JPH05320391A - Easily adhesive polyester film improved in electrostatic property and its production - Google Patents

Abstract

PURPOSE:To provide an easily adhesive polyester film free from troubles (e.g. ignited explosion or the adhesion of dust) caused by static electricity in its processing treatments and excellent in the adhesion to magnetic coatings, printing inks, etc. and to provide the method for producing the polyester film. CONSTITUTION:The easily adhesive polyester film improved in the electrostatic property is characterized by disposing a primer layer comprising a composition containing (1) an easily adhesive polyester resin, (2) an antistatic agent having a sulfonic acid group and/or its metal salt group in the molecule and (3) an acidic compound having at least one free carboxyl group or phenolic hydroxyl group on at least one side of a polyester film, and the method for producing the film by an in-line coating method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easy-adhesive polyester film having an improved charging property and a method for producing the same, and more particularly, to an obstacle caused by static electricity generated during the production of magnetic tapes, OHP films, magnetic cards, etc. The present invention relates to a polyester film which is free from flammable explosion, dust adhesion, etc. and has excellent adhesiveness to magnetic paints, printing inks, etc., and a method for producing the same.

[0002]

2. Description of the Related Art Thermoplastic polyesters such as polyethylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene naphthalate or copolymers thereof, or blends thereof with a small proportion of other resins. The polyester film obtained by melt-extruding, is biaxially stretched, and then heat-fixed is excellent in mechanical strength, heat resistance, chemical resistance and the like, and is used in various industrial fields. However, since its surface is highly crystallographically oriented, there is a problem that it is poor in acceptability of paints, adhesives, inks and the like.

Therefore, as a method for improving the adhesiveness, physical treatment such as corona treatment, ultraviolet treatment, plasma treatment, EB treatment or flame treatment, or chemical treatment such as alkali, amine aqueous solution, and trichloroacetic acid phenols is used. The process 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 in which an easily adhesive coating film is applied to the surface of the film to form a primer layer by a process other than the usual polyester film forming process. However, in this method, it is difficult to say that an organic solvent is usually used as a solvent for the coating material, and the coating atmosphere is sufficiently clean.Therefore, frequent occurrence of surface defects of processed products due to adhesion of dust, or environmental problems caused by organic solvents. There are safety and hygiene problems such as deterioration.

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

Aqueous resins such as polyester resins, polyurethane resins and acrylic resins are known as water-based coating agents used for the primer treatment. These aqueous resins are
In order to develop into an aqueous solvent, hydrophilic groups such as sulfonic acid metal salts and carboxylates have been introduced into the polymer molecule, and the static electricity presumed to be caused by the electrical characteristics of these hydrophilic groups It has a drawback that it is easily generated and the charging property is increased.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide various coatings such as offset inks, gravure inks and silk screen inks which are free from electrostatic damage such as ignition and explosion and dust adhesion and which are applied to polyester films. , UV ink, magnetic paint, gelatin composition, adhesive,
Primer having excellent adhesion to magnetic paints, such as electrophotographic toners, chemical matte paints, diazo paints, hard coat paints, UV paints, heat-sealability imparting compositions, and inorganic film-forming substances, and having no tackiness. It is an object of the present invention to provide a polyester film having a layer and having an improved charging property, and a method for producing the same.

[0008]

The objects of the present invention are: On at least one side of the polyester film, (1) an easily adhering polyester resin, (2) an antistatic agent having a sulfonic acid group and / or a metal salt group thereof in the molecule, and (3) at least one free carboxyl group in the molecule. 1. An easily-adhesive polyester film having improved chargeability, characterized in that a primer layer of a composition containing an acidic compound having a phenyl group or a phenyl group is provided. (1) Easy-adhesive polyester resin on at least one side of the polyester film before crystal orientation is completed,
Aqueous coating of a composition containing (2) an antistatic agent having a sulfonic acid group and / or a metal salt group thereof in the molecule and (3) an acidic compound having at least one free carboxyl group or phenyl hydroxyl group in the molecule. Apply the liquid, then dry,
It is achieved by a process for producing an easily-adhesive polyester film with improved charging properties, which comprises stretching and further subjecting to heat treatment to complete oriented crystallization.

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-naphthalene dicarboxylate, and the like. A combination or a blend of these with a small proportion of another resin is also included.

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 externally added particles include silica, kaolin, calcium carbonate, calcium phosphate,
Titanium oxide and the like can be mentioned, and examples of the internally precipitated particles include those precipitated during the production of polyester by a combination of an alkali (earth) metal compound, a phosphorus compound and the like.

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 ℃)
Is preferably 0.45 to 0.9.

In the present invention, polyester is melt-extruded by a conventional method and rapidly solidified to obtain an amorphous unstretched film. Then, this unstretched film is first stretched in the machine direction and then stretched in the transverse direction. The stretching is carried out by running the film. As the stretching means in the longitudinal 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 usually performed at a magnification of 2.5 to 4.5 times. The transverse stretching (transverse stretching) is performed using a tenter type stretching heat treatment device. This stretching in the transverse direction is usually performed at a magnification of 2.5 to 4.5 times. Then 150-24
Heat treatment is performed at a temperature of 0 ° C. to complete the crystal orientation.

The stretching of the polyester film can be carried out by the simultaneous biaxial stretching method or the multi-stage stretching method (longitudinal-horizontal-longitudinal, longitudinal-horizontal-longitudinal-horizontal, longitudinal-longitudinal-horizontal, longitudinal-in addition to the above-mentioned sequential biaxial stretching method. You can also do it sideways-sideways etc.).

In the present invention, the easily-adhesive polyester resin (1) which is a component forming the primer layer is a substantially linear polyester synthesized from a polybasic acid or its ester-forming derivative and a polyol or its ester-forming derivative. Is.

As the polybasic acid component of this polyester, terephthalic acid, isophthalic acid, phthalic acid, 2,6-
Examples thereof include naphthalenedicarboxylic acid, phenylindanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid and dimer acid. Two or more kinds 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.

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 and poly (tetramethylene oxide) glycol. These can use 2 or more types.

The above polyesters are, for example, organic sulfonates, carboxylates, diethylene glycol,
Copolymers of hydrophilic group-containing compounds such as polyethylene glycol and polytetramethylene glycol are preferred because they are advantageous for preparing an aqueous dispersion. This carboxylic acid salt is usually charged with a trifunctional or higher functional carboxylic acid,
Since this carboxylic acid undergoes branching during the polymerization process and easily gels, it is desirable to reduce the copolymerization ratio.
In this respect, the introduction of a hydrophilic group using a sulfonate, diethylene glycol, polyalkylene ether glycol or the like is more advantageous because it does not cause a problem in the case of a carboxylate.

To introduce a sulfonate group into the polyester molecule, for example, 5-Nasulfoisophthalic acid, 5-ammoniumsulfoisophthalic acid, 4-Nasulfoisophthalic acid, 4-methylammoniumsulfoisophthalic acid, 2 -Na sulfoterephthalic acid, 5-K sulfoisophthalic acid, 4-K sulfoisophthalic acid, 2-K sulfoisophthalic acid, Na sulfosuccinic acid and the like sulfonic acid alkali metal salt-based compounds or sulfonic acid amine salt-based compounds can be used. preferable. The polyvalent carboxylic acid or polyhydric alcohol having a sulfonate group is 0.5 to 20 mol% in the total polyvalent carboxylic acid component or polyhydric alcohol component, and further 1
It is preferable to occupy -18 mol%.

Further, in order to introduce the carboxylic acid group into the polyester molecule, for example, trimellitic acid anhydride, trimellitic acid, pyromellitic acid anhydride, pyromellitic acid,
Compounds such as trimesic acid, cyclobutane tetracarboxylic acid, and dimethylol propionic acid can be used.
The carboxylic acid salt can be obtained by neutralizing the carboxylic acid with an amino compound, ammonia, an alkali metal or the like.

When introducing the hydrophilicity-containing compound into the polyester molecule, various known methods can be adopted. The case of introducing a carboxylate or organic sulfonate group will be further described. For example, a method of synthesizing a polyester using a compound having a carboxylate or organic sulfonate group in the molecule as one component of a starting material, and a molecule After synthesizing a polyester by using a compound having three or more carboxylates as one component as a starting material, the free carboxyl group in the polyester is converted to ammonia, amine,
There are methods such as a method of neutralizing the medium with an alkali metal compound or the like. The method will be further explained. For example, trimellitic anhydride was used as one component of the polyester raw material to prepare a polymer having a free carboxyl group in the side chain, and after the reaction was completed, ammonia water was added to neutralize the aqueous polyester. Can be built. The polyester is preferably produced by a melt polymerization method.

In the present invention, the antistatic agent (2) which is a component forming the primer layer is an antistatic agent having a sulfonic acid group and / or a metal salt group thereof in the molecule. Examples of the antistatic agent include dodecylbenzenesulfonic acid and its metal salts (Li, K, Na, etc.), octylsulfonic acid and its metal salts (Li, K, Na, etc.), oligostyrenesulfonic acid and its metal salts ( Li, K, Na, etc.), dibutylnaphthalenesulfonic acid and its metal salts (Li, K,
Na, etc.), metal salts of lauryl sulfosuccinate (Li, K, Na, etc.), polyallyl sulfonic acid and its metal salts (Li, K, Na, etc.), polyvinyl sulfonic acid and its metal salts (Li, K, Na) Etc.), alkyl diphenyl ether disulfonic acid and its metal salts (Li, K, N
a) and the like. More preferably, alkyl diphenyl ether disulfonic acid and its metal salt which have a large ratio of sulfonic acid groups and their metal bases per weight can be mentioned. These can also use 2 or more types.

In the present invention, the acidic compound (3) as a component forming the primer layer is an acidic compound having at least one free carboxyl group or phenyl hydroxyl group in the molecule. This compound has the effect of lowering the pH of the entire coating liquid, for example formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lauric acid, myristic acid, palmitic acid, stearic acid, other saturated monocarboxylic acids,
Acrylic acid, methallylic acid, crotonic acid, oleic acid, sorbic acid, linoleic acid, other unsaturated monocarboxylic acids and their (co) polymers, oxalic acid, malonic acid, adipic acid, azelaic acid, sebacic acid, other Aliphatic saturated dicarboxylic acids, maleic acid, fumaric acid, other aliphatic unsaturated dicarboxylic acids and their (co) polymers, benzoic acid, other aromatic monocarboxylic acids, phthalic acid, isophthalic acid, terephthalic acid, other Examples thereof include aromatic dicarboxylic acids, trimellitic acid, pyromellitic acid, trimesic acid, other aromatic polycarboxylic acids, tannic acid, pyrogallol, and other compounds having a phenolic hydroxyl group. Moreover, what acts as a carboxylic acid by hydrolyzing like an acid anhydride can also be used. More preferably, a polymer having a high proportion of free carboxyl groups per weight, a polymer of acrylic acid, a polymer of methacrylic acid, a copolymer of acrylic acid and methacrylic acid, butanetetracarboxylic acid and its dianhydride, pyromellitic acid. And dianhydride thereof.

In the present invention, the amount ratio of the above-mentioned easily adhesive polyester resin (1), antistatic agent (2) and acidic compound (3) is such that the total amount of these three components is 100% by weight and the component (1 ) Is 75% by weight or more, the sum of the components (2) and (3) is 10 to 25% by weight, and the component (3) is 5% by weight.
It is above, and it is preferable that the pH of the entire coating liquid is 2 to 5. When the ratio of the component (1) is less than 75% by weight, the easy adhesion property is insufficient and the blocking resistance is deteriorated.
When the sum of the component (2) and the component (3) is less than 10% by weight or the ratio of the component (3) is less than 5% by weight, the antistatic property is deteriorated.

The primer coating liquid in the present invention comprises the above-mentioned easily adhesive polyester resin (1) and antistatic agent (2).
The antistatic agent (2) often acts as a wetting agent, although it is a coating liquid of a composition containing the acid compound (3) and the acidic compound (3).
However, when the wettability of the coating liquid is insufficient, another surfactant can be used in combination. As the surfactant, for example, anionic surfactant, cationic surfactant, nonionic surfactant, etc. are preferable, and examples thereof include polyethylene oxide / polypropylene oxide block copolymer, polyoxyethylene alkylphenyl ether, polyoxyethylene. -Fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfosuccinate,
Examples thereof include quaternary ammonium chloride salt and alkylamine hydrochloric acid. The amount of this surfactant is preferably 1 to 30% by weight of the total solids of the primer,
It is more preferably 2 to 20% by weight.

Further, within a range where the effects of the present invention are not lost, for example, other antistatic agents, ultraviolet absorbers, pigments, organic fillers, inorganic fillers, lubricants, antiblocking agents, crosslinking agents such as melamine, epoxy, aziridine, etc. Other additives can be mixed.

The solid content concentration of the primer coating liquid (aqueous coating liquid) is usually 30% by weight or less, more preferably 10% by weight or less. The coating amount is preferably 0.5 to ²⁰ g, 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. This 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 primer coating solution may be applied to the polyester film having crystal orientation completed, but it is preferable to apply it to the polyester film before crystal orientation is completed, and particularly to a longitudinally stretched polyester film. It is preferable to do so. When the primer coating liquid is applied before the roll lengthwise stretching, heat resistance that withstands roll stretching is required.

The longitudinally stretched polyester film coated with the aqueous coating solution is dried and then subjected to steps such as lateral stretching and heat setting. For example, a longitudinally stretched polyester film coated with an aqueous coating solution is introduced into a stenter and laterally 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 low-charge, easily-adhesive polyester film having the primer layer thus obtained is used for various coatings such as ink for cellophane, magnetic paint, gelatin composition, toner composition for electrophotography, chemical matte coating, It exhibits high adhesion to a wide variety of paints such as diazo paints and UV inks, particularly strong adhesion to magnetic paints, and good blocking resistance without tackiness.

[0031]

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 evaluation coating material 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. After that, aging was performed at 60 ° C. for 24 hours, and then Scotch tape No. 600
(3M), 12.7 mm wide and 15 cm long, were adhered to prevent air bubbles from entering and JIS C2701 (197)
5) Using a manual load roll as described in (1), bring it into close contact, and cut it into a tape width. The strength when peeled 180 degrees is measured.

[Evaluation paint] Urethane resin Nipporan 2304 25 parts (manufactured by Nippon Polyurethane) PVC / vinegar resin S-REC A (manufactured by Sekisui Chemical) 50 parts Dispersant Recion P (manufactured by RIKEN VITAMINS) 1 part in terms of solid content Magnetic agent CTX-860 (manufactured by Toda Kagaku Co., Ltd.) (500 parts) is dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to prepare a 40% solution, which is then dispersed in a sand grinder for 2 hours. Thereafter, 25 parts of Coronate L (as solid content) as a cross-linking agent is added and stirred well to obtain a magnetic coating material.

2. Blocking property 5cm after the front and back of the polyester film are aligned
Cut into a 10 cm square, apply a load of 6 kg / cm ² for 17 hours in an atmosphere of 50 ° C. and 70% RH, and then cut this 5 cm
Measure the peel strength of the width. The peeling speed at this time is 1
It is 00 mm / min.

3. Antistatic Polyester film coated with primer on one side (10 μm x
A roll (500 mm × 3000 m) is rewound at a speed of 150 m / min in an atmosphere of 23 ° C. × 75% RH and 23 ° C. × 40% RH, and the peeling charge of the roll is measured.

[0036]

Examples 1 to 7 and Comparative Examples 1 to 4 Intrinsic viscosity is 0.65
Polyethylene terephthalate (containing lubricant) at 170 ℃
2 hours on a rotating cooling drum kept at 20 ° C after drying for 3 hours.
It is melt extruded at 80 ° C. to obtain an unstretched film having a thickness of 150 μm, and then longitudinally stretched 3.8 times by an infrared heater method, and then the aqueous primer solution (solid content 4 wt%) in Table 1 is longitudinally stretched film by a kiss coat method. Wet 2g / m ^{2 on} one side of
Was applied. Subsequently, the film was stretched 3.9 times in the transverse direction at 105 ° C., and then heat set at 215 ° C. for 6 rows. At this time, the film thickness was 10 μm, and the thickness of the final primer layer was 0.02 μm. The characteristics of this film are shown in Table 2.

[0037]

Comparative Example 5 A biaxially oriented film was obtained in the same manner as in Example 1 except that the primer liquid was not applied. The characteristics of this film are shown in Table 2.

[0038]

[Table 1]

However, the symbols in Table 1 are as follows. TA: terephthalic acid IA: isophthalic acid QA: 2,6-naphthalenedicarboxylic acid K _2: 5-sodium sulfoisophthalic acid Na salt EG: Ethylene glycol C ₄ G: 1,4-butanediol BPA-2: Ethylene bisphenol A Oxide adduct (2 mol) BPA-4: Bisphenol A ethylene oxide adduct (4 mol)

[0040]

[Table 2]

As is apparent from Table 2, the polyester film of the present invention has low chargeability, and also has excellent adhesiveness and blocking resistance.

[0042]

INDUSTRIAL APPLICABILITY According to the present invention, a low chargeability that does not cause various troubles due to static electricity is maintained, and further, offset ink, gravure ink, silk screen ink, UV ink, magnetic paint, gelatin composition, adhesive, electronic Primer layer with excellent adhesiveness and non-adhesiveness especially for magnetic toners such as photographic toners, chemical matte paints, diazo paints, hard coat paints, UV paints, heat sealability imparting compositions, and inorganic film forming substances. It is possible to provide a low-chargeable, easily-adhesive polyester film having the following properties and a method for producing the same.

Claims (2)

[Claims] 1. A polyester film having (1) an easily adhesive polyester resin, (2) an antistatic agent having a sulfonic acid group and / or a metal salt group thereof in the molecule, and (3) at least one molecule in at least one surface of the polyester film. An easily-adhesive polyester film having improved chargeability, characterized in that a primer layer of a composition containing one acidic compound having a free carboxyl group or a phenyl hydroxyl group is provided. 2. An (1) easy-adhesive polyester resin on at least one side of a polyester film before completion of crystal orientation, (2) an antistatic agent having a sulfonic acid group and / or a metal salt group thereof in a molecule, and ( 3) Applying an aqueous coating solution of a composition containing an acidic compound having at least one free carboxyl group or phenyl hydroxyl group in the molecule, followed by drying, stretching and heat treatment to complete the oriented crystallization. A method for producing an easily-adhesive polyester film having improved charging property.