Polyurethane dispersions

Abstract

In a polyurethane dispersion in which a polyurethane resin is dispersed with water, the polyurethane resin is a reaction product of a polyisocyanate component and at least a reactive hydrogen group-containing component containing a reactive hydrogen compound containing an anionic group, the total mole ratio of urethane groups and urea groups is 1.5 moles or more per 1 kg of the polyurethane dispersion, and the carbonate ion concentration is 700 ppm or less per the polyurethane dispersion.

Description

Technical Field

[0001] This invention relates to polyurethane dispersions, and more specifically, to polyurethane dispersions for obtaining polyurethane layers. Background Technology

[0002] Conventionally, a gas barrier composite membrane with excellent gas barrier properties is known, for example, which comprises a substrate membrane layer and a polyurethane layer obtained by coating a gas barrier polyurethane dispersion onto the substrate membrane layer and drying it.

[0003] As a gas-barrier polyurethane dispersion, for example, an aqueous dispersion of a gas-barrier polyurethane resin with a solid component concentration of 25% by mass has been proposed. This dispersion is obtained by reacting hydrogenated dimethyl phthalate diisocyanate, dimethylolpropionic acid, and ethylene glycol, then neutralizing the resulting polyurethane prepolymer solution containing carboxylic acid groups with a neutralizing agent such as triethylamine, dispersing it in water, and then carrying out a chain extension reaction using 2-[(2-aminoethyl)amino]ethanol (for example, see Patent Document 1 (Manufacturing Example 9)).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-98047 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In the above-mentioned aqueous dispersion of polyurethane resin (polyurethane dispersion), from the viewpoint of reducing coating production efficiency and transportation costs, it is required that the concentration of solid components of polyurethane resin be relatively high (e.g., greater than 20% by mass).

[0009] However, when the concentration of solid components in the polyurethane resin is high (e.g., greater than 20% by mass), the concentrations of urethane groups and urea groups in the polyurethane dispersion also become high.

[0010] On the other hand, in the manufacture of polyurethane dispersions, during the chain extension reaction, carbon dioxide is generated by the reaction of water with isocyanate-terminated polyurethane prepolymers containing carboxylic acid groups in water, and carbonate ions are contained in the polyurethane dispersion.

[0011] Furthermore, sometimes carbonate ions in polyurethane dispersions can cause the neutralizing agent that has neutralized the carboxylic acid groups (anionic groups) to detach, generating free carboxylic acid groups (anionic groups).

[0012] If free carboxylic acid groups (anionic groups) are generated, the aqueous dispersion stability of the polyurethane dispersion will decrease. This is especially true for polyurethane dispersions with high concentrations of urethane and urea groups, where the polyurethane resin exhibits high agglomeration power. Therefore, if the aqueous dispersion stability decreases, the polyurethane resin is more prone to agglomeration.

[0013] As a result, the stability of water-dispersed particles is reduced, and the storage stability (thermal stability) of polyurethane dispersions during storage and transportation, as well as the mechanical stability (resistance to curing) during mechanical application, is sometimes insufficient.

[0014] The present invention provides a polyurethane dispersion that can suppress the aggregation of polyurethane resin and exhibit excellent storage stability and mechanical stability even when the concentrations of urethane and urea groups are relatively high.

[0015] Methods for solving problems

[0016] The present invention [1] includes a polyurethane dispersion, which is a polyurethane dispersion formed by dispersing polyurethane resin in water. The polyurethane resin is a reaction product formed by reacting a polyisocyanate component with an active hydrogen group component containing an active hydrogen compound containing an anionic group. The total molar ratio of urethane groups and urea groups is more than 1.5 moles per kilogram of the polyurethane dispersion, and the carbonate ion concentration is less than 700 ppm per kilogram of the polyurethane dispersion.

[0017] The present invention [2] includes the polyurethane dispersion described in [1] above, wherein the aforementioned polyurethane resin is a gas barrier polyurethane resin.

[0018] The present invention [3] includes the polyurethane dispersion described in [1] above, wherein the aforementioned polyisocyanate component contains a polyisocyanate containing an aromatic ring.

[0019] The present invention [4] comprises the polyurethane dispersion described in any one of [1] to [3] above, wherein the aforementioned polyisocyanate component contains aromatic aliphatic polyisocyanate and alicyclic polyisocyanate.

[0020] The present invention [5] comprises any one of the polyurethane dispersions described in [1] to [4] above, wherein the aforementioned polyurethane resin is the reaction product of the following isocyanate-terminated prepolymer and chain extender, wherein the isocyanate-terminated prepolymer is formed by reacting a polyisocyanate component containing phenylene diisocyanate with a short-chain diol containing 2 to 6 carbon atoms and an active hydrogen-containing component containing anionic groups.

[0021] The present invention [6] includes the polyurethane dispersion described in any one of [1] to [5] above, wherein the rate of change (D2 / D1) of the average particle size D2 of the polyurethane dispersion after storage at 40°C for 7 days relative to the average particle size D1 of the polyurethane dispersion before storage is 2.5 or less.

[0022] The effects of the invention

[0023] The polyurethane dispersion of the present invention uses an active hydrogen compound containing anionic groups as a raw material component of polyurethane resin, and the total molar ratio of urethane groups and urea groups is 1.5 moles or more relative to 1 kg of polyurethane dispersion, and the carbonate ion concentration is 700 ppm or less relative to the polyurethane dispersion.

[0024] That is, in the polyurethane dispersion described above, the concentrations of urethane groups and urea groups are relatively high. Under such circumstances, if the neutralizing agent targeting the anionic groups detaches and generates free anionic groups, the stability of the particles is easily reduced, and the polyurethane resin is prone to agglomeration.

[0025] However, in the polyurethane dispersion described above, the concentration of carbonate ions is sufficiently low, thus suppressing the detachment of the neutralizing agent caused by carbonate ions. As a result, the generation of free anionic groups and the aggregation of polyurethane resin can be suppressed.

[0026] Therefore, the above-mentioned polyurethane dispersion exhibits excellent storage stability and mechanical stability. Attached Figure Description

[0027] [ Figure 1 ] Figure 1 This is a schematic structural diagram illustrating one embodiment of a polyurethane laminate obtained using the polyurethane dispersion of the present invention.

[0028] [ Figure 2 ] Figure 2 A schematic structural diagram illustrating other embodiments of polyurethane laminates obtained using the polyurethane dispersion of the present invention. Detailed Implementation

[0029] The polyurethane dispersion of the present invention can be obtained by dispersing a polyurethane resin (aqueous polyurethane resin) in water.

[0030] As will be explained in detail below, the polyurethane resin in this invention is a polyurethane resin containing a high proportion of urethane groups and urea groups. Examples of such polyurethane resins include gas barrier polyurethane resins and chemical-resistant polyurethane resins, with gas barrier polyurethane resins being a preferred example.

[0031] It should be noted that, in this invention, gas barrier properties refer to the property of reducing oxygen permeability. More specifically, it can be defined as follows: the oxygen permeability of a laminate containing a polyurethane resin layer, measured according to the examples described later, after 7 days at 40°C, is 90 cc / (m³). 2 When the temperature is below ·day·atm, polyurethane resin has gas barrier properties.

[0032] Such polyurethane resins can be obtained, for example, by reacting isocyanate-terminated prepolymers with chain extenders. That is, the polyurethane resin is a secondary reaction product of isocyanate-terminated prepolymers and chain extenders.

[0033] Isocyanate-terminated prepolymers can be obtained by reacting a polyisocyanate component with a component containing active hydrogen groups. That is, the isocyanate-terminated prepolymer is a product of a primary reaction between a polyisocyanate component and a component containing active hydrogen groups.

[0034] Examples of polyisocyanate components include polyisocyanates containing aromatic rings and polyisocyanates without aromatic rings.

[0035] Examples of polyisocyanates containing aromatic rings include aromatic aliphatic polyisocyanates and aromatic polyisocyanates.

[0036] Examples of aromatic aliphatic polyisocyanates include, for example, phenylene diisocyanate (1,2-, 1,3- or 1,4-phenylene diisocyanate) (XDI), tetramethylphenylene diisocyanate (1,3- or 1,4-tetramethylphenylene diisocyanate or mixtures thereof) (TMXDI), ω,ω'-diisocyanate-1,4-diethylbenzene, and other aromatic aliphatic diisocyanate monomers (aromatic aliphatic diisocyanates, etc.), with phenylene diisocyanate (XDI) being a preferred example. These aromatic aliphatic diisocyanate monomers can be used alone or in combination of two or more.

[0037] In addition, as aromatic aliphatic polyisocyanates, derivatives of aromatic aliphatic diisocyanate monomers can be cited.

[0038] Examples of derivatives of aromatic aliphatic diisocyanate monomers include, for instance, polymers of aromatic aliphatic diisocyanate monomers (e.g., dimers, trimers, pentamers, heptomers, etc. (e.g., isocyanurate modified products, iminooxadiazine dione modified products)), urea carbamate modified products (e.g., urea carbamate modified products generated by reacting aromatic aliphatic diisocyanate monomers with known monohydric alcohols and / or known dihydric alcohols), and polyol modified products (e.g., polyol modified products generated by reacting aromatic aliphatic diisocyanate monomers with known 3 or more alcohols). These derivatives include alcohol adducts, biuret-modified derivatives (e.g., biuret-modified derivatives generated by the reaction of aromatic aliphatic diisocyanate monomers with water and amines), urea-modified derivatives (e.g., urea-modified derivatives generated by the reaction of aromatic aliphatic diisocyanate monomers with diamines), oxadiazine trione-modified derivatives (e.g., oxadiazine trione-modified derivatives generated by the reaction of aromatic aliphatic diisocyanate monomers with carbon dioxide), carbodiimide-modified derivatives (carbodiimide-modified derivatives generated by the decarboxylation condensation reaction of aromatic aliphatic diisocyanate monomers), urea dione-modified derivatives, and urea ketone-imide-modified derivatives. These derivatives can be used alone or in combination of two or more.

[0039] Examples of aromatic polyisocyanates include toluene diisocyanate (2,4- or 2,6-toluene diisocyanate or mixtures thereof) (TDI), phenyl diisocyanate (m- or p-phenyl diisocyanate or mixtures thereof), 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate (NDI), diphenylmethane diisocyanate (4,4'-, 2,4'- or 2,2'-diphenylmethane diisocyanate or mixtures thereof) (MDI), 4,4'-toluidine diisocyanate (TODI), 4,4'-diphenyl ether diisocyanate, and other aromatic diisocyanate monomers (aromatic diisocyanates, etc.), with toluene diisocyanate (TDI) being a preferred example. These aromatic diisocyanate monomers can be used alone or in combination of two or more.

[0040] Furthermore, as aromatic polyisocyanates, derivatives of aromatic diisocyanate monomers can be cited. As derivatives, the aforementioned derivatives (derivatives exemplified as derivatives of aromatic aliphatic diisocyanate monomers) can be cited. These derivatives can be used alone or in combination of two or more.

[0041] These polyisocyanates containing aromatic rings can be used alone or in combination of two or more.

[0042] Examples of polyisocyanates that do not contain aromatic rings include aliphatic polyisocyanates and alicyclic polyisocyanates.

[0043] Examples of aliphatic polyisocyanates include, for instance, trimethylene diisocyanate, 1,2-propanediisocyanate, succinate (1,4-succinate, 1,2-succinate, 2,3-succinate, 1,3-succinate), 1,5-pentamethylene diisocyanate (PDI), 1,6-hexamethylene diisocyanate (HDI), 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate-methylhexanoate, etc., and other aliphatic diisocyanate monomers (chain-like aliphatic diisocyanates, etc.). 1,5-pentamethylene diisocyanate (PDI) and 1,6-hexamethylene diisocyanate are preferred examples. These aliphatic diisocyanate monomers can be used alone or in combination of two or more.

[0044] Furthermore, derivatives of aliphatic diisocyanate monomers can be cited as examples of aliphatic polyisocyanates. Among these derivatives are the aforementioned derivatives (derivatives exemplified as derivatives of aromatic aliphatic diisocyanate monomers). These derivatives can be used alone or in combination of two or more.

[0045] Examples of alicyclic polyisocyanates include, for example, 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (also known as isophorone diisocyanate) (IPDI), bis(isocyanatomethyl)cyclohexane (also known as hydrogenated diphenylmethane diisocyanate (1,2-, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane)) (H6XDI), methylene bis(cyclohexyl)isocyanate (also known as hydrogenated diphenylmethane diisocyanate (4,4'-, 2,4'- or 2,2'-methylene bis(cyclohexyl)isocyanate, their trans, trans, trans, cis, cis, or mixtures thereof) (H 12 MDI), methylcyclohexane diisocyanate (methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), norbornene diisocyanate (various isomers or mixtures thereof) (NBDI) and other alicyclic diisocyanate monomers (alicyclic diisocyanates, etc.), preferably bis(isocyanatomethyl)cyclohexane (H6XDI) and methylene bis(cyclohexyl)isocyanate (H 12 MDI), more preferably methylene bis(cyclohexyl isocyanate) (H 12 MDI). These alicyclic diisocyanate monomers can be used alone or in combination of two or more.

[0046] Furthermore, derivatives of alicyclic diisocyanate monomers can be cited as examples of alicyclic polyisocyanates. The derivatives described above (derivatives exemplified as derivatives of aromatic alicyclic diisocyanate monomers) can be used alone or in combination of two or more.

[0047] These polyisocyanates, which do not contain aromatic rings, can be used alone or in combination of two or more.

[0048] There are no particular limitations on the use of polyisocyanates. For example, the polyisocyanates containing aromatic rings described above can be used alone, as can the polyisocyanates without aromatic rings described above. In addition, they can be used in combination.

[0049] From the viewpoint of improving gas barrier properties, the polyisocyanate component preferably contains a polyisocyanate containing an aromatic ring, more preferably contains an aromatic aliphatic polyisocyanate, even more preferably contains an aromatic aliphatic diisocyanate monomer, and especially preferably contains phenylene diisocyanate (XDI).

[0050] When the polyisocyanate component contains a polyisocyanate containing an aromatic ring (preferably an aromatic aliphatic polyisocyanate, more preferably phenylene diisocyanate (XDI)), its content ratio relative to 100 parts by mass of the total polyisocyanate component is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, more preferably 70 parts by mass or more, for example, 100 parts by mass or less, preferably 95 parts by mass or less, more preferably 90 parts by mass or less.

[0051] Furthermore, from the viewpoint of improving water dispersion stability, the polyisocyanate component preferably contains polyisocyanates with aromatic rings and polyisocyanates without aromatic rings, more preferably contains aromatic aliphatic polyisocyanates and alicyclic polyisocyanates, even more preferably contains aromatic aliphatic diisocyanate monomers and alicyclic diisocyanate monomers, and particularly preferably contains phenylene diisocyanate (XDI) and methylene bis(cyclohexyl) isocyanate (H). 12 MDI).

[0052] Furthermore, when the polyisocyanate component contains aromatic aliphatic polyisocyanates and alicyclic polyisocyanates, the proportion of aromatic aliphatic polyisocyanates relative to their total amount of 100 parts by mass is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, more preferably 70 parts by mass or more, for example, 99 parts by mass or less, preferably 95 parts by mass or less, more preferably 90 parts by mass or less. The proportion of alicyclic polyisocyanates is, for example, 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, for example, 70 parts by mass or less, preferably 50 parts by mass or less, more preferably 30 parts by mass or less.

[0053] Polyols are an example of components containing active hydrogen groups. Polyols contain compounds with active hydrogen groups, including anionic groups, as essential components.

[0054] Compounds containing anionic groups and active hydrogen groups are, for example, organic compounds that have both anionic groups such as carboxylic acids and active hydrogen groups such as two or more hydroxyl or amino groups.

[0055] More specifically, examples of compounds containing anionic groups and active hydrogen groups include organic compounds that have both carboxylic acids and two hydroxyl groups (compounds containing carboxyl groups and active hydrogen groups, such as carboxyl-containing polyols, etc.).

[0056] Examples of carboxyl-containing polyols include 2,2-dihydroxymethylacetic acid, 2,2-dihydroxymethyllactic acid, 2,2-dihydroxymethylpropionic acid (also known as dihydroxymethylpropionic acid), 2,2-dihydroxymethylbutanoic acid, 2,2-dihydroxymethylbutanoic acid, 2,2-dihydroxymethylvaleric acid, and other polyhydroxyalkane acids, with 2,2-dihydroxymethylpropionic acid being a preferred example.

[0057] These compounds containing anionic groups and active hydrogen groups can be used alone or in combination.

[0058] As compounds containing anionic groups and active hydrogen groups, polyols containing carboxyl groups are preferred, polyhydroxyalkanoic acids are more preferred, and dimethylolpropionic acid is even more preferred.

[0059] The proportion of compounds containing anionic groups and active hydrogen groups relative to 100 parts by mass of the total polyol content is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 30 parts by mass or more, for example, 70 parts by mass or less, preferably 55 parts by mass or less, more preferably 40 parts by mass or less.

[0060] In addition, short-chain diols containing 2 to 6 carbon atoms are preferred as optional components of the polyol component.

[0061] Short-chain diols with 2 to 6 carbon atoms are organic compounds with a molecular weight (number average molecular weight converted to polystyrene based on GPC, where a molecular weight distribution is available) of 50 to 650 and having two hydroxyl groups. Examples include alkyl diols (alkylene diols with 2 to 6 carbon atoms) such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, 3-methyl-1,5-pentanediol, and 1,3- or 1,4-cyclohexanediol; ether diols with 2 to 6 carbon atoms such as diethylene glycol, triethylene glycol, and dipropylene glycol; and olefin diols with 2 to 6 carbon atoms such as 1,4-dihydroxy-2-butene.

[0062] These short-chain diols with 2 to 6 carbon atoms can be used alone or in combination of two or more.

[0063] From the viewpoint of gas barrier properties, alkane diols with 2 to 6 carbon atoms are preferred as short-chain diols, and ethylene glycol is more preferred.

[0064] The proportion of short-chain diols with 2 to 6 carbon atoms relative to the total amount of polyol components (100 parts by mass) is, for example, 10 parts by mass or more, preferably 30 parts by mass or more, more preferably 50 parts by mass or more, for example, 90 parts by mass or less, preferably 80 parts by mass or less, more preferably 70 parts by mass or less.

[0065] The polyol component may also contain other low molecular weight polyols (excluding diols with 2 to 6 carbon atoms, and low molecular weight polyols containing hydrophilic groups or active hydrogen groups) and high molecular weight polyols as optional components.

[0066] It should be noted that, from the perspective of gas barrier properties, polyol components are preferably free of high molecular weight polyols.

[0067] High molecular weight polyols are compounds with a molecular weight (number average molecular weight) greater than 650 and having two or more hydroxyl groups. Examples include polyether polyols (e.g., polyoxyalkylene polyols with 2-3 carbon atoms, polytetramethylene ether polyols, etc.), polyester polyols (e.g., adipic acid-based polyester polyols, phthalic acid-based polyester polyols, lactone-based polyester polyols, etc.), polycarbonate polyols, polyurethane polyols (e.g., polyols obtained by modifying polyether polyols, polyester polyols, polycarbonate polyols, etc. with urethane using polyisocyanates), epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, vinyl monomer-modified polyols, and other high molecular weight macromolecular polyols with a molecular weight greater than 650.

[0068] Such high molecular weight polyols can sometimes reduce gas barrier properties.

[0069] Therefore, the polyol component is preferably free of high molecular weight polyols. This improves the gas barrier properties of the polyurethane resin (described later).

[0070] On the other hand, the polyol component may contain low molecular weight polyols with a molecular weight of 50 or more and 650 or less (excluding the short-chain diols with 2 to 6 carbon atoms mentioned above). (Hereinafter referred to as other low molecular weight polyols.) as optional components.

[0071] Other examples of low molecular weight polyols include diols with 7 or more carbon atoms and low molecular weight polyols with 3 or more carbon atoms.

[0072] Examples of diols with 7 or more carbon atoms include alkane-1,2-diol, 2,6-dimethyl-1-octen-3,8-diol, 1,3- or 1,4-cyclohexanediol and mixtures thereof, hydrogenated bisphenol A, bisphenol A and other diols with 7 or more carbon atoms.

[0073] These diols with 7 or more carbon atoms can be used alone or in combination of two or more.

[0074] Low molecular weight polyols with a molecular weight of 3 or more are organic compounds with a molecular weight of less than 650 and having 3 or more hydroxyl groups in one molecule. Examples include glycerol, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolpropane, 2,2-bis(hydroxymethyl)-3-butanol, etc. (triols with low molecular weight), tetramethylolmethane (pentaerythritol), diglycerol, etc. (tetraols with a molecular weight), xylitol, etc. (pentaerythritols with a molecular weight), sorbitol, mannitol, allitol, idotitol, eurythritol, atroitol, inositol, dipentaerythritol, etc. (hexaols with a molecular weight), avocado, etc. (hexaols with a molecular weight), sucrose, etc. (octanools with a molecular weight).

[0075] These low molecular weight polyols with 3 or more elements can be used alone or in combination of two or more.

[0076] Furthermore, as long as the number average molecular weight is below 650, the aforementioned macromolecular polyols (specifically, polyether polyols (e.g., polyoxyalkylene polyols, polytetramethylene ether polyols, etc.), polyester polyols (e.g., adipic acid-based polyester polyols, phthalic acid-based polyester polyols, lactone-based polyester polyols, etc.), polycarbonate polyols, polyurethane polyols (e.g., polyols obtained by modifying polyether polyols, polyester polyols, polycarbonate polyols, etc. with urethane using polyisocyanates), epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, vinyl monomer-modified polyols, etc., and low molecular weight macromolecular polyols with a molecular weight of below 650) can be used as other low molecular weight polyols.

[0077] Other low molecular weight polyols can be used alone or in combination of two or more.

[0078] From the viewpoint of solvent resistance, heat resistance, and water dispersion stability of polyurethane dispersions, low molecular weight polyols with 3 or more elements are preferred, trihydric alcohols and tetrahydric alcohols are more preferred, trihydric alcohols are even more preferred, and trimethylolpropane is particularly preferred.

[0079] When combined with other low molecular weight polyols, the proportion of the 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, for example, 20 parts by mass or less, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, relative to the total amount of 100 parts by mass of the polyol components.

[0080] Furthermore, regarding the proportion of short-chain diols with 2 to 6 carbon atoms used in combination with other low molecular weight polyols (preferably low molecular weight polyols with 3 or more carbon atoms), relative to their total amount of 100 parts by mass, the other low molecular weight polyols are, for example, 2 or more parts by mass, preferably 5 or more parts by mass, for example, 20 or less parts by mass, preferably 15 or less parts by mass, and more preferably 10 or less parts by mass.

[0081] In addition, relative to the total amount of short-chain diols with 2 to 6 carbon atoms and other low molecular weight polyols (preferably low molecular weight polyols with 3 or more carbon atoms) of 100 parts by mass, the compound containing anionic groups and active hydrogen groups is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 40 parts by mass or more, for example, 90 parts by mass or less, preferably 80 parts by mass or less, more preferably 70 parts by mass or less.

[0082] If the proportions of other low molecular weight polyols are within the above range, excellent dispersibility can be ensured. Therefore, a polyurethane layer with excellent gas barrier properties and adhesion can be formed.

[0083] The polyol component is preferably formed from short-chain diols with 2 to 6 carbon atoms, low molecular weight polyols with 3 or more carbon atoms, and compounds containing active hydrogen groups containing anionic groups, or from short-chain diols with 2 to 6 carbon atoms and compounds containing active hydrogen groups containing anionic groups.

[0084] Furthermore, in order to synthesize the isocyanate-terminated prepolymer, the above-mentioned components are combined in a ratio of isocyanate group to active hydrogen group (hydroxyl group) equivalent ratio (isocyanate group / active hydrogen group) greater than 1, preferably 1.1 to 10. Moreover, the above-mentioned components are reacted by known polymerization methods such as bulk polymerization or solution polymerization, preferably solution polymerization which is easier to adjust reactivity and viscosity.

[0085] In bulk polymerization, for example, under a nitrogen atmosphere, the above components are combined and reacted at a reaction temperature of 75–85°C for about 1–20 hours.

[0086] In solution polymerization, for example, under a nitrogen atmosphere, the above-mentioned components are combined in an organic solvent and the reaction is carried out at a reaction temperature of 20–80°C for about 1–20 hours.

[0087] Examples of organic solvents that are inactive to isocyanate groups and are hydrophilic include acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, and acetonitrile.

[0088] For this polymerization reaction, the isocyanate group content in the reaction solution is defined as the following isocyanate group concentration.

[0089] In addition, reaction catalysts such as amine-based, tin-based, and lead-based catalysts can be added as needed during the above polymerization. Furthermore, unreacted polyisocyanates can be removed from the obtained isocyanate-terminated prepolymer by known methods such as distillation and extraction.

[0090] The resulting isocyanate-terminated prepolymer is a polyurethane prepolymer having two or more free isocyanate groups at the ends of its molecules, and has a high isocyanate group concentration (isocyanate group content calculated based on the solid component after solvent removal). More specifically, the isocyanate group concentration is, for example, 4% by mass or more, preferably 5% by mass or more, more preferably 6% by mass or more, and even more preferably 8% by mass or more. It is also, 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.

[0091] In addition, the average number of functional groups of the isocyanate group 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.

[0092] If the average number of functional groups of isocyanate groups is within the above range, a stable polyurethane dispersion can be obtained, which can ensure substrate adhesion, gas barrier properties, etc.

[0093] In addition, its number-average molecular weight (the molecular weight of polystyrene as determined by GPC) is, for example, 500 or more, preferably 800 or more, and, for example, 100,000 or less, preferably 50,000 or less.

[0094] Next, in this method, a neutralizing agent is added to the isocyanate-terminated prepolymer obtained by the above method to neutralize the anionic groups and form a salt.

[0095] As neutralizing agents, commonly used bases can be cited, such as organic bases and inorganic bases.

[0096] Examples of organic bases include tertiary amines such as trialkylamines (e.g., trimethylamine, triethylamine, etc., trialkylamines with 1 to 4 carbon atoms), alkanolamines (e.g., dimethylethanolamine, methyldiethanolamine, triethanolamine, triisopropanolamine, etc.), and secondary amines such as heterocyclic amines (morpholine, etc.).

[0097] Examples of inorganic bases include ammonia, alkali metal hydroxides (e.g., lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.), alkaline earth metal hydroxides (e.g., magnesium hydroxide, calcium hydroxide, etc.), and alkali metal carbonates (e.g., sodium carbonate, potassium carbonate, etc.).

[0098] These neutralizing agents can be used alone or in combination of two or more.

[0099] As a neutralizing agent, an organic base is preferred, a tertiary amine is more preferred, a trialkylamine is even more preferred, and triethylamine is particularly preferred. That is, the neutralizing agent is preferably formed from an organic base, more preferably from a tertiary amine, more preferably from a trialkylamine, and particularly preferably from triethylamine.

[0100] The amount of neutralizing agent added is based on 1 equivalent of anionic group, for example, 0.4 equivalents or more, preferably 0.6 equivalents or more, for example, 1.2 equivalents or less, preferably 1 equivalent or less.

[0101] Next, in this method, the isocyanate-terminated prepolymer, which has been neutralized with the above-mentioned neutralizing agent, is reacted with a chain extender in, for example, water to obtain a polyurethane dispersion in which polyurethane resin is dispersed in water.

[0102] Chain extenders are organic compounds with multiple active hydrogen groups that enable isocyanate-terminated prepolymers to undergo chain extension reactions. Examples include aromatic polyamines, aromatic aliphatic polyamines, alicyclic polyamines, aliphatic polyamines, polyamines containing polyoxyethylene, and amino alcohols.

[0103] Examples of aromatic polyamines include 4,4'-diphenylmethanediamine and toluenediamine.

[0104] Examples of aromatic aliphatic polyamines include, for example, 1,3- or 1,4-phenylenedimethyldiamine or mixtures thereof.

[0105] Examples of alicyclic polyamines include 3-aminomethyl-3,5,5-trimethylcyclohexylamine (also known as isophorone diamine), 4,4'-dicyclohexylmethane diamine, 2,5(2,6)-bis(aminomethyl)bicyclo[2.2.1]heptane, 1,4-cyclohexane diamine, 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- and 1,4-bis(aminomethyl)cyclohexane, and mixtures thereof.

[0106] Examples of aliphatic polyamines include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexamethylenediamine, hydrazine (including hydrates), diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,2-diaminoethane, 1,2-diaminopropane, and 1,3-diaminopentane.

[0107] Examples of polyoxyethylene-containing polyamines include polyoxyethylene ether diamines and polyoxyalkylene ether diamines. More specifically, examples include PEG#1000 diamine manufactured by Nippon Yushu Corporation, and Jeffamine ED-2003, EDR-148, and XTJ-512 manufactured by Huntsman Corporation.

[0108] 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).

[0109] In addition, alkoxysilyl compounds having primary amino groups, or primary amino groups and secondary amino groups, can also be cited as chain extenders.

[0110] Examples of alkoxysilyl compounds having a primary amino group, or both a primary and secondary amino group, include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane, as well as N-β-(aminoethyl)γ-aminopropyltrimethoxysilane (also known as N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) and N-β-(aminoethyl)γ-aminopropyltriethoxysilane. Alkoxysilanes, such as N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, and N-β(aminoethyl)γ-aminopropylmethyldiethoxysilane, are alkoxysilane compounds containing primary and secondary amino groups.

[0111] These chain extenders can be used alone or in combination of two or more.

[0112] As chain extenders, amino alcohols are preferred, and 2-((2-aminoethyl)amino)ethanol is more preferred.

[0113] Furthermore, in order to react the isocyanate-terminated prepolymer with the chain extender in water, for example, firstly, the isocyanate-terminated prepolymer is added to water, thereby dispersing the isocyanate-terminated prepolymer in water, and then the chain extender is added thereto to extend the chain of the isocyanate-terminated prepolymer.

[0114] To achieve water dispersion of the isocyanate-terminated prepolymer, the isocyanate-terminated prepolymer is added while stirring the water, at a ratio of 100 to 1000 parts by mass of water relative to 100 parts by mass of the isocyanate-terminated prepolymer. Alternatively, water can be added to the isocyanate-terminated prepolymer at the above-mentioned ratio.

[0115] Subsequently, under stirring conditions, the chain extender is added dropwise to water in which the isocyanate-terminated prepolymer has been dispersed, with the equivalent ratio (active hydrogen group / isocyanate group) of the chain extender to the isocyanate group of the isocyanate-terminated prepolymer being, for example, 0.6 to 1.2.

[0116] For chain extenders, the reaction is carried out dropwise while stirring, and is allowed to proceed at, for example, room temperature. The reaction time until completion is, for example, 0.1 hours or more, and also, for example, 10 hours or less.

[0117] Thus, a polyurethane resin is obtained, and a dispersion (polyurethane dispersion) is obtained by dispersing the polyurethane resin with water.

[0118] Regarding the content ratio of urethane groups and urea groups relative to the polyurethane resin (solid component), the total molar amount of urethane groups and urea groups relative to 1 kg of polyurethane resin (solid component) is, for example, 5.0 mol or more, preferably 5.5 mol or more, more preferably 6.0 mol or more, even more preferably 6.5 mol or more, for example, 9.0 mol or less, preferably 8.5 mol or less, more preferably 8.0 mol or less, even more preferably 7.5 mol or less.

[0119] It should be noted that the ratio of urethane groups and urea groups can be calculated from the input ratio of raw material components (the same applies below).

[0120] If the proportions of urethane groups and urea groups relative to the polyurethane resin (solid component) are within the above range, a polyurethane layer with excellent gas barrier properties can be obtained.

[0121] In addition, the acid value of the polyurethane resin (solid component) is, for example, 10 mg KOH / g or more, preferably 20 mg KOH / g or more, for example, 50 mg KOH / g or less, preferably 40 mg KOH / g or less.

[0122] It should be noted that acid value can be determined using conventional methods, or it can be calculated from the content of carboxylic acid in the polyurethane resin. The content of carboxylic acid can be calculated from the raw materials of the polyurethane resin and their input amounts.

[0123] Furthermore, in this method, organic solvents and water are removed (desolventization) as needed.

[0124] As a result, the concentration of the solid component of the polyurethane resin in the polyurethane dispersion can be adjusted. In addition, the ratio of urethane groups and urea groups in the polyurethane dispersion relative to the polyurethane dispersion is adjusted to a specified range.

[0125] From the perspective of reducing coating production efficiency and transportation costs, the solid component concentration of polyurethane resin in the polyurethane dispersion is relatively high, for example, greater than 20% by mass, preferably 21% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, for example, 60% by mass or less, and preferably 50% by mass or less.

[0126] If the concentration of the solid component of polyurethane resin in the polyurethane dispersion is within the above range, the production efficiency and transportation cost of the coating film are excellent.

[0127] In other words, for polyurethane dispersions, coatings are typically formed by evaporating water. Therefore, if the concentration of the solid component exceeds the aforementioned lower limit, the energy cost of water evaporation can be reduced, environmental impact can be decreased, and coating production efficiency can be improved. Furthermore, if the concentration of the solid component exceeds the aforementioned lower limit, compared to a concentration below the lower limit, polyurethane resin (solid component) can be transported more efficiently with less mass and volume, resulting in superior transport costs.

[0128] Furthermore, regarding the content ratio of urethane groups and urea groups relative to the polyurethane dispersion, the total molar amount of urethane groups and urea groups relative to 1 kg of the polyurethane dispersion is 1.5 mol or more, preferably 1.7 mol or more, more preferably 1.8 mol or more, even more preferably 1.9 mol or more, for example 5.0 mol or less, preferably 4.0 mol or less, more preferably 3.0 mol or less, and even more preferably 2.5 mol or less.

[0129] If the proportions of urethane groups and urea groups relative to the polyurethane dispersion are within the above range, a polyurethane layer with excellent gas barrier properties can be obtained.

[0130] On the other hand, in the polyurethane dispersions mentioned above, the concentrations of urethane groups and urea groups are relatively high. Therefore, if the neutralizing agent targeting the anionic groups is removed and free anionic groups are generated, the stability of the particles is easily reduced, and the polyurethane resin is prone to agglomeration.

[0131] In particular, when phenylene diisocyanate is used as a polyisocyanate component, carbon dioxide is easily generated, leading to a higher concentration of carbonate ions. Therefore, polyurethane resin aggregation is more likely to occur.

[0132] Therefore, the storage stability (thermal stability) and mechanical stability (resistance to curing) of polyurethane dispersions with high concentrations of urethane and urea groups are sometimes insufficient during storage and transportation.

[0133] In contrast, for example, to suppress aggregation, studies have been conducted on adjusting the concentration of the solid component of the polyurethane resin to a lower concentration (e.g., below 20% by mass) to reduce the concentration of urethane and urea groups in the polyurethane dispersion. However, lowering the concentration of the solid component reduces the production efficiency and transportation costs of the coating film.

[0134] In addition, for example, studies have been conducted on reducing the carbonate ion concentration by decarboxylation through nitrogen purging, thereby improving storage stability and mechanical stability. However, nitrogen purging alone cannot fully decarboxylate the material, resulting in undesirable storage stability and mechanical stability.

[0135] Therefore, in this method, for example, the concentration of carbonate ions in the polyurethane dispersion is reduced by performing vacuum purging.

[0136] More specifically, in this method, when adjusting the concentration of the solid components of the polyurethane dispersion, the organic solvent and water are removed by vacuum purging (solvent removal), but vacuum purging continues after the solvent removal is completed, thereby removing carbon dioxide and carbonate ions from the polyurethane dispersion (decarboxylation).

[0137] That is, in this method, after the organic solvent and water are removed (solvent removal), the removal of carbon dioxide and carbonate ions (decarboxylation) continues until the carbonate ion concentration of the polyurethane dispersion reaches below a specified value.

[0138] As a condition for vacuum purging, the pressure condition is, for example, 1 kPa or more, preferably 2 kPa or more, for example 50 kPa or less, preferably 40 kPa or less.

[0139] In addition, the vacuum purging time is, for example, 0.5 hours or more, preferably 1.0 hour or more, more preferably 1.5 hours or more, even more preferably 2.0 hours or more, and especially preferably 3.0 hours or more.

[0140] This allows for a significant reduction in the concentration of carbonate ions in the polyurethane dispersion.

[0141] On the other hand, from the perspective of suppressing aggregation, the longer the vacuum purging time and the lower the carbonate ion concentration, the better. However, the lower the carbonate ion concentration, the longer the vacuum purging time will be, resulting in reduced productivity and increased costs.

[0142] Therefore, from the viewpoint of productivity and cost, the vacuum purging time is, for example, 24.0 hours or less, preferably 18.0 hours or less, more preferably 12.0 hours or less, and even more preferably 6.0 hours or less.

[0143] Therefore, it is possible to obtain polyurethane dispersions with sufficiently reduced carbonate ion concentrations with good productivity and cost-effectiveness.

[0144] The residual solvent content (solvent content) of the polyurethane dispersion is, for example, 0.5% by mass or less, preferably 0.3% by mass or less, relative to the total amount of the polyurethane dispersion.

[0145] It should be noted that the residual solvent content of the polyurethane dispersion can be determined by gas chromatography according to the examples described later.

[0146] In addition, relative to the total amount of polyurethane dispersion, the carbonate ion concentration is 700 ppm or less, preferably 600 ppm or less, more preferably 500 ppm or less, even more preferably 400 ppm or less, especially preferably 300 ppm or less, and usually 10 ppm or more.

[0147] It should be noted that the carbonate ion concentration can be determined by quantitative analysis using an electrophoresis system (single-point standard curve method) according to the examples described later.

[0148] In addition, organic solvents and water may be added as needed to adjust the content ratio of urethane groups and urea groups relative to the polyurethane dispersion and the carbonate ion concentration to the above range.

[0149] Moreover, as mentioned above, the carbonate ion concentration is sufficiently reduced, thereby suppressing the detachment of the neutralizing agent caused by carbonate ions, suppressing the generation of free anionic groups and the aggregation of polyurethane resin, thus achieving improved storage stability and mechanical stability.

[0150] In addition, various additives can be incorporated into polyurethane dispersions as needed. Examples of additives include silane coupling agents, alkoxysilane compounds, stabilizers (antioxidants, heat stabilizers, UV absorbers, etc.), plasticizers, antistatic agents, lubricants, anti-blocking agents, surfactants, dispersing stabilizers, colorants (pigments, dyes, etc.), fillers, colloidal silica, inorganic particles, inorganic oxide particles, nucleating agents, etc.

[0151] It should be noted that the additives can be pre-mixed in the above-mentioned raw material components, or they can be mixed in the synthesized isocyanate-terminated prepolymer and polyurethane resin. In addition, they can be mixed simultaneously with the above-mentioned components.

[0152] In addition, there are no particular restrictions on the proportion of additives; they can be set appropriately according to the purpose and use.

[0153] Additionally, depending on the requirements, it can be combined with thermoplastic resins that have gas barrier properties.

[0154] Examples of thermoplastic resins with gas barrier properties include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride or polyvinylidene chloride copolymer, starch, cellulose and other polysaccharides.

[0155] It should be noted that there are no particular restrictions on the mixing ratio of thermoplastic resins, which can be appropriately set according to the purpose and application.

[0156] Furthermore, such a polyurethane dispersion uses an active hydrogen compound containing anionic groups as a raw material component of the polyurethane resin, and the total molar ratio of urethane groups and urea groups is more than 1.5 moles per kilogram of polyurethane dispersion, and the carbonate ion concentration is less than 700 ppm per kilogram of polyurethane dispersion.

[0157] That is, in the polyurethane dispersion described above, the concentrations of urethane groups and urea groups are relatively high. Under such circumstances, if the neutralizing agent targeting the anionic groups detaches and generates free anionic groups, the stability of the particles is easily reduced, and the polyurethane resin is prone to agglomeration.

[0158] However, in the polyurethane dispersion described above, the concentration of carbonate ions is sufficiently low, thus suppressing the detachment of the neutralizing agent caused by carbonate ions. As a result, the generation of free anionic groups and the aggregation of polyurethane resin can be suppressed.

[0159] Therefore, the above-mentioned polyurethane dispersion exhibits excellent storage stability.

[0160] For example, the average particle size D1 of the polyurethane dispersion before storage (e.g., immediately after manufacturing) is, for example, 10 nm or more, preferably 20 nm or more, more preferably 30 nm or more, and even more preferably 40 nm or more. In addition, it is, for example, 200 nm or less, preferably 100 nm or less, and more preferably 60 nm or less.

[0161] On the other hand, the average particle size D2 of the polyurethane dispersion after being stored at 40°C for 7 days is, for example, 10 nm or more, preferably 30 nm or more, more preferably 40 nm or more, and also, for example, 300 nm or less, preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less.

[0162] Furthermore, the rate of change (D2 / D1) of the average particle size D2 of the polyurethane dispersion after storage at 40°C for 7 days, which is an indicator of storage stability, relative to the average particle size D1 of the polyurethane dispersion before storage, is 2.5 or less, preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.2 or less, and typically 0.9 or more.

[0163] It should be noted that the average particle size of the polyurethane dispersion was determined according to the examples described later.

[0164] Additionally, for example, the viscosity V1 of the polyurethane dispersion at 25°C before storage (e.g., immediately after manufacturing) is, for example, 5 mPa·s or more, preferably 8 mPa·s or more, more preferably 10 mPa·s or more, and for example, 50 mPa·s or less, preferably 30 mPa·s or less, more preferably 20 mPa·s or less.

[0165] On the other hand, the viscosity V2 of the polyurethane dispersion at 25°C after being stored at 40°C for 7 days is, for example, 5 mPa·s or more, preferably 8 mPa·s or more, more preferably 10 mPa·s or more, and, for example, 50 mPa·s or less, preferably 30 mPa·s or less, more preferably 20 mPa·s or less.

[0166] Furthermore, the rate of change (V2 / V1) of the viscosity V2 of the polyurethane dispersion after storage at 40°C for 7 days, which is an indicator of storage stability, relative to the viscosity V1 of the polyurethane dispersion before storage, is 2.5 or less, preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.2 or less, and typically 0.9 or more.

[0167] It should be noted that the viscosity of the polyurethane dispersion at 25°C was measured according to the examples described later.

[0168] Furthermore, the aforementioned polyurethane dispersion exhibits excellent mechanical stability.

[0169] For example, the agglomeration rate of the polyurethane resin, as determined using a Maron-type testing machine according to the examples described below, is, for example, 6.0% or less, preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, particularly preferably 2.0% or less, and typically 0.0% or more.

[0170] As described above, the polyurethane dispersion exhibits excellent storage stability and mechanical stability.

[0171] Therefore, the above-mentioned polyurethane dispersion is preferably used in the manufacture of polyurethane laminates having a polyurethane layer as a gas barrier layer.

[0172] Figure 1 In the process, the polyurethane laminate 1 includes a substrate 2 and a polyurethane layer 3 laminated on the substrate 2.

[0173] The substrate 2 is not particularly limited and may be formed of, for example, plastic (e.g., thermoplastic resin, thermosetting resin, etc.), paper, cloth, wood, metal, ceramic, etc., preferably plastic, and more preferably thermoplastic resin.

[0174] Examples of thermoplastic resins include, for example, polyolefin resins (e.g., polyethylene, polypropylene, propylene-ethylene copolymer, etc.), polyester resins (e.g., polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamide resins (e.g., nylon 6 (registered trademark), nylon 66 (registered trademark), poly(m-phenylene adipamide), etc.), vinyl resins (e.g., polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polystyrene, polyvinyl acetate, etc.), acrylic resins (e.g., polymethyl methacrylate, polyacrylonitrile, etc.), polycarbonate resins (e.g., bisphenol A polycarbonate, etc.), and cellulose resins (e.g., cellophane, cellulose acetate, etc.). Polyolefin resins, polyester resins, and polyamide resins are preferred. Polypropylene, polyethylene terephthalate, and nylon 6 (registered trademark) are more preferred.

[0175] The substrate 2 is formed of a single layer, or a laminate of the same type or more.

[0176] It should be noted that the shape of the substrate 2 is not particularly limited, and examples include film, sheet, bottle, and cup shapes. Film is preferred.

[0177] The substrate 2 can be any of an unstretched substrate, a uniaxial or biaxial stretched substrate. In addition, the substrate 2 can be subjected to surface treatment (such as corona discharge treatment), anchor coating or primer coating treatment. Furthermore, it can also be subjected to vapor deposition treatment of metal oxides such as aluminum, silicon dioxide, alumina, or a mixture of silicon dioxide and alumina.

[0178] The thickness of the substrate 2 is, for example, 3 μm or more, preferably 5 μm or more, and also, for example, 500 μm or less, preferably 200 μm or less.

[0179] The polyurethane layer 3 is formed from the polyurethane resin described above. From the viewpoint of manufacturing efficiency, it is preferable to form such a polyurethane layer 3 by coating the polyurethane dispersion described above onto the substrate 2 and allowing it to dry.

[0180] More specifically, in order to form polyurethane layer 3, the concentration of the polyurethane dispersion obtained by the above method is adjusted to prepare a coating agent. Then, the obtained coating agent is applied to substrate 2 and allowed to dry.

[0181] When adjusting the concentration of polyurethane dispersion, known methods can be used, such as adding water, known organic solvents, or removing water, known organic solvents, etc.

[0182] The concentration of the solid component of the coating agent is, for example, 0.5% by mass or more, preferably 1% by mass or more, and also, for example, 30% by mass or less, preferably 25% by mass or less.

[0183] In addition, a curing agent can be added to the coating agent as needed.

[0184] Examples of curing agents include epoxy curing agents, melamine curing agents, carbodiimide curing agents, aziridine curing agents, oxazoline curing agents, and isocyanate curing agents. More specifically, regarding isocyanate curing agents, examples include water-dispersible isocyanate curing agents (e.g., capped isocyanates (e.g., toluene diisocyanate-based capped isocyanates, hexamethylene diisocyanate-based capped isocyanates, phenylene diisocyanate-based capped isocyanates, hydrogenated phenylene diisocyanate-based capped isocyanates, etc.) and uncapped polyisocyanates containing hydrophilic groups).

[0185] When a curing agent is used, the proportion of the curing agent, as a solid component, is, for example, 0.1 parts or more, preferably 1 part or more, relative to 100 parts by weight of polyurethane resin, and for example, 50 parts or less, preferably 30 parts or less.

[0186] In addition, there are no particular restrictions on the coating method used as the coating agent, and known coating methods such as gravure coating, reverse coating, roller coating, bar coating, spraying, air knife coating, and immersion coating can be cited.

[0187] In addition, coating can be applied online when making substrate 2.

[0188] Specifically, when the substrate 2 is a film, after the longitudinal uniaxial stretching treatment during film making, a coating agent can be applied using a gravure coating method and dried, and then a biaxial stretching treatment can be performed to set the polyurethane layer 3 on the substrate 2.

[0189] Alternatively, if the substrate 2 is bottle-shaped, a coating agent can be applied to the preform before blow molding using an impregnation method and dried, and then blow molding can be performed to place the polyurethane layer 3 on the substrate 2.

[0190] Furthermore, regarding drying conditions, the drying temperature is, for example, 40°C or higher, preferably 50°C or higher, and for example, 250°C or lower, preferably 200°C or lower. Additionally, the drying time is, for example, 1 second or higher, preferably 3 seconds or higher, and for example, 10 minutes or lower, preferably 5 minutes or lower.

[0191] Therefore, a polyurethane layer 3 formed of polyurethane resin can be formed on the substrate 2, thereby obtaining a polyurethane laminate 1 having the substrate 2 and the polyurethane layer 3.

[0192] The thickness of polyurethane layer 3 is measured by the lamination weight of polyurethane resin (after drying), for example, 0.1 g / m³.2 The above is preferably 0.2 g / m 2 The above, more preferably 0.3 g / m 2 The above, in addition, for example, is 10g / m 2 The following is preferred: 7g / m 2 The following is more preferably 5g / m 2 the following.

[0193] In addition, the thickness of the polyurethane laminate 1 is, for example, 5 μm or more, preferably 10 μm or more, and for example, 1 mm or less, preferably 0.5 mm or less.

[0194] Additionally, depending on the requirements, the obtained polyurethane laminate 1 can be cured at, for example, 30–50°C for about 2–5 days.

[0195] Such a polyurethane laminate 1 has a polyurethane layer 3 obtained using the above-described polyurethane dispersion, and therefore has excellent gas barrier properties.

[0196] In addition, in order to improve the gas barrier properties, fillers can also be dispersed in the polyurethane layer 3 in the polyurethane laminate 1.

[0197] More specifically, for example, the polyurethane dispersion and the mixture of filler described above can be coated onto substrate 2 and dried to form a polyurethane layer 3 with the filler dispersed therein.

[0198] Examples of fillers include organic nanofibers and layered inorganic compounds. From the viewpoint of gas barrier properties, layered inorganic compounds are preferred.

[0199] Examples of organic nanofibers include cellulose nanofibers and chitosan nanofibers.

[0200] Examples of layered inorganic compounds include swollen layered inorganic compounds and non-swollen layered inorganic compounds. From the viewpoint of gas barrier properties, swollen layered inorganic compounds are preferred.

[0201] Swellable layered inorganic compounds are clay minerals formed from extremely thin crystal units and possessing the property of solvent coordination or absorption between crystal unit layers, resulting in swelling.

[0202] As swelling layered inorganic compounds, examples include hydrous silicates (such as shale silicate minerals), kaolinite group clay minerals (such as halloysite, kaolinite, endellite, dickite, and pearlite), serpentine group clay minerals (such as serpentine and fibrous serpentine), montmorillonite group clay minerals (such as montmorillonite, bedeite, chlorodiazepite, soapstone, lithium montmorillonite, zinc montmorillonite, and styraxite), vermiculite group clay minerals (such as vermiculite), mica or mica group clay minerals (such as muscovite, phlogopite, pearlite, tetramethylsilylated mica, and banded mica), and synthetic mica.

[0203] These swellable layered inorganic compounds can be natural clay minerals or synthetic clay minerals. Furthermore, two or more can be used alone or in combination. Preferred examples include montmorillonite group clay minerals (such as montmorillonite), mica group clay minerals (such as water-swellable mica), and synthetic mica; more preferably, synthetic mica.

[0204] The average particle size of the filler is, for example, 50 nm or more, preferably 100 nm or more, and typically 10 μm or less, for example 5 μm or less, preferably 3 μm or less. Furthermore, the aspect ratio of the filler is, for example, 50 or more, preferably 100 or more, more preferably 200 or more, and for example 5000 or less, preferably 3000 or less, more preferably 2000 or less.

[0205] If the aspect ratio of the packing is within the above range, the gas permeation path becomes tortuous between the crystal layers of the packing (such as the gaps between silicate layers), thus the permeation path becomes longer, which can suppress gas permeation and improve gas barrier properties.

[0206] Furthermore, in order to form a polyurethane layer 3 with dispersed fillers, for example, firstly, the above-mentioned polyurethane dispersion is mixed with fillers to prepare a mixed coating agent. Then, the obtained mixed coating agent is applied to the substrate 2 and allowed to dry.

[0207] To prepare the mixture (mixed coating agent), firstly, the filler is dispersed in water, and then a polyurethane dispersion (including polyurethane resin) is added to the dispersion.

[0208] Regarding the mixing ratio of polyurethane resin and filler, relative to the total mass of polyurethane resin and filler (100 parts by mass), the filler is 0.1 parts by mass or more, preferably 1 part by mass or more, for example, 50 parts by mass or less, and preferably 30 parts by mass or less.

[0209] If the ratio of polyurethane resin to filler is within the above range, gas barrier properties can be maintained, and the adhesion to the substrate, transparency, and cost-effectiveness can be improved.

[0210] The total concentration of polyurethane resin and filler in the obtained mixture (mixed coating agent) is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, and also, for example, 15% by mass or less, preferably 12% by mass or less.

[0211] It should be noted that in the mixture (mixed coating agent), the filler may undergo secondary agglomeration. Therefore, it is preferable to disperse the filler by mechanical forced dispersion treatment using shear force after dispersing or mixing it in the solvent, such as dispersion treatment based on homogenizers, rubber mills, jet mills, kneaders, bead mills, sand mills, ball mills, three-roll mills, ultrasonic dispersion devices, etc.

[0212] Furthermore, there are no particular limitations on the coating method for the mixed coating agent, and the known coating methods mentioned above can be cited as examples.

[0213] Regarding drying conditions, the drying temperature is, for example, 40°C or higher, preferably 50°C or higher, for example, 250°C or lower, preferably 200°C or lower. Furthermore, the drying time is, for example, 1 second or higher, preferably 3 seconds or higher, for example, 10 minutes or lower, preferably 5 minutes or lower.

[0214] Thus, a polyurethane layer 3 (composite polyurethane layer) formed of polyurethane resin and filler can be formed on the substrate 2, thereby obtaining a polyurethane laminate 1.

[0215] The thickness of polyurethane layer 3 is measured by the lamination weight of polyurethane resin and filler (after drying), for example, 0.1 g / m³. 2 The above is preferably 0.2 g / m 2 The above, more preferably 0.3 g / m 2 The above, in addition, for example, is 10g / m 2 The following is preferred: 7g / m 2 The following is more preferably 5g / m 2 the following.

[0216] In addition, the thickness of the polyurethane laminate 1 is, for example, 5 μm or more, preferably 10 μm or more, and for example, 1 mm or less, preferably 0.5 mm or less.

[0217] Furthermore, in the polyurethane laminate 1, regarding the mass ratio of the filler, relative to the total mass of 100 parts by mass of the polyurethane layer 3, the mass of the filler is, for example, 0.1 parts by mass or more, preferably 0.2 parts by mass or more, more preferably 1 part by mass or more, for example, 90 parts by mass or less, preferably 70 parts by mass or less, more preferably 50 parts by mass or less.

[0218] If the mass ratio of the filler is within the above range, the adhesion and transparency with the substrate can be improved, and the proportion of filler can be reduced, thus improving cost reduction.

[0219] Additionally, depending on the requirements, the obtained polyurethane laminate 1 can be cured at, for example, 30–60°C for about 2–5 days.

[0220] Such a polyurethane laminate 1 has a polyurethane layer 3 obtained using the above-described polyurethane dispersion, and a filler is dispersed in the polyurethane layer 3, thus exhibiting particularly excellent gas barrier properties.

[0221] Therefore, the polyurethane laminate 1 is preferably used in the field of gas barrier films, specifically in packaging films for food and pharmaceuticals, food packaging containers (including bottles), optical films, industrial films, etc., and is especially preferred for use as food packaging films for contents that require high-temperature sterilization treatments such as boiling sterilization, steam sterilization, or heat treatments such as cooking.

[0222] In addition, by including pigments and other colorants in the above-mentioned coating agent, printing ink can be prepared and applied to plastic film, paper, various containers, etc., thus it can also be preferably used as a printing film or printing body.

[0223] It should be noted that in the above description, polyurethane layer 3 is described as a single layer, but for example, it can be as follows: Figure 2 As shown, the polyurethane layer 3 consists of two layers: a first polyurethane layer 3a stacked on the substrate 2 and a second polyurethane layer 3b stacked on the first polyurethane layer 3a. In addition, although not shown, the polyurethane layer 3 may also be a multilayer consisting of three or more layers.

[0224] Furthermore, in such a polyurethane laminate 1, if the filler is dispersed in the polyurethane layer 3, the filler may be dispersed in at least one layer, or it may be dispersed in all layers. It should be noted that it is also possible for no filler to be dispersed in any layer.

[0225] For example, the polyurethane layer 3 can be two layers: a first polyurethane layer 3a stacked on the substrate 2 and a second polyurethane layer 3b stacked on the first polyurethane layer 3a, with the filler dispersed only in the second polyurethane layer 3b.

[0226] In addition, in the above description, the polyurethane layer 3 is laminated on the entire surface of one side of the substrate 2 in the thickness direction, but it is not limited to this. For example, although not shown, it can be laminated on two sides of the substrate 2 in the thickness direction, or it can be partially laminated on the substrate 2.

[0227] Example

[0228] The present invention will now be described based on embodiments and comparative examples, but the present invention is not limited to the embodiments described below. It should be noted that unless otherwise specified, "parts" and "%" are based on mass. In addition, the specific values ​​of the proportions (including proportions), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values ​​(values ​​defined in the form of "below" or "lower") or lower limit values ​​(values ​​defined in the form of "above" or "higher") of the proportions (including proportions), physical property values, parameters, etc., described in the "Specific Embodiments" above.

[0229] It should be noted that the determination methods used below are described.

[0230] <Carbonate ion concentration>

[0231] The concentration of carbonate ions in polyurethane dispersions was quantified using an electrophoresis system.

[0232] That is, after separating and weighing the polyurethane dispersion sample, it is appropriately diluted and dissolved with ultrapure water to prepare a quantitative sample solution. Then, the quantitative sample solution and the standard solution are measured using the following electrophoresis system. In addition, a sample determination solution with a known concentration of standard solution is prepared, and a recovery test is performed.

[0233] (Apparatus and Measurement Conditions)

[0234] Apparatus: Agilent Technologies 7100 capillary electrophoresis system; Buffer: Agilent Technologies harmful anion analysis buffer.

[0235] Then, the concentration of carbonate ions is determined using the single-point standard curve method, and their mass ratio is calculated.

[0236] <Residual Solvent>

[0237] The amount of residual solvent in polyurethane dispersions was quantified using gas chromatography.

[0238] Specifically, using 1-propanol as an internal standard, standard substances, polyurethane dispersions, and their respective quantitative sample aqueous solutions were prepared. Then, the residual solvent content in the polyurethane dispersion was calculated under the following gas chromatographic conditions.

[0239] (Apparatus and Measurement Conditions)

[0240] Device: Shimadzu Corporation GC-2014

[0241] Column: Sunpak-A 50 / 80 glass column, φ3.2mm×2mm×2.1m

[0242] Detector: FID

[0243] Synthesis example 1 (PUD1)

[0244] 170.7g of TAKENATE 500 (1,3-phenylene diisocyanate, m-XDI, manufactured by Mitsui Chemicals) and VestanatH 12 MDI (4,4'-methylenebis(cyclohexyl isocyanate), H 12 29.8 g of MDI (manufactured by Evonik), 34.4 g of ethylene glycol, 2.6 g of trimethylolpropane, 19.6 g of dimethylolpropionic acid, and 146.2 g of methyl ethyl ketone as a solvent were mixed and reacted at 65–70 °C under a nitrogen atmosphere until the isocyanate group concentration (NCO%) (based on the unit solid content after removing the solvent) reached 9.53% by mass, resulting in a reaction solution containing isocyanate-terminated prepolymer.

[0245] The urethane group concentration (input ratio) of the isocyanate-terminated prepolymer is 33.5% by mass.

[0246] Next, the reaction solution was cooled to 40°C, and then neutralized with 14.5g of triethylamine.

[0247] Next, the reaction solution was dispersed in 1009.7 g of ion-exchanged water using a homogenizer. An aqueous amine solution obtained by dissolving 28.5 g of 2-((2-aminoethyl)amino)ethanol in 85.6 g of ion-exchanged water was then added to the dispersion. Subsequently, a chain extension reaction was carried out for 2 hours to obtain the polyurethane resin.

[0248] Thus, polyurethane dispersion 1 (PUD1) was obtained.

[0249] The proportion of urethane and urea groups relative to 1 kg of polyurethane resin (solid component) was calculated based on the input ratio, and the result was 6.7 mol (39.6% by mass).

[0250] In addition, the acid value of the solid component of the polyurethane resin was determined according to JIS K 1557-5 (2007), and the result was 27.3 mg KOH / g.

[0251] Synthesis examples 2 to 8 (PUD 2 to 8)

[0252] Following the formulation shown in Table 1, polyurethane dispersions 2-8 (PUD2-8) were obtained using the same method as in Synthesis Example 1.

[0253] Examples 1-13 and Comparative Examples 1-4

[0254] The polyurethane dispersion (PUD) shown in Table 2 was vacuum-purged for the times shown in Table 2 under reduced pressure at a water bath temperature of 50°C using an evaporator. This confirmed that the proportion of methyl ethyl ketone as a solvent was below 0.3% by mass.

[0255] It should be noted that the solvent (methyl ethyl ketone) was quantified using gas chromatography. The detection limit for this quantitative method is 0.3% by mass.

[0256] Furthermore, as can be seen from Comparative Example 1, when vacuum purging is performed for 1 hour, the solvent concentration becomes less than 0.3% by mass, and the solvent removal ends.

[0257] Subsequently, the concentration was adjusted using ion-exchanged water in a manner that resulted in the solid component concentrations shown in Table 2.

[0258] "evaluate"

[0259] <Evaluation of Polyurethane Dispersions>

[0260] (1) Storage stability 1 (average particle size)

[0261] The particle size D1 of PUD was determined using a thick particle size analyzer FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.).

[0262] In addition, after storing PUD at 40°C for 7 days, the particle size D2 was measured using the same method.

[0263] Then, the rate of change of particle size (D2 / D1) before and after storage is calculated.

[0264] The results are shown in Table 2.

[0265] (2) Storage stability 2 (viscosity)

[0266] The viscosity V1 of PUD at 25°C was determined according to JIS K 7117 (1999).

[0267] In addition, after storing PUD at 40°C for 7 days, the viscosity V2 at 25°C was measured using the same method.

[0268] Then, the rate of change of particle size (V2 / V1) before and after storage is calculated.

[0269] The results are shown in Table 2.

[0270] (3) Mechanical stability

[0271] Using a Maron-type testing machine (Maron mechanical stability testing machine AB-802, manufactured by Tester Sangyo), 100g of PUD was treated for 15 minutes under a load of 15kg and a speed of 1,000rpm.

[0272] Subsequently, the treatment solution was filtered through a 100-mesh metal mesh, and the residue was washed with water and dried at 110°C for 2 hours to collect the coagulant. Then, the mass of the obtained coagulant was measured, and the coagulant concentration (mass%) was calculated.

[0273] Then, the ratio of aggregate concentration (%) to solid component concentration (%) of PUD was calculated, and the agglomeration rate of the polyurethane resin was determined using the following formula. This was used as an evaluation index. The results are shown in Table 2.

[0274] (Agglomeration rate of polyurethane resin (%)) = [(Agglomerate concentration) / (Solid component concentration)] × 100

[0275] It should be noted that the smaller the value, the higher the mechanical stability.

[0276] <Evaluation of Layered Structures>

[0277] (4) Oxygen permeability

[0278] Using a rod coater, a polyethylene terephthalate film (biaxially stretched polyester film, trade name: Toyobo ESTER FILM E5102, manufactured by Toyobo Corporation, thickness 12μm) was applied to the substrate, with a thickness of 3g / m² at the time of drying. 2 The PUD is coated in this manner.

[0279] Next, the coated film is placed in a drying oven set to 110°C for 1 minute to dry, resulting in a laminate.

[0280] Using an oxygen permeation measuring device (OX-TRAN2 / 20, MOCON), in accordance with JIS K 7126-2 (2006), measurements were taken immediately after the laminate was manufactured and 7 days after manufacturing at 40°C, at 20°C and a relative humidity of 80% (80% RH) per 1 m. 2 Oxygen permeability (cc) over 1 day and 1 atmosphere. The results are shown in Table 1.

[0281] It should be noted that the polyurethane dispersion of Comparative Example 1 has a high carbonate ion concentration (greater than 700 ppm), therefore, it is prone to aggregation, resulting in insufficient storage stability and mechanical stability.

[0282] In addition, the solid component concentration of the polyurethane dispersion in Comparative Example 2 was lower (less than 20% by mass), thus reducing the production efficiency of the coating and the reduction in transportation costs.

[0283] Furthermore, regarding the polyurethane dispersions of Comparative Examples 3 and 4, the gas barrier properties of the polyurethane resin were insufficient.

[0284] [Table 1]

[0285]

[0286] [Table 2]

[0287]

[0288] It should be noted that the details of the abbreviations in the table are recorded below.

[0289] XDI: Trade name TAKENATE 500, 1,3-phenylene diisocyanate, m-XDI, manufactured by Mitsui Chemicals.

[0290] H6XDI: Trade name TAKENATE 600, 1,3-bis(isocyanate methyl)cyclohexane, manufactured by Mitsui Chemicals.

[0291] TDI: Trade name TAKENATE 80, toluene diisocyanate, 2,4-polymer / 2,6-polymer = 80 / 20 (mass ratio), manufactured by Mitsui Chemicals.

[0292] H12MDI: Trade name VestanetH 12 MDI, 4,4'-methylenebis(cyclohexyl isocyanate), manufactured by Evonik

[0293] UH-200: Trade name ETERNACOLLR UH-200, polycarbonate diol, number average molecular weight 2000, manufactured by Ube Industries.

[0294] P400: Trade name Actcall P400, polypropylene glycol, number average molecular weight 400, manufactured by Mitsui Chemicals.

[0295] It should be noted that the above-described invention is provided as an illustrative embodiment of the present invention, and is merely an example and not intended to be limiting. Modifications of the invention that will be apparent to those skilled in the art are included in the appended claims.

[0296] Industrial availability

[0297] The polyurethane dispersion of the present invention is preferably used in packaging films for food and pharmaceutical products, food packaging containers, optical films, industrial films, etc.

[0298] Explanation of reference numerals in the attached figures

[0299] 1. Polyurethane laminate

[0300] 2. Substrate

[0301] 3. Polyurethane layer

Claims

1. A polyurethane dispersion, characterized in that, It is a polyurethane dispersion formed by dispersing polyurethane resin with water. The polyurethane resin is a reaction product of a water-dispersed isocyanate-terminated prepolymer and a chain extender. The isocyanate-terminated prepolymer is a reaction product obtained by reacting a polyisocyanate component with an active hydrogen-containing component containing an anionic group. The total molar ratio of urethane groups and urea groups is 1.5 moles or more per 1 kg of the polyurethane dispersion. The carbonate ion concentration is 10 ppm or more and 700 ppm or less relative to the polyurethane dispersion.

2. The polyurethane dispersion as described in claim 1, characterized in that, The polyurethane resin is a gas barrier polyurethane resin.

3. The polyurethane dispersion as described in claim 1, characterized in that, The polyisocyanate component contains a polyisocyanate comprising an aromatic ring.

4. The polyurethane dispersion as described in claim 1, characterized in that, The polyisocyanate component contains aromatic aliphatic polyisocyanates and alicyclic polyisocyanates.

5. The polyurethane dispersion as described in claim 1, characterized in that, The polyurethane resin is the product of the reaction of the following isocyanate-terminated prepolymer with a chain extender. The isocyanate-terminated prepolymer is formed by reacting a polyisocyanate component containing phenylene diisocyanate with a short-chain diol containing 2 to 6 carbon atoms and an active hydrogen-containing compound containing anionic groups.

6. The polyurethane dispersion as described in claim 1, characterized in that, The rate of change (D2 / D1) of the average particle size D2 of the polyurethane dispersion after storage at 40°C for 7 days relative to the average particle size D1 of the polyurethane dispersion before storage is less than 2.5.

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