JPS595430B2 - Tasouyouki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coextruded multilayer container consisting of a polyamide layer and a polyolefin layer.

Currently, single polyvinyl chloride containers are used in a variety of applications, but these containers emit toxic gas when incinerated.
The amount of smoke emitted is a problem. In addition, vinyl chloride is
Residual monomers pose a hygienic problem, and this problem is particularly serious in the case of food products. Therefore, various containers using resins with performance comparable to polyvinyl chloride are being considered. One possible example is a multilayer container made of polyamide resin and polyolefin resin, but since both resins have poor adhesion, they do not adhere at the joint surface and separate between the layers.

Here, as a method of firmly adhering the polyamide layer and the polyolefin layer, a method of modifying the polyolefin layer is generally used.

It is common to graft an unsaturated carboxylic acid such as maleic anhydride onto a polyolefin and chemically bond it to a polyamide layer.

In the above container, since polyamide resin is expensive,
Even if we tried to make the container as thin as possible, we could not obtain a container that was comparable in price to a container made of polyvinyl chloride.

The aim of the invention is to eliminate these drawbacks and to provide a cheaper and
Has gas permeability, transparency, mechanical strength, and chemical resistance.
Moreover, the object is to obtain a coextruded multilayer container with excellent adhesive strength between layers.

The present invention will be explained in detail below.

The present invention consists of a polyamide resin layer and a polyolefin layer, and the polyolefin layer has 80% by weight of polyolefin.
This is a coextruded multilayer container made of a resin mixed with 15% by weight of an ionomer resin and 5% by weight of polypropylene modified with maleic anhydride.

Although the adhesiveness between polyamide resin and ionomer resin is strong, ionomer resin is about 2.5 times more expensive than polyolefin and is not suitable. The amount of ionomer resin added to the polyolefin is preferably about 15% by weight based on the polyolefin.

Addition amounts other than this tend to cause flo marks, deterioration of moldability, and uneven adhesion. Adding about 5% by weight of maleic anhydride graft-modified polypropylene to the above polyolefin/ionomer resin mixture improves adhesion;
Further, uniformity of mixing can be obtained by reducing flow marks and the like.

This graft-modified polypropylene has good compatibility with ionomer resins and the like, and can be made with excellent transparency. The container of the present invention can be produced at a lower cost, and has the same gas barrier properties as polyvinyl chloride, which is currently commonly used.
It has comparable transparency and mechanical properties, and is easily incinerated, so there is no risk of pollution.

Examples will be described below.

Extrude through the die so that the nylon layer is on the outside and the polyolefin layer is on the inside.

The polyolefin layer is made of low density polyethylene (MI=0.
3) A resin was used in which 80% by weight, 15% by weight of Surlyn A (manufactured by DuPont) and 5% by weight of maleic anhydride were mixed. Each resin is melted and extruded through a concentric die using an extruder. The extruded nylon layer and polyolefin layer were fused in a die and extruded as a two-layer parison, then placed in a mold and blow-molded to obtain a multilayer hollow container. Comparative Example 1 A multilayer hollow container was obtained in the same manner as in Example 1, with a nylon layer on the outside and an ionomer layer on the inside.

Comparative Example 2 A multilayer hollow container was obtained in the same manner as in Example 1, with the outer layer consisting of a nylon layer and the inner layer consisting of a maleic anhydride graft-modified low-density polyethylene layer.

Comparative Example 3 A multilayer hollow container was obtained in the same manner as in Example 1, consisting of a nylon layer on the outside and a polyolefin layer containing 85% by weight of low-density polyethylene and 15% by weight of Surlyn A on the inside.

Next is a table comparing these physical properties.

The prices are compared when the price of a single polyvinyl chloride container is taken as 1.

Comparative Examples 1 and 2 are comparable to the present invention in terms of physical properties, but are expensive in terms of price.

Claims (1)

[Claims] 1. In a multilayer container consisting of a polyamide layer and a polyolefin layer, the polyolefin layer is made of a resin mixed with 80% by weight of polyolefin resin, 15% by weight of ionomer resin, and 5% by weight of graft-modified polyolefin with maleic anhydride. Extruded multilayer container.