JPH07144361A - Production of low charge and easy adhesive polyester film - Google Patents

Abstract

PURPOSE:To provide a low charge and easy adhesive polyester film not causing the thermal transfer of a film or the shaving thereof in a film producing process and having excellent adhesion and low charge properties to the coating substance of every kind applied to the film, for example, magnetic coating. CONSTITUTION:A water-based coating soln. based on water-insoluble polyester having a glass transition point (Tg) of 50-100 deg.C and containing below 0.5mol% of a sulfonate-containing dicarboxylic acid component per a dicarboxylic acid component and having filming temp. of 30-70 deg.C is applied to at least the single surface of a longitudinally oriented polyester film to be dried and the coated film is re-stretched longitudinally and re-oriented laterally if necessary to be thermally fixed.

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 low-charge, easily-adhesive polyester film. More specifically, it has a low chargeability and does not cause thermal transfer or abrasion during the process and has excellent adhesiveness. The present invention relates to a method for producing a high-strength polyester film which is coated with a primer layer exhibiting the following properties and is particularly useful as a base material for magnetic recording media.

[0002]

2. Description of the Related Art It is known that a thermoplastic polyester such as polyethylene terephthalate or a copolymer thereof, polyethylene naphthalate or a copolymer thereof, or a blend thereof with a small proportion of other resin is melt-extruded to form a film. Is. It is also known that the obtained biaxially stretched and heat-fixed polyester film is superior in heat resistance, gas barrier property, electrical property and chemical resistance to films made of other resins.

The above-mentioned polyester film is usually produced by a simple biaxial stretching method, that is, simultaneous or sequential stretching in the longitudinal and transverse directions, and then heat setting at high temperature. It is desired to further improve the strength of the polyester film depending on the application. Therefore, as a method for producing a high-strength polyester film, a method of biaxially stretching in the longitudinal and transverse directions and then longitudinal stretching again (re-longitudinal stretching method) Has been proposed (Japanese Patent Publication Sho 34-5)
887, Japanese Patent Publication No. 36-2258, etc.). In this re-longitudinal stretching method, for example, the polyester film after biaxial stretching is re-longitudinal stretched under the conditions of a stretching temperature of 80 to 180 ° C. and a stretch ratio of 1.2 times or more (in some cases, transverse stretching is further performed). The re-longitudinal stretched film has the advantage that the mechanical strength in the longitudinal direction is dramatically improved by 1.5 times or more as compared with a mere biaxially stretched film. Especially, a magnetic tape centered on a video tape. 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 is highly cohesive,
For example, the adhesiveness of paints, adhesives, inks, etc. is poor.

Therefore, as a method for improving this adhesiveness, physical treatment such as corona treatment, ultraviolet treatment, plasma treatment, EB treatment, flame treatment and the like, or chemical treatment such as alkali, amine aqueous solution, trichloroacetic acid phenols and the like Processing is known. However, these methods have practical disadvantages such as deterioration of adhesive strength with time and contamination of working environment due to volatilization of chemicals.

As another means, there is known a method of forming a primer layer by applying an easily-adhesive coating film on the surface of the film by a process other than the usual polyester film forming process. However, in this method, an organic solvent is usually used as the solvent for the coating agent, and since it is hard to say that the coating atmosphere is sufficiently clean, the occurrence of surface defects of processed products due to the adhesion of dust, or the environment caused by the organic solvent. There are safety and hygiene problems such as deterioration.

Therefore, if this primer treatment is carried out in a polyester film forming process using an aqueous coating agent, dust will not adhere in a clean environment, and an aqueous solvent will cause an explosion and a deterioration of the environment. It is advantageous in terms of film performance, economics and safety.

[0008]

DISCLOSURE OF THE INVENTION The inventor of the present invention, in order to achieve a low-charge and easy-adhesion property of a high-strength polyester film,
The easily adhesive primer coating solution used in the simple biaxial stretching method was applied after the first longitudinal stretching in the re-longitudinal stretching method,
It was clarified that the coating film was transferred to the hot roll during the second-stage longitudinal stretching (re-longitudinal stretching), and the re-stretching caused breakage and drop of the coating film. As a result of further study to eliminate such troubles, the present inventor found that the glass transition point (Tg) was 5
0 to 100 ° C. or higher and a dicarboxylic acid component of 0.
It has been found that the above problems can be solved by applying a coating liquid having a water-insoluble polyester having a sulfonic acid group-containing dicarboxylic acid component of less than 5 mol% and a wetting agent as a main component and having a film forming temperature of 30 to 70 ° C., The present invention has been reached.

The object of the present invention is that various coatings such as offset inks and gravure inks are applied to a polyester film without transfer or loss of the coating film during the manufacturing 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, easily-adhesive polyester film having a primer layer having excellent adhesiveness, no tackiness, and a low electrostatic property.

[0010]

The object of the present invention is, according to the present invention, to have a glass transition point (Tg) of 50 to 100 ° C. on at least one side of a longitudinally stretched polyester film.
And a water-insoluble polyester having a carboxylic acid group-containing dicarboxylic acid component of less than 0.5 mol% as a carboxylic acid component and a wetting agent as main components, and a film-forming temperature of 30 to 70.
The coating solution is applied at a temperature of ℃, then dried and stretched in the transverse direction, re-stretched in the longitudinal direction, if necessary, re-stretched in the transverse direction, and then heat set. This is achieved by a method of manufacturing a polyester film that is easily charged and easily adheres.

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

The linear saturated polyester in the present invention is
An agent that improves film properties, such as a lubricant, an antistatic agent, a colorant, a flame retardant, a light shielding agent, a stabilizer, and an ultraviolet absorber can be contained. The lubricant may be either internally precipitated particles or externally added particles, or may be a combination of two or more kinds. Examples of the externally added particles include silica, kaolin, calcium carbonate, calcium phosphate, titanium oxide, etc., and examples of the internally precipitated particles include a combination of an alkali (earth) metal compound, a phosphorus compound, etc., which are precipitated during polyester production. You can list things.

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

In the present invention, polyester can be melt-extruded by a conventional method and rapidly solidified to obtain an amorphous unstretched film. And this unstretched film is
First, the film is stretched in the machine direction and then in the transverse direction. These stretchings are performed by running the film. As the stretching means in the machine direction and the transverse direction, known means can be used. For example, the longitudinal stretching (longitudinal stretching) is performed by heating the unstretched film with a heating roll group and utilizing the peripheral speed difference between the low speed roll and the high speed roll. At that time, an infrared heater is preferably provided between the low speed roll and the high speed roll to heat the film to the stretching temperature, and the low speed roll may heat the film to the stretching temperature. This stretching in the machine direction is 1.5-
Perform at a magnification of 5.7 times. Also, stretching in the lateral direction (horizontal stretching)
Is performed using a tenter type stretching heat treatment apparatus. This transverse stretching is performed at a predetermined magnification when the transverse stretching is not performed again, but is performed at a lower magnification than the predetermined magnification (total stretching magnification) when the transverse stretching is performed again. The biaxially stretched film stretched also in the transverse direction is usually subjected to a heat (fixing) 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 direction and the transverse direction, and then subjected to heat (fixing) treatment. This re-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 process since the temperature of the heat roll with which the coating material comes into contact is lower. Further, the transverse stretching (re-transverse stretching) and the heat (fixing) treatment are performed again by using a tenter type stretching heat treatment apparatus. When the transverse stretching ratio is set to 1 in this tenter type stretching heat treatment apparatus, the case where the transverse transverse stretching is not substantially performed but only the heat setting treatment is performed is also an embodiment of the present invention.

A longitudinal stretching device, a lateral stretching device,
As the re-longitudinal stretching device, the final heat treatment device, etc., as known from the above, those conventionally known can be used.

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

The re-longitudinal stretching ratio depends on the mechanical strength of the film, 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 longitudinal stretching ratio (predetermined ratio) of the first stage is 1.5.
˜3.0 times, preferably 1.5 to 2.6 times.

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 the conventionally known temperature range.

In the present invention, the primer aqueous coating liquid is applied after the first stage longitudinal stretching, and the film forming temperature of this coating liquid is 3
It is 0 to 70 ° C, preferably 40 to 60 ° C. When this film forming temperature is set to 30 to 70 ° C., the coating film after coating and transverse stretching becomes a flat and continuous film, which has appropriate heat resistance and is 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 there is a problem that the coating film is transferred to the hot roll for re-longitudinal stretching. On the other hand, if this temperature exceeds 70 ° C,
During coating and drying, the film-forming property of the coating liquid is insufficient, the formed coating film becomes non-uniform, and corrugation occurs in the coating film. Further, when the film-forming property is deteriorated, the coating film is cracked and an earthworm-shaped projection is formed. Roughness of these coating films undesirably increases the friction coefficient between the easily contacting surface and the metal roll or nip roll during the process, causing film scraping.

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

The carboxylic acid component of this 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 phenylindane dicarboxylic acid, phenyl quinoxaline dicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, dimer acid and the like. Two or more of these components can be used. Further, a small proportion of an unsaturated polybasic acid such as maleic acid, fumaric acid or itaconic acid or a hydroxycarboxylic acid such as p-hydroxybenzoic acid or p- (β-hydroxyethoxy) benzoic acid may be used together with these components. it can. The ratio of the unsaturated polybasic acid component and the hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less.

To introduce a sulfonate group into the polyester molecule, a dicarboxylic acid containing a sulfonate group such as 5-Nasulfoisophthalic acid, 5-ammoniumsulfoisophthalic acid, 4-Nasulfoisophthalic acid, 4-
Methylammonium sulfoisophthalic acid, 2-Na sulfoterephthalic acid, 5-K sulfoisophthalic acid, 4-K sulfoisophthalic acid, 2-K sulfoisophthalic acid, 5-N
It is preferable to use a sulfonic acid alkali metal salt-based compound such as sulfosuccinic acid or a sulfonic acid amine salt-based compound.

The amount of the sulfonic acid group-containing dicarboxylic acid is preferably less than 0.5 mol% based on the total carboxylic acid components. When the content of this dicarboxylic acid component is 0.5 mol% or more, the chargeability of the easy-contact layer becomes high, which is not preferable. This sulfonate group has a property of enhancing water dispersibility, and as a range for ensuring water dispersibility and low chargeability, 0.003 to 0.4
5 mol% is preferable, and more preferably 0.005 to 0.
It is 3 mol%.

As the polyol component, 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. These can use 2 or more types.

[0026]

[Chemical 1]

(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 the above, 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, and therefore a large amount of a wetting agent is required to adjust the coating liquid to the maximum film-forming temperature, resulting in coating unevenness due to foaming of the coating liquid, Further, there is a drawback that the adhesiveness is lowered due to the decrease in the amount of the binder.

As the wetting agent for the coating liquid in the present invention, surfactants such as anionic surfactants, chicaone type surfactants and nonionic type 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,
Examples thereof include alkane sulfonate, alkyl sulfate, alkylbenzene sulfonate, alkyl sulfonate, alkyl diphenyl ether disulfonate, alkyl sulfosuccinate, quaternary ammonium chloride acid and alkyl amine acid salt. Of these, nonionic surfactants are preferable. Furthermore, 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, and more preferably 3 to 20% by weight based on the total solid content of the primer.

Further, within a range that does not impair the effects of the present invention, for example, an antistatic agent, an ultraviolet absorber, a pigment, an organic filler, an inorganic filler, a lubricant, an antiblocking agent,
Other additives such as crosslinking agents such as melamine, epoxy and aziridine, and (meth) acrylic resins, polyester resins,
A polyurethane resin or the like may be mixed alone or in a blend.

The ring and ball softening point of this coating film is preferably 120 ° C. or higher. Further, it is preferable that this coating film has stretch followability upon re-stretching. Therefore, it is preferable that the elongation of the primer coating film at 120 ° C. is 100% or more, further 150% or more. If the ring-and-ball type softening point of the coating film is lower than 120 ° C., the coating film is transferred to a hot roll, which is not preferable. On the other hand, if the elongation of the coating film is too small, the coating film may break and fall during re-stretching, and the fallen material may adhere to and accumulate on the guide roll, which is not preferable.

The solid content concentration of the aqueous coating solution is usually 30% by weight.
It is below, and more preferably 10% by weight or less. The coating amount is preferably 0.5 to ²⁰ g, and more preferably 1 to 10 g per 1 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 and a curtain coating method 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 stability of the coating liquid or coatability of the coating liquid.

The longitudinally stretched polyester film coated with the aqueous coating solution is dried and introduced into the steps of transverse stretching, re-longitudinal stretching, heat setting and the like. For example, a longitudinally stretched polyester film coated with an aqueous coating solution is introduced into a stenter and laterally stretched, re-longitudinal stretched and heat set. During this time, the coating solution is dried to form a continuous film on the film. Drying may be performed before or during transverse stretching.

The high-strength polyester film having the primer layer thus obtained has various characteristics such as high strength and various coating materials such as ink for cellophane, magnetic paint,
Shows high adhesion to a wide variety of paints such as electrophotographic toner compositions, chemical matte paints, diazo paints, UV inks, etc., especially strong adhesion to magnetic paints, and low chargeability within the process. It shows good blocking resistance with no stickiness and no thermal transfer or scraping problems.

[0035]

EXAMPLES The present invention will be further described below with reference to examples. In addition, "part" in an example means a "weight part." Each characteristic of the film was measured by the following method.

1. Adhesiveness The coating material for evaluation is applied to the primer-coated polyester film with a Meyer bar so that the thickness after drying is about 4 μm, and dried at 100 ° C. for 3 minutes. Then, it was aged at 60 ° C. for 24 hours, and then Scotch tape No. 600 (3
Adhesive with a width of 12.7 mm and a length of 15 cm so that air bubbles do not enter, and the top of this is JIS C2701 (197).
5) Level with a manual load roll described in (3), bring it into close contact, and cut into a tape width. The strength when peeled at 180 degrees is measured. [Evaluation paint] Urethane resin Nipporan 2304 25 parts (manufactured by Nippon Polyurethane) PVC / Vinyl acetate resin S-REC A 50 parts (manufactured by Sekisui Chemical) Dispersant Resion P 1 part (manufactured by RIKEN VITAMINS) Magnetic agent CTX- 860 500 parts (manufactured by Toda Kagaku Co., Ltd.) is dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to prepare a 40% solution, which is then dispersed by a sand grinder for 2 hours. After that, 25 parts (corresponding to solid content) of the cross-linking agent Coronate L is added and well stirred to obtain a magnetic coating material.

2. Blocking property 10 after putting the front and back of the polyester film together
Cut into squares of 15 cm × 15 cm, and apply a load of 50 kg / cm ² 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 Instruments Inc. Approximately 10 mg of the sample is enclosed in an aluminum bolter, the temperature is once raised to 100 ° C. by DSC, then gradually cooled and cooled to 0 ° C., and then the main measurement is started.
The temperature is raised at a rate of 10 ° C./min, the change in the amount of heat is measured up to 100 ° C., and Tg is obtained from the intersection of the tangents of the two curves in FIG.

4. Thermal Transferability and Heat Scrapability during Hot Stretching The film before re-longitudinal stretching is sampled and the transferability during hot stretching is evaluated by the hot stretching tester shown in FIG. That is, the film before re-longitudinal stretching was set in the unwinder 1 in FIG. 2, and this film was 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. It is stretched between the roll 3 and the roll 3 which is being cooled, and wound up by the winder 4. After this stretching was continued for 1 hour, the surface of the heat roll 2 (heat transfer property and heat abradability) and the surface of the nip roll 6 (heat abradability) of the cooling roll 3 which were in contact with the primer layer were observed to confirm the presence or absence of the transferred material. Examine and evaluate according to the following criteria. There is no transfer material on the surface ... ○ Some transfer material is observed on the surface ... △ A large amount of transfer material is observed on the surface ... ×

5. Charging property A primer-coated polyester film having a width of 400 mm and a length of 3000 m is 200 m / m in an atmosphere of 60% RH at 23 ° C.
Rewind in minutes, M of Hughli Electronics Co., Ltd.
The peeling charge (average value) is measured with an odel-230 type static electricity measuring device.

6. Coating liquid film forming temperature The heat plate of the thermal gradient tester HG-100 type of Toyo Seiki Co., Ltd. is set at 30 to 80 ° C. at an interval of 5 ° C., a cover glass is placed on the hot plate and left for 2 minutes, 3w solid from the dropper
Approximately 0.3 g of t% coating liquid was dropped on glass and the coating liquid was dried for 1 hour at each temperature in an open system, and the temperature at which a coating film with almost no cracks was formed was defined as the film-forming temperature. To do.

7. Ring and ball softening point The coating solution is dried to prepare a dry solid of an aqueous binder and a wetting agent, and the softening point is measured according to JIS K-2531-1960. Glycerin is used as the heating bath liquid, and the heating rate is 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 at 280 ° C. on a rotary cooling drum maintained at 20 ° C. The film is melt extruded to obtain an unstretched film having a thickness of 150 μm, then stretched by 2.0 times in the lengthwise direction by the infrared heater method, and then the aqueous primer solution (solid content 3 wt%) in Table 1 is stretched in the lengthwise direction by the kiss coat method. Was applied to one side of the above at a rate of Wet 5 g / m ² . Continued 105
The film is stretched 3.9 times in the transverse direction at ℃, then the film is heated to 120 ℃ with a hot roll and the second stage longitudinal stretching (re-longitudinal stretching) is performed at a stretching ratio of 2.8 times by the speed difference between two nip rolls. Then, heat setting was further performed at 215 ° C. for 6 seconds. At this time, the film thickness was 10 μm, and the final primer layer had a thickness of 0.015 μm. The characteristics of this film are shown in Table 2.

[Comparative Example 3] A re-longitudinal stretched film of a plain was obtained in the same manner as in Example 1 except that the primer solution was not applied. The characteristics of this film are shown in Table 2.

[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; Japan Nonion NS208. Made by Yushi Co., Ltd.
5 SAA-2; C ₁₂ H ₂₅ O (CH ₂ CH ₂ O) ₉ H (straight chain) SAA-3; C ₁₄ H ₂₉ O (CH ₂ CH ₂ O) ₇ H (branched) SAA-4; Sanyo New pole PE-10 manufactured by Kasei Co., Ltd.
8

[0047]

[Table 2]

As is clear from Table 2, the low charge of the present invention
The easily-adhesive polyester film does not have thermal transfer during re-longitudinal stretching or scraping in the process, and is excellent in adhesiveness, blocking property, and charging property.

[0049]

According to the present invention, various coatings such as offset inks, gravure inks, silk screen inks, UV coatings applied to a polyester film can be obtained without thermal transfer of the coating film or scraping in the manufacturing process. ink,
Excellent adhesion to magnetic paints, adhesives, electrophotographic toners, chemical matte paints, diazo paints, hard coat paints, UV paints, heat-sealability imparting compositions, inorganic film-forming substances, etc. Further, it is possible to provide a method for producing a low-charge, easily-adhesive polyester film having a primer layer which is not tacky and has low chargeability.

[Brief description of drawings]

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

FIG. 2 is a schematic view of a hot stretching test machine for evaluating the transferability of a primer layer.

[Explanation of symbols]

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

 ─────────────────────────────────────────────────── ─── Continued front page (72) Satomi Miura 3-37-19 Oyama, Sagamihara City, Kanagawa Prefecture, Sagamihara Research Center, Teijin Limited (72) Inventor, Tomoki Nakamura 77, Kitayoshida-cho, Matsuyama-shi, Ehime Prefecture Address: Teijin Limited, Matsuyama Office

Claims (1)

[Claims] 1. A water-insoluble polyester having a glass transition point of 50 to 100 ° C. and a carboxylic acid component containing less than 0.5 mol% of a sulfonic acid group-containing dicarboxylic acid component on at least one side 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 transverse direction, and further re-stretched in the longitudinal direction, and if necessary, re-stretched in the lateral direction. Low charge, which is characterized by performing heat fixing after that.
A method for producing an easily-adhesive polyester film.