JPH11286092A - Laminated polyester film and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated polyester film and manufacture thereof wherein not only the adhesiveness between a substrate polyester film and a lamination film but also the adhesiveness between the polyester film and coating materials or inks of various kinds can be improved, and the polyester film can maintain its improved adhesiveness even under conditions of high temperature and humidity. SOLUTION: The laminated polyester film has at least on one of its surfaces a lamination film composed mainly of a synthetic resin, melamine crosslinking agent, and oxazoline crosslinking agent. After a lamination film forming coating material composed mainly of a synthetic resin, melamine crosslinking agent, and oxazoline crosslinking agent is applied to at least one of the surfaces of the polyester film before the completion of its crystalline orientation, the film is stretched at least in one direction and subjected to a stretching and heat treatment to manufacture a laminated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film and a method for producing the same, and more particularly, to a laminated polyester film having excellent adhesion to various paints and inks, and excellent adhesion under high temperature and high humidity conditions. The present invention relates to a laminated polyester film capable of maintaining properties and a method for producing the same.

[0002]

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

[0003] However, biaxially oriented polyester films generally have a highly crystalline surface, so that various types of paints,
Because of the disadvantage of poor adhesion to ink, studies have been made in the past to impart adhesion to the polyester film surface by various methods.

[0004] Examples of the method for imparting adhesiveness include a surface activation method in which the surface of a base polyester film is subjected to corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, etc., acid,
There are known a surface etching method in which treatment is performed with a chemical such as an alkali or amine aqueous solution, and a lamination method in which various synthetic resins such as an acrylic resin, a polyester resin, a urethane resin, and a polyolefin resin are provided as a primer layer on the film surface. Among the methods for imparting adhesiveness by providing the above-mentioned primer layer by applying various synthetic resins, a coating liquid containing the above-mentioned synthetic resin component is applied to a polyester film before crystal orientation is completed, and dried. After that, a method of completing the crystal orientation by performing stretching and heat treatment (in-line coating method) is considered to be promising in terms of process simplification and manufacturing cost, and is widely adopted in the industry.

That is, since the above-mentioned in-line coating method can be carried out even in the process of producing a polyester film, it is advantageous in terms of cost, and it is possible to select and coat an adhesive substance which can cope with various coatings. Because it is possible, a laminated film in which a water-soluble or water-dispersible polyester resin, acrylic resin, urethane resin, or the like is laminated on a polyester film as an adhesive substance is disclosed in, for example, JP-A-55-15825 and JP-A-58-15858. -77861, JP-A-60-24
Many have already been proposed in Japanese Patent Application Laid-Open Nos. 8232, 62-204940, and 1-18037.

However, in the above-mentioned prior art, when an acrylic resin or a urethane resin is laminated on a polyester film in order to impart adhesiveness, although the adhesiveness with various coating materials and inks as coatings is excellent, the laminated film Adhesion between the polymer and the base polyester film tends to be insufficient, and in particular, the adhesion often becomes insufficient particularly under high-temperature and high-humidity use conditions.

In the above prior art, when a polyester resin is laminated, the adhesiveness between the laminated film and the base polyester film is improved, but the adhesiveness with the ink tends to be inferior. Similarly, the adhesion under the conditions of high temperature and high humidity is often insufficient.

As a method for improving the adhesiveness under the conditions of high temperature and high humidity described above, a method for improving the adhesiveness by increasing the molecular weight of the resin or crosslinking is generally known. For example, a method for forming a laminated film is known. Acrylic resin, urethane resin, or polyester resin may be added with melamine-based crosslinking agent, isocyanate-based crosslinking agent, epoxy-based crosslinking agent, etc. It has been difficult to achieve a balance between the properties and the adhesiveness under high temperature and high humidity use conditions.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide not only an adhesive property between a base polyester film and a laminated film, but also
It is an object of the present invention to provide a laminated polyester film having excellent adhesiveness to various paints and inks and capable of maintaining excellent adhesiveness even under use conditions under high temperature and high humidity, and a method for producing the same.

[0010]

The laminated polyester film of the present invention that achieves the above object has a laminated film comprising a synthetic resin, a melamine-based crosslinking agent and an oxazoline-based crosslinking agent as main components on at least one surface of the polyester film. It is characterized by having.

[0011] The laminated polyester film of the present invention is obtained by adding two specific types of cross-linking agents to the synthetic resin forming the laminated film in combination, thereby improving the adhesiveness between the base polyester film and the laminated film, various paints and the like. The adhesiveness with the ink is remarkably improved, and a property capable of maintaining the excellent adhesiveness under use conditions under high temperature and high humidity is exhibited.

In the laminated polyester film of the present invention, preferably, the synthetic resin in the laminated film is at least one selected from acrylic resin, polyester resin and urethane resin, and the mixing ratio of each component in the laminated film is as follows:
Melamine-based crosslinking agent is 0.2 per 100 parts by weight of synthetic resin.
To 20 parts by weight, the oxazoline-based crosslinking agent is 0.2 to 20 parts by weight, and the weight ratio of oxazoline-based crosslinking agent / melamine-based crosslinking agent is in the range of 0.1 to 10; polyester The film comprises at least one selected from a polyethylene terephthalate film, a polypropylene terephthalate film and a polyethylene-2,6-naphthalate film, and the polyester film comprises a melamine-based crosslinking agent, an oxazoline-based crosslinking agent or a reaction product thereof. It is desirable that the composition contains at least one selected from a total of 5 ppm or more and less than 20% by weight.

In the method for producing a laminated polyester film of the present invention, a laminated film comprising a synthetic resin, a melamine crosslinker and an oxazoline crosslinker as main components is formed on at least one surface of the polyester film before the crystal orientation is completed. After applying the coating liquid, stretching in at least one direction,
It is characterized by performing a heat treatment.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION 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, and preferable polyesters include ethylene terephthalate, propylene terephthalate, and the like. At least one selected from ethylene-2,6-naphthalate, butylene terephthalate, propylene-2,6-naphthalate, ethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate and the like And those having the above component as a main component. One of these components may be used alone or two or more of them may be used in combination. Among them, it is particularly preferable to use a polyester containing ethylene terephthalate as a main component, when comprehensively judging quality, economy and the like. In applications where heat acts on the base material or in applications where the resin shrinks during curing, such as a UV-curable resin as a coating, polyethylene-2, which has excellent heat resistance and rigidity, is used.
More preferably, 6-naphthalate is used.

[0015] These polyesters may further contain some other dicarboxylic acid component or diol component, preferably 2 or more.
0 mol% or less may be copolymerized. Furthermore, in this polyester, various additives, for example, antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants,
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 intrinsic viscosity of the above-mentioned polyester (25 ° C.)
Measured in o-chlorophenol of 0.4-1.2 d
1 / g is preferable, and more preferably 0.5 to 0.1.
Those in the range of 8 dl / g are suitable for practicing the present invention. The polyester film using the polyester is preferably biaxially oriented in a state where the following laminated film is provided. With a biaxially oriented polyester film, generally, a polyester sheet or film in an unstretched state is stretched about 2.5 to 5 times in each of the longitudinal direction and the width direction, and then subjected to a heat treatment to complete the crystal orientation. And shows a biaxially oriented 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. However, from the viewpoint of mechanical strength and handling properties, it is usually 1 to 50.
0 μm, preferably 5 to 300 μm. Further, the obtained films can be used by being bonded by various methods.

In addition, for use as an image receiving sheet or a label, a white polyester film is preferably used as a base film in addition to a transparent polyester film. This white polyester film is not particularly limited as long as it is a polyester film colored white, and preferably has a whiteness of 85 to 150%,
More preferably, it is 90 to 130%, and the optical density is preferably 0.5 to 5, more preferably 1.2 to 3.
For example, when a base film having a small whiteness is used, the pattern and coloring on the opposite surface are transmitted and the appearance of the printed layer on the surface is easily impaired.On the other hand, when the optical density is small, sufficient light reflection is not obtained. It is not possible to obtain, and not only the whiteness when viewed with the naked eye is reduced, but also an undesirable tendency such as being affected by the opposite surface may be caused.

The method for obtaining such optical density and whiteness is not particularly limited, but it can usually be obtained by adding inorganic particles or a synthetic resin incompatible with polyester. The addition amount of these inorganic particles or synthetic resin is not particularly limited, but in the case of inorganic particles, preferably 5 to 3
It is 5% by weight, more preferably 8 to 25% by weight. On the other hand, when adding an incompatible resin,
It is 35% by volume, more preferably 8 to 25% 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 4 μm.
Inorganic particles of up to 1.5 μm can be used as typical examples. Specifically, barium sulfate, calcium carbonate, calcium sulfate, titanium oxide, silica, alumina, talc, clay, and the like, or a mixture thereof can be used.These inorganic particles can be used in other inorganic compounds such as calcium phosphate. , Titanium oxide, mica, zirconia, tungsten oxide, lithium fluoride,
And calcium fluoride. Further, among the inorganic particles described above, Mohs hardness is 5 or less,
It is more preferable to use one having 4 or less, because the whiteness is further increased.

The synthetic 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, polymethylpentene , A modified olefin resin, a polybutylene terephthalate-based resin, a phenoxy resin, a polyphenylene oxide, or the like, and may be used in combination with the above-described inorganic particles. For example, a white polyester film having a specific gravity of 0.5 to 1.3 and having a cavity inside obtained by mixing an inorganic particle or a synthetic resin incompatible with the polyester and an incompatible synthetic resin is particularly excellent in printing characteristics. Is preferable.

Examples of the synthetic resin which is a component of the laminated film in the present invention include acrylic resin, polyester resin, urethane resin, polyolefin resin, polycarbonate resin, alkyd resin, epoxy resin, urea resin,
At least one selected from a phenol resin, a vinyl chloride resin, a vinyl acetate resin, a fluororesin, a silicone resin, a rubber-based resin, and a wax-based resin can be used.

Among them, it is preferable to use at least one selected from acrylic resins, polyester resins and urethane resins in terms of excellent adhesiveness between the obtained laminated film and the polyester film and adhesiveness with various paints and ink layers. Preferably, two different kinds of resins, for example, an acrylic resin and a polyester resin, an acrylic resin and a urethane resin, or a combination of a polyester resin and a urethane resin are used, because the properties of both are developed and the adhesiveness is further improved. More preferred. It is also preferable to use a combination of two different polyester resins with the same resin, for example, a polyester resin, from the viewpoint of improving adhesiveness.
This is the same for other resins.

In the laminated polyester film of the present invention, the acrylic resin used as a component of the laminated film includes, for example, alkyl acrylate, alkyl methacrylate (where the alkyl group is a methyl group, an ethyl group, an n-propyl group, an isopropyl group, -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, Hydroxy group-containing monomers such as 2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-
Amide group-containing monomers such as methylolacrylamide, N-methylolmethacrylamide, N, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide, N, N-diethylaminoethyl acrylate, N , An amino group-containing monomer such as N-diethylaminoethyl methacrylate, an epoxy group-containing monomer such as glycidyl acrylate and glycidyl methacrylate, and a carboxyl group such as acrylic acid, methacrylic acid and salts thereof (lithium salt, sodium salt, potassium salt and the like). It is a polymer using a monomer component containing the salt, and these monomer components are copolymerized using one or more kinds. Further, they can be used in combination with other types of monomers.

Other types of monomers include, for example, epoxy group-containing monomers such as allyl glycidyl ether, and sulfonic acids such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.). Monomer containing a group or a salt thereof, crotonic acid, itaconic acid, maleic acid, fumaric acid and salts thereof (lithium salt, sodium salt,
Monomers containing a carboxyl group or a salt thereof, such as potassium salts and ammonium salts), maleic anhydride,
Monomers containing acid anhydrides such as itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacryloyl Nitriles, alkyl itaconic acid monoesters, vinylidene chloride, vinyl acetate, vinyl chloride, and the like can be used.

In the present invention, as the acrylic resin,
Modified acrylic copolymers, for example, block copolymers and graft copolymers modified with polyester, urethane, epoxy and the like can also be used.

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 ° C.
° C. When an acrylic resin having a low Tg is used, the adhesiveness under high temperature and high humidity tends to be inferior, and when it is too high, a crack may be generated at the time of stretching, which is not preferable. The molecular weight of the acrylic resin is preferably 100,000 or more, more preferably 300,000 or more, from the viewpoint of adhesiveness.

Preferred acrylic resins used in the present invention include copolymers selected from methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-methylol acrylamide, glycidyl methacrylate and acrylic acid. Is mentioned. In producing the laminated polyester film of the present invention, it is possible to apply a water-based resin coating solution to the polyester film before the completion of the crystal orientation, and to perform the heat treatment at a high temperature by stretching and heat treatment to complete the crystal orientation. And a more uniform and thin laminated film can be obtained. When a laminated film is formed by the above method, an acrylic resin which is soluble, emulsified, or suspended in water is preferable in terms of environmental pollution and explosion-proof properties. Such an aqueous acrylic resin is copolymerized with a monomer having a hydrophilic group (such as acrylic acid, methacrylic acid, acrylamide, vinyl sulfonic acid and a salt thereof), and is subjected to 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 polyester film of the present invention, the polyester resin used as a component of the laminated film has an ester bond in a main chain or a side chain and is obtained by polycondensation from a dicarboxylic acid and a diol. is there.

As the carboxylic acid component constituting the polyester resin, aromatic, aliphatic and alicyclic dicarboxylic acids and trivalent or higher polycarboxylic acids can be used. Specific examples of the aromatic dicarboxylic acid 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 and phenylindanedicarboxylic acid. These aromatic dicarboxylic acids preferably account for at least 30 mol%, more preferably at least 35 mol%, most preferably at least 40 mol% of the total dicarboxylic acid components in view of the strength and heat resistance of the laminated film. desirable. Specific examples of the aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecandionic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, and 1,2-cyclohexanedicarboxylic acid. , 1,4
-Cyclohexanedicarboxylic acid and the like, and their ester-forming derivatives.

Specific examples of the glycol component of 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, 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.

When the polyester resin is used as a coating liquid containing an aqueous resin, a compound containing a carboxylate group or a sulfone compound may be used to improve the adhesion of the polyester resin or to make the polyester resin water-soluble. It is preferable to copolymerize a compound containing an acid base. 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-2,3,4,5-tetracarboxylic acid, ethylenetetracarboxylic acid, etc., or a mixture thereof Alkali metal salts, alkaline earth metal salts, and ammonium salts can be used, but are not limited thereto.

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, an alkaline earth metal salt, or an ammonium salt thereof can be used, but is not limited thereto.

In the present invention, 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.

Preferred polyester resins include terephthalic acid, isophthalic acid, sebacic acid and
-Sodium sulfoisophthalic acid, trimellitic acid, pyromellitic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2
And copolymers using a dicarboxylic acid and ethylene glycol, diethylene glycol, 1,4-butanediol and neopentyl glycol as glycol components.

In the laminated polyester film of the present invention, the polyester resin used for the laminated film can be produced by the following production method. For example, three kinds of terephthalic acid, isophthalic acid and 5-sodium sulfoisophthalic acid are used as dicarboxylic acid components, and two kinds of ethylene glycol and neopentyl glycol are used as glycol components.
The copolymerized polyester resin using seeds is described as follows. Terephthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid and ethylene glycol, neopentyl glycol are directly esterified, or terephthalic acid, isophthalic acid, 5-sodium The sulfoisophthalic acid, ethylene glycol, neopentyl glycol can be produced by a method comprising a first step of transesterification with neopentyl glycol and a second step of subjecting the reaction product of the first step to a polycondensation reaction. .

At this time, as a reaction catalyst, for example, an alkali metal, an alkaline earth metal, manganese, cobalt, zinc,
Antimony, germanium, a titanium compound, or the like can be used. As a method for obtaining a polyester resin having a large number of carboxylic acids at terminals and / or side chains, JP-A-54-46294 and JP-A-60-20
No. 9073, JP-A-62-240318, JP-A-53-26828, JP-A-53-26829
JP, JP-A-53-98336, JP-A-56-98336
JP-A-116718, JP-A-61-124684, and JP-A-62-240318 can be produced using a resin obtained by copolymerizing a trivalent or higher polycarboxylic acid. May be used.

The intrinsic viscosity of the polyester resin used for the laminated film in the present invention is not particularly limited, but is preferably 0.3 dl / g or more from the viewpoint of adhesiveness.
It is more preferably at least 0.35 dl / g, most preferably at least 0.4 dl / g. The glass transition point (hereinafter, abbreviated as Tg) of the aqueous polyester resin is preferably from 0 to 90 ° C, more preferably from 10 to 80 ° C. If the Tg is less than 0 ° C, the moisture-resistant adhesiveness is inferior.
If it exceeds, the resin may be inferior in film-forming properties, which may not be preferable. The acid value of the aqueous polyester resin is preferably 20 mg KOH / g or more, more preferably 3 mg KOH / g or more.
It is preferable that it is 0 mgKOH / g or more from the viewpoint of adhesiveness, particularly moisture resistance adhesiveness.

In the laminated polyester film of the present invention, the urethane resin used as a component of the laminated film is not particularly limited as long as it is a water-soluble or water-dispersible urethane resin having an anionic group. And those obtained by copolymerizing a polyisocyanate compound as a main constituent.

As the urethane resin, a resin whose affinity for water is increased by a carboxylic acid group, a sulfonic acid group, or a sulfuric acid half ester base can be used. The content of a carboxylate group, a sulfonate group, a sulfuric acid half ester base or the like is preferably in the range of 0.5 to 15% by weight.

Examples of the polyol compound include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, hexamethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, and triethylene glycol. , Polycaprolactone, polyhexamethylene adipate, polytetramethylene adipate, trimethylolpropane, trimethylolethane, glycerin,
And an acrylic polyol.

As the polyisocyanate compound, for example, tolylene diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, an adduct of tolylene diisocyanate and trimethylolpropane, and an adduct of hexamethylene diisocyanate and trimethylolethane are used. be able to.

Here, as a main constituent of the urethane resin, a chain extender, a crosslinking agent, and the like may be contained in addition to the polyol compound and the polyisocyanate compound. As a chain extender or a crosslinking agent, ethylene glycol, propylene glycol, butanediol, diethylene glycol, ethylenediamine, diethylenetriamine, and the like can be used.

The urethane resin having an anionic group includes, for example, a polyol compound, a polyisocyanate compound,
A method using a compound having an anionic group together with a chain extender, a method of reacting a compound having an anionic group with an unreacted isocyanate group of a generated urethane resin,
And a method in which a group having an active hydrogen of the urethane resin is reacted with a specific compound, or the like, but is not particularly limited.

A urethane resin comprising a polyol compound having a molecular weight of 300 to 20,000, a polyisocyanate compound, a chain extender having a reactive hydrogen atom, a group which reacts with an isocyanate group, and a compound having at least one anionic group is used. preferable. The anionic group in the urethane resin is preferably used as a sulfonic acid group, a carboxylic acid group, or an ammonium salt, a lithium salt, a sodium salt, a potassium salt or a magnesium salt thereof, and particularly preferably a sulfonate group.

The amount of the anionic group in the polyurethane resin is preferably in the range of 0.05% by weight to 8% by weight. 0.
If it is less than 05% by weight, the water dispersibility of the urethane resin tends to be poor, and if it exceeds 8% by weight, the water resistance and blocking resistance of the resin tend to be poor.

The laminated film according to the present invention is obtained by adding a melamine-based crosslinking agent and an oxazoline-based crosslinking agent to the above-mentioned synthetic resin, preferably a synthetic resin selected from at least one of acrylic resin, polyester resin and urethane resin. By doing so, the adhesiveness under normal conditions and the adhesiveness under high temperature and high humidity are dramatically improved.

The melamine crosslinking agent used in the present invention is not particularly limited, but is partially or completely reacted by reacting a lower alcohol with melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, or partially or completely. Etherified compounds or mixtures thereof can be used. In addition, as the melamine-based cross-linking agent, a monomer, a condensate composed of a multimer of a dimer or more, or a mixture thereof can be used. Lower alcohols used for etherification include methyl alcohol, ethyl alcohol,
Isopropyl alcohol, n-butanol, isobutanol, and the like can be used. The functional group is a compound having an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, and includes an imino group-type methylated melamine resin, a methylol group-type melamine resin, and a methylol group-type. Methylated melamine resins and fully alkylated methylated melamine resins. Among them, the use of a methylolated melamine resin is most preferred. Further, an acidic catalyst such as p-toluenesulfonic acid may be used in order to promote the thermal curing of the melamine-based crosslinking agent.

The oxazoline-based crosslinking agent used in the present invention is not particularly limited as long as it has an oxazoline group as a functional group in the compound, and contains at least one or more oxazoline group-containing monomers. Those comprising an oxazoline group-containing copolymer are preferred. As such oxazoline-based cross-linking agents, JP-A-Hei.
Copolymers described in JP-A-60941, JP-A-2-99537, JP-A-2-115238, JP-B-63-48884 and derivatives thereof can be used.

Specifically, the following general formula (I)

[0051]

Embedded image

(Where R ₁ , R ₂ , R ₃ , R ₄
Are each independently hydrogen, halogen, alkyl, aralkyl, phenyl or substituted phenyl groups, and R ₅ is a noncyclic organic group having an addition-polymerizable unsaturated bond. A copolymer obtained by copolymerizing the addition-polymerizable oxazoline represented by the formula (1) and at least one other monomer can be used.

Examples of the addition-polymerizable oxazoline include 2-vinyl-2-oxazoline and 2-vinyl-4-methyl-2.
-Oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-
Isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like can be used, and one or a mixture of two or more thereof can also be used. Among them, 2-isopropenyl-2-oxazoline is preferable because it is easily available industrially.

In the oxazoline-based crosslinking agent, the at least one other monomer used for the addition-polymerizable oxazoline is not particularly limited as long as it is a monomer copolymerizable with the addition-polymerizable oxazoline.
Acrylic esters or methacrylic esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and acrylic acid , Methacrylic acid, itaconic acid, unsaturated carboxylic acids such as maleic acid, acrylonitrile, unsaturated nitriles such as methacrylonitrile, acrylamide, methacrylamide, N-methylol acrylamide, unsaturated amides such as N-methylol methacrylamide, Vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; olefins such as ethylene and propylene; vinyl chloride; vinyl chloride Emissions, halogen-containing -α such as vinyl fluoride, beta-unsaturated monomers, and styrene, alpha-
Α, β-unsaturated aromatic monomers such as methylstyrene can be used, and one or a mixture of two or more thereof can be used.

In order to obtain an oxazoline-based crosslinking agent using addition-polymerizable oxazoline and at least one other monomer, polymerization may be carried out by an emulsion polymerization method, a solution polymerization method or the like.

For example, in the emulsion polymerization method, a polymerization catalyst, water,
A method in which a surfactant and a monomer are mixed at once and polymerization is performed, or various methods such as a monomer dropping method, a multi-stage polymerization method, and a pre-emulsion method can be used. Examples of the polymerization catalyst include benzoyl peroxide, t-butyl hydroperoxide, azobisisobutyronitrile,
Radical polymerization initiators such as hydrogen peroxide, potassium persulfate, ammonium persulfate, and 2,2′-azobis (2-amidinopropane) dihydrochloride can be used.
As the surfactant, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, a reactive surfactant, or the like can be used. The polymerization temperature is usually from 0 to 100.
° C, preferably 50 to 80 ° C, and the polymerization time is usually 1 to 10 hours.

Examples of the solvent that can be used in the solution polymerization method include toluene, hexane, methyl ethyl ketone, ethyl cellosolve, methyl cellosolve, ethyl acetate, isopropyl alcohol, and propylene glycol monomethyl ether. Mixtures of the above can also be used. Examples of the polymerization initiator used include azobisisobutyronitrile and benzoyl peroxide. The polymerization temperature is from 20 to 200C, preferably from 40 to 120C.

In obtaining an oxazoline-based cross-linking agent using an addition-polymerizable oxazoline and another monomer, the amount of the addition-polymerizable oxazoline used is 0.5 to 8 in all monomers.
There is no particular limitation as long as it is in the range of 0% by weight or more. If the amount of the addition-polymerizable oxazoline is less than 0.5% by weight, the crosslinking effect by the oxazoline group is small, and the adhesiveness tends to be poor. If the amount exceeds 80% by weight, the affinity with other resin used in combination and the crosslinking agent itself are used. Tend to be inferior in polymerizability.

The oxazoline-based crosslinking agent thus obtained is obtained, for example, in the form of an aqueous dispersion by the emulsion polymerization method and in the form of an organic solvent liquid by the solution polymerization method.
Any of these can be used as it is as a coating liquid for forming a laminated film. In addition, a solution obtained by a solution polymerization method can also be used as a pseudo-aqueous coating liquid by a method such as addition of water as long as it is an aqueous organic solvent. In particular, when the thus obtained resin is used by mixing with another resin, for example, an aqueous resin, the synthetic resin used in the present invention is more preferable than the aqueous dispersion obtained by the emulsion polymerization method. This is preferable because the affinity with the resin is increased and the crosslinking effect is significantly increased.

In the present invention, in addition to the above-mentioned melamine-based crosslinking agent and oxazoline-based crosslinking agent, a functional group existing in the synthetic resin, for example, a hydroxyl group, a carboxyl group,
A crosslinking agent capable of performing a crosslinking reaction with a methylol group or the like may be used in combination. For example, ureol-based, acrylamide-based, polyamide-based resins, epoxy compounds, isocyanate compounds, aziridine compounds, various silane coupling agents, various titanate-based coupling agents, etc., which are methylolated or alkylolated, can be used.

In the laminated film according to the present invention, a synthetic resin,
The melamine-based cross-linking agent and the oxazoline-based cross-linking agent can be used in a mixture at an arbitrary ratio. The addition ratio of the melamine-based crosslinking agent is
The range of 0.2 to 20 parts by weight relative to 0 parts by weight is preferable from the viewpoint of improving adhesion under normal conditions, and more preferably 0.5 to 20 parts by weight.
-15 parts by weight, most preferably 1-10 parts by weight. When the amount of the melamine-based crosslinking agent is less than 0.2 parts by weight, the effect of the addition is small. When the amount exceeds 20 parts by weight, the adhesiveness tends to be reduced.

The addition ratio of the oxazoline-based crosslinking agent is preferably from 0.2 to 20 parts by weight based on 100 parts by weight of the synthetic resin from the viewpoint of improving the adhesion under normal conditions, more preferably from 0.5 to 15 parts by weight. It is added by weight, most preferably 1 to 10 parts by weight. When the amount of the oxazoline-based crosslinking agent is 0.2
If the addition is less than 10 parts by weight, the effect of the addition is small, and if it exceeds 20 parts by weight, the adhesiveness tends to decrease.

Further, it should be particularly noted in the present invention that the weight ratio of the above-mentioned melamine-based crosslinking agent and oxazoline-based crosslinking agent to oxazoline-based crosslinking agent / melamine-based crosslinking agent is 0.1%.
It has been found that when the content is in the range of 1 to 10, there is a remarkable effect on the adhesiveness under high temperature and high humidity. According to the findings of the present inventors, the addition weight ratio is set to 0.5 to 5
Within this range, the adhesiveness under high temperature and high humidity is excellent.

The laminated film according to the present invention comprises the above-mentioned synthetic resin, melamine-based cross-linking agent and oxazoline-based cross-linking agent as main constituents. In the present invention, the main component is 70% by weight in the laminated film. It means occupying the above. In particular, in the present invention, the component ratio is preferably 80% by weight or more, more preferably 90% by weight or more.

In the laminated film, various additives such as an antioxidant may be used as long as the effects of the present invention are not impaired.
Heat stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, nucleating agents, and the like may be added. In particular, those obtained by adding inorganic particles to the laminated film are more preferable because the lubricity and the blocking resistance are improved.

In this case, as the inorganic particles to be added, silica, colloidal silica, alumina, alumina sol, kaolin, talc, mica, calcium carbonate and the like can be used. The inorganic particles used preferably have an average particle size of 0.01 to 5 μm, more preferably 0.05 to 3 μm, and most preferably 0.08 to 2 μm. Although not particularly limited, the solid content is preferably 0.05 to 8 parts by weight, more preferably 0.1 to 100 parts by weight per 100 parts by weight of the laminated film.
３3 parts by weight.

In producing the laminated polyester film of the present invention, the most preferable method for providing a laminated film is a method in which the polyester film is applied during the production process of the polyester film and stretched together with the base film. For example, the melt-extruded polyester film before crystal orientation is stretched about 2.5 to 5 times in the longitudinal direction, and a coating liquid is continuously applied to the uniaxially stretched film. Next, the applied film is dried while passing through a stepwise heated zone, and is stretched about 2.5 to 5 times in the width direction. Furthermore, it can be obtained by a method (inline coating method) in which the crystal orientation is completed by being continuously guided to a heating zone at 150 to 250 ° C. The coating solution used in this case is preferably an aqueous solution in view of environmental pollution and explosion-proof properties.

In the present invention, before applying the coating liquid,
The surface of the base film (in the case of the above example, a uniaxially stretched film) is subjected to corona discharge treatment or the like to reduce the surface wetting tension.
Preferably 47 mN / m or more, more preferably 50 mN / m
/ M or more is preferably employed because the adhesion of the laminated film to the base film can be improved and the coating defect can be eliminated.

The thickness of the laminated film is not particularly limited, but is usually preferably in the range of 0.01 to 5 μm, more preferably 0.02 to 2 μm, and most preferably 0.05 to 0.
The range is 5 μm. If the thickness of the laminated film is too small, poor adhesion may occur. Various coating methods, such as a reverse coating method, a gravure coating method, a rod coating method,
Bar coating method, Meyer bar coating method, die coating method,
And a spray coating method.

Next, the method for producing a laminated polyester film of the present invention will be described with reference to an example in which polyethylene terephthalate (hereinafter abbreviated as “PET”) is used as a base film, but the present invention is not limited to this. The laminated polyester film of the present invention, which has excellent adhesiveness with the various paints and inks described above, and also has excellent adhesiveness under high temperature and high humidity, has at least one surface of the polyester film, the above-described resin and a melamine-based crosslinking agent. And a laminated film having an oxazoline-based crosslinking agent as a main component.

More specifically, for example, the intrinsic viscosity is 0.5 to
After vacuum drying 0.8 dl / g of PET pellets, the pellets are supplied to an extruder, melted at 260 to 300 ° C., extruded into a sheet shape from a T-shaped die, and subjected to a surface temperature of 10 to 10 using an electrostatic application casting method. It is wound around a mirror casting drum at 60 ° C. and cooled and solidified to obtain unstretched P.
Create an ET film.

Next, this unstretched film is put in a
The film is stretched 2.5 to 5 times in the longitudinal direction (the direction in which the film advances) between the rolls heated to ° C. At least one surface of the film is subjected to a corona discharge treatment to reduce the surface wetting tension to 47.
mN / m or more, and the coating liquid for forming a laminated film according to the present invention is applied to the treated surface.

The coated film is gripped with a clip, guided to a hot air zone heated to 70 to 150 ° C., dried, stretched 2.5 to 5 times in the width direction, and then stretched 16 times.
It is led to a heat treatment zone of 0 to 250 ° C. and heat treated for 1 to 30 seconds to complete the crystal orientation. During this heat treatment step, a 3 to 12% relaxation treatment may be performed in the width direction or the longitudinal direction as necessary.

The biaxial stretching may be any of longitudinal and transverse sequential stretching or simultaneous biaxial stretching, and may be re-stretched in either the longitudinal or transverse direction after the longitudinal or transverse stretching. Further, the thickness of the polyester film is not particularly limited,
３００300 μm is preferably used. The coating liquid used in this case is preferably water-based in view of environmental pollution and explosion-proof properties.

In the above examples, the base polyester film on which the laminated film is provided can also contain at least one selected from melamine-based crosslinking agents, oxazoline-based crosslinking agents, and reaction products thereof. . In this case, not only the adhesiveness between the laminated film and the base film is improved, but also effects such as improved lubricity of the laminated polyester film are obtained. When a melamine-based cross-linking agent, an oxazoline-based cross-linking agent, or a reaction product of these is contained, the total amount of one or more of them is 5 ppm or more and less than 20% by weight. It is preferable in terms of lubricity. Of course, the melamine-based crosslinking agent, the oxazoline-based crosslinking agent, or a reaction product thereof may be a laminated film forming composition (including a recycled pellet of the laminated polyester film of the present invention) provided on the base film.

The thus obtained laminated polyester film of the present invention has excellent adhesiveness between the base polyester film and the laminated film, and various paints and inks, and at the same time under high temperature and high humidity conditions. Excellent adhesion can be maintained. Therefore, for example, what is printed or displayed on the laminated polyester film of the present invention with various inks can be suitably used in the case of processing under high temperature and high humidity. For example, it can be suitably used for retort treatment or high-temperature sterilization.

[0077]

EXAMPLES In the examples described below, the method for measuring characteristics and the method for evaluating effects in the present invention are as follows. (1) Thickness of Laminated Film The thickness was determined from a photograph obtained by observing the cross section of the laminated polyester film provided with the laminated film using a transmission electron microscope HU-12 manufactured by Hitachi, Ltd. The thickness was an average value of 30 pieces in the measurement visual field.

(2) Adhesion-1 Diferacoat CAD4301 (Dainichi Seika Kogyo Co., Ltd.)
1 part by weight of Sumidur N-75 (manufactured by Sumitomo Bayer Co., Ltd.) was added to 100 parts by weight of the mixture, and this was applied on a laminated polyester film using a bar coater.
After drying for 8 minutes, a coating film having a thickness of 8 μm was formed on the laminated film.

A 1 mm 2 cross cut was applied to the paint dry film.
100 pieces, a polyester adhesive tape manufactured by Nitto Denko Corporation was stuck on it, and a load of 1
After reciprocating three times at 9.6N, pressing, peeling in the direction of 90 °, and four-stage evaluation based on the number of remaining paint dry films (◎: 100, ○: 80 to 99, Δ: 50 to 79, ×:
0 to 49), and (◎) and (○) were evaluated as having good adhesiveness.

(3) Adhesion-2 FLASH DRY (FDO) as an ultraviolet curable ink
L Ink APN) (manufactured by Toyo Ink Mfg. Co., Ltd.) was applied on a laminated polyester film by a roll coating method to form a coating film having a thickness of about 1.5 μm on the laminated film. Thereafter, irradiation was performed at an irradiation distance (a distance between the lamp and the ink surface) of 9 cm for 5 seconds using an ultraviolet lamp having an irradiation intensity of 80 W / cm to cure the ultraviolet curable ink. The evaluation of adhesion was performed by the following method.

The cross cut of 1 mm 2 was made 100
The pieces were put on each other, and a cellophane tape manufactured by Nichiban Co., Ltd. was adhered thereon, and reciprocated three times with a load of 19.6 N using a rubber roller. To give a 4-grade rating (（: 100,
○: 80 to 99, Δ: 50 to 79, ×: 0 to 49)
(A) and (B) were evaluated as having good adhesiveness.

(4) Adhesiveness-3 After providing a cured film of an ultraviolet curable ink on the laminated film in the same manner as in (3) above, a high-temperature and high-humidity treatment (90
C. for 1 hour in hot water). After taking out,
Immediately after the adhered water was wiped off, and after 3 minutes, the same evaluation as in the above (3) was performed.

Example 1 PET pellets 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 (intrinsic viscosity: 0.63 dl / g) ) Is sufficiently dried in a vacuum, fed to an extruder, melted at 285 ° C., extruded into a sheet shape from a T-shaped die, and subjected to a surface temperature of 20 using an electrostatic application casting method.
It was wrapped around a mirror-surfaced casting drum at ℃ to be cooled and solidified.

The unstretched film was heated to 95 ° C. and stretched 3.5 times in the longitudinal direction to obtain a uniaxially stretched film. The film was subjected to a corona discharge treatment in air, the wet tension of the substrate film was set to 52 mN / m, and the following coating liquid for forming a laminated film was applied to the treated surface.

The coated uniaxially stretched film is guided into a preheating zone while being gripped with clips, dried at 110 ° C., and continuously continuously heated in a 125 ° C. heating zone at 3.5 in the width direction.
Stretched twice, and heat-treated in a heating zone at 225 ° C,
A laminated PET film with completed crystal orientation was obtained.

The thickness of the base PET film in the obtained laminated polyester film was 75 μm, and the thickness of the laminated film was 0.15 μm. Table 1 shows the evaluation results of the laminated PET film. `` Laminated film forming coating liquid ''

A. Acrylic resin: Methyl methacrylate 60% by weight Ethyl acrylate 35% by weight Acrylic acid 2% by weight N-methylolacrylamide 2% by weight Acrylonitrile 1% by weight An acrylic resin copolymer emulsion copolymerized with the above composition.

B. Melamine-based cross-linking agent: methylolated melamine is mixed with a mixed solvent of isopropyl alcohol and water (1
0/90 (weight ratio).

C. Oxazoline-based crosslinking agent: methyl methacrylate 50% by weight ethyl acrylate 25% by weight styrene 5% by weight 2-isopropenyl-2-oxazoline 20% by weight The oxazoline group-containing resin composition copolymerized with the above composition is mixed with propylene glycol monomethyl ether and water. And a coating solution diluted with a mixed solvent (20/80 (weight ratio)).

A coating liquid for forming a laminated film was prepared by adding 5 parts by weight of a melamine crosslinking agent and 5 parts by weight of an oxazoline crosslinking agent to 100 parts by weight of the acrylic resin. Example 2 A laminated PET film was obtained in the same manner as in Example 1, except that 2 parts by weight of a melamine-based crosslinking agent was used in the coating liquid for forming a laminated film of Example 1. Table 1 shows the evaluation results of the laminated PET film.

Comparative Example 1 A laminated PET film was obtained in the same manner as in Example 1 except that the melamine-based crosslinking agent and the oxazoline-based crosslinking agent were not used in the coating liquid for forming a laminated film of Example 1. Table 1 shows the evaluation results of the laminated PET film.

Comparative Example 2 Lamination was carried out in the same manner as in Example 1 except that 5 parts by weight of a melamine-based crosslinking agent was added to the coating liquid for forming a laminated film of Example 1 and no oxazoline-based crosslinking agent was used. A PET film was obtained. Table 1 shows the evaluation results of the laminated PET film.
Shown in

Comparative Example 3 Lamination was carried out in the same manner as in Example 1 except that the oxazoline-based crosslinking agent was added in an amount of 10 parts by weight and the melamine-based crosslinking agent was not added to the coating liquid for forming a laminated film of Example 1. A PET film was obtained. Table 1 shows the evaluation results of the laminated PET film.

Comparative Example 4 In the coating liquid for forming a laminated film of Example 1, 10 parts by weight of a crosslinking agent "CR-5L" manufactured by Dainippon Ink and Chemicals, Inc. was added as an epoxy crosslinking agent instead of a melamine crosslinking agent. A laminated PET film was obtained in the same manner as in Example 1, except that 10 parts by weight of the oxazoline-based crosslinking agent was used. Table 1 shows the evaluation results of the laminated PET film.

Example 3 A laminated PET film was obtained in the same manner as in Example 1, except that the synthetic resin was changed to the following polyester-1 in the coating liquid for forming a laminated film of Example 1. Table 1 shows the evaluation results of the laminated PET film. Polyester-1: Acid component Terephthalic acid 45 mol% Isophthalic acid 22 mol% Sebacic acid 30 mol% 5-Sodium sulfoisophthalic acid 3 mol% Diol component Ethylene glycol 55 mol% Neopentylglycol 45 mol% Above acid component and diol The polyester resin comprising the components was mixed with a mixed solution of t-butyl cellosolve and water (10/90
(Weight ratio)).

Example 4 A laminated PET film was prepared in the same manner as in Example 1 except that the following urethane resin was used as a resin in the coating liquid for forming a laminated film, and 2 parts by weight of an oxazoline-based crosslinking agent was added. I got Table 1 shows the evaluation results of the laminated PET film.

Urethane resin: 192 parts by weight of polyether containing sodium sulfonate obtained by sulfonating polyether of ethylene oxide (sulfonic acid group content: 8% by weight), 1013 parts by weight of polytetramethylene adipate,
248 parts by weight of polypropylene oxide polyether were mixed, dehydrated at 100 ° C. under reduced pressure, the mixture was heated to 70 ° C., and a mixture of 178 parts by weight of isophorone diisocyanate and 244 parts by weight of hexamethylene-1,6-diisocyanate was added, The product mixture was further stirred at 80-90 ° C. until the isocyanate content was 5.6% by weight. The obtained prepolymer was cooled to 60 ° C., and bisketimine 173 obtained from 56 parts by weight of biuret polyisocyanate obtained from 3 moles of hexamethylene diisocyanate and 1 mole of water, isophoronediamine and acetone was used.
Parts by weight. Then, hydrazine hydrate 1
An aqueous solution at 50 ° C. in which 5 parts by weight was dissolved was added to this mixture with stirring to obtain a urethane resin aqueous dispersion.

Example 5 A laminated PE was prepared in the same manner as in Example 1 except that a mixture of the following two types of polyester-1 and polyester-2 was used as the synthetic resin in the coating liquid for forming a laminated film of Example 1.
A T film was obtained. Table 1 shows the evaluation results of the laminated PET film. Polyester-1: The same polyester-1 used in Example 3 was used.

Polyester-2: Acid component 88 mol% terephthalic acid 12 mol% 5-sodium sulfoisophthalic acid 12 mol% Diol component Ethylene glycol 99 mol% Diethyleneglycol 1 mol% Water-soluble coating of polyester resin composed of the above acid component and diol component liquid.

50 parts by weight of the above polyester-1
A laminate film forming coating liquid was prepared by adding 5 parts by weight of a melamine-based crosslinking agent and 5 parts by weight of an oxazoline-based crosslinking agent to 100 parts by weight of a total of 50 parts by weight of polyester-2. Example 6 A laminated PE was prepared in the same manner as in Example 5, except that the melamine-based crosslinking agent was added in an amount of 2 parts by weight and the oxazoline-based crosslinking agent was added in an amount of 15 parts by weight in the coating solution for forming a laminated film of Example 5.
A T film was obtained. Table 1 shows the evaluation results of the laminated PET film.

Example 7 A laminated PET film was obtained in the same manner as in Example 1 except that a mixture of the following acrylic resin and polyester-2 was used as a synthetic resin in the coating liquid for forming a laminated film of Example 1. Table 1 shows the evaluation results of the laminated PET film.
Acrylic resin: The same acrylic resin as used in Example 1 was used.

Polyester-2: The same polyester resin as polyester-2 used in Example 5 was used. 70 parts by weight of the above acrylic resin and 30 parts of the polyester resin
A coating liquid for forming a laminated film was prepared by adding 10 parts by weight of a melamine-based crosslinking agent and 2 parts by weight of an oxazoline-based crosslinking agent to 100 parts by weight in total.

Example 8 Lamination was carried out in the same manner as in Example 7, except that 5 parts by weight of a melamine crosslinking agent and 5 parts by weight of an oxazoline crosslinking agent were used in the coating liquid for forming a laminated film of Example 7. PET
A film was obtained. Table 1 shows the evaluation results of the laminated PET film.

Example 9 Lamination was performed in the same manner as in Example 7 except that the melamine-based crosslinking agent was added in an amount of 2 parts by weight and the oxazoline-based crosslinking agent was added in an amount of 5 parts by weight. PET
A film was obtained. Table 1 shows the evaluation results of the laminated PET film.

Example 10 Lamination was carried out in the same manner as in Example 7 except that the melamine-based crosslinking agent was added in an amount of 1 part by weight and the oxazoline-based crosslinking agent was added in an amount of 20 parts by weight. PE
A T film was obtained. Table 1 shows the evaluation results of the laminated PET film.

Example 11 A laminate was prepared in the same manner as in Example 7 except that the melamine-based crosslinking agent was added in an amount of 5 parts by weight and the oxazoline-based crosslinking agent was added in an amount of 30 parts by weight. PE
A T film was obtained. Table 1 shows the evaluation results of the laminated PET film.

Example 12 In Example 8, the polyester film was changed from a polyethylene terephthalate film to polyethylene-2,6-
A laminated PEN film was obtained in the same manner as in Example 8, except that the film was changed to a naphthalate (hereinafter abbreviated as “PEN”) film. Table 1 shows the evaluation results of the laminated PEN film.

Example 13 PET containing 14% by weight of titanium dioxide having an average particle size of 0.2 μm and 0.5% by weight of silica having an average particle size of 1 μm
The pellet (intrinsic viscosity: 0.63 dl / g) was sufficiently dried in a vacuum, fed to an extruder, melted at 285 ° C., extruded into a sheet shape from a T-shaped die, and cast at a surface temperature of 20 using an electrostatic application casting method. It was wrapped around a mirror-surfaced casting drum at ℃ to be cooled and solidified.

The unstretched film was heated to 95 ° C. and stretched 3.2 times in the longitudinal direction to obtain a uniaxially stretched film. This film was subjected to a corona discharge treatment in air, the wet tension of the base film was set to 52 mN / m, and the same coating liquid for forming a laminated film as in Example 8 was applied to the treated surface.

The coated uniaxially stretched film is guided to a preheating zone while being gripped by clips, dried at 110 ° C., and then continuously continuously heated in a 125 ° C. heating zone in a 3.2 direction.
Stretched twice, and heat-treated in a heating zone at 225 ° C,
A white laminated PET film provided with a laminated film whose crystal orientation was completed was obtained.

The thickness of the obtained white base PET film was 75 μm, the optical density was 1.6, the whiteness was 88%, and the thickness of the laminated film was 0.15 μm. Table 1 shows the evaluation results of the laminated PET film.

Example 14 The same procedure as in Example 1 was carried out except that the laminated PET film obtained in Example 1 was pulverized and pelletized, and 20% by weight of polyethylene terephthalate was added thereto and melt-extruded. To obtain a laminated PET film. Table 1 shows the evaluation results of the laminated PET film.

[0113]

[Table 1]

[0114]

As described above, the laminated polyester film of the present invention can be laminated with the base polyester film by providing a laminated film mainly composed of a synthetic resin, a melamine crosslinking agent and an oxazoline crosslinking agent. It has excellent adhesiveness to films and various paints and inks, and can maintain its excellent adhesiveness under use conditions under high temperature and high humidity. Therefore, on the laminated polyester film of the present invention, for example, those printed or displayed with various inks, are used for processing under high temperature and high humidity, for example, suitable for use in performing retort processing or high temperature sterilization processing Can be used.

Further, according to the method of the present invention, a laminated polyester film having the above properties can be efficiently produced.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08J 7/04 CFD C08J 7/04 CFDF // B29K 67:00 B29L 7:00 9:00

Claims (6)

[Claims] 1. A laminated polyester film having a laminated film comprising a synthetic resin, a melamine-based crosslinking agent and an oxazoline-based crosslinking agent as main components on at least one surface of the polyester film. 2. The laminated polyester film according to claim 1, wherein the synthetic resin in the laminated film is at least one selected from an acrylic resin, a polyester resin, and a urethane resin. 3. The mixing ratio of each component in the laminated film is such that the melamine crosslinking agent is 0.2 to 100 parts by weight of the synthetic resin.
20 parts by weight, the oxazoline-based crosslinking agent is 0.2 to 20 parts by weight, and the weight ratio of oxazoline-based crosslinking agent / melamine-based crosslinking agent is in the range of 0.1 to 10; 3. The laminated polyester film according to 2. 4. The laminate according to claim 1, wherein the polyester film comprises at least one selected from a polyethylene terephthalate film, a polypropylene terephthalate film, and a polyethylene-2,6-naphthalate film. Polyester film. 5. The polyester film comprises a melamine-based crosslinking agent, an oxazoline-based crosslinking agent or at least one selected from the reaction products thereof in a total of 5 ppm.
2. The composition according to claim 1, wherein the composition contains less than 20% by weight.
5. The laminated polyester film according to any one of items 4 to 4. 6. A coating liquid for forming a laminated film containing a synthetic resin, a melamine-based cross-linking agent and an oxazoline-based cross-linking agent as main components on at least one surface of the polyester film before the completion of the crystal orientation, and then, in at least one direction. The method for producing a laminated polyester film according to any one of claims 1 to 5, wherein the laminate is subjected to stretching and heat treatment.