 % by weight of the stucco. Since the
- concentrated layer slurry can have less or no foam, the fatty alcohol is not required in the concentrated layer, or else can be included in a lower amount, such as from about 0.0001% to about 0.004% by weight of the stucco, e.g., from about 0.00001% to about 0,003% by weight of the stucco, from about 0,00001 % to about 0.00.15% by weight of the stucco, or from about 0.00001 % to about 0.001 % by weight of the stucco.
- Enhancing agent for imparting strength properties as described herein can also optionally be included in the slurry for forming the board core.
- Other ingredients as known in the art can also be included in the board, core slurry, including, for example, accelerators, retarders, etc.
- Accelerator can be in various forms (e.g., wet gypsum accelerator, heat resistant accelerator, and climate stabilized accelerator). See, e.g., U.S. Patents 3,573,947 and 6,409,825.
- the accelerator and/or retarder each can be in the stucco slurry for forming the board core in an amount on a solid basis of, such as, from, about 0% to about 10% by weight of the stucco (e.g., about 0.1 % to about 10%), such as, for example, from about 0% to about 5% by weight of the stucco (e.g., about 0.1 % to about 5%).
- the board core and/or concentrated layer can be further formed from at least one dispersant to enhance fluidity in some embodiments,
- the dispersants may be included in a dry form with other dry ingredients and/or in a liquid form with other liquid ingredients in stucco slurry.
- dispersants include naphthalenesulfonates, such as polynaphthalenesulfonic acid and its salts (polynaphthalenesu!fonates) and derivatives, which are condensation products of naphtha] enesulfonic acids and formaldehyde; as well as polycarboxylate dispersants, such as polycarboxylic ethers, for example, PCE21 1 , PCE1 1 1 , 1641 , 164 I F, or PCE 2641 -Type Dispersants, e.g., MELFLUX 264 IF, MELFLUX 265 I F, M ELF LUX 1641 F, MELFLUX 2500L dispersants (BASF), and COATEX EthacryJ M, available from Coatex, inc.; and/or lignosuifonates or sulfonated lignin.
- naphthalenesulfonates such as polynaphthalenesulfonic acid
- Lignosulfonates are water-soluble anionic polyelectrolyte polymers, byproducts from the production of wood pulp using sulfite pulping.
- a lignin useful in the practice of principles of embodiments of the present disclosure is Marasperse €-21 available from Reed Lignin Inc.
- naphthaienesuifonatc dispersants in some embodiments, they are selected, to have molecular weights from about 3,000 to about 10,000 (e.g., about 8,000 to about 10,000). in some embodiments, higher water demand naphthalenesulfonates can be used, e.g., having molecular weights above 10,000. As another illustration, for PCE21 1 type dispersants, in some embodiments, the molecular weight can be from about 20,000 to about 60,000, which exhibit less retardation than dispersants having molecular weight above 60,000.
- naphthalenesulfonate is D!LOFLO, available from GEO Specialty Chemicals.
- DiLOFLO is a 45% naphthalenesulfonate solution in water, although other aqueous solutions, for example, in the range of about 35% to about 55% by weight solids content, are also readily available.
- Naphthalenesulfonates can be used in dry solid or powder fomi, such as LOMAR D, available from GEO Specialty Chemicals, for example.
- DAXAD available from GEO Specialty Chemicals, Ambler, PA.
- the dispersant can be provided in any suitable amount.
- the dispersant can be present in the concentrated layer slurry in an amount, for example, from about 0.05% to about 0,5%, e.g., about 0.1 % to about 0,2% by weight of the stucco, and can be present in the board core slurry in an amount, for example, from about 0% to about 0.7%, e.g., 0% to about 0.4% by weight of the stucco.
- the board core and/or concentrated laver can be further formed from at least one phosphate-containing compound, if desired, to enhance green strength, dimensional stability, and/or sag resistance.
- phosphate-containing components useful in sorne embodiments include water-soluble components and can be in the form of an ion, a salt, or an acid, namely, condensed phosphoric acids, each of which comprises two or more phosphoric acid units; salts or ions of condensed phosphates, each of which composes two or more phosphate units; and monobasic salts or monovalent ions of orthophosphates as well as water-soluble acyclic polyphosphate salt. See, e.g., U.S. Patents 6,342,284; 6,632,550; 6,815,049; and 6,822,033.
- Phosphate compositions if added in some embodiments can enhance green strength, resistance to permanent deformation (e.g., sag), dimensional stability, etc.
- Green strength refers to the strength of the board while still wet during manufacture. Due to the rigors of the manufacturing process, without sufficient green strength, a board precursor can become damaged on a manufacturing line.
- Tnmetaphosphate compounds can be used, including, for example, sodium trimetaphosphate, potassium trimetaphosphate, lithium trimetaphosphate, and ammonium frimetaphosphate.
- Sodium trimetaphosphate (STMP) is preferred, although other phosphates may be suitable, including for example sodium tetrametaphosphate, sodium
- bexameiaphosphate having from about 6 to about 27 repeating phosphate units and having the molecular formula Na n . ( .2P n 0 3rt ⁇ -i wherein n :::: 6-27, teirapotassium pyrophosphate having the molecular formula K4P2O7, trisodium dipotassium tripolyphosphate having the molecular formula sodium tripolyphosphate having the molecular formula
- trimetaphosphate having the molecular formula AlfPC)?)*, sodium acid pyrophosphate having the molecular formula ammonium polyphosphate having 1 ,000-3,000 repeating phosphate units and having the molecular formula (NH4) ir 3 ⁇ 4P ri Q ii+i wherein n 1,000-3 ,000, or polyphosphorie acid having two or more repeatin phosphoric acid units and having the molecular formula wherein n is two or more.
- the polyphosphate can be present in any suitable amount.
- the polyphosphate can be present in the concentrated layer slurry in an amount, for example, from about 0.1% to about 1 %, e.g., about. 0.2% to about 0.4% by weight of the stucco, and is present in the board core slurry in an amount, for example, from about 0% to about 0.5%, e.g., from about 0% to about 0,2% by weight of the stucco.
- the dispersant and polyphosphate optionally can be in any suitable amount in the core slurry and/or in the concentrated layer slurry, such that in some embodiments, the core slurry contains a higher weight percentage of the dispersant and/or polyphosphate than the concentrated layer slurry. In alternate embodiments, the dispersant and/or polyphosphate are included in higher weight percentage in the concentrated layer slurry than in the core slurry (including core slurries with zero dispersant and/or polyphosphate) (with or without the enhancing additive being more concentrated in the concentrated layer).
- the hoard core can have any suitable density useful in contributing to a desired total composite board density, such as, for example, a core density of from about 16 pcf ⁇ about 260 kg m 3 ) to about 40 pcf e.g., from about 18 pcf to about 40 pcf, 18 pcf to about 38 pcf, 18 pcf to about 36 pcf, 18 pcf to about 32 pcf, 20 pcf io about 40 pel, 20 pcf to about 36 pcf, 20 pcf to about 32 pel ' , 22 pcf to about 40 pcf, 22 pcf to about 36 pcf, 22 pcf to about 32 pcf, 26 pcf to about 40 pcf, 26 pcf to about 40 pcf, 26 pcf to about 36 pcf, or 26 pcf to about 32 pcf.
- the board core has an even lower density, e.g.. about 30 pcf or less, about 29 pcf (about 460 kg nv') or less, about 28 pcf or less, about 27 pcf (about 430 kg ' m 3 ) or less, about 26 pcf or less, etc.
- the core density is from about 12 pcf (about 190 kgbrr') to about 30 pcf, from about 14 pcf (about 220 kg/m J ) to about 30 pcf 16 pcf to about 30 pcf, 16 pcf to about 28 pcf, 16 pcf to about 26 pcf, 16 pcf to about 22 pcf (about 350 k.g/rrf ), 18 pcf to about 30 pcf, 18 pcf to about 28 pcf, 18 pcf to about 26 pcf 18 pcf to about 24 pcf, 20 pcf to about 30 pcf, 20 pcf to about 28 pcf, 20 pcf to about 26 pcf, 20 pcf to about 24 pcf, 22 pcf to about 28 pcf, etc.
- the concentrated layer is "concentrated" in some embodiments because of the presence of an enhancing additive in the concentrated layer slurry in an amount that is more concentrated than the amount by weight, if any, of the same enhancing additive in the board core slurry.
- the concentrated layer has a density that is at least about 1.1 times higher than the density of the board core, and/or has substantial thickness, such as at least about 0.02 inches (about 0,05 cm).
- the concentrated layer is formed from slurry comprising water and eementitioiis material, such as stucco, which hydrates to form a set hydrated material, e.g., continuous crystalline matrix of set gypsum, in the final product, in preferred embodiments, the eementitious material is stucco, and the slurry for forming the concentrated layer is a stucco slurry.
- the slurry for forming the concentrated layer further comprises an enhancing additive in a higher relative weight concentration than the concentration of the enhancing additive in the slurry for forming the board core.
- the slurry for forming the concentrated layer can optionally include foaming agent or other lightweight agent as described herein to produce the desired density for the concentrated layer, If included, in some embodiments the foaming or other lightweight agent will be present in a lower amount in the slurry for forming the concentrated layer, or the foaming agent can be ' ' 'beaten out" to at least some extent to reduce the population of foam voids as known in the art in order to achieve the desired higher density than the density of the board core.
- foaming agent can be ' ' 'beaten out” to at least some extent to reduce the population of foam voids as known in the art in order to achieve the desired higher density than the density of the board core.
- the formation of the concentrated layer to the desired density through an effective (or no) amount of foaming agent or other lightweight agent can be achieved as described herein and through the ordinary skill in the art.
- Other ingredients such as accelerator and retarder can optionally be included in the concentrated layer as desired as described herein.
- Fibers can further be included in the concentrated layer as an optional additive to improve the process of preparing gypsum board.
- the concentrated layer slurry can be applied to the paper, e.g., at a high rate of speed and with the use of a roller or other spreading means, which forms a head of slurry that accumulates upstream of the roller before it is applied evenly to the paper downstream of the roller (and whereby board edges are typically formed around the ends of the roller from the concentrated layer slurry).
- the environment in which the concentrated layer is applied is transient with three-dimensional oscillation, leading to scalloping in the slurry, whereby relatively large ah entrain ents can occur, which can cause a rough, uneven slurry that can lead to defects in the board if not addressed.
- defects can include the formation of large air pockets which are referred to as voids or blisters, as well as del animation of the paper, soft and/or hard edges, etc.
- the fibers advantageously improve the rheology of the slurry in order to ensure a smoother flow. It is also believed that the fibers improve the hydrodynamic properties of the slurry such that viscosity, rheology and the balance of ulcererpartiele forces of the slurry are improved, the slurry is more evenly distributed on the application roller, and undesirable entrained air is more easily released from the slurry.
- the fibers can he in the form of any suitable fibers.
- the fibers can be in the form of one or more of glass fibers, mineral fibers, carbon fibers, paper fibers, and mixtures of such fibers, as well as other comparable fibers providing comparable benefits to the process and/or end product.
- glass fibers are
- Glass fibers are preferred because they do not absorb water.
- sizing agents can allow tor sizing of individual fibers in order to, e.g., change surface coating and properties and typically be in the form of one or more of organofunctionalized silanes, forming agents, surfactants, defoamers, lubricants and/or stabilizers.
- organofunctionalized silanes forming agents, surfactants, defoamers, lubricants and/or stabilizers.
- the precise selection of each ingredient can vary depending on fiber properties and the desired application.
- the silanes can be, e.g.. amino based, such as for, example,
- aramopropyltriethoxysilane or aminoethylaminopropyltrimethoxysiiane vinyl based such as for example, vinyltrimethoxysilane or vinyltriacetoxysiiane, alkyl based such as
- methyltrimethoxysilane or memyltriethoxysilane or any combination thereof.
- Forming agents are often polymers and can be hydrophobic to provide desired wetting characteristics and protection from fiber-to-fiber damage
- live forming agents can be in the form of, for example, polyurethanes, polyvinyl acetates, polyesters, polyalkenes and epoxies.
- Cationic lubricants can optionally be added and can be in the form of aliphatic ethanolamides such as stearic efhanol amide, or polyethyleneimine poiyamides,
- Surfactants can optionally be included to emulsify the forming agent, e.g., when the forming agent is hydrophobic.
- the surfactant if included is nonionie or slightly cationic, and can be in the form of an amide or other suitable form, e.g., polyoxyethylene glycol alkyl esters, copolymers of polyethylene glycol and polypropylene glycol, cocamide monoethanolarnme, or any combination thereof.
- Defoarners can provide benefit because they control foam formation with glass fiber, and any suitable defoamer can be used.
- suitable defoarners can be siloxane based, oil based or polymer based, such as, but not limited to mineral oil, waxes, ethylene bis stearamide, silicone oil, polyethylene glycol and polypropylene glycol copolymers based defoarners, or any combination thereof.
- Stabilizers provide the benefit of stabilizing the sizing fonmilation and any suitable stabilizer can be used.
- additive such as lubricant provides a positive surface charge which is believed to further improve slurry flow.
- the sizing agent can be provided in any suitable amount in the slurry for forming the concentrated layer.
- the sizing agent can be provided in an amount of from about 0.02 wt.% to about 2 wt.% of the fibers, such as from about 0.05 wt.,% to about I wt.%, or from about 0.1 wt.% to about 1.5 wt.% of the fibers.
- the concentrated layer and/or board core in the board product can contain the recited ingredient in an amount within the recited ranges.
- the fibers e.g., glass fiber
- the fibers can have any suitable length.
- the fibers can have an average length of from about 0.125 inch (about 0.32 cm) to about 1 mch (about 2,54 cm), such as, for example, from about 0, 125 inch to about 0.75 inch (about 1 .9 cm), from about 0.125 inch to about 0.5 inch (about 1 .3 cm), from about 0.125 inch to about 0.375 inch (about 1 em), from about 0.125 inch to about 0.25 inch (about 0.6 cm), from about 0.25 inch to about 3 inch, from about 0.25 inch to about 0.75 inch, from about 0.25 inch to about 0,5 inch, from about 0.25 inch to about 0.375 inch, from about 0.375 inch to about I inch, from about 0.375 inch to about 0.75 inch, from about 0.375 inch to about 0.5 inch, from about 0. 5 inch to about 1 inch, from about 0.5 inch to about 0.75 inch, or from about 0.75 inch to about 1 inch.
- the fibers can have any suitable average diameter.
- the fibers can have an average diameter of from about 5 microns to about 20 microns, from about 10 microns to about 15 microns, from about 10 microns to about 20 microns, from about 8 microns to about 18 microns, from about 5 microns to about 25 microns, from about 9 microns to about 20 microns, from about 10 microns to about 18 microns, from about 7 microns to about 18 microns, from about 10 microns to about 25 microns, a diameter of about 1 1 to about 17 microns, or a diameter of from about 15 microns to about 17 microns,
- such glass fibers can have an average length of about 0.5 to about 0.675 inches (about 1.7 cm) and a diameter of about 13 to about 16 microns, an average length of about 0.5 to about 0.75 inches and a diameter of about 11 to about 17 microns, or an average fiber length of 0.5 inch and an average diameter of from about 1 5,24 microns to about 16.51 microns.
- the aspect ratio of the fibers refers to the length divided by the diameter and in practice is believed to influence the slurry flow characteristics. To make the units consistent, the length in inches can be converted into microns such that the values are unitless. n some embodiments, the preferred aspect ratio is from about 200 to about 2000, such as from about 400 to about 1300, e.g., from about 800 to about 1500, from about 250 to about 1000, from about 500 to about 1500, or from about 700 to about 1 600, from about 800 to about 1400.
- fibers such as glass fibers
- the slurry for forming the concentrated layer in any suitable amount, such as, from about 0.1% to about 3%, e.g., from about 0.13% to about 2,5%, or from about 0.5% to about 1 % by weight of the stucco, and is present in the board core in any suitable amount, such as from about 0% to about 1 %, e.g., from 0% to about 0.5% by weight of the stucco, if desired, the fiber (and the aforementioned associated additives such as sizing agent, etc) can also be included in the core in any suitable amount such as these enumerated weight percentages.
- the concentrated layer desirably has substantial thickness.
- the dry concentrated layer has a substantial thickness of at least about 0.02 inches (about 0.05 cm), such as from about 0.02 inches to about 0.2 inches (about 0.5 cm).
- the concentrated layer has a substantial thickness with a minimum thickness of at least about 0.025 inches (about 0,06 cm), at least about 0.03 inches (about 0.075 cm), at least about 0.035 inches (about 0.09 cm), at least about 0.04 inches (about 0,1 cm), at least about 0.045 inches (about 0.1 1 cm), at least about 0.05 inches (about 0.13 cm), at least about 0.055 inches (about 0.14 cm), at least about 0.06 inches (about 0.15 cm), at least about 0.065 inches (about 0.17 cm), at least about 0.07 inches (about 0.18 cm), at least about 0.075 inches (about 0.19 cm), at least about 0.08 inches (about 0.2 cm), at least about 0.085 inches (about 0.22 cm), at least about 0.09 inches (about 0.).
- the dry concentrated layer can have a thickness from about 0,02 inches to about 0.175 inches, e.g., from about 0.02 inches to about 0.1 5 inches, from about 0,02 inches to about 0, 12 inches, from about 0.02 inches to about 0.1 inches, from about 0.02 inches to about 0.08 inches, from abou 0.02 inches to about 0,055 inches, from about 0.02 inches to about 0.05 inches, from about 0.02 inches to about 0.04 inches, front about 0.02 inches to about 0,03 inches, from about 0.03 inches to about 0.2 inches, from about 0.03 inches to about 0.175 inches, from about 0.03 inches to about 0.1 5 inches, from about 0,03 inches to about 0, 12 inches, from about 0.03 inches to about 0.1 inches, from about 0.03 inches to about 0.08 inches, from about 0.03 inches to about 0.055 inches, from about 0.03 inches to about 0.05 inches, from about 0.04 inches to about 0.2 iiiches, from about 0.04 inches to about 0.175 inches, from
- the concentrated layer preferably has a higher dry density and/or dry strength than the density of the board core.
- the concentrated layer has a density that is at least about 1 , 1 times greater than the density of the board core, e.g., at least about 1.2 times greater, at least about 1.3 times greater, at least about 1.4 times greater, at least about 1.5 times greater, at least about 1 .6 times greater, at least, about 1.7 times greater, at least about 1.8 times greater, at least about 1.9 times greater, at least about 2 times greater, etc, wherein each of these ranges has a suitable upper limit, as mathematically appropriate, such as, for example, about 3 times greater, about 2.9 times greater, about 2,8 times greater, abou 2.7 times greater, about 2,6 times greater, about 2,5 times greater, about 2.4 times greater, about 2.3 times greater, about 2.2 times greater, about 2,1 times greater, about 2 times greater, about 1 ,9 times greater, about 1 .8 times greater, about 1 .7
- the concentrated layer can have a dry density that is from about 1.1 to about 3 times the density of the board core, e.g., from about 1.1 to about 3 times, from about 1.1 to about 2.7 times, from about 1 .1 to about 2.5 times, from about 1.1 to about 2.2 times, from about 1.1 to about 2 times, from about 1.1 to about 1.7 times, from about 1 .1 to about 1.5 times, from about 1 .1 to about 1 ,4 times, from about 1 ,1 to about 1.3 times, from about 1 ,2 to about 3 times, from about 1 .2 to about 2.5 times, from about 1.2 to about 2.2 times, from about 1.2 to about 2 times, from about 1 ,2 to about 1 ,7 times, from about 1.2 to about 1.5 times, from about 1 .2 to about 1 .4 times, from about 1.2 to about 1 ,3 times, from about 1.3 to about 3 times, from about 1 ,3 to about 2.5 times, from about 1.3 to about 2 times, from about 1.3 to about 3
- the composite gypsum board can be designed to demonstrate any suitable dry- density differential between the concentrated layer and the board core, In some
- the density differential between the concentrated layer and the board core can be at least about 8 pcf (about 1 30 kg/m 3 ).
- the dry density differential between the concentrated layer and the bonding layer can be at least about 10 pci " , at least about 12 pcf, at least about 14 pcf, at least about 16 pcf, at least about 1 8 pcf, at least about 20 pcf, etc.
- the density differential between the concentrated layer and the board core is from about 8 pcf to about 50 pcf, such as about 8 pcf to about 45 pcf (about 720 kg/m 3 ), about 8 pcf to about 40 pcf, about 8 pcf to about 35 pcf, 8 pcf to about 30 pcf, about 8 pcf to about 25 pcf (about 400 kg m"), about 8 pcf to about 20 pcf, about 8 pcf to about 15 pcf (about 240 kg/m 3 ), about 8 pcf to about 12 pcf, about 10 pcf (about 160 kg-'m 3 ) to about 50 pcf, about 10 pcf to about 45 pcf, about 10 pcf to about 40 pcf, about 1 0 pcf to about 35 pcf, about 10 pcf to about 30 pcf, about 10 pcf to
- the concentrated layer can have any suitable dry density to fit within the desired parameters of embodiments described herein.
- the concentrated layer has a dry density of from about 28 pcf to about 70 pcf (about 1 120 kg/m 3 ), such as from about 28 pcf to about 65 pcf (about 1040 kg m J ), from about 28 pcf to about 60 pcf (about 960 kg/m J ), from about 28 pcf to about 55 pcf (about 880 kg/rrf ), from about.
- 28 pcf to about 50 pcf from about 28 pcf to about 45 pcf, from about 28 pcf to about 40 pcf, from about 28 pcf to about 35 pcf, from about 34 pcf to about 70 pcf, from about 34 pcf to about 65 pcf, from about 34 pcf to about 60 pcf, fronvabout 34 pcf to about 55 pcf from about 34 pcf to about 50 pcf.
- the concentrated layer generally has a dry stiffness value that is greater than the dry stiffness value of the board core.
- Young's modulus of elasticity can be used as a measure of dry stiffness herein, In some embodiments, the dry concentrated layer has a Young's modulus that is at least about 1.5 times as high, as the Young's modulus of the board core, e.g., 2 times as high as the Young's modulus of the board core, such as.
- the concentrated layer has a stiffness value thai, is closer to a stiffness value of the top and/or bottom cover sheet than a stiffness of the board core, when each stiffness value is measured according to Young's modulus.
- the concentrated layer has a stiffness value according to Young's modulus that is from about 0.3 to about 0.5 of the Young ' s modulus for at least one of the cover sheets,
- cover sheets can be in any suitable form. It will be understood that, with respect to cover sheets, the terms “face” and “top “ ' sheets are used interchangeably herein, while the terms “back” and '”bottom” are likewise used interchangeably herein.
- the cover sheets may comprise cellulosic fibers, glass fibers, ceramic fibers, mineral wool, or a combination of the aforementioned materials.
- One or both of the sheets may comprise individual sheets or multiple sheets.
- the cover sheets comprise a cellulosic fiber.
- paper sheet such as Manila paper or kraft paper, can be used as the back sheet.
- Useful cover sheet paper includes Manila 7-piy and News-Line 3 ply, or 7 ply available from United States Gypsum Corporation, Chicago, IL,; Grey-Back 3-ply and Manila Ivory 3-ply, available from International Paper, Newport, IN: and Manila heavy paper and Mil Manila HT (high tensile) paper, available from United States Gypsum Corporation, Chicago, IL.
- An exemplary cover sheet paper is 5-pIy Newsline.
- the back sheet can optionally define perforations, e.g., pin-holes, therein. Such perforations assist with drying in a kiln to provide an outlet for any steam formed during the heating process.
- the paper can comprise any other material or combination of materials.
- one or both sheets, particularly the face (top) sheet can include polyvinyl alcohol, boric acid, or polyphosphate as described herein (e.g.. sodium trimetaphosphate) to enhance the strength of the paper.
- the paper can be contacted with a solution of one or more of polyvinyl alcohol, boric acid, and/or polyphosphate so that the paper is at least partially wetted.
- the paper can be at least partially saturated in some embodiments.
- the polyvinyl alcohol, boric acid and/or boric acid can penetrate the fibers in the paper in some embodiments.
- the solution of polyvinyl alcohol, boric acid, and/or polyphosphate can be in any suitable amount and can be applied in any suitable manner as will be appreciated in the art.
- the solution can be in the form of from about 1% to about 5% solids by weight in water of each ingredient present between the polyvinyl alcohol, the boric acid and/or polyphosphate, which can be added in one solution or if desired in multiple solutions.
- one or both sheets can comprise glass fibers, ceramic fibers, mineral wool, or a combination of the aforementioned materials.
- One or both sheets in accordance with the present disclosure can be generally hydrophilic, meaning that the sheet is at least partially capable of adsorbing water molecules onto the surface of the sheet and/or absorbing water molecules into the sheet.
- the cover sheets can be "substantially free" of glass fibers ceramic fibers, mineral wool, or a mixture thereof, which means that the cover sheets contain either (i) 0 wt.% based on the weight of the sheet, or no such glass fibers ceramic fibers, mineral wool, or a mixture thereof, or (ii) an ineffective or (iii) an immaterial amount of glass fibers ceramic fibers, mineral wool, or a mixt ure thereof.
- An example of an ineffective amount is an amount below the threshold amount to achieve the intended purpose of using glass fibers ceramic fibers, mineral wool, or a mixture thereof, as one of ordinary skill in the art will appreciate.
- An immaterial amount may be, e.g., below about 5 wt.%, such as below about 2 wt.%. below about 1 wt.%, below about 0.5 wt.%, below about 0.2 wt.%, below about 0. 1 wt,%, or below about 0.01 wt.% based on the weight stucco as one of ordinary skill in the art will appreciate.
- such ingredients can be included in the cover sheets.
- the thermal conductivity of the top and/or bottom sheet is less than about 0, 1 w/(m.k.).
- the thermal conductivity of the top and/or bottom sheet is less than about 0.05 w (m.k.).
- one or both cover sheets can optionally include any suitable amount of inorganic compound or mixture of inorganic compo unds that adequately imparts greater fire endurance where such properties are sought.
- suitable inorganic compounds include aluminum trihydrate and magnesium hydroxide.
- the cover sheets can comprise any inorganic compound or mixture of inorganic- compounds with high crystallized water content, or any compound that releases water upon heating, hi some embodiments, the amount of inorganic compound or the total mixture of inorganic compounds in the sheet ranges from about 0.1 % to about 30% by weight of the sheet.
- the inorganic compound or inorganic compounds used in the sheet may be of any suitable particle size or suitable particle size distribution.
- Aluminum trihydrate also known as alumina trihydrate and hydratcd alumina, can increase fire resistance due to its crystallized or compound water content.
- ATH can be added in an amount from about 5% to about 30% by total weight of the sheet.
- ATH typically is very stable at room temperature. Above temperatures between about 1 80 °C and 205 °C, ATH typically undergoes an endotherrnic decomposition releasing water vapor.
- the heat of decomposition for such ATH additives is greater than about 1 00 Joule/grarn, and in one embodiment is about 1 170 Joule/ gram.
- the ATH additive decomposes to release approximately 35% of the water of crystallization as water vapor when heated above 205 °C in accordance with the fol lowing equation: AUQH) - ⁇ Al- 0 3 + 3H 2 0.
- a cover sheet comprising inorganic particles of high water content, such as ATH can increase fire endurance of the composite board.
- the inorganic compound or mixture of compounds is incorporated into the sheet in some embodiments.
- a cover sheer such as paper comprising ATH can be prepared by first diluting cellulosic fiber in water at about 1% consistency, then mixing with ATH particles at a predetermined ratio. The mixture can be poured into a mold, the bottom of which can have a wire mesh to drain off water, After draining, fiber and ATH particles are retained on the wire.
- the wet sheet can he transferred to a blotter paper and dried at about 200-360°F.
- ATH particles of less than about 20 ⁇ are preferred, but any suitable source or grade of ATH can be used.
- ATH can be obtained from commercial suppliers such as Huber under the brand names SB 432 (10 prn) or Hydra! ® 710 ( ⁇ ⁇ ).
- the cover sheet may comprise magnesium hydroxide.
- the magnesium hydroxide additive preferably has a heat of
- any suitable magnesium hydroxide can he used, such as that commercially available from suppliers, including Akrochem Corp. of Akron, Ohio.
- the cover sheets can be "substantially free" of inorganic compounds such as ATH, magnesium hydroxide, or a mixture thereof, which means that the cover sheets contain either (i) 0 wt.% based on the weight of the sheet, or no such inorganic compounds such as ATH, magnesium hydroxide, or a mixture thereof, or (it) an ineffective or (hi) an immaterial amount of inorganic compounds such as ATH, magnesium hydroxide, or a mixture thereof,
- An example of an ineffective amount is an amount below the threshold amount to achieve the intended purpose of using inorganic compounds such as ATH, magnesium hydroxide, or a mixture thereof, as one of ordinary skill m the art will appreciate.
- An immaterial amount may be, e.g., below about 5 wt.%, such as below about 2 wt.%, below about 1 wt.%, below about 0.5 wt.%, below about 0.1 wt.%, below about 0.05 wt.%, below about 0.01 wt.%, etc.
- cover sheets can also have any suitable total thickness, in some embodiments
- At least one of the cover sheets has a relatively high thickness, e.g., a thickness of at least about 0.014 inches. In some embodiments, it is preferred that there is an even higher thickness, e.g., at least about 0.0 i 5 inches, at least about 0.016 inches, at least about 0.017 inches, at least about 0.018 inches, at least about 0.019 inches, at least about 0.020 inches, at least about 0,021 inches, at least about 0.022 inches, or at least about 0.023 inches.
- any suitable upper limit for these ranges can be adopted, e.g., an upper end of the range of about 0.030 inches, about 0.027 inches, about 0.025 inches, about 0.024 inches, about 0.023 inches, about 0.022 inches, about 0.021 inches, about 0,020 inches, about 0.039 inches, about 0.018 inches, etc.
- the total sheet thickness refers to the sum of the thickness of each sheet attached to the gypsum board.
- the cover sheets can have any suitable density.
- at least one of the cover sheets e.g., the top (face) cover sheet, has a density that is equal to or greater than the density of the concentrated layer.
- at least one or both of the cover sheets has a density of at least about 36 pcf, e.g., from about 36 pcf to about 46 pcf, such as from about 36 pcf to about 44 pcf, from about 36 pcf to about 42 pcf, from about 36 pcf to about 40 pcf, from about 38 pcf to about 46 pcf, from about 38 pcf to about 44 pcf. from about 38 pcf to about 42 pcf, etc.
- the cover sheet can have any suitable weight.
- any suitable weight for example, in some embodiments, in some combination
- lower basis weight cover sheets e.g., formed from paper
- lower basis weight cover sheets such as, for example, at least about 33 Ibs/MSF (about 160 g m'), e.g., from about 33 Ibs/MSF to about
- Ibs/MSF about 320 g/m 2
- Ibs/MSF (about 270 g/m 2 ), from about 33 Ibs/MSF to about 50 Ibs/MSF ' (about 240 g m 2 ), from about 33 Ibs/MSF to about 45 Ibs/MSF (abou 220 g-'ra”), etc. or less than about
- one or both cover sheets has a basis weight from about 38 Ibs/MSF (about 190 g/m 4 ') to about 65 Ibs/MSF, from about 38 Ibs/MSF to about 60 Ibs/MSF, from about 38 Ibs/MSF to about 58 Ibs/MSF, from about 38 Ibs/MSF to about 55 Ibs/MSF, from about 38 Ibs/MSF to about 50 Ibs/MSF, or from about 38 lbs/MSI to about 5 Ibs/MSF.
- one or both of the cover sheets can have a basis weight of, for example, at least about 45 Ibs/MSF (e.g., from about 45 Ibs/MSF to about 65 Ibs/MSF, from about 45 Ibs/MSF to about 60 Ibs/MSF, from about 45 Ibs/MSF to about 55 Ibs/MSF, from about ' 50 Ibs/MSF to about 65 Ibs/MSF, from about 50 Ibs/MSF to about 60 Ibs/MSF, etc.).
- at least about 45 Ibs/MSF e.g., from about 45 Ibs/MSF to about 65 Ibs/MSF, from about 45 Ibs/MSF to about 60 Ibs/MSF, from about 45 Ibs/MSF to about 55 Ibs/MSF, from about ' 50 Ibs/MSF to about 65 Ibs/MSF, from about 50 Ibs/MSF to about 60 Ibs/MSF, etc.
- one cover sheet e.g., the "face" paper side when installed
- the other cover sheet e.g., the ''back" sheet when the board is installed
- weight basis e.g., weight basis of less than about 45 Ibs/MSF, e.g., from about 33 Ibs/MSF to about 45 Ibs/MSF or from about 33 ibs/MSF to about 40 Ibs/MSF).
- the enhancing additive provides desired strength properties.
- the enhancing additive is more concentrated in the concentrated layer slurry than in the board core slurry (and/or the resulting layers in the board product), as discussed herein.
- suitable enhancing additives help provide strength, such as starch, polyvinyl alcohol, boric acid, gypsum-cement, nano-cellulose, micro-cellulose, or any combination thereof
- starch polyvinyl alcohol, boric acid, gypsum-cement, nano-cellulose, micro-cellulose, or any combination thereof
- an enhancing additive may comprise one or more of starch, polyvinyl alcohol, boric acid, gypsum-cement, nano-cellulose, and/or micro-cellulose.
- the enhancing additive comprises an ingredient, such as starch, that is effective to increase the dry strength of the composite gypsum board relative to the sirength of the composite board without the ingredient such as starch (e.g., via increased compressive strength, nail pull resistance, fiexural strength, core hardness, or other strength parameter).
- starch any suitable strength enhancing starch can be used, including hydroxyalkylated starches such as hydroxyethy!ated or hydroxypropylaied starch, or a combination thereof, uncooked starches, or pregela inized starches, which are generally preferred over acid-modifying migrating starches which generally provide paper-core bond enhancement but not core strength enhancement.
- the acid-modifying migrating starch can be included with the enhancing additive in some embodiments.
- the starch can be cooked or uncooked.
- Uncooked starches are characterized as being cold water insoluble and having a semi-crystalline structure.
- uncooked starches are obtained by wet milling and are not modified by heating wet starch as in the case of cooked starches.
- Cooked starches are characterized by being cold water soluble and having a non-crystalline structure.
- Cooked starches are prepared by heating wet starch, and can be prepared, e.g., by extrusion techniques. See, e.g., co-pending U.S. patent applications 14/494,547; 14/044,582; and 13/835,002, which extrusion techniques are incorporated by reference.
- Cooked starches are sometimes referred to as pregeSatinized starches, because the crystalline structure of the starch granules melts, and results in starch geiatinization, which is characterized by the disappearance of the birefringence under a microscope with a polarized light.
- Preferred starches, whether cooked or uncooked are different than acid-modified migratory starches which do not confer the same strength properties and are used in the art for paper-core bond enhancement as they migrate to the paper-core interface due to their smaller chain lengths.
- the acid-modified migratory starches have minimal molecular weight, typically below about 6,000 Daltons. in some embodiments, preferred starches in accordance with embodiments of the disclosure have higher molecular weights, e.g.. at least about 30,000 Daltons.
- the starch added to the concentrated layer slurry can have a molecular weight of from about 30,000 Daltons to about 150.000.000 Dalions, e.g., from about 30,000 Daltons to about 1 50,000,000 Daltons, from about 30,000 Daltons to about 100,000,000 Daltons, from about 30,000 Daltons to about 50,000,000 Daltons, from about 30,000 Daltons to about 10,000,000 Daitons, from about 30,000 Daitons to about 5,000,000 Daltons, from about 30,000 Daltons to about 1 ,000,000 Daltons, from about 30,000 Daltons to about 500,000 Daltons, from about 30,000 Dalions to about 100,000 Daltons, from about 50,000 Daltons to about 150,000,000 Daltons, from about 50,000 Daltons to about 100,000,000 Daltons, from about 50,000 Daitons to about 50,000,000 Dalions, from about 50,000 Daltons to about 10,000,000 Daltons, from about 50,000 Daltons to about 5,000,000 Daltons, from about 50,000 Daltons to about 1 ,000,000 Daltons, from about 50,000 Daltons to about 500,000 Daltons, from about 30,000 Dalions to about 100,000 Daltons, from about
- Uncooked starches include having low viscosity in cold water (i.e., at a temperature of 77 ° ⁇ (25 °C)), while properties of pregelatinized starches include having instant high viscosity in cold water.
- Uncooked starches tend to have a viscosity of about 10 eentipoise or less in cold water (e.g., from about 1 centipoise to about 1 0 centipoise, such as from about 3 centipoise to about 7 centipoise), as measured according to a modified rapid viscosity analyzer method.
- the rapid viscosity analyzer method is explained in the text, Deffenbangh, L.B.
- the pregelatinized starches have "instant" high viscosity in cold water because the starch tends to instantly dissolve in water.
- Cooked or pregelatinized starches tend to have a cold water viscosity of at least about 100 centipoise (e.g., from about 50 ceniipoise to about ].
- ()()() centipoise such as from about 350 ceniipoise to about 1000 centipoise) as measured according to the modified rapid viscosity analyzer method.
- uncooked starches are selected because they are easy to mix with water. This is because of their low viscosity in water.
- Pregelatinized starches can sometimes cause '"fish eye," which is a condition that is characterized by one or more large lumps that form in the water soiution during mixing. While not wishing to be bound by any particular theory, during the mixing process, the large lumps are believed to be caused by fast water absorption of the starch, forming a viscous film on the surface of the lump, which prevents water penetration of the lump.
- Uncooked starches are believed to avoid the fish eye condition because of their cold water insolubility, which results in the separation of starch granules.
- pregelatinized starches can be used in accordance with embodiments of the disclosure inasmuch as they are desirable for the exposure of functional groups which allows for hydrogen bonding between starch and gypsum crystals.
- suitable uncooked starches include, but are not limited to. one or more of native cereal starches, native root starches, native tuber starches, and/or chemically modified starches, with specific representative examples including, e.g., corn starch (normal, waxy, and/or high-amylose), A type wheat starch, B type wheat starch, pea starch, acid modified starches with a molecular weight of at least about 30,000 Daltons, substituted starches having substituted groups (such as acetate, phosphate, hydroxyethyl, hydrox propyl) on starch hydroxyl groups, or any combination thereof, In some embodiments, the uncooked starch excludes pea starch.
- native cereal starches native root starches, native tuber starches, and/or chemically modified starches
- specific representative examples including, e.g., corn starch (normal, waxy, and/or high-amylose), A type wheat starch, B type wheat starch, pea starch, acid modified starches with a molecular
- any suitable pregelatinized starch can be included in the enhancing additive, as described m US 2014/01 13124 Al and US 2015/0010767-A1 , which include methods of preparation thereof and desired viscosity ranges described therein. If included, the pregelatinized starch can exhibit any suitable viscosity. In some embodiments, the pregelatinized starch is a mid-range viscosity starch as measured according to the VMA method as known in the art and as set forth in, e.g., US 2014/01 13124 AL which VMA method is hereby incorporated by reference,
- Desirable pregelatinized starches in accordance with some embodiments can have a mid-range viscosity, e.g., measured in a 15 wt.% solution of starch in water, of from about 20 centipoise to about 700 centipoise, e.g., from about from about 20 centipoise to about 600 centipoise, from about 20 centipoise to about 500 centipoise, from about 20 centipoise to about 400 centipoise, from about 20 centipoise to about 300 centipoise, " from about 20 eentipoise to about 200 centipoise, from about 20 centipoise to about 100 centipoise, from about 30 centipoise to about 700 eentipoise, from about 30 centipoise to about 600 centipoise, from about 30 centipoise to about 500 centipois
- the pregelatinized starch can he prepared as an extruded starch, e.g., where starch is prepared by pregelai.inizat.ion and acid- modification in one step in an extruder as described in US 2015/0010767-A1 , which extrusion method is hereby incorporated by reference.
- any suitable extruder can be used, such as a single-screw extruder (e.g., the Advantage 50 available from American Extrusion international, located in South Beloit, ⁇ ,) or a twin-screw extruder (e.g., the Wenger TX52 available from Wenger located in Sahetha, KS).
- a precursor to pregelatinized starch i.e., non-pregelatinized starch
- an acid in the form of a weak acid that substantially avoids chelating calcium ions, and/or a strong acid in a small amount
- water are mixed and fed into the extruder.
- additional water may be added to the extruder, in some embodiments, for example, aluminum sulfate (alum) is an appropriate weak acid to use in preparing the wet starch since it substantially avoids chelating calcium ions.
- weak acid is included in an amount of from about 0,5 wt.% to about 5 wt.% based on the weight of the starch.
- the amount of strong acid is relatively small, such as about 0.05 wt.% or less by weight of the starch, e.g., from about 0.0001 wt.% to about 0.05 wt.%.
- the amounts of strong acid used in accordance with some embodiments of the disclosure are considerably smaller than what were included in conventional systems which used, e.g., at least about 2 g of sulfuric acid for 35 g of starch, in some embodiments, the strong acid in small amounts as described above can be used in combination with a weak acid that does not chelate calcium ions, such as alum, as described herein.
- the wet starch can be pregelatinized and acid-modified in an extruder having a die at a temperature of from about 150°C (about 300°F) to about 21 0°C (about 410°F). Pressure inside the extruder is determined by the raw material being extruded, moisture content, die temperature, and screw speed, which will be recognized by one of ordinary skill in the art.
- the pressure in the extruder can be at least about 2,000 psi (about 13,800 kPa), e.g., from about 2,000 psi to about 5.000 psi (34,500 kPa).
- the conditions in the extruder because of the mechanical energy, will also cause the starch molecules to degrade, which partially produces the same effect of acid-modification. It is believed that because the conditions in an extruder (e.g., high reaction temperature and high pressure) in accordance with some embodiments facilitate this chemical reaction, a weak acid and or low amounts of a strong acid can be used.
- Cold water solubility relates to a pregelatinized starch having any amount of solubility in water at room temperature (about 25°C).
- the pregelatinized starch having any amount of solubility in water at room temperature (about 25°C).
- pregelatinized starch is partially hydrolyzed and can have, desired cold water solubility of from about 70% to about 100%, from about 75% to about 100%, from about 80% to about 100%, from about 85% to about 100%, from about 90% to about 100%, from about 95% to about 100%, from about 70% to about 99%, etc, from about 75% to about. 99%, from about 80% to about 99%, from about. 85% to about. 99%, from about 90% to about 99%, from about 95% to about 99%.
- the pregelatinized starch has a cold water viscosity (10% solids, 25°C) of from about 10 BU to about 120 BU, measured according to the Brabender method where viscosity is measured using a C.W.
- Brabender Viscograph e.g., a Viscograph-E thai uses reaction torque for dynamic measurement.
- the cold water viscosity can be, e.g., from about 20 BU to about 1 10 BU, from about 30 BU to about 100 BU, from about 40 BU to about 90 BU. from about 50 BU to about 80 BU, or from about 60 BU to about 70 BU.
- the Brabender units are measured using a sample cup size of 16 ft. oz (about 500 cc), with a 700 cmg cartridge at an RPM of 75.
- Brabender units can be converted to other viscosity measurements, such as centi poises (e.g., cP ::: BLJ X 2,1 , when the measuring cartridge is 700 cmg) or Krebs units.
- the starch has a cold water viscosity of al.0% slurry of the starch in water when measured at 25 °C of from about 60 cP to about 160 cP, as measured with a Brookfield viscometer with #2 spindle and at a rotation, speed of 30 rpm.
- the cold water viscosity of a 10% slurry of the starch in water when measured at 25 °C can be from about 60 cP to about 150 cP, from about 60 cP to about 120 cP, from about 60 cP to about 100 cP, from about 70 cP to about 150 cP, from about 70 cP to about 120 cP, from about 70 cP to about 100 cP, from about 80 cP to about 150 cP from about 80 cP to about 120 cP, from about 80 cP to about 100 cP, from about 90 cP to about 150 cP, from about 90 cP to about 120 cP, from about 100 cP to about 150 cP, or from about 100 cP to about 120 cP.
- the starch of any type described herein as enhancing additive can be present in any suitable amount. Irs some embodiments, the starch is present in the
- concentrated layer in an amount from about 5% to about 40%, by weight of the stucco, e.g., from about 5% to about 35% by weight, of the stucco, from about 5% to about 30% by weight of the stucco, from about 5% to about 25%, from about 5% to about 20%, from about 5% to about 15%, from about 5% to about 10%, from about 1 0% to about 30%, from about 10% to about 2.5%, from about 1 % to about 20%, from about 10% to about 15%, etc.
- the stucco e.g., from about 5% to about 35% by weight, of the stucco, from about 5% to about 30% by weight of the stucco, from about 5% to about 25%, from about 5% to about 20%, from about 5% to about 15%, from about 5% to about 10%, from about 1 0% to about 30%, from about 10% to about 2.5%, from about 1 % to about 20%, from about 10% to about 15%, etc.
- the starch can be present in the board core in an amount, from about 0% to about 4% by weight of the stucco, e.g., from about 0.1 % to about 4% by weight of the stucco, from about 0.1 % to about 3% by weight of the stucco, from about 0.1% to about 2% by weight of the stucco, from about 0.1% to about 1 % by weight of the stucco, from about 1 % to about 4% by weight of the stucco, from about 1 % to about 3% by weight of the stucco, from about 1 % to about 2% by weight of the stucco, etc.
- the enhancing additive can include polyvinyl alcohol and/or boric acid to enhance strength.
- polyvinyl alcohol, boric acid, and starch are all present. While not wishing to be bound by theory, it is believed that the boric acid acts as a cross-linker for the polyvinyl alcohol and starch to further enhance st arch.
- the concentration of polyvinyl alcohol and/or boric acid in the concentrated layer is believed to positively impact strength in the face paper; diis can be compounded by penetrating the face paper with polyvinyl alcohol and/or boric acid as described herein.
- the polyvinyl alcohol and boric acid can be present in any suitable amounts.
- the polyvinyl alcohol can be present in the concentrated layer in an amount from about 1 % to about 5% by weight of the stucco.
- the polyvinyl alcohol can be present in the board core in an amount from about 0% to about 1% by weight of the stucco.
- the boric acid can be present in the concentrated layer in an amount from about 0.1% to about 1% by weight of the stucco, and can be present in the board core in an amount from about 0% to about 0.1 % by weight of the stucco.
- the enhancing additive optionally comprises nano- cellulose, micro-cellulose, or any combination thereof in order to enhance strength, e.g., nail pull resistance or other strength parameter.
- the nano-cellulose, micro-cellulose, or combination thereof can be present in any suitable amount such as, for example, in the concentrated layer slurry in an amount, for example, from about 0.01 % to about 2%. e.g., from about 0.05% to about 1 % by weight of the stucco, and in the board core slurry in an amount, for example, from about 0% to about 0.5%, e.g., from 0% to about 0,01 % by weight of the stucco.
- the enhancing additive can comprise gypsum-cement in order to enhance strength, e.g., nail pull resistance or other strength parameter, in some embodiments.
- the gypsum-cement is optional and can be present in any suitable amount.
- it can be included in the concentrated layer in an amount of from about 5% to about 30% by weight of the stucco, and can be present in the board core in an amount from about 0% to about 10% by weight of the stucco.
- composite board made according to the disclosure meets test protocols according to ASTM Standard C473- 10.
- the dry board has a nail pull resistance of at least about 65 ib f (pounds force) as determined according to ASTM C473- 10 (method B), e.g., at least about 68 Ibf, at least about 70 ib f . at least about 72 Ibf, at least about 74 Ibf, at least about 75 Ibf, at least about 76 Ibf, at least about 77 Ibf, etc.
- the nail pull resistance can be from about 65 Ibf to about 100 Ibf, from about 65 Ib f to about
- Ibf from about 65 Ib f to about 90 Ibf, from about 65 ibf to about 85 ib f , from about 65 Ibf to about 80 Ibr, from about 65 Ibf to about 75 Ibf, from about 68 Ibf to about 100 Ib f , from about
- Ibf from about 70 lb t - to about 90 Ibf, from about 70 Ib f to about 85 Ibf, from about 70 Ibf to about 80 Ibf, from about 72 Ibf to about 100 ibf, from about 72 Ibf to about 95 Ibf, from about
- 72 Ibf to about 90 Ibf from about 72 Ibf to about 85 ib f , from about 72 Ibf to about 80 Ibf, from about 72 ibf to about 77 Ib f , from about 72 Ibf to about 75 Ibf, from about 75 ibf to about
- Ib f from about 75 Ibf to about 95 Ib f , from about 75 Ib f to about 90 ibf, from about 75 ibf to about 85 ibf, from about 75 Ibr to about 80 ibf, from about 75 ibf to about 77 Ib f , from about
- board can have an average core hardness of at least about
- 1 1 Ib f e.g., at least about 12 Ibf, at least about 13 ib f , at least about 14 Ib f , at least about 15 Ibf, at least about 16 Ibf, at least about 1 7 Ibf, at least about 18 lb--, at least about 1 Ib f , at least about 20 Ibf, at least about 21 Ib f , or at least about 22 ib f , as determined according to ASTM
- board can have a core hardness of from about
- 1 1 Ib f to about 25 Ibr e.g., from about 1 1 ibf to about 22 3 ⁇ 4, from about 1 1 Ibf to about 21 lb--, from about 1 1 Ib f to about 20 ibf, from about ] 1 Ibf to about 19 ib f , from about i i ibf to about 1 8 Ib f , from about 1 1 Ibr to about 17 Ib f . from about 1 1 lb-- to about 16 Ibf, from about 1 1 ib f to about 15 Ib f , from about I I Ibf to about 14 Ib f , from about 1 1 Ibf to about 13 Ibf, from about
- Ib f from about 13 Ibf to about 1 8 Ibf, from about 13 Ibf to about 17 Ibf, from about 13 ibf to about 16 Ibf, from about 13 Ibf to about 15 Ibf, from about 13 ibf to about 14 Ibf, from about
- Ibf from about 14 Ibf to about 17 Ibf, from about 14 Ibf to about 16 Ibf, from about 14 Ibf to about 15 Ibf, from about 1 5 ib f to about 25 Ibf, from about 1 5 Ibf to about 22 Ib f , from about
- 16 Ib f from about 16 Ibf to about 25 Ibf, from about 16 Ibf to about 22 Ibf, from about 16 Ibf to about 21 Ib f , from about 1 6 Ibf to about 20 Ib f , from about 1 6 Ibf to about 19 Ibf, from about 16 Ib f to about 18 Ibf, from about 16 Ibf to about 17 Ibf, from about 17 Ibf to about 25 Ib f , from about 17 ib f to about 22 Ibf, from about 1 7 ibf to about 21 Ibf, from about 17 Ibf to about
- Ib f from about 17 Ibf to about 19 Ibf, from about 17 Ibf to about 18 ibf, from about 18 Ib f to about 25 Ib f , from about 1 8 i bf to about 22 Ibf, from about 1 8 ibf to about 21 lb;, from about
- the concentrated layer has an average, dry core hardness that is at least about 1 .5 times greater than the average dry core hardness of the board core, wherein the average core hardness is measured according to ASTM C-473- 10, e.g., at least about 2 times greater, 2.5 times greater, 3 times greater, 3.5 times greater, 4 times greater, 4.5 times greater, etc, wherein each of these ranges can have any mathematically appropriate upper limit, such as, for example, 8, 7, 6, 5, 4, 3, or 2, [0122] With respect to fiexurai ' strength, in some embodiments, when cast in a board of 1 ⁇ 4 inch thickness, the dry board has a fiexurai strength of at least about 36 Ibf in a machine direction (e.g.
- Ibf e.g., at least about 1 10 ibf, at least about 1 12 Ib f , etc in a cross-machine direction as determined according io the ASTM standard C473-10.
- the board can have a .fiexurai strength in a machine direction of from about 36 Ibf to about 60 Ibf, e.g., from about 36 Ibf to about 55 Ibf, from about 36 Ibf to about 50 Ibf, from about 36 Ibf to about 45 Ibf, from about 36 Ibf to about 40 ibf, from about 36 Ibf to about 38 ib f , frorn about 38 !b ; - to about 60 Ibf, from about 38 Ibf to about 55 Ibf, from about 38 lb,- to about 50 ibf, from about 38 Ib f to about.
- the board can have a fiexurai strength in a cross-machine direction of from about 107 Ibf to about 130 Ibf, e.g., from about 107 Ibf to about 125 Ibf, from about 107 ibf to about 120 Ibf, from about 107 Ib f to about 1 15 ibf, from about 107 Ibf to about.
- 1 12 Ibf from about 107 Ibf to about 1 10 ibf, from about. 1 1 0 Ib to about 130 Ibf, from about 1 10 Ibf to about 125 Ib f , from about 1 10 Ibf to about 1.20 lb--, from about 1 10 Ibf to about 1 15 ibf, from about 1 ] 0 Ibf to about. 1 12 Ibf, from about 1 12 Ibf to about 1 30 Ibf, from about 1 12 Ib f to about .125 Ibf, from about 1 1 2 Ibf to about 120 Ibf, or from about. 1 12 Ib f to about 1 15 Ibf.
- the dry gypsum board can have a compressive strength of at. least about 170 psi ( 1 ,1 70 kPa), eg., from about 1 70 psi to about 1 ,000 psi (6,900 kPa), from about 170 psi to about 900 psi (6,200 kPa), from about 170 psi to about 800 psi (5,500 kPa), from about 170 psi to about 700 psi (4,800 kPa), from about 1 70 psi to about 600 psi (4, 100 kPa), from about 170 psi to about 500 psi (3,450 kPa), from about 170 psi to about 450 psi (3.1 00 kPa), from about 170 psi to about 400 psi (2,760 kPa), from
- the compressive strength can be bound by any two of the foregoing points.
- the compressive strength can be between about 450 psi and about 1 ,000 psi (e.g., between about 500 psi and about 900 psi, between about 600 psi and about 800 psi, etc.).
- the compressive strength can be measured using a materials testing system commercially available as ATS machine model 1.610, from Applied Test Systems in Butler, P A. The load is applied continuously and without a shock at speed of 1 mch/'min.
- these standards e.g., nail pull resistance, flexurai strength, and core hardness
- ultra light density board e.g., about 33 pcf or less, such as about 32 pcf or less, 31 pcf or less, 30 pcf or less, 29 pcf or less, 28 pcf or less, 27 pcf or less, 26 pcf or less, etc.
- these standards surprisingly can be met in some embodiments while using less overall enhancing additive and with a lighter, weaker, and/or softer core, and/or with lower overall water usage such that embodiments of the disclosure provide manufacturing efficiencies.
- Composite gypsum board according to embodiments of the disclosure can be made on typical gypsum waliboard manufacturing lines.
- board manufacturing techniques are described in, for example, U.S. Patent 7,364,676 and U.S. Patent Application Publication 2010/0247937. Briefly, the process typically involves discharging a cover sheet onto a moving conveyor. Since gypsum board is normally formed “face down,” this cover sheet is the “face” cover sheet in such embodiments,
- two separate slurries are formed.
- One slurry is a stucco slurry used to form the board core, and the other slurry is used to form the concentrated layer.
- the concentrated layer can be formed from any suitable material, including a cemencitious material, such as stucco, that hydrates to a set material, e.g., set gypsum.
- a cemencitious material such as stucco
- set material e.g., set gypsum
- the stucco slurry for forming the board core can have a lower WSR than the VV SR of the stucco slurry used for making the concentrated layer in some embodiments.
- foaming agent (or other lightweight material) is generally more prevalent in the board core slurry to provide its lower density, although some foam or lightweight material can be included in the concentrated layer slurry so long as the density parameters are achieved.
- concentration of the enhancing agent can be greater in the concentrated layer and some enhancing agent may not even be present in the board core slurry in accordance with some embodiments. Accordingly, the feed lines to the respective mixers can be adjusted accordingly, which is well within the level of ordinary skill.
- the two slurries can be formed in any suitable manner.
- two separate mixers can be used, where the raw materials are agitated to form the respective slurries.
- the mixers can be in series or unconnected.
- one mixer can be used to develop both slurry streams
- FIG. 2 illustrates three alternate schematic flow diagrams showing examples ' of how the slurries can be formed in accordance with the present disclosure.
- a single mixer can be used, whereas in depictions B and C, the two slurries are formed in separate mixers, e.g., in the form of "pin mixers " ' or '''pin-less mixers'" as desired.
- the mixer used for the concentrated layer can have a smaller mixing volume capacity in some embodiments since the amount of slurry needed to be applied for the concentrated layer is less than the amount of slurry that is applied to form the board core.
- the "main" mixer i.e., for forming the board core slurry
- the "main" mixer comprises a main body and a discharge conduit (e.g., a gate-canister-boot arrangement as known in the art, or a modified outlet design (MOD) arrangement as described in U.S. Patents 6,494,609 and 6,874,930).
- foaming agent can be added in the discharge conduit of the mixer (e.g., in the gate as described, for example, in U.S. Patents 5,683,635 and 6,494,609).
- Diagram A illustrates an embodiment where the steps occur using one mixer, i.e., the main mixer 100.
- Stucco 102 and water 104 are inserted into the main mixer 100, while foam 106 is inserted downstream in the discharge conduit 108 which can include a modified outlet design or canister, meaning that foam is not inserted in the body of the main mixer 100.
- a portion of the slurry 1 10, which is essentially foamless, is diverted from the mixer 100 from an exit port, e.g.. generally away from the discharge conduit 108 to form the
- the main mixer 100 acts as a pump to drive the unfoamed slurry 1 10 out the smaller discharge port for the concentrated layer slurry which flows through the pressurized slurry line.
- Additives, particularly, the enhancing additive, in wet form 1 14 are injected into the pressurized slurry line through injection ports.
- the inventors have found that the line is desirably long enough, which can be determined within the level of ordinary skill, to allow for uniform mixing of slurry including enhancing additive. There is no need for separate introduction- of stucco or water.
- edge slurry streams 1 16 and 1 1 S can also be diverted from the main mixer 100 without foam so that they have the desired hardness for their use on the edges as known in the art.
- FIG. 2 it can be seen that the two mixers 200 and 202 are connected in series. Stucco 204 and water 206 are added to the main mixer 200, The foam 208 is added downstream of the body of the main mixer 200 in the discharge conduit 210 (which can contain a modified outlet design or canister). Thus, fbamless slurry 212 can exit the mixer 200 through an exit port and inserted into the smaller secondary mixer 202 for the
- Edge slurry streams 214 and 216 are also shown as exiting from a port separate from the main discharge 210 to minimize foam therein and provide their desired hardness.
- FIG. 10331 In diagram C, it can be seen that there are two mixers 300 and 302 but the slurries are made separately, with each mixer having its own inputs for stucco and water as desired. Particularly, stucco 304 and water 306 are added into the main mixer 300. Foam 308 is added downstream of the body of the main mixer 300 in the discharge conduit 3 ⁇ 0 (which can contain a canister or modified outlet design as described in U.S. Patents 6,494,609 and 6,8 * 74,930), Edge slurry streams 312 and 314 can exit from a port separate from the main discharge 310 to minimize foam therein and provide their desired hardness.
- a secondary mixer 302 for forming the concentrated layer slurry 316, stucco and water 318, 320 can he added and mixed.
- Dry and wet additives e.g., via separate lines, including enhancing additive as described herein, can be inserted into the concentrated layer mixer 302.
- the concentrated layer slurry 316 is prepared separately from the core slurry formed in the main mixer 300.
- the edge slurries can be extracted from the concentrated layer mixer, instead of from the main mixer, as desired.
- the edges can he denser than the board core in some embodiments and, e.g., can have the same density as the concentrated layer.
- a portion of the concentrated layer slurry can How around the ends of the roller to form edges of the ultimate product, as seen in FIGS. 5 and 6 with respect to one end.
- the length of the roller can be configured (e.g., to be shorter than the width of the paper) to accommodate the formation of edges in d ss manner.
- the discharge conduit can include ' a slurry distributor with either a single feed inlet or multiple feed inlets, such as those described in U.S. Patent Application Publication 2012/0168527 Al (Application No.
- the discharge conduit can include a suitable flow splitter, such as those described in U.S. Patent Application Publication 2012/0170403 Al .
- Board is formed in a sandwich structure, normally concurrently and continuously, as will be understood in the art.
- the face cover sheet travels as a continuous ribbon on a conveyor. After being discharged from its mixer, the concentrated layer slurry is applied to the moving face cover sheet. Also, hard edges, as known in the art, can be formed, e.g., from the same slurry stream forming the concentrated layer for convenience, if desired.
- the board core slurry is then applied over the moving face paper bearing the concentrated layer slurry, and covered with a second cover sheet (typically the "back" cover sheet) to form a wet assembly in the form of a sandwich structure that is a board precursor to the final product.
- the back (bottom) cover sheet may optionally bear a skim coat, which can be formed from the same or different gypsum slurry as for the concentrated layer.
- the cover sheets may be formed from paper, fibrous mat or other type of material (e.g., foil, plastic, glass mat, non-woven material such as blend of cellulosic and inorganic filler, etc.).
- the concentrated layer is applied on both major sides of the board, i.e., in bonding relation to both the top and bottom sheets,
- the wet assembly thereby provided is conveyed to a forming station where the product is sized to a desired thickness (e.g., via forming plate), and to one or more knife sections where it is cut to a desired length.
- the wet assembly is allowed to harden to form the interlocking crystalline matrix of set gypsum, and excess water is removed using a drying process (e.g., by transporting the assembly through a kiln).
- a drying process e.g., by transporting the assembly through a kiln.
- Board 1 was a comparative board, absent a concentrated layer.
- Boards 2 and 3 were composite gypsum boards where each contained a concentrated layer and board core in accordance with principles of the disclosure. Each board was prepared at a thickness of about one-half inch with a composite density, not including the face and back paper, of about 26 pcf
- Each board was produced as a 6 inch by 6 inch laboratory sample following the genera] arrangement shown in FIG. 1 .
- the respective thickness and density for the concentrated layer (if present) and board core for each board is provided in Tables i A and IB.
- the enhancing additive was a pregelatinized com starch having a viscosity of 773 centipoise determined according to the VMA method. In Boards 2 and 3, it can be seen in Tables 1 A and I B that the enhancing additive was more concentrated in the concentrated layer than in the board core.
- composition 2A was a comparative composition inasmuch as it included no starch.
- Composition 2B included a cooked starch in the form of a pregelatmized starch having a viscosity of 80 cP, as measured according to the VMA Method, as set forth in US
- L Compositions 2C-20 included one of various uncooked starches as shown in Table 3 ,
- the disks were prepared from separate slurry compositions 2A-20.
- comparative composition 2A the total weight was 799.8 g as there was no starch.
- Each composition was prepared from dry and wet mixes that were combined. Each wet mix was prepared by weighing the water, dispersant, retard er 1% solution, dispersant, and sodium trimeiaphosphate .10% solution in a mixing bowl of a Waring blender (model CBI 5), commercially available from Conair Corp. (East Windsor, New Jersey).
- the sodium trimeiaphosphate 10% solution was prepared by dissolving 10 parts (weight) of sodium trimetaphosphate in 90 parts (weight) of water, while the retarder 1% solution was composed of an aqueous solution of the pentasodium salt of di ethyl enetriaminepentaacetic acid (VersenexTM 80, commercially available from DOW Chemical Company, Midland, MI), and prepared by mixing 1 part (weight) of VersenexTM 80 with 99 parts (weight) of water.
- the remaining ingredients particularly, the stucco, heat resistant accelerator, and starch (if present), were weighed and prepared in a dry mix.
- the heat resistant accelerator was composed of ground up land piaster and dextrose. The dry mix was poured into the blender with the wet ingredients, and soaked for 5 seconds and then mixed at high speed for 15 seconds.
- Foam was added in order to reduce disk density (and hence weight).
- a 0.5% solution of HyonicTM PFM-33 soap available from GEO Specialty Chemicals, Ambler, PA
- the air foam was added to the slurry using a foam generator.
- the foam generator was operated at a rate sufficient to obtain a density of the final dried disk of 38 pcf.
- the slurry was immediately poured into a ring (4" inside diameter and 0.5" thick) type of mold which was suited for forming a disk sample.
- the surface of the molds had previously been sprayed with lubricant in the form of WD40TM, commercially available from WD-40 Company, San Diego, CA.
- the slurry was poured to a point slightly above the top of the ring of the molds. The excess slurry was scraped as soon as the plaster was set.
- the disks were removed from the moid, and heated at 300 °F (149°C) for 60 min, then dried at 1 10°F (43°C) for about 48 hours until a constant weight was reached. Following removal from the oven, the disks were allowed to cool at room temperature for one hour.
- the final disks had dimensions of a diameter of 4 inches (10.16 em), and a thickness of 0.5 inches (1 .27 cm).
- this example illustrates thai both cooked and uncooked starches have benefit as enhancing additive for improving strength as shown by the improvement in performance on strength.
- the uncooked and cooked starches showed considerable improvement in strength over the comparative composition without the starch, with many of the values being more than about 50% higher than the strength of the control without starch, more than about 75% higher than the strength of the control without starch, or more than about 100% more than the strength of the control without starch.
- the improvement in strength seen in the disks shown from both cooked and uncooked starches indicates the utili ty of these starches in the concentrated layer of a gypsum wallboard in accordance with some embodiments because the desired starches provides extra bonding between gypsum crystals for strength improvement.
- the starches were effective to improve strength, thereby suggesting lack of migration, contrary to the case with a migratory acid-modified starch. Therefore, the example shows that the starches would be effective in a concentrated layer.
- composition 3 A did not contain any fi ber
- composition 3B contained glass fiber having a fiber length of 0.5 inch (25,400 ⁇ ) and diameter of 15.24 - ⁇ 16.51 ⁇ , thereby having an aspect ratio of about 1540 to about 1670 (length divided by diameter).
- the glass fiber was in the form of DuraCoreTM SF+ 1/2M300 pre-chopped strands, commercially available from Johns Manvvette Inc., (Denver, CO).
- a general representative range of formulation for illustrative purposes only for the concentrated layer is provided in Table 4, where low and high columns are provided to indicate an example of desired ranges of ingredients therebetween (inclusive) in accordance with an embodiment.
- Other representative formulations and embodiments will be easily ascertained from the full description herein, including the ranges for ingredients provided.
- the triaied formulations are provided in Tables 5A and 5B. Aside from the differences in glass fiber, the two formulations were the same, as can be seen in Tables 5A and 5B.
- the heat resistant accelerator was composed of ground land plaster and dextrose. Each slurry composition was prepared from dry and wet ingredients that were combined in a secondary mixer dedicated for the concentrated layer, separate from the main mixer for preparing the core. The sodium trimeiaphosphate, retarder, and dispersani were added in liquid form. The retarder was in the form of pentasodium salt of
- dieihylenetriaminepentaacetic acid (VersenexTM 80, commercially available from DOW Chemical Company, Midland, Ml).
- the dispersant was in the form of a poly naphthalene sulfonate calcium salt (DURASARTM commercially from Ruetgers Polymers, Candiae, (Canada).
- a 3 urn can optionally be included to modify the gypsum hydration rate, if desired, j OlSS] Foam was included in the concentrated layer, and the density of the concentrated layer produced from both slurries was 36 pcf on a dry basis.
- a solution of a mixture of STEOLTM CS230 and Polystep 25 foaming agents (available from Stepan Co., Nortbfteld, IL) was formed and then mixed with air to make the air foam using a foam generator.
- the air foam was added to the slurry at the secondary mixer.
- the amount of foam added was 1 % by weight foaming agent.
- the foaming agent (1 % solution) was prepared by dissol ving 1 parts (weight) of foaming agent in 1(50 parts (weight) of water.
- the roller normally works with a second roller under the paper with a sufficient gap between the rollers to permit the thickness of the paper to travel therebetween. f01S?S As the roller obstructs the forward progress of the slurry, a slurry head forms behind, and just upstream, from the roller, controlled primarily by tangential speed of the rotating roller.
- the head is an inventory of slurry that helps decelerate the incoming material, providing spread, which allows for proper amount, of slurry to form the concentrated layer and the edges.
- the slurry is wiped from the head and carried by the roller to the downstream side of the roller and re-deposited on the paper and spread to lay what becomes the concentrated layer o the board.
- FIGS. 3-6 illustrate images depicting the slurry head (FIGS. 3-4) and the formation of an edge around the roller (FIGS. 5-6) from the manufacturing trials using ihe slurries without the glass fiber (composition 3 A; FIGS. 3 and 5), and with optional glass fiber (composition 3B; FIGS. 4 and 6).
- composition 3A composition 3 A
- FIGS. 3 and 5 composition 3 A
- FIGS. 4 and 6 composition 3B
- composition 3B was carried out to illustrate the conditions shown in FIGS, 4 and 6.
- the concentrated layer slurry was applied by a roller 400 or 500 to a paper cover sheet 402 or 502,
- the slurry without glass fiber shown in FIG. 3 was deposited on paper 402 upstream of roller 400 and the deposited slurry traveled toward the roller 400 in a line of slurry 404 that was choppy and uneven.
- the slurry without glass fiber resulted in a more scalloped slurry head 406, with livdrodynamic instability 408 resulting in undesired air entraimnent.
- FIG. 5 corresponds with the trial shown in FIG. 3, and FIG. 6 corresponds with the trial shown in FIG. 4.
- FIGS. 5-6 show an edge 410 or 510 of the roller 400 or 500.
- An edge slurry 12 or 512 is formed around the edge 410 or 510 of the roller 400 or 500 to ultimately form an edge of the board to be produced.
- the slurry without glass fiber resulted in a more variable edge which can cause voids, blisters, paper delamination, soft and/or hard edges, and general disruption to the edge formation and manufacturing process, as seen in FIG. 5.
- FIG. 5 shows an edge 410 or 510 of the roller 400 or 500.
- An edge slurry 12 or 512 is formed around the edge 410 or 510 of the roller 400 or 500 to ultimately form an edge of the board to be produced.
- the slurry without glass fiber resulted in a more variable edge which can cause voids, blisters, paper delamination, soft and/or hard edges, and general disruption to the edge formation and manufacturing process
- slurry compositions were prepared as follows. Each slurry composition was prepared from dry and wet ingredients that were combined in a mixer (i.e., a main mixer for the core slurries, and a secondary mixer dedicated for the concentrated layer .slurries). The water, sodium trimetaphosphate, retarder, dispersant, and alum were added in liquid form. The retarder was in the form of pentasodium salt of diethylenetriaminepentaaeetie acid (VersenexTM 80, commercially available from DOW Chemical Company, Midland, MI).
- the dispersant was in the form of a poly naphthalene sulfonate calcium salt (DU ASARTM commercially from Ruetgers Polymers, Candiac, Canada).
- the stucco, heat resistant accelerator, glass fiber, and dextrose were added in solid form.
- Alum was optionally included to modify the gypsum hydration rate, if desired.
- the heat resistant accelerator was composed of ground land-plaster and dextrose. Additional dextrose was added in some instances to improve bonding with the back (news-line) paper cover sheet.
- Foam was included in the core slurries and concentrated layer slurries.
- a solution of a mixture of STTEOLTM CS230 and Polystep 25 foaming agent (available from Stepan Co., Northfield, IL) was formed and then mixed with air to make the air foam using a foam generator.
- the air foam density was approximately 4.5 lbs per cubic foot.
- the air foam was added to core slurry in a discharge conduit of the main mixer and added to the concentrated slurry at the secondary mixer.
- the weight percentage of a specific ingredient is based on its own weight, versus the total composition of the wet slurry (thus, excluding paper). Any inconsistencies in the totals are due to rounding of values of individual ingredients, e.g., due to effective limits of readings from equipment such as pumps and flow meters, as will be understood by those skilled in the art.
- This example demonstrates a benefit of including a concentrated layer in gypsum board.
- the example shows that the concentrated layer enhances nail pull performance.
- Two boards were prepared. Board 4A and Board 4B. Board 4A did not contain a coneentrated layer. Board 4B did.
- the slurry compositions for preparing boards 4A and 4B are set forth in Tables 6 and 7, respectively.
- Boards 4A and 4B were each prepared on a high speed (over 600 ft/min) board manufacturing line (machine) using a main pin mixer to combine wet and dry ingredients in a continuous process to form a continuous ribbon of board precursor, with a core slurry deposited between two sheets of paper, as described in Example 3.
- the concentrated layer- was used in preparing Board 4B with the aid of a secondary board, mixer to blend wet and dry ingredients.
- This concentrated layer slurry was applied to the face paper using an application roller, with the core slurry deposited thereon from a discharge conduit from the main mixer.
- the precursors were processed and kiln dried to form the final Boards, 4A and 4B.
- This example shows a benefit of the concentrated layer in enhancing strength of the board product.
- Board 4B which included the concentrated layer, resulted in an increased nail pull (resistance) value.
- nail pull herein refers to nail pull resistance as mea ured according to ASTM 473 - 10 Method B, unless otherwise stated.
- nail pull improvement is beneficial in providing strength and enhancing peribraiance in the field of.the board.
- increasing nail pull with the aid of concentrated layer can be used to reduce board weight and the cost of
- This example demonstrates a benefit of using a concentrated layer in gypsum board.
- tailoring ingredients in the slurry for forming the concentrated layer can be beneficial
- the rate in which a concentrated layer stiffens can be optionally modulated to effect the washout of the concentrated layer as the main (core) slurry meets the concentrated layer slurry during the board manufacturing process. Washout refers to the removal of the concentrated layer which can occur when the core slurry is distributed over the concentrated layer during the continuous manufacturing process. Washout undesirably can result in product non-uniformity and reduced nail pull.
- Two boards were prepared. Boards 5A and 5B.
- the compositions for preparing Boards 5 A and 5 B are set forth in Tables 9 and 10, respecti ely.
- the stiffening rate of stucco slurry (sometimes called gypsum slurry) in this example was modified using alum and retard er.
- the amount of al um was decreased in Board 5B to decrease the rate of setting, while retarder was added to Board 5B to also decrease the rate of setting.
- Boards 5A and Mix 5B were each, prepared on a high speed machine using a main pin mixer to combine wet and dry ingredients in a continuous process, as described in Example 3, to form a continuous ribbon of board precursor, with core slurry deposited between two sheets of paper.
- a concentrated layer was used to prepare Boards 5A and 5B with the aid of a secondary board mixer to blend wet and dry ingredients. This concentrated layer slurry was applied to the face paper using an application roller, with the core slurry deposited thereon from a discharge conduit from the main mixer.
- the precursors were processed and kiln dried to form the final boards 5A and 5B. Properties and dimensions of the boards are set forth in Table 1 1.
- Washout was measured utilizing a density profiiimeier machine which utilizes X- Ray technology (i.e., QDP-01X Density Profiler, commercially available from Quintek Measurement Systems, inc., noxville, TN) to determine the density gradient throughout the sample.
- X- Ray technology i.e., QDP-01X Density Profiler, commercially available from Quintek Measurement Systems, inc., noxville, TN
- This example demonstrates a benefit of including a concentrated layer in a gypsum board.
- the slurry composition for forming the concentrated layer can be tailored to include enhancing additives.
- starch concentration can be used to decrease the washout of the concentrated layer as the main (core) slurry meets the concentrated layer slurry during the board manufacturing process.
- Two boards were prepared, Boards 6A and 6B.
- the slurry compositions for preparing Boards 6A and 6B are set forth in Tables 12 and 13, respectively. Table 12 - Composition for Board 6A
- Boards 6A and 6B were each prepared on a high speed machine using a main pin mixer to combine wet and dry ingredients in a continuous process, as described in Example 3, to form a continuous ribbon of board precursor, with core slurry deposited between two sheets of paper.
- a concentrated layer was used to prepare Boards 6 A and 6B with the aid of a secondary board mixer to blend wet and dry ingredients. This concentrated layer slurry was applied to the face paper using an application roller, with the core slurry deposited thereon from a discharge conduit from the main mixer.
- the precursors were processed and kiln dried to form the final Boards, 6A and 6B. Properties of the boards are set forth in Table 14.
- This example illustrates a benefit of having a concentrated layer. Particularly, it can be seen that having a higher concentration of pregeiatinized starch in the concentrated layer slurry, as compared with the core slurry, was beneficial. As seen in Table 14, Board 6 A demonstrated more washout as compared with Board 6B. In this regard, Board 6A differed from Board 6B in that Board 6A was prepared using less pregeiatinized starch, resulting in more washout, while Board 6B included more pregelaniinized starch in the slurry. The results shown in Table ,14 indicate washout was reduced by 75% in Board 6B as compared with Board 6A. Use of more enhancing additive, e.g., pregeiatinized starch, in the concentrated layer can be less costly and more efficient as the additive is more highly located where the most benefit is seen, i.e., in the concentrated layer.
- more enhancing additive e.g., pregeiatinized starch
- This example demonstrates a benefit of including a concentrated layer in a gypsum board.
- density of a concentrated layer can be used to improve nail pull. Density was modified by changing the amount of foam contained in the concentrated layer.
- Two boards were prepared, Boards 7A and 7B.
- the slurry compositions for preparing Boards 7A and 7B are set forth in Tables 15 and 16, respectively.
- Boards 7A and 7B were each prepared on a high speed machine using a main pin mixer to combine wet and dry ingredients in a continuous process, as described in Example 3, to form a continuous ribbon of board precursor, with core slurry deposited between two sheets of paper.
- a concentrated layer was used to prepare Boards 7A and 7B with the aid of a secondary board mixer to blend wet and dry ingredients. This concentrated layer slurry was applied to the face paper using an application roller, with the core slurry deposited thereon from a discharge from the main mixer.
- the precursors were processed and kiln dried to form the final boards 7 A and 7B. Properties and dimensions of the boards are set forth in Table
- This example demonstrates a benefit of including a concentrated layer in gypsum board.
- Starcii concentration in the concentrated layer can be used to improve nail pull.
- Two boards were prepared, Boards 8A and 8B. In this instance, since washout was more prevalent under test conditions, the nail pull difference was measured along the machine direction side of the board (the non-code side) where washout was not prevalent.
- the slurry compositions for preparing Boards 8A and 8B are set forth in Tables 18 and 19, respectively.
- Boards SA and 8B were each prepared on a high speed machine using a main pin mixer to combine wet and dry ingredients in a continuous process, as described in Example 3, to form a continuous ribbon of board precursor, with core slurry deposited between two sheets of paper.
- a concentrated layer was used to prepare Boards 8A and 8B with the aid of a secondary board mixer to blend wet and dry ingredients. This concentrated layer slurry was applied to the face paper using an application roller, with the core slurry deposited thereon from a discharge conduit from the main mixer.
- the precursors were processed and kiln dried to form the final Boards, 8 A. and SB. Properties and dimensions of the boards are set forth in Table 20.
- This example shows a benefit of using a concentrated layer. Both boards demonstrated good nail pull with higher concentration of starch in the concentrated layer. Adding a higher concentration of pregelatinized starch in the concentrated layer resulted in better strength. As seen in Table 20, Board 8A demonstrated lower nail pull as compared with Board 8B. In this regard, Board 8A differed from Board 8B in that the concentrated layer of Board 8 A was prepared using less pregelaiinized starch, resulting in lower nail pull, while the concentrated layer slurry of Board 8B included more starch, resulting in higher nail pull. The results shown in Table 20 indicate starch concentration in the concentrated layer can be used to modify the nail pull result.
- This example illustrates a benefit of including a concentrated layer in gypsum board. Representative thickness of the concentrated layer for achieving improved nail pull is shown. Other thickness as described throughout herein can be used. Two boards were prepared. Boards 9 A and 9B. Thickness was modified by increasing the speed of the application roller and narrowing the spread of the concentrated layer, thereby making it thicker. The compositions used in preparing 9 A and 9B are set forth in Tables 21 and 22, respectively.
- Boards 9A and 9B were each prepared on a high speed machine using a main pin mixer to combine wet and dry ingredients in a continuous process, as described in Example 3, to form a continuous ribbon of board precursor, with core slurry deposited between two sheets of paper.
- a concentrated layer was used to prepare Boards 9A and B with the aid of a secondary board mixer to blend wet and dry ingredients. This concentrated layer slurry was applied to the face paper using an application roller, with the core slurry deposited thereon from a discharge conduit from the main, mixer .
- the precursors were processed and kiln dried to form the final boards, 9.4 and 9B. Properties and dimensions of the boards are set forth in Table 23.
- This example demonstrates that the concentrated layer enhances nail pull performance at a board weight target of 1.100 Ibs/MSF (about 5370 g/m 2 ).
- Two boards were prepared, Board 10A and Board 10B.
- Board IOB did not contain a concentrated layer, while Board 10A did.
- the slurry compositions for preparing Boards 10A and IOB are set forth in Tables 24 and 25, respectively. The compositions were prepared as described in Example 3, Table 24 - Composition for Board 10A
- Boards 10A and 10B were each prepared on a high speed machine using a main pin mixer to combine wet and dry ingredients in a continuous process, as described in Example 3, to form a continuous ribbon of board precursor, with core slurry deposited between two sheets of paper.
- a concentrated layer was used to prepare Boards i OA with the aid of a secondary board mixer to blend wet and dry ingredients. This concentrated layer slurry was applied to the face paper using an application roller, with the core slurry deposited thereon from a discharge conduit, from the main mixer.
- the precursors were processed and kiln dried to form the final boards, 10A and 10B. Properties and dimensions of the boards are set forth in Table 26.
- This example shows a benefit of using a concentrated layer.
- Board I DA demonstrated a higher nail pull as compared with Board 10B.
- Board lOA differed from Board 10B in that Board 10A was prepared using a concentrated layer slurry that included higher concentrations of pregelatinized starch compared to the core slurry, resulting in higher nail pull, while Board 10B did not contain a concentrated layer.
- the results shown in Table 26 indicate a concentrated layer containing high concentrations of pregelatinized starch can be used to increase nail pull,
Abstract
Description
Claims
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AU2016284331A AU2016284331C1 (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and methods related thereto |
CA2990472A CA2990472A1 (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and methods related thereto |
BR112017027589-9A BR112017027589B1 (en) | 2015-06-24 | 2016-06-22 | COMPOSITE PLASTER BOARD |
MX2018000159A MX2018000159A (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and methods related thereto. |
MYPI2017704930A MY194083A (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and methods related thereto |
EP16738261.3A EP3313659A1 (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and methods related thereto |
CN201680046161.1A CN107921736A (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and its correlation technique |
RU2018102152A RU2721675C2 (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board (versions) |
UAA201800571A UA125282C2 (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and methods related thereto |
KR1020187002300A KR102541879B1 (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and its associated method |
CN202310212563.6A CN116215019A (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board and related methods |
JP2017566400A JP6997626B2 (en) | 2015-06-24 | 2016-06-22 | Composite gypsum board |
SA517390593A SA517390593B1 (en) | 2015-06-24 | 2017-12-23 | Composite gypsum board and methods related thereto |
CONC2018/0000192A CO2018000192A2 (en) | 2015-06-24 | 2018-01-11 | Composite drywall and its related methods |
AU2021229170A AU2021229170A1 (en) | 2015-06-24 | 2021-09-08 | Composite gypsum board and methods related thereto |
AU2021229169A AU2021229169B2 (en) | 2015-06-24 | 2021-09-08 | Composite gypsum board and methods related thereto |
AU2021229171A AU2021229171A1 (en) | 2015-06-24 | 2021-09-08 | Composite gypsum board and methods related thereto |
AU2024201220A AU2024201220A1 (en) | 2015-06-24 | 2024-02-23 | Composite Gypsum Board and Methods Related Thereto |
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US62/290,361 | 2016-02-02 | ||
US15/186,176 US10421250B2 (en) | 2015-06-24 | 2016-06-17 | Composite gypsum board and methods related thereto |
US15/186,232 | 2016-06-17 | ||
US15/186,257 | 2016-06-17 | ||
US15/186,257 US20160376191A1 (en) | 2015-06-24 | 2016-06-17 | Composite gypsum board and methods related thereto |
US15/186,212 | 2016-06-17 | ||
US15/186,232 US10421251B2 (en) | 2015-06-24 | 2016-06-17 | Composite gypsum board and methods related thereto |
US15/186,212 US11040513B2 (en) | 2015-06-24 | 2016-06-17 | Composite gypsum board and methods related thereto |
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US10309771B2 (en) | 2015-06-11 | 2019-06-04 | United States Gypsum Company | System and method for determining facer surface smoothness |
EP3356307B1 (en) * | 2015-10-01 | 2021-02-24 | United States Gypsum Company | Foamed gypsum board and method of making it |
AU2017284000B2 (en) * | 2016-06-17 | 2021-08-12 | United States Gypsum Company | Method and system for on-line blending of foaming agent with foam modifier for addition to cementitious slurries |
JP2021524814A (en) * | 2018-05-21 | 2021-09-16 | ユナイテッド・ステイツ・ジプサム・カンパニー | Multilayer gypsum board and related methods and slurries |
US11267759B2 (en) | 2015-10-01 | 2022-03-08 | United States Gypsum Company | Method and system for on-line blending of foaming agent with foam modifier for addition to cementitious slurries |
US11697618B2 (en) | 2013-12-20 | 2023-07-11 | Gold Bond Building Products, Llc | Gypsum board with improved starch binder |
US11891815B2 (en) | 2017-09-28 | 2024-02-06 | Flooring Industries Limited, Sarl | Board and method for manufacturing a board |
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US10309771B2 (en) | 2015-06-11 | 2019-06-04 | United States Gypsum Company | System and method for determining facer surface smoothness |
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US11267759B2 (en) | 2015-10-01 | 2022-03-08 | United States Gypsum Company | Method and system for on-line blending of foaming agent with foam modifier for addition to cementitious slurries |
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US11891815B2 (en) | 2017-09-28 | 2024-02-06 | Flooring Industries Limited, Sarl | Board and method for manufacturing a board |
JP2021524814A (en) * | 2018-05-21 | 2021-09-16 | ユナイテッド・ステイツ・ジプサム・カンパニー | Multilayer gypsum board and related methods and slurries |
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