JPH0135730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold crosslinking foam molding method and an apparatus therefor, and more particularly to a mold crosslinking foam molding method and apparatus suitable for obtaining molded articles of complex shapes.

Conventionally, foamable thermoplastic resin was the main component,
A method of producing a soft raw material by adding a foaming agent and a crosslinking agent to it, kneading it, and molding it with a mold to obtain a foamed molded product is generally known.

The conventional molding method will be explained below with reference to FIGS. 1 to 3. First, as shown in FIG. A soft solid raw material 1 is created by kneading at a certain temperature, and before this raw material 1 is cooled and hardened, it is deformed to fit the shape of the mold 2, and after cooling and hardening, It is put into a mold 2 heated to about 170°C and pressurized with a hydraulic heat press 3 as shown in FIG. After the chemical reaction is completed, the mold 2 is opened. Then, the crosslinked raw material 1
As shown in Figure 3, it naturally expands and becomes the specified product 4.
becomes.

The conventional molding method is as described above, but this type of molding method has the following problems.

In other words, in the conventional method, it is necessary to transform the raw material that has been kneaded and softened into a shape that fits the mold before it cools and solidifies. It has the disadvantage that it must be cooled and hardened, which is not easy to work with, and that it takes a long time to harden the raw material and to preheat in the mold, so it takes a lot of time to mold. In addition, thick-walled items or items with uneven thickness cannot be heated uniformly due to poor thermal conductivity during the preheating time in the mold, and therefore cannot be foamed to the inside. There is also the drawback that when heated to high temperatures, the outer surface hardens and deteriorates, making it impossible to obtain a sufficient molded product. Furthermore, in the past, it was necessary to deform the raw material to fit the mold, and it was not possible to process the raw material into a complicated shape, so there was also the drawback that products with complicated shapes could not be molded.

The present invention was made in order to solve these conventional problems, and its purpose is to be able to mold thick-walled items, uneven-walled items, or items with complicated shapes, and to significantly reduce the time required for molding work. An object of the present invention is to provide a mold cross-linking foam molding method and an apparatus therefor, which can be shortened to a mold crosslinking foam molding method.

The present invention will be explained below with reference to embodiments shown in FIGS. 4 to 6.

In the figure, 11 is a first mold formed from an upper mold 11a and a lower mold 11b.
A second mold 12 is disposed below the mold 1 and communicates with the first mold 11 via a passage 13. The second mold 12 includes an upper mold 12a connected to the lower mold 11b of the first mold 11, and a hydraulic heat press 1 that expands and contracts vertically to pressurize the raw material 14 in the first mold 11.
5 and a lower mold 12b connected to the lower mold 12b. The raw material 14 pressurized in the first mold 11 by the press 15 flows into the second mold 12 through a passage 13, as shown in FIG. Further, the second mold 12 is designed so that by reducing the size of the hot press 15, the upper and lower molds 12a and 12b can be separated and opened as shown in FIG.

On the other hand, the raw material 14 is mainly composed of a foamable thermoplastic resin such as ethylene-vinyl acetate copolymer, to which appropriate amounts of a blowing agent, a crosslinking agent, a polyethylene resin, calcium carbonate, etc. are added as additives, This is then kneaded at a temperature of about 80°C to make it soft, and this raw material is melted in the first mold 11 preheated to about 170°C, and then transferred to the second mold 12 by pressure from the hot press 15. It is now being pumped. When the second mold 12 is opened after the chemical reaction is completed, the raw material 14 naturally expands into a specified product 16 as shown in FIG. 6.

Next, the molding method according to the present invention will be explained.

First, the main component is a foamable thermoplastic resin such as ethylene-vinyl acetate copolymer, an appropriate amount of a foaming agent and a crosslinking agent are added as additives, and if necessary, polyethylene resin and calcium carbonate are added. A soft raw material 14 is prepared by adding and kneading at a temperature of 80 to 90°C.

Next, this raw material 14 is put into the first mold 11 which has been preheated to about 170° C. by an appropriate preheating means, and is pressed by a hot press 15. Then, the raw material 14 is melted by the heat from the first mold 11 and flows into the second mold 12 through the passage 13 due to the pressure from the hot press 15, where a crosslinking reaction occurs.

After the chemical reaction is completed, the heat press 15 is scaled down and the second
When the mold 12 is opened, the crosslinked raw material 14 naturally expands due to the action of the foaming agent, and a product 16 shown in FIG. 6 is obtained.

As explained above, according to the molding method and apparatus according to the present invention, the following effects can be obtained.

(1) There is no need to transform the kneaded raw materials to fit the mold, and the work is extremely easy as it is only necessary to put the required amount of raw materials into the first mold.

(2) Conventionally, the kneaded raw materials could only be molded after being cooled and solidified, but in the present invention, the heated raw materials can be used as they are, so the preheating time in the mold can be shortened. The separation molding time can be shortened.

(3) Since heated raw materials are used as they are, even thick or unevenly-walled items can be heated and melted uniformly in the mold, resulting in high-quality products that are sufficiently foamed to the inside and have no deterioration on the outer surface. of products are obtained.

(4) Since there is no need to transform the raw material to fit the mold, it is possible to mold products with complex shapes.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are explanatory views showing a conventional molding method, and FIGS. 4, 5, and 6 are schematic views showing an example of an embodiment of the present invention. 11...first mold, 12...second mold, 14...
...Raw material, 15...Heat press, 16...Product.

Claims (1)

[Scope of Claims] 1. A soft raw material containing a foamable thermoplastic resin as a main component and kneaded with a blowing agent and a crosslinking agent is put into a preheated first mold and melted. The second mold is pressurized and communicates with the first mold.
A mold crosslinking foam molding method characterized by pressure feeding into a mold, opening a second mold after completion of a chemical reaction, and obtaining a foamed product through natural expansion. 2. A first mold into which a solid raw material whose main component is a foamable thermoplastic resin and which is formed by adding a blowing agent and a crosslinking agent and kneading is put into it, and a raw material melted in the first mold by heating. a pressurizing mechanism that pressurizes the
a second mold that communicates with the first mold and into which the molten and pressurized raw material flows from the first mold; and after the chemical reaction of the raw material that has flowed into the second mold is completed, the second mold is opened. A mold crosslinking foam molding method comprising: an opening mechanism for naturally expanding the raw material.