JPH01125227A - Laminated polyester film and production thereof - Google Patents

Abstract

PURPOSE:To obtain a laminate polyester film comprising a modified layer having excellent easiness of adhesion, solvent resistance, alkali resistance and water resistance, by mixing specified amounts of a water-soluble or water- dispersible resin and a copolymer obtained by grafting a graft compound onto the resin in a specified range, applying the mixture to a polyester film by use of a crosslinking binder, then stretching the film and causing thermal crosslinking to provide the modified layer. CONSTITUTION:A laminate polyester film comprises, on at least one side of a polyester film, a crosslinked modified layer comprising as a main constituents a hydrophilic group-containing polyester resin A, a copolymer C obtained by grafting at least one compound B having an unsaturated bond to the resin A, and a crosslinking binder. The modified layer has a grafting degree of the copolymer C of 0.5-600% and a mixing ratio of the copolymer C to the resin A of 90/10-5/95. By this, a laminate polyester film can be provided which has excellent adhesion, solvent resistance, water resistance and alkali resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a laminated polyester film. Specifically, the present invention relates to a laminated polyester film having a modified layer with excellent adhesion, solvent resistance, alkali resistance, and water resistance.

[Prior Art] Polyester biaxially stretched films have excellent properties such as mechanical properties, electrical properties, dimensional stability, transparency, and heat resistance, so they are used as magnetic recording materials, packaging materials, electrical insulating materials, It is widely used as a base film for many applications such as various photographic materials and graphic arts materials. However, the polyester film surface generally has high cohesiveness and poor adhesion, so various coatings such as magnetic paint, chemical matte paint, diazo paint, gelatin composition, and heat sealing composition are applied to the surface. When applying ink, etc., the film surface is subjected to corona discharge treatment, corona discharge treatment under various gas atmospheres, plasma treatment, treatment, ultraviolet irradiation treatment, etc. in order to strengthen the adhesion of the coating layer. Physical treatment methods, chemical treatment methods such as chemical etching treatment with alkali, trichloroacetic acid, amines, phenols, etc., primer treatment, and treatment methods using a combination of these are known. Among these, primer treatment on the surface of polyester film to provide easy adhesion is widely practiced as it has advantages such as safety in processing and work and maintaining high quality of film processed products.Moreover, primer treatment can be done all at once during the manufacturing process of polyester film. This method is considered to be effective in terms of process simplification and manufacturing cost, and is being widely implemented. On the other hand, many water-based compositions have been proposed as primer treatment agents, among them water-soluble or water-dispersible compositions that have excellent applicability to polyester substrates, adhesion of coating layers, and abrasion resistance. Various studies have been made to form a coating layer made of a composition containing polyester resin as a main component. Examples of such a laminated polyester film include (1) a laminated polyester film in which a polyester resin in which a hydrophilic group is introduced into a polyester resin by a copolymerization method to impart water solubility or water dispersibility to the film surface is coated; For example, Tokuko Sho 47-408
73@ Publication, Special Publication No. 5B-5476, Japanese Unexamined Patent Publication No. 1983
-8845, Japanese Unexamined Patent Publication No. 61-85436, etc.

(2) A laminated polyester film in which a composition consisting of a mixture of a water-soluble or water-dispersible polyester resin and various water-soluble or water-dispersible resins other than the above resin is coated on the surface of the film. For example, there is Japanese Patent Application Laid-Open No. 58-124651.

etc. are known.

[Problems to be Solved by the Invention] However, the above-mentioned laminated polyester film having easy adhesion properties has the following problems.

In item (1) above, even if the desired easy adhesion is obtained, the laminated film has poor water resistance and hot water resistance, so the laminated film may cause blocking between films under high temperature or high humidity atmosphere, or Depending on the processed product, if it is subjected to hot water treatment during the manufacturing process, the adhesive strength with other types of materials will drop significantly.

In general, it is difficult to sufficiently cross-link polyester resins, so when applying organic solvent-based paints on the surface of laminated films, the solvent resistance is poor, so in some cases, the laminated film may partially dissolve, causing the film to deteriorate. may become cloudy, or the interface with the property-imparting layer formed on the laminated film may be disturbed and become non-uniform, leading to deterioration of properties.

In the above item (2), it is difficult to obtain a homogeneous mixture layer, but even if it is obtained, the water resistance and solvent resistance of the polyester resin are insufficient and are inherent in the laminated film.

Furthermore, in some cases, the adhesion between the laminated film and the substrate base may be reduced, or the properties of the film may be deteriorated during recovery and reuse of film flakes.

The present invention solves the drawbacks of these conventional techniques and provides a laminated polyester film that has excellent adhesion, solvent resistance, water resistance, and alkali resistance. The present invention provides a laminated polyester film with excellent adhesiveness, solvent resistance, water resistance, and alkali resistance.

[Means for Solving the Problems] The present invention provides at least one side of a polyester film,
A hydrophilic group-containing polyester resin [A] and a compound [B] having at least one unsaturated bond in the resin [A]
In a laminated polyester film comprising a crosslinked modified layer mainly composed of a copolymer [C] grafted with a copolymer [C] and a crosslinking agent, the crosslinked modified layer must be a copolymer [C] grafted with a copolymer [C]. ]
The grafting rate of 0.5 to 600%, the copolymer [C]
and the resin [A] in a mixing ratio of 90/10 to 5/95, and a method for producing the same.

The polyester used in the present invention refers to well-known polyesters, specifically, for example, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, bis-α,β(2-chlorophenoxy)ethane-4,4′-dicarboxylic acid, and adipine. Polyester obtained by polycondensing at least one difunctional carboxylic acid such as acid/sebacic acid and at least one glycol such as ethylene glycol, triethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, etc. can be mentioned. Further, the polyester may be blended or copolymerized with other polymers within the range that does not impede the purpose of the present invention, and may contain antioxidants, heat stabilizers, lubricants, pigments, ultraviolet absorbers, etc. You can leave it there.

The intrinsic viscosity of the polyester (measured in orthochlorophenol at 25°C) is 0.4 to 2.0, preferably 0.4 to 2.0.
A value in the range of 5 to 1.0 is usually used.

The present invention includes polyesters such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene-α, β-bis(2-chlorophenoxy)ethane-
Particularly excellent effects are obtained when 4,4'-dicarboxylate is used.

The crosslinked modified layer (hereinafter abbreviated as modified layer) as used in the present invention refers to a hydrophilic group-containing polyester resin [A] and the resin [A
] A compound having at least one unsaturated bond in [
This layer is composed of a composition whose main components are a copolymer [C] grafted with B] and a crosslinking agent. The term "main component" means that the component itself occupies 80% or more of the modified layer.

In the present invention, such a modified layer is provided on at least one side of the polyester film, but if it is provided on both sides, the following description of the modified layer applies to at least one side.

The hydrophilic group-containing polyester resin [A] (hereinafter abbreviated as resin [A]) in the present invention refers to a hydrophilic group or a hydrophilic component in the molecule, such as a hydroxyl group, a carboxyl group, a carbonyl group, a cyano group, Amino group, methylcarbonyl group,
It is a polyester copolymer into which at least one of polyethylene glycol, carboxylate, phosphate ester salt, quaternary ammonium salt, sulfate ester salt, sulfonate, etc. is introduced. Among these, typical polyester copolymers having the following compositions are useful.

That is, examples include polycondensates of aromatic dicarboxylic acids and/or non-aromatic dicarboxylic acids, ester-forming sulfonic acid alkali metal salt compounds, and glycols. Specifically, aromatic dicarboxylic acids include, for example, terephthalic acid,
Isophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-〇, p
-dicarboxylic M and their ester-forming derivatives; non-aromatic dicarboxylic acids include, for example, oxalic acid, malonic acid, succinic acid, geltaric acid, adipic acid, sebacic acid, 1,2-cyclohexanedicarboxylic acid, 1, Examples include 4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, and ester-forming derivatives thereof. Among these, it is preferable that aromatic dicarboxylic acids and/or their ester-forming derivatives account for 40 mol% or more of the total dicarboxylic acid components in terms of heat resistance, film strength, and water resistance of the resin, and within this range, More than one type of dicarboxylic acid may be used in combination.

Examples of ester-forming sulfonic acid alkali metal salt compounds include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, and 4-sulfonaphthalene-2.
, 1-dicarboxylic acid, sulfo-p-xylylene glycol, 2-sulfo-1,4-bis(hydroxyethoxy)
Examples include alkali metal salts such as benzene (alkali metal salts of sulfonic acids) and ester-forming derivatives thereof, and 5-sulfoisophthalic acid, sodium sulfoterephthalic acid and their ester-forming derivatives are more preferably used. .

Next, the glycol component is an aliphatic glycol having 2 to 8 carbon atoms or an alicyclic glycol having 6 to 12 carbon atoms,
For example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,2-propylene glycol, neopentyl glycol, 1,4-cyclohexane dimetatool, 1,6-hexanediol, 1,3-
Cyclohexane dimetatool, 1°2-cyclohexane dimetatool, p-xylylene glycol, diethylene glycol, triethylene glycol and the like are preferably used.

In some cases, polyethers may be copolymerized.

The term "polyether" as used herein refers to a hydrophilic polymer having ether bonds as its main bond chain, and aliphatic polyethers are particularly preferred, such as polyethylene glycol, polypropylene glycol, glycerin ether,
Polyethylene glycol ether and the like are preferably used.

The resin [A] may be water-soluble or water-dispersible, and its solubility depends on the type of copolymer component, the blending ratio, or the presence or absence of addition of a hydrophilic organic compound used as a dispersion stability imparting agent, and its type. The hydrophilic organic compound is preferably added in a small amount as long as it does not impair dispersion stability, although it varies depending on the composition, formulation, etc. In addition, hydrophilic organic compounds include aliphatic and alicyclic alcohols, esters, ethers, and ketones. For example, alcohols include methanol, ethanol, isopropanol, n-butanol, and glycols include ethylene glycol and propylene. Examples of glycols include methyl cellosolve, ethyl cellosolve, and n-butyl cellosolve as derivatives; ethyl acetate as esters; dioxane and tetrahydrofuran as ethers; and methyl ethyl ketone as ketones. The hydrophilic organic compounds may be used alone or in combination of two or more as necessary. Among hydrophilic compounds, butyl cellosolve and ethyl cellosolve are particularly preferred from the viewpoint of dispersion performance, dispersion stability, coating properties, etc. In general, in resin [A], an increase in the amount of components that particularly contribute to hydrophilicity, such as the ester-forming sulfonic acid alkali metal salt compound in the copolymerization component, significantly deteriorates the water resistance of the applied modified layer. Therefore, it is preferable to use a small amount as long as solubility, dispersion stability, etc. are not impaired.

In the present invention, the glass transition temperature (TCI) of the resin [A] is 3.
It is desirable that the temperature is in the range of 0 to 80°C, preferably 50 to 75°C. If the glass transition temperature of the resin [A] is less than 30° C., the resulting modified layer will have poor water resistance, alkali resistance, and heat resistance, resulting in an increase in various disadvantages. If the temperature exceeds 80°C, the dispersion stability will be poor and grafting of compounds having unsaturated bonds will be extremely difficult.

Resin [A] can usually be manufactured using conventional polyester manufacturing techniques. That is, the desired polymer is obtained by melt polycondensing the acid component and glycol component described above using a reaction catalyst such as an esterification or transesterification catalyst or a polymerization catalyst. Solution polycondensation can also be applied to the coating. At this time, various modifiers, stabilizers, etc. may be added to the extent that they do not adversely affect the grafting reaction.

Furthermore, the presence of the hydrophilic organic compound is necessary to obtain an aqueous dispersion of resin [A] lacking in water solubility.

Usually resin [A] and hydrophilic organic compound are mixed, and while stirring,
Preferably, it is produced by adding water while heating and stirring, or by adding the above mixture to water while stirring. In addition, when the solid content concentration of the obtained aqueous dispersion increases, the resin [A
] The fine particles tend to re-agglomerate, making the homogeneous dispersion system unstable and making the grafting reaction difficult.

Compound [B] having an unsaturated bond as used in the present invention (hereinafter referred to as
(abbreviated as compound [B]) is a compound grafted onto resin [A], and specifically, as vinyl esters, for example, vinyl propionate, vinyl stearate, higher tertiary vinyl ester, Vinyl chloride, vinyl bromide, unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate,
Butyl methacrylate, butyl maleate, octyl maleate, butyl fumarate, octyl fumarate, glycidyl acrylate, glycidyl methacrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, methacrylic acid Dimethylaminoethyl, dimethylaminoethyl acrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, unsaturated carboxylic acid amides such as acrylamide,
Methacrylamide, methylol acrylamide, butoxymethylol acrylamide, unsaturated nitriles such as acrylonitrile, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic acid ester, fumarr
i Acidic esters, acidic itaconic acid esters, acrylic compounds such as allyl acetate, allyl glycidyl ether, allyl methacrylate, allyl acrylate, diallyl itaconate, nitrogen-containing compounds such as vinylpyridine,
Vinylimidazole, hydrocarbons such as ethylene, propylene, hexene, octene, styrene, vinyltoluene, butadiene, vinylsilane compounds,
Examples include dimethylvinylmethoxysilane, dimethylethylethoxysilane, methylvinyldimethoxysilane, methylvinyljethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, etc.; At least one or more of the above may be applied, but the invention is not particularly limited.

The grafted copolymer [C] in the present invention (hereinafter referred to as
The polymer [C]) is obtained by grafting the compound [B] onto the resin [A]. Incidentally, the polymer [C] is produced by a conventional graft polymerization method. That is, the reaction is carried out by adding compound [B] in an aqueous medium system of resin [A] in the presence of a water-soluble or water-dispersible polymerization initiator. Examples of the polymerization initiator include ceric ammonium nitrate, potassium persulfate, ammonium persulfate, cesium ammonium sulfate, hydrogen peroxide, azobisisobutyronitrile, and benzoyl peroxide. It is preferable to use an organic peroxide such as benzoyl peroxide in terms of graft polymerization reactivity to A]. The graft polymerization reaction is usually performed under cooling or heating, and the reaction temperature is 5 to 100°C, preferably 1
The temperature is 0 to 80°C.

In the present invention, the grafting rate of compound [B] to resin [A] is 0.5 to 600%, preferably 5 to 300%.
, more preferably in the range of 10 to 100%. If the grafting rate is less than 0.5%, the solvent resistance and water resistance of the modified layer will deteriorate, which is not preferable. If the grafting rate exceeds 600%, coating properties may deteriorate,
This is not preferable because it reduces the adhesion between the modified layer and the substrate base.

The crosslinking agent used in the present invention refers to a crosslinking agent that undergoes a thermal crosslinking reaction with a functional group present in the resin [A] or polymer [C], such as a hydroxyl group, a carboxyl group, a glycidyl group, an amide group, etc., and finally forms a tertiary This is a crosslinking agent for forming a modified layer having an original network structure.

In the present invention, it is preferable to use a melamine crosslinking agent, a urea crosslinking agent, or an epoxy crosslinking agent as the crosslinking agent because the crosslinking effect is particularly large and a modified layer with excellent water resistance and solvent resistance can be obtained. Specific examples of epoxy crosslinking agents include polyepoxy compounds, jepoxy compounds, monoepoxy compounds, etc. Examples of polyepoxy compounds include sorbitol, polyglycidyl ether,
Polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and as the jepoxy compound, for example, neopentyl glycol diglycidyl ether, 1,6-hexanesiol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether , monoepoxy compounds such as allyl glycidyl ether,
Examples include 2-ethylhexylglycidyl ether and phenylglycidyl ether. Examples of the urea curing agent include dimethylolurea, dimethylolethyleneurea, dimethylolpropyleneurea, tetramethylolacetyleneurea, 4methoxy5dimethylpropyleneurea dimethylol, and the like. As the melamine-based crosslinking agent, compounds obtained by etherifying a methylolmelamine derivative obtained by condensing melamine and formaldehyde with lower alcohol such as methyl alcohol, ethyl alcohol, isopropyl alcohol, etc., and mixtures thereof are preferable. Examples of methylolmelamine derivatives include monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, and hexamethylolmelamine.

These crosslinking agents may be used alone, or in some cases, two or more types may be used in combination. The amount of the crosslinking agent added is preferably 0.001 to 60 parts by weight, and 0.01 to 20 parts by weight per 100 parts by weight of solid content in the mixture of resin [A] and polymer [C].
Parts by weight are more preferred.

If the amount added is less than 0.001 part by weight, the crosslinking effect will be low and the solvent resistance and alkali resistance of the modified layer will deteriorate.

If the amount exceeds 60 parts by weight, the adhesiveness of the modified layer will decrease, and furthermore, the coating properties will deteriorate, making it difficult to form a uniform layer.

Although the polyester film constituting the film of the present invention is at least uniaxially oriented by a conventional method, it is preferably at least biaxially oriented in terms of mechanical strength, dimensional stability, rigidity, etc. Further, the thickness of the polyester film is not particularly limited, but is preferably from 2 to 500 μm, more preferably from 5 to 300 μm, and is excellent in practical handling as a base material.

The laminated thickness of the modified layer constituting the film of the present invention is 090
The range of O5 to 1.0 μm is preferable, and the range of 0.01 to 0.5 μm is more preferable. When the lamination thickness is less than 0.005 μm, uniform lamination is difficult, and the adhesion between the modified layer and the substrate base is reduced, and sufficient adhesion is difficult to achieve. 1.
If it exceeds 0 μm, the slipperiness of the modified layer tends to deteriorate.

The film of the present invention consists of a polymer [C] and a resin [A] of the modified layer.
The weight mixing ratio of is 90/10 to 5/95, preferably 7
0/30 to 20/80, more preferably 60/40 to 3
It is necessary that the range is 0/70. Polymer [C]
If the weight mixing ratio is less than 5%, the solvent resistance, alkali resistance and water resistance of the modified layer will deteriorate, which is not preferable. 9
If it exceeds 0%, the adhesion of the modified layer to the base material will decrease, which is not preferable.

Further, the advantage in post-processing can be increased by incorporating known crosslinking catalysts, specifically salts, inorganic substances, organic substances, acid substances, alkaline substances, etc., and known adhesion promoters in the modified layer. can. Furthermore, if necessary, known additives may be added in amounts that do not impair the effects of the present invention, such as antifoaming agents, coating improvers, thickeners, antistatic agents, antioxidants, ultraviolet absorbers, dyes, and pigments. or fine particles made of an inorganic or organic compound as a lubricant.

Next, the manufacturing method of the present invention will be explained. First, polyester pellets polymerized by a conventional method are sufficiently dried, and then fed to a known extruder, preferably a melt extruder with a compression ratio of 3.8 or more, at a temperature higher than the temperature at which the pellets melt, and at a temperature at which the polymer decomposes. It is melt-extruded into a sheet through a slit-shaped die at the following temperature, and then cooled and solidified to produce an unstretched sheet.

At this time, the intrinsic viscosity of the unstretched sheet is 0 from the film properties.
．． It is desirable that it is 5 or more. Next, the unstretched sheet or the unstretched sheet is heated at 70 to 120°C for 2.0 to 5.
When using an unstretched film, apply a coating material prepared from the above composition for a predetermined period of time on a film stretched 0 times, and dry the coating film to form a predetermined coating layer at 170 to 150 °C. 2.0 to 5.0 times in the vertical direction and 2.0 to 5.0 times in the horizontal direction.
0x circumferential stretching, or 2 when using an axially stretched film.
．． Stretch horizontally by 0 to 5.0 times. In addition, the two-wheel oriented film is oriented at 100 to 1.1 to 3 in at least one direction at 100 to iao'c.
．． It may be stretched 0 times. Furthermore, the biaxially oriented film is heat treated at 150 to 240° C. for 1 to 60 seconds while giving 0 to 10% relaxation, if necessary.

The coating method is not particularly limited and may be an extrusion lamination method or a melt coating method, but since it is possible to coat a thin film at high speed, a gravure coating method using a water-soluble or water-dispersed coating material, It is preferable to apply known methods such as a reverse coat method, a kit coat method, a die coat method, and a metal ring bar code method. In this case, if necessary, the film is subjected to a known surface treatment such as corona discharge treatment in the air or various other atmospheres before coating, which not only improves the coating properties but also improves the quality of the modified layer. can be formed more firmly on the film surface. Although the coating material concentration and coating film drying conditions are not particularly limited, it is desirable that the coating film drying conditions be within a range that does not adversely affect the various properties of the laminated polyester film.

[Evaluation method] The characteristic values of the present invention are based on the following measurement method and evaluation criteria.

(1) Adhesion of the modified layer The adhesion of the modified layer/base film is determined by making cross cuts (100 pieces/-) on the modified layer and using cellophane tape (CT-) at 45 degrees to the cross-cut surface. 24 (manufactured by Chiban ■), applied a load of approximately 5 kO using a hand roller, and
The cellophane tape was pressed back and forth 0 times and then peeled off by hand to observe and evaluate the degree of peeling of the modified layer. The judgment criteria are O:
Good (peeling area less than 5%), △: Slightly poor (peeling area 5%), △: Slightly poor (peeling area 5%)
% or more and less than 20%), X: Poor (peeling area 20% or more)
And so.

(2) Ethyl acetate, toluene, etc. as organic solvents on the surface of the solvent-resistant modified layer.
For each of methyl ethyl ketone, acetone, and isopropanol, a cotton swab impregnated with the solvent was rubbed 5 times (number of reciprocations), and changes in the surface condition were observed with the naked eye and with a magnifying glass/or differential interference microscope. A relative comparison was made with the treated product, and the following judgments were made.

◎: Not much change.

○: Slightly dissolved.

Δ: Quite dissolved, but a modified layer is present.

X: Almost completely dissolved and removed.

(3) After forming a coating layer using the following two types of coating materials on the easily adhesive laminated film, crosscuts (100 pieces/-) are made on the coating film, and the following steps are the same as in (1) above. It was evaluated and judged using the method.

■Gravure printing ink Commercially available gravure ink for cellophane printing: Cellocolor ST
(manufactured by Toyo Ink Mfg. ■) was diluted with a mixed solvent of toluene/ethyl acetate/methyl ethyl ketone (2:1:1) to a concentration of 10% by weight, barcoded, and 100°C x 1.
It was dried for 5 minutes to form a coating layer with a thickness of 1.5 μm.

■Cellulose for diazo binder CAB38 is a commercially available cellulose for siazo binder.
1-05 (manufactured by Nagase Sangyo ■) in ethyl acetate,
Shun with a concentration of 10% by weight, barcoded and 110'CX
It was dried for 1.5 minutes to form a coating layer with a thickness of 5.0 μm.

(4) Water-resistant laminated film was immersed in warm water at 50°C for 30 minutes,
Crosscuts (100 pieces/cd) were put into the modified layer and the above (
Evaluation and determination were made in the same manner as in 1). Incidentally, if the surface condition was observed to be abnormal (white clouding rate), the cellophage evaluation was rated as good (◯) and poor (X).

(5) Alkali resistance After immersing the film (■) on which the cellulose layer for diazo binder was formed in the above (2) in aqueous ammonia with a concentration of 30% by weight at room temperature for 20 hours, the CAB layer was covered with cellophane tape and was prepared in the above (1). It was evaluated and determined using the same method.

(6) Grafting rate (%) The grafted polymer was subjected to CNMR method, IHNM
It was calculated from the following formula based on the analysis results by various analysis methods such as the R method and the INEPT method.

Grafting rate [%) - [Function of the invention] The present invention provides a polyester film with a water-soluble or water-dispersible resin, a copolymer in which a graft compound is grafted onto the resin in a specific range, After blending in a specific amount and applying it using a cross-linking agent, stretching it,
Since a thermally crosslinked modified layer was formed, the following excellent effects could be obtained without deteriorating the various properties of the base film.

[Effects of the invention] (1) The laminated polyester film has excellent adhesive properties, so when a coating layer made of various resin compositions, an inorganic coating layer, a metal vapor deposition coating layer, etc. is provided in post-processing, the coating layer is strong. is formed.

(2) Since the laminated polyester film has excellent solvent resistance, even when an organic solvent-based paint is applied, the layer interface is not disturbed and a uniform layer is formed.

(3) Since the laminated polyester film has excellent alkali resistance, the properties do not deteriorate even if it is subjected to alkali treatment in post-processing.

(4) Since the laminated polyester film has excellent water resistance, blocking does not occur under high temperature or high humidity atmospheres.

The laminated polyester film of the present invention can be applied to base films for magnetic recording media, base films for electrical disconnection, base films for capacitors, base films for packaging, base films for various photographs, base films for optics, base films for graphic arts, etc. However, among others,
It is particularly preferable to use it for substrate base films that require easy adhesion, solvent resistance, and alkali resistance.

[Examples] The present invention will be explained using the following Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 (1) Production of resin [A] 100 parts of dimethyl terephthalate, 100' parts of dimethyl isophthalate, 7 parts of dimethyl 5-sodium sulfoisophthalate, 95 parts of ethylene glycol, 95 parts of neopentyl glycol, 4 parts of manganese acetate in water 0.106 parts of salt and 0.07 parts of calcium acetate dihydrate were mixed and heated under a nitrogen stream for 14 hours.
After distilling methanol out at 0 to 220°C and performing a transesterification reaction, 0.09 part of trimethyl phosphate and 0.06 part of antimony dioxide were added, and the mixture was heated at 240°C to 280°C.
The temperature was raised over 1 hour and 30 minutes, and the pressure was gradually lowered from normal pressure to 0.5 mmHg to remove the generated ethylene glycol from the system, and this state was maintained for 40 minutes to carry out the polycondensation reaction. A polyester copolymer having a rearrangement temperature of 60° C. and an intrinsic viscosity [η] of 0.58 was obtained. Next, a mixture of 250 parts of this polyester copolymer and 110 parts of butyl cellosolve was stirred at 150° C. for 4 hours to obtain a uniform solution. 480 parts of water was gradually added dropwise to the resulting solution under high-speed stirring to obtain a uniform, milky white, opaque solid content concentration of 25%.
% dispersion is 1q.

(2) Production of polymer [C] Add 100 parts of water to 700 parts of the polyester resin dispersion obtained in (1) above, and further add 30 parts of water, 1.5 parts of benzoyl peroxide, and 12 parts of methyl methacrylate. A dispersion of a polymerization initiator consisting of 2.5 parts of polyoxyethylene alkyl ether phosphate was added, and the mixture was heated to 75° C. after nitrogen gas was passed through the mixture for 1 hour while stirring. Next, 37 parts of methyl methacrylate as a graft compound,
25 parts of butyl acrylate, 1 part of glycidyl methacrylate
0 parts of the mixture was added dropwise to the above-mentioned mixture under stirring at 85°C over 60 minutes, and the reaction was carried out while maintaining the state at 85°C for 120 minutes under a nitrogen stream to form an aqueous dispersion with a solid content concentration of 25%. A graft copolymer was obtained.

Incidentally, the grafting rate of the graft compound was 35%.

(3) Production of laminated polyester film Polyethylene terephthalate homopolymer chips (intrinsic viscosity = 0.62, melting point = 259°C) manufactured by a conventional method were heated to 180°C.
It was dried under reduced pressure (3II 1 mHg) at ℃ for 2 hours. The chips were fed to an extruder equipped with a screw with a compression ratio of 3.8 at 280°C, melted and extruded from a T-shaped nozzle, and then wound around a cooling drum with a surface temperature of 20°C using an electrostatic application method to cool and solidify. After forming an unstretched film, the obtained film was
The film was stretched 3.3 times in the machine direction by roll stretching at 0°C.

Next, the polymers produced in <1) and <2> above were mixed uniformly at a solid content ratio of 40(2):60(1>), diluted by adding water, and a melamine-based crosslinking agent was added as a crosslinking agent. MW-12L F (manufactured by v7J Sanwa Chemical Co., Ltd.) was added in an amount of 4 parts by weight per 100 parts by weight of resin solids, and silica sol "Cataroid" (Catalytic Chemical Co., Ltd.) with an average particle diameter of 0.10 μm was added as a lubricant. A coating material containing 0.5 parts by weight of Kogyo (manufactured by Kogyo ■) per 100 parts by weight of resin solid content, with a final adjusted concentration of 3.0% by weight, was applied to one side of the above-mentioned -axially stretched film using a metaling bar. Then, the coated layer was stretched 3.6 times in the transverse direction at 100°C while drying, and heat treated at 210°C for 5 seconds while relaxing by 2% in the transverse direction, to form a modified layer of 0.1 μm. A laminated film with a thickness of 50 μm was obtained.The characteristics of the laminated film thus obtained were as follows.
As shown in the table, adhesiveness, solvent resistance, alkali resistance,
Both had excellent water resistance.

Comparative Example 1 Based on Example 1, a coating material consisting of the composition of Example 1 except for the crosslinking agent was prepared, and a laminated film was obtained in the same manner as in Example 1. As shown in Table 1, the physical properties of this laminated film were poor in solvent resistance, water resistance, and alkali resistance.

Example 2 Based on Example 1, a coating material made of a composition using the epoxy crosslinking agent "Dinacol" EX-314 (manufactured by Nagase Kasei) as the crosslinking agent of Example 1 was prepared, and the following Examples were prepared. 1q of laminated film using the same method as 1. As shown in Table 1, this laminated film has easy adhesion, solvent resistance,
Both water resistance and alkali resistance were excellent.

Comparative Example 2 Based on Example 1, the blocked isocyanate crosslinking agent "Prominate" 910 was used as the crosslinking agent of Example 1.
(manufactured by Takeda Pharmaceutical Co., Ltd.) A coating material consisting of a composition was prepared, and 1q of laminated films were prepared using the same method as in Example 1. As shown in Table 1, the properties of this laminated film are poor in solvent resistance, water resistance, and alkali resistance, indicating that a sufficient crosslinking effect cannot be obtained. Moreover, the coating material had poor storage stability and was prone to gelation.

Example 3. Comparative Examples 3 to 4 Based on Example 1, coating materials with different mixing ratios of the resin [A] and polymer [C] of Example 1 were made, and laminated films were obtained using the same method as in Example 1. .

The properties of these laminated films are shown in Table 1.

As shown in Table 1, when the laminated film falls within the scope of the present invention (Example 3), a film with an excellent balance of adhesiveness, solvent resistance, alkali resistance, and water resistance can be obtained. It can be seen that in cases outside the scope of the invention (Comparative Examples 3 and 4), a film excellent in all properties cannot be obtained.

Example 4. Comparative Examples 5 to 6 Based on Example 1, polymers were made in which the blending ratio and production conditions were slightly changed and the grafting rate was changed in Polymer [C] of Example 1, and the following polymers were the same as Example 1. A laminated film was obtained using this method. As shown in Table 1, the laminated film satisfies each characteristic when the characteristics are within the scope of the present invention (Example 4), but when the characteristics are outside the scope of the present invention (Comparative Example 5). .6) shows that the laminated film does not satisfy all of the characteristics.

Claims (6)

[Claims] (1) A copolymer [C] in which a hydrophilic group-containing polyester resin [A] and a compound [B] having at least one unsaturated bond are grafted onto the resin [A] on at least one side of a polyester film. ], and a crosslinked modified layer containing a crosslinking agent as a main component, wherein the crosslinked modified layer has a grafting ratio of the copolymer [C] of 0.5 to 600. %, and the mixing ratio of the copolymer [C] and the resin [A] is 90/10 to 5/95. (2) Glass transition temperature (Tg) of resin [A] is 30 to 8
Claim No. 1, characterized in that the range is 0°C.
The laminated polyester film described in item 1). (3) The laminated polyester film according to claim (1), wherein the crosslinking agent is a melamine crosslinking agent, a urea crosslinking agent, or an epoxy crosslinking agent. (4) On at least one side of the unstretched or unidirectionally stretched polyester film, a hydrophilic group-containing polyester resin [A] and a compound [B] having at least one unsaturated bond in the resin [A] are added. A water-based coating material consisting of a grafted copolymer [C] and a composition mainly composed of a crosslinking agent is applied, and after drying, it is further stretched in at least one direction and heat treated. A method for producing a laminated polyester film. (5) The glass transition temperature (Tg) of the resin [A] is 30-30
The method for producing a laminated polyester film according to claim (4), wherein the temperature is in the range of 80°C. (6) The method for producing a laminated polyester film according to claim (4), wherein the crosslinking agent is a melamine crosslinking agent, a urea crosslinking agent, or an epoxy crosslinking agent.