JP2828579B2 - Manufacturing method of low charge and easy adhesion polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester film having a low chargeability and high adhesiveness, and more particularly to a method for producing a polyester film having a low chargeability, not causing thermal transfer or shaving during heating in the process, and excellent adhesiveness. The present invention relates to a method for producing a high-strength polyester film having a primer layer coated thereon, which is particularly useful as a base material of a magnetic recording medium.

[0002]

2. Description of the Related Art It is known that a thermoplastic polyester, for example, polyethylene terephthalate or its copolymer, polyethylene naphthalate or its copolymer, or a blend of these with a small proportion of another resin is melt-extruded to form a film. It is. It is also known that the resulting biaxially stretched and heat-set polyester film has better heat resistance, gas barrier properties, electrical properties and chemical resistance than films made of other resins.

[0003] The above polyester film is usually produced by a simple biaxial stretching method, that is, simultaneous or sequential stretching in the machine direction and the transverse direction, followed by heat fixing at a high temperature. For polyester films, further improvement in strength is desired depending on the application. For this reason, as a method for producing a high-strength polyester film, a method in which the film is biaxially stretched in the longitudinal and transverse directions and then stretched again (re-longitudinal stretching method). Has been proposed (Japanese Patent Publication No. 34-5)
887, Japanese Patent Publication No. 36-2258, etc.). In this re-longitudinal stretching method, for example, a polyester film after biaxial stretching is re-longitudinal-stretched under the conditions of a stretching temperature of 80 to 180 ° C. and a stretching ratio of 1.2 or more (in some cases, further transverse stretching). Re-stretched films have the advantage that the mechanical strength in the machine direction is 1.5 times more than that of simple biaxially stretched films, especially magnetic tapes, especially video tapes. It is extremely useful as a base film for use.

By the way, since the surface of the polyester film is highly crystallographically oriented, the surface has high cohesiveness,
For example, the adhesion of paints, adhesives, inks and the like is poor.

[0005] Therefore, as a method for improving the adhesion, physical treatment such as corona treatment, ultraviolet treatment, plasma treatment, EB treatment, flame treatment or the like, or chemical treatment such as alkali, aqueous amine, trichloroacetate phenols or the like is used. Is known. However, these methods have practical disadvantages such as deterioration of the adhesive force with time and contamination of the working environment due to volatilization of the chemical.

As another means, there is known a method in which an easily adhesive coating film is applied to the film surface by a process other than the ordinary polyester film forming process to provide a primer layer. However, in this method, an organic solvent is usually used as a solvent for the coating agent, and it is difficult to say that the coating atmosphere is sufficiently clean. There are safety and hygiene problems such as deterioration.

[0007] Therefore, if this primer treatment is carried out in the process of forming a polyester film using an aqueous coating agent, there is no adhesion of dust in a clean environment, and there is no danger of explosion or deterioration of the environment due to the aqueous solvent. However, it is advantageous in terms of film performance, economy and safety.

[0008]

SUMMARY OF THE INVENTION The present inventor has sought to improve the adhesion of a high-strength polyester film to a low charge property.
When applying the easily adhesive primer coating solution used in the simple biaxial stretching method after the first-stage longitudinal stretching in the re-longitudinal stretching method,
It was clarified that the coating film was transferred to a hot roll during the second-stage longitudinal stretching (re-longitudinal stretching), and the coating film was broken and dropped due to the re-stretching. The present inventor further studied to solve such a trouble, and as a result, the glass transition point (Tg) was 5
0-100 ° C. or higher and 0.1 as a dicarboxylic acid component.
The inventors have found that the above problems can be solved by applying a coating liquid having a water-insoluble polyester having a sulfonate group-containing dicarboxylic acid component of less than 5 mol% and a wetting agent as main components and a film forming temperature of 30 to 70 ° C. The present invention has been reached.

It is an object of the present invention to provide various coatings such as offset inks, gravure inks, etc. which are applied to a polyester film without transferring or falling off the coating film during the production process.
Silk screen inks, UV inks, magnetic paints, adhesives, electrophotographic toners, chemical matte paints, diazo paints, hard coat paints, UV paints, heat sealability-imparting compositions, inorganic film-forming substances, etc., especially for magnetic paints It is an object of the present invention to provide a method for producing a low-charge and easily-adhesive polyester film having a primer layer having excellent adhesiveness and non-tackyness and having a low chargeability.

[0010]

The object of the present invention is to provide a polyester film stretched in the machine direction, having a glass transition point (Tg) of at least one side of 50 to 100 ° C.
A water-insoluble polyester having less than 0.5 mol% of a sulfonic acid group-containing dicarboxylic acid component as a carboxylic acid component and a wetting agent as main components, and having a film forming temperature of 30 to 70.
C., and then drying and stretching in the horizontal direction, further stretching in the vertical direction, and if necessary, stretching in the horizontal direction, followed by heat fixing. This is achieved by a method for producing a chargeable and easily-adhesive polyester film.

In the present invention, the polyester constituting the polyester film is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of the polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), and polyethylene-2,6.
-Naphthalenedicarboxylate and the like, and examples thereof include copolymers thereof and blends thereof with a small proportion of other resins. Among such polyesters, those having a secondary transition point (Tg) of 60 to 90 ° C are preferred.

[0012] The linear saturated polyester in the present invention comprises:
It may contain an agent for improving the film properties such as a lubricant, an antistatic agent, a coloring agent, a flame retardant, a light-shielding agent, a stabilizer, and an ultraviolet absorber. The lubricant may be either internally precipitated particles or externally added particles, or may be a combination of two or more. The externally added particles include, for example, silica, kaolin, calcium carbonate, calcium phosphate, titanium oxide, and the like. The internally precipitated particles include, for example, an alkali (earth) metal compound, a phosphorus compound and the like which are precipitated during the production of the polyester. Can be mentioned.

The polyester in the present invention is known per se and can be produced by a known method. Inherent viscosity of polyester (O-chlorophenol, 35
C) is preferably from 0.45 to 0.9.

In the present invention, an amorphous unstretched film can be obtained by melt-extruding a polyester by a conventional method and quenching and solidifying it. And this unstretched film is
First, the film is stretched in the longitudinal direction and then in the transverse direction. These stretchings are performed by running a film. A known means can be used for the stretching means in the longitudinal direction and the transverse direction. For example, stretching in the longitudinal direction (longitudinal stretching) is performed by heating an unstretched film with a group of heating rolls and utilizing a peripheral speed difference between a low-speed roll and a high-speed roll. At that time, it is preferable to provide an infrared heater between the low-speed roll and the high-speed roll to heat the film to the stretching temperature, or the low-speed roll may heat the film to the stretching temperature. This stretching in the longitudinal direction is 1.5 to
Perform at 5.7x magnification. In addition, stretching in the transverse direction (lateral stretching)
Is performed using a tenter-type stretching heat treatment apparatus. When the horizontal stretching is not performed again, the horizontal stretching is performed at a predetermined magnification. When the horizontal stretching is performed again, the horizontal stretching is performed at a magnification lower than the predetermined magnification (total stretching magnification). The biaxially stretched film stretched in the transverse direction is usually subjected to a heat (fixation) treatment at a low temperature as described above.

The biaxially stretched film thus obtained is further stretched at least in the longitudinal direction, in other words, in the longitudinal direction, or in the longitudinal and transverse directions, and then subjected to a heat (fixing) treatment. This second longitudinal stretching (re-longitudinal stretching) can be performed in the same manner as the above-described first-stage longitudinal stretching means, or can be performed by another method. For example, the first-stage longitudinal stretching can be performed by an infrared heating method, and the re-longitudinal stretching can be performed by a roll heating method. As the method of re-longitudinal stretching, the infrared heating method is advantageous in terms of the process because the temperature of the hot roll in contact with the coating material is low. Further, the horizontal stretching (re-horizontal stretching) and the heat (fixation) treatment are performed again using a tenter-type stretching heat treatment apparatus. In the tenter-type stretching heat treatment apparatus, when the transverse stretching ratio is set to 1, the re-lateral stretching is not substantially performed, and only the heat setting treatment is performed.

A longitudinal stretching device, a transverse stretching device,
As can be understood from the above, a conventionally known apparatus can be used as the re-longitudinal stretching apparatus, the final heat treatment apparatus, and the like.

In the present invention, the transverse stretching ratio is preferably 2 times or more, more preferably 2.5 times or more, and particularly preferably 3 times or more. However, when re-horizontal stretching is performed, the above ratio can be determined in combination with the re-horizontal stretching ratio. The upper limit of the transverse stretching ratio depends on the film properties, but is preferably 6 times or less, more preferably 5 times or less.

The magnification of the re-longitudinal stretching depends on the mechanical strength of the film and the like, but is preferably 2.0 times or more, more preferably 2.2 times or more. The upper limit of this magnification is preferably about 4.6 times. The first-stage longitudinal stretching ratio (predetermined ratio) is 1.5.
To 3.0 times, preferably 1.5 to 2.6 times.

[0019] The temperature of the final heat treatment is preferably selected from the range of 150 to 240 ° C, more preferably 170 to 230 ° C. This time is usually several tens of seconds or less. The stretching temperature can be selected from a conventionally known temperature range.

In the present invention, the primer aqueous coating solution is applied after the first-stage longitudinal stretching.
The temperature is 0 to 70 ° C, preferably 40 to 60 ° C. When the film forming temperature is 30 to 70 ° C., the coating film after application and lateral stretching becomes a flat and continuous film, and has a moderate heat resistance and a tough film that can withstand friction and stretching stress in the process. . However, when the film forming temperature is lower than 30 ° C., the heat resistance of the coating film is insufficient, and a problem occurs in that the coating film is transferred to a hot roll of vertical re-stretching. On the other hand, if this temperature exceeds 70 ° C,
At the time of coating and drying, the film forming property of the coating liquid is insufficient, the formed coating film becomes non-uniform, and the coating film has wavy folds. Further, when the film forming property is deteriorated, cracks of the coating film occur, and worm-like projections are formed. Due to the roughening of these coating films, the coefficient of friction between the easily contacting surface and the metal roll or nip roll during the process is increased, and film shaving is undesirably generated. In addition, film formation
The temperature is the lowest to form a coating with almost no cracking
Temperature.

The substantially water-insoluble polyester is a substantially linear polyester synthesized from a carboxylic acid or an ester-forming derivative thereof and a polyol or an ester-forming derivative thereof.

The carboxylic acid component of the polyester includes terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, Examples thereof include phenylindanedicarboxylic acid, phenylquinoxalinedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, and dimer acid. Two or more of these components can be used. Further, a small proportion of unsaturated polybasic acids such as maleic acid, fumaric acid, itaconic acid, and hydroxycarboxylic acids such as p-hydroxybenzoic acid and p- (β-hydroxyethoxy) benzoic acid may be used together with these components. it can. The proportion of the unsaturated polybasic acid component or hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less.

In order to introduce a sulfonic acid group into the polyester molecule, a sulfonic acid group-containing dicarboxylic acid, for example, 5-Na sulfoisophthalic acid, 5-ammonium sulfoisophthalic acid, 4-Na sulfoisophthalic acid,
Methyl ammonium sulfoisophthalic acid, 2-Na sulfoterephthalic acid, 5-K sulfoisophthalic acid, 4-K sulfoisophthalic acid, 2-K sulfoisophthalic acid, 5-N
a It is preferable to use an alkali metal sulfonic acid salt compound such as sulfosuccinic acid or an amine sulfonic acid salt compound.

The amount of the sulfonic acid group-containing dicarboxylic acid is preferably less than 0.5 mol% of the total carboxylic acid component. When the content of the dicarboxylic acid component is 0.5 mol% or more, the chargeability of the easy-contact layer increases, which is not preferable. This sulfonate group has a performance of enhancing the water dispersibility, and the range of ensuring the water dispersibility and the low chargeability is 0.003 to 0.4.
The content is preferably 5 mol%, more preferably 0.005 to 0.5%.
3 mol%.

The polyol component includes ethylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol, dimethylol Propionic acid, glycerin, trimethylolpropane,
Examples thereof include poly (ethylene oxide) glycol, poly (tetramethylene oxide) glycol, and the following bisphenol A derivatives. Two or more of these can be used.

[0026]

Embedded image

(Where R is H or CH ₃ and m + n =
2 to 10. ) The glass transition point (Tg) of this water-insoluble polyester is 50 to 100 ° C. Tg is 50 ° C
If it is less than 1, the film forming temperature of the water-insoluble polyester alone is low, the amount of the wetting agent used is limited to a small amount, the surface tension of the coating liquid is high, and cissing of the coating liquid film occurs on the polyester film. On the other hand, when Tg exceeds 100 ° C., the film-forming temperature of the water-insoluble polyester alone is too high, so that a large amount of a wetting agent is required to adjust the coating solution to the maximum film-forming temperature, and coating unevenness due to foaming of the coating solution, In addition, there is a disadvantage that the adhesiveness is reduced due to a decrease in the amount of the binder.

As the wetting agent for the coating liquid in the present invention, surfactants such as anionic surfactants, tikaon surfactants, and nonionic surfactants are preferable. For example, polyethylene oxide / polypropylene oxide block copolymers, Polyoxyethylene alkyl phenyl ether, polyoxyethylene-fatty acid ester, polyoxyethylene alkyl ether, sorbitan fatty acid ester, polyoxyethylene alkyl ether, sorbitan fatty acid, glycerin fatty acid ester, fatty acid metal soap,
Alkane sulfonates, alkyl sulfates, alkyl benzene sulfonates, alkyl sulfonates, alkyl diphenyl ether disulfonates, alkyl sulfosuccinates, quaternary ammonium chloride acids, alkyl amine salts and the like can be mentioned. Among these, nonionic surfactants are preferred. Further, ethylene oxide adducts of higher alcohols having 8 to 20 carbon atoms are preferable, and those having 11 to 15 carbon atoms are particularly preferable. The amount of the wetting agent is preferably 2 to 30% by weight, more preferably 3 to 20% by weight based on the total solids of the primer.

Further, as long as the effects of the present invention are not lost, for example, an antistatic agent, an ultraviolet absorber, a pigment, an organic filler, an inorganic filler, a lubricant, a blocking inhibitor,
Other additives such as melamine, epoxy, aziridine and other crosslinking agents and (meth) acrylic resins, polyester resins,
Either a polyurethane resin or the like alone or a blend can be mixed.

The ring and ball softening point of the coating is preferably 120 ° C. or higher. Further, it is preferable that this coating film has a stretch-following property at the time of re-stretching. Therefore, it is preferable that the elongation of the primer coating film is 100% or more at 120 ° C., more preferably 150% or more. When the ring and ball softening point of the coating film is lower than 120 ° C., the coating film is undesirably transferred to a hot roll. On the other hand, if the elongation of the coating film is too small, the coating film will break and fall off during re-stretching, and a phenomenon in which the falling-off material adheres and accumulates on the guide roll will occur, which is not preferable.

The solid content of the aqueous coating solution is usually 30% by weight.
Or less, and more preferably 10% by weight or less. The amount of coating is preferably 0.5 to ²⁰ g, more preferably 1 to 10 g, per m ² of the running film.

As a coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be applied alone or in combination.
The aqueous coating liquid may contain a small amount of an organic solvent for the purpose of assisting the stability of the coating liquid or the coatability of the coating liquid.

The longitudinally stretched polyester film coated with the aqueous coating solution is dried and led to processes such as transverse stretching, re-longitudinal stretching, and heat setting. For example, a longitudinally stretched polyester film coated with an aqueous coating solution is guided to a stenter, and is horizontally stretched, re-longitudinal stretched, and thermally fixed. During this time, the coating solution dries and forms a continuous film on the film. Drying may be performed before or during the transverse stretching.

The thus obtained high-strength polyester film having a primer layer has high strength characteristics and various coatings such as cellophane ink, magnetic paint, and the like.
High adhesion to a very wide range of paints such as electrophotographic toner compositions, chemical matte paints, diazo paints, and UV inks, especially strong adhesion to magnetic paints, and low chargeability in the process. It shows good blocking resistance without sticking without heat transfer or scraping trouble.

[0035]

The present invention will be further described below with reference to examples. In the examples, “parts” means “parts by weight”. Each characteristic of the film was measured by the following method.

1. Adhesiveness A paint for evaluation is applied to the primer-coated polyester film with a Mayer bar so that the thickness after drying becomes about 4 μm, and dried at 100 ° C. for 3 minutes. Thereafter, aging was performed at 60 ° C. for 24 hours. 600 (3
M company) (12.7 mm wide and 15 cm long) were adhered so as not to contain air bubbles, and JIS C2701 (197
5) Using a manual load roll as described above, bring the tape into close contact, and cut it out into a tape width. The strength when this is peeled 180 degrees is measured. [Evaluation paint] 25 parts of urethane resin Nipporan 2304 (manufactured by Nippon Polyurethane) 50 parts of vinyl chloride / vinegar resin Esrec A (manufactured by Sekisui Chemical) 1 part of dispersant Ratio P (manufactured by RIKEN Vitamin) Magnetic agent CTX- 860 500 parts (manufactured by Toda Chemical Co., Ltd.) are dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to make a 40% solution, and dispersed by a sand grinder for 2 hours. Thereafter, 25 parts (in terms of solid content) of coronate L as a cross-linking agent are added and stirred well to obtain a magnetic paint.

2. Blocking property 10 after matching the front and back of the polyester film
cm × 15 cm square, and a weight of 50 kg / cm ² was applied thereto at 50 ° C. in an atmosphere of 50% RH for 17 hours.
Then, the peel strength of this 10 cm width is measured. The peeling speed at this time is 100 mm / min.

3. Glass transition point of polyester (Tg) The glass transition point is measured using SSC / 580DS type DSC manufactured by Seiko Denshi Kogyo. Approximately 10 mg of the sample is sealed in an aluminum voltter, and the temperature is once increased to 100 ° C. by DSC, then gradually cooled, and then cooled to 0 ° C., and then the main measurement is started.
The temperature was raised at a rate of 10 ° C./min, and the calorific value change was measured up to 100 ° C., and Tg was determined from the intersection of the tangents of the two curves in FIG.

4. Thermal transferability and thermal shaving during thermal stretching The film before re-longitudinal stretching is sampled, and the thermal transferability during thermal stretching is evaluated using the thermal stretching tester shown in FIG. That is, the film before re-longitudinal stretching is set in the unwinder 1 of FIG. 2, and the film is guided to a hot roll 2 heated to 120 ° C. and having a surface speed of 5 m / min, and then water having a surface speed of 11 m / min. Then, the film is stretched between the roll 3 and the roll 3 which is cooled by the winder 4. After this stretching is continued for 1 hour, the surface of the hot roll 2 (thermal transferability and heat-sharpability) in contact with the primer layer and the surface of the nip roll 6 (heat-sharpability) of the cooling roll 3 are observed to determine the presence or absence of a transferred material. Check and evaluate according to the following criteria. There are no transcripts on the surface ... ○ Some transcripts are observed on the surface… 表面 A large amount of transcripts are observed on the surface… ×

5. Charging property A primer-coated polyester film having a width of 400 mm and a length of 3000 m was immersed in a 60% RH atmosphere at 23 ° C. in an amount of 200 m /
In a minute, Hughry Electronics Co., Ltd.'s M
The exfoliation charge amount (average value) is measured using an odel-230 type static electricity measuring device.

6. Coating liquid film forming temperature A hot plate of a thermal gradient tester HG-100 type of Toyo Seiki Co., Ltd. was set at 30 to 80 ° C. every 5 ° C., and a cover glass was placed on the hot plate and left for 2 minutes. 3w solid from dropper
The t% of the coating solution was about 0.3g dropped onto a glass, the open system at the lowest temperature to form almost no cracks coating the coating film dried finished the 1 hour coating solution at each temperature film forming Temperature.

7. Ring and ball softening point The coating liquid is dried to prepare a dried product of an aqueous binder and a wetting agent, and the softening point is measured according to JIS K-2531-1960. Glycerin is used for the heating bath, and the temperature is raised at a rate of about 5 ° C./min.

[Examples 1 to 5 and Comparative Examples 1 and 2] Polyethylene terephthalate (containing a lubricant) having an intrinsic viscosity of 0.65 was dried at 170 ° C for 3 hours, and then dried at 280 ° C on a rotating cooling drum maintained at 20 ° C. It was melt-extruded to obtain a 150 μm thick unstretched film, and then stretched 2.0 times vertically in one step by an infrared heater method. Then, the aqueous primer liquid (solid content: 3 wt%) shown in Table 1 was stretched in a kiss coat method to one time vertically stretched film. Was coated at a rate of 5 g / m ^{2 on} one side. Continue 105
The film was stretched 3.9 times in the transverse direction at a temperature of 120 ° C., then the film was heated to 120 ° C. with a hot roll, and the second-stage longitudinal stretching (re-longitudinal stretching) was performed at a stretching ratio of 2.8 times by the speed difference between two sets of nip rolls. Then, heat setting was performed at 215 ° C. for 6 seconds. At this time, the film thickness was 10 μm, and the thickness of the final primer layer was 0.015 μm. Table 2 shows the characteristics of this film.

Comparative Example 3 A plain re-stretched film was obtained in the same manner as in Example 1 except that the primer solution was not applied. Table 2 shows the characteristics of this film.

[0045]

[Table 1]

However, the symbols in Table 1 are as follows. TA; terephthalic acid IA; isophthalic acid QA; naphthalenedicarboxylic acid K ₂ ; 5-sodium sulfoisophthalic acid EG; ethylene glycol BPA-P; propylene oxide adduct of bisphenol-A (4 mol) DEG; diethylene glycol SAA-1; Nonion NS208 manufactured by Yushi Co., Ltd.
5 SAA-2; C ₁₂ H ₂₅ O (CH ₂ CH ₂ O) ₉ H (linear) SAA-3; C ₁₄ H ₂₉ O (CH ₂ CH ₂ O) ₇ H (branched) SAA-4; Newpole PE-10 manufactured by Kasei Corporation
8

[0047]

[Table 2]

As is evident from Table 2, the low chargeability of the present invention
The easily-adhesive polyester film is free from thermal transfer during re-longitudinal stretching and scraping during the process, and is excellent in adhesiveness, blocking property and charging property.

[0049]

According to the present invention, various coatings applied to a polyester film, such as offset ink, gravure ink, silk screen ink, UV, can be obtained without thermal transfer of the coating film or scraping during the manufacturing process. ink,
Excellent adhesion to magnetic paints, especially magnetic paints, adhesives, electrophotographic toners, chemical mat paints, diazo paints, hard coat paints, UV paints, heat sealability-imparting compositions, inorganic film-forming substances, etc. It is also possible to provide a method for producing a low-charge / easily-adhesive polyester film having a primer layer having no tackiness and low chargeability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of Tg measurement from a calorie change curve of DSC.

FIG. 2 is a schematic diagram of a hot stretching tester for evaluating the transferability of a primer layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unwinder 2 Heating roll 3 Cooling roll 4 Winder 5, 6 Nip roll

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sadami Miura 3-37-19 Koyama, Sagamihara-shi, Kanagawa Prefecture Inside the Sagamihara Research Center, Teijin Limited (72) Tomoki Nakamura 77-77 Kitayoshida-cho, Matsuyama-shi, Ehime Teijin Limited Matsuyama Office (56) References JP-A-6-293068 (JP, A) JP-A-4-173228 (JP, A) JP-A-4-235019 (JP, A) JP-A-2-229838 (JP, A) JP-A-5-179032 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 55/02-55/16 C08J 7/04 CFD B32B 27/36

Claims (1)

(57) [Claims] 1. A water-insoluble polyester having a glass transition point of 50 to 100 ° C. and a sulfonic acid group-containing dicarboxylic acid component of less than 0.5 mol% as a carboxylic acid component on at least one surface of a longitudinally stretched polyester film. A coating liquid containing a wetting agent as a main component and having a film forming temperature of 30 to 70 ° C. is applied, then dried and stretched in the horizontal direction, and further stretched in the vertical direction. And then heat-fixed.
A method for producing an easily adhesive polyester film.