JPS6049925A - Manufacture of container - Google Patents

Abstract

PURPOSE:To obtain a container having practically sufficient bonding strength by using a hot-melt adhesive and by subjecting the joint of PET films to a low- temperature plasma treatment. CONSTITUTION:In bonding the peripheral edge of a laminate whose at least one side is polyethylene terephthalate (PET) film A with the film A or the other side B of the laminate, the surface of at least the joint of the film is subjected to a low-temperature plasma treatment and then they are hot-bonded through a hot-melt adhesive layer. The hot-melt adhesive is composed of a modified polyethylene and polyolefin film, ethylene-vinyl acetate copolymer, etc., subjected to low-temperature plasma treatment. The bonding strength of the joint of the container having innermost face of PET is about 4kg/15mm. width.

Description

Detailed Description of the Invention The present invention relates to polyethylene terephthalate (hereinafter referred to as PET).
That's what it means. ) Relates to a method for producing a container having a film as the innermost surface.

Conventionally, food packaging containers have been made from a composite laminate of various plastics, paper, metal foil, etc.

There are bags or self-supporting containers whose peripheral edges are fused by heating and pressurizing, and those whose innermost surface is made of polyolefin resin, which has excellent hygiene and heat-sealability, are generally used. however.

Recently, flavor retention, which is presumed to be derived from polyolefin resins, has become a problem for some types of food and drink products. The present inventor attempted to manufacture a container whose innermost surface is made of PET film, which has no problems in flavor retention and hygiene, but since PET film has almost no heat sealability, a heat-fusible adhesive was used. It was found that sufficient adhesive strength could not be obtained even with this method.

Therefore, as a result of further research, the inventors of the present invention have found that by applying low-temperature plasma treatment to the surface of the part corresponding to the joint of the PET film, a heat-fusible adhesive can be used to create a container with sufficient adhesive strength for practical use. The present invention was completed based on the knowledge that this could be obtained.

That is, one aspect of the present invention is that the peripheral edge of a laminate having at least one surface made of a polyethylene terephthalate film (A) is formed between the films (A) or between the films (A) and the film (A).
and the other surface (B) of the laminate are bonded by heating and pressing with a heat-fusible adhesive layer interposed therebetween, thereby manufacturing a container having the film (A) as the innermost surface. The present invention provides a method for manufacturing a container, characterized in that the surface of at least the portion of the film (A) corresponding to the bonding portion is subjected to low temperature plasma treatment.

In the present invention, it is preferable to use a uniaxially or biaxially stretched PET film (A) from the viewpoint of strength.

Constituent materials other than PET film (A) of the laminate in the present invention include metals, especially aluminum foil or aluminum vapor deposited layer, saponified ethylene/vinyl acetate copolymer, polycarbonate, polyimide, polyolefin, polyvinylidene chloride, and Vinyl chloride, polyvinyl alcohol, polyamide.

Resins such as polystyrene and cellophane 1 Paper, non-woven fabric, etc. that have barrier properties against oxygen gas or moisture.

Depending on the purpose of strength, self-supporting properties, etc., suitable materials may be laminated by a known method such as heat seal lamination, extrinsic lamination, or using an adhesive.

However, when heat-sealing the film (A) and the other surface (B) of the 8-layer body, the material constituting the other surface (B) must be heat-sealable with the heat-sealable adhesive. 9 For example, polyolefins having carboxyl groups (hereinafter sometimes referred to as modified polyolefins) 2 surface treatment, especially low-temperature plasma treated polyolefins or PE
T film, metal layer.

In particular, there are aluminum foils, vapor-deposited layers, metal oxide vapor-deposited layers, etc.

In the present invention, heat-fusible adhesives include modified polyolefins, polyolefin films treated with low-temperature plasma, ethylene-vinyl acetate copolymers or unsaturated carboxylic acid or acid anhydride graft modified products thereof, polyamides, etc. be.

Modified polyolefins include ethylene, propylene,
Copolymerization or graft polymerization of olefins such as butene and α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, and maleic anhydride; β−
Graft-polymerized unsaturated carboxylic acids, etc., or these materials.

Furthermore, a metal compound was added. What is generally called an ionomer can also be used, and these can be used alone or in combination with an unmodified polyolefin. From the viewpoint of adhesive strength, the amount of the carboxyl group-containing unsaturated monomer is 0.01% by weight or more, preferably in the range of 0.1 to 10% by weight.

Furthermore, the conditions for low-temperature plasma treatment of the PE'T film are oxygen and argon at lX10=~l Torr.

Under conditions of a discharge value of 100 W or more in hydrogen, nitrogen or helium gas, or a mixed gas containing these.

The processing time is 0.1 seconds or more, preferably 1 second or more.

If the discharge value is set low or the treatment time is shortened, the adhesive strength may decrease.

In the present invention, the conditions for welding by heating and pressurizing are as follows:
It is above the softening temperature of the heat-fusible adhesive and below the melting temperature of the PET film (approximately 250°C).2For example, if the heat-fusible adhesive is mainly composed of low-density polyethylene, the temperature is about 1.
00℃ or higher, 11 for ethylene-vinyl acetate copolymer system
The temperature is preferably 0° C. or higher, about 135° C. or higher for those whose main component is high-density polyethylene, and about 160° C. or higher for those whose main component is polypropylene.

The conditions for pressurization are a linear pressure of 2 kg/cm or more, preferably in the range of 4 to 8 kg/am.

As described above, since the innermost surface of the container according to the present invention is made of PET film, there is no problem in flavor retention and hygiene, and depending on the selection of other materials constituting the laminate, the container can withstand retort sterilization. You can also do it.

The present invention will be explained in more detail below using Examples and Comparative Examples.

Example I PET film (Lumirror manufactured by Toshio Kiku, trade name, 125
An aluminum vapor deposition layer (approximately 500 layers) was formed on one side of μ), and lQu+Hg was formed on the other side using nitrogen gas.

After performing low temperature plasma treatment at 350W for 3 seconds.

Using a rectangular laminate in which a modified polypropylene (Liosen M-1063-4, trade name, manufactured by Toyo Ink Manufacturing Co., Ltd., Ltd., trade name) layer was formed on an aluminum vapor-deposited layer to a thickness of 40μ by the Extru-Silon method, a PE'r film was formed. Both ends were overlapped with the low-temperature plasma treated surface inside, and sealed into an envelope shape at 180°C for 2 seconds.

It was made into a cylindrical shape. On the other hand, using the same laminate as above, a dish-shaped body having a depth of 5 mm and a diameter equal to the inner diameter of the above-mentioned cylindrical body was produced by thermo-vacuum forming at 120° C. with the PET film inside.

The plate-shaped body was fitted onto the inner surface of the bottom of the cylindrical body, and dielectric heating was performed by a conventional method to thermally bond the body. The adhesive strength of this heat-sealed portion was approximately 4 kg/15 mm width.

Comparative Example 1 An attempt was made to obtain a cylindrical body in the same manner as in Example 1 except that the low-temperature plasma treatment of the PET film was omitted, but the adhesive strength of the heat-sealed portion was weak and a two-bag-shaped body could not be obtained. .

Example 2 PET film (same as Example 1)/polypropylene film (50μ)/saponified ethylene/vinyl acetate copolymer film (15μ)/polyethylene film (1
5μ) respectively, and two-wave type polyurethane adhesive (Toyo Morton@NA D-98OA, 980B).

Example 1
A container with the PET film surface as the inner surface was similarly produced by low-temperature plasma treatment in the same manner as above. The adhesive strength of this heat-sealed portion was approximately 3.51 (g/15+u).

Example 3 PET film (Lumirror manufactured by Toshio Kiku, trade name, 75μ
)/polypropylene film (100μ)/PET film (75μ) using an adhesive in the same manner as in Example 2. One side of the laminate was subjected to low-temperature plasma treatment in the same manner as in Example 1, and cut into rectangles. With the low-temperature plasma treated side of the PET film on the inside, a heat-sealable adhesive layer with a thickness of 5.
Using an adhesive film of modified polyamide (Meltron PAM, trade name manufactured by Diabond Industries) of 0μ, medium size, and adhesive film of 5 mm, both ends were overlapped by 5 mm and sealed at 180° C. for 2 seconds.

A flat container was obtained. The adhesive strength of this heat-sealed part is approximately 3
．． It was 5 kg/15 cranes.

Example 4 A TL, H composite film was obtained using a PET film (same as in Example 1) and a soft aluminum foil (30μ) with the same two-wave type polyurethane adhesive used in Example 2. On the other hand, composite films were prepared by coextruding polypropylene and the same modified polypropylene as in Example 1 to thicknesses of 50 μm and 10 μm, respectively.

The aluminum and polypropylene surfaces of the above two composite films were bonded together using the same urethane adhesive to obtain a laminate. The PET film surface of this laminate was subjected to low-temperature plasma treatment in ammonia gas at 10 Torr for 2 seconds, and a container having a PET film as an inner surface was prepared in the same manner as in Example 1. The adhesive strength of this heat-sealed part is approximately 4
The width was 715 kg (i+i).

Example 5 PET film (same as Example 3) with a thickness of about 50 mm on one side
An aluminum vapor deposited layer was formed on the vapor deposited layer, and modified polyethylene (Atomer LP-300, trade name manufactured by Mitsui Petrochemical Co., Ltd.) polypropylene and modified polyethylene were coated on this vapor deposited layer so that the thicknesses were 5μ, 70μ, and 10μ, respectively. A laminate was obtained by extrusion. The PET film surface of this laminate was subjected to low-temperature plasma treatment in air at 1 Q Torr for 2 seconds, and a container having a PET film as an inner surface was prepared in the same manner as in Example 1.

The adhesive strength of this heat-sealed part is approximately 4Kg/15n+m
It was wide.

Example 6 A container was prepared in the same manner as in Example 5, except that a mixture of equal amounts of nitrogen gas and hydrogen gas was used for the low-temperature plasma treatment. The adhesive strength was 4 Kg/15+u.

patent applicant Toyo Ink Manufacturing Co., Ltd.

Claims (1)

[Claims] l. At least one surface of the laminate is made of polyethylene terephthalate film (A).
A) or the film (A) and the other surface (B) of the laminate are bonded by heat and pressure with a heat-fusible adhesive layer interposed therebetween, with the film (A) being the innermost surface. The method for manufacturing a container, characterized in that the surface of at least the portion of the film (A) corresponding to the bonding portion is subjected to low-temperature plasma treatment in advance.