JP6720600B2 - Release film - Google Patents

Description

The present invention relates to a release film, for example, in a production process including an adhesive coating step, a drying step, a release film laminating step, etc., in particular, it is necessary that the release layer does not easily fall off during the production step. The present invention relates to a release film that can be used for the intended use.

Release films based on polyester films are used in various applications from the viewpoints of mechanical strength, heat resistance, thermal dimensional stability, chemical resistance and economic efficiency.For example, optical clear adhesive used for touch panels. For manufacturing (OCA), for manufacturing LCD components such as polarizing plates/retarders used in liquid crystal displays (LCD), for manufacturing plasma display panel (PDP) components, for manufacturing organic electroluminescence (organic EL) components. For manufacturing various display components, medical adhesives such as poultices/patches, ceramic sheets, polyvinyl chloride sheets, carbon fiber molding processes, labels, adhesive tapes, decorative sheets, transfer tapes Industrial applications such as are exemplified.

In the process application of touch panel manufacturing, there is a manufacturing process in which a polyester film with a hard coat layer and a release film are bonded together via an adhesive layer, and during the processing process, a polyester film base constituting the release film is used. In some cases, it is necessary that the release layer does not easily fall off the material, and therefore a release film having improved adhesion between the release layer and the polyester film substrate is required. (Patent Documents 1 and 2)

On the other hand, by smoothing the surface of the polyester film and increasing the flatness, the traveling property of the release film is deteriorated, and during the processing step, the guide roll for delivery and the release film come into contact with each other, and the components derived from the release layer are delivered. There is a case where the release layer and the polyester film base material adhere to and accumulate on the work roll, so that the stability with time-dependent adhesion between the release layer and the polyester film base material is required more.

In LCD component manufacturing applications and PDP component manufacturing applications, peeling stability is required over a wide area with the recent increase in the size of panels, and more time-dependent adhesion stability between the release layer and the base material is required. It is like this.
Further, even in the case of adhesive film for medical use, the adhesive layer is peeled after being in contact with a drug for a long period of time and the adhesive portion directly contacts the skin of the human body, and therefore the stability of the release layer with time is required from the viewpoint of safety.

JP-A-4-292665 Japanese Patent No. 5797416

The object of the present invention was made in view of the above circumstances, and the problem to be solved is to improve the adhesion between the release layer and the polyester film substrate, and the mold release with good adhesion stability over time. To provide a film.

The present inventors, in view of the above circumstances, as a result of diligent studies, by using a laminated polyester film having a specific configuration, it was found that the adhesion performance with the release layer for a long period of time can be greatly improved from the conventional technique, The invention was completed.

That is, the gist of the present invention is a release film having a coating layer on at least one surface of a polyester film and having a release layer on the coating layer, wherein the coating layer contains at least a condensed polycyclic aromatic structure. And a copolymerized polyester resin having an acid component having an aliphatic acid component and a polyester resin having an aliphatic acid component.

According to the above configuration of the present invention, it is possible to obtain a release film that can satisfy the adhesiveness with time to the release layer for a long period of time, which has been a problem of the prior art. For example, for touch panel production, liquid crystal polarizing plate production. It is suitable for various optical applications.

The release film of the present invention is a release film having a coating layer on at least one surface of a polyester film and having a release layer on the coating layer, wherein the coating layer contains at least a condensed polycyclic aromatic structure. It is characterized in that it contains a copolymerized polyester resin having an acid component having an acid and an aliphatic acid component. This feature is a technical feature common to the inventions according to claims 1 to 3.

Hereinafter, the present invention, its constituent elements, and preferable modes for carrying out the present invention will be described in detail.

The polyester in the polyester film used in the release film of the present invention is preferably one obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol, and preferably one aromatic dicarboxylic acid and one aliphatic glycol. And a copolymerized polyester obtained by copolymerizing one or more other components. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol and 1,4-cyclohexanedimethanol. Polyethylene terephthalate etc. are illustrated as a typical polyester. On the other hand, examples of the dicarboxylic acid used as the component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and the like, and the glycol component includes ethylene glycol, diethylene glycol, Examples include propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like. An oxycarboxylic acid such as p-oxybenzoic acid can also be used. Further, it may be a polyester obtained by copolymerizing other acid component or glycol component, and if necessary, a conventionally known coloring agent (dye/pigment), ultraviolet absorber, antioxidant, antistatic agent, conductive agent, heat It may contain various functionalizing components such as stabilizers and lubricants and additives.

Further, in the polyester film constituting the release film in the present invention, due to thermal history during film processing, etc., in order to reduce the amount of the oligomer contained in the film precipitated/crystallized on the surface of the film, It is also possible to use a low-oligomerized polyester for the outermost layer of the multilayer structure film. As a method for reducing the amount of oligomer in the polyester, for example, a solid phase polymerization method or the like can be used.

The polyester film constituting the release film of the present invention may contain particles for the main purpose of imparting easy slipperiness, ensuring the running property of the film in each step, and preventing scratches from occurring. The type of particles to be blended is not particularly limited as long as it is a particle capable of imparting lubricity, and specific examples include, for example, silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, calcium phosphate. , Calcium fluoride, calcium oxalate, lithium fluoride, zeolite, magnesium phosphate, kaolin, talc, aluminum oxide, alumina, titanium oxide, molybdenum sulfide and the like. Further, the heat-resistant organic particles described in JP-B-59-5216 and JP-A-59-217755 may be used. Examples of other heat-resistant organic particles include thermosetting urea resin, thermosetting phenol resin, thermosetting epoxy resin, and benzoguanamine resin. Furthermore, during the polyester manufacturing process, it is also possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed.

On the other hand, the shape of the particles used is not particularly limited, and any of spherical, lumpy, rod-shaped, flattened, etc. may be used. Further, the hardness, specific gravity, color, etc. are not particularly limited. Two or more kinds of these particles may be used in combination, if necessary.

The particle size and content of the particles are selected according to the application and purpose of the film, but when used in optical film applications, the average particle size of the particles is usually 0.01 to 5 μm, preferably 0.01 to 2 μm. It is a range. If the average particle size is less than 0.01 μm, the particles may easily aggregate and the dispersibility may be insufficient. On the other hand, if the average particle size exceeds 5 μm, the surface roughness of the film may be too rough, and Problems may occur when various surface functional layers are applied in the process.

When used for optical film applications, the particle content is usually 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the content of particles is less than 0.001% by weight, the slipperiness of the film may be insufficient, while when it exceeds 5% by weight, the transparency of the film may be insufficient.

If there are no particles or if there are few particles, the transparency of the film will be high and a good film will be obtained, but handling may be difficult due to insufficient slip properties, so particles may be included in the knurling or coating layer. May need to be devised.

The method of adding particles to the polyester is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage of producing the polyester constituting each layer, but it is preferably added after the completion of the esterification or transesterification reaction.

Further, a method of blending a slurry of particles dispersed in ethylene glycol or water with a polyester raw material using a kneading extruder with a vent, or a method of blending dried particles and a polyester raw material using a kneading extruder. It is done by the method.

The polyester film constituting the laminated polyester film in the present invention may have a single-layer structure or a multi-layer structure, and besides the two-layer or three-layer structure, four layers or more may be used as long as the gist of the present invention is not exceeded. It may be a multi-layer, and is not particularly limited.

The laminated polyester film in the present invention may contain an ultraviolet absorber in the polyester film in order to improve the weather resistance of the film. The ultraviolet absorber is not particularly limited as long as it is a compound having an ultraviolet absorbing ability and can withstand the heat applied in the production process of the polyester film.

As the ultraviolet absorber, there are an organic ultraviolet absorber and an inorganic ultraviolet absorber, and the organic ultraviolet absorber is preferable from the viewpoint of transparency. The organic UV absorber is not particularly limited, and examples thereof include cyclic imino ester-based, benzotriazole-based, and benzophenone-based. From the viewpoint of durability, cyclic imino ester type and benzotriazole type are more preferable. It is also possible to use two or more kinds of ultraviolet absorbers in combination.

The thickness of the laminated polyester film constituting the release film in the present invention is not particularly limited as long as it can be formed into a film, but is usually 400 μm or less, preferably 5 to 250 μm, more preferably 12 To 200 μm.

The transparency of the laminated polyester film in the present invention is not particularly limited, but in the case of an optical film application requiring transparency, the haze of the entire film is preferably 1.8% or less, and 1.2% or less. Is more preferable.

The total light transmittance of the laminated polyester film of the present invention is not particularly limited, but in the case of an optical film application where transparency is required, it is preferably 80% or more, more preferably 85% or more.

Next, the release film in the present invention will be specifically described with respect to production examples of the polyester film, but the present invention is not limited to the following production examples. Can be adopted. That is, it is preferable to use the above-mentioned polyester raw material and obtain a non-stretched sheet by cooling and solidifying a molten sheet extruded from a die with a cooling roll. In this case, in order to improve the flatness of the sheet, it is preferable to enhance the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method and/or liquid application adhesion method is preferably adopted. Next, the unstretched sheet obtained is stretched biaxially. In that case, first, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120° C., preferably 80 to 110° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Then, it is stretched in a direction orthogonal to the stretching direction of the first stage, in which case the stretching temperature is usually 70 to 170° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. is there. Then, subsequently, heat treatment is carried out at a temperature of 180 to 270° C. under tension or under relaxation within 30% to obtain a biaxially oriented film. In the above stretching, it is possible to employ a method in which stretching in one direction is performed in two or more stages. In that case, it is preferable that the stretching ratio in each of the two directions be finally within the above range.

Further, the simultaneous biaxial stretching method can be adopted for the production of the polyester film in the present invention. In the simultaneous biaxial stretching method, the unstretched sheet is usually stretched and oriented in the machine direction (longitudinal direction) and the width direction (horizontal direction) simultaneously at 70 to 120°C, preferably 80 to 110°C in a temperature controlled state. The area draw ratio is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times. Then, subsequently, heat treatment is carried out at a temperature of 170 to 250° C. under tension or under relaxation within 30% to obtain a stretched and oriented film. Regarding the simultaneous biaxial stretching device that employs the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, and a linear drive method can be adopted.

Next, the formation of the coating layer provided on at least one surface of the polyester film constituting the release film of the present invention will be described. The coating layer constituting the release film in the present invention refers to a layer having easy adhesion. The coating layer may be provided by in-line coating, which is a treatment of the film surface during the stretching process of the polyester film, or may be off-line coating, which is applied to the once-produced film outside the system. Inline coating is preferably used because it can be applied at the same time as film formation and can be manufactured at low cost, and the thickness of the coating layer can be changed by the draw ratio.

The in-line coating is not limited to the following, but for example, in the sequential biaxial stretching, the coating treatment can be performed before the transverse stretching particularly after the longitudinal stretching. When the coating layer is provided on the polyester film by in-line coating, coating can be performed at the same time as film formation, and the coating layer can be treated at a high temperature, whereby a film suitable as a polyester film can be manufactured.

When the coating layer is provided by in-line coating, it is preferable to produce a laminated polyester film by coating the coating liquid on a polyester film using the above-mentioned series of compounds as an aqueous solution or dispersion. Further, within a range not impairing the gist of the present invention, a small amount of an organic solvent may be contained in the coating liquid for the purpose of improving dispersibility in water, improving film-forming property and the like. Only one type of organic solvent may be used, or two or more types may be appropriately used.

The organic solvent content of the coating liquid is preferably 10% by weight or less, more preferably 5% by weight or less.
Specific examples of organic solvents include aliphatic or alicyclic alcohols such as n-butyl alcohol, n-propyl alcohol, isopropyl alcohol, ethyl alcohol and methyl alcohol, glycols such as propylene glycol, ethylene glycol and diethylene glycol. , N-butyl cellosolve, ethyl cellosolve, methyl cellosolve, glycol derivatives such as propylene glycol monomethyl ether, ethers such as dioxane and tetrahydrofuran, esters such as ethyl acetate and amyl acetate, ketones such as methyl ethyl ketone and acetone, N-methylpyrrolidone And other amides.

Further, regardless of off-line coating or in-line coating, heat treatment and irradiation of active energy rays such as ultraviolet irradiation may be used together, if necessary.

Examples of the method for forming the coating layer include gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze coating, curtain coating, and impregnation. Conventionally known coating methods such as coat, kiss coat, spray coat, calendar coat and extrusion coat can be used. In addition, regarding the formation of various functional layers, it may be provided by in-line coating that processes the film surface during the film formation process of the polyester film substrate, and off-line coating that is applied outside the system on the film once manufactured is adopted. You may.

It is essential that the coating layer in the present invention contains at least a copolymerized polyester resin having an acid component having a condensed polycyclic aromatic structure and an aliphatic acid component.
In the present invention, the copolyester resin contained in the coating layer is defined as a copolymer having an acid component and an alcohol component as constituent components.

The chemical structure of the acid component having a condensed polycyclic aromatic structure in the present invention is not particularly limited, but it has a condensed polycyclic aromatic structure as exemplified by the following chemical formula 1 from the economical viewpoint. Preference is given to using compounds. Note that the category of the compound having a condensed polycyclic aromatic structure exemplified in the following formula also includes the category of compounds containing a hetero atom in any of the structures.

As a method for incorporating the condensed polycyclic aromatic compound into the polyester resin, for example, two or more hydroxyl groups are introduced into the condensed polycyclic aromatic compound as a substituent to form a diol component or a polyvalent hydroxyl group component, or a carboxyl group is used. There is a method of introducing two or more acid groups to prepare a dicarboxylic acid component or a polycarboxylic acid component.

In addition to a hydroxyl group and a carboxylic acid group, a condensed polycyclic aromatic group may be introduced with a substituent containing a sulfur element, an aromatic substituent such as a phenyl group, a halogen element group, and the like, and coating property and adhesion. From the viewpoint of properties, a substituent such as an alkyl group, an ester group or an amide group may be introduced.

From the viewpoint of economic efficiency and adhesion to the release layer, a compound having a naphthalene ring structure is preferable as the condensed polycyclic aromatic contained in the copolyester resin in the coating layer, and a naphthalene ring structure is used as a polyester constituent component. The incorporated resin is preferably used. Typical examples of the naphthalene ring structure include 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid.

The chemical structure of the aliphatic acid component in the invention is not particularly limited, but it is preferable to use an aliphatic acid component having 12 or less carbon atoms from the viewpoint of adhesion to the release layer, and the number of carbon atoms as the polyester constituent component. A resin incorporating 12 or less aliphatic acid components is preferably used.
Typical examples of the aliphatic acid component having 12 or less carbon atoms include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, and the like. Among these, the viewpoint of adhesiveness to the release layer. Therefore, the use of suberic acid, sebacic acid, dodecanedioic acid is preferable, and the use of sebacic acid is particularly preferable.

The copolymerized polyester resin in the coating layer in the present invention may contain an acid component having any other structure as long as it contains the acid component having the condensed polycyclic aromatic structure and the aliphatic acid component. Examples of typical other acid components include terephthalic acid, isophthalic acid, phthalic acid, 4,4-diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phenylindanedicarboxylic acid and dimer acid. can do. Two or more kinds of these components can be used. In addition to these components, unsaturated polybasic acids such as maleic acid, fumaric acid, itaconic acid and the like, and hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-(β-hydroxyethoxy)benzoic acid in a small proportion. Can be used. The ratio of the unsaturated polybasic acid component and the hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less.
Further, in order to facilitate water dispersion or water solubilization, it is preferable that at least one kind of component having a sulfonic acid group or a sulfonate group is contained in the copolyester resin.

Examples of these components include 5-sodium sulfoisophthalic acid, 5-ammonium sulfoisophthalic acid, 4-sodium sulfoisophthalic acid, 4-methylammonium sulfoisophthalic acid, 2-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, Preferable examples include sulfonic acid alkali metal salt-based compounds such as 4-potassium sulfoisophthalic acid, 2-potassium sulfoisophthalic acid, and sodium sulfosuccinic acid, or sulfonic acid amine salt-based compounds.

The content ratio of the acid component having a condensed polycyclic aromatic structure of the copolyester resin of the present invention and the component having a sulfonic acid or a sulfo group is not particularly limited, but the viewpoint of adhesion to the release layer Therefore, the molar ratio of the acid component having the condensed polycyclic aromatic structure is preferably 1.5 or more of the molar ratio of the component having a sulfonic acid or a sulfo group.

Next, the chemical structure of the alcohol component in the copolyester resin of the present invention is not particularly limited, but from the viewpoint of adhesion to the release layer, it is preferable to use an alcohol component having 12 or less carbon atoms, and polyester composition. A resin incorporating an alcohol component having 12 or less carbon atoms as a component is preferably used.
Typical alcohol components having 12 or less carbon atoms include ethylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, Examples thereof include xylylene glycol, dimethylolpropionic acid, glycerin, and trimethylolpropane, and these can be used in combination of two or more. Further, in the present invention, poly(ethyleneoxy)glycol is interpreted as a complex of an alcohol component having 2 carbon atoms, and poly(tetramethyleneoxy)glycol is interpreted as a complex of an alcohol component having 4 carbon atoms and falls within the scope of the present invention. Including.
In the present invention, the inclusion of ethylene glycol, diethylene glycol, and 1,6-hexanediol components is particularly preferred from the viewpoint of adhesion to the release layer.

When ethylene glycol and diethylene glycol are used as the alcohol component of the copolyester resin in the present invention, the component content ratio is not particularly limited, but from the viewpoint of adhesion with the release layer, the ethylene glycol molar ratio is diethylene glycol. It is preferable that the molar ratio is 3 or more.

The content of the copolymerized polyester resin having an acid component having a condensed polycyclic aromatic structure and an aliphatic acid component in the coating layer is usually 50% by weight or more, preferably a content of the non-volatile components in the coating liquid. It is 70% by weight, more preferably 80% by weight, and further preferably 90% by weight or more. If it is out of this range, the easy adhesion performance to the release layer may be deteriorated.

In the present invention, for the purpose of improving the film-forming property of the coating film, the coating layer may contain one kind or two or more kinds of polymers other than the above-mentioned copolyester resin as long as the main purpose is not impaired. Examples include polyester resins, polyurethane resins, acrylic resins, vinyl resins such as polyvinyl alcohol, epoxy resins, polyether resins, amide resins, and the like.
Further, these skeleton structures may have a substantially composite structure by copolymerization, and examples of the polymer having the composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft. Examples thereof include polyester and vinyl resin-grafted polyurethane.

Further, the coating layer may contain a cross-linking agent for the purpose of improving the film-forming property as long as the gist of the present invention is not impaired. As the crosslinking agent, various known resins can be used, for example, melamine compounds, guanamine-based, alkylamide-based, polyamide-based compounds, glyoxal-based, carbodiimide compounds, epoxy compounds, oxazoline compounds, aziridine compounds, isocyanate compounds, silanes. Examples thereof include coupling agents, dialcohol aluminate-based coupling agents, dialdehyde compounds, zircoaluminate-based coupling agents, peroxides, heat- or photoreactive vinyl compounds, and photosensitive resins. In the present invention, it is preferable to use a silane coupling agent from the viewpoint of easy adhesion with silicone.

The silane coupling agent is an alkoxysilane compound represented by the general formula of Y—Si(OR ² ) ₃ and containing ^two reactive group sites Y and alkoxyl group sites OR ^{2 in} the molecule. However, any silane coupling agent that is synthetically possible can be used in the present invention as long as it is a silane compound containing a reactive group moiety Y and an alkoxyl group moiety OR ² in the molecule. is there.

The reactive group moiety Y of the silane coupling agent contains a reactive group such as a double bond group, an amino group, an epoxy group, a mercapto group, a sulfide group, an isocyanate group, a ureido group, a chloropropyl group and a hydroxyl group. Any structure can be used as the reactive group moiety Y as long as it has a structure.

In the present invention, of the silane coupling agents, it is preferable to use a silane coupling agent having a structure containing an epoxy group, from the viewpoint of easy adhesion to silicone. The ratio of the silane coupling agent in the nonvolatile content of the coating liquid is preferably 1% by weight to 90% by weight, more preferably 3% by weight to 50% by weight, and further preferably 4% by weight to. It is in the range of 30% by weight.

The oxazoline compound is a compound having an oxazoline group in the molecule and a compound obtained as a result of the reaction of the oxazoline group. As the compound having an oxazoline group in the molecule, a polymer containing an oxazoline group is particularly preferable, and it can be prepared by polymerization of an addition-polymerizable oxazoline group-containing monomer alone or with another monomer. The addition-polymerizable oxazoline group-containing monomer includes 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like can be mentioned, and one kind or a mixture of two or more kinds thereof can be used. Among these, 2-isopropenyl-2-oxazoline is industrially easily available and suitable. The other monomer is not limited as long as it is a monomer copolymerizable with the addition-polymerizable oxazoline group-containing monomer, and examples thereof include alkyl (meth)acrylate (wherein the alkyl group is a methyl group, an ethyl group, an n-propyl group, an isopropyl group, (Meth)acrylic acid esters such as n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene Unsaturated carboxylic acids such as sulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); Unsaturated nitriles such as acrylonitrile, methacrylonitrile; (meth)acrylamide, N-alkyl( (Meth)acrylamide, N,N-dialkyl(meth)acrylamide, (as the alkyl group, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group Groups, cyclohexyl groups, etc.), unsaturated amides; vinyl acetates, such as vinyl acetate and vinyl propionate; vinyl ethers, such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; vinyl chloride, vinylidene chloride And halogen-containing α,β-unsaturated monomers such as vinyl fluoride; α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and one or more of these. Can be used.

The epoxy compound is a compound having an epoxy group in the molecule and a compound obtained as a result of the reaction of the epoxy group. Examples of the compound having an epoxy group in the molecule include condensates of epichlorohydrin and a hydroxyl group or amino group such as ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A. Polyepoxy compounds, diepoxy There are compounds, monoepoxy compounds, glycidylamine compounds and the like. Examples of the polyepoxy compound include sorbitol, polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl)isocyanate, glycerol polyglycidyl ether, trimethylol. Examples of the propane polyglycidyl ether and diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether. Examples of the ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, and monoepoxy compound include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and glycidyl amine compounds of N, N, N′, Examples thereof include N′,-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N-diglycidylamino)cyclohexane.

The melamine compound is a compound having a melamine skeleton in the compound. For example, an alkylolated melamine derivative, a compound obtained by reacting an alkylolated melamine derivative with an alcohol to partially or completely etherify, and a mixture thereof can be used. As the alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like are preferably used. Further, the melamine compound may be either a monomer or a dimer or higher polymer, or a mixture thereof. Further, a product obtained by co-condensing a part of melamine with urea or the like can be used, and a catalyst can be used to increase the reactivity of the melamine compound.

The isocyanate compound is a compound having an isocyanate derivative structure represented by isocyanate or blocked isocyanate. As the isocyanate, for example, aromatic isocyanate such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate and naphthalene diisocyanate, and aromatic ring such as α,α,α′,α′-tetramethylxylylene diisocyanate. Aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl isocyanate), isopropylidene dicyclohexyl diisocyanate, etc. Examples of the alicyclic isocyanate are as follows. In addition, polymers and derivatives of these isocyanates such as burettes, isocyanurates, uretdiones, and carbodiimide modified products are also included. These may be used alone or in combination of two or more. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferable than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.

When used in the state of blocked isocyanate, as the blocking agent, for example, oxime type, pyrazole type, alcohol type, alkylphenol type, phenol type, mercaptan type, acid amide type, acid imide type, imidazole type, urea type, amine Examples of the blocking agent include a system, an imine system, a bisulfite, an active methylene compound and the like. The blocking agents may be used alone or in combination of two or more.

The carbodiimide compound is a compound having one or more carbodiimide or carbodiimide derivative structures in the molecule, but a polycarbodiimide compound having two or more carbodiimide compounds in the molecule is more preferable for better adhesion.

The carbodiimide compound can be synthesized by a conventionally known technique, and a condensation reaction of a diisocyanate compound is generally used. The diisocyanate compound is not particularly limited, and any of aromatic series and aliphatic series can be used. Specifically, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexa Examples thereof include methylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate and dicyclohexylmethane diisocyanate.

The present invention may contain particles for the purpose of improving the stickiness and slipperiness of the coating layer. The average particle size is not particularly limited, but when used for optical applications, for example, from the viewpoint of transparency of the film, the range is preferably 1.0 μm or less, more preferably 0.5 μm or less, particularly preferably 0.2 μm. The range is as follows. Specific examples of the particles include silica, alumina, calcium carbonate, inert inorganic particles such as titanium dioxide, fine particles obtained from polystyrene resin, polyacrylic resin, polyvinyl resin, or organic particles represented by cross-linked particles thereof. Are listed.

Further, within the range not impairing the gist of the present invention, the coating layer may optionally contain a surfactant, a defoaming agent, a coating property improver, a release agent, a thickener, an organic lubricant, an antistatic agent, and a conductive agent. Agents, light absorbers such as ultraviolet rays, antioxidants, foaming agents, dyes, pigments and the like may be contained.

The components in the coating layer can be analyzed by, for example, TOF-SIMS, ESCA, fluorescent X-ray analysis, or the like.

The thickness of the coating layer provided on the polyester film in the present invention is usually 0.01 to 3 g/m ² , preferably 0.02 to 1 g/m ² , and more preferably 0 when viewed as a final coating. The range is 0.03 to 0.3 g/m ² . If it is 0.01 g/m ² , sufficient performance may not be obtained in terms of easy adhesion to the release layer, and if the coating layer exceeds 3 g/m ² , the appearance and transparency may be deteriorated and the film may be blocked. It is easy to increase the cost due to the decrease of the line speed. The coating amount was calculated from the liquid weight per application time (before drying), the non-volatile content of the coating liquid, the coating width, the stretching ratio, the line speed, and the like.

The polyester film used in the present invention may be subjected to various surface treatments separately from the coating layer. Specifically, it can be applied before forming the coating layer on the polyester film, or can be applied on the polyester film on the back side of the coating layer. Conventionally known techniques can be used for various surface treatments and various functional layers. Examples of the surface treatment include corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, microwave treatment, glow discharge treatment, active plasma treatment, laser treatment and the like.

In the polyester film used in the present invention, various functional layers may be provided on the back side of the coating layer in addition to the coating layer. Examples of the various functional layers include an easy-adhesion layer, an antistatic layer, and a release layer. Layers, bleed-out component sealing layers, refractive index adjusting layers, light absorbing layers, light transmittance improving layers, antifogging layers, barrier coat layers, hard coat layers, adhesive layers and layers that combine these functionalities. be able to. The functional layer may be a single layer, but may have a structure of two or more layers.

For example, when the hard coat layer is provided on the back surface side of the release film on which the coating layer of the polyester base material is provided, the refractive index of the refractive index adjustment easy-adhesion layer adjacent to the film should be 1.57 to 1.63. It is more preferable because the interface reflection between the film base material and the easy-adhesion layer can be reduced, the interference with the light of the interface reflection on the surface of the hard coat layer can be suppressed, and rainbow unevenness on the film surface can be suppressed. As a method of adjusting the refractive index, it can be carried out by appropriately adjusting the ratio of an oxide sol having a relatively high refractive index such as zirconium oxide, titanium oxide, tin oxide sol, and cerium oxide sol to a binder resin, and applying the resin. Further, as the easy-adhesion layer component, various polymers such as polyester, polyamide, polyurethane, polyether, vinyl-based copolymer, butadiene-based copolymer, acrylic-based copolymer, vinylidene-based copolymer, and epoxy-based copolymer And various cross-linking agents such as melamine-based, benzoguanamine-based, urea-based amino resins, carbodiimide, isocyanate-based, oxazoline-based, epoxy-based, glyoxal-based, and silane coupling agents, surfactants, defoaming agents, coating improvers Examples thereof include thickeners, organic lubricants, organic particles, inorganic particles, antioxidants, light absorbers such as ultraviolet rays, foaming agents, dyes, and additives such as pigments.

The release layer provided on the coating layer constituting the release film in the present invention will be described below.
The release film used in the present invention is not particularly limited in the constitutional components of the release layer as long as it has good release performance at the time of peeling from the adhesive layer, but from the viewpoint of obtaining good release performance. Therefore, the release layer constituting the release film preferably contains a curable silicone resin in order to improve the releasability. A type containing a curable silicone resin as a main component may be used, or a modified silicone type obtained by graft polymerization with an organic resin such as urethane resin, epoxy resin, or alkyd resin may be used. Further, when the adhesive layer is a silicone adhesive or the like, it is preferable to contain a fluorosilicone resin or the like.

As the type of curable silicone resin, any existing curing reaction type can be used, such as a thermosetting type such as an addition type or a condensation type, an electron beam curing type such as an ultraviolet ray curing type, or a plurality of types of curable types. A silicone resin may be used in combination. Furthermore, the coating form of the curable silicone resin for forming the release layer is not particularly limited, and may be a form dissolved in an organic solvent, an aqueous emulsion form, or a solventless form.

The type of silicone resin used in the present invention is not limited, but in the present invention, use of a curable silicone resin containing an alkenyl group is preferable from the viewpoint of excellent release characteristics such as light release characteristics.
Examples of the curable silicone resin containing an alkenyl group include diorganopolysiloxanes represented by the following general formula (1).
_{R (3-a) X a} SiO- (RXSiO) m - (R 2 SiO) n -SiX a R (3-a) ... (1)

In the general formula (1), R is a monovalent hydrocarbon group having 1 to 10 carbon atoms, and X is an alkenyl group-containing organic group. a is an integer of 0 to 3, preferably 1, and m is 0 or more, but when a=0, m is 2 or more, and m and n are numbers satisfying 100≦m+n≦20000 respectively. Also, the above formula does not mean a block copolymer. R is a monovalent hydrocarbon group having 1 to 10 carbon atoms, specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a cycloalkyl group such as a cyclohexyl group, a phenyl group, a tolyl group. Examples thereof include allyl groups and the like, with methyl and phenyl groups being particularly preferred. X is preferably an alkenyl group-containing organic group having 2 to 10 carbon atoms, specifically, vinyl group, allyl group, hexenyl group, octenyl group, acryloylpropyl group, acryloylmethyl group, methacryloylpropyl group, cyclohexenylethyl group. Examples thereof include a vinyl group and a vinyloxypropyl group, with a vinyl group and a hexenyl group being particularly preferable. Specifically, a dimethylsiloxane-methylhexenylsiloxane copolymer capped with trimethylsiloxy groups at both ends of the molecular chain (96 mol% of dimethylsiloxane units, 4 mol% of methylhexenylsiloxane units, dimethylsiloxane with dimethylvinylsiloxy groups blocked at both ends of the molecular chain) Methylhexenyl siloxane copolymer (dimethyl siloxane unit 97 mol %, methyl hexenyl siloxane unit 3 mol %), dimethyl hexenyl siloxy group-capped dimethyl siloxane/methyl hexenyl siloxane copolymer at both molecular chain ends (dimethyl siloxane unit 95 mol %, methyl Hexenyl siloxane units (5 mol %).

Next, as a polyorganosiloxane containing a SiH group, which is necessary for forming a stronger silicone release layer by reacting with a curable silicone resin containing an alkenyl group, hydrogen bonded to a silicon atom in one molecule is used as the polyorganosiloxane containing a SiH group. Organohydrogenpolysiloxanes having at least 2, preferably 3 or more atoms, which may be linear, branched, or cyclic, such as compounds represented by the following general formula (2) are listed. However, it is not limited to these.
^{_{H b R 1 (3-b}} ) SiO- (HR 1 SiO) x - (R 1 2 SiO) y -SiR 1 (3-b) H b ... (2)

In the general formula (2), R ¹ is a monovalent hydrocarbon group having 1 to 6 carbon atoms and containing no aliphatic unsaturated bond. b is an integer of 0 to 3, and x and y are integers. Specific examples include methyl chain polymethyl siloxane endcapped with trimethylsiloxy groups at both ends of the molecular chain, dimethylsiloxane-methylhydrogensiloxane co-polymers capped with trimethylsiloxy group at both ends of the molecular chain, dimethyl hydrogensiloxy group capped with both ends of the molecular chain. Hydrogen polysiloxane, a dimethylhydrogensiloxy group-capped dimethylsiloxane/methylhydrogensiloxane copolymer with both ends of the molecular chain blocked.

Next, specific examples of various types of commercially available silicone resins that can be used in the present invention include KS-774, KS-775, KS-778, and KS- manufactured by Shin-Etsu Chemical Co., Ltd. 779H, KS-847H, KS-856, X-62-2422, X-62-2461, X-62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A/B, X-62-7052, X-62-7028A/B, X-62-7619, X-62-7213, X-41-3035, Momentive Performance Materials As a product, YSR-3022, TPR-6700, TPR-6720, TPR-6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605, Toray Dow Corning (shares). ), SRX357, SRX211, SD7220, SD7292, LTC750A, LTC760A, LTC303E, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210,. Among the DEHESIVE series manufactured by Asahi Kasei Wacker Silicone Co., Ltd., DEHESIVE 636, 919, 920, 921, 924, 929 and the like are exemplified.

In the release layer of the present invention, it is preferable to use a platinum-based catalyst that promotes the addition-type reaction in order to make the coating layer clean and tough. As this component, chloroplatinic acid, an alcohol solution of chloroplatinic acid, a complex of chloroplatinic acid and an olefin, a platinum compound such as a complex of chloroplatinic acid and an alkenylsiloxane, platinum black, platinum-supported silica, platinum-supported activated carbon. Is exemplified. The platinum-based catalyst content in the coating layer is 0.3 to 3.0% by weight, preferably 0.5 to 2.0% by weight. When the platinum-based catalyst content in the coating layer is lower than 0.3% by weight, the peeling force may be defective, or the curing reaction in the coating layer may be insufficient, which may cause problems such as deterioration in surface condition. On the other hand, if the platinum-based catalyst content in the coating layer exceeds 3.0% by weight, it may be costly, the reactivity may be increased, and process defects such as gel foreign matter may occur.

In addition, since the addition type reaction is extremely reactive, acetylene alcohol may be added as an unreactable inhibitor in some cases. The component is an organic compound having a carbon-carbon triple bond and a hydroxyl group, preferably 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyne-3-ol and phenylbutyrate. It is a compound selected from the group consisting of norls.

In the present invention, a catalyst may be used in combination in the release layer constituting the release film for the purpose of promoting the hydrolysis/condensation reaction. Specific examples of the catalyst, acetic acid, butyric acid, maleic acid, organic acids such as citric acid, hydrochloric acid, nitric acid, phosphoric acid, inorganic acids such as sulfuric acid, basic compounds such as triethylamine, tetrabutyl titanate, dibutyltin dilaurate, Organic metal salts such as dibutyltin diacetate, dibutyltin dioctate, dibutyltin diolate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis(triethoxysiloxy)tin, dibutyltin benzyl malate, KF, NH4 F Fluorine element-containing compounds such as The above catalysts may be used alone or in combination of two or more. Among them, organic metal salts are preferable in that the coating film durability is particularly good.

In the present invention, various release control agents may be used in combination in order to adjust the releasability of the release layer. When the release force is to be heavy-released, generally, an appropriate content of organopolysiloxane resin, silica particles, silicone species having a heavy release force, etc. in the release layer is adjusted to obtain a desired release force. Specific examples of commercially available heavy release agents include Shin-Etsu Chemical Co., Ltd. KS-3800, X-92-183, Toray Dow Corning Co., Ltd. SDY7292, BY24-843, BY24-4980. To be done. When the release force is to be lightly released, various low molecular weight siloxanes are selected and the release layer is adjusted to have an appropriate content so that the siloxane transfer component exhibits release performance. Examples of the low molecular weight siloxane compound include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and the like. Other compounds of the former low-molecular cyclic siloxane include dimethylsiloxy oligomers capped with trimethylsiloxy groups at both ends of the molecular chain; dimethylsiloxane oligomers capped with dimethylhydroxysiloxy groups at both ends of the molecular chain, and the compounds are mixed as necessary. You may use it. These low-molecular-weight siloxane compounds are usually contained in the silicone resin as a transfer component in an amount of 0.1 to 15.0% by weight, preferably 0.1 to 10.0% by weight, and more preferably 0.1 to 5% by weight. It is possible to achieve the desired light peeling. If the value is less than 0.1% by weight, the releasability is not exhibited because the amount of the migratory component is small, and if the content of the low-molecular siloxane is more than 15.0% by weight, the migratory component is Excessive precipitation causes process contamination.

In addition, an organic silicon compound represented by the following general formula (3) is used in combination in the release layer constituting the release film in the present invention in order to improve the coating adhesion between the release layer and the polyester film. Preferably.
Si(X) _d (Y) _e (R ¹ ) _f (3)
[In the above formula, X is an organic group having at least one selected from an epoxy group, a mercapto group, a (meth)acryloyl group, an alkenyl group, a haloalkyl group and an amino group, R ¹ is a monovalent hydrocarbon group, and It has 1 to 10 carbon atoms, Y is a hydrolyzable group, d is an integer of 1 or 2, e is an integer of 2 or 3, f is an integer of 0 or 1, and d+e+f=4. ]

The organosilicon compound represented by the general formula (3) has two hydrolyzable groups Y capable of forming a siloxane bond by a hydrolysis/condensation reaction (D unit source) or three (T unit). Source) can be used.

In the general formula (3), the monovalent hydrocarbon group R1 has 1 to 10 carbon atoms, and a methyl group, an ethyl group and a propyl group are particularly preferable.

Examples of the hydrolyzable group Y in the general formula (3) include the following. That is, a methoxy group, an ethoxy group, a butoxy group, an isopropenoxy group, an acetoxy group, a butanoxime group, an amino group and the like. These hydrolyzable groups may be used alone or in combination. The application of a methoxy group or an ethoxy group is particularly preferable because it can impart good storage stability to the coating material and has suitable hydrolyzability.

In the present invention, as specific examples of the organosilicon compound contained in the release layer, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3, 4-epoxycyclohexyl)ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 5-hexenyltrimethoxy Examples thereof include silane, p-styryltrimethoxysilane, trifluoropropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiisopropenoxysilane and the like.

The content of the organosilicon compound is preferably 0.5 to 5.0 parts by weight, and more preferably 0.5 to 2.0 parts by weight, based on 100 parts by weight of the curable silicone resin. If the range is less than 0.5 parts by weight, it may be difficult to secure the desired adhesion, while if it exceeds 5.0 parts by weight, the adhesion to the mating resin layer to be bonded is too strong. However, in a situation where peeling is originally required, there may be a problem such as difficulty in peeling.

Furthermore, in the range not impairing the gist of the present invention, the coating solution for forming the release layer may have an antifoaming agent, a coating property improving agent, a thickener, an inorganic organic particle, an organic lubricant, if necessary. An antistatic agent, a conductive agent, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, a pigment and the like may be contained.

The release layer is formed by coating the film with a coating liquid, and even if it is provided by in-line coating performed in the film manufacturing process, it is also applied to the film once manufactured outside the system, so-called offline. A coating may be adopted.

In the present invention, as a method for providing the release layer on the coating layer of the polyester film, reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, etc., the conventionally known coating method described above is used. be able to. Regarding the coating method, there is an example in "Coating method" published by Maki Shoten Yuji Harasaki in 1979.

In the present invention, the curing conditions for forming the release layer on the coating layer of the polyester film are not particularly limited, and when the release layer is provided by off-line coating, it is usually at 80° C. or higher for 10 seconds or longer. The heat treatment is preferably performed at 100 to 200° C. for 3 to 40 seconds, more preferably 120 to 180° C. for 3 to 40 seconds. If necessary, heat treatment and irradiation with active energy rays such as ultraviolet irradiation may be used in combination. A known device and energy source can be used as an energy source for curing by irradiation with active energy rays. The coating amount (after drying) of the release layer is usually 0.005 to 5 g/m ² , preferably 0.005 to 1 g/m ² , and more preferably 0.005 to 0. It is in the range of 1 g/m ² . When the coating amount (after drying) is less than 0.005 g/m ² , the coating property may lack stability and it may be difficult to obtain a uniform coating film. On the other hand, when the coating thickness is more than 5 g/m ² , the coating adhesion and curability of the release layer itself may be deteriorated. The coating amount was calculated from the liquid weight per application time (before drying), the non-volatile content of the coating liquid, the coating width, the draw ratio, the line speed and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples and Production Examples, but the present invention is not limited to the following Examples, Comparative Examples and Production Examples as long as the gist thereof is not exceeded. .. The evaluation methods and sample processing methods in Examples, Comparative Examples and Production Examples are as follows.

(1) Method for Measuring Intrinsic Viscosity of Polyester 1 g of polyester was precisely weighed, 100 ml of a mixed solvent of phenol/tetrachloroethane=50/50 (weight ratio) was added and dissolved, and the viscosity was measured at 30°C.

(2) Method for measuring average particle size (d50: μm) Accumulation (weight basis) 50% in equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) The value of was taken as the average particle size.

(3) Evaluation of release force with time of release film After sticking one side of a double-sided adhesive tape (“No. 502” manufactured by Nitto Denko) on the release layer surface of the release film left under the following conditions 1 to 5, After cutting into a size of 50 mm×300 mm, the peeling force after standing for 1 hour at room temperature is measured. For the peeling force measurement, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180° peeling was performed under the condition of a pulling speed of 300 mm/min. Further, the time-dependent peeling force was evaluated according to the following criteria.
"conditions"
Condition 1: Immediately after the release film is prepared Condition 2: The release film is left in a constant temperature and humidity chamber in an atmosphere of 23°C x 50% RH for 1 month Condition 3: The release film is placed in an atmosphere of 23°C x 50% RH Left in constant temperature and humidity chamber for 2 months Condition 4: Release film left in constant temperature and humidity chamber at 23°C x 50% RH atmosphere for 3 months Condition 5: Release film in 23°C x 50% RH atmosphere Leave for 4 months in the lower temperature and humidity chamber <Evaluation criteria>
◯: Peeling force is 25 mN/cm or less for 4 months after the release film is formed. X: Peeling force exceeds 25 mN/cm for 4 months after the release film is formed.

(4) Evaluation of coating film adhesion over time of release film (substitution evaluation of practical properties)
After the release layer surface of the release film left to stand under the following conditions 1 to 5 was rubbed with the tentacles 5 times, the degree of falling of the release layer was determined according to the following determination criteria.
"conditions"
Condition 1: Immediately after the release film is prepared Condition 2: The release film is left in a constant temperature and humidity chamber in an atmosphere of 23°C x 50% RH for 1 month Condition 3: The release film is placed in an atmosphere of 23°C x 50% RH Left in constant temperature and humidity chamber for 2 months Condition 4: Release film left in constant temperature and humidity chamber at 23°C x 50% RH atmosphere for 3 months Condition 5: Release film in 23°C x 50% RH atmosphere Leave in the constant temperature and humidity tank below for 4 months <<Criteria>>
○: No release layer was confirmed to have fallen off (no problem in practical use)
×: The release layer was confirmed to have fallen off (at a practically problematic level)

The raw materials of the polyester film used in the following production examples are as follows.
<Method for producing polyester (I)>
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, 0.09 parts by weight of magnesium acetate/tetrahydrate as a catalyst was placed in a reactor, the reaction start temperature was set to 150° C., and methanol was gradually distilled off. The reaction temperature was raised to 230° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part by weight of ethyl acid phosphate to the reaction mixture, 0.04 part by weight of antimony trioxide was added and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually raised from 230°C to 280°C. On the other hand, the pressure was gradually reduced from atmospheric pressure to finally 0.3 mmHg. After the reaction was started, the reaction was stopped at a time point corresponding to an intrinsic viscosity of 0.63 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure. The intrinsic viscosity of the obtained polyester (I) was 0.63.

<Method for producing polyester (II)>
In the method for producing polyester (I), after adding 0.04 part by weight of ethyl acid phosphate, 0.3 part by weight of silica particles having an average particle diameter of 1.6 μm dispersed in ethylene glycol and 0.04 part of antimony trioxide are added. Polyester (II) was obtained in the same manner as in the production method of polyester (I) except that the polycondensation reaction was stopped at the time point corresponding to an intrinsic viscosity of 0.65 by adding parts by weight. The intrinsic viscosity of the obtained polyester (II) was 0.65.

The following was used as the composition of the coating layer formed on the surface of the polyester film.

(A1) Copolyester Resin Having Acid Component Having Fused Polycyclic Aromatic Structure and Aliphatic Acid Component: Water Dispersion of Polyester Resin Copolymerized by Following Composition Monomer composition: (acid component) 2,6-naphthalene Dicarboxylic acid/sebacic acid/5-sodium sulfoisophthalic acid/(diol component) ethylene glycol/hexanediol/diethylene glycol=37/11/3//27/17/5 (mol%)
(A2) Polyester resin having condensed polycyclic aromatic: Water dispersion of polyester resin copolymerized with the following composition Monomer composition: (acid component) 2,6-naphthalenedicarboxylic acid/5-sodium sulfoisophthalic acid// (Diol component) ethylene glycol/diethylene glycol = 32/19//37/12 (mol%)
(A3) Acrylic resin: Aqueous dispersion of acrylic resin polymerized with the following composition of ethyl acrylate/n-butyl acrylate/methyl methacrylate/N-methylol acrylamide/acrylic acid=65/21/10/2/2 (% by weight) Emulsion polymer (emulsifier: anionic surfactant)
(A4) Polyester resin Aqueous dispersion of polyester resin copolymerized with the following composition Monomer composition: (acid component) terephthalic acid/isophthalic acid/5-sodium sulfoisophthalic acid//(diol component) ethylene glycol/1,4- Butanediol/diethylene glycol=56/40/4//70/20/10 (mol%)
(B1) 3-glycidoxypropyltrimethoxysilane (B2) epoxy compound: polyglycerol polyglycidyl ether (B3) hexamethoxymethylol melamine (B4) active methylene block polyisocyanate compound active methylene block polyisocyanate compound synthesized by the following method ..
1000 parts by weight of hexamethylene diisocyanate were stirred at 60° C., and 0.1 part by weight of tetramethylammonium capryate was added as a catalyst. After 4 hours, 0.2 part by weight of phosphoric acid was added to stop the reaction to obtain an isocyanurate type polyisocyanate composition. 100 parts by weight of the obtained isocyanurate type polyisocyanate composition, 42.3 parts by weight of methoxypolyethylene glycol having a number average molecular weight of 400, and 29.5 parts by weight of propylene glycol monomethyl ether acetate were charged, and the mixture was kept at 80° C. for 7 hours. Thereafter, the reaction solution temperature was maintained at 60° C., 35.8 parts by weight of methyl isobutanoyl acetate, 32.2 parts by weight of diethyl malonate, and 0.88 parts by weight of a 28% methanol solution of sodium methoxide were added, and maintained for 4 hours. .. A blocked polyisocyanate obtained by adding 58.9 parts by weight of n-butanol, maintaining the reaction solution temperature at 80° C. for 2 hours, and then adding 0.86 parts by weight of 2-ethylhexyl acid phosphate.
(B5) Carbodiimide compound: Polycarbodiimide compound Carbodilite (carbodiimide equivalent=600, manufactured by Nisshinbo Co., Ltd.)
(B6) Oxazoline compound: Acrylic polymer epocros having an oxazoline group and a polyalkylene oxide chain (oxazoline group amount=4.5 mmol/g, manufactured by Nippon Shokubai Co., Ltd.)
(C1) particles: silica particles having an average particle size of 0.07 μm

[Examples 1 to 10], [Comparative examples 1 to 5]
A mixed raw material obtained by mixing polyesters (I) and (II) at a ratio of 90% and 10%, respectively, was used as a raw material for the outermost layer (surface layer), and polyester (I) was used as a raw material for the intermediate layer. And melted at 285° C. respectively, and then coextruded on a cooling roll set at 40° C. in a layer structure of 2 types and 3 layers (surface layer/intermediate layer/surface layer), cooled and solidified to form an unstretched sheet. Obtained. Then, the film was stretched 3.4 times in the machine direction at a film temperature of 85° C. by using the difference in roll peripheral speed, and then the coating liquid having the coating composition shown in Table 1 below was applied to give a predetermined amount (after drying). After coating on one side of the film, it was introduced into a tenter, stretched in the transverse direction by 4.3 times at 120° C., and heat-treated at 225° C., and then a coating layer having a thickness of 38 μm (surface layer 5 μm, intermediate layer 28 μm) The laminated polyester film provided was obtained.
The coating liquid of the following <release agent composition A> was applied to the laminated polyester film of Example 1 off-line on the coating layer of the obtained laminated polyester film, and the other Examples 2 to 10 and Comparative Example 1 The coating liquid of the following <release agent composition B> was applied to the laminated polyester films of Nos. 5 to 5 by the reverse gravure coating method so that the applied amount (after drying) was 0.1 g/m ² , and the coating liquid was applied at 180°C. After heat treatment for 10 seconds, a release film was obtained.
Table 2 shows the results of evaluation of the peel strength with time of the obtained release film, and Table 3 shows the results of evaluation of the coating film adhesion with time.

<Release agent composition A>
Hexenyl group-containing addition type curable silicone resin (LTC303E, manufactured by Toray Dow Corning): 20 parts by weight octamethylcyclotetrasiloxane: 0.5 parts by weight Addition type platinum catalyst (SRX212, manufactured by Toray Dow Corning): 0.16 parts by weight Part MEK/toluene/n-heptane mixed solvent (mixing ratio 1:1:1)

<Release agent composition B>
Addition type cured silicone resin (KS-847H, manufactured by Shin-Etsu Chemical Co., Ltd.): 20 parts by weight Addition-type platinum catalyst (CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.): 0.2 parts by weight MEK/toluene mixed solvent (Mixing ratio 1:1)

The release films of Examples 1 to 5 maintain good release force and coating adhesion even after 4 months, and are practically useful release films that can be used in various applications and usage situations. It was Among them, the release film of Example 1 was lightly peeled off as compared with the other Examples, and was particularly practical.
Further, the release films of Examples 6 to 7 exhibit good peeling force and coating adhesion even after 2 months or more, and are release films which are practically problem-free even when used for a relatively long period of time. there were.
Further, since the release films of Examples 8 to 10 exhibited good peeling force and coating adhesion even after 1 month, they are release films which are practically problem-free when used in a relatively short period. there were.
On the other hand, the release films of Comparative Examples 1 to 5 had no problem with the peeling force over time, but the adhesion of the coating film over time was poor, and problems could occur even in cases such as long-term transport. Met. In particular, the release film of Comparative Example 5 was significantly deteriorated.

INDUSTRIAL APPLICABILITY The present invention can be suitably used as a release film for optical applications such as touch panel production and liquid crystal polarizing plate production.

Claims (7)

A release film having a coating layer on at least one surface of a polyester film, and a release layer on the coating layer, wherein the coating layer contains at least an acid component having a condensed polycyclic aromatic structure and an aliphatic acid. A release film comprising a copolyester resin having a component and a silane coupling agent . A release film having a coating layer on at least one surface of a polyester film, and a release layer on the coating layer, wherein the coating layer contains at least an acid component having a condensed polycyclic aromatic structure and an aliphatic acid. A release film comprising a copolyester resin having a component and an isocyanate compound . A release film having a coating layer on at least one surface of a polyester film, and a release layer on the coating layer, wherein the coating layer contains at least an acid component having a condensed polycyclic aromatic structure and an aliphatic acid. A release film comprising a copolyester resin having a component and an oxazoline compound . A release film having a coating layer on at least one surface of a polyester film, and a release layer on the coating layer, wherein the coating layer contains at least an acid component having a condensed polycyclic aromatic structure and an aliphatic acid. A release film comprising a copolyester resin having a component and a carbodiimide compound . The release film according to claim 1, further comprising particles in the coating layer. The release film according to any one of claims 1 to 5, wherein the condensed polycyclic aromatic structure is a naphthalene ring structure. The release film according to any one of claims 1 to 6, wherein the aliphatic acid component is an aliphatic acid component having 12 or less carbon atoms.