JP7393173B2 - film coating agent - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to film coating agents.

Polyurethane aqueous dispersions are widely used as raw materials for paints and coating agents, for example, for interior and exterior applications such as aircraft and automobiles, and for exterior walls and flooring of houses. Therefore, polyurethane aqueous dispersions are required to provide coating films with various properties (for example, hardness, strength, durability, etc.) depending on the use and purpose for which they are used.

For example, Patent Document 1 describes a coating composition that can be easily reapplied or remove excess coating after being applied to a substrate, including (a) a polyisocyanate compound, (b) a number average molecular weight (A) obtained by reacting one or more polyol compounds containing a polycarbonate polyol having a molecular weight of 400 to 3,000, (c) an acidic group-containing polyol compound, and (d) an isocyanate group blocking agent that dissociates at 80 to 180°C. A polyurethane resin obtained by reacting a polyurethane prepolymer with a chain extender (B) having reactivity with isocyanate groups is dispersed in an aqueous medium, and the content ratio of urethane bonds and the content ratio of urea bonds are dispersed in an aqueous medium. The total content of carbonate bonds is 15 to 40% by weight on a solid content basis, and the content of isocyanate groups bonded to the blocking agent is 7 to 18% by weight on a solid content basis, and the content of isocyanate groups bonded to the blocking agent is on a solid content basis and A coating composition containing an aqueous polyurethane resin dispersion in an amount of 0.2 to 3% by weight calculated as isocyanate groups is disclosed.

JP 2015-7239 Publication

Coating compositions are required to have heat resistance, particularly resistance to heat yellowing, depending on their use and purpose, but conventional coating compositions have not had sufficient resistance to heat yellowing.

The present invention was made based on the above circumstances, and an object of the present invention is to provide a film coating agent that has excellent resistance to heat yellowing and excellent adhesion to substrates.

The present invention provides the following [1] to [3].
[1] A polyurethane water dispersion in which a polyurethane resin obtained by reacting an isocyanate group-terminated prepolymer obtained by reacting a polyisocyanate and a polyol with a compound having one or more amino groups is dispersed in water. and the polyol contains a polyol having one or more acidic groups, and the amino group mole is the molar ratio of the isocyanate group of the isocyanate group-terminated prepolymer to the amino group of the compound having one or more amino groups. A film coating agent comprising an aqueous polyurethane dispersion having a number/mole number of isocyanate groups of 1 or more.
[2] The film coating agent according to [1], wherein the polyurethane resin has a number average molecular weight of 3,000 or more and 15,000 or less.
[3] The film coating according to [1] or [2], wherein the compound having one or more amino groups is one or more selected from adipic acid dihydrazide, hydrazine, and ammonia. agent.

The present invention can provide a film coating agent that is resistant to heat yellowing and has excellent adhesion to substrates.

The film coating agent of the present invention contains an aqueous polyurethane dispersion.
The above-mentioned polyurethane aqueous dispersion is a polyurethane in which a polyurethane resin obtained by reacting an isocyanate group-terminated prepolymer obtained by reacting a polyisocyanate and a polyol with a compound having one or more amino groups is dispersed in water. An aqueous dispersion, wherein the polyol contains a polyol having one or more acidic groups, and the molar ratio of the isocyanate group of the isocyanate group-terminated prepolymer to the amino group of the compound having one or more amino groups. , the number of moles of amino groups/number of moles of isocyanate groups is 1 or more.

The polyisocyanate is not particularly limited, and polyisocyanates commonly used in the technical field can be used. Specifically, aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and araliphatic polyisocyanates can be mentioned.

Examples of aliphatic polyisocyanates include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate,
Examples include lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, and 3-methylpentane-1,5-diisocyanate.

Examples of the alicyclic polyisocyanate include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis(
Methyl isocyanate) cyclohexane and the like.

As the aromatic polyisocyanate, tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate, 1,5 -naphthylene diisocyanate , 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate and the like.

Examples of the aromatic aliphatic polyisocyanate include dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, xylylene diisocyanate, α,α,α,α-tetramethylxylylene diisocyanate, and the like.

Further, modified forms of these polyisocyanates such as dimers, trimers, and buretted isocyanates can be mentioned. These can be used alone or in combination of two or more.

Among the above polyisocyanates, from the viewpoint of heat resistance to yellowing and light resistance, one or more selected from aliphatic polyisocyanates, alicyclic polyisocyanates, and araliphatic polyisocyanates are preferred, particularly araliphatic polyisocyanates. Polyisocyanates are preferred.

The above-mentioned polyol consists of a polyol having one or more acidic groups and a polyol having no acidic group.

The above-mentioned polyol having no acidic group contains one or more selected from polyester polyols and polyether polyols.

The above polyester polyol can generally be obtained by a condensation reaction between a polyhydric carboxylic acid and a polyhydric alcohol.

The polycarboxylic acids mentioned above are not particularly limited, but specifically include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, scuberic acid, azelaic acid, sebacic acid, 1,12-dodecanedicarboxylic acid , phthalic anhydride, isophthalic acid, terephthalic acid, dimer acid, halogenated phthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, hexahydroterephthalic acid, hexahydroisophthalic acid, 2 , 6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid anhydride, 4,4'-biphenyl dicarboxylic acid, and dialkyl esters thereof. Examples include basic acids, acid anhydrides corresponding to these, and polybasic acids such as pyromellitic acid. These polyhydric carboxylic acids can be used alone or in combination of two or more. Examples of the α,β-unsaturated dibasic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, and itaconic anhydride.

The above polyhydric alcohols are not particularly limited, but specifically include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl- 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2-methyl-2-butyl -1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonane Diol, dihydric alcohol such as 2,4-diethyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, diethylene glycol, dipropylene glycol, triethylene glycol, glycerin, trimethylolpropane , pentaerythritol, sorbitol, and the like.

The polyether polyol is not particularly limited, and polyether polyols commonly used in the technical field can be used. Specifically, ethylene glycol, propylene glycol, propanediol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, neopetyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol. , dipropylene glycol, tripropylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol F, bisphenol S, hydrogenated bisphenol A, dibromobisphenol A, 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, hydroquinone dihydroxyethyl Examples include polyhydric alcohols such as ether, trimethylolpropane, glycerin, and pentaerythritol, and oxyalkylene derivatives thereof such as ethylene oxide, propylene oxide, and butylene oxide.

In the present invention, a polyol having a vinyl group may be contained as a polyol for the purpose of improving adhesion to a hard coat layer containing a UV curable resin and improving UV resistance. Specifically, the vinyl group-containing polyols include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycerin monoallyl ether, and trimethylol. Examples include propane diallyl ether and pentaerythritol triallyl ether. Among these, glycerin monoallyl ether is preferred in terms of UV resistance. The vinyl group-containing polyol is preferably 1 part by mass or more, more preferably 10 parts by mass or more, based on 100 parts by mass of the polyurethane, from the viewpoint of improving adhesion to the hard coat layer containing the UV-curable resin and UV resistance. . On the other hand, it is preferably 50 parts by mass or less, more preferably 30 parts by mass or less.

Polyols other than the above-mentioned polyester polyols and polyether polyols may be used within a range that does not impede the effects of the present invention. As polyols other than the above-mentioned polyester polyols and polyether polyols, specifically, known polycarbonates, polyether esters, polyacetals, polyolefins, fluorine-based, vegetable oil-based, etc. can be used. More specifically, carbonate polyols of 1,6-hexanediol, carbonate polyols of 1,4-butanediol and 1,6-hexanediol, carbonates of 1,5-pentanediol and 1,6-hexanediol, 3 -carbonate polyols of methyl-1,5-pentanediol and 1,6-hexanediol, carbonates of 1,9-nonanediol and 2-methyl-1,8-octanediol, 1,4-cyclohexanedimethanol and 1, 6-hexanediol carbonate, 1,4-cyclohexanedimethanol carbonate, polycaprolactone polyol, polyester polyol, polythioether polyol, polyacetal polyol, polytetramethylene glycol, polybutadiene polyol, castor Examples include polyol compounds such as oil polyol, soybean oil polyol, fluorine polyol, silicone polyol, and modified products thereof.

In the present invention, the content of the polyester polyol and/or polyether polyol is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and the lower limit is 100 parts by mass or less, based on 100 parts by mass of the polyol. The amount is preferably 60 parts by mass or less, and more preferably 60 parts by mass or less. It is preferable in terms of refractive index and hardness that the content of the polyester polyol and/or polyether polyol is within the above range.

Moreover, the content ratio of polyester polyol and polyether polyol is preferably 50 parts by mass or more, and more preferably 80 parts by mass or more, with respect to 100 parts by mass of polyester polyol. On the other hand, it is preferably 200 parts by mass or less, more preferably 120 parts by mass or less. When the content ratio is within the above range, it is preferable in terms of refractive index, hardness, and heat resistance.

In the present invention, the polyol may contain a polyol having a number average molecular weight of 400 or less.

Among the polyols mentioned above, the polyols having a number average molecular weight of 400 or less are the polyols described below. That is, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,
Neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 3-methylpentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, cyclohexanedimethanol, glycerin, or trimethylolpropane. Among these, one or two selected from glycerin and trimethylolpropane are preferred in terms of solvent resistance.

The content of the polyol having a number average molecular weight of 400 or less is 100% of the polyurethane resin
It is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more. Further, the amount is preferably 3 parts by mass or less, and more preferably 1 part by mass or less. When the content is within the above range, it is preferable in terms of handling during urethane resin production.

Examples of the acidic group of the polyol having an acidic group include carboxyl groups and salts thereof, sulfonic acid groups and salts thereof, and the like.

Examples of the polyol having a carboxyl group include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dioxymaleic acid, 2,6-dioxybenzoic acid, 3, Examples include carboxylic acid-containing compounds such as 4-diaminobenzoic acid, derivatives thereof, and salts thereof, as well as polyester polyols obtained using these. Further examples include amino acids such as alanine, aminobutyric acid, aminocaproic acid, glycine, glutamic acid, aspartic acid, and histidine, and carboxylic acids such as succinic acid, adipic acid, maleic anhydride, phthalic acid, and trimellitic anhydride.

Examples of the polyol having the above sulfonic acid group and its salt include 2-oxyethanesulfonic acid, phenolsulfonic acid, sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid, sulfanilic acid, 1,3-phenylenediamine-4 ,6-disulfonic acid,2
, 4-diaminotoluene-5-sulfonic acid and other sulfonic acid-containing compounds and derivatives thereof, and polyester polyols and polyamide polyols obtained by copolymerizing these;
Examples include polyamide polyester polyol.

By neutralizing these carboxyl groups or sulfonic acid groups into salts, the polyurethane finally obtained can be made water-dispersible. Examples of neutralizing agents in this case include nonvolatile bases such as sodium hydroxide and potassium hydroxide, tertiary amines such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, and triethanolamine, and volatile bases such as ammonia. Examples include bases. Neutralization can be performed before, during, or after the urethanization reaction.

As the neutralizing agent, an amine compound having a boiling point of 100° C. or lower is preferable. Specific examples include tertiary amines such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, and triethanolamine, and volatile bases such as ammonia.

In the present invention, the above-mentioned polyol having an acidic group is preferably the above-mentioned polyol having a carboxyl group, and 2,2-dimethylolpropionic acid is particularly preferable, from the viewpoint of raw material supply stability and versatility.

As the compound having one or more amino groups, one or more selected from hydrazines such as ammonia, hydrazine, carbodihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, and phthalic acid dihydrazide can be used. can. The above-mentioned compound having one or more amino groups is preferably one or more selected from ammonia, hydrazine, and adipic acid dihydrazide from the viewpoint of resistance to heat yellowing, and adipic acid dihydrazide is more preferable.

The method for producing the aqueous polyurethane dispersion of the present invention is not particularly limited, but generally, the stoichiometric amount is An isocyanate group-terminated prepolymer is produced by reacting an excess polyisocyanate in an equivalent ratio of 1:0.85 to 1.1 with the total amount of isocyanate groups and hydroxyl groups without a solvent or in an organic solvent having no active hydrogen groups. After synthesis, the molar ratio between the isocyanate group of the isocyanate group-terminated prepolymer and the amino group of the compound having one or more amino groups, ie, the number of moles of amino groups/the number of moles of isocyanate groups, is 1 or more. An aqueous polyurethane dispersion can be obtained by reacting a compound having an amino group to neutralize the acidic groups of the urethane prepolymer and dispersing and emulsifying it in water. The dispersion and emulsification may be performed before the reaction of the isocyanate group-terminated prepolymer with the compound having one or more amino groups. Thereafter, by removing the used solvent as necessary, a polyurethane aqueous dispersion can be obtained.

The molar ratio of the isocyanate groups of the isocyanate group-terminated prepolymer to the amino groups of the compound having one or more amino groups, the number of moles of amino groups/the number of moles of isocyanate groups, is 1 or more, but preferably 1.05 or more. , more preferably 1.1 or more. Moreover, 2.0 or less is preferable, and 1.25 or less is more preferable. When the equivalent ratio is within the above range, a film coating agent with excellent resistance to heat yellowing and adhesion to the substrate can be obtained.

The above-mentioned organic solvents having no active hydrogen group are not particularly limited, but specific examples include dioxane, methyl ethyl ketone, dimethyl formamide, tetrahydrofuran, N-methyl-2
-Pyrrolidone, toluene, propylene glycol monomethyl ether acetate, etc. It is preferable that these hydrophilic organic solvents used in the reaction are finally removed.

The number average molecular weight of the polyurethane in the aqueous polyurethane dispersion in the present invention is 3000 or more and 16000 or less from the viewpoint of solvent resistance, substrate adhesion, and UV curing resin (hard coat layer), but 4000 or more. 12000 or less is more preferable

The acid value of the polyurethane is preferably 20 mgKOH/g or more, more preferably 30 mgKOH/g or more from the viewpoint of adhesion to the substrate. On the other hand, it is preferably 50 mgKOH/g or less, more preferably 40 mgKOH/g or less.

The degree of crosslinking of the polyurethane is preferably 0.01 mol/Kg or more, more preferably 0.03 mol/Kg or more from the viewpoint of substrate adhesion and solvent resistance. On the other hand, it is preferably 1 mol/Kg or less, more preferably 0.5 mol/Kg or less.

The amount of urethane bonding in the polyurethane is preferably 2.0 mol/Kg or more, more preferably 2.5 mol/Kg, from the viewpoint of hardness, heat resistance, and substrate adhesion. On the other hand, it is preferably 10.0 mol/Kg or less, more preferably 7.5 mol/Kg or less.

The film coating agent of the present invention preferably contains the above-mentioned polyurethane based on 100 parts by mass of the film coating agent in terms of transparency, heat resistance to yellowing, adhesion to substrates, and adhesion to UV curable resin (hard coat layer). It contains 20 parts by mass or more, more preferably 50 parts by mass or more. Further, the content is preferably 90 parts by mass or less, more preferably 80 parts by mass or less.

The film coating agent of the present invention may contain pigments, thickeners, ultraviolet absorbers, antioxidants, light stabilizers, antifoaming agents, plasticizers, and surface conditioners, as necessary, as long as they do not impede the effects of the present invention. , other additives such as anti-settling agents. One type of additive may be used alone, or two or more types may be used in combination.

The above pigments are not particularly limited, but specifically include, for example, inorganic pigments such as titanium dioxide, zinc oxide, iron oxide, calcium carbonate, barium sulfate, yellow lead, clay, talc, carbon black, azo pigments, diazo pigments, Examples include organic pigments such as condensed azo, thioindigo, indanthrone, anthraquinone, benzimidazole, phthalocyanine, isoindolinone, perylene, quinacridone, dioxane, and diketopyrrolopyrrole.

The above-mentioned thickener is not particularly limited, but specifically includes at least one type selected from the group consisting of synthetic polymers, cellulose and polysaccharides, and turpentine emulsions (each alone or a mixture of two or more of these).

Examples of synthetic polymers include polyacrylic acids, polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, polyvinyl methyl ether, and polyacrylamide. Examples of cellulose include ethyl cellulose, methyl cellulose, hydroxymethyl cellulose, carboxymethyl cellulose, and the like. Examples of the polysaccharide include xanthan gum, guar gum, casein, gum arabic, gelatin, carrageenan, alginic acid, gum tragacanth, locust bean gum, and pectin.

Examples of the turpentine emulsion include a mousse-like emulsion made by emulsifying mineral turpentine and water with a nonionic surfactant.

The above-mentioned ultraviolet absorbers are not particularly limited, but specific examples include benzophenone, benzotriazole, cyanoacrylate, salicylate, and oxalic acid anilide. Examples of the ultraviolet stabilizer include hindered amine compounds. More specifically, light stabilizers such as "TINUVIN622LD", "TINUVIN765" (all manufactured by Ciba Specialty Chemicals), "SANOL LS-2626" and "SANOL LS-765" (all manufactured by Sankyo) , "TINUVIN328" and "TINUVIN234" (all manufactured by Ciba Specialty Chemicals).

The above antioxidants are not particularly limited, but specifically include "IRGANOX245", "IRGANOX1010" (manufactured by Ciba Specialty Chemicals), "Sumilizer GA-80" (manufactured by Sumitomo Chemical), and 2. Examples include 6-dibutyl-4-methylphenol (BHT).

The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[Synthesis of polyester polyol (a-1)]
While bubbling nitrogen gas in a reaction vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 16.76 parts by mass of maleic anhydride, 83.14 parts by mass of bisphenol A-2EO adduct, and 0 parts of dioctyltin were added. The reaction temperature was set at 160 to 170°C so that the tower top temperature was 50 to 60°C, and the reaction was carried out until the acid value became 2.6 mgKOH/g or less, and the hydroxyl value was 98. A polyester polyol (a-1) having a weight average molecular weight of 9 mgKOH/g and a weight average molecular weight of 1100 was obtained.
The average hydroxyl value of the polyol was measured according to JIS K 1557.

[Synthesis of polyester polyol (a-2)]
While bubbling nitrogen gas in a reaction vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 17.05 parts by mass of succinic acid, 82.85 parts by mass of bisphenol A-2EO adduct, and 0.5 parts by mass of dioctyltin were added. The reaction temperature was set at 160 to 170°C so that the tower top temperature was 50 to 60°C, and the reaction was carried out until the acid value became 2.6 mgKOH/g or less, resulting in a hydroxyl value of 98.5 mgKOH. A polyester polyol (a-2) having a weight average molecular weight of 1,100 and a weight average molecular weight of 1,100 was obtained.

<Synthesis of polyurethane water dispersion>
[Example 1]
61.82 parts by mass of polyester polyol (a-1) (weight average molecular weight: 1100, hydroxyl value: 98.9 mgKOH/g) was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube. , 0.54 parts by mass of trimethylolpropane, 9.14 parts by mass of dimethylolpropionic acid, and 100 parts by mass of methyl ethyl ketone were added and dissolved with sufficient stirring. Then, 28.5 parts by mass of xylene diisocyanate was added, and the NCO content was 1.0%. The reaction was carried out at 75°C until the temperature reached 75°C. After that, this prepolymer solution was cooled to 45 ° C., 1.16 parts by mass of ammonia and 300 parts by mass of water were added as neutralizing agents, and emulsified using a homomixer, and then 0.41 parts by mass of ammonia was added, The end-blocking reaction was carried out at 30°C for 30 minutes. This resin solution was heated under reduced pressure to distill off methyl ethyl ketone to obtain an aqueous polyurethane dispersion with a solid content of 25%.

[Example 2], [Example 8], [Example 13] to [Example 15] are the same as [Example 1] except that the types and amounts of each raw material were changed as shown in Table 1 below. Each polyurethane aqueous dispersion was produced in the same manner as above.

[Example 3]
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, a 4-mol adduct of bisphenol A with ethylene oxide (product name: Newpol BPE-20NK, manufactured by Sanyo Chemical Industries, Ltd., weight average molecular weight :400, hydroxyl value: 345mgKOH/g), 33.72 parts by mass of glycerin monoallyl ether (product name: Neoallyl E-10, manufactured by Osaka Soda Co., Ltd.), and 8.00 parts by mass of dimethylolpropionic acid. 40 parts by mass and 100 parts by mass of methyl ethyl ketone were added and sufficiently stirred and dissolved, and then 47.88 parts by mass of xylene diisocyanate was added and reacted at 75°C until the NCO content became 1.0%. Thereafter, 4.15 parts by mass of adipine dihydrazide was added, and an end blocking reaction was carried out at 30° C. for 30 minutes. Thereafter, 1.07 parts by mass of ammonia and 300 parts by mass of water were added as neutralizing agents, and the mixture was emulsified using a homomixer. Thereafter, 10 parts by mass of adipic acid dihydrazide was added as an additive. This resin solution was heated under reduced pressure to distill off methyl ethyl ketone to obtain an aqueous polyurethane dispersion with a solid content of 25%.

[Example 4], [Example 6], [Example 7], [Example 9], [Example 11], and [Example 12], the types and amounts of each raw material are shown in Table 1 below. Each polyurethane aqueous dispersion was obtained in the same manner as in [Example 3] except for the changes as shown.

[Example 5] and [Example 10] are the same as [Example 3] except that the types and amounts of each raw material were changed as shown in Table 1 below, and adipic acid dihydrazide was not added as an additive. Each urethane water dispersion was produced in the same manner.

[Comparative example 1]
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, a 4-mol adduct of bisphenol A with ethylene oxide (product name: Newpol BPE-20NK, manufactured by Sanyo Chemical Industries, Ltd., weight average molecular weight :400, hydroxyl value: 345mgKOH/g), 33.72 parts by mass of glycerin monoallyl ether (product name: Neoallyl E-10, manufactured by Osaka Soda Co., Ltd.), and 8.00 parts by mass of dimethylolpropionic acid. 40 parts by mass and 100 parts by mass of methyl ethyl ketone were added and sufficiently stirred and dissolved, and then 47.88 parts by mass of xylene diisocyanate was added and reacted at 75°C until the NCO content became 1.0%. Thereafter, 8.94 parts by mass of triethylamine and 300 parts by mass of water were added as a neutralizing agent and emulsified using a homomixer, and stirring by the homomixer was continued to carry out a chain elongation reaction with water. This resin solution was heated under reduced pressure to distill off methyl ethyl ketone to obtain an aqueous polyurethane dispersion with a solid content of 25%.

[Comparative Example 2] was produced in the same manner as [Comparative Example 1] except that the types and amounts of each raw material were changed as shown in Table 1 below, and each polyurethane aqueous dispersion was obtained.

[Comparative example 3]
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, a 4-mol adduct of bisphenol A with ethylene oxide (product name: Newpol BPE-20NK, manufactured by Sanyo Chemical Industries, Ltd., weight average molecular weight :400, hydroxyl value: 345mgKOH/g), 33.72 parts by mass of glycerin monoallyl ether (product name: Neoallyl E-10, manufactured by Osaka Soda Co., Ltd.), and 8.00 parts by mass of dimethylolpropionic acid. 40 parts by mass and 100 parts by mass of methyl ethyl ketone were added and sufficiently stirred and dissolved, and then 47.88 parts by mass of xylene diisocyanate was added and reacted at 75°C until the NCO content became 1.0%. Thereafter, 8.94 parts by mass of triethylamine and 300 parts by mass of water were added as a neutralizing agent and emulsified using a homomixer, 2.19 parts by mass of adipic acid dihydrazide was added, and stirring with the homomixer was continued. A chain extension reaction was performed. This resin solution was heated under reduced pressure to distill off methyl ethyl ketone to obtain an aqueous polyurethane dispersion with a solid content of 25%.

*1: 2 mole ethylene oxide adduct of bisphenol A (manufactured by Sanyo Chemical Industries, Ltd.)
*2: Trimethylolpropane
*3: Glycerin monoallyl ether (manufactured by Osaka Soda Co., Ltd.)
*4: Dimethylolpropionic acid
*5: Xylene diisocyanate
*6: Adipic acid dihydrazide

[Evaluation of polyurethane water dispersion]
Evaluation was made using the following evaluation method and evaluation criteria. The evaluation results are shown in Table 1.
<Exterior>
Judgment was made visually.
<Nonvolatile content>
Measured according to JIS K 6828.
<pH>
Evaluation was made in accordance with JIS Z8802.
<Viscosity>
The viscosity at 25° C. was measured using a BM type viscometer (single cylindrical rotational viscometer) according to JIS Z8803. At that time, (a) measure the rotor rotation speed at 60 rpm, (b) if the measured value in (a) above is 8000 mPa・s or more, change the rotor rotation speed to 30 rpm and measure, (c) If the measured value in (b) above was 16,000 mPa·s or more, the rotor rotation speed was changed to 12 rpm and the measurement was performed.
<Average particle size>
It was measured using Microtrac UPA-UZ152 (manufactured by Nikkiso Co., Ltd.), and the 50% average value was calculated as the particle diameter.

[Evaluation of heat resistance yellowing]
Evaluation was performed as follows. The evaluation results are shown in Table 1.
(Evaluation of polyurethane water dispersion)
The color of each polyurethane aqueous dispersion after being stored at 70° C. for 3 days was visually compared with the color before storage. The evaluation criteria are as follows.
◎: No change ○: Slight yellowing ×: Yellowing.
(Evaluation of film)
Each polyurethane aqueous dispersion was applied to a dry thickness of about 200 to 300 μm, dried at room temperature (25° C.) for 24 hours, then dried at 50° C. for 3 hours and at 120° C. for 20 minutes to form a film.
After heating the created film at 200° C. for 2 hours, the color of the film was visually evaluated.
◎: No change ○: Slightly yellowed ×: Discolored to blackish brown

[Evaluation of adhesion]
The base material (PET film (untreated)) was degreased using isopropyl alcohol. Next, the aqueous polyurethane dispersions obtained in the above Examples and Comparative Examples were applied using a bar coater to a dry film thickness of 5 μm, and dried for 10 minutes using a hot air drying oven at an ambient temperature of 280°C. was prepared, a 1 mm grid test was conducted, and evaluation was performed using the following evaluation criteria.
○: 100 out of 100 sections remain ×: 99 out of 100 sections or less remain

As shown in Table 1, a polyurethane water dispersion (Comparative Examples 1 and 2) in which a polyurethane resin that has been subjected to a chain extension reaction with water without reacting a compound having an amino group to the free NCO groups of a urethane prepolymer is dispersed in water (Comparative Examples 1 and 2) ) and an aqueous dispersion of a polyurethane resin subjected to chain extension using adipic acid dihydrazide, a compound having an amino group, resulted in worsening of heat-resistant yellowing of the film.

The film coating agent of the present invention can be used as a coating agent for PET films and the like, and is particularly useful as a film coating agent for optical applications.

Claims (3)

A polyurethane water dispersion in which a polyurethane resin obtained by reacting an isocyanate group-terminated prepolymer obtained by reacting a polyisocyanate and a polyol with a compound having one or more amino groups is dispersed in water,
The polyol contains a polyol having one or more acidic groups,
Polyurethane water in which the number of moles of amino groups/number of moles of isocyanate groups, which is the molar ratio of the number of moles of isocyanate groups in the isocyanate group-terminated prepolymer to the number of moles of amino groups in the compound having one or more amino groups, is 1.05 or more. containing a dispersion;
The polyisocyanate includes one or more selected from aliphatic polyisocyanates and araliphatic polyisocyanates,
A film coating agent , wherein the compound having one or more amino groups is an end blocking agent for the isocyanate group-terminated prepolymer . The film coating agent according to claim 1, wherein the polyurethane resin has a number average molecular weight of 3,000 or more and 15,000 or less. 3. The film coating agent according to claim 1, wherein the compound having one or more amino groups is one or more selected from adipic acid dihydrazide, hydrazine, and ammonia.