JP2000301675A - Laminate and sealed container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the deep draw forming, provide superior heat resistance, oxygen gas barrier properties, mechanical strength and the like and enable laminatation on a paper by forming a laminate out of a polypropylene layer, a bonding resin layer, a gas barrier layer and an ethylene copolymer layer of specified bonding strength with the paper. SOLUTION: At least four layers formed of a polypropylene layer, a bonding resin layer, a gas barrier layer and an ethylene copolymer layer of bonding strength with a paper of 150 g/15 mm width or more (180 deg. release, 300 mm/min. release speed) are laminated together. The melt index (JIS K6758) of a propylene of the polypropylene layer is preferably 0.1-10. As the bonding resin, a maleic anhydride modified propylene is preferred. As the gas barrier layer, an ethylene- vinyl alcohol copolymer is preferred. As the ethylene copolymer layer, a terpolymer composed of an ethylene of little odor, an acrylic ester and a maleic anhydride is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a film and a container for food packaging which can be formed by deep drawing such as pressure forming and can be bonded to paper, and have heat resistance, oxygen gas barrier properties, and transparency. The present invention relates to a multilayer film having excellent properties and mechanical strength, a multilayer container obtained by bonding the film to paper, and a sealed container.

[0002]

2. Description of the Related Art In the food industry, foods undergo quality deterioration due to various kinds of deterioration such as loss of shape, color, taste, and aroma due to temperature, moisture, oxygen, light rays, microorganisms such as bacteria and mold in the distribution process. Conventionally, as a method of preserving without causing deterioration of the quality until the food is consumed by a consumer, a method of directly adding additives such as a preservative and an antioxidant to food has conventionally been adopted. However, in recent years, in the food processing industry, regulations on additives for food have become strict, and the amount of additives used has been reduced or almost eliminated. Under these circumstances, as a method for ensuring long-term storage of contents, use of a packaging material having excellent oxygen gas barrier properties has been performed.
As a plastic material conventionally used as a packaging material for these contents, there has been a container formed from a relatively thick plastic sheet. On the other hand, as a flexible packaging material using a relatively thin plastic film, there was a multi-layer film bag-like packaging material called a retort pouch, but recently, a deep drawing molding machine has been used for the purpose of speeding up and automation of packaging. Packaging materials that can be packaged at a high speed by using such materials have been required. Further, in the transportation stage in the food distribution process, there is a problem that a bag is broken depending on the transportation method, and a film having excellent mechanical strength is required. In view of the above, plastic films as packaging materials required in such fields have multiple functions such as deep drawability, oxygen gas barrier properties, transparency, and mechanical strength, and are inexpensive. Also, cheap ones are required. In order to satisfy these requirements, it is conceivable that the film has a laminated structure of several layers in terms of performance, and that various functions are dispersed in each layer so as to have many functions comprehensively. In order to obtain such a film,
Conventionally, a method of laminating individual films by a dry laminating method or the like has been used, but it has to be selected from a single-layer film having a limited thickness and performance, and when the number of layers increases, In addition to the increase in cost, it was difficult to obtain a satisfactory product such as generating a solvent odor during molding. Further, in recent years, from the viewpoint of resource saving and environmental consideration, there has been a strong demand for synthetic resin products, particularly for packaging products having a large amount of use, to have low capacity and easy disposal. For this reason, various types of composite containers in which a synthetic resin film and a paper body such as paperboard are bonded have been proposed in the past, but none of them have satisfied the above-mentioned problems and the strength of bonding to paper.

[0003]

The object of the present invention is that deep drawing can be performed, heat resistance, oxygen gas barrier properties, and mechanical strength are excellent, and it can be laminated on paper as a support. It is to provide a laminate.

[0004]

According to the present invention, a polypropylene layer (A), an adhesive resin layer (B), a gas barrier layer (C), and an adhesive strength to paper (180 ° peeling, peeling speed 300 mm / min.) Is a laminate comprising at least four layers in the order of an ethylene-based copolymer layer (D) having a width of 150 g / 15 mm or more, and the resin (A)-
(B)-(C)-(B)-(A)-(D) in order to improve the adhesive strength.
(B)-(C)-(B)-(A)-(B)-(D). Preferably, the thickness of the ethylene-based copolymer layer (D) is 5 μm or more, the adhesive resin layer (B) is made of a modified polyolefin-based resin, and the gas barrier layer (C) is made of an ethylene-vinyl alcohol copolymer. It is a laminate. Further, a multilayer container in which the laminated body of each constitution described above and paper are adhered on the (D) layer surface, and furthermore, the container is made of a plastic having as a sealing layer a thermoplastic resin which can be thermally fused with at least polypropylene. It is a sealed container heat-sealed with a laminated lid.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polypropylene layer (A) of the present invention
Index of polypropylene used for JIS (JIS
K6758) is preferably from 0.1 to 10, more preferably from 0.5 to 7. It is also possible to blend 3 to 20 parts by weight of polyethylene in consideration of moldability.
In addition to polyethylene, a blend of a thermoplastic resin such as an unsaturated carboxylic acid-modified polyolefin or ethylene vinyl acetate is also possible as long as it is not taken on a hot platen during shaping. Also, for the purpose of increasing the heat resistance of the polypropylene layer (A),
By blending a homopolymer type cyclic polyolefin resin, it is possible to prevent the resin from being taken into a hot plate during shaping.

The adhesive resin used in the adhesive resin layer (B) of the present invention is not particularly limited, but maleic anhydride-modified polypropylene is an ethylene-vinyl alcohol copolymer and polypropylene, both of which have good adhesiveness. preferable. Further, an ethylene copolymer layer (D) may be used instead of (B).

As the resin used for the gas barrier layer (C) of the present invention, an ethylene-vinyl alcohol copolymer is preferable, and the ratio of commercially available ethylene can be selected from among 20 to 50 mol% according to the purpose. .

The ethylene copolymer layer (D) of the present invention comprises:
It is used because it has a low melting point and is excellent in low-temperature heat sealability, and includes ethylene-vinyl acetate copolymer, low-density polyethylene, ionomer, etc.
A terpolymer of ethylene, acrylic acid ester and maleic anhydride having low odor is preferred. Also, the adhesive strength between the resin and paper (180 degree peeling, peeling speed 300 mm
/ Min.) Requires a width of 150 g / 15 mm or more. It is also possible to mix thermoplastic resins such as polyethylene and polypropylene within a range that does not impair the adhesive strength. If the adhesive strength is less than this, there is a possibility that the adhesive layer between the layer (D) and the paper will be broken and the function as the container will not be satisfied if the lid is sealed and opened in the container in which the laminate is formed. is there. The ethylene-based copolymer resin layer (D) is 5 μm
The above is required for the adhesive strength to paper.
0g / 15mm width (180 ° peeling, 300mm / min
Peeling). If it is less than 5 μm, sufficient adhesive strength may not be obtained.

The laminated lid having a thermoplastic resin having a heat-fusing property with the polypropylene of the present invention as a sealing layer may be formed of a homo-, block-, or random polypropylene, a mixture of polypropylene and polyethylene, A vinyl acetate copolymer, a carboxylic anhydride-modified polypropylene, and a mixture, and the like, may be used as long as heat sealing with a container is possible.In some cases, in order to impart easy-opening properties, In order to adjust the heat sealing strength, a thermoplastic resin having no heat-fusing property with another polypropylene can be mixed within a range that does not impair the fusion with the polypropylene layer on the container side.
As a layer other than the sealing layer of the lid material, as a gas barrier layer,
Ethylene vinyl alcohol copolymer, vinylidene chloride copolymer, polyester, nylon or aluminum foil on which aluminum or inorganic silica is deposited can be used. Further, as the base material layer, any thermoplastic resin film such as polyester, nylon, stretched polypropylene, cellophane and the like can be used. However, since there is a possibility that these base films come into direct contact with the metal hot platen, it is necessary to take into consideration the releasability from the metal during heating. These seal layer, gas barrier layer, and base material layer can be laminated by a dry lamination method, a co-extrusion method, an extrusion lamination method, or the like. Even if the number of laminated layers is three or more, there is no problem.

[0010] The laminate of the present invention comprises
It can be obtained by coextrusion, lamination, or the like. As the lamination, any method such as coextrusion lamination, dry lamination, and thermal lamination can be used. The multilayer container of the present invention can be obtained by mounting a paper substrate in a mold and thereafter vacuum-forming or pressure-forming the laminate of the present invention. The paper base material used in the present invention is not particularly limited, and examples thereof include paperboard for paper containers, white paperboard, yellow balls, chip balls, and cup base paper. The sealed container of the present invention can be obtained by placing the container and the plastic laminated lid in a receiving mold, and pressing the flange portion with a heated hot plate.

[0011]

The present invention will be described with reference to the following examples, which are illustrative only and do not limit the present invention. Table 1 shows the layer structure, the oxygen gas barrier value, the adhesive strength to paper, and the temperature at which the laminate was attached to the hot platen of the laminates of the examples and comparative examples. The laminate was prepared by a co-extrusion method. The resins used in the examples and comparative examples are as follows. (A): Homopolypropylene (Sumitomo Noblen F
H1016 (Sumitomo Chemical Co., Ltd.) (A-1): Homopolypropylene (Sumitomo Noblen)
FH1016 (manufactured by Sumitomo Chemical Co., Ltd.); 80% by weight, cyclic polyolefin (Zeonor 1420R (Nippon Zeon)
20 wt% blend. (A-2): Ethylene-random copolymerized polypropylene (Sumitomo Noblen S131 (manufactured by Sumitomo Chemical Co., Ltd.)) (B): Maleic anhydride-modified polypropylene (Adtex ER313E, manufactured by Nippon Polyolefin Co., Ltd.) (C) : Ethylene-vinyl alcohol copolymer (EVAL J102B, manufactured by Kuraray Co., Ltd.) (D): Ethylene-acrylate-maleic anhydride terpolymer (Lexpearl ET182, manufactured by Nippon Polyolefin Co., Ltd.)

Each measuring method is as follows. (1) Oxygen gas barrier property; by OXTRAN method. (2) Adhesive strength between laminate and paper;
Heated at 0 ° C. for 2 to 3 seconds, molded and adhered to the inside of paper blanks (cup base paper) placed in a mold, 15 mm
A sample piece having a width was prepared, and the laminate and the paper blank were peeled at 180 ° at a tensile speed of 300 mm / min, and the maximum load was recorded. (3) Adhesion temperature to a hot plate; a 20 mm × 50 mm aluminum heat seal plate was brought into contact with the polypropylene layer (A) side of the laminate at 140 ° C. and 4 kgf / cm 2,
The time until removal to the heat seal board occurred was measured.

Next, the laminates of Example 1 and Comparative Example 1
A multi-layer container is formed by shaping a paper blank (cup base paper) having a rectangular parallelepiped shape of 2 cm × 16 cm × 3.5 cm so that the paper layer is on the outside of the container. Ethylene vinyl copolymer (15μ
m), nylon (15 μm), and polyethylene terephthalate (12 μm) were laminated by a dry lamination method to produce a sealed container sealed with a thermoplastic plastic lid.
Table 2 shows the gas barrier values of this sealed container.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

The laminate according to the present invention has a deep drawability,
It has excellent oxygen gas barrier properties, mechanical strength, etc., and is particularly suitable for packaging containers formed by bonding to paper. Further, the multilayer container obtained by the present invention can easily be sealed with a plastic film lid, and also has good gas barrier properties, which is an index of storage stability.

Continued on the front page F term (reference) 3E086 AD01 BA04 BA14 BA15 BB01 BB22 BB41 CA01 4F100 AK01B AK03B AK04D AK07A AK64 AK69C AK80 AL01D AL06B AR00C BA04 BA05 BA10A BA10D BA10E BA25D DG10J16J01 J01 GB01

Claims (7)

[Claims] 1. A polypropylene layer (A), an adhesive resin layer (B), a gas barrier layer (C), and an adhesive strength (180) with paper.
Peeling, peeling speed 300mm / min.) Is 150g / 1
A laminate comprising an ethylene-based copolymer layer (D) having a width of 5 mm or more. 2. Adhesion strength (180) between a polypropylene layer (A), an adhesive resin layer (B), a gas barrier layer (C), and paper.
Peeling, peeling speed 300mm / min.) Is 150g / 1
Consisting of an ethylene copolymer layer (D) having a width of 5 mm or more,
(A)-(B)-(C)-(D), (A)-(B)-
(C)-(B)-(A)-(D) or (A)-
A laminate characterized by being laminated in the order of (B)-(C)-(B)-(A)-(B)-(D). 3. An ethylene-based copolymer layer (D) having a thickness of 5
The laminate according to claim 1, wherein the thickness is at least μm. 4. The laminate according to claim 1, wherein the adhesive resin layer (B) is made of a modified polyolefin resin. 5. The laminate according to claim 1, wherein the gas barrier layer (C) comprises an ethylene-vinyl alcohol copolymer. 6. The laminate according to claim 1, wherein the laminate comprises paper (D).
Multi-layer container bonded at the layer surface. 7. A sealed container, wherein the multilayer container according to claim 6 is heat-sealed with a plastic laminated lid having a thermoplastic resin having at least heat-fusibility with polypropylene as a sealing layer.