JP6108709B2 - Transparent conductive film sheet - Google Patents

Description

  The present invention relates to a laminated polyester film, for example, severe conditions such as a long-time heat treatment at 150 ° C., a sputtering process at a high tension, and a durability test in a high-temperature and high-humidity atmosphere. Even after passing through the steps below, the increase in film haze is as small as possible, and it relates to an optical laminated polyester film that has excellent optical properties and visibility even after being processed as a product for optical members. is there.

  Conventionally, in touch panel applications, various methods such as a resistive film method and a capacitance method are employed depending on the position detection method. Among them, there is a tendency to increase the spread of a capacitance method characterized by multipoint detection, high light transmittance, high resolution, and high response speed. There are two types of capacitive touch panels: surface type and projection type. The surface type consists of three layers: a cover, a transparent conductive layer, and a glass substrate. The projection type consists of a glass or plastic film, a transparent electrode layer, and a substrate layer equipped with an IC that performs arithmetic processing. The

  In the manufacturing process of the transparent conductive laminate, it is generally heat-processed. For example, in order to form a transparent conductive film, an ITO film is formed by a sputtering method, and then heat treatment is performed at 150 ° C. for crystallization (Patent Document 1), or in the production of a conductive laminated film. When it is allowed to stand at 150 ° C. for 1 hour for low heat shrinkage treatment (Patent Document 2), or when processing a transparent conductive film, heat treatment at about 150 ° C. may be required to print a silver paste or the like. Yes (Patent Document 3). In the transparent conductive thin film manufacturing process, with heat treatment in a high temperature atmosphere, a low molecular weight substance called an ester cyclic trimer contained in the polyester film precipitates and crystallizes on the film surface. It may be difficult to obtain a highly accurate transparent conductive thin film.

  In addition, in the touch panel application, in recent years, the frequency of mounting on communication information devices such as mobile phones and PDAs (Personal Digital Assistance), game machines, etc. has been increasing. High visibility tends to be preferred. As a result, in the polyester film used in this field, the visibility degradation accompanying the increase in film haze due to the precipitation of the ester cyclic trimer after processing is increasingly regarded as a problem. is there.

  There has also been proposed a method of suppressing precipitation of an ester cyclic trimer by coating an application layer on a polyester film substrate (Patent Document 4). However, there may be problems such as contact between the guide roll for conveyance and the polyester film surface in the processing step, and problems such as peeling of the coating layer due to rubbing. In such cases, precipitation of the ester cyclic trimer in that part is suppressed. In addition, when the precipitation amount of the ester cyclic trimer of the polyester base itself is reduced, the precipitation of the ester cyclic trimer is combined with the coating layer having a function of suppressing the precipitation of the ester cyclic trimer. Since the amount can be further reduced, there is a situation in which a technique for suppressing precipitation of the ester cyclic trimer of the polyester film substrate itself is strongly demanded.

  As a transparent substrate film for forming a transparent conductive film, a polyester film is generally used in consideration of transparency and mechanical properties, and has a function of suppressing precipitation of the polyester film of the substrate and the ester cyclic trimer. In order to improve the adhesion to the coating layer, an easily adhesive coating layer is generally provided as the intermediate layer. As an easily adhesive coating layer, for example, polyester resin, acrylic resin, urethane resin and the like are known (Patent Documents 5 and 6).

  In recent years, ester cyclic trimer after undergoing severe conditions such as long-time heat treatment under 150 ° C conditions, sputtering process with high tension, durability test under high temperature and high humidity atmosphere, etc. A function to suppress the precipitation of the body is required. For these reasons, there is a demand for a polyester film having an easy-adhesive performance such that the composition of the coating layer having a function of suppressing the precipitation of the ester cyclic trimer is drastically changed and has good adhesion to various layers. Yes.

JP 2007-200823 A JP 2007-42473 A JP 2007-320144 A JP 2003-237005 A JP-A-8-281890 JP 2000-229395 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is, for example, a long-time heat treatment at 150 ° C., a sputtering process with high tension, and a high-temperature and high-humidity atmosphere. Even after being subjected to harsh conditions such as durability tests, the increase in film haze is suppressed to a small level, and even after processing as a product for optical components, optical lamination with excellent optical properties and visibility It is to provide a polyester film.

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

That is, the gist of the present invention is that a laminated polyester film in which a coating layer is provided on one surface layer of at least three or more layers of polyester film having a thickness of both surface layers of 4 μm or more, and an ITO film is a coating layer of the laminated polyester film. The laminated polyester film has a total film thickness (total with coating layer) of 45 to 200 μm and is heat-treated at 150 ° C. for 90 minutes. consists in the transparent conductive film sheet the amount of the polyester film surface (coating layer without surface) ester cyclic trimer extracted from is characterized Oh Rukoto at 3.0 mg / m ² or less.

  According to the present invention, for example, a process under severe conditions such as a long-time heat treatment at 150 ° C., a sputtering process with high tension, and a durability test under a high-temperature and high-humidity atmosphere are performed. Even after, an increase in film haze is suppressed to a small level, and it is possible to provide a laminated polyester film excellent in adhesion with a coating layer having a function of suppressing precipitation of an ester cyclic trimer, and its industrial value. Is expensive.

  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, which is melt-extruded from an extrusion die. 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.

  The polyester used for the outermost layer in the present invention preferably has an ester cyclic trimer content of 0.5% by weight or less. When a polyester with an oligomer content exceeding 0.5% is used, the resulting laminated polyester is heat-treated for a long time at 150 ° C, a sputtering process with high tension, and in a high-temperature, high-humidity atmosphere. When used in processing processes under harsh conditions such as durability tests at high temperatures, the film haze will increase, and after processing as a product, it may not be suitable for optical members in terms of optical properties and visibility .

  In the film of the present invention, the thickness of both outermost layers is 4 μm or more, preferably 6 μm or more, and more preferably 7 μm or more. When the thickness of both outermost layers is less than 4 μm, the precipitation sealing effect of the outermost ester cyclic trimer with a small content of the ester cyclic trimer is reduced.

  The film haze of the film of the present invention is preferably 1.3% or less, more preferably 1.1% or less, and still more preferably 1.0% or less. The film of the present invention is widely used in optical applications because of its excellent transparency. However, when the haze exceeds 1.3%, the transparency as an optical display member is impaired due to poor transparency. May end up.

  The total film thickness (total with the coating layer) of the laminated film of the present invention is in the range of 45 to 200 μm. When the total film thickness is less than 45 μm, after forming a transparent conductive film on the film, when forming a transparent conductive film sheet (laminated transparent conductive film) formed by laminating film-film, wrinkles occur in the film Therefore, a transparent conductive film sheet cannot be formed properly. When the thickness exceeds 200 μm, the sheet flexibility of the sheet forming the transparent conductive film sheet (laminated transparent conductive film) formed by laminating the film and film after forming the transparent conductive film on the film is It will be damaged.

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, 0.01-3 micrometers, Preferably it is the range of 0.1-2 micrometers. When particles having an average particle size of less than 0.01 μm are used, sufficient slipperiness cannot be imparted, so that the winding characteristics in the film production process tend to be inferior. On the other hand, when the average particle size exceeds 3 μm, the degree of roughening of the film surface becomes too large and the film haze may increase.

  Further, the content of particles in the polyester layer is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient, resulting in poor appearance such as scratches during film processing. On the other hand, when the addition exceeds 5% by weight, the transparency of the film may be insufficient.

  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.

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

  Hereinafter, although the manufacturing method of the film of this invention is demonstrated concretely, as long as the summary of this invention is satisfied, this invention is not specifically limited to the following illustrations.

  Polyester chips dried by a known method are supplied to a melt extrusion apparatus and heated to a temperature equal to or higher than the melting point of each polymer to melt. Next, the molten polymer is extruded from a die and rapidly cooled and solidified on a rotary cooling drum so that the temperature is equal to or lower than the glass transition temperature to obtain a substantially amorphous unoriented sheet. 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. In the present invention, an electrostatic application adhesion method and / or a liquid application adhesion method is preferably employed.

  In the present invention, the simultaneous biaxial stretching method can be adopted for the production of the polyester film constituting the laminated polyester film. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is usually stretched and oriented in the machine direction and the width direction at a temperature controlled normally at 70 to 120 ° C., preferably 80 to 110 ° C. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. 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. Further, it is possible to add re-longitudinal stretching and re-lateral stretching as necessary.

The amount of the ester cyclic trimer extracted with dimethylformamide from the polyester film surface (surface without the coating layer) before and after heat treatment (150 ° C., 90 minutes) of the laminated polyester film in the present invention was 3.0 mg / m ^2. Or less, preferably 2.5 mg / m ² or less, more preferably 2.0 mg / m ² or less. When the amount of the ester cyclic trimer exceeds 3.0 mg / m ² , precipitation of the ester cyclic trimer occurs in post-processing, for example, with long-time heat treatment at 150 ° C., 90 minutes, etc. The amount increases and the transparency of the film decreases.

The polyester film of the present invention can be mixed with other thermoplastic resins such as polyethylene naphthalate and polytrimethylene terephthalate as long as the effects of the present invention are not impaired. Moreover, you may mix | blend coloring agents, such as a ultraviolet absorber, antioxidant, surfactant, a fluorescent whitening agent, a lubricant agent, a light-shielding agent, a matting agent, and a dye, a pigment. In addition, for the purpose of improving the slipperiness and abrasion resistance of the film, inert inorganic or organic fine particles can be blended with the polyester as necessary.
Next, formation of the coating layer which comprises the laminated polyester film in 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 this invention, it is preferable to have the coating layer formed by apply | coating the coating liquid containing an acrylic resin, an epoxy compound, and an oxazoline compound on the single side | surface of a polyester film.

  The coating layer in this invention can improve adhesiveness with various thermosetting layers and active energy ray hardening layers, such as a coating layer which has a function which suppresses precipitation of ester cyclic trimer.

  As a result of various investigations, by forming a coating layer that uses one kind of a crosslinking agent such as an acrylic resin and an epoxy compound or an oxazoline compound, the coating layer has a function of suppressing precipitation of an ester cyclic trimer. It was found that adhesion was improved. As a result of further investigation, it was found that the coating layer made of an acrylic resin, an epoxy compound, and an oxazoline compound exhibits very good adhesion.

  The acrylic resin used in the present invention is a polymer comprising a polymerizable monomer having a carbon-carbon double bond, as typified by acrylic and methacrylic monomers. These may be either a homopolymer or a copolymer. Moreover, the copolymer of these polymers and other polymers (for example, polyester, polyurethane, etc.) is also included. For example, a block copolymer or a graft copolymer. Alternatively, a polymer (possibly a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyester solution or a polyester dispersion is also included. Similarly, a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyurethane solution or polyurethane dispersion is also included. Similarly, a polymer obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in another polymer solution or dispersion (in some cases, a polymer mixture) is also included.

  The polymerizable monomer having a carbon-carbon double bond is not particularly limited, but particularly representative compounds include, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citracone. Various carboxyl group-containing monomers such as acids, and salts thereof; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxyl fumarate, Various hydroxyl group-containing monomers such as monobutylhydroxy itaconate; various monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate ( (Meth) acrylic acid esters; Various nitrogen-containing vinyl monomers such as (meth) acrylimide, diacetone acrylamide, N-methylol acrylamide or (meth) acrylonitrile; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene, Various vinyl esters such as vinyl acetate and vinyl propionate; γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, “Silaplane FM-07” (methacryloyl silicon macromer) manufactured by Chisso Corporation Various silicon-containing polymerizable monomers; phosphorus-containing vinyl monomers; vinyl chloride, biliden chloride, vinyl fluoride, vinylidene fluoride, trifluorochloroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafur Various vinyl halides such as Russia propylene; various conjugated dienes such as butadiene and the like.

  An acrylic resin containing a functional group such as a hydroxyl group, an amino group, or an amide group can be used in order to improve adhesion with a coating layer having a function of suppressing precipitation of an ester cyclic trimer.

  In the formation of the coating layer in the film of the present invention, the coating layer of the coating layer is strengthened and has sufficient adhesion with a coating layer having a function of suppressing precipitation of various ester cyclic trimers. An epoxy compound and an oxazoline compound are used as a crosslinking agent in order to improve the heat and moisture resistance after formation.

  As an epoxy compound, the compound containing an epoxy group in a molecule | numerator, its prepolymer, and hardened | cured material are mentioned, for example. Examples include condensates of epichlorohydrin with hydroxyl groups and amino groups such as ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A, and polyepoxy compounds, diepoxy compounds, monoepoxy compounds, glycidylamine compounds, and the like. is there. Examples of the polyepoxy compound include sorbitol, polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, trimethylol. Examples of the propane polyglycidyl ether and diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether. Ether, polypropylene glycol diglycidyl ether, Ritetramethylene glycol diglycidyl ether and monoepoxy compounds include, for example, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and glycidyl amine compounds such as N, N, N ′, N ′,-tetraglycidyl-m. -Xylylenediamine, 1,3-bis (N, N-diglycidylamino) cyclohexane and the like.

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

  In the laminated polyester film of the present invention, the improvement in visibility and transparency when a coating layer having the function of suppressing the precipitation of various ester cyclic trimers is formed on the coated surface, in the coated surface shape. Therefore, it is possible to use a binder polymer other than the acrylic resin in combination.

  The “binder polymer” used in the present invention is a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) in accordance with a high molecular 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, urethane resin, polyvinyl (polyvinyl alcohol, polyvinyl chloride, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches, and the like. Can be mentioned. Among these, it is preferable to use a polyester resin in combination from the viewpoint of improving the coated surface and adhesion.

  Moreover, it is also possible to contain particle | grains for the improvement of the slipperiness of a coating layer, or a blocking improvement. Examples of the particles used include inorganic particles such as silica, alumina, and metal oxide, or organic particles such as crosslinked polymer particles.

  Furthermore, as long as it does not impair the gist of the present invention, the coating layer has an antifoaming agent, a coating property improving agent, a thickener, an organic lubricant, an antistatic agent, an ultraviolet absorber, an antioxidant, foaming as necessary. Agents, dyes and the like may be contained.

  In the present invention, the content of the acrylic resin in the coating layer is usually 20 to 90% by weight, preferably 25 to 85% by weight, and more preferably 30 to 80% by weight. When the amount is less than 20% by weight, the adhesion may not be sufficient due to the small amount of the acrylic resin component, and when it exceeds 90% by weight, the coating layer becomes brittle due to the small amount of the crosslinking agent component, and the adhesion is not sufficient. In some cases, the heat and humidity resistance may not be sufficient.

  In this invention, the quantity of the compound derived from the epoxy compound and oxazoline compound which occupies in a coating layer is 10-80 weight% normally, Preferably it is 15-75 weight%, More preferably, it is 20-70 weight%. When the amount is less than 10% by weight, the coating layer becomes brittle and may not sufficiently withstand moisture and heat. When the amount exceeds 80% by weight, the adhesion may not be sufficient. Moreover, it is preferable that at least one of an epoxy compound and an oxazoline compound exceeds 5 weight%. In the case of 5% by weight or less in all cases, when exposed to high temperature and high humidity conditions for a long time, the adhesion with an application layer or the like having a function of suppressing precipitation of ester cyclic trimer may not be stable.

  In the polyester film of the present invention, a coating layer can also be provided on the surface opposite to the surface on which the coating layer is provided. For example, in the case of forming a functional layer such as an undercoat layer for forming an ITO film for forming a transparent conductive film on the opposite side on which the coating layer having a function of suppressing the precipitation of the ester cyclic trimer is formed, Adhesion with the functional layer can be improved. A conventionally well-known thing can be used as a component of the coating layer formed in the surface on the opposite side. For example, a binder polymer such as a polyester resin, an acrylic resin, and a urethane resin, a crosslinking agent such as an epoxy compound, an oxazoline compound, a melamine compound, and an isocyanate compound may be used. These materials may be used alone or in combination. You may use together. Further, it may be a coating layer (a coating layer having the same surface on both sides of a polyester film) formed from an acrylic resin, an epoxy compound, or an oxazoline compound as described above. Considering the convenience of production and film processing, the coating layers are preferably the same.

  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.

Respect laminated 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 0.01 to 0.5 g / ^{m 2,} more preferably The range is 0.02 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 present invention, as a method for providing the coating 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.

  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 40 at 80 to 200 ° C. The heat treatment may be performed for 2 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 film of the present invention is suitable for, for example, a capacitive touch panel application in which a transparent conductive film-film is bonded.

  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 measuring method used in the present invention is 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) Average particle diameter (d50)
The particle size was measured by a sedimentation method based on Stokes' resistance law using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 manufactured by Shimadzu Corporation.

(3) 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.

(4) Method for measuring the amount of ester cyclic trimer extracted from the surface of the laminated polyester film In advance, the untreated laminated polyester film is heated in air at 150 ° C. for 90 minutes. Thereafter, the heat-treated film is adhered as close as possible to the inner surface of a box having a top and width of 10 cm and a height of 3 cm so that the coated layer surface is on the outer side. 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 is supplied to liquid chromatography (manufactured by Shimadzu Corp .: LC-7A) to determine the amount of ester cyclic trimer in DMF, and this value is divided by the area of the film in contact with DMF. The amount of the surface ester cyclic trimer (mg / m ² ). The amount of ester cyclic trimer in DMF was determined from the peak area ratio of the standard sample peak area and the measured sample peak area (absolute calibration curve method).
The standard sample was prepared by accurately weighing the ester cyclic trimer previously collected 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

(5) Measuring method of film haze Film haze was measured for the sample film according to JIS-K-7136 with a haze meter “HM-150” manufactured by Murakami Color Research Laboratory.

(6) Method for evaluating film visibility after lamination of transparent conductive film (practical property substitution evaluation)
In the laminated polyester film, a sintered body of 95% indium oxide and 5% by weight tin oxide on the surface opposite to the coating layer in an atmosphere of 0.4 Pa composed of 95% argon gas and 5% oxygen gas. An ITO film (transparent conductive thin film) having a thickness of 25 nm was formed by a reactive sputtering method using the material. The ITO film was crystallized by heat treatment at 150 ° C. for 1 hour.
The transparency and visibility of the obtained film were determined according to the following criteria.
<Criteria>
○: Transparency / Visibility is good (practically acceptable level)
×: Transparency / visibility poor (practical problem level)

(7) Film-film bonding property evaluation method (practical property substitution evaluation)
A coreless double-sided adhesive was applied to a film heated at 150 ° C. for 2 hours, and the film was attached to the opposite surface for determination. A roller was used at the time of bonding.
<Criteria>
○: Wrinkle-free and particularly good. (Practical, no problem level)
X: Wrinkles entered and defective. (Practical problem level)

(8) Film-film sheet flexibility evaluation method (practical property substitution evaluation)
The A4 cut size film sample was bent into a loop shape, and the strength of the stiffness was evaluated by loading when the diameter direction of the loop was crushed.
○: Film stiffness is weak and sheet flexibility is good (practically satisfactory level)
×: Strong film stiffness and poor sheet flexibility (practical problem level)

(9) Evaluation method for adhesion 1 As a coating solution for the light diffusion layer, 100 parts by mass of resin (Halus Hybrid UV-G301 manufactured by Nippon Shokubai), 10 parts by mass of isocyanate (manufactured by Sumika Bayer Urethane, Death Module N-3200), By preparing 30 parts by mass of acrylic resin particles having an average particle size of 15 μm (MBX-15, manufactured by Sekisui Plastics Industry Co., Ltd.), 100 parts by mass of toluene, and 100 parts by mass of methyl ethyl ketone, coating and heat curing, the thickness of 15 g / m ² A light diffusion layer was formed. Further, acrylic resin particles having an average particle size of 15 μm used in the coating solution for the light diffusion layer as an anti-sticking layer on the side opposite to the light diffusion layer were replaced with acrylic resin particles having an average particle size of 5 μm (manufactured by Sekisui Plastics Co., Ltd.). MBX-5) A double-sided product was prepared in the same manner except that a layer having a thickness of 3 g / m ² was formed instead of 7 parts by mass. Then, 10 × 10 cross cut is applied to each of the light diffusion layer and the anti-sticking layer, and an 18 mm wide tape (Cello Tape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) is applied thereon. After peeling off sharply at a peeling angle of 180 degrees, the peeled surface is observed, and for the larger peeled area, if the peeled area is 5% or less, ○, if it exceeds 5% and 30% or less, Δ, 30 When it exceeded%, it was set as x.

(10) Adhesion 2 Evaluation Method As a light diffusion layer coating solution, 60 parts by mass of dipentaerythritol hexaacrylate, 6 parts by mass of 2-hydroxy-3-phenoxypropyl acrylate, a photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals) ) 4 parts by mass, acrylic resin particles having an average particle size of 12 μm (MBX-12 manufactured by Sekisui Plastics Industry Co., Ltd.), 30 parts by mass, and 200 parts by mass of methyl ethyl ketone were prepared, applied, cured by irradiation with ultraviolet rays, and a thickness of 10 g / A light diffusion layer of m ² was formed. Further, acrylic resin particles having an average particle diameter of 12 μm used in the coating solution for the light diffusion layer as an anti-sticking layer on the side opposite to the light diffusion layer, acrylic resin particles having an average particle diameter of 5 μm (manufactured by Sekisui Plastics Co., Ltd.) MBX-5) A double-sided processed product was prepared in the same manner except that a layer having a thickness of 3 g / m ² was formed instead of 5 parts by mass. Immediately thereafter (initial), after 150 hours in an environment of 80 ° C./90% RH (wet heat test), a 10 × 10 cross-cut was made on each of the light diffusion layer and the anti-sticking layer, and 18 mm was formed thereon. After affixing a width tape (cello tape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) and peeling off sharply at a peel angle of 180 degrees, the peeled surface was observed, and the peel area was larger, When the peeled area was 5% or less, it was evaluated as ◯ when it exceeded 5% and 30% or less, and when it exceeded 30%, it was rated as x.

<Manufacture of polyester>
[Production method of 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 by weight of ethyl acid phosphate to this reaction mixture, 0.04 part by weight of antimony trioxide was added, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from 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 ester cyclic trimer content of 0.97% by weight.

[Production method of polyester (B)]
Polyester (A) was pre-crystallized at 160 ° C. in advance and then solid-phase polymerized in a nitrogen atmosphere at a temperature of 220 ° C., and had an intrinsic viscosity of 0.75 and an ester cyclic trimer content of 0.46% by weight. Polyester (B) was obtained.

[Production method of polyester (C)]
In the method for producing polyester (A), after adding 0.04 part by weight of ethyl acid phosphate, 0.2 part by weight 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. A polyester (C) was obtained using the same method as the production method of the polyester (A) except that the polycondensation reaction was stopped at a time corresponding to the intrinsic viscosity of 0.65 by adding parts by weight. The obtained polyester (C) had an intrinsic viscosity of 0.65 and a content of ester cyclic trimer of 0.82% by weight.

Examples of compounds constituting the coating layer are as follows.
(Example compounds)
Acrylic resin: (IA) Aqueous dispersion of acrylic resin polymerized with the following composition: ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylol acrylamide / acrylic acid = 65/21/10/2/2 (% by weight) Emulsion polymer (emulsifier: anionic surfactant)
Acrylic resin: (IB) Aqueous dispersion of acrylic resin polymerized with the following composition: ethyl acrylate / methyl methacrylate / 2-hydroxyethyl methacrylate / N-methylol acrylamide / acrylic acid = 65/28/3/2/2 (% by weight ) Emulsion polymer (emulsifier: anionic surfactant)

Polyester resin: (II) A water dispersion of a polyester resin copolymerized with the following composition: Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / 1 4-butanediol / diethylene glycol = 56/40/4 // 70/20/10 (mol%)

Epoxy compound: (III) Denacol EX-521 (manufactured by Nagase ChemteX), which is polyglycerol polyglycidyl ether

・ Oxazoline compounds: (IVA)
Acrylic polymer Epocross WS-500 having an oxazoline group and a polyalkylene oxide chain (manufactured by Nippon Shokubai, containing about 38% by weight of 1-methoxy-2-propanol solvent)
・ Oxazoline compounds: (IVB)
Oxazoline group-containing acrylic polymer Epocros WS-300 (manufactured by Nippon Shokubai)

-Particles: (V) Silica sol with an average particle size of 65 nm

Example 1:
A mixed raw material obtained by mixing the above polyesters (B) and (C) in proportions of 84% by weight and 16% by weight is used as a raw material for the A layer, and a raw material of 100% by weight of polyester (A) is used as a raw material for the B layer. Each was supplied to an extruder and melted at 285 ° C., and then the A layer was the outermost layer (surface layer) and the B layer was an intermediate layer on a casting drum cooled to 40 ° C. ) And coextruded so as to have a thickness composition ratio of A: B: A = 4.0: 42: 4.0 and cooled and solidified to obtain a non-oriented sheet. Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the difference in peripheral speed of the roll, and then the coating solution 1 shown in Table 1 below was applied to one side of the longitudinally stretched film, which was led to a tenter. The film is stretched 4.0 times at 120 ° C in the transverse direction, heat treated at 225 ° C, relaxed by 2% in the transverse direction, and rolls a film having a coating layer whose coating amount (after drying) is as shown in Table 2 A roll-up laminated polyester film was obtained. The characteristics of the obtained film are as shown in Tables 2 and 3 below, and were good in all evaluations.

Examples 2-7:
In Example 1, a polyester film was obtained in the same manner as in Example 1 except that the thickness component ratio and the coating composition were changed to the coating composition shown in Table 1. The characteristics of the obtained laminated polyester film are as shown in Tables 2 and 3 below, and were good in all evaluations.

Comparative Example 1:
In Example 1, using the mixed raw materials obtained by mixing the polyesters (A) and (C) in proportions of 84% by weight and 16% by weight, respectively, as the raw material for the A layer, the thickness composition ratio is A: B: A = 2. A polyester film was obtained in the same manner as in Example 1 except that the coextrusion was changed to 5: 45: 2.5 and the coating composition was changed to the coating composition shown in Table 1. . The characteristics of the obtained laminated polyester film are shown in Tables 2 and 3 below.

Comparative Examples 2-7:
In Example 1, a polyester film was obtained in the same manner as in Example 1 except that the thickness component ratio and the coating composition were changed to the coating composition shown in Table 1. The characteristics of the obtained laminated polyester film are shown in Tables 2 and 3 below.

  The film of the present invention can be suitably used as an optical member such as a touch panel, for example.

Claims (1)

The thickness of both surface layers is 4 μm or more, and the surface of the laminated polyester film provided with the coating layer on one surface layer of at least three layers of the polyester film is opposite to the surface on which the coating layer of the laminated polyester film is provided. About the transparent conductive film sheet provided on the surface,
The laminated polyester film has a total film thickness (total with the coating layer) of 45 to 200 μm, and is an ester cyclic trimer extracted from the surface of the polyester film ( surface without the coating layer) heat-treated at 150 ° C. for 90 minutes. transparent conductive film sheet amount is characterized Oh Rukoto at 3.0 mg / ^{m 2} or less.