JP3395493B2 - Laminated polyester film and method for producing laminated polyester film - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminated polyester film and a method for producing the same, and more particularly to a laminated polyester film excellent in easy adhesion and a method for producing the same.

[0002]

2. Description of the Related Art Biaxially oriented polyester films are excellent in mechanical properties, electrical properties, dimensional stability, heat resistance, transparency, chemical resistance, etc. It is widely used as a base film for many applications such as insulating materials, various photographic materials, photosensitive materials, heat-sensitive materials and graphic arts materials.

In these applications, the polyester film is not generally used alone, but various coatings such as magnetic paint, UV ink, chemical mat paint, diazo photosensitive paint, sublimation type ink, gelatin composition are used on the film surface. The composition, the heat-sealing composition, etc. are applied or printed and used.

Generally, since the surface of the biaxially oriented polyester film is highly crystalline oriented, various paints, adhesives,
It has the disadvantage of poor adhesion to ink. Therefore, it has been proposed in the past to provide the polyester film surface with easy adhesion by various methods.

For example, a method of laminating a polyester resin on a base film by a co-extrusion method, corona discharge treatment in various gas atmospheres on the film surface, plasma treatment, ultraviolet irradiation treatment, flame treatment and the like surface activation. Method, a surface etching method using an agent such as acid or alkali, trichloroacetic acid, amine or phenol, or a method of forming various resins such as polyester, acryl, polyurethane and acryl graft polyester on the film surface as a primer layer (JP-A-55-55). 15825, JP-A-5
No. 8-78761, JP-A-60-248232, JP-A-1-171988, etc.) are already known. In particular, a method of laminating an easily adhesive polyester resin by a co-extrusion method or a method of providing an easily adhesive property by providing the primer layer by coating, that is, a polyester film before crystal orientation is completed, if necessary, a corona A method of applying a discharge treatment, applying a coating liquid containing the above resin component, drying, stretching and heat treatment to complete crystal orientation (in-line coating method) and the like are performed in the art.

[0006]

However, the above-mentioned conventional technique has the following problems.

A product obtained by coating an acrylic resin on a polyester film in order to impart adhesiveness has excellent adhesiveness with coating materials such as various inks, but on the other hand, the adhesiveness between the acrylic resin itself and the base polyester film is high. It has the disadvantage of being inferior.

A polyester film coated with a polyester resin or laminated by a co-extrusion method has excellent adhesiveness between the base polyester film and the polyester resin, but the essential coating material for various inks and the like. It had a drawback that it had poor adhesiveness with.

The present invention eliminates these drawbacks, and not only the adhesiveness between the base polyester film and the laminated film,
Excellent adhesion to various inks, for example, printing materials such as labels, magnetic recording materials such as prepaid cards, photosensitive materials, graphic materials, industrial materials such as sublimation type thermal transfer materials, and laminated films useful as packaging materials. The purpose is to provide. Another object of the present invention is suitable for producing a laminated film having the above-mentioned property of easy adhesion, and also provides a novel and effective method as a general method for producing a laminated film. There is also a thing.

[0010]

The laminated polyester film of the present invention which achieves the above-mentioned object has the following constitution.

[0011] That is, the laminated polyester Fi <br/> Lum of the present invention is substantially on at least one surface of a polyester film
Is a laminated polyester film provided with a laminated film formed by coating a single layer , wherein the surface layer of the laminated film is composed mainly of an acrylic resin and a melamine-based cross-linking agent, and the surface layer of the laminated film. And an intermediate layer having a polyester resin as a main constituent component between the polyester film and the polyester film to form the laminated film , and
At the interface between the surface layer and the intermediate layer of the laminated film, the mixture of phases forming each layer is
The laminated polyester film is characterized by the presence of an in-phase region .

The method for producing a laminated polyester film of the present invention which achieves the above-mentioned other objects of the present invention has the following constitution.

[0013] In other words, at least on one side of the polyester film before the substantially crystalline orientation is completed, at least when
Also, a water-based resin coating liquid in which a polyester resin, an acrylic resin, and a melamine-based crosslinking agent are mixed is applied, and then the applied water-based resin coating liquid is dried under two or more different set drying conditions. A method for producing a laminated polyester film, which comprises subjecting the polyester film to a treatment and then stretching the polyester film in at least a uniaxial direction.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The laminated polyester film of the present invention and the method for producing the laminated polyester film will be described in more detail below.

In the laminated polyester film of the present invention, polyester is a general term for polymers having an ester bond as a main bonding chain of the main chain. Preferred polyesters are ethylene terephthalate, ethylene-2,
6-naphthalate, butylene terephthalate, ethylene-α, β-bis (2-chlorophenoxy) ethane-4,
At least 1 selected from 4'-dicarboxylate and the like
It is possible to use those having a seed constituent as a main constituent. These constituent components may be used alone or in combination of two or more kinds. Among them, it is particularly preferable to use a polyester containing ethylene terephthalate as a main constituent component in view of quality, economy and the like. Polyethylene-2,6-naphthalate, which is excellent in heat resistance and rigidity, is more preferable in applications where heat acts on a substrate such as electrophotographic materials, heat-sensitive recording materials, and image-receiving sheets for recording such as various kinds of printing.

Further, these polyesters further contain a part of other dicarboxylic acid components and diol components, preferably 2 parts.
0 mol% or less may be copolymerized.

Further, in this polyester, various additives such as antioxidants, heat resistance stabilizers, weather resistance stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, An antistatic agent, a nucleating agent, a cross-linking agent, etc. may be added to the extent that the characteristics are not deteriorated.

The intrinsic viscosity of the above-mentioned polyester (25 ° C.
Measured in o-chlorophenol) of 0.4-1.2d
1 / g is preferable, more preferably 0.5 to 0.8 dl
Those in the range of / g are suitable for carrying out the present invention.

The polyester film using the above polyester is preferably biaxially oriented when the laminated film is provided. The biaxially oriented polyester film generally means a polyester sheet or film in an unstretched state in the longitudinal direction and the width direction.
It is drawn about 5 to 5 times, then heat-treated to complete the crystal orientation, and shows a biaxial orientation pattern in wide-angle X-ray diffraction.

The thickness of the polyester film is not particularly limited and may be appropriately selected depending on the application, but is usually 0.5-5.
The thickness is 00 μm, preferably 1 to 300 μm. Further, the obtained film can be laminated by various methods to form a thicker film. In addition, a white polyester film can be preferably used as a base film for image receiving sheets, card applications such as prepaid cards and IC cards. The white polyester film is not particularly limited as long as it is a polyester film colored white, but the whiteness is preferably 85 to 150%, more preferably 90 to 130%.
And the optical density is preferably 0.5 to 5, and more preferably 1.2 to 3. For example, when using a magnetic recording card as an example, when a base film having a low degree of whiteness is used, coloring due to the magnetic recording layer and the like easily penetrates the appearance of the printed layer on the surface, while the optical density is low. The reason is that sufficient light reflection cannot be obtained, whiteness is reduced when viewed with the naked eye, the opposite surface is affected, or trouble may occur depending on the measuring method for reading magnetic recording.

The method for obtaining such optical density and whiteness is not particularly limited, but usually, it can be obtained by adding a resin incompatible with inorganic particles or polyester. The amount to be added is not particularly limited, but in the case of inorganic particles, preferably 5 to 35% by weight, more preferably 8 to 2%.
It is 5% by weight. On the other hand, when an incompatible resin is added, it is preferably 5 to 35% by volume, more preferably 8 to 2%.
It is 5% by volume.

The inorganic particles are not particularly limited, but preferably have an average particle size of 0.1 to 4 μm, more preferably 0.3 to.
Inorganic particles of 1.5 μm or the like can be used as a typical one. Specifically, barium sulfate, calcium carbonate, calcium sulfate, titanium oxide, silica, alumina, talc, clay, etc., or a mixture thereof can be used, and these inorganic particles include other inorganic compounds such as calcium phosphate, titanium oxide, mica. , Zirconia, tungsten oxide, lithium fluoride, calcium fluoride and the like. Further, among the above-mentioned inorganic particles, it is more preferable to use one having a Mohs hardness of 5 or less, preferably 4 or less, because the whiteness is further increased.

The resin incompatible with the above-mentioned polyester is not particularly limited. For example, in the case of mixing with polyethylene terephthalate or polyethylene-2,6-naphthalate, acrylic resin, polyethylene, polypropylene, modified olefin resin, A polybutylene terephthalate resin, a phenoxy resin, a polyphenylene oxide, or the like can be used, and naturally, the inorganic particles described above may be used in combination. For example, in particular, a white polyester film having a specific gravity of 0.5 to 1.3, which has inorganic particles or a resin incompatible with polyester and is biaxially stretched and has a cavity inside, has good printability. preferable.

The polyester resin, which is a constituent component of the laminated film in the polyester film of the present invention, has an ester bond in the main chain or side chain. Such a polyester resin can be obtained by polycondensing a dicarboxylic acid and a diol.

As the carboxylic acid component constituting the polyester resin, aromatic, aliphatic or alicyclic dicarboxylic acid or polyvalent carboxylic acid having a valence of 3 or more can be used. Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid,
1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bisphenoxyethane-p, p'-dicarboxylic acid, phenylindanedicarboxylic acid and the like can be used. From the viewpoint of strength and heat resistance of the laminated film, these aromatic dicarboxylic acids are preferably 30 mol% or more of all dicarboxylic acid components,
It is more preferable to use 35 mol% or more, and further preferably 40 mol% or more. Examples of the aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and 1,4-cyclohexane. Dicarboxylic acid, etc.
And their ester-forming derivatives can be used.

As the glycol component of the polyester resin, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3
-Butanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,7
-Heptanediol, 1,8-octanediol, 1,
9-nonanediol, 1,10-decanediol, 2,
4-dimethyl-2-ethylhexane-1,3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3 -Methyl-1,5
-Pentanediol, 2,2,4-trimethyl-1,6
-Hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-
Cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thiodiphenol, bisphenol A, 4,4'-methylenediphenol, 4,4 '-(2 -Norbornylidene)
Diphenol, 4,4'-dihydroxybiphenol,
o-, m-, and p-dihydroxybenzene, 4,
4'-isopropylidenephenol, 4,4'-isopropylidenebindiol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol and the like can be used.

When the polyester resin is used as a coating liquid containing an aqueous resin, a compound containing a carboxylate group or a sulfone is used in order to improve the adhesiveness of the polyester resin or to facilitate the water solubility of the polyester resin. It is preferable to copolymerize a compound containing an acid base.
In particular, in applications where moisture-resistant adhesiveness is required, as the polyester resin constituting the laminated film, a compound containing a carboxylate group is used without copolymerizing a compound having strong basicity represented by a sulfonate group. Copolymerization is desirable.

Examples of the compound containing a carboxylate group include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, trimesic acid, 1,
2,3,4-butanetetracarboxylic acid, 1,2,3,4
-Pentanetetracarboxylic acid, 3,3 ', 4,4'-benzophenonetetracarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-cyclohexene-
1,2-dicarboxylic acid, cyclopentanetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid,
1,2,5,6-naphthalenetetracarboxylic acid, ethylene glycol bistrimellitate, 2,2 ', 3,3'
-Diphenyltetracarboxylic acid, thiophene-2,3
It is possible to use 4,5-tetracarboxylic acid, ethylene tetracarboxylic acid, etc., or their alkali metal salts, alkaline earth metal salts, ammonium salts, but not limited to these.

Examples of the compound containing a sulfonate group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4
-Sulfoisophthalic acid, 4-sulfonaphthalene-2,7
-Dicarboxylic acid, sulfo-p-xylylene glycol,
2-sulfo-1,4-bis (hydroxyethoxy) benzene or the like, or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof can be used, but is not limited thereto.

As the polyester resin, it is also possible to use a modified polyester copolymer such as a block copolymer or a graft copolymer modified with acryl, urethane or epoxy.

Preferred polyester resins include terephthalic acid, isophthalic acid, sebacic acid, trimellitic acid, pyromellitic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene as the acid component. -1,2-dicarboxylic acid, ethylene glycol as a glycol component, diethylene glycol, 1,4
-A copolymer selected from butanediol and neopentyl glycol.

The polyester resin used for the laminated film of the laminated polyester film of the present invention can be manufactured by the following manufacturing method. For example, a polyester resin composed of terephthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid as a dicarboxylic acid component and ethylene glycol and neopentyl glycol as a glycol component will be described. Terephthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid and ethylene A first step in which a glycol or neopentyl glycol is directly esterified or a transesterification reaction between terephthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid and ethylene glycol or neopentyl glycol is performed, and the reaction in this first step It can be produced by a method of producing by a second step in which the product is subjected to polycondensation reaction.

At this time, as the reaction catalyst, for example, alkali metal, alkaline earth metal, manganese, cobalt, zinc,
Antimony, germanium, titanium compounds and the like can be used.

As a method for obtaining a polyester resin having a large amount of carboxylic acid at the terminal and / or side chain,
JP-A-54-46294, JP-A-60-2090
73, JP-A-62-240318, JP-A-53-26828, JP-A-53-26829, JP-A-53-98336, and JP-A-56-11.
It can be produced by a resin obtained by copolymerizing a polyvalent carboxylic acid having a valence of 3 or more as described in JP 6718, JP 61-124684, JP 62-240318 and the like. It may be a method.

In the present invention, the intrinsic viscosity of the polyester resin used for the laminated film is not particularly limited, but from the viewpoint of adhesiveness, it is preferably 0.3 dl / g or more, more preferably 0.35 dl / g or more, Most preferably 0.
It is 4 dl / g or more. The glass transition point (hereinafter abbreviated as Tg) of the water-based polyester resin is 0 to 9
It is preferably 0 ° C., more preferably 10 to 80.
℃. If the Tg is less than 0 ° C, the moisture-resistant adhesiveness will be poor, and if it exceeds 90 ° C, the resin film-forming property will be inferior, which is not preferable. Further, the acid value of the water-based polyester resin is preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more in terms of adhesiveness, particularly moisture-resistant adhesiveness.

The acrylic resin, which is a constituent component of the laminated film in the polyester film of the present invention, is, for example, an alkyl acrylate or an alkyl methacrylate (wherein the alkyl group is a methyl group, an ethyl group, n -Propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-
Ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group, etc.), 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, etc. Group-containing monomer, acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N-methylol acrylamide, N-
Methylol methacrylamide, N, N-dimethylol acrylamide, N-methoxymethyl acrylamide, N
Amide group-containing monomers such as methoxymethylmethacrylamide and N-phenylacrylamide, amino group-containing monomers such as N, N-diethylaminoethyl acrylate and N, N-diethylaminoethyl methacrylate, and epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate , Acrylic acid, methacrylic acid and monomers containing a carboxyl group such as a salt thereof (lithium salt, sodium salt, potassium salt, etc.) or a salt thereof can be used. These can be used alone or in combination of two or more. Copolymerized. Furthermore, they can be used in combination with other types of monomers.

Examples of other types of monomers include epoxy group-containing monomers such as allyl glycidyl ether, styrene sulfonic acid, vinyl sulfonic acid and sulfones such as salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.). A monomer containing an acid group or a salt thereof,
Monomers containing carboxyl groups such as crotonic acid, itaconic acid, maleic acid, fumaric acid and their salts (lithium salt, sodium salt, potassium salt, ammonium salt, etc.) or salts thereof, maleic anhydride, itaconic anhydride, etc. Monomers containing acid anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid Monoester, vinylidene chloride, vinyl acetate, vinyl chloride and the like can be used.

Further, as the acrylic resin may be used, modified polyester copolymer, For example, U Etat <br/> down, block copolymers modified with epoxy or the like is also possible.

The glass transition point (Tg) of the acrylic resin used in the present invention is not particularly limited, but is preferably 0 to 90 ° C, more preferably 10 to 80.
℃. When an acrylic resin having a low Tg is used, the adhesiveness under high temperature and high humidity tends to be poor, and when it is too high, cracking may occur during stretching, which is not preferable. The molecular weight of the acrylic resin is preferably 100,000 or more,
More preferably, it is 300,000 or more in terms of adhesiveness.

The preferred acrylic resin used in the present invention is a copolymer selected from methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-methylol acrylamide, glycidyl methacrylate and acrylic acid. Is.

In producing the laminated polyester film of the present invention, a method of applying a water-based resin coating solution to a polyester film before completion of crystal orientation and completing crystal orientation by stretching and heat treatment is performed at high temperature. It is particularly preferable because heat treatment is possible and a more uniform and thin laminated film can be obtained. When the laminated film is formed by the above method, the acrylic resin is preferably an aqueous resin that can be dissolved, emulsified or suspended in water, from the viewpoint of environmental pollution and explosion proof. Such water-based acrylic resins are copolymerized with monomers having a hydrophilic group (acrylic acid, methacrylic acid, acrylamide, vinyl sulfonic acid and salts thereof, etc.) or emulsion polymerization using a reactive emulsifier or a surfactant.
It can be prepared by a method such as suspension polymerization or soap-free polymerization.

In the laminated film of the laminated polyester film of the present invention, when the surface layer contains the acrylic resin and the melamine-based cross-linking agent as main constituents, the adhesiveness (moisture resistance) under high humidity is remarkably improved. Found. Further, the intermediate layer between the surface layer of the laminated film and the polyester film has a polyester resin as a main constituent, but a melamine-based crosslinking agent may be contained in the intermediate layer.

The melamine-based crosslinking agent used is not particularly limited, but melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde,
A compound obtained by partially or completely etherifying a methylolated melamine with a lower alcohol, a mixture thereof, or the like can be used. The melamine-based cross-linking agent may be either a monomer, a condensate composed of a dimer or higher polymer, or a mixture thereof. As the lower alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like can be used. As the functional group, an imino group, a methylol group,
Alternatively, those having an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, and imino group-type methylated melamine resin, methylol group-type melamine resin,
Examples include methylol-based methylated melamine resin and completely alkyl-type methylated melamine resin. Among them, the methylolated melamine resin is the most preferable. Further, an acidic catalyst such as p-toluenesulfonic acid may be used to accelerate the thermal curing of the melamine-based crosslinking agent. Further, as long as the effect of the present invention is not impaired, other crosslinking agents such as methylolated or alkylolated urea-based, acrylamide-based, polyamide-based resin, epoxy compound,
You may use together an isocyanate compound, an aziridine compound, a silane coupling agent, a titanium coupling agent, etc.

The amount of the melamine-based cross-linking agent added is not particularly limited, but in order to bring out the effect of the present invention more remarkably, to 100 parts by weight of the solid content used as the coating liquid,
Preferably 0.5 to 50 parts by weight, more preferably 1 to 4
0 parts by weight, most preferably 2 to 20 parts by weight. That is, when an acrylic resin is used, preferably 0.5 to 50 parts by weight with respect to 100 parts by weight of the acrylic resin solid content,
More preferably 1 to 40 parts by weight, most preferably 2 to 2
0 parts by weight, and when the acrylic resin and the polyester resin are mixed and used, the amount is preferably 0.5 with respect to 100 parts by weight of the total solid content of the acrylic resin and the polyester resin.
-50 parts by weight, more preferably 1-40 parts by weight, most preferably 2-20 parts by weight.

Further, in the laminated film, other resins and modified products thereof, for example, polyester resins, acrylic resins, urethane resins, polyolefin resins, polycarbonate resins other than those of the present invention, within the range in which the effects of the present invention are not impaired, An epoxy resin, a urea resin, a phenol resin, a vinyl chloride resin, a fluororesin, a silicone resin, a rubber resin or the like may be blended.

Further, in the laminated film, various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, an organic slippery agent, a pigment, etc. are added within the range where the effects of the present invention are not impaired. Dyes, organic or inorganic fine particles, fillers, antistatic agents, nucleating agents and the like may be added.

In particular, in carrying out the present invention, a composition in which inorganic particles are added and blended in a coating solution and biaxially stretched is more preferable because slipperiness is improved.

The inorganic particles to be added are typically:
Silica, colloidal silica, alumina, alumina sol,
Kaolin, talc, mica, calcium carbonate and the like can be used. The inorganic particles used have an average particle size of 0.0
It is preferably from 1 to 10 μm, more preferably from 0.05 to 5 μm, most preferably from 0.08 to 2 μm, and the compounding ratio to the solid content in the coating liquid is not particularly limited, but the weight ratio is 0. The amount is preferably 05 to 8 parts by weight, more preferably 0.1 to 3 parts by weight.

In carrying out the present invention, as a method of applying the water-based resin, for example, a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method or the like can be used.

The thickness of the laminated film is not particularly limited, but it is usually preferably 0.01 to 5 μm, more preferably 0.
03-2 μm, most preferably 0.05 μm-0.5 μ
The range is m. In particular, if the thickness is too thin, the adhesion may be poor.

The lamination ratio between the surface layer and the intermediate layer (surface layer / thickness ratio of the intermediate layer) is not particularly limited, but is usually 2/98 to 9
It is preferably 5/5, more preferably 5/95 to
90/10, most preferably 10/90 to 70/30 is excellent in terms of moisture-resistant adhesion.

Further, in the present invention, the main constituent component of the laminated film means that the component is 60% by weight or more in the laminated film. However, in the present invention, it is desirable that the main constituent component is present in an amount of preferably 80% by weight or more, more preferably 90% by weight or more.

The laminated structure as described above can be realized by the following various methods, for example. Ie the example
Example, polyester resins, acrylic resins, and the substrate poly coating solution obtained by mixing the melamine-based crosslinking agent in coating
There is a method of obtaining the laminated film constitution of the present invention by applying the composition on an ester film, drying it under a specific condition, and then stretching the polyester film in at least one axial direction .

[0054]

In particular, the above-mentioned method is a unique method which has not been conceived in the past. According to the knowledge of the present inventors, this method is most industrially desirable, and this method is the above-mentioned laminated film. Is not limited to the method for producing a laminated polyester film having a laminated film in which the surface layer has an acrylic resin and a melamine-based cross-linking agent as main constituent components and the intermediate layer has a polyester resin as a main constituent component, widely, in general, to produce a laminated film This method can also be used in some cases.

That is, the present invention is a general method for producing a film having a laminated structure, in which at least one surface of the polyester film before the crystal orientation is substantially completed,
At least polyester resin, acrylic resin and melamine
After applying a water-based resin coating liquid mixed with a system crosslinking agent , subjected to a drying treatment of the applied water-based resin coating liquid under two or more different set drying conditions, and thereafter, at least the polyester film Also provided is a method for producing a laminated polyester film, which is characterized by stretching in a uniaxial direction.

[0057] To explain this method in detail, the water-based resin used in the present invention, those of different at least two solubility parameter, among a wide range of adhesion to the coating provided on the laminated polyester film in terms of obtaining a gender and especially, Te applications odor moisture adhesion is required, use acrylic resin and a polyester resin
Can be In this case, a combination of melamine-based crosslinking agent, it is possible to further improve the moisture adhesion.

The method for producing the polyester film of the present invention is not particularly limited as long as it can dry the aqueous resin coating liquid under two or more different set drying conditions. For example, the following method is used. You can The glass transition temperature of the base polyester resin (hereinafter referred to as Tg
A temperature lower than Tg), and then the second stage drying is performed at a temperature of Tg or higher to a temperature near Tg necessary for stretching (however, Tg or higher), and then stretching is used. be able to. In particular, by making the second-stage set drying temperature higher than the first-stage set drying temperature in this way, the laminated structure of the present invention can be more remarkably exhibited. Further, the above-mentioned drying can be repeatedly used. Examples of the drying method used include a method using a radiation heater, a method of blowing heated hot air, and a combination of both.

At this time, it is preferable to increase the ambient temperature at 10 ° C./sec or more during the second stage drying temperature between the first stage and the second stage drying, and more preferable. Is 40 ° C / sec or more, most preferably 200 ° C
/ Sec or more.

In summary, the laminated film provided on the surface of the polyester film of the present invention uses two kinds of resins having different solubility parameters, and two kinds of resins are prepared by controlling the set drying conditions when the laminated film is formed. It has been found that the resin of (1) has a phase separation structure, a resin having a small solubility parameter on the gas phase side and a resin having a large solubility parameter on the polyester film side, that is, a so-called phase separation structure. Further, they have found that a mixed phase region of phases forming each layer exists at the interface between the surface layer and the intermediate layer of the laminated film. In particular, when the above-mentioned mixed phase region is present, the laminated film of the laminated polyester film has excellent adhesiveness with the coating material and at the same time excellent adhesiveness with the base film, and further has an adhesive property at the interface between both phases. It is more preferable because the property is improved.

The structure in which such a mixed phase region exists will be described with reference to the drawings. FIG. 1 is a schematic outline explanatory view tracing an enlarged cross-sectional micrograph near the surface layer of the laminated polyester film of the present invention. 2 is a schematic explanatory diagram in which each part is made easier to understand by further tracing the trace FIG.

As shown in FIGS. 1 and 2, the laminated polyester film 1 of the present invention comprises a polyester film 2 and a laminated film 3 formed thereon.
In order from the polyester film 2 side, the intermediate layer 4, the mixed phase region 5, and the surface layer 6 are configured.

According to the knowledge of the present inventors, the presence of such a mixed phase region clearly in the laminated polyester of the present invention improves the adhesiveness at the interface between the surface layer and the intermediate layer of the laminated film. Furthermore, it has an effect in improving the properties as a laminated polyester film having excellent adhesiveness. It is important that the mixed phase region has a small effect even if it exists, and has a certain thickness, and it is preferably 0.005 to 2 μm according to the knowledge of the present inventors. It is preferable that the layered structure has a certain thickness, more preferably about 0.02 to 0.4 μm and exists as a clear mixed phase region.

In the present invention, before applying the coating liquid,
The surface of the base film is subjected to corona discharge treatment or the like, and the wetting tension of the surface is preferably 47 mN / m or more, more preferably 50 mN / m or more to improve the adhesion of the laminated film to the base film. Not only this, but also the above-mentioned phase separation can be made more remarkable.

Next, the method for producing the laminated polyester film of the present invention will be described by taking a polyethylene terephthalate (hereinafter abbreviated as "PET") film as an example of the substrate film, but the invention is not limited to this. Absent.

[0066]

Alternatively, the laminated polyester film of the present invention can be produced by the phase-separated laminated film described below.

For example, an intrinsic viscosity of 0.5 to 0.8 dl / g
After vacuum-drying the PET pellets, the PET pellets are supplied to an extruder, melted at 260 to 300 ° C., extruded in a sheet form from a T-shaped die, and subjected to an electrostatic application casting method to obtain a surface temperature of 10
The film was wrapped around a mirror-casting drum at -60 ° C and cooled and solidified to prepare an unstretched PET film. This unstretched film is stretched 2.5-5 times in the machine direction (the direction of film travel) between rolls heated to 70-100 ° C. At least one surface of this film was subjected to corona discharge treatment in air to have a wetting tension of 47 mN / m or more on the surface, and the treated surface was coated with a coating liquid for forming a laminated film by the phase separation structure of the present invention. The coated film is grasped with a clip and guided to a drying zone, dried at a temperature lower than Tg of the base polyester resin, then raised to Tg or higher, dried again at a temperature near Tg, and continuously 70 to 70%. 15
The film was stretched 2.5 to 5 times in the width direction in a heating zone of 0 ° C., and then heat-treated in a heating zone of 160 to 240 ° C. for 1 to 10 seconds to prepare a laminated PET film with crystal orientation completed. If necessary, a relaxation treatment of 3 to 12% may be performed during this heat treatment. Biaxial stretching may be longitudinal, transverse sequential stretching or simultaneous biaxial stretching, and after longitudinal and transverse stretching,
You may re-stretch in either the lengthwise direction or the widthwise direction. The thickness of the polyester film is not particularly limited, but 1 to 300 μm is preferably used. The coating liquid used in this case is preferably an aqueous system from the viewpoint of environmental pollution and explosion proof.

In the above example, the base film on which the laminated film is provided can also contain at least one selected from melamine resins, acrylic resins, polyester resins, and reaction products of these. In this case, the adhesiveness between the laminated film and the base film is improved, and the slipperiness of the laminated polyester film is improved. When containing a melamine resin, an acrylic resin, a polyester resin, and a reaction product of these,
The amount added is 5 ppm or more and less than 20% by weight.
It is preferable in terms of easy adhesion and slipperiness. Of course, the melamine-based resin, the acrylic resin, the polyester resin, and the reaction products thereof may be a coating composition (including recycled pellets of the laminated film of the present invention) provided on the base film.

The laminated film thus obtained is
Various coatings such as magnetic paints, UV curable inks,
Excellent adhesion to oxidative polymerization type inks, flexo inks, diazo sensitive materials, cellulosic inks, toner compositions, etc. Therefore, this laminated film is useful for various applications, and can be used for magnetic tapes, floppy disks, magnetic recording cards, OHP applications, heat-sensitive recording materials, packaging materials, graphic applications, various printing materials, optical applications and the like.

[0071]

[Characteristic Measuring Method and Effect Evaluation Method] The characteristic measuring method and effect evaluating method in the present invention are as follows.

(1) Cross-sectional morphology of laminated film, phase separation structure, and thickness of laminated film The cross-section of the laminated film was cut into an ultrathin section, and RuO ₄
Staining, OsO ₄ staining, or double staining of both of them was carried out and observed and photographed with a TEM (transmission electron microscope) by an ultrathin section method. From the cross-sectional photograph, the phase separation state of the laminated film, the presence or absence thereof, the thickness of each phase, the thickness of the laminated film, etc. were confirmed and measured. In addition, the resin type was determined by the difference in dyeing density on the photograph. Further, a portion where both phases of the interface portion are intricate and cannot be determined as any of the phases is defined as the mixed phase.

The thickness of each phase was calculated from the thickness of the laminated film and the area ratio of the portion dyed with each resin.

Observation method / apparatus: Transmission electron microscope (H-7 manufactured by Hitachi, Ltd.)
100FA type) ・ Measurement conditions: Accelerating voltage 100kV ・ Sample preparation: Frozen ultra-thin section method (2) Adhesiveness-1 (Adhesiveness of UV curable ink: normal state) FLASH DRY (FDO) as UV curable ink
L ink (manufactured by Toyo Ink Mfg. Co., Ltd.) was applied to a thickness of about 1.5 μm by a roll coating method. After that, light intensity 20
Ultraviolet irradiation was carried out at mW / cm ² for 50 seconds to give an integrated irradiation amount of 1000 mJ and curing. 1m on this ink
100 m ² cross cuts were put, cellophane tape manufactured by Nichiban Co., Ltd. was stuck on it, and it was strongly pressed with a finger, then rapidly peeled in the direction of 90 degrees, and a four-level evaluation was performed according to the remaining number. . (⊚) and (∘) were evaluated as good adhesiveness.

⊚: 100/100 (remaining number / measured number) ◯: 80/100 or more and less than 100/100 Δ: 50/100 or more, less than 80/100 x: less than 50/100 (3) Adhesion-2 (Ultraviolet curable ink adhesion: bending) An ultraviolet curable ink layer was provided in the same manner as in (2) above.

A polyester adhesive tape manufactured by Nitto Denko Co., Ltd. was attached to the paint-dried film, which was strongly pressed with a finger, folded back 180 degrees with the tape inside, and the crease was strongly pressed with a finger, and then returned to its original state. After returning, the film was rapidly peeled in the direction of 90 degrees, and the state of the peeling was evaluated in four grades.
(⊚) and (∘) were evaluated as good adhesiveness.

◎: Not removable ○: Slightly removable Δ: Fairly removable ×: Completely removable (4) Adhesiveness-3 (Adhesiveness of sublimation type ink: normal state) Thickness after drying the following sublimation type ink Is 5 μm using a bar coater. After coating, dry at 120 ° C for 2 minutes, leave at 25 ° C and 60% relative humidity for 24 hours, and then apply "Scotch Mending Tape" (Sumitomo 3M Co., Ltd.) on the sublimation type ink layer and hand. After strongly pressure bonding with, peel in the direction of 180 degrees. The following 5 grades were evaluated according to the state of the sublimation type ink layer remaining on the substrate film side at this time. (⊚) and (∘) indicate good adhesion. (◎): 100% ink remaining on the release surface (○): 〃 80% or more remaining (△): 〃 50% or more remaining (x): 〃 less than 50% What remains (XX): What peels off without any resistance "Sublimation ink composition":-Disperse dye KST-B-136 (manufactured by Nippon Kayaku Co., Ltd.) /
Ink mixed with ethyl hydroxyethyl cellulose / methyl ethyl ketone / toluene = 4/6/45/45 (weight ratio).

(5) Adhesiveness-4 (Sublimation type ink adhesiveness:
Moisture resistance-A) A sublimation type ink layer is provided in the same manner as in (4) above, and 35
After leaving it at 100 ° C. and a relative humidity of 75% for 100 hours and taking it out, after 5 minutes under normal conditions, the adhesiveness was evaluated by the same method as the above (4).

(6) Adhesiveness-5 (sublimation type ink adhesiveness:
Moisture resistance-B) A sublimation type ink layer is provided in the same manner as in (4) above, and 40
After leaving at 100 ° C. and 90% relative humidity for 100 hours and taking out, after 5 minutes under normal conditions, the adhesiveness was evaluated by the same method as the above (4).

(7) Adhesiveness-6 (adhesiveness of diazo photosensitive paint) CAB381-05 as a binder for diazo photosensitive paint
(Manufactured by Nagase Sangyo Co., Ltd.) was dissolved in ethyl acetate and coated on the film surface so that the thickness after drying was 6 μm to form a coating layer. After coating, it is dried at 100 ° C for 2 minutes, and then dried. Dry diazo copying machine RICOPY SM2300F (Co., Ltd.)
Ricoh) and developed, and the unexposed areas were evaluated in the same manner as in (2) above.

(8) Printing Characteristics The printing characteristics of the sublimation type thermal transfer material prepared by further providing the stick preventing layer shown in the above (4) were compared with those of Sharp Color Video Printer GZ-P11W type (Sharp Corp.).
The product was visually inspected for the printing condition and evaluated according to the following criteria.

⊚: Very good printing characteristics ○: Good printing characteristics Δ: Slightly bad ×: Remarkably poor “stick preventing layer forming coating”: Amino-modified silicone / epoxy-modified silicone / ethanol / isopropyl alcohol = 3/2 / 45/5
Coating mixture mixed at 0 (weight ratio).

(9) Flatness With respect to the ultraviolet-curable ink laminate coated and cured in (2) above, the flatness of the laminate was placed on the glass plate with the ink side facing up, and the degree of curl was visually observed. It was measured and judged according to the following criteria.

[0084] ⊚: No curl at all, extremely good flatness ○: Slightly curled at the edges but good Δ: The curl extends to the vicinity of the central portion.

[0085] ×: remarkable curl

[0086]

EXAMPLES Next, the present invention will be explained based on examples, but the present invention is not necessarily limited to these.

Reference Example 1 0.15% by weight of deposited particles having a particle diameter of 0.5 to 1.5 μm (particles deposited in the polymerization step), and calcium carbonate particles having an average particle diameter of about 1.5 μm were added. PET pellets containing 2% by weight (intrinsic viscosity 0.63 dl / g) were prepared. Further, as the polyester resin for forming the A layer, P was obtained by polycondensing the acid component with terephthalic acid / isophthalic acid at 80/20 (molar ratio) and the diol component with ethylene glycol / diethylene glycol at 95/5 (molar ratio).
ET / I pellets (intrinsic viscosity 0.62 dl / g) were prepared. After fully vacuum drying these polymers, PET
Is fed to the extruder 1 and melted at 285 ° C.
/ I is supplied to the extruder 2 and melted at 270 ° C., and these polymers are combined and laminated by a confluent block having a rectangular laminated portion, and wound on a mirror-casting drum having a surface temperature of 30 ° C. by using an electrostatically applied casting method. By cooling and solidifying, an unstretched film having a PET / I layer on one side or both sides was prepared. This unstretched film was heated to 95 ° C. and stretched 3.5 times in the longitudinal direction to obtain a uniaxially stretched film. The laminated surface of this film was subjected to corona discharge treatment in air, the wetting tension of the base film was adjusted to 52 mN / m, and the coating liquid described below was applied to the treated surface. After the crystal orientation was completed, the layer thickness was 0.05 μm in the surface layer and 0.15 μm in the lower layer,
The total thickness was 0.2 μm.

"Coating liquid" -Aqueous coating liquid prepared by mixing acrylic resin / melamine-based crosslinking agent = 100/10 (solid content weight ratio). However, as an acrylic resin, a water-based acrylic resin coating liquid obtained by copolymerizing methyl methacrylate / ethyl acrylate / acrylic acid / N-methylol acrylamide at a ratio of 77/20/1/2 (weight ratio), and a methylol compound as a melamine-based cross-linking agent A melamine coating solution was used.

The applied uniaxially stretched film was held by a clip, introduced into a preheating zone heated to 110 ° C. to dry the water, and continuously stretched 4.5 times in the width direction in a heating zone of 130 ° C. Then, heat treatment was performed for 2 seconds in a heating zone of 225 ° C. to prepare a laminated PET film with crystal orientation completed. At this time, the thickness of the base film is 6 μm
Met. The results are shown in Table 1.

[0090]

[Table 1] Comparative Example 1 Reference In Example 1, a laminated PET film (lamination thickness 0.2 μm) not coated with the coating liquid was prepared. The results are shown in Table 1.
Shown in.

Comparative Example 2 Reference A laminated PET film obtained by coating and laminating a coating liquid without laminating PET / I layers in Example 1 (lamination thickness: 0.
2 μm) was prepared. The results are shown in Table 1.

Comparative Example 3 Reference In Example 1, a PET film having no laminated film was prepared. The results are shown in Table 1.

Example 1 0.15% by weight of precipitated particles having a particle diameter of 0.5 to 1.5 μm (particles deposited in the polymerization step) and 0.2 of calcium carbonate particles having an average particle diameter of about 1.5 μm. PET pellets (intrinsic viscosity 0.63 dl / g) containing 10% by weight are sufficiently vacuum dried, then supplied to an extruder and melted at 285 ° C., extruded into a sheet from a T-shaped die, and electrostatically cast It was wound around a mirror-casting drum having a surface temperature of 30 ° C. and cooled and solidified. This unstretched film was heated to 95 ° C. and stretched 3.5 times in the longitudinal direction to obtain a uniaxially stretched film. This film was subjected to corona discharge treatment in air, and the wetting tension of the base film was 52 mN / m.
The following coating liquid was applied to the treated surface. The layer thickness was set to 0.2 μm after the crystal orientation was completed.

"Coating liquid" -Aqueous coating liquid prepared by mixing acrylic resin / polyester resin / melamine-based crosslinking agent = 30/70/10 (weight ratio of solid content). However, as the acrylic resin, an aqueous acrylic resin coating liquid obtained by copolymerizing methyl methacrylate / ethyl acrylate / acrylic acid / N-methylol acrylamide at 75/20/3/2 (weight ratio), and as the polyester resin terephthalic acid / isophthalic acid Acid / 5-sodium sulfoisophthalic acid / ethylene glycol / 1,4-butanediol polycondensed at 30/15/5/30/20 (mol%), water-based polyester resin coating liquid, methylol as melamine crosslinking agent A melamine coating solution was used.

The coated uniaxially stretched film is held by a clip, introduced into a preheating zone, and dried at an ambient temperature of 75 ° C.,
Once the temperature was raised to 125 ° C. and dried again at 95 ° C., it was continuously stretched 4.5 times in the width direction in a heating zone of 130 ° C., then heat-treated in a heating zone of 225 ° C. for 2 seconds to crystallize. A laminated PET film with completed orientation was prepared. At this time, the thickness of the base film was 6 μm.
The results are shown in Table 2.

[0096]

[Table 2] Example 2 The polyester resin of the coating solution of Example 1 was mixed with isophthalic acid /
Example except that the water-based polyester resin coating solution was polycondensed with trimellitic acid / neopentyl glycol / diethylene glycol = 45/5/25/25 (mol%).
A laminated PET film was prepared in the same manner as in 1 . The results are shown in Table 2.

Example 3 The polyester resin of the coating liquid of Example 1 was prepared by using terephthalic acid / isophthalic acid / 5- (2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2-
Dicarboxylic acid / ethylene glycol / diethylene glycol / neopentyl glycol = 5/40/5/20 /
A laminated PET film was prepared in the same manner as in Example 1 except that an aqueous ammonium salt type polyester dispersion composed of 20/10 (mol%) was used. The results are shown in Table 2.

[0098] except for using a coating solution containing no added polyester resin in the coating solution of Comparative Example 4 Example 1 to prepare a laminated PET film in the same manner as in Example 1. The results are shown in Table 2.

[0099] except for using a coating solution containing no added an acrylic resin in the coating solution of Comparative Example 5 Example 1 to prepare a laminated PET film in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 6 A laminated PET film was prepared in the same manner as in Example 1 except that the coating liquid of Example 1 containing no melamine crosslinking agent was used. The results are shown in Table 2.

Reference Examples 2 to 4 Reference A laminated PET film was prepared in the same manner as in Reference Example 1 except that the thicknesses of the surface layer and the intermediate layer were changed as shown in Table 1. The results are shown in Table 1.

Examples 4 to 9 Example 3 A laminated PET was prepared in the same manner as in Example 3 except that the mixing ratio of the acrylic resin / polyester resin / melamine type crosslinking agent was changed as shown in Table 2 in the coating liquid. I made a film. The results are shown in Table 2.

[0103] Example 10 Example 3 Polyethylene-2,6-naphthalate base film with a film (hereinafter, abbreviated as "PEN") to obtain a laminated PEN film in the same manner as in Example 3 except that the . The results are shown in Table 2.

Example 11 In Example 3 , PET pellets containing 0.015% by weight of colloidal silica having an average particle size of 0.4 μm and 0.005% by weight of colloidal silica having an average particle size of 1.5 μm (with an intrinsic viscosity of 0 A laminated PET film was obtained in the same manner as in Example 4 except that 0.62 dl / g) was used. At this time, the thickness of the base film was 75 μm. As a result of TEM cross-section observation of the laminated film of this laminated film, the laminated film was phase-separated in the thickness direction, and a mixed phase of these resins was present. A diazo photosensitive coating was applied to this laminated film and the adhesiveness was evaluated. It showed good adhesiveness of diazo photosensitive paint.

Example 12 PET pellets in which 16% by weight of titanium oxide was finely dispersed (intrinsic viscosity 0.62 dl / g) were thoroughly vacuum-dried,
It was supplied to an extruder, melted at 280 ° C., extruded in a sheet form from a T-shaped die, and wound around a mirror-casting drum having a surface temperature of 30 ° C. by an electrostatic applied casting method to be cooled and solidified. This unstretched film was heated to 90 ° C. and stretched 3.5 times in the longitudinal direction to obtain a uniaxially stretched film. This film was subjected to corona discharge treatment in the air so that the wetting tension of the base film was 52 mN / m, and the treated surface was coated with the same coating liquid as in Example 3 . The layer thickness was set to 0.2 μm after the crystal orientation was completed.

The coated uniaxially stretched film is held by a clip, guided to a preheating zone, and dried at an ambient temperature of 75 ° C.,
Once the temperature was raised to 140 ° C. and dried again at 95 ° C., it was continuously stretched 4.5 times in the width direction in a heating zone of 130 ° C., then heat-treated in a heating zone of 225 ° C. for 2 seconds to crystallize. A laminated PET film with completed orientation was prepared. At this time, the thickness of the substrate film was 190 μm, the optical density was 1.5, and the whiteness was 85%. An ultraviolet curable ink was applied on this laminated film to evaluate the adhesiveness.
Adhesiveness-1 (ultraviolet curable ink adhesiveness: normal state) and adhesiveness-2 (ultraviolet curable ink adhesiveness: bending) both showed good adhesiveness, and the flatness was also good (○) level. .

[0107] except that the base film in Example 13 Example 12 was polyethylene-2,6-naphthalate film to obtain a laminated PEN film in the same manner as in Example 12. Adhesiveness-1 and 2 both showed good adhesiveness, and the flatness was also very good at (⊚) level.

[0108]

INDUSTRIAL APPLICABILITY According to the present invention, adhesiveness with various inks is excellent, and for example, printing materials such as labels, magnetic recording materials such as prepaid cards, photosensitive materials, graphic materials,
Provided are a laminated film useful as an industrial material such as a sublimation type thermal transfer material, a packaging material and the like, and a method for producing the same.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view in which a cross-sectional enlarged micrograph of the vicinity of the surface layer portion of the laminated polyester film of the present invention is traced.

FIG. 2 is a schematic explanatory diagram in which each part is made easier to understand by further tracing the trace diagram of FIG.

[Explanation of symbols]

1: Laminated polyester film of the present invention 2: Polyester film 3: Laminated film 4: Middle layer 5: Mixed phase area 6: Surface

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B29L 7:00 B29L 7:00 9:00 9:00 (56) References JP-A-6-115030 (JP, A) JP JP-A-8-2122 (JP, A) JP-A-8-1886 (JP, A) JP-A-4-299136 (JP, A) JP-A-6-107830 (JP, A) JP-A-1-156337 (JP , A) JP-A 1-125227 (JP, A) JP-A 3-26543 (JP, A) JP-A 60-63161 (JP, A) JP-A 58-124651 (JP, A) JP-A 60-61259 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04

Claims (5)

(57) [Claims] 1. A laminated polyester film in which a laminated film formed by coating of substantially one layer is provided on at least one side of a polyester film, and the surface layer of the laminated film is mainly composed of an acrylic resin and a melamine-based crosslinking agent. An intermediate layer containing a polyester resin as a main component is formed between the surface layer of the laminated film and the polyester film to form the laminated film .
At the interface between the surface layer and the intermediate layer of the laminated film, each layer is formed.
A laminated polyester film having a mixed phase region of phases . 2. The polyester film is a polyethylene terephthalate film or polyethylene-2,6-
Claim, characterized in that a naphthalate film 1
Laminated polyester film according to. 3. The polyester film comprises a composition containing at least one selected from an acrylic resin, a polyester resin, a melamine resin, and a reaction product of these, and the composition according to claim 1 or 2. Laminated polyester film. 4. At least one surface of the polyester film before substantially completing the crystal orientation is covered with at least a polyester film.
After applying a water-based resin coating liquid in which a stell resin, an acrylic resin, and a melamine-based cross-linking agent are mixed, and subjecting the applied water-based resin coating liquid to a drying treatment under two or more different set drying conditions, Then, the polyester film is stretched in at least one axial direction, which is a method for producing a laminated polyester film. 5. The laminated polyester film according to claim 4 , wherein the second stage set drying temperature is set to a temperature higher than the first stage set drying temperature to carry out two or more stages of drying treatment. Law.