JP5784651B2 - Laminated polyester film - Google Patents

Description

  The present invention relates to a laminated polyester film containing a colorant, and is very excellent in preventing bleeding out of the colorant from the film. For example, it is used for pasting automobile windows, for X-ray bluing, for displays, etc. The present invention relates to a laminated polyester film suitable for film use using a colorant.

  Polyester film is excellent in heat resistance, water resistance, chemical resistance, mechanical strength, dimensional stability, etc., and has been used in various industrial applications, but its applications are expanding and diversifying, and are transparent. It has been used also for the use which makes a colored polyester film by putting a coloring agent in the polyester raw material which has property.

  For example, in the use of a film containing a colorant such as an automobile window pasting film, an X-ray bluing film, and a display use, even if a good colorant such as color preparation, heat resistance and dispersibility is selected, it is severe. Under such heating conditions, the colorant bleeds out from the film containing the colorant, resulting in contamination and haze-up in various manufacturing processes, and therefore there is a need for improvement.

  In order to solve the above problems, Patent Documents 1 and 2 propose a coextruded laminated film comprising three or more layers containing a colorant in an intermediate layer in order to prevent bleeding out of the colorant. However, the film described in the above-mentioned patent document still has insufficient colorant bleed-out prevention performance under severe heating conditions.

Japanese Patent Laid-Open No. 10-157040 JP 2002-52675 A

  This invention is made | formed in view of the said situation, Comprising: The solution subject is providing the polyester film which has the bleed-out prevention property of the outstanding coloring agent also under severe heating conditions.

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

That is, the gist of the present invention is that a polyester film having a three-layer structure containing a colorant in an intermediate layer contains a polyamine having an alkyl chain on at least one side, and has a final dried thickness of 0.001 to 0. The present invention resides in a laminated polyester film characterized by having a coating layer of 5 μm .

  According to the polyester film of the present invention, it is possible to provide a film having excellent colorant bleeding prevention performance, and its industrial value is high.

  The polyester film constituting the 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 the gist of the present invention is not exceeded other than the two-layer or three-layer structure. It may be a multilayer and is not particularly limited. For example, it is possible to change the raw material of the surface layer and the intermediate layer into a three-layer structure for the purpose of effectively improving various properties using a polyester film with high functionality as the surface layer raw material. In the polyester film of the present invention, the surface layer is a layer constituting two exposed surfaces, and the other layers are called intermediate layers.

  In one preferred embodiment of the present invention, the film has a three-layer structure, and a color material is contained only in the intermediate layer, and the surface layer is a polyester layer that does not contain a colorant. There is a method for preventing it.

  The intrinsic viscosity of the polyester composition constituting the surface layer and the intermediate layer is usually 0.3 to 0.9 dl / g, preferably 0.4 to 0.8 dl / g, more preferably 0.5 to 0.8 dl / g. g. When the intrinsic viscosity is less than 0.3 dl / g, the heat resistance and mechanical strength of the film tend to be inferior. On the other hand, if the intrinsic viscosity exceeds 0.90 dl / g, the load becomes excessive in the extrusion process during the production of the polyester film, and as a result, the productivity may decrease.

  The polyester used for the film 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.

  The laminated polyester film of the present invention contains a colorant. In this invention, the structure which contains the coloring agent in the intermediate | middle layer of a multilayer film from a viewpoint of reducing the bleeding out of a coloring agent is preferable.

  As the colorant contained in the polyester layer of the film of the present invention, it is preferable to consider the heat resistance during polyester production and the dispersibility in the polyester, and in terms of chemical structure, anthraquinone, phthalocyanine, Perinone-based and isoquinoline-based colorants are preferably used. These colorants are generally used by appropriately selecting and mixing several kinds, and the content in the raw material polyester constituting each layer is preferably in the range of 0.01 to 10% by weight.

  In the polyester layer of the film of the present invention, particles can be blended mainly for the purpose of imparting slipperiness. The type of particles to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness, and specific examples include, for example, silica, titanium oxide, zeolite, silicon nitride, boron nitride, celite, alumina, carbonic acid. Calcium, Magnesium carbonate, Barium carbonate, Calcium sulfate, Barium sulfate, Calcium phosphate, Lithium phosphate, Magnesium phosphate, Lithium fluoride, Aluminum oxide, Silicon oxide, Titanium oxide, Kaolin, Talc, Carbon black, Silicon nitride, Boron nitride, Crosslinked polymer fine powder can be mentioned, but is not limited thereto.

  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.

  Moreover, the average particle diameter of the particle | grains to be used is 5 micrometers or less normally, Preferably it is the range of 0.01-3 micrometers. When the average particle diameter exceeds 5 μm, the flatness of the film surface may be impaired or the transparency may be impaired.

  Further, the content of the particles in the polyester layer is usually 5% by weight or less, preferably 0.0005 to 3% by weight, based on the polyester layer containing the particles. When there are no or few particles, the transparency of the film becomes high and the film becomes a good film, but the slipperiness becomes insufficient and the winding property of the film may be inferior. In some cases, it is necessary to devise measures such as improving the slipperiness. On the other hand, when the particle content exceeds 5% by weight, the transparency of the film may be insufficient.

  In the present invention, the method of incorporating the particles and the colorant into the polyester is not particularly limited, but the method of adding to the polymerization step, the method of kneading the particles and the colorant using an extruder to obtain a master batch. Etc.

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

  The polyester film constituting the polyester film in the present invention may have a single layer structure or a multilayer structure, but one of the preferred forms in the present invention has a three-layer film structure and contains a colorant only in the intermediate layer. Since the surface layer has a layer structure not containing a colorant, the formation of a polyester film having this structure will be described below.

  The polyester used for the intermediate layer containing a predetermined amount of colorant and the polyester used for the surface layer containing a predetermined amount of particles as needed are supplied to separate melt extrusion apparatuses and heated to a temperature equal to or higher than the melting point of each polymer. Melt. Next, the molten polymer is bonded and laminated in a laminar flow in an extrusion die, extruded from a slit die, rapidly cooled and solidified on a rotating cooling drum to a temperature below the glass transition temperature, and substantially amorphous. An unstretched sheet in a state is obtained. 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.

  Specifically describing the stretching conditions in the present invention, the unstretched sheet is preferably stretched 2 to 6 times at 70 to 120 ° C. in the longitudinal direction to form a uniaxially stretched film, and then at 90 to 160 degrees in the lateral direction. The film is stretched 2 to 6 times to form a biaxially stretched film, and heat treatment is performed at 150 to 250 ° C. for 1 to 600 seconds. Further, at this time, a method of relaxing 0.1 to 15% in the vertical direction and / or the horizontal direction in the maximum temperature zone of the heat treatment and / or the cooling zone at the heat treatment outlet is preferable. Further, it is possible to add re-longitudinal stretching and re-lateral stretching as necessary.

  Next, formation of the coating layer which comprises the laminated polyester film in this invention is demonstrated. Regarding the coating layer, it may be provided by in-line coating, which treats the film surface during the above-mentioned polyester film forming process, or may be applied off-system on a once produced film. . More preferably, it is 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 coated on any of an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, and a film after heat setting and before winding. 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, it can be set as a firm coating layer, and performances such as adhesion to various functional layers that can be formed on the coating layer and wet heat resistance can be improved.

  In the present invention, it is an essential requirement to have a coating layer containing a polyamine having an alkyl chain on at least one surface of the polyester film.

  The polyamine having an alkyl chain in the invention means a compound containing a plurality of primary, secondary and tertiary amines in the molecule of an acyclic and / or cyclic aliphatic compound. The polyamine having any structure can be used in the present invention as long as it can be synthesized.

  In the present invention, it is preferable to use a polymer among polyamines having an alkyl chain from the viewpoint of suppressing bleeding out of the colorant. In the polyamine polymer having an alkyl chain, it is preferable to use a polymer having a high amine content in the molecule, preferably a polymer containing an amine compound having 18 or less carbon atoms as a monomer, more preferably 12 or less carbon atoms. A polymer containing as a monomer, more preferably a polymer containing an amine compound having 6 or less carbon atoms as a monomer, most preferably a polyallylamine containing an amine compound having 3 or less carbon atoms as a monomer , Polyvinylamine, polyethyleneimine, polytrimethyleneimine, and the like. Among these, polyallylamine is preferable.

  The number of carbons described above means the number of carbons of the part that is bonded to the nitrogen atom of the amine and that is involved in forming the polymer. With respect to the number of carbon atoms bonded to the nitrogen atom of the amine that is not involved in the formation of the polymer, the number of carbon atoms is not limited without departing from the gist of the present invention.

  The polyallylamine that can be used in the present invention is a polymer in which an allylamine structure is incorporated, such as a homopolymer of allylamine or a copolymer of allylamine and another polymerizable monomer, and if it can be synthesized. Any structure of polyallylamine may be used.

  Among these polyallylamines, it is preferable to use an allylamine homopolymer from the viewpoint of suppressing bleeding out of the colorant. A specific example of the polyallylamine homopolymer in the present invention is a structure represented by the following chemical formula (1).

R ¹ and R ² are usually an alkyl group such as hydrogen, a methyl group, or an ethyl group, but may have any structure as long as it can be synthesized. R ¹ and R ² may be groups having the same structure or different structures. In the present invention, it is particularly preferable to use a polyallylamine homopolymer having a structure in which R ¹ and R ^{2 in} the chemical formula (1) are both hydrogen from the viewpoint of suppressing bleeding out of the colorant.

  Although there is no restriction | limiting in particular in the weight average molecular weight of the polyallylamine used in this invention, Preferably it is 1000 or more, More preferably, it is 2000-200000, More preferably, it is the range of 5000-100000. When it is outside the above lower limit range, there is a concern that the effect of suppressing bleeding out of the colorant is deteriorated, and when the molecular weight is too large, there is a concern that the handling property of the liquid is deteriorated.

  The ratio of polyallylamine in the coating solution forming the coating layer to the total nonvolatile components is usually 15% by weight or more, preferably 40% by weight or more, more preferably 90% by weight or more. If it is less than 15% by weight, the effect of suppressing bleeding out of the colorant from the laminated film may be reduced.

  In this invention, you may contain a crosslinking agent in the said coating liquid. As crosslinking agents, melamine compounds, guanamines, alkylamides, polyamide amino resin compounds, epoxy compounds, oxazoline compounds, aziridine compounds, isocyanate compounds, carbodiimide compounds, silane coupling agents, dialcohol aluminate coupling agents, Zircoaluminate coupling agents, peroxides, heat or photoreactive vinyl compounds, photosensitive resins, and the like can be mentioned. From the viewpoint of improving mechanical strength, use of epoxy compounds and oxazoline compounds is particularly preferable.

  In the present invention, the coating solution may contain one or more polymers for the purpose of improving the film forming property of the coating film, and the structure and ionicity of the polymer to be used are not particularly limited. Examples of the polymer include polyester resins, polyurethane resins, acrylic resins, vinyl resins such as polyvinyl alcohol, epoxy resins, amide resins, and other anions having sulfonic acid groups, sulfate groups, carboxyl groups, phosphates, etc. in the molecule. And a cationic group-containing resin having a quaternary ammonium base such as a pyrrolidinium ring or a quaternized alkylamine in the molecule.

  In addition, these skeleton structures may have a composite structure by copolymerization or the like. Examples of the polymer having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, acrylic resin graft anionic group. Resin, acrylic resin graft cationic group-containing resin, vinyl resin graft polyester, vinyl resin graft polyurethane and the like.

  Among the above polymers, from the viewpoint of compatibility with other substances in the coating solution, it is preferable to use a polyester resin, an acrylic resin, polyvinyl alcohol, or a cationic group-containing resin as the polymer.

  In the present invention, particles may be contained in the coating solution for improving the slipperiness of the coating layer. Examples of the particles include inert inorganic particles such as silica, alumina, calcium carbonate, titanium dioxide, fine particles obtained from polystyrene resins, polyacrylic resins, polyvinyl resins, or organic particles represented by these crosslinked particles. .

  In addition, for the formation of the coating layer, colors such as antifoaming agents, coating property improvers, thickeners, antistatic agents, mold release agents, antioxidants, ultraviolet absorbers, foaming agents, dyes and pigments are necessary. An agent or the like may be used in combination.

Further, the coating solution preferably contains water as a main medium, and may contain a small amount of an organic solvent for the purpose of improving dispersion in water or improving the film forming performance. When the organic solvent is used by being mixed with water, which is the main medium, it is desirable to use it in a range that dissolves in water.
Examples of the organic solvent include aliphatic or alicyclic alcohols such as n-butyl alcohol, n-propyl alcohol, isopropyl alcohol, ethyl alcohol and methyl alcohol, glycols such as ethylene glycol, propylene glycol and diethylene glycol, and n-butyl. Cellosolve, ethyl cellosolve, methyl cellosolve, glycol derivatives such as propylene glycol monomethyl ether, ethers such as dioxane and tetrahydrofuran, esters such as ethyl acetate and amyl acetate, ketones such as methyl ethyl ketone and acetone, N-methylpyrrolidone Amides such as, but not limited to. These organic solvents may be used alone or in combination of two or more as required.

  When the coating layer is provided on the film of the present invention, the thickness is usually 0.001 to 0.5 μm, preferably 0.005 to 0.3 μm, more preferably 0.01 to the thickness after final drying. 0.2 μm. When the thickness of the coating layer exceeds 0.5 μm, the films are likely to block each other, and particularly when the stretched coated film is re-stretched for the purpose of increasing the strength of the film, it tends to stick to the roll during the process. May be. If the thickness of the coating layer is less than 0.001 μm, the colorant bleeding-out prevention performance may be deteriorated.

  Examples of the method for coating the polyester film with the coating solution for forming the coating layer of the present invention include, for example, gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, Conventionally known coating methods such as knife coating, transfer roll coating, squeeze coating, impregnation coating, kiss coating, spray coating, calendar coating, extrusion coating and the like can be used.

  In addition, in order to improve the applicability | paintability to the film of a coating liquid and adhesiveness, you may give a chemical process, an electrical discharge process, etc. to a film before application | coating. In addition, in order to improve the surface characteristics of the coating layer of the film of the present invention, the surface of the coating layer may be subjected to chemical treatment or discharge treatment after the coating layer is formed.

  When processing the laminated polyester film of the present invention, on the opposite side of the coated layer surface of the laminated polyester film of the present invention, the properties required according to the required properties, such as adhesion, antistatic properties, weather resistance and surface hardness are improved. Therefore, various coats such as an in-line coat and an off-line coat may be performed.

In the present invention, ΔE ^* ab is used for evaluating the bleeding out of the colorant on the surface of the laminated film. The ΔE ^* ab value is obtained by heating the laminated film, extracting the coated surface of the film with dimethylformamide, and obtaining the L ^* value, a ^* value, and b ^* value of the extract and reference dimethylformamide with a spectrophotometer. The difference ΔL ^* , Δa ^* , Δb ^* is substituted into the following formula (1) for calculation.

ΔE ^* ab = [(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² )] ^1/2
The lower the value of ΔE ^* ab, the higher the transparency of the extract, and it can be said that the colorant bleed-out to the surface of the laminated film is suppressed.

In the present invention, from the viewpoint of practicality, the value of ΔE ^* ab is preferably 10 or less, more preferably 5 or less, and most preferably 3 or less.

  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 physical property measurement method used in the present invention is shown below.

(1) Intrinsic viscosity (dl / g)
A mixed solvent of phenol / tetrachloroethane: 50/50 (weight ratio) was added to 1 g of polyester at a ratio of 100 ml, and the mixture was measured at 30 ° C.

(2) Average particle diameter of added particles (μm)
Using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 manufactured by Shimadzu Corporation, the particle size was measured by a sedimentation method based on Stokes' resistance law. The average particle diameter was determined by using a value of 50% of integration (volume basis) in the equivalent spherical distribution of particles obtained by measurement.

(3) 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).

(4) Bleed-out prevention performance evaluation of colorant (ΔE ^* ab value evaluation)
The films prepared in the examples and comparative examples are heated in an oven at 180 degrees for 10 minutes.
Thereafter, the heat-treated film is folded so that the surface of the coating layer is inside the box, and a box shape having a length of 20 cm, a width of 12.5 cm, and a height of 5 cm is formed. Next, 10 mL of dimethylformamide was put in contact with the bottom surface (250 cm ² ) of the box prepared by the above method and allowed to stand for 3 minutes, and then the dimethylformamide was recovered, 12.5 mm in length, 12.5 mm in width, height Placed in a 45 mm quartz liquid cell, the liquid cell was installed in a spectrophotometer “UV-3100PC” manufactured by Shimadzu Corporation so that the optical path length was 12.5 mm, and the transmittance was measured. The L ^* value, a ^* value, and b ^* value at the time of visual field and standard D65 light source were obtained. Similarly, the L ^* value, a ^* value, and b ^* value of the reference dimethylformamide are obtained, and the differences ΔL ^* , Δa ^* , and Δb ^* are substituted into the above-described formula (1), and the reference dimethylformamide is calculated. ΔE ^* ab value was calculated.

(5) Bleed-out prevention performance evaluation of colorant (visual evaluation)
The film is heated in a 180 degree oven for 10 minutes. Thereafter, the heat-treated film is folded so that the surface of the coating layer is inside the box, and the upper part is opened to form a box shape having a length of 20 cm, a width of 12.5 cm, and a height of 5 cm. Place 10 mL of dimethylformamide so that it touches the bottom (250 cm ² ) of the box prepared in step 3 and leave it for 3 minutes. Then, collect dimethylformamide and visually determine the degree of colorant extraction under a fluorescent lamp. Evaluation was made according to the following criteria.

A: Almost no outflow of colorant is observed. O: Very slight outflow of colorant is observed. X: The outflow degree of the colorant is severe.

The composition component which comprises the coating layer used by the Example and the comparative example is as showing below.
In addition, the weight% used in Examples and Comparative Examples means weight% in a nonvolatile content.

[Compositional components constituting the coating layer]
(A) Polyallylamine (A-1): Allylamine homopolymer having a weight average molecular weight of 25000 in the chemical formula (1) described in the specification (A-2): Weight of the chemical formula (1) described in the specification Allylamine homopolymer (A-3) having an average molecular weight of 1600: Allylamine homopolymer having a weight average molecular weight of 8,000 in the chemical formula (1) described in the specification

(B) Polymer (B-1)
Copolymerized diallyldimethylammonium chloride, N-methylolacrylamide and NNdimethylacrylamide in a weight ratio of 90/5/5, containing a cationic group having a cation in the main chain having a number average quantity of 20000 Resin (B-2): Acrylic resin having a glass transition temperature (Tg) of 50 ° C. obtained by copolymerization of acrylic acid alkyl ester and methacrylic acid alkyl ester (B-3): polyester resin acid component having the following composition : Terephthalic acid / isophthalic acid / 5-sodiumsulfoisophthalic acid // diol component: ethylene glycol / 1,4-butylene glycol = 55/40/5 // 65/35 (mol%)

(C) Crosslinking agent (C-1): polyglycerol polyglycidyl ether.
(C-2): Epocross WS-500 which is an oxazoline compound (manufactured by Nippon Shokubai Co., Ltd.)
(D) Silica particles having an average particle diameter of 0.07 μm

≪Production of polyester-A≫
100% by weight of dimethyl terephthalate and 60% by weight of ethylene glycol are used as starting materials, 0.09% by weight of magnesium acetate tetrahydrate as a catalyst is placed in a reactor, the reaction start temperature is set to 150 ° C. The reaction temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially completed. To this reaction mixture, 0.04% by weight of ethyl acid phosphate, 0.04% by weight of antimony trioxide and 0.05% by weight of silica particles having an average particle size of 1.9 μm were added, and a polycondensation reaction was performed for 4 hours. . That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After 4 hours from the start of the reaction, the reaction was stopped and the polymer was discharged under nitrogen pressure. The intrinsic viscosity of the obtained polyester was 0.65 dl / g.

≪Production of polyester-B≫
In the production of polyester-A, a polyester was obtained in the same manner as for polyester-A, except that 0.05% by weight of silica particles having an average particle size of 1.9 μm was not added and the polycondensation reaction was carried out for 3 hours and 15 minutes. Further, this polyester was subjected to solid phase polymerization for 15 hours under the condition of 225 ° C.-0.3 mmHg. The intrinsic viscosity of the obtained polyester was 0.78 dl / g.

≪Production of polyester-C≫
After drying 100% by weight of Polyester-B, Mitsubishi Chemical Co., Ltd. Dialresin Red HS (Perinone series) 0.4% by weight, Mitsubishi Chemical Co., Ltd. Dialresin Blue H3G (Anthraquinone series) 0.8% by weight, Further, 0.3% by weight of Dialresin Yellow F (isoquinoline) manufactured by Mitsubishi Chemical Corporation was melt-kneaded with an extruder to obtain Polyester-C. The intrinsic viscosity of the obtained polyester was 0.61 dl / g.

Example 1:
Using polyester-A as a raw material for the surface layer and polyester-C as a raw material for the intermediate layer, each was supplied to two extruders, melted at 285 ° C., and then on a cooling roll set at 30 ° C. The layers were coextruded so as to have a thickness composition ratio of A / C / A = 3/19/3, and cooled and solidified to obtain an unstretched sheet. Next, the film was stretched 3.4 times in the machine direction at a film temperature of 85 ° C. using the difference in peripheral speed of the roll, and then the coating solution shown in Table 1 was applied to one side of the machined film, guided to a tenter, and transverse direction After being stretched 4.3 times at 93 ° C., heat treatment was performed at 225 ° C. to obtain a 25 μm thick polyester film having a coating layer having a coating layer thickness (after drying) of 0.05 μm. When the obtained polyester film was evaluated, as shown in Table 2 below, the bleeding-out prevention performance of the colorant was good.

Examples 2-13:
A polyester film was obtained in the same manner as in Example 1 except that the coating solution applied in Example 1 was changed to the coating composition and coating thickness shown in Table 1 below. As shown in Table 2 below, the obtained polyester film had good bleeding-out prevention performance of the colorant.

Comparative Examples 1-4:
A polyester film was obtained in the same manner as in Example 1 except that the coating solution applied in Example 1 was changed to the coating composition and coating thickness shown in Table 1 below. As shown in Table 2 below, the resulting polyester film had extremely poor colorant bleeding out prevention performance.

  In addition, the numerical value described in the compounding ingredient column of Table 1 represents weight% in the non volatile matter in a coating liquid.

  The film of the present invention can be suitably used in the use of a film containing a colorant such as an automobile window pasting film, an X-ray bluing film, and a display use.

Claims (2)

At least one side of a three-layer polyester film containing a colorant in the intermediate layer has a coating layer containing a polyamine having an alkyl chain and having a final dried thickness of 0.001 to 0.5 μm. A laminated polyester film characterized by The laminated polyester film according to claim 1, wherein the polyamine having an alkyl chain is a polymer containing an amine compound having 18 or less carbon atoms as a monomer.