JPWO2019003980A1 - Method for manufacturing optical film - Google Patents

Abstract

A step of forming a resin layer on the temporary support surface of the temporary support having a temporary support surface having a surface free energy of 20 mJ / m 2 or less; a base film formed of a resin containing an alicyclic structure-containing polymer A step of subjecting the film surface to a hydrophilic treatment so that the surface free energy of the film surface becomes 40 mJ / m 2 or more; the resin layer formed on the temporary support surface of the temporary support, and the hydrophilicity of the base film. A step of laminating the treated film surface; a step of peeling the temporary support; and a glass transition temperature of the alicyclic structure-containing polymer or more in the resin layer and the base film. And a step of performing heat treatment at the temperature of.

Description

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

  In a display device such as a liquid crystal display device and 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).

JP, 2010-107958, A International Publication No. 2014/175312

  When a film made 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 of the film. For example, an easy-adhesion layer may be formed on the surface of a film formed of a resin containing an alicyclic structure-containing polymer by using a resin suitable for increasing the adhesiveness. Generally, a film formed of a resin containing an alicyclic structure-containing polymer has poor adhesiveness, and it was difficult to bond it to other members with high adhesive strength even if an adhesive was used. By using such an easy-adhesion layer, it becomes possible to bond the above-mentioned member with high adhesive strength.

  It was usual that a resin layer such as an easy-adhesion layer was formed by a coating method on a film formed of a resin containing an 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. It was However, in the field of industrial production, a method other than the coating method may be desired as a method for forming the resin layer on the film formed of the resin containing the alicyclic structure-containing polymer.

  For example, when a resin layer is formed on both sides of a film formed of a resin containing an alicyclic structure-containing polymer by a coating method, it is required to form a resin layer on each side due to the nature of the coating method. However, the number of steps is increased, which tends to increase the manufacturing cost. Therefore, from the viewpoint of suppressing the manufacturing cost by simultaneously forming the resin layers on both surfaces, development of a method other than the coating method is desired. Further, as in the above example, even in the case where the resin layer is formed on both surfaces of the film formed of the resin containing the alicyclic structure-containing polymer, the method other than the coating method is used as the method for forming the resin layer. May be desired.

  Therefore, the present inventor has studied 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 attached to a film formed of a resin containing an alicyclic structure-containing polymer, and then the temporary support is peeled off to obtain an alicyclic structure. A resin layer is formed on the surface of the film formed of the resin containing the contained polymer. However, a film formed of a resin containing an alicyclic structure-containing polymer generally has poor adhesion to the resin layer, and thus the resin layer formed by the transfer method tends to be easily peeled 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 lower adhesiveness after stretching.

  Further, the present inventors have studied, when a crystalline alicyclic structure-containing polymer is used, a film formed of a resin containing the alicyclic structure-containing polymer, adhesion to the resin layer Was found to be particularly low. Furthermore, the adhesiveness of the film formed of the resin containing a crystalline alicyclic structure-containing polymer to the resin layer is further reduced as the crystallization of the alicyclic structure-containing polymer proceeds, and the resin layer It has been found that the peeling is particularly likely to occur.

  The present invention was devised in view of the above problems, and a film surface of a base material film formed 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 is capable of producing an optical film including a substrate film and a resin layer that is difficult to be peeled off from the substrate film, by laminating.

As a result of intensive studies to solve the above problems, the present inventor has found that 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 film surface of a base film. A step of subjecting the film surface to a hydrophilic treatment so that the surface free energy of the film surface falls within a predetermined range, a resin layer formed on the temporary supporting surface of the temporary support and a film surface subjected to the hydrophilic treatment of the base film. The step of laminating, the step of peeling the temporary support, and the step of subjecting the resin layer and the base material film to a heat treatment at a temperature not lower than the glass transition temperature of the alicyclic structure-containing polymer, The inventors have found that the problems are 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 the temporary support having a temporary support surface having a surface free energy of 20 mJ / m ² or less,
A step of subjecting a film surface of a substrate film formed of a resin containing an alicyclic structure-containing polymer to a hydrophilic treatment so that the surface free energy of the film surface becomes 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 hydrophilic film-treated film surface of the base film,
A step of peeling the temporary support, and
A method for producing an optical film, comprising a step of subjecting the resin layer and the base film to a heat treatment 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 alicyclic structure-containing polymer has a crystallinity of 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 subjecting the resin layer and the base film to the heat treatment,
A step of stretching the substrate film,
The process of advancing crystallization of the said alicyclic structure containing polymer contained in the said base film after extending | stretching, The manufacturing method of the optical film as described in any one of [2]-[4].
[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], 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. A method for producing the optical film described above.

  According to the present invention, the film surface of the base material 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 material film and the base material. It is possible to provide a manufacturing method capable of manufacturing an optical film including a resin layer that is difficult to peel 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 exemplifications shown below, and may be implemented by being arbitrarily modified within the scope of the claims of the present invention and the scope of equivalents thereof.

  In the following description, the “long” film means a film having a length of 5 times or more the width, preferably having a length of 10 times or more, specifically a roll shape. A film having such a length that it can be wound up and 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 100,000 times or less, for example.

[1. Overview of optical film manufacturing method]
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 is
A step (I) of forming a resin layer on the temporary support surface of the temporary support having a temporary support surface having a predetermined surface free energy;
On the film surface of the base film, a step of performing a hydrophilic treatment so that the surface free energy of the film surface falls within a predetermined range (II),
A step (III) of laminating the resin layer formed on the temporary support surface of the temporary support and the hydrophilic film surface of the substrate film (III),
Step (IV) of peeling the temporary support, and
A step (V) of subjecting the resin layer and the base film to a heat treatment at a temperature not lower than the glass transition temperature of the alicyclic structure-containing polymer;
including.

  According to the above manufacturing method, it is possible to manufacture an optical film including a base film and a resin layer that is difficult to peel from the base film. Further, in the above-mentioned manufacturing method, since it is possible to prevent a part or all of the resin layer from remaining on the temporary support surface of the temporary support, it is possible to smoothly form the resin layer 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 substrate film are usually directly bonded. Therefore, in the optical film, the base film and the resin layer are usually in direct contact with each other. Here, the fact that the resin layer and the film surface of the base material film are directly bonded to each other means that the resin layer and the film surface of the base material film are not bonded to each other in a mode in which there is no other layer. Say. In addition, "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 the step (V-1) of stretching the base material film. Furthermore, when the alicyclic structure-containing polymer contained in the base film has crystallinity, the step (V) includes a step (V-2) of promoting crystallization of the alicyclic structure-containing polymer. You may stay.

[2. Step (I) of forming a resin layer on the temporary support surface of the temporary support]
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), usually, a temporary support having a temporary support surface having a predetermined surface free energy is prepared, and a resin layer is formed on the temporary support surface.

Surface free energy of the temporary support surface, usually 20 mJ / ^{m 2} or less, preferably less than 20 mJ / ^{m 2,} more preferably less than 19mJ / ^{m 2.} The temporary supporting 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 resin layer from remaining on the temporary support surface. The lower limit of the surface free energy of the temporary supporting 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 angle of water and hexadecane on the surface and fitting the measured contact angle to the Owens Wendt model. The surface free energy can be specifically measured by the measuring method described in the examples.

  A resin film is usually used as the temporary support. Among them, a long resin film is preferable from the viewpoint of efficiently producing an optical film by the roll-to-roll method. As this 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 resins containing polymers such as alicyclic structure-containing polymers, polyethylene terephthalate, polyethylene, polybutylene terephthalate, polypropylene and polytetrafluoroethylene. Further, as this resin film, for example, a film whose surface is subjected to a release treatment with an appropriate release agent may be used.

  The resin layer formed on the temporary support surface of the temporary support is formed of a resin of a type suitable for the properties 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 be made to 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, trimethylolpropane, and the like. Examples of the polybasic acid include polyvalent carboxylic acids such as dicarboxylic acids and tricarboxylic acids, and anhydrides thereof. Examples of the dicarboxylic acid include adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid. Examples of the tricarboxylic acid include trimellitic acid and the like. Examples of the above-mentioned polyether polyols include poly (oxypropylene ether) polyols and poly (oxyethylene-propylene ether) polyols. In the polyurethane, for example, after the reaction between the polyol and the polyisocyanate, the unreacted residual hydroxyl group can be used as a polar group capable of undergoing a crosslinking reaction with the functional group in the crosslinking agent. As the polyurethane, a polycarbonate polyurethane derived from a polycarbonate polyol and a polyisocyanate and having a carbonate structure in its skeleton is preferable. Regarding the urethane resin, for example, the description in JP-A-2016-182568 can be referred to.

  As the polyurethane, those contained in water-based emulsions that are commercially available as water-based urethane resins 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 the water-based urethane resin are "ADEKA Bontiter" series manufactured by ADEKA, "Orestar" series manufactured by Mitsui Chemicals, "Bondick" series manufactured by DIC, "Hydran (WLS201, WLS202, etc.)" series. , Bayer's "Implanyl" series, Kao's "Poise" series, Sanyo Kasei's "Sampren" series, Daiichi Kogyo Seiyaku's "Superflex" series, Kusumoto Kasei's " It is possible to use the NEOREZ series, the Sancure series manufactured by Lubrizol.

  As the olefin resin, a resin containing an acid-modified polyolefin having a content of the unsaturated carboxylic acid component of 0.1% by weight to 10% by weight or a crosslinked product thereof can be used. Preferable examples of the olefin component which is the main component of the acid-modified polyolefin include ethylene, propylene, isobutylene, 2-butene, 1-butene, 1-pentene, 1-hexene, and other alkenes having 2 to 6 carbon atoms, and these. A mixture may be mentioned. Among them, from the viewpoint of enhancing the adhesiveness 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 further preferable, and ethylene is particularly preferable. On the other hand, examples of the unsaturated carboxylic acid component that is a modifying component of the acid-modified polyolefin include acrylic acid, methacrylic acid, maleic acid (anhydrous), itaconic acid (anhydrous), fumaric acid, crotonic acid, and a half of unsaturated dicarboxylic acid. Examples thereof include esters and half amides. Of these, acrylic acid, methacrylic acid, and (anhydrous) maleic acid are preferable, and acrylic acid and (anhydrous) maleic acid are particularly preferable, because they can enhance the adhesiveness 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). Regarding the olefin resin, for example, the description in JP-A-2014-240174 can be referred to.

  A commercially available product may be used as the acid-modified polyolefin. 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.) and the like. To be

  As the polyester resin, a resin containing a polyester obtained by the reaction of the polyol compound and the polybasic acid or a crosslinked product thereof can be used. In this polyester, for example, after the completion of the reaction between the polyol compound and the polybasic acid, the unreacted residual hydroxyl group and carboxyl group can be used as polar groups capable of undergoing a crosslinking reaction with a crosslinking agent. Further, the polyester may be one obtained by copolymerizing a copolymer component having a polar group such as a hydroxyl group and a carboxyl group in combination with the above-mentioned polyol compound and polybasic acid. 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. Regarding the polyester resin, for example, the description in JP-A-2015-024511 can be referred to.

  A commercially available product may be used as the polyester. Examples of commercially available water-soluble or water-dispersible polyesters include, for example, "Nichigo Polyester (Nichigo Polyester W-0030, Nichigo Polyester W-0005S30WO, Nichigo Polyester WR-961)" series (manufactured by Nippon Synthetic Chemical Co., Ltd.). ), "Peth Resin A (Peth Resin A-210, Peth Resin A-520, Peth Resin A-684G, Peth Resin A-695GE, etc.)" series (manufactured by Takamatsu Yushi Co., Ltd.) and the like.

  As the epoxy resin, any epoxy resin such as a one-component curing type epoxy resin and a two-component curing type epoxy resin can be used. Among them, those containing a water-soluble epoxy polymer are preferable. Polyamide epoxy polymer is mentioned as a preferable example of a water-soluble epoxy polymer. This polyamide-epoxy polymer can be obtained, for example, by reacting a polyamide polyamine obtained by reacting a polyalkylene polyamine such as diethylene triamine or triethylene tetramine with a dicarboxylic acid such as adipic acid with epichlorohydrin. Examples of commercially available products of such a polyamide epoxy polymer include "SUMIREZ RESIN 650 (30)" and "SUMIREZ RESIN 675" manufactured by Sumika Chemtech. Regarding the epoxy resin, for example, the description in JP 2008-26352 A 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 coatability. This polyvinyl alcohol includes not only partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, but also modified polyvinyl alcohol such as carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. Contains alcohol. As a commercial item of polyvinyl alcohol, anionic group-containing polyvinyl alcohol “KL-318” manufactured by Kuraray Co., Ltd. may be mentioned.

  As the acrylic resin, a resin containing an acrylic polymer or a crosslinked product thereof can be used. Examples of the acrylic polymer include homopolymers of acrylic monomers, copolymers of two or more types of acrylic monomers, and copolymers of one or more types of acrylic monomers with other monomers. Examples of the acrylic monomer include acrylic acid, acrylic acid ester such as alkyl acrylate, acrylamide, acrylonitrile, methacrylic acid ester such as methacrylic acid and alkyl methacrylate, methacrylamide, methacrylonitrile and the like. 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. In addition, the acrylic polymer was combined with the above acrylic monomer to copolymerize a copolymerization component having a polar group such as a hydroxyl group and a carboxyl group so that the acrylic polymer could react with the functional group of the crosslinking agent (crosslinking reaction). Those are preferable. Regarding 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 above polymer becomes a cross-linked product by the reaction with the 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 and isocyanate compounds. Moreover, as the crosslinking agent, one kind may be used alone, or two or more kinds may be used in combination at an arbitrary ratio. Of these, epoxy compounds are preferable as the crosslinking 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, those which are soluble in water or which can be dispersed in water to form an emulsion are preferable from the viewpoint of ease of use. As an example of the epoxy compound, 1 mol of glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexane glycol and neopentyl glycol And a diepoxy compound obtained by etherification with 2 mol of epichlorohydrin; a polyepoxy compound obtained by etherification with 1 mol of polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, and sorbitol, and 2 mol or more of epichlorohydrin Epoxy compound; diepoxy obtained by esterification of 1 mol of dicarboxylic acid such as phthalic acid, terephthalic acid, oxalic acid and adipic acid with 2 mol of epichlorohydrin Compounds; and the like.

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

  Further, the resin forming the resin layer may further contain an optional component in combination with the above-mentioned polymer or a crosslinked product thereof. Examples of the optional component include a curing accelerator, a curing aid, particles, a heat resistance stabilizer, a weather resistance stabilizer, a leveling agent, a surfactant, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, and an antifogging agent. Examples include agents, lubricants, dyes, pigments, natural oils, synthetic oils and waxes. As the arbitrary component, one type may be used alone, or two or more types may be used in combination at any ratio.

  The resin forming the resin layer may be one type or two or more types. Therefore, for example, the urethane resin, the olefin resin, the polyester resin, the epoxy resin, and the acrylic resin described above may be used in combination of two or more kinds. For example, a resin containing a combination of polyurethane and an acid-modified polyolefin, 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 application 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, particularly preferably 1 μm or less. is there. By setting the thickness of the easy-adhesion layer to the above lower limit or more, the optical film can be attached to other members with sufficient adhesive strength. Further, by setting the thickness of the easy-adhesion layer to be equal to or less than the upper limit value, the occurrence of deformation of the easy-adhesion layer, which is a relatively soft layer, is suppressed, and the optical film can be easily wound as a roll. When the thickness of the easy-adhesion layer is within the above range, sufficient adhesion between the base film and the easy-adhesion layer can be obtained, and the thickness of the optical film can be reduced.

  The resin layer can be formed on the temporary support surface of the temporary support by, for example, a coating method. In this coating method, usually, a coating liquid containing a component such as a polymer contained in a resin forming a resin layer or a precursor thereof is coated on a temporary support surface, and the coated coating liquid is cured. . In this coating method, the coating liquid can usually form the resin layer as it is. Alternatively, in this coating method, the coating liquid can usually form a resin layer after the reaction of the components therein, the volatilization of the solvent, and the like, if necessary. As a result, 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. % By weight.

  When the coating liquid contains a crosslinking agent, the amount of the crosslinking agent is usually 0.1 parts by weight or more, preferably 1 part by weight, based on 100 parts by weight of the total amount of the polymer and the precursor in the coating liquid. As described above, more preferably 2 parts by weight or more, usually 20 parts by weight or less, preferably 15 parts by weight or less, more preferably 10 parts by weight or less. Since the crosslinking reaction proceeds sufficiently by setting the amount of the crosslinking agent to the lower limit value or more, the mechanical strength of the resin layer can be appropriately improved, and the amount of the crosslinking agent is set to the upper limit value or less. As a result, the amount of unreacted crosslinking agent remaining 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, dimethyl sulfoxide, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, methyl ethyl ketone, and triethyl amine; and the like. Further, the solvent may be used alone or in combination of two or more kinds at an arbitrary ratio. Of these, water is preferable as the solvent. As a preferred example, the coating liquid may be an aqueous emulsion having an organic solvent concentration of less than 1% by weight. It is preferable that the amount of the solvent is appropriately set so that the viscosity of the coating liquid is in a range suitable for coating.

  Examples of the coating method of the coating liquid include a wire bar coating method, a dipping method, a spraying method, a spin coating method, a roll coating method, a gravure coating method, an air knife coating method, a curtain coating method, a slide coating method and an extrusion method. Examples include the coating method.

  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, the cross-linking agent may be used to perform cross-linking. The method of drying and crosslinking is arbitrary. For example, the drying may be any method such as reduced pressure drying and heat drying. Above all, it is preferable to cure the coating liquid by heating and drying from the viewpoint of rapidly advancing a reaction such as a crosslinking reaction as it is dried. 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. Process 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 hydrophilic treatment. In this step (II), usually, a base film formed of a resin containing an alicyclic structure-containing polymer is prepared, and the film surface of the base film is subjected to 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 further has low hygroscopicity. Examples of such an alicyclic structure-containing polymer include a polymer that can be obtained by a polymerization reaction using a cyclic olefin as a monomer, or a hydrogenated product thereof. As the alicyclic structure-containing polymer, both a polymer having an alicyclic structure in its main chain and a polymer having an alicyclic structure in its side chain can be used. Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and 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, more preferably 20 or less, Particularly preferably, it 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 structural units having an alicyclic structure in the alicyclic structure-containing polymer is preferably 30% by weight or more, more preferably 50% by weight or more, further preferably 70% by weight or more, particularly preferably 90% by weight. That is all. By increasing the proportion of the structural unit 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 according to the purpose of use.

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

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

  Specifically, the crystalline alicyclic structure-containing polymer is a ring-opening polymer of dicyclopentadiene and has crystallinity, and a hydrogenated product of the ring-opening polymer of dicyclopentadiene. It is more preferable that the polymer has crystallinity, and a hydrogenated product of a ring-opening polymer of dicyclopentadiene that has crystallinity is particularly preferable. Here, the ring-opening polymer of dicyclopentadiene means that the ratio of structural units derived from dicyclopentadiene to all 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 means 100% by weight of the polymer.

The hydride of the ring-opening polymer of dicyclopentadiene preferably has a high proportion of racemo dyads. Specifically, the ratio of racemo dyad of the repeating unit in the hydride of the ring-opening polymer of dicyclopentadiene is preferably 51% or more, more preferably 60% or more, particularly preferably 65% or more. A high proportion of Racemo Dyad indicates high syndiotactic stereoregularity. Therefore, the higher the racemo dyad ratio, the higher the melting point of the hydride of the ring-opening polymer of dicyclopentadiene tends to be.
The ratio of racemo dyads can be determined based on ¹³ C-NMR spectrum analysis described in Examples 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 high crystallinity. However, the surface of the base film containing the alicyclic structure-containing polymer having high crystallinity has poor adhesion to other resins. Therefore, the crystallization is preferably performed after the resin layer is attached to the base material film, and therefore, before the step (V), the alicyclic ring included in the resin forming the base material film is preferably used. The crystallinity of the formula structure-containing polymer is preferably low. Therefore, the crystallinity of the alicyclic structure-containing polymer contained in the base film is preferably low before the film surface is subjected to the hydrophilic treatment in step (II). Specifically, the crystallinity of the crystalline alicyclic structure-containing polymer contained in the base film before the hydrophilic treatment on the film surface is preferably less than 3%, more preferably 2%. %, Particularly preferably less than 1%.

  The crystallinity is an index showing the ratio of the crystallized alicyclic structure-containing polymer having crystallinity 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 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 a crystalline alicyclic structure-containing polymer having such a melting point Mp, it is possible to obtain an optical film having a better balance between moldability and heat resistance.

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

  On the other hand, the alicyclic structure-containing polymer having no crystallinity is, for example, (1) norbornene-based polymer, (2) monocyclic cycloolefin polymer, (3) cyclic conjugated diene polymer, (4) Examples thereof include vinyl alicyclic hydrocarbon polymers and their hydrides. 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 ring-opening polymers of norbornene monomers, ring-opening copolymers of norbornene monomers with other monomers capable of ring-opening copolymerization, and hydrides thereof; addition polymers of norbornene monomers, Examples thereof include addition copolymers of the norbornene monomer and other copolymerizable monomers. Among these, hydrides of ring-opening polymers of norbornene monomers are particularly preferable from the viewpoint of transparency.
As the alicyclic structure-containing polymer, 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 an arbitrary 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, more preferably 170 ° C. or lower. . The alicyclic structure-containing polymer having a glass transition temperature in such a range is resistant to deformation and stress during use at high temperatures and has excellent 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, further preferably 10,000 or more, particularly preferably 25,000 or more, preferably Is 1,000,000 or less, more preferably 500,000 or less, further 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 moldability 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, more preferably It is 4.0 or less, more preferably 3.5 or less. Here, Mn represents a number average molecular weight. The alicyclic structure-containing polymer having such a molecular weight distribution is excellent in moldability.

  The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) can be measured as a polystyrene conversion value 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, further preferably 80% by weight or more, particularly preferably 90% by weight or more. is there. By setting the ratio of the alicyclic structure-containing polymer to be the lower limit value or more in the above range, excellent properties of the alicyclic structure-containing polymer can be effectively exhibited.

  The resin forming the base material may further contain an optional component in combination with the alicyclic structure-containing polymer. Examples of optional components include antioxidants such as phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, light stabilizers such as hindered amine light stabilizers, petroleum wax, Fischer-Tropsch wax, and the like. Waxes such as polyalkylene waxes; sorbitol compounds, metal salts of organic phosphoric acids, metal salts of organic carboxylic acids, nucleating agents such as kaolin and talc; diaminostilbene derivatives, coumarin derivatives, azole derivatives (for example, benzoxazole derivatives, Fluorescent brighteners such as benzotriazole derivatives, benzimidazole derivatives, and benzothiazole derivatives), carbazole derivatives, pyridine derivatives, naphthalic acid derivatives, and imidazolone derivatives; benzophenone-based UV absorbers, salicylic acid-based UV absorbers, benzotriazole-based UV absorbers such as external line absorbers; inorganic fillers such as talc, silica, calcium carbonate, glass fibers; coloring agents; flame retardants; flame retardant aids; antistatic agents; plasticizers; near infrared absorbers; lubricants; fillers And any polymer other than the alicyclic structure-containing polymer, such as a soft polymer. In addition, as the optional component, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

  The base film preferably has a high total light transmittance. Specifically, the total light transmittance of the substrate 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 a 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 substrate 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, particularly preferably 50 μm or less. By setting the thickness of the base film to be the above lower limit or more, the mechanical strength of the optical film can be increased. The thickness of the optical film can be reduced by adjusting the thickness of the base film to the upper limit or less.

  The base film can be produced by molding a resin containing an alicyclic structure-containing polymer into a film by any 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 calender molding method, a cast 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 substrate film is produced by the melt extrusion molding method, the extrusion molding conditions are preferably as follows. The cylinder temperature (melting resin temperature) is preferably (Tg + 80 ° C.) or higher, more preferably (Tg + 100 ° C.) or higher, preferably (Tg + 180 ° C.) or lower, more preferably (Tg + 150 ° C.) or lower. In addition, 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, 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 substrate film under such conditions, the substrate 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 the base film is prepared, the film surface of the base film is subjected to hydrophilic treatment. When the resin layer is formed on one film surface of the base film, the one film surface is subjected to hydrophilic treatment. Further, when the resin layers are formed on both film surfaces of the substrate film, both film surfaces are subjected to hydrophilic treatment. By performing such a hydrophilic treatment, the surface free energy of the film surface of the base film is adjusted within a predetermined range.

Specific surface free energy of the film surface of the substrate film after the hydrophilic treatment is usually 40 mJ / ^{m 2} or more, preferably 50 mJ / ^{m 2} or more, particularly preferably 60 mJ / ^{m 2} or more. Since the film surface of the base material 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 step (IV), It is possible to suppress the resin layer from remaining on the temporary support surface of. 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.

  The hydrophilic treatment is preferably at least one selected from the group consisting of corona treatment, plasma treatment and excimer treatment. In addition, these treatments may be performed alone or in combination of two or more. By subjecting the film surface of the substrate film to these treatments, a hydrophilic group such as a hydroxyl group, a carboxyl group or a carbonyl group is usually produced on the film surface. Thereby, the surface free energy of the film surface can be improved.

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

In corona treatment, a high voltage is applied at high frequency 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. . In general, the surface free energy of the corona-treated film surface is adjusted according to the type of electrodes, electrode spacing, voltage, humidity, and the type of substrate film to be treated. The distance between the electrode and the substrate 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 substrate film, the treatment intensity calculated by “treatment intensity = (output) / (transport speed × electrode width)” is preferably 4.2 kW · min / m ² or more.

In the plasma treatment, usually, the film surface of the substrate film is 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 reduced pressure of, for example, about 0.1 Torr to 1 Torr, but it is preferably performed under atmospheric pressure from the viewpoint of performing the treatment efficiently while conveying the substrate 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; fluorine compounds such as CF ₄ , CHF ₃ , C ₂ F _{6 and the} like. . As a preferable gas, for example, a mixed gas in which an inert gas such as nitrogen and oxygen are mixed in a ratio of 95.0: 5.0 to 99.9: 0.1 can be mentioned. The distance between the electrode and the substrate film is preferably 1 mm to 5 mm, more preferably 1 mm to 3 mm. The conveyance speed of the substrate film that is 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 substrate film, the treatment intensity calculated by “treatment intensity = (output) / (transport speed × electrode width)” is preferably 0.028 kW · min / m ² or more.

In the excimer treatment, an excimer lamp is usually used to treat the film surface of the base material film by irradiating it with light having a central wavelength of less than 180 nm. The lower limit of the central wavelength of the irradiation light is not particularly limited and may be, for example, 100 nm or more. Here, the "center wavelength of light" refers to a wavelength that gives the maximum emission intensity in the emission spectrum. In the excimer processing, by selecting the type of the excimer lamp, the light having the target center wavelength can be obtained. For example, the center wavelength of the light emitted from the Ar excimer lamp is 126 nm, the center wavelength of the light emitted from the Kr excimer lamp is 146 nm, the center 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 irradiation time of light is 0.1 second 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 substrate film and resin layer (III)]
After step (I) and step (II), a step (III) of laminating the resin layer formed on the temporary support surface of the temporary support and the hydrophilic film surface of the substrate film I do. In this step (III), usually, the resin layer and the film surface of the substrate film are directly bonded to each other without interposing another layer such as an adhesive layer.

  From the viewpoint of preventing bubbles from remaining between the resin layer and the base film, the above-mentioned bonding is preferably performed so that the resin layer and the base film are pressed against each other. For example, by passing the temporary support having the resin layer formed on the temporary support surface and the base film between the pair of nip rolls, the resin layer and the base film are brought into pressure contact with each other, and the bonding is performed. 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 (IV) of peeling the temporary support]
After the step (III), the step (IV) of peeling the temporary support is performed. When the surface free energy of the film surface of the base film is within the above range, the resin layer can be stably fixed on the film surface of the base film. Further, since the surface free energy of the temporary support surface of the temporary support is within the above range, the resin layer can be smoothly separated from the temporary support surface of the temporary support. Therefore, the temporary support is peeled off smoothly. 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 multilayer film including a base film and a resin layer can be obtained.

[6. Step (V) of heat-treating the base material film and the resin layer]
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 including the base film and the resin layer that is difficult to be peeled 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 adhesiveness between the resin layer and the base film is effective. From the viewpoint of increasing the temperature to a higher level, the heat treatment temperature in the step (V) is preferably set higher 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, more preferably (Tg + 110 ° C.) It is particularly preferably (Tg + 100 ° C.) or less. When the heat treatment temperature is at least the lower limit value of the above range, the adhesiveness between the resin layer and the base film can be effectively enhanced. When the heat treatment temperature is at most the upper limit value of the above range, cloudiness 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 performing the heat treatment can be arbitrarily set within a range in which the adhesion between the resin layer and the base film can be enhanced. The specific treatment 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 value of the above range, the adhesiveness 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.

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

  There is no particular limitation on the stretching method of the base film, and any stretching method can be used. Examples of the stretching method include a uniaxial stretching method such as a method of uniaxially stretching the base film in the longitudinal direction (longitudinal uniaxial stretching method) and a method of uniaxially stretching the base film in the width direction (transverse uniaxial stretching method); Biaxial stretching such as simultaneous biaxial stretching in which the material film is stretched in the longitudinal direction and simultaneously in the width direction, and sequential biaxial stretching in which the base film is stretched in one of the longitudinal direction and the width direction and then stretched in the other. Method; and a method (oblique stretching method) of stretching the substrate film in an oblique direction which is neither parallel nor perpendicular to the width direction, such as more than 0 ° and less than 90 ° with respect to the width direction. 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 performing stretching in such a temperature range, the polymer molecules contained in the base film can be properly oriented. Here, "Tg" represents the glass transition temperature of the alicyclic structure-containing polymer contained in the base film.

  The stretching ratio in the step (V-1) can be appropriately selected according to the attributes such as optical properties, thickness and strength obtained after stretching and is usually 1.1 times or more, usually 10 times or less, preferably 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 stretching ratio to the upper limit value of the above range or less, the possibility that the film is broken can be reduced, so that the optical film can be easily manufactured.

  By subjecting the substrate film to the stretching treatment as described above in the step (V-1), an optical film having desired characteristics can be obtained.

  The step (V) is a step of advancing crystallization of the alicyclic structure-containing polymer contained in the base film, if necessary, when the base film contains a crystalline alicyclic structure-containing polymer. (V-2) may be included. In this step (V-2), the base film is heated to a predetermined temperature by heating the multilayer film including the base film and the resin layer, and crystallization of the alicyclic structure-containing polymer proceeds. . Usually, the crystallization of the alicyclic structure-containing polymer is carried out under the temperature condition of the glass transition temperature of the alicyclic structure-containing polymer contained in the base film or higher. 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 the step (V-1) of stretching the substrate film, the step (V-2) of advancing the crystallization of the alicyclic structure-containing polymer is usually the step (V- It is performed after 1).

  Crystallization is preferably performed in a state in which at least two edges of the multilayer film including the base film are held and strained. The tensioned state of the multilayer film means a state in which the multilayer film is under tension. However, the tensioned state of the multilayer film does not include the state in which the multilayer film is substantially stretched. Further, “substantially stretched” means that the stretching ratio in either direction of the multilayer film is usually 1.1 times or more. In a state where at least two edges of the multilayer film are held and tensioned, deformation of the multilayer film due to heat shrinkage is prevented in a region between the held edges. Therefore, crystallization can be promoted without impairing the smoothness of the film.

  In order to prevent deformation in a large area of the multilayer film, hold the edges including two opposite edges of the multilayer film and tension the area between the held edges. Is preferred. For example, in the case of a rectangular sheet-fed multilayer film, two opposing edges (for example, edges on the long side or edges on the short side) are held and the space between the two edges is held. By making the region of 10 in a tense state, it is possible to prevent deformation on the entire surface of the single-layered multilayer film. Further, in a long multi-layer film, the two end sides (that is, the end sides on the long side) at the end portions in the width direction are held and the region between the two end sides is in a tense state. Thus, the deformation can be prevented on the entire surface of the long multilayer film. In the multilayer film thus prevented from being deformed, the occurrence of deformation such as wrinkles is suppressed even if stress is generated in the film due to heat shrinkage. When a stretched film is used as the multilayer film, the deformation is more suppressed by holding at least two edges that are orthogonal to the stretching direction (the direction in which the stretching ratio is large in the case of biaxial stretching). It will be certain. As such a holder, for example, those 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 to promote crystallization of the alicyclic structure-containing polymer contained in the base film. At this time, the specific treatment temperature is usually Tg or higher, preferably (Tg + 20 ° C.) or higher, more preferably (Tg + 30 ° C.) or higher, and usually Tm or lower, preferably (Tm−20 ° C.) or lower, more preferably (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. It represents the glass transition temperature of the polymer. When the treatment temperature is at least the lower limit value of the above range, crystallization of the alicyclic structure-containing polymer can be efficiently progressed. In addition, when the treatment temperature is equal to or lower than the upper limit value of the above range, cloudiness of the base film can be suppressed.

  In the step (V-2), the treatment time for maintaining the temperature of the substrate 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 minutes. It is less than a minute. When the treatment time is at least the lower limit value of the above range, crystallization of the alicyclic structure-containing polymer having crystallinity can be sufficiently promoted, so that flexibility, heat resistance, and folding endurance of the optical film are obtained. It is possible to improve the characteristics such as. In addition, when the treatment time is equal to or less than the upper limit value of the above range, cloudiness of the base film can be suppressed.

  By subjecting the base film to the crystallization treatment as described above in the step (V-2), the crystallinity of the crystalline alicyclic structure-containing polymer contained in the base film can be increased. It is possible to obtain an optical film having excellent characteristics such as flexibility, heat resistance, folding resistance and solvent resistance.

[7. Arbitrary process]
The method for producing an optical film may further include an optional step in combination with the above steps.
Examples of the optional step include a relaxation step of removing the residual stress by heat-shrinking the base film after the step (V-2).

  Moreover, as an arbitrary process, the process of providing the optical film with arbitrary layers other than a base material film and a resin layer is mentioned, for example. The optional layer is usually provided on the surface of the base film opposite to the resin layer. Examples of the optional layer include a conductive layer, an antireflection layer, a hard coat layer, an antistatic layer, an antiglare layer, an antifouling layer, and a separator film layer.

[8. Optical film]
According to the manufacturing method described above, 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 peel from the base film. In this optical film, the base material film is subjected to a stretching treatment, the base material film contains a crystalline alicyclic structure-containing polymer, and further, the alicyclic structure-containing polymer crystal The adhesion between the base material film and the resin layer can be increased even if the progress of the polymerization is progressing.

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

  Since the optical film includes the substrate film formed of the resin containing the alicyclic structure-containing polymer, the optical film can exhibit the excellent properties exhibited by the alicyclic structure-containing polymer. Therefore, the optical film is usually excellent in mechanical strength, transparency, dimensional stability and light weight, and further has low hygroscopicity. Further, in the case of using a polymer having an alicyclic structure having crystallinity, the optical film has flexibility, heat resistance, folding resistance, low water absorption, etc. in addition to the above-mentioned excellent properties. 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 included in the optical film is It is preferable to have high crystallinity. The specific crystallinity range is preferably 10% or more, more preferably 15% or more, further preferably 30% or more, particularly preferably 50% or more, particularly preferably 60% or more. Such high crystallinity can be achieved by promoting crystallization of the alicyclic structure-containing polymer in step (V). The upper limit of the crystallinity is ideally 100%, but usually 90% or less, or 80% or less.

  In addition, since the optical film includes the resin layer, it can exhibit excellent characteristics based on the resin layer. For example, an optical film including an easy-adhesion layer as a resin layer can exhibit excellent adhesiveness on the surface of the easy-adhesion layer side. Therefore, it is possible to bond the optical film to the other member with a high bonding strength via the adhesive or the pressure-sensitive adhesive on the surface of the easily adhesive layer side.

  The optical film preferably has a high total light transmittance. Specifically, the total light transmittance of the optical film is preferably within the same range as described above as the range of the total light transmittance of the substrate film.

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

  The optical film can be arbitrarily applied to optical applications and can be used as a constituent element of a display device, for example. Among them, the optical film is preferably used as a component of a touch sensor of a liquid crystal display device by utilizing its excellent heat resistance and mechanical strength (in particular, flexibility). In particular, an optical film provided with a substrate film containing a crystalline alicyclic structure-containing polymer is excellent in folding endurance, and thus is applicable to a flexible display device, which is preferable.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples described below, and may be implemented by being arbitrarily modified within the scope of the claims of the present invention and the scope of equivalents thereof.
In the following description, "%" and "parts" representing amounts are by weight unless otherwise specified. In addition, the operations described below were performed under the conditions of normal temperature and normal pressure unless otherwise specified.

[Evaluation methods]
(Method of measuring thickness)
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 Woollam Co., Ltd.). Then, using the measured refractive index, the thickness of the film was measured with an optical interference type film thickness meter (“MCPD-9800” manufactured by Otsuka Electronics Co., Ltd.).

(Measurement 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 a column, and tetrahydrofuran was used as a solvent. The temperature at the time of measurement was 40 ° C.

(Method for measuring 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 the temperature is increased at 10 ° C./min using a differential operation calorimeter (DSC) to increase the glass transition temperature Tg, melting point Tm, and crystallization temperature of the sample. Each Tpc was determined.

(Measurement method of glass transition temperature of polyurethane)
The aqueous dispersion of polyurethane used in the examples was poured into a Teflon (registered trademark) -treated container and dried at room temperature for 24 hours. Then, it was further dried in an oven at 120 ° C. for 1 hour to prepare a polyurethane layered product having a thickness of 150 μm. The glass transition temperature of this layered product 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 appeared, the one having the lower temperature was adopted as the glass transition temperature.

(Method of measuring hydrogenation rate of polymer)
The hydrogenation rate of the polymer was measured by ¹ H-NMR measurement at 145 ° C. using orthodichlorobenzene-d ⁴ as a solvent.

(Measurement method of the ratio of racemo diad of polymer)
¹³ C-NMR measurement of the polymer was carried out at 200 ° C. using the ortho-dichlorobenzene-d ⁴ / trichlorobenzene-d ³ (mixing ratio (mass standard) 1/2) as a solvent and applying the inverse-gated decoupling method. went. In the result of this ¹³ C-NMR measurement, with the peak of 127.5 ppm of orthodichlorobenzene-d ⁴ as a reference shift, a signal of 43.35 ppm derived from meso dyad and a signal of 43.43 ppm derived from racemo dyad were obtained. Was identified. Based on the intensity ratio of these signals, the racemo-dyad ratio of the polymer was determined.

(Measurement method of crystallinity of polymer)
The crystallinity was confirmed by X-ray diffraction according to JIS K0131. Specifically, a wide-angle X-ray diffractometer (“RINT 2000” manufactured by Rigaku Corporation) was used to determine the diffraction X-ray intensity from the crystallized portion, and from the ratio to the overall diffraction X-ray intensity, the following formula The crystallinity was determined according to (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. The contact angle with respect to the surface of the film was measured for each of these liquid samples. The contact angle was measured as follows.
<Contact angle measuring method>
・ Measuring device: AutoDispenser AD-31 (manufactured by Kyowa Interface Science Co., Ltd.)
・ Control analysis software: FAMAS ver3.13
・ Contact angle measurement method: hanging drop method ・ Analysis method: Young-Laplace method ・ Teflon (registered trademark) coated needle: 18G (or 22G)
・ Liquid volume: 3 μL to 4 μL
・ Measurement waiting time: 3000 ms
・ Number of measurements: Measured 10 times and adopted the average value.

The measured contact angle θ was applied to the following Owens Wendt model 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. In the Owens 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 easily adhesive layer]
After peeling off the temporary support, the surface of the peeled temporary support was visually observed. As a result of the observation, the transferability of the easy-adhesion layer was judged according to the following criteria.
◯: No adhered piece consisting of the easily adhesive layer having a diameter of 50 μm or more remains on the surface of the temporary support.
Δ: One or more adhered pieces consisting of the easily adhesive layer having a diameter of 50 μm or more remain on the surface of the temporary support.
X: The temporary support itself could not be separated from the easy-adhesion layer.

[Evaluation Method of Adhesion between Easy Adhesion Layer and Base Film]
Eleven cuts were made longitudinally and laterally at 1 mm intervals in the easy-adhesion layer of the optical film to form 100 squares (10 × 10) of 1 mm square. Cellophane tape was attached to the surface of this easy-adhesion layer, which was quickly peeled off, and the number of squares remaining without peeling off 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]
Corona treatment was applied to the easy-adhesion layer surface of the optical film. Further, one side of an unstretched film (“Zeonor film” manufactured by Nippon Zeon Co., Ltd., thickness 100 μm, glass transition temperature 160 ° C. of resin) formed of norbornene-based resin 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 attached to the surface coated with this adhesive using a laminator. The adhesive was crosslinked by irradiating ultraviolet rays using a high pressure mercury lamp under the conditions of an illuminance of 350 mJ / cm ² and an integrated light material of 1000 mJ / cm ² . Thus, a bonded sample including the optical film and the unstretched film was obtained. Then, the bonded sample was cut into 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. A double-sided pressure-sensitive adhesive tape (manufactured by Nitto Denko Corp., product number “CS9621”) was used as the pressure-sensitive adhesive during the bonding. After the bonding, the bonded product was allowed to stand for 12 hours.
Then, a 90-degree peel 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 direction normal to the surface of the slide glass. The peeling speed during pulling was 20 mm / min. Since the force measured when the unstretched film peels off is the force required to peel the unstretched film from the optical film, the magnitude of this force was measured as the peel strength. This peel strength corresponds to the adhesive strength between the unstretched film and the optical film.

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

To a solution prepared by dissolving 0.014 parts of tetrachlorotungsten phenylimide (tetrahydrofuran) complex in 0.70 parts of toluene, 0.061 parts of a 19% diethylaluminum ethoxide / n-hexane solution was added and stirred for 10 minutes. To prepare a catalyst solution.
This catalyst solution was added to the pressure resistant reactor to start 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 the weight average molecular weight (Mw) of the obtained ring-opening polymer of dicyclopentadiene were 8750 and 28,100, respectively, and the molecular weight distribution (Mw / Mn) obtained from them was 3 It was .21.

  To 200 parts of the obtained solution of the ring-opening polymer of dicyclopentadiene, 0.037 part of 1,2-ethanediol was added as a terminating agent, heated to 60 ° C., and stirred for 1 hour to stop the polymerization reaction. Let To this, 1 part of a hydrotalcite-like compound (“Kyoward (registered trademark) 2000” manufactured by Kyowa Chemical Industry Co., Ltd.) was added, heated to 60 ° C., and stirred for 1 hour. Then, 0.4 parts of a filter aid (“Radiolite (registered trademark) # 1500” manufactured by Showa Chemical Industry Co., Ltd.) was added, and a PP pleated cartridge filter (“TCP-HX” manufactured by ADVANTEC Toyo Corp.) was used as an adsorbent. The solution was filtered off.

  To 200 parts of a solution of the ring-opening polymer of dicyclopentadiene after filtration (100 parts of polymer), 100 parts of cyclohexane was added, and 0.0043 parts of chlorohydridocarbonyltris (triphenylphosphine) ruthenium was added to obtain hydrogen. The hydrogenation reaction was carried out at a pressure of 6 MPa and 180 ° C. for 4 hours. As a result, a reaction liquid containing a hydride of a ring-opening polymer of dicyclopentadiene was obtained. This reaction liquid was a slurry solution in which hydride was deposited.

  27. A hydride of a ring-opening polymer of crystalline dicyclopentadiene was separated from the hydride contained in the above reaction solution and the solution by using a centrifuge and dried under reduced pressure at 60 ° C. for 24 hours. 5 parts were obtained. The hydride had a hydrogenation ratio of 99% or more, a glass transition temperature Tg of 94 ° C., a melting point (Tm) of 262 ° C., a crystallization temperature Tpc of 170 ° C., and a racemo dyad ratio of 89%.

[Production Example 2. Manufacturing 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 part of "IRGANOX (registered trademark) 1010" manufactured by BASF Japan Ltd.) was mixed to obtain a crystalline resin.

  The crystalline resin was charged 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 molded into a strand-shaped molded body by hot melt extrusion molding using the above-mentioned twin-screw extruder. This molded body was shredded with a strand cutter to obtain crystalline resin pellets.

Subsequently, the obtained pellets were fed to a hot 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 a method of 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 ℃ -290 ℃
・ Die temperature: 270 ℃
・ 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 substrate film was 0.7%.

[Production Example 3. Production of coating liquid for easy adhesion layer]
An aqueous dispersion of a carbonate-based polyurethane (“ADEKA BONTITER SPX-0672” manufactured by ADEKA, glass transition temperature −16 ° C.) in an amount of 100 parts by weight of polyurethane, and a polyfunctional epoxy compound as a cross-linking agent (Nagase Chemtex Corporation) 2.7 parts of "Denacol EX-521" manufactured by Japan, 0.18 parts of acetylene glycol ("Surfynol 440" manufactured by Nisshin Chemical Industry Co., Ltd.) as a surfactant, and ion-exchanged water as a solvent are mixed. Thus, a coating liquid having a solid content concentration of 30% was obtained.

[Example 1]
(1.1. Step of forming easily-adhesive layer on temporary support)
As a temporary support, a resin film (“Zeonor film ZF16-050” manufactured by Nippon Zeon Co., Ltd., thickness: 50 μm; hereinafter sometimes referred to as “temporary support 1”) formed of norbornene-based resin was prepared. The surface free energy of the surface of this 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 layer of the applied coating liquid was dried at 90 ° C. for 120 seconds to form an easy-adhesion 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)
The substrate film produced in Production Example 2 was corona-treated on the surface of the substrate film while being conveyed in the longitudinal direction of the substrate film. This corona treatment was performed under the conditions of an output of 100 W, an electrode width of 0.3 m, and a film transport speed of 0.080 m / min. The treatment 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 base film that was subjected to corona treatment was measured.

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

(1.4. Step of peeling temporary support)
The temporary support 1 was peeled off to obtain a multilayer film including a base film and an easy-adhesion 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 stretched in the width direction of the multilayer film 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 step)
After the stretching treatment, the multilayer film was subjected to a crystallization treatment of heating at 170 ° C. for 30 seconds. The above-mentioned crystallization treatment was performed in a state where the end portion of the multilayer film was fixed and tensioned so that wrinkles due to heat shrinkage did not occur.
Thereby, an optical film including the base film and the easy-adhesion layer was obtained. The crystallinity of the hydride of the ring-opening polymer of dicyclopentadiene in the substrate 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 formed of norbornene-based resin (“Zeonor film” manufactured by Nippon Zeon Co., Ltd., thickness 50 μm; hereinafter, may be referred to as “temporary support 2”).
An optical film was manufactured and evaluated in the same manner as in Example 1 except for the above matters.

[Example 3]
The substrate film is a resin film formed of norbornene-based resin (“ZEONOR film” manufactured by Zeon Corporation, thickness 100 μm, glass transition temperature of norbornene-based polymer 125 ° C .; hereinafter, may be referred to as “non-crystalline COP”). There is).
Further, in the stretching treatment of the multilayer film, the stretching ratio was changed to 3.0 times.
Furthermore, the multilayer film obtained after the stretching treatment was evaluated as an optical film without performing the crystallization treatment on the multilayer film.
An optical film was manufactured and evaluated in the same manner as in Example 1 except for the above matters.

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

[Comparative Example 1: Example in which no easy adhesion layer was 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-adhesion layer were not attached. The peel strength of the substrate film thus obtained was measured by the above-described measuring method. In this measuring method, the corona-treated surface of the substrate film was attached to the surface of the slide glass, and the peel strength was measured.

[Comparative Example 2: Example in which no easy adhesion layer was 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 substrate film was obtained instead of the optical film in the same manner as in Example 3 except that the substrate film and the easy-adhesion layer were not attached. The peel strength of the substrate film thus obtained was measured by the above-described measuring method. In this measuring method, the corona-treated surface of the substrate film was attached to the surface of the slide glass, and the peel strength was measured.

[Comparative Example 3: Example in which heat treatment was not performed after bonding with the easily adhesive 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 instead of the base film produced in Production Example 2.
Further, the stretching treatment and the crystallization treatment were not performed after the bonding of the crystallized base film and the easy-adhesion layer and the peeling of the temporary support.
An optical film was manufactured and evaluated in the same manner as in Example 1 except for the above matters.

[Comparative Example 4: Example in which heat treatment temperature was low]
The stretching temperature in the stretching process was changed to 90 ° C.
In addition, no crystallization treatment was performed.
An optical film was manufactured and evaluated in the same manner as in Example 1 except for the above matters.

[Comparative Example 5: Example in which the surface free energy of the temporary supporting surface was large]
Before applying the coating liquid produced in Production Example 3, a treatment strength of 4.2 kW was applied to the surface of the temporary support 1 under conditions of an output of 100 W, an electrode width of 0.3 m, and a film transport speed of 0.080 m / min.・ A corona treatment of min / m ² was applied.
An optical film was manufactured and evaluated in the same manner as in Example 1 except for the above matters. However, since the transferability of the easy-adhesion layer was poor, 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 applied to the film surface of the base film.
An optical film was manufactured and evaluated in the same manner as in Example 1 except for the above matters. However, since the transferability of the easy-adhesion layer was poor, 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 .
An optical film was manufactured and evaluated in the same manner as in Example 1 except for the above matters. However, in Comparative Example 7, the transferability of the easy-adhesion layer was insufficient, and thus the peel strength was not evaluated.

[Comparative Example 8: Example in which the surface free energy of the temporary supporting surface was large]
The surface of a resin film (“Zeonor film ZF16-050” manufactured by Nippon Zeon Co., Ltd., 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 this corona-treated surface. The applied coating layer was dried at 90 ° C. for 120 seconds to form an easy-adhesion layer having a thickness of 100 nm. Thus, a temporary support having a multilayer structure including the resin film and the easy-adhesion layer (hereinafter sometimes referred to as “temporary support 5”) was obtained.

This temporary support 5 having a multilayer structure was used instead of the temporary support 1 used in Example 1. At this time, the surface of the temporary support 5 having the multilayer structure on the side of the easy adhesion layer was used as a temporary support surface for further forming the easy adhesion layer.
Further, the corona treatment on the film surface of the substrate film was not performed.
An optical film was manufactured and evaluated in the same manner as in Example 1 except for the above matters. However, since the transferability of the easy-adhesion layer was poor, 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 Examples and Comparative Examples are shown in Tables 3 and 4 below. In the following table, in the column of adhesion, the numerical value of the molecule represents the number of squares left without peeling off the easily adhesive layer.

[Consideration]
As can be seen from Comparative Example 3, the easy-adhesion layer formed on the temporary support surface of the temporary support was simply laminated to the base film formed of the resin containing the alicyclic structure-containing polymer, High adhesion cannot be obtained and peeling is easy. Further, as can be seen from Comparative Example 4, even if heat treatment is performed after the easy-adhesion layer is attached to the substrate film, high adhesion can be obtained if the temperature of the heat treatment is out of the predetermined temperature range. Absent. On the other hand, in the examples, after the easy-adhesion layer is attached to the base film, the adhesion between the easy-adhesion layer and the base film is effectively increased by performing heat treatment in a predetermined temperature range. 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 material film are out of the predetermined ranges, they are formed on the temporary support surface. The easily adhesive layer thus formed cannot be smoothly transferred to the film surface of the base film. On the other hand, in the examples, 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 easily 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 material 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 substrate. It was confirmed that an optical film including a material film and a resin layer that is difficult to peel off from the base film can be manufactured.

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

Claims (7)

A step of forming a resin layer on the temporary support surface of the temporary support having a temporary support surface having a surface free energy of 20 mJ / m ² or less,
A step of subjecting a film surface of a substrate film formed of a resin containing an alicyclic structure-containing polymer to a hydrophilic treatment so that the surface free energy of the film surface becomes 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 hydrophilic film-treated film surface of the base film,
A step of peeling the temporary support, and
A method for producing an optical film, comprising a step of subjecting the resin layer and the base film to a heat treatment 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, 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. The step of applying the heat treatment to the resin layer and the base film,
A step of stretching the substrate film,
The process of advancing crystallization of the said alicyclic structure containing polymer contained in the said base film after extending | stretching is included, The manufacturing method of the optical film as described in any one of Claims 2-4.   The method for producing an optical film according to claim 1, wherein the hydrophilic treatment is at least one selected from the group consisting of corona treatment, plasma treatment and excimer treatment.   7. The optical film according to claim 1, 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.