KR20000004280A - Production method of foaming goods - Google Patents

Abstract

PURPOSE: A production method of foaming goods is provided to obtain foaming goods with high quality using a cheap and simple equipment. CONSTITUTION: A production method of foaming goods has the steps of: obtaining a solid inserting piece(2) by forming the foaming resin containing a foaming agent at a temperature lower than foaming temperature; preparing a foaming mold(10) having heaters(15a,15b) for heating inside of a foaming cavity; inserting the solid inserting piece into the foaming cavity of the foaming mold; heating the solid inserting piece inside of the foaming cavity at a temperature higher than the foaming temperature, and ripening for a specific ripening time, and then opening the foaming mold to obtain the foaming goods.

Description

Manufacturing method of foam product

The present invention relates to a method for producing a foamed product, and more particularly to a method for producing a foamed product that can obtain a foamed product of excellent physical properties by using a relatively inexpensive and simple structure of the equipment.

In the injection foaming method for providing a high quality foam product, a mixture of a resin material such as EVA and a foaming agent is injected into a predetermined cavity formed in a mold, and then aged for 6 to 10 minutes at a temperature of 170 to 190 degrees. After the mold is opened, a product which is expanded by about 30% or more than the cavity by the expansion of the blowing agent gas, that is, an injection foam product, is obtained. This injection foaming technique is a recently developed foaming technology, but has not yet reached the stage of general use, but has the advantage that it is possible to quickly and easily obtain a foamed product having a variety of shapes, dense structure and high-quality appearance, It is expected that the scope of application will be extended in the future.

However, this conventional injection foaming method has a disadvantage that a relatively expensive complex injection equipment for the injection of the material is required.

On the other hand, foam bead molding is another conventional foam molding method for obtaining a foam product of a dense structure. The molding method is to add a volatile solvent such as petroleum and ether to the PS beads made by the suspension polymerization of PS, and foam the foam particles sufficiently using a preliminary foamer, and then compress them by putting them in a mold. It is a method of molding. However, this conventional method is disadvantageous in that it is not environmentally friendly in that it requires the use of an organic solvent, and requires a compression molding mold having the same size as a pre-foaming machine and additionally requires a compression molding process after foaming. Therefore, the production efficiency for the input device is not large, and the quality of the foamed product produced is also less than that by the injection foaming method.

Accordingly, an object of the present invention is to provide a method for producing a foamed product that can obtain a high quality foamed product using a relatively inexpensive and simple equipment.

1 is a perspective view of an outsole for shoes as an example of a foam product;

2 is a cross-sectional view of the foam mold according to the present invention,

3 to 5 is a cross-sectional view of the injection mold sequentially showing the foaming process,

Explanation of symbols on the main parts of the drawings

1: outsole 2: solid insert

10: foam mold 11: upper die of foam mold

12: lower die 13: cavity

15a, 15b: heater

In order to achieve the above object, the manufacturing method of the foamed product of the present invention, the step of producing a solid insert containing the foaming agent and the main material foaming resin at the foaming temperature or less, the foam cavity and the foam cavity in the shape of the foamed article Providing a foam mold having a heater for heating the foam mold, inserting the solid insert into the foam cavity of the foam mold, heating the insert in the foam cavity above the foam temperature and maintaining the foam for a predetermined aging time, and then Opening the step of obtaining a foamed product.

Here, as the main material of the solid insert piece, polyurethane, polystyrene, EVA (Ethyl Vinyl Acetate), PVC, TPR (Thermoplastic Rubber) and the like can be used, and most preferably EVA.

In addition, the solid insert may be prepared in advance by a method of producing a sheet-like sheet by extrusion, injection, or roll, and then die cutting to a capacity suitable for the volume of the cavity of the mold. In particular, it is preferred to be produced by extrusion. When the solid insert is produced by extrusion, it is cut and used to a suitable size so that it can be inserted into a foam mold.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of an outsole for shoes that is an example of a foamed product that can be produced by the present invention. As can be seen from this figure, the outsole 1, which is a foamed product, has a sole shape of a shoe, especially a sports shoe as a whole, and has a shape in which a midsole, which is a foamed product that has been separated from each other in a conventional sports shoe, and an outsole made of rubber are integrated. Have

The foaming material of the outsole 1 is a foaming resin containing a foaming agent, and polyurethane, polystyrene, EVA (Ethyl Vinyl Acetate), PVC, TPR (Thermoplastic Rubber) and the like can be used, and the most preferable foaming resin is EVA.

In the present invention, a foamed resin containing a foaming agent is first produced under a foaming temperature of the foaming agent by extrusion, injection, or roll to produce a sheet-like sheet, and then die-cut to a capacity suitable for the volume of the cavity of the mold. After molding by a method of die cutting to obtain a solid insert having a predetermined size, it is inserted into the foam cavity of the foam mold, the foam mold is sealed, and heated and aged to prepare a foamed product.

Figure 2 shows a cross-sectional view of the foam mold for molding the outsole. In this figure, the injection cavity 13 in the foam mold 10 is simplified somewhat differently from the product of FIG. 1 for convenience of explanation and illustration.

The foam mold 10 has a lower die 12 in which an injection cavity 13 is formed on an upper surface thereof, and an upper die 11 that seals an upper portion of the cavity 13. These dies 12 and 14 are moved relative to each other in a vertical direction by a driving means (not shown) to be in contact with and separated from each other, thereby closing and opening the cavity 13. In the cavity 13 of the lower die 12, several ribs are formed to form the bottom pattern of the outsole 1. In addition, heaters 15a and 15b for heating the interior of the foam cavity 13 are provided in the upper die 11 and the lower die 12 of the foam mold 10, respectively.

3 to 5 sequentially show the foaming process of the outsole.

First, in the foam mold 10 in the state as shown in FIG. 2, the upper die 11 is opened by the driving means (not shown) to open the cavity 13, and the solid insert previously formed in the opened cavity 13 is inserted. Insert each piece (2). At this time, the solid insert 2 contains a foaming resin containing a foaming agent, and formed into a sheet shape by extrusion at a foaming temperature below the foaming mold 10 of a suitable size so that it can be inserted into the cavity (13) It is cut. Then, the upper die 11 and the lower die 12 are moved relative to close the cavity 13 as shown in FIG. When the cavity 13 is closed, the heaters 15a and 15b are operated to heat above the foaming temperature. At this time, the solid insertion piece 2 in the cavity 13 is first melted at the melting temperature to change into a liquid liquid having a high adhesiveness, so that an empty space is generated in the upper part of the cavity, but when the temperature rises above the foaming temperature, foaming gas is generated. As a result, the generated foaming gas completely fills the cavity 13 with the liquid material. That is, since the solid insert is melted and changed into a liquid state having high adhesiveness, even if a foaming gas is generated, the liquid phase and the foaming gas are not separated, and the foaming gas completely fills the liquid in the cavity 13. In the state where the foaming gas is dispersed and contained in the tacky liquid, the foamed resin, which is the main component of the tacky liquid, is aged by crosslinking reaction. Figure 4 shows a state in which the foamed resin is aged by crosslinking reaction. Therefore, after the foam mold is heated above the foaming temperature, the foam mold should be maintained without opening the foam mold at that temperature for a predetermined time. For example, when the foaming resin is EVA, the foaming mold is maintained to be aged by crosslinking at a temperature of about 170 to 190 degrees, which is a foamable temperature, for about 6 to 10 minutes.

Figure 5 shows the process of obtaining the foam product by opening the foam mold. After sufficient maturation time has elapsed, the upper die 11 is instantaneously moved up by a driving means (not shown). At this time, the material that has undergone sufficient crosslinking in the foam cavity 13 by expansion of the foaming gas while the foam cavity 13 is opened is expelled from the foam cavity 13 while rapidly expanding as shown in FIG. 5. The outsole 1, which is a product separated from the foam cavity 13, is shipped as a finished product through post-processing procedures such as subsequent trimming.

As described above, by foaming using a solid insert manufactured by extrusion, injection molding or the like, an outsole of almost the same quality as that produced by injection foam molding can be easily produced, and the manufacturing process is simple and efficient. As described above, the manufacturing method of the shoe outsole is described as an example of the present invention, but the manufacturing method can be widely applied to a foamed product having various shapes and functions as well as the outsole.

As described above, the present invention relates to a method for producing a foamed product that is foamed using a solid insert manufactured by extrusion, injection molding, and the like, and has a quality almost equivalent to that of a product manufactured by injection foaming molding according to the present invention. It is possible to manufacture foamed products, and to reduce costs and improve productivity by using a manufacturing equipment having a relatively inexpensive and simple structure.

Claims (4)

In the manufacturing method of the foamed product, Molding a foamed resin containing a foaming agent at a foaming temperature or less to obtain a solid insert piece, Forming a foam cavity corresponding to the shape of the foam product, and preparing a foam mold having a heater for heating the interior of the foam cavity; Inserting the solid insert into the foam cavity of the foam mold, and The method for producing a foamed product comprising the step of heating the solid insert in the foam cavity above the foaming temperature and maintaining for a predetermined aging time to open the foaming mold to obtain a foamed product. The method of claim 1, The foamed resin is a method for producing a foamed product, characterized in that the EVA. The method of claim 1, The solid insertion piece is a foamed product manufacturing method characterized in that it is produced by extrusion molding. The method of claim 1, The solid insert is manufactured by forming a sheet shape by a roll and then die cutting a solid insert having a capacity suitable for a mold volume.