KR20010003496A - Method for manufacturing foamed product with foaming resin pieces - Google Patents

Abstract

PURPOSE: A preparation method of foam product is useful for manufacturing high quality foam product with low production cost by using only one foam resin material in various metallic molds for casting the foam product. CONSTITUTION: A preparation method of foam product starts by a first step of obtaining a number of foam resin solid pieces formed below the foaming temperature. In a next step, the solid pieces are provided into a foam cavity. In a third step, by using a heater, the inner side of the cavity should be heated to reach a temperature above the foam temperature and maintain it for a certain time. Finally, the metallic mold is opened and the final foam product is obtained. The solid piece can be pellet type or flake type materials by forming the foam resin into elongated bar and cutting it to any desired size.

Description

Method for manufacturing foamed product with foamed resin pieces

The present invention relates to a method for producing a foamed product, and more particularly, to a method for producing a foamed product using a solid piece made of a foamed resin containing a foaming agent.

In order to manufacture high quality foam products, various methods such as an injection foaming method or a foam bead molding method are used. The injection foaming technique has the advantage of quickly and easily obtaining foam products having various shapes, dense structures, and high-quality appearance, but has a disadvantage of requiring a relatively expensive complicated injection equipment for injection of materials. In addition, the foam bead molding method is not environmentally friendly in that an organic solvent should be used, and a compression molding mold having the same size as a prefoaming machine is required, and an additional compression molding process is required after foam molding, resulting in a long cycle time and complicated process. There are disadvantages. Therefore, the production efficiency for the input device is not large and the quality of the foamed product produced is not as good as that of the injection foaming method.

In order to solve these problems, the inventor of the present invention has applied for a method for producing a new foamed product in Korean Patent Application No. 1998-25712 filed on June 30, 1998. In the foamed product manufacturing method disclosed in the above patent application, first, a solid insert containing a foaming agent and a foamed resin as a main material is prepared at a foaming temperature or lower, and the solid insert is inserted into the foaming cavity of the foam mold and then heated. The foamed product can be obtained by opening the foam mold after maintaining the heating state for a predetermined aging time. Here, the insert is manufactured by extrusion molding, or manufactured by forming a sheet shape using a roll, and then die cutting to a capacity suitable for the mold volume. According to this, it is possible to obtain a foamed product of the physical properties equivalent to those of the product produced by the injection foaming method using a manufacturing equipment having a relatively inexpensive and simple structure.

By the way, according to the method for producing a foamed product by the applicant of the present application as described above, there is a disadvantage that the solid insert is cut in advance to have an appropriate size according to the volume of the foam cavity. Therefore, in order to produce various kinds of foam products, various kinds of inserts having different sizes according to the volume of the foam cavity in the respective foam molds for manufacturing the foam products should be prepared in advance. Accordingly, it is inconvenient to perform an additional process for producing various kinds of sheet-like inserts having various sizes, and to separately manage inserts having different sizes.

Accordingly, it is an object of the present invention to make it possible to use one type of foamed resin material in various types of foaming molds without having to separately manufacture the foamed resin inserts inserted into the foaming cavity according to the volume of the foaming cavity. It is to provide a method for producing a foamed product that can obtain a high-quality foamed product at a lower cost.

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

Figure 2 is a perspective view of a pellet applied to the foamed product manufacturing method according to the present invention,

3 is a cross-sectional view of the foam mold,

4 to 6 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 pellets

10: foam mold 11: upper die of foam mold

12: lower die 13: cavity

15a, 15b: heater

The above object is, according to the present invention, in the method for producing a foamed product using a foaming mold having a heater for forming a foaming cavity corresponding to the shape of the foamed product and for heating the inside of the foaming cavity, the foaming agent-containing foaming Obtaining a large amount of solid piece molded of the resin at a foaming temperature or less; Receiving a predetermined amount of the solid piece in the foam cavity in the foam cavity; Heating the inside of the foam cavity to a foaming temperature or more by using the heater and maintaining the predetermined maturing time; And it is achieved by the method for producing a foamed product comprising the step of obtaining the foamed product by opening the foam mold.

Here, the solid piece has a shape of a pellet formed by molding a foamed resin into a long rod, and then cutting it by a predetermined length, or a flake obtained by cutting a molded article of the foamed resin obtained in a suitable shape by a predetermined size. Can have In addition, the foamed resin is preferably made of EVA.

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, first, the foamed resin containing the foaming agent is molded at the foaming temperature of the foaming agent or less. At this time, the foamed resin is produced in a large amount of solid pieces. Solid pieces can be made in a variety of ways. For example, the foamed resin may be made into a sheet shape by extrusion, injection, or roll, and then finely cut and made into flakes, or may be prepared as individual particulate pellets. Alternatively, as shown in Fig. 2, a plurality of pellets 2 may be obtained by extruding the foamed resin in a long line and then cutting it continuously. In consideration of manufacturing workability, the solid piece preferably has the shape of a pellet. Hereinafter, the molding using the pellet will be described as an example.

It is preferable that the pellets 2 used as the solid piece have a diameter and a length of about 4 mm to 1 cm in consideration of manufacturing efficiency, molding speed and the like. The size of the pellets 2 is not critical to the present invention, but if it is too small, the moldability of the pellets is poor, and if too large, the heating time for melting the pellets may be long.

Finely chopped pellets 2 are accommodated in the foam cavity of the foam mold. At this time, pellets 2 of a quantity corresponding to the volume of the foam cavity are inserted into the foam cavity. The operator may adjust the quantity of the pellets 2 according to the volume of the foam cavity, and may also allow the appropriate quantity of pellets 2 to be automatically inserted using a separate automatic feeding mechanism.

Figure 3 shows a cross-sectional view of the foam mold for molding the outsole. In this figure, for convenience of explanation and illustration, the shape of the injection cavity 13 in the foam mold 10 is simplified to be somewhat different from the shape of the product of FIG.

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, 11 are moved relative to and separated from each other in the vertical direction by driving means (not shown), 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.

4 to 6 sequentially show the foam molding process of the outsole.

First, pellets (2) are manufactured by using a foaming resin containing a blowing agent as described above. In the foam mold 10 in the state as shown in FIG. 3, the upper die 11 is opened by the driving means (not shown) to open the cavity 13, and the appropriate number of solid pellets 2 are opened in the opened cavity 13. Insert). 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 granular solid pellets 2 in the cavity 13 are first melted at the melting temperature to change into a liquid phase having high adhesiveness, so that an empty space is formed at the upper part of the cavity, but when the temperature rises to be above the foaming temperature, foaming is performed. As the gas is generated, the generated foaming gas completely fills the cavity 13 with the liquid material. That is, since the solid pellet 2 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 liquid is completely filled in the cavity 13 by the foaming gas. In the state where the foaming gas is dispersed and contained in the tacky liquid, the foamed resin, which is a main component of the tacky liquid, is aged by crosslinking reaction.

Figure 5 shows a state in which the foamed resin is aged by crosslinking reaction. After the foam mold is heated above the foaming temperature, the foam mold should be maintained at that temperature without opening. For example, when the foaming resin is EVA, the foaming mold is maintained to be aged by crosslinking at a temperature of about 160 to 190 degrees, which is a foamable temperature, for about 6 to 10 minutes.

Figure 6 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 expanding the foaming gas while the foaming cavity 13 is opened is released from the foaming cavity 13 while expanding rapidly as shown in FIG. 6. 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, 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, according to the present invention, it is possible to apply to various types of foaming molds by simply controlling the number of pellets because the foaming molding using a pellet-shaped pellets prepared in advance with a foaming resin containing a blowing agent. In addition, high quality foam products can be easily produced and the manufacturing process is simple and efficient.

Claims (4)

In the method for producing a foamed product using a foam mold having a heater for heating the inside of the foam cavity to form a foam cavity corresponding to the shape of the foam product, Obtaining a large amount of solid pieces molded at a foaming temperature containing a foaming agent at a foaming temperature or less; Receiving a predetermined amount of the solid piece in the foam cavity in the foam cavity; Heating the inside of the foam cavity to a foaming temperature or more by using the heater and maintaining the predetermined maturing time; And Method for producing a foamed product comprising the step of obtaining the foamed product by opening the foam mold. Obtaining a large amount of solid pieces molded at a foaming temperature containing a foaming agent at a foaming temperature or less; Receiving a predetermined amount of the solid piece in the foam cavity in the foam cavity; The method of claim 1, The obtaining of the solid piece comprises the steps of molding the foamed resin into a long rod, and forming a pellet by cutting the molded article of the foamed resin by a predetermined length. The method of claim 1, Said solid piece has a shape of flakes. The method according to any one of claims 1 to 3, The foamed resin is a method for producing a foamed product, characterized in that the EVA.