JPS5843084B2 - Simultaneous molding and coating method for plastic molded shoe soles - Google Patents

Description

[Detailed Description of the Invention] Conventionally, there are thermoplastic plastics such as soft vinyl chloride, nylon, ABS, ethylene ethyl acrylate copolymer resin, polyethylene, and ethylene vinyl acetate copolymer resin as plastic sole materials. ,
ABC, polyethylene, etc. were used only in a small part of shoes.

However, in recent years, resources such as wood and cork have become scarce, and vinyl chloride and ethylene ethyl acrylate copolymer resin (hereinafter referred to as E
(abbreviated as EA), ethylene vinyl acetate copolymer resin (hereinafter referred to as E
(abbreviated as VA), polyurethane.

Plastics such as polystyrene have begun to be used in the soles of shoes to take advantage of their properties.

In recent years, fashionable thick-soled shoes have been attracting particular attention, and this trend is becoming more and more popular.

However, from the viewpoint of moldability, such as production speed, investment efficiency of molds, physical properties, fashionability, and increasing the quality of shoes, the molded shoe soles taken out from the molding machine cannot be used immediately as shoe soles, and are coated with paint. Generally, coatings are applied by coating or gluing thinly sliced cork sheets, gluing leather, gluing leather, gluing cloth, baking, gluing rubber or rubber sponge, etc.

The labor costs required for such secondary processing account for a considerable proportion of the shoe price.

The inventors have focused on and studied this problem, and have discovered an innovative method that allows these coatings to be applied during molding, thereby eliminating the secondary coating process described above all at once.

That is, when using an extruder such as injection molding or extrusion molding, the plastic is heated above its softening temperature and injected into a mold through an injection port in a molten state. The coating material is attached to the side wall of the mold cavity, that is, the side of the sole of the shoe, or the bottom of the cavity, that is, the sole of the shoe.

For these coating materials, an adhesive having adhesive strength between the core plastic and the coating material is melted and applied to a thickness of 10 to 150 .mu.m on the side that contacts the inner surface of the cavity before the mold is attached to the mold plate.

After that, by injecting molten plastic through the injection port to fully fill the mold cavity, the adhesive will melt due to the pressure at the time of injection and the temperature of the molten plastic, increasing its miscibility with the molten plastic, and gradually cooling down. It solidifies by solidifying.

After this, the molded product that has solidified to the point where no deformation occurs is taken out from the mold.

It was discovered that this molded product completely fulfilled the intentions of the inventors, and was a groundbreaking shoe sole with no differences compared to conventional shoe soles and an extremely simplified process. .

In this case, we have also found that foamed molten plastic injected into the mold is more effective in applying internal pressure to the cavity after injection.

Also, the plastics used are polyethylene and EEA.

EVA, polystyrene, ABS, or a mixture of these plastics blended with rubber are effective, and the covering materials include cork sheet, leather rubber sheet, synthetic leather, rubber sponge, and natural leather.

Sponges such as EVA, cloth, etc. are effective.

Also, as an adhesive, it is solid at room temperature and has a softening point of 8.
Adhesives between 0°C and 170°C are preferred, especially those based on EVA.

Hereinafter, this will be explained in more detail in Examples.

Example 1 80 parts of ethylene vinyl acetate copolymer resin, 2, 20 parts of polybutadiene, 1.0 part of blowing agent, 0.3 part of liquid paraffin
(4), natural leather (B), rubber sponge (B'), 40 parts of ethylene vinyl acetate copolymer resin, 40 parts of ester gum, 10 parts of Vistanex, 10 parts of paraffin wax. , antioxidant 0
．． Adhesive with a softening point of 92°C (C
), these were used as the materials used.

The procedure was as follows: First, adhesive "C" was applied to the back surface of "rBj rB'" in a molten state, and immediately cooled.

The coating thickness of this product was about 60μ. Then IBj
Cut the side of the sole of the shoe to the expanded size and attach it to the side of the mold, and do the same for "B'", and after attaching it to the bottom of the mold,
Two minutes after rAJ was injected into a mold at a temperature of 150 to 160°C using an injection molding machine, the molded product was taken out.

This was a shoe sole material in which "B" was completely adhered to the outer wall of a plastic core, and "B'" was completely adhered to the bottom.

In order to check the degree of adhesion, we measured the peel strength and found that 2
The width was 6.4 kg/2 Smvt, and I was confident that there would be no practical problems.

[Brief explanation of drawings]

Figures 1 to 3 are schematic diagrams showing one example of a molded shoe sole molded according to the present invention. Figure 1 is an external view of the shoe, Figure 2 is a sectional view of the covering material, and Figure 3 is a sectional view of the sole. be. 1: side covering material, 2: original wave covering material, 3: niblastic core, 4: molten plastic injection port contact area, 5: adhesive layer.

Claims (1)

[Claims] 1. In the method of molding shoe sole materials using a plastic molding machine, a coating material coated with an adhesive having a softening point of 80 to 170°C is inserted into a mold, and then a plastic molding machine is used to mold the sole material to 80°C. A method for simultaneously coating plastic shoe sole materials, characterized by injecting plastic heated and melted above ℃ to fill the inside and simultaneously combining it with a coating material via an adhesive.