JP3037549B2 - 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, which can be deep drawn by a method such as pressure forming, and has heat resistance, oxygen gas barrier properties, transparency, mechanical strength and the like. Are related to an excellent multilayer film.

[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, as a method for ensuring the long-term preservability of the contents, packaging materials having excellent oxygen gas barrier properties, treatments such as boil sterilization and retort sterilization are performed. The retort foods are completely sterilized by heating and sterilized by microorganisms so that they 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 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 include heat resistance to withstand retort sterilization, deep drawability, oxygen gas barrier properties, transparency, and multiple mechanical strengths. It is required to have functions and be inexpensive. 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 laminating individual films by a dry laminating method or the like has conventionally been used, 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 heat-resistant, oxygen-gas-barrier, transparent, and mechanical strength which can be deep-drawn and sterilized by retort. It is to provide an excellent multilayer film.

[0004]

According to the present invention, MXDs 6 and 6 are provided.
Blend material layer with nylon resin (A), 6,6-6 copolymerized nylon resin layer (B), modified polyolefin adhesive resin layer (C), random copolymerized polypropylene resin layer (D), and homopolymerized polypropylene resin In the multilayer film in which the layer (E) is laminated in the order of (A)-(B)-(C)-(D)-(E), the thickness of the (A)-(B) layer is 20- of the total thickness. The present invention relates to a multilayer film characterized in that the thickness is 50% and the thickness of the (A) layer is 10 to 50% of that of the (A)-(B) layer. That is, mechanical strength,
Layer (A) as a layer for providing oxygen gas barrier properties, and layer (B) as a layer for preventing film thinning during deep drawing.
This is a film having a laminated structure by a co-extrusion method using a layer (D) as a layer for preventing wrinkling during deep drawing and a layer (E) as a sealant layer.

[0005] The layer (A) in the present invention uses a blend material of MXD6 produced by a polycondensation reaction of metaxylenediamine and adipic acid with 6 nylon resin produced by ring-opening polymerization of ε-caprolactam. , MX
A blend material in which D6 is mixed in 10 to 90% of the entire (A) layer (hereinafter, referred to as “blend”) is used. From the viewpoint of mechanical strength and oxygen gas barrier properties, it is preferable that MXD6 is mixed in the blend in an amount of 50% or more. Further, the relative viscosity (JIS K 6810 {method using sulfuric acid solution}) of the blended material of MXD6 and 6 nylon resin is preferably 3.5 to 5.0 from the viewpoint of preventing wrinkles due to uneven film heating during deep drawing. preferable. (B) In the layer,
6,6-6 copolymerized nylon produced by a copolymerization reaction between ε-caprolactam and hexamethylene adipate is used. The relative viscosity (JIS K 6810 {method using sulfuric acid solution}) of the 6,6-6 copolymerized nylon resin is preferably 3.5 to 5.0 from the viewpoint of preventing wrinkles due to uneven film heating during deep drawing. preferable.

The layer (C) includes linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer,
Or ethylene-propylene elastomer, acrylic acid, monobasic unsaturated fatty acid such as methacrylic acid, or anhydride of dibasic unsaturated fatty acid such as maleic acid, fumaric acid, itaconic acid, that is, maleic anhydride, etc. An acid-modified olefin-based resin obtained by a natural bond 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 (D) layer, a random copolymerized polypropylene resin of a copolymer of propylene and another olefin such as ethylene is used. The melt flow rate of the random copolymerized polypropylene resin (JIS K 6758, test temperature 230 ° C, The test load of 2.16 kgf) is 0.5 to 0.5 to prevent wrinkles due to uneven film heating during deep drawing.
It is preferably 3.0 (g / 10 min).
A homopolymer of propylene is used for the layer (E), but a suitable 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). . The melt flow rate of this homopolymerized polypropylene resin (JISK 6758, test temperature 230 ° C,
The test load of 2.16 kgf) is 0.5 to 3.0 (g / g) from the viewpoint of preventing wrinkles due to uneven film heating during deep drawing.
10 min). 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.

[0007]

【Example】

(Example 1) As a T-die extrusion method, melt extrusion was performed from a multi-layer coextrusion die using a T-die extrusion method, and a layer structure of blend / 6,6-6 nylon copolymer / adhesive resin / random copolymerized polypropylene / homopolymerized polypropylene was 100 μm. Film (thickness ratio of each layer; 10/30/10/25/25%)
Was prepared. The MXD6 ratio of the blend was 90%. (Example 2) 100 μm film having a layer structure of blend / 6,6-6 nylon copolymer / adhesive resin / random copolymerized polypropylene / homopolymerized polypropylene (thickness ratio of each layer; 25/25/10/25/25) %). The MXD6 ratio of the blend was 50%. (Comparative Example 1) A 100 μm film having a layer configuration of 6 nylon / 6,6-6 nylon copolymer / adhesive resin / homopolymerized polypropylene (thickness ratio of each layer; 10/30/1)
(0/50%). (Comparative Example 2) Blend / adhesive resin / random copolymerized polypropylene / homopolymerized polypropylene layer composition 1
00 μm film (thickness ratio of each layer; 40/10/20 /
30%). (Comparative Example 3) 100 μm film having a layer configuration of blend / 6,6-6 nylon copolymer / adhesive resin / homopolymerized polypropylene (thickness ratio of each layer; 10/30/10)
/ 50%). MXD of the blend of the comparative example
The 6 ratio was 80%.

[0008] The raw materials of the resin constituting each layer include: MXD6: MX Nylon 6121 manufactured by Mitsubishi Gas Chemical.
(Relative viscosity: 3.5) 6 Nylon: Kanebo Nylon MC-14 manufactured by Kanebo
0 (relative viscosity: 4.6)-6,6-6 copolymer nylon: Toray Nylon manufactured by Toray
CM6041XFS (relative viscosity: 4.2)-Adhesive resin: Admer QF- manufactured by Mitsui Petrochemical
305 ・ Random copolymerized polypropylene: Sumitomo Noblen S
-131 (melt flow rate: 1.2) ・ Homopolymerized polypropylene: UP made by Union Polymer
Polypropylene YE-101 (melt flow rate: 1.
2) was used. In addition, the following single-layer film was used as (Comparative Example 4): Non-stretched nylon film (CNy) Toray Synthetic Film Reifan T-1401 (thickness: 40 μm) Non-stretched polypropylene film (CPP) Toray Synthetic Film Toray Fan 3931 (thickness 60
μm) A film having a layer configuration of CNy / CPP was produced by a dry lamination method. The obtained film is applied to a deep drawing air forming machine (FV-6300 manufactured by Omori Machinery) and 100 mm ×
Molding was performed using a molding die having a thickness of 100 mm and a depth of 20 mm, and the contents were filled with seasoned frying, and the resulting package was placed in a retort pot and subjected to a retort sterilization treatment at 120 ° C. for 40 minutes. Table 1 shows oxygen gas barrier properties of Examples and Comparative Examples,
2 shows the state of the deep drawn compressed air formability and the package after retort.

Table 1 Oxygen gas Deep drawing Barrier property after retort Pneumatic forming property Packed state (cc / m ² · D) Example 1 6 Good Almost no change Example 2 6 Good Almost no change Comparative Example 1 25 Good Almost no change Comparative Example 2 5 Thinning at corners Almost no change Comparative Example 3 10 Wrinkle generation Almost no change Comparative Example 4 25 Wrinkle generation As shown in Table 1, which is deformed , the films of Examples have oxygen gas barrier properties similar to those of Comparative Examples 1 and 4. As compared with the above, the deep drawing pressure forming property is excellent without the thinning of the corner portion and the wrinkle like raindrops seen in Comparative Examples 2, 3, and 4. Also, the retort suitability is excellent without deformation of the package.

[0010]

The multilayer film according to the present invention is excellent in deep drawing formability, retort suitability, oxygen gas barrier properties, transparency, mechanical strength, etc., and is suitable as a packaging film for food and other retort sterilization. It is.

Claims (5)

(57) [Claims] 1. A blend material layer of MXD6 and 6 nylon resin (A), a 6,6-6 copolymer nylon resin layer (B),
The modified polyolefin adhesive resin layer (C), the random copolymerized polypropylene resin layer (D), and the homopolymerized polypropylene resin layer (E) are (A)-(B)-(C)-(D)
-In the multilayer film laminated in the order of (E),
The thickness of the (A)-(B) layer is 20-50% of the total thickness, and the thickness of the (A) layer is 10-5 of the (A)-(B) layer.
A multilayer film, which is 0%. 2. The multilayer film according to claim 1, wherein the relative viscosity (JIS K 6810 {method using sulfuric acid solution}) of the blended material of MXD6 and nylon 6 resin is 3.5 to 5.0. 3. The multilayer film according to claim 1, wherein the relative viscosity (JIS K 6810 {method using sulfuric acid solution}) of the 6,6-6 copolymerized nylon resin is 3.5 to 5.0. 4. The melt flow rate of a random copolymerized polypropylene resin (JIS K 6758, test temperature 23)
0 ° C, test load 2.16 kgf) is 0.5 to 3.0.
(G / 10min), The multilayer film of Claim 1, 2 or 3. 5. The melt flow rate of a homopolymerized polypropylene resin (JISK 6758, test temperature 230 ° C.,
Test load 2.16 kgf) is 0.5 to 3.0 (g / 1)
0 min).