JPH0120177B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyvinyl chloride resin foam molded article. Foaming methods for thermoplastic resin materials include mechanical foaming, which involves turning the resin material into a liquid state and stirring it vigorously to disperse and mix fine air bubbles into the molded product, or by heating or other means to easily decompose the resin material. , a foaming agent that generates a large amount of gas upon decomposition is mixed into the resin material in advance,
A chemical foaming method is known in which the foaming agent is decomposed during molding to generate gas bubbles, which are then dispersed in the molded product.

However, the mechanical foaming method is mainly used as a means of manufacturing sponge rubber or foam rubber with open cells, and special measures are required to uniformly disperse the cells when used for thermoplastic resin materials. do. Furthermore, according to this method, most of the bubbles are dispersed in the product as so-called open cells, so there is a drawback that the product feels relatively hard to the touch.

On the other hand, with the chemical foaming method, it is easier to disperse and arrange cells in the product as closed cells than with the mechanical foaming method, so it is possible to foam and mold various thermoplastic resin materials such as polyvinyl chloride resin. It is widely used as a tool. On the other hand, the chemical foaming method causes the blowing agent to decompose, so it is necessary to maintain the thermoplastic resin material at a high temperature close to its decomposition temperature for a certain period of time during molding. Alternatively, deterioration of physical properties such as burning is likely to occur.

The present invention is intended to solve the above-mentioned problems observed in conventional foam molding methods for thermoplastic resin materials, and to produce foam molded products without deterioration of physical properties.

Therefore, the main object of the present invention is to provide an industrial method for producing a foam molded product having a good texture in which fine closed cells are uniformly dispersed singly or in a mixed state with open cells. The goal is to establish a means to do so.

Another main object of the present invention is that by selecting thermally expandable microcapsules as a blowing agent that can be foamed at a lower temperature than the molding temperature of resin materials by conventional methods, heat can be applied without reducing the physical properties of the final product. An object of the present invention is to provide a novel foam molding method for foam molding a plastic resin material.

Yet another object of the present invention is that foam molding is possible at lower temperatures compared to conventional methods.
The object of this invention is to establish a means for manufacturing polyvinyl chloride resin foam molded products that is easy to manage the process and has an excellent thermal energy saving effect.

These objects of the present invention are to form a plastisol by blending thermally expandable microcapsules as a low-temperature foaming agent in a polyvinyl chloride paste resin in an amount of 40 parts or less based on the weight of the paste resin;
Polyvinyl chloride resin foam molding, the gist of which is to promote gasification of the thermally expandable microcapsules by the latent heat during gelation after heating and melting the plastisol, and perform foam molding under reduced temperature conditions. This can be achieved industrially advantageously by adopting a manufacturing method for the product.

The heat-expandable microcapsules used in the present invention are heat-expandable containers made of microspheres with a particle size of about 10 to 30 μm, which contain a low-boiling solvent in a film or shell of a thermoplastic polymer material. The form may be a single capsule, a multinucleated capsule, a multinucleated capsule, a double capsule, a capsule cluster, or a self-contained capsule. The shell of thermally expandable microcapsules generally has a wall thickness of 10μ or less, more preferably 7μ or less, but needs to be thermoplastic and have good gas barrier properties, so for example, chloride It is formed from a copolymer mainly composed of vinylidene and acrylonitrile.

When carrying out the method of the present invention, it is desirable that the thermally expandable microcapsules be blended in an amount of 40 parts or less, more preferably 20 parts or less, based on the weight of the polyvinyl chloride paste resin.

Further, the foam molding temperature varies depending on the composition of the polyvinyl chloride paste resin, the amount of plasticizer added, etc., but it is desirable to adjust it to approximately 170°C or less, more preferably 160°C or less. on the other hand,
Since the heating time during molding, together with the molding temperature, acts as a kind of thermal history on the molded product, it is necessary to determine its suitable range in relation to the molding temperature. From this point of view, it is desirable to set the upper limit of the heating time during foam molding to approximately 200 seconds or less, more preferably 180 seconds or less.

EXAMPLES In order to facilitate understanding of the present invention, Examples are described below, but the gist of the present invention is not limited by these Examples.

(Example 1) A polyvinyl chloride paste resin having a molding temperature of 180° C. in a conventional foam molding method, an appropriate amount of a plasticizer, a stabilizer, and the paste resin 100
A plastisol was prepared by mixing 5 parts by weight of heat-expandable microcapsules and Micropearl F-40 (trade name of a low-temperature foaming agent manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.). This plastisol was stirred to form a gel, then supplied onto a coating film with a thickness of 2 mm, and foam-molded by a low-pressure method under heating conditions of 160° C. for 180 seconds. The resulting product has a foaming ratio of 3 times and a soft suede-like feel due to the mixture of closed cells formed by foaming the thermally expandable microcapsules and open cells formed by mechanical stirring. Furthermore, since the foam molding temperature was lower than that of conventional methods, no deterioration in physical properties such as decomposition or burning was observed in the resin material.

(Example 2) The polyvinyl chloride paste resin described in Example 1, an appropriate amount of a plasticizer, a stabilizer, an azo blowing agent, and 5 parts by weight of thermally expandable microcapsules per 100 parts by weight of the paste resin. Micro Pearl F
-30 (trade name of a low-temperature foaming agent manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.) was mixed to create plastisol. This plastisol was heated to 140°C for 60 seconds to gel, and then supplied onto a coating film with a thickness of 0.3 mm.
Foam molding was carried out by a normal pressure method under heating conditions of 150°C and 180 seconds.

The obtained product is produced by heating and melting the plastisol.
Gasification of the low-temperature foaming agent is promoted using the latent heat during gelation, and foam molding is performed at a lower temperature than the known foam molding process, so the product has good physical properties similar to the product of Example 1. It was equipped with

In addition, the product according to this example had fine closed cells dispersed over the entire cross section of the molded product, and a smooth suede-like surface condition and a soft touch were obtained.

As is clear from the above explanation, the method of the present invention not only improves the feel of foamed molded products, but also has the advantage that the molded products do not deteriorate in physical properties because they are carried out at lower temperatures compared to conventional methods. have In addition, lowering the temperature of the foam molding process also brings side effects such as ease of process control and reduction of thermal energy.
The contribution to this industry is extremely large.

Claims (1)

[Claims] 1 Form a plastisol by blending thermally expandable microcapsules as a low-temperature foaming agent into a polyvinyl chloride paste resin in an amount of 40 parts or less based on the weight of the paste resin, and after heating and melting the plastisol,
A method for producing a polyvinyl chloride resin foam molded article, characterized in that gasification of the thermally expandable microcapsules is promoted by latent heat during gelation, and foam molding is carried out under reduced temperature conditions.