Structure, method for producing a structure, greaseproof paper, gas barrier paper, fragrance barrier paper and packaging material

Abstract

Provided are a structure in which a layer having heat-sealing properties is low in cracks and which is characterized by water vapor barrier properties, heat-sealing properties, and oxygen barrier properties, a method for producing such a structure, and greaseproof paper, gas barrier paper, fragrance barrier paper, and a packaging material each comprising such a structure. In the structure, an A layer, a B layer, and a C layer are stacked in this order on at least one surface of a paper base material. The A layer contains at least one selected from the group consisting of an olefin polymer, a styrene polymer, and a polyester polymer. The B layer contains a vinyl alcohol polymer. The C layer contains a polymer having a glass transition temperature of -100°C or more and 5°C or less.

Description

TECHNICAL FIELD

[0001] The present invention relates to a structure, a method for producing a structure, greaseproof paper, gas barrier paper, fragrance barrier paper and a packaging material. STATE OF THE ART

[0002] For packaging food, medical products, electronic components, and the like, packaging materials in which water vapor barrier properties and gas barrier properties (particularly oxygen barrier properties) are imparted to a paper base material have been conventionally used. Patent Documents 1 and 2 each disclose a packaging material in which a water vapor barrier layer, a gas barrier layer, and a heat-sealing layer are provided in this order on a paper base material. As such a packaging material, Patent Documents 1 and 2 each also disclose a packaging material in which a vinyl alcohol polymer is used in a gas barrier layer. DOCUMENTS OF THE PRIOR ART Patent documents Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-163675 Patent Document 2: Japanese Unexamined Patent Application Publication No. 2021-20398 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0003] In a packaging material such as those disclosed in Patent Documents 1 and 2, each layer is typically provided by coating a paper base material with it. However, in a case where a heat-sealing layer is provided on a surface of a gas-barrier layer containing a vinyl alcohol polymer, for example, a crack may occur in the formed film, and therefore, uniform heat-sealing properties cannot be obtained. Furthermore, the inventors also found that a crack in the heat-sealing layer causes deterioration of the water vapor barrier properties.

[0004] An object of the present invention is to provide a structure in which a layer having heat-sealing properties has only few cracks and which is characterized by water vapor barrier properties, heat-sealing properties and oxygen barrier properties, a method for producing such a structure, and greaseproof paper, gas barrier paper, fragrance barrier paper and a packaging material each comprising such a structure. MEANS TO SOLVE THE PROBLEMS

[0005] The above problems can be solved by providing one of the following configurations: (1) a structure in which an A layer, a B layer, and a C layer are stacked in this order on at least one surface of a paper base material, wherein the A layer contains at least one selected from the group consisting of an olefin polymer, a styrene polymer, and a polyester polymer, the B layer contains a vinyl alcohol polymer, and the C layer contains a polymer having a glass transition temperature of -100°C or more and 5°C or less; (2) the structure according to (1), wherein the C layer has a melting point of 120 °C or less; (3) the structure according to (1) or (2), wherein the A layer contains the olefin polymer, and the olefin polymer contains an olefin-unsaturated carboxylic acid polymer; (4) the structure according to any one of the embodiments (1) to (3), wherein the A layer further contains soapstone; (5) the structure according to (4), wherein the content of soapstone in the A layer is 1 mass% or more and 80 mass% or less; (6) the structure according to any one of the embodiments (1) to (5), wherein the vinyl alcohol polymer is an ethylene-modified vinyl alcohol polymer; (7) the structure according to any one of aspects (1) to (6), wherein the polymer having a glass transition temperature of -100 °C or more and 5 °C or less is a styrene-acrylic copolymer; (8) the structure according to any one of the embodiments (1) to (7), wherein the C layer further contains a wax; (9) the structure according to (8), wherein the content of the wax in the C layer is 0.1 mass% or more and 30 mass% or less; (10) the structure according to (8) or (9), wherein the wax contains paraffin wax; (11) the structure according to (10), wherein the content of the paraffin wax in the C layer is 1 mass% or more and 30 mass% or less; (12) the structure according to any one of the aspects (1) to (11), wherein the vinyl alcohol polymer consists of two or more kinds of vinyl alcohol polymers having different degrees of polymerization; (13) the structure according to any one of the embodiments (1) to (12), wherein the A layer contains at least two selected from the group consisting of the olefin polymer, the styrene polymer and the polyester polymer; (14) the structure according to any one of the embodiments (1) to (13), wherein the C layer contains two or more kinds of polymers; (15) a method of manufacturing the structure according to any one of the embodiments (1) to (14), comprising: providing at least one of the A layer, the B layer, or the C layer using a curtain coater; (16) greaseproof paper comprising the structure according to any one of the embodiments (1) to (14); (17) Gas barrier paper comprising the structure according to any one of the embodiments (1) to (14); (18) Fragrance barrier paper comprising the structure according to any one of embodiments (1) to (14); and (19) a packaging material comprising at least one selected from the group consisting of the greaseproof paper according to (16), the gas barrier paper according to (17) and the fragrance barrier paper according to (18). EFFECTS OF THE INVENTION

[0006] According to the present invention, there can be provided a structure in which a layer having heat-sealing properties has few cracks and which is characterized by water vapor barrier properties, heat-sealing properties and oxygen barrier properties, a method for producing such a structure, and greaseproof paper, gas barrier paper, fragrance barrier paper and a packaging material each comprising such a structure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view illustrating a structure according to an embodiment of the present invention. DESCRIPTION OF THE EMBODIMENTSStructure

[0007] An embodiment of the present invention is a structure in which an A layer, a B layer, and a C layer are stacked in this order on at least one surface of a paper base material, wherein the A layer contains at least one selected from the group consisting of an olefin polymer, a styrene polymer, and a polyester polymer, the B layer contains a vinyl alcohol polymer, and the C layer contains a polymer having a glass transition temperature of -100°C or more and 5°C or less.

[0008] In this structure, a layer with heat-sealing properties exhibits little cracking, and the structure is characterized by water vapor barrier properties, heat-sealing properties, and oxygen barrier properties. Although the reasons why this structure exhibits such effects are not clear, the following reasons may exist. The oxygen barrier properties can be improved by using a vinyl alcohol resin with excellent oxygen barrier properties in the B layer. However, the vinyl alcohol polymer is a resin that changes relatively significantly due to swelling and shrinkage; therefore, in the case where the C layer is provided on the B layer containing the vinyl alcohol polymer, the C layer may not follow the swelling and shrinkage of the B layer and may crack. Therefore, the use of the polymer with a glass transition temperature of -100°C or more and 5°C or less, i.e.A polymer with a low glass transition temperature in the C layer ensures that the C layer adequately follows the swelling and shrinkage of the B layer. As a result, cracks in the C layer can be prevented in the structure, and the water vapor barrier properties can be improved.

[0009] As in Fig.1, a structure 10 according to one embodiment of the present invention comprises a paper base material 11, an A layer 12, a B layer 13, and a C layer 14. The structure 10 is a layered arrangement in which the A layer 12, the B layer 13, and the C layer 14 are arranged one on top of the other in this order on one surface of the paper base material 11. In the structure 10, the paper base material 11 and the A layer 12, the A layer 12 and the B layer 13, and the B layer 13 and the C layer 14 are each directly arranged on top of one another. In the structure 10, the C layer 14 is also an outermost layer. The structure 10 may be coated paper.

[0010] In an embodiment different from that of structure 10 in Fig.1, the A layer, the B layer, and the C layer may be stacked on top of one another in this order on both surfaces of the paper base material. The A layer, the B layer, and the C layer may be stacked on top of one another in this order on one surface of the paper base material, while one or more of the A layer, the B layer, the C layer, and other layers may be stacked on the other surface of the paper base material. Another layer or layers may be present between the paper base material and the A layer, and / or between the A layer and the B layer, and / or between the B layer and the C layer, and / or on a surface of the C layer. Each component of the structure will be described in detail below. Paper base material

[0011] As the paper base material, general paper containing plant-based pulp as the main component can be used. Note that the "main component" as referred to herein refers to a component having the highest content by mass. The paper base material may contain, in addition to the pulp, a sizing agent, a filler, a paper reinforcing agent, a yield-improving agent, a pH modifier, a drainage-improving agent, a water-preserving agent, a plasticizer, an antistatic agent, a defoaming agent, a sludge control agent, a dye, a pigment, and / or the like.

[0012] Examples of the paper base material include kraft paper, wood-free paper, wood-containing paper, alkaline paper, a cardboard, glassine paper, semi-glassine paper, parchment paper and the like, and wood-free paper is preferred.

[0013] The basis weight (mass per unit area) of the paper base material is preferably 20 g / m 2 or more and 500 g / m 2 or less, preferably 30 g / m 2 or more and 300 g / m 2 or less, more preferably 40 g / m 2 or more and 200 g / m 2 or less and even more preferably 50 g / m 2 or more and 100 g / m 2 or less.

[0014] The density of the paper base material is preferably 0.5 g / cm 3 or more and 1.2 g / cm 3 or less and more preferably 0.6 g / cm 3 or more and 1.0 g / cm 3 or less.

[0015] The paper base material can be produced by a known process. A commercial product can also be used as the paper base material. A-shift

[0016] The A layer is a layer located between the paper base material and the B layer. The A layer can be placed directly on the paper base material. Polymer (a)

[0017] The A layer contains at least one selected from the group consisting of an olefin polymer, a styrene polymer, and a polyester polymer (hereinafter also referred to as "polymer (a)"). When the A layer contains the polymer (a) with relatively high hydrophobic properties in this way, the A layer can exhibit favorable water vapor barrier properties and the like. The polymer (a) is preferably a main component of the A layer. One type or two or more types of polymers can be used as the polymer (a). olefin polymer

[0018] An olefin polymer is a polymer containing an olefin as a monomer. The olefin polymer may be a polyolefin, which is a polymer of one or more types of olefins, or it may be a copolymer of one or more types of olefins and one or more types of monomers other than olefins.

[0019] Examples of the olefin include α-olefins such as ethylene, propylene, n-butene, isobutylene and the like.

[0020] Examples of the monomers other than olefins constituting the olefin polymer include an unsaturated carboxylic acid compound, a diene compound, vinyl ether, a vinyl halide, a vinylidene halide, an allyl compound, and the like, and an unsaturated carboxylic acid compound is preferred.

[0021] The term "unsaturated carboxylic acid compound" refers to an unsaturated carboxylic acid and a compound in which a hydrogen atom of a carboxyl group constituting an unsaturated carboxylic acid is substituted by another atom or group. This means that, in addition to unsaturated carboxylic acids, the unsaturated carboxylic acid compound also includes unsaturated carboxylic acid esters, unsaturated carboxylates, and the like. The unsaturated carboxylic acid compound is preferably a monomer having a carboxyl group or a salt thereof.

[0022] Examples of the unsaturated carboxylic acid compound include unsaturated carboxylic acids such as (meth)acrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, and butenetricarboxylic acid; unsaturated carboxylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, monoethyl itaconic acid, and monobutyl fumaric acid; unsaturated carboxylates such as sodium (meth)acrylate; and the like. Note that "(meth)acrylic acid" refers to acrylic acid and methacrylic acid.

[0023] As the olefin polymer, a polyolefin and an olefin-unsaturated carboxylic acid copolymer are preferred, and an olefin-unsaturated carboxylic acid copolymer is more preferred. An olefin-unsaturated carboxylic acid copolymer refers to a copolymer of one or two or more types of olefins and one or two or more types of unsaturated carboxylic acid compounds. Among olefin-unsaturated carboxylic acid copolymers, an olefin-unsaturated carboxylic acid copolymer is preferred, which is a copolymer of one or two or more types of olefins and one or two or more types of unsaturated carboxylic acids.

[0024] Examples of the olefin-unsaturated carboxylic acid copolymer include an ethylene-(meth)acrylic acid copolymer, an ethylene-methyl (meth)acrylate copolymer, an ethylene-ethyl (meth)acrylate copolymer, an ethylene-butyl (meth)acrylate copolymer, and the like; among these, an ethylene-(meth)acrylic acid copolymer is preferred. Furthermore, a copolymer of ethylene and an unsaturated carboxylic acid compound is also preferred. Such a copolymer may be further copolymerized with another monomer copolymerizable with the olefin and the unsaturated carboxylic acid compound. Styrene polymer

[0025] A styrenic polymer is a polymer containing a styrenic compound as a monomer. A styrenic compound refers to styrene and a compound in which a hydrogen atom contained in styrene is substituted by another atom or group. Examples of a styrenic compound include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, and the like, and styrene is preferred.

[0026] Examples of a styrene copolymer include polystyrene, a styrene-acrylic copolymer, a styrene-butadiene copolymer, and the like.

[0027] The styrene-acrylic copolymer is a copolymer of the above-mentioned styrene compound and an acrylic compound. The acrylic compound refers to a (meth)acrylic acid and a compound in which a hydrogen atom of a carboxyl group constituting a (meth)acrylic acid is substituted by another atom or group. Examples of the acrylic compound include a (meth)acrylic acid, (meth)acrylic acid ester, (meth)acrylate, and the like. Examples of the (meth)acrylic acid ester include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and the like. Examples of the (meth)acrylate include sodium (meth)acrylate and the like.

[0028] Examples of the styrene-acrylic copolymer include a styrene-(meth)acrylic acid copolymer, a styrene-(meth)acrylic acid ester copolymer, a styrene-(meth)acrylate copolymer, and the like. The styrene-acrylic copolymer may be further copolymerized with another monomer.

[0029] The styrene-butadiene copolymer is a copolymer of the above-mentioned styrene compound and a butadiene compound. The butadiene compound refers to a butadiene and a compound in which a hydrogen atom contained in a butadiene is substituted by another atom or group. Examples of the butadiene compound include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and the like, and 1,3-butadiene is preferred.

[0030] A styrene-butadiene copolymer is preferred as the styrene-butadiene copolymer. The styrene-butadiene copolymer may also be copolymerized with another monomer.

[0031] A styrene-acrylic copolymer and a styrene-butadiene copolymer are preferred as the styrene polymer. Polyester polymer

[0032] A polyester polymer is a polymer in which one or two or more types of monomers are polymerized through an ester bond. Examples of the polyester polymer include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polyglycolic acid, aromatic liquid crystal polyester, and the like.

[0033] Among the examples of the polymer (a), an olefin polymer and a styrene polymer are preferable in view of water vapor barrier properties and the like, and an olefin polymer is more preferable.

[0034] The lower limit of the content of the polymer (a) in the A layer is preferably 20 mass%, more preferably 40 mass%, and may be 60 mass%, 70 mass%, 80 mass%, or 90 mass%. On the other hand, the upper limit of this content may be 100 mass%, or may be 99 mass%, 90 mass%, 80 mass%, or 60 mass%. Other component(s) and the like in the A layer

[0035] The A layer preferably contains a layered inorganic compound. When the A layer contains the layered inorganic compound, the water vapor barrier properties and the like of the structure can be further improved.

[0036] Examples of layered inorganic compounds include mica, steatite, montmorillonite, kaolinite, vermiculite, smectite, hectorite, taeniolite, acid clay, and the like. Given its water vapor barrier properties, soapstone is preferred as a layered inorganic compound used in the A layer. One type or two or more types of layered inorganic compounds can be used.

[0037] In the case where the A layer contains the layered inorganic compound such as soapstone or the like, the lower limit of the content of the layered inorganic compound in the A layer is preferably 1 mass%, more preferably 5 mass%, and even more preferably 10 mass%, 20 mass%, or 30 mass%. On the other hand, the upper limit of this content is preferably 80 mass%, more preferably 70 mass%, and even more preferably 60 mass%, 50 mass%, or 40 mass%. By setting the content of the layered inorganic compound in the A layer within the above range, the water vapor barrier properties and the like can be further improved.

[0038] The A layer may further contain component(s) other than the polymer (a) and the layered inorganic compound. Examples of the other component(s) include a resin other than the polymer (a), a dispersant, a surfactant, a defoaming agent, a dye, a thickener, and the like. Note that the total content of the polymer (a) and the optional layered inorganic compound in the A layer is preferably 90 mass% or more, and more preferably 95 mass% or more, or 99 mass% or more. In addition, the content of a cationic resin in the A layer may preferably be 10 mass% or less, and more preferably may be 5 mass% or less, 1 mass% or less, or 0.5 mass% or less.

[0039] The mass per unit area of ​​a layer of the A layer is preferably 1 g / m 2 or more and 100 g / m 2 or less, preferably 3 g / m 2 or more and 50 g / m2 or less, more preferably 5 g / m 2 or more and 30 g / m 2 or less, even more preferably 7 g / m 2 or more and 20 g / m 2 or less and particularly preferably 9 g / m 2 or more and 15 g / m 2 or less. If the mass per unit area of ​​a layer of the A layer is at or above the lower limit, the water vapor barrier properties and the like can be further improved. On the other hand, if the mass per unit area of ​​a layer of the A layer is at or below the upper limit, the thickness of the structure, for example, can be reduced. B-layer

[0040] The B layer is a layer located between the A layer and the C layer. The B layer can be a layer located directly on top of the A layer. Polymer (b)

[0041] The B layer contains a vinyl alcohol polymer (hereinafter also referred to as "polymer (b)"). When the structure comprises the B layer containing the polymer (b), excellent oxygen barrier properties can be exhibited. The polymer (b) is preferably a main component of the B layer. The polymer (b) is a polymer having a vinyl alcohol unit (-CH2-CHOH-). The polymer (b) is typically obtained by saponification of a vinyl ester polymer. One type or two or more types of polymers (b) can be used.

[0042] The lower limit of the saponification degree of the polymer (b) is preferably 80 mol%, more preferably 90 mol%, and may even more preferably be 95 mol%, 97 mol%, 98 mol%, or 99 mol%. When the saponification degree is at or above the lower limit, oxygen barrier properties and the like can be further improved. On the other hand, the upper limit of the saponification degree may be 100 mol% or 99.9 mol%. The saponification degree of the polymer (b) is measured according to JIS K 6726:1994.

[0043] The viscosity-average degree of polymerization of the polymer (b) is preferably 200 or more and 3000 or less. The lower limit of the viscosity-average degree of polymerization may be 300, 500, or 800. On the other hand, the upper limit of the viscosity-average degree of polymerization may be 2500, 2000, 1200, or 800. When the viscosity-average degree of polymerization of the polymer (b) is within the above range, the oxygen barrier properties and the like can be further improved, and the coatability when providing the B layer by coating, the strength of the B layer, and the like can also be optimized.

[0044] The viscosity-average degree of polymerization of the polymer (b) is measured according to JIS K 6726:1994. Specifically, the intrinsic viscosity [η] (L / g) of the polymer (b) is measured in water at 30 °C, and the value of the intrinsic viscosity [η] is used to calculate a viscosity-average degree of polymerization P according to the following formula. Note that in a case where the saponification degree of the polymer (b) is less than 99.5 mol%, the intrinsic viscosity [η] is measured after the polymer is saponified until the saponification degree reaches 99.5 mol% or more. P=([η]×104 / 8.29)(1 / 0.62)

[0045] The polymer (b) may contain a monomer unit derived from a monomer other than the vinyl alcohol unit and a vinyl ester unit. Examples of the other monomer include α-olefins such as ethylene, propylene, n-butene, and isobutylene; (meth)acrylic acids and salts thereof; (meth)acrylic acid esters; (meth)acrylamides; (meth)acrylamide derivatives such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, diacetone(meth)acrylamide, (meth)acrylamidepropanesulfonic acids and salts thereof, (meth)acrylamidepropyldimethylamines and salts or quaternary salts thereof, and N-methylol(meth)acrylamides and derivatives thereof; vinyl ethers such as N-(meth)acrylamide, N-(meth)acrylamide, N-(meth)acrylamide, N,N-dimethyl(meth)acrylamide, diacetone(meth)acrylamide, (meth)acrylamidepropanesulfonic acids and salts thereof, (meth)acrylamidepropyldimethylamines and salts or quaternary salts thereof, and N-methylol(meth)acrylamides and derivatives thereof; B. Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; nitriles, such as acrylonitrile and methacrylonitrile; vinyl halides, such as vinyl chloride and vinyl fluoride; vinylidene halides, such asVinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid, and salts or esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate; and the like.

[0046] The other monomer is preferably an α-olefin, and more preferably ethylene. That is, the polymer (b) is preferably an α-olefin-modified vinyl alcohol polymer, and more preferably an ethylene-modified vinyl alcohol polymer. Using such a modified vinyl alcohol polymer, the oxygen barrier properties and the like can be further improved.

[0047] The lower limit of the percentage content of an α-olefin unit with respect to all monomer units in the α-olefin-modified vinyl alcohol polymer is preferably 0.1 mol%, more preferably 1 mol%, and may be 2 mol%, 5 mol%, or 7 mol%. On the other hand, the upper limit of this percentage content may be 30 mol%, or may be 20 mol%, 15 mol%, or 12 mol%. Note that the percentage content of the α-olefin unit with respect to all monomer units is also referred to as the degree of α-olefin modification. For example, the percentage content of an ethylene unit with respect to all monomer units is also referred to as the degree of ethylene modification.

[0048] The total percentage content of the vinyl alcohol unit, the vinyl ester unit and the optional α-olefin unit with respect to all monomer units in the polymer (b) is preferably 95 mol% or more, more preferably 99 mol% or more, and may be 100 mol%.

[0049] A mixture of two or more types of polymers (b) can be used. For example, the polymer (b) may consist of two or more types of vinyl alcohol polymers with different degrees of polymerization. A vinyl alcohol polymer with a low degree of polymerization has low viscosity and excellent coatability. On the other hand, a vinyl alcohol polymer with a high degree of polymerization has excellent strength and the like. Accordingly, by using a mixture of two or more types of vinyl alcohol polymers with different degrees of polymerization, these properties can be well balanced. Note that the mixture consisting of two or more types of vinyl alcohol polymers with different degrees of polymerization may exhibit two or more peaks in a molecular weight distribution curve obtained by GPC (gel permeation chromatography) analysis.

[0050] The lower limit of the content of the polymer (b) in the B layer is preferably 70 mass%, more preferably 80 mass%, and even more preferably 90 mass%. By setting the content of the polymer (b) in the B layer to a value at or above the lower limit, the oxygen barrier properties and the like can be further improved. On the other hand, the upper limit of this content may be 100 mass%, 99 mass%, or 97 mass%. Other component(s) and the like in the B layer

[0051] The B layer preferably contains a layered inorganic compound. When the B layer contains the layered inorganic compound, the oxygen barrier properties and the like of the structure can be further improved.

[0052] Examples of the layered inorganic compound are similar to those listed in the description of the A layer. Considering oxygen barrier properties and the like, mica is preferred as the layered inorganic compound used in the B layer. One type or two or more types of layered inorganic compounds can be used.

[0053] In the case where the B layer contains the layered inorganic compound such as mica or the like, the lower limit of the content of the layered inorganic compound in the B layer is preferably 1 mass%, and more preferably 3 mass%. On the other hand, the upper limit of this content is preferably 30 mass%, more preferably 20 mass%, and even more preferably 10 mass%. By setting the content of the layered inorganic compound in the B layer within the above range, the oxygen barrier properties and the like can be further improved.

[0054] The B layer may further contain component(s) other than the polymer (b) and the layered inorganic compound. Examples of the other component(s) include a resin other than the polymer (b), a dispersant, a surfactant, a defoaming agent, a dye, a thickener, and the like. Note that the total content of the polymer (b) and the optional layered inorganic compound in the B layer is preferably 90 mass% or more, and more preferably 95 mass% or more or 99 mass% or more.

[0055] The mass per unit area of ​​a layer of the B layer is preferably 0.3 g / m 2 or more and 20 g / m 2 or less, more preferably 0.5 g / m 2 or more and 10 g / m 2 or less, more preferably 1 g / m 2 or more and 7 g / m 2 or less and even more preferably 2 g / m 2 or more and 5 g / m 2or less. If the mass per unit area of ​​a layer of the B layer is at or above the lower limit, the oxygen barrier properties and the like can be further improved. On the other hand, if the mass per unit area of ​​a layer of the B layer is at or below the upper limit, the thickness of the structure, for example, can be reduced. C-layer

[0056] The C layer is a layer opposite the A layer with respect to the B layer. The C layer can be a layer located directly on top of the B layer. Furthermore, the C layer can be an outermost layer. Polymer (c)

[0057] The C layer contains a polymer with a glass transition temperature of -100°C or more and 5°C or less (hereinafter also referred to as "polymer (c)"). The polymer (c) is preferably a main component of the C layer. One type or two or more types of polymers (c) can be used.

[0058] The upper limit of the glass transition temperature of the polymer (c) is 5°C, preferably 3°C, more preferably 2°C, and even more preferably 1°C, 0°C, -1°C, -3°C, -5°C, or -10°C. When the glass transition temperature of the polymer (c) is at or below the upper limit, cracks in the C layer can be prevented and the water vapor barrier properties can be improved. On the other hand, the lower limit of this glass transition temperature is -100°C, may be -80°C, or may be -60°C, -50°C, or -40°C.

[0059] The upper limit of the melting point of the polymer (c) may be 120°C, and is preferably 100°C, more preferably 85°C, even more preferably 80°C, and even more preferably 75°C, 70°C, or 65°C. When the melting point of the polymer (c) is at or below the upper limit, the heat-sealing properties can be improved. The melting point of the polymer (c) may be lower than 80°C. On the other hand, the lower limit of this melting point is preferably 30°C, more preferably 40°C, and even more preferably 50°C.

[0060] The glass transition temperature and melting point of the polymer (c) are measured by differential scanning calorimetry (DSC). Specifically, they can be measured using a method described in EXAMPLES.

[0061] The polymer (c) is not particularly limited as long as it is a polymer having a glass transition temperature of -100°C or more and 5°C or less. For example, among the olefin polymer, the styrene polymer, and the polyester polymer in the description of the polymer (a), a polymer or the like having a glass transition temperature of -100°C or more and 5°C or less can be used as the polymer (c).

[0062] As the polymer (c), an olefin polymer and a styrene polymer are preferred, a styrene polymer is more preferred, a styrene-acrylic copolymer and a styrene-butadiene copolymer are even more preferred, a styrene-acrylic copolymer is even more preferred, and a styrene-(meth)acrylic acid ester copolymer is particularly preferred. Furthermore, among olefin polymers, an olefin-unsaturated carboxylic acid copolymer is preferred, an olefin-unsaturated carboxylic acid copolymer is more preferred, and an ethylene-(meth)acrylic acid copolymer is even more preferred. Also preferred as the polymer (c) is a copolymer of a hydrocarbon monomer and an acrylic compound. Examples of the hydrocarbon monomer include the above-described olefins, styrene compounds, and the like. By using such a polymer as the polymer (c), water vapor barrier properties, heat-sealing properties, and the like can be further improved.Concrete modes of the olefin polymer and the styrene polymer used as the polymer (c) are similar to those of the olefin polymer and the styrene polymer in the polymer (a) described above.

[0063] In one embodiment of the present invention, polymer (a) and polymer (c) may be polymers of the same type or different types of polymers. For example, to optimize the functions of the A layer and the C layer, different types of polymers may be used as polymer (a) and polymer (c).

[0064] The lower limit of the content of the polymer (c) in the C layer is preferably 50 mass%, more preferably 60 mass%, even more preferably 70 mass%, and even more preferably 80 mass%, 85 mass%, or 90 mass%. On the other hand, the upper limit of this content is preferably 100 mass%, more preferably 99 mass%, and even more preferably 95 mass%. Other component(s) and the like in the C layer

[0065] The C layer preferably contains a wax. When the C layer contains the wax, the water vapor barrier properties, for example, can be further improved. When the C layer contains the wax, grease resistance and the like also tend to improve.

[0066] The wax preferably contains paraffin wax. For example, paraffin wax containing ordinary paraffin with 20 or more and 40 or fewer carbon atoms and a molecular weight of 300 or more and 500 or less as the main component can be used. A commercial product can be used as paraffin wax.

[0067] In the case where the C layer contains the wax, the lower limit of the content of the wax in the C layer may be, for example, 0.1 mass%, and is preferably 1 mass%, more preferably 3 mass%, and even more preferably 5 mass%. On the other hand, the upper limit of this content may be, for example, 30 mass%, and is preferably 20 mass%, more preferably 15 mass%, and even more preferably 12 mass%. By setting the content of the wax in the C layer within the above range, the water vapor barrier properties and the like can be further improved. In addition, in the case where the C layer contains the paraffin wax, the lower limit of the content of the paraffin wax in the C layer may be, for example, 0.1 mass%, and is preferably 1 mass%, more preferably 3 mass%, and even more preferably 5 mass%. On the other hand, the upper limit of this content may be, for example, 30 mass%, and is preferably 20 mass%, more preferably 15 mass%, and even more preferably 12 mass%.By adjusting the content of paraffin wax in the C layer in the above range, the water vapor barrier properties and the like can be further improved.

[0068] The C layer may further contain component(s) other than the polymer (c) and the wax. Examples of the other component(s) include a resin other than the polymer (c), a dispersant, a surfactant, a defoaming agent, a dye, a thickener, and the like. The C layer may contain two or more types of polymers. The two or more types of polymers that may be contained in the C layer may be a combination of the polymer (c) and another polymer, or two or more types of polymers (c). Note that the total content of the polymer (c) and the optional wax in the C layer is preferably 90 mass% or more, and more preferably 95 mass% or more or 99 mass% or more.

[0069] In particular, it is preferable that the C layer substantially contains no vinyl alcohol polymer. The content of the vinyl alcohol polymer in the C layer is preferably 10 mass % or less, more preferably 3 mass % or less, further preferably 1 mass % or less, and even more preferably 0.1 mass % or less. By reducing the content of the vinyl alcohol polymer in the C layer in this way, an increase in the viscosity of a C layer-forming coating liquid when providing the C layer by coating can be prevented, and the C layer can be formed efficiently.

[0070] The C layer preferably has a melting point of 120°C or less. The upper limit of the melting point of the C layer is preferably 100°C, more preferably 85°C, even more preferably 80°C, and even more preferably 75°C, 70°C, or 65°C. When the melting point of the C layer is at or below the upper limit, heat-sealing properties can be improved. The melting point of the C layer may be lower than 80°C. On the other hand, the lower limit of this melting point is preferably 30°C, more preferably 40°C, and even more preferably 50°C. The melting point of the C layer is measured by differential scanning calorimetry (DSC). Note that in a case where one of the components (polymer (c) and other optional component(s)) of the C layer has a predetermined melting point T, the C layer also typically has the predetermined melting point T.

[0071] The mass per unit area of ​​a layer of the C layer is preferably 1 g / m 2 or more and 100 g / m 2 or less, preferably 3 g / m 2 or more and 50 g / m 2 or less, more preferably 5 g / m 2 or more and 30 g / m 2 or less, even more preferably 7 g / m 2 or more and 20 g / m 2 or less and particularly preferably 9 g / m 2 or more and 15 g / m 2 or less. If the mass per unit area of ​​a layer of the C layer is at or above the lower limit, the water vapor barrier properties and the like can be further improved. On the other hand, if the mass per unit area of ​​a layer of the C layer is at or below the upper limit, the thickness of the structure, for example, can be reduced.

[0072] The structure can be conveniently used as greaseproof paper, gas-barrier paper, fragrance-barrier paper, packaging material, or the like. The structure can also be used in a state where the structure is formed by heat-sealing the C layers into a predetermined shape (for example, a pocket shape). A heat-sealing method is not particularly limited and can be a known method; for example, heat-sealing can be performed using a hot-plate heat sealer, an impulse sealer, an ultrasonic sealer, a friction heat sealer, a dielectric heat sealer, or the like. Method for producing the structure

[0073] A method for manufacturing the structure according to an embodiment of the present invention is not particularly limited, and the structure can typically be manufactured such that the A layer, the B layer, and the C layer are provided in this order by coating on the paper base material. Specifically, for example, the A layer is provided such that a surface of the paper base material is coated with an A layer-forming coating liquid and then drying is performed. Next, the B layer is provided such that a surface of the A layer is coated with a B layer-forming coating liquid and then drying is performed. Next, the C layer is provided such that a surface of the B layer is coated with a C layer-forming coating liquid and then drying is performed.In this way, the structure can be preserved. Drying does not necessarily have to be performed after coating with each coating liquid, and a simultaneous multi-layer coating process can be used.

[0074] Coating with any coating liquid can be performed by a conventionally known method. For example, coating can be performed using a blade coater, a bar coater, an air knife coater, a slot die coater, a gravure coater, a microgravure coater, a gate roll coater, a curtain coater, or the like. Among these, a curtain coater is preferably used.

[0075] That is, the method for manufacturing the structure according to one embodiment of the present invention includes a step of providing at least one of the A layer, the B layer, or the C layer using a curtain coater. In the manufacturing method, the A layer, the B layer, and the C layer are preferably all provided using a curtain coater.

[0076] A method for drying each coating liquid that has been applied is not particularly limited, and for example, a hot air dryer, an infrared dryer, a gas burner, a hot plate, or the like can be used.

[0077] A solvent or a dispersion medium of the coating liquid for forming each layer is not particularly limited; water or an organic solvent (ethanol, isopropyl alcohol, methyl ethyl ketone, toluene, or the like) can be used, and water is preferred.

[0078] The solid content (solid concentration) in the coating liquid for forming each layer is not particularly limited and may, for example, be 3 mass% or more and 70 mass% or less, may be 5 mass% or more and 60 mass% or less, or may be 10 mass% or more and 50 mass% or less. Greaseproof paper

[0079] Greaseproof paper according to one embodiment of the present invention comprises the structure according to one embodiment of the present invention. The greaseproof paper according to one embodiment of the present invention may consist of the structure according to one embodiment of the present invention.

[0080] Greaseproof paper is characterized by its water vapor barrier properties and oxygen barrier properties, and if it has a heat-sealed section, its adhesive properties are also advantageous. Greaseproof paper is useful, for example, as a packaging material used in serving oily foods such as fries, fried chicken, etc., as a packaging material for wrapping butter, etc., or as a cooking paper used in baking bread, cakes, etc.

[0081] The grease resistance (KIT value) of the greaseproof paper is preferably 5 or more, and more preferably 6 or 7 or more. This grease resistance is defined as the value obtained when the surface of the C layer is measured by a TAPPI UM-557 method (Kit test). Gas barrier paper

[0082] Gas barrier paper according to an embodiment of the present invention comprises the structure according to an embodiment of the present invention. The gas barrier paper according to an embodiment of the present invention may consist of the structure according to an embodiment of the present invention.

[0083] The gas-barrier paper is characterized by both oxygen-barrier and water-vapor-barrier properties, and if it has a heat-sealed section, its adhesive properties are also advantageous. The gas-barrier paper is suitably used, for example, as packaging materials for food, agrochemicals, chemicals, cosmetics, medical products, electronic components, clothing, etc.

[0084] The oxygen permeability of the gas barrier paper is preferably 10 cc / m 2 24 hours or less, preferably 5 cc / m 224 hours or less and more preferably 3 cc / m 2 24 hours or less. Oxygen permeability is defined as the value measured under conditions including 23°C / 65% RH. Fragrance barrier paper

[0085] Fragrance barrier paper according to an embodiment of the present invention comprises the structure according to an embodiment of the present invention. The fragrance barrier paper according to an embodiment of the present invention may consist of the structure according to an embodiment of the present invention.

[0086] The fragrance barrier paper is characterized by both oxygen barrier properties and water vapor barrier properties, and if it has a heat-sealed section, its adhesive properties are also advantageous. The fragrance barrier paper is suitably used, for example, as packaging materials for scented items such as sweets, tea leaves, coffee, spices, tobacco, cosmetics, perfumes, etc. The fragrance barrier paper is also useful as packaging materials or the like for other foodstuffs, agrochemicals, chemicals, clothing, etc.

[0087] Generally, when oxygen permeability is low, the fragrance-blocking properties also tend to improve. The oxygen permeability of fragrance-barrier paper is preferably 10 cc / m 2 24 hours or less, preferably 5 cc / m 2 24 hours or less and more preferably 3 cc / m 224 hours or less. Packaging material

[0088] A packaging material according to an embodiment of the present invention comprises at least one selected from the group consisting of the greaseproof paper according to an embodiment of the present invention, the gas-barrier paper according to an embodiment of the present invention, and the fragrance-barrier paper according to an embodiment of the present invention. The packaging material according to an embodiment of the present invention may comprise the structure according to an embodiment of the present invention.

[0089] The packaging material is characterized by water vapor barrier properties and oxygen barrier properties, and if it has a heat-sealed section, its adhesive properties are also advantageous. The packaging material is suitably used, for example, as packaging materials for food, agrochemicals, chemicals, cosmetics, medical products, electronic components, clothing, etc. EXAMPLES

[0090] Hereinafter, the present invention will be described in more detail by way of example, and the present invention is not limited to the examples. Production Example 1: Production of PVA-1

[0091] In a reaction vessel equipped with a stirrer, a nitrogen inlet, and an initiator addition port, 1050 g of vinyl acetate and 1.950 g of methanol were added and heated to 60 °C. Then, the system was replaced with nitrogen by bubbling nitrogen for 30 min. After the temperature in the reaction vessel was adjusted to 60 °C, 1.6 g of azobisisobutyronitrile (AIBN) was added as a polymerization initiator to initiate polymerization. When the polymerization rate reached 50% in 3 h, cooling was performed to stop the polymerization. Unreacted vinyl acetate monomers were removed, and methanol was added to obtain a polyvinyl acetate (PVAc) solution in methanol (concentration: 30 wt%).To 400 g of the PVAc solution in methanol (PVAc in the solution: 120 g), 55.8 g of a 10% NaOH solution in methanol (molar ratio [MR] of the amount of NaOH with respect to the vinyl acetate unit in the PVAc: 0.10) was added, and saponification was carried out at 40 °C. After adding the NaOH solution in methanol, the resulting gel was crushed in a crusher and subjected to a saponification reaction for a total of 1 h. Thereafter, 1000 g of methyl acetate was added to neutralize the remaining alkali. A phenolphthalein indicator was used to confirm that the neutralization was complete. 1000 g of methanol was then added to a white solid obtained by filtration, and the resulting mixture was left at room temperature for 3 h and then washed.After the washing process was repeated three times, a solid obtained by centrifugal dehydration was left in a dryer at 70 °C for 2 days and dried to obtain a vinyl alcohol polymer (PVA-1). Production Example 2: Production of PVA-2

[0092] In a 5 L pressure reaction vessel equipped with a stirrer, a nitrogen inlet, an ethylene inlet, and an initiator addition port, 1440 g of vinyl acetate and 1560 g of methanol were added and heated to 60 °C. Then, the interior of the system was replaced with nitrogen by bubbling for 30 min. Next, ethylene was introduced so that the reaction vessel pressure reached 7.8 kg / cm 2After the temperature in the reaction vessel was adjusted to 60 °C, 2.0 g of AIBN was added as a polymerization initiator to start polymerization. During the polymerization, ethylene was introduced to maintain the reaction vessel pressure at 7.8 kg / cm 2and maintaining the polymerization temperature at 60 °C. When the polymerization rate reached 50% in 3 h, cooling was performed to stop the polymerization. After the reaction vessel was opened to remove ethylene, bubbling with nitrogen gas was continued. Next, unreacted vinyl acetate monomers were removed under reduced pressure, and methanol was added to obtain an ethylene-vinyl acetate copolymer solution in methanol (concentration: 30 wt%). To 400 g of the ethylene-vinyl acetate copolymer solution in methanol (ethylene-vinyl acetate copolymer in the solution: 120 g), 55.8 g of a 10% NaOH solution in methanol (molar ratio [MR] of the amount of NaOH with respect to the vinyl acetate unit in the ethylene-vinyl acetate copolymer: 0.10) was added, and saponification was carried out at 40 °C.After adding the NaOH solution in methanol, the resulting gel was crushed in a crusher, and a saponification reaction was carried out for a total of 1 h. Afterward, 1000 g of methyl acetate was added to neutralize the remaining alkali. A phenolphthalein indicator was used to confirm that neutralization was complete. 1000 g of methanol was then added to a white solid obtained by filtration, and the resulting mixture was left at room temperature for 3 h and then washed. After repeating the washing process three times, a solid obtained by centrifugal dehydration was left in a dryer at 70 °C for 2 days to obtain an ethylene-modified vinyl alcohol polymer (PVA-2). Production examples 3 to 5: Production of PVA-3 to PVA-5

[0093] Each ethylene-modified vinyl alcohol polymer (PVA-3 to PVA-5) was prepared by the same method as in Preparation Example 2, except that the polymerization conditions and saponification conditions were as shown in Table 1.

[0094] The viscosity-average degree of polymerization, degree of saponification, and degree of ethylene modification (ethylene unit content) of each of the obtained PVA-1 to PVA-5 were measured. The measurement results are shown in Table 1.

[0095] Apart from PVA-1 to PVA-5, polymers used in Examples and Comparative Examples are shown below. Polymer (a) Polymer a1: “MFP1883” (manufactured by Michelman, Inc.), an olefin-acrylic acid copolymer emulsion with a solids content of 27 wt% Polymer a2: “OP-671” (manufactured by Lion Corporation), a styrene-acrylic acid ester copolymer emulsion with a solid content of 48 wt% Polymer a3: “CHEMIPEARL S-100” (manufactured by Mitsui Chemicals, Inc.), an ethylene-methacrylic acid copolymer emulsion with a solid content of 27 wt% Polymer a4: “Tykote 1004” (manufactured by Mallard Creek Polymers, Inc.), a styrene-butadiene copolymer emulsion Polymer (b)

[0096] PU-1: “TAKELAC WPB-341” (manufactured by Mitsui Chemicals, Inc.), a polyurethane emulsion with a solid content of 30 wt% Polymer (c) Polymer c1: “VAPCT2200” (manufactured by Michelman, Inc.), a styrene-acrylic acid ester copolymer emulsion with a solids content of 48 wt%, a glass transition temperature of -32.3 °C, and a melting point of 60.4 °C Polymer c2: “498340R” (manufactured by Michelman, Inc.), an ethylene-acrylic acid copolymer emulsion with a solids content of 40 wt%, a glass transition temperature of -0.5 °C, and a melting point of 78.7 °C Polymer c3: “OP-671” (manufactured by Lion Corporation), a styrene-butadiene copolymer emulsion with a solid content of 48 wt%, a glass transition temperature of 2.8 °C, and a melting point of 47.0 °C Polymer c4: “CHEMIPEARL S-100” (manufactured by Mitsui Chemicals, Inc.), an ethylene-methacrylic acid copolymer emulsion with a solid content of 27 wt%, a glass transition temperature of 23.9 °C, and a melting point of 86.9 °C Method for measuring glass transition temperature and melting point

[0097] The glass transition temperature and melting point of the polymer (c) were measured by the following method.

[0098] Approximately 3 mg of a sample was placed in a sample pan, and the glass transition point and melting point of the sample were measured using a DSC Q2000 device (manufactured by TA Instruments, Inc.). The temperature of the sample was increased from 30 °C to 200 °C, then decreased to -90 °C and held for 5 min, and then increased to 200 °C. Both the increase and decrease of the temperature were performed at a rate of 10 °C / min. Example 1: Creating a structure

[0099] Wood-free paper with a basis weight of 70.5 g / m 2 was prepared as the paper base material. The A-layer was prepared such that one area of ​​the paper base material was coated with the emulsion “MFP1883” of polymer a1 as the A-layer-forming coating liquid at a coating amount of 10.0 g / m 2in the dry mass and then drying was carried out. Next, the B layer was provided such that one surface of the A layer was coated with an aqueous solution of PVA-1 (solid content: 10 wt%) as the B layer-forming coating liquid at a coating amount of 3.0 g / m 2 in the dry mass and then drying was carried out. Next, the C-layer was provided such that one surface of the B-layer was coated with the emulsion "VAPCT2200" of polymer c1 as the C-layer-forming coating liquid at a coating amount of 10.0 g / m 2in the dry mass and then drying was carried out. In the manner described above, a structure of Example 1 was obtained. The A layer, the B layer, and the C layer were all applied using a wire bar. The obtained structure and the C layer-forming coating liquid used were subjected to the following evaluation. The evaluation results are shown in Table 3. Evaluation(1) Viscosity of the C-layer forming coating liquid

[0100] After the temperature of the C-layer forming coating liquid in a chamber was controlled at 20 °C, the viscosity of the C-layer forming coating liquid was measured using a B-type viscometer under conditions including 60 rpm. (2) Viscosity stability of the C-layer forming coating liquid

[0101] The solid content of the C-layer forming coating liquid was adjusted to 22 wt%, and the fluidity of this coating liquid during stirring was evaluated according to the following criteria: A: liquid without thickening; B: thickened but liquid; and C: not liquid (creamy). (3) Oxygen permeability (gas barrier properties)

[0102] The oxygen permeability of the structure was measured using “OX-TRAN2 / 21,” manufactured by MOCON, Inc., under conditions including 23 °C / 65% RH. (4) Water vapor permeability (water vapor barrier properties)

[0103] The water vapor permeability of the structure was measured based on JIS Z 2080 by a shell method under conditions including a temperature of 40 ± 0.5 °C and a relative humidity difference of 90 ± 2%. (5) Cracks in the C layer

[0104] The presence or absence of cracks in the C-layer of the structure and their degree were visually evaluated according to the following criteria: A + : no cracks were observed; A: cracks were partially observed; B: continuous cracks were partially observed; and C: Continuous cracks were observed throughout the layer. (6) Heat sealing properties

[0105] The C layers of the structure were superimposed and sealed together by heating using a thermal gradient tester under conditions including 160°C, 0.3 MPa, and 1 s. A 180° peel test was then performed using an autograph, and a section where a fracture occurred was evaluated according to the following criteria: A: Breakage of the paper base material (the bonding strength between the C layers was greater than or equal to that of the paper base material and was sufficiently high); B: Interlayer delamination (the C layers were sealed, but the adhesion strength between them was lower than that of the paper base material); and C: natural detachment (unsealed condition). Example 2

[0106] A structure of Example 2 was obtained by the same procedure as in Example 1, except that PVA-2 was used instead of PVA-1 in the B-layer-forming coating liquid, and the polymer c2 emulsion "498340R" was used as the C-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 3

[0107] A structure of Example 3 was obtained by the same procedure as Example 2, except that the emulsion "OP-671" of polymer c3 was used as the C-layer-forming coating liquid. Evaluation was performed by the same methods as Example 1. The evaluation results are shown in Table 3. Example 4

[0108] A paraffin wax emulsion "Haricoat RT" (manufactured by Harima Chemicals Group, Inc.) was added to the emulsion "VAPCT2200" of polymer c1 to prepare a mixture in which the content of "Haricoat RT" with respect to polymer c1 (100 parts by mass) was 0.5 parts by mass in terms of solid content. A structure of Example 4 was obtained by the same procedure as in Example 2, except that this mixture was used as the C-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 5

[0109] A structure of Example 5 was obtained by the same procedure as Example 4, except that the content of "Haricoat RT" in terms of polymer c1 (100 parts by mass) in the C-layer-forming coating liquid was adjusted to 10 parts by mass in terms of solid content. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 6

[0110] A structure of Example 6 was obtained by the same procedure as Example 4, except that the content of "Haricoat RT" in terms of polymer c1 (100 parts by mass) in the C-layer-forming coating liquid was adjusted to 22 parts by mass in terms of solid content. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 7

[0111] A structure of Example 7 was obtained by the same procedure as Example 5, except that the emulsion "OP-671" of polymer a2 was used as the A-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 8

[0112] A structure of Example 8 was obtained by the same procedure as Example 5, except that the emulsion "CHEMIPEARL S-100" of polymer a3 was used as the A-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 9

[0113] A structure of Example 9 was obtained by the same procedure as Example 5, except that the emulsion "Tykote 1004" of polymer a4 was used as the A-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 10

[0114] A soapstone dispersion "Finntalc C10B" (manufactured by Elementis plc) was added to the emulsion "MFP1883" of polymer a1 to prepare a mixture in which the soapstone content was 50 parts by mass relative to polymer a1 (100 parts by mass). A structure of Example 10 was obtained by the same procedure as in Example 5, except that this mixture was used as the A-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 11

[0115] A mica dispersion "ME-100" (manufactured by Katakura & Co-op Agri Corporation) was added to an aqueous solution of PVA-2 (solid content: 10 mass%) to prepare a mixture in which the mica content was 5 mass parts relative to PVA-2 (100 mass parts). A structure of Example 11 was obtained by the same procedure as in Example 5, except that this mixture was used as the B-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Example 12

[0116] A structure of Example 12 was obtained by the same procedure as Example 5, except that PVA-3 was used instead of PVA-2 in the B-layer forming coating liquid. Evaluation was performed by the same methods as Example 1. The evaluation results are shown in Table 3. Example 13

[0117] A structure of Example 13 was obtained by the same procedure as Example 5, except that PVA-4 was used instead of PVA-2 in the B-layer-forming coating liquid. Evaluation was performed by the same methods as Example 1. The evaluation results are shown in Table 3. Example 14

[0118] A mica dispersion "ME-100" (manufactured by Katakura & Co-op Agri Corporation) was added to an aqueous solution of PVA-2 (solid content: 10 mass%) to prepare a mixture in which the mica content was 5 mass parts relative to PVA-2 (100 mass parts). A structure of Example 14 was obtained by the same procedure as in Example 10, except that this mixture was used as the B-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Comparison example 1

[0119] A structure of Comparative Example 1 was obtained by the same procedure as Example 5, except that the emulsion "CHEMIPEARL S-100" of polymer c4 was used as the C-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Comparison example 2

[0120] A structure of Comparative Example 2 was obtained by the same procedure as Example 2, except that the emulsion "CHEMIPEARL S-100" of polymer c4 was used as the C-layer-forming coating liquid. Evaluation was performed by the same methods as Example 1. The evaluation results are shown in Table 3. Comparison example 3

[0121] PVA-5 was added to the "CHEMIPEARL S-100" emulsion of polymer c4 to prepare a mixture in which the content of PVA-5 was 5 parts by mass relative to polymer c4 (100 parts by mass). A structure of Comparative Example 3 was obtained by the same procedure as in Comparative Example 2, except that this mixture was used as the C-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Comparison example 4

[0122] A structure of Comparative Example 4 was obtained by the same procedure as Comparative Example 2, except that the emulsion "TAKELAC WPB-341" of PU-1 was used as the B-layer-forming coating liquid. Evaluation was performed by the same methods as in Example 1. The evaluation results are shown in Table 3. Table 1 PVA Polymerization conditions Saponification conditions Analysis results Polymerization temperature Vinyl acetate Methanol Ethylene pressure during polymerization Amount of added polymerization initiator Polymerization time polymerization rate PVAc concentration Amount of NaOH to be added Saponification temperature viscosity-average degree of polymerization Degree of saponification Degree of ethylene modification °C g g kg / cm 2 g h % % Molar ratio °C - Mol-% Mol-% PVA-1 60 1050 1950 - 1,6 3 50 30 0,10 40 400 99,3 0 PVA-2 60 1440 1560 7,8 2,0 3 50 30 0,10 40 400 99,2 10 PVA-3 60 2550 450 2,9 1,0 3 20 20 0,04 40 1700 98,4 2 PVA-4 60 2640 360 7,3 0,8 3 20 20 0,04 40 2000 98,2 6 PVA-5 60 2550 450 2,9 1,0 3 20 20 0,01 40 1700 93,1 2 Table 2 A-shift B-layer C-layer Polymer (a) Soapstone Polymer (b) mica Polymer (c) Haricoat RT Type Content (parts by mass) Type Content (parts by mass) Type Glass transition temperature (°C) Melting point (°C) Content (parts by mass) Example 1 a1 0 PVA-1 0 c1 -32,3 60,4 0 Example 2 a1 0 PVA-2 0 c2 -0,5 78,7 0 Example 3 a1 0 PVA-2 0 c3 2,8 47,0 0 Example 4 a1 0 PVA-2 0 c1 -32,3 60,4 0,5 Example 5 a1 0 PVA-2 0 c1 -32,3 60,4 10 Example 6 a1 0 PVA-2 0 c1 -32,3 60,4 22 Example 7 a2 0 PVA-2 0 c1 -32,3 60,4 10 Example 8 a3 0 PVA-2 0 c1 -32,3 60,4 10 Example 9 a4 0 PVA-2 0 c1 -32,3 60,4 10 Example 10 a1 50 PVA-2 0 c1 -32,3 60,4 10 Example 11 a1 0 PVA-2 5 c1 -32,3 60,4 10 Example 12 a1 0 PVA-3 0 c1 -32,3 60,4 10 Example 13 a1 0 PVA-4 0 c1 -32,3 60,4 10 Example 14 a1 50 PVA-2 5 c1 -32,3 60,4 10 Comparison example 1 a1 0 PVA-2 0 c4 23,9 86,9 10 Comparison example 2 a1 0 PVA-2 0 c4 23,9 86,9 0 Comparison example 3 a1 0 PVA-2 0 c4 / PVA-5 = 100 / 5(mass ratio) 23,9 *1 86,9 0 Comparison example4 a1 0 PU-1 0 c4 23,9 86,9 0 *1: Glass transition temperature of polymer c4, which is the main component polymer Table 3 C-layer-forming coating liquid structure viscosity Viscosity stability Oxygen permeability Water vapor permeability cracks Heat sealing properties mPa s - cc / m 2 ·24 h g / m 2 ·24 h - - Example 1 200 A 5 30 A + A Example 2 1200 A 3 45 A A Example 3 110 A 3 60 B A Example 4 190 A 3 25 A + A Example 5 160 A 3 15 A + A Example 6 130 A 3 20 A + A Example 7 160 A 3 35 A + A Example 8 160 A 3 30 A + A Example 9 160 A 3 35 A + A Example 10 160 A 3 10 A + A Example 11 160 A 1 30 A + A Example 12 160 A 5 30 A + A Example 13 160 A 5 30 A + A Example 14 160 A 1 10 A + A Comparison example 1 320 A 3 100 C B Comparison example 2 400 A 3 100 C B Comparison example 3 unmeasurable C 3 75 A B Comparison example 4 400 A 10 45 A B

[0123] The results indicate that the structures of Examples 1 to 14, each of which contains the vinyl alcohol polymer (PVA-1 to PVA-4) in the B layer and the polymer with a glass transition temperature of -100°C or more and 5°C or less (polymers c1 to c3), exhibit only minimal cracking in the C layer and are excellent in water vapor barrier properties, heat-sealing properties, and oxygen barrier properties. Specifically, when comparing Examples 2 and 3 and Comparative Example 2, which differ only in the type of polymer (c), it can be confirmed that the glass transition temperature of the polymer (c) constituting the C layer significantly affects the probability of cracking in the C layer and the water vapor barrier properties.

[0124] It should be noted that in the case where the B layer did not contain a vinyl alcohol polymer as in Comparative Example 4, the oxygen barrier properties were low, while cracks were less likely to occur in the C layer even when the glass transition temperature of the polymer contained in the C layer was high. In contrast, in the case where the B layer contained the vinyl alcohol polymer as in Comparative Examples 1 and 2, cracks occurred in the C layer depending on the glass transition temperature of the polymer contained in the C layer, and the water vapor barrier properties were deteriorated. Therefore, it can be confirmed that cracks in the C layer are a phenomenon that prominently occurs when the B layer contains the vinyl alcohol polymer.In other words, in each of the structures of Examples 1 to 14, the vinyl alcohol polymer having particularly high oxygen barrier properties is used in the B layer and the polymer less likely to cause cracks is used in the C layer, whereby both excellent oxygen barrier properties and excellent water vapor barrier properties can be achieved.

[0125] In addition, it was found that in the case where the C-layer-forming coating liquid contains the vinyl alcohol polymer as in Comparative Example 3, the viscosity increases and the viscosity stability decreases, resulting in deterioration of the coatability. INDUSTRIAL APPLICABILITY

[0126] The structure of the present invention can be suitably used as a packaging material such as greaseproof paper, gas barrier paper, fragrance barrier paper or the like. EXPLANATION OF REFERENCE SYMBOLS 10 Structure 11 Paper base material 12 A-shift 13 B-shift 14 C-layer QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited non-patent literature

[0000] JIS K 6726:1994

[0044]

Claims

[1] Structure in which an A layer, a B layer and a C layer are arranged one upon another in this order on at least one surface of a paper base material, where the A layer contains at least one selected from the group consisting of an olefin polymer, a styrene polymer and a polyester polymer, the B layer contains a vinyl alcohol polymer, and the C layer contains a polymer with a glass transition temperature of - 100 °C or more and 5 °C or less. [2] The structure according to claim 1, wherein the C layer has a melting point of 120 °C or less. [3] Structure according to claim 1 or 2, where the A layer contains the olefin polymer, and the olefin polymer contains an olefin-unsaturated carboxylic acid copolymer. [4] A structure according to any one of claims 1 to 3, wherein the A layer further contains soapstone. [5] The structure according to claim 4, wherein the content of the soapstone in the A layer is 1 mass% or more and 80 mass% or less. [6] The structure according to any one of claims 1 to 5, wherein the vinyl alcohol polymer is an ethylene-modified vinyl alcohol polymer. [7] The structure according to any one of claims 1 to 6, wherein the polymer having a glass transition temperature of -100°C or more and 5°C or less is a styrene-acrylic copolymer. [8] The structure according to any one of claims 1 to 7, wherein the C layer further contains a wax. [9] The structure according to claim 8, wherein the content of the wax in the C layer is 0.1 mass% or more and 30 mass% or less. [10] A structure according to claim 8 or 9, wherein the wax contains paraffin wax. [11] The structure according to claim 10, wherein the content of the paraffin wax in the C layer is 1 mass% or more and 30 mass% or less. [12] The structure according to any one of claims 1 to 11, wherein the vinyl alcohol polymer consists of two or more kinds of vinyl alcohol polymers having different degrees of polymerization. [13] The structure according to any one of claims 1 to 12, wherein the A layer contains at least two selected from the group consisting of the olefin polymer, the styrene polymer and the polyester polymer. [14] The structure according to any one of claims 1 to 13, wherein the C layer contains two or more kinds of polymers. [15] A method of manufacturing the structure according to any one of claims 1 to 14, comprising: Providing at least one of the A layer, the B layer, or the C layer using a curtain coater. [16] Greaseproof paper comprising the structure according to any one of claims 1 to 14. [17] Gas barrier paper comprising the structure according to any one of claims 1 to 14. [18] Fragrance barrier paper comprising the structure of any one of claims 1 to 14. [19] A packaging material comprising at least one selected from the group consisting of the greaseproof paper according to claim 16, the gas barrier paper according to claim 17 and the fragrance barrier paper according to claim 18.

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