JP2016126141A - Resin composition for light diffusion film, and light diffusion film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new resin composition for a light diffusion film which has not only high light diffusion property but also excellent luminance characteristics.SOLUTION: A resin composition (F) for a light diffusion film contains an urethane(meth) acrylate compound (C) which contains the following components (A) and (B) and has a weight average molecular weight of 2,000 or more and a liquid refractive index of 1.40-1.54; a (meth)acrylate ester compound (D) having an aromatic skeleton having a weight average molecular weight of 1,000 or less and a liquid refractive index of 1.55-1.65; and a photopolymerization initiator (E).The component (A) is at least one or more polyol compounds selected from polyester polyol, polycarbonate polyol and a low molecular diol compound, and the component (B) is an aliphatic and/or alicyclic polyisocyanate compound.SELECTED DRAWING: None

Description

  The present invention relates to a resin composition for a light diffusing film and a light diffusing film, and in particular, a resin composition for a light diffusing film capable of obtaining a light diffusing film having a high light diffusing angle and excellent luminance characteristics, and the same. The present invention relates to a light diffusing film obtained by curing.

  A light diffusion film (light control film) in which incident light in a specific angle region is scattered and expresses opacity, and incident light in other specific angle regions is transmitted and expresses transparency, for example, privacy In order to protect the film, it is used as a viewing angle control film used for window glass, a cash dispenser touch panel, etc., and as an optical film such as a viewing angle widening film for a flat panel display.

  As such a light diffusion film, for example, a film-like composition containing at least a material having a high refractive index and a material having a low refractive index, such as 2-hydroxy-3-phenoxypropyl acrylate and polyether urethane (meth) acrylate A light diffusion film obtained by irradiating an object with ultraviolet rays from a specific direction and curing the composition is known (Patent Document 1).

  In such a light diffusion film, in order to improve the diffusion angle, the homopolymer is efficiently formed in the ultraviolet curing process, and the purity of each component in the cured product of the layer having a high refractive index and the layer having a low refractive index is adjusted. For example, Patent Document 2 proposes that a compound having a radical polymerizable group and a compound having a cationic group be used in combination to obtain a light diffusion film having a portion having a different refractive index. ing. However, the high refractive index resin material used is based on the bisphenol type, and the refractive index is not high enough. In order to improve the diffusion angle, a material with a higher refractive index is used. There is a need.

  An example of an attempt to improve the scattering angle characteristics by having a higher refractive index material has a higher refractive index is the application of a fluorene-based acrylate compound as described in Patent Document 3. Also in this case, a composition using both a radical curing system and a cationic curing system is used at the time of ultraviolet curing, and the residual of a strongly acidic substance derived from the photocation initiator may become a problem in terms of quality of the final member.

  In addition, an anisotropic light diffusing film composition that uses only a radical curing system in an ultraviolet curing process is known as a light diffusing film composition (Patent Document 4). In such a composition, (meth) acrylate having a biphenyl skeleton is used as a high refractive index material, and urethane (meth) acrylate is used as a low refractive index material. Polypropylene glycol is used as a component constituting such urethane (meth) acrylate. Such polyether polyols are specifically disclosed.

Japanese Patent No. 3211381 JP 2006-028205 A JP 2008-239757 A JP 2012-141591 A

  In the light diffusing film obtained by curing the composition for anisotropic light diffusing film, although the scattering angle is improved to some extent, other optical characteristics, particularly the luminance characteristics are not sufficient.

  Therefore, the present invention provides a novel resin composition for a light diffusing film that can obtain a light diffusing film excellent not only in light diffusibility but also in luminance characteristics.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that a resin composition containing a (meth) acrylate compound having a specific structural composition solves the above problems, and reached the present invention. did.

（式中、Ｒ_１は炭素数１から５の炭化水素基、Ｒ_２は水素原子またはメチル基を示し、ｎは平均の繰り返し数であり、ｎ＝０〜５を示す。）

（式中、Ｒ_１は同一もしくはそれぞれ異なり炭素数１から５の炭化水素基、Ｒ_２は同一もしくはそれぞれ異なり水素原子またはメチル基を示し、ｍおよびｎは平均の繰り返し数であり、ｍ＋ｎ＝０．４〜１２をそれぞれ示す。）
（８）（１）乃至（７）のいずれか一項に記載の光拡散フィルム用樹脂組成物（Ｆ）を光硬化させてなる光拡散フィルム、
（９）（８）に記載の光拡散フィルムを有する物品、
（１０）光拡散フィルムの製造方法であって、（１）乃至（７）のいずれか一項に記載の光拡散フィルム用樹脂組成物（Ｆ）に、光を照射して、該組成物を硬化させることを含む、方法、
（１１）光が紫外線又は可視光線であることを特徴とする（１０）記載の方法、
（１２）光の照度が１０〜１５００μＷ／ｃｍ^２であることを特徴とする（１０）または（１１）記載の方法。
（１３）光を０．５〜３０分間照射することを特徴とする（１０）乃至（１２）のいずれか一項に記載の方法、
に関する。 That is, the present invention
(1) Urethane (meth) acrylate compound (C) having a weight average molecular weight of 2,000 or more and a liquid refractive index of 1.40 to 1.54 including components (A) and (B) shown below, and weight Containing a (meth) acrylic acid ester compound (D) having an aromatic skeleton having an average molecular weight of 1,000 or less and a liquid refractive index of 1.55 to 1.65, and a photopolymerization initiator (E). Characteristic resin composition for light diffusion film (F),
Component (A): At least one polyol compound selected from polyester polyol, polycarbonate polyol, and low molecular diol compound Component (B): Aliphatic and / or alicyclic polyisocyanate compound (2) Urethane (meth) acrylate compound (C), the resin composition for light diffusion films (F) according to (1), further comprising a polyether polyol component,
(3) The resin composition for light diffusing films (F) according to (1) or (2), wherein the viscosity of the (meth) acrylic acid ester compound (D) at 60 ° C. is 10 Pa · s or less,
(4) The resin composition for light diffusion films (F) according to any one of (1) to (3), wherein the curing shrinkage of the (meth) acrylic ester compound (D) is 10% or less,
(5) The resin composition for light diffusion films (F) according to any one of (1) to (4), wherein the glass transition temperature (Tg) of the (meth) acrylic acid ester compound (D) is 40 ° C. or higher. ),
(6) The (meth) acrylic acid ester compound (D) is a compound containing two or more aromatic rings in one molecule, as described in any one of (1) to (5) Resin composition for light diffusion film (F),
(7) (meth) acrylic acid ester compound (D) is a compound represented by the following general formula (1), a compound represented by the following general formula (2), a compound represented by the formula (1) The resin composition for light diffusion film (F) according to any one of (1) to (6), which is a mixture of compounds represented by the formula (2),

(In the formula, R ₁ represents a hydrocarbon group having 1 to 5 carbon atoms, R ₂ represents a hydrogen atom or a methyl group, n represents an average number of repetitions, and n = 0 to 5).

(Wherein R ₁ is the same or different and each is a hydrocarbon group having 1 to 5 carbon atoms, R ₂ is the same or different and represents a hydrogen atom or a methyl group, m and n are average repeat numbers, and m + n = 0. .4 to 12 are shown.)
(8) A light diffusion film obtained by photocuring the resin composition for light diffusion film (F) according to any one of (1) to (7),
(9) An article having the light diffusion film according to (8),
(10) A method for producing a light diffusing film, wherein the resin composition (F) for a light diffusing film according to any one of (1) to (7) is irradiated with light, and the composition is applied. A method comprising curing,
(11) The method according to (10), wherein the light is ultraviolet light or visible light,
(12) The method according to (10) or (11), wherein the illuminance of light is 10 to 1500 μW / cm ² .
(13) The method according to any one of (10) to (12), wherein the light is irradiated for 0.5 to 30 minutes.
About.

  The resin composition for a light diffusing film of the present invention has excellent luminance characteristics in addition to a high light scattering angle in a cured product after photocuring, and when the cured product is applied to a reflective liquid crystal display device or the like. In addition, external light can be used efficiently as a light source, and a clear display object with a wide viewing angle can be realized.

Drawing 1 is a figure for explaining an outline of a manufacturing method of a hardened material of a resin composition for light diffusion films obtained in an example. FIG. 2 is a photograph showing the result of observation of the test piece of the cured product obtained in Example 1 with a laser microscope. FIG. 3 is a diagram showing the measurement results of the light diffusion distribution of the cured product obtained in Example 1. FIG. 4 is a diagram showing the results of comparing the light diffusion distributions of the cured products obtained in Example 11 and Comparative Example 1, respectively. FIG. 5 is a diagram showing a result of comparing the light diffusion distribution of the cured product obtained in Example 12 and a conventional light diffusion film.

  The resin composition for a light diffusing film of the present invention contains a specific urethane (meth) acrylate compound (C), a specific (meth) acrylic acid ester compound (D), and a photopolymerization initiator (E). And

  When the resin composition for light diffusion film (F) of the present invention is photocured, the urethane (meth) acrylate compound (C) as a low refractive index component and the (meth) acrylic acid ester compound as a high refractive index component ( As a result of polymerizing each of D) as a main homopolymer while phase-separating due to the difference in polymerization rate, it is possible to obtain a layered cured product in which the layers of each component are alternately stacked. By such a layered structure, The cured product is considered to exhibit a light diffusion function.

  Therefore, the urethane (meth) acrylate compound (C) and the (meth) acrylic acid ester compound (D) used in the present invention preferably maintain a compatible liquid state before curing and a phase-separated combination at the time of curing. In order to develop the diffusion function, the liquid refractive index of the urethane (meth) acrylate compound (C) is 1.40 to 1.54, preferably 1.40 to 1.51, and the (meth) acrylate compound The liquid refractive index of (D) is 1.55-1.65, preferably 1.58-1.65. Here, the liquid refractive index refers to the refractive index at 25 ° C. of the compound before photocuring.

  The difference in liquid refractive index between the urethane (meth) acrylate compound (C) and the (meth) acrylic ester compound (D) is preferably 0.05 or more from the viewpoint of improving the luminance and the diffusion angle. More preferably, it is 0.1 or more. In addition, although the difference of liquid refractive index is so preferable that it is large, the upper limit is considered to be about 1.

  Further, in order to obtain a combination that causes a difference in polymerization rate during photocuring and is more easily phase-separated, it is preferably a combination of compounds having a difference in molecular weight, and the weight average molecular weight of the urethane (meth) acrylate compound (C) Is preferably 2,000 or more, and the weight average molecular weight of the (meth) acrylic acid ester compound (D) is preferably 1,000 or less. In addition, “weight average molecular weight” in the present specification is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

  The urethane (meth) acrylate compound (C) used in the present invention preferably has a structural characteristic such that it can be polymerized while being phase separated from the (meth) acrylic ester compound (D) when cured.

  In order to further increase the transparency of the light diffusion film of the present invention, the urethane (meth) acrylate compound (C) is preferably non-yellowing, that is, non-yellowing. As the non-yellowing urethane (meth) acrylate compound, a known commercial product can be used.

  The urethane (meth) acrylate compound (C) includes at least one polyol compound selected from a polyester polyol compound, a polycarbonate polyol compound, and a low molecular diol compound as the component (A), and an aliphatic as the component (B). And / or including an alicyclic polyisocyanate compound.

  The polyester polyol compound and the polycarbonate polyol compound used as the component (A) are easy to express the intermolecular aggregation effect at the time of curing of the urethane (meth) acrylate compound (C), and the low molecular diol compound is urethane (meth) acrylate. The molecular cohesion force of the compound (C) can be improved. That is, by using these polyol compounds as constituent components of the urethane (meth) acrylate compound (C), the aggregation effect of the urethane (meth) acrylate compound (C) can be enhanced.

  Polyester polyols that can be used as component (A) include (poly) ethylene glycol, (poly) propylene glycol, (poly) tetramethylene glycol, (poly) butylene glycol, 3-methyl-1,5-pentanediol, hexanediol, and the like. Diol components and polybasic compounds such as maleic acid, fumaric acid, succinic acid, adipic acid, phthalic acid, isophthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid, dimer acid, sebacic acid, azelaic acid, 5-sodium sulfoisophthalic acid Polyester polyols which are a reaction product of acids and their anhydrides; cyclic lactone-modified polyester diols comprising the diol component and polybasic acids and their anhydrides and ε-caprolactone, γ-butyrolactone, δ-valerolactone, etc. To mention Kill, but is not limited to these.

  Similarly, the polycarbonate polyol which can be used as the component (A) is an aliphatic polycarbonate polyol which is a polycarbonate of an aliphatic diol such as butanediol, pentanediol or hexanediol, or a polycarbonate of an alicyclic diol such as cyclohexanedimethanol. The alicyclic polycarbonate polyol etc. which are can be mentioned.

  Similarly, the low molecular weight diol compound that can be used as the component (A) is a diol having a weight average molecular weight of 800 or less, such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, neopentylglycol. , Glycols such as methylpentanediol and nonanediol, cyclohexane dimethylol, hydrogenated bisphenol A, hydrogenated bisphenol F, spiro skeleton-containing alcohols, alicyclic alcohols such as tricyclodecane dimethylol and pentacyclopentadecane dimethylol, and these An alkylene oxide adduct etc. can be mentioned.

  In addition to the component (A) described above, other polyol components can be used in combination. Examples of polyol components that can be used in combination include polyether polyols such as polyethylene glycol, polybutylene glycol, polytetramethylene glycol, polypropylene glycol, and polyethylene glycol, polymers such as polyolefins such as polybutadiene and polyisobutene, and polyols of hydrides thereof. Examples include polyols.

  The aliphatic and / or alicyclic polyisocyanate compound of the component (B) constituting the urethane (meth) acrylate compound (C) used in the present invention maintains its transparency in the light diffusion film of the present invention. It is used for maintaining a low refractive index in a portion formed by the urethane (meth) acrylate compound (C) and maintaining light resistance and weather resistance as an optical film.

  Examples of the aliphatic and / or alicyclic polyisocyanate compound include 1,6-hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and 1,3-diisocyanate cyclohexane. 1,4-diisocyanatecyclohexane, dicyclohexylmethane-4,4'-diisocyanate, m-tetramethylxylene diisocyanate, p-tetramethylxylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,12-dodecamethylene diisocyanate, 2, 2,4-trimethylcyclohexane diisocyanate, 2,4,4-trimethylcyclohexane diisocyanate, 2,2,4-trimethylhexa Ji diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, norbornane diisocyanate and the like.

  The urethane (meth) acrylate compound (C) used in the present invention includes the component (A) or a combination of the component (A) and the polyol component other than the component (A) as desired, and the component (B). And a hydroxyl group-containing (meth) acrylate.

  Examples of the hydroxyl group-containing (meth) acrylate that can be used for the production of the urethane (meth) acrylate compound (C) include hydroxy groups such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate. C2-C4 alkyl (meth) acrylate, dimethylol cyclohexyl mono (meth) acrylate, hydroxycaprolactone (meth) acrylate, hydroxyl group-terminated polyalkylene glycol (meth) acrylate, and the like can be used.

  Reaction for obtaining the said urethane (meth) acrylate compound (C) is performed as follows, for example. That is, the isocyanate group is preferably 1.1 to 2.0 equivalents, more preferably 1.1 to 1.5 equivalents of the aliphatic and / or alicyclic polyisocyanate compound per equivalent of the hydroxyl group to the polyol compound. And the reaction temperature is preferably 70 to 90 ° C. to synthesize a urethane oligomer. Next, the above hydroxyl group-containing (meth) acrylate compound is mixed so that the hydroxyl group is preferably 1 to 1.5 equivalent per equivalent of isocyanate group of the urethane oligomer, and reacted at 70 to 90 ° C. for the purpose. A urethane (meth) acrylate compound (C) can be obtained.

  In the resin composition for light diffusion films (F) of the present invention, one or more of the urethane (meth) acrylate compounds (C) can be mixed and used in an arbitrary ratio.

  Unlike the urethane (meth) acrylate compound (C), the (meth) acrylic acid ester compound (D) used in the present invention retains the cured product characteristics as a high refractive index component. The (meth) acrylic acid ester compound which has is used.

  As the (meth) acrylic acid ester compound having an aromatic skeleton, there is a (meth) acrylic acid ester compound generally obtained from a compound having a phenolic hydroxyl group through modification with ethylene oxide, propylene oxide, glycidyl ether or the like.

As a specific example of the (meth) acrylic acid ester compound, for example,
(Meth) acrylate of a compound having one phenolic hydroxyl group such as phenol, o-phenylphenol, naphthol, ethylene oxide adduct or propylene oxide adduct (meth) acrylate of the compound having phenolic hydroxyl group, phenylglycidyl ether Aromatic monofunctional (meth) acrylic esters such as epoxy (meth) acrylate and epoxy (meth) acrylate of phenylphenol glycidyl ether;
Bisphenol A, bisphenol F, bisphenol S, bisphenol O, bisphenol E, binaphthol, fluorene compounds, (meth) acrylates of compounds having a plurality of phenolic hydroxyl groups, ethylene oxide addition of compounds having phenolic hydroxyl groups Aromatic or polyfunctional (meth) acrylate compounds such as (meth) acrylates of adducts or propylene oxide adducts, and epoxy (meth) acrylates of compounds having a phenolic hydroxyl group.

  Since the (meth) acrylic acid ester compound (D) used in the present invention is used in combination with a urethane (meth) acrylate compound (C) having a relatively high molecular weight, a low viscosity compound is preferable from the viewpoint of workability. Specifically, the viscosity at 60 ° C. measured with an E-type viscometer is preferably 10 Pa · s or less.

Further, in order not to adversely affect the film shape such as curling and cracking when cured, the (meth) acrylic acid ester compound (D) preferably has a low shrinkage, and specifically has a cure shrinkage of 10% or less. Are preferred. Here, the curing shrinkage is calculated from the following formula: liquid specific gravity before curing at 25 ° C. and film specific gravity at 25 ° C. obtained by curing.
Curing shrinkage = (film specific gravity−liquid specific gravity) / film specific gravity × 100
Is calculated by

  Further, the (meth) acrylic acid ester compound (D) is preferably a compound capable of maintaining heat resistance as film characteristics. Specifically, the glass transition temperature (Tg) of the (meth) acrylic acid ester compound (D) is 40 ° C. The above is preferable.

  Among the (meth) acrylic acid ester compounds (D) described above, compounds having two or more aromatic rings in one molecule are preferable because they have a higher refractive index.

（式中、Ｒ_１は炭素数１から５の炭化水素基、Ｒ_２は水素原子またはメチル基を示し、ｎは平均の繰り返し数であり、ｎ＝０〜５を示す。）

（式中、Ｒ_１は同一もしくはそれぞれ異なり炭素数１から５の炭化水素基、Ｒ_２は同一もしくはそれぞれ異なり水素原子またはメチル基を示し、ｍおよびｎは平均の繰り返し数であり、ｍ＋ｎ＝０．４〜１２をそれぞれ示す。） Specifically, the (meth) acrylic acid ester compound (D) is represented by the compound represented by the following general formula (1), the compound represented by the following general formula (2), and the formula (1). A mixture of the compound and the compound represented by the formula (2) is more preferable because the refractive index is higher.

(In the formula, R ₁ represents a hydrocarbon group having 1 to 5 carbon atoms, R ₂ represents a hydrogen atom or a methyl group, n represents an average number of repetitions, and n = 0 to 5).

(Wherein R ₁ is the same or different and each is a hydrocarbon group having 1 to 5 carbon atoms, R ₂ is the same or different and represents a hydrogen atom or a methyl group, m and n are average repeat numbers, and m + n = 0. .4 to 12 are shown.)

  In the resin composition for light diffusion film (F) of the present invention, the (meth) acrylic acid ester compound (D) can be used alone or as a mixture of two or more.

  In the resin composition for light diffusion films of the present invention, the ratio of the components (C) and (D) is not particularly limited, but the weight ratio of the component (C) :( D) is from 3: 7 to 7: 3 is preferred, and 1: 1 is more preferred.

  Specific examples of the photopolymerization initiator (E) used in the resin composition for light diffusion film (F) of the present invention include benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, and benzoin isobutyl ether. Acetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methyl-phenylpropan-1-one, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl Acetophenones such as -1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one; 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-chloroanthraquinone, 2-amylanthraquinone Anthraquinones; thioxanthones such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenone, 4-benzoyl-4′-methyldiphenyl Benzophenones such as sulfide and 4,4′-bismethylaminobenzophenone; phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide Can be mentioned. These addition ratios are usually 0.01 to 30% by weight, preferably 0.1 to 25% by weight, when the solid content of the resin composition (F) is 100% by weight.

  Said photoinitiator (E) can be used individually or in mixture of 2 or more types, Furthermore, tertiary amines, such as a triethanolamine and a methyldiethanolamine, N, N- dimethylaminobenzoic acid ethyl ester, N, It can be used in combination with an accelerator such as a benzoic acid derivative such as N-dimethylaminobenzoic acid isoamyl ester. As the addition amount of these accelerators, an amount of 100% by weight or less is added to the photopolymerization initiator (E) as necessary.

  Usually, a polymerization inhibitor such as 4-methoxyphenol is already added to the acrylate compound used as a raw material, but a polymerization inhibitor may be added again during the reaction. Examples of such polymerization inhibitors include hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-cresol, 3-hydroxythiophenol, Examples include p-benzoquinone, 2,5-dihydroxy-p-benzoquinone, and phenothiazine. The amount used is 0.01 to 1% by weight based on the reaction raw material mixture.

  In order to obtain the resin composition for light diffusion film (F) of the present invention, the above-described components may be mixed, and the order and method of mixing are not particularly limited.

  The resin composition for a light diffusing film of the present invention does not substantially require a solvent. For example, ketones such as methyl ethyl ketone and methyl isobutyl ketone, acetates such as ethyl acetate and butyl acetate, benzene, toluene, It is also possible to dilute and use the resin composition for light diffusing films of the present invention with other commonly used organic solvents such as aromatic hydrocarbons such as xylene.

  The resin composition for light diffusing film (F) of the present invention is excellent in flexibility, weather resistance, and light resistance, in addition to a novel light diffusing film application excellent in high light diffusibility and other optical properties. , Optical applications that need to maintain transparency, inks, plastic paints, paper printing, metal coatings, furniture coatings, various coating fields, linings, adhesives, as well as insulating varnishes, insulating sheets and laminates in the electronics field It is useful in many fields such as printed circuit boards, resist inks and semiconductor encapsulants. More specific applications include planographic relief inks, flexographic inks, gravure inks, screen inks and other ink fields, glossy fields, paper coating materials fields, wood coating materials fields, beverage can coating materials or printing ink fields, Soft packaging film coating agent, printing ink or adhesive, thermal paper, thermal film coating agent, printing ink, adhesive, adhesive or optical fiber coating agent, liquid crystal display device, organic EL display device, touch panel type image display device It is useful for applications such as air gap fillers for display devices (fillers for gaps between display devices and face plates).

  Next, the light diffusion film of the present invention will be described. The light diffusion film of the present invention is obtained by photocuring the above-described resin composition for light diffusion film (F). The light diffusing film of the present invention comprises a layer obtained by polymerizing the low refractive index urethane (meth) acrylate compound (C) as a main homopolymer, and the above high refractive index (meth) acrylate compound (D ) Has a layered structure in which layers formed by polymerization as a main homopolymer are alternately stacked in parallel to the light irradiation direction. In particular, in the light diffusing film of the present invention, the urethane (meth) acrylate compound (C) and the (meth) acrylic acid ester compound (D) are phase-separated at the time of curing and cured to achieve respective purity. A very high layer is formed, and the layers of each component are alternately stacked. With such a layered structure, the light diffusing film of the present invention has a wide diffusion angle, high light transmittance, and less luminance unevenness.

  The light-diffusion film of this invention can be manufactured by irradiating light to the resin composition (F) for light-diffusion films mentioned above, and hardening this composition.

  The light used in the method for producing a light diffusion film of the present invention is preferably ultraviolet rays or visible rays having a wavelength of 180 to 500 nm from the viewpoint of productivity. In addition, the wavelength of the light to be used can be determined according to the absorption wavelength of the photopolymerization initiator (E) to be used.

  Examples of the light generation source of ultraviolet light or visible light having a wavelength of 180 to 500 nm include, for example, a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a chemical lamp, a black light lamp, a mercury-xenon lamp, an excimer lamp, and a short. Examples include arc lamps, helium / cadmium lasers, argon lasers, excimer lasers, and sunlight.

In the method for producing a light diffusion film of the present invention, in order to improve the phase separation of the urethane (meth) acrylate compound (C) and the (meth) acrylic ester compound (D) at the time of curing, It is desirable to carry out photopolymerization at low illuminance. Specifically, the illuminance used for the photopolymerization is preferably 10 to 1500 μW / cm ² , more preferably 10 to 100 μW / cm ² , and particularly preferably 10 to 50 μW / cm ² . Furthermore, in order to achieve photopolymerization at the low illuminance mentioned above, the light irradiation time is preferably 0.5 to 30 minutes, more preferably 5 to 30 minutes, and 5 to 20 minutes. It is particularly preferred.

  The light diffusing film of the present invention is an optical film such as a viewing angle control film used for a window glass or a cash dispenser touch panel to protect privacy, and a viewing angle widening film of a reflective liquid crystal display device such as a flat panel display. Can be used as The light diffusion film of the present invention has a high light diffusion angle and excellent luminance characteristics, and is suitable for use as the above-described film.

  The article of the present invention is characterized by having the above-described light diffusion film of the present invention. Although it does not specifically limit as articles | goods which can use the light-diffusion film in this invention, For example, reflective liquid crystal display devices, such as a window glass, a cash dispenser touch panel, and a flat panel display, are mentioned. The article of the present invention includes a light diffusing film having an appropriate light diffusing angle and luminance characteristics depending on the application, and is excellent in the characteristics of the film.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the following Example.

  As shown in Table 1 below, the liquid refractive index (25 ° C.) of the urethane (meth) acrylate compound (manufactured by Nippon Kayaku Co., Ltd.) used as the low refractive index material is the Abbe refractometer (DR-M2: Atago Co., Ltd.). Manufactured).

  Similarly, as shown in Table 2 below, the liquid refractive index (25 ° C.) of the (meth) acrylic acid ester compound (manufactured by Nippon Kayaku Co., Ltd.) used as the high refractive index material is the Abbe refractometer (DR-M2 :( Measured by Atago Co., Ltd.

Examples 1-10
Compounds (C-1) to (C-5) in Table 1 as urethane (meth) acrylate compounds (C), and compounds (D-1) to (D-) in Table 2 as (meth) acrylic acid ester compounds (D) 2) As a photopolymerization initiator, Darocur 1173 (2-hydroxy-2-methyl-phenylpropan-1-one) was mixed as shown in Tables 3 and 4 below (weight%), and the light of the present invention was mixed. A resin composition for a diffusion film was obtained.

The resin compositions for light diffusing films obtained in Examples 1 to 10 were irradiated with parallel UV light (wavelength: 365 nm) at an illuminance of 34 μW / cm ² for 10 minutes so as to have a film thickness of 200 μm as shown in FIG. A specimen was obtained.

  The test piece of the obtained cured product was observed with a laser microscope (manufactured by Keyence). The result of having observed the test piece of the hardened | cured material obtained in Example 1 with the laser microscope is shown in FIG. In Examples 1 to 10, it was confirmed that a cured product having a layered structure parallel to the exposure direction was obtained as shown in FIG.

  A conoscope (manufactured by Autoronic) was used to measure the light diffusion distribution, and light was incident in the vertical direction with a white LED collimated on the cured surface. FIG. 3 shows the light diffusion distribution of the cured product obtained in Example 1. In Examples 1 to 10, it was confirmed that the obtained cured product had a diffusive distribution as shown in FIG.

  In FIG. 3, the horizontal axis indicates the light diffusion angle, and the vertical axis indicates a scale related to light transmission. When the width is wide, the diffusibility is high, and when the width is high, it indicates that a film excellent in light transmittance is obtained.

  The obtained light diffusion characteristics (angle range) and luminance characteristics (intensity value average) are summarized in Tables 3 and 4 below.

  The resin composition for a light diffusing film of the present invention has a light diffusing characteristic in a cured product after photocuring, and is excellent in luminance characteristics.

Comparative Synthesis Example 1
In a reactor equipped with a reflux condenser, a stirrer, a thermometer, and a temperature controller, 1 mol of Exenol 3020 (polypropylene glycol, hydroxyl value: 35.9 mg · KOH / g) manufactured by Asahi Glass Co., Ltd. as a diol compound, isophorone diisocyanate 1.5 mol was added, 100 ppm of tin octylate was added as a urethanization reaction catalyst, and the mixture was reacted at 90 ° C. for 12 hours. Next, 500 ppm of 4-methoxyphenol was added as a polymerization inhibitor, 1.0 mol of 2-hydroxyethyl methacrylate was added, and the mixture was reacted at 80 ° C. for 12 hours to obtain urethane acrylate (C-6) having a weight average molecular weight of 10,000. .

Example 11, Comparative Example 1
In the same manner as in the above procedure, blending was performed as shown in Table 5 below to obtain a cured product. The light diffusion characteristics were similarly observed and compared with a conoscope (manufactured by Autoronic) (FIG. 4). In addition, the numerical value in a table | surface shows the mixture ratio (weight%) of each component.

  When a urethane (meth) acrylate using only a polyether polyol such as polypropylene glycol is used as the polyol compound, although it has light diffusibility, the luminance characteristics are inferior to the resin composition for light diffusing film of the present invention. It was confirmed that a cured product was obtained.

Example 12
50 parts by weight of compound (C-1) as urethane (meth) acrylate compound (C), 50 parts by weight of compound (D-1) in Table 2 as (meth) acrylic acid ester compound (D), photopolymerization initiator As a result, 2 parts by weight of Darocur 1173 (2-hydroxy-2-methyl-phenylpropan-1-one) was mixed to obtain a resin composition for a light diffusion film of the present invention. The obtained resin composition is made into a cured product in the same manner as described above, and compared with the conventional light diffusion film used in the existing liquid crystal display device, their light diffusion characteristics are similarly conoscoped. Observations (manufactured by Autoronic) were repeated and compared (FIG. 5).

  The cured product of the resin composition for a light diffusing film of the present invention has no luminance unevenness as compared with a light diffusing film used in a currently marketed liquid crystal display device, which leads to reduction of glare in a liquid crystal display, for example. It is possible.

  The resin composition for a light diffusing film of the present invention has excellent luminance characteristics in addition to a high light scattering angle in a cured product after photocuring, and when the cured product is applied to a reflective liquid crystal display device or the like. In addition, external light can be used efficiently as a light source, and a clear display object with a wide viewing angle can be realized.

Claims (13)

The weight average molecular weight including the components (A) and (B) shown below is 2,000 or more, the liquid refractive index is 1.40 to 1.54 urethane (meth) acrylate compound (C), and the weight average molecular weight is 1. Characterized by containing a (meth) acrylic acid ester compound (D) having an aromatic skeleton having a liquid refractive index of 1.55 to 1.65 and a photopolymerization initiator (E) Resin composition for diffusion film (F).
Component (A): Polyester polyol, polycarbonate polyol, at least one polyol compound selected from diol compounds having a weight average molecular weight of 800 or less Component (B): Aliphatic and / or alicyclic polyisocyanate compound   The resin composition (F) for a light diffusion film according to claim 1, wherein the urethane (meth) acrylate compound (C) further comprises a polyether polyol component.   The resin composition (F) for a light diffusing film according to claim 1 or 2, wherein the viscosity of the (meth) acrylic acid ester compound (D) at 60 ° C is 10 Pa · s or less.   The resin composition (F) for light diffusion films according to any one of claims 1 to 3, wherein the curing shrinkage of the (meth) acrylic acid ester compound (D) is 10% or less.   The resin composition (F) for light diffusion films according to any one of claims 1 to 4, wherein the glass transition temperature (Tg) of the (meth) acrylic ester compound (D) is 40 ° C or higher.   6. The resin for light diffusion films according to claim 1, wherein the (meth) acrylic acid ester compound (D) is a compound containing two or more aromatic rings in one molecule. Composition (F). The (meth) acrylic acid ester compound (D) is a compound represented by the following general formula (1), a compound represented by the following general formula (2), a compound represented by the formula (1) and the formula (1) The resin composition (F) for a light diffusion film according to any one of claims 1 to 6, which is a mixture of compounds represented by 2).

(In the formula, R ₁ represents a hydrocarbon group having 1 to 5 carbon atoms, R ₂ represents a hydrogen atom or a methyl group, n represents an average number of repetitions, and n = 0 to 5).

(Wherein R ₁ is the same or different and each is a hydrocarbon group having 1 to 5 carbon atoms, R ₂ is the same or different and represents a hydrogen atom or a methyl group, m and n are average repeat numbers, and m + n = 0. .4 to 12 are shown.)   The light-diffusion film formed by photocuring the resin composition for light-diffusion films (F) as described in any one of Claims 1 thru | or 7.   An article comprising the light diffusing film according to claim 8.   It is a manufacturing method of a light-diffusion film, Comprising: Irradiating light to the resin composition (F) for light-diffusion films as described in any one of Claims 1 thru | or 7, this composition is hardened. ,Method.   The method according to claim 10, wherein the light is ultraviolet light or visible light. 12. The method according to claim 10, wherein the illuminance of light is 10 to 1500 [mu] W / cm < ² >.   The method according to any one of claims 10 to 12, wherein the light is irradiated for 0.5 to 30 minutes.

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