WO1990005063A1 - Wrap, method for its manufacture and coating mix for use in the method - Google Patents

Wrap, method for its manufacture and coating mix for use in the method Download PDF

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Publication number
WO1990005063A1
WO1990005063A1 PCT/FI1989/000203 FI8900203W WO9005063A1 WO 1990005063 A1 WO1990005063 A1 WO 1990005063A1 FI 8900203 W FI8900203 W FI 8900203W WO 9005063 A1 WO9005063 A1 WO 9005063A1
Authority
WO
WIPO (PCT)
Prior art keywords
wrap
mix
coating mix
coating
amorphic
Prior art date
Application number
PCT/FI1989/000203
Other languages
French (fr)
Inventor
Pentti JÄRVELÄ
Mirja Lehtinen
Tapani Penttinen
Original Assignee
Enso-Gutzeit Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Enso-Gutzeit Oy filed Critical Enso-Gutzeit Oy
Publication of WO1990005063A1 publication Critical patent/WO1990005063A1/en

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H19/00—Coated paper; Coating material
    • D21H19/10—Coatings without pigments
    • D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
    • D21H19/20—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H19/22—Polyalkenes, e.g. polystyrene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
    • B05C11/023—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface
    • B05C11/025—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface with an essentially cylindrical body, e.g. roll or rod
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/10—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material
    • B05C11/1042—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material provided with means for heating or cooling the liquid or other fluent material in the supplying means upstream of the applying apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/80—Component parts, details or accessories; Auxiliary operations
    • B29B7/82—Heating or cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D65/38—Packaging materials of special type or form
    • B65D65/42—Applications of coated or impregnated materials
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D123/00—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers
    • C09D123/02—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D123/10—Homopolymers or copolymers of propene
    • C09D123/12—Polypropene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C3/00—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material
    • B05C3/18—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material only one side of the work coming into contact with the liquid or other fluent material

Definitions

  • the present invention concerns a wrap composed of paper, paperboard or similar fibrous material which is coated with a vapour barrier type of coating mix containing polyolefin plastic.
  • a typical application for the use of wrap is in the wrapping of large-size paper rolls.
  • the wrap enclosing the roll acts as both a mechanical protection and a vapour barrier maintaining a constant moisture content of the paper.
  • paper rolls are transferred by fork lifts, whereby the wrap must endure the mechanical stresses imposed by the lift arms closing about the roll.
  • one material used is pure polyethylene film.
  • Polyethylene gives a good vapour barrier, thereby maintaining the initial moisture content of the paper constant over the storage time, but its disadvantage is its tendency to easily tear. Tears can be caused by lift arms clamping the roll or additionally by other objects hitting the wrap.
  • a better mechanical protection is achieved by using polyethylene-coated paper for wrapping the roll.
  • the paper base gives the wrap mechanical strength, while poly ⁇ ethylene forms the required vapour barrier.
  • This approach is hampered by the low friction provided by the polyethylene layer facing the roll, whereby the wrap tends to slip when the roll is being lifted. It may even happen that the lift clamping the roll merely lifts the wrap.
  • a disadvantage in the use of polyethylene in wraps for paper rolls has further been that folding the wrap over the roll ends is cumbersome as well as that polyethylene is amenable to seal by heat. The latter characteristic makes the wrap prone to heat-seal itself to the roll during the attachment of end heads to the roll. In winter conditions a further disadvantage is that low temperature further reduces the initially low coefficient of friction of polyethylene and at the same time makes polyethylene brittle.
  • materials for paper roll wraps are selected from laminated wrap materials, in which two paper layers are adhered to each other with a plastic material layer.
  • the laminated structure prevents heat-sealing and removes slip problems caused by low friction during roll handling, but due to its composition results in a heavy and difficult to fold material with a high price in relation to its properties.
  • the present invention aims to achieve a novel wrap composed of a layer of paper, paperboard or similar fibrous material which is coated with a coat layer of an appropriate plastic material.
  • the invention avoids the disadvantages associated with the laminated wrap structures described above.
  • the basic structure of a wrap in accordance with the invention is similar to a conventional polyethylene-coated wrap, whose drawbacks are avoided according to the invention through the use of an advantageous coating mix, different from prior-art coatings.
  • the invention concerns a wrap, which is characterized by the constitution of the coating mix, which is composed of isotactic polypropylene with atactic polypropylene or amorphic poly- ⁇ -olefin acting as a plasticizer so that the needle penetration index of the mix is in the range 0.5...20 (0.1 mm/5 s) .
  • the preferred range of needle penetration index for the mix is 0.5...5 (0.1 mm/5 s) .
  • a wrap structure in accordance with the invention is further characterized by incorporating into the coating mix at least 50 % of an amorphic component, which is atactic polypropylene or poly- ⁇ -olefin.
  • the invention concerns a method for manu ⁇ facturing a wrap, in which method a polyolefin-containing coating mix with vapour-barrier characteristics is applied on paper, paperboard or similar fibrous base material.
  • the method is characterized in that into isotactic polypropy ⁇ lene is mixed atactic polypropylene or amorphic poly- ⁇ - olefin so that the proportion of the amorphic component in the mix will be at least 50 %, after which the obtained coating mix is applied in a melted state onto the base material of the wrap.
  • the preferred manufacturing method of the wrap starts with the mixing of the coating mix components in granulated form, after which the mix is melted and applied via a nozzle in a layer onto a movable web of paper, paperboard or similar base material.
  • the invention concerns a coating mix for use in the method described above, which mix is characterized by containing isotactic polypropylene mixed with atactic polypropylene or amorphic poly- ⁇ -olefin so that the pro ⁇ portion of the amorphic component in the mix will be at least 50 %.
  • the mix in accordance with the method contains 50...95 %, preferably 60...80 % of atactic polypropylene, and 5...50 %, preferably 20...40 % of isotactic poly ⁇ propylene, as well as wax and/or resin as possible additives.
  • the coating mix in accordance with the invention contains isotactic poly ⁇ propylene as one of its components, whose constitution is crystalline polypropylene with a melting index of 2...200 g/10 min according to the ASTM D 1238/L standard.
  • the mix contains as a component amorphic polyolefin, which can be atactic polypropylene with a melt viscosity of 100...500 000 mPa-s as measured in 180 °C temperature using the Brookfield viscometer according to the ASTM D 3236 standard.
  • Atactic polypropylene is a side product from the manufacture of polypropylene, whose yield is typically below 5 % and which is separated from the manufactured isotactic polypropylene by solvent extraction.
  • the amorphic component in the mix according to the invention can be a poly- ⁇ -olefin, advantageously a poly- ⁇ -ethylene, -propylene or -butylene having a melt viscosity falling within the range expressed above.
  • the purpose of a possible addition of wax to the coating mix according to the invention in a proportion of, for instance, approx. 10...15 %, is to adjust the hardness, tack and slip of the mix.
  • the purpose of natural or synthetic resin added to the coating mix with a proportion of, for instance, approx. 5 %, is to improve the adhesion of the mix to the fibrous base material.
  • a benefit of the wrap obtained in accordance with the invention is that the coating mix provides friction capable of preventing slip between a paper roll and the applied wrap while lifting the roll. Furthermore, multiple layers of wrap over the roll does not lead to a slip between the layers.
  • the coating mix moreover characterized by negligible embrittlement or loss of friction in low temperatures.
  • a further benefit of the invention is that the coating mix is not prone to sealing by heat during the application of end heads to the paper roll being wrapped. Furthermore, the wrap according to the invention is characterized by its easy foldability, which helps in obtaining a tight seal of the end heads to the roll.
  • a particular benefit of the wrap manufacturing method in accordance with the invention is that the base material does not require pretreatment by flame or corona discharge prior to the application of the coating mix, contrary to the need for pretreatment with the use of polyethylene for coat.
  • the coating mix can be routed to a slit nozzle, provided with a rotating applicator bar and butting a moving material web, whose function is to press the coating mix to the fibrous base material thus achieving a sufficient adhesion without any pretreatment of the base material.
  • a sufficient coat weight of the coating mix is typically approx.
  • the wrap according to the invention is also suitable for other wrapping purposes such as ream wraps for copying paper.
  • the wrap in accordance with the invention prevents moisture loss from the paper thus maintaining a constant moisture content of paper from the paper machine all the way to the customer.
  • the apparatus comprises a mixing container 1 provided with a rotating mixer 2 and having a hopper opening 3 at its top.
  • the components of the coating mix are fed in granulated form from a feed trough 4 via the opening 3 into the container 1.
  • the composition of the coating mix can be, e.g., 70 % atactic polypropylene and 30 % isotactic polypropylene.
  • the mixer 2 in the container 1 mixes the components, while the melting of the mix 5 is effected by heater elements provided within the container. An appropriate melting temperature is approx. 170 °C.
  • the melted homogenized coating mix 5 is routed via a line 7 provided with a pump 6 to a feed hopper 8 of the coater.
  • the coater comprises a rotating roll 9, which guides a paper web 10 of the base material for the web to be manufactured past an applicator nozzle head 11.
  • the melted coating mix 5 is conveyed from the hopper 8 under pressure imposed by toothed feeder bars 12 through an exit slit 13 of the applicator head having a width essentially equal to that of the paper web 10.
  • the nozzle head 11 is provided with a rotating coater bar 14, over which the coating mix to be applied flows to form a homogeneous layer on the paper web 10.
  • the result is a one-side coated wrap 15 having an appropriate coat weight of approx. 15 g/m 2 .
  • composition of the coating mix described above with 70 % atactic polypropylene and 30 % isotactic poly ⁇ propylene has been found advantageous in practice.
  • Other applicable compositions of the coating mix can be referred to as a mix containing 50 % atactic polypropylene with 35 % isotactic polypropylene and 15 % wax, and a mix containing 70 % atactic polypropylene with 15 % isotactic polypropylene, 10 % wax and 5 % resin.
  • the composition of the coating mix can, however, be varied within the limits expressed in the enclosed claims. For those versed in the art, it is evident that the different implementations of the invention can vary within the enclosed claims.
  • the base material of the wrap can be, in addition to paper, any other suitable fibrous material such as paperboard or linerboard.
  • the coating process is not limited to the procedure described above but can instead be a two- stage process, in which the first stage produces a homogenized coating mix broken into a granulate or blocks, while the second stage acting as the coating stage processes the granulate or block-formed coating mix by melting and application onto the base material.

Abstract

The invention concerns a wrap, a method for manufacturing the wrap and a coating mix for use according to the method. The wrap is composed of paper, paperboard or other similar fibrous base material coated with a coating mix, which provides for the vapour barrier characteristics of the wrap. The coating mix according to the invention is composed of isotactic polypropylene with atactic polypropylene or amorphic poly-α-olefin acting as a plasticizer so that the proportion of the amorphic component in the mix is at least 50 %. The components of the coating mix are intermixed and applied in a melted state onto the base material. The needle penetration index characterizing the softness of the coating mix is advantageously in the range 0.5...20 (0.1 mm/5 s). The wrap according to the invention is particularly applicable for wrapping paper rolls or copying paper.

Description

/
WRAP, METHOD FOR ITS MANUFACTURE AND COATING MIX FOR USE IN THE METHOD
The present invention concerns a wrap composed of paper, paperboard or similar fibrous material which is coated with a vapour barrier type of coating mix containing polyolefin plastic.
A typical application for the use of wrap is in the wrapping of large-size paper rolls. The wrap enclosing the roll acts as both a mechanical protection and a vapour barrier maintaining a constant moisture content of the paper. During storage and transportation, paper rolls are transferred by fork lifts, whereby the wrap must endure the mechanical stresses imposed by the lift arms closing about the roll.
For wrapping paper rolls, one material used is pure polyethylene film. Polyethylene gives a good vapour barrier, thereby maintaining the initial moisture content of the paper constant over the storage time, but its disadvantage is its tendency to easily tear. Tears can be caused by lift arms clamping the roll or additionally by other objects hitting the wrap.
A better mechanical protection is achieved by using polyethylene-coated paper for wrapping the roll. The paper base gives the wrap mechanical strength, while poly¬ ethylene forms the required vapour barrier. This approach, however, is hampered by the low friction provided by the polyethylene layer facing the roll, whereby the wrap tends to slip when the roll is being lifted. It may even happen that the lift clamping the roll merely lifts the wrap. A disadvantage in the use of polyethylene in wraps for paper rolls has further been that folding the wrap over the roll ends is cumbersome as well as that polyethylene is amenable to seal by heat. The latter characteristic makes the wrap prone to heat-seal itself to the roll during the attachment of end heads to the roll. In winter conditions a further disadvantage is that low temperature further reduces the initially low coefficient of friction of polyethylene and at the same time makes polyethylene brittle.
In the aim to avoid the disadvantages described above, materials for paper roll wraps are selected from laminated wrap materials, in which two paper layers are adhered to each other with a plastic material layer. The laminated structure prevents heat-sealing and removes slip problems caused by low friction during roll handling, but due to its composition results in a heavy and difficult to fold material with a high price in relation to its properties.
The present invention aims to achieve a novel wrap composed of a layer of paper, paperboard or similar fibrous material which is coated with a coat layer of an appropriate plastic material. In this approach the invention avoids the disadvantages associated with the laminated wrap structures described above. The basic structure of a wrap in accordance with the invention is similar to a conventional polyethylene-coated wrap, whose drawbacks are avoided according to the invention through the use of an advantageous coating mix, different from prior-art coatings. Consequently, the invention concerns a wrap, which is characterized by the constitution of the coating mix, which is composed of isotactic polypropylene with atactic polypropylene or amorphic poly-α-olefin acting as a plasticizer so that the needle penetration index of the mix is in the range 0.5...20 (0.1 mm/5 s) . The preferred range of needle penetration index for the mix is 0.5...5 (0.1 mm/5 s) .
The needle penetration values expressed above are based on tests performed according to the ASTM D 1321 and DIN 52010 standards. In comparison it can be pointed out that pure, crystalline isotactic polypropylene has a needle penetra¬ tion value of 0.
A wrap structure in accordance with the invention is further characterized by incorporating into the coating mix at least 50 % of an amorphic component, which is atactic polypropylene or poly-α-olefin.
Furthermore, the invention concerns a method for manu¬ facturing a wrap, in which method a polyolefin-containing coating mix with vapour-barrier characteristics is applied on paper, paperboard or similar fibrous base material. The method is characterized in that into isotactic polypropy¬ lene is mixed atactic polypropylene or amorphic poly-α- olefin so that the proportion of the amorphic component in the mix will be at least 50 %, after which the obtained coating mix is applied in a melted state onto the base material of the wrap.
The preferred manufacturing method of the wrap starts with the mixing of the coating mix components in granulated form, after which the mix is melted and applied via a nozzle in a layer onto a movable web of paper, paperboard or similar base material.
Moreover, the invention concerns a coating mix for use in the method described above, which mix is characterized by containing isotactic polypropylene mixed with atactic polypropylene or amorphic poly-α-olefin so that the pro¬ portion of the amorphic component in the mix will be at least 50 %. According to an advantageous implementation of the method, the mix in accordance with the method contains 50...95 %, preferably 60...80 % of atactic polypropylene, and 5...50 %, preferably 20...40 % of isotactic poly¬ propylene, as well as wax and/or resin as possible additives.
According to the description above, the coating mix in accordance with the invention contains isotactic poly¬ propylene as one of its components, whose constitution is crystalline polypropylene with a melting index of 2...200 g/10 min according to the ASTM D 1238/L standard. In addition to isotactic polypropylene, the mix contains as a component amorphic polyolefin, which can be atactic polypropylene with a melt viscosity of 100...500 000 mPa-s as measured in 180 °C temperature using the Brookfield viscometer according to the ASTM D 3236 standard. Atactic polypropylene is a side product from the manufacture of polypropylene, whose yield is typically below 5 % and which is separated from the manufactured isotactic polypropylene by solvent extraction. Alternatively, the amorphic component in the mix according to the invention can be a poly-α-olefin, advantageously a poly-α-ethylene, -propylene or -butylene having a melt viscosity falling within the range expressed above.
The purpose of a possible addition of wax to the coating mix according to the invention in a proportion of, for instance, approx. 10...15 %, is to adjust the hardness, tack and slip of the mix. Further, the purpose of natural or synthetic resin added to the coating mix with a proportion of, for instance, approx. 5 %, is to improve the adhesion of the mix to the fibrous base material.
A benefit of the wrap obtained in accordance with the invention is that the coating mix provides friction capable of preventing slip between a paper roll and the applied wrap while lifting the roll. Furthermore, multiple layers of wrap over the roll does not lead to a slip between the layers. The coating mix moreover characterized by negligible embrittlement or loss of friction in low temperatures.
A further benefit of the invention is that the coating mix is not prone to sealing by heat during the application of end heads to the paper roll being wrapped. Furthermore, the wrap according to the invention is characterized by its easy foldability, which helps in obtaining a tight seal of the end heads to the roll.
A particular benefit of the wrap manufacturing method in accordance with the invention is that the base material does not require pretreatment by flame or corona discharge prior to the application of the coating mix, contrary to the need for pretreatment with the use of polyethylene for coat. In a melted state the coating mix can be routed to a slit nozzle, provided with a rotating applicator bar and butting a moving material web, whose function is to press the coating mix to the fibrous base material thus achieving a sufficient adhesion without any pretreatment of the base material. A sufficient coat weight of the coating mix is typically approx. 15 g/m2, which provides less than 5 g/m2-24h water vapour transmission measured in 23 °C temperature at 50 % RH according to the P 448 om-84 and SCAN-P 22, 68 standards. In comparison it can be pointed out that conventional laminated wrap structures for paper rolls require a coat weight of 20...30 g/mz for achieving a comparable level of vapour barrier efficiency.
In addition to the application of wrapping paper or paperboard rolls, the wrap according to the invention is also suitable for other wrapping purposes such as ream wraps for copying paper. By virtue of its impermeability, the wrap in accordance with the invention prevents moisture loss from the paper thus maintaining a constant moisture content of paper from the paper machine all the way to the customer.
The invention is clarified in the following with a detailed description of a method for manufacturing the wrap according to the invention. Herein, a reference is made to the enclosed drawing illustrating an apparatus used for the implementation of the method.
According to the drawing, the apparatus comprises a mixing container 1 provided with a rotating mixer 2 and having a hopper opening 3 at its top. The components of the coating mix are fed in granulated form from a feed trough 4 via the opening 3 into the container 1. The composition of the coating mix can be, e.g., 70 % atactic polypropylene and 30 % isotactic polypropylene. The mixer 2 in the container 1 mixes the components, while the melting of the mix 5 is effected by heater elements provided within the container. An appropriate melting temperature is approx. 170 °C.
From the mixing container 1 the melted homogenized coating mix 5 is routed via a line 7 provided with a pump 6 to a feed hopper 8 of the coater. The coater comprises a rotating roll 9, which guides a paper web 10 of the base material for the web to be manufactured past an applicator nozzle head 11. The melted coating mix 5 is conveyed from the hopper 8 under pressure imposed by toothed feeder bars 12 through an exit slit 13 of the applicator head having a width essentially equal to that of the paper web 10. The nozzle head 11 is provided with a rotating coater bar 14, over which the coating mix to be applied flows to form a homogeneous layer on the paper web 10. The result is a one-side coated wrap 15 having an appropriate coat weight of approx. 15 g/m2.
The composition of the coating mix described above with 70 % atactic polypropylene and 30 % isotactic poly¬ propylene has been found advantageous in practice. Other applicable compositions of the coating mix can be referred to as a mix containing 50 % atactic polypropylene with 35 % isotactic polypropylene and 15 % wax, and a mix containing 70 % atactic polypropylene with 15 % isotactic polypropylene, 10 % wax and 5 % resin. The composition of the coating mix can, however, be varied within the limits expressed in the enclosed claims. For those versed in the art, it is evident that the different implementations of the invention can vary within the enclosed claims. Thus, according to the invention the base material of the wrap can be, in addition to paper, any other suitable fibrous material such as paperboard or linerboard. Moreover, the coating process is not limited to the procedure described above but can instead be a two- stage process, in which the first stage produces a homogenized coating mix broken into a granulate or blocks, while the second stage acting as the coating stage processes the granulate or block-formed coating mix by melting and application onto the base material.

Claims

WHAT IS CLAIMED IS:
1. A wrap composed of paper, paperboard or other similar fibrous base material coated with a coating mix containing polyolefin plastic, which coating provides for the vapour barrier characteristics of the wrap, c h a r a c t e r¬ i z e d in that the coating mix is composed of isotactic polypropylene with atactic polypropylene or amorphic poly- α-olefin acting as a plasticizer so that the needle penetration index of the coating mix is in the range 0.5...20 (0.1 mm/5 s) .
2. A wrap as claimed in claim 1, c h a r a c t e r- i z e d in that the needle penetration index of the coating mix is in the range 0.5...5 (0.1 mm/5 s) .
3. A wrap as claimed in claim 1, c h a r a c t e r- i z e d in that the coating mix composition has a proportion of the amorphic component, which is atactic polypropylene or poly-α-olefin, of at least 50 %.
4. A wrap as claimed in claim 1, c h a r a c t e ¬ i z e d in that the coating mix contains 50...95 %, preferably 60...80 % of atactic polypropylene, and 5...50 %, preferably 20...40 % of isotactic polypropylene.
5. A wrap as claimed in any of the foregoing claims,, c h a r a c t e r i z e d in that the coating mix additionally contains wax and/or resin.
6. A method for manufacturing a wrap, in which method a coating mix containing polyolefin plastic for generating a vapour barrier is applied onto paper, paperboard or other similar base material, c h a r a c t e r i z e d in that isotactic polypropylene is mixed with atactic polypropylene or amorphic poly-α-olefin so that the proportion of the amorphic component in the mix is at least 50 % and that the mix obtained is applied in a melted state onto the base material of the wrap.
7. A method as claimed in claim 6, c h a r a c t e r¬ i z e d in that 50...95 %, preferably 60...80 % of atactic polypropylene, and 5...50 %, preferably 20...40 % of isotactic polypropylene are intermixed and applied in a melted state onto the base material of the wrap.
8. A method as claimed in claim 6 or 7, c h a r a c¬ t e r i z e d in that the components of the coating mix are intermixed in granulate form, after which the mix is melted and applied via a nozzle onto a moving material web of paper, paperboard or other similar fibrous base material.
9. A coating mix for use according to the method as claimed in claims 6...8, c h a r a c t e r i z e d in that the mix contains isotactic polypropylene mixed with atactic polypropylene or poly-α-olefin so that the proportion of the amorphic component in the mix is at least 50 %.
10. A coating mix for use according to the method as claimed in claim 9, c h a r a c t e r i z e d in that mix contains 50...95 %, preferably 60...80 % of atactic polypropylene, and 5...50 %, preferably 20...40 % of isotactic polypropylene as well as wax and/or resin as possible additives.
PCT/FI1989/000203 1988-11-07 1989-11-03 Wrap, method for its manufacture and coating mix for use in the method WO1990005063A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI885123 1988-11-07
FI885123A FI85683C (en) 1988-11-07 1988-11-07 FOERPACKNINGSEMBALLAGE, ETT FOERFARANDE FOER DESS TILLVERKNING SAMT EN I FOERFARANDET ANVAEND BELAEGGNINGSKOMPOSITION.

Publications (1)

Publication Number Publication Date
WO1990005063A1 true WO1990005063A1 (en) 1990-05-17

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Family Applications (1)

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PCT/FI1989/000203 WO1990005063A1 (en) 1988-11-07 1989-11-03 Wrap, method for its manufacture and coating mix for use in the method

Country Status (3)

Country Link
FI (1) FI85683C (en)
FR (1) FR2638719B3 (en)
WO (1) WO1990005063A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3325562A (en) * 1965-03-10 1967-06-13 Sun Oil Co Hot melt adhesive comprising polypropylene and an aromatic hydrocarbon-aldehyde resin
GB1374467A (en) * 1970-10-30 1974-11-20 Veba Chemie Ag Heat fusible coating compositions
US3904806A (en) * 1973-02-28 1975-09-09 Du Pont Composite films of glassine-polyolefin copolymer resins exhibiting high oxygen barrier characteristics
EP0015306A2 (en) * 1979-03-13 1980-09-17 Montedison S.p.A. Manufactured articles coated with olefinic polymers and process for their preparation
JPS63283943A (en) * 1987-05-18 1988-11-21 Honshu Paper Co Ltd Moisture resistant carton

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3325562A (en) * 1965-03-10 1967-06-13 Sun Oil Co Hot melt adhesive comprising polypropylene and an aromatic hydrocarbon-aldehyde resin
US3370106A (en) * 1965-03-10 1968-02-20 Sun Oil Co Hot melt adhesive containing atactic polypropylene and polyethylene
GB1374467A (en) * 1970-10-30 1974-11-20 Veba Chemie Ag Heat fusible coating compositions
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Title
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Also Published As

Publication number Publication date
FR2638719A1 (en) 1990-05-11
FI85683B (en) 1992-02-14
FI885123A (en) 1990-05-08
FI85683C (en) 1992-05-25
FI885123A0 (en) 1988-11-07
FR2638719B3 (en) 1991-01-18

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