JP6371502B2 - Manufacturing method of optical film - Google Patents

Description

  The present invention relates to a method for producing an optical film that is suitably used for an image display device such as a liquid crystal display.

In an image display device such as a liquid crystal display, it is known to provide a surface protective film having antireflection properties on the outermost surface of the image display unit for the purpose of surface protection and antireflection of the image display unit. As the antireflection film, those having a low refractive index layer on a plastic film and those having a multilayer structure in which one or more low refractive index layers and high refractive index layers are laminated are known. Silicon is generally used as a material constituting such a low refractive index layer, and a thin film layer containing silicon is formed by a physical vapor deposition (PVD) method, a chemical vapor deposition (CVD) method, a dry method such as sputtering. A process method and a wet process method using a so-called sol-gel method are known. Since the dry process method usually requires a vacuum apparatus, the wet process method has attracted attention from the viewpoint of the apparatus cost and the like.
Thin film formation by the sol-gel method is performed, for example, by applying a solution containing a metal alkoxide and an acid or a basic catalyst and then heating to advance hydrolysis and polycondensation reactions. Here, when a catalyst is previously added to the coating solution for forming a sol-gel film, a part of the sol-gel reaction proceeds in the coating solution, and the storage stability of the coating solution may become a problem. In order to solve this problem, a method using an acid generator that generates an acid by light or heat as a sol-gel reaction catalyst is known. Since the acid generator generates acid after applying light or heat energy, it does not accelerate the sol-gel reaction in the coating solution for forming the sol-gel film, and improves the storage stability of the coating solution. Can do.
For example, Patent Documents 1 and 2 disclose an antireflection film having a layer formed by a sol-gel method using a silane compound and a light or thermal acid generator as a sol-gel reaction catalyst.

JP 2002-22905 A JP 2007-301970 A

  However, the sol-gel reaction using an acid catalyst has a long reaction time and low productivity. Moreover, when heating temperature was made high in order to shorten reaction time, there existed a problem that the base material used for a film was restrict | limited to the material with high heat-resistant temperature.

In recent years, with the spread of tablet terminals and the like, cases of using display devices such as liquid crystal displays not only indoors but also outdoors are increasing. Therefore, there is a demand for a display device including a high-hardness surface protective material that is not easily damaged even outdoors with much dust.
Furthermore, as a new problem that has not been known in the past, when a tablet terminal or a smartphone is operated, the image display of the display device is caused by the adhesion of oil from food, in particular from luxury products, or contamination from the living environment such as detergents and cosmetics. There is a problem that parts and the like are easily damaged and cause serious problems. As a method for imparting antifouling properties to the surface of an image display device, it has been conventionally known to provide a water-repellent organic film or the like. However, only having antifouling properties such as repelling pollutants can damage the surface. The protection performance against was not sufficient.
Since the inorganic film is harder than the organic film, the surface protective material having the inorganic film on the outermost surface is provided on the surface of the display device in order to prevent scratches caused by the dust and the contamination caused by the contaminants. It is thought that it is also effective in preventing scratches.

  An object of the present invention is to provide a method for efficiently producing an optical film having high scratch resistance even when contaminated due to dust and the like and contamination resulting from living environment.

In the production of an optical film having a surface protective layer formed by a sol-gel method, the present inventor forms at least one selected from a metal alkoxide and a hydrolyzate thereof and a specific light for the formation of the surface protective layer. It has been found that the above problems can be solved by using a composition for forming a surface protective layer containing a base generator.
That is, the present invention is a method for producing an optical film having a hard coat layer and a surface protective layer in this order on at least one surface of a substrate, wherein the surface protective layer is selected from a metal alkoxide and a hydrolyzate thereof. It is a cured product of a composition for forming a surface protective layer containing at least one kind and an ionic photobase generator, and the uncured composition is formed by applying the composition for forming a surface protective layer on the hard coat layer. The present invention relates to a method for producing an optical film comprising a step of forming a layer, a step of irradiating the uncured composition layer with light to generate a base, and a step of heating and curing the uncured composition layer. is there.

  According to the method for producing an optical film of the present invention, it is possible to efficiently produce an optical film having high scratch resistance due to dust and the like and high scratch resistance at the time of contamination derived from the living environment. The obtained optical film is suitably used for an image display device such as a liquid crystal display.

It is a schematic sectional drawing which shows an example of the optical film manufactured by this invention. It is a schematic sectional drawing which shows an example of the optical film manufactured by this invention.

  The method for producing an optical film of the present invention is a method for producing an optical film having a hard coat layer and a surface protective layer in this order on at least one surface of a substrate, the surface protective layer comprising a metal alkoxide and its hydrolysis. A cured product of a composition for forming a surface protective layer containing at least one selected from products and an ionic photobase generator, and the composition for forming a surface protective layer is applied onto the hard coat layer. Including a step of forming an uncured composition layer, a step of irradiating the uncured composition layer with light to generate a base, and a step of heating and curing the uncured composition layer. To do.

In the present invention, the average particle size of fine particles in a solution such as a composition described later is 50% when the fine particles in the solution are measured by a dynamic light scattering method and the particle size distribution is represented by a volume cumulative distribution. Means particle size (d50 median diameter). The average particle size can be measured using a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd. or a Nanotrac particle size analyzer.
The average particle diameter in the solution represents the average of the primary particle diameters if the particles are not aggregated, and represents the average of the dispersed particle diameters of the aggregated particles if the particles are aggregated particles. is there.
Moreover, in this invention, the average particle diameter of the microparticles | fine-particles in each layer which comprises an optical film can be calculated | required by the method of directly measuring the magnitude | size of a primary particle from the electron micrograph of the cross section of an optical film. Specifically, the average particle diameter of the fine particles is determined by measuring the short axis diameter and the long axis diameter of each primary particle, and using the average as the particle diameter of each particle, The volume average particle diameter obtained by approximating the volume to the rectangular parallelepiped having the particle diameter is the average particle diameter of the fine particles. Note that the same result can be obtained regardless of whether the electron microscope is a transmission type (TEM) or a scanning type (SEM).

(Optical film)
As illustrated in FIG. 1, an optical film 10 obtained by the production method of the present invention has at least a hard coat layer 2 and a surface protective layer 3 in this order on at least one surface of a substrate 1. . The optical film 10 may have other layers as necessary as long as the effects of the present invention are not impaired. For example, like the optical film illustrated in FIG. 2, a configuration in which a high refractive index layer 4 is further provided as the other layer between the hard coat layer 2 and the surface protective layer 3 can be used.
From the viewpoint of surface protection performance, the optical film 10 preferably has the surface protective layer 3 on the outermost surface. The said optical film 10 consists of hardened | cured material of the composition for a specific surface protective layer formation which the surface protective layer 3 formed in the outermost surface mentions later. As a result, the optical film 10 is excellent in scratch resistance due to dust and the like, and is less damaged when contaminated due to the living environment.
Here, since the optical film is usually provided on the outermost surface of the image display device, it is preferable to have antireflection properties in addition to the surface protection performance. In this case, if the surface protective layer 3 is used as an optical interference layer, it is preferable in that the antireflection property of the optical film becomes higher.

Hereinafter, the optical film 10 manufactured by the present invention will be described in more detail with reference to FIGS. 1 and 2. 1 and 2 are cross-sectional views showing an example of an optical film 10 manufactured according to the present invention. A film of an embodiment in which the surface protective layer 3 also functions as an optical interference layer is used. It is called “optical film”. A film other than the optical film of the first embodiment, that is, a film in which the surface protective layer 3 does not function as an optical interference layer is referred to as an “optical film of the second embodiment”. In the present invention, the optical interference layer refers to a layer that imparts antireflection properties by utilizing the light interference effect.
From the viewpoint of having high antireflection properties in addition to the surface protection performance, the optical film produced by the method of the present invention is preferably the optical film of the first embodiment.

As illustrated in FIG. 1, the optical film of the first embodiment has at least a hard coat layer 2 and a surface protective layer 3 in this order on at least one surface of the substrate 1, and the surface protective layer. The structure which has 3 in the outermost surface is mentioned. The optical film of the first embodiment only needs to have the hard coat layer 2 and the surface protective layer 3 in this order on at least one surface of the substrate 1, and the hard coat layer 2 and the surface on both surfaces of the substrate 1, respectively. The protective layer 3 may be included.
From the viewpoint of using the surface protective layer 3 as an optical interference layer and imparting high antireflection properties, in the optical film of the first embodiment, the thickness d of the surface protective layer 3 preferably satisfies d = mλ / 4n. . Here, m represents a positive odd number, n represents the refractive index of the surface protective layer 3, and λ represents the wavelength. m is preferably 1. λ is preferably 450 to 700 nm, and more preferably 500 to 600 nm.

In the optical film of the first embodiment, it is preferable that the surface protective layer 3 is a low refractive index layer 31 having a lower refractive index than the adjacent layers from the viewpoint of imparting antireflection properties. In the present invention, the low refractive index layer means a layer having a lower refractive index than at least the adjacent layer, and the high refractive index layer means a layer having a higher refractive index than at least the adjacent layer.
The difference in refractive index between the low refractive index layer 31 and the layer adjacent to the low refractive index layer 31 is preferably 0.10 or more, more preferably 0.15 or more. The refractive index of the low refractive index layer 31 is preferably 1.47 or less, more preferably 1.40 or less, from the viewpoint of antireflection properties.
When the layer adjacent to the low refractive index layer 31 is a hard coat layer, the hard coat layer is preferably the high refractive index hard coat layer 21 containing fine particles of high refractive index. Thereby, the high antireflective property using optical interference can be provided. The high refractive index fine particles will be described later.

Moreover, as illustrated in FIG. 2, the optical film of the first aspect includes a hard coat layer 2, a high refractive index layer 4, and a surface protective layer 3 in this order on at least one surface of the substrate 1. The structure which has may be sufficient. Also in this case, it is preferable to have the surface protective layer 3 on the outermost surface. A preferred thickness d of the surface protective layer 3 in the optical film of FIG. 2 is the same as described above. Further, from the viewpoint of antireflection properties, the surface protective layer 3 is preferably a low refractive index layer 31.
In the optical film illustrated in FIG. 2, the layer adjacent to the low refractive index layer 31 is the high refractive index layer 4 from the viewpoint of using the low refractive index layer 31 as an optical interference layer and imparting high antireflection properties. It is preferable.

  A preferred embodiment of the optical film of the first embodiment is a configuration in which the hard coat layer 2 and the surface protective layer 3 are adjacent to each other in FIG. 1, and the refractive index of the hard coat layer 2 is the refractive index of the surface protective layer 3. The film is more preferably 0.10 or more, more preferably 0.15 or more.

Next, the optical film of the second aspect will be described.
While the optical film of the first embodiment has high antireflection properties, since the surface protective layer 3 also functions as an optical interference layer, the thickness of the surface protective layer 3 is limited to some extent as described above. On the other hand, since the surface protective layer 3 does not need to function as an optical interference layer, the thickness of the optical film of the second aspect may be increased. Therefore, the optical film of the second embodiment is inferior to the antireflection property than the optical film of the first embodiment, but has a higher hardness of the surface protective layer and is more excellent in scratch resistance due to dust and the like than the first embodiment. The optical film can be hardly damaged when contaminated by the living environment.

A preferred embodiment of the optical film of the second embodiment has at least the hard coat layer 2 and the surface protective layer 3 in this order on at least one surface of the substrate 1, and has the surface protective layer 3 on the outermost surface. The optical film of the second embodiment also needs to have the hard coat layer 2 and the surface protective layer 3 in this order on at least one surface of the substrate 1, and the hard coat layer 2 and the surface on both surfaces of the substrate 1, respectively. The protective layer 3 may be included. From the viewpoint of further improving the scratch resistance due to dust and the like, and the scratch resistance at the time of contamination derived from the living environment, the thickness of the surface protective layer 3 in the second aspect is preferably 200 nm or more, more preferably 300 nm or more, still more preferably. Is 400 nm or more. Further, from the viewpoint of curling prevention, the thickness of the surface protective layer 3 is preferably 2000 nm or less, more preferably 1500 nm or less, and still more preferably 1200 nm or less.
The optical film of the second aspect may not have the same degree of antireflection as that of the first aspect. However, when it is provided on the outermost surface of an image display device or the like, the surface reflection is reduced as much as possible to reduce the reflection. Is preferably suppressed. From this viewpoint, the surface protective layer 3 is preferably the low refractive index layer 31 also in the optical film of the second embodiment.

The refractive index of the low refractive index layer 31 is preferably 1.47 or less, more preferably 1.40 or less, in the same manner as the optical film of the first aspect, from the viewpoint of antireflection properties. However, in the optical film of the second aspect, the low refractive index layer 31 and the low refractive index are reduced from the point of suppressing reflection at the interface between the low refractive index layer 31 and a layer adjacent to the low refractive index layer 31. It is preferable that the difference in refractive index from the layer adjacent to the layer 31 is small. In this case, the difference in refractive index between the low refractive index layer 31 and its adjacent layer is preferably 0.05 or less, more preferably 0.03 or less.
That is, when the layer adjacent to the low refractive index layer 31 in the optical film of the second embodiment is a hard coat layer, the refractive index difference between the hard coat layer 2 and the low refractive index layer 31 is preferably 0. 05 or less, more preferably 0.03 or less. The refractive index of the hard coat layer 2 can be adjusted by selecting the type and blending amount of the material constituting the hard coat layer. The material constituting the hard coat layer will be described later.

  Next, each layer and material which comprise the said optical film are demonstrated.

<Base material>
The substrate used in the present invention is preferably a substrate having high light transmittance, and a resin substrate used for a conventionally known optical film can be appropriately selected and used.
Examples of the resin base material include acetyl cellulose resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, olefin resins such as polyethylene and polymethylpentene, acrylic resins, polyurethane resins, poly Examples include those mainly composed of resins such as ether sulfone, polycarbonate, polysulfone, polyether, polyether ketone, acrylonitrile, methacrylonitrile, cycloolefin polymer, and cycloolefin copolymer. Especially, it is preferable to use triacetylcellulose (TAC) or an acrylic resin from the point which is excellent in light transmittance and refractive index anisotropy, and triacetylcellulose is more preferable.
“Mainly” means that the content ratio is the highest among the components constituting the substrate. Further, the content ratio of the main component is usually 90% by mass or more, which means that an additive or the like may be contained unless the effects of the present invention are impaired.

Moreover, a triacetylcellulose base material is preferable also from the point which has solvent permeability.
When the hard coat layer and the base material are adjacent to each other and the refractive indexes thereof are different, interface reflection and interference fringes are generated due to the interface between the hard coat layer and the base material, and an optical film for an image display device When used as, the visibility of the image may be lowered. However, when the hard coat layer-forming composition is applied to these solvent-permeable substrates, the organic solvent and low-molecular resin component in the hard coat layer-forming composition are impregnated into the substrate. When the layer forming composition is cured, a permeation layer is formed in the vicinity of the interface between the hard coat layer and the substrate, and the interface becomes unclear. As a result, even when materials having different refractive indexes are used for the hard coat layer and the base material, there is an effect that interface reflection and interference fringes can be reduced.

The total light transmittance of the substrate used in the present invention is preferably 70% or more, and more preferably 85% or more. The transmittance of the substrate can be measured according to JIS K7361-1 (a test method for the total light transmittance of a plastic-transparent material).
The thickness of the substrate used in the present invention is not particularly limited, and can be appropriately selected and used. Usually, the thickness of a base material is 10-300 micrometers, and it is preferable to set it as 15-200 micrometers from the point of the handleability, intensity | strength, and thickness reduction of a hard coat film.

  The substrate may be subjected to a surface treatment (for example, saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment), or a primer layer (adhesive layer) may be formed. . The base material in the present invention refers to those including these surface treatments and primer layers.

<Hard coat layer>
A hard-coat layer is provided in order to provide hardness to an optical film, The conventionally well-known hard-coat layer used for an optical film can be used. From the viewpoint of imparting hardness and various desired performances, the hard coat layer is preferably a cured product of the composition for forming a hard coat layer.
In addition, in this invention, a hard-coat layer means the thing which shows the hardness more than "H" in the pencil hardness test prescribed | regulated by JIS5600-5-4 (1999). The hard coat layer in the present invention is preferably 3H or more, more preferably 4H or more, in a pencil hardness test.

≪Hardcoat layer forming composition≫
The composition for forming a hard coat layer used in the present invention is preferably a composition that is cured by heat or ionizing radiation from the viewpoint of imparting hardness, heat resistance, and various desired performances. More preferably, it is a composition. As the ionizing radiation, electromagnetic waves or charged particle beams having energy quanta capable of polymerizing or cross-linking molecules, for example, ultraviolet rays (UV) or electron beams (EB), X-rays, γ-rays, etc. are used. Charged particle beams such as electromagnetic waves, α rays, and ion beams are also used.

[Ionizing radiation curable compounds]
When the composition for forming a hard coat layer is an ionizing radiation curable composition, the composition has a compound having an ionizing radiation curable functional group as a resin component (hereinafter also referred to as “ionizing radiation curable compound”). including. Examples of the ionizing radiation curable functional group include an ethylenically unsaturated bond group such as a (meth) acryloyl group, a vinyl group, and an allyl group, an epoxy group, and an oxetanyl group. As the ionizing radiation curable compound, a compound having an ethylenically unsaturated bond group is preferable, a compound having two or more ethylenic unsaturated bond groups is more preferable, and among them, having two or more ethylenically unsaturated bond groups, Polyfunctional (meth) acrylate compounds are more preferred. As the polyfunctional (meth) acrylate compound, any of a monomer and an oligomer can be used.

Among the polyfunctional (meth) acrylate compounds, bifunctional (meth) acrylate monomers include ethylene glycol di (meth) acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, 1,6-hexane. Examples thereof include diol diacrylate.
Examples of the tri- or higher functional (meth) acrylate monomer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, di Examples include pentaerythritol tetra (meth) acrylate and isocyanuric acid-modified tri (meth) acrylate.
The (meth) acrylate-based monomer may be modified by partially modifying the molecular skeleton, and is modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, or the like. Can also be used.

Moreover, examples of the polyfunctional (meth) acrylate oligomer include acrylate polymers such as urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and polyether (meth) acrylate.
Urethane (meth) acrylate is obtained by reaction of polyhydric alcohol and organic diisocyanate with hydroxy (meth) acrylate, for example.
A preferable epoxy (meth) acrylate is a (meth) acrylate obtained by reacting (meth) acrylic acid with a tri- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin or the like. (Meth) acrylates obtained by reacting the above aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins and the like with polybasic acids and (meth) acrylic acid, and bifunctional or higher functional aromatic epoxy resins, It is a (meth) acrylate obtained by reacting an alicyclic epoxy resin, an aliphatic epoxy resin or the like with a phenol and (meth) acrylic acid.
The ionizing radiation curable compounds can be used alone or in combination of two or more.

When the ionizing radiation curable compound is an ultraviolet curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator.
Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzylmethyl ketal, benzoylbenzoate, α-acyloxime ester, thioxanthones, and the like.
The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing speed. For example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. One or more selected may be mentioned.

[Fine particles]
The composition for forming a hard coat layer may contain fine particles in order to impart hardness to the hard coat layer.
The fine particles used for imparting hardness to the hard coat layer (hereinafter also referred to as “high-hardness fine particles”) may be inorganic fine particles or organic fine particles, but inorganic fine particles are preferable from the viewpoint of imparting high hardness.
Examples of the inorganic fine particles include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconia, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide. And metal oxide fine particles such as magnesium fluoride and sodium fluoride. In addition, metal fine particles, metal sulfide fine particles, metal nitride fine particles, and the like can be used. From the viewpoint of imparting high hardness to the hard coat layer, silica or alumina is preferred.

The inorganic fine particles have a photoreactive functional group capable of undergoing a crosslinking reaction between the inorganic fine particles, or a polyfunctional ionizing radiation curable compound and a surface treatment compound, on at least a part of the surface thereof. (Hereinafter, the fine particles are also referred to as “reactive inorganic fine particles”). The hardness of the hard coat film can be further improved by a cross-linking reaction between the reactive inorganic fine particles or between the reactive inorganic fine particles and the polyfunctional ionizing radiation curable compound and the surface treatment compound.
The reactive inorganic fine particles include those having two or more inorganic fine particles as a core per particle. Moreover, the reactive inorganic fine particles can increase the number of crosslinking points per content in the matrix of the hard coat layer by reducing the particle size.

  The average particle diameter of the high hardness fine particles may be appropriately adjusted according to the thickness of the hard coat layer and the type of fine particles used, but is usually 5 to 100 nm, preferably 5 to 50 nm, preferably 10 to 50 nm. It is preferable that it is 10-30 nm. The fine particles may be agglomerated particles. In the case of agglomerated particles, the secondary particle size is preferably within the above range. If the average particle diameter of the high-hardness fine particles is not less than the above lower limit, sufficient hardness can be imparted to the hard coat layer. If the average particle size of the high hardness fine particles is not more than the above upper limit value, the hard coat layer is excellent in transparency.

By selecting the type of high-hardness fine particles, in addition to imparting hardness to the hard coat layer, various functions such as adjustment of refractive index and antistatic property can be further imparted.
Among these, the refractive index adjusting fine particles include low refractive index fine particles and high refractive index fine particles. In the present invention, the low refractive index fine particles are fine particles having a refractive index of less than 1.50, and preferably have a refractive index of 1.46 or less. The high refractive index fine particles are fine particles having a refractive index of 1.50 or more, and preferably have a refractive index of 1.50 to 2.80.

When the composition for forming a hard coat layer is used for the optical film of the first aspect, the composition for forming a hard coat layer preferably contains high refractive index fine particles. The hard coat layer 2 in the optical film of FIG. 1 can be used as the high refractive index hard coat layer 21 by using the composition for forming a hard coat layer containing high refractive index fine particles. Further, by laminating the surface protective layer 3 (low refractive index layer 31) having a predetermined thickness adjacent to the high refractive index hard coat layer 21, a film having high antireflection properties utilizing optical interference can be obtained. .
The high refractive index fine particles are preferably high refractive inorganic fine particles from the viewpoint of imparting both high refractive index and high hardness to the hard coat layer, and examples thereof include metal oxide fine particles having a refractive index of 1.50 or more.
Specific examples of the metal oxide fine particles used as the high refractive index fine particles include, for example, titania (TiO ₂ , refractive index: 2.71), zirconium oxide (ZrO ₂ , refractive index: 2.10), cerium oxide (CeO). ₂ , refractive index: 2.20), tin oxide (SnO ₂ , refractive index: 2.00), antimony tin oxide (ATO, refractive index: 1.75 to 1.95), indium tin oxide (ITO, Refractive index: 1.95 to 2.00), phosphorus tin compound (PTO, refractive index: 1.75 to 1.85), antimony pentoxide (Sb ₂ O ₅ , refractive index: 2.04), aluminum zinc oxidation (AZO, refractive index: 1.90 to 2.00), gallium zinc oxide (GZO, refractive index: 1.90 to 2.00) and zinc antimonate (ZnSb ₂ O ₆ , refractive index: 1.90) -2.00) etc. are mentioned. Further, fine particles whose surface is coated with the metal oxide can also be used.
The above can be used individually by 1 type or in combination of 2 or more types.

  From the viewpoint of maintaining the transparency and hardness of the hard coat layer, the average particle diameter of the high refractive index fine particles is usually from 5 to 100 nm, preferably from 5 to 50 nm, like the above-mentioned high hardness fine particles. It is preferable that it is 50 nm, and it is more preferable that it is 10-30 nm.

Moreover, as the low refractive index fine particles, inorganic fine particles having a refractive index of less than 1.50 are preferable from the viewpoint of imparting both a low refractive index and a high hardness to the hard coat layer. For example, silica (SiO ₂ ), cryolite (Na ₃ AlF ₆ ) and the like.
From the viewpoint of maintaining the transparency and hardness of the hard coat layer, the average particle diameter of the low refractive index fine particles is usually from 5 to 100 nm, preferably from 5 to 50 nm, preferably from 10 to 50 nm, like the above-mentioned high hardness fine particles. It is preferable that it is 10-30 nm.

[Other ingredients]
The composition for forming a hard coat layer is further, if necessary, for the purpose of preventing blocking, such as an antiglare agent, an antifouling agent, an antistatic agent, a leveling agent, etc. It may contain other components such as a lubricant.

  The composition for forming a hard coat layer may further contain a solvent. The solvent does not react with each component in the composition for forming a hard coat layer, and may be appropriately selected from solvents that can dissolve or disperse each component. For example, alcohol solvents such as isopropyl alcohol and ethanol; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester solvents such as methyl acetate and ethyl acetate; halogenated hydrocarbons; aromatic hydrocarbons such as toluene and xylene And mixed solvents thereof. Among the above solvents, it is preferable to use an ester solvent, a ketone solvent, or a mixed solvent thereof.

The content of the ionizing radiation curable compound in the hard coat layer forming composition is usually 30 to 95% by mass when the fine particles are contained relative to the total solid content of the hard coat layer forming composition. It is preferable that it is 45-90 mass%, and it is still more preferable that it is 60-90 mass%. Moreover, when not containing the said microparticles | fine-particles, it is preferable that it is 70-100 mass%. In the present invention, the total solid content of the composition means all components other than the solvent in the composition.
Moreover, when using a photoinitiator, the content is 1-20 mass parts normally with respect to 100 mass parts of ionizing radiation-curable compounds, and it is preferable that it is 2-15 mass parts. More preferably, it is part by mass.

When the composition for forming a hard coat layer contains the fine particles, the total content is preferably 5 to 70% by mass with respect to the total solid content of the composition for forming a hard coat layer. More preferably, it is 55 mass%. If the content is 5% by mass or more, sufficient hardness can be imparted to the hard coat layer. Moreover, if it is 70 mass% or less, there is no fear of the hardness fall by becoming hard in a hard-coat layer.
Also when the fine particles are fine particles for adjusting the refractive index, the total content of the fine particles in the hard coat layer forming composition is preferably within the above range from the viewpoint of the hardness of the hard coat layer. And from a viewpoint of obtaining a desired refractive index, it is still more preferable that it is 10-40 mass% with respect to the total solid of the composition for hard-coat layer formation.

  The solid content concentration of the composition for forming a hard coat layer (ratio of the mass of the total solid content to the total mass of the composition) is preferably 10 to 60 mass% from the viewpoint of coating properties, and 20 to 50 mass%. % Is more preferable.

<Method for forming hard coat layer>
The hard coat layer can be formed by applying a composition for forming a hard coat layer on the substrate to form a coating layer, and performing a drying step as necessary, followed by curing.
The method for applying the composition for forming a hard coat layer may be any method that can be applied uniformly to a desired thickness, and may be appropriately selected from conventionally known methods. For example, gravure coating, knife coating, dip coating, spray coating, air knife coating, spin coating, roll coating, curtain coating, die coating, casting, bar coating, and extrusion coating Can be mentioned.

When the hard coat layer and the base material are adjacent to each other and the refractive indexes of the two are different, interface reflection and interference fringes are generated due to the interface between the hard coat layer and the base material. When used as an optical film, the visibility of the image may be reduced. As a countermeasure, as described above, a solvent-permeable base material such as a triacetyl cellulose base material is used as the base material, and an impregnation layer is formed at the interface between the hard coat layer and the base material. Examples include reducing the difference in refractive index between the hard coat layer and the substrate by selecting the type and amount of the resin component and fine particles to be blended in the forming composition.
In addition, when a hard coat layer containing low refractive index fine particles or high refractive index fine particles is formed, the hard coat layer is formed so that the fine particles in the hard coat layer have a concentration gradient in the thickness direction of the hard coat layer. It is preferable to apply and dry the composition. For example, when the hard coat layer contains high refractive index fine particles and has a higher refractive index than the base material, the concentration of the high refractive fine particles on the substrate side is low in the thickness direction of the hard coat layer. Create a gradient. When the hard coat layer contains fine particles having a high refractive index and has a lower refractive index than that of the substrate, the concentration gradient is set so that the concentration of the fine particles on the substrate side is increased in the thickness direction of the hard coat layer. Give rise to In the case of forming a hard coat layer containing fine particles such as low refractive index fine particles and high refractive index fine particles, in the vicinity of the interface between the hard coat layer and the substrate or when the solvent-permeable substrate is used. Alternatively, a method of applying and drying the composition for forming a hard coat layer may be employed so that a part of the fine particles are impregnated at the interface with the impregnated layer.
By the method as described above, the refractive index difference between the hard coat layer and the base material can be reduced, and interference fringes caused by the interface between the hard coat layer and the base material can be reduced.

Subsequently, after performing a drying process as needed, the said coating layer is hardened. When the composition for forming a hard coat layer is an ionizing radiation curable composition, the coating layer is cured by irradiating with ionizing radiation such as an electron beam or ultraviolet rays. When an electron beam is used as the ionizing radiation, the acceleration voltage can be appropriately selected according to the resin used and the thickness of the layer, but it is usually preferable to cure the coating layer at an acceleration voltage of about 70 to 300 kV.
When ultraviolet rays are used as the ionizing radiation, those containing ultraviolet rays having a wavelength of 190 to 380 nm are usually emitted. There is no restriction | limiting in particular as an ultraviolet-ray source, For example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a carbon arc lamp, etc. are used.

  The thickness (at the time of hardening) of a hard-coat layer can be suitably selected according to the intensity | strength and required performance of the said base material, and is 0.1-100 micrometers normally, Preferably it is 0.8-20 micrometers. Moreover, from the point which expresses sufficient hardness and suppresses generation | occurrence | production of a curl and a crack, More preferably, it is the range of 3-20 micrometers.

<Surface protective layer>
In the present invention, the surface protective layer is for forming a surface protective layer containing at least one selected from metal alkoxides and hydrolysates thereof (hereinafter also referred to as “metal alkoxides”) and an ionic photobase generator. It consists of the hardened | cured material of a composition. This hardened | cured material is a layer which is obtained by the sol-gel reaction of a metal alkoxide and its hydrolyzate, and has an inorganic material as a main component. Further, since the sol-gel reaction is catalyzed by a base generated from an ionic photobase generator, the reaction is faster than when an acid catalyst is used, and as a result, a highly cross-linked dense layer is obtained. It is thought that. Therefore, the surface protective layer has a higher hardness and excellent scratch resistance due to dust and the like, and excellent scratch resistance when contaminated from the living environment.

≪Surface protective layer forming composition≫
The composition for forming a surface protective layer contains at least one metal alkoxide and a hydrolyzate thereof (hereinafter also referred to as “metal alkoxide”) and an ionic photobase generator. . Moreover, unless the effect of this invention is impaired, you may contain another component as needed.

[Metal alkoxide, etc.]
In the composition for forming the surface protective layer, at least one selected from metal alkoxides and hydrolysates thereof is used. Since a layer mainly composed of an inorganic material can be formed by a sol-gel reaction such as a metal alkoxide, a surface protective layer having high scratch resistance due to dust and the like and contamination when living environment is contaminated is obtained. be able to.
The metal alkoxide can be appropriately selected from those having hydrolyzability, and examples thereof include those represented by the following general formula (A).
(R ^x ) _n M (OR ^Y ) _(mn) (A)
(In general formula (A), M is a metal atom. R ^x represents an organic group having 1 to 8 carbon atoms. R ^Y represents an alkyl group having 1 to 12 carbon atoms; N is an integer of 0 or more and m or less, and when there are a plurality of R ^x and R ^Y , the plurality of R ^x and the plurality of R ^Y may be the same or different from each other. .)

In the present invention, the organic group means a group having one or more carbon atoms. The organic group for R ^x is preferably an alkyl group or a phenyl group, and the alkyl group and the phenyl group may further have a substituent. Examples of the substituent include halogen atoms such as fluorine, chlorine and bromine, amino groups and epoxy groups. The alkyl group may have a double bond.
R ^Y represents an alkyl group having 1 to 12 carbon atoms, and a hydrogen atom in the alkyl group may be substituted with a halogen atom such as fluorine, chlorine, or bromine.
From the viewpoint of reducing the refractive index of the surface protective layer, it is preferable that the hydrogen atom in the alkyl group is substituted with a fluorine atom. On the other hand, from the viewpoint of improving the hardness of the surface protective layer, it is preferable that the hydrogen atom in the alkyl group is not substituted with a halogen atom.
Moreover, from the point which improves the hardness of a surface protective layer, it is preferable that ^RY is C1-C8, and it is more preferable that it is 1-5.
In the general formula (A), n is preferably 0 or 1 from the viewpoint of improving the hardness of the surface protective layer and improving the scratch resistance due to dust and the like, and the scratch resistance when contaminated from the living environment. , 0 is more preferable. The metal atom M in the metal alkoxide is preferably one or more selected from silicon, zirconium, titanium, aluminum, vanadium, zinc, strontium, indium, tin, tantalum, tungsten, thallium, antimony, and cerium. M is preferably silicon from the viewpoint of improving the scratch resistance of the surface protective layer due to dust and the like, the scratch resistance at the time of contamination derived from the living environment, and the low refractive index. Further, from the viewpoint of improving the scratch resistance of the surface protective layer due to dust and the like, and the scratch resistance at the time of contamination derived from living environment, and from the viewpoint of high refractive index, M is preferably zirconium or titanium.

When the metal atom M in the general formula (A) is silicon, the metal alkoxide is alkoxysilane. Specific examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, and the like. It is not limited.
Among the above alkoxysilanes, n in the general formula (A) is 0 from the viewpoint of improving the scratch resistance due to dust and the like of the surface protective layer and the scratch resistance at the time of contamination derived from the living environment, and the reactivity. One or more selected from tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane are preferable, and tetraethoxysilane is more preferable.

[Ionic photobase generator]
The composition for forming a surface protective layer contains an ionic photobase generator as a catalyst for the sol-gel reaction of a metal alkoxide and a hydrolyzate thereof. In the present invention, the ionic photobase generator refers to a salt of an acidic compound and a basic compound that has a property of generating a base by light irradiation. The light irradiated when the base is generated preferably contains ultraviolet light having a wavelength of 190 to 380 nm. There is no restriction | limiting in particular as an ultraviolet-ray source, For example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a carbon arc lamp, etc. are used.
When an ionic photobase generator is used, a base can be generated immediately before or simultaneously with the sol-gel reaction, so that problems such as gelation immediately after preparing the surface protective layer forming composition are avoided, The storage stability of the composition can be improved.
The photobase generator having no ionicity is a composition for forming a surface protective layer because it has low solubility in a surface protective layer forming composition and a lower alcohol solvent usually contained in the composition as a main solvent. It is not suitable for the present invention in terms of handling property, uniform coating property and the like.

  In the ionic photobase generator which is a salt of an acidic compound and a basic compound, the acidic compound is preferably a compound represented by the following general formula (1).

(.R shown wherein, R ¹ and R ² are each independently a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an aryl group having a carbon number of 6-8 ^{3 to} R ⁷ each independently represent a hydrogen atom, a hydroxyl group, or an organic group, and two of R ^{1 to} R ⁷ may be bonded to each other to form a ring.
Moreover, from the viewpoint of base generation efficiency, in the general formula (1), one of R ^{3 to} R ⁷ is preferably a group represented by the following general formula (2).

(Wherein, R ⁸ to R ¹² are two of each independently represent a hydrogen atom or an organic group .R ⁸ to R ^12, it may combine with each other to form a ring.)

  Here, the ionic photobase generator which is a salt of the acidic compound and the basic compound represented by the general formula (1) is represented by the following general formula (X). The ionic photobase generator can be easily prepared without going through a complicated synthesis route by proceeding the following acid-base reaction simply by mixing the acidic compound and the basic compound. is there.

(In the above formula, R ^{1 to} R ⁷ are the same as described above. Z represents a basic compound.)
When the ionic photobase generator represented by the general formula (X) is irradiated with light, the reaction represented by the following formula proceeds and is decarboxylated easily. Therefore, the quantum yield is extremely high, and a sufficient amount of base can be generated with a short time and a small amount of light irradiation.

(In the above formula, R ^{1 to} R ⁷ are the same as described above. Z represents a basic compound.)

Specific examples of the acidic compound represented by the general formula (1) include phenylacetic acid, diphenylacetic acid, triphenylacetic acid, 2-phenylpropionic acid, 2,2-diphenylpropionic acid, 2-phenylbutyric acid, α-methoxy. Phenylacetic acid, mandelic acid, 3-methyl-2-phenylbutyric acid, 2- (4-isobutylphenyl) propionic acid, 2-methoxyphenylacetic acid, 3-methoxyphenylacetic acid, 4-methoxyphenylacetic acid, 2-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid, 3,4-dimethoxyphenylacetic acid, 3,4- (methylenedioxy) phenylacetic acid, 2,5-dimethoxyphenylacetic acid, 3,5-dimethoxyphenylacetic acid, 3, 4,5-trimethoxyphenylacetic acid, 2,4-dinitrophenylacetic acid, 4-bif Sulfonyl acetic acid, 2- (3-benzoylphenyl) propionic acid, 1-naphthalenesulfonic acid, 2-naphthalene acetic acid, 6-methoxy -α- methyl-2-naphthalene acetic acid.
Among the above, from the viewpoint of base generation efficiency, the acidic compound used for the ionic photobase generator is more preferably 2- (3-benzoylphenyl) propionic acid.

The basic compound used for the ionic photobase generator is not particularly limited. For example, an amine compound, a compound containing a pyridyl group, a hydrazine compound, an amide compound, a quaternary ammonium hydroxide salt, a mercapto compound, a sulfide compound, or a phosphine compound can be used. From the viewpoint of basicity, among the above, amine compounds are preferable.
The amine is not particularly limited, and any of primary amines, secondary amines and tertiary amines can be used. From the viewpoint of basicity, pyrrolidine, piperidine, cyclohexylamine, dicyclohexylamine, imidazole, tetramethylammonium. Hydroxide, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,5-diazabicyclo [4.3.0] nona-5 -Ene, guanidine, 1,5,7-triazabicyclo [4.4.0] dec-5-ene, and at least one selected from compounds represented by the following general formulas (3) to (4) More preferably.

(In the formula, R ¹³ represents a single bond or an alkylene group having 1 to 10 carbon atoms, and R ¹⁴ represents an alkylene group having 1 to 10 carbon atoms.)
Of the above basic compounds, one or more selected from cyclohexylamine, dicyclohexylamine, and guanidine are more preferable.

  The ionic photobase generator used in the present invention is particularly preferably at least one selected from compounds represented by the following formulas (A-1) to (A-3).

  Examples of commercially available ionic photobase generators used in the present invention include WPBG series “WPBG-082” (compound of (A-1) above) and “WPBG-167” (above) of Wako Pure Chemical Industries, Ltd. (Compound of (A-2)), “WPBG-168” (compound of (A-3) above) and the like.

[Fine particles]
The composition for forming a surface protective layer may contain fine particles for imparting hardness, adjusting the refractive index, and further imparting various functions. The fine particles include solid fine particles and hollow fine particles, and can be appropriately selected according to a desired function.
The viewpoint of improving the hardness of the surface protective layer and suppressing the curing shrinkage during the formation of the surface protective layer to reduce surface irregularities, and to provide scratch resistance such as dust and scratch resistance at the time of contamination from the living environment. Therefore, the surface protective layer 3 preferably contains inorganic solid fine particles. In addition, when the surface protective layer 3 is the low refractive index layer 31, the surface protective layer 3 preferably further includes hollow fine particles from the viewpoint of reducing the refractive index of the surface protective layer.

[Inorganic solid fine particles]
Inorganic solid fine particles improve the hardness of the surface protective layer and suppress curing shrinkage during the formation of the surface protective layer to reduce surface irregularities, resulting in scratch resistance such as dust and scratches caused by contamination from the living environment It is preferably used from the viewpoint of imparting adhesion.
Surface protection layer obtained by curing metal alkoxide etc. by sol-gel method can provide hardness by mixing inorganic solid fine particles, and can reduce the compounding amount of metal alkoxide etc. Curing shrinkage during layer formation is also suppressed. As a result, cracks and unevenness of the film due to curing shrinkage are unlikely to occur, and thus it is considered that a surface protective layer having a high hardness with less surface unevenness can be obtained.

In the present invention, the inorganic solid fine particles mean inorganic fine particles having no voids. Since the inorganic solid fine particles are neither porous nor hollow, the inorganic fine particles are less likely to be crushed by the pressure applied to the particles from the outside (external pressure) than the hollow fine particles, and are excellent in pressure resistance.
Since the inorganic solid fine particles do not have voids, the refractive index is higher than that of hollow fine particles. For example, when the inorganic solid fine particles are silica particles, the refractive index is preferably 1.42 to 1.46. The inorganic solid fine particles may be in an amorphous state or a crystalline state.

As the inorganic solid fine particles, inorganic solid fine particles used in conventionally known antireflection films and hard coat films can be used. For example, a metal oxide, a metal nitride, a metal sulfide, a metal fluoride, etc. are mentioned. Silica fine particles are preferred from the viewpoint of making the surface protective layer have a low refractive index and obtaining hardness.
The shape of the solid silica fine particles may be any of a substantially spherical shape, a chain shape, a needle shape, a plate shape, a piece shape, a rod shape, and a fiber shape. From the viewpoint of improving the hardness of the surface protective layer, it is preferably substantially spherical or chain-like, and more preferably elliptical spherical silica particles or chain-like silica fine particles.
Further, from the viewpoint of improving the hardness of the surface protective layer, the solid silica fine particles are irregular silica fine particles in which 3 to 20 substantially spherical silica fine particles having an average particle diameter of 1 to 100 nm are bonded by an inorganic chemical bond. Is more preferable. As such deformed silica fine particles, for example, commercially available products such as “V-8803” manufactured by JGC Catalysts & Chemicals Co., Ltd. can be used.

  The average particle size of the inorganic solid fine particles is preferably 1 to 100 nm, more preferably 10 to 70 nm. When the average particle size is not more than the above upper limit value, the obtained surface protective layer is excellent in transparency. Moreover, if an average particle diameter is more than the said lower limit, it will become a high-hardness surface protective layer.

[Hollow particles]
The hollow fine particles are preferably used when the surface reflectance is reduced by making the surface protective layer have a low refractive index.
In the present invention, the hollow fine particles refer to particles in which the inside surrounded by the outer shell layer is porous or hollow and air is contained inside the particles. The refractive index of the hollow fine particles is preferably 1.20 or more and 1.44 or less, and more preferably 1.40 or less from the viewpoint of imparting low refractive index properties.

The outer shell layer of the hollow fine particles may be inorganic or organic, and examples thereof include those made of metal, metal oxide, and resin. From the viewpoint of improving the hardness of the surface protective layer, an inorganic material is preferable, and silica is more preferable. When the outer shell layer is silica, the silica may be either crystalline silica or amorphous silica.
The shape of the hollow fine particles may be any of a substantially spherical shape, a chain shape, a needle shape, a plate shape, a piece shape, a rod shape, a fiber shape, and the like. Among them, since the porosity can be increased while having pressure resistance, it is preferably approximately spherical, and more preferably elliptical or true spherical.
In the present invention, the term “substantially spherical” means an elliptical sphere or a shape that can approximate a sphere including a polyhedron, and is a concept that includes a true sphere.

  The average particle diameter of the hollow fine particles is preferably 1 to 100 nm, and more preferably 30 to 80 nm. When the average particle size is not more than the above upper limit value, the surface protective layer is excellent in transparency. Moreover, if an average particle diameter is more than the said lower limit, the said hollow fine particle will be easy to disperse | distribute uniformly and it will be easy to provide low refractive index property.

In the present invention, two or more kinds of hollow silica fine particles having different average particle diameters may be used in combination. When two or more kinds of hollow silica fine particles having different average particle diameters are used, it is preferable that the hollow silica fine particles have the same particle diameter. Specifically, the standard deviation of the particle diameters is 20 times the average particle diameter. % Or less, and more preferably 10% or less. When hollow fine particles are added, the hardness tends to decrease normally. However, when two or more types of hollow silica fine particles having a small variation in particle diameter and different average particle diameters are used in combination, the hardness is reduced while achieving a low refractive index. Can be suppressed.
Moreover, it is preferable that the hollow silica fine particles used in the present invention are not particularly subjected to surface treatment from the viewpoint of reactivity with metal alkoxide and the like. Since the hollow silica fine particles not subjected to surface treatment with a silane coupling agent or the like have many hydroxyl groups on the surface, the reactivity with a metal alkoxide or the like is high.

  Specific examples of the hollow fine particles include composite oxide sols or hollow silica fine particles disclosed in JP-A Nos. 7-133105 and 2001-233611. Among these, hollow silica fine particles prepared using the technique disclosed in JP-A-2001-233611 are preferable.

The hollow fine particles are preferably used in combination with the aforementioned inorganic solid fine particles. Thereby, hardness can be provided, making a surface protective layer low refractive index. In this case, the mass ratio of the hollow fine particles to the inorganic solid fine particles in the composition for forming a surface protective layer is preferably 5 to 100 parts by mass of the inorganic solid fine particles with respect to 100 parts by mass of the hollow fine particles. More preferably, it is -70 mass parts, and it is still more preferable that it is 20-50 mass parts. If it is more than the said lower limit, the hardness of a surface protective layer will become especially excellent. On the other hand, if it is below the said upper limit, it will be easy to reduce the refractive index of a surface protective layer.
The ratio of the average particle size of the hollow fine particles to the inorganic solid fine particles is such that when the average primary particle size of the hollow fine particles is 1, the average particle size of the inorganic solid fine particles is 0.1 to 10. Preferably, it is 0.2-5, and it is still more preferable that it is 0.5-2.

〔solvent〕
The composition for forming a surface protective layer usually contains a solvent from the viewpoint of improving coatability. As the solvent used in the composition for forming the surface protective layer, it does not react with each component in the composition for forming the surface protective layer, and the respective components can be dissolved or dispersed uniformly, and the leveling property after application, quick drying property From this point of view, alcohol solvents are preferable, and lower alcohols having 1 to 4 carbon atoms such as methanol, ethanol, 1-propanol, and isopropyl alcohol are more preferable. The “main component” means that the amount of the lower alcohol having 1 to 4 carbon atoms is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80 to 100% by mass with respect to the total amount of the solvent. means.
In addition, an ester solvent, a ketone solvent, an ether solvent, and the like may be further contained as long as the coating property of the surface protective layer forming composition is not impaired.
The said solvent can be used individually by 1 type or in combination of 2 or more types.

[Other ingredients]
In addition to the above components, various surfactants can be used in the composition for forming a surface protective layer in order to further improve properties such as anti-aggregation effect and anti-settling effect, and leveling properties. Examples of the surfactant include silicone oil, a fluorine-based surfactant, and preferably a fluorine-based surfactant containing a perfluoroalkyl group. Further, from the viewpoint of the denseness of the layer to be formed, the surfactant is preferably one that hardly remains in the surface protective layer and easily bleeds out.
Furthermore, for the surface protective layer forming composition, an antistatic agent, an antifouling agent, a colorant (pigment, dye), a flame retardant, a silane coupling agent, an ultraviolet absorber, an infrared absorber, an adhesive, if necessary. An imparting agent, an antioxidant, a surface modifier, an antiblocking agent and the like can be added.

The total content of metal alkoxide and the like in the surface protective layer forming composition is preferably 20 to 99.95% by mass with respect to the total solid content of the surface protective layer forming composition. It is more preferable that it is mass%, and it is still more preferable that it is 30-60 mass%. If it is in the said range, a surface protective layer will be a thing of high hardness.
From the viewpoint of promoting the sol-gel reaction, the content of the ionic photobase generator is preferably 0.05 to 10 parts by mass with respect to 100 parts by mass of the total amount of metal alkoxide and the like. More preferably, it is 5 parts by mass.

When inorganic solid fine particles are used, the content thereof is preferably 1 to 80% by mass, and preferably 10 to 50% by mass, based on the total solid content of the composition for forming a surface protective layer. More preferred. If it is above the above lower limit value, it is easy to impart hardness, and suppresses curing shrinkage when forming the surface protective layer to reduce surface irregularities, scratch resistance such as dust, and damage due to contamination from the living environment Sex can be imparted. Moreover, if it is below the said upper limit, the hardness fall by a surface protective layer becoming weak can be prevented.
Moreover, when using hollow microparticles, it is preferable that the content is 20-60 mass% with respect to the solid content whole quantity of the composition for surface protection layer formation, and it is 30-50 mass%. More preferred. If it is not less than the above lower limit value, it is easy to impart low refractive index properties, and if it is not more than the above upper limit value, it is possible to prevent a decrease in hardness due to the surface protective layer becoming brittle.
Further, the total amount of the inorganic solid fine particles and the hollow fine particles is 80% by mass or less based on the total amount of the composition for forming a surface protective layer, from the viewpoint of preventing a decrease in hardness due to the surface protective layer becoming brittle. preferable.
Moreover, it is preferable that it is 60-99 mass% with respect to the whole quantity of the composition for surface protection layer formation, and, as for content of a solvent, it is more preferable that it is 80-98 mass%.

<High refractive index layer>
Of the optical films 10 according to the present invention, the optical film of the first aspect includes a hard coat layer 2, a high refractive index layer 4, and a surface on at least one surface of the substrate 1 as illustrated in FIG. The structure which has the protective layer 3 in this order may be sufficient. The high refractive index layer 4 is a layer having a refractive index higher than at least the surface protective layer 3, and is usually provided between the hard coat layer 2 and the surface protective layer 3 and adjacent to the surface protective layer 3. The optical film of the first embodiment having such a configuration has a high antireflection property.

The high refractive index layer is usually formed using a composition for forming a high refractive index layer containing high refractive index fine particles, and is preferably a cured product of the composition for forming a high refractive index layer. Each component used in the composition for forming a high refractive index layer is the same as that described in the composition for forming a hard coat layer, or in the composition for forming a surface protective layer, the metal in the metal alkoxide or the like is zirconium. A material having a high refractive index sol-gel material such as titanium or the like is preferable. These high refractive index layers can be formed by the same method as the hard coat layer or the surface protective layer.
Although the refractive index of a high refractive index layer should just be set suitably, it is 1.50-2.80 normally.

The thickness of the high refractive index layer is in the range of m ₁ λ ₁ / 4n _{1 to} m ₁ λ ₁ / 2n ₁ from the viewpoint of imparting high antireflection properties utilizing optical interference in the optical film of the first embodiment. It is preferable. Here, m ₁ represents a positive odd number, n ₁ represents the refractive index of the high refractive index layer 4, and λ ₁ represents the wavelength. m ₁ is preferably 1, and λ ₁ is preferably 450 to 700 nm.

[Method for producing optical film]
The method for producing an optical film of the present invention relates to the production of an optical film having, in order, a hard coat layer and a surface protective layer on at least one surface of a substrate, A step of forming an uncured composition layer by coating on the hard coat layer, a step of generating light by irradiating the uncured composition layer with light, and heating and curing the uncured composition layer Process.
The base material, the hard coat layer, the surface protective layer, and the method for forming the hard coat layer are as described above.

In the method for producing an optical film of the present invention, an uncured composition is formed by applying a composition for forming a surface protective layer containing at least one selected from a metal alkoxide and a hydrolyzate thereof and an ionic photobase generator. After forming the layer, the uncured composition layer is irradiated with light to generate a base from the ionic photobase generator. The base generated from the ionic photobase generator catalyzes the sol-gel reaction of the metal alkoxide and its hydrolyzate. Therefore, in the present invention, since the base is generated in the reaction system immediately before or simultaneously with the sol-gel reaction, problems such as gelation immediately after the preparation of the surface protective layer forming composition are avoided, and the composition can be stored stably. Can be improved.
When a basic catalyst is used in the sol-gel reaction, the reaction proceeds faster than the acid catalyst, so that the heating temperature at the time of forming the surface protective layer can be lowered and a highly crosslinked film can be obtained. . As a result, it is possible to form a surface protective layer having higher hardness and excellent scratch resistance due to dust and the like, and excellent scratch resistance at the time of contamination derived from the living environment.

In the method for producing an optical film of the present invention, first, as described above, a hard coat layer is formed on at least one surface of a substrate, and then a surface protective layer-forming composition is applied onto the hard coat layer to form an optical film. A cured composition layer is formed.
The method for applying the composition for forming the surface protective layer may be any method that can uniformly apply the composition for forming the surface protective layer to a desired thickness, and may be appropriately selected from conventionally known methods. For example, gravure coating method, knife coating method, dip coating method, spray coating method, air knife coating method, spin coating method, roll coating method, printing method, curtain coating method, die coating method, casting method, bar coating method, extrusion Examples thereof include a coating method.
In addition, when it has arbitrary layers, such as the high refractive index layer mentioned above, on the hard-coat layer, the composition for surface protection layer formation is apply | coated on this arbitrary layer.

Next, a step of irradiating the uncured composition layer with light to generate a base from the ionic photobase generator contained in the uncured composition layer (hereinafter also referred to as “base generation step”) is performed. . The generated base acts as a base catalyst that accelerates the sol-gel reaction of the metal alkoxide and its hydrolyzate contained in the uncured composition layer.
The light source for irradiation and the irradiation amount may be appropriately selected according to the absorption wavelength and absorption intensity of the ionic photobase generator, but the irradiation light preferably includes ultraviolet light having a wavelength of 190 to 380 nm. There is no restriction | limiting in particular as an ultraviolet-ray source, For example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a carbon arc lamp, etc. are used. The amount of light irradiation is generally in the range of 10 to 2000 mJ / cm ² .

The method for producing an optical film of the present invention includes a step of heating and curing the uncured composition layer (hereinafter also referred to as “heating step”). The heating step may be performed simultaneously with the base generation step, and may be performed at any stage before or after the base generation step, but is preferably performed simultaneously with the base generation step or before the base generation step. . By performing the heating step, the sol-gel reaction of the metal alkoxide and its hydrolyzate contained in the uncured composition layer proceeds under the base catalyst, the uncured composition layer is cured, and the hard coat layer is A surface protective layer is formed on the surface.
The heating temperature of the uncured composition layer is preferably 70 to 150 ° C., more preferably from the viewpoint of accelerating the sol-gel reaction and the heat resistance of the base material and hard coat layer constituting the optical film. 80-100 ° C. Thus, in the present invention, the reaction can efficiently proceed even at a relatively low heating temperature.
The heating time is preferably 0.5 to 5 minutes, more preferably 1 to 3 minutes from the viewpoint of productivity.

  According to the said manufacturing method, the optical film excellent in the scratch resistance by the dust etc. and the scratch resistance at the time of the contamination originating in a living environment can be manufactured efficiently. Moreover, the optical film obtained by the said manufacturing method is used suitably as a surface protection film or antireflection film for image display apparatuses, such as a liquid crystal display.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, this invention is not limited to the form as described in an Example.
Evaluation of the optical films of Examples and Comparative Examples was performed as follows.

<Sandfall test (when not contaminated)>
The transmittance of the optical films obtained in Examples and Comparative Examples was measured using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC) (transmittance before a sandfall test).
Next, the optical film was disposed at an inclination angle of 45 degrees with respect to a horizontal plane so that the surface protective layer side of the optical film was the upper surface, and sand was dropped from the optical film toward the optical film at a height of 1 m. . Thereafter, the optical film was washed, and the transmittance after the sandfall test was measured in the same manner as described above.
The hardness of the optical film was evaluated by determining the difference between the transmittance after the sandfall test and the transmittance before the sandfall test. It shows that the hardness of an optical film is so high that the difference of the transmittance | permeability before and after a sandfall test is small.
The sand used in the sand fall test is a carborundum produced by pulverizing and classifying black silicon carbide ingot and green silicon carbide ingot. In this test, carborundum # 24 having a center particle size of 600 to 850 μm. 800 cm ^{3 was} used.

<Sandfall test (when contaminated)>
The transmittance of the optical films obtained in Examples and Comparative Examples was measured using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC) (transmittance before a sandfall test). Next, on the surface protective layer side of the optical film, dish detergent (Family Fresh, manufactured by Kao Corporation), salad oil (Nisshin Salad Oil, Nisshin Oillio), emulsion (SK-II Skin Signature, manufactured by Max Factor) Sunburn oil (Dark Tanning Oil, manufactured by HAWAII TROPIC) was applied, and sand fall test evaluation was performed in the same manner as described above.

<Refractive index>
The refractive index of the hard coat layer was determined by measuring the reflectance R of the hard coat layer at a temperature of 23 ° C. and a wavelength of 550 nm using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC). Calculated from
R = (n ₀ −n ₁ ) ² / (n ₀ + n ₁ ) ²
n ₀ ; Refractive index of air n ₁ ; Refractive index of hard coat layer Further, the refractive index of the surface protective layer of the optical film obtained in Examples and Comparative Examples is determined by an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation). , UV-3100PC), the reflection spectrum (spectral reflectance) of the surface protective layer was measured and calculated by fitting the obtained reflection spectrum curve.

Production Example 1 (Preparation of composition 1 for forming a hard coat layer)
The following components were mixed to prepare composition 1 for forming a hard coat layer.
Ionizing radiation curable compound: a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name: KAYARAD-PET-30, molecular weight: 298 and 352, number of ionizing radiation curable functional groups: 3 And 4): 37 parts by mass. Solvent 1: methyl acetate: 25 parts by mass. Solvent 2: methyl ethyl ketone (MEK): 18 parts by mass. Solvent 3: methyl isobutyl ketone (MIBK): 18 parts by mass. Photopolymerization initiator (BASF). Product name: Irgacure 184): 2 parts by mass

Production Example 2 (Preparation of composition 2 for forming a hard coat layer)
The following components were mixed to prepare a hard coat layer forming composition 2 having a high refractive index.
Ionizing radiation curable compound: a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name: KAYARAD-PET-30, molecular weight: 298 and 352, number of ionizing radiation curable functional groups: 3 And 4): 25 parts by mass / high refractive index fine particles: antimony pentoxide fine particles (manufactured by JGC Catalysts & Chemicals, trade name: V-4562, average particle size: 20 nm, solid content: 40% by mass, solvent: methyl isobutyl ketone) ): 30 parts by mass. Solvent 1: methyl acetate: 25 parts by mass. Solvent 2: methyl ethyl ketone (MEK): 18 parts by mass. Photopolymerization initiator (trade name: Irgacure 184 manufactured by BASF): 2 parts by mass.

Production Example 3 (Preparation of surface protective layer-forming composition 1)
The following components were mixed to prepare a surface protective layer forming composition 1.
· Tetraethoxysilane hydrolyzate containing ethanol solution (solid content of 10 percent as SiO _2): 20 parts by weight Ionic photobase generator (manufactured by Wako Pure Chemical Industries, Ltd., trade name: WPBG-082) : 0.05 part by mass hollow silica fine particles (average particle size 50 nm, solid content concentration 20% as SiO ₂ ): 10 parts by mass solid colloidal silica (manufactured by JGC Catalysts & Chemicals, trade name: V-8803) , Irregular-shaped silica fine particles in which 2 to 10 substantially spherical silica fine particles having an average particle size of 25 nm are bonded by an inorganic chemical bond, (average particle size 50 nm) solid content concentration of 40% as SiO ₂ ): 2 parts by mass / isopropyl Alcohol (IPA): 68 parts by mass

Production Example 4 (Preparation of surface protective layer-forming composition 2)
In Production Example 3, the ionic photobase generator was changed from WPBG-082 to WPBG-167 (manufactured by Wako Pure Chemical Industries, Ltd., trade name), in the same manner as in Production Example 3, for the surface protective layer. Forming composition 2 was prepared.

Production Example 5 (Preparation of surface protective layer-forming composition 3)
In Production Example 3, the surface protective layer was formed in the same manner as in Production Example 3, except that the ionic photobase generator was changed from WPBG-082 to WPBG-168 (trade name, manufactured by Wako Pure Chemical Industries, Ltd.). Composition 3 was prepared.

Production Example 6 (Preparation of surface protective layer-forming composition 4)
The following components were mixed to prepare surface protective layer forming composition 4.
· Tetraethoxysilane hydrolyzate containing ethanol solution (solid content of 10 percent as SiO _2): 20 parts by weight Ionic photobase generator (manufactured by Wako Pure Chemical Industries, Ltd., trade name: WPBG-082) : 0.05 part by mass / solid colloidal silica (manufactured by JGC Catalysts & Chemicals Co., Ltd., trade name: V-8803, 2 to 10 substantially spherical silica fine particles having an average particle diameter of 25 nm are bonded by an inorganic chemical bond. Modified silica fine particles (average particle size 50 nm) Solid content concentration of 40% as SiO ₂ ): 5 parts by mass / isopropyl alcohol (IPA): 75 parts by mass

Comparative Production Example 1 (Preparation of surface protective layer-forming composition 5)
In Production Example 3, a surface protective layer-forming composition 5 was prepared in the same manner as in Production Example 3 except that the ionic photobase generator was not added.

Comparative Production Example 2 (Preparation of surface protective layer-forming composition 6)
In Production Example 3, instead of 0.05 part by mass of ionic photobase generator WPBG-082 (trade name, manufactured by Wako Pure Chemical Industries, Ltd.), 4-methoxyphenyldiphenylsulfonium trifluoromethane, which is a photoacid generator A surface protective layer-forming composition 6 was prepared in the same manner as in Production Example 3 except that 0.05 part by mass of sulfonate (trade name: WPAG-370, manufactured by Wako Pure Chemical Industries, Ltd.) was used.

Comparative Production Example 3 (Preparation of surface protective layer-forming composition 7)
In Production Example 3, instead of the ionic photobase generator WPBG-082 (manufactured by Wako Pure Chemical Industries, Ltd., trade name), a photobase generator having no ionicity (manufactured by Wako Pure Chemical Industries, Ltd.), A surface protective layer-forming composition 7 was prepared in the same manner as in Production Example 3 except that trade name: WPBG-018) was used. However, the photobase generator did not dissolve in isopropyl alcohol, and even when the surface protective layer forming composition 7 was used, a uniform coating film (uncured composition layer) could not be formed.

Example 1 (Production of optical film)
(1) Formation of hard coat layer Hard obtained in Production Example 1 using a slot die coater on a triacetyl cellulose (TAC) substrate (manufactured by Konica Minolta, Inc., trade name: KC4UY, thickness 40 μm) The coating layer forming composition 1 was applied at a coating speed of 20 m / min to form a coating film. The coating film was dried at 80 ° C. for 30 seconds to remove the solvent. Next, the coating film is cured by irradiating the coating film with ultraviolet rays at an irradiation amount of 80 mJ / cm ² using an ultraviolet irradiation device to obtain a film 1 having a hard coat (HC) layer having a thickness of 7 μm after curing. It was. The refractive index of the hard coat layer was 1.52.

(2) Formation of surface protective layer On the HC layer of the film 1 obtained in the above (1), the surface protective layer-forming composition 1 obtained in Production Example 3 is slot die coater as in the above (1). Was applied to form an uncured composition layer. The uncured composition layer was irradiated with ultraviolet rays at an irradiation amount of 100 mJ / cm ² using an ultraviolet irradiation device to generate a base. Subsequently, it heated at 100 degreeC for 2 minute (s), the uncured composition layer was hardened, the surface protective layer with a film thickness of 100 nm was formed after hardening, and the optical film was obtained. The refractive index of the surface protective layer was 1.36. The said evaluation was performed using the obtained film. The results are shown in Table 1.
When the obtained optical film was cut and the cut surface was observed with a scanning electron microscope, the hollow silica fine particles in the surface protective layer had an average particle diameter of 50 nm, and the solid colloidal silica had an average particle diameter of 50 nm. It was.

Example 2 (Production of optical film)
In Example 1, an optical film was obtained in the same manner as in Example 1 except that the surface protective layer-forming composition 2 obtained in Production Example 4 was used instead of the surface protective layer-forming composition 1. . The refractive index of the surface protective layer was 1.36. The said evaluation was performed using the obtained film. The results are shown in Table 1.

Example 3 (Production of optical film)
In Example 1, an optical film was obtained in the same manner as in Example 1 except that the surface protective layer-forming composition 3 obtained in Production Example 5 was used instead of the surface protective layer-forming composition 1. . The refractive index of the surface protective layer was 1.36. The said evaluation was performed using the obtained film. The results are shown in Table 1.

Example 4 (Production of optical film)
In Example 1, an optical film was obtained in the same manner as in Example 1 except that the surface protective layer-forming composition 4 obtained in Production Example 6 was used instead of the surface protective layer-forming composition 1. . The refractive index of the surface protective layer was 1.46. The said evaluation was performed using the obtained film. The results are shown in Table 1.
In addition, when the obtained optical film was cut | disconnected and the cut surface was observed with the scanning electron microscope, the average particle diameter of the solid colloidal silica in a surface protective layer was 50 nm.

Example 5 (Production of optical film)
In Example 1, an optical film was obtained in the same manner as in Example 1 except that instead of the hard coat layer forming composition 1, the hard coat layer forming composition 2 obtained in Production Example 2 was used. . The refractive index of the hard coat layer was 1.57. The said evaluation was performed using the obtained film. The results are shown in Table 1.

Example 6 (Production of optical film)
In Example 1, an optical film was obtained in the same manner as in Example 1 except that the film thickness after curing of the surface protective layer was 1000 nm. The said evaluation was performed using the obtained film. The results are shown in Table 1.

Comparative Example 1 (Production of comparative optical film)
Comparative Example 1 was carried out in the same manner as in Example 1 except that the composition 5 for forming a surface protective layer obtained in Comparative Production Example 1 was used instead of the composition 1 for forming a surface protective layer in Example 1. An optical film was obtained. The said evaluation was performed using the obtained film. The results are shown in Table 1.

Comparative Example 2 (Production of comparative optical film)
Comparative Example 2 was carried out in the same manner as in Example 1 except that the surface protective layer-forming composition 6 obtained in Comparative Production Example 2 was used instead of the surface protective layer-forming composition 1 in Example 1. An optical film was obtained. The said evaluation was performed using the obtained film. The results are shown in Table 1.

  It became clear that the optical films of Examples 1 to 6 were excellent in scratch resistance both when contaminated from the living environment and when not contaminated. In particular, compared with the optical films of Comparative Examples 1 and 2, the scratch resistance at the time of contamination derived from the living environment is excellent.

  According to the method for producing an optical film of the present invention, it is possible to efficiently produce an optical film having excellent scratch resistance due to dust and the like, and scratch resistance at the time of contamination derived from the living environment. The optical film is suitably used for an image display device such as a liquid crystal display.

DESCRIPTION OF SYMBOLS 1 Base material 2 Hard-coat layer 3 Surface protective layer 4 High refractive index layer 10 Optical film

Claims (13)

A method for producing an optical film having, in order, a hard coat layer and a surface protective layer on at least one surface of a substrate, wherein the surface protective layer is at least one selected from metal alkoxides and hydrolysates thereof, A cured product of a composition for forming a surface protective layer containing an ionic photobase generator, and a step of applying the composition for forming a surface protective layer on the hard coat layer to form an uncured composition layer Irradiating the uncured composition layer with light to generate a base; heating the uncured composition layer to sol-gel reaction with at least one selected from the metal alkoxide and its hydrolyzate The manufacturing method of an optical film including the process made to harden | cure by. The method for producing an optical film according to claim 1, wherein the ionic photobase generator is a salt of an acidic compound and a basic compound, and the acidic compound is represented by the following general formula (1).

(In the formula, R ¹ and R ² each independently represent a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an aryl group having 6 to 8 carbon atoms. ^{3 to} R ⁷ each independently represents a hydrogen atom, a hydroxyl group, or an organic group, and two of R ^{1 to} R ⁷ may be bonded to each other to form a ring. The manufacturing method of the optical film of Claim 2 whose one of R < ³ > -R < ⁷ > is group represented by the following general formula (2) in the said General formula (1).

^(Wherein, R 8 ^{to R 12} are two of each independently represent a hydrogen atom or an organic group ^.R 8 ^{to R 12,} it may combine with each other to form a ring.)   The method for producing an optical film according to claim 2 or 3, wherein the acidic compound is 2- (3-benzoylphenyl) propionic acid.   The manufacturing method of the optical film in any one of Claims 2-4 whose said basic compound is an amine compound. The basic compound is pyrrolidine, piperidine, cyclohexylamine, dicyclohexylamine, imidazole, tetramethylammonium hydroxide, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0]. ] Undec-7-ene, 1,5-diazabicyclo [4.3.0] non-5-ene, guanidine, 1,5,7-triazabicyclo [4.4.0] dec-5-ene, and The manufacturing method of the optical film in any one of Claims 2-5 which is at least 1 sort (s) chosen from the compound represented by following General formula (3)-(4).

(In the formula, R ¹³ represents a single bond or an alkylene group having 1 to 10 carbon atoms, and R ¹⁴ represents an alkylene group having 1 to 10 carbon atoms.) The production of an optical film according to any one of claims 1 to 6, wherein the ionic photobase generator is at least one selected from compounds represented by the following formulas (A-1) to (A-3). Method.
  The content of the ionic photobase generator in the surface protective layer forming composition is 0.05 to 10 parts by mass with respect to 100 parts by mass of the total amount of the metal alkoxide and its hydrolyzate. The manufacturing method of the optical film in any one of 1-7.   The metal atom in the metal alkoxide is at least one selected from silicon, zirconium, titanium, aluminum, vanadium, zinc, strontium, indium, tin, tantalum, tungsten, thallium, antimony, and cerium. The manufacturing method of the optical film in any one.   The hard coat layer and the surface protective layer are adjacent to each other, and the refractive index of the hard coat layer is 0.10 or more higher than the refractive index of the surface protective layer. The manufacturing method of the optical film in any one of.   The method for producing an optical film according to claim 1, wherein the surface protective layer further contains inorganic solid fine particles.   The method for producing an optical film according to claim 1, wherein the hard coat layer further contains fine particles having a high refractive index.   The manufacturing method of the optical film in any one of Claims 1-12 whose heating temperature of the said uncured composition layer is 80-100 degreeC.