JP2016166372A - Method for producing laminated polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated polyester film capable of being suitably used for various applications required to have excellent adhesion characteristics, for instance, applications of a surface protective film and the like that is used for preventing scratches and preventing adhesion of dirt at the time of conveyance, storage, and processing of a resin plate, a metal plate and the like.SOLUTION: A method for producing a laminated polyester film includes applying a coating liquid mainly containing a resin having a glass transition point of 0°C or lower on at least one surface of a polyester film by in-like coating, and thereby forming an adhesive layer having adhesion characteristics.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a laminated polyester film. For example, as a surface protection film for transporting, storing and processing a resin plate, a metal plate, etc. The present invention relates to a method for producing a laminated polyester film having few eyes, excellent mechanical strength and heat resistance, and having good adhesive properties.

  Conventionally, when transporting, storing and processing resin plates, metal plates, glass plates, etc., preventing scratches and dirt, and scratching when processing components used in electronic fields such as liquid crystal panels and polarizing plates Wide range of surface protection films for applications such as prevention of dust and dirt, prevention of dirt and dirt during transportation and storage of automobiles, protection of automobile coating from acid rain, and protection during plating and etching of flexible printed circuit boards It is used.

  These surface protective films have an appropriate adhesive force to the adherend during transport, storage, processing, etc. of various adherends such as resin plates, metal plates and glass plates, It is required that the surface of the adherend be protected by adhering to the surface of the adherend and easily peeled off after the end of the purpose. In order to overcome these problems, proposals have been made to use polyolefin-based films for surface protection (Patent Documents 1 and 2).

  However, since a polyolefin-based film is used as the surface protective film substrate, it is not possible to remove defects caused by gel-like materials and deteriorated products, which are generally called fisheye, For example, when inspecting an adherend in a state where the surface protective film is bonded, there is a problem that it becomes an obstacle such as detecting a defect of the surface protective film.

  In addition, as a base material for the surface protection film, a film having a certain degree of mechanical strength is required so that the base material is not stretched due to various processing tensions such as bonding to an adherend. However, since polyolefin films generally have poor mechanical strength, there is a drawback that they are unsuitable for high-tension processing due to an increase in processing speed in order to place importance on productivity.

  Furthermore, even when the processing temperature is increased to improve the processing speed and various characteristics, the polyolefin-based film is not excellent in shrinkage stability due to heat, so that the dimensional stability is poor. Therefore, there is a demand for a film that has little thermal deformation even when processed at high temperature and has excellent dimensional stability.

JP-A-5-98219 JP 2007-270005 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that there are few fish eyes used for various surface protection films, etc., excellent mechanical strength and heat resistance, and good adhesive properties. The object is to provide a laminated polyester film.

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

  That is, the gist of the present invention is to form an adhesive layer having adhesive properties by applying in-line coating on at least one surface of a polyester film with a coating liquid mainly containing a resin having a glass transition point of 0 ° C. or less. The feature resides in a method for producing a laminated polyester film.

  According to the method for producing a laminated polyester film of the present invention, as various surface protective films, it is possible to provide a film having few fish eyes, excellent mechanical strength and heat resistance, and having good adhesive properties. Value is high.

  We think that it is necessary to change the base material of the base film significantly in order to reduce fish eyes, improve mechanical strength, and improve heat resistance, and as a result of various studies, they differ greatly from conventional polyolefin-based materials. It has been found that this can be achieved by using a polyester-based material. However, by greatly changing the material system of the base film, the adhesive properties are greatly lowered, which cannot be achieved with a general polyester film.

  Therefore, we considered giving adhesive properties by laminating the coating layer, but in offline coating performed after the polyester film manufacturing process, heat is applied in the process of applying and drying the coating layer, so the dimensions of the finished film have changed. There is also a drawback that it increases the risk of scratches and foreign matter adhesion due to the addition of one additional coating process, and also leads to an increase in manufacturing cost. We considered it and formed it.

  As a result of studying the formation of a coating layer having adhesive properties by in-line coating, it has been found that any coating layer mainly containing a resin having a glass transition point of 0 ° C. or lower can be a film having good adhesive properties. Invented. Hereinafter, the details of the present invention will be described.

  The polyester film constituting the laminated polyester film in the present invention may have a single layer structure or a multilayer structure, and may have four or more layers as long as it does not exceed the gist of the present invention other than a two-layer or three-layer structure. It may be a multilayer, and is not particularly limited. It is preferable to have a multi-layer structure of two or more layers and to give each layer a characteristic so as to achieve multiple functions.

  The polyester used in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Typical polyester includes polyethylene terephthalate and the like. On the other hand, the dicarboxylic acid component of the copolyester includes isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxybenzoic acid, etc.), etc. 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexane dimethanol, neopentyl glycol, is mentioned.

  From the viewpoint of forming a film that can withstand various processing conditions, it is preferable that the mechanical strength and heat resistance (dimensional stability by heating) are high, and for that purpose, it is preferable that the copolymer polyester component is small. Specifically, the proportion of the monomer forming the copolyester in the polyester film is preferably in the range of 10 mol% or less, more preferably 5 mol% or less, and more preferably produced as a by-product during homopolyester polymerization. It is a grade which contains the diether component of 3 mol% or less which is a grade which will carry out. In view of mechanical strength and heat resistance, a more preferable form of polyester is more preferably a film formed from polyethylene terephthalate or polyethylene naphthalate, which is polymerized from terephthalic acid and ethylene glycol, among the above compounds. In consideration of ease of handling and handling properties as a surface protective film, a film formed from polyethylene terephthalate is more preferable.

  There is no restriction | limiting in particular as a polymerization catalyst of polyester, A conventionally well-known compound can be used, For example, an antimony compound, a titanium compound, a germanium compound, a manganese compound, an aluminum compound, a magnesium compound, a calcium compound etc. are mentioned. Among these, antimony compounds are preferable because they are inexpensive, and titanium compounds and germanium compounds have high catalytic activity, can be polymerized in a small amount, and the amount of metal remaining in the film is small. Since transparency of this becomes high, it is preferable. Furthermore, since a germanium compound is expensive, it is more preferable to use a titanium compound.

  In the case of polyester using a titanium compound, the titanium element content is preferably 50 ppm or less, more preferably 1 to 20 ppm, and still more preferably 2 to 10 ppm. If the content of the titanium compound is too high, the polyester may be deteriorated in the process of melt-extruding the polyester, resulting in a strong yellowish film. If the content is too low, the polymerization efficiency is poor and the cost is low. In some cases, a film having a sufficient strength or a sufficient strength cannot be obtained. Moreover, when using the polyester by a titanium compound, it is preferable to use a phosphorus compound in order to reduce the activity of a titanium compound for the purpose of suppressing deterioration in the step of melt extrusion. As the phosphorus compound, orthophosphoric acid is preferable in view of the productivity and thermal stability of the polyester. The phosphorus element content is preferably in the range of 1 to 300 ppm, more preferably 3 to 200 ppm, and still more preferably 5 to 100 ppm with respect to the amount of polyester to be melt-extruded. If the content of the phosphorus compound is too large, it may cause gelation or foreign matter. If the content is too small, the activity of the titanium compound cannot be lowered sufficiently, and the yellowish It may be a film.

  In the polyester layer of the film of the present invention, particles can be blended mainly for the purpose of imparting slipperiness and preventing scratches in each step. When the particles are blended, the kind of the particles to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness, and specific examples thereof include, for example, silica, calcium carbonate, magnesium carbonate, barium carbonate, sulfuric acid. Examples thereof include inorganic particles such as calcium, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, zirconium oxide, and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, and benzoguanamine resin. 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. Of these, silica particles and calcium carbonate particles are preferable because they are particularly effective in a small amount.

  Moreover, the average particle diameter of the particles is preferably 5.0 μm or less, and more preferably in the range of 0.01 to 3.0 μm. When the average particle diameter exceeds 5.0 μm, the surface roughness of the film becomes too rough, and problems may occur in various processes in the subsequent steps. Moreover, by using in the said range, haze is restrained low and it is easy to ensure transparency as the whole film.

  Further, the particle content in the polyester layer is preferably less than 5% by weight, more preferably in the range of 0.0003 to 1% by weight, and still more preferably in the range of 0.0005 to 0.5% by weight. When there are no or few particles, the transparency of the film becomes high and the film becomes a good film, but the slipperiness may be insufficient. There are cases where improvement is required. In addition, when the particle content is high, haze increases and lacks transparency. For example, during various inspections, defects such as difficulty of defect inspection for foreign matters may occur.

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.

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

  From the viewpoint of the transparency of the polyester film, it is preferable not to contain particles throughout the film, but to make the film have a multilayer structure and to contain particles only in the outermost layer of the polyester film. In particular, a structure in which the film has a three-layer structure and particles are contained on both surface layers side than the intermediate layer is more preferable.

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

  The thickness of the polyester film in the present invention is not particularly limited as long as it can be formed as a film, but is preferably in the range of 2 to 350 μm, more preferably in the range of 5 to 200 μm.

  As a film forming method of the film of the present invention, a generally known film forming method can be adopted, and there is no particular limitation. For example, when producing a biaxially stretched polyester film, the polyester raw material described above is first melt-extruded from a die using an extruder, and the molten sheet is cooled and solidified with a cooling roll to obtain an unstretched 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, and an electrostatic application adhesion method or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the film is stretched in the direction perpendicular to the first-stage stretching direction at usually 70 to 170 ° C. and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Subsequently, a method of obtaining a biaxially oriented film by performing heat treatment at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% can be mentioned. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  In the present invention, the simultaneous biaxial stretching method can 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 180 to 270 ° C. under tension or 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.

  Next, formation of the coating layer which comprises the laminated polyester film in this invention is demonstrated. The coating layer of the present invention is laminated on at least one side of a polyester film and formed by in-line coating.

  In-line coating is a method of coating within the process of manufacturing a polyester film, and specifically, a method of coating at any stage from melt extrusion of a polyester to heat setting after stretching and winding up. Usually, it is preferable to coat on either an unstretched sheet obtained by melting and quenching, or a stretched uniaxially stretched film.

  Although not limited to the following, for example, in sequential biaxial stretching, a method of stretching in the transverse direction after coating a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) is particularly excellent. According to such a method, film formation and coating layer formation can be performed at the same time, so there is an advantage in manufacturing cost. In addition, in order to perform stretching after coating, the thickness of the coating layer can be changed by the stretching ratio. Compared to offline coating, thin film coating can be performed more easily.

  Further, by providing the coating layer on the film before stretching, the coating layer can be stretched together with the base film, whereby the coating layer can be firmly adhered to the base film. Furthermore, in the production of a biaxially stretched polyester film, the film can be restrained in the longitudinal and lateral directions by stretching while gripping the film end with a clip, etc. High temperature can be applied while maintaining the properties. Therefore, since the heat treatment performed after coating can be performed at a high temperature that cannot be achieved by other methods, the film forming property of the coating layer can be improved, and the coating layer and the base film can be more firmly adhered to each other. Furthermore, a strong coating layer can be obtained.

  According to the above-mentioned process by in-line coating, the film size does not change greatly depending on whether or not the coating layer is formed, and the risk of scratches and foreign matter adhesion does not change greatly depending on whether or not the coating layer is formed. This is a significant advantage over an extra off-line coating. Furthermore, as a result of various studies, it has been found that in-line coating has an advantage that adhesive residue on the adherend can be reduced. This is because heat treatment can be performed at a high temperature that cannot be obtained by off-line coating, and the coating layer and the substrate film are considered to be a result of tighter adhesion.

  In the present invention, it is an essential requirement to have a coating layer mainly containing a resin having a glass transition point of 0 ° C. or lower. “Mainly” means 50% by weight or more as a ratio in the coating layer.

  It has been found that by mainly using a resin having a glass transition point of 0 ° C. or lower, an appropriate adhesive property can be imparted to the polyester film. Conventionally known resins can be used as the resin having a glass transition point of 0 ° C. or lower. Specific examples of the resin include polyester resin, acrylic resin, urethane resin, polyvinyl resin (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.) and the like. Acrylic resin and urethane resin are preferred. Furthermore, when considering stronger adhesive properties and reusability of the film, a polyester resin or an acrylic resin is preferable, and adhesion to the polyester film as a base material and a small amount of adhesive residue on the adherend are required. When considering, polyester resin is most preferable, and when considering strong adhesive properties, acrylic resin is most preferable.

  The polyester resin includes, for example, those composed of the following polyvalent carboxylic acid and polyvalent hydroxy compound as main constituent components. That is, as the polyvalent carboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6 -Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutar Acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt and ester-forming derivatives thereof can be used. As the polyvalent hydroxy compound, ethylene Recall, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol , Neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol Polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate, and the like can be used. One or more compounds may be appropriately selected from these compounds, and a polyester resin may be synthesized by a conventional polycondensation reaction.

  Among them, it is preferable to contain an aliphatic polyvalent carboxylic acid or an aliphatic polyvalent hydroxy compound as a constituent component in order to lower the glass transition point to 0 ° C. or lower. In general, since a polyester resin is composed of an aromatic polyvalent carboxylic acid and a polyvalent hydroxy compound including an aliphatic group, in order to lower the glass transition point than a general polyester resin, an aliphatic polyvalent compound is used. It is effective to contain a carboxylic acid. From the viewpoint of lowering the glass transition point, the aliphatic polyvalent carboxylic acid should have a long carbon number, preferably 6 or more (adipic acid), more preferably 8 or more, and still more preferably 10 or more. The upper limit of the preferred range is 20.

  Further, from the viewpoint of improving adhesive properties, the content of the aliphatic polyvalent carboxylic acid in the acid component in the polyester resin is preferably 2 mol% or more, more preferably 4 mol% or more, and even more preferably 6 mol%. As mentioned above, it is 10 mol% or more especially preferably, and the upper limit of a preferable range is 50 mol%.

  In the aliphatic polyvalent hydroxy compound, in order to lower the glass transition point, the number of carbon atoms is preferably 4 or more (butanediol), and the content of the hydroxy component in the polyester resin is preferably 10 mol. % Or more, more preferably in the range of 30 mol% or more.

  In consideration of suitability for in-line coating, it is preferable to use an aqueous system. For this purpose, it is preferable that a sulfonic acid, a sulfonic acid metal salt, a carboxylic acid, and a carboxylic acid metal salt are contained in the polyester resin. In view of good dispersibility in water, sulfonic acid and sulfonic acid metal salt are preferable, and sulfonic acid metal salt is particularly preferable.

  When using the sulfonic acid, sulfonic acid metal salt, carboxylic acid, or carboxylic acid metal salt, the content in the polyester resin is preferably 0.1 to 10 mol%, more preferably 0.2 to 8 mol%. Range. By using in the above range, water dispersibility is good.

  In addition, considering the appearance of in-line coating, adhesion to polyester film and blocking, and reduction of adhesive residue on the adherend when used as a surface protection film, as an acid component in the polyester resin, It preferably contains an aromatic polycarboxylic acid. Among aromatic polycarboxylic acids, a benzene ring structure such as terephthalic acid or isophthalic acid is preferable to a naphthalene ring structure from the viewpoint of adhesive properties. In order to further improve the adhesive properties, it is more preferable to use two or more kinds of aromatic polyvalent carboxylic acids in combination.

  As a glass transition point of the polyester resin for improving the adhesive properties, 0 ° C. or less is essential, preferably −10 ° C. or less, more preferably −20 ° C. or less, and the lower limit of the preferred range is − 60 ° C. It becomes easy to set it as the film which has the optimal adhesion characteristic by using in the said range.

  The acrylic resin is a polymer composed of a polymerizable monomer including acrylic and methacrylic monomers (hereinafter, acrylic and methacryl may be abbreviated as (meth) acryl). These may be either homopolymers or copolymers, and copolymers with polymerizable monomers other than acrylic and methacrylic monomers. 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 in a polyester solution or a polyester dispersion is also included. Similarly, a polymer obtained by polymerizing a polymerizable monomer in a polyurethane solution or a polyurethane dispersion (sometimes a mixture of polymers) is also included. Similarly, a polymer (in some cases, a polymer mixture) obtained by polymerizing a polymerizable monomer in another polymer solution or dispersion is also included.

  The polymerizable monomer is not particularly limited, but particularly representative compounds include, for example, various carboxyl groups such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid. Monomers, and salts thereof; such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxyl fumarate, monobutyl hydroxy itaconate Various hydroxyl group-containing monomers; various such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate No (meta) acrylic Acid esters; various nitrogen-containing compounds such as (meth) acrylamide, diacetone acrylamide, N-methylolacrylamide or (meth) acrylonitrile; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene Various vinyl esters such as vinyl propionate and vinyl acetate; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane; phosphorus-containing vinyl monomers; Examples include various vinyl halides such as vinyl and biliden chloride; and various conjugated dienes such as butadiene.

  In order to lower the glass transition point to 0 ° C. or lower, it is necessary to use a (meth) acrylic system having a glass transition point of the homopolymer of 0 ° C. or lower. For example, ethyl acrylate (glass transition point: −22 ° C.), n-propyl acrylate (glass transition point: −37 ° C.), isopropyl acrylate (glass transition point: −5 ° C.), normal butyl acrylate (glass transition point: −55 ° C.), n-hexyl acrylate (glass transition point: − 57 ° C), 2-ethylhexyl acrylate (glass transition point: -70 ° C), isononyl acrylate (glass transition point: -82 ° C), lauryl methacrylate (glass transition point: -65 ° C), 2-hydroxyethyl Examples include acrylate (glass transition point: −15 ° C.).

  From the viewpoint of adhesive properties, the content of the monomer having a homopolymer glass transition point of 0 ° C. or less as the monomer constituting the acrylic resin is preferably 30% by weight or more, more preferably 45%, as a proportion of the entire acrylic resin. % By weight or more, more preferably 60% by weight or more, particularly preferably 70% by weight or more. The upper limit of the preferred range is 99% by weight. It is easy to obtain good adhesive properties by using in this range.

  Moreover, as a glass transition point of the monomer whose homopolymer has a glass transition point of 0 ° C. or lower for improving the adhesive property, it is preferably −20 ° C. or lower, more preferably −30 ° C. or lower, and further preferably −40 ° C. or lower. Especially preferably, it is -50 degrees C or less, and the minimum of a preferable range is -100 degreeC. By using it in the said range, it becomes easy to set it as the film which has moderate adhesive characteristics.

  The monomer used for improving the adhesive properties is preferably an alkyl (meth) in which the alkyl group has 4 to 30 carbon atoms, more preferably 4 to 20 carbon atoms, and even more preferably 4 to 12 carbon atoms. Acrylate. Acrylic resins containing normal butyl acrylate and 2-ethylhexyl acrylate are optimal from the viewpoint of mass production industrially and handling and supply stability.

  As a more optimal form of the acrylic resin for improving the adhesive properties, the total content of normal butyl acrylate and 2-ethylhexyl acrylate in the acrylic resin is preferably 30% by weight or more, more preferably 40% by weight. % Or more, more preferably 50% by weight or more, and the upper limit of the preferred range is 99% by weight.

The glass transition point of the acrylic resin for improving the adhesive properties must be 0 ° C. or lower, preferably −10 ° C. or lower, more preferably −20 ° C. or lower, and further preferably −30 ° C. The lower limit of the preferred range is −80 ° C. It becomes easy to set it as the film which has the optimal adhesion characteristic by using in the said range.

  The urethane resin is a polymer compound having a urethane bond in the molecule, and is usually produced by a reaction between a polyol and an isocyanate. Examples of the polyol include polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

  Polycarbonate polyols are obtained from a polyhydric alcohol and a carbonate compound by a dealcoholization reaction. Examples of the polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane. Diol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane Diol, neopentyl glycol, 3-methyl-1,5-pentanediol, 3,3-dimethylol heptane and the like can be mentioned. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate. Examples of the polycarbonate-based polyols obtained from these reactions include poly (1,6-hexylene) carbonate, poly (3- And methyl-1,5-pentylene) carbonate.

  From the viewpoint of improving adhesive properties, the chain alkyl chain is a polycarbonate polyol composed of a diol component preferably in the range of 4 to 30, more preferably 4 to 20, and even more preferably 6 to 12. In terms of industrial mass production and good handling and supply stability, 1,6-hexanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol It is optimal that it is a copolymerized polycarbonate polyol containing at least two diols selected from among them.

  Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, and the like.

  From the viewpoint of improving the adhesive properties, the monomer forming the polyether is an aliphatic diol, particularly a straight chain fat, preferably having 2 to 30 carbon atoms, more preferably 3 to 20 carbon atoms, and even more preferably 4 to 12 carbon atoms. It is a polyether polyol containing a group diol.

  Polyester polyols include polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides. Product and polyhydric alcohol (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol 2-methyl-2-propyl-1 3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, cyclohexane Diol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyl dialkanolamine, lactone diol, etc.) and those having derivative units of lactone compounds such as polycaprolactone.

  Considering the adhesive properties, among the polyols, polycarbonate polyols and polyether polyols are more preferably used, and polycarbonate polyols are particularly preferable.

  Examples of the polyisocyanate compound used for obtaining the urethane resin include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate, α, α, α ′, α ′. -Aliphatic diisocyanates having aromatic rings such as tetramethylxylylene diisocyanate, aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl Methanzi Cyanate, alicyclic diisocyanates such as isopropylidene dicyclohexyl diisocyanates. These may be used alone or in combination.

  A chain extender may be used when synthesizing the urethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with an isocyanate group. Alternatively, a chain extender having two amino groups can be mainly used.

  Examples of the chain extender having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol, aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene, and esters such as neopentyl glycol hydroxypivalate. And glycols such as glycols. Examples of the chain extender having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine, ethylenediamine, propylenediamine, hexanediamine, 2,2-dimethyl-1,3- Propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10- Aliphatic diamines such as decane diamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isoprobilitincyclohexyl-4,4′-diamine, 1,4-diaminocyclohexane, 1 , 3-Bisaminomethylcyclohexa And alicyclic diamines such as

  The urethane resin in the present invention may use a solvent as a medium, but preferably uses water as a medium. In order to disperse or dissolve the urethane resin in water, there are a forced emulsification type using an emulsifier, a self-emulsification type in which a hydrophilic group is introduced into the urethane resin, and a water-soluble type. In particular, the self-emulsification type in which an ionic group is introduced into the structure of the urethane resin to form an ionomer is preferable because of excellent storage stability of the liquid and water resistance and transparency of the resulting coating layer.

  Examples of the ionic group to be introduced include various groups such as a carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, and quaternary ammonium salt, and a carboxyl group is preferred. As a method for introducing a carboxyl group into a urethane resin, various methods can be taken in each stage of the polymerization reaction. For example, there are a method of using a carboxyl group-containing resin as a copolymer component during prepolymer synthesis, and a method of using a component having a carboxyl group as one component such as polyol, polyisocyanate, and chain extender. In particular, a method in which a desired amount of carboxyl groups is introduced using a carboxyl group-containing diol depending on the amount of this component charged is preferred.

  For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butanoic acid and the like are copolymerized with a diol used for polymerization of a urethane resin. Can do. The carboxyl group is preferably in the form of a salt neutralized with ammonia, amine, alkali metal, inorganic alkali or the like. Particularly preferred are ammonia, trimethylamine and triethylamine. In such a urethane resin, the carboxyl group from which the neutralizing agent has been removed in the drying step after coating can be used as a crosslinking reaction point by another crosslinking agent. Thereby, it is possible to further improve the durability, solvent resistance, water resistance, blocking resistance, and the like of the obtained coating layer, as well as excellent stability in a liquid state before coating.

  The glass transition point of the urethane resin for improving the adhesive properties must be 0 ° C. or lower, preferably −10 ° C. or lower, more preferably −20 ° C. or lower, and further preferably −30 ° C. The lower limit of the preferred range is −80 ° C. It becomes easy to set it as the film which has the optimal adhesion characteristic by using in the said range.

  Moreover, it is also possible to use a crosslinking agent in combination for adjusting the strength and adhesive properties of the coating layer. A conventionally well-known material can be used with a crosslinking agent, For example, an epoxy compound, a melamine compound, an oxazoline compound, an isocyanate type compound, a carbodiimide type compound, a silane coupling compound, a hydrazide compound, an aziridine compound etc. are mentioned. From the viewpoint of the strength of the coating layer and the adjustment of the adhesive property, an epoxy compound, a melamine compound, an oxazoline compound, an isocyanate compound, a carbodiimide compound, and a silane coupling compound are preferable, and an epoxy compound is particularly preferable.

  When a crosslinking agent other than an epoxy compound is used, if the content in the coating layer is too large, the adhesive properties may be deteriorated too much. Therefore, when using a crosslinking agent other than an epoxy compound, it is necessary to pay attention to the content in the coating layer.

  The epoxy compound is a compound having an epoxy group in the molecule, and examples thereof include condensates of epichlorohydrin with ethylene glycol, polyethylene glycol, glycerin, polyglycerin, bisphenol A and the like hydroxyl groups and amino groups, There are polyepoxy compounds, diepoxy compounds, monoepoxy compounds, glycidylamine compounds, and the like. Examples of the polyepoxy compound include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, trimethylolpropane. Examples of the polyglycidyl ether and diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether. , Polypropylene glycol diglycidyl ether, poly Examples of tetramethylene glycol diglycidyl ether and monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and glycidyl amine compounds such as N, N, N ′, N′-tetraglycidyl-m-xylyl. Examples include range amine and 1,3-bis (N, N-diglycidylamino) cyclohexane.

  Of the above, polyether epoxy compounds are preferable from the viewpoint of good adhesive properties. The amount of the epoxy group is preferably a polyepoxy compound that is trifunctional or more polyfunctional than bifunctional.

  The melamine compound is a compound having a melamine skeleton in the compound. For example, an alkylolized melamine derivative, a compound partially or completely etherified by reacting an alcohol with an alkylolated melamine derivative, and these Mixtures can be used. As alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like are preferably used. Moreover, as a melamine compound, either a monomer or a multimer more than a dimer may be sufficient, or a mixture thereof may be used. In view of reactivity with various compounds, it is preferable that the melamine compound contains a hydroxyl group. Further, a product obtained by co-condensing urea or the like with a part of melamine can be used, and a catalyst can be used to increase the reactivity of the melamine compound.

  The oxazoline compound is a compound having an oxazoline group in the molecule, and a polymer containing an oxazoline group is particularly preferable, and 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.

  The amount of the oxazoline group of the oxazoline compound is preferably in the range of 0.5 to 10 mmol / g, more preferably 1 to 9 mmol / g, still more preferably 3 to 8 mmol / g, and particularly preferably 4 to 6 mmol / g. By using in the said range, durability of a coating film improves and it becomes easy to adjust an adhesive characteristic.

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

  When used in the state of blocked isocyanate, the blocking agent includes, for example, bisulfites, phenolic compounds such as phenol, cresol, and ethylphenol, and alcohols such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol, and ethanol. Compounds, active methylene compounds such as dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, mercaptan compounds such as butyl mercaptan and dodecyl mercaptan, lactam compounds such as ε-caprolactam and δ-valerolactam , Amine compounds such as diphenylaniline, aniline, ethyleneimine, acetanilide, acid amide compounds of acetic acid amide, formaldehyde, acetoald Examples include oxime compounds such as oxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime, and these may be used alone or in combination of two or more.

  In addition, the isocyanate compound in the present invention may be used alone, or may be used as a mixture or bond with various polymers. In the sense of improving the dispersibility and crosslinkability of the isocyanate compound, it is preferable to use a mixture or a bond with a polyester resin or a urethane resin.

  A carbodiimide-based compound is a compound having a carbodiimide structure, and is used to improve adhesion with various surface functional layers that can be formed on a coating layer and to improve the heat and humidity resistance of the coating layer. is there. The carbodiimide compound is a compound having one or more carbodiimide or carbodiimide derivative structures in the molecule, but a polycarbodiimide compound having two or more in the molecule is more preferable for better adhesion and the like.

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

  Furthermore, in order not to lose the effect of the present invention, in order to improve the water solubility and water dispersibility of the polycarbodiimide compound, adding a surfactant, polyalkylene oxide, quaternary ammonium salt of dialkylamino alcohol, You may add and use hydrophilic monomers, such as a hydroxyalkyl sulfonate.

  These cross-linking agents are used in a design that improves the performance of the coating layer by reacting in the drying process or film forming process. It can be inferred that unreacted products of these crosslinking agents, compounds after the reaction, or mixtures thereof exist in the finished coating layer.

  In forming the coating layer, particles can be used in combination for blocking, improving slipperiness, and adjusting the adhesive property.

  Further, in the range not impairing the gist of the present invention, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, an ultraviolet absorber, and an antioxidant are formed as necessary for forming the coating layer. It is also possible to use a foaming agent, a dye, a pigment and the like in combination.

  As a ratio in the coating layer constituting the laminated polyester film in the present invention, the resin having a glass transition point of 0 ° C. or lower is essential to use, and the amount is preferably 50% by weight or more, preferably Is in the range of 65% by weight or more, more preferably 75% by weight or more, still more preferably 85% by weight or more, and the upper limit of the preferred range is 99% by weight. When it is out of the above range, sufficient adhesive properties cannot be obtained.

  As a ratio in the coating layer which comprises the laminated polyester film in this invention, the ratio of an epoxy compound is 50 weight% or less, Preferably it is 40 weight% or less, More preferably, it is the range of 30 weight% or less. When used in the above range, good coating strength and adhesive properties can be easily obtained.

  As a ratio in the coating layer constituting the laminated polyester film in the present invention, the ratio of the crosslinking agent other than the epoxy compound is 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight or less. It is easy to obtain good coating strength and adjusted adhesive properties by using in the above range, but depending on the material and composition used in the coating layer, it is preferable not to use it because of the concern that the adhesive properties will be too low. In some cases.

  In the polyester film of the present invention, various coating layers can be provided on the side opposite to the coating layer mainly containing a resin having a glass transition point of 0 ° C. or lower. For example, for the purpose of preventing blocking, a release layer, an antistatic layer for preventing dust adhesion, or an antistatic release layer having both of them may be used.

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

  Regarding the formation of the coating layer, the above-described series of compounds is used as a solution or solvent dispersion, and the coating solution adjusted with a solid content concentration of about 0.1 to 80% by weight as a guide is laminated on the polyester film. It is preferable to produce a polyester film. In particular, since the coating layer is provided by in-line coating, an aqueous solution or a water dispersion is more preferable. A small amount of an organic solvent may be contained in the coating solution for the purpose of improving the dispersibility in water, improving the film forming property, and the like. Moreover, only one type of organic solvent may be used, and two or more types may be used as appropriate.

  Regarding the laminated polyester film in the present invention, the thickness of the coating layer provided on the polyester film is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm, still more preferably 0.05 to 3 μm, particularly preferably. It is in the range of 0.08 to 1.5 μm, most preferably 0.15 to 0.90 μm. By using the film thickness within the above range, it becomes easy to maintain appropriate adhesive properties and blocking properties.

  In the film of the present invention, as a method for forming the coating layer, for example, gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze Conventionally known coating methods such as coating, impregnation coating, kiss coating, spray coating, calendar coating, extrusion coating, etc. 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, but the drying of a solvent such as water used in the coating solution is preferably 70 to It is 150 degreeC, More preferably, it is 80-130 degreeC, More preferably, it is the range of 90-120 degreeC. The drying time is generally 3 to 200 seconds, preferably 5 to 120 seconds. Moreover, in order to improve the mold release performance and intensity | strength of an application layer, In a film manufacturing process, Preferably it is 180-270 degreeC, More preferably, it is 200-250 degreeC, More preferably, it passes through the heat treatment process of the range of 210-240 degreeC. It is. The time for the heat treatment step is generally 3 to 200 seconds, preferably 5 to 120 seconds.

  Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. 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.

  Although the haze of the polyester film of the present invention is not particularly limited, for example, when used for strict inspections such as polarizing plates, transmission of inspection light is important for more accurate inspection. Therefore, a lower haze may be preferable. When used in such applications, the preferred haze is 5.0% or less, more preferably 3.0% or less, still more preferably 2.0% or less, and particularly preferably 0.2 to 1. The range is 5%.

  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) Method for measuring the 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. And dissolved at 30 ° C.

(2) Method for measuring film thickness of coating layer The surface of the coating layer was dyed with RuO ₄ and embedded in an epoxy resin. Thereafter, the section prepared by ultramicrotomy stained with RuO _4, a coating layer cross-section was measured by using a TEM (Hitachi High Technologies Corporation H-7650, accelerating voltage 100 V). The film thickness was measured at a location not including the particle portion.

(3) Glass transition point Using a differential scanning calorimeter (DSC) 8500, manufactured by PerkinElmer Japan Co., Ltd., measurement was performed at −100 to 200 ° C. under a temperature rising condition of 10 ° C. per minute.

(4) Measuring method of haze It measured by JISK7136 using the Murakami Color Research Laboratory make and haze meter HM-150.

(5) Adhesive property evaluation method for coating layer (Adhesion 1)
The application layer side of one A4 size laminated polyester film was piled up and pressed with fingers to evaluate the adhesive properties. 5 points when the film can be held in a curled state by pressing it lightly with a finger, 4 points for when the film can be held in a curled state by pressing it firmly with a finger, film by pressing firmly with a finger Can be held in a rounded state with 3 sticks, but 3 points when peeled off within 3 seconds. A point where no adhesive property was observed even when pressed strongly with a finger was defined as one point. In practical use, three or more points are preferable.

(6) Method for evaluating adhesive properties of coating layer (Adhesion 2)
The coating layer side of one A4 size laminated polyester film and the A4 size polyester film without the coating layer of Comparative Example 1 described later were stacked and pressed with fingers to evaluate the adhesive properties. 5 points when the film sticks with just a finger and you can hold the film even if you have only the film that has the coating layer. 4 points when you can hold the sticking state even if you have only the film you have, the film sticks by pressing firmly with your finger, and keeps the sticking state even if you have only the film that has the coating layer Yes, if the film is peeled off within 3 seconds, press the finger firmly. Press the button with your finger. In the case where no adhesive property was observed, 1 point was assigned. In practical use, two or more points are preferable.

(7) Reworkability evaluation method of coating layer In the evaluation methods (5) and (6), when the same operation is performed again at the same location after the film is peeled off, The case where the adhesive property deteriorated was evaluated as x.

(8) Adhesive residue evaluation method of application layer In the above evaluation method (6), the adhesive film is observed after peeling off the pasted film. The case was marked with x.

The polyester used in the examples and comparative examples was prepared as follows.
<Method for producing polyester (A)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, 30 ppm of ethyl acid phosphate with respect to the resulting polyester, and 100 ppm of magnesium acetate tetrahydrate with respect to the resulting polyester as the catalyst at 260 ° C. in a nitrogen atmosphere at 260 ° C. The reaction was allowed to proceed. Subsequently, 50 ppm of tetrabutyl titanate was added to the resulting polyester, the temperature was raised to 280 ° C. over 2 hours and 30 minutes, the pressure was reduced to 0.3 kPa in absolute pressure, and melt polycondensation was further carried out for 80 minutes. A polyester (A) having 0.63 and an amount of diethylene glycol of 2 mol% was obtained.

<Method for producing polyester (B)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, and magnesium acetate tetrahydrate as a catalyst were subjected to an esterification reaction at 225 ° C. in a nitrogen atmosphere at 900 ppm with respect to the produced polyester. Subsequently, 3500 ppm of orthophosphoric acid was added to the produced polyester, and 70 ppm of germanium dioxide was added to the produced polyester. The temperature was raised to 280 ° C. over 2 hours and 30 minutes, and the pressure was reduced to an absolute pressure of 0.4 kPa. After 85 minutes of melt polycondensation, polyester (B) having an intrinsic viscosity of 0.64 and a diethylene glycol amount of 2 mol% was obtained.

<Method for producing polyester (C)>
In the production method of polyester (A), polyester (C) is obtained using the same method as the production method of polyester (A) except that 0.3 part by weight of silica particles having an average particle diameter of 2 μm is added before melt polymerization. It was.

Examples of compounds constituting the coating layer are as follows.
(Example compounds)
・ Polyester resin: (IA)
Water dispersion of polyester resin (glass transition point: −20 ° C.) having the following composition: Monomer composition: (acid component) dodecanedicarboxylic acid / terephthalic acid / isophthalic acid / 5-sodiumsulfoisophthalic acid // (diol component) ethylene Glycol / 1,4-butanediol = 20/38/38/4 // 40/60 (mol%)
・ Polyester resin: (IB)
Water dispersion of polyester resin (glass transition point: −30 ° C.) having the following composition: Monomer composition: (acid component) dodecanedicarboxylic acid / terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene Glycol / 1,4-butanediol = 30/33/33/4 // 40/60 (mol%)
・ Polyester resin: (IC)
Water dispersion of polyester resin (glass transition point: 30 ° C.) having the following composition: Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / 1,4 -Butanediol / diethylene glycol = 40/56/4 // 45/25/30 (mol%)

・ Acrylic resin: (IIA)
Aqueous dispersion of acrylic resin (glass transition point: −25 ° C.) having the following composition: normal butyl acrylate / methyl methacrylate / 2-hydroxyethyl methacrylate / acrylic acid = 72/23/3/2 (% by weight)
・ Acrylic resin: (IIB)
Aqueous dispersion of acrylic resin (glass transition point: −40 ° C.) having the following composition: normal butyl acrylate / 2-ethylhexyl acrylate / ethyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 30/30/36/2 / 2 (% by weight)
・ Acrylic resin: (IIC)
Aqueous dispersion of acrylic resin (glass transition point: −50 ° C.) having the following composition: 2-ethylhexyl acrylate / lauryl methacrylate / 2-hydroxyethyl methacrylate / acrylic acid / methacrylic acid = 50/25/15/5/5 (weight%)

・ Acrylic resin: (IID)
Aqueous dispersion of acrylic resin (glass transition point: −55 ° C.) having the following composition 2-ethylhexyl acrylate / vinyl acetate / acrylic acid = 78/20/2 (% by weight)
・ Acrylic resin: (IIE)
Aqueous dispersion of acrylic resin (glass transition point: −15 ° C.) having the following composition: normal butyl acrylate / ethyl acrylate / methyl methacrylate / acrylic acid = 45/23/30/2 (% by weight)
・ Acrylic resin: (IIF)
Aqueous dispersion of acrylic resin (glass transition point: 10 ° C.) having the following composition: ethyl acrylate / normal butyl methacrylate / acrylic acid = 25/73/2 (% by weight)

-Urethane resin: (III)
Consisting of 80 parts of polycarbonate polyol having a number average molecular weight of 2000 consisting of 1,6-hexanediol and diethyl carbonate, 4 parts of polyethylene glycol having a number average molecular weight of 400, 12 parts of methylenebis (4-cyclohexylisocyanate), and 4 parts of dimethylolbutanoic acid. An aqueous dispersion obtained by neutralizing a urethane resin with triethylamine (glass transition point: −30 ° C.).

Epoxy compound: (IVA) polyglycerol polyglycidyl ether, which is a polyfunctional polyepoxy compound

Melamine compound: (IVB) hexamethoxymethylol melamine

・ Oxazoline compounds: (IVC)
Acrylic polymer having an oxazoline group and a polyalkylene oxide chain Epocross (Oxazoline group amount = 4.5 mmol / g, manufactured by Nippon Shokubai Co., Ltd.)

-Particles: (V) Silica particles with an average particle size of 0.15 μm

Example 1:
A mixed raw material in which polyesters (A), (B), and (C) were mixed in proportions of 91%, 3%, and 6%, respectively, was used as a raw material for the outermost layer (surface layer), and polyesters (A) and (B) were each 97 %, 3% of the mixed raw material is used as an intermediate layer raw material, each is supplied to two extruders, melted at 285 ° C., and then on a cooling roll set at 40 ° C. Coextruded and cooled and solidified in a layer configuration of layers (surface layer / intermediate layer / surface layer = 2: 21: 2 discharge amount) to obtain an unstretched sheet.
Next, the film was stretched 3.2 times in the machine direction at a film temperature of 85 ° C. using the roll peripheral speed difference, and then the coating liquid 1 shown in Table 1 below was applied to one side of the longitudinally stretched film with the film thickness (dried) After coating to 0.20 μm, guided to a tenter, dried at 95 ° C. for 10 seconds, stretched 4.3 times at 120 ° C. in the transverse direction, and heat-treated at 230 ° C. for 10 seconds. The polyester film was relaxed by 2% in the lateral direction to obtain a polyester film having a thickness of 50 μm.

  When the finished polyester film was evaluated, the adhesive properties were good. The properties of this film are shown in Table 2 below.

Examples 2-18:
In Example 1, it manufactured similarly to Example 1 except having changed the coating agent composition into the coating agent composition shown in Table 1, and obtained the polyester film. The finished polyester film had good adhesive properties as shown in Table 2.

Comparative Example 1:
In Example 1, it manufactured similarly to Example 1 except having not provided the application layer, and obtained the polyester film. When the finished polyester film was evaluated, as shown in Table 2 below, it was a film having no adhesive properties.

Comparative Examples 2-4:
In Example 1, it manufactured similarly to Example 1 except having changed the coating agent composition into the coating agent composition shown in Table 1, and obtained the polyester film. The finished polyester film was a film having no adhesive properties as shown in Table 2.

Comparative Example 5:
On the polyester film without the coating layer obtained in Comparative Example 1, coating solution 1 shown in Table 1 below was coated so that the coating layer thickness (after drying) was 0.40 μm, and the coating layer was coated at 100 ° C. for 60 seconds. Was dried to obtain a polyester film on which a coating layer by off-line coating was laminated. As shown in Table 2, the finished polyester film had good adhesive properties but was poor in adhesive residue.

  The film obtained by the production method of the present invention can be used for, for example, a surface protection film used for transporting resin sheets, metal plates, etc., for preventing scratches and preventing soiling during storage and processing, etc. There are few eyes, it is excellent in mechanical strength and heat resistance, and it can utilize suitably for the use which needs the favorable adhesion characteristic.

Claims (2)

Production of a laminated polyester film characterized in that an adhesive layer having an adhesive property is formed by applying an in-line coating application on at least one surface of a polyester film with a coating liquid mainly containing a resin having a glass transition point of 0 ° C. or less. Method. The method for producing a laminated polyester film according to claim 1, wherein the proportion of the monomer forming the copolyester in the polyester film is 10 mol% or less.