JP2012193220A - Electron beam-curable composition for forming optical film or sheet, optical film or sheet, and polarizer protecting film and sheet polarizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam-curable composition for forming an optical film excellent in a balance of the transparency and the yellowing degree after the light resistance test of its cured material, good in solvent resistance, and low in the in-plane retardations in the frontal and oblique directions and the thickness-direction retardation, even if containing no UVA or containing UVA; and to provide an optical film obtained, and a polarizer protecting film and a sheet polarize obtained from the composition.SOLUTION: The optical film or the electron beam-curable composition for forming a sheet contains a urethane (meth)acrylate (A) being a reaction product of a polycarbonate diol, a polyester diol or a polyether diol, a yellowing-free organic diisocyanate and a hydroxyl group-containing (meth)acrylate, and a compound having one (meth)acryloyl group, wherein the haze of its cured material is ≤1.0%, and the in-plane retardations in the frontal and 40°-oblique directions and the thickness-direction retardation are all ≤10 nm.

Description

The present invention relates to an electron beam curable composition used for forming an optical film, an optical film or sheet obtained by curing the composition, and a polarizing plate using the same as a polarizer protective film. Belonging to.
In the following, for the sake of convenience, unless otherwise specified, “optical film or sheet” is described as “optical film”. Further, acrylate or methacrylate is represented as (meth) acrylate.

  In the liquid crystal display device, it is indispensable to dispose polarizing plates on both sides of the glass substrate on which the liquid crystal panel surface is formed because of the image forming method. In general, a polarizing plate is obtained by bonding a polarizer protective film using triacetyl cellulose or the like to both surfaces of a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine with a polyvinyl alcohol adhesive. Things are used.

  The polarizer protective film may be required to have ultraviolet absorption performance for the purpose of preventing the liquid crystal and the polarizer from being deteriorated by ultraviolet rays. At present, an ultraviolet absorber (hereinafter referred to as “UVA”) is added to a triacetyl cellulose film as a polarizer protective film to impart ultraviolet absorption performance.

  However, triacetyl cellulose does not have sufficient heat and heat resistance, and when a polarizing plate using a triacetyl cellulose film as a polarizer protective film is used at a high temperature or under high humidity, the performance of the polarizing plate such as the degree of polarization and hue deteriorates. There is a drawback. The triacetyl cellulose film has a retardation with respect to incident light in the oblique direction and a retardation in the thickness direction. Such retardation is noticeably affecting viewing angle characteristics as the size of liquid crystal displays increases in recent years.

  Therefore, a transparent thermoplastic resin has been studied as a material for a polarizer protective film that replaces conventional triacetyl cellulose.

Patent Documents 1 and 2 disclose a polarizer protective film in which UVA is added to a transparent thermoplastic resin so as to have an ultraviolet absorption performance. In such a polarizer protective film, a resin protective film is disclosed. The yellowing is large, and UVA evaporates due to heat applied when molding a thermoplastic resin composition containing UVA, and the UV absorption ability of the obtained resin molded product is reduced, or the UVA that has evaporated evaporates the molding apparatus. Problems such as contamination may occur.
When producing a polarizer protective film from a thermoplastic resin composition containing UVA, if the compatibility with the resin is poor or if the amount of addition is large, it will precipitate, resulting in an increase in haze. There was a problem that the degree would decrease.

  Patent Document 3 discloses a thermoplastic acrylic resin having a small in-plane retardation for use in a polarizer protective film, but has insufficient solvent resistance, and the solvent or polarization of a hard coat agent applied to the surface. Problems such as a decrease in transparency due to erosion of the liquid adhesive used for bonding the child and the protective film may occur.

JP-A-9-166711 JP 2004-45893 A JP 2006-96960 A

  As described above, a transparent thermoplastic resin that has been studied as a material for a polarizer protective film that replaces the conventional triacetyl cellulose is one that contains a UVA, and the yellowing of the resin may increase. Insufficient properties may cause problems such as a decrease in transparency due to erosion of solvents and adhesives.

  Even if UVA is not included or UVA is included, the present invention has an excellent balance between the transparency of the cured product and the yellowing degree after the light resistance test, good solvent resistance, and front and oblique surfaces. It aims at providing the electron beam curable composition for optical film formation with small internal retardation and thickness direction retardation, the optical film obtained from the said composition, a polarizer protective film, and a polarizing plate.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have obtained urethane (meth) acrylate and one (() produced from a specific diol, a non-yellowing organic diisocyanate, and a hydroxyl group-containing (meth) acrylate. It has been found that an electron beam curable composition containing a compound having a (meth) acryloyl group and having a specific value of retardation and haze of the cured product can solve the above problems, and has completed the present invention.

The composition of the present invention is such that the front and oblique in-plane retardation and thickness direction retardation of the resulting cured product are as small as 10 nm or less and haze is 1.0% or less, whereby the cured product is transparent. And the balance after the light resistance test is excellent, and the solvent resistance is also excellent.
Therefore, the electron beam curable optical film of the present invention can be suitably used for a polarizer protective film, and there is no problem that the degree of polarization is lowered.

The present invention is a urethane (meth) acrylate (A) [hereinafter, a reaction product of at least one diol selected from polycarbonate diol, polyester diol or polyether diol, non-yellowing organic diisocyanate and hydroxyl group-containing (meth) acrylate. Simply (referred to as “component (A)”) and compound (B) having one (meth) acryloyl group (hereinafter simply referred to as “component (B)”),
For forming an optical film in which the haze of the cured product is 1.0% or less and all of the in-plane retardation and the in-plane retardation of the cured product and the thickness direction are 10 nm or less when measured at a thickness of 80 μm. The present invention relates to an electron beam curable composition.
Hereinafter, the present invention will be described in detail. In the present specification, a crosslinked product and a cured product obtained by irradiating the composition with an electron beam are collectively referred to as a “cured product”.

1. Component (A) Component (A) used in the present invention is polycarbonate diol, polyester diol or polyether diol (hereinafter collectively referred to as “diol a”), non-yellowing organic diisocyanate and hydroxyl group-containing (meth). It is urethane (meth) acrylate which is a reaction product of acrylate.
Compared with other urethane (meth) acrylates, the component (A) has a low degree of yellowing after the light resistance test by using diol a as the polyol and non-yellowing type as the organic diisocyanate.

As the component (A), a diol a and a non-yellowing organic diisocyanate are reacted to produce an isocyanate group-containing compound, which is then reacted with a hydroxyl group-containing (meth) acrylate (hereinafter referred to as “compound A1”). And a compound obtained by reacting diol a, a non-yellowing organic diisocyanate, and a hydroxyl group-containing (meth) acrylate at the same time (hereinafter referred to as “compound A2”), and the compound A1 is preferable because the molecular weight is easily controlled. .
As the component (A), both oligomers and polymers can be used, and those having a weight average molecular weight of 1,000 to 50,000 are preferable, and more preferably 3,000 to 30,000.
In the present invention, the weight average molecular weight is a value obtained by converting the molecular weight measured by gel permeation chromatography into polystyrene.

In the diol a, examples of the polycarbonate diol include a reaction product of a low molecular weight diol, a polyether diol, and / or a bisphenol such as bisphenol A and a dialkyl ester carbonate such as ethylene carbonate and dibutyl ester carbonate.
Here, examples of the low molecular weight diol include ethylene glycol, propylene glycol, cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 1,5-pentanediol, 1,6-hexanediol, and the like.
Examples of polyether diols include polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, and block or random polymer diols such as polyethylene polypropoxy block polymer diols.

  In the diol a, as the polyester diol, the low molecular weight diol or / and the polyether diol and a dibasic acid such as adipic acid, succinic acid, phthalic acid, tetrahydrphthalic acid, hexahydrophthalic acid and terephthalic acid, or The esterification reaction product with acid components, such as the anhydride, etc. are mentioned.

  In the diol a, the polyether diol includes polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol; block or random polymer diols such as polyethylene polypropoxy block polymer diol; and bisphenol A ethylene oxide adduct diol. And diol of bisphenol A alkylene oxide adduct of bisphenol A propylene oxide adduct.

  These diols a may be used alone or in combination of two or more.

  Non-yellowing organic diisocyanates include hexamethylene diisocyanate, lysine methyl ester diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate and other aliphatic diisocyanates, isophorone diisocyanate (hereinafter referred to as “IPDI”), 4, 4'-methylenebis (cyclohexyl isocyanate) (hereinafter referred to as “H12MDI”) and alicyclic diisocyanates such as ω, ω′-diisocyanate dimethylcyclohexane and the like.

  These organic diisocyanate compounds may be used alone or in combination of two or more.

  Among the above-mentioned compounds, when light resistance (weather resistance) is required for the cured product, IPDI and H12MDI are preferable.

As the hydroxyl group-containing (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxy Examples include octyl (meth) acrylate, pentaerythritol tri, di or mono (meth) acrylate, and hydroxyalkyl (meth) acrylate such as trimethylolpropane di or mono (meth) acrylate.
Among the above-described compounds, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate are preferable in terms of excellent sheet flexibility.

(A) A component may be manufactured according to the conventional method.
In the case of producing compound A1, in the presence of a urethanization catalyst such as dibutyltin dilaurate, the diol a and non-yellowing organic diisocyanate to be used are heated and stirred for addition reaction, and further hydroxyalkyl (meth) acrylate is added and heated and stirred. In the case of producing the compound A2, the diol a, the non-yellowing organic diisocyanate and the hydroxyalkyl (meth) acrylate are simultaneously added and stirred while heating in the presence of the same catalyst as described above. Methods and the like.

  (A) A component may use only 1 type or may use 2 or more types together.

2. Component (B) The component (B) is a compound having one (meth) acryloyl group. In the present invention, by including the component (B), the coating property of the composition and the mechanical strength of the cured product can be balanced.

  As the component (B), isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclohexyl (meth) acrylate, trimethylcyclohexyl (meth) acrylate, 1 -Adamantyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (Meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, glycidyl (meth) Acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, benzyl (meth) acrylate, allyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, о-phenylphenol EO Modified (n = 1-4) (meth) acrylate, p-cumylphenol EO modified (n = 1-4) (meth) acrylate, phenyl (meth) acrylate, о-phenylphenyl (meth) acrylate, p-cumylphenyl (Meth) acrylate, (meth) acryloylmorpholine, N-vinylformamide, N- (meth) acryloyloxyethyl hexahydrophthalimide, N- (meth) acryloyloxyethyl tetrahydrophthalimide and the like can be mentioned.

  As the component (B), only one kind of the aforementioned compounds may be used, or two or more kinds may be used in combination.

(B) As a component, (meth) acrylate whose glass transition temperature of a homopolymer is 50 degreeC or more is mentioned among the above-mentioned compounds.
Specific examples of the (meth) acrylate include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopenta in that the cured product of the composition has excellent heat resistance and light resistance. Nyl (meth) acrylate, (meth) acryloylmorpholine and N- (meth) acryloyloxyethyl hexahydrophthalimide are more preferred.

3. Electron beam curable composition for optical film formation This invention is an electron beam curable composition for optical film formation which contains the said (A) component and (B) component as an essential component.
As a manufacturing method of a composition, what is necessary is just to follow a conventional method, using (A) component and (B) component, using other components further as needed, and obtaining these by stirring and mixing. it can.

In the composition of the present invention, the cured product has a haze of 1.0% or less, and those having such a haze are particularly suitable for a polarizer protective film.
When the haze of the cured product exceeds 1.0%, the degree of polarization due to depolarization decreases.
In the present invention, haze represents the turbidity of a film, and means what is calculated | required from the ratio with respect to the total light transmitted light of diffuse transmitted light among the incident light to a film.

Further, the composition of the present invention needs to have a front surface of the cured product, an in-plane retardation of 40 ° oblique and a retardation in the thickness direction of 10 nm or less when measured at a thickness of 80 μm. Thereby, when it uses as a polarizer protective film, the liquid crystal display excellent in the viewing angle characteristic can be obtained. A cured product having a retardation larger than 10 nm has a problem of poor viewing angle characteristics.
Further, it is preferable that the in-plane retardation of the cured product when measured at a thickness of 80 μm is 1 nm or less, the in-plane retardation at an oblique angle of 40 ° is 5 nm or less, and the retardation in the thickness direction is 10 nm or less.

In the present invention, the retardation means a phase difference caused by birefringence when the transmitted light is considered to be decomposed into two linearly polarized lights orthogonal to each other when the linearly polarized light enters the optical film.
Specifically, the in-plane retardation (Re) and the thickness direction retardation (Rth) are nx, ny (where nx ≧ ny), and nz is the refractive index in the thickness direction. When the film thickness is d, it is a value defined by the following formula.
Re = (Nx-ny) * d
Rth = {(nx + ny) / 2−nz)} × d
Furthermore, in the present invention, the in-plane retardation at an angle of 40 ° means an in-plane retardation when linearly polarized light is incident on the optical film at an angle of 40 °.

The proportion of the component (A) and the component (B) may be appropriately set according to the purpose. However, the amount of the component (A) is 20 to 95% by weight based on the total amount of the component (A) and the component (B). The component (B) is preferably 5 to 80% by weight, more preferably (A) 30 to 90% by weight and (B) component 10 to 70% by weight.
By making the ratio of the component (A) 20% by weight or more, the cured product obtained can be excellent in flexibility, and by making it 95% by weight or less, the viscosity of the composition is lowered, It can be excellent in coatability.

  The composition of the present invention is an electron beam curable composition, and a conventionally known photopolymerization initiator can be blended if necessary, but preferably does not contain a photopolymerization initiator. By not containing a photopolymerization initiator, the obtained cured product can be excellent in heat resistance and light resistance.

The composition of the present invention essentially comprises the component (A) and the component (B), but various components can be blended depending on the purpose.
Specifically, an ethylenically unsaturated compound other than the components (A) and (B) [hereinafter referred to as component (C)], an organic solvent [hereinafter referred to as component (D)], a polymerization inhibitor and / or an antioxidant. Agents, light resistance improvers and the like.
Hereinafter, these components will be described.

-Component (C) The component (C) is an ethylenically unsaturated compound other than the components (A) and (B).
(C) A component is a component mix | blended as needed for the purpose of reducing the viscosity of the whole composition, and the purpose of adjusting other physical properties.

  Specific examples of the component (C) include (meth) acrylates (hereinafter referred to as “other (meth) acrylates”) other than the components (A) and (B).

  Other (meth) acrylates include compounds having two or more (meth) acryloyl groups (hereinafter referred to as “polyfunctional (meth) acrylates”).

Specific examples of the polyfunctional (meth) acrylate include bisphenol A EO-modified (n = 1 to 2) di (meth) acrylate, bisphenol A di (meth) acrylate, ethylene glycol di (meth) acrylate, and diethylene glycol di (meth). Acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol (n = 5-14) di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) Acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, polypropylene glycol (n = 5-14) di (meth) acrylate, 1,3-butylene glycol Di (meth) acrylate, 1,4-butanediol di (meth) acrylate, polybutylene glycol (n = 3 to 16) di (meth) acrylate, poly (1-methylbutylene glycol) (n = 5 to 20) di (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, Examples thereof include dicyclopentanediol di (meth) acrylate and bifunctional (meth) acrylate of tricyclodecane dimethylol di (meth) acrylate.
In the above, EO modification means ethylene oxide modification, and n means the number of repeating alkylene oxide units.

  As the component (C), only one kind of the aforementioned compounds may be used, or two or more kinds may be used in combination.

  The proportion of the component (C) may be appropriately set according to the purpose, and may be an amount that does not decrease the flexibility of the obtained cured product, but the total amount of the component (A) and the component (B) is 100 weights. The amount is preferably 1 to 100% by weight, more preferably 1 to 80% by weight based on the part.

-(D) component The composition of this invention contains the organic solvent of (D) component for the objective, such as improving the coating property to a base material.

Specific examples of the component (D) include hydrocarbon solvents such as n-hexane, benzene, toluene, xylene, ethylbenzene and cyclohexane;
Methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethanol, 2-isopropoxyethanol, 2-butoxy Ethanol, 2-isopentyloxyethanol, 2-hexyloxyethanol, 2-phenoxyethanol, 2-benzyloxyethanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, 1 Alcohol-based solvents such as methoxy-2-propanol and 1-ethoxy-2-propanol;
Ether solvents such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, bis (2-methoxyethyl) ether, bis (2-ethoxyethyl) ether and bis (2-butoxyethyl) ether;
Ketone solvents such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, diethyl ketone, butyl methyl ketone, methyl isobutyl ketone, methyl pentyl ketone, di-n-propyl ketone, diisobutyl ketone, phorone, isophorone, cyclohexanone and methylcyclohexanone Can be mentioned.

  As the component (D), one or more of the aforementioned compounds can be used.

  The proportion of the component (D) may be set as appropriate, but is preferably 10 to 90% by weight, more preferably 40 to 80% by weight in the composition.

● Polymerization inhibitor or / and antioxidant It is preferable to add a polymerization inhibitor or / and an antioxidant to the composition of the present invention, which can improve the storage stability of the composition of the present invention. .
As the polymerization inhibitor, hydroquinone, hydroquinone monomethyl ether, 2,6-di-tert-butyl-4-methylphenol, and various phenolic antioxidants are preferable. A secondary antioxidant or the like can also be added.
The total blending ratio of these polymerization inhibitors or / and antioxidants is preferably 0.001 to 3% by weight, more preferably 100 parts by weight of the total amount of component (A) and component (B). Is 0.01 to 0.5% by weight.

-Light resistance improver You may add light resistance improvement materials, such as a ultraviolet absorber and a light stabilizer, to the composition of this invention.
Examples of the ultraviolet absorber include 2- (2′-hydroxy-5-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, 2- (2 Benzotriazole compounds such as'-hydroxy-3'-t-butyl-5'-methylphenyl)benzotriazole;
Triazine compounds such as 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-iso-octyloxyphenyl) -s-triazine;
2,4-dihydroxy-benzophenone, 2-hydroxy-4-methoxy-benzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2, 4, 4 ' -Trihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3', 4,4'-tetrahydroxybenzophenone, or 2,2 Examples include benzophenone compounds such as'-dihydroxy-4,4'-dimethoxybenzophenone.
Examples of the light stabilizer include N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) -N, N′-diformylhexamethylenediamine, bis (1,2,6,6). -) Pentamethyl-4-piperidyl) -2- (3,5-ditertiarybutyl-4-hydroxybenzyl) -2-n-butylmalonate, bis (1,2,2,6,6-pentamethyl-4- Low molecular weight hindered amine compounds such as piperidinyl) sebacate; N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) -N, N′-diformylhexamethylenediamine, bis (1,2 Hindered amine light stabilizers such as high molecular weight hindered amine compounds such as 2,6,6-pentamethyl-4-piperidinyl) sebacate.
The blending ratio of the light fastness improver is preferably 0 to 5% by weight, more preferably 0 to 1% by weight, based on 100 parts by weight of the total amount of the component (A) and the component (B).

4). Method of Use The composition of the present invention can employ various methods of use depending on the purpose of forming the optical film.
Specifically, a method of applying a composition to a substrate and irradiating it with an electron beam to cure, applying a composition to a substrate and bonding it to another substrate, and further irradiating with an electron beam and curing And a method of pouring the composition into a mold having a recess and irradiating it with an electron beam to cure.

As the substrate, any of a peelable substrate and a substrate having no releasability (hereinafter referred to as “non-releasing substrate”) can be used.
Examples of the peelable substrate include a release-treated film and a surface untreated film having peelability (hereinafter collectively referred to as “release material”).
Examples of the release material include silicone-treated polyethylene terephthalate film, surface untreated polyethylene terephthalate film, surface untreated cycloolefin polymer film, and surface untreated OPP film (polypropylene).
In order to suppress the haze of the cured product of the composition of the present invention to 1.0% or less, it is preferable to use a surface untreated polyethylene terephthalate film or a surface untreated OPP film (polypropylene).

In order to achieve low haze or impart surface smoothness to the optical film obtained from the composition of the present invention, it is preferable to use a substrate having a surface roughness Ra of 150 nm or less as a peelable substrate. .
Specific examples of the substrate include a surface untreated polyethylene terephthalate film and a surface untreated OPP film (polypropylene).
In the present invention, the surface roughness Ra means a value obtained by measuring the surface roughness of the film and calculating an average roughness.

  Examples of the non-releasable base material include various plastics other than the above, cellulose acetate resins such as polyvinyl alcohol, triacetyl cellulose and diacetyl cellulose, acrylic resins, polyesters, polycarbonates, polyarylates, polyethersulfones, norbornene, etc. And cyclic polyolefin resins having a cyclic olefin as a monomer.

  As a coating method, it may be appropriately set depending on the purpose, and it is applied with a conventionally known bar coater, applicator, doctor blade, knife coater, comma coater, reverse roll coater, die coater, gravure coater, micro gravure coater, etc. The method of doing is mentioned.

  What is necessary is just to set suitably irradiation conditions, such as a dose in electron beam irradiation, according to the composition to be used, a base material, the objective, etc.

5). Optical Film The composition of the present invention can be preferably used for the production of an optical film.
Hereinafter, the optical film will be described.
Hereinafter, a part of the description will be given with reference to FIGS. 1 and 2.

5-1. Production method of optical film The production method of the optical film may be in accordance with conventional methods. For example, the composition can be produced by applying the composition to a substrate and then irradiating it with an electron beam.

FIG. 1 shows an example of a preferable method for producing an optical film composed of a release material / cured product.
In FIG. 1, (1) means a release material.
When the composition is a solventless type (FIG. 1: F1), the composition is applied to a release material [FIG. 1: (1)]. When the composition contains an organic solvent or the like (FIG. 1: F2), the composition is applied to a release material [FIG. 1: (1)] and then dried to evaporate the organic solvent or the like (FIG. 1: 1). -1).
By irradiating an electron beam onto the sheet having the composition layer (2) formed on the release material, an optical film composed of the release material / cured product is obtained. The electron beam is usually irradiated from the composition layer side, but can also be irradiated from the release material side.
In the above, if a release material is used as the substrate (1), an optical film composed of the release material / cured product can be produced.

  The coating amount of the composition of the present invention may be appropriately selected according to the application to be used, but it is preferable that the coating is performed so that the film thickness after drying the organic solvent or the like is 5 to 200 μm. Preferably it is 10-100 micrometers.

When the composition contains an organic solvent or the like, it is dried after coating to evaporate the organic solvent or the like.
What is necessary is just to set drying conditions suitably according to the organic solvent etc. to be used, and the method of heating to the temperature of 40-150 degreeC etc. are mentioned.

  What is necessary is just to set suitably irradiation conditions, such as a dose in electron beam irradiation, according to the composition to be used, a base material, the objective, etc.

FIG. 2 shows an example of a preferable method for producing an optical film composed of a release material / cured product / release material.
In FIG. 2, (1), (3), and (4) mean release materials.
When the composition is a solventless type (FIG. 2: F1), the composition is applied to a release material [FIG. 2: (1)]. When the composition contains an organic solvent or the like (FIG. 2: F2), the composition is applied to a release material [FIG. 2: (1)] and then dried to evaporate the organic solvent (FIG. 2: 2). -1). In the composition layer (2), a release material (3) is laminated and then irradiated with an electron beam, or after being irradiated with an electron beam, a release material, a cured product and a release material are formed in this order. An optical film is obtained.

Although the example which used the mold release material as a base material was described in the said FIG. 1 and 2, an optical film can also be manufactured using a non-mold release base material.
For example, in FIG. 1, a non-releasable substrate is used instead of the release material of (1), and is cured by irradiation with an electron beam in the same manner as described above. A film can also be produced.
In FIG. 2, a non-releasable base material is used as the release material of any one of (1), (3) and (4) and cured by electron beam irradiation in the same manner as described above. An optical film composed of a mold material / cured product / non-releasable substrate and an optical film composed of non-releasing substrate / cured product / non-releasing substrate can also be produced.
Specific examples of the embodiment include a method in which a polarizer is used as a non-releasing substrate, a composition is applied, and an electron beam is irradiated to directly form a protective film on the polarizer.

  In the above example, the optical film is produced by applying the composition to a substrate. However, when producing an optical film having a large film thickness, the composition is formed on a mold having a specific recess. An optical film can also be produced by pouring an object and irradiating an electron beam in the same manner as described above to cure the composition.

5-2. Use of optical film The optical film formed from the composition of the present invention has a haze of 1.0% or less and an in-plane retardation of 40 ° front and oblique directions and a retardation in the thickness direction when measured at a thickness of 80 μm. Are all 10 nm or less.
The optical film can be used for various optical applications, and more specifically, includes a polarizer protective film for polarizing plates used in liquid crystal display devices, a prism sheet support film, a light guide film, and the like. It is done.
Among these, the optical film formed from the composition of the present invention can be used publicly for a polarizer protective film.

  Hereinafter, a polarizing plate using a polarizer protective film (hereinafter simply referred to as “protective film”) formed from the composition of the present invention will be described.

-Polarizing plate A polarizing plate is the structure by which the protective film was laminated | stacked on the at least single side | surface of the polarizer.
As the polarizer, various materials can be used as long as they have a function of selectively transmitting linearly polarized light in one direction from natural light.
For example, an iodine polarizing film in which iodine is adsorbed and oriented on a polyvinyl alcohol film, a dye polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol film, and a dichroic dye is coated. Examples include a fixed coating type polarizer. These iodine-based polarizing films, dye-based polarizing films, and coating-type polarizers have a function of selectively transmitting linearly polarized light in one direction from natural light and absorbing linearly polarized light in the other direction. It is called a polarizer. Among these polarizers, it is preferable to use an absorption type polarizer having excellent visibility. The thickness of the absorption polarizer is preferably 5 to 40 μm.
The polarizing plate of the present invention is a polarizing plate in which the optical film of the present invention is laminated as a protective film on at least one surface of a polarizer, and is bonded by an adhesive.

Any adhesive can be used for the adhesive between the polarizer and the protective film in consideration of the respective adhesiveness.
Specific examples of the adhesive include polyvinyl alcohol-based water-based adhesives, solvent-based adhesives, hot-melt-based adhesives, and solvent-free adhesives, and solvent-free active energy ray-curable adhesives. It can be used suitably.
Examples of the active energy ray curable adhesive include a photo cation curable adhesive, a photo radical curable adhesive, and a hybrid adhesive that uses both photo cation curing and photo radical curing.
Examples of the photo cation curable adhesive include photo cation curable compounds such as epoxy compounds and oxetane compounds, and adhesives including a photo cation polymerization initiator.
Examples of the photo-radical curable adhesive include photo-radical curable compounds such as (meth) acrylates, vinyl ethers and vinyl compounds, and adhesives containing a photo-radical polymerization initiator.
Examples of the hybrid adhesive include an adhesive containing the above-described photocationic curable compound, photoradical curable compound, photocationic polymerization initiator, and photoradical polymerization initiator.

When it has a protective film on both surfaces of a polarizer, what has the protective film of this invention on both surfaces is the most preferable. However, if necessary, the protective film of the present invention can be used on one side, and a protective film other than the protective film of the present invention (hereinafter referred to as “other protective film”) can be used on the other side.
Examples of other protective films include cellulose acetate resin films such as triacetyl cellulose and diacetyl cellulose, acrylic resin films, polyester resin films, and cyclic polyolefin resin films containing cyclic olefins such as norbornene as monomers. Moreover, when using these as a protective film of a display side, the film which has phase difference may be sufficient.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the following, “parts” means parts by weight.

○ Production Example 1 [Production of component (A)]
In a 500 mL reaction vessel equipped with a stirrer, 200 g (0 of polyester polyol (P-2020 made by Kuraray Co., Ltd., esterified product of terephthalic acid and 3-methyl-1,5-pentanediol) having a number average molecular weight of 2,000 was added. 0.098 mol), 114.2 g of isobornyl acrylate as a diluent, 290 mg of dibutyltin dilaurate as a catalyst (1,000 ppm in the reaction solution), and 2,6-di-t-butyl-4-methyl as a polymerization inhibitor In a nitrogen atmosphere containing 5% by volume of oxygen, 290 mg of phenol was charged, and the mixture was heated to 70 ° C. while stirring. To the reaction solution, 43.7 g (0.196 mol) of IPDI was added all at once and reacted for 2 hours.
Thereafter, 22.8 g (0.196 mol) of 2-hydroxyethyl acrylate was added and reacted for 3 hours. The spectrum was measured with an infrared absorption spectrum apparatus (FT-IR Spectrum 100 manufactured by Perkin Elmer). After confirming consumption, a 30% isobornyl acrylate diluted solution containing urethane acrylate (hereinafter referred to as “UA-1”) was obtained.
The weight average molecular weight of UA-1 in terms of polystyrene (hereinafter referred to as Mw) was measured by gel permeation chromatography (solvent: tetrahydrofuran, column: HSPgel HR MB-L manufactured by Waters), and was 9,300.

○ Production Example 2 [ Production of urethane acrylate other than component (A)]
The same operation was performed except that the isocyanate was changed to 37 g of m-xylylene diisocyanate in Production Example 1, and a 30% isobornyl acrylate diluted solution containing urethane acrylate (hereinafter referred to as “UA-2”) was obtained.
The Mw of the obtained UA-2 was 10,400.

○ Production Example 3 [ Production of urethane acrylate other than component (A)]
The same operation as in Production Example 1 except that the isocyanate was changed to 34.2 g of tolylene-2,6-diisocyanate was performed to obtain a 30% isobornyl acrylate diluted solution containing urethane acrylate (hereinafter referred to as “UA-3”). It was.
Mw of UA-3 obtained was 8,500.

○ Production Example 4 [ Production of Polarizer]
A polyvinyl alcohol film having a thickness of 80 μm was swelled in a 30 ° C. water bath and then dyed in an aqueous iodine solution of 5 wt% (weight ratio: iodine / potassium iodide = 1/10). Then, it is immersed in an aqueous solution containing 3% by weight boric acid and 2% by weight potassium iodide, and further up to 5.5 times in an aqueous solution containing 4% by weight boric acid and 3% by weight potassium iodide at 55 ° C. After uniaxial stretching, it was immersed in a 5 wt% potassium iodide aqueous solution. Then, it dried for 1 minute in 70 degreeC oven, and obtained the 30-micrometer-thick polarizer (henceforth polarizer P).
About the obtained polarizer P, when the polarization degree and the single transmittance were measured using the spectrophotometer with a polarizing prism (Shimadzu Corporation UV-2200), it was 99.99% and 43.1%, respectively. there were.

○ Production Example 5 [ Production of UV-curable adhesive]
50 parts of bisphenol A diglycidyl ether (Japan Epoxy Resin Co., Ltd. jER807), 20 parts of tetrahydrofurfuryl acrylate (THF-A, Osaka Organic Chemical Co., Ltd.), 4-hydroxylbutyl acrylate (Nippon Kasei Co., Ltd.) 4-HBA), 30 parts of photopolymerization initiator (hereinafter referred to as “photoinitiator”) iodonium (4-methylphenyl) [4- (2-methylpropyl) phenyl] -hexafluorophosphate (BASF Japan ( IRGACURE250 (made by Co., Ltd.) 4 parts, 1,4-diethylthioxanthone (Nippon Kayaku Co., Ltd. Kayacure DETX-s) 1 part is put into a stainless steel container, and stirred with a magnetic stirrer until it is uniform, UV curing A mold adhesive (hereinafter referred to as adhesive UVX) was obtained.

(1) Example (Production of composition)
The components shown in Table 1 below were charged in a stainless steel container at the ratio shown in Table 1, and stirred with a magnetic stirrer while heating to obtain a composition.

The abbreviations in Table 1 mean the following.
UCA002: Polycarbonate-based non-yellowing urethane acrylate, Art Resin UCA-002 [Mw 7,000] manufactured by Negami Kogyo Co., Ltd.
M1600: Polyether urethane acrylate, Aronix M-1600 manufactured by Toagosei Co., Ltd.
-IBXA: Isobornyl acrylate, IBXA manufactured by Osaka Organic Chemical Industry Co., Ltd.
M140: N-acryloyloxyethylhexahydrophthalimide, Aronix M-140 manufactured by Toagosei Co., Ltd.
Dc1173: 2-hydroxy-2-methyl-1-phenylpropan-1-one, DAROCUR-1173 manufactured by BASF Japan

(3) Examples 5 to 8 and Comparative Examples 7 to 8 (Production of optical film by electron beam curing)
Examples 1 to 4 and a film “Lumirror 50-T60” manufactured by Toray Industries, Inc. having a width of 300 mm and a length of 300 mm (surface-untreated polyethylene terephthalate film, thickness 50 μm, surface roughness Ra111 nm, hereinafter referred to as “Lumirror”) The compositions obtained in Comparative Examples 3 to 4 were heated and coated with an applicator so that the film thickness was 80 μm.
Then, after laminating 300 mm width x 300 mm length on the composition layer, an acceleration voltage of 200 kV, a dose of 50 kGy (adjusted by the beam current and the conveyance speed), oxygen by an electron beam irradiation device manufactured by NHV Corporation, oxygen Electron beam irradiation was performed under conditions of a concentration of 300 ppm or less to obtain an optical film.
After curing, the film was peeled off from the untreated polyethylene terephthalate film, and used for evaluation of total light transmittance, haze, light resistance test, in-plane and thickness direction retardation, and solvent resistance described later.

(4) Comparative Examples 5 to 6 (Production of optical film by ultraviolet curing)
The UV curable composition obtained in Comparative Examples 1 and 2 was heated on a Lumirror having a width of 300 mm and a length of 300 mm, and coated with an applicator so that the film thickness was 80 μm.
Then, after laminating 300 mm width x 300 mm length on the composition layer, a conveyor type ultraviolet irradiation device (high pressure mercury lamp, lamp height 12 cm, 365 nm irradiation intensity 400 mW / cm ² manufactured by Eye Graphics Co., Ltd.) (Measurement value of UV POWER PUCK manufactured by Fusion UV Systems Japan Co., Ltd.) was adjusted to carry out ultraviolet irradiation with an integrated light amount of 1,000 mJ / cm ² to obtain an ultraviolet curable optical film.
After curing, the film was peeled off from the untreated polyethylene terephthalate film and used for evaluation described later.

(5) Comparative Example 9 (Production of optical film by electron beam curing)
A release film “Celapeel BX8” manufactured by Toray Film Processing Co., Ltd. (silicone-treated polyethylene terephthalate film, thickness 38 μm, surface roughness Ra 363 nm, hereinafter referred to as “therapy”) as a release material, and Example 1 except that Example 1 was used as a composition Produced optical films by electron beam curing in the same manner as in Examples 5-8 and Comparative Examples 7-8.
After curing, it was peeled off from the silicone-treated polyethylene terephthalate film and used for the evaluation described later.

[Total light transmittance and haze]
About the optical film obtained by the Example and the comparative example, the total light transmittance and haze were measured using the haze meter [Nippon Denshoku Industries Co., Ltd. NDH2000]. The results are shown in Table 2.

(Light resistance test)
Initial YI (Yellowing Index) of optical films obtained in Examples and Comparative Examples, and YI change after being left for 500 hours in an ultraviolet fade meter (UV Long Life Fade Meter FAL-5H type manufactured by Suga Test Instruments Co., Ltd.) The light resistance of the optical film was evaluated by measuring (ΔYI). The results are shown in Table 2.
In addition, the YI value was measured using a high-speed integrating sphere type spectral transmittance measuring device [SPECTROTOPOMETER DOT-3C manufactured by Murakami Color Research Laboratory Co., Ltd.].

[In-plane and thickness direction retardation]
About the optical film obtained by the Example and the comparative example, in-plane retardation (henceforth "0 degree Re" respectively) using the phase difference measuring device (Oji Scientific Instruments Co., Ltd. product KOBRA-21ADH) and diagonal 40 degrees. And “40 ° Re”) and thickness direction retardation (hereinafter referred to as “Rth”). The results are shown in Table 2.

[Solvent resistance]
About the solvent resistance (ethyl acetate) of the optical film obtained by the Example and the comparative example, it evaluated on the following reference | standard by the spot test. The results are shown in Table 2.
○: No change in appearance ×: Whitening due to solvent erosion

The abbreviations in Table 2 mean the following.
-TAC: Triacetyl cellulose film, Fujifilm manufactured by Fuji Film Co., Ltd. (with UVA, 80 μm)

Examples 5 to 8 are optical films obtained by irradiating the compositions from Examples 1 to 4 which are the compositions of the present invention with an electron beam, and have a yellowing degree after a light resistance test even without UVA. Small, haze, oblique 40 ° front and retardation in the thickness direction were small, and the solvent resistance was good.
On the other hand, Comparative Examples 5 and 6 are optical films produced by irradiating the compositions of Comparative Examples 1 and 2 containing a photoinitiator with ultraviolet rays, although they contain the components (A) and (B). Yes, the yellowing degree after the light resistance test was larger than those of the optical films of Examples 5 to 8, and particularly the thickness direction retardation was large.
Comparative Example 7 is an optical film produced from the composition of Comparative Example 3 containing urethane acrylate (UA-2) produced from a slightly yellowing organic diisocyanate different from component (A), and after the light resistance test The degree of yellowing was large.
Comparative Example 8 is an optical film produced from the composition of Comparative Example 4 containing urethane acrylate (UA-3) produced from a yellowing organic diisocyanate different from component (A), and the yellow after the light resistance test. The degree of change was very large.
In Comparative Example 9, the composition of Example 1 was used, but since the surface roughness Ra of the release material was larger than 150 nm, the haze of the cured product was larger than 1.0%.
Comparative Example 10 is a conventional triacetyl cellulose, but the initial yellowing was large because it contained UVA. In addition, the retardation in the oblique 40 ° front and thickness directions was large, and the solvent resistance was poor due to the thermoplastic resin.

(6) Examples 9 to 10 and Comparative Examples 11 to 12 (Production of Polarizing Plate)
The optical film or TAC film obtained in Examples 5 to 6 and Comparative Example 9 was used as a polarizer protective film, and was bonded to both sides of the polarizer P via an adhesive UVX, and then manufactured by Eye Graphics Co., Ltd. The conveyor speed is adjusted by a conveyor type ultraviolet irradiation device (high pressure mercury lamp, lamp height 15 cm, irradiation intensity 370 mW / cm ^{2 of} 365 nm (measured value of UV POWER PUCK manufactured by Fusion UV Systems Japan Co., Ltd.)) An ultraviolet ray with an integrated light quantity of 220 mJ / cm ² was applied to obtain a polarizing plate (width 100 mm × length 100 mm).
In addition, no corona treatment was performed on any of the polarizer protective films.

(Measurement of degree of polarization and single transmittance)
About the polarizing plate obtained by the Example and the comparative example, the polarization degree and the single-piece | unit transmittance were measured using the spectrophotometer with a polarizing prism (Shimadzu Corporation UV-2200). The results are shown in Table 3.

[Adhesiveness between polarizer protective film and polarizer]
In the polarizing plates obtained in the examples and comparative examples, the adhesive properties of the polarizer protective film and the polarizer P were evaluated by the following criteria when twisted by hand twisting. The results are shown in Table 3.
A: The polarizer and the polarizer protective film are integrated with each other so that peeling does not occur.
X: Peeling is recognized between the polarizer and the polarizer protective film.

Examples 9 and 10 are polarizing plates using the optical films obtained in Examples 5 to 6 which are the compositions of the present invention, the performance of the polarizer P is maintained, and the corona treatment is not performed. Adhesiveness was good.
On the other hand, although the comparative example 11 is a polarizing plate using the optical film obtained in the comparative example 9, although adhesiveness is favorable, since the haze of an optical film is high, the performance of the polarizer P is maintained. The degree of polarization was not reduced. Moreover, although the comparative example 12 is a polarizing plate using the conventional TAC film, although the performance of the polarizer P was maintained, since the corona treatment was not performed, adhesiveness was bad.

The electron beam curable composition for forming an optical film of the present invention can be suitably used for the production of an optical film.
Furthermore, as described in detail above, the optical film of the present invention is suitably used in a polarizer protective film application.

FIG. 1 shows an example of production of an optical film using the composition of the present invention. FIG. 2 shows an example of production of an optical film using the composition of the present invention.

Claims (17)

Urethane (meth) acrylate (A) and one (meth) which is a reaction product of at least one diol selected from polycarbonate diol, polyester diol or polyether diol, non-yellowing organic diisocyanate and hydroxyl group-containing (meth) acrylate Including a compound (B) having an acryloyl group,
An optical film or sheet in which the haze of the cured product is 1.0% or less and all of the front and oblique in-plane retardation of the cured product and the retardation in the thickness direction are 10 nm or less when measured at a thickness of 80 μm. An electron beam curable composition for forming.   2. The optical film according to claim 1, wherein the in-plane retardation of the cured product when measured at a thickness of 80 [mu] m is 1 nm or less, the in-plane retardation at 40 [deg.] Is 5 nm or less, and the retardation in the thickness direction is 10 nm or less. Or the electron beam curable composition for sheet formation.   The electron beam curable composition for optical film or sheet formation according to claim 1 or 2, wherein the component (B) is a compound having a glass transition temperature of a homopolymer of 50 ° C or higher.   The composition according to any one of claims 1 to 3, comprising 20 to 95% by weight of (A) component and 5 to 80% by weight of component (B), based on the total amount of component (A) and component (B). 2. An electron beam curable composition for forming an optical film or a sheet.   The optical film or sheet forming electron beam curable composition according to any one of claims 1 to 4, wherein the composition does not contain a photopolymerization initiator. The electron beam irradiation cured product of the composition according to any one of claims 1 to 5, is formed into a film or a sheet,
An optical film or sheet having a haze of 1.0% or less and an in-plane retardation of 40 ° and an in-plane retardation and a retardation in the thickness direction of 10 nm or less when measured at a thickness of 80 μm.   7. The optical film or sheet according to claim 6, wherein the in-plane retardation at the front when measured at a thickness of 80 [mu] m is 1 nm or less, the in-plane retardation at 40 [deg.] Is 5 nm or less, and the retardation in the thickness direction is 10 nm or less.   A polarizer protective film comprising the optical film or sheet according to claim 6.   A film-like or sheet-like substrate (hereinafter collectively referred to as “sheet-like substrate”), an electron beam irradiation cured product of the composition according to any one of claims 1 to 5 and a sheet-like substrate. An optical film or sheet in which materials are formed in this order.   The optical film or sheet according to claim 9, wherein either one or both of the sheet-like base materials are base materials having a surface roughness Ra of 150 nm or less.   The manufacturing method of the optical film or sheet | seat which irradiates an electron beam from the coating surface side or the sheet-like base material side, after apply | coating the composition of any one of Claims 1-5 to a sheet-like base material. .   The method for producing an optical film or sheet according to claim 11, wherein the sheet-like substrate is a peelable substrate.   The method for producing an optical film or sheet according to claim 12, wherein the sheet-like substrate is a peelable substrate, and the surface roughness Ra is 150 nm or less.   After apply | coating the composition of any one of Claims 1-5 to a sheet-like base material, and bonding another sheet-like base material to the coating surface of a composition, the said sheet-like base material The manufacturing method of the optical film or sheet | seat which irradiates an electron beam from either side.   The method for producing a resin film or sheet according to claim 14, wherein either one or both of the sheet-like substrates are peelable substrates.   The method for producing an optical film or sheet according to claim 15, wherein the sheet-like substrate is a peelable substrate, and the surface roughness Ra is 150 nm or less.   A polarizing plate in which the polarizer protective film according to claim 8 is laminated on at least one surface of a polarizer formed from a polyvinyl alcohol-based resin, and the polarizer is attached to the polarizer protective film via an adhesive layer. A bonded polarizing plate.

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