JPS5829808B2 - Polyolefin resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for producing a polyolefin resin foam by an extrusion foaming method.

When extruding and foaming polyolefin resins, such as low-density polyethylene resins, high-density polyethylene resins, and polypropylene resins, very fine bubbles are often produced, making molding difficult, resulting in wavy foam and continuous bubbles. There have been cases where the product has been damaged.

The cause of this phenomenon is unknown, but when a relatively large amount of cell regulator is used in an attempt to control the bubbles to a relatively small size, a particularly large amount occurs, making extrusion molding of the foam difficult.

The present inventors completed the present invention as a result of various studies to solve this phenomenon.

In the present invention, based on 100 parts by weight of polyolefin resin,
This is a method for producing a polyolefin resin foam, characterized by adding 1 part by weight or more of an aromatic petroleum resin, mixing with a blowing agent, and extruding into atmospheric pressure.

The polyolefin resins used in the present invention include low-density polyethylene resin, high-density polyethylene resin, polypropylene resin, ethylene-propylene copolymer resin containing mainly ethylene and propylene and some copolymer components, ethylene-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer resin, Refers to methyl methacrylate copolymer resin, etc.

The aromatic petroleum resin used in the present invention is generally known as petroleum resin and is a low molecular weight resin produced as a by-product during the refining of cracked naphtha, and the main component is a low polymer mixture of styrene, vinyltoluene, indene, etc. It is said that

As a specific example, product name: Vetrozin (manufactured by Mitsui Petrochemical Co., Ltd.), product name: Niscolella (manufactured by Tonen Petrochemical Co., Ltd.)
, and products from several other companies are commercially available and known.

The amount of petroleum resin added must be 1 part by weight or more per 100 parts by weight of polyolefin resin.

If it is less than 1 part by weight, the effect of preventing abnormal foaming, which is the objective of the present invention, will not be sufficient.

The amount added can be arbitrarily selected from 1 part by weight or more; the greater the amount added, the greater the effect of preventing abnormal foaming and the larger the cell diameter, making it easier to control the bubbles with a cell control agent. become.

Another effect of adding petroleum resin is that the fluidity of the resin improves, making extrusion processing easier.

The blowing agents used in the present invention include hydrocarbons such as propane, butane, pentane, and hexane; Foaming agents known for extrusion foaming can be used.

Various cell control agents can be used to control the cell size of the extruded foam.

Further, colorants, various stabilizers and auxiliary agents may be used, and some other resins may be mixed for the purpose of increasing the amount or for other purposes.

Other benefits achieved by the method of the present invention include reduced shrinkage of the foam after molding and improved adhesion of adhesives and adhesives to the foam.

Example 1 11 parts of aromatic petroleum resin [trade name: Vetrozin (manufactured by Mitsui Petrochemicals)] was added to 100 parts by weight of low-density polyethylene.
2 parts by weight of Merck as a foam regulator and 0.5 parts by weight of calcium stearate as a lubricant were mixed and the mixture was supplied to a foam extrusion molding machine.

In the foaming extrusion molding machine, 1 resin is added to the kneaded resin.
20 parts by weight per 0.00 parts by weight of dichlorotetrafluoroethane were injected and kneaded, cooled to an appropriate temperature for foam extrusion, and a circular tubular foam was extruded through a die for tubular foam.

A good tubular foam with a cell diameter of about 0.4 mm was obtained.

The shrinkage ratio of the foam to the length immediately after extrusion, which indicates a decrease in length after the dimension has stabilized after a period of -week, was 3%.

The peel strength between the surface of the tubular body and a vinyl chloride adhesive film coated with an acrylic adhesive was measured at a speed of 400 mm/mm.
, if the ☆☆ wave is constant at 20℃, it will be 180? 720
It was mm.

Comparative Example 1 Example 1 was repeated without adding petroleum resin (trade name: Vetrogin).

Although a foam with very fine cells was obtained, the cross section of the foam was deformed into a triangular shape, making it impossible to mold the foam into a cylindrical shape.

Dimensional shrinkage was 12% and surface peel strength was 45 g/20 m7IL.

Example 2 330 parts of aromatic petroleum resin [trade name: Niscolella (manufactured by Tonen Petrochemical Co., Ltd.)] was added to 100 parts by weight of high-density polyethylene.
A good tubular foam with a cell diameter of about 0.6 mm was obtained in the same manner as in Example 1 except that the weight was added.

The shrinkage rate was 8%, and the peel strength was 200 g/20 peaks.

Comparative Example 2 Example 2 was repeated without adding aromatic petroleum resin (trade name: Niscolella).

As in Comparative Example 1, a foam with very fine cells was produced and the cross section was triangular, making it impossible to mold a cylindrical foam.

Examples 3 to 5 and Comparative Examples 3 to 4 Foams were obtained in the same manner as in Example 1 except for the compositions shown in the following table.

The shrinkage rate and peel strength of the foam are shown in the table below.

Claims (1)

[Claims] 1. A method for producing a polyolefin resin foam, which comprises adding 1 part by weight or more of an aromatic petroleum resin to 100 parts by weight of a polyolefin resin, mixing with a blowing agent, and extruding the mixture into atmospheric pressure.