Laminate and food packaging material

Abstract

A laminate (1) includes a paper substrate (2), an anchor coat layer (3) disposed at a one-surface side of the paper substrate (2), and a barrier coat layer (4) disposed at a one-surface side of the anchor coat layer (3). The paper substrate (2) has a density of 0.72 g / cm³ or more. The barrier coat layer (4) contains a gas barrier polyurethane resin. (Most illustrative figure: Fig.1)

Description

Laminates and food packaging materials

[0001] The present invention relates to a laminate and a food packaging material, and more particularly to a laminate having a paper substrate and a food packaging material including the laminate.

[0002] BACKGROUND ART It has been known that gas barrier properties can be imparted to a paper substrate by coating the surface of the paper substrate with a gas barrier polyurethane resin.

[0003] For example, a basis weight of 70 g / m ２ It has been proposed to obtain a laminate by laminating an anchor coat layer containing a first polyurethane resin and a layered inorganic compound and a barrier coat layer containing a second polyurethane resin and a layered inorganic compound onto uncoated paper of the above, and curing the resulting product at 40°C for 3 days (see, for example, Patent Document 1 (Example 1)).

[0004] JP 2015-104831 A

[0005] On the other hand, the laminate has the drawback that it does not exhibit sufficient gas barrier properties unless it is cured.

[0006] The present invention relates to a laminate having excellent gas barrier properties and a food packaging material comprising the laminate.

[0007] The present invention [1] comprises a paper base material, an anchor coat layer disposed on one side of the paper base material, and a barrier coat layer disposed on one side of the anchor coat layer, wherein the density of the paper base material is 0.72 g / cm ３ As described above, the barrier coat layer includes a laminate containing a gas barrier polyurethane resin.

[0008] The present invention [2] includes the laminate according to the above [1], which has an air resistance measured in accordance with JIS P 8117 (2009) of 30,000 s or more.

[0009] The present invention [3] includes the laminate according to the above [1] or [2], wherein in the barrier coat layer, the gas barrier polyurethane resin includes a secondary reaction product of an isocyanate-terminated prepolymer, which is a primary reaction product of a polyisocyanate component containing xylylene diisocyanate and / or hydrogenated xylylene diisocyanate, a short-chain diol having 2 to 6 carbon atoms, and an active hydrogen group-containing component containing an active hydrogen compound containing a hydrophilic group, and a chain extender.

[0010] The present invention [4] includes the laminate according to any one of the above [1] to [3], wherein the barrier coat layer further contains a layered inorganic compound.

[0011] The present invention [5] is characterized in that the amount of the barrier coat layer is 0.5 g / cm ２ 20.0g / cm or more ２ The laminate according to any one of the above [1] to [4] is included.

[0012] The present invention [6] is characterized in that the amount of the anchor coat layer is 0.3 g / cm ２ 20.0g / cm or more ２ The laminate according to any one of the above [1] to [5] is included.

[0013] The present invention [7] includes a food packaging material comprising the laminate according to any one of the above [1] to [6].

[0014] The laminate and food packaging material of the present invention have excellent gas barrier properties because the paper substrate has a predetermined density.

[0015] FIG. 1 is a schematic diagram showing an embodiment of the laminate of the present invention.

[0016] In FIG. 1 , the laminate 1 comprises a paper substrate 2 , an anchor coat layer 3 disposed on one side of the paper substrate 2 , and a barrier coat layer 4 disposed on one side of the anchor coat layer 3 .

[0017] The paper substrate 2 is a substrate made of paper. Paper is formed, for example, by papermaking pulp. Examples of pulp include natural pulp and synthetic pulp.

[0018] In the laminate 1, a paper having a predetermined density is selected as the paper substrate 2.

[0019] The density of the paper base material 2 is 0.72 g / cm ３ More preferably, 0.75 g / cm ３ More preferably, 0.80 g / cm ３ More preferably, 0.90 g / cm ３ More preferably, 1.00 g / cm ３ That's all.

[0020] If the density of the paper base material 2 is above the above lower limit, the degree of penetration of the anchor coat layer 3 (described later) and the barrier coat layer 4 (described later) into the paper base material 2 can be appropriately adjusted, and a laminate 1 with excellent gas barrier properties in an uncured state can be obtained.

[0021] The density of the paper base material 2 is, for example, 1.50 g / cm ３ Preferably, 1.45 g / cm or less ３ More preferably, 1.40 g / cm or less ３ More preferably, 1.35 g / cm or less ３ More preferably, 1.30 g / cm or less ３ Particularly preferably, 1.25 g / cm ３ The following is the result.

[0022] If the density of the paper base material 2 is below the upper limit, the anchor coat layer 3 (described later) and the barrier coat layer 4 (described later) can be arranged with good orientation relative to the paper base material 2, and a laminate 1 having excellent gas barrier properties in the uncured state can be obtained.

[0023] The density of the paper is adjusted by, for example, the type of pulp and the papermaking method.

[0024] The thickness of the paper base material 2 is, for example, 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and for example, 500 μm or less, preferably 200 μm or less.

[0025] If the thickness of the paper substrate 2 is within the above range, a laminate 1 having excellent gas barrier properties can be obtained.

[0026] The basis weight of the paper substrate 2 is, for example, 20 g / m ２ More than 30 g / m ２ The basis weight of the paper base material 2 is, for example, 400 g / m ２ Preferably, 300 g / m or less ２ The following is the result.

[0027] The gas barrier properties (described later) of the uncured laminate do not correlate with the basis weight of the paper base material 2 but correlate with the density of the paper base material 2 .

[0028] More specifically, examples of such paper substrate 2 include glassine paper, coated paper, and one-sided gloss kraft paper.

[0029] These paper substrates 2 can be used alone or in combination of two or more types.

[0030] The paper substrate 2 may be a single layer or a multi-layer. When the paper substrate 2 is a multi-layer, each layer may be made of the same type of paper or two or more types of paper.

[0031] There are no particular limitations on the shape of the paper substrate 2. Examples of the shape of the paper substrate 2 include a sheet shape, a bottle shape, and a cup shape. A preferred shape of the paper substrate 2 is a sheet shape.

[0032] The paper substrate 2 may also be surface-treated, for example, by corona discharge treatment or vapor deposition treatment.

[0033] The anchor coat layer 3 is disposed on at least one surface of the paper substrate 2. The anchor coat layer 3 may be disposed on both surfaces of the paper substrate 2. The anchor coat layer 3 is preferably disposed on only one surface of the paper substrate 2.

[0034] The anchor coat layer 3 contains an anchor coat resin.

[0035] Examples of anchor coat resins include polyurethane resins, acrylic resins, polyolefin resins, polyethyleneimine resins, polyvinyl alcohol resins, olefin-vinyl alcohol copolymers, styrene-butadiene copolymers, carboxy-modified styrene-butadiene copolymers, polyester resins, and chitosan.

[0036] These anchor coating resins can be used alone or in combination of two or more kinds.

[0037] Examples of the anchor coat resin include polyurethane resin, acrylic resin, polyvinyl alcohol resin, and styrene-butadiene copolymer, and more preferably polyurethane resin.

[0038] The polyurethane resin also includes a gas barrier polyurethane resin, which will be described later.

[0039] The anchor coating layer 3 is formed, for example, by applying an anchor coating agent to the paper substrate 2 and drying the anchor coating agent.

[0040] The anchor coating agent contains the above anchor coating resin and a known solvent.

[0041] As the solvent, a solvent inactive to the anchor coat resin is appropriately selected.

[0042] Examples of the solvent include water, methanol, ethanol, propanol, isopropanol, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, and acetonitrile. These solvents can be used alone or in combination of two or more.

[0043] The blending ratio of the anchor coat resin and the solvent is appropriately set depending on the purpose and application.

[0044] The method for applying the anchor coating agent is not particularly limited, and examples of the application method include dip coating, gravure coating, reverse coating, roll coating, bar coating, spray coating, and air knife coating.

[0045] The drying conditions for the anchor coating agent are not particularly limited. For example, the drying temperature is, for example, 40°C or higher, preferably 50°C or higher. The drying temperature is, for example, 200°C or lower, preferably 180°C or lower. The drying time is, for example, 0.1 minutes or longer, preferably 0.2 minutes or longer. The drying time is, for example, 10 minutes or shorter, preferably 5 minutes or shorter.

[0046] As a result, the anchor coat layer 3 is formed.

[0047] The anchor coat layer 3 may also contain additives.

[0048] Examples of additives include fillers, silane coupling agents, alkoxysilane compounds, thickeners, antioxidants, heat stabilizers, UV absorbers, plasticizers, antistatic agents, lubricants, antiblocking agents, surfactants, dispersion stabilizers, colorants, pigments, dyes, colloidal silica, inorganic particles, inorganic oxide particles, nucleating agents, crosslinking agents, and curing agents. These additives can be used alone or in combination of two or more. The blending ratio of the additives is not particularly limited and can be appropriately set depending on the purpose and application.

[0049] The additive is preferably a filler. Examples of the filler include organic nanofibers and layered inorganic compounds, and more preferably layered inorganic compounds. Details of the layered inorganic compounds will be described later.

[0050] The additive is added to, for example, an anchor coating agent, which is then applied to the paper substrate 2 together with the anchor coating resin and dried.

[0051] The amount of the anchor coat layer 3 is, for example, 0.1 g / m ２ More than 0.3 g / m ２ More preferably, 0.5 g / m ２ More preferably, 1.0 g / m ２ More preferably, 1.5 g / m ２ The amount of the anchor coat layer 3 is, for example, 30.0 g / m ２ Preferably, 20.0 g / m or less ２More preferably, 10.0 g / m or less ２ More preferably, 5.0 g / m or less ２ Below, particularly preferably 3.0 g / m ２ The following is the result.

[0052] When the amount of the anchor coat layer 3 is within the above range, a laminate 1 having excellent gas barrier properties can be obtained.

[0053] The barrier coat layer 4 is a resin layer having gas barrier properties.

[0054] The gas barrier property is a property that reduces oxygen permeability. More specifically, the gas barrier property is a property that has an air resistance of a predetermined value or more and an oxygen permeability of a predetermined value or more.

[0055] The barrier coat layer 4 contains a gas barrier polyurethane resin.

[0056] More specifically, the barrier coating layer 4 is formed by preparing a barrier coating agent containing a gas-barrier polyurethane resin, applying the barrier coating agent to one side of the anchor coating layer 3, and then drying the barrier coating agent.

[0057] An example of a barrier coating agent is an aqueous dispersion of a gas-barrier polyurethane resin.

[0058] Hereinafter, the water dispersion of the gas-barrier polyurethane resin may be referred to as a polyurethane dispersion.

[0059] In the polyurethane dispersion, the gas-barrier polyurethane resin contains at least a reaction product obtained by reacting a polyisocyanate component with an active hydrogen group-containing component.

[0060] More specifically, the gas-barrier polyurethane resin is obtained by reacting an isocyanate-terminated prepolymer with a chain extender. The isocyanate-terminated prepolymer is obtained by reacting a polyisocyanate component with an active hydrogen group-containing component.

[0061] That is, the isocyanate-terminated prepolymer is a primary reaction product between a polyisocyanate component and an active hydrogen group-containing component, and the gas-barrier polyurethane resin is a secondary reaction product between the isocyanate-terminated prepolymer and a chain extender.

[0062] By using such a gas barrier polyurethane resin, a laminate 1 having excellent gas barrier properties can be obtained.

[0063] In preparing the polyurethane dispersion, for example, first, an isocyanate group-terminated prepolymer is synthesized.

[0064] The isocyanate-terminated prepolymer is a polyurethane prepolymer having two or more free isocyanate groups at the molecular terminals.

[0065] As described above, the isocyanate group-terminated prepolymer is obtained by reacting a polyisocyanate component with an active hydrogen group-containing component.

[0066] The polyisocyanate component may be, for example, xylylene diisocyanate (XDI) and / or hydrogenated xylylene diisocyanate (H ６ XDI).

[0067] Examples of xylylene diisocyanate include xylylene diisocyanate monomer (XDI monomer) and xylylene diisocyanate derivatives (XDI derivatives).

[0068] Xylylene diisocyanate monomers include, for example, 1,2-xylylene diisocyanate, 1,3-xylylene diisocyanate, and 1,4-xylylene diisocyanate.

[0069] These xylylene diisocyanate monomers can be used alone or in combination of two or more kinds.

[0070] As the xylylene diisocyanate monomer, preferably, 1,3-xylylene diisocyanate or 1,4-xylylene diisocyanate is used, and more preferably, 1,3-xylylene diisocyanate is used.

[0071] Examples of the xylylene diisocyanate derivative include modified products obtained by modifying the above-mentioned xylylene diisocyanate monomer by a known method.

[0072] More specific examples of xylylene diisocyanate derivatives include polymers, allophanate-modified products, polyol-modified products, biuret-modified products, urea-modified products, oxadiazinetrione-modified products, and carbodiimide-modified products.

[0073] These xylylene diisocyanate derivatives can be used alone or in combination of two or more kinds.

[0074] These xylylene diisocyanates can be used alone or in combination of two or more.

[0075] As the xylylene diisocyanate, preferably, a xylylene diisocyanate monomer is used.

[0076] Examples of hydrogenated xylylene diisocyanate include hydrogenated xylylene diisocyanate monomer (H ６ XDI monomer) and hydrogenated xylylene diisocyanate derivatives (H ６ XDI derivatives).

[0077] The hydrogenated xylylene diisocyanate monomer is bis(isocyanatomethyl)cyclohexane.

[0078] Examples of the hydrogenated xylylene diisocyanate monomer include 1,2-hydrogenated xylylene diisocyanate, 1,3-hydrogenated xylylene diisocyanate, and 1,4-hydrogenated xylylene diisocyanate.

[0079] These hydrogenated xylylene diisocyanate monomers can be used alone or in combination of two or more.

[0080] As the hydrogenated xylylene diisocyanate monomer, preferably, 1,3-hydrogenated xylylene diisocyanate and 1,4-hydrogenated xylylene diisocyanate are used, and more preferably, 1,3-hydrogenated xylylene diisocyanate is used.

[0081] Examples of the hydrogenated xylylene diisocyanate derivative include the same derivatives as those mentioned above.

[0082] These hydrogenated xylylene diisocyanate derivatives can be used alone or in combination of two or more.

[0083] These hydrogenated xylylene diisocyanates can be used alone or in combination of two or more.

[0084] As the hydrogenated xylylene diisocyanate, preferably, hydrogenated xylylene diisocyanate monomer is used.

[0085] As the xylylene diisocyanate and / or hydrogenated xylylene diisocyanate, preferably, xylylene diisocyanate is used, and more preferably, xylylene diisocyanate monomer is used.

[0086] Furthermore, the polyisocyanate component may contain other polyisocyanates as needed.

[0087] The other polyisocyanates are polyisocyanates other than xylylene diisocyanate and hydrogenated xylylene diisocyanate.

[0088] Other polyisocyanates include polyisocyanates commonly used industrially, more specifically, aromatic polyisocyanates, araliphatic polyisocyanates (excluding xylylene diisocyanate), aliphatic polyisocyanates, and alicyclic polyisocyanates (excluding hydrogenated xylylene diisocyanate).

[0089] Other polyisocyanates include derivatives of the same types as those mentioned above.

[0090] The other polyisocyanates may be used alone or in combination of two or more kinds.

[0091] As the other polyisocyanates, preferably, alicyclic polyisocyanates are used. Examples of the alicyclic polyisocyanates include methylenebis(cyclohexyl isocyanate) (H １２ Examples include MDI.

[0092] When the polyisocyanate component contains other polyisocyanates, the ratio of xylylene diisocyanate and hydrogenated xylylene diisocyanate to the other polyisocyanates is appropriately set within a range that does not impair the excellent effects of the present invention.

[0093] For example, the content ratio of xylylene diisocyanate and hydrogenated xylylene diisocyanate (the total amount of them when used in combination) relative to the total amount of the polyisocyanate component is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, and for example, 99% by mass or less.

[0094] As the polyisocyanate component, preferably, xylylene diisocyanate and hydrogenated xylylene diisocyanate are used in combination, and more preferably, xylylene diisocyanate monomer and hydrogenated xylylene diisocyanate monomer are used in combination.

[0095] When xylylene diisocyanate and hydrogenated xylylene diisocyanate are used in combination, the amount of xylylene diisocyanate is, for example, 60 parts by mass or more, preferably 70 parts by mass or more, more preferably 80 parts by mass or more, and for example, 95 parts by mass or less, preferably 93 parts by mass or less, more preferably 90 parts by mass or less, relative to 100 parts by mass of the total amount of xylylene diisocyanate and hydrogenated xylylene diisocyanate.

[0096] Furthermore, relative to 100 parts by mass of the total amount of these, the amount of hydrogenated xylylene diisocyanate is, for example, 5 parts by mass or more, preferably 7 parts by mass or more, more preferably 10 parts by mass or more, and for example, 40 parts by mass or less, preferably 30 parts by mass or less, more preferably 20 parts by mass or less.

[0097] The active hydrogen group-containing component may be a polyol component.

[0098] The polyol component contains, for example, a short-chain diol having 2 to 6 carbon atoms.

[0099] The short-chain diol having 2 to 6 carbon atoms is an organic compound having two hydroxyl groups and having 2 to 6 carbon atoms.

[0100] The molecular weight of the short-chain diol is from 50 to 650. When the short-chain diol has a molecular weight distribution, the molecular weight indicates the number average molecular weight in terms of polystyrene measured by GPC.

[0101] Examples of short-chain diols include alkane diols having 2 to 6 carbon atoms, ether diols having 2 to 6 carbon atoms, and alkene diols having 2 to 6 carbon atoms.

[0102] Examples of alkanediols having 2 to 6 carbon atoms include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,3-cyclohexanediol, and 1,4-cyclohexanediol.

[0103] Examples of the ether diol having 2 to 6 carbon atoms include diethylene glycol, triethylene glycol, and dipropylene glycol.

[0104] An example of the alkenediol having 2 to 6 carbon atoms is 1,4-dihydroxy-2-butene.

[0105] These short chain diols can be used alone or in combination of two or more.

[0106] As the short-chain diol, from the viewpoint of gas barrier properties, preferably, an alkanediol having 2 to 6 carbon atoms is used, and more preferably, ethylene glycol is used.

[0107] The content ratio of the short-chain diol having 2 to 6 carbon atoms, relative to 100 parts by mass of the total amount of the polyol components, is, for example, 10 parts by mass or more, preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and for example, 90 parts by mass or less, preferably 80 parts by mass or less, more preferably 70 parts by mass or less.

[0108] When the gas-barrier polyurethane resin is prepared as a polyurethane dispersion, the polyol component contains an active hydrogen group-containing compound that contains a hydrophilic group.

[0109] The active hydrogen group-containing compound containing a hydrophilic group is a compound containing a hydrophilic group and an active hydrogen group.

[0110] Examples of the active hydrogen group include a hydroxyl group and an amino group.

[0111] Examples of the hydrophilic group include a nonionic group and an ionic group.

[0112] More specific examples of the active hydrogen group-containing compound containing a hydrophilic group include an active hydrogen group-containing compound containing a nonionic group and an active hydrogen group-containing compound containing an ionic group.

[0113] The active hydrogen group-containing compound containing a nonionic group is a compound having one or more nonionic groups and two or more active hydrogen groups. Examples of the nonionic group include a polyoxyethylene group.

[0114] Examples of the active hydrogen group-containing compound containing a nonionic group include polyoxyethylene glycol, one-end-blocked polyoxyethylene glycol, and polyols containing polyoxyethylene side chains.

[0115] Examples of active hydrogen group-containing compounds containing an ionic group include active hydrogen group-containing compounds containing an anionic group and active hydrogen group-containing compounds containing a cationic group.

[0116] The active hydrogen group-containing compound containing an anionic group is a compound having one or more anionic groups and two or more active hydrogen groups. Examples of the anionic group include a carboxy group (carboxylic acid group) and a sulfo group (sulfonic acid group).

[0117] The active hydrogen group-containing compound containing a cationic group is a compound having one or more cationic groups and two or more active hydrogen groups. Examples of the cationic group include a quaternary ammonium group.

[0118] These active hydrogen group-containing compounds containing hydrophilic groups can be used alone or in combination of two or more kinds.

[0119] As the active hydrogen group-containing compound containing a hydrophilic group, a preferred example is an active hydrogen group-containing compound containing an anionic group.

[0120] In the active hydrogen group-containing compound containing an anionic group, examples of the anionic group include a carboxy group (carboxylic acid group) and a sulfo group (sulfonic acid group).

[0121] From the viewpoint of gas barrier properties and water resistance, the anionic group is preferably a carboxy group.

[0122] In the active hydrogen group-containing compound containing an anionic group, examples of the active hydrogen group include a hydroxyl group and an amino group, and preferably a hydroxyl group.

[0123] That is, as the active hydrogen group-containing compound containing an anionic group, an organic compound having both a carboxy group and two hydroxyl groups is preferably used.

[0124] An example of an organic compound having both a carboxy group and two hydroxyl groups is a carboxy group-containing polyol.

[0125] Examples of carboxy group-containing polyols include polyhydroxyalkanoic acids.

[0126] Examples of polyhydroxyalkanoic acids include 2,2-dimethylolacetic acid, 2,2-dimethylollactic acid, 2,2-dimethylolpropionic acid (also known as dimethylolpropionic acid), 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid.

[0127] These organic compounds having both a carboxy group and two hydroxyl groups can be used alone or in combination of two or more kinds.

[0128] A preferred example of the organic compound having both a carboxy group and two hydroxyl groups is 2,2-dimethylolpropionic acid.

[0129] The content ratio of the active hydrogen group-containing compound that contains a hydrophilic group is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, and for example, 50 parts by mass or less, preferably 40 parts by mass or less, relative to 100 parts by mass of the total amount of the polyol component.

[0130] The polyol component may further contain other low molecular weight polyols as optional components.

[0131] The other low molecular weight polyols are low molecular weight polyols excluding short chain diols having 2 to 6 carbon atoms and active hydrogen group-containing compounds containing hydrophilic groups.

[0132] The low-molecular-weight polyol is an organic compound having a relatively low molecular weight and having two or more hydroxyl groups in the molecule.

[0133] The molecular weight of the low-molecular-weight polyol is 50 or more and 650 or less, preferably 500 or less.

[0134] Examples of other low molecular weight polyols include diols having 7 or more carbon atoms and low molecular weight polyols having 3 or more valences.

[0135] Examples of diols having 7 or more carbon atoms include alkane (having 7 to 20 carbon atoms)-1,2-diol, 2,6-dimethyl-1-octene-3,8-diol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, and bisphenol A.

[0136] These diols having 7 or more carbon atoms can be used alone or in combination of two or more kinds.

[0137] Examples of the low molecular weight trihydric or higher polyols include trihydric alcohols and tetrahydric alcohols.

[0138] Examples of trihydric alcohols include glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolpropane, and 2,2-bis(hydroxymethyl)-3-butanol.

[0139] Examples of tetrahydric alcohols include tetramethylolmethane (pentaerythritol) and diglycerin.

[0140] These trivalent or higher low molecular weight polyols can be used alone or in combination of two or more kinds.

[0141] Further, other low molecular weight polyols include polyether polyols having a number average molecular weight of 650 or less, polyester polyols having a number average molecular weight of 650 or less, and polycarbonate polyols having a number average molecular weight of 650 or less.

[0142] The other low molecular weight polyols may be used alone or in combination of two or more kinds.

[0143] As the other low molecular weight polyol, from the viewpoint of water resistance and aqueous dispersion stability, preferably, a low molecular weight polyol having a valence of three or more is used, more preferably, a trihydric alcohol is used, and particularly preferably, trimethylolpropane is used.

[0144] When other low-molecular-weight polyols are contained, the content ratio of the other low-molecular-weight polyols is, for example, 0.2 parts by mass or more, preferably 1 part by mass or more, more preferably 2 parts by mass or more, and for example, 20 parts by mass or less, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, per 100 parts by mass of the total amount of the polyol components.

[0145] The combined ratio of the short-chain diol having 2 to 6 carbon atoms and the other low-molecular-weight polyol is, for example, 2 parts by mass or more, preferably 5 parts by mass or more, and for example, 20 parts by mass or less, preferably 15 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of the total amount thereof.

[0146] Furthermore, relative to 100 parts by mass of the total amount of the short-chain diol having 2 to 6 carbon atoms and the other low-molecular-weight polyol, the amount of the active hydrogen group-containing compound that contains a hydrophilic group is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 40 parts by mass or more, and for example, 90 parts by mass or less, preferably 80 parts by mass or less, more preferably 70 parts by mass or less.

[0147] When the content of the other low-molecular-weight polyol is within the above range, excellent dispersibility can be ensured, and therefore a barrier coat layer with excellent gas barrier properties can be formed satisfactorily.

[0148] The polyol component may further contain a high molecular weight polyol as an optional component.

[0149] The high-molecular-weight polyol is a relatively high-molecular-weight organic compound (polymer) having two or more hydroxyl groups in the molecule, and the number-average molecular weight of the high-molecular-weight polyol is, for example, more than 650 and, for example, 20,000 or less.

[0150] Examples of high molecular weight polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols.

[0151] These high molecular weight polyols can be used alone or in combination of two or more kinds.

[0152] However, high-molecular-weight polyols may reduce the gas barrier properties of the polyurethane resin (described later), and therefore the polyol component preferably does not contain high-molecular-weight polyols.

[0153] That is, the polyol component preferably comprises a short-chain diol having 2 to 6 carbon atoms, a low-molecular-weight polyol having a valence of 3 or more, and an active hydrogen group-containing compound having a hydrophilic group, or comprises a short-chain diol having 2 to 6 carbon atoms and an active hydrogen group-containing compound having a hydrophilic group.

[0154] The polyol component more preferably comprises a short-chain diol having 2 to 6 carbon atoms, a low-molecular-weight polyol having a valence of 3 or more, and an active hydrogen group-containing compound having an anionic group, or comprises a short-chain diol having 2 to 6 carbon atoms and an active hydrogen group-containing compound having an anionic group.

[0155] The isocyanate-terminated prepolymer can be obtained by reacting the above components in a predetermined equivalent ratio.

[0156] In the synthesis of an isocyanate group-terminated prepolymer, the equivalent ratio is the equivalent ratio of isocyanate groups to active hydrogen groups (hydroxyl groups) (isocyanate groups / active hydrogen groups).

[0157] The equivalent ratio (isocyanate group / active hydrogen group) is, for example, more than 1, preferably 1.1 or more, and for example, 20 or less, preferably 10 or less.

[0158] In addition, a known polymerization method is used to synthesize the isocyanate group-terminated prepolymer.

[0159] Polymerization methods include, for example, bulk polymerization and solution polymerization.

[0160] As the polymerization method, solution polymerization is preferably adopted from the viewpoint of adjusting the reactivity.

[0161] In bulk polymerization, the above components are mixed and reacted, for example, under a nitrogen atmosphere at a reaction temperature of, for example, 75 to 85° C. The reaction time is, for example, 1 to 20 hours.

[0162] In solution polymerization, the above components are mixed in an organic solvent under a nitrogen atmosphere and reacted at a reaction temperature of, for example, 20 to 80° C. The reaction time is, for example, 1 to 20 hours.

[0163] The organic solvent may be a solvent inactive to an isocyanate group, such as acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, or acetonitrile. These organic solvents may be used alone or in combination of two or more.

[0164] In addition, a catalyst can be added to the polymerization as needed. Examples of the catalyst include amine catalysts and organometallic catalysts. These catalysts can be used alone or in combination of two or more. The amount of catalyst added is appropriately determined depending on the purpose and application.

[0165] In this method, the polymerization is terminated, for example, when the isocyanate group concentration in the reaction product reaches the range described below. In this method, the unreacted polyisocyanate component can be removed by a known removal method. Examples of the removal method include distillation and extraction.

[0166] This gives an isocyanate group-terminated prepolymer.

[0167] The isocyanate group concentration of the isocyanate group-terminated prepolymer is, for example, 4% by mass or more, preferably 5% by mass or more, more preferably 6% by mass or more, and for example, 25% by mass or less, preferably 20% by mass or less, more preferably 17% by mass or less, and even more preferably 15% by mass or less.

[0168] The average functionality of the isocyanate groups is, for example, 1.5 or more, preferably 1.9 or more, more preferably 2.0 or more, and for example, 3.0 or less, preferably 2.5 or less.

[0169] When the isocyanate-terminated prepolymer contains an anionic group, for example, a neutralizing agent is added to the isocyanate-terminated prepolymer to neutralize it, thereby forming a salt of the anionic group.

[0170] The neutralizing agent may be a commonly used base, specifically an organic base or an inorganic base.

[0171] Organic bases include, for example, tertiary amines and secondary amines.

[0172] Tertiary amines include, for example, trialkylamines and alkanolamines. Trialkylamines include, for example, trialkylamines having 1 to 4 carbon atoms. Such trialkylamines include, for example, trimethylamine and triethylamine. Alkanolamines include, for example, dimethylethanolamine, methyldiethanolamine, triethanolamine, and triisopropanolamine.

[0173] Examples of secondary amines include heterocyclic amines, such as morpholine.

[0174] These organic bases can be used alone or in combination of two or more kinds.

[0175] Inorganic bases include, for example, ammonia, alkali metal hydroxides, alkaline earth metal hydroxides, and alkali metal carbonates. Alkali metal hydroxides include, for example, lithium hydroxide, sodium hydroxide, and potassium hydroxide. Alkaline earth metal hydroxides include, for example, magnesium hydroxide and calcium hydroxide. Alkali metal carbonates include, for example, sodium carbonate and potassium carbonate.

[0176] These inorganic bases can be used alone or in combination of two or more.

[0177] These neutralizing agents can be used alone or in combination of two or more.

[0178] As the neutralizing agent, preferably, an organic base is used, more preferably, a tertiary amine is used, further preferably, a trialkylamine is used, and particularly preferably, triethylamine is used.

[0179] The amount of the neutralizing agent added is, for example, 0.4 equivalents or more, preferably 0.6 equivalents or more, relative to 1 equivalent of the anionic group, and for example, 1.2 equivalents or less, preferably 1.0 equivalents or less, relative to 1 equivalent of the anionic group.

[0180] Next, in this method, the isocyanate group-terminated prepolymer (primary reaction product) is reacted with a chain extender to obtain a gas-barrier polyurethane resin (secondary reaction product).

[0181] For example, a polyurethane dispersion can be obtained by reacting an isocyanate-terminated prepolymer with a chain extender in water.

[0182] The chain extender is an organic compound that has a plurality of active hydrogen groups and that causes a chain extension reaction of the isocyanate-terminated prepolymer.

[0183] Chain extenders include, for example, polyamines and amino alcohols.

[0184] Examples of polyamines include aromatic polyamines, araliphatic polyamines, alicyclic polyamines, aliphatic polyamines, and polyoxyethylene group-containing polyamines.

[0185] Aromatic polyamines include, for example, 4,4'-diphenylmethanediamine and tolylenediamine.

[0186] Araliphatic polyamines include, for example, 1,3-xylylenediamine and 1,4-xylylenediamine.

[0187] Examples of alicyclic polyamines include 3-aminomethyl-3,5,5-trimethylcyclohexylamine (also known as isophoronediamine), 4,4'-dicyclohexylmethanediamine, 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 1,4-cyclohexanediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis-(4-aminocyclohexyl)methane, diaminocyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,3-bis(aminomethyl)cyclohexane, and 1,4-bis(aminomethyl)cyclohexane.

[0188] Examples of aliphatic polyamines include ethylenediamine, propylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexamethylenediamine, hydrazine, hydrazine hydrate, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,2-diaminoethane, 1,2-diaminopropane, and 1,3-diaminopentane.

[0189] Examples of polyoxyethylene group-containing polyamines include polyoxyalkylene ether diamines. Examples of polyoxyalkylene ether diamines include polyoxyethylene ether diamines. More specific examples include PEG#1000 Diamine (manufactured by NOF Corp.), Jeffamine ED-2003 (manufactured by Huntsman), Jeffamine EDR-148 (manufactured by Huntsman), and Jeffamine XTJ-512 (manufactured by Huntsman).

[0190] Examples of amino alcohols include 2-((2-aminoethyl)amino)ethanol (also known as N-(2-aminoethyl)ethanolamine) and 2-((2-aminoethyl)amino)-1-methylpropanol (also known as N-(2-aminoethyl)isopropanolamine).

[0191] Further examples of the chain extender include alkoxysilyl compounds having a primary amino group, and alkoxysilyl compounds having a primary amino group and a secondary amino group.

[0192] Examples of alkoxysilyl compounds having a primary amino group include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane.

[0193] Examples of alkoxysilyl compounds having a primary amino group and a secondary amino group include N-β(aminoethyl)γ-aminopropyltrimethoxysilane (also known as N-2-(aminoethyl)-3-aminopropyltrimethoxysilane), N-β(aminoethyl)γ-aminopropyltriethoxysilane (also known as N-2-(aminoethyl)-3-aminopropyltriethoxysilane), N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane (also known as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane), and N-β(aminoethyl)γ-aminopropylmethyldiethoxysilane (also known as N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane).

[0194] These chain extenders can be used alone or in combination of two or more.

[0195] The chain extender is preferably an amino alcohol, more preferably 2-((2-aminoethyl)amino)ethanol.

[0196] The method for reacting the isocyanate group-terminated prepolymer with the chain extender in water is not particularly limited.

[0197] For example, first, an isocyanate-terminated prepolymer is dispersed in water, and then a chain extender is added to the aqueous dispersion of the isocyanate-terminated prepolymer, and the chain of the isocyanate-terminated prepolymer is extended by the chain extender.

[0198] The method for dispersing the isocyanate group-terminated prepolymer in water is not particularly limited.

[0199] For example, the isocyanate-terminated prepolymer is added to water while stirring the water, in which case the amount of water is 100 to 1000 parts by mass per 100 parts by mass of the isocyanate-terminated prepolymer.

[0200] Thereafter, the chain extender is dropped into the water in which the isocyanate-terminated prepolymer is dispersed while stirring the water, in which the equivalent ratio of the active hydrogen groups of the chain extender to the isocyanate groups of the isocyanate-terminated prepolymer (active hydrogen groups / isocyanate groups) is, for example, 0.6 to 1.2.

[0201] The chain extension reaction is completed, for example, at room temperature, and the time required for the reaction to be completed is, for example, 0.1 to 10 hours.

[0202] In this method, the organic solvent and / or water can be removed after the reaction is complete to adjust the solids concentration, and water can be added after the reaction is complete to adjust the solids concentration.

[0203] This gives a polyurethane dispersion (PUD) as a barrier coating agent.

[0204] The polyurethane dispersion has a solids concentration of, for example, 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, and for example, 60% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less.

[0205] The polyurethane dispersion has a pH of, for example, 5 or more, or preferably 6 or more. The polyurethane dispersion has a pH of, for example, 11 or less, or preferably 10 or less.

[0206] The polyurethane dispersion has an average particle size of, for example, 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more, and for example, 500 nm or less, preferably 300 nm or less, more preferably 200 nm or less.

[0207] In addition, the total concentration of urethane groups and urea groups in the polyurethane dispersion is relatively high. By increasing the concentrations of urethane groups and urea groups, it is possible to improve the gas barrier properties.

[0208] The sum of the urethane group concentration and the urea group concentration is, for example, 30% by mass or more, preferably 34% by mass or more, more preferably 38% by mass or more. The sum of the urethane group concentration and the urea group concentration is, for example, 50% by mass or less, preferably 46% by mass or less, more preferably 42% by mass or less. The sum of the urethane group concentration and the urea group concentration can be calculated from the charging ratio of the raw material components.

[0209] The barrier coat layer 4 is formed, for example, by applying a barrier coat agent to the anchor coat layer 3 and drying it.

[0210] The method for applying the barrier coating agent is not particularly limited, and examples of the application method include dip coating, gravure coating, reverse coating, roll coating, bar coating, spray coating, and air knife coating.

[0211] The drying conditions for the barrier coating agent are not particularly limited. For example, the drying temperature is, for example, 40°C or higher, preferably 50°C or higher. The drying temperature is, for example, 200°C or lower, preferably 180°C or lower. The drying time is, for example, 0.1 minutes or longer, preferably 0.2 minutes or longer. The drying time is, for example, 10 minutes or shorter, preferably 5 minutes or shorter.

[0212] As a result, the barrier coating layer 4 is formed.

[0213] Furthermore, the barrier coating layer 4 can be cured as necessary.

[0214] The curing conditions for the barrier coating layer 4 are not particularly limited. For example, the curing temperature is, for example, 20°C or higher, preferably 30°C or higher. The curing temperature is, for example, 100°C or lower, preferably 80°C or lower. The curing time is, for example, 1 hour or longer, preferably 10 hours or longer. The curing time is, for example, 10 days or shorter, preferably 7 days or shorter.

[0215] From the viewpoint of improving production efficiency and shortening lead time, the barrier coating layer 4 is preferably not cured.

[0216] The barrier coating layer 4 may also contain additives.

[0217] Examples of additives include fillers, silane coupling agents, alkoxysilane compounds, thickeners, antioxidants, heat stabilizers, UV absorbers, plasticizers, antistatic agents, lubricants, antiblocking agents, surfactants, dispersion stabilizers, colorants, pigments, dyes, colloidal silica, inorganic particles, inorganic oxide particles, nucleating agents, crosslinking agents, and curing agents. These additives can be used alone or in combination of two or more. The blending ratio of the additives is not particularly limited and can be appropriately set depending on the purpose and application.

[0218] The additive is preferably a filler, such as an organic nanofiber or a layered inorganic compound, more preferably a layered inorganic compound.

[0219] If the barrier coat layer 4 contains a layered inorganic compound, the laminate 1 having excellent gas barrier properties can be obtained.

[0220] Examples of fillers include organic nanofibers and layered inorganic compounds.

[0221] As the filler, from the viewpoint of gas barrier properties, a layered inorganic compound is preferably used.

[0222] Examples of the layered inorganic compound include a swellable layered inorganic compound and a non-swellable layered inorganic compound.

[0223] As the layered inorganic compound, from the viewpoint of gas barrier properties, a swellable layered inorganic compound is preferably used.

[0224] The swellable layered inorganic compound is a clay mineral consisting of extremely thin unit crystals. The swellable layered inorganic compound has the property of swelling due to the coordination and / or absorption of a solvent between the unit crystal layers.

[0225] Examples of the swellable layered inorganic compounds include hydrous silicates, kaolinite-based clay minerals, antigorite-based clay minerals, smectite-based clay minerals, vermiculite-based clay minerals, and mica-based clay minerals.

[0226] Examples of hydrous silicates include phyllosilicate minerals.

[0227] Examples of kaolinite group clay minerals include halloysite, kaolinite, endelite, dickite, and nacrite.

[0228] Antigorite group clay minerals include, for example, antigorite and chrysotile.

[0229] Examples of smectite group clay minerals include montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite.

[0230] Vermiculite clay minerals include, for example, vermiculite.

[0231] Examples of mica group clay minerals include mica, margarite, tetrasilylic mica, taeniolite, and synthetic mica.

[0232] The swellable layered inorganic compound may be a natural clay mineral or a synthetic clay mineral.

[0233] The swellable layered inorganic compounds can be used alone or in combination of two or more.

[0234] As the swellable layered inorganic compound, preferably, smectite clay minerals, mica clay minerals and synthetic mica are used, and more preferably, synthetic mica is used.

[0235] The filler has an average particle size of, for example, 50 nm or more, or preferably 100 nm or more.

[0236] The average particle size of the filler is, for example, 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less.

[0237] The aspect ratio of the filler is, for example, 50 or more, preferably 100 or more, or more preferably 200 or more.

[0238] The aspect ratio of the filler is, for example, 5000 or less, preferably 3000 or less, or more preferably 2000 or less.

[0239] The filler may be blended as 100% solids, or may be blended as a dispersion in which the filler is dispersed in a solvent.

[0240] The blending ratio of the filler is not particularly limited.

[0241] For example, the amount of the filler relative to 100 parts by mass of the gas barrier polyurethane resin is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, and more preferably 30 parts by mass or more.

[0242] The amount of the filler relative to 100 parts by mass of the gas barrier polyurethane resin is, for example, 70 parts by mass or less, or preferably 60 parts by mass or less.

[0243] The additive is added to, for example, a barrier coating agent, which is then applied to the paper substrate 2 together with a gas-barrier polyurethane resin and dried.

[0244] The timing of adding the additive is not particularly limited. For example, the additive may be added during synthesis of the gas barrier polyurethane resin. Alternatively, the additive may be added to a polyurethane dispersion containing the gas barrier polyurethane resin.

[0245] In the polyurethane dispersion, the total concentration (solids concentration) of the gas barrier polyurethane resin and additives is, for example, 10 mass % or more, preferably 15 mass % or more, and more preferably 20 mass % or more.

[0246] In addition, in the polyurethane dispersion, the total concentration (solids concentration) of the gas barrier polyurethane resin and additives is, for example, 60 mass % or less, preferably 50 mass % or less, and more preferably 40 mass % or less.

[0247] Then, a polyurethane dispersion containing a gas barrier polyurethane resin and additives is applied to the anchor coat layer 3 under the above conditions and dried, thereby forming a barrier coat layer 4 containing a gas barrier polyurethane resin and additives.

[0248] The amount of the barrier coat layer 4 is, for example, 0.1 g / m ２ More than 0.3 g / m ２ More preferably, 0.5 g / m ２ More preferably, 1.0 g / m ２ More preferably, 1.5 g / m ２ The amount of the barrier coat layer 4 is, for example, 30.0 g / m ２ Preferably, 20.0 g / m or less ２ More preferably, 10.0 g / m or less ２ More preferably, 5.0 g / m or less ２ Below, particularly preferably 3.0 g / m ２ The following is the result.

[0249] When the amount of the barrier coat layer 4 is within the above range, a laminate 1 having excellent gas barrier properties can be obtained.

[0250] The laminate 1 may further include a functional layer (not shown). The functional layer is, for example, a resin layer that imparts desired functionality to the laminate 1.

[0251] The functional layer is disposed by a known method on one side of the barrier coating layer 4 and / or the other side of the paper substrate 2. For example, the functional layer is formed by applying and drying an ionomer.

[0252] The functionality imparted by the functional layer includes, for example, water resistance, oil resistance, and heat sealability.

[0253] In the laminate 1, the density of the paper base material 2 is above a predetermined lower limit, so that the degree of penetration of the anchor coat layer 3 and the barrier coat layer 4 into the paper base material 2 can be adjusted appropriately.

[0254] Furthermore, in the laminate 1, the density of the paper base material 2 is below a predetermined upper limit. Therefore, the anchor coat layer 3 and the barrier coat layer 4 can be disposed on the paper base material 2 with good orientation.

[0255] As a result, the laminate 1 has excellent gas barrier properties, and in particular has excellent gas barrier properties in an uncured state.

[0256] The air resistance of the laminate 1 in an uncured state is, for example, 30,000 s or more, preferably 50,000 s or more, more preferably 70,000 s or more, and still more preferably 100,000 s or more.

[0257] The air resistance is measured in accordance with JIS P 8117 (2009).

[0258] Furthermore, the air resistance of the uncured laminate 1 can be adjusted by selecting a paper base material 2 with a predetermined density. That is, by using a paper base material 2 with a predetermined density, a laminate 1 with excellent air resistance in an uncured state can be obtained.

[0259] The oxygen transmission rate (OTR) of the laminate 1 in an uncured state is, for example, 800 cc / m at 20°C and a relative humidity of 70%. ２ ·day·atm or less, preferably 500cc / m ２ ·day·atm or less, more preferably 100cc / m ２ ·day·atm or less, more preferably 50 cc / m ２ ·day·atm or less, more preferably 10 cc / m ２ ·day·atm or less, more preferably 5 cc / m ２ ·day·atm or less, more preferably 3 cc / m ２ ·day·atm or less, particularly preferably 2 cc / m ２ The oxygen transmission rate (OTR) of the laminate 1 is, for example, 0.001 cc / m ２ ・day・atm or more.

[0260] The oxygen permeability is measured in accordance with JIS K 7126-2 (2006).

[0261] The laminate 1 has excellent gas barrier properties and is therefore suitable for use in various industrial fields. Preferably, the laminate 1 is suitable for use as a food packaging material.

[0262] In other words, the food packaging material preferably comprises the laminate 1 described above.

[0263] Therefore, the food packaging material has excellent gas barrier properties, particularly in an uncured state.

[0264] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are by mass unless otherwise specified. Furthermore, specific numerical values ​​such as blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be substituted with the corresponding upper limit values ​​(numeric values ​​defined as "equal to or less than") or lower limit values ​​(numeric values ​​defined as "equal to or more than" or "exceeding") of the blending ratios (content ratios), physical property values, parameters, etc. described in the above "Modes for Carrying Out the Invention."

[0265] The following raw material components were reacted in a nitrogen atmosphere at 65 to 70° C. until the isocyanate group concentration (NCO%) reached 6.79% by mass or less, thereby obtaining a reaction liquid containing an isocyanate-terminated prepolymer.

[0266] Raw material components: 1,3-xylylene diisocyanate (Takenate 500, 1,3-XDI, manufactured by Mitsui Chemicals, Inc.) 169.9 parts by mass; 1,3-hydrogenated xylylene diisocyanate (Takenate 600, 1,3-H ６ XDI (Mitsui Chemicals, Inc.) 29.2 parts by mass Ethylene glycol 35.9 parts by mass Trimethylolpropane 3.4 parts by mass Dimethylolpropionic acid 18.2 parts by mass Methyl ethyl ketone (solvent) 115.8 parts by mass

[0267] The reaction mixture was then cooled to 40°C.

[0268] Next, 13.6 parts by weight of triethylamine was added to the reaction solution to neutralize the isocyanate-terminated prepolymer.

[0269] The reaction solution was then dispersed in 751.5 parts by mass of ion-exchanged water using a homodisper. An aqueous amine solution was then added to the resulting dispersion to carry out a chain extension reaction, followed by aging for 1 hour. The aqueous amine solution was a mixture of 59.6 parts by mass of ion-exchanged water and 29.8 parts by mass of 2-((2-aminoethyl)amino)ethanol.

[0270] Thereafter, the methyl ethyl ketone and ion-exchanged water were distilled off using an evaporator, thereby adjusting the solid content concentration to 30% by mass.

[0271] This gave a polyurethane dispersion containing a gas-barrier polyurethane resin.

[0272] 28.3 parts by mass of the polyurethane dispersion (solid content concentration 30%) obtained in Synthesis Example 1, 25.0 parts by mass of an aqueous dispersion of synthetic mica (NTS-5, manufactured by Topy Industries, Ltd., solid content concentration 6% by mass), and 46.7 parts by mass of water were mixed to obtain a barrier coating agent.

[0273] Production Example 2 (Barrier Coating Agent) 33.3 parts by mass of the polyurethane dispersion (solid content concentration 30%) obtained in Synthesis Example 1, 10 parts by mass of isopropanol as a solvent, and 56.7 parts by mass of water were mixed to obtain a barrier coating agent.

[0274] Preparation Examples 1 to 10 (Anchor Coating Agents) Anchor coating agents were prepared according to the formulations shown in Table 1.

[0275] In Preparation Example 1, an anchor coating agent containing a polyurethane resin was obtained by reacting an acrylic polyol with a trimethylolpropane adduct of xylylene diisocyanate in ethyl acetate.

[0276] In Preparation Examples 2 and 3, the solids concentration of the polyurethane dispersion obtained in Synthesis Example 1 was adjusted with water and / or alcohol to obtain anchor coating agents.

[0277] In Preparation Examples 4 to 11, the solid content of a commercially available anchor coating resin was adjusted with water or ethyl acetate to obtain an anchor coating agent.

[0278]

[0279] Details of the abbreviations in the table are given below.

[0280] PUD: polyurethane dispersion of Synthesis Example 1 NTS-5: manufactured by Topy Industries, Ltd., aqueous dispersion of synthetic mica, solid content concentration 6% by mass XMU-18: manufactured by Mitsui Chemicals, Ltd., ethyl acetate solution of acrylic polyol, solid content concentration 50% by mass D-110N: manufactured by Mitsui Chemicals, Inc., ethyl acetate solution of xylylene diisocyanate trimethylolpropane adduct, solid content concentration 75% by mass W-6061: manufactured by Mitsui Chemicals, Inc., aqueous dispersion of water-dispersed polyurethane resin, solid content concentration 30% by mass OHP-51b: manufactured by Mitsui Chemicals, Inc., aqueous dispersion of water-dispersed acrylic resin, solid content concentration 25% by mass EP501H: manufactured by Mitsui Chemicals, Inc., aqueous dispersion of water-dispersed polyolefin resin, solid content concentration 45% by mass Aqueous solution of chitosan acetic acid neutralizer: an aqueous solution prepared by adding 10 g of chitosan (Tokyo Chemical Industry Co., Ltd.) to 10 g of acetic acid and diluting the solution with pure water to a solid content concentration of 20% Water-dispersed polyethyleneimine: manufactured by MICA Corporation, trade name A-131-X, water dispersion of polyethyleneimine, solid content concentration 5% by mass. PVA210: manufactured by Kuraray Co., Ltd., polyvinyl alcohol. SR116: manufactured by Nippon A&L Co., Ltd., water dispersion of carboxy-modified styrene-butadiene copolymer, solid content concentration 50.5% by mass. IPA: manufactured by Tokyo Chemical Industry Co., Ltd., isopropanol, solvent. Ethyl acetate: manufactured by Tokyo Chemical Industry Co., Ltd., solvent.

[0281] Examples 1 to 14 and Comparative Examples 1 to 3 Paper substrates shown in Tables 2 to 4 were prepared.

[0282] Next, the anchor coating agent was applied to the surface of the paper substrate using a bar coater according to the descriptions in Tables 2 to 4, and dried at 120° C. for 90 seconds, thereby forming an anchor coating layer.

[0283] Thereafter, a barrier coating agent was applied to the surface of the anchor coating layer using a bar coater according to the descriptions in Tables 2 to 4, and dried at 120° C. for 90 seconds, thereby forming a barrier coating layer.

[0284] This resulted in a laminate.

[0285] In each of the examples and comparative examples, the barrier coating layer was not cured.

[0286] Reference Example 1 A laminate was obtained in the same manner as in Comparative Example 3, except that the barrier coating layer was cured at 40° C. for 3 days.

[0287] <Evaluation> (1) Air Resistance The air resistance of the laminate was measured using an Oken type air permeability smoothness tester (manufactured by Asahi Seiko Co., Ltd.).

[0288] The measurement was performed in accordance with JIS P 8117 (2009).

[0289] (2) Appearance The appearance of the laminate was observed and evaluated according to the following criteria: ○: No problem; △: Slight whitening of the laminate was observed; ×: Whitening of the laminate and / or peeling of the barrier coat layer was observed.

[0290] (3) Oxygen Transmission Rate (OTR) The oxygen transmission rate of the laminate was measured using an oxygen transmission rate measuring device (MOCON, OX-TRAN2 / 20).

[0291] The measurement conditions were set to 20° C. and a relative humidity of 70% (70% RH).

[0292] The measurement was carried out in accordance with JIS K 7126-2 (2006).

[0293] Also, 1 m ２ , oxygen transmission rate per day and atmosphere (cc / m ２ ·day·atm) was measured.

[0294]

[0295]

[0296]

[0297] The details of the paper substrate are as follows: Glassine paper A: density 1.24 g / cm ３ , basis weight 30.8g / m ２ Glassine paper B: density 1.15 g / cm ３ , basis weight 32.1g / m２ Coated paper: density 1.17 g / cm ３ , basis weight 68.0g / m ２ Single gloss kraft paper: density 0.73 g / cm ３ , basis weight 73.1g / m ２ Bleached neutral paper: density 0.71g / cm ３ , basis weight 71.3g / m ２

[0298] The above invention is provided as an exemplary embodiment of the present invention, but it is merely an example and should not be interpreted as being limiting. Modifications of the present invention that are obvious to those skilled in the art are intended to be included in the scope of the following claims.

[0299] The laminate and food packaging material of the present invention are suitably used in the food packaging field.

[0300] REFERENCE SIGNS LIST 1 Laminate 2 Paper substrate 3 Anchor coat layer 4 Barrier coat layer

Claims

1. A paper substrate, an anchor coat layer disposed on one side of the paper substrate, and a barrier coat layer disposed on one side of the anchor coat layer, wherein the density of the paper substrate is 0.72 g / cm ３ The laminate as described above, wherein the barrier coat layer contains a gas barrier polyurethane resin.

2. The laminate according to claim 1, characterized in that the air resistance measured in accordance with JIS P 8117 (2009) is 30,000 s or more.

3. The laminate according to claim 1, wherein in the barrier coat layer, the gas barrier polyurethane resin comprises an isocyanate-terminated prepolymer which is a primary reaction product between a polyisocyanate component containing xylylene diisocyanate and / or hydrogenated xylylene diisocyanate, a short-chain diol having 2 to 6 carbon atoms, and an active hydrogen group-containing component containing an active hydrogen compound containing a hydrophilic group, and a secondary reaction product with a chain extender.

4. The laminate according to claim 1, characterized in that the barrier coat layer further contains a layered inorganic compound.

5. The amount of the barrier coat layer is 0.5 g / cm ２ 20.0g / cm or more ２ The laminate according to claim 1 , characterized in that:

6. The amount of the anchor coat layer is 0.3 g / cm ２ 20.0g / cm or more ２ The laminate according to claim 1 , characterized in that:

7. A food packaging material comprising the laminate according to claim 1.