JP2981086B2 - Multilayer film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used as a bottom material for food packaging, and is a composite multilayer film which can be deep drawn by a method such as pressure forming and has excellent heat resistance, transparency and mechanical strength. It is about.

[0002]

2. Description of the Related Art In the food industry, temperature, moisture, oxygen, light rays, etc. in the distribution process, and microorganisms such as bacteria and mold cause deterioration in quality due to various kinds of deterioration such as loss of shape, color, taste and aroma. As a method of storing without deterioration of quality until it is easily consumed by consumers,
Conventionally, a method has been employed in which additives such as preservatives and antioxidants are directly added to foods. 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 such circumstances, treatments such as boil sterilization and retort sterilization are performed as one method for ensuring the long-term preservability of the contents. In particular, retort foods are completely sterilized by heating to sterilize microorganisms and can be stored at room temperature for a long period of time. 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 bag-like packaging material of a composite film called a retort pouch, but recently, a deep drawing molding machine has been developed 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 heat resistance to withstand retort sterilization, deep drawability, transparency, multiple functions such as mechanical strength, and A low price is 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, a method of pasting individual films to form a multilayer by a dry laminating method or the like has conventionally been adopted, but a single-layer film having a limited thickness and performance must be selected. However, it has been difficult to obtain a satisfactory material, such as increasing the number of layers, increasing the cost, and generating a solvent odor during molding.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite multilayer film which can be formed by deep drawing and which can be subjected to a retort sterilization treatment and has excellent heat resistance, transparency and mechanical strength. To provide.

[0004]

The present invention comprises a 6 nylon resin layer (A), a copolymer resin layer of 6 nylon and 6-6 nylon (B), a modified polyolefin adhesive resin layer (C),
The random copolymerized polypropylene resin layer (D) and the homopolymerized polypropylene resin layer (E) are (A)-(B)-
In the composite multilayer film laminated in the order of (C)-(D)-(E), the thickness of the (A)-(B) layer is 20 times the total thickness.
To 50%, and the thickness of the (A) layer is (A)-
(B) A multilayer film characterized by comprising 10 to 50% of the layer. That is, the layer (A) is provided as a layer for providing mechanical strength and the like, the layer (B) is provided as a layer for preventing film thinning during deep drawing, and the layer (D) is provided as a layer for preventing wrinkles during deep drawing. Is a film having a laminated structure by a co-extrusion method using the (E) layer as a sealant layer.

[0005] The layer (A) in the present invention comprises ε-capro-
Nylon 6 produced by ring-opening polymerization of lactam is used, and nylon 6 having a relative viscosity (JIS K 6810 {method using sulfuric acid solution}) of 3.5 to 5.0 is preferably used. The layer (B) in the present invention contains ε-capro
Lactam and hexamethylenediamine adipate
6 nylon and 6 -copolymer having relative viscosities (JIS K 6810 {method using sulfuric acid solution}) of 3.5 to 5.0
6 nylon copolymer resin is used. In the layer (C) in the present invention, linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer or ethylene-propylene elastomer may be added to a monobasic unsaturated fatty acid such as acrylic acid or methacrylic acid, or maleic acid. acid,
An acid-modified olefin resin obtained by chemically bonding an anhydride of a dibasic unsaturated fatty acid such as fumaric acid or itaconic acid, that is, maleic anhydride, is used. Particularly, a maleic acid-modified product using polypropylene as a base polymer is most suitable from the viewpoint of interlayer adhesion strength. For the layer (D) in the present invention, a copolymer of propylene and another olefin such as ethylene is used, preferably a melt flow rate (JIS K 6758, test temperature 230).
° C, test load 2.16 kgf｝) 0.5-3.0 (g
/ 10 min) is used. For the layer (E) in the present invention, a homopolymer of propylene is used. Preferably, a melt flow rate (JIS K 6758, test temperature 2) is used.
30 ° C., test load 2.16 kgf｝) 0.5 to 3.0 (g)
/ 10 min) is used. An appropriate amount of a lubricant, an anti-blocking agent, an antistatic agent, an ultraviolet absorber or the like may be added to the layer (A) or the layer (E). As a method for producing a film, a method in which melt extrusion is performed from a lamination die by a coextrusion method using a plurality of extruders, and cooling and solidification is optimal.

[0006]

【Example】

<< Example 1 >> A film having a layer structure of 6 nylon / 6,6-6 nylon copolymer / adhesive resin / random copolymerized polypropylene / homopolymerized polypropylene, which was melt-extruded from a multilayer co-extrusion die by a T-die extrusion method. (Thickness 100
μm). The thickness ratio of each layer is 10/30 /
10/20/30%. << Comparative Examples 1 and 2 >> As Comparative Example 1, 6 nylon / 6,6-
6 nylon copolymer / adhesive resin / homopolymerized polypropylene (each layer thickness ratio: 10/30/10/50%), Comparative Example 2 includes 6 nylon / adhesive resin / random copolymerized polypropylene / homopolymerized polypropylene (each layer thickness) ratio;
A film (thickness: 100 μm) having a layer configuration of (40/10/20/30%) was produced. The raw material resin used for each layer configuration of Example 1 and Comparative Examples 1 and 2 was: 6 Nylon Kanebo Nylon MC-1 manufactured by Kanebo
40 ・ 6,6-6 nylon copolymer Toray Nylon CM6041XFS made by Toray ・ Adhesive resin Admer QF-30 made by Mitsui Petrochemical
5. Random copolymerized polypropylene Sumitomo Noblen S-131 manufactured by Sumitomo Chemical Co., Ltd. Homopolymerized polypropylene UP Polypro YE-101 manufactured by Union Polymer.

Comparative Example 3 In Comparative Example 3, the following single-layer film was used. Non-stretched nylon film (CNy) Reyfan T-1401 (40 μm in thickness) manufactured by Toray Synthetic Film. Unstretched polypropylene film (CPP). Toray synthetic film Torayfan 3931 (thickness 60)
μm) A film having a layer configuration of CNy / CPP was produced by a dry lamination method. The films obtained in Example 1 and Comparative Examples 1, 2, and 3 were subjected to a deep drawing air forming machine (FV-
6300) 100 mm x 100 mm, depth 20 m
m, and the contents were filled with seasoned fried food and heat-sealed with the lid film. Note that a dry laminate film having a stretched nylon ONy / CPP configuration was used as the cover material. The single-layer film used is shown below.・ ONy Unitika emblem ON (25μ thickness)
m) ・ CPP Toray Synthetic Film Trefane 3931
(Thickness: 60 μm) The obtained package was placed in a retort pot and subjected to a retort sterilization treatment at 125 ° C. for 40 minutes. Table 1 shows the deep-drawn air-forming properties of Example 1 and Comparative Examples 1, 2, and 3, and the state of the package after retorting.

[0008] As is clear from Table 1, the films of the Examples have better deep drawability than Comparative Examples 1, 2, and 3, and also have excellent retort suitability.

The composite multilayer film according to the present invention is excellent in deep drawing formability, suitability for retort, transparency, mechanical strength and the like, and is suitable as a packaging film for food and other retort sterilization.

Claims (5)

(57) [Claims] 1. A 6 nylon resin layer (A), a 6 nylon and 6-6 nylon copolymer resin layer (B), a modified polyolefin adhesive resin layer (C), a random copolymerized polypropylene resin layer (D), and homopolymerization. Polypropylene resin layer (E)
In a composite multilayer film laminated in the order of (A)-(B)-(C)-(D)-(E), the thickness of the (A)-(B) layer is 20-50% of the total thickness. A multilayer film, wherein the thickness of the layer (A) is 10 to 50% of the layer (A)-(B). 2. A nylon 6 resin having a relative viscosity (JIS K
6810 {method using sulfuric acid solution}) The multilayer film according to claim 1, wherein 3.5) to 5.0. 3. The multilayer film according to claim 1, wherein the nylon 6 and nylon 6-6 copolymer resins have a relative viscosity (JIS K 6810 {method using sulfuric acid solution}) of 3.5 to 5.0. 4. The method according to claim 1, wherein the random copolymerized polypropylene resin has a melt flow rate (JIS K 6758, test temperature 2).
30 ° C, test load 2.16kgf) 0.5-3.0
(G / 10min), The multilayer film of Claim 1, 2 or 3. 5. The method according to claim 1, wherein the homopolymerized polypropylene resin has a melt flow rate (JISK 6758, test temperature 230 ° C.,
Test load 2.16kgf) 0.5-3.0 (g / 10m)
The multilayer film according to claim 1, 2, 3, or 4, which is in).