JP6655395B2 - Water-based polyurethane resin composition and optical film using the composition - Google Patents

Description

  The present invention relates to an aqueous polyurethane resin composition useful as a material for an adhesive layer between a polyester resin layer and a photocurable resin layer. Further, the present invention relates to an optical film, for example, a prism sheet, using the aqueous polyurethane resin composition.

  Various optical films are used in liquid crystal displays used in televisions, personal computers, and the like, and a prism sheet is used as a component of a backlight unit of the liquid crystal display to improve luminance. In the prism sheet, the function of condensing outgoing light emitted from the light guide in the direction of the liquid crystal panel by the prism inclined surface realizes an improvement in luminance. The prism sheet is made of a polyester resin such as PET and a photo-curing resin on which a prism pattern is formed. Various bonding layers have been used to bond the polyester resin and the photocurable resin. As a process of manufacturing a prism sheet, the polyester resin is heated and melted, and after the polyester resin extruded by a single-screw or twin-screw extruder is formed into a film by a stretching machine, the adhesive layer is coated on the surface of the polyester resin. There is a method in which a photocurable resin is brought into close contact with the above.

JP 2011-140139 A JP 2012-194308 A

The prism sheet is required to have high light transmittance with respect to ultraviolet light and visible light in a relatively low wavelength region, and heat resistance for maintaining performance at high temperatures such as in summer. Therefore, it is necessary that the adhesive layer for bonding the polyester resin and the photocurable resin has the same performance. Further, the adhesive layer is required to have a property of little adhesion to the photocurable resin and little adhesion (blocking property) between the films when the films are stacked. As an adhesive layer for such a prism sheet, for example, Patent Literatures 1 and 2 disclose an adhesive layer using an aqueous polyurethane resin composition. These prism sheet contact adhesive layer, it is possible to provide a prism sheet having both flexibility and high optical transparency and heat resistance by urethane. However, the improvement in the adhesiveness between these adhesive layers and the photocurable resin and the blocking property between the adhesive layers is not at a satisfactory level. The prism sheet, which is a component of the backlight unit of the liquid crystal display, still needs to be improved in the adhesion between the polyester resin layer and the photocurable resin layer constituting the prism sheet.

  Therefore, the present inventors have made intensive efforts to improve the adhesiveness of the adhesive layer to the photocurable resin and the blocking resistance when the aqueous polyurethane resin composition is used as the adhesive layer of the prism sheet.

  As a result, the present inventors have found that an aqueous polyurethane resin composition having good adhesion to a photocurable resin and improved blocking resistance can be obtained by using a (meth) acrylic compound as a raw material in combination. Was. That is, the present invention is as follows.

(Invention 1) A urethane prepolymer (A) obtained by reacting a polyol (a), a polyisocyanate (b), and an anionic group-introducing agent (c) with the following general formula (1) and / or general formula (2) ) In such a manner that the amount ratio of the urethane prepolymer (A) to the (meth) acrylic compound (B) is 100: 1 to 30 (mass ratio). A urethane prepolymer composition is prepared, and then the urethane prepolymer composition is dispersed in water such that the concentration of the urethane prepolymer composition becomes 10 to 70% by mass. An aqueous polyurethane resin composition for an optical film obtained by reacting the urethane prepolymer (A) with a chain extender (C).

(R ^{1 to} R ² represent a hydrogen atom or a methyl group. R ³ and R ⁴ each independently represent a divalent hydrocarbon group having 2 to 4 carbon atoms. R ⁵ represents a sulfur atom or a hydrocarbon group. M and n each represent an integer of 0 to 10.)

(R ⁶ , R ⁷ , and R ⁸ each independently represent a divalent hydrocarbon group having 2 to 10 carbon atoms. R ⁹ , R ¹⁰ , and R ¹¹ each independently represent a hydrogen atom or a methyl group.)
(Invention 2) The (meth) acrylic compound (B) is a compound represented by the general formula (1), wherein R ⁵ in the general formula (1) is a single bond, a methylene group, —CH (CH ₃ ) _{-, - C (CH 3)} 2 -, the following general formula (3-1) to be selected from any of the functional group represented by (3-7), the invention first optical film for aqueous polyurethane resin composition.

（ｍは４〜１２の整数を表す。）

(M represents an integer of 4 to 12.)

(Invention 3) The polyol (a) is at least one or more selected from a polyester polyol (a1), a polycarbonate diol (a2), a polyether polyol (a3), and a polyol (a3) having a number average molecular weight of less than 200. The aqueous polyurethane resin composition for an optical film according to the invention 1 or 2.

(Invention 4) The aqueous polyurethane resin composition for an optical film according to any one of Inventions 1 to 3, wherein the polyol (a) is at least one kind selected from polycarbonate diol (a2).

(Invention 5) The polyol (a) comprises a high molecular weight polyol (a-HM) having a number average molecular weight of 1500 to 5000 and a low molecular weight polyol (a-LM) having a number average molecular weight of 300 to 1000. The aqueous polyurethane resin set for an optical film according to any one of Inventions 1 to 4 (Invention 6), wherein the urethane prepolymer (A) has an acid value in the range of 30 to 80 mgKOH / g. Water-based polyurethane resin composition for optical films .

(Invention 7) An optical film comprising the aqueous polyurethane resin composition for an optical film according to any one of Inventions 1 to 6.

(Invention 8) A prism sheet including a layer comprising the aqueous polyurethane resin composition for an optical film according to any one of Inventions 1 to 6, a substrate film, and a layer of a cured product of a photocurable resin.

  According to the present invention, there is provided an aqueous polyurethane resin composition which has good adhesion to a polyester resin and a photocurable resin and is less likely to cause blocking between films. Further, the present invention provides a prism sheet suitable for components of a backlight unit of a liquid crystal display, which has less warpage due to curing shrinkage and has excellent moisture resistance and transparency.

  Hereinafter, embodiments of the aqueous polyurethane resin composition of the present invention will be described. The aqueous polyurethane resin composition of the present invention comprises a urethane prepolymer (A) obtained by reacting a polyol (a), a polyisocyanate (b), and an anionic group-introducing agent (c), and a (meth) acrylic compound. The urethane prepolymer composition mixed with (B) is dispersed in water so as to have a concentration of 10 to 70% by mass, and then the urethane prepolymer (A) in the obtained dispersion is converted into a chain extender ( It is obtained by crosslinking to C). In addition, the (meth) acrylic compound in this specification is a general term for a compound selected from any of an acrylic compound having at least one acryl group in a molecule and a methacryl compound having at least one methacryl group in a molecule. It is. The (meth) acryl group represents an acryl group or a methacryl group.

[Urethane prepolymer (A)]
The urethane prepolymer (A) is a component of the urethane prepolymer composition that is a raw material of the aqueous polyurethane resin composition of the present invention. The urethane prepolymer (A) is obtained by reacting a polyol (a), a polyisocyanate (b), and an anionic group-introducing agent (c). Hereinafter, the constituent components of the urethane prepolymer (A) of the present invention will be described.
(Polyol (a))
As the polyol (a), for example, a polyester polyol (a1), a polycarbonate diol (a2), a polyether polyol (a3), a polyol (a4) having a number average molecular weight of less than 200, and the like can be used.

  Examples of the polyester polyol (a1) include a compound obtained by an esterification reaction of a low molecular weight polyol and a polycarboxylic acid, and a ring ester polymerization reaction of a cyclic ester compound such as ε-caprolactone and γ-valerolactone. Compounds, and copolyesters thereof can be used.

  As the low molecular weight polyol, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3-propane Diol, neopentyl glycol, 2-butyl- Aliphatic diols such as -ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, and glycerin And aliphatic polyols such as trimethylolpropane, ditrimethylolpropane, tritrimethylolpropane and pentaerythritol. Examples of the low-molecular-weight polyol include, for example, aliphatic cyclic structure-containing polyols such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A, bisphenol A, alkylene oxide adducts of bisphenol A, bisphenol S, and alkylenes of bisphenol S. Bisphenol-type polyols such as oxide adducts can also be used. As these low molecular weight polyols, aliphatic polyols or aliphatic cyclic structure-containing polyols are preferred, and aliphatic diols are particularly preferred.

  Examples of the polycarboxylic acid include aliphatic acids such as succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and dimer acid, and 1,4-cyclohexanedicarboxylic acid and cyclohexanetricarboxylic acid. Cyclic polycarboxylic acid, orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid And aromatic polycarboxylic acids and their anhydrides or ester derivatives. The compound used as the polycarboxylic acid may be a single compound or a mixture of two or more compounds. As such a polycarboxylic acid, an aliphatic polycarboxylic acid is preferable, and an aliphatic dicarboxylic acid is particularly preferable.

  As the polyester polyol (a1), a polyester polyol having no aromatic cyclic structure is preferable, and a polyester polyol obtained by reacting an aliphatic polyol with an aliphatic polycarboxylic acid is more preferable. In order to improve the heat resistance and light transmittance of the prism sheet using the aqueous polyurethane resin composition of the present invention, the prism sheet has an aliphatic polyol having 2 to 6 carbon atoms and 2 to 6 carbon atoms. A polyester polyol obtained by reacting with an aliphatic polycarboxylic acid is particularly preferred as the polyester polyol (a1).

  As the polycarbonate diol (a2), those obtained by reacting a carbonate ester and / or phosgene with a polyol described below can be used. As the carbonic acid ester, for example, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, diphenyl carbonate, dinaphthyl carbonate, phenylnaphthyl carbonate and the like can be used.

Examples of the polyol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7 -Heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, Neopentyl glycol, 2-butyl-2-ethyl Le-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1, using the fat di- ol such as 8-octanediol Can be. Furthermore, low molecular weight dihydroxy compounds such as 1,4-cyclohexanedimethanol, hydroquinone, resorcinol, bisphenol A, bisphenol F, and 4,4′-biphenol; and polyols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol as the above polyols. Ether polyols; polyester polyols such as polyhexamethylene adipate, polyhexamethylene succinate, and polycaprolactone can also be used. As the polyol used for producing such polycarbonate diol (a2), an aliphatic diol is preferable, and 1,6-hexanediol is more preferable.

  As the polyether polyol (a3), those obtained by subjecting an alkylene oxide to addition polymerization using one or more compounds having two or more active hydrogen atoms as an initiator can be used.

  Examples of the initiator include water, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, and 1,2-butane. Diol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol 1,1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3 -Propanediol, neopentyl glycol, 2-butyl-2-ethyl 1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, glycerin, diglycerin, trimethylolpropane, ditri Methylolpropane, tritrimethylolpropane, 1,2,6-hexanetriol, triethanolamine, triisopropanolamine, pentaerythritol, dipentaerythritol, sorbitol, saccharose, ethylenediamine, N-ethyldiethylenetriamine, 1,2-diaminopropane , 1,3-diaminopropane, 1,2-diaminobutane, 1,3-diaminobutane, 1,4-diaminobutane, diethylenetriamine, phosphoric acid, acidic phosphoric acid ester, and the like.

  As the alkylene oxide, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran and the like can be used.

  Examples of the polyol (a4) having a number average molecular weight of less than 200 include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol, triethylene glycol, -Butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, , 5-Heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol Aliphatic diols such as 1,9-nonanediol; alicyclic diols such as cyclohexanedimethanol and cyclohexanediol; trivalent or higher valent such as trimethylolethane, trimethylolpropane, hexitols, pentitols, glycerin, pentaerythritol and the like. Polyols can be used.

The polyol (a) may be any of the above-mentioned polyester polyol (a1), polycarbonate diol (a2), polyether polyol (a3), and low molecular polyols (a4) having a number average molecular weight of less than 200, use of heat resistance and polycarbonate diols for the light transmitting the prism sheet formed with a water-based poly urethane resin composition of the present invention (a2) are preferred. As such a polycarbonate diol (a2), a polycarbonate diol having no aromatic cyclic structure is more preferable, and a polycarbonate diol having a 1,6-hexanediol skeleton is particularly preferable.

  In the present invention, two kinds of polyols having different number average molecular weights can be used in combination as the polyol (a). Such a polyol (a) has a number average molecular weight of 1500 to 5000, preferably 1700 to 3000, more preferably 1800 to 2200, and a number average molecular weight of 300 to 1000, preferably Consists of 400 to 700 low molecular weight polyols (a-LM). The ratio of the high molecular weight polyol (a-HM) to the low molecular weight polyol (a-LM) is not limited, but the ratio of the high molecular weight polyol (a-HM) to the total amount of the polyol (a) is preferably 1 to 70 mass. %, More preferably 3 to 50% by mass, particularly preferably 5 to 30% by mass.

By using a high molecular weight polyol (a-HM) and a low molecular weight polyol (a-LM) in combination as the polyol (a) of the present invention, it is possible to reduce blocking of a film composed of the aqueous polyurethane resin composition of the present invention. it can. Although the mechanism of the blocking reduction has not yet been sufficiently elucidated, the use of the low molecular weight polyol (a-LM) reduces the amount of the soft segment in the resin, and accordingly, the soft segment in the aqueous polyurethane resin composition. It is presumed that the scale of the micro-Brownian motion decreases, and as a result, the binding between the aqueous polyurethane resin compositions is suppressed. In addition, when the polyol (a) contains the high-molecular-weight polyol (a-HM), the viscosity of the obtained urethane prepolymer (A) decreases, and there is an advantage that the urethane prepolymer (A) that can be easily handled is obtained. .

(Polyisocyanate (b))
Examples of the polyisocyanate (b) include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and xylylene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, and 4,4′-dicyclohexylmethane. Aliphatic or alicyclic structure-containing diisocyanates such as diisocyanate and tetramethylxylylene diisocyanate can be used. Further, a compound obtained by trimerizing the above aromatic diisocyanate or the above diisocyanate having an aliphatic or alicyclic structure can also be used. These compounds may be used alone, or two or more of these compounds may be used in combination.

To further improve the optical transparency and heat resistance in the ultraviolet or low wavelength region such as visible light of a prism sheet formed with a water-based poly urethane resin composition of the present invention, an aliphatic ring as the polyisocyanate (b) Formula structure-containing diisocyanates are preferred, and 4,4'-dicyclohexylmethane diisocyanate or isophorone diisocyanate is more preferred. 4,4'-Dicyclohexylmethane diisocyanate is particularly preferred for the heat resistance of the prism sheet.

(Anionic group-introducing agent (c))
Examples of the anionic group-introducing agent (c) include polyols containing a carboxyl group such as dimethylolpropionic acid, dimethylolbutanoic acid, dimethylolbutyric acid, and dimethylolvaleric acid, and 1,4-butanediol-2-sulfone Polyols containing a sulfonic acid group such as an acid can be used.
In terms of easy availability, polyols containing a carboxyl group are preferable, and dimethylolpropionic acid is more preferable.

(Amount of (a), (b), (c))
In general, when a urethane prepolymer is produced by reacting a polyol, a polyisocyanate, and an anionic group-introducing agent, the total isocyanate group equivalent (NCO) of the polyisocyanate and the total hydroxyl group equivalent contained in the polyol and the anionic group-introducing agent are used. The terminal structure of the obtained urethane prepolymer varies depending on the ratio of (OH). When the NCO / OH is less than 1.0, that is, when the number of hydroxyl groups in the reaction components is excessive, a urethane prepolymer having a terminal group of a hydroxyl group is obtained. When the ratio NCO / OH is 1.0 or more, that is, when the isocyanate group in the reaction component is excessive, a urethane prepolymer having terminal isocyanate groups is obtained. Urethane prepolymers whose terminal groups are isocyanate groups have higher water dispersibility than urethane prepolymers whose terminal groups are hydroxyl groups, and are easily polymerized by chain extension. Therefore, as the urethane prepolymer (A) of the present invention, a urethane prepolymer having an isocyanate terminal group is preferable.

However, when the ratio NCO / OH is 1.0 or more and less than 1.1, a relatively high molecular weight urethane prepolymer is obtained, and such a high molecular weight urethane prepolymer tends to have poor dispersibility in water. There is. In this case, the storage stability of the water-based polyurethane resin composition finally obtained may be deteriorated. When the ratio NCO / OH is more than 2.5, the product contains a high concentration of isocyanate groups. Therefore, when the obtained prepolymer is dispersed in water, the isocyanate groups react with water to produce carbon dioxide. This may cause manufacturing problems such as rapid foaming. Further, in this case, there is a possibility that the adhesiveness between the obtained coating film composed of the aqueous polyurethane resin composition and the base material may be reduced.

  Therefore, when producing the urethane prepolymer (A) of the present invention, the polyol (a), the polyisocyanate (b), and the anion group-introducing agent (c) are combined with the total isocyanate group equivalent of the polyisocyanate (b). The ratio (NCO / OH) of (NCO) to the total hydroxyl equivalent (OH) contained in the polyol (a) and the anionic group-introducing agent (c) is preferably 1.1 to 2.5, more preferably 1.2. The components (a), (b), and (c) are blended so as to be 2.0 to 2.0, particularly preferably 1.3 to 1.8.

(Acid value of urethane prepolymer (A))
In order to reduce the blocking of the aqueous polyurethane resin composition of the present invention, the acid value of the urethane prepolymer (A) is preferably 35 to 90 mgKOH / g, more preferably the acid value is 40 to 80 mgKOH / g, particularly Preferably, it is set in the range of 50 to 70 mgKOH / g. The anionic group-introducing agent (c) is used in an amount corresponding to the acid value of the urethane prepolymer (A). The acid value of the urethane prepolymer (A) is a theoretical value obtained from the amount of the reaction components of the urethane prepolymer (A). When an inert solvent is used for producing the urethane prepolymer (A) as described later, the measured value of the acid value of the obtained urethane prepolymer (A) varies from the theoretical value described above. The following relationship exists between the above theoretical value and the measured value.
Acid value (theoretical value)
= Acid value (measured value) x {(a) + (b) + (c) + solvent: total mass} / {(a) + (b) + (c): total mass}
(catalyst)
In the production of the urethane prepolymer (A) of the present invention, a catalyst can be used if necessary. Such catalysts include, for example, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N'-tetramethylpropylenediamine, N, N, N ', N ", N''-Pentamethyldiethylenetriamine, N, N, N', N ", N" -pentamethyl- (3-aminopropyl) ethylenediamine, N, N, N ', N ", N" -pentamethyldipropylene Triamine, N, N, N ', N'-tetramethylguanidine, 1,3,5-tris (N, N-dimethylaminopropyl) hexahydro-S-triazine, 1,8-diazabicyclo [5.4.0] Undecene-7, triethylenediamine, N, N, N ', N'-tetramethylhexamethylenediamine, N-methyl-N'-(2-dimethylaminoethyl) piperazine, N, N'-dimethylpiperazine, dimethylcy Clohexylamine, N-methylmorpholine, N-ethylmorpholine, bis (2-dimethylaminoethyl) ether, N, N-dimethyllaurylamine, 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2- Tertiary amines such as methylimidazole and 1-dimethylaminopropylimidazole can be used. In addition, quaternary ammonium salts such as tetraalkylammonium halides such as tetramethylammonium chloride, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, and tetraalkylammonium organic acid salts such as tetramethylammonium 2-ethylhexanoate. Grade ammonium salt, stannas diacetate, stannas dioctoate, stannas dioleate, stannas dilaurate, dibutyl tin oxide, dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tin dichloride, dioctyl tin dilaurate, lead octoate, lead naphthenate And organometallic catalysts such as nickel naphthenate, cobalt naphthenate and the like. These catalysts may be used alone or in combination of two or more. Among these catalysts, organometallic catalysts are preferable, and dibutyltin dilaurate or dioctyltin dilaurate is more preferable in terms of less yellowing and good reactivity. The amount of such a catalyst is not particularly limited, but is preferably 0.001 to 1% by mass based on the total amount of the polyol (a), the polyisocyanate (b), and the anionic group-introducing agent (c). , More preferably 0.01 to 0.1% by mass.

(Crosslinking agent)
In the production of the urethane prepolymer (A) of the present invention, a crosslinked structure can be introduced into the urethane prepolymer (A) using a crosslinking agent. As the cross-linking agent, a cross-linking agent generally used in synthesizing the urethane prepolymer can be used without limitation. As such a crosslinking agent, for example, melamine, monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, hexamethylol melamine, methylated methylol melamine, butylated methylol melamine, melamine resin and the like are used. can do. As the crosslinking agent used in the present invention, melamine which is excellent in dispersibility in polyurethane and is inexpensive is preferable. The amount of the crosslinking agent to be used is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the polyol (a).

(Production of urethane prepolymer (A))
The urethane prepolymer (A) used in the present invention comprises the above polyol (a), polyisocyanate (b), anionic group-introducing agent (c), an optional catalyst and / or a crosslinking agent, and an optional inert solvent. It is obtained by reacting in the presence. As the inert solvent used at this time, acetone, methyl ethyl ketone, dioxane, tetrahydrofuran, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, etc., having a high affinity for water can be used. When a solvent having a boiling point of 100 ° C. or lower is used, it is preferable to remove the solvent by distillation under reduced pressure after synthesizing the aqueous polyurethane resin of the present invention. The amount of the solvent used is not particularly limited, but is preferably 3 to 200 parts by mass with respect to 100 parts by mass of the total amount of the raw material of the urethane prepolymer (A). The obtained urethane prepolymer (A) is dispersed in water together with a (meth) acrylic compound (B) described below to form a urethane prepolymer composition.

[(Meth) acrylic compound (B)]
The (meth) acrylic compound (B) is a component of the urethane prepolymer composition that is a raw material of the aqueous polyurethane resin composition of the present invention. The (meth) acrylic compound (B) is dispersed in water together with the urethane prepolymer (A) to form a urethane prepolymer composition. The (meth) acrylic compound (B) of the present invention is an acrylic compound represented by the following general formula (1) or (2).

(R ¹ and R ² each independently represent a hydrogen atom or a methyl group. R ³ and R ⁴ each independently represent a divalent hydrocarbon group having 2 to 4 carbon atoms. R ⁵ represents a sulfur atom or a carbon atom. Represents a hydrogen group, m and n each represent an integer of 0 to 10.)

(R ⁶ , R ⁷ , and R ⁸ each independently represent a divalent hydrocarbon group having 2 to 10 carbon atoms. R ⁹ , R ¹⁰ , and R ¹¹ each independently represent a hydrogen atom or a methyl group.)
In the above formula (1), R ¹ and R ² each independently represent a hydrogen atom or a methyl group. R ³ and R ⁴ are each independently a divalent hydrocarbon group having 2 to 4 carbon atoms, for example, 1,2-ethanediyl group, 1,1-ethanediyl group, 1,3-propanediyl group, 1,2- And represents a propanediyl group, a 1,1-propanediyl group, a 2,2-propanediyl group, a 1,4-propanediyl group, and the like. R ³ and / or R ⁴ are preferably a 1,2-ethanediyl group and / or a 1,2-propanediyl group in view of the availability of the (meth) acrylic compound (B).

In the above formula (1), R ⁵ represents a sulfur atom or a hydrocarbon group. R ⁵ which is a hydrocarbon group is, for example, a methanediyl group, a 1,2-ethanediyl group, a 1,1-ethanediyl group, a 1,3-propanediyl group, a 1,2-propanediyl group, a 1,1-propanediyl group 2,2-propanediyl group, 1,4-propanediyl group, 1,5-pentanediyl group, 1,6-hexanediyl group, 1-methyl-1,3-propanediyl group, 2-methyl-1, Aliphatic diyl groups such as a 3-propanediyl group, a 2-methyl-1,2-propanediyl group, a 1-methyl-1,4-butanediyl group, and a 2-methyl-1,4-butanediyl group; Alicyclic diyl groups such as cyclobutanediyl group, cyclopentanediyl group, cyclohexanediyl group, cycloheptanediyl group, cyclooctanediyl group, benzenediyl group, and toluenediyl And an aromatic diyl group such as a naphthalenediyl group, an anthracenediyl group, a phenanthenediyl group, and a fluorenediyl group. In view of the availability of the (meth) acrylic compound (B), preferred R ⁵ is a single bond, a methylene group, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, or a compound represented by the following general formula (3- It is a group selected from the functional groups shown in 1) to (3-7).

（ｍは４〜１２の整数を表す。）

(M represents an integer of 4 to 12.)

  In the above formula (1), m and n each represent an integer of 0 to 10. From the viewpoint of the compatibility between the urethane prepolymer (A) and the (meth) acrylic compound (B) in the aqueous dispersion and the water resistance of the coating film when the aqueous polyurethane resin composition is formed into a coating film, the above m, n is preferably from 0 to 5, more preferably from 0 to 3. When m or n is greater than 10, the compatibility between the urethane prepolymer (A) and the (meth) acrylic compound (B) in the aqueous dispersion is good, but the water resistance of the coating film made of the aqueous polyurethane resin composition is good. Is significantly reduced. Note that the numbers m and n are average values using integer values.

  Preferred compounds as the (meth) acrylic compound (B) represented by the above formula (1) are represented by any of the following formulas (4-1), (4-2), and (4-3). You.

(P and q are each independently an integer of 1 to 3.)

(Urethane prepolymer composition)
(Water dispersion)
In the present invention, a urethane prepolymer composition containing a urethane prepolymer (A) and a (meth) acrylic compound (B) is dispersed in water. The method of dispersing the urethane prepolymer composition in water is not particularly limited, and for example, the following prepolymer mixing method and phase inversion method can be used.
(Prepolymer mixing method) The urethane prepolymer (A) and the (meth) acrylic compound (B) are mixed. An anionic group neutralizer can be added together with the (meth) acrylic compound (B). The resulting mixture is poured into water to disperse the urethane prepolymer mixture in water. Note that an emulsifier can be added to water before the mixture is charged. Thus, the aqueous dispersion of the urethane prepolymer composition of the present invention is completed.
(Phase inversion method) The urethane prepolymer (A) and the (meth) acrylic compound (B) are mixed. Water is added to the obtained mixture to obtain a dispersion of the urethane prepolymer mixture and water. In addition, water to which an anionic group neutralizing agent and / or an emulsifier has been added in advance can be added. Thus, the aqueous dispersion of the urethane prepolymer composition of the present invention is completed.

(Anionic group neutralizer)
Examples of the anionic group neutralizer include trialkylamines such as trimethylamine, triethylamine, and tributylamine; N, N-dimethylethanolamine, N, N-dimethylpropanolamine, N, N-dipropylethanolamine, 1-dimethyl Tertiary amine compounds such as N, N-dialkylalkanolamines such as amino-2-methyl-2-propanol, trialkanolamines such as N-alkyl-N, N-dialkanolamines and triethanolamine; ammonia, Basic compounds such as trimethylammonium hydroxide, sodium hydroxide, potassium hydroxide and lithium hydroxide can be used. These compounds may be used alone, or two or more of these compounds may be used in combination. From the viewpoint of improving the weather resistance and water resistance of the dried product of the water-based polyurethane resin composition of the present invention, it is preferable to use a highly volatile anionic group neutralizing agent which is easily dissociated by heat. Particularly preferred anionic group neutralizers are trimethylamine and / or triethylamine.

  The storage stability of the aqueous polyurethane resin composition, the mechanical properties such as the strength of the coating film made of the aqueous polyurethane resin composition, the water resistance of the coating film made of the aqueous polyurethane resin composition, and the like, The amount used is preferably 0.5 to 2.0 equivalents, more preferably 0.8 to 1.5 equivalents, per equivalent of the anionic group.

(emulsifier)
Known surfactants can be used as the emulsifier. For example, cations such as common anionic surfactants and nonionic surfactants, primary amine salts, secondary amine salts, tertiary amine salts, quaternary amine salts, and pyridinium salts as surfactants An amphoteric surfactant such as a betaine type, a sulfate type and a sulfonic acid type can be used.

Examples of the anionic surfactant include alkyl sulfates such as sodium dodecyl sulfate, potassium dodecyl sulfate, and ammonium dodecyl sulfate; polyoxyethylene ether sulfates such as sodium dodecyl polyglycol ether sulfate and ammonium polyoxyethylene alkyl ether sulfate; Alkyl sulfonates such as ricinolate, alkali metal salt of sulfonated paraffin, ammonium salt of sulfonated paraffin; fatty acid salts such as sodium laurate, triethanolamine oleate, triethanolamine aviate; sodium benzene sulfonate, alkali phenol hydroxy Alkyl aryl sulfo such as alkali metal sulfate of ethylene It can be used over door class. Furthermore, high alkyl naphthalene sulfonate, naphthalene sulfonic acid formalin condensate, dialkyl sulfosuccinate, polyoxyethylene alkyl sulfate, polyoxyethylene alkyl aryl sulfate, polyoxyethylene ether phosphate, polyoxyethylene alkyl ether acetate Salts, N-acylamino acid salts, N-acylmethyltaurine salts and the like can also be used .

  As the nonionic surfactant, fatty acid partial esters of polyhydric alcohols such as sorbitan monolaurate and sorbitan monooleate, polyoxyethylene glycol fatty acid esters, and polyglycerin fatty acid esters can be used. Further, an ethylene oxide and / or propylene oxide adduct of an alcohol having 1 to 18 carbon atoms, an ethylene oxide and / or propylene oxide adduct of an alkyl phenol, an ethylene oxide and / or propylene oxide adduct of an alkylene glycol and / or an alkylene diamine, and the like. Can be used.

  The alcohol having 1 to 18 carbon atoms constituting the nonionic surfactant is, for example, methanol, ethanol, propanol, 2-propanol, butanol, 2-butanol, tert-butanol, amyl alcohol, isoamyl alcohol, tertiary amyl alcohol, Hexanol, octanol, decane alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol and the like.

  Examples of the alkylphenol include phenol, methylphenol, 2,4-di-tert-butylphenol, 2,5-di-tert-butylphenol, 3,5-di-tert-butylphenol, 4- (1,3-tetramethylbutyl) phenol, 4-isooctylphenol, 4-nonylphenol, 4-tertiary octylphenol, 4-dodecylphenol, 2- (3,5-dimethylheptyl) phenol, 4- (3,5-dimethylheptyl) phenol, naphthol, bisphenol A, and Bisphenol F and the like.

  The alkylene glycol is, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, , 4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, etc. is there.

  The alkylene diamine is, for example, a compound in which the alcoholic hydroxyl group of the alkylene glycol described above is substituted with an amino group. As the ethylene oxide and propylene oxide adducts, both random adducts and block adducts can be used.

  Examples of the cationic surfactant include lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, didecyl dimethyl ammonium chloride, lauryl benzyl dimethyl ammonium chloride, didecyl dimethyl ammonium chloride, alkyl pyridinium bromide and imidazolinium Laurate or the like can be used.

  Examples of the amphoteric surfactants include coconut oil fatty acid amide propyl dimethyl acetate betaine, lauryl dimethyl amino acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxymethylimidazolinium betaine, lauryl hydroxysulfobetaine, lauroylamidoethyl hydroxyethyl. Betaine-type amphoteric surfactants such as carboxymethyl betaine and metal salts of hydroxypropyl phosphate, amino acid-type amphoteric surfactants such as metal salts of β-laurylaminopropionic acid, sulfate-type amphoteric surfactants and sulfonic acid-type amphoteric surfactants Surfactants can be used.

  Nonionic surfactants are preferred as emulsifiers because they are easily available and inexpensive, and fatty acid partial esters of polyhydric alcohols such as sorbitan monolaurate and sorbitan monooleate; ethylene of alcohols having 1 to 18 carbon atoms Oxide and / or propylene oxide adducts are more preferred.

  The amount of the emulsifier is not particularly limited, but is preferably 0 to 30 parts by mass with respect to the total amount of the urethane prepolymer composition of 100 parts by mass from the viewpoint of the water resistance of the coating film composed of the aqueous polyurethane resin composition. , More preferably 0 to 20 parts by mass. When the water resistance of the coating film made of the aqueous polyurethane resin composition is particularly important, it is preferable to minimize the amount of the emulsifier used.

(Amount of urethane prepolymer (A) and (meth) acrylic compound (B))
The amount of the (meth) acrylic compound (B) in the urethane prepolymer composition is preferably 1 to 30 parts by mass, more preferably 3 to 25 parts by mass, particularly preferably 100 parts by mass of the urethane prepolymer (A). 5 to 20% by weight. When the amount of the (meth) acrylic compound (B) is less than 1 part by mass relative to 100 parts by mass of the urethane prepolymer (A), the adhesion to the photocurable resin is significantly reduced. When the amount is more than 30 parts by mass, the storage stability of the produced aqueous urethane resin composition is remarkably reduced.

(Aqueous polyurethane resin composition)
(Chain extender (C))
The water-based polyurethane resin composition of the present invention can be obtained by adding a chain extender (C) to a water-dispersed urethane prepolymer composition to convert the urethane prepolymer (A) contained in the urethane prepolymer composition into water. Obtained by chain extension.

  Examples of the chain extender (C) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol, triethylene glycol, and 2-butyl-2-ethyl. -1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1, 5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, Aliphatic such as 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol It is possible to use all. Furthermore, cycloaliphatic diols such as cyclohexane dimethanol and cyclohexane diol, low molecular weight diamines such as ethylene diamine, propylene diamine, hexamethylene diamine, tolylene diamine, piperazine, 2-methyl piperazine, polyoxypropylene diamine, polyoxyethylene diamine and the like Can also be used.

  As chain extenders (C), mensendiamine, isophoronediamine, norbornenediamine, aminoethylaminoethanol, bis (4-amino-3-methyldicyclohexyl) methane, diaminodicyclohexylmethane, bis (aminomethyl) cyclohexane, 3,9 Alicyclic diamines such as -bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro (5,5) undecane; m-xylenediamine, α- (m / p-aminophenyl) ethylamine , M-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodimethyldiphenylmethane, diaminodiethyldiphenylmethane, dimethylthiotoluenediamine, diethyltoluenediamine, α, α'-bis (4-aminophenyl) -p-diisopro Such Rubenzen, may be used a polyamine aromatic diamines. Further, succinic dihydrazide, adipic dihydrazide, sebacic dihydrazide, phthalic dihydrazide, 1,6-hexamethylenebis (N, N-dimethylsemicarbazide), 1,1,1 ′, 1′-tetramethyl-4,4 ′ Hydrazines such as-(methylene-di-para-phenylene) disemicarbazide, hydrated hydrazine, and water can also be used.

  From the viewpoints of availability and ease of reaction, as the chain extender (C), diamines, hydrazides, hydrazine hydrate, and water are preferable, and ethylenediamine, adipic dihydrazide, hydrated hydrazine, and water are particularly preferable.

  For the properties and the like of the coating film comprising the water-based polyurethane resin composition of the present invention, the amount of the chain extender (C) used is determined based on the isocyanate group equivalent contained in the urethane prepolymer (A) before the chain extension reaction. It is preferable that the ratio of the isocyanate-reactive group equivalents contained in (C) be set to an amount in the range of 0.1 to 1.0.

(Polyurethane resin)
The aqueous polyurethane resin composition of the present invention contains a specific polyurethane resin as a main component. The polyurethane resin contained in the aqueous polyurethane resin composition of the present invention is obtained by reacting a urethane prepolymer (A) obtained by reacting a polyol (a), a polyisocyanate (b), and an anionic group-introducing agent (c) with water. And a chain extended in the presence of the (meth) acrylic compound (B). The repeating units of the polyurethane resin contained in the aqueous polyurethane resin composition of the present invention are not uniform, and the structure and the number of repeating units are rich in variety. Therefore, the structure of the polyurethane resin contained in the aqueous polyurethane resin composition of the present invention is very complicated. For this reason, the structure of the polyurethane resin finally contained in the aqueous polyurethane resin composition of the present invention cannot be uniformly represented by a certain general formula. Therefore, in the present invention, the invention “aqueous polyurethane resin composition” containing such a polyurethane resin is referred to as “a polyol (a), a polyisocyanate (b), and an anionic group-introducing agent (c)”. The urethane prepolymer (A) and the (meth) acrylic compound (B) represented by the following general formulas (1) and / or (2) are reacted with the urethane prepolymer (A) and the urethane prepolymer (A). A urethane prepolymer composition containing the (meth) acrylic compound (B) in a ratio of 100: 1 to 30 (mass ratio) is prepared, and then the urethane prepolymer composition is added to the urethane prepolymer composition. Dispersing in water so that the concentration becomes 10 to 70% by mass, and further reacting the urethane prepolymer (A) in the obtained aqueous dispersion with the chain extender (C). It obtained, water-based polyurethane resin composition ", not forced to defined term.

(Additive)
Additives can be added to the aqueous polyurethane resin composition of the present invention as long as the effects of the present invention are not impaired. As the additive, various general resin additives can be used without limitation. Such additives include, for example, crosslinking agents, various weathering agents (hindered amine light stabilizers, ultraviolet absorbers and antioxidants), silane coupling agents that particularly enhance adhesion to substrates, colloidal silica or colloidal alumina. Inorganic colloid sols, tetraalkoxysilanes and polycondensates thereof, chelating agents, epoxy compounds, pigments, dyes, film-forming auxiliaries, curing agents, external crosslinking agents, viscosity modifiers, leveling agents, defoamers, anticoagulants, Radical scavenger, heat resistance imparting agent, inorganic or organic filler, plasticizer, lubricant, antistatic agent such as fluorine or siloxane, reinforcing agent, catalyst, thixotropic agent, wax, antifogging agent, antibacterial agent , A fungicide, a corrosion inhibitor, a rust inhibitor and the like can be used.

  Examples of the crosslinking agent include an adduct of urea, melamine, benzoguanamine and the like with formaldehyde, an amino resin comprising the adduct and an alkyl ether compound containing an alcohol unit having 1 to 6 carbon atoms, a polyfunctional epoxy compound; A polyfunctional isocyanate compound; a blocked isocyanate compound; a polyfunctional aziridine compound, and the like. Specific examples of these include oxazoline compounds, epoxy compounds, carbodiimide compounds, aziridine compounds, melamine compounds, and zinc complexes.

  Examples of the ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 5,5′-methylenebis (2-hydroxy-4-methoxybenzophenone). 2-hydroxybenzophenones; 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy-3, 5-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5 -Dicumylphenyl) benzotriazole, 2,2'-methylenebis (4- 3-octyl-6-benzotriazolylphenol), polyethylene glycol ester of 2- (2-hydroxy-3-tert-butyl-5-carboxyphenyl) benzotriazole, 2- [2-hydroxy-3- (2-acryloyl) Oxyethyl) -5-methylphenyl] benzotriazole, 2- [2-hydroxy-3- (2-methacryloyloxyethyl) -5-tert-butylphenyl] benzotriazole, 2- [2-hydroxy-3- (2 -Methacryloyloxyethyl) -5-tert-octylphenyl] benzotriazole, 2- [2-hydroxy-3- (2-methacryloyloxyethyl) -5-tert-butylphenyl] -5-chlorobenzotriazole, 2- [ 2-hydroxy-5- (2-methacryloyloxyethyl) phenyl] Zotriazole, 2- [2-hydroxy-3-tert-butyl-5- (2-methacryloyloxyethyl) phenyl] benzotriazole, 2- [2-hydroxy-3-tert-amyl-5- (2-methacryloyloxy) Ethyl) phenyl] benzotriazole, 2- [2-hydroxy-3-tert-butyl-5- (3-methacryloyloxypropyl) phenyl] -5-chlorobenzotriazole, 2- [2-hydroxy-4- (2- (Methacryloyloxymethyl) phenyl] benzotriazole, 2- [2-hydroxy-4- (3-methacryloyloxy-2-hydroxypropyl) phenyl] benzotriazole, 2- [2-hydroxy-4- (3-methacryloyloxypropyl) Phenyl] benzotriazole and the like. B) benzotriazoles; 2- (2-hydroxy-4-methoxyphenyl) -4,6-diphenyl-1,3,5-triazine, 2- (2-hydroxy-4-hexyloxyphenyl) -4,6 -Diphenyl-1,3,5-triazine, 2- (2-hydroxy-4-octoxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [ 2-hydroxy-4- (3-C12-C13 mixed alkoxy-2-hydroxypropoxy) phenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [2- Hydroxy-4- (2-acryloyloxyethoxy) phenyl] -4,6-bis (4-methylphenyl) -1,3,5-triazine, 2- (2,4-dihydroxy-3-allylphenyi) Ru) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-hexyloxyphenyl) -1, 2- (2-hydroxyphenyl) -4,6-diaryl-1,3,5-triazines such as 3,5-triazine; phenyl salicylate, resorcinol monobenzoate, 2,4-ditert-butylphenyl-3, 5-di-tert-butyl-4-hydroxybenzoate, octyl (3,5-di-tert-butyl-4-hydroxy) benzoate, dodecyl (3,5-di-tert-butyl-4-hydroxy) benzoate, tetradecyl (3 5-di-tert-butyl-4-hydroxy) benzoate, hexadecyl (3,5-di-tert-butyl-4-hydroxy) benzoate, octadecyl (3,5-di Benzoates such as 3-butyl-4-hydroxy) benzoate and behenyl (3,5-ditert-butyl-4-hydroxy) benzoate; 2-ethyl-2′-ethoxyoxanilide, 2-ethoxy-4′-dodecyl Substituted oxanilides such as oxanilide; cyanoacrylates such as ethyl-α-cyano-β, β-diphenylacrylate and methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate; Metal salts or metal chelates such as nickel or chromium salts or chelates are used.

  As the antioxidant, a phosphorus antioxidant, a phenolic antioxidant, and a sulfur antioxidant can be used. Examples of the phosphorus antioxidant include triphenyl phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tris (2,5-di-tert-butylphenyl) phosphite, and tris (nonylphenyl) Phosphite, tris (dinonylphenyl) phosphite, tris (mono, di-mixed nonylphenyl) phosphite, diphenylacid phosphite, 2,2′-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, Diphenyldecyl phosphite, diphenyloctyl phosphite, di (nonylphenyl) pentaerythritol diphosphite, phenyldiisodecyl phosphite, tributyl phosphite, tris (2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, Butyl acid phosphite, dilauryl acid phosphite, trilauryl trithiophosphite, bis (neopentyl glycol) -1,4-cyclohexanedimethyldiphosphite, bis (2,4-ditert-butylphenyl) pentaerythritol diphos Phyte, bis (2,5-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4-dicumyl) Phenyl) pentaerythritol diphosphite, distearylpentaerythritol diphosphite, tetra (mixed alkyl of C12 alkyl to C15 alkyl) -4,4′-isopropylidene diphenyl phosphite, bis [2,2′-methylenebis (4, 6-Zia Phenyl)]-isopropylidene diphenyl phosphite, tetratridecyl-4,4'-butylidenebis (2-tert-butyl-5-methylphenol) diphosphite, hexa (tridecyl) -1,1,3-tris (2-methyl -5-tert-butyl-4-hydroxyphenyl) butane triphosphite, tetrakis (2,4-ditert-butylphenyl) biphenylenediphosphonite, tris (2-[(2,4,7,9-tetrakis 3-butyldibenzo [d, f] [1,3,2] dioxaphosphepin-6-yl) oxy] ethyl) amine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10 -Oxide, tris (2-[(2,4,8,10-tetrakis-tert-butyldibenzo [d, f] [1,3,2] dioxaphos Epin-6-yl) oxy] ethyl amine, 2- (1,1-dimethylethyl) -6-methyl-4- [3-[[2,4,8,10-tetrakis (1,1-dimethylethyl)] Dibenzo [d, f] [1,3,2] dioxaphosphepin-6-yl] oxy] propyl] phenol and 2-butyl-2-ethylpropanediol-2,4,6-tri-tert-butylphenol Monophosphite or the like can be used.

Examples of the phenolic antioxidants include 2,6-di-tert-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, and stearyl (3,5-di-tert-butyl-4-). (Hydroxyphenyl) propionate, distearyl (3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate, tridecyl-3,5-di-tert-butyl-4-hydroxybenzylthioacetate, thiodiethylenebis [(3,5 -Di-tert-butyl-4-hydroxyphenyl) propionate], 4,4'-thiobis (6-tert-butyl-m-cresol), 2-octylthio-4,6-di (3,5-di-tert-butyl) -4-hydroxyphenoxy) -s-triazine, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), bis [3,3-bi (4-hydroxy-3-tert-butylphenyl) butylic acid] glycol ester, 4,4′-butylidenebis (2,6-ditertbutylphenol), 4,4′-butylidenebis (6-tert-butyl-3) -Methylphenol), 2,2'-ethylidenebis (4,6-di-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, bis [ 2-tert-butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl] terephthalate, 1,3,5-tris (2,6-dimethyl-3-hydroxy- 4-tert-butylbenzyl) isocyanurate, 1,3,5-tris (3,5-ditert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (3 5-di-tert-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, 1,3,5-tris [(3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxyethyl] isocyan isocyanurate, tetrakis [methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, 2-tert-butyl-4-methyl-6- (2-Accession Li Roiruokishi -3 -Tert-butyl-5-methylbenzyl) phenol, 3,9-bis [2- (3-tert-butyl-4-hydroxy-5-methylhydrocinnamoyloxy) -1,1-dimethylethyl] -2, 4,8,10-tetraoxaspiro [5.5] undecane, triethylene glycol bis [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propione G], and tocopherol.

  Examples of the sulfur-based antioxidants include dialkylthiodipropionates such as dilauryl, dimyristyl, myristylstearyl, and distearyl esters of thiodipropionic acid, and pentaerythritol tetra (β-dodecylmercaptopropionate). , Β-alkyl mercaptopropionate esters of polyols can be used.

  The amount of the weathering agent (hindered amine light stabilizer, ultraviolet absorber and antioxidant) to be used is preferably 0.001 to 10 parts by mass, more preferably 0.001 to 10 parts by mass, based on 100 parts by mass of the solid content of the aqueous polyurethane resin composition. It is 0.01 to 5 parts by mass. If the amount of the weathering agent is less than 0.001 part by mass with respect to 100 parts by mass of the solid content, a sufficient effect of addition may not be obtained. If the amount of the weathering agent is more than 10 parts by mass with respect to 100 parts by mass of the solid content, there is a possibility that the dispersion stability in water and the physical properties of the coating film may be adversely affected.

  As a method of adding these weathering agents, a method of adding to a polyol of a urethane raw material, a method of adding to a urethane prepolymer, a method of adding to a water phase at the time of aqueous dispersion of a urethane prepolymer, and a method of adding after water dispersion Either is acceptable. In terms of easy operation, a method of adding to the raw material polyol and a method of adding to the urethane prepolymer are preferable.

(Optical film)
The optical film is a laminate in which an optically anisotropic layer containing a liquid crystal compound is laminated on one side of a transparent support, and a hard coat layer is laminated on the opposite side. Such an optical film is, for example, a polarizer protective film, a retardation film, a viewing angle compensation film, a light diffusion film, a reflection film, an antireflection film, an antiglare film, a conductive film for a touch panel, a prism sheet, and the like. The aqueous polyurethane resin composition of the present invention can be used for such an optical film. The optical film to which the aqueous polyurethane resin composition of the present invention is applied is preferably a light diffusion film, a reflection film, or a prism sheet, and more preferably a prism sheet.

[Prism sheet]
The prism sheet is formed by attaching a photocurable resin such as an acrylic resin, urethane acrylate, or epoxy acrylate and a photocurable agent to a sheet-like plastic substrate. The water-based polyurethane resin composition of the present invention is suitable as a binder via a plastic substrate and a cured photocurable resin, that is, as an easily adhesive layer. Such a prism sheet can be manufactured in the following order. First, the aqueous polyurethane resin composition of the present invention is applied to a plastic substrate, and then a photocurable resin is laminated. Then, the photocurable resin is cured by irradiating the photocurable resin with light such as ultraviolet rays. Thus, the prism sheet can be obtained without the cured product peeling from the plastic substrate.

  As the plastic base material, a plastic base material on which a photocurable resin can be applied in a prism array can be used without limitation. For example, silicone resin, acrylic resin, epoxy resin, fluororesin, polystyrene resin, vinyl chloride resin, PC (polycarbonate), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), modified PPE (polyphenylene ether), PEN (polyethylene) Naphthalate), PET (polyethylene terephthalate), COP (cycloolefin polymer), TAC (triacetyl cellulose) and the like can be used. Inexpensive and easily available PET is preferred as the plastic substrate.

  The method for applying the aqueous polyurethane resin composition of the present invention to a plastic substrate is not particularly limited. As such a coating method, for example, a slit coater method such as a curtain flow coater method or a die coater method, a knife coater method, a roll coater method, or the like can be used.

  Examples of the photocuring agent include 2-2-dimethoxy-1,2-diphenylethan-1-one, benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl diphenyl sulfide, and tetramethylthiurammono. Sulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl -1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, bis (2,4 6-trimethylbenzo Le) - phenyl phosphine oxide, 2,4,6-trimethylbenzoyl - phenyl - may be a known photoinitiator such as phosphine oxide.

Hereinafter, the present invention will be described specifically with reference to Examples. In addition, in the following Examples and the like, the blending ratio (%) means a ratio based on mass unless otherwise specified.
[Example 1]
(Production and evaluation of water-based polyurethane resin composition U-1)
UH-CARBO200 (polycarbonate diol having a number average molecular weight of 2000, manufactured by Ube Industries, Ltd.), which is a polyol (a) as a polyol (a) in a 5-neck separable round bottom flask equipped with a Dimroth, stirring blade, and nitrogen line 12.7 g and 114.6 g of UH-CARBO50 (polycarbonate diol having a number average molecular weight of 500, manufactured by Ube Industries, Ltd.), which is a polyol (a-LM), were used as polyisocyanate (b) as 4,4-dicyclohexylmethane diisocyanate 213. 6.6 g, 41.2 g of dimethylolpropionic acid as an anionic group-introducing agent (c), and 163.5 g of methyl ethyl ketone (MEK) as a solvent. The acid value of the urethane prepolymer to be produced based on this formulation was determined to be 45.2 mgKOH / g. The raw material mixture was reacted at 80 ° C. for 6 hours to produce a urethane prepolymer containing MEK. When the acid value of the urethane prepolymer containing MEK was measured, it was 27.9 mgKOH / g.
The obtained urethane prepolymer was cooled to 60 ° C., and 31.1 g of triethylamine and 42.3 g of BPE-200 (ethoxylated bisphenol A dimethacrylate as (meth) acrylic compound (B), Shin-Nakamura Chemical Co., Ltd.) ) And stirred for 30 minutes to produce a urethane prepolymer composition. At this time, the content of BPE-200 is equivalent to 11.1 parts by mass based on 100 parts by mass of the urethane prepolymer.
To a 2 L disposable cup, 660 g of water at 40 ° C., 2.1 g of triethylamine, and 0.1 g of adecanate B-1016 (antifoaming agent, manufactured by ADEKA Corporation) were added, and the mixture was stirred for 5 minutes with a disper. 506.8 g of the prepolymer composition was added over 2 minutes and stirred for 30 minutes. Thereafter, 32.4 g of an aqueous solution of ethylenediamine / water = 1/3 (mass ratio) was added, and the mixture was further stirred for 30 minutes. Thereafter, the mixture was heated to 40 ° C., and MEK was removed under reduced pressure. Thus, an aqueous polyurethane resin composition U-1 of the present invention was obtained.

  On one side of the corona-treated PET film, the above-mentioned U-1 was applied using a bar coater so that the film thickness after drying was 1 μm, and was applied at 25 ° C. for 30 minutes and at 180 ° C. for 10 minutes. It was dried to obtain a test piece in which a urethane resin film was coated on one side of a PET film. Table 1 shows the evaluation results obtained by using this test piece to evaluate a moisture transparency test, an adhesion test with a UV curable resin, a warp test, and a blocking test by the following methods.

<Moisture transparency test>
The test piece was allowed to stand in a constant temperature and humidity chamber at 80 ° C. and 80% RH for 500 hours. Thereafter, the haze value of the test piece was measured with a haze meter (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.). The haze value of the PET film alone was also measured, and a value (ΔH) calculated by subtracting the haze value of the PET film alone from the haze value of the test piece was calculated. Using the calculated values, the moisture resistance of the test piece was evaluated as follows.
A: ΔH is less than 0.5.
B: ΔH is 0.5 or more and less than 1.0.
C: ΔH is 1.0 or more and less than 2.0.
D: ΔH is 2.0 or more.
<Adhesion test>
Adecaoptomer HC-211-9 (acrylic resin, manufactured by ADEKA Corporation) was coated on the surface of the test piece coated with the urethane resin film with a bar coder so that the cured film thickness was 3 μm. And applied. The coating film was dried at 80 ° C. for 1 minute, and irradiated with UV by a metal halide lamp (intensity: 600 mW / cm ² , cumulative light amount: 500 mJ / cm ² ) to cure the acrylic resin in the coating film.
The surface on which the cured acrylic resin adhered to the urethane resin film was cut into 100 squares using a cutter guide with a gap of 1 mm in accordance with JIS-K5600-5-6. The cut sample was observed for the adhesion of the cured acrylic resin, and the adhesion between the base film and the cured acrylic resin of each sample was evaluated as follows.
A: All the cut 100 squares adhere to the urethane resin.
B: 90 to 99 of the cut 100 squares adhere to the urethane resin.
C: Out of 100 cut cells, 80 to 89 cells adhere to the urethane resin.
D: Of the cut 100 squares, only 79 squares or less adhere to the urethane resin.
<Sledding test>
The urethane resin film to which the acrylic resin cured product prepared in the above adhesion test was attached was allowed to stand at 25 ° C. for 24 hours, and the degree of the warpage was evaluated as follows by visually observing the change in the shape of the film.
A: The shape of the film has not changed at all and can be used (pass *).
B: The film is slightly deformed but usable (pass *).
C: Unusable because the film is greatly warped.
(* A prism sheet in which a urethane resin film to which a cured acrylic resin is attached and a film such as PET becomes difficult to apply to a liquid crystal display or the like when it is greatly deflected. Passed.)
<Blocking test>
Two urethane resin films used in the above-mentioned moisture resistance transparency test were adhered to each other with the surfaces coated with the urethane resin films, and sandwiched using a glass plate and a buffer. A load of 10 kgf was applied to this and left standing for 24 hours in an atmosphere of 60 ° C. and 80% RH. Thereafter, the overlapped test pieces were peeled off, and the damaged state was visually observed. From the observation results, the blocking resistance of the urethane resin film was evaluated as follows.
A: The state is the same as before the blocking test, and the film is not damaged at all.
B: A part (less than 0.1 to 10%) of the entire area of the film is damaged.
C: 10% or more and less than 50% of the entire area of the film is damaged.
D: 50% or more of the entire area of the film is damaged.

[Examples 2 to 4]
(Production and evaluation of aqueous polyurethane resin compositions U-2, U-3, and U-4)
Water-based polyurethane resin compositions U-2, U-3, and U-4 were prepared in the same manner as in Example 1, except that the (meth) acrylic compound (B) was changed to the products shown in Table 1. Films using the aqueous polyurethane resin compositions U-2, U-3, and U-4 were evaluated from the same viewpoint as in Example 1. Table 1 shows the evaluation results.

[Example 5]
(Production and evaluation of aqueous polyurethane resin composition U-5)
54.6 g of UH-CARBO200 (same as above) and 54.6 g of UH-CARBO50 (same as above) were used as a polyol (a) in a 5-neck separable round bottom flask equipped with a Dimroth, stirring blade, and nitrogen line, and polyisocyanate (b). 214.0 g of 4,4-dicyclohexylmethane diisocyanate, 54.6 g of dimethylolpropionic acid as an anionic group-introducing agent (c), and 155.1 g of methyl ethyl ketone (MEK) as a solvent. The acid value of the urethane prepolymer to be produced based on this formulation was determined to be 60.5 mgKOH / g. The raw material mixture was reacted at 80 ° C. for 6 hours to produce a urethane prepolymer containing MEK. When the acid value of the urethane prepolymer containing MEK was measured, it was 36.8 mgKOH / g.
The obtained urethane prepolymer was cooled to 60 ° C., and 41.0 g of triethylamine, 46.2 g of BPE-200 as a (meth) acrylic compound (B) were added, and the mixture was stirred for 30 minutes to prepare a urethane prepolymer composition. Manufactured. At this time, the content of BPE-200 corresponds to 12.2 parts by mass with respect to 100 parts by mass of the urethane prepolymer (A).
To a 2 L disposable cup, 1170 g of water at 40 ° C., 2.9 g of triethylamine, and 0.1 g of adecanate B-1016 were added, and the mixture was stirred with a disper for 5 minutes. And stirred for 30 minutes. Thereafter, 32.4 g of an aqueous solution of ethylenediamine / water = 1/3 (mass ratio) was added, and the mixture was further stirred for 30 minutes. Thereafter, the mixture was heated to 40 ° C., and MEK was removed under reduced pressure to obtain an aqueous polyurethane resin composition U-5. A film using the water-based polyurethane resin composition U-5 was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[Example 6]
(Production and evaluation of aqueous polyurethane resin composition U-6)
An aqueous polyurethane resin composition U-6 was prepared in the same manner as in Example 1, except that 110.6 g of BPE-200 was used. A film using the water-based polyurethane resin U-6 was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[Example 7]
(Production and evaluation of aqueous polyurethane resin composition U-7)
An aqueous polyurethane resin composition U-7 was prepared in the same manner as in Example 1 except that 21.0 g of BPE-200 was used, and a moisture resistance test, an adhesion test with a UV curable resin, a warp test, and a blocking test were performed. Was evaluated. Table 1 shows the evaluation results.

[Comparative Example 1]
This is an example in which the (meth) acrylic compound (B) is changed.
(Production and evaluation of water-based polyurethane resin composition U-8 for comparison)
Aqueous polyurethane resin composition in the same manner as in Example 1 except that A-TMMT (pentaerythritol tetraacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) was used instead of BPE-200 as the (meth) acrylic compound (B). Was manufactured. Thus, a comparative aqueous polyurethane resin composition U-8 was obtained. A film using the water-based polyurethane resin U-8 was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[Comparative Example 2]
This is an example in which the (meth) acrylic compound (B) is changed.
(Production and evaluation of water-based polyurethane resin composition U-9 for comparison)
An aqueous polyurethane resin composition was produced in the same manner as in Comparative Example 1 except that 110.6 g of A-TMMT was used as the (meth) acrylic compound (B). Thus, a comparative aqueous polyurethane resin composition U-9 was obtained. A film using the water-based polyurethane resin U-9 was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[Comparative Example 3]
This is an example in which the (meth) acrylic compound (B) is changed.
(Production and evaluation of water-based polyurethane resin composition U-10 for comparison)
An aqueous polyurethane resin as in Example 1 except that AM-90G (methoxypolyethylene glycol # 400 acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) was used as the (meth) acrylic compound (B) instead of BPE-200. A composition was prepared. Thus, a comparative aqueous polyurethane resin composition U-10 was obtained. A film using the water-based polyurethane resin U-10 was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[Comparative Example 4]
This is an example in which the (meth) acrylic compound (B) was not used.
(Production and evaluation of water-based polyurethane resin composition U-11 for comparison)
An aqueous polyurethane resin composition was produced in the same manner as in Example 1 except that the (meth) acrylic compound (B) was not added to the urethane prepolymer. Thus, a comparative aqueous polyurethane resin composition U-11 was obtained. A film using the water-based polyurethane resin composition U-11 was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[Comparative Example 5]
This is an example in which the (meth) acrylic compound (B) is excessively mixed.
(Production and evaluation of water-based polyurethane resin composition U-12 for comparison)
A urethane prepolymer was produced under the same conditions as in Example 1. The obtained urethane prepolymer was cooled to 60 ° C., and 31.1 g of triethylamine, 190.7 g of BPE-200 as a (meth) acrylic compound (B) were added, and the mixture was stirred for 30 minutes to obtain a urethane prepolymer composition. Manufactured. At this time, the content of BPE-200 is equivalent to 50.0 parts by mass based on 100 parts by mass of the urethane prepolymer.
To a 2 L disposable cup, 660 g of water at 40 ° C., 2.1 g of triethylamine, and 0.1 g of adecanate B-1016 were added, and the mixture was stirred for 5 minutes with a disper. Then, 506.8 g of the urethane prepolymer composition was added for 2 minutes. And stirred for 30 minutes. Thereafter, 32.4 g of an aqueous solution of ethylenediamine / water = 1/3 (mass ratio) was added, and the mixture was further stirred for 30 minutes. Thus, a comparative aqueous polyurethane resin composition U-12 was obtained. When the aqueous polyurethane resin composition U-12 was visually confirmed, it was found that some components were separated. The component separated by IR analysis was found to be BPE-200. With respect to the water-based polyurethane resin composition U-12, no evaluation was made on the moisture transparency test, the adhesion test with the UV curable resin, the warp test, and the blocking test.

(Notes in Table 1)
** 1: ABE-300: ethoxylated bisphenol A diacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.
** 2: EA-0200: In the above formula (1), R ¹ and R ² are hydrogen atoms, R ³ and R ⁴ are ethylene groups, and R ⁵ is a diamine represented by the above formula (3-7). Acrylate compound, manufactured by Osaka Gas Chemical Co., Ltd.
** 3: A-9300S: Ethoxylated isocyanuric acid triacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.

  As shown in the evaluation results in Table 1, the comparative water-based polyurethane composition U-11 in which the (meth) acrylic compound (B) was not blended had poor adhesion to the photocurable resin and was not suitable for optical film applications. The comparative water-based polyurethane compositions U-8, U-9, and U-10, which did not use the predetermined compound of the present invention as the (meth) acrylic compound (B), have moisture-resistant transparency, adhesion, warpage, and blocking resistance. In any one or more items, the performance is significantly inferior and is not suitable for optical film applications. The comparative aqueous polyurethane composition U-12 containing an excessive amount of the (meth) acrylic compound (B) had its components separated, and it was difficult to process the film itself. On the other hand, U-1, U-2, U-3 and U-4 corresponding to the water-based polyurethane composition which is an example of the present invention have all of moisture resistance, transparency, adhesion, warpage, and blocking resistance. A pass rating has been obtained.

It was confirmed that the urethane film using the water-based polyurethane resin composition of the present invention was excellent in moisture resistance and transparency, and had good adhesion to the cured acrylic resin. Furthermore, it was confirmed that the film obtained by laminating the cured product of the PET film and the acrylic resin through the layer of the aqueous polyurethane resin composition of the present invention showed little warpage over time. It was also confirmed that there was little blocking when the films made of the aqueous polyurethane resin composition of the present invention were stacked. Water-based urethane resin composition of the present invention as described above, optical transparency, heat resistance, adhesion to a polyester base film and a photocurable resin, any of the blocking resistance is good.

The water-based polyurethane resin composition of the present invention having good adhesion to the cured acrylic resin is useful as a film for easy adhesion that functions as a binder between the photocurable resin used in the prism sheet and the PET film. Since the water-based polyurethane resin composition of the present invention also has good moisture resistance and transparency, it is considered that an optical film using the water-based polyurethane resin composition of the present invention as a binder exhibits good performance while maintaining luminance. Further, the films made of the aqueous polyurethane resin composition of the present invention have reduced blocking, and can be superposed. Therefore, the workability of the film comprising the aqueous polyurethane resin composition of the present invention is good. The aqueous polyurethane resin composition of the present invention can be applied to various optical films used for displays such as liquid crystal televisions and personal computers. The present invention is extremely useful in industry.

Claims (8)

A urethane prepolymer (A) obtained by reacting a polyol (a), a polyisocyanate (b), and an anionic group-introducing agent (c) with the following general formula (1) and / or general formula (2) Urethane prepolymer containing a (meth) acrylic compound (B) such that the ratio of the urethane prepolymer (A) to the (meth) acrylic compound (B) is 100: 1 to 30 (mass ratio). A composition is prepared, and then the urethane prepolymer composition is dispersed in water such that the concentration of the urethane prepolymer composition is 10 to 70% by mass. Further, the urethane prepolymer in the obtained aqueous dispersion is further dispersed. An aqueous polyurethane resin composition for an optical film obtained by reacting (A) with a chain extender (C).

(R ¹ and R ² each independently represent a hydrogen atom or a methyl group. R ³ and R ⁴ each independently represent a divalent hydrocarbon group having 2 to 4 carbon atoms. R ⁵ represents a sulfur atom or a divalent hydrocarbon group. Wherein m and n each represent an integer of 0 to 10.)

(R ⁶ , R ⁷ , and R ⁸ each independently represent a divalent hydrocarbon group having 2 to 10 carbon atoms. R ⁹ , R ¹⁰ , and R ¹¹ each independently represent a hydrogen atom or a methyl group.) The (meth) acrylic compound (B) is a compound represented by the general formula (1), wherein R ⁵ in the general formula (1) is a single bond, a methylene group, —CH (CH ₃ ) —, —C _{(CH 3) 2} -, the following general formula (3-1) to be selected from any of the functional group represented by (3-7), the optical film for aqueous polyurethane resin composition of claim 1.

(M represents an integer of 4 to 12.) The polyol (a) is at least one or more selected from a polyester polyol (a1), a polycarbonate diol (a2), a polyether polyol (a3), and a polyol (a4) having a number average molecular weight of less than 200. 3. The aqueous polyurethane resin composition for an optical film according to item 2. The aqueous polyurethane resin composition for an optical film according to any one of claims 1 to 3, wherein the polyol (a) is at least one selected from polycarbonate diol (a2). The said polyol (a) consists of high molecular weight polyol (a-HM) whose number average molecular weight is 1500-5000, and low molecular weight polyol (a-LM) whose number average molecular weight is 300-1000. The aqueous polyurethane resin composition for an optical film according to any one of items 1 to 4. The aqueous polyurethane resin composition for an optical film according to any one of claims 1 to 5, wherein the urethane prepolymer (A) has an acid value in a range of 30 to 80 mgKOH / g. An optical film comprising the aqueous polyurethane resin composition for an optical film according to claim 1. A prism sheet comprising a layer made of the aqueous polyurethane resin composition for an optical film according to claim 1, a base film, and a layer of a cured product of a photocurable resin.