JPH05169603A - Multilayer oriented film - Google Patents

Abstract

PURPOSE:To manufacture a multilayer film of improved resistance to bag breakage and resistance to pinholes of a packaging material for a product being low temperature distributed in the foodstuff field and demonstrating sufficiently barrier properties and the like provided with the packaging material. CONSTITUTION:A multilayer oriented film comprises anyone of polyamide resin layers (A) (A'), an ethylene-vinyl acetate copolymerization saponified layer (B), bonding resin layers (C), (C') (C'') and a seal layer (D), and its laminating order is (1) A-C-A', (2) A-C-B-A', (3) A-C-B-C'-A', (4) A-C-A'-C'-D, (5) A-C-B- A'-C'-D, or (6) A-C-B-C'-A'-C'-D.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention has a transparency, mechanical strength, gas barrier property, etc. which can be widely used in the packaging field such as a lid material by laminating it with a bag, a pillow package, a printed polyester film or a stretched polypropylene film. The present invention relates to an excellent multilayer stretched film.

[0002]

2. Description of the Related Art Packaging materials in the food field are required to have higher functionality due to diversification of lifestyles due to improvement of consumers' standard of living and gourmet orientation, and various packaging forms from individual packaging to commercial packaging. There is. For example, high oxygen gas barrier properties and water vapor barrier properties are required by reducing the amount of additives and changing heat sterilization conditions, etc. Packaging materials with excellent mechanical strength to prevent bag breakage in the distribution process due to the development of freezing and refrigerating distribution. Is required. Under such circumstances, it is indispensable for the packaging material to be able to satisfy a plurality of functions. Therefore, the packaging material has a multi-layered structure of several layers to disperse various functions in each layer. Further, in the case of a thin packaging material, a packaging material with high mechanical strength is basically required for applications such as bags, pillow packaging, lid materials, etc., except for forming such as deep drawing, and a stretched film is generally used. .

On the other hand, as a method for producing a multi-layered packaging material containing a stretched film, dry lamination, extrusion lamination, coating, vapor deposition and the like are used. However, in these methods, the layer construction is complicated in order to impart many functions. Therefore, there is a problem that the manufacturing process is increased and the cost is inevitably increased. Therefore, as a method for simplifying the process, multi-layer stretching for stretching a co-extruded film has been put into practical use. While the present inventors have been involved in packaging materials in the food field, the demand for packaging materials having excellent mechanical strength, particularly bag puncture resistance and pinhole resistance, has become stronger than before, and dry laminating, extrusion laminating and co-extrusion However, we tried to consider packaging materials, but couldn't make products that are satisfactory in terms of both performance and cost.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of various studies on film layer constitutions and production methods in response to the demand for a packaging material having particularly excellent bag-breaking resistance and pinhole resistance. It is an object of the present invention to provide a multilayer stretched film capable of stabilizing the quality by preventing bag breakage and pinholes in the distribution process of frozen / refrigerated products, which has recently been increasing in the food field.

[0005]

The present invention provides a polyamide resin layer (A) (A '), an ethylene-vinyl acetate copolymer saponified resin layer (B), an adhesive resin layer (C) (C').
(C '') or the sealing layer (D) is included, and the stacking order is (1) A-C-A ', (2) A-C-B-A', (3).
A-C-B-C'-A ', (4) A-C-A'-C'-
D, (5) A-C-B-A'-C'-D or (6) A
-C-B-C'-A'-C ''-D is a multilayer stretched film.

The polyamide resins (A) and (A ') used in the present invention may be the same resin or different. As the polyamide resin, generally known 6 nylon, 6-6 nylon, 6-10 nylon, 6-12
Nylon, 11 nylon, 12 nylon, and copolymers thereof, amorphous nylon, MXD6 nylon obtained by polycondensation of metaxylylenediamine and adipic acid, and blends thereof are used.

The ethylene-vinyl acetate copolymer saponified resin (hereinafter abbreviated as EVOH) (B) has an ethylene content of 2
5 to 75 mol%, and the degree of saponification with respect to vinyl acetate in the copolymer is 90% or more.

The adhesive resins (C), (C ') and (C'') may be the same resin or different. As the adhesive resin, polyethylene, polypropylene, copolymers of these copolymers and further different α-olefins, or ethylene-vinyl acetate copolymers with acrylic acid, methacrylic acid and other monobasic unsaturated fatty acids, Alternatively, an acid-modified olefin resin obtained by chemically binding an anhydride of a dibasic unsaturated fatty acid such as maleic acid, phthalic acid, or itaconic acid, that is, maleic anhydride is used.

The sealing layer resin (D) is low density polyethylene (LDPE), linear low density polyethylene (LLDP).
E), medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene (PP) and other polyolefin resins, and ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA) and ethylene-methyl methacrylate copolymer. Polymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EEA), ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MA)
H), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMMA), ionomer (ION) and other resins can be used.

The layer structure of the multi-layer stretched film of the present invention will be described in more detail. The adhesive resin layer of the multi-layer stretched film not only functions as the original adhesive layer, but also plays a more important role as a buffer against external impact. It is possible to exert the function of the belt. Therefore, if the adhesive resin layer is extremely thin, its function will not be sufficient. As a result of examining the thicknesses of various adhesive resin layers, the thickness ratio at which the function of the buffer zone is recognized is 5% or more with respect to the total thickness. To describe the method for producing a multilayer stretched film, the coextrusion method is desirable as the method for producing a raw film. A uniaxial stretching method and a biaxial stretching method are used in the subsequent stretching step.
As the biaxial stretching method, a tubular method and a flat method which are simultaneous biaxial stretching methods and a sequential biaxial stretching method are used. After stretching, heat treatment may be performed depending on the application.

[0011]

【Example】

(Example-1) Polyamide resin 1 / adhesive resin 1 / ethylene-vinyl acetate copolymer saponified resin / by coextrusion method
A film (total thickness 450 μm) having a layer structure of polyamide resin 2 / adhesive resin 1 / ethylene-vinyl acetate copolymer was prepared. When the thickness ratio of each layer was measured, it was 15/10/15/10/5/5/45 (%) in the order of the above layer constitution. The raw materials used for each layer were as follows. Polyamide resin 1: 6 Nylon (1030B manufactured by Ube Industries) and amorphous nylon (PA3426 manufactured by Mitsui Deyupon Polychemical) (blend ratio = 95:
5) Polyamide resin 2: 6-6,6 copolymer nylon (501
3B Ube Industries, Ltd.) Ethylene-vinyl acetate copolymer saponified resin: (Eval EP-F101 made by Kuraray) Adhesive resin 1: Acid-modified linear low-density polyethylene (Admer NF-300 manufactured by Mitsui Petrochemical Industries) Ethylene- Vinyl acetate copolymer: (Evatate D201
1 Sumitomo Chemical Co., Ltd.) The obtained raw film was sequentially stretched by a biaxial stretching method at a stretching ratio of length × width = 3 × 3 to form a multilayer stretched film having a total thickness of 50 μm. The pinhole resistance was evaluated by measuring the bending fatigue resistance with a gel bot tester and the puncture strength with a pin curvature radius of 0.5 mm.

Example 2 A film (total thickness 180 μm) having a layer structure of polyamide resin 1 / adhesive resin 1 / polyamide resin 1 was prepared by a coextrusion method. When the thickness ratio of each layer was measured, it was 40/20/40 in the order of the above layer constitution.
(%)Met. The raw materials used for each layer were as follows. Polyamide resin 1: 6-nylon (1030B manufactured by Ube Industries) and MXD6 nylon (6001 manufactured by Mitsubishi Gas Chemical Co., Inc.) (blend ratio = 80: 20) Adhesive resin 1: Acid-modified ethylene-vinyl acetate copolymer ( The obtained raw fabric film was stretched by a simultaneous biaxial stretching method with a stretching ratio of length × width = 3 × 4 to obtain a multilayer stretched film having a total thickness of 15 μm. The evaluation of the pinhole resistance is Example-1.
I went the same way.

(Example-3) Polyamide resin 1 / adhesive resin 1 / ethylene-vinyl acetate copolymer saponified resin / adhesive resin 1 / polyamide resin 2 / adhesive resin 2 / linear chain by coextrusion method A film having a layered structure of low density polyethylene (total thickness 300 μm) was prepared. When the thickness ratio of each layer was measured, it was 10/10/10/10 / in the order of the above layer constitution.
It was 10/10/40 (%). The raw materials used for each layer were as follows. Polyamide resin 1: 6 nylon (1030B made by Ube Industries) and 6-12 nylon (7128B made by Ube Industries) Bund product (blend ratio = 90: 10) Polyamide resin 2: 6-6,6 Copolymer nylon (501
3B Ube Industries) ethylene-vinyl acetate copolymer saponified resin: (Eval EP-E105 made by Kuraray) Adhesive resin 1: Acid-modified linear low-density polyethylene (Admer NF-300 manufactured by Mitsui Petrochemical Industries) Adhesion Resin 2: Ethylene / acrylic acid ester / maleic anhydride terpolymer (Bondaine TX8030 manufactured by Sumika CDF Chemicals) Linear low-density polyethylene: (Sumikasen L FA-20
3-1 Sumitomo Chemical Co., Ltd.) The obtained raw film was sequentially stretched by a biaxial stretching method at a stretching ratio of length × width = 3 × 4 to form a multilayer stretched film having a total thickness of 25 μm. The evaluation of the pinhole resistance is Example-1.
I went the same way.

Example 4 A film having a layer structure of polyamide resin 1 / adhesive resin 1 / saponified ethylene / vinyl acetate copolymer / adhesive resin 1 / polyamide resin 1 by coextrusion method (total thickness 130 μm) )made. When the thickness ratio of each layer was measured, it was 30/7/20 in the order of the above layer constitution.
It was / 10/33 (%). The raw materials used for each layer were as follows. Polyamide resin 1: 6 Nylon (1030B made by Ube Industries) and amorphous nylon (PA3426 made by Mitsui Dupont Polychemical) blended product (blend ratio = 80: 2)
0) Saponified ethylene-vinyl acetate copolymer resin: (Eval EP-F101, manufactured by Kuraray) Adhesive resin 1: Acid-modified linear low-density polyethylene (Mersen P2030W, manufactured by Toyo Soda Kogyo Co., Ltd.) The total thickness is about 15μm by the biaxial stretching method with a stretching ratio of length x width = 2.5 x 3.5
A multilayer stretched film of The evaluation of pinhole resistance was performed in the same manner as in Example-1.

(Comparative Example 1) A film having a layer structure of polyamide resin 1 / ethylene-vinyl acetate copolymer saponified resin / polyamide resin 1 by a coextrusion method (total thickness 130 μm).
m) made. When the thickness ratio of each layer was measured, it was 40/20/40 (%) in the order of the above layer constitution. The raw materials used for each layer were the same as those of the polyamide resin 1 and the ethylene-vinyl acetate copolymer saponified resin of Example-4. The obtained raw film was stretched under the same conditions as in Example-4,
Furthermore, the evaluation of pinhole resistance was performed in the same manner as in Example-1.

(Comparative Example 2) A film having a layer structure of polyamide resin 1 / ethylene-vinyl acetate copolymer saponified resin / polyamide resin 2 / adhesive resin 1 / ethylene-vinyl acetate copolymer by a coextrusion method ( A total thickness of 450 μm) was made. When the thickness ratio of each layer was measured, it was 15/15/10/4/56 (%) in the order of the above layer constitution. The raw materials used for each layer were the same as the polyamide resin 1, polyamide resin 2, ethylene-vinyl acetate copolymer saponified resin, adhesive resin 1 and ethylene-vinyl acetate copolymer of Example-1. The obtained raw film was stretched under the same conditions as in Example-1, and the pinhole resistance was evaluated in the same manner as in Example-1.

(Comparative Example 3) A film having a layer structure of polyamide resin 1 (thickness: 180 μm) is formed by an extrusion method using a single layer die.
m) made. The raw material used was the same as the polyamide resin 1 of Example-2. The obtained raw film was stretched under the same conditions as in Example-2, and the pinhole resistance was evaluated in the same manner as in Example-1.

Table 1 shows the evaluation results of the pinhole resistance of Examples-1 to 4 and Comparative Examples-1 to 3. The flex fatigue resistance by the gel bot tester was evaluated by the number of pinholes generated 1000 times in an atmosphere of 25 ° C. The puncture strength was measured by applying the polyamide resin 1 side to the pin in a 25 ° C. atmosphere at a puncture speed of 500 mm / min. Compared to the comparative example, the number of pinholes generated in the gelbo flex was significantly reduced in the example, and the piercing strength was also increased.

Table 1 Thickness Gelbo flex Puncture strength (μm) (pieces / 1000 times) (Kgf) Example-1 50 3 1.7 Example-2 15 0 1.2 Example-3 25 1 1.9 Example-4 15 3 1.1 Comparative example-1 15 42 0.7 Comparative example-2 50 18 1.2 Comparative example-3 15 25 0.8

[0020]

EFFECTS OF THE INVENTION The multilayer stretched film of the present invention can significantly improve bag breaking resistance and pinhole resistance by incorporating an adhesive resin layer in an amount of 5% or more with respect to the total thickness, and has been increasing in the food field in recent years. -A packaging material that can prevent bag breakage and pinholes during the distribution process of refrigerated products and stabilize the quality.

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Claims (1)

[Claims] 1. A polyamide resin layer (A) (A '), an ethylene-vinyl acetate copolymer saponified resin layer (B), an adhesive resin layer (C) (C') (C '') and a seal layer. (D)
Which includes any of the following, and the stacking order is (1) A-C-A ', (2) A-C-B-A', (3).
A-C-B-C'-A ', (4) A-C-A'-C'-
D, (5) A-C-B-A'-C'-D or (6) A
-C-B-C'-A'-C ''-D which is a multilayer stretched film.