Polyurethane dispersion, gas barrier coating material and laminate

Abstract

To provide a polyurethane dispersion and a gas barrier coating material which are capable of forming a polyurethane layer excellent in gas barrier properties, and to provide a laminate including the polyurethane layer.SOLUTION: The polyurethane dispersion is an aqueous dispersion of a polyurethane resin. The polyurethane resin is a reaction product of an isocyanate group-terminated prepolymer and ammonia. The isocyanate group-terminated prepolymer contains a reaction product of: a polyisocyanate component which contains an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate; and an active hydrogen group-containing component which contains a C2-6 short-chain diol and an active hydrogen group-containing compound containing an anionic group. The ammonia blocks isocyanate groups at molecular terminals of the isocyanate group-terminated prepolymer and neutralizes the anionic group. The content of the aromatic ring-containing isocyanate is 50 mass% or more based on the total amount of the aromatic ring-containing isocyanate and the alicyclic ring-containing isocyanate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polyurethane dispersion, a gas barrier coating material, and a laminate. [Background technology]

[0002] 2. Description of the Related Art It is conventionally known to impart gas barrier properties to a substrate by forming a resin layer containing a polyurethane resin (hereinafter referred to as a polyurethane layer) on the surface of the substrate.

[0003] The following method has been proposed for producing a polyurethane resin. First, 112.9 g of XDI, 185.5 g of NBDI, 55.9 g of ethylene glycol, and 40.2 g of dimethylolpropionic acid are reacted to obtain a carboxyl group-containing urethane prepolymer. Next, 61.2 g of 25% by weight ammonia water is added to the carboxyl group-containing urethane prepolymer to block the isocyanate residues and neutralize the carboxyl groups. After that, water is added to the reaction product to emulsify and disperse it. This produces a water-dispersed polyurethane resin (see, for example, Patent Document 1 (Production Example 1)). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-193657 A Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, the polyurethane layer is required to have a further improved gas barrier property.

[0006] The present invention relates to a polyurethane dispersion capable of forming a polyurethane layer having excellent gas barrier properties, a gas barrier coating material, and further to a laminate comprising a polyurethane layer. [Means for solving the problem]

[0007] The present invention [1] is a polyurethane dispersion which is a water dispersion of a polyurethane resin, the polyurethane resin being a reaction product of an isocyanate-terminated prepolymer and ammonia, the isocyanate-terminated prepolymer comprising a reaction product of a polyisocyanate component containing an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate, and an active hydrogen group-containing component containing a short-chain diol having 2 to 6 carbon atoms, and an active hydrogen group-containing compound containing an anionic group, the ammonia capping the isocyanate groups at the molecular terminals of the isocyanate-terminated prepolymer and neutralizing the anionic groups, the aromatic ring-containing isocyanate accounting for 50 mass% or more of the total amount of the aromatic ring-containing isocyanate and the alicyclic ring-containing isocyanate.

[0008] The present invention [2] includes the polyurethane dispersion according to the above [1], in which the polyurethane resin has a number average molecular weight of 800 or more and 1,300 or less.

[0009] The present invention [3] further includes the polyurethane dispersion according to the above [1] or [2], which contains a layered inorganic compound.

[0010] The present invention [4] includes a gas barrier coating material containing the polyurethane dispersion according to any one of the above [1] to [3].

[0011] The present invention [5] includes a laminate comprising a substrate and a polyurethane layer disposed on the surface of the substrate, the polyurethane layer being a dried product of the gas barrier coating material described in [4] above. Effect of the Invention

[0012] In the polyurethane dispersion of the present invention, the polyurethane resin is a reaction product of an isocyanate-terminated prepolymer and ammonia. The isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer are blocked with ammonia. Furthermore, the anionic groups are neutralized with ammonia. The polyisocyanate component, which is the raw material of the isocyanate-terminated prepolymer, contains an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate in a predetermined ratio. Therefore, the polyurethane dispersion of the present invention contains a polyurethane resin with excellent gas barrier properties.

[0013] As a result, the polyurethane dispersion and gas barrier coating material of the present invention can form a polyurethane layer with excellent gas barrier properties.

[0014] In the laminate of the present invention, the polyurethane layer is a dried product of the gas barrier coating material, and therefore the laminate of the present invention has excellent gas barrier properties. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of a laminate of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The polyurethane dispersion of the present invention is an aqueous dispersion of a polyurethane resin. Examples of the polyurethane resin include gas-barrier polyurethane resins. Gas-barrier properties are the property of reducing oxygen permeability.

[0017] The polyurethane resin is a reaction product obtained by reacting an isocyanate-terminated prepolymer with ammonia. The isocyanate-terminated prepolymer is a reaction product obtained by reacting a polyisocyanate component with an active hydrogen group-containing component.

[0018] In other words, 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 ammonia.

[0019] The isocyanate-terminated prepolymer is a polyurethane prepolymer having two or more free isocyanate groups at the molecular terminals. As described above, the isocyanate-terminated prepolymer is obtained by reacting a polyisocyanate component with an active hydrogen group-containing component.

[0020] The polyisocyanate component contains, as essential components, an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate, and preferably consists of an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate.

[0021] The aromatic ring-containing isocyanate is a polyisocyanate containing one or more aromatic rings and two or more isocyanate groups in one molecule. Examples of the aromatic ring-containing isocyanate include aromatic polyisocyanates and araliphatic polyisocyanates.

[0022] Examples of aromatic polyisocyanates include aromatic polyisocyanate monomers and aromatic polyisocyanate derivatives. Examples of aromatic polyisocyanate monomers include aromatic diisocyanates. Examples of aromatic diisocyanates include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), toluidine diisocyanate (TODI), paraphenylene diisocyanate, and naphthalene diisocyanate (NDI). Examples of aromatic polyisocyanate derivatives include modified products obtained by modifying aromatic polyisocyanate monomers by known methods. Examples of modified products include uretdione modified products, isocyanurate modified products, allophanate modified products, polyol modified products, biuret modified products, urea modified products, oxadiazinetrione modified products, and carbodiimide modified products. These can be used alone or in combination of two or more types.

[0023] Examples of the araliphatic polyisocyanate include araliphatic polyisocyanate monomers and araliphatic polyisocyanate derivatives. Examples of the araliphatic polyisocyanate monomers include araliphatic diisocyanates. Examples of the araliphatic diisocyanates include xylylene diisocyanate (XDI) and tetramethyl xylylene diisocyanate (TMXDI). Examples of the araliphatic polyisocyanate derivatives include the above-mentioned modified products of the araliphatic polyisocyanate monomers. These can be used alone or in combination of two or more kinds.

[0024] The aromatic ring-containing isocyanate may be used alone or in combination of two or more kinds. As the aromatic ring-containing isocyanate, preferably, araliphatic polyisocyanate is used, more preferably, araliphatic polyisocyanate monomer is used, further preferably, araliphatic diisocyanate is used, and particularly preferably, xylylene diisocyanate (XDI) is used.

[0025] Examples of xylylene diisocyanate (XDI) include 1,2-xylylene diisocyanate (o-XDI), 1,3-xylylene diisocyanate (m-XDI), and 1,4-xylylene diisocyanate (p-XDI). These can be used alone or in combination of two or more. Examples of xylylene diisocyanate (XDI) include preferably 1,3-xylylene diisocyanate (m-XDI) and 1,4-xylylene diisocyanate (p-XDI), and more preferably 1,3-xylylene diisocyanate (m-XDI).

[0026] The alicyclic ring-containing isocyanate is a polyisocyanate containing one or more alicyclic rings and two or more isocyanate groups in one molecule. Examples of the alicyclic ring-containing isocyanate include alicyclic polyisocyanates.

[0027] Examples of the alicyclic polyisocyanate include alicyclic polyisocyanate monomers and alicyclic polyisocyanate derivatives. Examples of the alicyclic polyisocyanate monomers include alicyclic diisocyanates. Examples of the alicyclic diisocyanates include isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), methylene bis(cyclohexyl isocyanate) (H 12 Examples of the alicyclic polyisocyanate derivatives include the above-mentioned modified products of the alicyclic polyisocyanate monomers. These can be used alone or in combination of two or more kinds.

[0028] The alicyclic ring-containing isocyanate may be used alone or in combination of two or more kinds. As the alicyclic ring-containing isocyanate, preferably, an alicyclic polyisocyanate is used, more preferably, an alicyclic polyisocyanate monomer is used, further preferably, an alicyclic diisocyanate is used, and further preferably, methylenebis(cyclohexylisocyanate)(H 12 MDI), and bis(isocyanatomethyl)cyclohexane (H6XDI).

[0029] As the alicyclic isocyanate, particularly preferred is methylene bis(cyclohexyl isocyanate) (H 12 MDI) and bis(isocyanatomethyl)cyclohexane (H6XDI) in combination. 12 When bis(isocyanatomethyl)cyclohexane (H6XDI) and bis(isocyanatomethyl)cyclohexane (H6XDI) are used in combination, their ratio is set from the viewpoint of gas barrier properties.

[0030] For example, methylenebis(cyclohexyl isocyanate) (H 12 Methylenebis(cyclohexylisocyanate) (H MDI) and bis(isocyanatomethyl)cyclohexane (H6XDI) for a total of 100 parts by mass 12MDI) is, for example, 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more. 12 MDI) is, for example, 90 parts by mass or less, preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 30 parts by mass or less. 12 For a total of 100 parts by mass of MDI and bis(isocyanatomethyl)cyclohexane (H6XDI), the amount of bis(isocyanatomethyl)cyclohexane (H6XDI) 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 even more preferably 70 parts by mass or more. The amount of bis(isocyanatomethyl)cyclohexane (H6XDI) is, for example, 99 parts by mass or less, preferably 95 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less.

[0031] The polyisocyanate component may also contain a chain aliphatic polyisocyanate as an optional component. The chain aliphatic polyisocyanate is a polyisocyanate that does not contain an aromatic ring or an alicyclic ring in one molecule and contains two or more isocyanate groups. Examples of the chain aliphatic polyisocyanate include a chain aliphatic polyisocyanate monomer and a chain aliphatic polyisocyanate derivative. Examples of the chain aliphatic polyisocyanate monomer include ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI) and hexamethylene diisocyanate (HDI). Examples of the chain aliphatic polyisocyanate derivative include the above-mentioned modified products of the chain aliphatic polyisocyanate monomer. These may be used alone or in combination of two or more types.

[0032] In the polyisocyanate component, the content ratio of the chain aliphatic polyisocyanate is appropriately set within a range that does not impair the excellent effects of the present invention. More specifically, the content ratio of the chain aliphatic polyisocyanate is, for example, 50 mass% or less, preferably 30 mass% or less, more preferably 10 mass% or less, and particularly preferably 0 mass% based on the total amount of the polyisocyanate component. That is, the content ratio of the aromatic ring-containing isocyanate and / or the alicyclic ring-containing isocyanate is, for example, 50 mass% or more, preferably 70 mass% or more, more preferably 90 mass% or more, and particularly preferably 100 mass% based on the total amount of the polyisocyanate component. In other words, the polyisocyanate component preferably does not contain a chain aliphatic polyisocyanate, and is composed of an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate.

[0033] In the polyisocyanate component, the content of the aromatic ring-containing isocyanate is greater than the content of the alicyclic ring-containing isocyanate.

[0034] More specifically, the aromatic ring-containing isocyanate is 50% by mass or more, preferably more than 50% by mass, more preferably 55% by mass or more, and even more preferably 60% by mass or more, based on the total amount of the aromatic ring-containing isocyanate and the alicyclic ring-containing isocyanate. The aromatic ring-containing isocyanate is 99% by mass or less, preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. The alicyclic ring-containing isocyanate is, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, based on the total amount of the aromatic ring-containing isocyanate and the alicyclic ring-containing isocyanate. The alicyclic ring-containing isocyanate is, for example, 50% by mass or less, preferably less than 50% by mass, more preferably 45% by mass or less, and even more preferably 40% by mass or less.

[0035] When the content of the aromatic ring-containing isocyanate and the content of the alicyclic ring-containing isocyanate are within the above ranges, a polyurethane resin having particularly excellent gas barrier properties can be obtained.

[0036] An example of the active hydrogen group-containing component is a polyol component, which essentially contains a short-chain diol having 2 to 6 carbon atoms and an active hydrogen group-containing compound that contains an anionic group.

[0037] The short-chain diol having 2 to 6 carbon atoms has two hydroxyl groups and is an organic compound having 2 to 6 carbon atoms. The molecular weight of the short-chain diol is, for example, 50 or more, and for example, 650 or less, preferably 500 or less, more preferably 400 or less, and further preferably 300 or less. When the short-chain diol has a molecular weight distribution, the molecular weight indicates the number average molecular weight in terms of polystyrene by GPC (gel permeation chromatography).

[0038] Examples of the short chain diol 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.

[0039] Examples of the alkane diol having 2 to 6 carbon atoms include ethylene glycol, propylene glycol, 1,3-propane diol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,5-pentane diol, 1,6-hexane diol, neopentyl glycol, 3-methyl-1,5-pentane diol, 1,3-cyclohexane diol, and 1,4-cyclohexane diol. Examples of the ether diol having 2 to 6 carbon atoms include diethylene glycol, triethylene glycol, and dipropylene glycol. Examples of the alkene diol having 2 to 6 carbon atoms include 1,4-dihydroxy-2-butene. These short chain diols can be used alone or in combination of two or more kinds. As the short chain diol, from the viewpoint of gas barrier properties, preferably, an alkane diol having 2 to 6 carbon atoms is used, and more preferably, ethylene glycol is used.

[0040] 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 active hydrogen group-containing component, is, for example, 10 parts by mass or more, preferably 30 parts by mass or more, and more preferably 50 parts by mass or more, and for example, 90 parts by mass or less, preferably 80 parts by mass or less, and more preferably 70 parts by mass or less.

[0041] The active hydrogen group-containing compound containing anionic group is a compound containing anionic group and active hydrogen group.The anionic group can be exemplified by carboxy group (carboxylic acid group) and sulfo group (sulfonic acid group), and preferably carboxy group.The active hydrogen group can be exemplified by hydroxyl group and amino group, and preferably hydroxyl group.

[0042] As the active hydrogen group-containing compound containing an anionic group, preferably, an organic compound having both a carboxy group and two hydroxyl groups is used.

[0043] An example of an organic compound having both a carboxy group and two hydroxyl groups is a carboxy group-containing polyol. An example of a carboxy group-containing polyol is a polyhydroxyalkanoic acid. An example of a polyhydroxyalkanoic acid is 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. These organic compounds having both a carboxy group and two hydroxyl groups can be used alone or in combination of two or more kinds. An example of an organic compound having both a carboxy group and two hydroxyl groups is preferably 2,2-dimethylolpropionic acid.

[0044] The content ratio of the active hydrogen group-containing compound containing an anionic group, relative to 100 parts by mass of the total amount of the active hydrogen group-containing components, 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.

[0045] The polyol component may further contain other low molecular weight polyols as optional components. 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 anionic groups. The low molecular weight polyols are relatively low molecular weight organic compounds having two or more hydroxyl groups in the molecule. The molecular weight of the low molecular weight polyol is 50 or more and 650 or less, preferably 500 or less. Examples of the other low molecular weight polyols include diols having 7 or more carbon atoms and low molecular weight polyols having a valence of 3 or more.

[0046] 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. These diols having 7 or more carbon atoms can be used alone or in combination of two or more kinds.

[0047] Examples of the low molecular weight polyol having a valence of three or more include trihydric alcohols and tetrahydric alcohols. Examples of the 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. Examples of the tetrahydric alcohols include tetramethylolmethane (pentaerythritol) and diglycerin. These low molecular weight polyols having a valence of three or more can be used alone or in combination of two or more.

[0048] 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.

[0049] The other low molecular weight polyols can be used alone or in combination of two or more. From the viewpoint of water resistance and water dispersion stability, the other low molecular weight polyols are preferably trihydric or higher low molecular weight polyols, more preferably trihydric alcohols, and particularly preferably trimethylolpropane.

[0050] When the active hydrogen group-containing component contains a trihydric or higher alcohol, the ratio of the trihydric or higher alcohol to the total amount of the active hydrogen group-containing component is, for example, 0.1 mol% or more, preferably 1 mol% or more, more preferably 3 mol% or more, and for example, 30 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less. The molar ratio of the trihydric or higher alcohol in the active hydrogen group-containing component is calculated by a known method based on the hydroxyl group equivalent (molecular weight / hydroxyl group number) and the blending amount.

[0051] In addition, when the active hydrogen group-containing component contains other low molecular weight polyols, the content of the other low molecular weight polyols is, per 100 parts by mass of the total amount of the active hydrogen group-containing component, for example, 0.2 parts by mass or more, preferably 1 part by mass or more, and more preferably 2 parts by mass or more, and for example, 20 parts by mass or less, preferably 10 parts by mass or less, and more preferably 8 parts by mass or less.

[0052] The ratio of the short-chain diol having 2 to 6 carbon atoms and the other low-molecular-weight polyol used in combination 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, and more preferably 10 parts by mass or less, per 100 parts by mass of the total amount of them.

[0053] Furthermore, the amount of the active hydrogen group-containing compound containing an anionic group 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 is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, and more preferably 40 parts by mass or more, and for example, 90 parts by mass or less, preferably 80 parts by mass or less, and more preferably 70 parts by mass or less.

[0054] When the content of the other low molecular weight polyol is within the above range, excellent dispersibility can be ensured.

[0055] The polyol component may further contain a high molecular weight polyol as an optional component. The high molecular weight polyol has two or more hydroxyl groups in the molecule and is a relatively high molecular weight organic compound (polymer). The number average molecular weight of the high molecular weight polyol is, for example, more than 650 and, for example, 20,000 or less. Examples of the high molecular weight polyol include polyether polyol, polyester polyol, polycarbonate polyol, polyurethane polyol, epoxy polyol, vegetable oil polyol, polyolefin polyol, acrylic polyol, and vinyl monomer modified polyol. These high molecular weight polyols may be used alone or in combination of two or more kinds.

[0056] However, high molecular weight polyols may deteriorate the gas barrier properties of the polyurethane resin (described later), and therefore the polyol component preferably does not contain high molecular weight polyols.

[0057] That is, the polyol component preferably consists of a short-chain diol having 2 to 6 carbon atoms, a low-molecular-weight polyol having three or more valences, and an active hydrogen group-containing compound containing an anionic group, or consists of a short-chain diol having 2 to 6 carbon atoms and an active hydrogen group-containing compound containing an anionic group.

[0058] The isocyanate-terminated prepolymer is obtained by reacting the above-mentioned components at a predetermined equivalent ratio. In the synthesis of the isocyanate-terminated prepolymer, the equivalent ratio is the equivalent ratio of the isocyanate group to the active hydrogen group (hydroxyl group) (isocyanate group / active hydrogen group).

[0059] The equivalent ratio (isocyanate group / active hydrogen group) is, for example, more than 1, and preferably 1.1 or more. Also, the equivalent ratio (isocyanate group / active hydrogen group) is, for example, 20 or less, and preferably 10 or less.

[0060] In addition, in the synthesis of the isocyanate group-terminated prepolymer, a known polymerization method is adopted. Examples of the polymerization method include bulk polymerization and solution polymerization. From the viewpoint of adjusting the reactivity, the polymerization method is preferably solution polymerization. In bulk polymerization, for example, the above components are mixed and reacted under a nitrogen atmosphere. The reaction temperature is, for example, 75 to 85°C. The reaction time is, for example, 1 to 20 hours. In solution polymerization, for example, the above components are mixed and reacted in an organic solvent under a nitrogen atmosphere. The reaction temperature is, for example, 20 to 80°C. The reaction time is, for example, 1 to 20 hours.

[0061] The organic solvent may be a solvent inactive to the isocyanate group. For example, the organic solvent may be acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, or acetonitrile. These organic solvents may be used alone or in combination of two or more kinds.

[0062] In addition, in the above polymerization, a catalyst can be added as necessary. Examples of the catalyst include amine catalysts and organometallic catalysts. These catalysts can be used alone or in combination of two or more kinds. The amount of catalyst added is appropriately set according to the purpose and application.

[0063] 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.

[0064] This gives an isocyanate-terminated prepolymer.

[0065] From the viewpoint of adjusting the number average molecular weight of the polyurethane resin to the range described below, the isocyanate group concentration of the isocyanate group-terminated prepolymer is, for example, 1.5 mass% or more, preferably 2.0 mass% or more, more preferably 3.0 mass% or more, and even more preferably 4.0 mass% or more. The isocyanate group concentration of the isocyanate group-terminated prepolymer is, for example, 8.0 mass% or less, preferably 7.0 mass% or less, more preferably 6.0 mass% or less, and even more preferably 5.5 mass% or less.

[0066] The acid value of the isocyanate-terminated prepolymer is, for example, 20 mgKOH / g or more, preferably 25 mgKOH / g or more. The acid value of the isocyanate-terminated prepolymer is, for example, 45 mgKOH / g or less, preferably 40 mgKOH / g or less. The acid value of the isocyanate-terminated prepolymer can be calculated from the charge ratio of the raw material components.

[0067] 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. The average functionality of the isocyanate groups is, for example, 3.0 or less, preferably 2.5 or less.

[0068] Next, in this method, the isocyanate-terminated prepolymer (first reaction product) is reacted with ammonia to obtain a polyurethane resin (second reaction product).

[0069] More specifically, an isocyanate-terminated prepolymer is reacted with ammonia, for example, in water, and the isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer are blocked with ammonia, and the anionic groups in the isocyanate-terminated prepolymer are neutralized with ammonia, thereby obtaining a polyurethane dispersion.

[0070] In such a method, for example, first, the isocyanate-terminated prepolymer is dispersed in water. The method for dispersing the isocyanate-terminated prepolymer in water is not particularly limited. For example, the isocyanate-terminated prepolymer is added to water while stirring the water. In this case, the amount of water is 100 to 1000 parts by mass per 100 parts by mass of the isocyanate-terminated prepolymer.

[0071] Next, ammonia is supplied to the aqueous dispersion of the isocyanate-terminated prepolymer to cap the isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer with ammonia. That is, the ammonia is a capping agent that caps the isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer.

[0072] In addition, since an active hydrogen group-containing compound containing an anionic group is used as a raw material in the synthesis of the isocyanate-terminated prepolymer, the isocyanate-terminated prepolymer contains an anionic group, and therefore ammonia is also used as a neutralizing agent for neutralizing the anionic group.

[0073] Ammonia may be supplied to the isocyanate group-terminated prepolymer as a gas or as an aqueous solution (ammonia water), for example. Preferably, ammonia is supplied as an aqueous solution. The ammonia concentration in the aqueous solution of ammonia (ammonia water) is not particularly limited and is, for example, 1 to 30 mass%.

[0074] The aqueous solution of ammonia is dropped, for example, into the aqueous dispersion of the isocyanate-terminated prepolymer. The amount of ammonia supplied is set according to the total amount of isocyanate groups and anionic groups in the isocyanate-terminated prepolymer. For example, the equivalent ratio of ammonia (ammonia / isocyanate groups+anionic groups) to the total amount of isocyanate groups and anionic groups in the isocyanate-terminated prepolymer is, for example, 0.6 or more, preferably 0.8 or more, and for example, 1.2 or less, preferably 1.1 or less. The reaction temperature is, for example, 10° C. to 40° C. The reaction time is, for example, 0.1 to 10 hours.

[0075] In this method, the organic solvent and / or water can be removed after the reaction is completed in order to adjust the solid content concentration. In this method, water can be added after the reaction is completed in order to adjust the solid content concentration. In addition, in this method, a solvent can be added in order to adjust the solid content concentration. 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 kinds.

[0076] This produces a polyurethane resin in which the molecular ends of the isocyanate-terminated prepolymer are blocked with ammonia, and a polyurethane dispersion (PUD) in which the polyurethane resin is dispersed in water and / or an organic solvent is obtained.

[0077] The number average molecular weight of the polyurethane resin is relatively small. By reducing the number average molecular weight of the polyurethane resin, it is possible to suppress an increase in viscosity and improve dispersibility. Furthermore, by reducing the number average molecular weight of the polyurethane resin, it is possible to improve the water vapor barrier property in addition to the gas barrier property (oxygen barrier property).

[0078] The number average molecular weight of the polyurethane resin is, for example, 600 or more, preferably 700 or more, more preferably 800 or more, even more preferably 900 or more, and particularly preferably 1000 or more. The number average molecular weight of the polyurethane resin is, for example, 2000 or less, preferably 1700 or less, more preferably 1500 or less, even more preferably 1300 or less, and particularly preferably 1200 or less. The number average molecular weight of the polyurethane resin is measured as a polystyrene-equivalent molecular weight by GPC (gel permeation chromatography) in accordance with the examples described later.

[0079] The solid content concentration of the polyurethane dispersion is, for example, 10 mass% or more, preferably 15 mass% or more, more preferably 20 mass% or more. The solid content concentration of the polyurethane dispersion is, for example, 60 mass% or less, preferably 50 mass% or less, more preferably 40 mass% or less.

[0080] 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.

[0081] The average particle size of the polyurethane dispersion is, for example, 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more.The average particle size of the polyurethane dispersion is, for example, 500 nm or less, preferably 300 nm or less, more preferably 200 nm or less.

[0082] In addition, the polyurethane dispersion has a relatively high urethane group concentration. By increasing the urethane group concentration and the urea group concentration, the gas barrier property can be improved.

[0083] The urethane group concentration is, for example, 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more. The urethane group concentration is, for example, 45% by mass or less, preferably 40% by mass or less, more preferably 35% by mass or less. The urethane group concentration can be calculated from the charging ratio of the raw material components.

[0084] The polyurethane dispersion may also contain additives in appropriate proportions.

[0085] Examples of additives include fillers, silane coupling agents (excluding the curing agents described below), 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, layered inorganic compounds, leveling agents, crystal nucleating agents, crosslinking agents, and curing agents. These additives can be used alone or in combination of two or more.

[0086] In such a polyurethane dispersion, the polyurethane resin is a reaction product of an isocyanate-terminated prepolymer and ammonia. The isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer are blocked with ammonia. Furthermore, the anionic groups are neutralized with ammonia. The polyisocyanate component, which is the raw material of the isocyanate-terminated prepolymer, contains an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate in a predetermined ratio. Therefore, the polyurethane dispersion contains a polyurethane resin with excellent gas barrier properties.

[0087] Therefore, the polyurethane dispersion is suitable for use as a gas barrier coating material.

[0088] The gas barrier coating material contains the above polyurethane dispersion.

[0089] The solid content concentration of the gas barrier coating material can be adjusted by removing water from the polyurethane dispersion. Also, the solid content concentration of the gas barrier coating material can be adjusted by adding water to the polyurethane dispersion. Furthermore, the solid content concentration of the gas barrier coating material can be adjusted by adding the above-mentioned solvent to the polyurethane dispersion.

[0090] The solid content of the gas barrier coating material is, for example, 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more. The solid content of the polyurethane dispersion is, for example, 60% by mass or less, preferably 50% by mass or less, and more preferably 40% by mass or less.

[0091] The gas barrier coating material may also contain additives. Examples of additives include fillers, silane coupling agents (excluding the curing agent described below), 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, layered inorganic compounds, leveling agents, crystal nucleating agents, crosslinking agents, and curing agents. These additives may be used alone or in combination of two or more. The mixing ratio of the additives is not particularly limited and may be appropriately set depending on the purpose and application.

[0092] In the polyurethane dispersion and the gas barrier coating material, the additive is preferably a layered inorganic compound. When the polyurethane dispersion contains a layered inorganic compound, a polyurethane layer having excellent gas barrier properties and water vapor barrier properties can be obtained.

[0093] Examples of the layered inorganic compound include a swellable layered inorganic compound, a non-swellable layered inorganic compound, etc. From the viewpoint of gas barrier property and water vapor barrier property, a swellable layered inorganic compound is preferable.

[0094] The swellable layered inorganic compound is a clay mineral that is composed of extremely thin unit crystals and has the property of coordinating or absorbing and swelling a solvent between the unit crystal layers. Examples of the swellable layered inorganic compound include hydrated silicates, kaolinite clay minerals, antigorite clay minerals, smectite clay minerals, vermiculite clay minerals, and mica clay minerals. These may be natural clay minerals or synthetic clay minerals. These may be used alone or in combination of two or more. As the swellable layered inorganic compound, preferably, smectite clay minerals and mica clay minerals are used, and more preferably, mica clay minerals are used.

[0095] The blending ratio of the layered inorganic compound is, for example, 1 part by mass or more, preferably 10 parts by mass or more, more preferably 100 parts by mass or more, and even more preferably 150 parts by mass or more, relative to 100 parts by mass of the polyurethane resin. The blending ratio of the layered inorganic compound is, for example, 500 parts by mass or less, preferably 400 parts by mass or less, and more preferably 300 parts by mass or less, relative to 100 parts by mass of the polyurethane resin.

[0096] In the polyurethane dispersion and the gas barrier coating material, a curing agent is preferably used as an additive. If the polyurethane dispersion and the gas barrier coating material contain a curing agent, a polyurethane layer having particularly excellent gas barrier properties and water vapor barrier properties can be obtained.

[0097] Examples of the curing agent include epoxy curing agents, melamine curing agents, carbodiimide curing agents, aziridine curing agents, oxazoline curing agents, isocyanate curing agents, and reactive curing agents. These can be used alone or in combination of two or more. Preferred examples of the curing agent include epoxy curing agents, carbodiimide curing agents, and isocyanate curing agents.

[0098] The timing of adding the additive is not particularly limited. For example, the additive may be added to the polyurethane dispersion and the gas barrier coating material before storage. Also, the additive may be added to the polyurethane dispersion and the gas barrier coating material after storage (i.e., the polyurethane dispersion and the gas barrier coating material immediately before use).

[0099] Since such a gas barrier coating material contains the above-mentioned polyurethane dispersion, it can form a polyurethane layer having excellent gas barrier properties, and therefore the gas barrier coating material can be suitably used to produce a laminate having a polyurethane layer as a gas barrier layer.

[0100] In Fig. 1, the laminate 1 includes a substrate 2 and a polyurethane layer 3 disposed on the surface of the substrate 2. Examples of the substrate 2 include plastic, metal-deposited plastic, paper, cloth, wood, metal, and ceramics. These can be used alone or in combination of two or more types.

[0101] The substrate 2 preferably includes plastic, metal-deposited plastic, and paper. The plastic includes, for example, thermoplastic resin and thermosetting resin, and preferably includes thermoplastic resin. The thermoplastic resin includes, for example, polyolefin resin, polyester resin, polyamide resin, vinyl resin, acrylic resin, polycarbonate resin, and cellulose resin. These can be used alone or in combination of two or more kinds. The thermoplastic resin includes, for example, polyolefin resin, polyester resin, and polyamide resin.

[0102] Examples of the substrate 2 include a non-stretched substrate, a uniaxially stretched substrate, and a biaxially stretched substrate. The substrate 2 may be a single layer or a multi-layer. The substrate 2 may be surface-treated. Examples of the surface treatment include a corona discharge treatment and an anchor coat treatment.

[0103] The shape of the substrate 2 may be, for example, a film, a sheet, a bottle, or a cup, with a film being preferred.

[0104] The thickness of the substrate 2 is, for example, 3 μm or more, or preferably 5 μm or more. The thickness of the substrate 2 is, for example, 500 μm or less, or preferably 200 μm or less.

[0105] The polyurethane layer 3 contains the above polyurethane resin, and is preferably formed from the above polyurethane resin. As the polyurethane layer 3, a dried product of a gas barrier coating material is preferably used.

[0106] That is, from the viewpoint of production efficiency, the polyurethane layer 3 is preferably formed by applying a gas barrier coating material to the substrate 2 and drying it. More specifically, to form the polyurethane layer 3, the gas barrier coating material is applied onto the substrate 2 and dried. The method of applying the gas barrier coating material is not particularly limited. Examples of the application method include a dip coating method, a gravure coating method, a reverse coating method, a roll coating method, a bar coating method, a spray coating method, an air knife coating method, and an in-line coating method.

[0107] The drying conditions for the barrier coating material 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 higher, preferably 0.2 minutes or higher. The drying time is, for example, 10 minutes or lower, preferably 5 minutes or lower.

[0108] As a result, a polyurethane layer 3 made of polyurethane resin is formed on the substrate 2. As a result, a laminate 1 including the substrate 2 and the polyurethane layer 3 is obtained.

[0109] Furthermore, the polyurethane layer 3 can be cured as necessary. The curing conditions for the polyurethane layer 3 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.

[0110] The amount of the polyurethane layer 3 is, for example, 0.1 g / m 2 More than 0.2 g / m 2 More preferably, 0.3 g / m 2 The lamination amount of the polyurethane layer 3 is, for example, 10 g / m 2 Preferably, 7 g / m or less 2 Less than 5 g / m 2 The following is the result.

[0111] In addition, in the laminate 1, the polyurethane layer 3 may be an overcoat layer or an anchor coat layer. When the polyurethane layer 3 is an overcoat layer, the polyurethane layer 3 is the outermost layer in the laminate 1. When the polyurethane layer 3 is an anchor coat layer, the polyurethane layer 3 is an intermediate layer in the laminate 1. In such a case, the laminate 1 may further include a deposition layer (not shown) laminated on the polyurethane layer 3. The deposition layer is laminated on the polyurethane layer 3 by a known deposition method.

[0112] The laminate 1 has a total thickness of, for example, 5 μm or more, or preferably 10 μm or more. The laminate 1 has a total thickness of, for example, 1 mm or less, or preferably 0.5 mm or less.

[0113] Such a laminate 1 includes a polyurethane layer 3 obtained by using the above-mentioned gas barrier coating material. More specifically, the polyurethane layer 3 is a dried product of the above-mentioned gas barrier coating material.

[0114] That is, in the laminate 1, the polyurethane layer 3 contains a polyurethane resin. Therefore, the laminate 1 has excellent gas barrier properties. Therefore, the laminate 1 is suitably used in various industrial fields. Preferably, the laminate 1 is suitably used as a packaging material. Examples of packaging materials include food packaging films, pharmaceutical packaging films, food packaging containers, optical films, and industrial films. EXAMPLES

[0115] 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 based on mass unless otherwise specified. In addition, the specific numerical values ​​of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit value (numerical value defined as "less than or equal to" or "less than") or lower limit value (numerical value defined as "more than or equal to" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention".

[0116] Example 1 The following raw material components were reacted in a nitrogen atmosphere at 65 to 70° C. until the isocyanate group concentration (NCO%) reached 3.8 mass % or less, thereby obtaining a reaction liquid containing an isocyanate group-terminated prepolymer.

[0117] Raw material ingredients 1,3-Xylylene Diisocyanate (Takenate 500, 1,3-XDI, manufactured by Mitsui Chemicals) 121.4 parts by mass 1,3-Bis(isocyanatomethyl)cyclohexane (Cosmonate 600, manufactured by Mitsui Chemicals) 52.2 parts by weight Methylenebis(cyclohexyl isocyanate) (VestanatH 12 MDI, H 12 MDI, manufactured by Evonik) 14.1 parts by weight Ethylene glycol 39.1 parts by weight Trimethylolpropane 3.7 parts by mass Dimethylolpropionic acid 17.9 parts by mass Methyl ethyl ketone (solvent) 106.5 parts by weight

[0118] Next, 66.9 parts by mass of ammonia water (28% by mass) was added to the reaction solution to neutralize the isocyanate-terminated prepolymer and to cap the isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer, thereby obtaining a polyurethane resin.

[0119] The reaction solution was then dispersed in 1019.6 parts by mass of ion-exchanged water to obtain an aqueous dispersion. The aqueous dispersion was then subjected to Fourier transform infrared (FT-IR) spectroscopy. This confirmed that the isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer were blocked.

[0120] The aqueous dispersion was then heated to 40°C under reduced pressure over 1 hour to remove the solvent, and the solid content was adjusted to 25% by mass. This resulted in a polyurethane dispersion (PUD) containing a polyurethane resin. The solid content, particle size, viscosity, and pH of the polyurethane dispersion are shown in Table 1.

[0121] Further, 100 parts by mass of the polyurethane dispersion, 16.67 parts by mass of a solvent (isopropanol), and 50 parts by mass of ion-exchanged water were mixed together to obtain a gas barrier coating material.

[0122] In addition, a polyethylene terephthalate film was prepared as a substrate. The polyethylene terephthalate film was a biaxially oriented polyester film (product name: Toyobo Ester Film E5102, manufactured by Toyobo Co., Ltd., thickness 12 μm). Next, a gas barrier coating material was applied to the substrate using a bar coater. The amount of coating was 2 g / m2 when dried. 2 Next, the film coated with the gas barrier coating material was dried for 90 seconds in a drying oven set at 90° C. As a result, a laminate including a substrate and a polyurethane layer was obtained.

[0123] Examples 2 to 3 and Comparative Examples 1 to 5 According to the formulations shown in Tables 1 and 2, polyurethane dispersions, gas barrier coating materials and laminates were obtained in the same manner as in Example 1.

[0124] <Evaluation> (1) PUD appearance The appearance of the polyurethane dispersion was visually confirmed.

[0125] (2) Number average molecular weight of polyurethane resin 0.1g of polyurethane dispersion was dissolved in 10mL of dimethylacetamide (DMAc) eluent, and the solution was left to stand overnight. This solution was filtered through a 0.45μm membrane filter. The filtrate was subjected to GPC measurement (polystyrene equivalent) under the following conditions to determine the number average molecular weight (Mn).

[0126] Analyzer: TOSOH HLC-8320GPC+UV-8320 Analysis device: TOSOH GPC Work station EcoSEC-WS Column: TOSOH TSK-GEL TSK gel α-M Column No. G0032+G0033 Eluent: 0.01mol-LiBr / 1000ml-DMAc(N,N-Dimethylacetamide) Detector: RI 40℃ Column temperature: 40℃ Flow rate: 0.6mL / min Injection volume: 100μL

[0127] (3) Manufacturing of laminated films A mixture of Takelac A-969V (manufactured by Mitsui Chemicals) and Takenate A-5 (manufactured by Mitsui Chemicals) (Takelac A-969V / Takenate A-5 = 3 / 1 (mass ratio)) was applied to the polyurethane layer of the laminate to a dry thickness of 3.0 g / m 2 The adhesive was applied with a bar coater so that the adhesive was applied to the surface of the film, and then dried with a dryer. Next, an unstretched polypropylene film (Tocello CP RXC-22 (CPP film), #60, manufactured by Mitsui Chemicals Tocello Co., Ltd.) was laminated onto the adhesive-applied surface, and the film was aged at 40°C for 48 hours to obtain a laminate film.

[0128] (4) Gas barrier properties (OTR) Using an oxygen permeability measuring device (OX-TRAN2 / 22, manufactured by MOCON), the oxygen permeability of each laminate film was measured at 20°C and 80% relative humidity (80% RH) for 1 m 2 , oxygen transmission rate per day and atmosphere (OTR: cc / m 2 In addition, each laminate film was stored at 40°C for one month, and then the oxygen transmission rate (OTR over time) was measured in the same manner.

[0129] (5) Water Vapor Barrier Resilience (WVTR) Using a moisture permeability cup (manufactured by Tester Sangyo Co., Ltd.), the moisture permeability test method for moisture-proof packaging materials (cup method, compliant with JIS Z 0208) was used to measure the moisture permeability of each laminate film at 40°C and a relative humidity of 90% (90% RH) for 1m 2 and the daily water vapor transmission rate (WVTR: g / m 2 ·day·atm) was measured.

[0130] [Table 1]

[0131] [Table 2]

[0132] Examples 4 to 13 A layered inorganic compound and / or a curing agent was added to the polyurethane dispersion according to the formulations shown in Tables 3 and 4. The amounts of the solvent (isopropanol) and ion-exchanged water added were also changed. Furthermore, the substrate was changed. The rest of the process was the same as in Example 1 to obtain a polyurethane dispersion, a gas barrier coating material, and a laminate. These were also evaluated in the same manner as in Example 1.

[0133] [Table 3]

[0134] [Table 4]

[0135] Details of the abbreviations in the table are given below. PUD: Polyurethane dispersion ME300-B4T: Product name ME300-B4T, layered inorganic compound, solid content concentration 7.8% by mass, manufactured by Katakura Co-op Agri Co., Ltd. WD-725: Product name Takenate WD-726, hardener, isocyanate hardener, solid content 80% by mass, manufactured by Mitsui Chemicals SV-02: Trade name Carbodilite SV-02, hardener, carbodiimide hardener, solid content concentration 40% by mass, manufactured by Nisshinbo Chemical Co., Ltd. KBM-403: Product name KBM-403, hardener, epoxy hardener, manufactured by Shin-Etsu Chemical CPP: Unstretched polypropylene film LDPE: Low density polyethylene film VM-CPP: Aluminum-coated unstretched polypropylene film AlOxPET: Aluminum oxide deposited polyethylene terephthalate film Paper: Glassine paper [Explanation of symbols]

[0136] 1. Laminate 2 Base material 3 Polyurethane layer

Claims

1. A polyurethane dispersion which is a water dispersion of a polyurethane resin, The polyurethane resin is a reaction product of an isocyanate-terminated prepolymer and ammonia, The isocyanate group-terminated prepolymer is a polyisocyanate component containing an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate; The composition comprises a reaction product of a short-chain diol having 2 to 6 carbon atoms and an active hydrogen group-containing component including an active hydrogen group-containing compound having an anionic group, the ammonia caps the isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer and neutralizes the anionic groups; The amount of the aromatic ring-containing isocyanate is 50 mass% or more based on the total amount of the aromatic ring-containing isocyanate and the alicyclic ring-containing isocyanate; The number average molecular weight of the polyurethane resin is 600 or more and 1300 or less. Polyurethane dispersion.

2. A polyurethane dispersion which is an aqueous dispersion of a polyurethane resin, comprising: The polyurethane resin is a reaction product of an isocyanate-terminated prepolymer and ammonia, The isocyanate group-terminated prepolymer is a polyisocyanate component containing an aromatic ring-containing isocyanate and an alicyclic ring-containing isocyanate; The reaction product includes a short-chain diol having 2 to 6 carbon atoms and an active hydrogen group-containing component including an active hydrogen group-containing compound containing an anionic group. the ammonia caps the isocyanate groups at the molecular ends of the isocyanate-terminated prepolymer and neutralizes the anionic groups; the alicyclic-containing isocyanate contains bis(isocyanatomethyl)cyclohexane, A polyurethane dispersion, wherein the aromatic ring-containing isocyanate accounts for 50 mass% or more based on the total amount of the aromatic ring-containing isocyanate and the alicyclic ring-containing isocyanate.

3. 3. The polyurethane dispersion according to claim 1, wherein the polyurethane resin has a number average molecular weight of 800 or more and 1,300 or less.

4. The polyurethane dispersion according to any one of claims 1 to 3, further comprising a layered inorganic compound.

5. A gas barrier coating material comprising the polyurethane dispersion according to any one of claims 1 to 4.

6. A substrate and a polyurethane layer disposed on a surface of the substrate, A laminate, wherein the polyurethane layer is a dried product of the gas barrier coating material according to claim 5 .

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