JP2006047532A - Optical film, manufacturing method therefor, antireflection film, polarizing plate and image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film having a coating film having uniform thickness, a preferable surface state and no spot defect, the coating film formed by applying a coating liquid containing molecules having many polymerizable unsaturated bonds and using an organic solvent, to provide a method for manufacturing the optical film, and to provide an antireflection film, a polarizing plate and an image display apparatus using the film. <P>SOLUTION: The method for manufacturing an optical film is carried out by forming a film of one or more layers on a long support which is continuously carried, wherein one or more layers are formed by applying a coating liquid containing a compound having a polymerizable unsaturated bond by a die coating method into ≤200 nm dry film thickness, and using a filter for filtering the coating liquid prior to coating, the filter showing 99.9% trapping efficiency for less than 1.0 μm particles. The optical film is formed by the above method, and is used for the antireflection film, the polarizing plate and the image display apparatus. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical film and a method for producing the same, an antireflection film comprising the optical film, a polarizing plate using the antireflection film, and an image display device provided with at least one of the antireflection film and the polarizing plate.

With the high performance and widespread use of information communication equipment and AV equipment, the demand for optical parts using optical thin films is rapidly increasing, and the need for producing optical thin films with high productivity is increasing. The optical thin film has an optical film thickness (optical film thickness nd = physical film thickness × refractive index) of about ¼ to 1 times the visible light wavelength, and various functions can be achieved by laminating the optical thin film as a single layer or multiple layers. You can have it. Main products using optical thin films include bandpass filters, dichroic mirrors, dichroic filters, cold mirror filters, beam splitters, antireflection films, near-infrared cut filters, laser mirrors, and ND filters.
As an optical thin film, a multilayer film obtained by laminating a transparent thin film of metal oxide has been conventionally used. The reason for using a plurality of transparent thin films is to prevent reflection of light in a wavelength range as wide as possible in the visible range. The transparent thin film of metal oxide is formed by a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, particularly a vacuum vapor deposition method or a sputtering method which is a kind of physical vapor deposition method. A metal oxide transparent thin film has excellent optical properties as an optical thin film. However, a deposition method using a vapor deposition method or a sputtering method has low productivity and is not suitable for mass production.

Instead of the vapor deposition method, a method of forming an optical thin film by coating has been proposed. Patent Document 1 (Japanese Patent Publication No. 60-59250) discloses an antireflection layer having fine pores and fine inorganic particles. The antireflection layer is formed by coating. The fine pores are formed by performing an activated gas treatment after the application of the layer and releasing the gas from the layer. Patent Document 2 (Japanese Patent Application Laid-Open No. 59-50401) discloses an antireflection film in which a support, a high refractive index layer and a low refractive index layer are laminated in this order. This publication also discloses an antireflection film in which an intermediate refractive index layer is provided between a support and a high refractive index layer. Each coating layer is formed by coating a coating solution in which a polymer or inorganic fine particles are dissolved or dispersed in a solvent.
Since the optical thin film can be continuously formed on the long support by coating, the optical thin film can be produced with higher productivity. Further, productivity can be further increased by increasing the coating speed.
When an optical thin film is prepared by coating, a drying process for removing the solvent after coating and a curing process for fixing the coating film on the support are required. The curing step is generally a step in which at least one of a thermosetting material and a photocurable material is previously placed in a coating solution and cured by at least one of heating and light irradiation. When applying at a high speed in order to increase productivity, the heat curing requires a long heat curing step, and therefore, it is preferably formed by a crosslinking reaction or a polymerization reaction by light irradiation or electron beam irradiation.

A gravure coating method is an example of a coating method with high applicability of a thin film. In the gravure coating method, the surplus coating solution on the surface of the gravure roll on which the concavo-convex engraving has been applied is scraped off using a doctor blade, and then the coating solution remaining in the concave portion of the gravure roll is transferred to a film.
In patent document 3 (Unexamined-Japanese-Patent No. 2003-322703), the antireflection film is apply | coated by the micro gravure coating system and the dry film of 80-90 nm is coated.
However, when a coating solution containing molecules having many polymerizable unsaturated bonds is applied using the gravure coating method described above, the surface shape after coating becomes whitish, and when observed with an optical microscope, point defects having a diameter of about 1 to 5 μm are observed. It may occur on the entire surface. Due to the occurrence of this point defect, the quality of the coating film is significantly lowered. Further, the post-metering coating method including the gravure coating method has a drawback that the film thickness stability is relatively low when applied for a long time. In particular, when applying a coating solution containing an organic solvent as a solvent, there may be a problem that a change in the film thickness accompanying the concentration of the coating solution becomes large.

On the other hand, since the die coating method is a pre-measuring coating method, the amount of the extruded coating liquid is applied as it is and the area where the liquid is released is very small, so the change in film thickness when applying for a long time is small Has characteristics. Moreover, although the phenomenon that the surface shape after application becomes whitish over the front surface can be suppressed by using the die coating method, the defect cannot be completely eliminated.
In the production of an optical thin film produced by conventional coating, the coating solution is filtered before coating. In Patent Document 4 (Japanese Patent Laid-Open No. 2003-121606), filtration is performed using a filter having a pore diameter of about 3 μm. Has been done. Moreover, in patent document 5 (Unexamined-Japanese-Patent No. 2004-45462), it filters using a 1 micrometer filter. However, the above-described point defects such as those described above cannot be completely removed by filtration using a conventionally used filter having a pore size.
Japanese Patent Publication No. 60-59250 JP 59-50401 A JP 2003-322703 A JP 2003-121606 A JP 2004-45462 A

The present invention includes a coating liquid containing a molecule having many polymerizable unsaturated bonds on a support, mainly using an organic solvent as a solvent, having a uniform film thickness, a good surface shape, It aims at providing the optical film in which the coating film without a defect was formed.
Furthermore, an object of the present invention is to provide an antireflection film comprising the above optical film, a polarizing plate using the antireflection film, an antireflection film or an image display device provided with the polarizing plate.

As a result of diligent studies to achieve the above object, the present inventor uses a die coating method as a coating method and selects a filter satisfying a certain trapping efficiency, so that molecules having many polymerizable unsaturated bonds can be obtained. The present inventors have found that the coating liquid containing it can be applied without the occurrence of point defects.
That is, according to the present invention, an optical film having the following constitution, a method for producing the film, a polarizing plate, and an image display device are provided, and the object of the present invention is achieved.
1. A method for producing an optical film by forming one or more films on a continuous substrate that is continuously conveyed, wherein at least one layer is coated with a coating solution containing a compound having a polymerizable unsaturated bond. 99.9% trapping efficiency is less than 1.0 μm as a filter formed by coating so that the dry film thickness of the coating layer is 200 nm or less and used for filtration of the coating liquid performed before the coating A method for producing an optical film, comprising using the filter.
2. ^{2. The} method for producing an optical film as described in 1 above, wherein the number of point defects observed at a diameter of 1.0 μm or more when the optical film is observed with an optical microscope is 10 or less per 0.1 mm ^2. .
3. When forming an optical film by forming one or more films on a continuously supported long support, the film thickness of the coating film at a certain point on the optical film and the long support 500 m continuously from this point 3. The method for producing an optical film as described in 1 or 2 above, wherein the difference in film thickness of the coating film at the point applied on the body is in the range of ± 5%.
4). The optical film obtained by the manufacturing method in any one of said 1 to 3.
5. The antireflection film which consists of an optical film obtained by the manufacturing method in any one of said 1 to 3.
6). 6. A polarizing plate, wherein the antireflection film described in 5 above is used for at least one of the polarizing films.
7). 6. An image display device, wherein the antireflection film according to 5 or the polarizing plate according to 6 is disposed on an image display surface.

The method for producing an optical film described in 1 above shows a method for forming an optical thin film without causing point defects. By using the die coating method, the point defect that occurs in the gravure coating method does not occur. In the region of the optical thin film, point defects which have been a problem in the past appear remarkably. Therefore, the present invention is particularly useful when an optical thin film is formed by a coating method. Furthermore, the cause of the same type of point defects previously contained in the coating solution is eliminated by setting the particle size showing the 99.9% capture efficiency of the filter used for filtration performed in advance of coating to less than 1.0 μm. It is possible to achieve a good surface condition.
In the above 2, the point defects are reduced by the production method shown in the above 1, and a good planar coating film is obtained. However, the satisfactory planar properties (the number of point defects observed at a diameter of 1.0 μm or more). The coating film itself is less regarded as an invention.

The optical film of the present invention contains a molecule having many polymerizable unsaturated bonds on a support, and is coated with a coating solution mainly using an organic solvent as a solvent by a die coating method, so that the film thickness is uniform, which is good. A coating film having a flat surface shape and few point defects is formed.
Furthermore, the present invention provides an antireflection film comprising the above optical film, a polarizing plate using the antireflection film, an antireflection film or an image display device comprising the polarizing plate. In particular, the image display device has a very high display quality in which the reflection of the background is extremely small, the color of reflected light is remarkably reduced, the uniformity in the display surface is ensured, and the number of point defects is drastically reduced. It is.

  The present invention is described in detail below. In the present specification, the description “numerical value A” to “numerical value B” represents the meaning of “numerical value A or more and numerical value B or less” when the numerical value represents a physical property value, a characteristic value, or the like. The description of “(meth) acryloyl” means “acryloyl or methacryloyl, or both”. The same applies to “(meth) acrylate”, “(meth) acrylic acid”, and “(meth) acrylamide”. Further, when a hydrogen atom is substituted with an atom other than a hydrogen atom, the atom other than the hydrogen atom is also handled as a substituent for convenience.

[Configuration of die coater]
FIG. 1 is a sectional view of a coater using a slot die embodying the present invention. The coater 10 is applied to the web 12 supported by the backup roll 11 and continuously applied from the slot die 13 with the coating liquid 14 as a bead 14 a, thereby forming a coating film 14 b on the web 12.

  Inside the slot die 13, a pocket 15 and a slot 16 are formed. The pocket 15 has a curved section and a straight section, and may be, for example, a substantially circular shape as shown in FIG. 1 or a semicircular shape. The pocket 15 is a liquid storage space for the coating liquid extended in the width direction of the slot die 13 with its cross-sectional shape, and the length of the effective extension is generally equal to or slightly longer than the coating width. The supply of the coating liquid 14 to the pocket 15 is performed from the side surface of the slot die 13 or from the center of the surface opposite to the slot opening 16a. The pocket 15 is provided with a stopper that prevents the coating liquid 14 from leaking out.

  The slot 16 is a flow path of the coating liquid 14 from the pocket 15 to the web 12, and has a cross-sectional shape in the width direction of the slot die 13 like the pocket 15, and the opening 16a located on the web side is generally Using a width regulating plate (not shown), the width is adjusted to be approximately the same as the coating width. The angle between the slot tip of the slot 16 and the tangent in the web running direction of the backup roll 11 is preferably 30 ° or more and 90 ° or less.

The tip lip 17 of the slot die 13 where the opening 16a of the slot 16 is located is formed in a tapered shape, and the tip is a flat portion called a land, and the upstream side in the advancing direction of the web 12 with respect to the slot 16 is formed. The upstream lip land 18a and the downstream side are referred to as the downstream lip land 18b.
When applying a thin layer such as an optical thin film, the structure of the die coater described in Japanese Patent Laid-Open No. 2003-200097, Japanese Patent Laid-Open No. 2003-211052, and Japanese Patent Laid-Open No. 2003-236434 is used. Is preferred. As for the configuration of the backup roll, as shown in Japanese Patent Application Laid-Open No. 2003-251260, it is desirable that the fluctuation width due to the rotation of the backup roll be less than 10 μm.
In the present invention, a coating solution is applied using such a die coater to form each layer on the support, at least one of which contains a compound having a polymerizable unsaturated group, The dry film is formed so that the film thickness is 200 nm or less, preferably 110 nm or less. When the film thickness exceeds 200 nm, it does not play a role as an optical thin film, which is not preferable.
Further, the difference between the thickness of the coating film at a certain point of the optical film and the thickness of the coating film at the point where the coating is continuously applied on the long support 500 m from this point is in the range of ± 5%. It is preferable. This means that the film thickness of the coating film is uniform.

[Compound with polymerizable unsaturated bond]
The compound having a polymerizable unsaturated bond may be a monomer or a polymer. For example, in the case of a monomer, a monomer having two or more ethylenically unsaturated groups, an ester of a polyhydric alcohol and (meth) acrylic acid (example: Ethylene glycol di (meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, Dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane Acrylate, polyester polyacrylate), vinylbenzene and its derivatives (eg, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinylsulfone (eg, divinylsulfone). ), Acrylamide (eg, methylenebisacrylamide) and methacrylamide.

Further, a crosslinkable group may be introduced instead of or in addition to the monomer having two or more ethylenically unsaturated groups. Examples of the crosslinkable functional group include isocyanate group, epoxy group, aziridine group, oxazoline group, aldehyde group, carbonyl group, hydrazine group, carboxyl group, methylol group and active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. That is, in the present invention, the crosslinkable functional group may not react immediately but may exhibit reactivity as a result of decomposition.
When using these compounds having a crosslinkable functional group, a crosslinked structure can be formed by heating after coating.
Other examples include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like.

  Examples of other compounds having a polymerizable unsaturated bond include a crosslinkable fluoropolymer compound, and a perfluoroalkyl group-containing silane compound (for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) In addition to triethoxysilane), a fluorine-containing copolymer having a fluorine-containing monomer component and a monomer component for imparting a crosslinkable group as constituent components may be mentioned.

  Specific examples of the fluorine-containing monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, perfluorooctylethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole. Etc.), partially (meth) acrylic acid or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) or M-2020 (manufactured by Daikin)), fully or partially fluorinated vinyl ethers, However, perfluoroolefins are preferred, and hexafluoropropylene is particularly preferred from the viewpoints of refractive index, solubility, transparency, availability, and the like.

  As structural units for imparting crosslinking reactivity, structural units obtained by polymerization of monomers having a self-crosslinkable functional group in advance in the molecule such as glycidyl (meth) acrylate and glycidyl vinyl ether, carboxyl groups, hydroxy groups, amino groups , Obtained by polymerization of a monomer having a sulfo group or the like (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, maleic acid, crotonic acid, etc.) And a structural unit obtained by introducing a crosslinking reactive group such as a (meth) acryloyl group into these structural units by a polymer reaction (for example, it can be introduced by a technique such as allowing acrylic acid chloride to act on a hydroxy group) And the like.

  In addition to the above-mentioned fluorine-containing monomer units and structural units for imparting crosslinking reactivity, monomers not containing fluorine atoms can be copolymerized as appropriate from the viewpoints of solubility in solvents and film transparency. There are no particular limitations on the monomer units that can be used in combination. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid 2) -Ethylhexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl) Vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate etc.), acrylamides (N-tert-butylacrylamide, N- Black hexyl acrylamide), methacrylamides, and acrylonitrile derivatives.

  As described in JP-A-10-25388 and JP-A-10-147739, a curing agent may be appropriately used in combination with the above polymer.

  The fluorine-containing polymer particularly useful in the present invention is a random copolymer of perfluoroolefin and vinyl ethers or vinyl esters. In particular, it preferably has a group capable of undergoing a crosslinking reaction alone (a radical reactive group such as a (meth) acryloyl group, a ring-opening polymerizable group such as an epoxy group or an oxetanyl group). These cross-linking reactive group-containing polymer units preferably occupy 5 to 70 mol%, particularly preferably 30 to 60 mol% of the total polymer units of the polymer.

  As a preferred form of the copolymer used in the present invention, one having the following general formula 1 can be mentioned.

General formula 1

In General Formula 1, L represents a linking group having 1 to 10 carbon atoms, more preferably a linking group having 1 to 6 carbon atoms, particularly preferably a linking group having 2 to 4 carbon atoms, It may have a branched structure, may have a ring structure, and may have a heteroatom selected from O, N, and S.
Preferred examples include * — (CH ₂ ) ₂ —O — **, * — (CH ₂ ) ₂ —NH — **, * — (CH ₂ ) ₄ —O — **, * — (CH ₂ ). _{6 -O - **, * - (} CH 2) 2 -O- (CH 2) 2 -O - **, * - CONH- (CH 2) 3 -O - **, * - CH 2 CH (OH ) CH ₂ —O — **, * —CH ₂ CH ₂ OCONH (CH ₂ ) ₃ —O — ** (* represents a connecting site on the polymer main chain side, and ** represents a connection on the (meth) acryloyl group side) Represents a part). m represents 0 or 1;

  In general formula 1, X represents a hydrogen atom or a methyl group. From the viewpoint of curing reactivity, a hydrogen atom is more preferable.

  In the general formula 1, A represents a repeating unit derived from an arbitrary vinyl monomer, and is not particularly limited as long as it is a constituent component of a monomer copolymerizable with hexafluoropropylene. Tg (contributes to film hardness), solubility in solvents, transparency, slipperiness, dust / antifouling properties, etc., can be selected as appropriate, depending on the purpose, depending on the single or multiple vinyl monomers It may be configured.

  Preferred examples include methyl vinyl ether, ethyl vinyl ether, t-butyl vinyl ether, cyclohexyl vinyl ether, isopropyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, glycidyl vinyl ether, vinyl ethers such as allyl vinyl ether, vinyl acetate, vinyl propionate, butyric acid. (Meth) such as vinyl esters such as vinyl, methyl (meth) acrylate, ethyl (meth) acrylate, hydroxyethyl (meth) acrylate, glycidyl methacrylate, allyl (meth) acrylate, (meth) acryloyloxypropyltrimethoxysilane Acrylates, styrene, styrene derivatives such as p-hydroxymethylstyrene, crotonic acid, maleic acid, itaconic acid Can be mentioned unsaturated carboxylic acids and derivatives thereof, more preferably ether derivatives, vinyl ester derivatives, particularly preferably a vinyl ether derivative.

  x, y, and z represent mol% of each constituent component, and represent values satisfying 30 ≦ x ≦ 60, 5 ≦ y ≦ 70, and 0 ≦ z ≦ 65. Preferably, 35 ≦ x ≦ 55, 30 ≦ y ≦ 60, and 0 ≦ z ≦ 20, and particularly preferably 40 ≦ x ≦ 55, 40 ≦ y ≦ 55, and 0 ≦ z ≦ 10.

  A particularly preferred form of the copolymer used in the present invention is General Formula 2.

General formula 2

In general formula 2, X, x, and y have the same meaning as in general formula 1, and the preferred ranges are also the same.
n represents an integer of 2 ≦ n ≦ 10, preferably 2 ≦ n ≦ 6, and particularly preferably 2 ≦ n ≦ 4.
B represents a repeating unit derived from an arbitrary vinyl monomer, and may be composed of a single composition or a plurality of compositions. As an example, what was demonstrated as an example of A in the said General formula 1 is applicable.
z1 and z2 represent mol% of each repeating unit, and represent values satisfying 0 ≦ z1 ≦ 65 and 0 ≦ z2 ≦ 65. It is preferable that 0 ≦ z1 ≦ 30 and 0 ≦ z2 ≦ 10 respectively, and it is particularly preferable that 0 ≦ z1 ≦ 10 and 0 ≦ z2 ≦ 5.

  For the copolymer represented by the general formula 1 or 2, for example, a (meth) acryloyl group is introduced into a copolymer comprising a hexafluoropropylene component and a hydroxyalkyl vinyl ether component by any one of the methods described above. Can be synthesized.

  Preferred examples of the copolymer useful in the present invention include those described in JP-A-2004-45462, [0043] to [0047]. Further, methods for synthesizing these copolymers are also described in detail in the publication.

  When adjusting the coating solution using the compound having a polymerizable unsaturated bond, the total solid content is preferably 10% by mass or more and more preferably 20% by mass or more from the viewpoint of film hardness. preferable.

[Polymerization initiator]
Next, the polymerization initiator used in combination with the compound having a polymerizable unsaturated bond will be described in detail.
Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator.
The polymerization initiator (L) of the present invention is preferably a compound that generates radicals by at least one of light irradiation and heat irradiation. The photopolymerization initiator (L) used in the present invention preferably has a maximum absorption wavelength of 400 nm or less. Thus, the handling can be performed under a white light by setting the absorption wavelength to the ultraviolet region. A compound having a maximum absorption wavelength in the near infrared region can also be used.

First, the compound (L1) that generates radicals will be described in detail.
The compound (L1) capable of generating a radical preferably used in the present invention generates a radical by at least one of light irradiation and heat irradiation, and initiates and accelerates the polymerization of the compound having a polymerizable unsaturated group. Refers to the compound to be made.
A known polymerization initiator or a compound having a bond with a small bond dissociation energy can be appropriately selected and used. Moreover, the compound which generate | occur | produces a radical can be used individually or in combination of 2 or more types.
Examples of the compound that generates radicals include conventionally known organic peroxide compounds, thermal radical polymerization initiators such as azo polymerization initiators, amine compounds (described in Japanese Patent Publication No. 44-20189), organic halogenated compounds, carbonyls, and the like. Examples include photo radical polymerization initiators such as compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boric acid compounds, and disulfone compounds.

Specific examples of the organic halogenated compounds include Wakabayashi et al., “Bull Chem. Soc Japan” 42, 2924 (1969), US Pat. No. 3,905,815, JP-A 63-298339, M.M. P. Examples include compounds described in Hutt “Journal of Heterocyclic Chemistry” 1 (No 3), (1970) ”, and in particular, an oxazole compound substituted with a trihalomethyl group: an S-triazine compound.
More preferred are s-triazine derivatives in which at least one mono, di, or trihalogen-substituted methyl group is bonded to the s-triazine ring.

  Examples of other organic halogen compounds include ketones, sulfides, sulfones and nitrogen-containing heterocycles described in paragraphs [0039] to [0048] of JP-A-5-27830.

  Examples of the carbonyl compound include, for example, “Latest UV Curing Technology”, pages 60 to 62 (published by Technical Information Association, 1991), paragraph numbers [0015] to [0016] of JP-A-8-134404, And the compounds described in paragraph Nos. [0029] to [0031] of the specification of No. 11-217518, and benzoin compounds such as acetophenone, hydroxyacetophenone, benzophenone, thioxan, benzoin ethyl ether, and benzoin isobutyl ether Benzoic acid ester derivatives such as ethyl p-dimethylaminobenzoate and ethyl p-diethylaminobenzoate, benzyldimethyl ketal, and acylphosphine oxide.

As said organic peroxide compound, the compound etc. of the paragraph number [0019] of Unexamined-Japanese-Patent No. 2001-139663 are mentioned, for example.
Examples of the metallocene compound include various titanocene compounds described in JP-A-2-4705 and JP-A-5-83588, iron-arene complexes described in JP-A-1-304453, JP-A-1-152109, and the like. Is mentioned.

  Examples of the hexaarylbiimidazole compound described in JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, 4,622,286, and the like. And various compounds.

Examples of the organic borate compound include, for example, Japanese Patent Nos. 2764769 and 2002-116539, and Kunz, Martin “Rad Tech'98. Proceeding April 19-22, 1998, Chicago”. Examples of the organic borate described are the compounds described. For example, the compounds described in paragraphs [0022] to [0027] of JP-A-2002-116539 can be mentioned.
As other organic boron compounds, organic boron such as JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, JP-A-7-306527, JP-A-7-292014, etc. Specific examples include transition metal coordination complexes and the like.

Examples of the sulfone compound include compounds described in JP-A-5-239015, and examples of the disulfone compound include those represented by general formulas (II) and (III) described in JP-A 61-166544. Compounds and the like.
These radical generating compounds may be used alone or in combination of two or more. As addition amount, it is 0.1-30 mass% with respect to the whole quantity of a radically polymerizable monomer, Preferably it is 0.5-25 mass%, Most preferably, it can add at 1-20 mass%. Within this range, the polymerizability is high.

It is preferable that the composition of this invention contains a radical polymerization initiator in the ratio of 0.5-10 mass% with respect to the total mass of the compound containing a polymerizable unsaturated bond. More preferably, it contains a radical polymerization initiator in a proportion of 1 to 5% by mass.
In the composition of the present invention, when a polymerization reaction is carried out by ultraviolet irradiation, a conventionally known ultraviolet spectral sensitizer or chemical sensitizer may be used in combination. Examples include Michler's ketone, amino acids (such as glycine), and organic amines (such as butylamine and dibutylamine).

Moreover, when performing a polymerization reaction by near infrared irradiation, it is preferable to use a near infrared spectral sensitizer together.
The near-infrared spectral sensitizer used in combination may be a light-absorbing substance having an absorption band in at least a part of the wavelength range of 700 nm or more, and a compound having a molecular extinction coefficient of 10,000 or more is preferable. Furthermore, a value having absorption in the region of 750 to 1400 nm and a molecular extinction coefficient of 20000 or more is preferable. Moreover, it is more preferable that there is a trough of absorption in the visible light wavelength region of 420 nm to 700 nm, and it is optically transparent. As the near-infrared spectral sensitizer, various pigments and dyes known as near-infrared absorbing pigments and near-infrared absorbing dyes can be used. Among these, it is preferable to use a conventionally known near-infrared absorber.
Commercially available dyes and literature (for example, “Chemical Industry”, May 1986, p. 45-51, “Near Infrared Absorbing Dye”, “Development and Market Trends of Functional Dyes in the 90s”, Chapter 2.3. (1990) CMC), “special function pigments” (edited by Ikemori and Piladani, 1986, issued by CMC Corporation), J. Am. FABIAN, Chem. Rev., 92, pp. 1197 to 1226 (1992), a catalog published in 1995 by Nippon Sensitive Dye Research Institute, Exciton Inc. Known dyes described in the laser dye catalog or patent issued in 1989.

[Curing]
In the present invention, the method for curing each layer of the antireflection film is preferably formed by a crosslinking reaction or a polymerization reaction at the same time as or after application of the coating composition by light irradiation, electron beam irradiation or heating. .
When each layer of the antireflection film is formed by a crosslinking reaction or a polymerization reaction of an ionizing radiation curable compound, the crosslinking reaction or the polymerization reaction is preferably performed in an atmosphere having an oxygen concentration of 10% by volume or less. By forming in an atmosphere having an oxygen concentration of 10% by volume or less, an outermost layer excellent in physical strength and chemical resistance can be obtained.
The oxygen concentration is preferably 5% by volume or less, more preferably the oxygen concentration is 1% by volume or less, particularly preferably the oxygen concentration is 0.5% by volume or less, and most preferably 0.1% by volume or less.

  As a method of reducing the oxygen concentration to 10% by volume or less, it is preferable to replace the atmosphere (nitrogen concentration of about 79% by volume, oxygen concentration of about 21% by volume) with another gas, particularly preferably replacement with nitrogen (nitrogen purge). It is to be.

The light source for light irradiation may be any one in the ultraviolet light region or near infrared light. Ultraviolet, high pressure, medium pressure and low pressure mercury lamps, chemical lamps, carbon arc lamps, metal halide lamps may be used as ultraviolet light sources. Xenon lamps, sunlight, etc. Various available laser light sources having a wavelength of 350 to 420 nm may be irradiated as a multi-beam. Further, examples of the near-infrared light source include a halogen lamp, a xenon lamp, and a high-pressure sodium lamp.
When a near infrared light source is used, it may be used in combination with an ultraviolet light source, or light may be irradiated from the substrate surface side opposite to the coating surface side. Film curing in the depth direction in the coating layer proceeds without delay with the vicinity of the surface, and a cured film having a uniform cured state is obtained.
Irradiation intensity of ultraviolet irradiation is preferably about 0.1~1000mW / cm ^2, irradiation amount on the coating film surface is preferably 10~1000mJ / cm ^2. Further, the temperature distribution of the coating film in the light irradiation step is preferably as uniform as possible, preferably within ± 3 ° C., and more preferably controlled within ± 1.5 ° C. In this range, the polymerization reaction in the in-plane and in-layer depth directions of the coating film proceeds uniformly, which is preferable.

[filtration]
The coating solution used for coating is filtered before coating. As a filter for filtration, it is preferable to use a filter having a pore diameter as small as possible within a range in which components in the coating solution are not removed. For filtration, a filter having a particle size of less than 1.0 μm showing 99.9% capture efficiency is used, and a filter having a particle size of less than 0.75 μm showing 99.9% capture efficiency is preferably used. Filtration pressure is 1.5 MPa or less, more preferably 1 MPa In the following, it is preferable to filter at 0.2 MPa or less.
The filtration filter member is not particularly limited as long as it does not affect the coating solution. Specific examples include stainless steel, polyethylene, polypropylene, nylon, Teflon (trade name), and the like. Among these, a filter made of Teflon (trade name) is preferable because of high uniformity of pore diameter.
It is also preferable to ultrasonically disperse the filtered coating solution immediately before coating to assist defoaming and dispersion holding of the dispersion.
In addition, the measurement method of the capture efficiency shows a value based on ISO / TC131SC6.

[Antireflection film]
FIG. 2 is an example of an antireflection film produced by the production method of the present invention. It has a layer structure in the order of a transparent support (1), a hard coat layer (2), a medium refractive index layer (3), a high refractive index layer (4), and a low refractive index layer (5). Such an antireflection film having a five-layer structure has an optical film thickness of each of the medium refractive index layer, the high refractive index layer, and the low refractive index layer, that is, the product of the refractive index and the film thickness with respect to the design wavelength λ. JP-A-59-50401 describes that nλ / 4 is preferably around or a multiple thereof. However, in order to realize the low reflectance and the reflectance characteristic of the reflected light of the present invention, the medium refractive index layer has the following formula (particularly for the design wavelength λ (= 400 nm to 680 nm) ( It is necessary that the high refractive index layer satisfies the following formula (II) and the low refractive index layer satisfies the following formula (III). The design wavelength is preferably 400 nm to 600 nm, more preferably 450 nm to 550 nm, and most preferably 475 nm to 525 nm.

Formula (I): lλ / 4 × 0.80 <n1d1 <lλ / 4 × 1.00
Formula (II): mλ / 4 × 0.75 <n2d2 <mλ / 4 × 0.95
Formula (III): nλ / 4 × 0.95 <n3d3 <nλ / 4 × 1.05
In the formula, l is 1, n1 is the refractive index of the medium refractive index layer, d1 is the layer thickness (nm) of the medium refractive index layer, m is 2, and n2 is the high refractive index layer. And d2 is the thickness (nm) of the high refractive index layer, n is 1, n3 is the refractive index of the low refractive index layer, and d3 is the low refractive index layer. Layer thickness (nm). Furthermore, for example, n1 is 1.60 to 1.65 and n2 is 1 for a transparent support having a refractive index of 1.45 to 1.55 made of triacetylcellulose (refractive index: 1.49). .85 to 1.95, n3 is preferably a refractive index of 1.35 to 1.45, for example, a refractive index of 1.55 to 1.65 made of polyethylene terephthalate (refractive index: 1.66). N1 is preferably 1.65 to 1.75, n2 is 1.85 to 2.05, and n3 is preferably a refractive index of 1.35 to 1.45. When materials of medium refractive index layer and high refractive index layer having the above refractive index cannot be selected, an equivalent combination of a layer having a refractive index higher than the set refractive index and a layer having a low refractive index is combined. It is known that a film layer can be used to form a layer that is optically equivalent to a medium refractive index layer or a high refractive index layer having a set refractive index, and also to realize the reflectance characteristics of the present invention. Can be used. The “substantially three layers” of the present invention includes an antireflection layer composed of terms having different refractive indexes of four layers and five layers using such an equivalent film.
Moreover, when a hard coat layer (2) is applied on the support (1) or on the support (1) and a low refractive index layer (5) is laminated as a refractive index layer, it is suitable as an antireflection film. (FIGS. 3 and 4). 5 and 6, the hard coat layer (2) is applied on the support (1) or the support (1), and then the high refractive index layer (4) and the low refractive index layer (5) are provided. Although the example which laminated | stacked and was set as the anti-reflective film was shown, it can use suitably. The hard coat layer may have antiglare properties. The antiglare property may be formed by dispersion of matte particles as shown in FIG. 7 or may be formed by surface shaping by a method such as embossing as shown in FIG. 3 to 8 show examples of the structure of the antireflection film.

[Polarizer]
When the antireflection film of the present invention is used as one side of the surface protective film of the polarizer, it is necessary to saponify the surface of the transparent support opposite to the surface on which the antireflection layer is formed with an alkali. . Specific means for the alkali saponification treatment can be selected from the following two (1) and (2). (1) is superior in that it can be processed in the same process as a general-purpose triacetylcellulose film, but since the surface of the antireflection film is saponified, the surface is alkali-hydrolyzed and the film deteriorates. The point that it becomes dirty when the liquid remains can be a problem. In that case, although it becomes a special process, (2) is excellent.
(1) After the antireflection layer is formed on the transparent support, the back surface of the film is saponified by immersing it in an alkaline solution at least once.
(2) Before or after forming the antireflection layer on the transparent support, the alkaline solution is applied to the surface of the antireflection film opposite to the surface on which the antireflection film is formed, heated, then washed with water and Only the back surface of the film is saponified by at least one of the sum treatments.

  Examples of the polarizer include an iodine polarizer, a dye polarizer using a dichroic dye, and a polyene polarizer. In general, a polyvinyl alcohol film (hereinafter referred to as PVA) is preferably used as the iodine polarizer and the dye polarizer. PVA is usually saponified polyvinyl acetate, but modified PVA can also be used. A polarizing film is obtained by dyeing PVA. Examples of dyeing can be performed by any means such as a method of immersing a PVA film in an iodine-potassium iodide aqueous solution, application or spraying of iodine or a dye solution. In the process of producing a polarizing film by stretching PVA, it is preferable to use an additive that crosslinks PVA, for example, boric acids. The transmittance of the polarizing plate is preferably in the range of 30 to 50% and more preferably in the range of 35 to 50% with respect to light having a wavelength of 550 nm. The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

[Image display device]
The antireflection film of the present invention, when used as one side of the surface protective film of a polarizer, is twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), optical It can be preferably used for a transmissive, reflective, or transflective liquid crystal display device of a mode such as a curry compensate bend cell (OCB). When used in a transmissive or transflective liquid crystal display device, it is used in combination with a commercially available brightness enhancement film (a polarized light separation film having a polarization selective layer, such as D-BEF manufactured by Sumitomo 3M Co., Ltd.). Thus, a display device with higher visibility can be obtained. In addition, when a front plate such as an acrylic plate is arranged over the entire surface of the liquid crystal cell in a transmissive, reflective, and transflective liquid crystal display device, not only the polarizing plate on the liquid crystal cell surface side, Adhering to at least one of the inner side and the outer side of the front plate via an adhesive or the like is preferable because reflection at the interface can be reduced. Further, by combining with a λ / 4 plate, it can be used as a reflective or transflective LCD or a surface protection plate for an organic EL display. In addition, the antireflection layer of the present invention is formed on a transparent support such as PET or PEN, and the surface protection plate of a PDA, a cellular phone, a touch panel, a plasma display panel (PDP), or a cathode ray tube display (CRT). It can be applied to various image display devices.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
(Preparation of coating liquid for hard coat layer (HCL-1))
The following components were put into a mixing tank and stirred to obtain a hard coat layer coating solution.
Trimethylolpropane triacrylate (TMPTA, Nippon Kayaku Co., Ltd.)
749.0 parts by weight Poly (glycidyl methacrylate) having a weight average molecular weight of 15000
271.0 parts by weight Methyl ethyl ketone 729.0 parts by weight Cyclohexanone 501.0 parts by weight Photopolymerization initiator (Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) 50.0 parts by weight After stirring these components, the pore size was 0. A coating solution for a hard coat layer was prepared by filtration through a 4 μm polypropylene filter.

(Preparation of titanium dioxide fine particle dispersion)
As titanium dioxide fine particles, titanium dioxide fine particles (MPT-129C, manufactured by Ishihara Sangyo Co., Ltd., TiO ₂ : Co ₃ O ₄ : containing cobalt and subjected to surface treatment using aluminum hydroxide and zirconium hydroxide: Al ₂ O ₃ : ZrO ₂ = 90.5: 3.0: 4.0: 0.5 mass ratio) was used.
The following dispersant (41.2 parts by mass) and cyclohexanone (701.6 parts by mass) were added to 257.2 parts by mass of the particles and dispersed by dynomill to prepare a titanium dioxide dispersion having a mass average diameter of 70 nm.

Dispersant

(Preparation of Medium Refractive Index Layer Coating Solution (ML-1))
In 59.60 parts by mass of the above titanium dioxide dispersion, 40.70 parts by mass of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.), a photopolymerization initiator (Irgacure 907) Ciba Specialty Chemicals Co., Ltd.) 2.19 parts by mass, photosensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) 0.71 parts by mass, methyl ethyl ketone 280.00 parts by mass and cyclohexanone 1050.00 A part by mass was added and stirred. After sufficiently stirring, the mixture was filtered through a polypropylene filter having a particle diameter of 0.8 μm and showing 99.9% trapping efficiency to prepare a coating solution for middle refractive index layer (ML-1).

(Preparation of coating solution for high refractive index layer (HL-1))
A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) 36.6 parts by mass, a photopolymerization initiator (Irgacure 907) 3.1 parts by mass, manufactured by Ciba Specialty Chemicals Co., Ltd., 1.0 parts by mass of photosensitizer (Kayacure-DETX, manufactured by Nippon Kayaku Co., Ltd.), 535.0 parts by mass of methyl ethyl ketone, and cyclohexanone 493 .7 parts by mass was added and stirred. A high refractive index layer coating solution (HL-1) was prepared by filtering through a polypropylene filter having a particle diameter of 0.8 μm and showing 99.9% capture efficiency.

(Preparation of coating solution for low refractive index layer (LL-1))
152.3 parts by mass of a solution obtained by dissolving copolymer P-3 described in JP-A-2004-45462 in methyl ethyl ketone so as to have a concentration of 23.7% by mass, and a terminal methacrylate group-containing silicone resin X-22-164C (Shin-Etsu Chemical Co., Ltd.) 1.1 parts by mass, photo radical generator (Irgacure 907, Ciba Specialty Chemicals Co., Ltd.) 1.8 parts by mass, methyl ethyl ketone 816 parts by mass, and cyclohexanone 28.9 parts by mass Was added and stirred. A low refractive index layer coating solution (LL-1) was prepared by filtration through a PTFE filter having a particle diameter of 0.45 μm and showing 99.9% capture efficiency.

(Preparation of sol solution a)
A reactor equipped with a stirrer and a reflux condenser, 119 parts by mass of methyl ethyl ketone, 101 parts by mass of acryloyloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), diisopropoxyaluminum ethyl acetoacetate (trade name: (Kelope EP-12, manufactured by Hope Pharmaceutical Co., Ltd.) 3 parts by mass and mixed, 30 parts by mass of ion-exchanged water were added and reacted at 60 ° C. for 4 hours, followed by cooling to room temperature to obtain sol solution a. It was. The mass average molecular weight was 1600, and among the components higher than the oligomer component, the component having a molecular weight of 1000 to 20000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.

(Preparation of coating solution for low refractive index layer (LL-2))
Thermally crosslinkable fluorine-containing polymer having a refractive index of 1.42 (JN7228A, solid content concentration 6%, manufactured by JSR Corporation) 12.9 g, silica sol MEK-ST-L (MEK-ST particle size difference, average particle size 45 nm , Solid content concentration 30%, manufactured by Nissan Chemical Co., Ltd.) 1.32 g, sol solution a 0.6 g and methyl ethyl ketone 4.9 g, cyclohexanone 0.6 g were added, and after stirring, the particle size showing 99.9% capture efficiency Was filtered with a 0.45 μm PTFE filter to prepare a coating solution LL-2 for a low refractive index layer. The refractive index of the layer formed with this coating solution was 1.43.

(Preparation of hollow silica dispersion)
Hollow silica fine particle sol (isopropyl alcohol silica sol, CS60-IPA manufactured by Catalyst Chemical Industry Co., Ltd., average particle diameter 60 nm, shell thickness 10 nm, silica concentration 20%, silica particle refractive index 1.31), 499 parts by mass, acryloyloxy 31 parts by mass of propyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-5103) and 1.5 parts by mass of diisopropoxyaluminum ethyl acetoacetate (trade name: Kellop EP-12, manufactured by Hope Pharmaceutical Co., Ltd.) After mixing, 9 parts by mass of ion exchange water was added. After making it react at 60 degreeC for 8 hours, it cooled to room temperature, added 1.8 mass parts of acetylacetone, and obtained the hollow silica dispersion liquid. The resulting hollow silica dispersion had a solid content concentration of 18% by mass and a refractive index after solvent drying of 1.31.

(Preparation of coating liquid LL-3 for low refractive index layer)
DPHA (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd.) 1.5 g
5.7 g of copolymer P-3 described in JP-A-2004-45462
Hollow silica dispersion 19.9g
RMS-033 (silicone compound, manufactured by Gelest) 0.7 g
Irgacure 907 0.2g
Sol liquid a 6.2g
MEK (methyl ethyl ketone) 315.8 g
After stirring the above components, the mixture was filtered through a PTFE filter having a particle diameter of 0.45 μm showing 99.9% trapping efficiency to prepare a coating solution LL-3 for a low refractive index layer. The refractive index of the layer formed with this coating solution was 1.43.

(Preparation of coating liquid LL-4 for low refractive index layer)
DPHA 3.5g
Hollow silica dispersion 20.1g
RMS-033 0.7g
Irgacure 907 0.2g
Sol liquid a 8.1g
MEK 275.9g
After stirring the above components, the mixture was filtered through a PTFE filter having a particle size of 0.45 μm showing 99.9% capture efficiency to prepare a coating solution LL-4 for a low refractive index layer. The refractive index of the layer formed with this coating solution was 1.41.

(Preparation of coating liquid LL-5 for low refractive index layer)
Mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (KAYARAD PET-30 (trade name), manufactured by Nippon Kayaku Co., Ltd.) 90.1 g
Hollow silica dispersion 19.9g
Octafluoropentyl methacrylate 10.0g
After stirring the above components, the mixture was filtered through a PTFE filter having a particle size of 0.45 μm showing 99.9% trapping efficiency to prepare a coating solution LL-5 for a low refractive index layer. The refractive index of the layer formed with this coating solution was 1.48.

(Die coater configuration)
The slot die 13 has an upstream lip land length I _UP of 0.5 mm, a downstream lip land length I _LO of 50 μm, a length of the opening of the slot 16 in the web running direction of 150 μm, and a length of the slot 16 of 50 mm. I used one. The gap between the upstream lip land 18a and the web 12 is 50 μm longer than the gap between the downstream lip land 18b and the web 12 (hereinafter referred to as an overbite length of 50 μm), and the gap between the downstream lip land 18b and the web 12 is set. _GL was set to 50 μm. Further, the gap G _B between the gap G _S, and the back plate 40a and the web 12 between the side plate 40b and the web 12 of the decompression chamber 40 were both 200 [mu] m.

Example 1
(Production of optical thin film)
Application speed of 25 m / min using a die coater having the above-described configuration on a low refractive index layer coating liquid (LL-1) on a 100 μm-thick PET film (FD-100M, manufactured by Fuji Photo Film Co., Ltd.) 1100 m was continuously applied. The degree of vacuum in the vacuum chamber was 0.8 kPa. Then, after drying at 90 ° C. for 30 seconds, using a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) while purging with nitrogen so that the atmosphere has an oxygen concentration of 0.1% by volume or less, An ultraviolet ray having an illuminance of 600 mW / cm ² and an irradiation amount of 400 mJ / cm ² was irradiated to form an optical thin film (refractive index of 1.45). In the above, the coating and drying steps are performed in an air atmosphere with an air cleanliness of 30 particles / (cubic meter) or less as particles of 0.5 μm or more, and the cleanliness described in JP-A-10-309553 is just before the coating. High air was blown at a high speed to separate the deposits from the film surface, and coating was performed while removing dust by a method of sucking with a suction port close to the film. The charged voltage of the base before dust removal was 200 V or less. Said application | coating was performed at each process of sending-out-dust removal-application-dry- (UV or heat) hardening-winding.
Using a spectrophotometer (manufactured by JASCO Corporation) at a point of 100 m and 600 m from the start of coating, the spectral reflectance at an incident angle of 5 ° was measured and the film thickness was measured to be 83 nm and 85 nm, respectively. It was. Moreover, when the same measurement was performed with respect to each point of 200m-700m, 300m-800m, 400m-900m, and 500m-1000m, the average value of the film thickness difference was 2.4%. Further, the surface of each film was observed with an optical microscope, and the number of point defects around 0.1 mm ² was counted. As a result, the average value was 3. However, what appeared to be 2 μm when observed with an optical microscope was counted as a point defect. The results are shown in Table 1.

Example 2
Application was carried out in the same manner as in Example 1 except that the particle diameter showing 99.9% trapping efficiency of the filter was changed to 0.9 μm. The results are shown in Table 1. When five sets of film thicknesses at a point 500 m away were taken under the same conditions as in Example 1 to derive the average value of the film thickness difference, the average value of the film thickness difference was 2.8%. Further, when the number of point defects was counted in the same manner as in Example 1, the average value was 7.

Comparative Example 1
Application was carried out in the same manner as in Example 1 except that the particle diameter showing 99.9% trapping efficiency of the filter was changed to 1.2 μm. The results are shown in Table 1. When five sets of film thicknesses at points 500 m apart were taken under the same conditions as in Example 1 and the average value of the film thickness difference was derived, the average value of the film thickness difference was 2.2%. Further, when the number of point defects was counted by the same method as in Example 1, the average value was 18. Since the point defect-causing substance in the coating liquid was not sufficiently removed by the filter, the point defect was confirmed, and the surface was whitish due to irregular reflection of the point defect.

Comparative Example 2
Coating was performed in the same manner as in Comparative Example 1 except that the dry film thickness was 180 nm. The results are shown in Table 1. When five sets of film thicknesses at a distance of 500 m were taken under the same conditions as in Example 1 and the average value of the film thickness differences was derived, the average value of the film thickness differences was 1.9%. Further, when the number of point defects was counted by the same method as in Example 1, the average value was 11. Point defects are confirmed because the point defect-causing substance in the coating solution is not sufficiently removed by the filter. Since the film thickness is thick, a relatively small point defect-causing substance is obscured, but the degree of the degree is insufficient, and the surface has become whitish due to irregular reflection of point defects.

Comparative Example 3
Application was carried out in the same manner as in Example 3 except that the dry film thickness was 250 nm. The results are shown in Table 1. When five sets of film thicknesses at points 500 m apart were taken under the same conditions as in Example 1 to derive the average value of the film thickness difference, the average value of the film thickness difference was 1.7%. Further, when the number of point defects was counted in the same manner as in Example 1, the average value was 7. Since the film thickness is increased and the point defects are obscured, the point defects were not confirmed even when the presence or absence of the point defects of the optical thin film was visually confirmed. However, since the optical thin film is thick, the performance as an optical thin film is not sufficiently satisfied.

Comparative Example 4
Coating was performed in the same manner as in Example 1 except that the coating method was changed from the die coating method to the gravure coating method. The results are shown in Table 1. When five sets of film thicknesses at points 500 m apart were taken under the same conditions as in Example 1 to derive the average value of the film thickness difference, the average value of the film thickness difference was 7.2%. The change in film thickness was large due to evaporation of the solvent during coating and blade scraping over time. Further, when the number of point defects was counted in the same manner as in Example 1, the average value was 42. When the presence or absence of a point defect in the optical thin film was visually confirmed, the point defect was confirmed and the surface was whitish due to irregular reflection of the point defect.

Comparative Example 5
Coating was performed in the same manner as in Comparative Example 1 except that the coating solution was changed from LL-1 to LL-2. The results are shown in Table 1. When five sets of film thicknesses at points 500 m apart were taken under the same conditions as in Example 1 and the average value of the film thickness differences was derived, the average value of the film thickness differences was 6.9%. The change in film thickness was large due to evaporation of the solvent during coating and blade scraping over time. Further, when the number of point defects was counted by the same method as in Example 1, the average value was 1. Since LL-2 does not contain a polymerizable unsaturated bond, no point defects were confirmed even when the presence or absence of point defects in this optical thin film was confirmed by visual observation.

Examples 3-7
Coating was performed in the same manner as in Example 1 except that the coating solution was changed from LL-1 to LL-3, LL-4, LL-5, ML-1, and HL-1. The results are shown in Table 1. When five sets of film thicknesses at a distance of 500 m were taken under the same conditions as in Example 1 and the average value of the film thickness differences was derived, the average values of the film thickness differences were 2.1%, 2.3%, 1 It was 0.9%, 3.3%, and 2.4%. Further, when the number of point defects was counted in the same manner as in Example 1, the average values were 3, 5, 2, 5, and 3, respectively. When the presence or absence of point defects in these optical thin films was confirmed by visual observation, none of the point defects were confirmed.

Comparative Examples 6-10
Coating was performed in the same manner as in Comparative Example 1 except that the coating solution was changed from LL-1 to LL-3, LL-4, LL-5, ML-1, and HL-1. The results are shown in Table 1. When five sets of film thicknesses at a distance of 500 m were taken under the same conditions as in Example 1 and the average value of the film thickness differences was derived, the average values of the film thickness differences were 6.2%, 7.3%, It was 0.9%, 7.9%, and 6.1%. The change in film thickness was large due to evaporation of the solvent during coating and blade scraping over time. Further, when the number of point defects was counted in the same manner as in Example 1, the average values were 37, 35, 24, 51, and 42, respectively. When the presence or absence of point defects in these optical thin films was visually confirmed, point defects were confirmed in any of the optical thin films.

Example 8
(Preparation of antireflection film)
The surface of the application side of a triacetyl cellulose film (TD80UF, manufactured by Fuji Photo Film Co., Ltd.) with a film thickness of 80 μm is subjected to charge removal with an ultrasonic dust remover, and the coating liquid for hard coat layer (HCL-1) is configured as described above. The coating was performed at a coating speed of 25 m / min using a die coater having In the application of HCL-1, the gap _GL between the downstream lip land 18b and the web 12 was changed to 80 μm, and the degree of vacuum in the vacuum chamber was 0.8 kPa. Then, after drying at 80 ° C., using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with a nitrogen purge so that the atmosphere has an oxygen concentration of 1.0% by volume or less, an illuminance of 400 mW / cm ^2, and an irradiation dose of 500 mJ / cm ² to cure the coating layer, to form a hard coat layer having a thickness of 8 [mu] m. On the hard coat layer, a medium refractive index layer coating solution (ML-1) was applied at a coating speed of 25 m / min using a die coater having the above-described configuration. The degree of vacuum in the vacuum chamber was 0.8 kPa. Then, after drying at 100 ° C. for 30 seconds, using a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) while purging with nitrogen so that the atmosphere has an oxygen concentration of 0.1% by volume or less, the illuminance The coating layer was cured by irradiating ultraviolet rays at 550 mW / cm ² and an irradiation amount of 550 mJ / cm ² to form a medium refractive index layer (refractive index 1.63, film thickness 64 nm).
On the middle refractive index layer, a coating solution for high refractive index layer (HL-1) was applied at a coating speed of 25 m / min using a die coater having the above configuration. The degree of vacuum in the vacuum chamber was 0.8 kPa. Then, after drying at 100 ° C. for 30 seconds, using a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) while purging with nitrogen so that the oxygen concentration becomes 0.1 vol% or less, An ultraviolet ray having an illuminance of 550 mW / cm ² and an irradiation amount of 550 mJ / cm ² was irradiated to form a high refractive index layer (refractive index 1.90, film thickness 103 nm).
On the high refractive index layer, the low refractive index layer coating solution (LL-1) was applied at a coating speed of 25 m / min using a die coater having the above-described configuration. The degree of vacuum in the vacuum chamber was 0.8 kPa. Then, after drying at 90 ° C. for 30 seconds, using a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) while purging with nitrogen so that the atmosphere has an oxygen concentration of 0.1% by volume or less, An ultraviolet ray having an illuminance of 600 mW / cm ² and an irradiation amount of 400 mJ / cm ² was irradiated to form a low refractive index layer (refractive index 1.45, film thickness 83 nm). In this way, an antireflection film was produced.

  In the above, the coating and drying steps are performed in an air atmosphere with an air cleanliness of 30 particles / (cubic meter) or less as particles of 0.5 μm or more, and the cleanliness described in JP-A-10-309553 is just before the coating. High air was blown at a high speed to separate the deposits from the film surface, and coating was performed while removing dust by a method of sucking with a suction port close to the film. The charged voltage of the base before dust removal was 200 V or less. Said application | coating was performed in each process of sending-out-dust removal-application-dry- (UV or heat) hardening-winding up for every layer.

  The prepared antireflection film was added at 2.0 mol / l. It was immersed in an aqueous NaOH solution at 55 ° C. for 2 minutes to saponify the triacetyl cellulose surface on the back side of the film, and an 80 μm thick triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Photo Film Co., Ltd.) under the same conditions. A polarizing plate was prepared by adsorbing iodine to polyvinyl alcohol with the film saponified with and adhering and protecting both sides of the polarizer prepared by stretching. The thus-prepared polarizing plate is a liquid crystal display device of a notebook computer equipped with a transmission type TN liquid crystal display device (Sumitomo 3M Co., Ltd., which is a polarization separation film having a polarization selection layer) so that the antireflection film side is the outermost surface. When the D-BEF made of D-BEF is replaced with the polarizing plate on the viewing side), there is very little reflection of the background, the color of the reflected light is remarkably reduced, and the display surface A display device with a very high display quality, in which the uniformity of the inside is ensured and there are no point defects, was obtained.

It is a schematic sectional drawing of the coater using a slot die. FIG. 2 is an example of an antireflection film produced by the production method of the present invention. On the support (1) or the support (1), the hard coat layer (2) is applied, and then the high refractive index layer (4) and the low refractive index layer (5) are laminated to form an antireflection film. It is sectional drawing which shows typically the done example. It is sectional drawing which shows the other aspect of the antireflection film of this invention typically. It is sectional drawing which shows the other aspect of the antireflection film of this invention typically. It is sectional drawing which shows the other aspect of the antireflection film of this invention typically. It is sectional drawing which shows typically the antireflection film to which anti-glare property was provided by dispersion | distribution of matte particles. It is sectional drawing which shows typically the anti-reflective film to which the glare-proof property was provided by the method of embossing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Coater 11 Backup roll 12 Web 13 Slot die 14 Coating liquid 14a Bead 14b Coating film 15 Pocket 16 Slot 16a Slot opening part 17 Tip lip 18a Upstream lip land 18b Downstream lip land (1) Transparent support (2) Hard coat Layer (3) Medium refractive index layer (4) High refractive index layer (5) Low refractive index layer

Claims (7)

  A method for producing an optical film by forming one or more films on a continuous substrate that is continuously conveyed, wherein at least one layer is coated with a coating solution containing a compound having a polymerizable unsaturated bond. 99.9% trapping efficiency is less than 1.0 μm as a filter formed by coating so that the dry film thickness of the coating layer is 200 nm or less and used for filtration of the coating liquid performed before the coating A method for producing an optical film, comprising using the filter. 2. The optical film according to claim 1, wherein the number of point defects observed with a diameter of 1.0 μm or more when the optical film is observed with an optical microscope is 10 or less per 0.1 mm ^2. Method.   When forming an optical film by forming one or more films on a continuously supported long support, the film thickness of the coating film at a certain point on the optical film and the long support 500 m continuously from this point The method for producing an optical film according to claim 1 or 2, wherein the difference in film thickness of the coating film at the point applied on the body is in the range of ± 5%.   The optical film obtained by the manufacturing method in any one of Claims 1-3.   The antireflection film which consists of an optical film obtained by the manufacturing method in any one of Claims 1-3.   A polarizing plate, wherein the antireflection film according to claim 5 is used for at least one of the polarizing films.   An image display device, wherein the antireflection film according to claim 5 or the polarizing plate according to claim 6 is disposed on an image display surface.

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