JP5553704B2 - Release polyester film - Google Patents

Description

  The present invention relates to a release polyester film suitable for use in a substrate-less double-sided pressure-sensitive adhesive sheet or a polarizing plate substrate for optical applications.

  In the process of attaching a release polyester film for a substrate-less double-sided pressure-sensitive adhesive sheet or a polarizing plate separator to a polarizing plate to make a product, a punching operation may be performed to cut the entire release polyester film.

  In this punching operation, cutting during processing of the polyester film, that is, difficulty in generating dust and the like when the polyester film is cut out is important.

  In polarizing plate substrate applications where the inspection of foreign materials and scratches is severe, if dust or dirt on the polarizing plate or polyester film is generated during the punching operation, it may become a foreign material to the adhesive used, which reduces productivity. Invite.

  In addition, when a release polyester film is used for optical applications such as a polarizing plate base material in this way, an optical inspection for finding foreign matter or the like may be performed with the polarizing plate attached. For this reason, defects such as foreign matters have become more important than ever.

  As one of the causes of the generation of foreign substances, an oligomer (hereinafter sometimes abbreviated as OL) contained in a polyester film is considered. OL, which is considered to be a low molecular weight sublimate of polyester, is deposited on the surface of the film within the production process and adheres to a roll or the like that comes into contact with the film to become a foreign matter. Moreover, in order to reduce a foreign material, although the operation | work which removes the oligomer adhering to a roll is performed, the problem that production efficiency worsens is also mentioned.

JP 2003-231214 A JP 2002-361737 A Japanese Patent Application No. 2001-301024 Japanese Patent Application No. 2010-121101 JP 2009-220296 A Japanese Patent Application No. 2009-188230

  The present invention has been made in view of the above circumstances, and the problem to be solved is that when a release polyester film is used for optical applications, for example, a touch panel, a liquid crystal deflecting plate, a retardation plate, etc., after applying a polarizing plate. When there is a punching process to the corresponding product size, dust is generated at the time of punching, process contamination, traces of dust on the adhesive remain, or heating in the polarizing plate attaching process, or An object of the present invention is to provide an inexpensive release polyester film that solves problems such as deterioration of productivity due to generation of oligomer (OL) due to pressurization and cost.

  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 that a polyester layer B having a melting point (TmB) in the range of 180 to 225 ° C. and a laminated polyester film having at least one layer A adjacent to the layer B as a base material, The melting point (TmA) is higher than the melting point of layer B, the difference between the melting points (TmA-TmB) is in the range of 10 to 40 ° C., and the coating layer obtained by coating a coating solution containing polyvinyl alcohol is formed on layer A And having a silicone release layer containing 0.5 to 5.0% by weight of at least one transition metal catalyst on the coating layer.

  According to the present invention, in a production process of a polarizing plate substrate, a release polyester film that is easily punched, that is, easily cut out, is a release polyester film in which dust and the like are not easily generated, and process contamination and optical properties. Since a release polyester film having advantageous low OL performance in inspection can be provided, its industrial value is high.

  The polyester constituting the film of the present invention is preferably terephthalic acid as the dicarboxylic acid component. Besides these, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, One or more known dicarboxylic acids such as naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, and cyclohexanedicarboxylic acid may be included as a copolymerization component. The diol component is preferably ethylene glycol. Besides these, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, One or more known diols such as neopentyl glycol may be included as a copolymerization component.

  In the present invention, it is effective to adjust the amount of the third component in order to keep the melting point of each layer of the film within a specified range.

  Examples of the polymerization catalyst include antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds, and titanium compounds. Titanium compounds include, for example, tetraalkyl titanates, tetraaryl titanates, titanyl oxalate salts, titanyl oxalate, chelate compounds containing titanium, titanium tetracarboxylates, and specifically tetraethyl titanate, tetrapropyl titanate, tetraphenyl Examples thereof include titanate or a partial hydrolyzate thereof, titanyl ammonium oxalate, potassium titanyl oxalate, titanium triacetylacetonate and the like.

  In addition, it is preferable to add inorganic particles, organic salt particles and crosslinked polymer particles to the polyester film of the present invention. Inorganic particles that can be used include calcium carbonate, kaolin, talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, Examples thereof include lithium fluoride. On the other hand, examples of the organic salt particles include calcium oxalate, terephthalate such as calcium, barium, zinc, manganese, and magnesium. Examples of the crosslinked polymer particles include divinylbenzene, styrene, acrylic acid, methacrylic acid, acrylic acid or a methacrylic acid vinyl monomer homopolymer or copolymer. In addition, organic particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, and thermosetting phenol resin may be used.

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 about the hardness, specific gravity, a color, etc.
These series of particles may be used in combination of two or more as required.

  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, but the polycondensation reaction may proceed preferably after the esterification stage or after the transesterification reaction. 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 to the above-mentioned particles, conventionally known antioxidants, heat stabilizers, lubricants, antistatic agents, fluorescent brighteners, dyes, pigments, and the like are added to the polyester film in the present invention as necessary. be able to.

  The total thickness of the polyester film of the present invention is not particularly limited because it is appropriately selected depending on the use for which the polyester film of the present invention is used, but is preferably 12 from the viewpoint of mechanical strength, handling properties, and productivity. ˜100 μm.

  The polyester film used as the base material of the present invention needs a multilayer structure. By making at least one outer layer a skin layer that is resistant to solvents, both punchability and solvent resistance can be achieved.

  The method for achieving the multilayer structure is not particularly limited, but two or three or more layers of films are obtained by a so-called coextrusion method using two or three or more melt extruders because of its economical efficiency. It is preferable.

  Next, formation of the coating layer for the purpose of OL sealing which comprises the polyester film of this invention is demonstrated. As for the coating 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 manufactured, and may employ both offline coating. You may use together. 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 the coating layer can be changed by the draw ratio.

  The in-line coating is not limited to the following, but for example, in the sequential biaxial stretching, the coating treatment can be performed 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.

  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.

  Specific examples of the binder polymer include polyester resin, acrylic resin, urethane resin, polyvinyl (polyvinyl alcohol, polyvinyl chloride, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkylene imine, methyl cellulose, hydroxy cellulose, and starch. And the like.

  Furthermore, a crosslinking agent can be used in the coating layer as long as the gist of the present invention is not impaired. Various known resins can be used as the crosslinking agent, and examples thereof include melamine compounds, epoxy compounds, oxazoline compounds, and isocyanate compounds. A melamine compound is more preferable because it can be designed to have a higher refractive index.

Examples of the melamine compound in the present invention include methoxymethylated melamine and butoxymethylated melamine which are alkylol or alkoxyalkylolated melamine compounds, and those obtained by co-condensing urea or the like with a part of melamine can also be used. .

Respect 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,} more preferably 0 The range is from 0.01 to 0.2 g / m ² . If the film thickness is less than 0.002 g / m ^2, sufficient adhesion may not be obtained, and if it exceeds 1.0 g / m ² , the appearance, transparency, and film blocking properties may be deteriorated. There is sex.

  In the polyester film of the present invention, examples of the method for providing the coating 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 coating 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 coating layer is provided by in-line coating, heat treatment is usually performed 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 the coating layer for the purpose of OL sealing which comprises the polyester film of this invention is demonstrated. As for the coating 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 manufactured, and may employ both offline coating. You may use together. 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 the coating layer can be changed by the draw ratio.

  The in-line coating is not limited to the following, but for example, in the sequential biaxial stretching, the coating treatment can be performed 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, it is normal to use a binder polymer in the coating layer. The binder polymer is a gel permeation according to a high molecular compound safety evaluation flow scheme (sponsored by the Chemical Substance Council in November 1985). It is defined as a high molecular compound having a number average molecular weight (Mn) of 1000 or more as measured by ablation chromatography (GPC) and having film-forming properties.

  Analysis of the components in the coating 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.

  In order to achieve the above object, in the present invention, an oligomer precipitation preventing layer is formed on the film surface by coating, and the layer comprises 10 to 100% by weight of polyvinyl alcohol, preferably 20 to 90% by weight, more preferably 30 to 30%. It shall contain 90% by weight. If the content of polyvinyl alcohol is less than 10% by weight, the oligomer sealing effect is insufficient, which is not preferable.

  The polyvinyl alcohol used in the present invention can be synthesized by a normal polymerization reaction and is preferably water-soluble. The degree of polymerization of polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably 300 to 40,000. When the degree of polymerization is 100 or less, the water resistance of the coating layer tends to decrease. The degree of saponification of the polyvinyl alcohol used in the present invention is not particularly limited, but a polyvinyl acetate saponified product that is usually 70 mol% or more, preferably 80 mol% or more and 99.9 mol% or less is practically used. It is done.

  In the oligomer precipitation preventing layer in the present invention, a water-soluble or water-dispersible binder resin other than the above-mentioned polyvinyl alcohol may be used in combination as necessary. Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, acrylate resin, and the like. In these, each skeleton structure may have a composite structure substantially by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, vinyl resin graft polyurethane, and acrylate resin graft polyethylene glycol. The blending amount of the binder component is preferably 50 parts by weight or less, and more preferably 30 parts by weight or less in terms of parts by weight with respect to the coating layer. Furthermore, the coating layer of the film of the present invention may contain a crosslinking reactive compound as required.

  Crosslinking reactive compounds include methylolated or alkylolated urea, melamine, guanamine, acrylamide, polyamide and other compounds, polyamines, epoxy compounds, oxazoline compounds, aziridine compounds, blocked isocyanate compounds, silane cups Polyfunctional low molecular weight compounds such as ring agents, titanium coupling agents, zirco-aluminate coupling agents, metal chelates, organic acid anhydrides, organic peroxides, thermally or photoreactive vinyl compounds and photosensitive resins, and It is selected from polymer compounds.

  Crosslinkable compounds improve the cohesiveness, surface hardness, scratch resistance, solvent resistance, and water resistance of the easy-adhesive resin layer mainly by cross-linking reaction with the functional groups of the resin contained in the easy-adhesive resin layer. can do. For example, when the functional group of the easily adhesive resin is a hydroxyl group, the crosslinking reactive compound is preferably a melamine compound, a blocked isocyanate compound, an organic acid anhydride, or the like, and the functional group of the easily adhesive polyester is an organic acid or an anhydride thereof. In this case, epoxy-based compounds, melamine-based compounds, oxazoline-based compounds, metal chelates and the like are preferable as the cross-linking reactive compound, and when the functional group of the easily adhesive resin is an amine, an epoxy-based compound is preferable as the cross-linking reactive compound. It is preferable to select and use a functional group contained in the easily adhesive resin and one having a high crosslinking reaction efficiency. Examples of the melamine compound in the present invention include methoxymethylated melamine and butoxymethylated melamine which are alkylol or alkoxyalkylolated melamine compounds, and those obtained by co-condensing urea or the like with a part of melamine can also be used. .

The cross-linking reactive compound may be either a low molecular weight compound or a high molecular polymer having a reactive functional group as long as the reactive functional group is always contained in two or more functional groups in one molecule. The compounding amount of the crosslinking reactive compound is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and particularly preferably 15 parts by weight or less in terms of parts by weight with respect to the easily adhesive resin layer.
Furthermore, the easily adhesive resin layer of the present invention may contain inert particles for improving the slipperiness of the coating layer, if necessary.

  Examples of the inert particles include inorganic inert particles and organic inert particles. Examples of the inorganic inert particles include silica sol, alumina sol, calcium carbonate, and titanium oxide. Examples of the organic inert particles include fine particles containing a single or copolymer of polystyrene resin, polyacrylic resin, and polyvinyl resin, or organic particles represented by crosslinked particles in which these and a crosslinking component are combined. These inert particles preferably have a softening temperature or decomposition temperature of about 200 ° C. or higher, more preferably 250 ° C. or higher, particularly 300 ° C. or higher. The average particle diameter (d) of the inert particles is 1/3 ≦ d / L ≦ 3, and further 1/2 ≦ d / L ≦ 2, when the average film thickness of the easily adhesive resin layer is (L). It is preferable to select so as to satisfy the relationship.

  The OL sealing layer of the present invention comprises a surfactant, an antifoaming agent, a coating property improver, a thickener, a low molecular antistatic agent, an organic lubricant, an antioxidant, an ultraviolet absorber, and foam as necessary. A small amount of additives such as additives, dyes and pigments may be contained. These additives may be used alone or in combination of two or more as necessary. The coating layer of the film of the present invention may be formed only on one side of the polyester film or on both sides. In the case of forming only on one side, another type of coating layer can be formed on the opposite side as required, and further properties can be imparted. In addition, in order to improve the applicability | paintability and adhesiveness to the film of a coating liquid, you may give a chemical process, an electrical discharge process, etc. to the film before application | coating.

Respect 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,} more preferably 0 The range is from 0.01 to 0.2 g / m ² . If the film thickness is less than 0.002 g / m ^2, sufficient adhesion may not be obtained, and if it exceeds 1.0 g / m ² , the appearance, transparency, and film blocking properties may be deteriorated. There is sex.

  In the polyester film of the present invention, examples of the method for providing the coating 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 coating 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 coating layer is provided by in-line coating, heat treatment is usually performed 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.

  The OL sealing layer of the polyester film of the present invention is preferably formed by blending a binder resin and a crosslinking agent in an arbitrary ratio. In this case, since the layer forms a barrier layer densely, the OL is suppressed. be able to. For this reason, there is an effect that OL from the polyester film is not attached to the adhesive as much as possible and is not produced in the previous processing step. Therefore, both sides of the OL sealing layer of the polyester film of the present invention are preferable, and it is necessary to apply at least one side according to the application.

  Although the method in particular of forming a silicone type coating layer in the outermost surface of the polyester film of this invention is not restrict | limited, The method of apply | coating a coating liquid in the process of manufacturing a polyester film is employ | adopted suitably. Specifically, a method of applying and drying a coating solution on the surface of an unstretched sheet, a method of applying and drying a coating solution on the surface of a uniaxially stretched film, and a method of applying and drying a coating solution on the surface of a biaxially stretched film Etc. Among these, it is economical to apply a coating solution to the surface of an unstretched film or a uniaxially stretched film, and then simultaneously dry and cure the coating layer in the process of heat treatment on the film. Moreover, as a method for forming the coating layer, a method in which some of the above-described coating methods are used in combination can be adopted as necessary. Specifically, a method of applying a first layer on the surface of an unstretched sheet and drying, then stretching in a uniaxial direction, and then applying and drying a second layer can be used. Use the reverse roll coater, gravure coater, rod coater, air doctor coater, etc. shown in “Coating Method” by Yuji Harasaki, Tsuji Shoten, published in 1979, as a method of applying the coating solution to the surface of the polyester film. Can do.

  In the present invention, the release layer formed on the coating layer 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 include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, Dow manufactured by Shin-Etsu Chemical Co., Ltd. -Corning Asia Co., Ltd. DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210, Toshiba Silicone Co., Ltd. YSR-3022, TPR-6700, TPR-6720, TPR-6721, Toray Dow Corning Co., Ltd. SD7220, SD7226, SD7229, etc. are mentioned. 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 coating amount of the release layer in the present invention is usually in the range of 0.01 to 1 g / m2.

  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. When the drying temperature is less than 80 ° C. or the curing time is less than 10 seconds, the coating film is not completely cured, and the coating film tends to fall off, which is not preferable.

In the polyester film in the present invention, a transition metal catalyst is used in order to make the coating layer clean and strong. The transition metal catalyst content in the coating layer is in the range of 0.5 to 5.0% by weight, preferably 1.5 to 4.0% by weight. When the content of the transition metal catalyst in the coating layer is lower than 0.5% by weight, there may be a problem such as deterioration of the surface condition due to insufficient peeling force or insufficient curing reaction in the coating layer. On the other hand, if the content of the transition metal catalyst in the coating layer exceeds 5.0% by weight, the cost is increased, the reactivity is increased, and gel defects are generated. End up.

  In the present invention, it is a polyester film having a base layer B and at least one outer layer A adjacent to the B layer, wherein the base layer B has a melting point (TmB) in the range of 180 to 225 ° C., and the melting point of the layer A ( TmA) is higher than the melting point of the base layer B, and the difference between the melting points (TmA−TmB) needs to be 10 to 40 ° C. In this case, the solvent resistance of the polyester film is good when the release layer is applied, and there is an advantage that dust does not easily occur during the punching operation after applying the polarizing plate. When the melting point (TmB) of the base layer of the film is less than 180 ° C., a temperature such as when a coating layer is provided and when a temperature is applied during the production of a polarizing plate, a phenomenon such as opening or tearing may occur. Many are inferior in heat resistance. When the melting point (TmB) of the base layer is higher than 225 ° C., the film is not deformed particularly at low temperature and low pressure, and the moldability is poor. When the difference in melting point (TmA-TmB) is less than 10 ° C, it has two properties such as poor film punchability when the film is provided with solvent resistance necessary for surface treatment. It is difficult to do. When the difference in melting point (TmA-TmB) is larger than 40 ° C., a phenomenon occurs in which a crack occurs between the base layer B and the outer layer A when the film is deformed and peels at the interface.

  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) Polyester composition The polyester film was dissolved in deuterated trifluoroacetic acid and analyzed by ¹ H-NMR method to determine isophthalic acid content and 1,4-cyclohexanedimethanol content.

(3) Measurement of average particle diameter (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.

(4) Evaluation of release film release force (F) After applying one side of a double-sided adhesive tape (Nitto Denko “No. 502”) to the surface of the release layer of the sample film, cut into 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.

(5) Measurement of OL extracted from anchor layer surface An unheat-treated release film is heated in air at 180 ° C. for 10 minutes in advance. 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

(6) Measurement of Melting Peak Temperature (Tm) by DSC Measurement of Release Polyester Film Using a differential scanning calorimeter “MDSC 2920 type” manufactured by TA Instruments Inc., about 5 mg of polyester resin is added at 0 ° C. to 300 ° C. The temperature of the endothermic peak accompanying melting obtained when the temperature was raised at a rate of 20 ° C./min until Tm was defined as Tm. Of the melting peak temperatures obtained by the above-mentioned method, only the outer layer (A layer) of the formed film was sampled and measured, and the melting peak temperature was defined as the matte outer layer A (TmA), and the outer layer of the formed film ( The melting peak temperature obtained from the film from which layer A) was removed was taken as the melting point (TmB) of base layer B, and the difference in melting points = (TmA) − (TmB) was determined.
○: TmB: 180 to 225 ° C range, TmA-TmB: 10 to 40 ° C range ×: TmB: smaller than 180 ° C, higher than 225 ° C, TmA-TmB: smaller than 10 ° C, higher than ° C

(7) Punching property The ease of punching cut when the polarizing plate and the release polyester film were bonded to each other in a desired size was evaluated. Judgment is based on the following criteria.
○: It can be cut cleanly, and almost no dust is generated at the time of cutting ×: There is a catch, and dust is generated at the time of cutting

(8) Peeling property after punching <Release property>
The release characteristics were evaluated from the situation when the polarizing plate having the adhesive layer and the release film were peeled off. Judgment is based on the following 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

(9) Comprehensive evaluation An evaluation is performed in consideration of all of the production yield and productivity from the punchability and peeling characteristics. Judgment is based on the following criteria.
○: Productivity is high enough to be supplied as a product ×: Productivity is poor or peeling property problems frequently occur

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, adding tetrabutoxy titanate as a catalyst to the reactor, setting the reaction start temperature to 150 ° C., and gradually increasing the reaction temperature as methanol is distilled off. It was 230 degreeC after 3 hours. After 4 hours, the transesterification reaction was substantially completed, and then a polycondensation reaction was performed 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 0.61 due to a change in the stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure to obtain a polyester (a) having an intrinsic viscosity of 0.61.

<Method for producing polyester (b)>
In the method for producing polyester (a), after adding ethyl acid phosphate, an ethylene glycol slurry of synthetic calcium carbonate particles having an average particle diameter of 0.8 μm was added so that the content of the particles with respect to polyester was 1% by weight. Obtained polyester (b) using the method similar to the manufacturing method of polyester (a). The obtained polyester (b) had an intrinsic viscosity of 0.60.

<Production of polyester (c)>
Starting from 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, magnesium acetate tetrahydrate is added as a catalyst to the reactor, the reaction start temperature is 150 ° C., and the reaction temperature is gradually increased as methanol is distilled off. The temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. Ethyl acid phosphate was added to the reaction mixture, which was then transferred to a polycondensation tank, and 0.04 part of antimony trioxide was added to carry out a polycondensation reaction 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 0.45 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure to obtain a polyester chip (c). The intrinsic viscosity of this polyester was 0.45.

<Manufacture of polyester (d)>
The intrinsic viscosity of this polyester chip was increased by a solid phase polycondensation method. After treatment in a preliminary crystallization tank at 170 ° C. in a nitrogen atmosphere for 0.5 hours, the moisture content becomes 0.005% at a temperature of 200 ° C. using a tower dryer that flows an inert gas. Until dried. Thereafter, it was sent to a solid phase polymerization tank and subjected to solid phase polymerization at 240 ° C. for 3 hours to obtain a polyester (d) having an intrinsic viscosity of 0.70.

<Manufacture of polyester (e)>
When producing the polyester (d), solid phase polymerization was performed in a solid phase polymerization tank for 5 hours to obtain a polyester (e) having an intrinsic viscosity of 0.80.

<Method for producing polyester (f)>
A raw material containing 0.50 part of amorphous silica having an average diameter of 2.5 μm polymerized by a conventional melt polycondensation method using isophthalic acid and terephthalic acid as dicarboxylic acid components and ethylene glycol as a polyhydric alcohol component, respectively. Chips were manufactured. The isophthalic acid content in the dicarboxylic acid component of this raw material was 16 mol%.

<Method for producing polyester (g)>
Using diphthalic acid components as isophthalic acid and terephthalic acid, and polyhydric alcohol components as ethylene glycol, raw material chips polymerized by a conventional melt polycondensation method were produced. The isophthalic acid content in the dicarboxylic acid component of this raw material was 22 mol%.

<Method for producing polyester (h)>
Using terephthalic acid as the dicarboxylic acid component and 1,4-cyclohexanedimethanol and ethylene glycol as the polyhydric alcohol component, raw material chips polymerized by a conventional melt polycondensation method were produced. The 1,4-cyclohexanedimethanol content in the diol component of this raw material was 33 mol%.

Example 1:
<Manufacture of polyester film>
30% by weight of polyester (b), 40% by weight of polyester (f) and 30% by weight of polyester (e) are mixed as raw materials for the outer layer A, and 20% by weight of polyester (a), polyester ( g) 30% by weight and 50% by weight of polyester (h) are mixed, supplied to two vented extruders, melt-extruded at 290 ° C., and then subjected to a surface temperature of 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. Next, the film was stretched 2.8 times in the longitudinal direction at 100 ° C., and then the following coating agent was applied to one side of the longitudinally stretched film so that the coating amount (after drying) was 0.03 g / m ² . After that, after being guided to a tenter, subjected to a preheating step at 120 ° C. in the transverse direction at a temperature of 120 ° C. and subjected to a transverse stretching of 5.1 times at 120 ° C., heat treatment was performed at 220 ° C. for 10 seconds, and then at 180 ° C. in the width direction. 4% relaxation was added to a master roll having a width of 4000 mm. A slit was made from a position of 1400 mm from the end of the master roll, and the core roll was wound up 1000 m to obtain a polyester film. The total thickness of the obtained film was 38 μm (layer constitution: surface layer 4 μm / intermediate layer 30 μm / surface layer 4 μm).

In addition, the example of a compound which comprises an application layer is as follows.
(Example compounds)
-Polyvinyl alcohol binder polymer having a saponification degree of 88 mol% and a polymerization degree of 350: A
Emulsion polymer of methyl methacrylate / ethyl acrylate / acrylonitrile / N-methylol methacrylamide = 45/45/5/5 (molar ratio) (emulsifier: anionic surfactant) Binder polymer: B
・ Crosslinking agent Hexamethoxymelamine crosslinking agent: C
・ Particulate colloidal silica (average particle diameter: 70 nm): D
Solid content ratio: A / B / C / D = 30/24/42/4

A release agent composed of release agent composition-A shown below was applied to the obtained polyester film by a reverse gravure coating method so that the coating amount (after drying) was 0.1 g / m ² , and the dryer temperature was 120. ° C., rolled peel force at 21 mN / cm release film under a condition of line speed 30 m / min, TmB of polyester film 218 ℃, TmA-TmB is 30 ° C., OL weight is 0.82 mg / ^{m 2} there were.
<Releasing agent composition-A>
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 wt%)
MEK / toluene mixed solvent (mixing ratio is 1: 1)

  For the obtained release polyester film, a deflection plate was prepared by the following method. The obtained release polyester film has good punchability, no generation of dust, good peeling characteristics, and it peels cleanly from the polarizing plate with adhesive, and the adhesive adheres to the release layer. I couldn't.

<Manufacture of polarizing plate with release film>
The acrylic adhesive shown below is applied to the polarizing plate so that the thickness after drying is 25 μm, and after passing through a 130 ° C. drying oven in 30 seconds, the release film is bonded, and the adhesive is interposed. Thus, a polarizing plate with a release film in which the release film and the polarizing film were adhered to each other was prepared. The laminating direction of the film was performed so that the width direction of the release film was parallel to the orientation axis of the polarizing film.
Acrylic adhesive coating solution Acrylic adhesive (Olivein BPS429-4: manufactured by Toyo Ink) 100 parts Curing agent (BPS8515: manufactured by Toyo Ink) 3 parts MEK / toluene mixed solvent (mixing ratio is 1: 1) 50 parts

Examples 2-6:
In Example 1, the same procedure as in Example 1 was performed except that the raw material species and the mixing ratio of the outer layer A and the inner layer B were changed, and the transition metal catalyst content of the release agent composition in the coating layer was changed. To obtain a polyester film. The obtained results are summarized in Table 1 below.

Comparative Examples 1-6:
In Example 1, the same procedure as in Example 1 was performed except that the raw material species and the mixing ratio of the outer layer A and the inner layer B were changed, and the transition metal catalyst content of the release agent composition in the coating layer was changed. To obtain a polyester film. The results obtained are summarized in Table 2 below.

※１）原反フィルムの耐溶剤性が悪く、塗布が困難
※２）ベースフィルムのＡ、Ｂ間で層間剥離が起こった
※３）コストが高いため、生産性に問題がある

* 1) Difficult to apply due to poor solvent resistance of the raw film * 2) Delamination occurred between A and B of the base film * 3) Due to high cost, there is a problem with productivity

  The polyester film of the present invention is a release polyester film that can be easily punched, that is, cut out in the production process of a polarizing plate base material, and at that time, a release polyester film that hardly causes dust and the like. And can be suitably used as a release polyester film having an advantageous low OL performance.

Claims (1)

A polyester layer B having a melting point (TmB) in the range of 180 to 225 ° C. and a laminated polyester film having at least one layer A adjacent to the layer B as a base material, and the melting point (TmA) of the layer A is the layer B Higher than the melting point, the difference in melting point (TmA-TmB) is in the range of 10 to 40 ° C., and has a coating layer obtained by coating a coating solution containing polyvinyl alcohol on the layer A, on the coating layer A release polyester film comprising a silicone release layer containing 0.5 to 5.0% by weight of at least one transition metal catalyst.