JP2012020402A - Mold release film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold release film in which the transition of a release layer to an adherend is suppressed and which can alleviate an environmental load and has high transparency.SOLUTION: The mold release film has a release layer of 0.01-0.20 μm thickness on a base material film having a haze value of 0.1-10%. The release layer contains 100 pts.mass of an acid-modified polyolefin resin, 1-50 pts.mass of an oxazoline compound, and 5-1,000 pts.mass of polyvinyl alcohol. The haze value of the mold release film is 1.5 times as large as the haze value or below of the base material film before the release layer is installed, and the peel strength between the release layer and the adherend is 3.0 N/cm or below.

Description

  The present invention relates to a release film that suppresses the transfer of a release layer to an adherend, can reduce the load on the environment, and is excellent in transparency.

  Release films are widely used industrially in various fields. Specifically, the release film is an adhesive film, an adhesive surface / adhesive surface protective material or process material such as an adhesive tape, a process material for manufacturing a printed wiring board, a flexible printed wiring board, a multilayer printed wiring board, etc. , It is used for polarizing plate and retardation plate protective materials for liquid crystal display parts, and for forming film-like structures.

  The release film is obtained, for example, by forming a resin having releasability into a film. However, since a resin having releasability is generally expensive, there is a problem that a release film in which the resin is formed into a single film becomes expensive. Therefore, an inexpensive base film is coated with a release layer by extrusion lamination or coating, so-called “coat film”, that is, a release layer made of a resin having releasability is laminated on the base film. Many release films have been proposed. However, in the extrusion laminating method, it is difficult to reduce the thickness of the release layer formed on the base film, and it is difficult to form a thin film. In addition, there is a problem that the adhesion between the release layer and the substrate film is not sufficient.

  On the other hand, a method for forming a release layer by forming a release layer on a substrate film by a coating method can make the release layer thinner, and thus various coating methods have been proposed.

  For example, it has been studied to obtain a release film in which a release layer is formed by applying a coating agent containing an addition polymerization type silicone resin on a polyester film (Patent Document 1). In addition, it has been studied to obtain a release film on which a release layer is formed by applying a coating agent containing a fluororesin and an amino resin to a polyester film or the like (Patent Document 2).

  However, in the case of Patent Document 1 and Patent Document 2, in actual use, when the adherend (target for which the release film is used) and the release film are peeled off, the release on the film is performed. Components such as low molecular weight compounds contained in the layer may migrate to the adherend. Therefore, its use has been limited in fields where contamination of the adherend is particularly problematic, such as in the electronic parts field. In addition, since an organic solvent is used as a solvent for dissolving the mold release agent, there are problems such as safety and hygiene for the coat worker and environmental load. Furthermore, when printing, overcoating, or the like is performed on the release layer, there is a problem that printing ink or overcoat coating is repelled and the coating cannot be normally performed in many cases.

  Patent Document 3 proposes a release film in which a fluorine-based coating agent is applied on the film. In such a case, the low molecular weight compound contained in the release layer has been improved so that it is difficult to migrate to the adherend during use. However, even in the case of Patent Document 3, since an organic solvent system is used at the time of application, there are problems such as safety and hygiene for workers and burden on the environment.

  Patent Document 4 describes a release composition that uses a water-based coating agent such as a silicone emulsion or a urethane emulsion as a release agent, and is considered in terms of safety and hygiene for workers and environmental load. In addition, the problem that components such as low molecular weight compounds contained in the release layer migrate to the adherend during use has been improved. However, in Patent Document 4, since the release agent contains a silicone-based material, printing ink, overcoat coating, and the like are repelled when printing or overcoating is performed on the surface having the release layer. There is a problem that it cannot be applied normally.

  In Patent Document 5, a release film containing an acid-modified polyolefin resin and a crosslinking agent and / or polyvinyl alcohol in a release layer is studied. In such a case, the problem that components such as a low molecular weight compound contained in the release layer migrate to the adherend during use is improved. In addition, since the release agent is water-based, consideration is given to problems such as safety and hygiene for coat workers and environmental impact. Furthermore, it is possible to perform processing such as printing and overcoat on the release layer, and coating on the release layer is also possible. However, in the case of Patent Document 5, there is a problem that the haze value becomes high and the transparency required by the release film user is not always satisfied.

JP 2002-182037 A JP 2007-002066 A JP 2004-114620 A JP 2005-125656 A WO2009 / 25063 publication

  In view of these problems, an object of the present invention is to provide a release film that has no transition of a release layer to an adherend, has a low environmental load during coating, and has high transparency. .

  As a result of intensive studies to solve the above problems, the present inventors have obtained a release film in which a release layer having a specific composition and a specific thickness is formed on a base film. The present inventors have found that the above problems can be solved and have reached the present invention.

That is, the gist of the present invention is as follows.
(1) A release film having a release layer having a thickness of 0.01 to 0.20 μm on a base film having a haze value of 0.1 to 10%, wherein the release layer is an acid-modified polyolefin. 100 parts by mass of resin, 1-50 parts by mass of oxazoline compound, 5 to 1000 parts by mass of polyvinyl alcohol, the haze value is 1.5 times or less the haze value of the base film before providing the release layer, and A release film having a peel strength between the release layer and an adherend of 3.0 N / cm or less.
(2) The release film according to (1), wherein the acid-modified polyolefin resin has an acid modification ratio of 1 to 15% by mass.
(3) When producing the release film of (1) or (2), the release film is wound around a take-up core having a load of 2 to 3 kN / 200 mm at the time of 3% flatness in the paper tube strength measurement. And then aging at 60 to 80 ° C., a method for producing a release film.

  The release film of the present invention has high wettability, can be subjected to processing such as printing and overcoat on the surface of the release film having a release layer, and has good release properties. . In addition, a mold release agent such as waxes, low molecular weight silicone compounds, and surfactants is not required for exhibiting mold release properties. For this reason, it can suppress that the low molecular weight compound etc. which are contained in the mold release layer on a film transfer to a to-be-adhered body at the time of use. In addition, there are no problems such as safety and hygiene for workers and environmental burdens, and it has excellent transparency. The release film of the present invention is a protective material such as an adhesive material and a liquid crystal display part, a process material when producing a printed wiring board, and a film-like structure such as an ion exchange membrane or a ceramic green film. It can be suitably used for applications that require transparency, such as applications. Furthermore, according to the method for producing a release film of the present invention, the release film of the present invention can be easily obtained industrially.

Hereinafter, the present invention will be described in detail.
The release film of the present invention has a base material and a release layer provided on the base material. The release layer contains an acid-modified polyolefin resin, an oxazoline compound, and polyvinyl alcohol (hereinafter sometimes referred to as “PVA”).

  The olefin component, which is the main component of the acid-modified polyolefin resin contained in the release layer, is not particularly limited, but is preferably an olefin having 2 to 4 carbon atoms from the viewpoint of adhesion to the base film. Among these, ethylene, propylene, isobutylene and 1-butene are preferable, ethylene and propylene are more preferable, and ethylene is most preferable. A mixture thereof may be used.

  Examples of the acid-modified component of the acid-modified polyolefin resin include an unsaturated carboxylic acid component. Examples of unsaturated carboxylic acid components include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, and the like, as well as unsaturated dicarboxylic acid half esters and half amides. It is done. Among these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferable from the viewpoint of dispersion stability of the resin, and acrylic acid, methacrylic acid, and maleic anhydride are particularly preferable.

  The acid modification ratio of the acid-modified polyolefin resin is preferably 1 to 15% by mass, more preferably 1 to 13% by mass, even more preferably 2 to 9% by mass, and 5 to 9% by mass. % Is even more preferred. When the amount of the acid-modified component is less than 1% by mass, sufficient adhesion between the release layer and the substrate film may not be obtained, and the adherend may be contaminated. In addition, it may be difficult to disperse the resin in water. On the other hand, if it exceeds 15% by mass, the releasability may decrease.

  The acid-modified polyolefin resin preferably contains a (meth) acrylic acid ester component from the viewpoint of improving the adhesion between the release layer and the base film. When a (meth) acrylic acid ester component is included, the content is preferably 0.5 to 40% by mass from the viewpoint of excellent adhesion between the release layer and various types of substrates (adhered bodies). 1 to 20% by mass, more preferably 3 to 10% by mass.

  Examples of the (meth) acrylic acid ester component include an esterified product of (meth) acrylic acid and an alcohol having 1 to 30 carbon atoms. Especially, the esterified substance of (meth) acrylic acid and a C1-C20 alcohol is preferable from the point of availability. Specific examples of such compounds include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, (meth) acrylic acid. Examples include octyl, decyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, and the like. Mixtures of these may be used. Among these, from the viewpoint of adhesion between the release layer and the base film, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl acrylate, and octyl acrylate are more preferable. Ethyl acid and butyl acrylate are more preferable, and ethyl acrylate is particularly preferable. Here, “(meth) acrylic acid˜” means “acrylic acid˜ or methacrylic acid˜”.

  Each component constituting the acid-modified polyolefin resin may be copolymerized in the acid-modified polyolefin resin, and the form thereof is not limited. Examples of the state of copolymerization include random copolymerization, block copolymerization, and graft copolymerization (graft modification).

  As the acid-modified polyolefin resin, a commercially available product can be suitably used. Specific examples thereof include “Bondaine” series manufactured by Arkema, which is a maleic anhydride-modified polyolefin resin, such as “KX-4110”, “HX-8210”, “HX”. -8290 "," AX-8390 "and the like.

The oxazoline compound contained in the release layer plays a role as a crosslinking agent.
The content of the oxazoline compound needs to be 1 to 50 parts by mass, preferably 3 to 30 parts by mass, and more preferably 5 to 10 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin. When the content of the oxazoline compound is less than 1 part by mass, the adhesion between the release layer and the substrate film is reduced, and contamination of the adherend occurs. Furthermore, it becomes difficult to make the coating agent (coating agent) aqueous, which is the previous stage of forming the release layer. On the other hand, if it exceeds 50 parts by mass, there is a problem that sufficient releasability cannot be obtained.

  The oxazoline compound in the present invention is not particularly limited, but those having two or more oxazoline groups in the molecule are preferable. For example, 2,2′-bis (2-oxazoline), 2,2′-ethylene-bis (4,4′-dimethyl-2-oxazoline), 2,2′-p-phenylene-bis (2-oxazoline) , A compound having an oxazoline group such as bis (2-oxazolinylcyclohexane) sulfide, and a polymer containing an oxazoline group (an oxazoline group-containing polymer). These oxazoline compounds can be used alone or in combination of two or more.

  Among these, an oxazoline group-containing polymer is preferable from the viewpoint of easy handling. The oxazoline group-containing polymer is obtained by polymerizing an oxazoline having an addition polymerization property such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline. Furthermore, if necessary, other monomers may be copolymerized. The polymerization method of the oxazoline group-containing polymer is not particularly limited, and various known polymerization methods can be employed.

  Commercially available products can be suitably used as the oxazoline group-containing polymer, and examples thereof include “Epocross Series” manufactured by Nippon Shokubai Co., Ltd. More specifically, water-soluble type “WS-500”, “WS-700”, emulsion type “K-1010E”, “K-1020E”, “K-1030E”, “K-2010E”, “ K-2020E "," K-2030E "and the like.

  The PVA contained in the release layer is not particularly limited, and examples thereof include a completely or partially saponified vinyl ester polymer. As the saponification method, a known alkali saponification method or acid saponification method can be used. Among them, a saponification method in which alcoholysis is performed using an alkali hydroxide in methanol is preferable. The polyvinyl alcohol in the present invention preferably has water solubility for use as a coating agent as described later.

  Examples of vinyl esters for obtaining PVA include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, and vinyl versatate. Among these, vinyl acetate is most preferable because it is easily available industrially.

  It is also possible to copolymerize the above vinyl ester with another vinyl compound as long as the effects of the present invention are not impaired. Other vinyl compounds that are vinyl compounds include unsaturated monocarboxylic acids such as crotonic acid, acrylic acid, and methacrylic acid and their esters, salts, anhydrides, amides, nitriles, maleic acid, itaconic acid, and fumaric acid. And unsaturated dicarboxylic acids and salts thereof, α-olefins having 2 to 30 carbon atoms, alkyl vinyl ethers, vinyl pyrrolidones and the like.

Although the average degree of polymerization of PVA is not specifically limited, 300-2000 are preferable.
The content of PVA in the release layer is required to be 5 to 1000 parts by weight, preferably 10 to 600 parts by weight, more preferably 20 to 400 parts by weight, with respect to 100 parts by weight of the acid-modified polyolefin resin. -200 mass parts is especially preferable. If it is less than 5 mass parts, there exists a problem that it is inferior to the adhesiveness of a mold release layer and a base film. On the other hand, when it exceeds 1000 mass parts, the adhesiveness of a mold release layer and a base film will deteriorate, and also wettability will fall. In addition, when used as a coating agent, which is a stage before forming the release layer, the liquid stability may be lowered.

  As PVA, a commercially available product can be suitably used. For example, “JC-05”, “VC-10”, “ASC-05X”, “UMR-10HH” of “J-Poval” series of Nippon Vinegar Poval Co., Ltd. Kuraray “Kuraray Poval” series “PVA-103”, “PVA-105”, “Exeval” series “AQ4104”, “HR3010”, Denki Poval “Denka Poval” series “PC-1000”, "PC-2000" etc. are mentioned.

  In the release layer, the total content of the silicone compound, the fluorine compound, the wax, and the surfactant is preferably 1 part by mass or less, and 0.5 parts by mass or less with respect to 100 parts by mass of the acid-modified polyolefin resin. It is more preferable that it is 0.1 mass part or less, and it is especially preferable that it is not included. The smaller the content, the better the adhesion between the release layer and the base film, and the more the contamination of the adherend is suppressed.

Examples of the silicone compound include oligomers and polymers having a siloxane bond as a main skeleton such as dimethyldichlorosilane.
Examples of the fluorine compound include ethylene tetrafluoride.

  The waxes mean plant waxes, animal waxes, mineral waxes, petrochemical waxes and the like having a number average molecular weight of 10,000 or less. Specifically, candelilla wax, carnauba wax, rice wax, wood wax, berry wax, jojoba wax, shea butter, beeswax, shellac wax, lanolin wax, whale wax, montan wax, ceresin, paraffin wax, microcrystalline wax, synthetic Examples thereof include polyethylene wax, synthetic polypropylene wax, and synthetic ethylene-vinyl acetate copolymer wax.

  Examples of the surfactant include a cationic surfactant, an anionic surfactant, a nonionic (nonionic) surfactant, an amphoteric surfactant, a fluorosurfactant, and a reactive surfactant. In addition to those generally used for emulsion polymerization, emulsifiers are also included.

  Examples of the cationic surfactant include amine salts, alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkylbenzyldimethylammonium salts.

  Anionic surfactants include higher alcohol sulfates, higher alkyl sulfonic acids and their salts, alkyl benzene sulfonic acids and their salts, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl Examples include sulfosuccinate.

  Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide-propylene oxide copolymer, etc. And a sorbitan derivative such as a polyoxyethylene sorbitan fatty acid ester.

Examples of the fluorine-based surfactant include perfluoroalkylsulfonic acid, perfluoroalkylcarboxylic acid [CF ₃ (CF ₂ ) _n COOH], fluorine telomer alcohol, and the like.

  Examples of amphoteric surfactants include lauryl betaine and lauryl dimethylamine oxide. Examples of reactive surfactants include alkylpropenylphenol polyethylene oxide adducts and their sulfate esters, allyl alkylphenol polyethylene oxide adducts and their sulfate esters, allyl dialkylphenol polyethylene oxide adducts and their sulfate esters, etc. And compounds having a reactive double bond.

The base film will be described below.
Examples of the resin material used for the base film include thermoplastic resins. Examples of the thermoplastic resin include polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polylactic acid (PLA); polyolefin resins such as polypropylene; polystyrene resin 6-nylon, poly-m-xylylene adipamide Polyamide resins such as (MDX-6 nylon); polycarbonate resins; polyacrylonitrile resins; polyimide resins; multilayers of these resins (for example, nylon 6 / MDX-6 / nylon 6, nylon 6 / ethylene-vinyl alcohol) Copolymer / nylon 6), a mixture, etc. are mentioned.

  The haze value of the base film is from 0.1 to 10% from the viewpoint of transparency. A method for measuring the haze value will be described later.

  The base film obtained from the above resin material may be stretched. The base film may contain a known additive or stabilizer, such as an antistatic agent, a plasticizer, a lubricant, or an antioxidant. Further, the base film may have a surface subjected to corona treatment, plasma treatment, ozone treatment, chemical treatment, solvent treatment or the like as a pretreatment in order to improve adhesion when laminated with other materials. Moreover, silica, alumina, etc. may be vapor-deposited, and other layers, such as a barrier layer, an easily bonding layer, an antistatic layer, an ultraviolet absorption layer, and an adhesive layer, may be laminated.

  The base film may be easily charged, and in this case, it is preferable that the base film is subjected to antistatic treatment. If the base film is antistatically treated, the frictional charge generated in the process of peeling off the obtained release film and the static electricity generated by the peeling charge will remove dust, dust, dust, etc. in the atmosphere. It is possible to prevent product defects caused by adsorption. In addition, when the release film is used as a protective material such as an adhesive, it is possible to prevent a decrease in adhesive force due to dust and dirt adhering to the adhesive surface due to static electricity generated by peeling charging.

  Examples of the method for performing an antistatic treatment on the base film include a method of kneading an antistatic material in a resin material constituting the base film, a method of laminating a layer containing an antistatic material on the base film, and the like. Among these, from the viewpoint of cost, it is preferable to perform an antistatic treatment by a method of laminating a layer containing an antistatic material.

  Antistatic materials that can be used for antistatic treatment include conductive polymers such as polyaniline, polypyrrole, and thiophene, conductive carbon such as carbon black and ketjen black, tin oxide, antimony-doped tin oxide, and tin oxide doped Examples include tin oxide ultrafine particles such as indium. By kneading into the resin material as a composition in which these antistatic materials are mixed with the resin material constituting the base film alone or with a binder resin, or by coating the surface of the resin material as a coating agent Antistatic treatment can be performed.

  The haze value of the release film of the present invention is preferably 1.5 times or less, more preferably 1.3 times or less the haze value of the base film before providing the release layer. When it exceeds 1.5 times, there is a problem that transparency that can withstand actual use cannot be achieved.

  In the release film of the present invention, the thickness of the release layer needs to be 0.01 to 0.2 μm, and more preferably 0.1 to 0.2 μm. When the release layer thickness exceeds 0.2 μm, the transparency cannot be obtained, and the haze value of the release film exceeds 1.5 times the haze value of the base film, and the transparency cannot be obtained. There is. On the other hand, when it is less than 0.01 μm, there is a problem that the releasability is not exhibited.

  The wetting tension on the surface of the release layer is preferably 30 mN / m or more, and more preferably 32 mN / m or more. If the wetting tension is less than 30 mN / m, it may be difficult to laminate another coating agent on the release layer. The wetting tension means a critical surface tension by Zisman and can be measured according to the method described in JIS K 6768. Since the release film of the present invention has excellent wettability on the surface of the release layer, the surface of the release layer can be subjected to processing such as printing and overcoat.

  When the release film of the present invention is used, the release layer and the adherend are peeled between the release layer and the adherend after heat-pressing the release layer and the adhesive material (adherent) of the release film. The strength needs to be 3 N / cm or less. If the peel strength exceeds 3 N / cm, the adhesive strength is too strong and it is difficult to use as a release film.

A method for producing the release film of the present invention will be described below.
The release film of the present invention is a production in which a release layer is formed by applying a coating agent (coating agent) containing an acid-modified polyolefin resin, an oxazoline compound and PVA onto a base film and then drying. It can be obtained by a method. According to this method, a release film can be obtained by an industrially simple production method.

A method for producing a coating agent containing an acid-modified polyolefin resin, an oxazoline compound, and PVA is not particularly limited as long as each component is uniformly mixed in a liquid medium. For example, the following methods can be mentioned.
(1) A method in which a dispersion or solution of an oxazoline compound and a dispersion or solution of PVA are added to and mixed with a dispersion or solution of an acid-modified polyolefin resin.
(2) A method of liquefying a mixture of an acid-modified polyolefin resin, an oxazoline compound, and PVA.

  In the case of the method (1), a dispersion or solution of each component may be prepared and mixed as appropriate. The solute concentration of the dispersion or solution of PVA is not particularly limited, but is preferably 5 to 10% by mass from the viewpoint of ease of handling.

In the case of the method (2), an oxazoline compound and PVA may be added when the acid-modified polyolefin resin is liquefied.
In addition, when adding components other than acid-modified polyolefin resin, an oxazoline compound, and PVA, it can add in the arbitrary steps in the method of (1) or (2).

  The solvent used for the coating agent containing the acid-modified polyolefin resin, the oxazoline compound, and PVA is not particularly limited as long as the coating agent can be applied onto the base film. Examples of the solvent include water, an organic solvent, and an aqueous medium containing water and an amphiphilic organic solvent. Especially, it is preferable to use water or an aqueous medium from an environmental viewpoint and a soluble viewpoint of PVA.

  In the present invention, the aqueous medium means a solvent containing water and an amphiphilic organic solvent and having a water content of 2% by mass or more. The amphiphilic organic solvent means an organic solvent having a water solubility of 5% by mass or more with respect to the organic solvent at 20 ° C. The solubility of water in an organic solvent at 20 ° C. is described in documents such as “Solvent Handbook (Kodansha Scientific, 1990, 10th edition)”.

  Specific examples of the amphiphilic organic solvent include methanol, ethanol (hereinafter sometimes abbreviated as “EA”), n-propanol (hereinafter sometimes abbreviated as “NPA”), isopropanol (hereinafter “IPA”). Alcohols such as tetrahydrofuran and 1,4-dioxane; ketones such as acetone and methyl ethyl ketone; methyl acetate, n-propyl acetate, isopropyl acetate, methyl propionate, propionic acid Esters such as ethyl and dimethyl carbonate; in addition, ammonia, diethylamine, triethylamine (hereinafter sometimes referred to as “TEA”), diethanolamine, triethanolamine, N, N-dimethylethanolamine (hereinafter referred to as “DMEA”) Abbreviated), N, N-diethylethanolamine, N- Examples thereof include organic amine compounds such as diethanolamine, and lactams such as 2-pyrrolidone and N-methyl-2-pyrrolidone.

  A method for dispersing the acid-modified polyolefin resin in the aqueous medium as described above is not particularly limited, and examples thereof include a method described in International Publication WO02 / 055598.

  The dispersed particle size of the acid-modified polyolefin resin in the aqueous medium preferably has a number average particle size of 1 μm or less from the viewpoint of stability when mixed with other components and storage stability after mixing. More preferably, it is 8 μm or less. Such a number average particle size can be achieved by the method described in the above-mentioned International Publication WO02 / 055598.

  In the production method of the present invention, the solid content in the coating agent can be appropriately selected depending on the lamination conditions, the intended thickness and performance, and is not particularly limited. However, in order to keep the viscosity of the coating agent moderate and to form a good release layer, 1 to 60% by mass is preferable, and 5 to 30% by mass is more preferable.

  As a method for applying the coating agent to the base film, known methods such as gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, and brush coating are used. Etc.

  Apply the coating agent uniformly on the surface of the base film, set it at around room temperature if necessary, and then subject it to a drying treatment or a heat treatment for drying. It can be formed in close contact with.

  The release film of the present invention needs to be aged in order to stabilize the release property after forming the release layer on the base film. More specifically, it is necessary to apply a coating agent to the base film and then dry it to obtain a release film, and then perform aging after winding the release film It is.

  When winding the release film of the present invention before aging, it is necessary to wind a 3% flat load on a core of 2 to 3 kN / 200 mm in the paper tube strength measurement. It is preferable to wind on a core of ˜2.8 kN / 200 mm. When using a core with a load resistance at 3% flatness of less than 2 kN / 200 mm when measuring the paper tube strength at the time of winding, the release strength of the release film increases, making it unsuitable for use as a release film. Become. On the other hand, even if a core having a load resistance of 3% flattened exceeding 3 kN / 200 mm is used, the release strength of the release film is increased, making it unsuitable for use as a release film.

  The aging temperature needs to be 60 to 80 ° C. If the aging temperature is less than 60 ° C, the releasability is deteriorated. On the other hand, if it exceeds 80 ° C, the transparency of the obtained release film is deteriorated. The aging time needs to be 48 hours or more. If the aging time is less than 48 hours, the releasability deteriorates.

In this way, the release film is wound up to form a film roll and then aged. The mold release film after aging has excellent transparency and mold release properties.
The release film of the present invention has good release properties for various adherends. Therefore, it can be suitably used in applications where it is necessary to form a laminate by laminating on various adherends via a release layer and then peel off. Specifically, suitable materials include protective materials for adhesive materials and liquid crystal display parts, printed circuit board pressing process materials, film-like structure forming process materials, and the like.

  The pressure-sensitive adhesive material is obtained by laminating a pressure-sensitive adhesive on a base material. Specific examples include a pressure-sensitive adhesive film, an adhesive film, a pressure-sensitive adhesive tape, and a pressure-sensitive adhesive tape. Although the component and base material of an adhesive are not specifically limited, For example, at least 1 type chosen from the acrylic adhesive, the natural rubber adhesive, and the synthetic rubber adhesive is mentioned. If necessary, the pressure-sensitive adhesive may contain rosin-based, coumarone-indene-based, terpene-based, petroleum-based, styrene-based, phenol-based, xylene-based tackifiers, and the like. Examples of the substrate include paper, cloth, and resin material.

  Examples of the liquid crystal display component include a polarizing plate, a retardation polarizing plate, a retardation plate, and the like. Examples of the printed wiring board include a single-sided printed wiring board, a double-sided printed wiring board, a flexible printed wiring board, and a multilayer printed wiring board.

  Examples of the film-like structure include an ion exchange membrane made of a polymer electrolyte such as perfluorosulfonic acid resin, and a ceramic green sheet made of dielectric ceramics or glass. These are formed by casting a raw material in a paste or slurry form with a solvent onto a release film.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
The measurement methods used for evaluating the examples and comparative examples are as follows.
(1) Measurement of acid-modified component of acid-modified polyolefin resin Ortho-dichlorobenzene (d ₄ ) was used as a solvent, and measurement was performed with a 1H-NMR analyzer (“GE Min I 2000/300”, 300 MHz, manufactured by Varian). The measurement temperature was 120 ° C.

(2) Solid content concentration An appropriate amount of the obtained coating agent was weighed and heated at 150 ° C. until the mass of the residue (solid content) reached a constant weight. The solid content concentration was determined by the following formula.
(Solid content concentration) (%) = [(mass of coating agent reaching constant weight) / (mass of coating agent before heating)] × 100

(3) Thickness of release layer The total thickness of the obtained release film was measured with a contact-type film thickness meter (manufactured by HEIDENHAIN). It calculated | required by reducing the thickness of a base film from the measured value.

(4) Wet tension measurement of release layer surface The measurement was performed according to the measurement method described in JIS K 6768. A standard solution (ethylene glycol monoethyl ether / formamide) having a different surface tension was applied to the measurement surface, and the surface tension of the standard solution determined to wet the release layer surface was defined as the wetting tension of the release layer surface.

(5) Peel strength Adhesive tape (Nitto Denko's "No. 31B") using an acrylic adhesive with a polyester having a width of 50 mm and a length of 150 mm as a base material on the release layer surface of the obtained release film. ) Was pressed into a laminate. This was sandwiched between metal plates / rubber plates / laminated bodies / rubber plates / metal plates using a metal plate and a rubber plate, and treated in an atmosphere of 2 kPa load × 70 ° C. for 20 hours. Thereafter, the sample was left in an atmosphere of 23 ° C. × 50% for 30 minutes or more to obtain a peel strength measurement sample. The peel strength between the adhesive tape of the peel strength measurement sample and the release film was measured with a tensile tester (manufactured by Shimadzu Corporation, “Autograph”) in an atmosphere of 23 ° C. × 50%. In addition, 180 degree peeling measurement was performed at a peeling speed of 300 mm / min.

(6) Residual adhesion rate In the peel strength measurement of (5) above, the peel strength of a 180 ° peel test was measured using an unused polyester-based adhesive tape. Next, the peeled polyester base adhesive tape was attached to a clean stainless steel plate well wiped with ethyl acetate, and the peel strength in the 180 ° peel test was measured in the same manner.
(Residual adhesion rate) (%) = [(Peeling strength of peeled adhesive tape) / (Peeling strength of unused pressure-sensitive adhesive tape)] × 100

(7) Transparency The transparency of the base film and the release film was measured with a haze meter (trade name “NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd.).

(8) Load at 3% flatness in paper tube strength measurement Using a paper tube strength measuring device (“No. 97419” manufactured by Yoshimizu), the breaking pressure of the core was measured. Displacement was given, and the load when the core flattened by 3% was measured.

<Preparation of acid-modified polyolefin resin (P-1)>
4 280 g of propylene-butene-ethylene terpolymer [manufactured by Huls Japan, trade name “Best Plast 708”, propylene / butene / ethylene = 64.8 / 23.9 / 11.3 (mass ratio)] It was put into a one-necked flask and heated and melted under a nitrogen atmosphere. Next, while maintaining the system temperature at 170 ° C. and stirring, 32.0 g of maleic anhydride as an unsaturated carboxylic acid and 6.0 g of dicumyl peroxide as a radical generator were added over 1 hour, respectively, and then stirred. The reaction was carried out for 1 hour. After completion of the reaction, the obtained reaction product was put into a large amount of acetone to precipitate an acid-modified polyolefin resin. This acid-modified polyolefin resin was further washed several times with acetone to remove unreacted maleic anhydride, and then dried under reduced pressure in a vacuum dryer to obtain an acid-modified polyolefin resin (P-1).

<Preparation of acid-modified polyolefin resin (P-2)>
Propylene-butene-ethylene terpolymer [manufactured by Huls Japan, trade name “Best Plast 408”, propylene / butene / ethylene = 12.3 / 82.2 / 5.5 (mass ratio)] was used. . Otherwise in the same manner as in Preparation Example 1, an acid-modified polyolefin resin (P-2) was obtained.

<Preparation of aqueous dispersion of acid-modified polyolefin resin>
(Acid-modified polyolefin resin aqueous dispersion ER-10)
A stirrer equipped with a heat-resistant 1-liter glass container with a heater was used. 60.0 g of “Bondyne LX-4110” (manufactured by Arkema, maleic anhydride-modified polyolefin resin), 90.0 g of IPA (manufactured by Wako Pure Chemical Industries, Ltd.), 3.0 g of TEA (manufactured by Wako Pure Chemical Industries, Ltd.) and 147 0.0 g of distilled water was charged into a glass container. And the rotational speed of the stirring blade was set to 300 rpm, and the system temperature was maintained at 140 to 145 ° C. for 30 minutes. Then, it was put on a water bath and cooled to 25 ° C. while stirring at a rotational speed of 300 rpm. Furthermore, pressure filtration (air pressure 0.2 MPa) was performed with a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave). As a result, a milky white uniform acid-modified polyolefin resin aqueous dispersion (ER-10) was obtained.

(Acid-modified polyolefin resin aqueous dispersion ER-30)
60.0 g of acid-modified polyolefin resin (P-1), 45.0 g of ethylene glycol-n-butyl ether (made by Wako Pure Chemical Industries, special grade, boiling point 171 ° C.) 6.9 g DMEA (manufactured by Wako Pure Chemical Industries, special grade, boiling point 134 ° C., 1.0 times equivalent to the carboxyl group of the maleic anhydride unit in the resin), 188.1 g of distilled water was injected, Stirring was performed at a rotation speed of 300 rpm of the stirring blade provided in the container. During stirring, no resin precipitation was observed at the bottom of the container, confirming that it was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 140 ° C. and further stirred for 60 minutes. Then, while stirring while maintaining the rotation speed at 300 rpm, the mixture was cooled to room temperature (25 ° C.) by air cooling, and pressure filtered (air pressure 0. 0 mm) with a 300 mesh stainless steel filter (wire diameter: 0.035 mm, plain weave). 2 MPa) to obtain a milky-yellow uniform acid-modified polyolefin resin dispersion (ER-30). There was almost no residual resin on the filter.

(Acid-modified polyolefin resin aqueous dispersion ER-60)
Instead of the acid-modified polyolefin resin (P-1) in Preparation Example 4, an acid-modified polyolefin resin (P-2) was used. Otherwise by performing the same operations as in the preparation of (ER-30), an acid-modified polyolefin resin aqueous dispersion (ER-60) was obtained.

  Table 1 shows the composition of the acid-modified polyolefin resin used for the production of each aqueous dispersion.

[Example 1]
(ER-10) and an aqueous solution of an oxazoline compound (“Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd., solid concentration 40% by mass) with respect to 100 parts by mass of the solid content of (ER-10) Further, PVA aqueous solution (“VC-10”, degree of polymerization 1,000, solid content concentration 10% by mass, manufactured by NIPPON BI POVAR CO., LTD.) And PVA solid content 30 parts by mass so that the solid content becomes 5 parts by mass. It mixed so that the coating agent might be obtained.

  This coating agent is applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret S-50" manufactured by Unitika Co., Ltd., thickness 50 μm) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a rate of drying at 140 ° C. for 90 seconds, and the resultant was wound up to 2000 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.5 kN / 200 mm). A film roll was prepared. This film roll was processed at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.18 μm. The evaluation of Example 1 is shown in Table 2.

[Example 2]
(ER-30) and (ER-30) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 with a PVA solid content of 800 so that the solid content of oxazoline compound is 30 parts by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret S-75", unit thickness 75 µm, manufactured by Unitika Co., Ltd.) with a clean coater (Okazaki Machine Industry Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and the resultant was wound up to 2000 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.1 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. The evaluation of Example 2 is shown in Table 2.

[Example 3]
(ER-60) and (ER-60) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 at a PVA solid content of 200 so that the oxazoline compound solid content is 10 parts by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent is applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-188", unit thickness 188 µm, manufactured by Unitika Co., Ltd.) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.8 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.15 μm. The release layer had a wetting tension of 32 mN / m. The evaluation of Example 3 is shown in Table 2.

[Example 4]
(ER-60) and (ER-60) solid content of 100 parts by mass, Epocros WS-500 is further adjusted to 10% of PVA solid content of VC-10 so that the solid content of oxazoline compound is 40 parts by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.8 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.18 μm. The evaluation results of Example 4 are shown in Table 2.

[Example 5]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further adjusted to 10% of PVA solid content of VC-10 so that the solid content of oxazoline compound is 40 parts by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.8 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. The evaluation results of Example 5 are shown in Table 2.

[Example 6]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 to have a PVA solid content of 100 so that the oxazoline compound solid content is 1 part by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.8 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. The evaluation results of Example 6 are shown in Table 2.

[Example 7]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 to have a PVA solid content of 5 so that the oxazoline compound solid content is 5 parts by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to the corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika Co., Ltd.) using a clean coater (manufactured by Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.8 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. The evaluation results of Example 7 are shown in Table 2.

[Example 8]
With respect to 100 parts by mass of (ER-10) and (ER-10), Epocros WS-500 is further mixed with VC-10 at 1000 PVA solids so that the solid content of oxazoline compound is 5 parts by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.8 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. The evaluation results of Example 8 are shown in Table 2.

[Example 9]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 to have a PVA solid content of 30 so that the oxazoline compound solid content is 5 parts by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret S-75", unit thickness 75 µm, manufactured by Unitika Co., Ltd.) with a clean coater (Okazaki Machine Industry Co., Ltd.). , 200 lines / inch, depth 10 μm). Thereafter, coating was performed at a rate of drying at 140 ° C. for 90 seconds, and the resultant was wound up to 2000 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.5 kN / 200 mm). A film roll was prepared. This film roll was processed at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.01 μm. The evaluation results of Example 9 are shown in Table 2.

[Example 10]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 to have a PVA solid content of 30 so that the oxazoline compound solid content is 5 parts by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret S-75", unit thickness 75 µm, manufactured by Unitika Co., Ltd.) with a clean coater (Okazaki Machine Industry Co., Ltd.). , 140 lines / inch, depth 50 μm). Thereafter, coating was performed at a rate of drying at 140 ° C. for 90 seconds, and the resultant was wound up to 2000 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.5 kN / 200 mm). A film roll was prepared. This film roll was processed at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.20 μm. The evaluation results of Example 10 are shown in Table 2.

[Example 11]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 to have a PVA solid content of 100 so that the oxazoline compound solid content is 1 part by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Then, coating was performed at a rate of drying at 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch paper tube (manufactured by Nippon Paper Tube Industry Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.0 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. Table 2 shows the evaluation results of the obtained release film.

[Example 12]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 to have a PVA solid content of 100 so that the oxazoline compound solid content is 1 part by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and the resultant was wound up to 500 m on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flattening in paper tube strength measurement: 3.0 kN / 200 mm). A film roll was obtained. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. The evaluation results of Example 12 are shown in Table 2.

[Example 13]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 to have a PVA solid content of 100 so that the oxazoline compound solid content is 1 part by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.8 kN / 200 mm). A film roll was obtained. The film roll was treated at 60 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. The evaluation results of Example 13 are shown in Table 2.

[Example 14]
(ER-10) and (ER-10) solid content of 100 parts by mass, Epocros WS-500 is further mixed with VC-10 to have a PVA solid content of 100 so that the oxazoline compound solid content is 1 part by mass. It mixed so that it might become a mass part, and the coating agent was obtained.

This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-75", unit thickness 75 µm, manufactured by Unitika) with a clean coater (Okazaki Machinery Co., Ltd.). , 200 lines / inch, depth 40 μm). Thereafter, coating was performed at a drying rate of 140 ° C. for 90 seconds, and wound up to 500 inches on a 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (load at 3% flatness in paper tube strength measurement: 2.8 kN / 200 mm). A film roll was obtained. The film roll was treated at 80 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.19 μm. The evaluation results of Example 14 are shown in Table 2.
[Comparative Example 1]
With respect to (ER-30) and 100 parts by mass of the solid content of (ER-30), VC-10 was mixed so that the PVA solid content was 30 parts by mass to obtain a coating agent.

  This coating agent was applied to a corona-treated surface of a biaxially stretched polyester resin film ("Embret S-75", unit thickness 75 µm, manufactured by Unitika Co., Ltd.) with a clean coater (Okazaki Machine Industry Co., Ltd.). , 200 lines / inch, depth 40 μm), then coated at 140 ° C. for 90 seconds to dry, 6-inch pultruded FRP core (manufactured by AGC Matex Co., Ltd.) (3% flat in paper tube strength measurement) A 2000 m winding film roll was obtained at a load of 2.5 kN / 200 mm. The film roll was treated at 70 ° C. for 48 hours to obtain a release film. The thickness of the release layer of the obtained release film was 0.18 μm. The evaluation of Comparative Example 1 is shown in Table 3.

[Comparative Examples 2 to 10]
As shown in Table 3, the release of Comparative Examples 2 to 10 was performed in the same manner as in Example 2 except that the blending amounts of the oxazoline compound and PVA, the release layer thickness, the core strength load, and the aging temperature were changed. A film was obtained. Table 3 shows the evaluation of Comparative Examples 2 to 10.

In Comparative Example 5, the release layer was too thin and could not be measured with a contact-type film thickness meter.
As is clear from Table 2, in Examples 1 to 16, the release layer was suppressed from being transferred to the adherend, and a release film excellent in transparency was obtained.

In Comparative Example 1, since the oxazoline compound was not contained, the residual adhesion rate was as low as 40%, and the transfer of the release layer to the adherend could not be suppressed.
In Comparative Example 2, since the content of the oxazoline compound was excessive, the peel strength was as high as 4.0 N / cm, and it was not suitable for use as a release film.

In Comparative Example 3, since PVA was not contained, the residual adhesion rate was as low as 35%, and the transfer of the release layer to the adherend could not be suppressed.
In Comparative Example 4, since the PVA content was excessive, the peel strength was as high as 4.7 N / cm, which was not suitable for use as a release film.

In Comparative Example 5, the release layer was too thin (outside the measurement range of the contact-type film thickness meter), so the peel strength was as high as 4.7 N / cm, which was not suitable for use as a release film. It was.
In Comparative Example 6, since the release layer was excessively thick, the haze of the release film was as high as 12.0%, and the transparency was severely lowered with respect to the base film.

In Comparative Example 7, since the load in the paper tube strength measurement was too small, the peel strength was as high as 4.1 N / cm, and it was not suitable for use as a release film.
In Comparative Example 8, since the load in the paper tube strength measurement was excessive, the peel strength was as high as 3.8 N / cm, and it was not suitable for use as a release film.

In Comparative Example 9, since the aging temperature was too low, the peel strength was as high as 4.0 N / cm, which was not suitable for use as a release film.
In Comparative Example 10, since the aging temperature was too high, the haze of the release film was as high as 12.0%, and the decrease in transparency with respect to the base film was severe.

Claims (3)

  A release film having a release layer having a thickness of 0.01 to 0.20 μm on a base film having a haze value of 0.1 to 10%, wherein the release layer is 100 masses of acid-modified polyolefin resin. Part, 1-50 mass parts of oxazoline compound, 5-1000 mass parts of polyvinyl alcohol, and the haze value is 1.5 times or less the haze value of the base film before providing the release layer, and the mold release A release film, wherein the peel strength between the layer and the adherend is 3.0 N / cm or less.   The film for mold release according to claim 1, wherein the acid-modified polyolefin resin has an acid modification ratio of 1 to 15% by mass. In producing the release film according to claim 1 or 2, after winding the release film on a take-up core having a load of 2 to 3 kN / 200 mm at the time of 3% flatness in the paper tube strength measurement, 60 A method for producing a release film, characterized by performing aging at -80 ° C.