UV-curable resin composition for light-diffusing film, and light-diffusing film

Abstract

To provide a UV-curable resin composition for a light-diffusing film and a light-diffusing film, which have excellent light diffusibility and mechanical properties.SOLUTION: A UV-curable resin composition for a light-diffusing film comprises (A) a polymer having no polymerizable ethylenically unsaturated group, (B) a urethane (meth)acrylate, (C) a (meth)acrylate monomer, and (D) a photoradical polymerization initiator, where the component (A) has a glass transition temperature of 25°C or higher and a weight-average molecular weight from 2,000 to 20,000 inclusive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin composition for a light diffusion film and a light diffusion film, and more particularly to a resin composition for a light diffusion film that can give a light diffusion film having high light diffusion performance and excellent mechanical properties, and a light diffusion film obtained by curing the same. [Background technology]

[0002] Light diffusion films (light control films) that scatter incident light within a specific angle range, exhibiting opacity, and transmit incident light within other specific angle ranges, exhibiting transparency, are used, for example, in applications such as viewing angle control films used in window glass and cash dispenser touch panels to protect privacy, and optical film applications such as viewing angle expansion films or brightness enhancement films for flat panel displays.

[0003] Known examples of such light diffusion films include those obtained by irradiating a film-like composition containing a material with a high refractive index, such as 2-hydroxy-3-phenoxypropyl acrylate, and a material with a low refractive index, such as polyether urethane (meth)acrylate, with ultraviolet light from a specific direction, thereby curing the composition and simultaneously separating it into layers with a regular structure (Patent Document 1).

[0004] However, compositions consisting only of urethane (meth)acrylate and (meth)acrylic acid ester compounds have a very low elastic modulus after UV curing and poor mechanical properties. Therefore, when pressure or stress is applied during the production of light diffusion films, when laminating them on products such as displays, or after they are installed on products such as displays, the regular structure formed inside the film is destroyed, resulting in the problem of not being able to achieve the desired diffusion properties.

[0005] Therefore, for the purpose of improving mechanical properties, the use of a polyfunctional (meth)acrylic acid ester compound in the composition has also been investigated (Patent Document 2).

[0006] However, when a polyfunctional (meth)acrylic acid ester compound is used to improve mechanical properties, the elongation of the light diffusion film is lost due to the increased crosslink density, making the light diffusion film more susceptible to breakage when force is applied in the direction of stretching. Furthermore, the increased crosslink density also hinders layer separation between the high refractive index component and the low refractive index component during UV curing, which tends to reduce light diffusion performance. Therefore, when a polyfunctional (meth)acrylic acid ester compound is used, it is difficult to achieve both the desired mechanical properties and light diffusion performance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 3211381 [Patent Document 2] Patent No. 7414397 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultraviolet-curable resin composition for a light diffusion film, which has excellent light diffusing properties and mechanical properties, and a light diffusion film. [Means for solving the problem]

[0009] That is, the present invention relates to the following [1] to [4]. In this application, "(numerical value 1) to (numerical value 2)" indicates that the upper and lower limits are included. Also, the (meth)acrylic group means a methacrylic group and / or an acrylic group, and the (meth)acrylate means a methacrylate and / or an acrylate. [1] (A) a polymer having no polymerizable ethylenically unsaturated group, (B) a urethane (meth)acrylate, (C) a (meth)acrylate monomer, and (D) a photoradical polymerization initiator; The component (A) is an ultraviolet-curable resin composition for a light-diffusing film, which has a glass transition temperature of 25° C. or higher and a weight-average molecular weight of 2,000 or higher and 20,000 or lower. [2] The ultraviolet-curable resin composition for a light-diffusing film according to the above item [1], wherein the content of the component (A) is 25% by weight or less based on the total amount of the ultraviolet-curable resin composition for a light-diffusing film. [3] The ultraviolet-curable resin composition for a light diffusion film according to the above item [1] or [2], wherein the component (A) is a polymer of a (meth)acrylic component having one or more functional groups selected from the group consisting of a hydroxyl group, an epoxy group, and a carboxyl group. [4] A light diffusion film obtained by ultraviolet curing the ultraviolet-curable resin composition for a light diffusion film according to any one of the above items [1] to [3]. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an ultraviolet-curable resin composition for a light diffusion film and a light diffusion film which are excellent in light diffusing properties and mechanical properties. [Brief explanation of the drawings]

[0011] [Figure 1] Micrograph of the cured film from the UV-irradiated side of Example 6 DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention (hereinafter also referred to as "the present embodiment") will be described in further detail.

[0013] The ultraviolet-curable resin composition for a light diffusion film of this embodiment (also simply referred to as the "resin composition") contains (A) a polymer having no polymerizable ethylenically unsaturated group, (B) a urethane (meth)acrylate, (C) a (meth)acrylate monomer, and (D) a photoradical polymerization initiator, and has excellent light diffusion properties and mechanical properties.

[0014] The light diffusion property can be evaluated by a cured film appearance test or a haze value test shown in the Examples below. Specifically, it is preferable that the cured film is transparent and that the light transmittance changes depending on the observation angle. Furthermore, a high haze value indicates high light diffusion property, and a haze value of 10 to 50% is preferable.

[0015] The mechanical properties can be evaluated using a universal testing machine as described in the Examples below, and a high modulus of elasticity and a high elongation are excellent. Specifically, the modulus of elasticity is preferably 500 to 2500 MPa. The elongation is preferably 10 to 60%.

[0016] [(A) Polymer Having No Polymerizable Ethylenically Unsaturated Group] The resin composition of the present embodiment contains, as component (A), a polymer that does not have a polymerizable ethylenically unsaturated group (also simply referred to as "component (A)"). The polymerizable ethylenically unsaturated group refers to an ethylenically unsaturated group such as a (meth)acrylic group, a vinyl group, an allyl group, or a maleimide group, which is polymerized by ultraviolet irradiation, heating, or the like.

[0017] The glass transition temperature (Tg) of the component (A) material alone is preferably 25°C or higher, more preferably 50°C or higher. The upper limit of Tg is preferably 120°C. A Tg of 25°C or higher increases the elastic modulus of the UV-curable resin composition for light diffusion films, improving its mechanical properties. Furthermore, because it does not react with the ethylenically unsaturated group-containing material in the resin composition, layer separation between the high refractive index component and the low refractive index component during UV curing is not inhibited, resulting in a film with excellent light diffusion performance. Tg can be determined by measuring the inflection point when the baseline shifts due to a change in heat capacity in a differential scanning calorimeter (DSC) at a heating rate of 5°C / min using aluminum of the same weight as the measurement sample as the reference sample.

[0018] The weight-average molecular weight (Mw) of Component A is preferably 2,000 or more and 20,000 or less, and more preferably 8,000 or more and 15,000 or less. If Mw is less than 2,000, migration within the film increases, and Component A may bleed out onto the film surface in high-temperature environments, impairing the appearance. If Mw is greater than 20,000, compatibility with other materials in the resin composition may be poor, causing the resin composition liquid to become cloudy. Furthermore, excessive layer separation may cause the entire cured film to become cloudy, resulting in a loss of transparency. The weight-average molecular weight (Mw) can be determined by gel permeation chromatography (GPC), and for commercially available products, the catalog value may be used.

[0019] The method for producing component (A) is not particularly limited, but it can be obtained, for example, by polymerizing a monomer compound having an ethylenically unsaturated group, such as a (meth)acrylic monomer or styrene. Furthermore, component (A) preferably has a hydrophilic functional group, such as a hydroxyl group, an epoxy group, or a carboxyl group. Compounds containing aromatic rings are suitable for the high refractive index component, which forms the domain that exhibits light diffusion properties, due to their high electron density, and tend to be highly hydrophobic. Therefore, compounds with hydrophilic functional groups are suitable for efficiently separating and growing the domains of the high refractive index component.

[0020] Commercially available products of component (A) include Toagosei's solvent-free acrylic polymers ARUFON UH-2170 (Tg 60°C, Mw 14,000, containing hydroxyl groups), UC-3080 (Tg 133°C, Mw 14,000, containing carboxyl groups), UG-4035 (Tg 52°C, Mw 11,000, containing epoxy groups), UG-4040 (Tg 63°C, Mw 11,000, containing epoxy groups), and UG-4070 (Tg point 58°C, Mw 9,700, containing epoxy groups).

[0021] [(B) Urethane (meth)acrylate] The resin composition of this embodiment contains a urethane (meth)acrylate (also simply referred to as "component (B)") as component (B). Component (B) can be obtained by reacting (a) a polyol, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate in a conventional manner, and a catalyst such as a tin compound may be used as needed. In the synthesis of component (B), 1 equivalent of the hydroxyl group of component (a) is preferably reacted with 1.1 to 2.0 equivalents, and particularly preferably 1.3 to 2.0 equivalents, of the isocyanate group of component (b). The reaction temperature is preferably room temperature (25°C) to 100°C. It is preferable to react 0.95 to 1.1 equivalents of hydroxyl groups in component (c) with 1 equivalent of isocyanate groups in the reaction product of component (a) and component (b). The reaction temperature is preferably room temperature (25°C) to 100°C.

[0022] Specific examples of (a) polyols include tricyclodecane dimethanol, hydrogenated polybutadiene polyol, dimer diol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-icosanediol, and 1-methyl-1,8-octanediol. Examples of the diols (a-1) include 2-methyl-1,8-octanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, cyclohexane-1,4-dimethanol, polyethylene glycol, polypropylene glycol, bisphenol A poly(n≒2-20)ethoxydiol, and bisphenol A poly(n≒2-20)propoxydiol, and polyester polyols (a-2) which are reaction products of these diols (a-1) with dibasic acids or their anhydrides (e.g., succinic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, isophthalic acid, terephthalic acid, phthalic acid, or anhydrides thereof). Preferred are polyester polyols and polyols having an aromatic ring, and particularly preferred are polyester polyols having an aromatic ring. Examples of the aromatic ring include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthroline ring; and aromatic heterocycles such as a furan ring, a pyrrole ring, a thiophene ring, a pyridine ring, a thiazole ring, and a benzothiazole ring; and preferably a benzene ring or a naphthalene ring. The component (a) may be used alone or in combination of two or more.

[0023] Specific examples of (b) organic polyisocyanates include tolylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-cyclohexylmethane diisocyanate, xylylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, trimethylhexamethylene diisocyanate, dimeryl diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-diphenylene diisocyanate, etc. Preferred examples include tolylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0024] Specific examples of (c) hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,4-butanediol (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, an ε-caprolactone adduct of 2-hydroxyethyl (meth)acrylate, and 2-hydroxy-3-phenyloxypropyl (meth)acrylate. Preferred examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[0025] The lower limit of the weight average molecular weight of the urethane (meth)acrylate in terms of polystyrene measured by GPC is preferably 1000 or more, more preferably 2000 or more, particularly preferably 3000 or more, and most preferably 4000 or more. The upper limit is preferably 10000 or less, more preferably 8000 or less, particularly preferably 7000 or less, and most preferably 6000 or less.

[0026] [(C) (Meth)acrylate Monomer] The resin composition of the present embodiment contains a (meth)acrylate monomer (also simply referred to as "component (C)") as component (C). The (meth)acrylate monomer is a monomer having one or more (meth)acryloyl groups in the molecule.

[0027] Specific examples of component (C) include N-acryloyloxyethylhexahydrophthalimide, acryloylmorpholine, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexane-1,4-dimethanol mono(meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenoxyethyl (meth)acrylate, phenylpolyethoxy (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, orthophenylphenoxyacrylate, p -Cumylphenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, tribromophenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, tricyclodecane dimethanol di (Meth)acrylate, bisphenol A polyethoxydi(meth)acrylate, bisphenol A polypropoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dioxane glycol diacrylate, tris(acryloxyethyl)isocyanurate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate )acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ester diacrylate of neopentyl glycol and hydroxypivalic acid, and diacrylate of an ε-caprolactone adduct of an ester of neopentyl glycol and hydroxypivalic acid.

[0028] [(D) Photoradical polymerization initiator] The resin composition of this embodiment contains a photoradical polymerization initiator (also simply referred to as "component (D)") as component (D). The photoradical polymerization initiator is not particularly limited as long as it is a compound that generates radicals or acids and initiates a chain polymerization reaction when irradiated with ultraviolet light or visible light. Examples of the photoradical polymerization initiator include benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, diethylthioxanthone, benzophenone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, camphorquinone, 9-fluorenone, and diphenyl disulfide. Specific examples include IRGACURE RTM 651, 184, 2959, 127, 907, 369, 379EG, 819, 784, 754, 500, OXE01, OXE02, OXE03, OXE04, DAROCURE RTM 1173, LUCIRIN RTM TPO (both manufactured by BASF), Seikuol RTM Z, BZ, BEE, BIP, BBI (all manufactured by Seiko Chemical Co., Ltd.), etc. The content of component (D) is preferably 0.1 to 10 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 5 to 10 parts by mass, based on the total amount of the resin composition.

[0029] The resin composition of the present embodiment may contain other materials as shown below, in addition to the components (A) to (D), as needed.

[0030] [Curable compound] The resin composition of the present embodiment may contain a curable compound other than components (B) and (C). The curable compound is not particularly limited as long as it is a compound that is cured by light, heat, or the like, and examples thereof include epoxy resins, epoxy (meth)acrylates, and polybutadiene compounds having a (meth)acrylic group in the molecule.

[0031] [Epoxy resin] The epoxy resin is not particularly limited, but is preferably a bifunctional or higher functional epoxy resin, such as dimer acid-modified epoxy resin, resorcinol diglycidyl ether, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, bisphenol F novolac epoxy resin, alicyclic epoxy resin, aliphatic linear epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, hydantoin epoxy resin, isocyanurate epoxy resin, phenol novolac epoxy resin having a triphenolmethane skeleton, and diglycidyl ethers of bifunctional phenols such as catechol and resorcinol, diglycidyl ethers of bifunctional alcohols, and their halides and hydrogenated derivatives. Of these, bisphenol A epoxy resin and resorcinol diglycidyl ether are preferred from the viewpoint of liquid crystal contamination resistance.

[0032] [Epoxy (meth)acrylate] Epoxy (meth)acrylates are obtained by known methods by reacting epoxy resins with (meth)acrylic acid. The epoxy resins used as raw materials are not particularly limited, but are preferably bifunctional or higher functional epoxy resins. Examples include resorcinol diglycidyl ether, bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A novolac epoxy resins, bisphenol F novolac epoxy resins, alicyclic epoxy resins, aliphatic linear epoxy resins, glycidyl ester epoxy resins, glycidyl amine epoxy resins, hydantoin epoxy resins, isocyanurate epoxy resins, phenol novolac epoxy resins having a triphenolmethane skeleton, and diglycidyl ethers of bifunctional phenols such as catechol and resorcinol, diglycidyl ethers of bifunctional alcohols, and their halides and hydrogenated derivatives. Bisphenol A epoxy resins and resorcinol diglycidyl ethers are preferred. The ratio of epoxy groups to (meth)acryloyl groups is not limited and may be appropriately selected from the viewpoint of process suitability.

[0033] [Polybutadiene compound having a (meth)acrylic group in the molecule] Polybutadiene compounds having a (meth)acrylic group in the molecule are commercially available, for example, as TEAI-1000 and TE-2000 manufactured by Nippon Soda Co., Ltd. The lower limit of the number average molecular weight of these polybutadiene compounds having a (meth)acrylic group in the molecule is preferably 500, more preferably 750, and particularly preferably 1000. From the viewpoint of handleability, the upper limit of the number average molecular weight is preferably 10000, more preferably 8000, and particularly preferably 6000.

[0034] [Silane coupling agents] The resin composition of this embodiment may contain a silane coupling agent. Examples of silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, and 3-chloropropyltrimethoxysilane. These silane coupling agents are sold by Shin-Etsu Chemical Co., Ltd. and other companies under the names KBM series and KBE series, and are therefore readily available on the market. When a silane coupling agent is used, it is preferably contained in an amount of 0.05 to 3 parts by mass based on the total amount of the resin composition.

[0035] [Compounds containing thiol groups] The resin composition of the present embodiment may contain a compound having a thiol group. Examples of the compound having a thiol group include methanedithiol, 1,2-dimercaptoethane, 1,2-dimercaptopropane, 2,2-dimercaptopropane, 1,3-dimercaptopropane, 1,2,3-trimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, bis(2-mercaptoethyl)sulfide, 1,2-bis(2-mercaptoethylthio)ethane, 1,5-dimercapto-3-oxapentane, and 1,8-dimercapto-3,6-dioxapentane. saoctane, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl-1,4-dimercaptobutane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 1,1,1-tris(mercaptomethyl)propane, tetrakis(mercaptomethyl)methane, ethylene glycol Lithium bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), 1,4-butanediol bis(2-mercaptoacetate), 1,4-butanediol bis(3-mercaptopropionate), trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate) Dipentaerythritol hexakis(3-mercaptopropionate), dipentaerythritol hexakis(2-mercaptoacetate), 1,2-dimercaptobenzene, 1,3-dimercapto-2-propanol, 2,3-dimercapto-1-propanol, 1,2-dimercapto-1,3-butanediol, hydroxyethyl-tris(mercaptoethylthiomethyl)methane, hydroxyethylthiomethyl-tris(mercaptoethylthio)methane, ethylene glycol bis(3-mercaptopropionate), propylene glycol bis(3-mercaptopropionate), butanediol bis(3-mercaptopropionate), octanediol bis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), Ethylene glycol bis(4-mercaptobutyrate), propylene glycol bis(4-mercaptobutyrate), butanediol bis(4-mercaptobutyrate), octanediol bis(4-mercaptobutyrate), trimethylolpropane tris(4-mercaptobutyrate), pentaerythritol tetrakis(4-mercaptobutyrate), ethylene glycol bis(6-mercaptovalerate), propylene glycol bis(6-mercaptovalerate) , butanediol bis(6-mercaptovalerate), octanediol bis(6-mercaptovalerate), trimethylolpropane tris(6-mercaptovalerate), pentaerythritol tetrakis(6-mercaptovalerate), 1,6-hexanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 4,4'-bis(mercaptomethyl)phenyl sulfide, 2,4'-bis(mercaptomethyl)phenyl sulfide, 2,4,4'-tri( mercaptomethyl)phenyl sulfide, 2,2',4,4'-tetra(mercaptomethyl)phenyl sulfide, 1,3,5-tris[2-(3-mercaptopropionyloxy)ethyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, polysulfide polymers, etc., which may be used alone or in combination of two or more. Among these, preferred are trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), 1,3,5-tris[2-(3-mercaptopropionyloxy)ethyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(3-mercapto Preferred are 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and pentaerythritol tetrakis(3-mercaptobutyrate), and more preferred are 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and pentaerythritol tetrakis(3-mercaptobutyrate), which have a secondary thiol structure.

[0036] The compound having a thiol group may be produced by a known method, or a commercially available compound may be used. RTM PE1, BD1, NR1, trimethylolpropane tris(3-mercaptobutyrate), trimethylolethane tris(3-mercaptobutyrate) (all manufactured by Resonac Co., Ltd.), polythiol RTM 340M (manufactured by Toray Fine Chemicals Co., Ltd.), pentaerythritol tetrakis(3-mercaptopropionate) (manufactured by SC Organic Chemicals Co., Ltd.), and the like.

[0037] [Thermal radical polymerization initiator] The resin composition of this embodiment contains a thermal radical polymerization initiator, which can improve the curing speed and curability. The thermal radical polymerization initiator is not particularly limited as long as it is a compound that generates radicals upon heating and initiates a chain polymerization reaction. Examples of the thermal radical polymerization initiator include organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, and benzopinacol, and benzopinacol is preferably used. For example, an organic peroxide such as Kayamec RTM A, M, R, L, LH, SP-30C, Perkadox CH-50L, BC-FF, Kadox B-40ES, Perkadox 14, Trigonox RTM 22-70E, 23-C70, 121, 121-50E, 121-LS50E, 21-LS50E, 42, 42LS, Kayaester RTM P-70, TMPO-70, CND-C70, OO-50E, AN, Kayabutyl RTM B, Percadox 16, Kayacarvone RTM BIC-75, AIC-75 (manufactured by Kayaku Akzo Co., Ltd.), Permec RTM N, H, S, F, D, G, Perhexa RTM H,HC,TMH,C,V,22,MC,Percure RTM AH, AL, HB, Perbutyl RTM H, C, ND, L, Park Mill RTM H., D., Parloyle RTM IB, IPP, Perocta RTM ND (manufactured by NOF Corporation) and other products are available commercially.

[0038] Furthermore, commercially available azo compounds include VA-044, 086, V-070, VPE-0201, and VSP-1001 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0039] The content of the thermal radical polymerization initiator is preferably 0.0001 to 10 parts by mass, more preferably 0.0005 to 5 parts by mass, and particularly preferably 0.001 to 3 parts by mass, based on the total amount of the resin composition.

[0040] [Radical polymerization inhibitor]The resin composition of this embodiment may contain a radical polymerization inhibitor. The radical polymerization inhibitor is not particularly limited as long as it is a compound that reacts with radicals generated from a photoradical polymerization initiator, a thermal radical polymerization initiator, or the like to prevent polymerization. Examples of the radical polymerization inhibitor include quinones, piperidines, hindered phenols, and nitroso compounds. Specific examples include naphthoquinone, 2-hydroxynaphthoquinone, 2-methylnaphthoquinone, 2-methoxynaphthoquinone, 2,2,6,6-tetramethylpiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-methoxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-phenoxypiperidine-1-oxyl, and hydroquinone. , 2-methylhydroquinone, 2-methoxyhydroquinone, parabenzoquinone, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butylcresol, stearyl β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol) ol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl], 2,4,8,10-tetraoxaspiro[5,5]undecane, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenylpropionate)methane], 1,3,5-trimethyl- Examples of suitable antibacterial agents include, but are not limited to, this(3',5'-di-t-butyl-4'-hydroxybenzyl)-sec-triazine-2,4,6-(1H,3H,5H)trione, paramethoxyphenol, 4-methoxy-1-naphthol, thiodiphenylamine, aluminum salt of N-nitrosophenylhydroxyamine, and Adeka STAB LA-81 (trade name) and Adeka STAB LA-82 (trade name) (manufactured by Adeka Corporation).Of these, naphthoquinone-based, hydroquinone-based, nitroso-based, and piperazine-based radical polymerization inhibitors are preferred, naphthoquinone, 2-hydroxynaphthoquinone, hydroquinone, 2,6-di-tert-butyl-p-cresol, and Polystop 7300P (manufactured by Hakuto Co., Ltd.) are more preferred, and Polystop 7300P (manufactured by Hakuto Co., Ltd.) is most preferred.

[0041] The content of the radical polymerization inhibitor is preferably 0.0001 to 1 part by mass, more preferably 0.001 to 0.5 parts by mass, and particularly preferably 0.01 to 0.2 parts by mass, based on the total amount of the resin composition.

[0042] The resin composition of the present embodiment may further contain additives such as a heat curing agent, a curing accelerator, an organic filler, an inorganic filler, a pigment, a leveling agent, an antifoaming agent, a solvent, etc. These additives preferably have low staining properties to the charge transport layer.

[0043] The resin composition of this embodiment can be obtained by the following method, but is not limited to the following method. Components (A) to (D), and optionally other materials, are added and mixed under heat. If any materials are not suitable for hot mixing, they may be cooled and mixed. After mixing, filtration may be performed to remove impurities, if necessary. [Example]

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0045] [Synthesis Example 1] A flask equipped with a thermometer, condenser, and stirrer was charged with 657.7 g of polypropylene glycol polyether polyol (AGC Corporation's Exenol 3020, hydroxyl value 35.8 mg KOH / g), 49.0 g of hexamethylene diisocyanate (Wanka Chemical Co., Ltd.'s Wannate HDI, molecular weight 168.2), and 0.1 g of tin octoate (catalyst), and the mixture was reacted at 80°C. The isocyanate content at this time was determined by adding excess amine and back titrating with hydrochloric acid, and it was confirmed that the value was within a range of plus or minus 2% of the residual isocyanate amount calculated from the calculated value. Next, 0.5 g of dibutylhydroxytoluene (polymerization inhibitor) and 341.8 g of dipentaerythritol hexaacrylate (KAYARAD DPHA manufactured by Nippon Kayaku Co., Ltd., hydroxyl value 49.0 mgKOH / g) were added, and the mixture was stirred at 80°C. The absorption spectrum of the isocyanate group (at 2280 cm) was measured by infrared absorption spectroscopy. -1 The reaction was continued until the methyl group disappeared, yielding a urethane acrylate having a weight-average molecular weight of 19,700.

[0046] [Synthesis Example 2] A flask equipped with a thermometer, condenser, and stirrer was charged with 814.3 g of polypropylene glycol polyether polyol (AGC Corporation, Exenol 3020, hydroxyl value 35.8 mg KOH / g), 115.5 g of isophorone diisocyanate (Wanka Chemical Co., Ltd., Wannate IPDI, molecular weight 222.3), and 0.1 g of stannous octoate (catalyst), and the mixture was allowed to react at 80 °C. The isocyanate content was determined by adding excess amine and back titrating with hydrochloric acid. The value was confirmed to be within ±2% of the residual isocyanate content calculated from the calculated value. Next, 0.5 g of dibutylhydroxytoluene (polymerization inhibitor) and 69.6 g of 2-hydroxyethyl methacrylate (molecular weight 130.1) were added, and the mixture was stirred at 80 °C. The isocyanate group absorption spectrum (at 2280 cm) was measured by infrared absorption spectroscopy. -1 The reaction was continued until the methyl group disappeared, yielding a urethane methacrylate having a weight-average molecular weight of 10,900.

[0047] [Examples 1 to 11, Comparative Examples 1 to 10] Various materials were mixed at 90°C in the proportions shown in Table 1 below, and after cooling to room temperature, the resin compositions were evaluated as follows.

[0048] [Liquid appearance] To evaluate the compatibility of component (A), the resin composition obtained above was visually observed and judged according to the following criteria. ○: Component (A) is completely dissolved and transparent △: Component (A) is dissolved, but the solution is cloudy ×: Component (A) is not dissolved

[0049] [Appearance of cured film] The appearance of the cured film was evaluated to confirm the light transmittance and light diffusion properties when the resin composition was made into a film. The resin composition obtained above was sandwiched between polyethylene terephthalate films having a release layer, stretched using a roll press until the thickness of the cured film became 200 μm, and then subjected to a 20 mW / cm 2 The film was cured by irradiating it with ultraviolet light from a metal halide lamp adjusted to an illuminance of 365 nm (wavelength) for 150 seconds. The cured film was visually observed and rated according to the following criteria. A micrograph of the cured film of Example 6, viewed from the ultraviolet-irradiated side, is shown in Figure 1. ○: The cured film is transparent and the light transmittance changes depending on the observation angle △: The cured product is transparent, but the light transmittance does not change depending on the observation angle ×: The cured product lacks transparency and is cloudy from any angle.

[0050] [Haze value] The haze value of the cured film was measured to quantify the light diffusion property when the resin composition was made into a film. The cured film prepared in the above-mentioned cured film appearance evaluation was cut into a 3 cm x 3 cm square, the polyethylene terephthalate film was peeled off, and the haze value was measured using a haze meter (Tokyo Denshoku Corporation: TC-H3DPK), with the empty state as the zero point. The haze value is expressed as the ratio of scattered light transmittance to total light transmittance, and a higher value indicates higher light diffusion property.

[0051] [Elastic modulus, elongation] To evaluate the mechanical properties of the resin composition when it was formed into a film, the elastic modulus of the cured film was measured. Dumbbell-shaped test pieces measuring 75 mm in overall length, 10 mm in overall width, and 100 μm in thickness (narrow parallel portion 30 mm in length x 5 mm in width) were cut out of the cured film prepared in the above cured film appearance evaluation in accordance with JIS 7113-1(1 / 2). After peeling off the polyethylene terephthalate film, tensile measurements were performed using a universal testing machine (Shimadzu Corporation: Autograph AG-Xplus500N) at a temperature of 23°C, a grip length of 50 mm, and a test speed of 10 mm / min. The elastic modulus was calculated from the measured tensile stress and strain values within the proportional limit. Furthermore, the displacement from the point at which a tensile load of 0.05 N was applied to the cured film to the point at which the cured film broke was measured, and the elongation was calculated by dividing this displacement by the grip length of 50 mm, which is the initial length of the cured film.

[0052] [Table 1]

[0053] [Table 2]

[0054] [Table 3]

[0055] Examples 1 to 11 achieved good results in all tests. On the other hand, Comparative Examples 6 to 8 had problems in that the cured films were cloudy, Comparative Examples 1, 2, 5, 7, and 8 had low modulus of elasticity, and Comparative Examples 3, 4, 9, and 10 had low haze values. Furthermore, from FIG. 1, it was confirmed that uniform domains on the order of microns were formed in the cured film of Example 6, confirming that the resin composition of the present application can form a layer-separated structure by ultraviolet irradiation. In Comparative Example 6, the compatibility of Component A was significantly poor, so a uniform cured film could not be produced, and all measurements were impossible.

Claims

1. (A) a polymer having no polymerizable ethylenically unsaturated group, (B) a urethane (meth)acrylate, (C) a (meth)acrylate monomer, and (D) a photoradical polymerization initiator; The component (A) is an ultraviolet-curable resin composition for a light-diffusing film, which has a glass transition temperature of 25° C. or higher and a weight-average molecular weight of 2,000 or higher and 20,000 or lower.

2. 2. The ultraviolet-curable resin composition for a light-diffusing film according to claim 1, wherein the content of said component (A) is 25% by weight or less of the total amount of said ultraviolet-curable resin composition for a light-diffusing film.

3. 2. The ultraviolet-curable resin composition for a light diffusion film according to claim 1, wherein the component (A) is a polymer of a (meth)acrylic component having one or more functional groups selected from the group consisting of a hydroxyl group, an epoxy group, and a carboxyl group.

4. A light diffusion film obtained by ultraviolet curing the ultraviolet-curable resin composition for a light diffusion film according to claim 1 .

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