JPS6035258B2 - laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a polypropylene film and a specific ethylene-vinyl acetate saponified material (hereinafter abbreviated as "saponified material").

) The present invention relates to a laminated film having a specific adhesive layer that allows the film to be bonded to the film very easily. Samurai Kosho 52-2202 for adhering coextruded laminated films made of two or more resins to each other.
As seen in No. 7, styrene-butadiene floc copolymer (hereinafter abbreviated as "block copolymer").

) was used as a preferred example. However, recently, the above-mentioned "block" has been used as an adhesive layer in laminated films made by the melt extrusion lamination method or English extrusion method, which are made of polypropylene film and "saponified" film, which are often used for packaging food products that require gas barrier properties. Although it is possible to adhere to a polypropylene film even if a ``copolymer'' is used, the adhesiveness of ``munanide'' is insufficient, and a new adhesive layer has been desired for this purpose. Here, we refer to methyl methacrylate-butadiene-styrene copolymer (hereinafter abbreviated as "Mold S").

), and as a result of various studies, we found that if "MBS" and "block copolymer" are used in a specific ratio, a polypropylene layer and a "saponified layer" can be formed by melt extrusion lamination method or coextrusion method. The present invention was developed based on the discovery that adhesion is extremely easy when bonding to a polypropylene layer, an ethylene content of 20-50 mol%, and a saponification degree of 90%
As the adhesive layer of the laminated film consisting of the above ethylene-vinyl acetate copolymer renanide layer, methyl methacrylate-butadiene-styrene copolymer and styrene-butadiene floc copolymer are used in a weight ratio of 1:0.2. This relates to a laminated film using a mixture formed by blending in the range of .about.4.

In the present invention, it is sufficient to use both the "M pre-copolymer" and the "block copolymer" that are commonly used for extrusion film forming, and the blend ratio is 1:0.2 to 4, preferably 1:1. : A range of 2 to 3 is essential.

Anything outside this range has poor adhesion and cannot be used. Further, the polypropylene is desirably an isotactic one having crystallinity, but copolymers with ethylene and the like are also included. The "saponified product" of the present invention has an ethylene content of 20 to 50
Mol%, preferably 30 to 45 mol%, degree of renanization 90
% or more, preferably 95% or more of saponified ethylene-vinyl acetate copolymer. The following preferred embodiments of the manufacturing method of the present invention can be exemplified.

[Saponified material added to 1'1 wisteria-stretched polypropylene film]
A method in which a mixture of "MBS" and "block copolymer" is coextruded and extrusion laminated, and then stretched in a direction perpendicular to the above-mentioned material.

'2' A mixture of "M spots" and "block copolymer" is extrusion laminated on a uniaxially stretched polypropylene film, and then "saponified material" is extrusion laminated on the mixture surface of this film, and further in a direction perpendicular to the above. How to stretch.

{3} Three-layer coextrusion method {4) Three-layer coextrusion → stretching method '5) Other appropriate methods Among these, '1' and ■ are particularly preferable examples.

Because a mixture of "M Shigeru" and "block copolymer" can be formed into a film by extrusion using normal methods, this property can be used to directly laminate both layers using extrusion lamination or coextrusion. This is because it is possible. The present invention is as described above, and the mixture of "MBS" and "block copolymer" according to the present invention is laminated by a polypropylene film and a "munanide" film by, for example, a melt extrusion lamination method or a coextrusion method. When applied as an adhesion layer for films, it has extremely high adhesive strength compared to conventional ones,
There is absolutely no possibility of peeling occurring during use.
According to the present invention, it is possible to produce a laminated film with excellent gas barrier properties extremely easily, and the present invention has a particularly remarkable effect as it greatly contributes to cost reduction through increased efficiency. Examples of the present invention will be described below.

Example 1 A saponified ethylene-vinyl acetate copolymer with an ethylene content of 40 mol% and a saponification degree of 99% or more, M old S resin, and styrene-butadiene were deposited on a film longitudinally stretched four times as much as crystalline polypropylene. Proc copolymer and weight ratio: 1
: The blended mixture of 3 was introduced into one die from two extruders and co-extruded at a die temperature of 21,000 ℃. By extrusion laminating with the mixture as an adhesive layer, 3
A layered film was obtained.

Thereafter, this three-layer film was subjected to 7-fold traverse stretching at 150q0, and then heat treated at 155oo to obtain a laminated film according to the present invention. Comparative example 1 Example 1
A laminated film was obtained by using a single styrene-butadiene floc copolymer instead of the adhesive layer.

Table 1 shows these comparative data. Table 1 (The adhesive strength was measured using a tensile test manufactured by Toyo Seiki Co., Ltd. to measure a peel force of 180 cm.) As is clear from Table 1, the adhesive of the present application exhibits extremely strong adhesive strength. .

Claims (1)

[Claims] 1 As an adhesive layer for a laminated film consisting of a polypropylene layer and a saponified ethylene-vinyl acetate copolymer layer with an ethylene content of 20 to 50 mol% and a saponification degree of 90% or more, methyl methacrylate-butadiene-styrene copolymer and styrene. butadiene block copolymer at a weight ratio of 1
: A laminated film characterized by using a mixture formed by blending in the range of 0.2 to 4.