JP5797416B2 - Release film - Google Patents

Description

  The present invention relates to a release film. For example, in a production process having an adhesive application step, a drying step, a release film laminating step, etc., it is particularly 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.

  A release film based on a polyester film is used for various applications. For example, in a touch panel manufacturing process, a polyester film with a hard coat layer and a release film are bonded together via an adhesive layer. It consists of a manufacturing process having processes and the like. During the processing step, it may be necessary that the release layer does not easily fall off from the polyester film substrate constituting the release film.

  For example, during the processing step, the conveyance guide roll and the release film may come into contact with each other and rub, or components from the release layer may adhere to and accumulate on the conveyance roll. Therefore, it is difficult to ensure continuous productivity, such as stopping the production line once and performing cleaning work.

  As a countermeasure against the above-described process contamination problem, for example, an adhesive layer may be provided between the polyester film and the release layer constituting the release film. However, depending on the material constituting the adhesive layer, when the release layer is applied on the adhesive layer, the adhesive layer itself may be poor in durability to the solvent. In some cases, the material component to be extracted is easily extracted with a solvent, resulting in problems such as inhibition of the curing of the release layer or failure to obtain a desired release property. Further, depending on the material composition constituting the adhesive layer, the adhesiveness between the release layer and the polyester film substrate may be maintained and ensured to a desired level, for example, over 14 days. May be difficult

  In view of the above problems, it is necessary to have good adhesion over time and solvent resistance to the release layer.

JP-A-9-141805 JP-A-9-141806 Japanese Patent No. 3471151 JP 2010-5807 A JP 2010-127543 A JP 2010-15506 A JP 2010-15507 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is a release layer that constitutes a release film in each manufacturing process of an adhesive application step, a drying step, and a release film bonding step. Another object of the present invention is to provide a release film having good adhesion with time and a polyester film substrate and good solvent resistance.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the use of a laminated polyester film having a specific configuration can easily solve the above-described problems, and have completed the present invention.

That is, the gist of the present invention is a release film having a coating layer on one side of a polyester film, and having a release layer having a press adhesion rate of 90% or more on the coating layer, and in the release layer, At least a polyester resin containing 0.5 to 2.0 parts by weight of β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and 100 parts by weight of curable silicone resin and having a sulfonic acid or a sulfonate group It exists in the release film characterized by including 1 or more types in the said coating layer.

  ADVANTAGE OF THE INVENTION According to this invention, the release film which has favorable adhesiveness with respect to a release layer and solvent resistance can be provided, For example, it is suitable for various optical uses, such as those for touch panel manufacture and liquid crystal polarizing plate manufacture. is there.

  In the present invention, the polyester film constituting the release film may have a single layer structure or a multilayer structure, and may have four layers or more unless the gist of the present invention is exceeded other than the two-layer or three-layer structure. The above multilayer may be used, and is not particularly limited.

  The polyester used in the present invention is preferably obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol, and may be a polyester comprising one kind of aromatic dicarboxylic acid and one kind of aliphatic glycol. It may be a copolyester 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. Typical polyester includes polyethylene terephthalate and the like. On the other hand, examples of the dicarboxylic acid used as a component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, and sebacic acid, and glycol components include ethylene glycol, diethylene glycol, and propylene. Examples include glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like. Oxycarboxylic acids such as p-oxybenzoic acid can also be used.

  In addition, in the laminated polyester film constituting the release film in the present invention, in order to reduce the amount of oligomers contained in the film deposited and crystallized on the surface of the film due to heat history during film processing, etc. 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.

  In the laminated polyester film constituting the release film of the present invention, it is necessary to blend particles for the main purpose of imparting slipperiness and preventing scratches in each step. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. Two or more kinds of these particles may be used in combination as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-3 micrometers normally, Preferably it is the range of 0.01-2 micrometers. When the average particle diameter is less than 0.01 μm, the particles are likely to aggregate and dispersibility may be insufficient. On the other hand, when the average particle diameter exceeds 3 μm, the surface roughness of the film becomes too rough and Problems may occur when various surface functional layers are applied in the process.

  Further, the content of particles in the polyester layer is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content 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.

  The method for 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 for producing the polyester constituting each layer, but it is preferably added after completion of esterification or transesterification.

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

  In addition, in the laminated polyester film constituting the release film in the present invention, conventionally known UV absorbers, antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes in addition to the above-mentioned particles as necessary. , Pigments and the like can be added.

  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 as a film, but is usually 25 to 250 μm, preferably 38 to 188 μm, more preferably. It is in the range of 50 to 125 μm.

  Next, although the manufacture example of the laminated polyester film which comprises the release film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all. That is, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a 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. Next, the film is stretched in the direction perpendicular to the first stretching direction. In that 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. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  In the present invention, the simultaneous biaxial stretching method can also be adopted for the production of the polyester film. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is usually stretched and oriented in the machine direction and the width direction at a temperature controlled normally at 70 to 120 ° C., preferably 80 to 110 ° C. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. Regarding the simultaneous biaxial stretching apparatus that employs the above-described stretching method, a stretching method such as a screw method, a pantograph method, or a linear drive method can be employed.

  Furthermore, a so-called coating stretching method (in-line coating) in which the film surface is treated during the above-described polyester film stretching step can be applied. When a coating layer is provided on a laminated polyester film by a coating stretching method, coating can be performed simultaneously with stretching, and the thickness of the coating layer can be reduced according to the stretching ratio. Can be manufactured.

Next, formation of the coating layer in the present invention will be described.
The coating layer constituting the release film in the present invention refers to a layer having easy adhesion.

  In the present invention, the polyester resin constituting the coating layer is defined as a linear polyester having a dicarboxylic acid component and a glycol component as constituent components. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, phenylindanedicarboxylic acid, A dimer acid etc. can be illustrated. Two or more of these components can be used. Further, together with these components, a small proportion of 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. Can be used. The proportion of the unsaturated polybasic acid component or the hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less.

As glycol components, ethylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol, dimethylolpropionic acid Glycerin, trimethylolpropane, poly (ethyleneoxy) glycol, poly (tetramethyleneoxy) glycol, an alkylene oxide adduct of bisphenol A, an alkylene oxide adduct of hydrogenated bisphenol A, and the like. Two or more of these can be used. Among these polyol components, ethylene glycol, an ethylene oxide adduct of bisphenol A, a propylene oxide adduct, and 1,4-butanediol are preferable, and an ethylene oxide adduct and propylene oxide adduct of ethylene glycol and bisphenol A are more preferable.

  Further, the coating layer constituting the laminated polyester film in the present invention contains at least one polyester resin having a sulfonic acid group or a sulfonic acid group in order to facilitate water dispersion or water solubility. Is an essential requirement.

  Examples of these polyester resins include 5-sodium sulfoisophthalic acid, 5-ammonium sulfoisophthalic acid, 4-sodium sulfoisophthalic acid, 4-methylammonium sulfoisophthalic acid, 2-sodium sulfoisophthalic acid, and 5-potassium sulfoisophthalic acid. Preferred examples include sulfonic acid alkali metal salt compounds such as 4-potassium sulfoisophthalic acid, 2-potassium sulfoisophthalic acid, and sodium sulfosuccinic acid, and sulfonic acid amine salt compounds.

  The glass transition temperature of the polyester resin used in the coating layer of the present invention (hereinafter sometimes abbreviated as Tg) is preferably 40 ° C. or higher, more preferably 60 ° C. or higher. When Tg is less than 40 ° C., for the purpose of improving adhesiveness, when the coating thickness of the coating layer is increased, problems such as easy blocking may occur.

  Next, in the case of providing a release layer on the coating layer constituting the laminated polyester film in the present invention, it may be provided on the polyester film in the film production process such as the above-described coating stretching method (inline coating), A so-called off-line coating that is applied outside the system on a once produced film may be employed, and any method may be employed. The coating stretching method (in-line coating) is not limited to the following, but for example, in sequential biaxial stretching, the first stage of stretching may be completed and the coating treatment may be performed before the second stage of stretching. it can. When a release layer is provided on a polyester film by a coating and stretching method, the film can be applied simultaneously with stretching, and the thickness of the release layer can be reduced according to the stretching ratio. Can be manufactured.

  The case where a release layer is provided on the coating layer constituting the release film in the present invention will be described below.

  The release layer constituting the release film of the present invention preferably contains a curable silicone resin in order to improve the release property. A type having a curable silicone resin as a main component may be used, or a modified silicone type by graft polymerization with an organic resin such as a urethane resin, an epoxy resin, or an alkyd resin may be used.

  As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet curable type, an electron beam curable type, and a solventless type can be used. Specific examples include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, X manufactured by Shin-Etsu Chemical Co., Ltd. -62-1387, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A / B, X-62-7052, X-62-7028A / B, X-62-7619, X-62 -7213, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210 manufactured by Dow Corning Asia Co., Ltd. YSR-3022, TPR-6700, TPR-6720 manufactured by GE Toshiba Silicone Co., Ltd. , TPR-6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775 XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605, manufactured by Dow Corning Toray Co., Ltd. SRX357, SRX211, SD7220, LTC750A, LTC760A, SP7259, BY24-468C, SP7248S, etc. BY24-452 are exemplified. Further, a release control agent may be used in combination to adjust the release property of the release layer.

Further, in the release layer constituting the release film in the present invention, an organosilicon compound represented by the following general formula (1) is used in combination in order to improve the coating film adhesion between the release layer and the polyester film. It is preferable to do.
Si (X) _d (Y) _e (R ¹ ) _f (1)
[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 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 (1) has two hydrolyzable groups Y (D unit source) or three (T unit) capable of forming a siloxane bond by hydrolysis / condensation reaction. Source) can be used.

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

  In the general formula (1), examples of the hydrolyzable group Y 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, specific examples of the organosilicon compound contained in the release layer include vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 5-hexenyltrimethoxy Examples include silane, p-styryltrimethoxysilane, trifluoropropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and γ-glycidoxypropylmethyldiisopropenoxysilane.

  As content of an organosilicon compound, it is good that it is 0.5-5.0 weight part with respect to 100 weight part of curable silicone resins, Preferably it is 0.5-2.0 weight part. If the range is less than 0.5 parts by weight, it may be difficult to ensure the desired adhesion. On the other hand, if it exceeds 5.0 parts by weight, the adhesion to the mating resin layer is too strong. In a scene that originally needs to be peeled off, there may be a problem that it cannot be easily peeled off.

In the present invention, a catalyst can be used in combination in the release layer constituting the release film for the purpose of promoting hydrolysis and condensation reaction. Specific examples of the catalyst include organic acids such as acetic acid, butyric acid, maleic acid and citric acid, inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid, basic compounds such as triethylamine, tetrabutyl titanate, dibutyltin dilaurate, Organometallic salts such as dibutyltin diacetate, dibutyltin dioctate, dibutyltin diolate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dibutyltin benzylmalate, KF, NH ₄ Fluorine element-containing compounds such as F can be mentioned. The above catalysts may be used alone or in combination of two or more. Among these, organometallic salts are preferable in that the coating film durability is particularly good.

  In the present invention, as a method for providing a release layer on the coated layer of the laminated polyester film, a conventionally known coating method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, etc. may be used. it can. Regarding the coating method, there is a description example in “Coating method” published by Yasuharu Harasaki in 1979.

In the present invention, the curing conditions for forming the release layer on the coated layer of the laminated polyester film are not particularly limited. When the release layer is provided by off-line coating, it is usually 3 at 120 to 200 ° C. The heat treatment may be performed for ˜40 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. In addition, as an energy source for hardening by active energy ray irradiation, a well-known apparatus and an energy source can be used. The coating amount of the release layer is usually 0.005 to 1 g / m ² , preferably 0.005 to 0.5 g / m ² , more preferably 0.005 to 0.1 g / m ² from the viewpoint of coatability. it is in the range of m ^2. If the coating amount is less than 0.005 g / m ² , the coating property may be less stable and it may be difficult to obtain a uniform coating film. On the other hand, when the coating is thicker than 1 g / m ² , the coating layer adhesion and curability of the release layer itself may be lowered.

  The laminated polyester film constituting the release film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  Next, formation of the coating layer constituting the release film in the present invention is provided by coating the film with a coating solution, and it may be provided by in-line coating performed in the film manufacturing process, or once manufactured. You may employ | adopt what is called an off-line coating apply | coated on the system outside.

  In the present invention, in the coating layer constituting the release film, it is intended to prevent elution of components derived from the coating layer due to durability against the solvent or thermal damage to the coating layer during the release layer coating. As long as the gist of the present invention is not impaired, a crosslinking agent can be used in combination. Specifically, methylolated or alkylolized urea, melamine, guanamine, oxazoline, epoxy compound, acrylamide, polyamide compound, epoxy compound, aziridine compound, isocyanate compound, titanium coupling agent, zirco-aluminate coupling agent, Examples include polycarbodiimide.

  The content of the crosslinking agent constituting the coating layer of the film of the present invention is preferably 10% by weight or less in terms of the blending ratio in the coating layer in consideration of coloring during regeneration of the polyester film with the coating layer.

  The oxazoline crosslinking agent in the present invention is a compound having an oxazoline ring in the molecule, and includes a monomer having an oxazoline ring and a polymer synthesized using an oxazoline compound as one of raw material monomers.

  The isocyanate compound in the present invention refers to a compound having an isocyanate group in the molecule, specifically, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, naphthalene diisocyanate, tolylene diisocyanate. And polymers and derivatives thereof.

  As an epoxy compound in this invention, the compound containing an epoxy group in a molecule | numerator, its prepolymer, and hardened | cured material are mentioned, for example. A typical example is a condensate of epichlorohydrin and bisphenol A. In particular, a reaction product of a low molecular polyol with epichlorohydrin gives an epoxy resin having excellent water solubility.

  Among the cross-linking agents, melamine cross-linking agents are preferable in terms of improving the applicability to the polyester film and the durable adhesion of the coating layer itself, particularly for the purposes of the present invention. The melamine crosslinking agent is not particularly limited, but melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, a compound partially or completely etherified by reacting methylolated melamine with a lower alcohol, And a mixture thereof can be used.

  The melamine crosslinking agent may be either a monomer or a condensate composed of a dimer or higher multimer, or a mixture thereof. As the lower alcohol used for the etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like can be preferably used. The functional group has an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, and an imino group type methylated melamine, a methylol group type melamine, or a methylol group type methylated group. Melamine, fully alkyl methylated melamine and the like can be used. Of these, methylolated melamine is most preferred. Furthermore, for the purpose of promoting thermal curing of the melamine crosslinking agent, for example, an acidic catalyst such as p-toluenesulfonic acid can be used in combination.

  These crosslinking agents may be used alone or in combination of two or more. Furthermore, when consideration is given to application to in-line coating, it is preferable to have water solubility or water dispersibility.

  Furthermore, it is preferable to contain particles for the purpose of improving the adhesion and slipperiness of the coating layer. Specific examples include silica, alumina, kaolin, calcium carbonate, titanium oxide, barium salt and the like.

  The amount of particles in each coating layer is usually 0.5 to 10% by weight, preferably 1 to 5% by weight. When the blending amount is less than 0.5% by weight, the blocking resistance may be insufficient. On the other hand, when it exceeds 10% by weight, the transparency of the film may be lowered.

  In addition, within the range not impairing the gist of the present invention, each coating layer includes an antifoaming agent, a coating property improver, a thickener, an organic lubricant, organic polymer particles, an antioxidant, if necessary. An ultraviolet absorber, a foaming agent, a dye, etc. may be contained.

  In the case of the coating stretching method (in-line coating), a coating solution in which the above-mentioned series of compounds is used as an aqueous solution or water dispersion and the solid content concentration is adjusted to about 0.1 wt% to 50 wt% as a guide is applied onto the polyester film. It is preferable to produce a laminated polyester film in the manner of application.

  In addition, a small amount of an organic solvent may be contained in the coating solution for the purpose of improving the dispersibility in water, improving the film forming property, and the like within a range not exceeding the gist of the present invention. Examples of the organic solvent 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, Examples include glycol derivatives such as ethyl cellosolve, methyl cellosolve, 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, and amides such as N-methylpyrrolidone. Can be mentioned. Only one type of organic solvent may be used, or two or more types may be used as appropriate.

The coating amount (after drying) of the coating layer constituting the release film in the present invention is usually 0.005 to 0.1 g / m ² , preferably 0.005 to 0.05 g / m ² , and more preferably 0.00. The range is from 005 to 0.01 g / m ² . When the coating amount is less than 0.005 g / m ² , the uniformity of the coating thickness may be insufficient, and the coating layer may be eluted by a solvent when the release layer is applied. On the other hand, in the case of application exceeding 0.1 g / m ² , problems such as deterioration of the applied surface may occur.

  The release force of the release film in the present invention is preferably 60 mN / cm or less, more preferably 20 mN / cm or less. When the peeling force exceeds 60 mN / cm, the peeling force becomes too heavy, and it may not be easily peeled even in a scene that originally needs to be peeled off. On the other hand, regarding the lower limit, 10 mN / cm is preferable in consideration of peelability with respect to the pressure-sensitive adhesive layer.

  It is an essential requirement that the press-bonding rate of the release layer constituting the release film in the present invention is 90% or more. When the press adhesion rate is less than 90%, a problem due to transfer of components derived from the release layer to the transport roll occurs.

  In the present invention, regarding the press adhesion rate of the release layer, not only from the viewpoint of evaluating the migration of components derived from the release layer, but also through the press process, the performance inherent in the release layer is not affected by the coating layer. It is also aimed to confirm that it is expressed.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. The measurement method and evaluation method used in the present invention are as follows.

(1) Measuring method of 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 measurement was performed at 30 ° C.

(2) Measuring method of average particle size (d ₅₀ : μm) Integration (weight basis) 50 in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type, manufactured by Shimadzu Corporation) % Was defined as the average particle size.

(3) Peeling force (F) measurement of release film After pasting a double-sided adhesive tape (Nitto Denko "No. 31B") on the release layer surface of the sample film, it was cut to a size of 50 mm x 300 mm, The peel force after standing for 1 hour at room temperature is measured. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min. The determination was made according to the following criteria.
<Criteria>
○: Peeling force exceeds 25 mN / cm ×: Peeling force is 25 mN / cm or less

(4) Solvent resistance evaluation of release film (practical property substitution evaluation)
In the sample film, 1 cc of a toluene solvent was dropped using a dropoid, and then the release layer surface state was determined according to the following criteria.
<Criteria>
○: Good, no change in the appearance of the release layer surface (practically satisfactory level)
X: Appearance change on the surface of the release layer (practically problematic level)

(5) Evaluation of film adhesion to release film (practical property substitution evaluation)
In the sample film, a release layer composed of the following release agent composition is applied to the surface of the application layer in advance, and then left in a constant temperature and humidity chamber at 60 ° C. × 90% RH for 30 days. Next, the sample film was taken out and allowed to stand at room temperature for 1 hour, and then the surface of the release layer was rubbed with a tentacle 5 times, and the degree of removal of the release layer was determined according to the following criteria.
(Releasing agent composition)
Curable silicone resin (KS-774: manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts Curing agent (PL-3: manufactured by Shin-Etsu Chemical Co., Ltd.) 10 parts Silane compound (KBM303: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 4) 1500 copies << Criteria >>
○: Dropping of the release layer was not confirmed (level that is practically acceptable)
Δ: Smear of the release layer was confirmed, but it did not fall off (level that may cause a problem in practical use)
×: Dropping of the release layer was confirmed (practically problematic level)

(6) Evaluation of press adhesion rate << Press adhesive strength >>
The press treatment is performed under the conditions of 75 μm polyester film / measurement sample film / 75 μm polyester film, temperature 60 ° C., pressure 1 MPa, and time 120 minutes. After the press treatment, on the surface of the 75 μm polyester film that was in contact with the measurement sample film release layer surface, Nitto No. 31 tape is affixed and peeling force (A) is measured. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min.
《Basic adhesive strength》
To the same 75 μm polyester film used for the press treatment, Nitto No. A 31 tape is affixed, the peel force (B) is measured in the same manner as the peel force (A), and the press adhesion rate is determined based on the following formula. The measurement is performed at 20 ± 2 ° C. and 65 ± 5% RH.
Press adhesive rate (%) = (Press adhesive force / Basic adhesive force) × 100

(7) Comprehensive evaluation About the peelability, adhesiveness, solvent resistance, and press adhesion rate evaluation of the release layer constituting the release film, the following determination criteria were used.
<Criteria>
◎: Particularly excellent in evaluation of peelability, adhesion, solvent resistance, and press adhesion rate of the release layer as ◯ or more, and adhesion evaluation as ◎ (practically no problem level)
○: Good for evaluation of peelability, adhesion, solvent resistance, and press adhesion rate of release layer (good level for practical use)
Δ: Evaluation of one of release layer peelability, adhesion, solvent resistance, and press adhesion rate evaluation is △ (level that may cause problems in practice)
× ・ ・ ・ Evaluation of any one of release layer peelability, adhesion, solvent resistance, and press adhesion rate evaluation × (level that is problematic in practice)

The polyester used in the examples and comparative examples was prepared 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 is placed in the reactor, the reaction start temperature is set to 150 ° C., and the methanol is distilled off gradually. 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 of ethyl acid phosphate to this reaction mixture, 0.04 part 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 normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped at a time 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 of ethyl acid phosphate, 0.3 part 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. In addition, polyester (II) was obtained using the same method as the production method of polyester (I) except that the polycondensation reaction was stopped at the time corresponding to the intrinsic viscosity of 0.65. The obtained polyester (II) had an intrinsic viscosity of 0.65.

Example 1:
A mixed raw material in which polyesters (I) and (II) are mixed at a ratio of 90% and 10%, respectively, is used as a raw material for the outermost layer (surface layer), and polyester (I) is used as a raw material for the intermediate layer. After being melted at 285 ° C. each, it is coextruded in a layer configuration of two types and three layers (surface layer / intermediate layer / surface layer) on a cooling roll set to 40 ° C., and cooled and solidified to form an unstretched sheet. Obtained. Next, after stretching 3.4 times in the machine direction at a film temperature of 85 ° C. using the difference in roll peripheral speed, the coating layer composed of the following coating composition is applied in a predetermined amount (after drying). After coating on one side of the film, it is guided to a tenter, stretched 4.3 times at 120 ° C in the transverse direction, and heat treated at 225 ° C, and then a coating layer with a thickness of 38 µm (surface layer 5 µm, intermediate layer 28 µm) is provided. A laminated film was obtained. In addition, the example of a compound which comprises an application layer is as follows.

(Example compounds)
・ Polyester resin (A1) Tg = 63 ℃
Acid component: terephthalic acid 50 mol%
Isophthalic acid 48mol%
5-Na sulfoisophthalic acid 2 mol%
Diol component: Ethylene glycol 50 mol%
Neopentyl glycol 50 mol%
・ Polyester resin (A2) Tg = 45 ° C
Acid component: 55 mol% terephthalic acid
Isophthalic acid 40 mol%
5-Na sulfoisophthalic acid 5 mol%
Diol component: Ethylene glycol 60 mol%
1,4 butanediol 40 mol%
・ Polyester resin (A3) Tg = 25 ° C
Acid component: terephthalic acid 60 mol%
Isophthalic acid 30 mol%
5-Na sulfoisophthalic acid 10 mol%
Diol component: Ethylene glycol 50 mol%
Diethylene glycol 50 mol%

・ Polyester resin (A4) Tg = 55 ° C
Acid component: terephthalic acid 20 mol%
Isophthalic acid 60 mol%
5- (2,5-dioxotetrahydrofurfuryl) -3-methyl-3cyclohexene-1,2-dicarboxylic acid 20 mol%
Diol component: Neopentyl glycol 50 mol%
Diethylene glycol 50 mol%

-Particles (B): Colloidal silica Nissan Chemical: Snowtex “YL” average particle size 70 nm
・ Crosslinking agent (C1): Oxazoline EPOCROSS “WS700” manufactured by Nippon Shokubai
・ Crosslinking agent (C2): Melamine crosslinking agent Crosslinkable resin of alkylolmelamine / urea copolymer DIC Beckamine “J101”
Crosslinking agent (C3): Urethane resin 400 parts of polycarbonate polyol having a number average molecular weight of 2000 consisting of 1,6-hexanediol and diethyl carbonate, 10.4 parts of neopentyl glycol, 58.4 parts of isophorone diisocyanate, dimethylol An aqueous dispersion of urethane resin obtained by neutralizing a prepolymer comprising 74.3 parts of butanoic acid with triethylamine and extending the chain with isophoronediamine

Acrylic resin (D): Tg = 64 ° C
50% by weight methyl methacrylate
Methyl acrylate 35% by weight
2-hydroxyethyl methacrylate 10% by weight
5% by weight of isobutyl acrylate

A release agent having a release agent composition shown below is applied off-line on the coated layer of the obtained laminated polyester film by a reverse gravure coating method so that the application amount (after drying) is 0.1 g / m ^2. After heat treatment at 180 ° C. for 10 seconds, a release film was obtained.
(Releasing agent composition)
Curable silicone resin (KS-774: manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts Curing agent (PL-3: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part Silane compound (KBM303: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

Examples 2-9 :
In Example 1, except having changed a coating layer into the coating agent composition shown in Table 1, it manufactured like Example 1 and obtained the release film. The properties of the obtained release film are shown in Table 2 below.

Comparative Example 1:
In Example 1, it manufactured similarly to Example 1 except not providing an application layer, and obtained the release film. The properties of the obtained release film are shown in Table 2 below. In the evaluation of the adhesion of the coating layer, it was confirmed that the release layer had already dropped after the treatment at 60 ° C. × 90% RH × 72 hours.

Comparative Example 2:
In Example 1, except having changed a mold release agent composition into the following composition, it manufactured like Example 1 and obtained the release film. The properties of the obtained release film are shown in Table 2 below.
(Releasing agent composition)
Curable silicone resin (KS-774: manufactured by Shin-Etsu Chemical) 100 parts Curing agent (PL-3: manufactured by Shin-Etsu Chemical) 1 part Polyether-modified silicone oil (KF-351: manufactured by Shin-Etsu Chemical) 3 parts MEK / toluene mixed solvent ( The mixing ratio is 1: 1) 1500 parts

  The present invention can be suitably used, for example, for optical purposes such as for touch panel production and liquid crystal polarizing plate production.

Claims (1)

A release film having a coating layer on one side of a polyester film and having a release layer having a press adhesion rate of 90% or more on the coating layer, and 100 parts by weight of curable silicone resin in the release layer In contrast, 0.5 to 2.0 parts by weight of β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and at least one polyester resin having a sulfonic acid or a sulfonate group is contained in the coating layer. A release film characterized by containing in the above.