JP2012194212A - Electron beam curable composition for lens sheet support film formation, lens sheet support film, and lens sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam curable composition for lens sheet support film formation, having high light transmittance of a cured product thereof, small in-plane retardation in a front direction and an oblique direction, and also excellent solvent resistance, and to provide a lens sheet support film and a lens sheet obtained from the composition.SOLUTION: The electron beam curable composition for lens sheet support film formation includes: urethane (meta) acrylate (A) which is a reactant of polycarbonate diol, polyester diol or polyether diol, non-yellow organic diisocyanate, and hydroxyl group-containing (meta) acrylate; and a compound (B) with one (meta) acryloyl group. The in-plane retardation of the cured product in a front direction and an oblique direction of 40 degrees thereto are 5 nm or less.

Description

The present invention relates to an electron beam curable composition used for forming a lens sheet support film or sheet, a lens sheet support film or sheet obtained by curing the composition, and a lens using the support film or sheet. The sheet belongs to these technical fields.
In the following, for the sake of convenience, unless otherwise specified, “support film or sheet” is described as “support film”. Further, acrylate or methacrylate is represented as (meth) acrylate.

  In recent years, color liquid crystal display devices have been widely used in various fields such as portable notebook personal computers, portable liquid crystal televisions using color liquid crystal panels, or video integrated liquid crystal televisions. A liquid crystal display device basically includes a backlight and a liquid crystal display element unit. There are two types of backlights: a direct-light method in which a light source is provided directly under a liquid crystal display element and an edge light method in which a light source is provided on the side surface of a light guide. . This edge light system is a backlight of a system in which a light source is disposed on the side surface of a plate-shaped light guide to emit light over the entire surface of the light guide, and a prism with a specific shape is used for the purpose of improving front luminance. A prism sheet that is a large number of formed lens sheets is used.

  However, as the support film for the prism sheet, a polyester-based resin film is mainly used. However, since the light transmittance of the support film is low, there is a limit to improving the luminance, and the retardation of the support film is high, so that the liquid crystal display As the size increases, the luminance unevenness is remarkably affected.

  Therefore, a transparent thermoplastic acrylic resin has been studied as a material for a prism sheet support film that replaces the conventional polyester resin film.

  Patent Documents 1 and 2 disclose a thermoplastic acrylic resin as a prism sheet support film, but the solvent resistance is insufficient, and the active energy ray-curable resin used in the prism forming resin is not suitable. Problems such as erosion of low molecular weight monomer components and a decrease in transparency due to erosion of the solvent of the hard coating agent applied to the back surface of the prism sheet may occur.

JP 2005-326613 A Japanese Patent No. 4282660

  The present invention solves the above-mentioned problems, and the cured product has a high light transmittance, small in-plane retardation in the front and oblique directions, and further excellent in solvent resistance. An object is to provide a lens sheet support film and a lens sheet obtained from the composition, the composition.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a urethane (meth) acrylate produced from a specific diol, a non-yellowing organic diisocyanate and a hydroxyl group-containing (meth) acrylate and one 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 of the cured product can solve the above problems, and has completed the present invention.

According to the composition of the present invention, the in-plane retardation in the front and oblique directions of the obtained cured product is as small as 5 nm or less, whereby the light transmittance of the cured product is high, and after the transparency and light resistance test Excellent balance and excellent solvent resistance.
Therefore, the lens sheet support film of the present invention can be suitably used as a support film in the production of lens sheets, and more preferably can be used as a support film for a prism sheet.

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)”),
It is related with the electron beam curable composition for lens sheet support film formation whose in-plane retardation of the hardened | cured material when measured at 80 micrometers in thickness and diagonal 40 degrees is 5 nm or less.
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. The electron beam curable composition for forming a lens sheet support film The present invention is an electron beam curable composition for forming a lens sheet support film comprising the component (A) and the component (B) as essential components.
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.

Further, the composition of the present invention needs to have an in-plane retardation of 5 nm or less at the front of the cured product and at an angle of 40 ° when measured at a thickness of 80 μm. Thereby, when it uses as a support film for lens sheets, the brightness nonuniformity of the lens sheet can be suppressed. When the retardation of the cured product is larger than 5 nm, there is a problem that uneven brightness occurs.
Further, it is preferable that the in-plane retardation at the front of the cured product when measured at a thickness of 80 μm is 1 nm or less and the in-plane retardation at an oblique angle of 40 ° is 5 nm or less.

In the present invention, the retardation means a phase difference caused by birefringence when the transmitted light is decomposed into two orthogonal linearly polarized lights when linearly polarized light enters the lens sheet support film.
Specifically, the in-plane retardation (Re) is a value defined by the following equation when the main refractive index in the film plane is nx, ny (where nx ≧ ny), and the film thickness is d. is there.
Re = (Nx-ny) * d
Further, in the present invention, the in-plane retardation at an angle of 40 ° means an in-plane retardation when linearly polarized light is incident at an angle of 40 ° to the lens sheet support film.

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, And 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 lens sheet support 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 give a low haze or impart surface smoothness to the lens sheet support 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. .
As specific examples of the substrate, it is preferable to use a surface untreated polyethylene terephthalate film or a surface untreated cycloolefin polymer film 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). Lens Sheet Support Film The composition of the present invention is used for producing a lens sheet support film.
Hereinafter, the lens sheet support film will be described.
Hereinafter, a part of the description will be given with reference to FIGS. 1 and 2.

5-1. Manufacturing method of lens sheet supporting film The manufacturing method of the lens sheet supporting film may be according to a conventional method. For example, the composition may be applied to a substrate and then irradiated with an electron beam.

FIG. 1 shows an example of a preferred method for producing a lens sheet support 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 to the sheet having the composition layer (2) formed on the release material, a lens sheet support 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), a lens sheet support 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 a lens sheet support 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. A lens sheet support film is obtained.

  In the above example, the lens sheet support film is manufactured by coating the composition on the substrate. However, when manufacturing a lens sheet support film having a large film thickness, a mold having a specific recess is used. The lens sheet support film can also be produced by pouring the composition into a frame or the like and irradiating with an electron beam in the same manner as described above to cure the composition.

5-2. Use of lens sheet support film The lens sheet support film formed from the composition of the present invention has an in-plane retardation of 5 nm or less when measured at a thickness of 80 μm in front and at an angle of 40 °.
The lens sheet support film can be used for various optical applications for producing a lens sheet, and more specifically, a prism lens sheet (hereinafter referred to as “prism sheet”), a lenticular lens sheet, and the like. .
Among these, the lens sheet support film formed from the composition of the present invention can be suitably used as a support film for a prism sheet.
Hereinafter, the prism sheet formed from the composition of the present invention will be described.

● Prism sheet The prism sheet is used for the purpose of improving the front luminance of the liquid crystal display device, and a large number of prisms having a specific shape are formed on a support film.
In the prism formed on the prism sheet support film of the present invention, the active energy ray-curable composition is applied to a mold such as a mold or a resin mold corresponding to the prism pattern, and the surface of the composition is smoothed. Then, the prism sheet support film of the present invention is overlaid and irradiated with an active energy ray to be cured.
With this method, it is possible to easily manufacture a fine pitch prism pattern that can cope with finer color filters associated with colorization of liquid crystal display devices without impairing optical characteristics.

In the prism sheet of the present invention, the resin constituting the prism is preferably a cured product of the active energy ray-curable composition. Such an active energy ray-curable composition may be any composition that is excellent in transparency, but is preferably a composition that gives a crosslinked cured polymer from the viewpoint of the mechanical properties of the triangular prism sheet.
Examples of such a composition include a (meth) acrylate-based composition containing (meth) acrylate, a photocationic composition containing an epoxy compound or an oxetane compound, and a polyene-thiol-based composition.
As a component of these compositions, a highly transparent (meth) acrylate-based composition is particularly preferable. For example, a prepolymer such as polyester (meth) acrylate, epoxy (meth) acrylate, polyurethane (meth) acrylate, and the like, Examples include combinations with functional or polyfunctional (meth) acrylate monomers.

  Examples of the active energy ray used for curing the active energy ray-curable resin composition include electron rays, ion rays and other particle rays, γ rays, X rays, ultraviolet rays, visible rays, electromagnetic rays such as infrared rays, and the like. Electron beams and ultraviolet rays are particularly preferable from the viewpoint of curing speed and production equipment.

As a method of applying the active energy ray-curable composition to the mold, the necessary composition may be applied to the mold by a single application, but the pattern portion of the mold on which the prism pattern is formed is uniformly formed. It is applied by a two-step application process, which is a first application process for applying a composition for forming a prism part tip so as to fill, and a second application process for applying a composition for forming a prism part base thereon. Also good.
In this case, it is preferable to smoothen the surface of the composition coating layer after coating after the first coating step, thereby obtaining a uniform triangular prism sheet free from thickness spots. In addition, when the composition layer is cured or semi-cured by irradiating active energy rays after the first coating layer is smoothed, the generation of bubbles due to the flow of the first composition coating layer is suppressed in the second coating step. This is preferable because it is possible.

The front luminance of the obtained prism sheet is preferably 300 to 600 cd / m ² , more preferably 300 to 500 cd / m ² . By setting this value, the brightness of the backlight can be made uniform.
In the present invention, the front luminance means that a liquid crystal display device using a sidelight type backlight having a surface luminance of 7000 cd / m ² is used, and a prism is provided on the obtained prism sheet on the backlight. This means that the surface brightness is set in front of the liquid crystal display part.

  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. 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 UV-curable composition for prism formation]
45 parts of ethylene oxide-modified bisphenol A dimethacrylate (Hankuri FA-521A manufactured by Hitachi Chemical Co., Ltd.), 25 parts of ethylene oxide-modified bisphenol A diacrylate (Aronix M-211B manufactured by Toagosei Co., Ltd.), tetrahydrofurfuryl acrylate 30 parts (THF-A manufactured by Osaka Organic Chemical Industry Co., Ltd.), 2-hydroxy-2-methyl-1-phenylpropan-1-one (BASF Japan) as a photopolymerization initiator (hereinafter referred to as “photoinitiator”) 3 parts DAROCUR-1173 manufactured by Co., Ltd. was put into a stainless steel container and stirred until it became uniform with a magnetic stirrer while heating, and a prism forming resin UV curable resin (hereinafter referred to as UVX for prism) was used. 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

(2) Examples 5 to 8 and Comparative Examples 7 to 8 (Production of lens sheet support film by electron beam curing)
Examples 1 to 4 and Comparative Examples 3 to 4 were prepared on a film “Lumirror 50-T60” (surface untreated polyethylene terephthalate film, thickness 50 μm, hereinafter referred to as “Lumirror”) manufactured by Toray Industries, Inc. having a width of 300 mm and a length of 300 mm The composition obtained in (1) was heated and coated with an applicator so that the film thickness became 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 a lens sheet support 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.

(3) Comparative Examples 5-6 (Production of lens sheet support film by UV 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 lens sheet support film. .
After curing, the film was peeled off from the untreated polyethylene terephthalate film and used for evaluation described later.

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

(Light resistance test)
The lens sheet support films obtained in Examples and Comparative Examples were initially left for YI (Yellowing Index) and an ultraviolet fade meter [UV Long Life Fade Meter FAL-5H type manufactured by Suga Test Instruments Co., Ltd.] for 500 hours. The light resistance of the lens sheet support film was evaluated by measuring the YI change (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]
With respect to the lens sheet support films obtained in Examples and Comparative Examples, front and oblique in-plane retardation (hereinafter referred to as “0 °” respectively) using a phase difference measuring device (KOBRA-21ADH manufactured by Oji Scientific Instruments). Re ”and“ 40 ° Re ”). The results are shown in Table 2.

[Solvent resistance]
The solvent resistance (ethyl acetate) of the lens sheet support films obtained in the examples and comparative examples was evaluated according to the following criteria by a spot test. The results are shown in Table 2.
○: No change in appearance ×: Solvent erosion

The abbreviations in Table 2 mean the following.
PET: polyethylene terephthalate film, Toyobo Co., Ltd. Cosmo Shine A-4300 (100 μm)

Examples 5 to 8 are lens sheet support films obtained by irradiating the compositions of Examples 1 to 4 which are the compositions of the present invention with an electron beam, the degree of yellowing and in-plane retardation after a light resistance test. The solvent resistance was good.
In contrast, although Comparative Examples 5 and 6 contain the components (A) and (B), the lens sheet support produced by irradiating the compositions of Comparative Examples 1 and 2 containing a photoinitiator with ultraviolet rays. It was a film, and the yellowing degree and retardation after a light resistance test were larger than the lens sheet support film of Examples 5-8.
Comparative Example 7 is a lens sheet support film produced from the composition of Comparative Example 3 containing urethane acrylate (UA-2) produced from a hardly yellowing organic diisocyanate different from the component (A), and a light resistance test. Later degree of yellowing was great.
Comparative Example 8 is a lens sheet support 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 after light resistance test The yellowing degree of was very large.
Although Comparative Example 9 is a conventional polyethylene terephthalate, the retardation was large and the solvent resistance was poor because it was a thermoplastic resin.

(4) Examples 9-10 and Comparative Examples 10-11 (Manufacture of prism sheets)
One side of the prism sheet support film or PET film obtained in Examples 5 to 6 and Comparative Example 2 is coated with UVX for prism, and a lens pattern having a large number of prism rows in parallel with a pitch of 50 μm and an apex angle of 95 ° is brass. A die formed by cutting in a flat plate state was pressed onto a flat plate. Next, a conveyor type ultraviolet irradiation device manufactured by Eye Graphics Co., Ltd. (high pressure mercury lamp, lamp height 12 cm, irradiation intensity 400 mW / cm ^{2 at} 365 nm (measurement value of UV POWER PUCK manufactured by Fusion UV Systems Japan Co., Ltd.)) ), The conveyor speed was adjusted, and UV irradiation with an integrated light quantity of 1,000 mJ / cm ² was performed to cure. Then, it peeled from the metal mold | die and the triangular prism sheet was obtained.

[Measurement of luminance characteristics]
Using a liquid crystal display device using an edge light type cold cathode tube backlight having a surface brightness of 7,000 cd / m ² , the prism sheets obtained in the examples and comparative examples are provided on the backlight. The front surface brightness was measured with a luminance meter (Topcon, BM-7 automatic luminance meter). In addition, the surface brightness | luminance when not using a prism sheet was 200 cd / m < ² >. The results are shown in Table 3.

In Examples 9 and 10, the prism sheet using the prism sheet support film obtained in Examples 5 to 6, which is the composition of the present invention, had a good luminance improvement effect.
In contrast, in Comparative Examples 10 and 11, the prism sheet support film obtained in Comparative Example 2 and the prism sheet using the conventional PET film were inferior in luminance improvement effect.

  The electron beam curable composition for forming a lens sheet support film of the present invention can be used for production of a lens sheet support film, and more preferably can be used for a prism sheet support film.

FIG. 1 shows an example of production of a lens sheet support film using the composition of the present invention. FIG. 2 shows an example of the production of a lens sheet support film using the composition of the present invention.

Claims (14)

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,
A lens sheet support film or an electron beam curable composition for forming a sheet, wherein the cured product has an in-plane retardation of 5 nm or less when measured at a thickness of 80 μm.   The lens sheet support film or electron beam curable type for sheet formation according to claim 1, wherein the in-plane retardation of the cured product when measured at a thickness of 80 µm is 1 nm or less and the in-plane retardation at an oblique angle of 40 ° is 5 nm or less. Composition.   The lens sheet support film or the electron beam curable composition for sheet formation according to claim 1, 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). The lens sheet supporting film or the electron beam curable composition for forming a sheet.   The lens composition according to any one of claims 1 to 4, wherein the composition does not contain a photopolymerization initiator, or the electron beam curable composition for sheet formation.   The electron beam irradiation cured product of the composition according to any one of claims 1 to 5 is formed in a film shape or a sheet shape, and has a front surface and an oblique angle of 40 ° when measured at a thickness of 80 µm. A lens sheet support film or sheet having an in-plane retardation of 5 nm or less.   The lens sheet supporting film or sheet according to claim 6, wherein the in-plane retardation at the front when measured at a thickness of 80 μm is 1 nm or less and the in-plane retardation at 40 ° is 5 nm or less.   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. A lens sheet support film or sheet in which the materials are formed in this order.   After applying the composition of any one of Claims 1-5 to a sheet-like base material, the lens sheet support film or sheet | seat which irradiates an electron beam from the coating surface side or a sheet-like base material side. Production method.   The method for producing a lens sheet supporting film or sheet according to claim 9, wherein the sheet-like substrate is a peelable substrate.   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 A method for producing a lens sheet supporting film or sheet, which is irradiated with an electron beam from either side.   The method for producing a lens sheet supporting film or sheet according to claim 11, wherein either or both of the sheet-like substrates are peelable substrates.   A lens sheet in which a prism is formed on the support film or sheet according to claim 6.   The lens sheet according to claim 13, wherein the prism is formed from a cured product of an active energy ray-curable composition.

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