JPH07241964A - Multilayered film - Google Patents

Abstract

PURPOSE:To obtain a multilayered film capable of being draw and mainly used as a bottom material for food packaging by forming a layered structure of blend resin/6,6-6 nylon copolymer/adhesive resin/random propylene copolymer/ propylene homopolymer. CONSTITUTION:A multilayered film is formed by successively laminating a blend material layer A of MXD 6 and a 6 nylon resin, a 6,6-6 nylon copolymer resin layer B, a modified polyolefin adhesive resin layer C, a propylene random copolymer resin layer D and a propylene homopolymer resin layer E. At that time, the thickness of the A-B layer is set to 20-50% of the total thickness of the film and the thickness of the layer A is set to 10-50% of the A-B layer. The layer A is formed by using a blend material of MXD 6 obtained by the polycondensation reaction of metaxylenediamine and adipic acid and a 6 nylon resin obtained by the ring opening polymerization of epsilon-caprolactam and the relative viscosity of the blend material of MXD 6 and the 6 nylon resin is adjusted to 3.5-5.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly used as a bottom material for food packaging, and can be deep-drawn by a method such as pressure molding, which has heat resistance, oxygen gas barrier property, transparency and mechanical strength. Relates to an excellent multilayer film.

[0002]

2. Description of the Related Art In the food industry, quality is deteriorated due to various alterations such as loss of shape, color, taste and aroma due to temperature, moisture, oxygen, light rays, etc. and microorganisms such as bacteria and mold in the distribution process. As a method that is easy to store without causing quality deterioration until it enters the mouth of the consumer,
Conventionally, a method of directly adding additives such as preservatives and antioxidants to food has been used. However, in recent years, in the food processing industry, regulations on additives to foods have become strict, and the amount of additives used has been reduced or almost never used. Under such circumstances, as a method for ensuring long-term storage stability of the contents, packaging materials having an excellent oxygen gas barrier property, treatments such as boil sterilization and retort sterilization are performed. The retort food is a product in which microorganisms are completely sterilized by heat sterilization and can be stored at room temperature for a long time. As a plastic material conventionally used as a packaging material for these contents, there is a container formed by molding a relatively thick plastic sheet. On the other hand, as a flexible packaging material using a relatively thin plastic film, there was a bag-shaped packaging material such as a multi-layer film called a retort pouch, but recently, a deep drawing machine for the purpose of speeding up and automation of packaging. There is a growing demand for packaging materials that can be packaged at high speed by using the above. Further, at the transportation stage in the food distribution process, there is a problem such as bag breakage depending on the transportation method, and a film having excellent mechanical strength is required. From the above points, the plastic film which is a packaging material required in such a field, heat resistance to withstand retort sterilization, deep drawing formability, oxygen gas barrier property, transparency, mechanical strength, etc. It is required to have functions and be cheap in price. In order to satisfy these requirements, it is conceivable that the film has a laminated structure of several layers in terms of performance, and various functions are dispersed in each layer so that the film has many functions in total. In order to obtain such a film, conventionally, a method of laminating individual films into a multi-layer by a dry laminating method or the like has been used, but it is necessary to select from a single-layer film with limited thickness and performance. In addition, the number of layers increases, the cost increases, and it is difficult to obtain a satisfactory product such that a solvent odor is generated during molding.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to obtain deep drawing, retort sterilization, heat resistance, oxygen gas barrier property, transparency and mechanical strength. It is to provide an excellent multilayer film.

[0004]

The present invention provides MXDs 6 and 6
Blend material layer with nylon resin (A), 6,6-6 copolymer nylon resin layer (B), modified polyolefin adhesive resin layer (C), random copolymer polypropylene resin layer (D), and homopolymer polypropylene resin In a multilayer film in which the layers (E) are laminated in the order of (A)-(B)-(C)-(D)-(E), the thickness of the (A)-(B) layers is 20 to the total thickness. The present invention relates to a multilayer film, which is 50% and the thickness of the (A) layer is 10 to 50% of the (A)-(B) layer. That is, mechanical strength,
The (A) layer is used as the oxygen gas barrier property-imparting layer, and the (B) layer is used as the film-thinning preventing property-imparting layer during deep drawing.
A film having a laminated structure formed by a co-extrusion method using a layer (D) as a wrinkle prevention-imparting layer at the time of deep drawing and a layer (E) as a sealant layer.

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

The layer (C) contains linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer,
Alternatively, ethylene-propylene elastomer is chemically treated with a monobasic unsaturated fatty acid such as acrylic acid or methacrylic acid, or an anhydride of a dibasic unsaturated fatty acid such as maleic acid, fumaric acid, or itaconic acid, that is, maleic anhydride. The acid-modified olefin-based resin obtained by chemically bonding is used. In particular, a maleic acid-modified product using polypropylene as a base polymer is most suitable from the viewpoint of interlayer adhesive strength. For the layer (D), a random copolymer polypropylene resin of a copolymer of propylene and another olefin such as ethylene is used, and the melt flow rate (JIS K 6758 {test temperature 230 ° C., The test load of 2.16 kgf} is 0.5 to 0.5 from the viewpoint of preventing wrinkles due to uneven heating of the film during deep drawing.
It is preferably 3.0 (g / 10 min).
A homopolymer of propylene is used for the (E) layer, but an appropriate amount of a lubricant, an anti-blocking agent, an antistatic agent, an ultraviolet absorber or the like may be added to the (A) layer or the (E) layer. . The melt flow rate of this homopolymerized polypropylene resin (JIS K 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 heating of the film during deep drawing.
10 min) is preferable. As a method for producing a film, a method of melt-extruding from a laminating die by a coextrusion method using a plurality of extruders and then cooling and solidifying is most suitable.

[0007]

【Example】

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

The raw materials for the resin constituting each layer are as follows: MXD6: Mitsubishi Gas Chemical's MX nylon 6121
(Relative viscosity: 3.5) 6 Nylon: Kanebo Kanebo Nylon MC-14
0 (relative viscosity: 4.6) ・ 6,6-6 copolymer nylon: Toray nylon
CM6041XFS (relative viscosity: 4.2) -Adhesive resin: Mitsui Petrochemical Admer QF-
305 ・ Random copolymer polypropylene: Sumitomo Noblen S
-131 (melt flow rate: 1.2) -Homopolymerized polypropylene: Union Polymer UP
Polypro YE-101 (melt flow rate: 1.
2) was used. In addition, the following monolayer film was used as (Comparative Example 4):-Unstretched nylon film (CNy) made by Toray Synthetic Film Rayfan T-1401 (thickness 40 μm) -Unstretched polypropylene film (CPP) made by Toray Synthetic Film Fan 3931 (thickness 60
μm) A film having a CNy / CPP layer structure was produced by a dry lamination method. The obtained film was applied to a deep-drawing pressure air forming machine (FV-6300 manufactured by Omori Machine Co., Ltd.) to obtain 100 mm ×
Molding was performed with a molding die having a depth of 100 mm and a depth of 20 mm, and a seasoned fried food was filled as the content, and the obtained packaged product was put in a retort kettle and subjected to retort sterilization treatment at 120 ° C. for 40 minutes. Table 1 shows the oxygen gas barrier properties of Examples and Comparative Examples,
The deep-drawing compressed air formability and the state of the package after retort are shown.

Table 1 Oxygen gas Barrier property after deep drawing retort Pneumatic formability Package 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 Comparative example 3 10 Wrinkle generation Almost no change Comparative example 4 25 Wrinkle generation Deformation As shown in Table 1, the films of Examples have oxygen gas barrier properties of Comparative Examples 1 and 4. Compared to Comparative Examples 2, 3 and 4, the deep-drawing compressed air formability is also excellent without the thinning of the corner portion and the raindrop-like wrinkles. Also, the retort suitability is excellent without the package being deformed.

[0010]

The multilayer film according to the present invention is excellent in deep drawability, retort suitability, oxygen gas barrier property, transparency, mechanical strength and the like, and is suitable as a packaging film for food and other retort sterilization. Is.

Claims (5)

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