JPH11300918A - Easily adhesive polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the increase of haze level and improve adhesive properties by laminating a layer composed of a polypropylene terephthalate as a main constituent on at least one of the sides of a base material film composed mainly of the polyethylene terephthalate, and forming an easily adhesive layer through the former layer. SOLUTION: A layer formed of a polypropylene terephthalate as a main constituent is laminated on at least one of the sides of a base material film composed mainly of the polyethylene terephthalate, and an easily adhesive layer is formed through the former layer. The polypropylene terephthalate is a polyester having a terephthalic acid as a main acidic component and a 1,3-propane diol as a main glycol component. In addition, the resin to be used for the easily adhesive layer is a polyester resin, an acrylic resin or a polyurethane resin from the viewpoint of adhesive properties with the layer composed mainly of the polypropylene terephthalate. Consequently, it is possible to prevent the deposition of an oligomer from occurring and suppress the increase of haze level and improve the adhesive properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily adhesive polyester film, and more particularly, to a polyester film capable of simultaneously suppressing both increase in haze value by preventing oligomer precipitation and adhesiveness.

[0002]

2. Description of the Related Art As a conventional easily-adhesive polyester film, a film in which various resins such as a polyester resin and an acrylic resin are provided as a primer layer on at least one surface of a polyester film serving as a base material is known. JP-A-58-29626 and JP-A-60-1
49442).

[0003]

However, the above-mentioned easily-adhesive polyester film has problems such as oligomer precipitation due to aging or heat treatment, resulting in an increase in haze value and a decrease in adhesiveness. It is an object of the present invention to improve the disadvantages of the prior art and to provide an easily-adhesive polyester film capable of simultaneously satisfying both suppression of haze value increase and adhesiveness.

[0004]

The easily adhesive polyester film of the present invention which achieves the above object has a layer comprising polypropylene terephthalate as a main component on at least one surface of a base film mainly comprising polyethylene terephthalate. They are laminated, and an easy-adhesion layer is provided via the layer.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polyethylene terephthalate used in the present invention is a polyester containing terephthalic acid as a main acid component and ethylene glycol as a main glycol component, and constitutes the main component in a base film. is there. Here, the main component means that the constituent ratio of the polymer is 50% by weight or more, preferably 80% by weight.
% Or more, more preferably 90% or more.

In the base film, various polyester copolymers can be used as components other than polyethylene terephthalate. For example, isophthalic acid, phthalic acid, diphenyl-4,4 ′ may be contained in an amount of 20 mol% or less, preferably 15 mol% or less of the acid component and / or the glycol component constituting polyethylene terephthalate.
-Dicarboxylic acid, naphthalene-2,6-dicarboxylic acid,
Naphthalene-2,7-dicarboxylic acid, naphthalene-1,
5-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid,
Acid components such as malonic acid, 1,1-dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, decamethylene dicarboxylic acid, 1,3-propanediol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol , Cyclohexane dimethanol,
Copolymerized polyesters obtained by copolymerizing glycol components such as hydroquinone and bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-propylene glycol copolymer and the like can be used. Further, two or more polymers may be mixed.

The layer containing polyethylene terephthalate as a main component may contain various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a lubricant,
Pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, nucleating agents and the like may be added to such an extent that their properties are not deteriorated.

The thickness of the layer containing polyethylene terephthalate as a main component is not particularly limited and may be appropriately selected depending on the application. However, from the viewpoint of mechanical strength and handling properties, it is usually 1 to 500 μm, preferably 5 to 500 μm. ~ 300μ
m.

The polypropylene terephthalate used in the present invention contains terephthalic acid as a main acid component,
Polyester containing 1,3-propanediol as a main glycol component, and a main component of a layer mainly containing polypropylene terephthalate. Here, the main component means that the composition ratio of the polymer is 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more. Here, if the ratio of the polypropylene terephthalate is too low, the precipitation of the oligomer may not be effectively prevented in some cases.

In the layer mainly composed of polypropylene terephthalate, various polyester copolymers can be used as components other than polypropylene terephthalate. For example, two of the acid component and / or the glycol component constituting polypropylene terephthalate
In a range of 0 mol% or less, preferably 15 mol% or less, isophthalic acid, phthalic acid, diphenyl-4,4'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene -1,5-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, malonic acid, 1,1-dimethylmalon Acid components such as acid, succinic acid, glutaric acid, adipic acid, sebacic acid, decamethylene dicarboxylic acid, and glycol components such as ethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexane dimethanol, hydroquinone, and bisphenol A And polyethylene glycol, polypro Copolymerized polyester obtained by copolymerizing pyrene glycol, polytetramethylene glycol, polyethylene glycol-propylene glycol copolymer, or the like can be used. Further, two or more polymers may be mixed.

The layer mainly composed of polypropylene terephthalate contains various additives such as antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, lubricants, pigments, dyes, organic or inorganic fine particles. , A filler, an antistatic agent, a nucleating agent, and the like may be added to such an extent that the characteristics are not deteriorated.

The thickness of the layer mainly composed of polypropylene terephthalate (each layer when the number of layers is two) is not particularly limited, but is preferably 0.05-3.
μm, more preferably 0.1 to 2 μm, and most preferably 0.2 to 1 μm. If the thickness of the layer is too small, it may not be possible to effectively prevent oligomer precipitation.

The resin which can be used in the easy-adhesion layer according to the present invention is not particularly limited. Among them, polyester resin, acrylic resin, and polyurethane resin are preferred from the viewpoint of adhesion to a layer mainly composed of polypropylene terephthalate. Can be used.

The polyester resin which can be preferably used as a component of the easy-adhesion layer according to the present invention has an ester bond in a main chain or a side chain. Such a polyester resin is composed of an acid component and a glycol component. It can be obtained by polycondensation.

As the acid component constituting the polyester resin, terephthalic acid, isophthalic acid, phthalic acid, 2,5-
Dimethyl terephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bisphenoxyethane-p, p'-
Dicarboxylic acid, phenylindanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecandioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,4
-Cyclohexanedicarboxylic acid and the like, and their ester-forming derivatives can be used.

When a polyester resin is used as a coating liquid, a compound containing a sulfonate group or a compound containing a sulfonate group is used in order to improve the adhesion of the polyester resin to various paints and inks, or to facilitate the water solubility of the polyester resin. The compound containing a carboxylate group is not particularly limited, but is preferably copolymerized at 1 to 30 mol%.

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)
Alkali metal salts such as benzene, alkaline earth metal salts,
An ammonium salt or the like can be used, but is not limited thereto.

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, ,
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
Alkali metal salts such as 4,5-tetracarboxylic acid and ethylenetetracarboxylic acid, alkaline earth metal salts, and ammonium salts can be used, but are not limited thereto.

The glycol components constituting the polyester resin include 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-octane Diol, 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-cyclohexane Dimethanol, 1,4-cyclohexanedimethanol, 2,2
4,4-tetramethyl-1,3-cyclobutanediol, 4,4′-thiodiphenol, bisphenol A,
4,4'-methylenediphenol, 4,4 '-(2-norbornylidene) diphenol, o-, m-, and p
-Dihydroxybenzene, p, p'-isopropylidenediphenol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-
1,4-diol and the like can be used.

As the polyester resin, a modified polyester copolymer, for example, a block copolymer or a graft copolymer modified with acryl, urethane, epoxy or the like can be used.

The acrylic resin that can be preferably used as a component of the easy-adhesion layer according to the present invention is, for example, an alkyl acrylate or an alkyl methacrylate (where the alkyl group is a methyl group or an ethyl group). , N-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, lauryl, stearyl, cyclohexyl, phenyl, benzyl, phenylethyl, etc.), 2- Hydroxyl group-containing monomers such as hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylacrylamide, N-methylmeth Riruamido, N- methylolacrylamide, N- methylolmethacrylamide, N,
Amide group-containing monomers such as N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide, N, N-diethylaminoethyl acrylate,
Amino group-containing monomers such as N, N-diethylaminoethyl methacrylate, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, acrylic acid, methacrylic acid and salts thereof (alkali metal salts, alkaline earth metal salts, ammonium salts, etc.) For example, monomers containing a carboxyl group or a salt thereof, and the like can be used, and these are copolymerized using one kind or two or more kinds. Further, 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 and sulfones such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt and the like). Monomers containing acid groups or salts thereof, monomers containing carboxyl groups or salts thereof such as crotonic acid, itaconic acid, maleic acid, fumaric acid and salts thereof (lithium salts, sodium salts, potassium salts, ammonium salts, etc.) , Maleic anhydride, monomers containing acid anhydrides such as itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene,
Use of vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleate monoester, alkyl fumarate monoester, acrylonitrile, methacrylonitrile, alkyl itaconate monoester, vinylidene chloride, vinyl acetate, vinyl chloride, etc. it can.

As the acrylic resin, a modified acrylic copolymer, for example, a block copolymer or a graft copolymer modified with polyester, urethane, epoxy or the like can be used.

The polyurethane resin which can be preferably used as a component of the easy-adhesion layer according to the present invention is not particularly limited as long as it has a urethane bond in its molecular structure. The reaction product obtained is used as its basic skeleton, and a chain extender or the like can be used if necessary.

The polyol compound to be used includes polyester diol, polyether diol, polyacetal diol, etc. Among them, polyester polyol and polyether polyol are preferable.

As the polyester polyol, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, neopentyl glycol, polyethylene glycol, polypropylene glycol, cyclohexane dimethanol, or a mixture thereof and an organic dicarboxylic acid such as a saturated fatty acid (adipic acid) , Sebacic acid, azelaic acid, etc.), unsaturated fatty acids (maleic acid, fumaric acid, etc.), aromatic acids (terephthalic acid, isophthalic acid, phthalic acid, etc.), alicyclic dicarboxylic acids and their mixtures, anhydrides, etc. A linear polyester having hydroxyl groups at both ends obtained by the reaction, and further a polyester obtained by ring-opening polymerization of lactones such as caprolactam and methylcaprolactone with glycols are also used. Door can be.

As the polyether polyol, for example, a polymer or copolymer having a hydroxyl group at a terminal obtained by ring-opening polymerization or copolymerization of ethylene oxide, propylene oxide, epichlorohydrin, oxacyclobutane, substituted oxacyclobutane or tetrahydrofuran; These mixtures and the like can be used.

As the isocyanate compound to be reacted with the polyol compound, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,8-octamethylene diisocyanate, 1,1
0-decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, toluene diisocyanate, 1,3-phenylene diisocyanate, 4,4′-
Methylene bis (cyclohexyl isocyanate), 4,
4'-diphenylmethane diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, or the like, or a mixture thereof can be used.

As the chain extender, ethylene glycol,
Diethylene glycol, propylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, and the like can be used.

In addition, other resins such as, for example, other resins such as an easy-adhesion layer according to the present invention may be used as long as the effects of the present invention are not impaired.
Epoxy resin, silicone resin, urea resin, phenol resin and the like may be blended.

Further, various additives such as antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, etc. may be added to the easy-adhesion layer according to the present invention as long as the effects of the present invention are not impaired. Lubricants, pigments, dyes, organic or inorganic fine particles,
A filler, an antistatic agent, a nucleating agent and the like may be blended.

It is optional to add particles or a crosslinking agent to the easy-adhesion layer according to the present invention. However, the addition of these particles improves the lubricity, blocking resistance, and adhesion to various paints and inks. Therefore, it is preferable.

The particles arbitrarily added to the easy-adhesion layer according to the present invention are not particularly limited, but silica, colloidal silica, alumina, alumina sol, kaolin, talc, mica, calcium carbonate and the like can be used. The average particle size is not particularly limited, but 0.01 to
5 μm is preferable, more preferably 0.05 to 3 μm,
Most preferably, it is 0.08 to 2 μm. Further, the mixing ratio to the total resin in the easy-adhesion layer is not particularly limited,
The solid content ratio is preferably 0.05 to 8 parts by weight, more preferably 0.1 to 3 parts by weight.

The crosslinking agent arbitrarily added to the easy-adhesion layer according to the present invention is not particularly limited, but urea-based, melamine-based, acrylamide-based, polyamide-based resin, epoxy compound, isocyanate, etc. Compounds, oxazoline compounds, aziridine compounds, various silane coupling agents, various titanate coupling agents, and the like can be used. The amount of addition is not particularly limited, but is preferably 0.5 to 20 parts by weight, more preferably 1 to 15 parts by weight, and most preferably 2 to 10 parts by weight, based on all resins forming the easy-adhesion layer. .

As the resin forming the above-mentioned easy-adhesion layer, a resin dissolved and dispersed in an organic solvent or water can be used.
In particular, in order to obtain the present easily adhesive polyester film, in consideration of economy, uniformity, adhesion to a substrate, and the like, it is preferable to use in-line coating applied in the polyester film manufacturing process. It is preferable to use a resin dissolved or dispersed in the resin.

The thickness of the easily adhesive layer according to the present invention is as follows:
Although not particularly limited, preferably 0.02 to 5 μm, more preferably 0.03 to 2 μm, and most preferably 0.02 to 2 μm.
5 to 0.5 μm. If the thickness of the layer is too small, the adhesion to various paints and inks may be poor.

Next, an example of the method for producing the easily adhesive polyester film of the present invention will be described, but the present invention is not particularly limited thereto.

As a preferable method, in a co-extrusion apparatus using two extruders, one extruder A is supplied with dried polyethylene terephthalate, and the other extruder B is supplied with dried polypropylene terephthalate, and is melt-extruded by a conventional method. Then, the unstretched sheet of A / B or B / A / B is prepared by cooling and solidifying on a mirror drum. The unstretched sheet is stretched in the longitudinal direction at a temperature of about 80 to 130 ° C. for 2.5
４4 times stretched, continuously guided into the tenter while holding the ends with clips, and after passing through a preheating zone of 80 to 130 ° C, stretched in the width direction 2.5 to 4 times at a temperature of 90 to 135 ° C I do. Further, it can be obtained by a method of being continuously guided to a heating zone of 150 to 250 ° C. and completing the crystal orientation. In this process, a corona discharge treatment is applied to the polypropylene terephthalate side of the laminated film after stretching in the longitudinal direction, and a coating liquid for forming an easily adhesive layer is applied to the surface. The coating liquid used in this case is preferably a water-based coating liquid in view of environmental pollution and explosion-proof properties.

The application of the easily adhesive polyester film obtained by the present invention is not particularly limited. For example, a receiving sheet substrate for cards, labels, photographs, OHP, thermal transfer, ink jet, offset printing, etc., packaging For magnetic recording media.

[0040]

[Measurement method of properties and evaluation method of effect] (1) Haze value The haze value was measured using a fully automatic direct reading haze computer HGM-2DP (for C light source) (manufactured by Suga Test Instruments Co., Ltd.), and 10 points were measured. It was indicated by the average value of the measurement.

Haze value: H (%) = (Td / Tt) × 1
00 Td (%) = [{T4−T3 × (T2 / T1)} / T1] ×
100 (diffuse transmittance) Tt (%) = (T3 / T1) × 100 (total light transmittance) (T1: incident light, T2: all light transmitted light, T3: diffused light of the device, T4: diffused transmitted light) (2) Adhesiveness FLASH DRY FD-
Using OL black (manufactured by Toyo Ink Mfg. Co., Ltd.), it was applied to a thickness of 2 μm by a roll coating method. Thereafter, an ultraviolet lamp (80 W / cm, 5 seconds) was irradiated to cure the ultraviolet curable ink.

For evaluation of adhesiveness, 100 crosscuts of 1 mm ² were put on the cured ink film, a cellophane tape was stuck thereon, and pressed with a rubber roller (load 1).
After three reciprocations at 9.6 N), the film was peeled in the 90-degree direction, and was evaluated on a 4-point scale based on the number of remaining ink cured films (A: 100,
：: 80 to 99, Δ: 50 to 79, ×: 0 to 49).

(3) Haze value after forced heating The film to be evaluated was fixed to a metal frame with a binder clip, and left at 80 ° C. for 3 days using a hot air oven.
The haze value of this film was measured by the above method (1).

[0044]

Next, embodiments of the present invention will be described with reference to examples, but the present invention is not necessarily limited thereto.

Example 1 Polymer A: polyethylene terephthalate (hereinafter referred to as PET) containing 0.015% by weight of colloidal silica having an average particle diameter of 0.4 μm and 0.005% by weight of colloidal silica having an average particle diameter of 1.5 μm ), And polymer B: polypropylene terephthalate (hereinafter referred to as PPT) after being sufficiently vacuum-dried.
The polymer B is supplied to the extruder 2, and the polymer B
After melting at 45 ° C. and filtering these polymers with high precision, they were melt-extruded in a two-layer laminated structure at a rectangular junction. This was wound around a casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method, and cooled and solidified to form an unstretched film. This unstretched film was stretched 3.5 times in the longitudinal direction at 95 ° C. The PPT side of this film was subjected to corona discharge treatment in air, and the treated surface was coated with a coating liquid a for forming an easily adhesive layer. The coated uniaxially stretched film is guided to a preheating zone while being gripped with a clip, dried at 110 ° C., then continuously stretched 3.5 times in the width direction in a heating zone, and further subjected to a heat treatment at 225 ° C. An easily adhesive polyester film was obtained.

At this time, when the thickness of the base PET film is 4
9.5 μm, the thickness of the PPT layer was 0.5 μm, and the thickness of the easily adhesive layer was 0.15 μm.

As shown in Table 1, an increase in haze after forced heating was suppressed, and the adhesiveness was good.

Easy-coating layer-forming coating liquid a: An aqueous coating liquid comprising a polyester resin (two kinds) comprising the following acid component and glycol component and a crosslinking agent.

Polyester resin A 50 parts by weight Acid component Terephthalic acid 50 mol% Isophthalic acid 25 mol% Sebacic acid 24 mol% 5-Sodium sulfonyl isophthalic acid 1 mol% Glycol component Ethylene glycol 55 mol% Neopentyl glycol 45 mol% 50 parts by weight of polyester resin B-Acid component 87.5 mol% of terephthalic acid 12.5 mol% of 5-sodium sulfonyl isophthalic acid-Glycol component Ethylene glycol 100 mol% 5 parts by weight of methylolated melamine-based crosslinking agent And diluted with water to a solids concentration of 5% by weight.

Examples 2 and 3 The thickness of the PPT layer of Example 1 was 0.1 μm (Example 2),
An easily adhesive polyester film was prepared in the same manner as in Example 1 except that the thickness was 3.0 μm (Example 3). All of these films showed little increase in haze value and good adhesion.

Example 4 As the polymer B of Example 1, PPT / polymer A = 8
An easily adhesive polyester film was prepared in the same manner as in Example 1 except that the ratio was 0/20 (weight ratio). This film had a small increase in haze value and good adhesion.

Example 5 An easily adhesive polyester film was prepared in the same manner as in Example 1, except that the composition of the coating solution for forming an easily adhesive layer in Example 1 was changed to the following coating solution b for forming an easily adhesive layer. This film had a small increase in haze value and good adhesion.

Coating liquid b for forming an easily adhesive layer: An aqueous emulsion of a copolymerized acrylic resin comprising the following monomer components. The mixture was diluted with water to a solid concentration of 5% by weight.

-Methyl methacrylate 60 mol%-Ethyl acrylate 33 mol%-Acrylic acid 5 mol%-N-methylolacrylamide 2 mol% Example 6 The composition of the easy-adhesion layer forming coating liquid of Example 1 is as follows. An easily adhesive polyester film was prepared in the same manner as in Example 1 except that the forming coating liquid c was used. This film had a small increase in haze value and good adhesion.

Easy-coating layer forming coating liquid c: an aqueous coating liquid comprising the following polyurethane resin and a polyester resin comprising the following acid component and glycol component.

Polyurethane resin 70 parts by weight "Hydran" AP40 (manufactured by Dainippon Ink and Chemicals, Inc.) Polyester resin 30 parts by weight Acid component Terephthalic acid 87.5 mol% 5-sulfonylsulfonyl isophthalic acid 12.5 mol% Glycol component Ethylene glycol 100 mol% The mixture was mixed so as to have the above-mentioned solid content ratio, and diluted with water so as to have a solid content concentration of 5% by weight.

Example 7 In Example 1, B / A / B (thickness composition: 0.5 / 49 / 0.5 μm) was obtained by laminating polymer B on both sides of polymer A.
m) An easily adhesive polyester film was prepared in the same manner as in Example 1 except that the composite film having the constitution was used. This film had a small increase in haze value and good adhesion.

Comparative Example 1 A film was prepared in the same manner as in Example 1 except that the single-layer film containing only the polymer A without using the polymer B was provided with an easy-adhesion layer. As shown in Table 1, the haze value after forcible heating increased and the adhesiveness also decreased.

Comparative Example 2 A film was prepared in the same manner as in Example 1, except that the easy-adhesion layer of Example 1 was not formed. The results are shown in Table 1,
The haze value rises slightly because the easy adhesion layer is not provided on the surface layer,
In addition, the adhesiveness was poor.

[0060]

[Table 1]

[0061]

The easily adhesive polyester film produced according to the present invention has at least one surface of a base film mainly composed of polyethylene terephthalate.
Layers mainly composed of polypropylene terephthalate are laminated, and an easy-adhesion layer is provided through this layer.Polypropylene terephthalate prevents oligomer precipitation, and simultaneously achieves both haze value increase suppression and adhesiveness. can do.

Claims (3)

[Claims] 1. A base film mainly composed of polyethylene terephthalate, on at least one side of which a layer mainly composed of polypropylene terephthalate is laminated, and an easy-adhesion layer is provided via this layer. Easily adhesive polyester film. 2. The polyester film according to claim 1, wherein the thickness of the layer mainly composed of polypropylene terephthalate is 0.05 to 3 μm. 3. The adhesive layer according to claim 1, wherein said easy-adhesion layer comprises at least one selected from a polyester resin, an acrylic resin and a polyurethane resin.
The easily adhesive polyester film according to claim 1 or 2, wherein the polyester film comprises a seed.