JP5023769B2 - Optical film - Google Patents

Description

  The present invention relates to a specific surface-treated silica particle, a resin composition containing the silica particle, and an optical film using the resin composition.

In displays such as PDP (plasma display), CRT (cathode ray tube), and LCD (liquid crystal display), light enters the screen from the outside, and this light is reflected to make it difficult to view the display image (decrease in visibility). In particular, in recent years, with the increase in the size of flat panel displays, it has become increasingly important to solve the above problems.
In order to solve such a problem, various antireflection treatments and antiglare treatments have been taken for various displays so far.

  As the anti-glare treatment, for example, a method of sticking an anti-glare film on a display screen of an image display device is used, and specifically, by inorganic fine particles such as silica and ionizing radiation on a base film by a wet process. A laminate in which an antiglare layer containing a cured resin is laminated is known (for example, see Patent Document 1). Further, an antiglare antireflection film is proposed in which a hard coat layer containing amorphous silica particles and a low refractive index layer having a specific refractive index are provided on a transparent support ( Patent Document 2).

  In addition, as an antireflection treatment, for example, a method of sticking an antireflection film on a display screen of an image display device is taken, and specifically, a hard coat containing translucent particles on a transparent support. An antireflection film having a layer and a low refractive index layer containing hollow silica has been proposed (see Patent Document 3).

JP 2002-36452 A JP 2000-258606 A JP 2005-301246 A

Optical films such as the antireflection film and the antiglare film as described above are often used by being attached to a polarizing plate as a display member. In general, a polarizing plate uses a polyvinyl alcohol film as a substrate, and an optical film may be subjected to a saponification treatment with a sodium hydroxide aqueous solution in order to ensure adhesion at the time of attachment.
However, in the optical film using silica particles for the low refractive index layer, the hard coat layer, and the antiglare layer as described above, there is a problem that silica is hydrolyzed under alkalinity and easily dissolved. For this reason, at the time of saponification, in order to protect these silica particles from an alkali, it is necessary to protect a silica from an alkali with a protective film etc., and the complicated work process was forced.
An object of the present invention is to provide silica particles that do not elute even during saponification without using such a protective film and an optical film using the silica particles.

As a result of intensive studies to achieve the above object, the present inventors have found that the above problems can be solved by using silica treated with a specific organic silicate. The present invention has been completed based on these findings.
That is, the present invention
[1] An optical film having a refractive index control layer formed by coating a resin composition containing 3 to 70% by mass of silica particles on an ionizing radiation curable resin binder on a transparent substrate,
The silica particles have a hollow structure having an average particle diameter of 1 to 100 nm, and a particle element treated with oligomer having silethylene structure or an oligomer having the silethylene structure silica having a silethylene group An optical film having antireflection performance, which is a copolymer having a copolymerization ratio of 40:60 to 60:40 (mass ratio) between the compound and another silane compound;
[2] The optical film having antireflection performance according to the above [1], wherein the silica particles are treated with 3 to 30 parts by mass of the oligomer having a silethylene structure with respect to 100 parts by mass of silica , and [3] The optical film having antireflection performance according to the above [1] or [2], wherein the silica particles are further treated with 1 to 10 parts by mass of a silane coupling agent with respect to 100 parts by mass of silica ,
Is to provide.

  According to the present invention, silica particles having alkali resistance can be provided. Moreover, according to this invention, the other functional group for providing further functionality to this silica particle can be introduce | transduced. Since the optical film containing the silica particles exhibits high alkali resistance, silica does not elute even in the saponification treatment, and it is not necessary to use a protective film, so that the manufacturing process of the optical film can be greatly simplified. it can.

  The silica particles of the present invention are characterized by being treated with an oligomer having a silethylene structure. Specifically, the oligomer having a silethylene structure is a copolymer of a silica compound having a silethylene group and another silane compound. Examples of the silica compound having a silethylene group include ethylenebistrimethoxysilane, ethylenebistriethoxysilane, ethylenebisdimethoxymethylsilane, 4,7-diethoxy-4,7-dimethyl-3,8-dioxa-4,7-disiladecane, and the like. Is mentioned. Other silane compounds include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraoctylsilane, methyltrimethoxysilane, ethyltriethoxysilane, methyltriisopropoxysilane, dimethyldimethoxysilane, Examples thereof include vinyltrimethoxysilane and hexaethoxydisiloxane.

About the copolymerization ratio of the said silica compound which has a silethylene group, and another silane compound, it is 20: 80-80: 20 (mass ratio) normally, Preferably it is 40: 60-60: 40 (mass ratio). It is a range.
It is preferable that the usage-amount of this oligomer in the process by the oligomer which has a silethylene structure is the range of 3-30 mass parts with respect to 100 mass parts of silica. When the amount is 3 parts by mass or more, the silica is sufficiently treated with the oligomer, and sufficient alkali resistance can be imparted. On the other hand, when it is 30 parts by mass or less, silanol groups on the silica surface are not excessively lost, and functional groups can be easily introduced by a silane coupling agent described in detail later. From the above viewpoint, the amount of the oligomer having a silethylene structure is more preferably in the range of 5 to 15 parts by mass.

  The treatment with an oligomer having a silethylene structure can be easily carried out by dissolving the oligomer in water or an alcohol solvent such as methanol and bringing it into contact with silica particles. The concentration of the oligomer is preferably about 1 to 10% by mass from the viewpoints of solubility of the oligomer in a solvent, ease of handling, and the like.

In the present invention, the treated silica can be further treated with a silane coupling agent. A functional group can be imparted to the silica particles by treatment with a silane coupling agent. The type of the functional group is not particularly limited, and can be appropriately determined according to the use.
The silane coupling agent is represented by the following general formula (I).
R ¹ —Si (OR ² ) ₃ (I)
Here, R ¹ is a functional group, and examples thereof include an aminopropyl group, a glycidoxy group, a methacryloxy group, an N-phenylaminopropyl group, a mercapto group, and a vinyl group. R ² is a methyl group or an ethyl group.

  It is preferable that the usage-amount of the silane coupling agent in a silane coupling agent process is the range of 1-10 mass parts with respect to 100 mass parts of silica. When the amount is 1 part by mass or more, a sufficient amount of functional groups can be introduced. On the other hand, when the amount is 10 parts by mass or less, it is advantageous in that formation of a gel due to a condensation reaction between unreacted silane coupling agents is suppressed. It is. From the above points, the amount of the silane coupling agent used is more preferably 3 to 5 parts by mass.

The silane coupling agent treatment can be easily carried out by dissolving the silane coupling agent in water or an alcohol solvent such as methanol and bringing the silane coupling agent into contact with the silica particles as in the treatment with the oligomer. As a density | concentration of this silane coupling agent, the range of 0.1-5 mass% is preferable. When it is 0.1% by mass or more, functional groups can be sufficiently introduced, and when it is 5% by mass or less, handling is easy. From the above viewpoint, about 0.2 to 1% by mass is preferable.
In addition, the process with the said oligomer and the process with a silane coupling agent can also be performed simultaneously. In this case, it can be easily performed by dissolving the oligomer and the silane coupling agent in water or an alcohol solvent or the like and bringing them into contact with the silica particles. Even in the case of such simultaneous treatment, preferred concentrations of the oligomer and the silane coupling agent are the same as described above.

In this invention, the average particle diameter of the silica particle processed with the said oligomer and a silane coupling agent is about 1 nm-20 micrometers, Comprising: It can use properly according to the use to be used. For example, when used for a refractive index control layer described later, it is preferably in the range of 1 to 100 nm, and when used for the antiglare layer, it is preferably in the range of 0.5 to 20 μm.
The shape of the silica particles used in the present invention is not particularly limited, and may be spherical or acicular.
The average particle diameter in the present invention is measured with a laser diffraction particle size distribution measuring device for particles having a diameter of 1 μm or more, and is calculated with a laser scattering diffraction particle size distribution measuring device for particles with a diameter of less than 1 μm. It is a thing. Moreover, the measurement using an electron microscope (a scanning electron microscope (SEM) or a transmission electron microscope (TEM)) may be used for confirmation.

  The silica particles of the present invention can be suitably used for, for example, a refractive index layer or an antiglare layer of an optical film. However, when used in such applications, it is necessary to apply to a transparent substrate or the like. is there. In coating, a resin can be used as a binder for silica particles, and an ionizing radiation curable resin is preferred particularly when used for an optical film.

As the ionizing radiation curable resin, there is a polymerizable functional group that causes a reaction to advance a large molecule such as polymerization or dimerization directly upon receiving irradiation with ionizing radiation or indirectly by the action of an initiator. Monomers, oligomers and polymers having the same can be used. Specifically, radically polymerizable monomers and oligomers having an ethylenically unsaturated bond such as (meth) acryloyl group, vinyl group, allyl group and the like are preferable, and one molecule is formed so that cross-linking occurs between molecules of the binder component. It is desirable that it is a polyfunctional binder component having 2 or more, preferably 3 or more polymerizable functional groups.
Moreover, you may use the photocation polymerizable monomer and oligomer like an epoxy group containing compound which are other ionizing-radiation-hardening binder components. Furthermore, a binder component that leaves a hydroxyl group in the molecule can also be used. In this case, the hydroxyl group in the binder can improve the adhesion to an adjacent layer such as a hard coat layer by hydrogen bonding.

  Monomers preferably used as the ionizing radiation curable resin composition include di (meth) acrylates such as ethylene glycol di (meth) acrylate and pentaerythritol di (meth) acrylate monostearate; trimethylolpropane tri ( Tri (meth) acrylates such as (meth) acrylate and pentaerythritol tri (meth) acrylate; polyfunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate derivatives and dipentaerythritol penta (meth) acrylate, ethylene oxide (EO) ) Modified products and the like can be exemplified.

In addition, epoxy acrylate resins (for example, “Epoxy ester” manufactured by Kyoeisha Chemical Co., Ltd., “Epoxy” manufactured by Showa High Polymer Co., Ltd.), various isocyanates, and monomers having a hydroxyl group are added by polyaddition via a urethane bond. Number average molecular weight (polystyrene equivalent number average molecular weight measured by GPC method) such as urethane acrylate resin obtained (for example, “Suriko” manufactured by Nippon Synthetic Chemical Industry Co., Ltd. or “urethane acrylate” manufactured by Kyoeisha Chemical Co., Ltd.) is 20,000. The following oligomers can also be preferably used.
These monomers and oligomers are highly effective in increasing the cross-linking density of the coating film, and the number average molecular weight is as small as 20,000 or less, so they are highly fluid components and have the effect of improving the coating suitability of the coating composition. is there.

  Furthermore, if necessary, a reactive polymer having a (meth) acrylate group in the main chain or side chain and having a number average molecular weight of 20,000 or more can be preferably used. These reactive polymers can be purchased as commercial products such as “macromonomer” manufactured by Toagosei Co., Ltd., and a copolymer of methyl methacrylate and glycidyl methacrylate is previously polymerized, A reactive polymer having a (meth) acrylate group can be obtained by condensing the glycidyl group of the copolymer and the carboxyl group of methacrylic acid or acrylic acid later. By including these components having a large molecular weight, it becomes possible to improve the film formability for complex shapes and to reduce curling and warping of the antireflection laminate due to volume shrinkage during curing.

When using a photocurable resin as the binder component, it is desirable to use a photoinitiator to initiate radical polymerization. There is no restriction | limiting in particular in a photoinitiator, The photoinitiator used normally can be used. Examples include acetophenones, benzophenones, ketals, anthraquinones, disulfide compounds, thiuram compounds, fluoroamine compounds, and the like.
More specifically, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propan-1-one, 1-hydroxy- Cyclohexyl-phenyl-ketone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, benzyldimethylketone, 1- (4-dodecylphenyl) -2-hydroxy-2-methyl Examples include propan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, and benzophenone. .

Among the photoinitiators, 1-hydroxy-cyclohexyl-phenyl-ketone and 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one are polymerized by irradiation with ionizing radiation even in a small amount. Since the reaction is initiated and promoted, it is preferably used in the present invention. The former also has the advantage of low yellowing. These can be used either alone or in combination.
As a commercial product of the above photoinitiator, 1-hydroxy-cyclohexyl-phenyl-ketone is a trade name of “Irgacure 184”, and 2-hydroxy-1- {4- [4- (2-hydroxy-2-ketone). Methyl-propionyl) -benzyl] -phenyl} -2-methyl-propan-1-one is available from Ciba Specialty Chemicals under the trade name “Irgacure 127”.
The former is effective as a photopolymerization initiator when forming a thick film, and the latter is effective as a photopolymerization initiator when forming a thin film. Therefore, it is preferable to properly use these when forming a hard coat layer and an antiglare layer that are thick films, and a refractive index control layer that is a thin film.

The content of the silica particles in the resin composition of the present invention containing the ionizing radiation curable resin as a binder and containing the silica particles of the present invention can be changed as appropriate within the range in which the effect is exerted depending on the intended use. However, it is usually about 3 to 70% by mass. When it is 3% by mass or more, it exhibits a sufficient effect when used as an antireflection film or an antiglare film, which will be described later, and when it is 70% by mass or less, the voids between the silica particles are filled with binder molecules, so that it can withstand practical use. It is preferable at the point which gives. From the above viewpoint, the content of the silica particles of the present invention in the resin composition is more preferably in the range of 5 to 60% by mass.
The resin composition is suitably used for a refractive index control layer, a hard coat layer, an antiglare layer and the like of an optical film such as an antireflection film or an antiglare film.

For example, as shown in FIG. 1, the antireflection film has a layer structure in which a hard coat layer 12 and a low refractive index layer 13 are laminated on a transparent substrate 11.
The transparent substrate used here is not particularly limited, and those generally used for optical films can be used. However, the transparent substrate has smoothness and heat resistance and is excellent in mechanical strength. Acetyl cellulose (TAC), polyester (polyethylene terephthalate (PET), polyethylene naphthalate, etc.), diacetyl cellulose, acetate butyrate cellulose, polyether sulfone, acrylic resins (polymethyl acrylate, polymethyl methacrylate, polyacrylate, polymethacrylate, etc.) ), Polyurethane resin, polycarbonate, polysulfone, polyether, polyamide, polyimide, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, (meth) acrylic Film was formed by the various resins nitrile such like can be preferably exemplified.
Of these, TAC having no birefringence, PET having excellent heat resistance / solvent resistance and mechanical strength, and polyethylene naphthalate are preferable.

  In addition, an amorphous olefin polymer (Cyclo-Olefin-Polymer: COP) film having an alicyclic structure can also be used as the transparent substrate of the present invention. This is a base material on which a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, a vinyl alicyclic hydrocarbon polymer resin, etc. are used. For example, manufactured by Nippon Zeon Co., Ltd. "Zeonex" and "Zeonoa" (norbornene resin), "Sumilite FS-1700" manufactured by Sumitomo Bakelite Co., Ltd., "Arton" (modified norbornene resin) manufactured by JSR Corporation, "Appel" manufactured by Mitsui Chemicals, Inc. ”(Cyclic olefin copolymer),“ Topas ”(cyclic olefin copolymer) manufactured by Ticona,“ Optretz OZ-1000 series ”(alicyclic acrylic resin) manufactured by Hitachi Chemical Co., Ltd., and the like. . Moreover, the FV series (low birefringence, low photoelastic modulus film) manufactured by Asahi Kasei Chemicals Corporation is also preferable as an alternative base material for TAC.

  As the transparent substrate of the present invention, it is preferable to use these thermoplastic resins in the form of a film having a thin film flexibility. However, depending on the use mode in which curability is required, these thermoplastic resin plates are used. It is also possible to use the one in the form.

Moreover, the thickness of a transparent base material is about 20-1000 micrometers normally, 20-300 micrometers is preferable and the range of 30-200 micrometers is more preferable.
When TAC which is a particularly preferable embodiment is used, the thickness is preferably in the range of 25 to 100 μm. When the thickness is within this range, there is an advantage that the mechanical strength and flexibility are well balanced and handling during film formation is easy. From the above viewpoint, the thickness of the TAC film is more preferably in the range of 30 to 90 μm, and particularly preferably in the range of 35 to 80 μm.

  When forming a hard coat layer or an antiglare layer on the transparent substrate, in order to improve adhesion, in addition to physical treatment such as corona discharge treatment and oxidation treatment, a coating material called an anchor agent or primer is used. Application may be performed in advance.

The hard coat layer laminated on the transparent substrate has a function of imparting strength to the optical film and imparting scratch resistance and the like to the surface. More specifically, it is preferable to improve performance such as scratch resistance and strength of the coating film and to show a hardness of “H” or higher in a pencil hardness test specified in JIS 5600-5-4: 1999.
As the resin component used in the resin composition constituting the hard coat layer, it is preferable to use the same resin component as the above-mentioned ionizing radiation curable resin.
The average film thickness of the hard coat layer is preferably in the range of 1 to 25 μm after drying and curing. When it is 1 μm or more, sufficient pencil hardness is obtained, and the strength of the optical film is obtained. On the other hand, when it is 25 μm or less, curling due to curing shrinkage of the resin composition hardly occurs, and handling properties and handling properties are good. From the above viewpoint, the average film thickness of the hard coat layer is more preferably in the range of 2 to 20 μm.

  In the antireflection film, a refractive index control layer is provided on the hard coat layer. The refractive index control layer is a layer that imparts antireflection performance by controlling the refractive index. The refractive index control layer may consist of a single layer as shown in FIG. 1, or may have a multilayer structure as shown in FIG. In the case of a multilayer structure, for example, the medium refractive index layer 24 (refractive index 1.50 to 1.70), the high refractive index layer 25 (refractive index 1.60 to 1.80), and the low refractive index layer 23 (refractive index). Preferred examples include those in which the ratio of 1.30 to 1.50) is laminated in this order. When the refractive index control layer is composed of a single layer, it is preferably a low refractive index layer. When the refractive index control layer is a multilayer, the layer farthest from the substrate is a low refractive index layer. It is preferable from the viewpoint of imparting performance.

The refractive index of the low refractive index layer is usually 1.30 to 1.50, preferably 1.30 to 1.45. The smaller the refractive index, the lower the reflectance, which is preferable. However, from the viewpoint of obtaining sufficient strength, it is preferably 1.30 or more.
Furthermore, the low refractive index layer preferably satisfies the following formula (II) from the viewpoint of reducing the reflectance.
(M / 4) λ × 0.7 <n ₁ d ₁ <(m / 4) λ × 1.3 Formula (II)
In the formula, m is a positive odd number, n ₁ is the refractive index of the low refractive index layer, and d ₁ is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 380 to 680 nm.
In addition, satisfy | filling said numerical formula (II) means that m (positive odd number, usually 1) which satisfy | fills numerical formula (II) exists in the said wavelength range.

In the present invention, it is important to use silica particles having an average particle diameter of 1 to 100 nm treated with the above oligomer having a silethylene structure as a material for forming the low refractive index layer.
By including this silica, the strength of the low refractive index layer itself is increased, and the scratch resistance is improved. Moreover, since the silica of the present invention has extremely high alkali resistance, it does not elute even when exposed to an alkaline environment. Therefore, the surface of the transparent substrate opposite to the refractive index control layer can be saponified without applying a protective film or the like to the refractive index control layer.

As described above, the average particle size of the silica particles is preferably in the range of 1 to 100 nm, but from the viewpoint of imparting sufficient scratch resistance, on the other hand, suppressing the appearance and reflectance deterioration due to fine irregularities. More preferably, it is in the range of 10 to 80 nm.
Moreover, the content of the silica particles is preferably in the range of 20 to 70% by mass in terms of solid content.
When it is 20% by mass or more, it has sufficient antireflection performance, and when it is 70% by mass or less, the gap between the silica fine particles can be filled with binder molecules, and sufficient strength is exhibited. From the above viewpoint, the content of silica particles is more preferably in the range of 30 to 60% by mass.

Moreover, it is preferable that the silica particle used for refractive index control layers, such as a low refractive index layer, is a silica which has a hollow structure. Specifically, it has nanoporous inside and / or at least a part of the surface. The low refractive index layer using silica particles having such a hollow structure can adjust the refractive index to 1.30 to 1.45.
Examples of such silica particles include trade names Nipsil and Nipgel manufactured by Nippon Silica Industry Co., Ltd., colloidal silica UP series (trade name) manufactured by Nissan Chemical Industries, Ltd., and the like.
The low refractive index layer is appropriately added with a known silicone-based or fluorine-based antifouling agent, slipping agent, etc. for the purpose of imparting antifouling properties, water resistance, chemical resistance, slipping properties and the like. You can also
The thickness of the refractive index control layer is preferably in the range of 50 to 120 nm. Within this range, the refractive index can be controlled, and good antireflection performance can be obtained. From the above viewpoint, the thickness of the refractive index control layer is more preferably in the range of 80 to 120 nm. In addition, when the refractive index control layer is a multilayer, the thickness means a thickness per layer.

As the method for producing the antireflection film, a resin composition for forming a hard coat layer and a resin composition for forming a refractive index control layer are each dissolved in a solvent to prepare a solution, and the solution is applied to a transparent substrate. To do. The coating method is not particularly limited, and examples thereof include a spin coating method, a dip method, a spray method, a die coating method, a bar coating method, a roll coater method, a meniscus coater method, a flexographic printing method, a screen printing method, and a pea coater method. .
As a specific procedure, a solution of the resin composition for a hard coat layer is applied to a transparent substrate, dried to remove the solvent, and irradiated with ionizing radiation such as ultraviolet rays to be semi-cured. Next, a solution of the resin composition for forming the refractive index control layer is applied onto the hard coat layer, dried to remove the solvent, and completely cured by irradiation with ionizing radiation.

As the solvent for preparing the solution, various solvents are used, for example, alcohols such as methanol, ethanol, isopropyl alcohol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; ethyl acetate, butyl acetate, etc. Esters; Halogenated hydrocarbons; Aromatic hydrocarbons such as toluene and xylene, or mixtures thereof can be used.
Among these, it is preferable to use a ketone-based organic solvent. When a solution is prepared using a ketone solvent, it can be easily and uniformly applied to the surface of the substrate, and the evaporation rate of the solvent after application is moderate and hardly causes uneven drying. A large-area coating film can be easily obtained.

The amount of the solvent is appropriately adjusted so that each component can be uniformly dissolved and dispersed, does not cause aggregation during storage after preparation, and does not become too dilute during coating. Prepare a high-concentration coating composition by reducing the amount of solvent used within the range where this condition is satisfied, store it in a state that does not take up the volume, take out the necessary amount at the time of use, and make the concentration suitable for coating work It is preferred to dilute.
When the total amount of the solid content and the solvent is 100 parts by mass, the solvent is 50 to 95.5 parts by mass with respect to the total solids of 0.5 to 50 parts by mass, and more preferably the total solid content is 10 to 30 parts by mass. By using the solvent at a ratio of 70 to 90 parts by mass with respect to parts, a resin composition that is particularly excellent in dispersion stability and suitable for long-term storage can be obtained.

Next, an antiglare film using the silica particles of the present invention will be described. For example, as shown in FIG. 3, the antiglare film has a layer structure in which an antiglare layer 32 and a low refractive index layer 33 are laminated on a transparent substrate 31.
The transparent base material used here is the same as that described in the above-mentioned antireflection film.

The antiglare layer laminated on the transparent substrate is a layer having a fine uneven shape on the surface and providing an antiglare function. In the present invention, it is important to use silica particles having an average particle diameter of 0.5 to 20 μm treated with the above-described oligomer having a silethylene structure in the antiglare layer.
By including this silica, irregularities are imparted to the layer and a function as an antiglare layer is imparted. Moreover, since the silica of the present invention has extremely high alkali resistance, it does not elute even when exposed to an alkaline environment. Therefore, the surface of the transparent substrate opposite to the antiglare layer can be saponified without applying a protective film or the like to the antiglare layer.

The average particle diameter of the silica particles is preferably in the range of 0.5 to 20 μm as described above. When it is 0.5 μm or more, sufficient antiglare property can be imparted, and when it is 20 μm or less, the surface shape of the antiglare layer is not roughened, the surface quality is deteriorated and the surface haze is increased. Is not seen. From the above viewpoint, the average particle diameter of the silica particles is more preferably in the range of 0.5 to 10 μm.
Moreover, the content of the silica particles is preferably in the range of 3 to 30% by mass in terms of solid content. When it is 3% by mass or more, it has a sufficient antireflection performance, and when it is 30% by mass or less, the haze is not excessively high and visibility is preferable. From the above viewpoint, the content of silica particles is more preferably in the range of 5 to 20% by mass.

As a resin component used for the resin composition which comprises an anti-glare layer, the thing similar to the above-mentioned ionizing radiation curable resin can be used.
In addition to the above silica, the antiglare layer has translucent fine particles for imparting antiglare properties, additives such as leveling agents as necessary, refractive index adjustment, crosslinking shrinkage prevention, pencil hardness. You may contain the inorganic filler etc. for obtaining.

The translucent fine particles for imparting antiglare properties are not particularly limited, and inorganic and organic particles can be used. Specific examples of the fine particles formed of an organic material include plastic beads. Plastic beads include styrene beads (refractive index 1.60), melamine beads (refractive index 1.57), acrylic beads (refractive index 1.50 to 1.53), acrylic-styrene beads (refractive index 1.54 to 1.58), benzoguanamine beads, benzoguanamine / formaldehyde condensation beads, polycarbonate beads (refractive index 1.57), polyethylene beads (refractive index 1.50), and the like. The plastic beads preferably have a hydrophobic group on the surface, and examples thereof include styrene beads. Examples of the inorganic fine particles include amorphous silica other than the silica of the present invention, inorganic silica beads, and the like.
These light-transmitting fine particles may be used alone or in combination of two or more kinds having different components, different shapes, different particle size distributions, and the like.

Moreover, it is desirable that the silica particles of the present invention and the translucent fine particles protrude from the antiglare layer. Due to this protrusion, fine irregularities are formed on the surface, and an antiglare action is produced. However, various kinds of particles can be used for purposes other than forming irregularities.
One kind or two or more kinds of translucent fine particles used in the present invention may be spherical, for example, spherical, elliptical, etc., and more preferably spherical. The average particle diameter of one or more kinds of translucent fine particles is preferably 0.5 to 20 μm, and more preferably 0.5 to 10 μm.

The antiglare layer in the present invention is not only provided with anti-glare properties by forming surface irregularities, but also has internal scattering properties (refractive index difference) caused by the difference in refractive index between the matrix resin and the translucent fine particles. It is preferable to impart a higher internal scattering property as the
This internal scattering is a glare that is a problem with anti-glare films (surface irregularities act as lenses, especially in the case of high-definition displays with a small pixel size, causing variations in brightness and reducing visibility. Phenomenon to cause) It can be improved.
The difference in refractive index between the translucent resin and the matrix (binder resin) is preferably 0.04 to 0.20. If it is 0.04 or more, a sufficient light diffusion effect is obtained, and if it is 0.20 or less, the light diffusion effect is too high and the entire film is whitened.

In the antiglare layer, the total content of the translucent fine particles is preferably 5 to 40% by mass with respect to the total solid mass of the antiglare layer. More preferably, it is 10-30 mass%. When it is 5% by mass or more, sufficient antiglare property and internal scattering property can be imparted, and when it is 40% by mass or less, sufficient strength can be imparted to the antiglare layer, and hard coat properties are imparted. Can do.
The antiglare layer may further contain an ultraviolet blocking agent, an ultraviolet absorber, a surface conditioner (leveling agent), or other components.

  In the present invention, the antiglare layer may be a concavo-convex layer or a multilayer. When the antiglare layer is a multilayer, it is preferably composed of a base uneven layer and a surface shape adjusting layer provided on the base uneven layer. Here, the surface shape adjusting layer is a layer having a function of adjusting the surface shape of the underlying uneven layer to a more appropriate uneven shape. In the case where the antiglare layer is a multi-layer, that is, when it has a base uneven layer and a surface shape adjusting layer provided on the base uneven layer, the surface shape adjusting layer installed on the viewer side of the display is more It is preferable that translucent fine particles are contained. The underlying concavo-convex layer in the case where the antiglare layer is a multilayer has a concavo-convex shape on the surface, and can be obtained by substantially the same method as the antiglare layer in the case of a single concavo-convex layer.

  The average film thickness of the antiglare layer is preferably in the range of 1 to 25 μm after drying and curing. When it is 1 μm or more, sufficient pencil hardness is obtained, and the strength of the optical film is obtained. On the other hand, when it is 25 μm or less, curling due to curing shrinkage of the resin composition hardly occurs, and handling properties and handling properties are good. From the above viewpoint, the average film thickness of the antiglare layer is more preferably in the range of 2 to 20 μm. In addition, the function of a hard-coat layer can also be given to an anti-glare layer by selecting resin etc. which are used for an anti-glare layer.

Further, as shown in FIG. 3, the antiglare film preferably has a layer structure in which a low refractive index layer having a refractive index of 1.30 to 1.50 is laminated on an antiglare layer. By having such a layer structure, in addition to anti-glare property, it can be set as the film excellent also in anti-reflective property.
It is preferable to use the same low refractive index layer as that used in the antireflection film. That is, by using silica having an average particle diameter of 1 to 100 nm treated with the oligomer having a silethylene structure of the present invention as inorganic particles for producing a low refractive index in the low refractive index layer, the antiglare film has alkali resistance. The surface opposite to the low refractive index layer of the transparent substrate can be saponified without applying a protective film or the like.

The thickness of the low refractive index layer is preferably in the range of 50 to 120 nm. Within this range, good antireflection performance can be obtained. From the above viewpoint, the thickness of the low refractive index layer is more preferably in the range of 80 to 120 nm.
In addition, as a manufacturing method of the said anti-glare film, it can carry out by the same method using the solvent similar to the said antireflection film.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.
(Evaluation method)
Regarding the optical films obtained in each of the examples and comparative examples, the films before and after the alkali treatment were evaluated by the following methods. The alkali treatment was performed by immersing in a 2N aqueous sodium hydroxide solution at 60 ° C. for 2 minutes.
1. Measurement of reflectance Absolute reflectance was measured using a spectrophotometer ("UV-3100PC" manufactured by Shimadzu Corporation) equipped with a 5 ° C specular reflection measuring device. The minimum reflectance is that of the low refractive index layer. The film thickness was evaluated by a value when the minimum value of the reflectance was set so as to be in the vicinity of a wavelength of 550 nm.
2. Scratch resistance evaluation test Using # 0000 steel wool, the presence or absence of scratches was confirmed by visual observation when the steel wool was reciprocated 10 times with a load of 300 g. The evaluation criteria were as follows.
○: No scratch was observed. Δ: Scratch was marked, but no peeling was observed. X: Peeling was observed. Transparency of coating film The haze value of the outermost surface of the antiglare film was measured according to JIS K 7105: 1981 “Testing method for optical properties of plastic”.
4). Pencil Hardness Test Pencil hardness was evaluated in accordance with JIS K 5400. Using the test pencils of HB to 4H specified in JIS S 6006, 5 tests with a load of 500 g were accepted, and no test was made. The highest pencil hardness value was evaluated.

Example 1
(1) Preparation of alkali-resistant hollow silica dispersion 20 parts by mass of tetraethoxysilane, 30 parts by mass of decaethoxytetrasiloxane, and 50 parts by mass of ethylenebistriethoxysilane were mixed with 890 parts by mass of methyl isobutyl ketone and 10 parts by mass of acetic acid. An alkylenediethoxysilane oligomer, which is an oligomer having a silethylene structure, was synthesized by dissolving in a solvent and stirring for 1 hour.
Next, a hollow silica dispersion (particle size 50 nm, solid content 20% by mass, solvent: methyl isobutyl ketone) was prepared. 100 parts by mass of the alkylenediethoxysilane oligomer (oligomer having a silethylene structure) synthesized above was added to 500 parts by mass of the hollow silica dispersion, followed by stirring at 50 ° C. for 4 hours. Thereafter, hollow silica was precipitated by centrifugation, and the supernatant was removed and washed. The same amount of methyl isobutyl ketone as that removed was added, and the silica particles were dispersed by ultrasonic waves. In order to impart reactivity, 5 parts by mass of 3-acryloxypropyldimethylmethoxysilane and 3 parts by mass of acetic acid were added, and the mixture was further stirred at 50 ° C. for 4 hours. Thereafter, washing by centrifugation was performed three times by the above method, and 5 parts by mass of trimethylmethoxysilane and 3 parts by mass of acetic acid were added to remove unreacted silanol residue, followed by stirring at 80 ° C. for 2 hours. Washing by centrifugation was further performed three times by the above method, and methyl ethyl ketone was added so as to have a solid content of 20% by mass to prepare an alkali-resistant hollow silica dispersion.

(2) Preparation of resin composition for forming low refractive index layer 15 parts by mass of alkali-resistant treated hollow silica dispersion prepared in (1) above, 2 parts by mass of pentaerythritol triacrylate (PETA), and photopolymerization initiator (Irgacure 0.08 parts by mass of 127 (trade name, manufactured by Ciba Specialty Chemicals) was dissolved in 82.9 parts by mass of methyl isobutyl ketone to obtain a resin composition for forming a low refractive index layer.

(3) Preparation of resin composition for forming hard coat layer 30.0 parts by mass of pentaerythritol triacrylate (PETA) and a photopolymerization initiator (Irgacure 907 (trade name), manufactured by Ciba Specialty Chemicals) 1.5 parts by mass Was dissolved in 73.5 parts by mass of methyl isobutyl ketone to obtain a resin composition for forming a hard coat layer.

(4) Preparation of antireflection film Bar coating the resin composition for forming a hard coat layer produced in (3) above on a triacetylcellulose (TAC) film having a thickness of 80 μm, which is a transparent substrate, and drying to obtain a solvent Was removed. Thereafter, ultraviolet irradiation is performed at an irradiation dose of about 20 mJ / cm ² using an ultraviolet irradiation device (“Fusion UV” manufactured by System Japan Co., Ltd., light source H bulb), and the hard coat layer is semi-cured to obtain a film thickness of 10 μm. A hard coat layer was produced on a transparent substrate.
Next, the resin composition for forming a low refractive index layer prepared in (2) above was bar-coated, and the solvent was removed by drying. Thereafter, ultraviolet irradiation was performed at an irradiation dose of about 200 mJ / cm ² using an ultraviolet irradiation apparatus, the coating film was cured, and a low refractive index layer of about 100 nm was produced on the hard coat layer. Table 1 shows the physical property evaluation results of the antireflection film before and after the alkali resistance test.

Comparative Example 1
In Example 1, the alkali resistance treatment of (1) was not performed, and the same procedure as in Example 1 was used except that the hollow silica dispersion (particle size 50 nm, solid content 20% by mass, solvent: methyl isobutyl ketone) was used as it was. Thus, an antireflection film was produced. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Comparative Example 2
In Example 1, the silane coupling treatment hollow silica dispersion obtained by treating with a silane coupling agent ("KBM-5103" manufactured by Shin-Etsu Silicone Co., Ltd.) instead of the alkali resistant treatment hollow silica dispersion liquid of (1). An antireflection film was produced in the same manner as in Example 1 except that the liquid was used. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

Example 2
(1) Preparation of alkali-resistant silica dispersion 20 parts by mass of tetraethoxysilane, 30 parts by mass of decaethoxytetrasiloxane, and 50 parts by mass of ethylenebistriethoxysilane are mixed solvents of 890 parts by mass of methyl isobutyl ketone and 10 parts by mass of acetic acid. The product was dissolved in and stirred for 1 hour to synthesize an alkylenediethoxysilane oligomer (an oligomer having a silethylene structure).
Next, a colloidal silica dispersion (average particle size 5 μm, solid content 50 mass%, solvent: methyl isobutyl ketone) was prepared. 100 parts by mass of the alkylenediethoxysilane oligomer (oligomer having a silethylene structure) synthesized above and 200 parts by mass of a colloidal silica dispersion were added to 300 parts by mass of methyl isobutyl ketone and stirred at 50 ° C. for 4 hours. Thereafter, silica was precipitated by centrifugation, and the supernatant was removed and washed. The same amount of methyl isobutyl ketone as that removed was added, and the silica particles were dispersed by ultrasonic waves. In order to impart reactivity, 5 parts by mass of 3-acryloxypropyldimethylmethoxysilane and 3 parts by mass of acetic acid were added, and the mixture was further stirred at 50 ° C. for 4 hours. Thereafter, washing by centrifugation was performed three times by the above method, and 5 parts by mass of trimethylmethoxysilane and 3 parts by mass of acetic acid were added to remove unreacted silanol residue, followed by stirring at 80 ° C. for 2 hours. Washing by centrifugation was performed three times by the above method, and methyl ethyl ketone was added so as to have a solid content of 50% by mass to prepare an alkali-resistant dispersion.

(2) Preparation of Antiglare Layer Forming Resin Composition 20 parts by mass of alkali-resistant treated silica dispersion prepared in (1) above, 85 parts by mass of pentaerythritol triacrylate (PETA), transparent fine particles (acrylic beads, particle size 3.5 μm) and 5 parts by mass of a photopolymerization initiator (Irgacure 184 (trade name), manufactured by Ciba Specialty Chemicals) were dissolved in a mixed solvent consisting of 40 parts by mass of toluene and 150 parts by mass of methyl isobutyl ketone. Thus, a resin composition for forming an antiglare layer was obtained.

(3) Production of antiglare film Bar coating is applied to the resin composition for forming the antiglare layer produced in the above (2) on a triacetylcellulose (TAC) film having a thickness of 80 μm, which is a transparent substrate, and the solvent is removed by drying. Was removed. Thereafter, ultraviolet rays were irradiated at an irradiation dose of about 100 mJ / cm ² using an ultraviolet irradiation device (“Fusion UV” manufactured by System Japan Co., Ltd., light source H bulb), and the coating film was cured to produce an antiglare film. Table 1 shows the physical property evaluation results of the antiglare film before and after the alkali resistance test.

Comparative Example 3
Example 2 was the same as Example 2 except that the alkali resistance treatment (1) was not performed and the colloidal silica dispersion (average particle size 5 μm, solid content 50 mass%, solvent: methyl isobutyl ketone) was used as it was. Thus, an antireflection film was produced. The results of evaluation in the same manner as in Example 1 are shown in Table 1.

  According to the present invention, silica particles having alkali resistance, and further other functional groups for imparting functionality to the silica particles can be introduced. Since the optical film containing the silica particles exhibits high alkali resistance, silica does not elute even in the saponification treatment, and it is not necessary to use a protective film, so that the manufacturing process of the optical film can be greatly simplified. it can.

It is a schematic diagram which shows an example of an antireflection film. It is a schematic diagram which shows another example of an antireflection film. It is a schematic diagram which shows an example of an anti-glare film.

Explanation of symbols

10. 10. Antireflection film Transparent substrate 12. Hard coat layer 13. Low refractive index layer 20. Antireflection film 21. Transparent substrate 22. Hard coat layer 23. Low refractive index layer 24. Medium refractive index layer 25. High refractive index layer 30. Antiglare film 31. Transparent substrate 32. Antiglare layer 33. Low refractive index layer 34. Silica particles

Claims (3)

An optical film having a refractive index control layer formed by coating a resin composition containing 3 to 70% by mass of silica particles on an ionizing radiation curable resin binder on a transparent substrate,
The silica particles have an average particle diameter of a hollow structure of 1 to 100 nm, and a particle element treated with oligomer having silethylene structure,
The oligomer having the silethylene structure is a copolymer having a silica compound having a silethylene group and another silane compound having a copolymerization ratio of 40:60 to 60:40 (mass ratio).
An optical film having antireflection performance. The optical film having antireflection performance according to claim 1, wherein the silica particles are treated with 3 to 30 parts by mass of the oligomer having the silethylene structure with respect to 100 parts by mass of silica . The optical film having antireflection performance according to claim 1 or 2, wherein the silica particles are further treated with 1 to 10 parts by mass of a silane coupling agent with respect to 100 parts by mass of silica .

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