WO2013006537A1

WO2013006537A1 - Method and device for making an aqueous foam

Info

Publication number: WO2013006537A1
Application number: PCT/US2012/045208
Authority: WO
Inventors: Yen-Yau Harrison CHAO
Original assignee: Allied Foam Tech Corp.
Priority date: 2011-07-05
Filing date: 2012-07-02
Publication date: 2013-01-10

Abstract

A method and device for making foams and slurries using an assembly of pins having rigid and flexible segments, a rotor shaft, and a container than can be easily assembled and disassembled. According to one embodiment of the present invention, a method for making a foam includes at least the following steps: (a) feeding one or more reactants (e.g., an aqueous solution) and one or more optional additives into a container having an open top, a closed bottom, and a wall, wherein a rotor shaft is inserted into the top of the container; (b) rotating the rotor shaft to mix the solution; and (c) forming a foam (e.g., an aqueous foam).

Description

METHOD AND DEVICE FOR MAKING AN AQUEOUS FOAM

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No.

61/504,498 filed on July 5, 201 1, which is hereby incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The invention relates to a device and method for making foams and slurries. In particular, the invention relates to devices for making foamed cement and plaster products, for example.

BACKGROUND OF THE INVENTION

Foamed plaster-containing acoustic materials are known in the art. Typical methods of making foamed plaster boards are either by incorporating a preformed foam into a plaster component or by vigorous agitation of a foam reagent-containing plaster slurry to produce foam within the slurry. Alternatively or in addition, a compressed air source may be required to make the foam.

For example, in U.S. Patent No. 4,655,950, a heavy duty planetary action type mixer equipped with whisks or a continuous type mixer where gel is pumped under high pressure with air into a rotor and stator is used to make foam. The foaming is accomplished when a large volume of air is introduced into a foamable substrate and chopped into smaller and smaller units.

U.S. Patent No. 5,575,844 describes a method of making gypsum products using a rotary mixer element operatively adapted to develop relatively high shear and another rotary mixer element of relatively low shear. Preferred foams are formed by incorporating air into a liquid medium. As described in the '844 patent, uneven distribution of air may occur leading to the presence of significant voids in the set gypsum and a relatively low level of incorporation of air in the slurry.

It is believed that these methods and devices are not efficient and often need high energy input for high shear mixing. They also need several large pieces of equipment, including a compressed air source, in addition to at least one mixer. Therefore, it is desirable to make foam with less heavy equipment that can be used at different sites, plant environments, and in ambient air. SUMMARY OF THE INVENTION

According to one embodiment of the present invention, a method for making a foam includes at least the following steps:

(a) feeding one or more reactants (e.g., an aqueous solution) and one or more optional additives into a container having an open top, a closed bottom, and a wall, wherein a rotor shaft is inserted into the top of the container, the rotor shaft having a plurality of pins protruding from the rotor shaft, each pin having a rigid segment connected to the rotor shaft and a flexible segment contiguous with the rigid segment, wherein the rotor shaft is inserted into the top of the container such that the rotor shaft is generally centered within the container and at least a portion of the flexible segments of the pins touch the wall of the container;

(b) rotating the rotor shaft to mix the solution; and

(c) forming a foam (e.g., an aqueous foam).

Another aspect of the invention provides a method for making an aqueous foam comprising providing a container having an open top, a closed bottom, and a wall and a rotor shaft having a plurality of pins protruding from the rotor shaft;

inserting the rotor shaft into the open top of the container such that the rotor shaft is generally centered within the container and at least a portion of the flexible segments of the pins touches the wall of the container; attaching a power source to the upper portion of the rotor shaft; feeding an aqueous solution and any optional additives into the container; rotating the rotor shaft to mix the solution; and forming an aqueous foam. Each pin may have a rigid segment connected to the rotor shaft and a flexible segment contiguous with the rigid segment.

Another aspect of the invention provides a device for making a foam comprising a container having an open top, a closed bottom, and a wall; a rotor shaft centrally located within the container; a plurality of pins protruding from the rotor shaft, where each pin has a rigid segment connected to the rotor shaft and a flexible segment contiguous with the rigid segment and at least a portion of the flexible segment touches the wall of the container; and a power source that attaches to the rotor shaft to rotate the rotor shaft. BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawing are the following figures:

Fig. 1 shows a side transparent view of one embodiment of the device of the invention;

Fig. 2 shows a side view of the rotor shaft and pin assembly of the device of

Fig. 1 ;

Fig. 3 shows a side view of one embodiment of the pin;

Fig. 4 shows a side view of another embodiment of the pin;

Fig. 5 shows a side view of yet another embodiment of the pin;

Fig. 6 shows a side view of one embodiment of the rotor shaft and pin assembly disassembled;

Fig. 7 shows a side view of one embodiment of a pin arrangement;

Fig. 8 shows a side view of another embodiment of a pin arrangement;

Fig. 9 shows a side view of yet another embodiment of a pin arrangement;

Fig. 10 shows a side view of the motor with a lid;

Fig. 1 1 shows a side view of the motor with a container bracket;

Fig. 12 shows a top view of the rotor shaft and pins rotating in a clockwise direction; and

Fig. 13 shows a top view of the rotor shaft and pins rotating in a counterclockwise direction.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a device that may be lightweight, e.g., able to be easily moved from jobsite to jobsite, portable, or used in a factory environment, yet able to produce industrial scale quantities, e.g., greater than 20 liters, of foamed cement and plaster products without the need of a compressed air source. The device is particularly suitable for the production of foamed cement, plaster, and gypsum slurries. As used in this document, "foam" is understood to include foamed

thermoplastics, foamed thermoset plastics, foamed resins, polymeric foams, foamed cement, foamed plaster, foamed gypsum, and other foamed products known in the art. The "foam" or "foams" discussed in this document typically refer to a foam that is not yet cured (e.g., still in a liquid or semi-solid phase). Foam may also generally refer, however, to the resulting product (e.g., a partially or fully cured foam in a solid form). Cured foams are made of a solid and gas phase mixed together. The resulting foam may have a polymer matrix with either air bubbles or air tunnels incorporated in the matrix, known as closed-cell, open-cell, or partially open-cell structures. Closed-cell foams may generally be more rigid, while open-cell foams may be more flexible.

The method for making a foam includes feeding or adding one or more reactants (e.g., an aqueous solution) and one or more optional additives to the device, which is discussed in more detail below. The one or more reactants needed to create a foam would be readily ascertainable by one of ordinary skill in the art. For example, the reactants may include at least one polyol (e.g., polyester polyols, polyether polyols, or polycarbonate polyols) and at least one isocyanate (e.g., aromatic isocyanates, such as toluene diisocyanate or diphenylmethane diisocyanate), for example, to create a polyurethane. The reactants may be selected to create suitable polymer-containing foams including, but not limited to, polyalkenyl aromatic polymers, such as polystyrene and styrene-acrylonitrile; polyolefins, such as polyethylene and polypropylene; acrylics, such as polymethyl methacrylate and polybutyl acrylate; polyurethanes; copolymers; and mixtures of these polymers. The reactants may also include other ingredients known to one of ordinary skill in the art, such as chain extenders, blowing agents, catalysts, and the like. The reactants and other optional ingredients may be added together simultaneously or sequentially.

The foam may also comprise components needed to produce a cementitous, plaster, or gypsum foamed product. The cement, plaster, and gypsum components may include, for example, Portland-type cement, limestone, gypsum, lime, bauxite, clay, sand, ash (e.g., fly ash), fibrous materials (e.g., mineral wool, fiberglass, or glass fiber), and other fillers (e.g., polystyrene beads).

The one or more reactants may comprise an aqueous solution (e.g., a solution comprising water, the reactants, and/or other ingredients). If water is present, the water may or may not react and assist in frothing or foaming the solution (e.g., act as a blowing agent). Other suitable ingredients may include, for example, surfactants, colorants and pigments, fillers, reinforcers, viscosity modifiers, fire retardants, dispersing aids, and the like.

Fig. 1 shows one embodiment of the device 1 , as assembled. The device 1 comprises a container 10 having an open top 1 1 , a closed bottom 12, and a wall 13. The open top 1 1 may be partially or completely open. For example, the open top 1 1 may be completely open to the atmosphere. Alternatively, the open top 1 1 may be substantially closed once the rotor shaft 15 and the pins 16 are positioned (e.g., the open top 1 1 is closed except for an opening to allow for the rotor shaft 15). The container 10 is a stator housing that may be any substantially round container of metal, fiber, or plastic with a flat or curved closed bottom 12. The container 10 may or may not be treated or coated, for example, to minimize corrosion, scratching, and the like. The container 10 may have a diameter ranging from about 4" to 55" (10.2 cm - 140 cm) and weight about 1 - 400 lbs. (0.5 kg - 182 kg); however, any size container 10 may be used. In this embodiment, the closed bottom 12 is flat, but it may also be round or any other shape. Preferably, the wall 13 is curved in the shape of a barrel or cylindrical container. Exemplary containers 10 include small pails or buckets, drums, and larger cylindrical storage or mixing containers known in the art. The stator housing may comprise any suitable surface texture. Preferably, the stator housing comprises a smooth surface (e.g., a Root Mean Square (RMS) (Roughness Average) of 125 or less, preferably a RMS of 65 or less). For example, the stator housing (namely, wall 13) preferably does not contain any pins (e.g., the stator is pin free).

The container 10 may also have a discharge 14 (e.g., a port) at its closed bottom 12 for quick discharge of the foam (e.g., foam, foamed cement, or foamed plaster). The discharge 14 may be opened and closed, for example, using suitable valves, adapters, or connectors (e.g., ball, butterfly, paddle, or gate valves, and the like). Upon opening the discharge 14, the contents of the container 10 may be emptied via gravity or forced air at the top of the container 10. If forced air is used, the container 10 may also have a lid (not shown) with an air connector that allows the application of air pressure to quickly release the contents from the container 10. Alternatively or in addition, the container 10 may be emptied from the open top 1 1 , for example, via pouring the contents out of the container 10 and/or scooping the contents out of the container 10, or otherwise extracting the contents from the container 10 as would be readily understood by one of ordinary skill in the art. The foam may be discharged into a mold, for example, to form the foam into a suitable shape, e.g., bricks, pavers, cobbles, steppingstones, and the like.

The rotor shaft 15 is substantially centrally located within the container 10 and is insertable into and removable from the container 10. The rotor shaft 15 may be centrally located by approximating the center of the container 10 (e.g., not located at or near the periphery or wall 13 of the container 10). The centrally located rotor shaft 15 may extend down to any suitable position in the container 10, for example, the end of the rotor shaft 15 may be in juxtaposition to the closed bottom 12, may touch the closed bottom 12, or may be of some distance from the closed bottom 12. The rotor shaft 15 may comprise a thin metal rod, lightweight metal tubing, or plastic rod. The rod may be solid or may be in tubular form. The rotor shaft 15 may be in a tubular form or in the form of a solid piece or flat piece. The rotor shaft 15 has a plurality of pins 16 protruding from the rotor shaft 15. As shown in Fig. 2, the rotor shaft 15 and pins 16 may comprise one piece of the assembly 1 of Fig. 1.

For example, the rotor shaft 15 may be from 5" to 100" (12.7 cm - 254 cm) in length. The length depends on the assembly of the rotor shaft 15 and pins 16 and the quantity of foam per batch desired. The spacing between the rotor pins 16 on the rotor shaft 15 may be from about 1/8" to 5" (0.3 cm - 12.7 cm), for example.

The rotor, rotor shaft 15, and the rotor pins 16 may be fabricated with thin metal wire, lightweight metal tubings, plastics, or other appropriate materials. The rotor shaft 15 and rotor pins 16 may be fabricated with a flexible or rigid material. Preferably, the rotor shift 15 is fabricated with a rigid material. Exemplary metals for the rotor shaft 15, rotor pins 16, and the container 10 may include, for example, steel (e.g., stainless steel or other non-rusting steel), aluminum, copper, tungsten, titanium, metal carbides, and other non-rusting metallic materials and alloys. The metals may also be coated with a coating, e.g., a metal or plastic coating, to minimize or prevent rust. In one embodiment, the rotor shaft 15 is rigid aluminum tubing. Suitable plastics for the rotor shaft 15 and pins 16 are durable plastics, including flexible plastics, such as nylon, polyvinylchloride (PVC), polycarbonate (PC), polyethylene (PE), polypropylene (PP), or any other plastics in tube or conventional cable form, or as flat pieces, such as wire ties. A cap (not shown) may be placed on the bottom of the rotor shaft 15 to prevent the rotor shaft 15 from scratching the closed bottom 12 of the container 10 and allow low friction rotation. The cap may be a smooth metal surface that is integrated into the rotor shaft 15 or a soft plug of rubber, plastic, metal, or other appropriate material as would be recognized by one of ordinary skill in the art.

Each pin 16 on the rotor shaft 15 has a rigid segment 17 connected to the rotor shaft 15 and a flexible segment 18 contiguous with the rigid segment 17. In other words, each pin 16 is composed of at least two portions, a flexible segment 18 at the tip of the pin 16 and a rigid segment 17 at the base of the pin 16, which is coupled to the rotor shaft 15. As used in this document, "rigid" refers to a material that does not bend or does not substantially bend or deform when a force is applied, but does not preclude some minor shape distortion under pressure. On the other hand, "flexible" refers to the property of a material to bend, without breaking, along at least one axis when a force is applied. The rigid segment 17 of each pin 16 is, preferably, 2-20 times longer than the length of the flexible segment 18 of each pin 16. In other words, the ratio of rigid segment 17 to flexible segment 18 may range from about 2: 1 to 20: 1 rigid segment 17 to flexible segment 18, preferably, 5: 1 to 18: 1 rigid segment 17 to flexible segment 18, and more preferably 10: 1 to 15: 1 rigid segment 17 to flexible segment 18. In one embodiment, all of the pins 16 have the same ratio of rigid segment 17 to flexible segment 18. Alternatively, each of the pins 16 may have different ratios (e.g., half of the pins 16 have a higher rigid to flexible segment ratio).

The pins 16 physically and mechanically mix and froth the mixture at a relatively high rate of shear. In other words, the pins 16 introduce air into the mixture to produce the foam structure. Thus, a source of air, e.g., compressed air, or carbon dioxide is not required to foam the mixture. Moreover, a chemical blowing agent is not required to foam the mixture, but may be included if desired. When agitating the mixture, the plurality of pins 16 mechanically incorporate bubbles into the mixture, homogenously mix, and provide for foams with fine porous structures. For example, resulting pores in the cured foam may be on the order of 1 mm or less in diameter, preferably 0.5 mm or less in diameter.

At least a portion of the flexible segment 18 of at least some of the pins 16 touches or contacts the wall 13 of the container 10. Alternatively, at least a portion of the flexible segments 18 of all of the pins 16 may touch or contact the wall 13 of the container 10. For example, the tips of the flexible segments 18 of some or all of the pins 16 may touch or contact the wall 13 of the container 10. Preferably, the flexible segments 18 of the rotating pins 16 are in intimate contact with the wall 13 of the container 10. Due to the flexible nature of the flexible segments 18, the pins 16 may rotate and mix the foam effectively and scrape the wall 13 of the container 10 without damaging the pins 16.

The two segments 17 and 18 of each pin 16 may be fabricated from a single piece or multiple pieces. In the case of a single piece of metal or plastic, for example, the flexible segment 18 of the pin 16 may be thinned out or flattened to provide the flexible portion. Preferably, the rigid segment 17 is made of a solid metal, a tubular metal, or a rigid plastic material having a flat or round shape. The flexible segment 18 is, preferably, made of flexible plastics or flexible metals. Flexible plastics or metals may include those with high elasticity (e.g., ability to bend without permanent deformation) and/or high plasticity (e.g., ability to bend without breaking) of the material. Flexible metals may include metal shavings, thin metal strips, sheet metal, and metal wires, for example. In one embodiment, the flexible segment 18 comprises more than one or several flexible wires. The flexible segment 18 of each pin 16 in contact with the wall 13 may function as a scraper to remove the aqueous solution or foam or other material build up from the wall 13 of the container 10 and re-introduce it into the solution while the pins 16 are rotating about the rotor shaft 15. The flexible segment 18 may contact the wall 13 without scratching or otherwise damaging the container 10.

Fig. 3 depicts a pin 36 formed with a rigid segment 37 of tubular form and a flexible segment 38 made from crimping one end of the rigid segment 37. The crimped portion of the flexible segment 38 extends from a point 39 to the tip of the pin 36. Fig. 4 depicts a pin 46 with a rigid segment 47 and a flexible segment 48 made of plastic, where the flexible segment 48 is tapered to provide for the appropriate degree of flexibility. Fig. 5 depicts a pin 56 with a rigid segment 57 and a flexible segment 8 made from a metal tube, where the flexible segment 58 is crimped at the end to impart flexibility to the tip of the pin 56.

Each pin 16 may be of any suitable shape and dimension, e.g., round, oval, square, rectangular, flat, etc. Each pin 16 may be solid or hollow (e.g., tubular). In one embodiment, the pins 16 are cylindrical with diameters ranging from about 1/32" to 1" (0.8 mm - 25.4 mm), for example. The total weight, flexibility, and sturdiness of the device 1 should be considered in choosing the right diameter of each of the pins 16. In another embodiment, the pins 16 are flat with thicknesses from about 1/64" to ½" (0.4 mm - 12.7 mm) and widths from about 1/64" to ½" (0.4 mm - 12.7 mm), for example. The length of each of the pins 16 should be such that at least a portion of the flexible segment 18 of at least some of the pins 16 can reach and make good contact with the wall 13 of the container 10. During foam production, one or more of the pins 16 should contact the wall 13 of the container 10 at the flexible segments 18 of the pins 16. In other words, one or more of the pins 16 may approximately correspond to or equal the radius of the wall 13 of the container 10. Preferably, the pins 16 are from about 5" to 55" (12.7 cm - 140 cm) in length.

A plurality of pins 16 are removably affixed to the rotor shaft 15. The plurality of pins 16 may be uniformly or non-uniformly spaced along the distance of the rotor shaft 15 within the container 10. Preferably, the pins 16 are uniformly and evenly spaced along the rotor shaft 15. The pins 16 may be spaced such that the plurality of pins 16 make up an array of pins 16 (e.g., a systematic arrangement of pins 16 in a certain configuration). Spacing between the pins 16 along the rotor shaft

15 may be from about 1/8" to 5" (0.3 cm - 12.7 cm), for example. The spacing between the pins 16 on the rotor shaft 15 may be adjusted according to the shape and thickness of the pins 16, the foam efficiency, the foam fineness required, and the power or energy input desired. As would be recognized by one of ordinary skill in the art, pins 16 having smaller diameters may be spaced more closely together without significant increase of the energy input or rotating speed, and are still able to provide the desired foam efficiency and foam fineness. The dimensions or the thickness of the tubular or solid pins 16 may also affect the pin spacing. The total number of pins

16 may vary, for example, from about 10 - 500, preferably 50-400, and the number depends on the dimensions of the container 10, dimensions of the pins 16, foam quantity, efficiency, and other site-specific parameters desired.

Preferably, the pins 16 are removable or releasable from the rotor shaft 15 either individually or as an array of pins 16. Thus, the rotor shaft 15 and pins 16 are separable. As such, the rotor shaft 15 and pins 16 are compact and easily stored and transportable separate from the container 10. The pins 16 may be removably attached to the rotor shaft 15 using any suitable equipment and techniques known to one of ordinary skill in the art (e.g., clamped, spring loaded, pinched, or the like). In one embodiment shown in Fig. 6, the pins 16 are aligned (e.g., in parallel) on a supporting frame 60 and affixed to the rotor shaft 15 by attaching each of the pins 16 to corresponding mounting tubes 61 on the rotor shaft 15. Preferably, each mounting tube 61 is of a slightly larger diameter than that of the respective pin 16. A connector 62 located on the pin 16 engages with a connector 63 on the mounting tube 61 to lock the pins 16 in place. In one embodiment, the connector 62 is a screw. In another embodiment the connector 62 is a spring-operated pop-out button, which allows quick and precise mounting of the arrays of rotating pins 16 onto the rotor shaft 15. The connector 63 may be a hole that receives the connector 62. Connector 63 and connector 62 may also be reversed or reconfigured as would be understood by one of ordinary skill in the art.

The pins 16 may be arranged in a number of suitable configurations along the length of the rotor shaft 15. For example, the pins 16 may be arranged, along the direction of the rotor shaft 15, as a spiral, in parallel, perpendicular, diagonal, or the like. In one example shown in Fig. 7, the rotor assembly 70 has a spiral or helical array of pins 76, which are arranged around the rotor shaft 75 (e.g., arranged as a curve on a plane that winds around a fixed center point at a continuously increasing or decreasing distance from the point). In another example shown in Fig. 8, the rotor assembly 80 has a parallel array of pins 86 along the rotor shaft 85 (e.g., each of the pins 86 are equidistant from each other). In yet another example shown in Fig. 9, the rotor assembly 90 has a perpendicular array of pins 96 around the rotor shaft 95 (e.g., each pin 96 is perpendicular to the next in sequence and every other pin 96 is parallel). The pins 16 may be arranged in any of the above configurations or a combination of the above configurations. The pins 16 may also be arranged in another array of angles, which lie somewhere between parallel and perpendicular. In other words, each of the pins 16 do not need to be precisely horizontal with one another or precisely perpendicular with the rotor shaft 15, but may be positioned at some angle relative to the horizontal plane (for example, somewhere between 0° to 90°, e.g., 30° to 60°).

Any suitable type of power source (e.g., a motor) may be used and positioned appropriately on the rotor shaft 15 as is necessary to rotate the rotor shaft 15 with the desired torque and speed. As shown in Fig. 1, a power source 20 may be attached to the rotor shaft 15(e.g., via a screw or chuck 25) to rotate the rotor shaft 15.

Exemplary motors include, but are not limited to, portable industrial drills and motors, such as an electric or air motor of fixed or varied speed. The power source 20 may be suitably mounted, for example, using various lid mounting setups or metal brackets of various widths for different sizes of containers 10. Fig. 10 depicts a power source 100 of a motor 120 mounted On a lid 130, which may be affixed to the container 10 to close the open top 1 1. Fig. 1 1 shows a power source 200 of a motor 220 mounted on a container bracket 230, which may be set on the open top 1 1 of the container 10. The power sources 100 and 200 may be mounted onto the container 10 to provide power for making a foam or slurry.

Foams, such as aqueous foams, and slurries may be made using device 1. The foams may be produced with a desired density (e.g., ranging from about 0.1 to 25 lbs. per cubic foot (PCF), preferably 1 to 15 PCF, and more preferably 1 to 10 PCF). "Density" is understood to mean a mass per unit volume of a material. For example, aqueous foams at densities of less than 10 lbs. per cubic foot (160 kg/m³) may be produced in 1-6 minutes of mixing with low horse power (0.1 -5 hp) motors. The foams may be produced with fine pores (e.g., on the order of 0.5 mm or less in diameter).

Lightweight foamed cement may be also be made by foaming a foam in the container 10 and adding the preformed foam into a cement or gypsum slurry in a conventional concrete or cement mortar mixer. Other optional ingredients or suitable additives known to those skilled in the art may also be included with the reactants (e.g., polyols, isocyanates, etc.) or with the aqueous foam, such as water, surfactants, colorants and pigments, fillers, reinforcers, viscosity modifiers, fire retardants, dispersing aids, and the like. For example, one or two part surfactants or protein based foam reagents commonly used for foam cement and plaster in the industry may be used in this invention.

A preformed foam may be formed in the container 10 with the multi-pin containing rotor shaft 15 using the power source 20. To make the foam, the rotor shaft 15 may be inserted into the open top 1 1 of the container 10 such that the rotor shaft 15 is generally centered within the container 10 and at least a portion of the flexible segments 18 of the pins 16 touches the wall 13 of the container 10. The rotor shaft 15 may be inserted into the container 10 before or after the ingredients to be mixed are added to the container 10. The rotor shaft 15 may be long enough for the rotor shaft 15 to extend outside and above the container 10, as shown in Fig. 1, or may be completely contained within the container 10. The power source 20 may be attached to an upper portion of the rotor shaft 15 either before or after the rotor shaft 15 is inserted into the container 10.

The aqueous solution, for example, containing a foaming agent, may be fed into the container 10 and one or more other optional additives for the slurry may be added to the container 10 before, in the middle, or after the foaming operation.

Exemplary additives for the cement or plaster slurry include colorants; pigments, thickeners; accelerators; retarders; water proofing materials; water reducers;

polymeric binders of soluble, dispersible, or emulsion type; lightweight aggregates, such as perlite, vermiculite, expanded polystyrene beads, ceramic and glass spheres, and porous ceramic and glass materials; fibers of various kinds, such as nylon, polypropylene, glass, starch, wood, polyvinylalcohol, and acrylamide; and any other additive used for a typical cement or plaster slurry. To improve foam efficiency or to allow additives to distribute uniformly in a foamed slurry, however, some of these additives, such as thickeners, accelerators, retarders, pigments, colorants, lightweight aggregates, fibers, and others, may preferably be added into the preformed foam and before the addition of the slurry.

Once the ingredients and the rotor shaft 15 are in the container 10, the rotor shaft 15 may then be rotated using the power source 20 to mix the solution and form a foam. As shown in Figs. 12 and 13, during the foam production, at least a portion of the flexible segments 18 are able to scrape against the wall 13 of the container 10 for the efficient and complete agitation of the whole foam liquid within the container 10. In one embodiment, as shown in Fig. 12, the rotor shaft 15 and pins 16 rotate in the clockwise direction. In another embodiment, as shown in Fig. 13, the rotor shaft 1 and pins 16 rotate in the counter-clockwise direction. The pins 16 may rotate in a clockwise or counter-clockwise direction continuously, sequentially, or intermittently, as desired.

Various mechanisms of mixing wires or coils, like those described in U.S. Patents No. 5,482,367 and No. 5,725,305, which are hereby incorporated by reference in their entireties for all purposes, may also be incorporated on a middle segment of the rotating pin 16 (e.g., on the rigid segment 17 between the rotor shaft 15 and before the flexible segment 18 of the pins 16) to further improve the foam efficiency of the invention. The foam may be discharged from the container 10 via gravity or forced air through the discharge 14. For example, the foam may exit the container 10 through the discharge 14 when it is opened. Once the contents are emptied and the discharge 14 is closed, the container 10 may then be used again for another batch of foam. It is important to remove the foam from the container 10 within a timely manner before the foam has cured and hardened within the container 10.

The device 1 may also be used to make a cement, plaster, or gypsum slurry. Once the foam is made, a cement, plaster, or gypsum slurry may then be added. The rigid segments 17 of the rotor pins 16 effectively mix the foam produced within the container 10 with a cement or plaster slurry added, for example, from the open top 1 1 of the container without the need for a separate mixing chamber or a separate mixing rotor. The additives, as listed above, may be added before or after making the foam. Such additives may be added directly into the preformed foam or added after the addition of the cement or gypsum slurry.

Thus, the device 1 may be setup in a factory environment or may be lightweight and/or portable, for example, about 100 lbs. or less and/or able to be easily moved to a desired location. The device 1 allows for batch production of industrial-scale quantities, e.g., 20 liters or greater, preferably 100 liters or greater. Moreover, a source of compressed air is not needed to operate the device 1 or foam the ingredients. The device 1 may be operated at low operating speeds (e.g., 10-300 rpm) with reduced energy requirements, but still provide for efficient and effective mixing. The device 1 is particularly suitable for the production of foamed cement, foamed plaster, and foamed gypsum products.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to one skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. For example, the container may of a different shape than round as long as at least some portion of the flexible segments contact the wall of the container. Thus, it is intended that the invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. It is expressly intended, for example, that all ranges broadly recited in this document include within their scope all narrower ranges which fall within the broader ranges. It is also expressly intended that the steps of the methods of using the various devices disclosed above are not restricted to any particular order.

Claims

What is claimed is:

1 . A method for making a foam comprising:

adding one or more reactants and one or more optional additives into a container having an open top, a closed bottom, and a wall, wherein a rotor shaft is inserted into the open top of the container, the rotor shaft having a plurality of pins protruding from the rotor shaft, each pin having a rigid segment connected to the rotor shaft and a flexible segment contiguous with the rigid segment, wherein the rotor shaft is inserted into the open top of the container such that the rotor shaft is generally centered within the container and at least a portion of the flexible segments of the plurality of pins touches the wall of the container;

rotating the rotor shaft to mix the solution; and

forming a foam.

2. The method of claim 1 wherein the one or more reactants comprise an aqueous solution and the foam formed is an aqueous foam.

3. The method of claim 1 wherein the foam is discharged from the container, which comprises:

opening a discharge in the closed bottom; and

emptying the foam from the container via gravity.

4. The method of claim 1 wherein rotating the rotor shaft to mix the solution comprises:

spinning the rotor shaft in at least one of a clockwise and a counter-clockwise direction; and

scraping the wall of the container with the portion of the flexible segments touching the wall of the container.

5. The method of claim 1 wherein the plurality of pins are arranged on the rotor shaft in at least one of a spiral array, a parallel array, a perpendicular array, and an array of angles between parallel and perpendicular.

6. The method of claim 1 wherein the foam comprises a density of 160 kg/m or less.

7. The method of claim 1 further comprising:

adding a slurry to the foam in the container;

turning the rotor shaft to mix the slurry with the foam; and

discharging the foamed slurry from the container.

8. The method of claim 7 wherein adding the slurry to the foam in the container comprises:

introducing at least one of cement and plaster additives into the foam in the container.

9. A foam prepared using the method of claim 1.

10. A device for making a foam comprising:

a container having an open top, a closed bottom, and a wall;

a rotor shaft substantially centrally located within the container; and a plurality of pins protruding from the rotor shaft, each pin having a rigid segment connected to the rotor shaft and a flexible segment contiguous with the rigid segment, wherein at least a portion of the flexible segment is contacting the wall of the container.

1 1. The device of claim 10, wherein each of the plurality of pins have a ratio of about 2: 1 to 20: 1 the rigid segment to the flexible segment.

12. The device of claim 10 further comprising a cap at an end of the rotor shaft, the cap supporting the rotor shaft and contacting the closed bottom of the container.

13. The device of claim 10 further comprising a discharge within the closed bottom that opens to empty contents of the container.

14. The device of claim 10 further comprising a mount that holds the rotor shaft in position.

15. The device of claim 10 further comprising a power source including a motor that attaches to the rotor shaft and rotates the rotor shaft.

16. The device of claim 10 wherein the pins are arranged on the rotor shaft in at least one of a spiral array, a parallel array, a perpendicular array, and an array of angles between parallel and perpendicular.

17. The device of claim 10 wherein the flexible segment comprises at least one of a crimped metal tube, a plastic end, and a flexible metal.

18. The device of claim 10 wherein the container comprises at least one of metal and plastic.

19. The device of claim 10 wherein the plurality of pins comprises 10 to 500 pins.

20. The device of claim 10 wherein the rotor shaft and pins are separable.