JPH05310975A - Readily bondable polyester film of improved electrostatic properties and its produciton - Google Patents

Abstract

PURPOSE:To obtain the polyester film which causes no static troubles on the magnetic tape productions and shows excellent adhesion to the magnetic coating by coating polyester film with a water-borne coating of a specific composition, before completion of orientation and crystallization. CONSTITUTION:A polyester film before completion of orientation and crystallization is coated on its at least one surface with a water-borne coating comprising (A) an aqueous polyester resin, (B) a polyether compound, preferably polyethylene glycol, and (C) an antistatic agent, preferably an alkyldiphenyl ether disulfonate. Then, the film is dried, drawn and heat-treated to complete the orientation and crystallization whereby the objective product having a primer layer of the composition containing components A, B and C. It is preferred that component A is a copolymer from an organic sulfonate such as 5-sodiosulfo- isophthalic acid, and a compound bearing hydrophilic groups such as diethylene glycol or polytetramethylene glycol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily-adhesive polyester film having an improved charging property and a method for producing the same, and more particularly to electrostatic damage (discharging ignition accidents) which occurs during the production of magnetic tape, chemical matte film and the like. The present invention relates to a polyester film which is free of adhesiveness and has excellent adhesiveness to magnetic paints, chemical matte paints and the like, 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 oriented and crystallized, there is a problem that it is poor in acceptability of paints, adhesives, inks and the like.

Therefore, as a method for improving this 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 and the like are used. Is known. However,
These methods have practical disadvantages such as deterioration of adhesive strength over 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, 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 a water-based coating agent, dust will not adhere in a clean environment, and the water-based solvent may cause an explosion or deterioration of the environment. It is advantageous in terms of film performance, economics and safety.

However, it is presumed that the easily adhesive polyester film obtained has different types of chemicals laminated on the surface of the base film, but it has the drawback that static electricity easily occurs and the chargeability is high. is doing.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide various coatings such as offset inks, gravure inks, silk screen inks, UV, which are free from static electricity such as discharge ignition fire and which are applied to a polyester film.
Inks, magnetic paints, gelatin compositions, adhesives, electrophotographic toners, chemical matte paints, diazo paints, hard coat paints, UV paints, heat sealability imparting compositions, inorganic film forming substances, etc., especially excellent for magnetic paints Another object of the present invention is to provide an easily-adhesive polyester film having improved adhesion and improved chargeability, and a method for producing the same.

[0008]

The object of the present invention is to:
According to the present invention, a polyester film is provided with a primer layer of a composition containing (1) an aqueous polyester resin, (2) a polyether compound and (3) an antistatic agent on at least one surface of the polyester film. Of a highly adhesive polyester film having improved properties, and a composition containing (1) an aqueous polyester resin, (2) a polyether compound and (3) an antistatic agent on at least one side of the polyester film before the completion of oriented crystals It is achieved by a method for producing an easily-adhesive polyester film with improved chargeability, which comprises applying an aqueous coating solution, followed by drying, stretching, and heat treatment to complete oriented crystallization.

The polyester constituting the polyester film in the present invention 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 or blends of these with small proportions of other resins are 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 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
C) is preferably 0.45 to 0.9.

In the present invention, a polyester is melt-extruded by a conventional method and then cooled and 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, in the longitudinal stretching (longitudinal stretching), an unstretched film is heated with a heating roll group,
This is done by using 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 transverse stretching is usually 2.
Perform at a magnification of 5 to 4.5 times. Then, heat treatment is performed at a temperature of 150 to 240 ° C. to complete the oriented crystallization.

In addition to the above sequential biaxial stretching method, the polyester film may be stretched by simultaneous biaxial stretching method or multi-stage stretching method (length-width-length, length-width-length-width, length-length-width, length). -side-
Horizontal, etc.) can also be used.

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

As the polybasic acid component of this polyester, terephthalic acid, isophthalic acid, phthalic acid, 2,6-
Naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid,
Pyromellitic acid, dimer acid, etc. can be illustrated. 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. The introduction of the carboxylic acid salt is usually 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 the hydrophilic group-containing compound is introduced 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 for synthesizing a polyester using a compound having a carboxylate or organic sulfonate group in the molecule as one component of a starting material, A method of synthesizing a polyester using a compound having three or more carboxylic acid salts therein as one component of a starting material, and then neutralizing free carboxyl groups in the polyester with ammonia, amine, alkali metal compound or the like into a medium; There is a way. 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 polyether compound (2) as the primer layer forming component is, for example, polyethylene glycol, polypropylene glycol, polyethylene glycol / polypropylene glycol copolymer (block type, random type), polyethylene glycol / polypropylene glycol copolymer (block). , Random type) lower alkyl ethers, self-polymers of aliphatic epoxy compounds, and the like. Among these, polyethylene glycol, polyethylene glycol / polypropylene glycol block copolymer, polyethylene glycol / polypropylene glycol random copolymer ether of glycerin, and polyethylene glycol can be preferably mentioned.

The weight average molecular weight of the polyether compound, particularly polyethylene glycol, is 500 or more, preferably 1000 to 50,000.

In the present invention, the antistatic agent (3) as a primer forming component is preferably an anionic antistatic agent, and of these, a sodium sulfonate type is preferred. Among them, alkyl diphenyl ether disulfonates (lithium, sodium, potassium, etc.) are preferable in terms of action and effect. Since such an antistatic agent also lowers the surface tension of the water-based coating liquid, a wetting agent for coating the polyester film is often unnecessary. However, if the antistatic agent lacks the ability to reduce the surface tension, a surfactant may be used in combination. The amount of the surfactant is preferably 1 to 30% by weight, and more preferably 2 to 30% by weight based on the total solid content of the primer.

In the present invention, the amount ratio of the aqueous polyester resin (1), the polyether compound (2) and the antistatic agent (3) is 75% by weight of the aqueous polyester resin (1) when the total amount thereof is 100% by weight. As described above, the total amount of the antistatic agent (3) is 10% by weight or more, and the total amount of the polyether compound (2) and the antistatic agent (3) is preferably 15 to 25% by weight. Water-based polyester resin (1)
Is less than 75% by weight, the adhesiveness is insufficient, the amount of the antistatic agent (3) is less than 10% by weight, or the total amount of the polyether compound (2) and the antistatic agent (3) is 15% by weight
If it is less than the above range, the antistatic property is poor, and especially in a low humidity atmosphere.

Further, other additives such as an ultraviolet absorber, a pigment, an organic filler, an inorganic filler, a lubricant, an antiblocking agent, and a crosslinking agent such as melamine, epoxy, aziridine, etc. may be added within a range in which the effects of the present invention are not lost. Can be mixed.

The solid content of the aqueous coating liquid 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, 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 application of the aqueous coating liquid may be carried out during the production process of the polyester film, or may be carried out on the polyester film which has been subjected to the biaxial orientation treatment. Among them, it is preferable to carry out during the production process of the polyester film, and further to the longitudinally stretched polyester film. However, when the primer is applied before the roll lengthwise stretching, heat resistance that is excellent in roll stretching is required.

After the application of the aqueous coating liquid, a primer layer is formed by a drying treatment, but when the oriented crystallization of the polyester film is not completed, for example, a vertically stretched polyester film coated with the aqueous coating liquid is used. Is dried and introduced into steps such as transverse stretching and heat setting. The longitudinally stretched polyester film coated with the aqueous coating liquid is guided to, for example, 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 the examples, "part" means "part by weight". 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, it was aged at 60 ° C for 24 hours, and then scotch tape No. 600 (3
(Manufactured by M Co.) 12.7 mm in width and 15 cm in length are adhered so that air bubbles do not enter, and this is leveled and brought into close contact with a manual load roll described in JIS C2701 (1975), and cut 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 Co., Ltd.) 50 parts Dispersant Recion P (manufactured by Riken Vitamin) 1 part Magnetic Agent CTX-860 (manufactured by Toda Kagaku) 500 parts

Is dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to prepare a 40% solution, which is dispersed by a sand glider for 2 hours. After that, 25 parts (corresponding to solid content) of Coronate L as a cross-linking agent is added and well stirred to obtain a magnetic coating material.

2. Blocking property 5cm after the front and back of the polyester film are aligned
Cut into 10 cm squares, apply a load of 6 kg / cm ² for 17 hours in an atmosphere of 50 ° C. and 70% RH, and then
Measure the peel strength of cm width. The peeling speed at this time is 100 mm / min.

3. Antistatic film coated on one side with primer (10μm x 500mm x 3)
000 m) roll at 23 ° C x 75% RH and 23 ° C x 4
The roll was rewound at a speed of 150 m / min in an atmosphere of 0% R, and the peeling charge of the roll was measured by a digital test electrical measuring instrument Model-manufactured by Hugle Electronics Co., Ltd.
Measure using 203.

[0038]

Examples 1 to 6 and Comparative Examples 1 and 2 Intrinsic viscosity of 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 in the transverse direction by 3.9 times at 105 ° C, and then heat set at 215 ° C for 6 seconds. At this time, the film thickness was 10 μm, and the thickness of the final primer layer was 0.02 μm. The characteristics of this film are shown in Table 2.

[0039]

Comparative Example 3 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.

[0040]

[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 EG; ethylene glycol BPA-4; bisphenol-A ethylene oxide adduct (4 mol) PEG1000; molecular weight 1000 Polyethylene glycol PEG 20000; polyethylene glycol with a molecular weight of 2000 PEG 50,000; polyethylene glycol with a molecular weight of 5000

[0042]

[Table 2]

As is clear from Table 2, the polyester film of the present invention has a low charging property, and in particular, has a low charging property at low humidity as well as an excellent adhesive property and blocking property.

[0044]

INDUSTRIAL APPLICABILITY According to the present invention, various coatings, such as offset inks and gravure inks, which have low chargeability even under low humidity and which are applied to polyester films,
Silk screen inks, UV inks, magnetic paints, gelatin compositions, adhesives, electrophotographic toners, chemical matte paints, diazo paints, hard coat paints, UV paints, heat sealability imparting compositions, inorganic film forming substances, etc. It is possible to provide a low-charge, easily-adhesive polyester film having a primer layer that exhibits excellent adhesiveness to a magnetic paint and has no tackiness, and a production method.

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Claims (2)

[Claims] 1. A charging property characterized in that a primer layer of a composition containing (1) an aqueous polyester resin, (2) a polyether compound and (3) an antistatic agent is provided on at least one surface of a polyester film. An improved, easy-adhesive polyester film. 2. An aqueous coating solution of a composition containing (1) an aqueous polyester resin, (2) a polyether compound, and (3) an antistatic agent is applied to at least one surface of a polyester film before the completion of oriented crystals. Next, a method for producing an easily-adhesive polyester film with improved charging properties, which comprises drying, stretching and heat treatment to complete oriented crystallization.