JPH03124737A - Easily adherable polyester film - Google Patents

Abstract

PURPOSE:To prepare the title film excellent in the adhesive properties and useful for packaging and industrial use by coating at least one side of a polyester film before the completion of orientation and crystallization with a coating liq., and then drying, orienting and thermally treating the coated film. CONSTITUTION:At least one side of a polyester film (e.g. a polyethylene terephthalate film) before the completion of orientation and crystallization is coated with a coating liq. contg. a polyethyleneimide (deriv.) (e.g. polyethyleneimine), and then the coated film is dried, oriented, and thermally treated to give the title film.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an easily adhesive polyester film, and more specifically to a base material for forming packaging and industrial laminated films such as printing and laminating. The object of the present invention is to provide a polyester film which is useful as a polyester film and has excellent adhesive properties.

(Prior Art) It is known to melt, extrude, and form a film from a thermally processable polyester such as polyethyl/nterephthalate or a copolymer thereof. The biaxially stretched polyester film obtained in this way has superior heat resistance, gas barrier properties, electrical properties, and chemical resistance compared to films made of other resins, so it is widely used as a packaging material. ing. However, polyester film has a high melting point (thermal adhesion between 11 pieces is accompanied by shrinkage and deformation of the film, making it practically impossible.

Therefore, in order to improve these drawbacks, resins with easy heat sealability such as vinyl acetate resin and vinyl chloride resin are used.
1-f can be coated or laminated with a film such as polyethylene or polypropylene.

Furthermore, before coating with a heat seal layer, activation treatment by discharge treatment such as corona, arc, or plasma, and a method of brimer treatment of aqueous polyacrylic ester, polyurethane, or polyester are available.

However, in the heat-sealable laminate produced in this way, the adhesive strength between the heat-sealable resin and the polyester film layer is not necessarily sufficient, and the adhesive strength between the heat-sealable laminate and the base material is not necessarily sufficient, especially when the heat-sealable laminate is bonded to the base material by hot water treatment. The adhesive strength with the sealing layer is significantly reduced, making it unsuitable for packaging applications requiring hot water sterilization.

In addition, as a method that can withstand hot water sterilization, there is a method in which a solvent-soluble polyurethane resin and a cross-linking agent such as polyisocyanate are applied to a biaxially stretched polyester film, dried, and then subjected to Agereg treatment after lamination, but this method is extremely expensive. There are some drawbacks, such as the film being sloppy.

(Problems to be Solved by the Invention) The present invention solves the problem of insufficient adhesion, especially after hot water treatment, in the adhesion between the heat seal layer and the base film when laminating the heat seal layer on a polyester film. This is an attempt to solve the problem at a low cost.

(Means for Solving the Problems) As a means for solving these problems, a coating solution containing polyethyleneimine and/or a polyethyleneimine derivative is applied to at least one side of the polyester film before the oriented crystallization is completed. is applied, then dried, stretched,
This is achieved by using an easily adhesive polyester film that has been subjected to heat treatment.

In the present invention, the polyester constituting the polyester film is composed of dibasic acid residues and glycol residues,
Made of polyester.

At least 85 mol% of the dibasic acid is terephthalic acid or 2,6-naphthalene dicarboxylic acid, and the remaining 15 mol%
Other dibasic acids in mol% droplets include isophthalic acid, biphenyldicarboxylic acid, adipic acid, etc. Glycol components include aliphatic acids such as ethylene glycol, propylene glycol, trimethylene glycol, and tetramethylene glycol. Glycols can be used.

In the present invention, the polyester film before the completion of crystal orientation refers to the above-described polyester resin melt-extruded,
It was made into a film. An unstretched film or an unstretched film oriented in either the machine direction or the transverse direction - an axially stretched film, and a film that is stretched at a low magnification in two directions, the machine direction and the transverse direction (final This includes a biaxially stretched film A) before being re-stretched in the longitudinal or transverse direction to complete oriented crystallization. Further, the polyethyleneimine used in the present invention is prepared by subjecting ethyleneimine to i11 autopolymerization using a conventional method.・Polyethyleneimine derivatives are copolymerized using ethyleneimine according to a conventional method, or derived using polyethyleneimine.Such derivatives include, for example, aldehydes, ketones, alkyl halides, and ethyleneimine. Examples include reaction products of polyethyleneimine with compounds selected from the group consisting of cyanate compounds, epoxy compounds, guanidines, urea, various acids and acid anhydrides, and graft products with vinyl compounds.

The solvent for preparing the coating solution in the present invention may be any solvent as long as it dissolves polyethyleneimine or a polyethyleneimine derivative and is chemically inert with these solutes. However, in consideration of safety, water is Most effective. Furthermore, in consideration of coating stability on the film and drying workability, aliphatic alcohols such as methyl alcohol and ethyl alcohol are used alone as a solvent,
These solvents can also be mixed with water to form a solvent.

The concentration of the coating liquid is usually 30% by weight or less, preferably 10% by weight or less.

The coating liquid prepared in this manner may contain, for example, aqueous polyurethane, polyamide, polyester, polyacrylic acid, etc., within a range that does not eliminate the effects of the present invention.
Resins such as esters, aqueous polyisocyanate compounds, polyepoxy compounds, crosslinking agents such as methylolmelamine and dimethylolethylene urea, antistatic agents,
Additives such as ultraviolet absorbers, pigments, organic fillers, inorganic fillers, lubricants, and anti-blocking agents can be mixed.

It is necessary to apply the coating liquid to one or both sides of the polyester film before crystal orientation is completed in the polyester film production frame. In particular, it is preferable for this method to coat a uniaxially stretched polyester film using a roll stretching method, and then immediately stretch it in a direction perpendicular to the previous stretching direction without drying it properly or without drying it, and then heat treat it. According to this method, it becomes possible to dry the coating layer along with stretching. In addition, the reason why this extremely good effect is obtained is that during stretching, there is a kind of anchor effect between the film and the primer layer.
It is thought that a stronger interface is formed between the two layers.

Any known coating method can be applied as a method for applying the coating liquid in the present invention. For example, roll coating method, gravure coating method, roll plush method, spray coating method,
It is best to apply an air knife coating method or the like or in combination.

Coating of the primer layer formed in the present invention
41.0.005 to 1.0 g/rl is preferable, and 0.01 to 5 g/rl is more preferable. Coating layer is 0
．． If it is less than 0.005g/♂, coating spots and film breakage are likely to occur during stretching, and if it is less than 1.0g, blocking will occur or the abrasion resistance of the primer layer will decrease, so it is preferable. do not have.

Conditions for orientation and crystallization of the polyester film, such as stretching, heat setting, etc., can be those conventionally accumulated in the art. Further, activation treatment such as corona discharge or arc discharge may be performed before or after coating the polyester film.

Heat-sealable resins used for the coated surface of polyethyleneimine or/and its derivatives of the film thus obtained include polyolefin resins such as polyethylene, polypropylene, and copolymers thereof, polyvinyl chloride, polyvinylidene chloride, etc. Examples include, but are not limited to, halogen-containing resins, rubber resins such as polybutadiene and polyisoprene, and polyvinyl ester resins such as polyvinyl acetate, modified products thereof, and copolymers thereof.

In order to maximize the effects of the present invention, polyolefin resins are preferred. Also, the lamination method with these resins has sufficient adhesive strength! j. Any method is fine if it is done, but
Preferably, extrusion lamination is used.

Next, examples and comparative examples will be shown.

Beer strength in Examples and Comparative Examples was determined by the method described below.

[Method for measuring beer strength] Polyethylene (
Sumitomo Chemical σ Gradient Pressure Sen L705) was laminated by extrusion lamination without using a contact layer.

The beer strength of the polyethylene and base material of this laminate that had been heat treated at 95° C. for 30 minutes and the untreated one were measured and are shown in Table 1.

Example 1 (1) Preparation of coating solution Polyethyleneimine ([1 catalyst 1'! Epomin P-1
A polyethyleneimine treatment solution was prepared by diluting 18 parts by weight of 000 (solid content: 30%) with a mixed solvent of 411 parts by weight of water and 41 parts by weight of isopropyl alcohol.

■ Manufacture of inline coated film J12 Polyethylene terephthalate with an intrinsic viscosity of 0.63 containing 700 ppm of silicon dioxide with an average particle size of 0.5 is melt-extruded at 280°C to 300°C, cooled with a cooling roll at 15°C, and thickened. An unstretched film with a diameter of 120 μm was obtained, and this unstretched film was stretched 3.5 times in the vertical direction between a pair of rolls at different circumferential speeds at 85° C., and the treatment solution prepared in (1) was applied using an air knife method. , dried with hot air at 70°C, then stretched 3.5 times in the transverse direction at 98°C with a tenter, and further heat-set at 200-210°C to obtain a thickness of 12μ and a coating layer of 0.
A biaxially stretched coating film of 0.05 g/♂ was obtained.

Comparative Example 1 A biaxially stretched polyester film was produced from the polyester produced in (1) in Example 1 by omitting the coating step.

WNI is applied to this polyester film using the air knife method.
Polyethyleneimine (Nippon Shokubai T) 11 Epomin P100O) was applied so that N7t was 0.05 g/♂ to obtain a coach film.

Comparative Example 2 The coating liquid was made of polyethylene resin (Toho Chemical ■Hitic S-
A biaxially raised film was obtained in the same manner as in Example 1, except that the film was changed to 3121).

Comparative Example 3 A biaxially stretched film was obtained in the same manner as in Example 1, except that the coating liquid was changed to a polyurethane resin (Dai [1 ink, 1 ink, Hytran HW340)].

Comparative Example 4 Except that the coating solution was changed to a 4:1 (weight 111 ratio) mixture of polyurethane resin (Dainippon Ink A-Jun Hytran HW340) and melamine crosslinking agent (Human [1 Ink 1'J:J Beckamine JIOI) A two-wheel stretched film was obtained in the same manner as in Example 1.

Comparative Example 5 A biaxially stretched film was obtained in the same manner as in Example 1, except that the coating liquid was changed to a polyester resin (Toyobo 01 Pyronal MDI200).

Example 2 The same procedure as in Example 1 was carried out except that 11,000 pp of silicon dioxide particles having an average particle size of 0.5 mm were added to the coating solution based on polyethyleneimine.

Example 3 The same procedure as in Example 1 was carried out except that 5% ethyl acrylate grafted polyethyleneimine was used instead of polyethyleneimine.

Example 4 The same procedure as Example 1 was carried out, except that in Example 2, 5% of glycerin triglycidyl ether (an epoxy crosslinking agent manufactured by Nagase Kasei Co., Ltd.) was added to polyethyleneimine.

Examples 5 to 6 In Example 4, Elastron E-37 (No. 1 T', manufactured by 1 company, block polyisocyanate-based crosslinking agent) and Beckamire JI were used instead of glycerin triglycidyl ether.
The same procedure as in Example 4 was carried out except that OI (melamine crosslinking agent manufactured by Ippon Ink Co., Ltd.) was used instead.

As shown in Table 1, the present invention exhibits extremely good adhesive strength before and after hot water treatment.

On the other hand, when polyethyleneimine was applied to a monobiaxially stretched film (Comparative Example 1), it had good adhesive strength before hot water treatment, but did not reach a practical level after hot water treatment.

In addition, when polyethylene (Comparative Example 2), polyurethane (Comparative Example 3), polyurethane combined with a melamine crosslinking agent (Comparative Example 4), and polyester were used as other resins for the brimer, almost no adhesion was observed before and after hot water treatment. It turns out that there is no gender.

Below is a margin table ■ Beer strength g / 15 mm (effects of the invention) The thus obtained polyester film with a primer layer solves the problems in conventional heat seal coating and lamination. It is found that the laminate is extremely useful for packaging applications and industrial applications that require heat resistance to provide sufficient adhesion during hot water treatment of the laminate.

Claims (1)

[Claims] An easily adhesive polyester film, characterized in that a coating solution containing polyethyleneimine and/or a polyethyleneimine derivative is applied to at least one side of the polyester film before oriented crystallization is completed, and then dried, stretched, and heat treated. .