JPS6044154B2 - multilayer container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer container with excellent gas barrier properties, and particularly to a multilayer container with excellent gas barrier properties and transparency.

In recent years, with the diversification of packaging containers, containers that contain contents such as foods and medicines are required to have higher gas barrier properties.

In order to meet this demand, various devised containers have been put into practical use.For example, nylon is made of a gas barrier resin layer such as ethylene-vinyl alcohol copolymer and polyolefin to supplement this moldability. A multilayer container consisting of a base material layer is known. In this container, an appropriate gas barrier property can be obtained by arbitrarily setting the thickness of the barrier layer, but since polyolefin such as polyethylene or polypropylene is used as the base material, it becomes translucent or opaque, and Rigidity is also not sufficient. In order to deal with these problems, the present inventors have developed a saponified ethylene-vinyl acetate copolymer with an ethylene content of 10 to 50 mol% and a saponification rate of 80% or more, or a saponified ethylene-vinyl acetate copolymer thereof, and other materials. or a layer made of polyvinyl chloride, thermoplastic polyester or its copolymer, polyacrylonitrile or its copolymer, polystyrene or its copolymer. A layer with an ethylene content of 50 to 95 mol% and a saponification rate of 10 to 90 is used as a layer between the two to firmly adhere the two.
% of a saponified ethylene-vinyl acetate copolymer, or a blend of the saponified ethylene-vinyl acetate copolymer and an ethylene-vinyl acetate copolymer having a vinyl acetate content of 2 to % by weight. sex and gaspariya sex,
He invented a multi-layered container with excellent rigidity and has already applied for a patent for it.

The present invention has further improved upon this and has solved the above problem without an intermediate adhesive layer. That is, the present invention uses a saponified ethylene-vinyl acetate copolymer A having an ethylene content of 10 to 50 mol% and a saponification rate of 80% or more, and an ethylene-vinyl acetate copolymer A having an ethylene content of 50 to 95 mol% and a saponification rate of 5 to 0%. 95:5 to 50 with saponified vinyl acetate copolymer B
Adjacent to this is a blend layer of polyvinyl chloride, thermoplastic polyester or a copolymer thereof, polyacrylonitrile or a copolymer thereof, polyamide, polystyrene or a copolymer thereof. A multilayer container consisting of a layer consisting of any one of the above, and a saponified ethylene-vinyl acetate copolymer A having an ethylene content of 10 to 50 mol% and a saponification rate of 80% or more, and a saponified ethylene-vinyl acetate copolymer A having an ethylene content of 5
Ethylene-vinyl acetate copolymer saponified product B having a saponification rate of 0 to 95 mol% and a saponification rate of 5 to 90% is mixed in a weight ratio of 95:5 to 50:50, and further added with a vinyl acetate content as a third component. A blend layer comprising an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylic acid copolymer, or an ionomer resin having 50% or less of It is a multi-layer container consisting of a layer made of any one of vinyl, thermoplastic polyester or a copolymer thereof, polyacrylonitrile or a copolymer thereof, polyamide, polystyrene or a copolymer thereof.

Further, the container of the present invention can be expanded by 1.2 to 4 times in the vertical direction by a stretching rod, and by 1.2 times in the horizontal direction by blowing air.
．． By stretching the film by a factor of 5 to 5, it is possible to obtain even better transparency. The saponification rate of ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) is that it is a terpolymer consisting of units of ethylene, vinyl acetate, and vinyl alcohol.
Its properties are related to the composition ratio of each unit.

Saponified product A, which has a low ethylene content and high vinyl alcohol content, has excellent gas barrier properties, and saponified product B, which has a high ethylene content and a low vinyl acetate content, has excellent adhesive properties. Moreover, these two resins have excellent compatibility, and by mixing them in an appropriate ratio, a blended resin with excellent gas barrier properties and adhesive properties can be obtained. The appropriate mixing ratio is a weight ratio of A:B = 95:5 to 50:50, as will be discussed in more detail later in Examples. Furthermore, an ethylene-vinyl acetate copolymer or an ethylene-vinyl acetate copolymer having a vinyl acetate content of 50% or less is added to the blend layer of EVA saponified product A-B as a third component.
A blend layer in which either an ethyl acrylic acid copolymer or an ionomer resin is mixed within a weight ratio of saponified material B or less can also be used.

These third component resins all have carbonyl groups in the side chains of their molecules, and therefore have excellent compatibility with saponified EVA.

In this case, the amount to be added is within a range that does not exceed the amount of saponified EVA B so as not to impair adhesiveness and gas barrier properties. By adding EVA saponide B or a third component to such EVA saponide A, adhesiveness,
Not only does it provide workability and impact resistance, but it also makes it possible to reduce the cost of the material. In addition, other layers are made of polyvinyl chloride, thermoplastic polyester or its copolymer, polyacrylonitrile or its copolymer, which have excellent transparency and rigidity,
It is made of polyamide, polystyrene, or a copolymer thereof. Examples will be explained below.

Example 1 Ethylene-vinyl acetate copolymer was added to saponified ethylene-vinyl acetate copolymer A (ethylene content 25 to 30 mol%, saponification rate 96% or more, melting point 180°C) in the outer layer extruder of an outer layer blow molding machine. Saponified product (ethylene content 72 mol%, saponification rate 40%, vinyl acetate content 17% by weight,
Density 0.95g/d)Bf! -The weight ratio of A and B is A:B
= 95:5, 80:20, 50:50s, 20:80 blends were supplied, and hard vinyl chloride (tensile strength 490 (K9/d), elongation 190%) was supplied to an extruder for the inner layer.
, softness temperature 66°C).

The extruded resins were brought into close contact within the die and extruded into a single parison to obtain a container. Table 1 shows the physical properties of the container at each blend ratio. Example 2 The outer layer was a blend of old VA saponified product A and EVA saponified product B at a blend ratio of A:B = 80:20, and the inner layer was supplied with a thermoplastic polyester copolymer (terephthalic acid, isophthalic acid). Copolymerized polyethylene glycol density 1.27 by polycondensation of and cyclohexanedimethanol
, VICAT (softening point: 8), polyacrylonitrile copolymer (Barex21O, manufactured by Vistron, USA), polystyrene, and styrene-maleic acid copolymer resin for the inner layer, respectively.

Table 1 shows the physical properties of the container. Example 3 Is the outer layer disturbed? ■A saponified product A. (Supplying a blend of 5EVA saponified product B with a blend ratio of A:B = 80:20,
A container was obtained by also supplying hard polyvinyl chloride and copolymerized polyester for the inner layer.

The burrs (two-layer component) generated during this molding were collected in the inner layer. Example 4 A container having the structure of Example 3 but with the resins of the inner and outer layers reversed was supplied.

The comparative exception layer is 80% of the saponified EVA A and modified polyethylene (maleic anhydride grafted low-density polyethylene, Admer LB53O manufactured by Mitsui Petrochemicals, density 0.92 g/al).
:20 ratio was supplied, and rigid PVC was supplied as the inner layer to obtain a container.

Claims (1)

[Claims] 1. Ethylene content is 10 to 50 mol%, saponification rate is 80
% or more of saponified ethylene-vinyl acetate copolymer A and ethylene content of 50 to 95 mol%, saponification rate of 5 to 90%
Saponified ethylene-vinyl acetate copolymer B and 95:
Adjacent to this is a blend layer formed by mixing in a weight ratio of 5 to 50:50, polyvinyl chloride, thermoplastic polyester or a copolymer thereof, polyacrylonitrile or a copolymer thereof, polyamide, polystyrene or a copolymer thereof. A multilayer container consisting of layers made of any one type of polymer. 2 Ethylene content is 10 to 50 mol%, saponification rate is 80
% or more of saponified ethylene-vinyl acetate copolymer A and ethylene content of 50 to 95 mol%, saponification rate of 5 to 90%
Saponified ethylene-vinyl acetate copolymer B and 95:
Mixed in a weight ratio of 5 to 50:50, and further added with ethylene containing 50% or less of vinyl acetate as a third component.
A blend layer consisting of a vinyl acetate copolymer, an ethylene-ethyl acrylic acid copolymer, or an ionomer resin mixed in a weight ratio below the above B; A multilayer container comprising a layer made of any one of polyacrylonitrile or a copolymer thereof, polyamide, polystyrene, or a copolymer thereof.