JP2015016677A - Release polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release polyester film which is a release film required during processing of a tackiness agent without contaminating a heating roll or a metal roll in a step requiring a severe degree of cleanliness and contaminating a drying furnace of a tackiness agent.SOLUTION: There is provided a release polyester film which is a laminated polyester film having a laminated structure having at least three or more layers and has a polyester containing 3000 to 30000 ppm of a polymer having at least two epoxy groups in the molecular chain as both surface layers. The release polyester film comprises: a coating layer obtained by coating a coating liquid containing a quaternary ammonium base-containing polymer, a polyethylene glycol-containing acrylate polymer and a crosslinking agent on one surface of the laminated polyester film; and a coating layer having a thickness of 10 to 100 nm which is formed by coating a coating agent containing at least one organosiloxane compound on the coating layer, and has a release layer on the other surface.

Description

  The present invention relates to a release polyester film having excellent oligomer sealing performance.

  The technologies of flat panel display, organic EL, touch panel and electronic paper are becoming general-purpose technologies. Among the items described, there is still a pressure-sensitive adhesive technology that bonds members together, but the demand for this pressure-sensitive adhesive continues to grow. From this, the demand for release films that may be used during adhesive processing has the potential to grow as well.

  As necessary properties for release films used for adhesive processing, processing properties such as releasability and handling properties are of course important, but in recent years, other foreign matter inspection properties and process contamination sealing properties are important. The characteristics for improving the quality and the processing yield are also important. Among them, a sealing function related to process contamination sealing properties, for example, a base material component scattering sealing performance, an AS performance that does not attract foreign substances, is cited as a demand for separators used in matured adhesive technology. .

  In conventional release films, especially release polyester films, due to rolls existing in the process, especially metal rolls, heating rolls, scratches entering when passing, temperature, and heat applied during adhesive processing, A polyester film base material component (here, an oligomer, which may be abbreviated as OL hereinafter) may occur.

  As existing technology for suppressing OL generation in a release polyester film, there are a method using a polyester raw material with a small amount of OL and a method of providing an OL sealing layer (Patent Documents 1 and 2). The method etc. are mentioned. However, in the former case, the efficacy may be insufficient, and in the latter case, there is a problem that the silicone film cannot be formed well during the final silicone processing due to a small amount of transfer of the components of the OL sealing layer.

  That is, in the release polyester film technology, there is a demand for OL sealing layer application technology for stably coating the silicone release layer.

Japanese Patent No. 5281595 JP 2012-179870 A

  The present invention has been made in view of the above circumstances, and its solution is a release film necessary at the time of adhesive processing, and does not contaminate a heating roll or a metal roll in a process with a strict cleanliness, And it is providing the release polyester film which does not contaminate an adhesive drying furnace.

  As a result of intensive studies in view of the above circumstances, the present inventor has found that the above problem can be easily solved by a polyester film having a specific configuration, and has completed the present invention.

  That is, the gist of the present invention is a laminated polyester film having a laminated structure of at least 3 layers, in which a polyester containing 3000 to 30000 ppm of a polymer having at least two epoxy groups in a molecular chain is used as both surface layers. One surface of the film has a coating layer obtained by coating a coating solution containing a quaternary ammonium base-containing polymer, a polyethylene glycol-containing acrylate polymer, and a crosslinking agent, and at least one kind of the coating layer is formed on the coating layer. The present invention resides in a release polyester film characterized by having a coating layer having a thickness of 10 to 100 nm formed by applying a coating agent containing an organosiloxane compound and having a release layer on the other surface.

  According to the present invention, it is possible to provide a release polyester film that prevents the contamination of the pressure-sensitive adhesive process and increases the pressure-sensitive adhesive processing yield, and therefore has high industrial value.

Schematic explanatory drawing showing the structure of the film of the present invention

  The optical laminated polyester film of the present invention is required to be a multilayer film having at least 3 layers. The laminated polyester film for optics referred to in the present invention is a polyester film extruded by a so-called extrusion method that is melt-extruded from an extrusion die, and is oriented in the biaxial direction of the vertical direction and the horizontal direction as necessary. Film.

  In the present invention, the polyester is obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. 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 polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN) and the like.

  The polyester used in the present invention may be a homopolyester or a copolyester. In the case of a copolyester, it is a copolymer containing 30 mol% or less of the third component. Examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acids (for example, P-oxybenzoic acid). Or 2 or more types are mentioned, As a glycol component, 1 type, or 2 or more types, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanone neopentyl glycol, is mentioned.

  In the present invention, it is necessary to use a polyester containing 3000 to 30000 ppm of a polymer containing an epoxy group in its molecular chain in the molecular chain. When the content of the epoxy group is less than 3000 ppm, the acid catalyst deactivation ability of the carboxyl group due to the epoxy group is not sufficient, and when the content exceeds 30000 ppm, the viscosity of the polyester is increased by cross-linking by a chemical reaction between the epoxy group and the carboxyl group. As a result, it becomes difficult to extrude with a polyester extruder.

  The polymer having at least two epoxy groups in the molecular chain used in the present invention is not limited as long as it is a polymer compatible with the polyester resin. For example, a polyester resin, an acrylic resin, a polyurethane resin, Examples thereof include polycarbonate resins, styrene resins, polyimide resins, polyamide resins, polyolefin resins, mixtures thereof, and copolymers. A resin that is particularly preferably used is a copolymer of an acrylic resin and a styrene resin.

  In addition, the molecular weight of the polymer having at least two epoxy groups in the molecular chain used in the present invention is not limited as long as it is compatible with the polyester resin, but the molecular weight of the polymer used preferably The average molecular weight is in the range of 350 to 8000 g / mol, preferably in the range of 400 to 3000 g / mol, and more preferably in the range of 500 to 3000 g / mol.

  The thickness of the outermost layer of the film of the present invention is preferably 4 μm or more, more preferably 5 μm or more, and further preferably 6 μm or more. When the thickness of the outermost layer is less than 4 μm, the oligomer reducing effect due to the epoxy group containing in the outermost layer tends to be reduced.

In the polyester layer of the film of the present invention, particles may be blended mainly for the 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. These series of particles may be used in combination of two or more as required.

  Although it does not specifically limit as an average particle diameter of the particle | grains mix | blended in a polyester film, Usually, 0.02-3 micrometers, Preferably it is 0.02-2.5 micrometers, More preferably, it is the range of 0.02-2 micrometers. It is. When particles having an average particle size of less than 0.02 μm are used, sufficient slipperiness may not be imparted, and as a result, the winding characteristics in the film manufacturing process may be inferior. On the other hand, when the average particle diameter exceeds 3 μm, the degree of roughening of the film surface tends to be too large and the film tends to become hazy.

  Furthermore, the particle content in the polyester layer is usually in the range of 0.0005 to 0.5% by weight, preferably 0.001 to 0.3% by weight. When the particle content is less than 0.0005% by weight, the slipperiness of the film is insufficient, and appearance defects such as scratches may occur during film processing. On the other hand, when adding over 0.5 weight%, the transparency of a film may become inadequate.

  In the present invention, the method of blending the particles with the polyester is not particularly limited, and a known method can be adopted. For example, it can be added at any stage of producing the polyester, but it is preferably added as a slurry dispersed in ethylene glycol or the like at the stage of esterification or before the start of the polycondensation reaction after completion of the transesterification reaction, The polycondensation reaction may proceed. 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.

  Next, although the manufacture example of the polyester 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 7.0 times, preferably 3.0 to 6.0 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 7.0 times, preferably 3.5 to 6 times. .0 times. 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.

  For the production of the polyester film of the present invention, a simultaneous biaxial stretching method can also be employed. 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. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, or a linear driving method can be employed.

  The total film thickness of the film of the present invention is preferably in the range of 10 to 188 μm. If the total film thickness is less than 10 μm, wrinkles are likely to occur in the heating process applied to the film, and the thickness of the pressure-sensitive adhesive may be uneven. If it is greater than 188 μm, the film weight will increase and heat drying during silicone processing In the process, it becomes difficult to run well, the film is easily scratched, and the yield may be reduced.

  Next, formation of a layer constituting the polyester film in the present invention (which is a layer adjacent to the polyester base material and may be simply abbreviated as A layer hereinafter) will be described. Regarding the A layer, it may be provided by in-line coating, which treats the film surface during the stretching process of the polyester film, or may be applied off-system on the film once produced, or may be used together. May be. In-line coating is preferably used in that it can be applied at the same time as film formation, and thus can be manufactured at low cost, and the thickness of layer A 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 particularly before the lateral stretching after the longitudinal stretching is finished. When a coating layer is provided on a polyester film by in-line coating, coating can be performed simultaneously with film formation, and the coating layer can be processed at a high temperature, and a film suitable as a polyester film can be produced.

  In the present invention, the layer A has an essential requirement to use a coating solution containing a quaternary ammonium base-containing polymer for the purpose of preventing the oligomer component from entering the pressure-sensitive adhesive layer. .

  Regarding the quaternary ammonium base-containing polymer used in the present invention, those having a constituent element containing a quaternary ammonium base in the main chain or side chain in the molecule are targeted. Specific examples include pyrrolidinium ring, quaternized alkylamine, copolymerized with acrylic acid or methacrylic acid, quaternized N-alkylaminoacrylamide, vinylbenzyltrimethylammonium salt, 2-hydroxy-3- And methacryloxypropyltrimethylammonium salt. Furthermore, these may be combined or copolymerized with other binder polymers. Examples of the anion that serves as a counter ion for these quaternary ammonium salts include ions such as halogen, alkyl sulfate, alkyl sulfonate, and nitric acid. Among these, counter ions other than halogen are preferable for the use of the present invention in that heat resistance is particularly good.

  Further, regarding the molecular weight of the quaternary ammonium base-containing polymer, when the molecular weight is too low, it is easily removed from the coating layer, and the performance deteriorates with time, or problems such as blocking of the coating layer occur. Moreover, when the molecular weight is low, the heat stability is poor.

  From this viewpoint, the number average molecular weight of the quaternary ammonium base-containing polymer is usually 1000 or more, preferably 2000 or more, and more preferably 5000 or more. On the other hand, when the number average molecular weight is too high, problems such as excessive increase in the viscosity of the coating solution occur. Therefore, the upper limit of the number average molecular weight is preferably 500,000 or less. Moreover, these compounds may be used independently and may be used in combination of 2 or more types.

The blending amount of the quaternary ammonium base-containing polymer in the layer A is preferably in the range of 20 to 70% by weight, more preferably in the range of 40 to 70% by weight in terms of dry weight.
When it is out of the range, it becomes difficult to obtain a desired oligomer sealing effect.

  In the present invention, it is essential to contain a polyethylene glycol-containing acrylate polymer in the coating solution for the purpose of improving the stretch followability when forming the A layer. Specifically, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, polyethylene glycol diacrylate (the polymerization degree of polyethylene glycol units is preferably in the range of 4 to 14), polypropylene glycol diacrylate, polytetramethylene glycol diacrylate, poly ( Ethylene glycol-tetramethylene glycol) diacrylate, poly (propylene glycol-tetramethylene glycol) diacrylate, polyethylene glycol-polypropylene glycol-polyethylene glycol diacrylate, polypropylene glycol-polybutylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate, methoxypolyethylene Glycol monoacrelan , Octoxy polyethylene glycol-polypropylene glycol monomethacrylate, Octoxy polyethylene glycol-polypropylene glycol monoacrylate, Lauroxy polyethylene glycol monomethacrylate, Lauroxy polyethylene glycol monoacrylate, Stearoxy polyethylene glycol monomethacrylate, Stearoxy polyethylene glycol monoacrylate, Ali Examples include polymers starting from loxypolyethylene glycol monomethacrylate, allyloxypolyethylene glycol monoacrylate, and the like.

  The number average molecular weight of the polyethylene glycol-containing acrylate polymer used in the present invention is usually 1000 or more, preferably 2000 or more, more preferably 5000 or more. On the other hand, when the number average molecular weight is too high, problems such as the viscosity of the coating solution becoming too high may occur. From this viewpoint, it is preferable that the upper limit of the number average molecular weight is 500,000 or less. Moreover, these compounds may be used independently and may be used in combination of 2 or more types.

  In the present invention, a polyethylene glycol-containing alkyl acrylate polymer is preferably used in combination in order to further improve stretchability. The chain length of the alkyl chain is not particularly limited as long as it is in a range that can be polymerized as a polymer. The content of the polyethylene glycol-containing alkyl acrylate polymer constituting the coating layer (A) in the present invention is preferably in the range of 5 to 40% by weight in order to improve stretchability. When it is out of the range, problems such as insufficient stretchability in forming the coating layer (A) may occur.

  Regarding the A layer constituting the polyester film of the present invention, the quaternary ammonium base-containing polymer and the polyethylene glycol-containing acrylate polymer to be used may be a mixture or may be copolymerized in advance, which impairs the gist of the present invention. The range is not particularly limited. Moreover, when making it copolymerize, a conventionally well-known manufacturing method can be used.

  In the present invention, it is necessary to use a crosslinking agent in combination as a coating solution for the purpose of further improving the durability of the A layer. Specific examples include 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, poly Examples thereof include carbodiimide.

  Among the cross-linking agents, melamine cross-linking agents are preferable in terms of good coating properties and durable adhesion particularly in the use 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 methylation. 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.

  The oxazoline crosslinking agent used 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 used 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 diene. Examples thereof include isocyanates, polymers and derivatives thereof.

  As an epoxy compound used by 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.

  These cross-linking 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.

  In the present invention, it is also possible to use a binder polymer in the coating layer as long as the gist of the present invention is not impaired.

  The “binder polymer” used in the present invention is a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) according to a polymer compound safety evaluation flow scheme (sponsored by the Chemical Substance Council in November 1985). ) Is a polymer compound having a molecular weight of 1000 or more and having a film-forming property.

  Specific examples of the binder polymer include polyester resin, acrylic resin, polyvinyl (polyvinyl alcohol, polyvinyl chloride, vinyl chloride vinyl acetate copolymer, etc.), polyurethane resin, polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starch. And the like.

  Analysis of the components in the coating solution for forming the A layer can be performed by surface analysis such as TOF-SIMS.

  When providing a coating layer by in-line coating, the above-mentioned series of compounds is applied as an aqueous solution or dispersion, and the coating solution adjusted to a solid content concentration of about 0.1 to 50% by weight as a guide is applied onto the polyester film. It is preferable to produce a laminated polyester film. Moreover, in the range which does not impair the main point of this invention, a small amount of organic solvents may be contained in the coating liquid for the purpose of improving dispersibility in water, improving film-forming properties, and the like. Only one type of organic solvent may be used, or two or more types may be used as appropriate.

For A layer of polyester film of the present invention, the thickness of the coating layer provided on the polyester film is usually 0.002~1.0g / ^{m 2,} more preferably 0.005 to 0.5 / ^{m 2,} further Preferably it is the range of 0.01-0.2 g / m < ² >. When the film thickness is less than 0.002 g / m ^2, sufficient adhesion may not be obtained, and when it exceeds 1.0 g / m ² , the appearance and transparency, and the blocking property of the film may deteriorate. is there.

  In the polyester film of the present invention, examples of the method of providing the A layer include conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, and curtain coating. Regarding the coating method, there is a description example in “Coating method” published by Yasuharu Harasaki in 1979.

  In the present invention, the drying and curing conditions for forming the A layer on the polyester film are not particularly limited. For example, when the coating layer is provided by off-line coating, it is usually 3 to 80 to 200 ° C. The heat treatment may be performed for 40 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds.

  On the other hand, when the A layer is provided by in-line coating, it is usually preferable to perform heat treatment at 70 to 280 ° C. for 3 to 200 seconds as a guide.

  Further, irrespective of off-line coating or in-line coating, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination as required. The polyester film constituting the laminated polyester film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  Next, formation of a coating layer (hereinafter sometimes simply referred to as B layer) to be laminated on the A layer will be described. Regarding the B layer, the above-described coating stretching method (in-line coating) may be used, or a so-called off-line coating that is applied outside the system on the polyester film having the above-described coating layer once manufactured may be employed. A technique may be adopted.

  The example of the organosiloxane compound mix | blended in the coating agent used in order to form B layer in this invention is shown below. Various substituents of the organosiloxane of the following formula are variously changed.

(R ¹ ) (R ³ ) ₂ Si— (O—Si (R ¹ ) (R ³ )) n- (O—Si (R ² ) (R ³ )) m—R ^{3 wherein} R ¹ and R ² is each independently an organic group containing an epoxy group such as a γ-glycidoxypropyl group or a 3,4-epoxycyclohexylethyl group, or an alkoxy group such as a methoxy group or an ethoxy group. , R ³ is an alkoxy group such as a methoxy group or an ethoxy group, or a group represented by the following formula.

—O—Si (R ³ ) ₂ (R ⁴ )
In the above formula, R ⁴ is the same epoxy group-containing organic group or alkoxy group as the R ¹ group or R ² group. Specific examples of the organosiloxane include γ-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 5 , 6-epoxyhexyltriethoxysilane, tetraethoxysilane, metolaethoxysilane, and other monomers, and hydrolyzable organisms of these monomers or mixtures of these monomers.

  The organic solvent that dissolves the B layer forming material preferably contains at least one alcohol solvent selected from ethanol, propanol, i-propanol, butanol, i-butanol, t-butanol, pentanol, and the like.

  Further, inorganic particles may be contained for the purpose of improving the adhesion and slipperiness of the B layer, and specific examples include silica, alumina, kaolin, calcium carbonate, titanium oxide, barium salt and the like.

  Moreover, if it is a material that has a low influence on the curing reaction inhibition of the release layer, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, organic polymer particles, an antioxidant, An ultraviolet absorbent foaming agent, a dye and the like may be contained.

  In the range not exceeding the gist of the present invention, only one type of organic solvent may be used for the purpose of improving dispersibility, improving film forming property, etc., and two or more types may be used as appropriate.

  In this invention, the application quantity (after drying) of B layer is 10-100 nm, Preferably it is the range of 20-100 nm. When the coating amount is less than 10 nm, the uniformity of the coating thickness becomes insufficient, and the amount of OL deposited from the surface of the B layer after heat treatment increases. On the other hand, if the thickness exceeds 100 nm, the coating film is brittle even if it has OL sealing performance, and scratches are likely to occur in the drying process and then the winding process after coating, and the film appearance tends to become cloudy.

  In the present invention, the roughness (Sa) of the surface of the B layer is preferably 10 nm or less. When the surface roughness exceeds 10 nm, the OL sealing performance may deteriorate. Furthermore, in order to exhibit sealing performance, Sa is preferably 8 nm or less. As a method of controlling this Sa, it is important that clusters (aggregates) are not generated as much as possible with the coating liquid before coating. As a result of the examination, it was found that the Sa can be controlled when the solution haze is usually 1.0% or less, preferably 0.5% or less.

  In the present invention, as a method of providing the B layer, a conventionally known coating method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating or the like can be used. As for the coating method, there is a description example in “Coating method” published by Yoji Harasaki in 1979.

  In the present invention, the curing conditions for forming the B layer on the polyester film are usually heat-treated at 120 ° C. or higher, preferably 120 to 200 ° C. for 3 to 40 seconds, more preferably 120 to 160 ° C. 3 Heat treatment is performed for approximately 40 seconds. When heat treatment is not performed at 120 ° C. or higher, the coating film formation is incomplete and the amount of OL deposited tends to increase.

  In the present invention, OL (oligomer) is defined as a cyclic trimer among low molecular weight substances that crystallize and precipitate on the film surface after heat treatment.

  In the present invention, the A layer and the B layer have OL sealing performance independently, but by combining them, the adhesive interaction in the film, or the configuration of compensating for the gap between each other is taken, and either of the films The OL sealing performance can be obtained more efficiently than the same thickness (A + B thickness). Moreover, even if only the B layer is applied to a certain extent so as to exceed 100 nm, a desired OL sealing performance can be imparted. C layer) causes curing inhibition during formation. The technical key of this patent is that the combination of the A and B layers and the thickness are important, and it is considered that a synergistic effect is brought about in the OL sealing performance.

  The release layer (C layer) provided on the opposite surface of the coating layer (A layer) and (B layer) in the present invention is not particularly limited as long as it contains a material having releasability. Among them, the one containing a curable silicone resin is preferable because the releasability is improved. 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 ray curable type, an electron beam curable type, and a solventless type can be used.

  Specific examples of the curable silicone resin include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2242, X-manufactured by Shin-Etsu Chemical Co., Ltd. 62-2461, 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 Toshiba Silicone Co., Ltd. , TPR-6721, SD 7220, SD 7226, SD 7229 manufactured by Toray Dow Corning Co., Ltd., and the like. Further, a release control agent may be used in combination to adjust the release property of the release layer. Further, as described above, a silane compound having an amino group may be added to the release layer.

In the present invention, as a method for providing a release layer on the polyester film, a conventionally known coating method such as reverse roll coating, gravure coating, bar coating, doctor blade coating, or the like can be used. The application amount of the release layer in the present invention is usually in the range of 0.01 to 1 g / m ² .

  In the present invention, a coating layer such as an adhesive layer, an antistatic layer and an oligomer precipitation preventing layer may be provided on the surface where the release layer is not provided, and the polyester film may be subjected to corona treatment, plasma treatment, etc. A surface treatment may be applied.

  Moreover, drying and / or curing (thermal curing, ionizing radiation curing, etc.) of the coating film of the pressure-sensitive adhesive layer or the release layer can be performed individually or simultaneously. When performing simultaneously, it is preferable to carry out at the temperature of 80 degreeC or more. The drying and curing conditions are preferably 80 ° C. or higher and 10 seconds or longer. If the drying temperature is less than 80 ° C. or the curing time is less than 10 seconds, the coating film is incompletely cured, and the coating film tends to fall off.

  In order to make the coated layer of the polyester film of the present invention clean and strong, it is preferable to use a transition metal catalyst. The content of the transition metal catalyst in the coating layer is usually 0.5 to 5.0% by weight, preferably 1.5 to 4.0% by weight. If the content of the transition metal catalyst in the coating layer is lower than 0.5% by weight, it may cause problems such as deterioration of the surface condition due to insufficient peeling force and insufficient curing reaction in the coating layer. On the other hand, when the content of the transition metal catalyst in the coating layer exceeds 5.0% by weight, there is a problem in that costs are increased, reactivity is increased, and gel foreign matter is generated.

In the release polyester film that was kept for one day after the production of the present invention, 3 ml of 1-butanol solution in which 5% by weight of potassium hydroxide was dissolved in a vial (20 mL) was added in order to ensure peeling stability over time. Further, after immersing the release film (40 cm ² ) and heat-treating the vial (20 mL) at 50 ° C. for 1 hour, the amount of hydrogen (H ₂ ) gas generated from the release film can be suppressed to 40 ppm or less. More preferably, it is 30 ppm or less. When the amount of hydrogen (H ₂ ) gas generated from the release film exceeds 40 ppm, when the adhesive layer and the release layer of the release film are pasted together for a long period of time, the variation in peeling over time is large. In a scene that originally needs to be peeled off, there may be problems such as difficulty in peeling.

In the release film in the present invention, as a specific method for suppressing the hydrogen (H ₂ ) gas generation amount to 40 ppm or less, for example, for the purpose of adjusting the release of the release layer, a silicone resin having a small amount of functional groups is used. In the case of using a peeling control agent in combination, a method of selecting a type having a small amount of Si—H group derived from a crosslinking agent is exemplified.

  Conventionally, a person skilled in the art commonly uses a method of adding a large amount of a crosslinking agent for the purpose of increasing the amount of Si-H groups derived from a crosslinking agent, as a method for increasing the peeling force. It is done. However, in this method, as the amount of Si—H groups derived from the crosslinking agent decreases with time due to the influence of moisture absorption or the like, the variation in peeling increases. For this reason, when the release film and the pressure-sensitive adhesive layer are stored in a state of being bonded together for a long time after the application of the pressure-sensitive adhesive, problems such as heavy release occur when the release film is peeled.

The amount of OL extracted from the surface of layer B with dimethylformamide after heat treatment (180 ° C., 10 minutes) of the releasable surface of the polyester film of the present invention is preferably 0.2 mg / m ² or less. Preferably it is 0.1 mg / m ² or less, particularly preferably 0.01 mg / m ² or less. When OL exceeds 0.2 mg / m ² , for example, due to scratches attached with a roll or the like in the adhesion process, OL occurs during heating, resulting in a decrease in transparency of the adhesive and a decrease in adhesive strength of the adhesive layer. In some cases, an inspection process involving optical evaluation may be hindered, and further problems such as process contamination may occur.

  In the release polyester film of the present invention, it is important to optimize the inclination (orientation angle) of the orientation main axis of the release film in order to reduce the generation of foreign matters and light interference colors in optical inspection of the process.

  The orientation angle of the release polyester film of the present invention is usually 12 degrees or less, preferably 9 degrees or less, more preferably 6 degrees or less. When the orientation angle is larger than 12 degrees, in the optical inspection, the light interference color is likely to be seen, and there may be a problem that the foreign matter inspection becomes difficult.

  The heat shrinkage rate in the present invention is an index representing the elongation and shrinkage of the film after the release polyester film is processed and then subjected to any temperature treatment.

  In the release polyester film of the present invention, the shrinkage after heating at 150 ° C. for 30 minutes is the width direction perpendicular to the longitudinal direction of the film (running direction) SMD and the longitudinal direction of the film (running direction) during film formation. It is preferable that the shrinkage ratio of STD is STD, the difference between SMD and STD is 1.5% or less, SMD is 2.5% or less, and TMD is 2.0% or less, more preferably SMD and The STD difference is 1.0% or less, the SMD is 2.0% or less, and the TMD is 1.5% or less. If the SMD is 2.5% and the STD is greater than 2.0%, the dimensional deformation may be significant and the thickness may become uneven in the pressure-sensitive adhesive heating process. May cause a malfunction.

  Means for satisfying the range of the inclination (orientation angle) of the orientation main axis of the release polyester film of the present invention and the range of the heat shrinkage rate at 150 ° C. for 30 minutes reduces productivity as a stretching condition during film formation. In other words, the ratio of the draw ratio and the drawing temperature are devised.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measurement method and evaluation method used in the present invention are as follows.

(1) Measurement of intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. It was dissolved and measured at 30 ° C.

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

(3) Measuring method of amount of oligomer contained in polyester raw material About 200 mg of the polyester raw material is weighed and dissolved in 2 ml of a mixed solvent of chloroform / HFIP (hexafluoro-2-isopropanol) ratio 3: 2. After dissolution, add 20 ml of chloroform, and then add 10 ml of methanol little by little. The precipitate is removed by filtration, and the precipitate is further washed with a mixed solvent having a chloroform / methanol ratio of 2: 1. The filtrate / washing solution is collected, concentrated by an evaporator, and then dried. After the dried product was dissolved in 25 ml of DMF (dimethylformamide), this solution was supplied to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A) to determine the amount of oligomer in DMF, and this value was obtained as a chloroform / HFIP mixed solvent. Divide by the amount of the polyester raw material dissolved in the amount to make the amount of oligomers contained (% by weight). The amount of oligomer in DMF was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method).

  The standard sample was prepared by accurately weighing an oligomer (cyclic trimer) collected in advance and dissolving it in accurately measured DMF. The concentration of the standard sample is preferably in the range of 0.001 to 0.01 mg / ml.

  The conditions for the liquid chromatograph were as follows.

Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

(4) Thickness of Laminated Polyester Layer After fixing a small piece of film with an epoxy resin, it was cut with a microtome, and the cross section of the film was observed with a transmission electron micrograph. Two of the cross-sections are observed in parallel with the film surface, and the interface is observed by light and dark. The distance between the two interfaces and the film surface was measured from 10 photographs, and the average value was defined as the laminated thickness.

(5) Measurement of solution haze of coating solution Using a Nippon Denshoku haze meter NDH-300A, the coating solution was put into a quartz cell and measured by a transmission method. An average value of three measurements was adopted.

(6) B layer surface side surface roughness measurement Using AFM Nano-R manufactured by Toyo Technica, a coating solution was applied to a polyester film and dried to obtain a measurement sample. In the contact mode, the surface roughness Sa (nm) was measured in a measurement range of 5 μm × 5 μm. Three average values were used.

(7) Coat thickness of coating layers (A) and (B) A cross section of the release polyester film was cut out by a freezing ultrathin section method, and a transmission electron microscope H manufactured by Hitachi, Ltd. was prepared by a stained ultrathin section method by RuO ₄ staining. Using a −7100FA type, the laminated film portion was observed and photographed at an acceleration voltage of 100 kV. The thickness of the laminated film was measured from the cross-sectional photograph.

(8) Evaluation of peeling force (F) on the C layer surface side Affixed with one side of a double-sided adhesive tape (Nitto Denko “No. 502”) on the surface of the release layer of the sample film, then cut to a size of 50 mm × 300 mm After that, the peel strength 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 peeling force (F) on the C layer surface side is represented by gf / 50 mm.

(9) Quantification of amount of hydrogen (H ₂ ) gas generated after heat treatment on C layer surface side A sample film of 40 cm ² is cut out in advance and weighed with respect to the release polyester film placed for 1 day after the production. Again cut out amount to be used for measuring the ^second corner 5 mm, (corresponding to about 0.213g in release film 38 [mu] m) of gas chromatography dedicated 20ml vial filling sample film. Next, 3 ml of a butanol solution in which 5% by weight of potassium hydroxide is dissolved (prepared by adding 1 g of potassium hydroxide to 19 g of butanol) is sampled with a pipetter, and the entire sample film is immersed in a 5% by weight of potassium hydroxide butanol solution. Add as follows. Thereafter, the vial is sealed using a crimper, and heat-treated at 50 ° C. for 1 hour using a heating block (model: HF21, manufactured by Yamato Kagaku). Thereafter, the amount of hydrogen (H ₂ ) gas generated from the sample film is quantitatively analyzed using the following gas chromatography measuring device, and judged according to the following criteria.

<< Gas chromatography measurement conditions >>
Equipment: EAGanalyzer (SENSORTEC Co, Ltd)
Measurement conditions: pressure Gauge Low: 0.05 MPa High: 0.05 MPa
Column temperature: 50 ° C
Column flow rate: 30.0sccm
Syringe injection volume: 1cc
Measurement time: 5 minutes << Criteria >>
○: 40 ppm or less (practical level)
X: Exceeding 40 ppm (practical level)

(10) Release characteristics on the C layer surface side The release characteristics were evaluated from the situation when the release film was peeled off from the laminated film having the adhesive layer. Judgment is based on the following criteria.
<Criteria>
○: The release film is peeled off cleanly, and the phenomenon that the adhesive adheres to the release layer is not observed. Δ: The release film peels off, but the adhesive adheres to the release layer when peeled off at a high speed. : Adhesive adheres to the release film

(11) Coating layer adhesion on the C layer surface side The release film was rubbed with a finger three times, and then a tape was applied to the rubbed portion to evaluate whether there was a catch when the tape was peeled off. Judgment is based on the following criteria.
<Criteria>
○: As with the case before rubbing with a finger, it does not feel a catch when the tape is peeled.

(12) Measurement of orientation (orientation angle) of orientation axis of release polyester film Using a polarizing microscope manufactured by Carl Zeiss, the orientation of the polyester film is observed. The number of tilts with respect to the width direction was measured to determine the orientation angle. This measurement was carried out at a total of three locations on the center and both ends of the film, and the largest orientation angle value among the three locations was taken as the maximum orientation angle.

(13) Measurement of transmittance of release polyester film According to JIS-K7105, the total light transmittance of the release polyester film was measured with an integrating sphere turbidimeter NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd.

(14) Haze (turbidity) measurement of release polyester film The total light transmittance of the release polyester film was measured with an integrating sphere turbidimeter NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS-K7105.

(15) Measurement of Heat Shrinkage Ratio of Release Polyester Film For the release polyester film, the shrinkage rate in the film running direction is SMD and the shrinkage rate in the width direction perpendicular to the transverse film running direction is STD. cm). Subsequently, the sample is heated in an oven at 150 ° C. for 30 minutes, and the sample is taken out of the oven and the length l (cm) is measured. This operation is performed three times, and the average value is adopted as the value of the heat shrinkage rate. The heat shrinkage rate can be calculated by the following formula.
Heat shrinkage (%) = S = {(L−l) / L} × 100

(16) Measurement of OL extracted from surface of layer B In advance, an unheated release film is heated in air at 180 ° C. for 10 minutes. After that, the heat-treated film is brought into close contact with the inner surface of a box having a top and width of 10 cm and a height of 3 cm, and the box shape is obtained. When the coating layer is provided, the coating layer surface is set to the inside. Next, 4 ml of DMF (dimethylformamide) is placed in the box prepared by the above method and left for 3 minutes, and then DMF is recovered. The recovered DMF was supplied to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A) to determine the amount of OL in DMF, and this value was divided by the area of the film in contact with DMF to obtain the amount of film surface OL (mg / M ² ).

  The amount of oligomer in DMF was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method). The standard sample was prepared by accurately weighing OL (cyclic trimer) collected in advance and dissolving it in DMF accurately weighed. The concentration of the standard sample is preferably in the range of 0.001 to 0.01 mg / ml. The conditions for the liquid chromatograph were as follows.

Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm
The quality of the surface OL is judged based on the following criteria.
<Criteria>
○: Value is lower than 0.15 mg / m ² Δ: 0.15 to 0.20 mg / m ²
×: Value higher than 0.20 mg / m ²

(17) Appearance and visual evaluation of film provided with layer B Appearance defects due to the thickness of the coating film were evaluated. Evaluation was performed according to the following criteria. Judgment is based on the following criteria.
<Criteria>
○: Transparent and beautiful △: Slightly whitish ×: Cloudy white

(18) Foreign matter inspection (visual)
A) It was evaluated whether transparency was maintained and foreign objects and scratches were easily found when inspected by a transmission and reflection method under a fluorescent lamp. In the observation, A4 size samples were cut out from a total of three locations in the center and both ends in the width direction of the obtained film.
B) Taking the polarizing plate inspection into consideration, the width direction of the release film obtained by applying a release agent on the film and having a dryer temperature of 120 ° C. and a line speed of 30 m / min is parallel to the alignment axis of the polarizing film. The release film was adhered to the polarizing film through an adhesive so that a polarizing plate was obtained. Here, when the polarizing plate was prepared, black metal powder (foreign matter) having a size of 50 μm or more was mixed between the pressure-sensitive adhesive and the polarizing film so as to be 50 / m ² . A polarizing plate for inspection is superimposed on the polarizing plate release film mixed with the foreign matter thus obtained so that the orientation axis is orthogonal to the width direction of the release film, and white light is irradiated from the polarizing plate side. Then, it was visually observed from a polarizing plate for inspection, and whether or not a foreign matter mixed between the adhesive and the polarizing film was found under crossed Nicols was evaluated according to the following criteria. In the observation, A4 size samples were cut out from a total of three locations in the center and both ends in the width direction of the obtained film. Judgment is based on the following criteria.
<Criteria>
○: Good foreign object recognition △: Foreign object can be recognized with relatively no problem.
×: Foreign matter recognition poor ○ and Δ are at a level where there is no problem in actual use.

(19) Release film formation and processing productivity When producing a polyester film, the film formation yield is evaluated from the film breakage and film formation characteristics due to stretching conditions. Further, in the subsequent B-layer and C-layer deposition, the processing yield including appearance and characteristics is evaluated. Judgment is based on the following criteria.
<Criteria>
○: Sufficient continuity can be secured (level that can be implemented and sold)
X: Sufficient continuity cannot be ensured (it is difficult to implement and costs do not match)

(20) Adhesive Processing Characteristics A) Adhesive Processing Step Roll Dirt In the pressure-sensitive adhesive step, the roll contamination of the heating roll and / or metal roll when using a release film quantitatively was evaluated. Judgment is based on the following criteria.
<Criteria>
○: Roll stain does not occur even if processed over 10,000m (practicable level)
X: Roll dirt occurs before processing 10,000 m (level at which implementation is difficult)
B) Adhesive processing step contamination The degree of contamination in the adhesive drying step when a release film was quantitatively used in the adhesive step was evaluated. Judgment is based on the following criteria.
<Criteria>
○ Contamination is not noticeable even after 1 week of production (practical level)
×: Whitish contamination occurs before production for 1 week (difficult to implement)
C) Pressure-sensitive adhesive processing productivity In the pressure-sensitive adhesive process, it was comprehensively evaluated whether the above-mentioned A) and B) were not satisfied, and the foreign matter inspection property was poor, resulting in defects. Judgment is based on the following criteria.
<Criteria>
○: Adhesive process is not contaminated and foreign matter inspection is good (practicable level)
X: There is pressure-sensitive adhesive process contamination, or the foreign matter inspection property is poor (level that is difficult to implement)

(21) Appropriate use of separator for polarizing plate member pressure-sensitive adhesive As a release film for polarizing plate pressure-sensitive adhesive, pressure-sensitive adhesive coating can be performed without problems, and foreign matter recognition after product production can be performed. Judgment is based on the following criteria.
<Criteria>
○: Appropriate for use, can be used ×: Not appropriate for use, difficult to use

(22) Appropriate Separator for General Optical Member Adhesive Use For general tapes and as a release film for new adhesives (especially highly transparent type), adhesive coating can be performed without problems. Judgment is based on the following criteria.
<Criteria>
○: Appropriate for use, can be used ×: Not appropriate for use, difficult to use

The polyester used in the examples and comparative examples was prepared as follows.
<Method for producing polyester (a)>
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 obtained polyester (a) had an intrinsic viscosity of 0.65 and an oligomer (cyclic trimer) content of 0.97% by weight.

<Method for producing polyester (b)>
“UVA3000PET” (polyester (b) manufactured by BASF Japan Ltd.) was used as a polyester masterbatch containing 30% by weight of an epoxy group-containing polymer. The intrinsic viscosity was 0.51.

<Method for producing polyester (c)>
In the production method of polyester (a), after adding 0.04 part of ethyl acid phosphate, 0.2 part of silica particles dispersed in ethylene glycol having an average particle diameter of 1.6 μm and 0.04 part of antimony trioxide are added. In addition, polyester (c) was obtained using the same method as the production method of polyester (a) except that the polycondensation reaction was stopped at the time corresponding to the intrinsic viscosity of 0.65. The obtained polyester (c) had an intrinsic viscosity of 0.65 and an oligomer (cyclic trimer) content of 0.82% by weight.

Example 1:
A mixed raw material obtained by mixing the polyesters (a), (b) and (c) at a ratio of 84.0% by weight, 1.0% by weight and 15% by weight, respectively, was used as a raw material for the surface layer (I layer), and polyester (a ) 100% of the raw material was used as a raw material for the intermediate layer (II layer), and each was supplied to two extruders, melted at 285 ° C., and then the I layer as the outermost layer (surface layer) and the II layer as the intermediate layer On a casting drum cooled to 40 ° C., two types and three layers (I / II / I) were coextruded so that the thickness composition ratio was I: II: I = 6: 26: 6, and cooled and solidified. An oriented sheet was obtained. Next, the film was stretched 2.8 times in the machine direction at a film temperature of 100 ° C. using the roll peripheral speed difference, and then the coating amount (after drying) of the following coating agent was applied to one side of the machine film. After coating to 03 g / m ² , it was guided to a tenter, stretched 5.1 times at 120 ° C. in the transverse direction, heat-treated at 220 ° C. for 10 seconds, and then relaxed 4% in the width direction at 180 ° C. Was added to obtain a polyester film (I) having a width of 4500 mm and a thickness of 38 μm having an A layer (6 μm for each surface layer and 26 μm for the intermediate layer).

In addition, the compound used in order to comprise A layer is as follows.
(Example compounds)
-Quaternary ammonium base-containing polymer (A1):
2-hydroxy-3-methacryloxypropyltrimethylammonium salt polymer Counter ion: methyl sulfonate Number average molecular weight: 30000
-Polyethylene glycol-containing acrylate polymer (B1):
Polyethylene glycol-containing monoacrylate polymer Number average molecular weight: 20000
-Polyethylene glycol-containing acrylate polymer (B2):
Octoxy polyethylene glycol-polypropylene glycol monoacrylate polymer Number average molecular weight: 32000
・ Crosslinking agent (C1): Melamine crosslinking agent (DIC Corporation: Becamine “MAS”)
・ Crosslinking agent (C2): Oxazoline crosslinking agent (Nippon Shokubai: Epocross “WS500”)
Particle (D1): Alumina surface modified colloidal silica (average particle size: 50 nm)
Particle (D2): colloidal silica (average particle diameter: 70 nm)

The following coating agent was applied on the A layer of the obtained polyester film by a reverse gravure coating method so that the coating amount (after drying) was 0.05 g / m ^2, and then heat-treated at 120 ° C. for 30 seconds. A laminated polyester film provided with a layer was obtained.
In addition, the coating agent composition used in order to comprise B layer is as follows.
<< Coating composition >>
Organosiloxane (ethyl silicate 48: Colcoat Co.): 0.9% by weight (based on 100% by weight of solvent)
The mixture was diluted with a mixed solvent of i-propanol / butanol = 6/4 to give 0.9% by weight.

A reverse gravure coating method so that a coating amount (after drying) of a release agent having a release agent composition shown below is 0.1 g / m ² on the opposite surfaces of the A and B layers of the obtained laminated polyester film. The layer C was installed under the conditions of a dryer temperature of 120 ° C. and a line speed of 30 m / min to obtain a roll-shaped release polyester film.

In addition, the mold release agent composition used in order to comprise C layer is as follows.
<Releasing agent composition>
Curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical) 20 parts Catalyst (PL-50T: manufactured by Shin-Etsu Chemical) 0.3 parts (1.5% by weight)
MEK / toluene mixed solvent (mixing ratio is 1: 1)

Examples 2-9:
In Example 1, it manufactured like Example 1 except having changed the raw material compounding quantity of a film, the change of film forming extending | stretching conditions, and B layer application | coating thickness, and obtained the release polyester film. The evaluation results of the produced release polyester film were as shown in Tables 1 and 2.

Comparative Examples 1-7:
In Example 1, it manufactured like Example 1 except having changed the raw material compounding quantity of a film, the change of film forming extending | stretching conditions, and B layer application | coating thickness, and obtained the release polyester film. The evaluation results of the produced release polyester film were as shown in Tables 3 and 4. Comparative Example 1 is an example in which the B layer is not provided.
Comparative Example 8:
In Example 1, it is the same method as Example 1 except having mixed polyester (a), (b), (c) as a raw material of I layer in the ratio of 75%, 10%, and 15%, respectively. A polyester film was tried. When the film was formed, an excessive load was applied to the extruder for the I layer, and a laminated polyester film could not be obtained (Table 3).

  Since the release polyester film of the present invention prevents contamination of the pressure-sensitive adhesive process and increases the pressure-sensitive adhesive processing yield, it can be suitably used for optical applications where quality control is severe with respect to foreign matters caused by OL.

10 Polyester intermediate layer: I layer 11 Polyester surface layer: II layer 11 ′ Polyester surface layer: II layer 12 Coating layer: A layer 13 Coating layer: B layer 14 Release layer: C layer

Claims (2)

It is a laminated polyester film having a laminated structure of at least 3 layers, in which polyester containing 3000 to 30000 ppm of a polymer having at least two epoxy groups in the molecular chain is used as both surface layers. The coating agent which has a coating layer obtained by apply | coating the coating liquid containing a quaternary ammonium base containing polymer, a polyethyleneglycol containing acrylate polymer, and a crosslinking agent, and contains at least 1 type of organosiloxane compound on the said coating layer A release polyester film characterized by having a coating layer having a thickness of 10 to 100 nm formed by coating and having a release layer on the other surface. The mold release polyester film according to claim 1, wherein the inclination (orientation angle) of the orientation main axis is 12 degrees or less, and the heat shrinkage ratio after treatment at 150 ° C for 30 minutes simultaneously satisfies the following formulas (1) to (3).
SMD-STD ≦ 1.5 (1)
SMD ≦ 2.5 (2)
STD ≦ 2.0 (3)
(In the above formula, SMD means shrinkage rate (%) in the film longitudinal direction, and STD means shrinkage rate (%) in the film width direction)

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