JP7088187B2 - Optical film manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing an optical film.

In a display device such as a liquid crystal display device or an organic electroluminescence display device, a resin optical film may be provided. As such an optical film, a film formed of a resin containing an alicyclic structure-containing polymer is known (for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2010-107958 International Publication No. 2014/175312

When a film formed of a resin containing an alicyclic structure-containing polymer is used as an optical film, an appropriate resin layer may be provided on the surface thereof. For example, an easy-adhesive layer may be formed on the surface of a film made of a resin containing an alicyclic structure-containing polymer with an appropriate resin in order to enhance the adhesiveness. In general, a film formed of a resin containing an alicyclic structure-containing polymer has poor adhesiveness, and it is difficult to bond it to other members with high adhesive strength even if an adhesive is used. By using the easy-adhesive layer, it is possible to bond to the above-mentioned member with high adhesive strength.

The resin layer such as the easy-adhesive layer was usually formed by a coating method with respect to the film formed of the resin containing the alicyclic structure-containing polymer. Specifically, it is usual that a film formed of a resin containing an alicyclic structure-containing polymer is coated with a coating liquid containing a resin layer material and dried to form a resin layer. rice field. However, in the field of industrial production, a method other than the coating method may be desired as a method for forming a resin layer on a film formed of a resin containing an alicyclic structure-containing polymer.

For example, when trying to form a resin layer on both sides of a film made of a resin containing an alicyclic structure-containing polymer by a coating method, it is required to form a resin layer one side at a time due to the nature of the coating method. As the number of processes increases, the manufacturing cost tends to increase. Therefore, from the viewpoint of suppressing the manufacturing cost by forming the resin layer on both sides at the same time, it is desired to develop a method other than the coating method. Further, as a method other than forming the resin layer on both sides of the film formed of the resin containing the alicyclic structure-containing polymer as in the above example, a method other than the coating method is used as a method for forming the resin layer. May be desired.

Therefore, the present inventor has investigated a transfer method as a method for forming a resin layer on the surface of a film formed of a resin containing an alicyclic structure-containing polymer. In the transfer method, the resin layer formed on the temporary support is bonded to a film formed of a resin containing an alicyclic structure-containing polymer, and then the temporary support is peeled off to form an alicyclic structure. A resin layer is formed on the surface of a film formed of a resin containing a contained polymer. However, since the film formed of the resin containing the alicyclic structure-containing polymer generally has poor adhesion to the resin layer, the resin layer formed by the transfer method tends to be easily peeled off from the film. .. In particular, it is particularly difficult to form a resin layer on a stretched film by a transfer method because a film formed of a resin containing an alicyclic structure-containing polymer tends to have further reduced adhesion after stretching.

Further, as examined by the present inventor, when a crystalline alicyclic structure-containing polymer is used, the film formed of the resin containing the alicyclic structure-containing polymer has adhesion to the resin layer. Turned out to be particularly low. Furthermore, the adhesiveness of the film formed of the resin containing the alicyclic structure-containing polymer having crystallinity to the resin layer further decreases as the crystallization of the alicyclic structure-containing polymer progresses, and the resin layer It was found that the peeling of the resin is particularly likely to occur.

The present invention has been devised in view of the above problems, and includes a film surface of a base film made of a resin containing an alicyclic structure-containing polymer and a resin layer formed on a temporary support. It is an object of the present invention to provide a method for producing an optical film, which can produce an optical film containing a base film and a resin layer that is difficult to peel off from the base film.

As a result of diligent studies to solve the above problems, the present inventor has a step of forming a resin layer on the temporary support surface of a temporary support having a temporary support surface having a predetermined surface free energy, a process of forming a resin layer on the temporary support surface, and a film surface of a base film. In the step of subjecting the film to a hydrophilic treatment so that the surface free energy of the film surface is within a predetermined range, the resin layer formed on the temporary support surface of the temporary support and the surface of the film subjected to the hydrophilic treatment of the base film are subjected to the hydrophilic treatment. The above-mentioned production method includes a step of bonding, a step of peeling off the temporary support, and a step of heat-treating the resin layer and the base film at a temperature equal to or higher than the glass transition temperature of the alicyclic structure-containing polymer. We have found that the problem can be solved and completed the present invention.
That is, the present invention includes the following.

[1] A step of forming a resin layer on the temporary support surface of a temporary support having a temporary support surface having a surface free energy of 20 mJ / m ² or less.
A step of subjecting the film surface of a base film made of a resin containing an alicyclic structure-containing polymer to a hydrophilic treatment so that the surface free energy of the film surface is 40 mJ / m ² or more.
A step of bonding the resin layer formed on the temporary support surface of the temporary support and the surface of the film subjected to the hydrophilic treatment of the base film.
The step of peeling off the temporary support and
A method for producing an optical film, comprising a step of heat-treating the resin layer and the base film at a temperature equal to or higher than the glass transition temperature of the alicyclic structure-containing polymer.
[2] The method for producing an optical film according to [1], wherein the alicyclic structure-containing polymer has crystallinity.
[3] The method for producing an optical film according to [2], wherein the crystallinity of the alicyclic structure-containing polymer is less than 3% before the film surface is subjected to a hydrophilic treatment.
[4] The method for producing an optical film according to [2] or [3], wherein crystallization of the alicyclic structure-containing polymer proceeds in the step of subjecting the resin layer and the base film to the heat treatment.
[5] The step of applying the heat treatment to the resin layer and the base film is
The step of stretching the base film and
The method for producing an optical film according to any one of [2] to [4], which comprises a step of advancing the crystallization of the alicyclic structure-containing polymer contained in the base film after stretching.
[6] The method for producing an optical film according to any one of [1] to [5], wherein the hydrophilic treatment is at least one selected from the group consisting of corona treatment, plasma treatment and excimer treatment.
[7] In any one of [1] to [6], the resin layer is formed of at least one selected from the group consisting of urethane resin, olefin resin, polyester resin, epoxy resin and acrylic resin. The method for manufacturing an optical film according to the description.

According to the present invention, the film surface of the base film formed of the resin containing the alicyclic structure-containing polymer and the resin layer formed on the temporary support are bonded together to form the base film and the base material. It is possible to provide a manufacturing method capable of manufacturing an optical film containing a resin layer that is difficult to peel off from the film.

Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be arbitrarily modified and carried out without departing from the scope of claims of the present invention and the equivalent scope thereof.

In the following description, the "long" film means a film having a length of 5 times or more with respect to the width, preferably 10 times or more, and specifically in a roll shape. A film that has a length that allows it to be rolled up, stored, or transported. The upper limit of the ratio of the length to the width of the film is not particularly limited, but may be, for example, 100,000 times or less.

[1. Outline of manufacturing method of optical film]
The method for producing an optical film of the present invention is a method for producing an optical film including a base film formed of a resin containing an alicyclic structure-containing polymer and a resin layer. This manufacturing method
Step (I) of forming a resin layer on the temporary support surface of a temporary support having a temporary support surface having a predetermined surface free energy.
Step (II) of applying hydrophilic treatment to the film surface of the base film so that the surface free energy of the film surface is within a predetermined range.
Step (III), in which the resin layer formed on the temporary support surface of the temporary support and the surface of the base film treated with hydrophilicity are bonded together.
Step of peeling off the temporary support (IV) and
Step (V) of heat-treating the resin layer and the base film at a temperature equal to or higher than the glass transition temperature of the alicyclic structure-containing polymer.
including.

According to the above-mentioned production method, it is possible to produce an optical film including a base film and a resin layer that is difficult to peel off from the base film. Further, in the above-mentioned manufacturing method, it is possible to prevent a part or all of the resin layer from remaining on the temporary support surface of the temporary support, so that the resin layer can be smoothly formed on the film surface of the base film. ..

In the step (III) of the above-mentioned manufacturing method, the resin layer and the film surface of the base film are usually directly bonded to each other. Therefore, in the optical film, the base film and the resin layer are usually in direct contact with each other. Here, the resin layer and the film surface of the base film are "directly" bonded to each other in a manner in which there is no other layer between the resin layer and the film surface of the base film. Say. Further, "direct contact" between the base film and the resin layer means that there is no other layer between the base film and the resin layer.

Further, the step (V) may include a step (V-1) of stretching the base film. Further, when the alicyclic structure-containing polymer contained in the base film has crystallinity, the step (V) includes a step (V-2) of advancing the crystallization of the alicyclic structure-containing polymer. You may.

[2. Step of forming a resin layer on the temporary support surface of the temporary support (I)]
The method for producing an optical film includes a step (I) of forming a resin layer on a temporary support surface of a temporary support. In this step (I), a temporary support having a temporary support surface having a predetermined surface free energy is usually prepared, and a resin layer is formed on the temporary support surface.

The surface free energy of the temporary support surface is usually 20 mJ / m ² or less, preferably less than 20 mJ / m ² , and more preferably less than 19 mJ / m ² . The temporary support surface having such a low surface free energy has excellent peelability. Therefore, when the temporary support having the temporary support surface is peeled off in the step (IV), it is possible to suppress the residual of the resin layer on the temporary support surface. The lower limit of the surface free energy of the temporary support surface is not particularly limited and may be, for example, 10 mJ / m ² or more.

The surface free energy of a surface can be determined by measuring the contact angles of water and hexadecane with respect to the surface and applying the measured contact angles to the Owns Wendt model. Specifically, the surface free energy can be measured by the measuring method described in the examples.

As the temporary support, a resin film is usually used. Above all, a long resin film is preferable from the viewpoint of efficiently producing an optical film by the roll-to-roll method. As the resin film, for example, a film formed of a resin material having a small surface free energy may be used. Examples of the resin material having a small surface free energy include a resin containing a polymer such as an alicyclic structure-containing polymer, polyethylene terephthalate, polyethylene, polybutylene terephthalate, polypropylene, and polytetrafluoroethylene. Further, as the resin film, for example, a film whose surface has been subjected to a mold release treatment with an appropriate mold release agent may be used.

The resin layer formed on the temporary support surface of the temporary support is formed of a type of resin according to the characteristics required for the optical film. As the resin forming the resin layer, at least one selected from the group consisting of urethane resin, olefin resin, polyester resin, epoxy resin and acrylic resin is preferable. By using these resins, the resin layer can function as an easy-adhesion layer, so that an optical film having excellent adhesiveness to other members can be realized.

As the urethane resin, a resin containing polyurethane or a crosslinked product thereof can be used. Examples of polyurethanes include polyurethanes derived from various polyols and polyisocyanates. Examples of the polyol include any one of an aliphatic polyester polyol, a polyether polyol, a polycarbonate-based polyol, and a polyethylene terephthalate polyol obtained by reacting a polyol compound with a polybasic acid; and a mixture thereof. Examples of the polyol compound include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, glycerin, and trimethylolpropane. Examples of the polybasic acid include a polyvalent carboxylic acid containing a dicarboxylic acid and a tricarboxylic acid, or a polyvalent carboxylic acid such as an anhydride thereof. Examples of the dicarboxylic acid include adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid and the like. Examples of the tricarboxylic acid include trimellitic acid and the like. Examples of the polyether polyol include poly (oxypropylene ether) polyol and poly (oxyethylene-propylene ether) polyol. In the polyurethane, for example, after the reaction between the polyol and the polyisocyanate, the hydroxyl group remaining unreacted can be used as a polar group capable of the cross-linking reaction with the functional group in the cross-linking agent. As the polyurethane, a polycarbonate-based polyurethane derived from a polycarbonate-based polyol and a polyisocyanate and having a carbonate structure in its skeleton is preferable. For the urethane resin, for example, the description in JP-A-2016-182568 can be referred to.

As the polyurethane, those contained in a commercially available water-based emulsion as a water-based urethane resin may be used. The water-based urethane resin is a composition containing polyurethane and water, and is usually one in which polyurethane and optional components contained as necessary are dispersed in water. Examples of water-based urethane resins include ADEKA's "ADEKA BONTITA" series, Mitsui Chemicals' "Orestar" series, DIC's "Bondic" series, and "Hydran (WLS201, WLS202, etc.)" series. , Bayer's "Implanil" series, Kao's "Poise" series, Sanyo Kasei Kogyo's "Samplen" series, Daiichi Kogyo Seiyaku Co., Ltd.'s "Superflex" series, Kusumoto Kasei's "" The "NEOREZ" series, the "Sancure" series manufactured by Lubrizol, etc. can be used.

As the olefin resin, a resin containing an acid-modified polyolefin having an unsaturated carboxylic acid component content of 0.1% by weight to 10% by weight or a crosslinked product thereof can be used. Preferred examples of the olefin component which is the main component of the acid-modified polyolefin include alkene having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 2-butene, 1-butene, 1-pentene and 1-hexene, and alkenes having 2 to 6 carbon atoms thereof. Examples include mixtures. Among them, from the viewpoint of enhancing the adhesion of the resin layer, an alkene having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene and 1-butene is more preferable, ethylene and propylene are more preferable, and ethylene is particularly preferable. On the other hand, the unsaturated carboxylic acid component which is a modification component of the acid-modified polyolefin includes, for example, acrylic acid, methacrylic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, fumaric acid, crotonic acid, and half of unsaturated dicarboxylic acid. Examples include esters and halfamides. Of these, acrylic acid, methacrylic acid, and (maleic anhydride) maleic acid are preferable, and acrylic acid and (maleic anhydride) maleic acid are particularly preferable because they can enhance the adhesion of the resin layer and suppress cracking. The unsaturated carboxylic acid component is usually copolymerized in an acid-modified polyolefin, and its form is not particularly limited. Examples of the copolymerization state include random copolymerization, block copolymerization, and graft copolymerization (graft modification). For the olefin resin, for example, the description in JP-A-2014-240174 can be referred to.

As the acid-modified polyolefin, a commercially available product may be used. Examples of the commercially available product of the aqueous dispersion include "Arrow Base (Arrow Base SA-1200, Arrow Base SB-1200, Arrow Base SE-1200, Arrow Base SB-1010" series (manufactured by Unitika Ltd.)). Be done.

As the polyester resin, a resin containing polyester obtained by reacting the polyol compound with the polybasic acid or a crosslinked product thereof can be used. In this polyester, for example, after the reaction between the polyol compound and the polybasic acid is completed, the hydroxyl group and the carboxyl group remaining as unreacted can be used as polar groups capable of the cross-linking reaction with the cross-linking agent. Further, the polyester may be a copolymer of a copolymerization component having a polar group such as a hydroxyl group or a carboxyl group in combination with the above-mentioned polyol compound and polybasic acid. Further, the polyester resin preferably further contains an acrylic polymer in combination with polyester or a crosslinked product thereof in order to improve the adhesion of the resin layer. For the polyester resin, for example, the description in JP-A-2015-024511 can be referred to.

As the polyester, a commercially available product may be used. Examples of commercially available water-soluble or water-dispersed polyester products include the "Nichigo Polyester (Nichigo Polyester W-0030, Nichigo Polyester W-0005S30WO, Nichigo Polyester WR-961, etc.)" series (manufactured by Nippon Synthetic Chemical Co., Ltd.). ), "Pesresin A (Pesresin A-210, Pessresin A-520, Pessresin A-684G, Pessresin A-695GE, etc.)" series (manufactured by Takamatsu Oil & Fat Co., Ltd.) and the like.

As the epoxy resin, any epoxy resin such as a one-component curable epoxy resin and a two-component curable epoxy resin can be used. Of these, those containing a water-soluble epoxy polymer are preferable. Preferred examples of water-soluble epoxy polymers include polyamide epoxy polymers. This polyamide epoxy polymer can be obtained by reacting a polyamide polyamine obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid with epichlorohydrin. Examples of commercially available products of such a polyamide epoxy polymer include "Smiley's Resin 650 (30)" and "Smiley's Resin 675" manufactured by Sumika Chemtech. For the epoxy resin, for example, the description in JP-A-2008-26352 can be referred to.

When a water-soluble epoxy polymer is used, it is preferable to use a water-soluble polymer such as polyvinyl alcohol in combination in order to further improve the coatability. This polyvinyl alcohol includes not only partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, but also modified polyvinyl such as carboxyl group-modified polyvinyl alcohol, acetacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. Contains alcohol. Examples of commercially available polyvinyl alcohol include "KL-318", which is an anionic group-containing polyvinyl alcohol manufactured by Kuraray.

As the acrylic resin, a resin containing an acrylic polymer or a crosslinked product thereof can be used. Examples of the acrylic polymer include a homopolymer of an acrylic monomer, a copolymer of two or more kinds of acrylic monomers, and a copolymer of one or more kinds of acrylic monomers and other monomers. Examples of the acrylic monomer include acrylic acid esters such as acrylic acid and alkyl acrylate, methacrylic acid esters such as acrylamide, acrylonitrile, methacrylic acid and alkyl methacrylate, methacrylamide and methacrylic nitrile. Of these, homopolymers and copolymers of acrylic monomers selected from the group consisting of acrylic acid esters and methacrylic acid esters are preferable. Particularly preferable examples include homopolymers and copolymers of acrylic monomers selected from the group consisting of acrylic acid esters and methacrylic acid esters having an alkyl group having 1 to 6 carbon atoms. Further, the acrylic polymer was combined with the above-mentioned acrylic monomer and copolymerized with a copolymerization component having a polar group such as a hydroxyl group and a carboxyl group so that the reaction with the functional group of the cross-linking agent (cross-linking reaction) was possible. Those are preferable. For the acrylic resin, for example, the description in JP-A-2015-024511 can be referred to.

In the resin layer described above, polymers such as polyurethane, polyolefin, polyester, epoxy polymer, and acrylic polymer may be crosslinked. When cross-linked, the polymer becomes a cross-linked product by reaction with a cross-linking agent. As the cross-linking agent used in this cross-linking, a compound having two or more functional groups in the molecule capable of reacting with a functional group such as a polar group contained in the polymer to form a bond can be used. Examples of the cross-linking agent include epoxy compounds, carbodiimide compounds, oxazoline compounds, isocyanate compounds and the like. In addition, one type of cross-linking agent may be used alone, or two or more types may be used in combination at any ratio. Of these, an epoxy compound is preferable as the cross-linking agent.

As the epoxy compound, a polyfunctional epoxy compound having two or more epoxy groups in the molecule can be used. As a result, the cross-linking reaction can proceed and the mechanical strength of the resin layer can be effectively improved.

As the epoxy compound, a compound that is soluble in water or can be dispersed in water and emulsified is preferable from the viewpoint of ease of use. Examples of epoxy compounds include 1 mol of glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexaneglycol, and neopentyl glycol. And a diepoxy compound obtained by etherification with 2 mol of epichlorohydrin; poly obtained by etherification of 1 mol of polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol and 2 mol or more of epichlorohydrin. Epoxy compounds; diepoxy compounds obtained by esterification of 1 mol of dicarboxylic acid such as phthalic acid, terephthalic acid, oxalic acid, adipic acid and 2 mol of epichlorohydrin; and the like.

More specifically, examples of the epoxy compound include 1,4-bis (2', 3'-epoxypropyloxy) butane, 1,3,5-triglycidyl isocyanurate, and 1,3-dicrysidyl-5- (γ-). Acetoxy-β-oxypropyl) isocinurate, sorbitol polyglycidyl ethers, polyglycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, diglycerol polyglucidyl ethers, 1,3,5-triglycidyl (2-hydroxyethyl) isocia Epoxy compounds such as nurate, glycerol polyglycerol ethers and trimethylolpropane polyglycidyl ethers are preferred. Specific examples of commercially available products include the "Denacol (Denacol EX-521, EX-614B, etc.)" series manufactured by Nagase ChemteX Corporation.

Further, the resin forming the resin layer may further contain any component in combination with the above-mentioned polymer or a crosslinked product thereof. Optional components include, for example, curing accelerators, curing aids, particles, heat-resistant stabilizers, weather-resistant stabilizers, leveling agents, surfactants, antioxidants, antistatic agents, slip agents, anti-blocking agents, anti-fog agents. Examples include agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes and the like. Any component may be used alone or in combination of two or more at any ratio.

The resin forming the resin layer may be one type or two or more types. Therefore, for example, the above-mentioned urethane resin, olefin resin, polyester resin, epoxy resin, and acrylic resin may be used in combination of two or more. For example, a resin containing a combination of polyurethane and an acid-modified polyolefin may be used, or a resin containing a combination of polyester and an acrylic polymer may be used.

The thickness of the resin layer can be arbitrarily set according to the use of the resin layer. For example, the thickness of the resin layer that can function as an easy-adhesion layer is preferably 10 nm or more, more preferably 30 nm or more, particularly preferably 50 nm or more, preferably 5 μm or less, more preferably 2 μm or less, and particularly preferably 1 μm or less. be. By setting the thickness of the easy-adhesion layer to be equal to or greater than the lower limit, the optical film can be bonded to other members with sufficient adhesive strength. Further, by setting the thickness of the easy-adhesive layer to the upper limit or less, the occurrence of deformation of the easy-adhesive layer, which is a relatively soft layer, is suppressed, and the optical film can be easily wound as a roll. Further, when the thickness of the easy-adhesive layer is within the above range, sufficient adhesion between the base film and the easy-adhesive layer can be obtained, and the thickness of the optical film can be reduced.

The formation of the resin layer on the temporary support surface of the temporary support can be performed, for example, by a coating method. In this coating method, a coating liquid containing a component such as a polymer contained in a resin forming a resin layer or a precursor thereof is usually applied to a temporary support surface, and the applied coating liquid is cured. .. In this coating method, the coating liquid can usually be a resin layer as it is. Alternatively, in this coating method, the coating liquid can usually become a resin layer through a reaction of components in the coating solution, volatilization of a solvent, or the like, if necessary. Thereby, a resin layer can be obtained as a layer of a resin containing a part or all of the components contained in the coating liquid or a reaction product thereof.

The amount of the polymer such as polyurethane or its precursor in the coating liquid is preferably 60% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, based on 100% by weight of the total solid content in the coating liquid. It is% by weight.

When the coating liquid contains a cross-linking agent, the amount of the cross-linking agent is usually 0.1 part by weight or more, preferably 1 part by weight, based on 100 parts by weight of the total of the polymer and its precursor in the coating liquid. As mentioned above, it is more preferably 2 parts by weight or more, usually 20 parts by weight or less, preferably 15 parts by weight or less, and more preferably 10 parts by weight or less. By setting the amount of the cross-linking agent to the lower limit of the above range or more, the cross-linking reaction proceeds sufficiently, so that the mechanical strength of the resin layer can be appropriately improved, and the amount of the cross-linking agent should be set to the upper limit or less. As a result, the residual unreacted cross-linking agent can be reduced, and the mechanical strength of the resin layer can be appropriately improved.

The coating liquid may contain a solvent, if necessary. Examples of the solvent include water; organic solvents such as methanol, ethanol, isopropyl alcohol, acetone, tetrahydrofuran, N-methylpyrrolidone, dimethylsulfoxide, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, methyl ethyl ketone, and triethylamine. In addition, one type of solvent may be used alone, or two or more types may be used in combination at any ratio. Of these, water is preferable as the solvent. As a preferred example, the coating liquid may be an aqueous emulsion in which the concentration of the organic solvent is less than 1% by weight. The amount of the solvent is preferably set appropriately so that the viscosity of the coating liquid is in a range suitable for coating.

Examples of coating liquid coating methods include wire bar coating method, dip method, spray method, spin coating method, roll coating method, gravure coating method, air knife coating method, curtain coating method, slide coating method, and extrusion. The coat method and the like can be mentioned.

Further, in the method of forming the resin layer on the temporary support surface of the temporary support, an arbitrary step may be further performed after applying the coating liquid to the temporary support surface. For example, when the coating liquid contains a solvent, the coating liquid may be dried to remove the solvent. Further, for example, when the cross-linking liquid contains a cross-linking agent, cross-linking may be performed by the cross-linking agent. The method of drying and cross-linking is optional. For example, the drying may be any method such as vacuum drying and heat drying. Above all, from the viewpoint of rapidly advancing the reaction such as the crosslinking reaction together with the drying, it is preferable to cure the coating liquid by heating and drying. When the coating liquid is cured by heating, the heating temperature can be appropriately set within a range in which the coating liquid can be dried to remove the solvent and at the same time the solid content in the coating liquid can be cured.

[3. Step of applying hydrophilic treatment to the film surface of the base film (II)]
The method for producing an optical film includes a step (II) of subjecting the film surface of the base film to a hydrophilic treatment. In this step (II), a base film usually formed of a resin containing an alicyclic structure-containing polymer is prepared, and the film surface of the base film is subjected to a hydrophilic treatment.

The alicyclic structure-containing polymer is a polymer having an alicyclic structure in the molecule. The alicyclic structure-containing polymer is usually excellent in mechanical strength, transparency, dimensional stability and light weight, and has low hygroscopicity. Examples of such an alicyclic structure-containing polymer include a polymer obtained by a polymerization reaction using a cyclic olefin as a monomer or a hydrogenated product thereof. Further, as the alicyclic structure-containing polymer, either a polymer having an alicyclic structure in the main chain or a polymer having an alicyclic structure in the side chain can be used. Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, but the cycloalkane structure is preferable from the viewpoint of thermal stability and the like.

The number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, more preferably 6 or more, preferably 30 or less, and more preferably 20 or less. Particularly preferably, the number is 15 or less. When the number of carbon atoms contained in one alicyclic structure is within the above range, mechanical strength, heat resistance, and moldability are highly balanced.

The proportion of the structural unit having an alicyclic structure in the alicyclic structure-containing polymer is preferably 30% by weight or more, more preferably 50% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight. That is all. By increasing the proportion of structural units having an alicyclic structure as described above, the flexibility and heat resistance of the optical film can be enhanced.
Further, in the alicyclic structure-containing polymer, the balance other than the structural unit having the alicyclic structure is not particularly limited and may be appropriately selected depending on the purpose of use.

As the alicyclic structure-containing polymer, either one having crystallinity or one having no crystallinity may be used, or both may be used in combination. Here, the polymer having crystallinity means a polymer having a melting point Mp. That is, the crystalline polymer means a polymer whose melting point Mp can be observed with a differential scanning calorimeter (DSC). By using a crystalline alicyclic structure-containing polymer, the impact strength, solvent resistance, diffraction resistance, and tear strength of the optical film can be particularly enhanced. Further, by using the alicyclic structure-containing polymer having no crystallinity, the manufacturing cost of the optical film can be reduced.

Examples of the crystalline alicyclic structure-containing polymer include the following polymers (α) to (δ). Among these, the polymer (β) is preferable as the alicyclic structure-containing polymer having crystallinity because it is easy to obtain an optical film having excellent flexibility, heat resistance and folding resistance.
Polymer (α): A ring-opening polymer of a cyclic olefin monomer having crystallinity.
Polymer (β): A hydrogenated product of the polymer (α), which has crystallinity.
Polymer (γ): An addition polymer of a cyclic olefin monomer having crystallinity.
Polymer (δ): A hydrogenated product of the polymer (γ), which has crystallinity.

Specifically, as the alicyclic structure-containing polymer having crystallinity, a ring-opening polymer of dicyclopentadiene having crystallinity and a hydrogenated product of the ring-opening polymer of dicyclopentadiene. The crystallinity is more preferable, and the hydrogenated additive of the ring-opening polymer of dicyclopentadiene, which has crystallinity, is particularly preferable. Here, in the open-ring polymer of dicyclopentadiene, the ratio of the structural unit derived from dicyclopentadiene to all the structural units is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. More preferably, it refers to a polymer of 100% by weight.

The hydride of the ring-opening polymer of dicyclopentadiene preferably has a high proportion of racemic diad. Specifically, the proportion of the repeating unit racemic diad in the hydride of the ring-opening polymer of dicyclopentadiene is preferably 51% or more, more preferably 60% or more, and particularly preferably 65% or more. A high proportion of racemic diads indicates a high syndiotactic stereoregularity. Therefore, the higher the proportion of racemic diad, the higher the melting point of the hydride of the ring-opening polymer of dicyclopentadiene tends to be.
The proportion of racemo diads can be determined based on the ¹³ C-NMR spectral analysis described in Examples described below.

A resin containing an alicyclic structure-containing polymer having a high crystallinity is usually excellent in properties such as flexibility, heat resistance, folding resistance, and solvent resistance. Therefore, the crystalline alicyclic structure-containing polymer contained in the optical film preferably has a high crystallinity. However, the surface of the base film containing the alicyclic structure-containing polymer having a high crystallinity has poor adhesion to other resins. Therefore, it is preferable that the crystallization proceeds after the resin layer is bonded to the base film, and therefore, at the time before the step (V), the alicyclic contained in the resin forming the base film is contained. The crystallinity of the formula-containing polymer is preferably low. Therefore, it is preferable that the crystallinity of the alicyclic structure-containing polymer contained in the base film is low before the film surface is subjected to the hydrophilic treatment in the step (II). Specifically, the crystallinity of the crystalline alicyclic structure-containing polymer contained in the base film is preferably less than 3%, more preferably 2 before the surface of the film is subjected to the hydrophilic treatment. %, Especially preferably less than 1%.

The crystallinity is an index showing the ratio of crystallized alicyclic structure-containing polymers contained in the base film. The crystallinity of the crystalline alicyclic structure-containing polymer contained in the base film can be measured by an X-ray diffraction method. Specifically, the crystallinity can be measured by the measuring method described in the examples.

The melting point Mp of the crystalline alicyclic structure-containing polymer is preferably 200 ° C. or higher, more preferably 230 ° C. or higher, and preferably 290 ° C. or lower. By using such a crystalline alicyclic structure-containing polymer having a melting point Mp, an optical film having a better balance between moldability and heat resistance can be obtained.

The alicyclic structure-containing polymer having crystallinity as described above can be produced, for example, by the method described in International Publication No. 2016/067893.

On the other hand, the non-crystalline alicyclic structure-containing polymer is, for example, (1) norbornene-based polymer, (2) monocyclic cyclic olefin polymer, (3) cyclic conjugated diene polymer, (4). Examples thereof include vinyl alicyclic hydrocarbon polymers and hydrides thereof. Among these, the norbornene-based polymer and its hydride are more preferable from the viewpoint of transparency and moldability.

Examples of the norbornene-based polymer include a ring-opening polymer of a norbornene monomer, a ring-opening copolymer of a norbornene monomer and another monomer capable of ring-opening copolymerization, and hydrides thereof; an addition polymer of a norbornene monomer. Examples thereof include an addition copolymer of a norbornene monomer and another copolymerizable monomer. Among these, the ring-opening polymer hydride of the norbornene monomer is particularly preferable from the viewpoint of transparency.
As the alicyclic structure-containing polymer described above, for example, those described in JP-A-2002-321302 can be arbitrarily selected and used.

As the alicyclic structure-containing polymer, one type may be used alone, or two or more types may be used in combination at any ratio.

The glass transition temperature Tg of the alicyclic structure-containing polymer is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, further preferably 90 ° C. or higher, preferably 250 ° C. or lower, and more preferably 170 ° C. or lower. .. The alicyclic structure-containing polymer having a glass transition temperature in such a range is less likely to be deformed and stressed when used at a high temperature, and is excellent in durability.

The weight average molecular weight (Mw) of the alicyclic structure-containing polymer is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 10,000 or more, and particularly preferably 25,000 or more. Is 1,000,000 or less, more preferably 500,000 or less, still more preferably 100,000 or less, particularly preferably 80,000 or less, and particularly preferably 50,000 or less. A polymer having such a weight average molecular weight has an excellent balance between molding processability and heat resistance.

The molecular weight distribution (Mw / Mn) of the alicyclic structure-containing polymer is preferably 1.0 or more, more preferably 1.2 or more, particularly preferably 1.5 or more, preferably 10 or less, and more preferably. It is 4.0 or less, more preferably 3.5 or less. Here, Mn represents a number average molecular weight. An alicyclic structure-containing polymer having such a molecular weight distribution is excellent in molding processability.

The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) can be measured as polystyrene-equivalent values by gel permeation chromatography (GPC) using tetrahydrofuran as a developing solvent.

The proportion of the alicyclic structure-containing polymer in the resin forming the base material is preferably 50% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, and particularly preferably 90% by weight or more. be. By setting the ratio of the alicyclic structure-containing polymer to the lower limit of the above range or more, the excellent characteristics of the alicyclic structure-containing polymer can be effectively exhibited.

The resin forming the base material may further contain any component in combination with the alicyclic structure-containing polymer. Optional components include, for example, antioxidants such as phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants; light stabilizers such as hindered amine light stabilizers; petroleum waxes, Fishertroph waxes, etc. Waxes such as polyalkylene waxes; sorbitol compounds, metal salts of organic phosphates, metal salts of organic carboxylic acids, nuclear agents such as kaolin and talc; diaminostylben derivatives, coumarin derivatives, azole derivatives (eg, benzoxazole derivatives, etc.) Fluorochrome agents such as benzotriazole derivatives, benzoimidazole derivatives, and benzothiazole derivatives), carbazole derivatives, pyridine derivatives, naphthalic acid derivatives, and imidazolone derivatives; benzophenone-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, benzotriazole-based UV absorbers such as UV absorbers; Inorganic fillers such as talc, silica, calcium carbonate, glass fibers; Colorants; Flame retardants; Flame retardant aids; Antistatic agents; Plastics; Near infrared absorbers; Lubricants; Fillers ; Any polymer other than the alicyclic structure-containing polymer, such as a soft polymer; and the like. Further, any component may be used alone or in combination of two or more at any ratio.

The base film preferably has a high total light transmittance. Specifically, the total light transmittance of the base film is preferably 80% or more, more preferably 85% or more, and particularly preferably 88% or more. The total light transmittance can be measured in the wavelength range of 400 nm to 700 nm using an ultraviolet / visible spectrometer.

The base film preferably has a small haze. Specifically, the haze of the substrate film is preferably less than 3.0%, more preferably less than 2.0%, particularly preferably less than 1.0%, and ideally 0%. The haze can be measured using a haze meter.

The thickness of the base film is preferably 5 μm or more, more preferably 10 μm or more, particularly preferably 15 μm or more, preferably 200 μm or less, more preferably 100 μm or less, and particularly preferably 50 μm or less. By setting the thickness of the base film to the lower limit or more, the mechanical strength of the optical film can be increased. By setting the thickness of the base film to the upper limit or less, the thickness of the optical film can be reduced.

The base film can be produced by molding a resin containing an alicyclic structure-containing polymer into a film by an arbitrary molding method. Examples of the molding method include an injection molding method, a melt extrusion molding method, a press molding method, an inflation molding method, a blow molding method, a calendar molding method, a casting molding method, and a compression molding method. Among these, the melt extrusion molding method is preferable because the thickness can be easily controlled.

When the base film is produced by the melt extrusion molding method, the conditions for extrusion molding are preferably as follows. The cylinder temperature (molten resin temperature) is preferably (Tg + 80 ° C.) or higher, more preferably (Tg + 100 ° C.) or higher, preferably (Tg + 180 ° C.) or lower, and more preferably (Tg + 150 ° C.) or lower. Further, particularly when a crystalline alicyclic structure-containing polymer is used, the cylinder temperature is preferably Tm or higher, more preferably (Tm + 20 ° C.) or higher, preferably (Tm + 100 ° C.) or lower, and more preferably (Tm + 100 ° C.) or lower. Tm + 50 ° C.) or less. Further, the cast roll temperature is preferably (Tg-30 ° C.) or higher, preferably Tg or lower, and more preferably (Tg-15 ° C.) or lower. By producing the base film under such conditions, a base film having a preferable thickness can be easily produced. Here, "Tm" represents the melting point of the alicyclic structure-containing polymer, and "Tg" represents the glass transition temperature of the alicyclic structure-containing polymer.

After preparing the base film, the film surface of the base film is subjected to hydrophilic treatment. When a resin layer is formed on one film surface of the base film, hydrophilic treatment is applied to the one film surface. When the resin layer is formed on both film surfaces of the base film, both film surfaces are subjected to hydrophilic treatment. By applying such a hydrophilic treatment, the surface free energy of the film surface of the base film is adjusted to a predetermined range.

The specific surface free energy of the film surface of the base film after the hydrophilic treatment is usually 40 mJ / m ² or more, preferably 50 mJ / m ² or more, and particularly preferably 60 mJ / m ² or more. Since the film surface of the base film has such a high surface free energy, the resin layer can be stably fixed to the film surface. Therefore, when the temporary support is peeled off in the step (IV), the temporary support is formed. It is possible to suppress the residual of the resin layer on the temporary support surface of the above. The upper limit of the surface free energy of the film surface is not particularly limited and may be, for example, 77 mJ / m ² or less.

As the hydrophilic treatment, it is preferable to carry out at least one selected from the group consisting of corona treatment, plasma treatment and excimer treatment. Further, these processes may be performed individually by one type or in combination of two or more types. By applying these treatments to the film surface of the base film, hydrophilic groups such as hydroxyl groups, carboxyl groups, and carbonyl groups are usually generated on the film surface. This makes it possible to improve the surface free energy of the film surface.

The treatment conditions for the hydrophilic treatment are appropriately set so that the surface free energy of the film surface of the base film can be kept within a desired range. The specific treatment conditions differ depending on the type of the base film and the treatment device, but can be set as follows, for example.

In corona treatment, usually, a high voltage is applied between a dielectric and an insulated electrode to generate a corona, and a base film is passed between the dielectric and the electrode to treat the film surface. .. Generally, the surface free energy of the corona-treated film surface is adjusted according to the type of electrodes, the electrode spacing, the voltage, the humidity, and the type of the base film to be treated. The distance between the electrode and the base film is preferably 1 mm to 5 mm, more preferably 1 mm to 3 mm. The transport speed of the base film subjected to the corona treatment is preferably 0.01 m / min to 10 m / min, more preferably 0.05 m / min to 5 m / min. The electrode width is preferably 0.1 m to 1 m. The corona output is preferably 100 W or more, and is preferably 3 kW or less, more preferably 1.5 kW or less, from the viewpoint of suppressing scratches on the base film. In the corona treatment performed while transporting the base film, the processing strength calculated by "processing strength = (output) / (conveying speed x electrode width)" is preferably 4.2 kW · min / m ² or more.

In the plasma treatment, the film surface of the base film is usually treated by performing plasma discharge in a gas atmosphere such as an inert gas and an oxygen gas. This plasma treatment may be performed under a reduced pressure of, for example, about 0.1 Torr to 1 Torr, but is preferably performed under atmospheric pressure from the viewpoint of efficiently performing the treatment while transporting the base film. Examples of the type of gas used in the plasma treatment include nitrogen; oxygen; rare gases such as argon and helium; acrylic acid; hydroxyalkyl; and fluorine-based compounds such as CF ₄ , CHF ₃ , C ₂ F ₆ ; and the like. .. Preferred gas includes, for example, a mixed gas in which an inert gas such as nitrogen and oxygen are mixed at a ratio of 95.0: 5.0 to 99.9: 0.1. The distance between the electrode and the base film is preferably 1 mm to 5 mm, more preferably 1 mm to 3 mm. The transport speed of the base film to be subjected to the plasma treatment is preferably 1 m / min to 70 m / min, more preferably 3 m / min to 50 m / min. The electrode width is preferably 0.1 m to 1 m. The plasma output is preferably 50 W or more. The frequency range is preferably 10 kHz to 100 kHz. In the plasma treatment performed while transporting the base film, the treatment strength calculated by "treatment strength = (output) / (transport speed x electrode width)" is preferably 0.028 kW · min / m ² or more.

In the excimer treatment, the film surface of the base film is usually treated by irradiating light having a center wavelength of less than 180 nm using an excimer lamp. The lower limit of the central wavelength of the irradiated light is not particularly limited and may be, for example, 100 nm or more. Here, the "center wavelength of light" means a wavelength that brings about the maximum emission intensity in the emission spectrum. In excimer processing, light having a desired center wavelength can be obtained by selecting the type of excimer lamp. For example, the central wavelength of the light emitted from the Ar excimer lamp is 126 nm, the central wavelength of the light emitted from the Kr excimer lamp is 146 nm, and the central wavelength of the light emitted from the ArBr excimer lamp is 165 nm. The central wavelength of the light emitted from the Xe excimer lamp is 172 nm, and the central wavelength of the light emitted from the ArCl excimer lamp is 175 nm. The light irradiation time is 0.1 seconds to 150 seconds, preferably 1 second to 120 seconds, and more preferably 10 seconds to 90 seconds. The illuminance is preferably 50 mW / cm ² or more. The distance between the excimer lamp and the base film is preferably 10 mm or less.

[4. Step of bonding the base film and the resin layer (III)]
After the steps (I) and (II), the resin layer formed on the temporary support surface of the temporary support and the surface of the base film subjected to the hydrophilic treatment are bonded together (III). I do. In this step (III), the resin layer and the film surface of the base film are usually directly bonded to each other without going through another layer such as an adhesive layer.

From the viewpoint of preventing bubbles from remaining between the resin layer and the base film, the bonding is preferably performed so that the resin layer and the base film are pressed against each other. For example, by passing a temporary support having a resin layer formed on a temporary support surface and a base film between a pair of nip rolls, the resin layer and the base film may be pressed against each other for bonding. good.

The above-mentioned bonding is usually performed at a temperature lower than the crystallization start temperature of the alicyclic structure-containing polymer contained in the resin forming the base film. From the viewpoint of reducing the energy for heating and suppressing the manufacturing cost, the bonding is preferably performed at room temperature.

[5. Step of peeling off the temporary support (IV)]
After the step (III), the step (IV) of peeling off the temporary support is performed. Since the surface free energy of the film surface of the base film is within the above range, the resin layer can be stably fixed to the film surface of the base film. Further, when the surface free energy of the temporary support surface of the temporary support is within the above-mentioned range, the resin layer can be smoothly separated from the temporary support surface of the temporary support. Therefore, the temporary support is smoothly peeled off. Therefore, it is possible to prevent a part or all of the resin layer from remaining on the temporary support surface of the temporary support to be peeled off.
By peeling off the temporary support, a multi-layer film including a base film and a resin layer can be obtained.

[6. Step of heat-treating the base film and resin layer (V)]
After the step (IV), a step (V) of heat-treating the resin layer and the base film is performed. The heat treatment temperature is set to be equal to or higher than the glass transition temperature of the alicyclic structure-containing polymer contained in the base film. At such a heat treatment temperature, the adhesion between the resin layer and the base film is enhanced, and an optical film containing the base film and a resin layer that is difficult to peel off from the base film can be manufactured.

When the resin contained in the resin layer has a glass transition temperature, the glass transition temperature of the resin contained in the resin layer is usually lower than the glass transition temperature of the alicyclic structure-containing polymer contained in the base film. Therefore, the heat treatment temperature in the step (V) is usually higher than the glass transition temperature of the resin contained in the resin layer. Further, when the glass transition temperature of the resin contained in the resin layer is higher than the glass transition temperature of the alicyclic structure-containing polymer contained in the base film, the adhesion between the resin layer and the base film is effective. The heat treatment temperature in the step (V) is preferably set to a higher temperature than the glass transition temperature of the resin contained in the resin layer.

The specific heat treatment temperature is preferably (Tg + 30 ° C.) or higher, more preferably (Tg + 50 ° C.) or higher, particularly preferably (Tg + 70 ° C.) or higher, preferably (Tg + 120 ° C.) or lower, and more preferably (Tg + 110 ° C.). Hereinafter, it is particularly preferably (Tg + 100 ° C.) or less. When the heat treatment temperature is at least the lower limit of the above range, the adhesion between the resin layer and the base film can be effectively enhanced. Further, when the heat treatment temperature is not more than the upper limit of the above range, the white turbidity of the base film can be suppressed. Here, "Tg" represents the glass transition temperature of the alicyclic structure-containing polymer contained in the base film.

The treatment time for applying the heat treatment can be arbitrarily set as long as the adhesion between the resin layer and the base film can be enhanced. The specific processing time is preferably 5 seconds or longer, more preferably 15 seconds or longer, and particularly preferably 30 seconds or longer. When the treatment time is at least the lower limit of the above range, the adhesion between the resin layer and the base film can be effectively enhanced. The upper limit of the processing time is not particularly limited, but may be, for example, 5 minutes or less.

The step (V) may include a step (V-1) of stretching the base film, if necessary. In this step (V-1), the base film is stretched by stretching the base film and the multilayer film including the resin layer. Usually, this stretching is performed under temperature conditions equal to or higher than the glass transition temperature of the alicyclic structure-containing polymer contained in the base film. Therefore, in the step (V-1), both the heat treatment for the resin layer and the base film and the stretching treatment for the base film can be performed.

There are no particular restrictions on the stretching method of the base film, and any stretching method can be used. Examples of the stretching method include a method of uniaxially stretching the base film in the longitudinal direction (longitudinal uniaxial stretching method), a method of uniaxially stretching the base film in the width direction (horizontal uniaxial stretching method), and the like. Biaxial stretching such as a simultaneous biaxial stretching method in which the material film is stretched in the longitudinal direction and at the same time in the width direction, and a sequential biaxial stretching method in which the base film is stretched in one of the longitudinal and width directions and then stretched in the other. Methods; and a method of stretching the substrate film in an oblique direction that is neither parallel nor perpendicular to the width direction, such as more than 0 ° and less than 90 ° with respect to the width direction (diagonal stretching method). As such a stretching method, for example, the method described in International Publication No. 2016/067893 can be used.

The stretching temperature in the step (V-1) is preferably Tg ° C. or higher, preferably (Tg + 60 ° C.) or lower, and more preferably (Tg + 50 ° C.) or lower. By stretching in such a temperature range, the polymer molecules contained in the base film can be appropriately oriented. Here, "Tg" represents the glass transition temperature of the alicyclic structure-containing polymer contained in the base film.

The draw ratio in the step (V-1) can be appropriately selected according to the attributes such as optical characteristics, thickness, and strength obtained after stretching, and is usually 1.1 times or more, usually 10 times or less, preferably 10 times or less. It is 5 times or less. Here, when stretching is performed in a plurality of different directions as in the biaxial stretching method, the stretching ratio is the total stretching ratio represented by the product of the stretching ratios in each stretching direction. By setting the draw ratio to be equal to or lower than the upper limit of the above range, the possibility of the film breaking can be reduced, so that the optical film can be easily manufactured.

By applying the above-mentioned stretching treatment to the base film in the step (V-1), an optical film having desired characteristics can be obtained.

Step (V) is a step of advancing the crystallization of the alicyclic structure-containing polymer contained in the base film, if necessary, when the base film contains an alicyclic structure-containing polymer having crystallization. (V-2) may be included. In this step (V-2), the substrate film and the multilayer film provided with the resin layer are heated to a predetermined temperature to promote the crystallization of the alicyclic structure-containing polymer. .. Usually, the crystallization of the alicyclic structure-containing polymer is carried out under a temperature condition equal to or higher than the glass transition temperature of the alicyclic structure-containing polymer contained in the base film. Therefore, in the step (V-2), both the heat treatment of the resin layer and the base film and the crystallization treatment of the alicyclic structure-containing polymer contained in the base film can be performed. When the step (V) includes a step (V-1) of stretching the base film, the step (V-2) for advancing the crystallization of the alicyclic structure-containing polymer is usually a step (V-). It is done after 1).

Crystallization is preferably carried out in a state where at least two edges of the multilayer film including the base film are held and tensioned. The state in which the multilayer film is tensioned means a state in which tension is applied to the multilayer film. However, the state in which the multilayer film is tense does not include the state in which the multilayer film is substantially stretched. Further, substantially stretched means that the stretch ratio of the multilayer film in any direction is usually 1.1 times or more. When at least two edges of the double glazing are held and tense, deformation due to thermal shrinkage of the double glazing is prevented in the region between the held edges. Therefore, crystallization can proceed without impairing the smoothness of the film.

In order to prevent deformation over a large area of the double glazing, the edges of the double glazing, including the two opposite edges, should be held and the area between the held edges should be tense. Is preferable. For example, in a rectangular single-wafer multi-layer film, two opposite ends (for example, the ends on the long side or the ends on the short side) are held between the two ends. By making the region tense, deformation can be prevented on the entire surface of the single-wafer multi-layer film. Also, in a long multi-layer film, the two ends at the widthwise ends (that is, the ends on the long side) are held so that the area between the two ends is in a tense state. This makes it possible to prevent deformation on the entire surface of the long multilayer film. In the multi-layer film whose deformation is hindered in this way, even if stress is generated in the film due to heat shrinkage, the occurrence of deformation such as wrinkles is suppressed. When a stretched multi-layer film is used, deformation can be further suppressed by holding at least two edges orthogonal to the stretching direction (in the case of biaxial stretching, the direction in which the stretching ratio is large). It will be certain. As such a holder, for example, the one described in International Publication No. 2016/067893 can be used.

In the step (V-2), as described above, the temperature of the base film is adjusted to a predetermined treatment temperature, and the crystallization of the alicyclic structure-containing polymer contained in the base film is promoted. At this time, the specific treatment temperature is usually Tg or more, preferably (Tg + 20 ° C.) or more, more preferably (Tg + 30 ° C.) or more, and usually Tm or less, preferably (Tm-20 ° C.) or less, more preferably. It is (Tm-40 ° C.) or less. Here, "Tm" represents the melting point of the crystalline alicyclic structure-containing polymer contained in the base film, and "Tg" represents the crystalline alicyclic structure-containing polymer contained in the base film. Represents the glass transition temperature of the polymer. When the treatment temperature is at least the lower limit of the above range, the crystallization of the alicyclic structure-containing polymer can be efficiently promoted. Further, when the treatment temperature is not more than the upper limit of the above range, the white turbidity of the base film can be suppressed.

In the step (V-2), the treatment time for maintaining the temperature of the base film in the above temperature range is preferably 1 second or longer, more preferably 5 seconds or longer, preferably 30 minutes or shorter, and more preferably 10 seconds. Less than a minute. When the treatment time is at least the lower limit of the above range, the crystallization of the alicyclic structure-containing polymer having crystallinity can be sufficiently promoted, so that the flexibility, heat resistance, and folding resistance of the optical film can be sufficiently promoted. Etc. can be enhanced. Further, when the treatment time is not more than the upper limit of the above range, the white turbidity of the base film can be suppressed.

By applying the above crystallization treatment to the base film in the step (V-2), the crystallinity of the crystalline alicyclic structure-containing polymer contained in the base film can be increased. An optical film having excellent properties such as flexibility, heat resistance, fold resistance, and solvent resistance can be obtained.

[7. Arbitrary process]
The method for producing an optical film may further include any step in combination with the above-mentioned steps.
As an arbitrary step, for example, after the step (V-2), a relaxation step of heat-shrinking the base film to remove residual stress can be mentioned.

Further, as an arbitrary step, for example, a step of providing an arbitrary layer other than the base film and the resin layer on the optical film can be mentioned. The arbitrary layer is usually provided on the surface of the base film opposite to the resin layer. Examples of the arbitrary layer include a conductive layer, an antireflection layer, a hard coat layer, an antistatic layer, an antiglare layer, an antifouling layer, a separator film layer and the like.

[8. Optical film]
According to the above-mentioned manufacturing method, it is possible to obtain an optical film including a base film and a resin layer formed on the film surface of the base film and difficult to be peeled off from the base film. In this optical film, the base film is stretched, the base film contains a crystalline alicyclic structure-containing polymer, and further, the crystals of the alicyclic structure-containing polymer are described above. Even if the polymerization is progressing, the adhesion between the base film and the resin layer can be improved.

In this optical film, the resin layer may be formed on only one film surface of the base film, or may be formed on both film surfaces of the base film. An optical film having resin layers on both film surfaces of the base film can form both resin layers at the same time. For example, each of the above-mentioned steps (II) to (V) can be simultaneously performed on both film surfaces of the base film to form two resin layers at the same time. Therefore, unlike the formation of the resin layer by the coating method, it is not necessary to form the resin layer one side at a time, so that the number of steps can be reduced and the manufacturing time can be shortened, and the manufacturing cost can be suppressed.

Since the optical film contains a base film formed of a resin containing an alicyclic structure-containing polymer, the excellent properties exhibited by the alicyclic structure-containing polymer can be exhibited. Therefore, the optical film is usually excellent in mechanical strength, transparency, dimensional stability and light weight, and has low hygroscopicity. Further, when a crystalline alicyclic structure-containing polymer is used, the optical film has, in addition to the above-mentioned excellent properties, flexibility, heat resistance, folding resistance, low water absorption and the like. Excellent in characteristics.

Among them, from the viewpoint of making properties such as flexibility, heat resistance, folding resistance, and low water absorption particularly good, the alicyclic structure-containing polymer having crystallinity in the base film contained in the optical film is used. , It is preferable to have a high crystallinity. The specific range of crystallinity is preferably 10% or more, more preferably 15% or more, still more preferably 30% or more, particularly preferably 50% or more, and particularly preferably 60% or more. Such a high crystallinity can be achieved by advancing the crystallization of the alicyclic structure-containing polymer in the step (V). The upper limit of crystallinity is ideally 100%, but usually 90% or less, or 80% or less.

Further, since the optical film contains a resin layer, it can exhibit excellent characteristics based on the resin layer. For example, an optical film containing an easy-adhesive layer as a resin layer can exhibit excellent adhesiveness on the surface on the easy-adhesive layer side. Therefore, it is possible to bond the optical film to another member with a high adhesive strength on the surface on the easy-adhesive layer side via an adhesive or an adhesive.

The optical film preferably has a high total light transmittance. Specifically, it is preferable that the total light transmittance of the optical film falls within the same range as described above as the range of the total light transmittance of the base film.

The optical film preferably has a small haze. Specifically, the haze of the optical film preferably falls within the same range as described above as the range of the haze of the base film.

The optical film can be arbitrarily applied to optical applications and can be used, for example, as a component of a display device. Above all, it is preferable to use the optical film as a component of the touch sensor of the liquid crystal display device by utilizing its excellent heat resistance and mechanical strength (particularly, flexibility). In particular, an optical film provided with a base film containing a crystalline alicyclic structure-containing polymer is preferable because it has excellent folding resistance and can be applied to a flexible display device.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples shown below, and may be arbitrarily modified and carried out without departing from the scope of claims of the present invention and the equivalent scope thereof.
In the following description, "%" and "part" representing quantities are based on weight unless otherwise specified. In addition, the operations described below were performed under normal temperature and pressure conditions unless otherwise specified.

[Evaluation method]
(Thickness measurement method)
The thickness of each layer contained in the film was measured as follows. The refractive index of each layer of the sample film was measured using ellipsometry (“M-2000” manufactured by Woolam Co., Ltd.). Then, using the measured refractive index, the thickness of the film was measured with an optical interferometry film thickness meter (“MCPD-9800” manufactured by Otsuka Electronics Co., Ltd.).

(Measuring method of weight average molecular weight and number average molecular weight)
The weight average molecular weight and the number average molecular weight of the polymer were measured as polystyrene-equivalent values using a gel permeation chromatography (GPC) system (“HLC-8320” manufactured by Tosoh Corporation). At the time of measurement, an H type column (manufactured by Tosoh Corporation) was used as the column, and tetrahydrofuran was used as the solvent. The temperature at the time of measurement was 40 ° C.

(Measurement method of glass transition temperature Tg, melting point Tm and crystallization temperature Tpc of hydride of ring-opening polymer of dicyclopentadiene)
A sample heated to 300 ° C. in a nitrogen atmosphere is rapidly cooled with liquid nitrogen and heated at 10 ° C./min using a differential operating calorimeter (DSC) to obtain a glass transition temperature Tg, melting point Tm and crystallization temperature of the sample. Tpc was calculated respectively.

(Measurement method of glass transition temperature of polyurethane)
The aqueous dispersion of polyurethane used in the examples was poured into a container treated with Teflon (registered trademark) and dried at room temperature for 24 hours. Then, it was dried in an oven at 120 degreeC for another 1 hour, and a layer of polyurethane having a thickness of 150 μm was prepared. The glass transition temperature of this layered material was measured from the peak of tan δ using a dynamic viscoelasticity measuring device (“Rheogel-E4000” manufactured by UBM). At this time, when two peaks appear, the peak with the lower temperature is adopted as the glass transition temperature.

(Measuring method of hydrogenation rate of polymer)
The hydrogenation rate of the polymer was measured by ¹ H-NMR measurement at 145 ° C. using orthodichlorobenzene ^- d4 as a solvent.

(Measuring method of racemic diad ratio of polymer)
Using orthodichlorobenzene-d ⁴ / trichlorobenzene-d ³ (mixing ratio (mass basis) 1/2) as a solvent, apply the inverse-gated decoupling method at 200 ° C. to perform ¹³ C-NMR measurement of the polymer. gone. In the results of this ¹³ C-NMR measurement, the signal of 43.35 ppm derived from meso-diad and the signal of 43.43 ppm derived from racemic diad were used as the reference shift with the peak of 127.5 ppm of orthodichlorobenzene ^- d4 as a reference shift. Was identified. Based on the intensity ratios of these signals, the proportion of racemic diads in the polymer was determined.

(Measuring method of polymer crystallinity)
The crystallinity was confirmed by X-ray diffraction according to JIS K0131. Specifically, a wide-angle X-ray diffractometer (“RINT 2000” manufactured by Rigaku Co., Ltd.) was used to obtain the diffracted X-ray intensity from the crystallized portion, and the following formula was obtained from the ratio with the total diffracted X-ray intensity. The crystallinity was determined by (I).
Xc = K · Ic / It (I)
In the above formula (I), Xc represents the crystallinity of the test sample, Ic represents the diffraction X-ray intensity from the crystallized portion, It represents the entire diffraction X-ray intensity, and K represents the correction term.

(Measurement method of surface free energy)
The surface free energy of the surface of the film was measured by the following method.
Water and hexadecane were prepared as liquid samples. For each of these liquid samples, the contact angle with respect to the surface of the film was measured. The method for measuring the contact angle was as follows.
<Contact angle measurement method>
-Measuring device: AutoDispenser AD-31 (manufactured by Kyowa Interface Science Co., Ltd.)
-Control analysis software: FAMAS ver3.13
-Contact angle measurement method: Suspension method-Analysis method: Young-Laplace method-Teflon (registered trademark) coated needle: 18G (or 22G)
-Liquid volume: 3 μL to 4 μL
・ Measurement waiting time: 3000ms
-Number of measurements: Measured 10 times and adopted the average value.

The measured contact angle θ was applied to the Owens Wendt model below to calculate the surface free energy r _S of the surface of the film. In this Owens Wendt model, the film corresponds to a solid sample. Further, in this Owns Wendt model, the meanings of the symbols are as shown in Table 1 below, and the values of r _L , r _L ^d and r _L ^p of the liquid sample are as shown in Table 2.

[Evaluation method of transferability of easy-adhesive layer]
After the temporary support was peeled off, the surface of the peeled temporary support was visually observed. As a result of observation, the transferability of the easy-adhesion layer was determined according to the following criteria.
◯: Adhesive pieces made of a portion of the easy-adhesive layer having a diameter of 50 μm or more do not remain on the surface of the temporary support.
Δ: One or more adhered pieces made of a portion of the easy-adhesive layer having a diameter of 50 μm or more remain on the surface of the temporary support.
X: The temporary support could not be peeled off from the easy-adhesive layer.

[Evaluation method of adhesion between easy-adhesion layer and base film]
Using a cutter, 11 cuts were made in the easy-adhesion layer of the optical film in the vertical and horizontal directions at 1 mm intervals to create 100 1 mm square squares (go board) (10 × 10). Cellophane tape was attached to the surface of this easy-adhesive layer, peeled off quickly, and the number of squares remaining without peeling was counted. The larger the number of squares remaining without peeling, the better the adhesion between the easy-adhesion layer and the base film.

[Measurement of peel strength]
The surface of the easy-adhesion layer of the optical film was subjected to corona treatment. Further, one side of an unstretched film made of a norbornene-based resin (“Zeonoa film” manufactured by ZEON Corporation, thickness 100 μm, glass transition temperature of resin 160 ° C.) was subjected to corona treatment. An ultraviolet curable adhesive (“CRB1352” manufactured by Toyo Ink Co., Ltd.) was applied to the corona-treated surface of the unstretched film. Then, the corona-treated surface of the optical film was bonded to the surface coated with this adhesive using a laminator. Using a high-pressure mercury lamp, the adhesive was crosslinked by irradiating with ultraviolet rays under the conditions of an illuminance of 350 mJ / cm ² and an integrated light charge of 1000 mJ / cm ² . As a result, a bonded sample containing an optical film and an unstretched film was obtained. Then, the bonded sample was cut to a width of 25 mm, and the surface on the optical film side was bonded to the surface of the slide glass with an adhesive to obtain a bonded product. At the time of bonding, a double-sided adhesive tape (manufactured by Nitto Denko Corporation, product number "CS9621") was used as the adhesive. After the bonding, the bonded product was allowed to stand for 12 hours.
Then, a 90-degree peeling test was carried out by sandwiching the end portion of the unstretched film with a jig at the tip of the force gauge and pulling it in the normal direction of the surface of the slide glass. The peeling speed during towing was 20 mm / min. Since the force measured when the unstretched film is peeled off is the force required to peel off the unstretched film from the optical film, the magnitude of this force was measured as the peeling strength. This peel strength corresponds to the adhesive strength between the unstretched film and the optical film.

[Manufacturing example 1. Production of hydride of ring-opening polymer of dicyclopentadiene]
The pressure resistant reactor made of metal was sufficiently dried and then replaced with nitrogen. In this metal pressure resistant reactor, 154.5 parts of cyclohexane, 42.8 parts of a 70% cyclohexane solution of dicyclopentadiene (endo content of 99% or more) (30 parts as the amount of dicyclopentadiene), and 1- 1.9 parts of hexene was added and heated to 53 ° C.

To a solution prepared by dissolving 0.014 parts of a tetrachlorotungstenphenylimide (tetrahydrofuran) complex in 0.70 parts of toluene, 0.061 parts of a diethylaluminum ethoxide / n-hexane solution having a concentration of 19% was added, and the mixture was stirred for 10 minutes. Prepared a catalytic solution.
This catalyst solution was added to the pressure resistant reactor to initiate the ring-opening polymerization reaction. Then, the reaction was carried out for 4 hours while maintaining 53 ° C. to obtain a solution of a ring-opening polymer of dicyclopentadiene.
The number average molecular weight (Mn) and weight average molecular weight (Mw) of the obtained ring-opening polymer of dicyclopentadiene are 8750 and 28,100, respectively, and the molecular weight distribution (Mw / Mn) obtained from these is 3 It was .21.

To 200 parts of the obtained solution of the ring-opening polymer of dicyclopentadiene, 0.037 parts of 1,2-ethanediol was added as a terminator, heated to 60 ° C., and stirred for 1 hour to stop the polymerization reaction. I let you. A part of a hydrotalcite-like compound (“Kyoward (registered trademark) 2000” manufactured by Kyowa Chemical Industry Co., Ltd.) was added thereto, and the mixture was heated to 60 ° C. and stirred for 1 hour. After that, 0.4 part of a filtration aid ("Radiolite (registered trademark) # 1500" manufactured by Showa Kagaku Kogyo Co., Ltd.) was added, and a PP pleated cartridge filter ("TCP-HX" manufactured by ADVANTEC Toyo Co., Ltd.) was used as an adsorbent. The solution was filtered off.

To 200 parts of the filtered dicyclopentadiene ring-opening polymer solution (30 parts of polymer amount), 100 parts of cyclohexane is added, 0.0043 parts of chlorohydride carbonyltris (triphenylphosphine) ruthenium is added, and hydrogen is added. The hydrogenation reaction was carried out at a pressure of 6 MPa and 180 ° C. for 4 hours. As a result, a reaction solution containing a hydride of a ring-opening polymer of dicyclopentadiene was obtained. In this reaction solution, hydride was precipitated to form a slurry solution.

The hydride contained in the reaction solution and the solution were separated using a centrifuge and dried under reduced pressure at 60 ° C. for 24 hours to obtain a hydride of a crystallized dicyclopentadiene ring-opening polymer 28. I got 5 copies. The hydrogenation rate of this hydride was 99% or more, the glass transition temperature Tg was 94 ° C., the melting point (Tm) was 262 ° C., the crystallization temperature Tpc was 170 ° C., and the ratio of racemo diad was 89%.

[Manufacturing example 2. Manufacture of base film]
An antioxidant (tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl)) was added to 100 parts of the hydride of the ring-opening polymer of dicyclopentadiene obtained in Production Example 1. Propionate] Methane; 0.5 parts of "Irganox (registered trademark) 1010" manufactured by BASF Japan Ltd.) was mixed to obtain a crystalline resin.

The crystalline resin was put into a twin-screw extruder (“TEM-37B” manufactured by Toshiba Machine Co., Ltd.) equipped with four die holes having an inner diameter of 3 mmΦ. The crystalline resin was formed into a strand-shaped molded product by hot melt extrusion using the above-mentioned twin-screw extruder. This molded product was shredded with a strand cutter to obtain pellets of crystalline resin.

Subsequently, the obtained pellets were supplied to a heat melt extrusion film forming machine equipped with a T-die. Using this film forming machine, a long film (width 120 mm) made of the above-mentioned crystalline resin was produced by winding it on a roll at a speed of 27 m / min. The operating conditions of the film forming machine are shown below.
-Barrel temperature setting: 280 ° C to 290 ° C
・ Die temperature: 270 ° C
・ Screw rotation speed: 30 rpm
・ Cast roll temperature: 70 ℃
As a result, a base film was obtained as a long crystalline resin film formed of the crystalline resin. The thickness of the obtained base film was 20 μm. The crystallinity of the hydride of the ring-opening polymer of dicyclopentadiene in this base film was 0.7%.

[Manufacturing example 3. Manufacture of coating liquid for easy-adhesive layer]
A water dispersion of carbonate-based polyurethane ("Adecabontiter SPX-0672" manufactured by ADEKA, glass transition temperature -16 ° C) was added to 100 parts of polyurethane in an amount of polyurethane, and a polyfunctional epoxy compound as a cross-linking agent (Nagase ChemteX). 2.7 parts of "Denacol EX-521" manufactured by Nisshin Kagaku Kogyo Co., Ltd., 0.18 parts of acetylene glycol as a surfactant ("Surfinol 440" manufactured by Nisshin Chemical Industry Co., Ltd.), and ion-exchanged water as a solvent are mixed. A coating liquid having a solid content concentration of 30% was obtained.

[Example 1]
(1.1. Step of forming an easy-adhesion layer on a temporary support)
As a temporary support, a resin film made of a norbornene-based resin (“Zeonoa Film ZF16-050” manufactured by Zeon Corporation, thickness 50 μm; hereinafter, may be referred to as “temporary support 1”) was prepared. The surface free energy of the surface of the temporary support 1 was measured. The coating liquid produced in Production Example 3 was applied to the surface of the temporary support 1. Then, the coated layer of the coating liquid was dried at 90 ° C. for 120 seconds to form an easily adhesive layer having a thickness of 100 nm on the surface of the temporary support 1.

(1.2. Corona treatment step on the film surface of the base film)
While the base film produced in Production Example 2 was conveyed in the longitudinal direction of the base film, the surface of the film was subjected to corona treatment. This corona treatment was performed under the conditions of an output of 100 W, an electrode width of 0.3 m, and a film transfer speed of 0.080 m / min. The processing intensity of the corona treatment under this condition is 4.2 kW · min / m ² . The surface free energy of the film surface of the corona-treated base film was measured.

(1.3. Laminating process)
The easy-adhesive layer formed on the surface of the temporary support 1 and the corona-treated surface of the base film were bonded together.

(1.4. Peeling process of temporary support)
The temporary support 1 was peeled off to obtain a multi-layer film including a base film and an easy-adhesive layer. The transferability of the easy-adhesion layer was evaluated by observing the surface of the peeled temporary support 1.

(1.5. Stretching process)
The multilayer film was subjected to a stretching treatment in which the multilayer film was stretched in the width direction under the conditions of a stretching temperature of 130 ° C., a stretching ratio of 1.2 times, and a stretching speed of 4 mm / min.

(1.6. Crystallization process)
After the stretching treatment, the multilayer film was subjected to a crystallization treatment in which the multi-layer film was heated at a temperature of 170 ° C. for 30 seconds. The above crystallization treatment was carried out in a state where the edges of the multilayer film were fixed and tensioned, and wrinkles due to heat shrinkage did not occur.
As a result, an optical film provided with a base film and an easy-adhesion layer was obtained. The crystallinity of the hydride of the ring-opening polymer of dicyclopentadiene in the base film contained in the obtained optical film was 73%. This optical film was evaluated by the method described above.

[Example 2]
The temporary support was changed to a resin film made of a norbornene-based resin (“Zeonoa film” manufactured by Zeon Corporation, thickness 50 μm; hereinafter, may be referred to as “temporary support 2”).
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1.

[Example 3]
The base film may be referred to as a resin film made of a norbornene-based resin (“Zeonoa film” manufactured by Nippon Zeon Co., Ltd., thickness 100 μm, glass transition temperature of norbornene-based polymer 125 ° C.; hereinafter, “non-crystalline COP”. Yes.).
Further, in the stretching treatment of the multilayer film, the stretching ratio was changed to 3.0 times.
Further, the multilayer film obtained after the stretching treatment without performing the crystallization treatment on the multilayer film was evaluated as an optical film.
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1.

[Example 4]
The temporary support was changed to a polyethylene terephthalate film (“Cosmo Shine (registered trademark) A4100” manufactured by Toyobo Co., Ltd., thickness 100 μm; hereinafter, may be referred to as “temporary support 3”).
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1.

[Comparative Example 1: Example in which the easy-adhesive layer was not formed]
The base film produced in Production Example 2 was subjected to corona treatment, stretching treatment and crystallization treatment under the same conditions as in Example 1. That is, a base film was obtained instead of the optical film in the same manner as in Example 1 except that the base film and the easy-adhesive layer were not bonded. The peel strength of the base film thus obtained was measured by the above-mentioned measuring method. In this measuring method, the corona-treated surface of the base film was attached to the surface of the slide glass, and the peel strength was measured.

[Comparative Example 2: Example in which the easy-adhesive layer was not formed]
The base film prepared in Example 3 was subjected to corona treatment and stretching treatment under the same conditions as in Example 3. That is, a base film was obtained instead of the optical film in the same manner as in Example 3 except that the base film and the easy-adhesive layer were not bonded. The peel strength of the base film thus obtained was measured by the above-mentioned measuring method. In this measuring method, the corona-treated surface of the base film was attached to the surface of the slide glass, and the peel strength was measured.

[Comparative Example 3: An example in which heat treatment was not performed after bonding with the easy-adhesion layer]
The base film produced in Production Example 2 was subjected to a stretching treatment and a crystallization treatment under the same conditions as in Example 1 to obtain a crystallized base film. This crystallized base film was used in place of the base film produced in Production Example 2.
Further, after the crystallization base film and the easy-adhesion layer were bonded and the temporary support was peeled off, the stretching treatment and the crystallization treatment were not performed.
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1.

[Comparative Example 4: Example in which the heat treatment temperature was low]
The stretching temperature in the stretching treatment was changed to 90 ° C.
Moreover, the crystallization treatment was not performed.
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1.

[Comparative Example 5: Example in which the surface free energy of the temporary support surface was large]
Before applying the coating liquid produced in Production Example 3, the processing strength is 4.2 kW on the surface of the temporary support 1 under the conditions of an output of 100 W, an electrode width of 0.3 m, and a film transfer speed of 0.080 m / min. -Min / m ² corona treatment was applied.
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1. However, since the transferability of the easy-adhesion layer was inferior, it was not possible to evaluate the adhesion between the easy-adhesion layer and the base film and measure the peel strength.

[Comparative Example 6: Example in which the surface free energy of the film surface of the base film was small]
No corona treatment was performed on the film surface of the base film.
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1. However, since the transferability of the easy-adhesion layer was inferior, it was not possible to evaluate the adhesion between the easy-adhesion layer and the base film and measure the peel strength.

[Comparative Example 7: Example in which the surface free energy of the film surface of the base film was small]
The treatment strength of the corona treatment on the film surface of the base film was changed to 3.2 kW · min / m ² .
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1. However, in Comparative Example 7, the transferability of the easy-adhesion layer was insufficient, so the peel strength was not evaluated.

[Comparative Example 8: Example in which the surface free energy of the temporary support surface was large]
The surface of a resin film (“Zeonoa Film ZF16-050” manufactured by Zeon Corporation, thickness 50 μm) formed of a norbornene-based resin was subjected to corona treatment with a treatment strength of 4.2 kW · min / m ² . The coating liquid produced in Production Example 3 was applied to the corona-treated surface. The coated layer of the coating liquid was dried at 90 ° C. for 120 seconds to form an easy-adhesive layer having a thickness of 100 nm. As a result, a temporary support having a multi-layer structure including a resin film and an easy-adhesive layer (hereinafter, may be referred to as “temporary support 5”) was obtained.

This temporary support 5 having a multi-layer structure was used in place of the temporary support 1 used in Example 1. At this time, the surface of the temporary support 5 having a multi-layer structure on the side of the easy-adhesive layer was used as a temporary support surface for further forming the easy-adhesive layer.
Moreover, the corona treatment on the film surface of the base film was not performed.
Except for the above items, the optical film was manufactured and evaluated in the same manner as in Example 1. However, since the transferability of the easy-adhesion layer was inferior, it was not possible to evaluate the adhesion between the easy-adhesion layer and the base film and measure the peel strength.

[result]
The results of the above-mentioned Examples and Comparative Examples are shown in Tables 3 and 4 below. In the table below, in the column of adhesion, the numerical value of the molecule represents the number of squares remaining without peeling off the easy-adhesion layer.

[examination]
As can be seen from Comparative Example 3, the easy-adhesive layer formed on the temporary support surface of the temporary support can be simply bonded to the base film formed of the resin containing the alicyclic structure-containing polymer. High adhesion cannot be obtained and it easily peels off. Further, as can be seen from Comparative Example 4, even if the heat treatment is performed after the easy-adhesion layer is bonded to the base film, high adhesion can be obtained if the temperature of the heat treatment is out of the predetermined temperature range. do not have. On the other hand, in the embodiment, the easy-adhesive layer is bonded to the base film and then heat-treated in a predetermined temperature range to effectively improve the adhesion between the easy-adhesive layer and the base film. I was able to.
Further, as can be seen from Comparative Examples 5 to 8, when the surface free energy of the temporary support surface of the temporary support and the surface free energy of the film surface of the base film are out of the predetermined range, they are formed on the temporary support surface. The easy-adhesion layer that has been formed cannot be smoothly transferred to the film surface of the base film. On the other hand, in the embodiment, the surface free energy of the temporary support surface of the temporary support and the surface free energy of the film surface of the base film are within a predetermined range, so that the easy-adhesive layer does not remain on the temporary support surface. , Smooth transfer was realized.
From the above results, in the production method of the present invention, the film surface of the base film formed of the resin containing the alicyclic structure-containing polymer and the resin layer formed on the temporary support are bonded together to form a base. It was confirmed that an optical film containing a resin layer that is difficult to peel off from the material film and the base film can be produced.

Further, as can be seen from Comparative Examples 1 and 2, the base film formed of the resin containing the alicyclic structure-containing polymer may be adhered to a member such as a slide glass using an adhesive or an adhesive. Its adhesive strength is small. On the other hand, it was confirmed that by forming an easy-adhesive layer as a resin layer on the base film to form an optical film, the optical film can be strongly adhered to the above-mentioned member as shown in Examples. Was done.

Claims (7)

A step of forming a resin layer on the temporary support surface of a temporary support having a temporary support surface having a surface free energy of 20 mJ / m ² or less.
A step of subjecting the film surface of a base film made of a resin containing an alicyclic structure-containing polymer to a hydrophilic treatment so that the surface free energy of the film surface is 40 mJ / m ² or more.
A step of bonding the resin layer formed on the temporary support surface of the temporary support and the surface of the film subjected to the hydrophilic treatment of the base film.
The step of peeling off the temporary support and
A method for producing an optical film, comprising a step of heat-treating the resin layer and the base film at a temperature equal to or higher than the glass transition temperature of the alicyclic structure-containing polymer. The method for producing an optical film according to claim 1, wherein the alicyclic structure-containing polymer has crystallinity. The method for producing an optical film according to claim 2, wherein the crystallinity of the alicyclic structure-containing polymer is less than 3% before the film surface is subjected to a hydrophilic treatment. The method for producing an optical film according to claim 2 or 3, wherein crystallization of the alicyclic structure-containing polymer proceeds in the step of applying the heat treatment to the resin layer and the base film. The step of applying the heat treatment to the resin layer and the base film is
The step of stretching the base film and
The method for producing an optical film according to any one of claims 2 to 4, further comprising a step of advancing the crystallization of the alicyclic structure-containing polymer contained in the base film after stretching. The method for producing an optical film according to any one of claims 1 to 5, wherein the hydrophilic treatment is at least one selected from the group consisting of corona treatment, plasma treatment and excimer treatment. The optical film according to any one of claims 1 to 6, wherein the resin layer is formed of at least one selected from the group consisting of urethane resin, olefin resin, polyester resin, epoxy resin and acrylic resin. Production method.