KR100256180B1 - Injection foaming product and manufacturing method thereof - Google Patents

Abstract

PURPOSE: An injection-foamed material and its preparation method are provided, which injection foamed one has at least one different natured material area, thereby to allow the design and appearance to be varied easily. CONSTITUTION: The method comprises the steps of preparing the main foaming material containing a resin and a foaming agent; molding the aid material inserted one which comprises the main foaming material and a cross-linkable resin and has the different nature from that of the main foaming material; forming the area for the aid material inserted one in the cavity of a foaming mold; inserting the solid aid material inserted one into the cavity; charging the liquid main foaming material into the cavity; and maturing it at specific temperature for specific period, opening the mold and foaming it. The main foaming material has the different color, foaming density or both from those of the aid material inserted one.

Description

Injection foam having heterogeneous material region and manufacturing method thereof

The present invention relates to an injection foam having at least one foreign material region and a method of manufacturing the same.

In the injection foaming method, a mixture of a resin material such as EVA and a foaming agent is filled into a cavity having a predetermined shape formed in the mold, and then aged for 6 to 10 minutes at a temperature of 170 to 190 degrees. It refers to a method in which a product, that is, an injection foam, which is expanded about 30% or more than a cavity by gas expansion is obtained. This injection foaming technique is a recently developed foaming technology, which has not yet reached the stage of legalization, but has the advantage of being able to obtain foams of various shapes and properties quickly and easily. It is expected to expand widely.

Such injection foams are actively employed in footwear, such as mid-soles or out-soles of sports shoes, and in recent years, products in which midsoles and outsoles are integrated as a single injection foam. Is being developed. In conventional sports shoes, as shown in US Pat. No. 4,245,406, the sole of a shoe was manufactured by attaching a rubber outsole to the bottom surface of a midsole made of foam such as polyurethane. However, according to the above-described injection foaming method, since the midsole and the outsole can be manufactured integrally, the weight of the product can be reduced, the manufacturing cost can be significantly reduced, and the productivity can be significantly increased.

By the way, the injection foam is inevitably molded by a single material because it must inject a flowable material into a single cavity and undergo a crosslinking process for a predetermined aging time. Therefore, the product as a whole has a limitation that the physical properties such as color and density should be uniform throughout. Due to these limitations, various creative color designs cannot be applied, and thus there is a problem in that they cannot cope with various tastes of consumers. In addition, since the injection foam is itself a foam, the wear resistance is relatively lower than that of other injection molding products or rubber. To compensate for this, it would be desirable if at least a portion of the injection foam could be molded to have a different density or hardness.

Accordingly, the present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an injection foam having a heterogeneous material region having a different color, density, or the like and a method of manufacturing the same.

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

2 is a cross-sectional view taken along the line I-I of FIG.

3 is a cross-sectional view of a mold according to the present invention;

4 is a plan view of the lower die;

5 to 7 are cross-sectional views of a mold sequentially showing the injection foaming process.

Explanation of symbols on the main parts of the drawings

1: Outsole 2: Main material area

3: first submaterial region 4: second submaterial region

5: critical area 10: mold

12: lower die 13: cavity

14: upper die 15: first sub-material cavity area

16: first isolation rib 17: second secondary material cavity area

18: 2nd isolation rib 20: main material inlet

21: main material runner

The object of the present invention is to provide a main foam material containing a resin material and a blowing agent, and a material insert including a resin material capable of crosslinking reaction with the main foam material and having different physical properties from the main foam material. Molding, forming a predetermined material cavity area in the cavity of the foam molding die, inserting the material insert into the material cavity area, filling a liquid main foam material into the cavity; It is achieved by a method for producing an injection foam having a heterogeneous material region, which comprises maintaining at a predetermined reaction temperature for a predetermined aging time and then opening and foaming the mold.

Here, the main foaming material and the subsidiary material insert are preferably made of the same resin material, for example, EVA in order to increase mutual crosslinking reactivity, but consist of heterogeneous materials by differentiating at least one of the color and the foam density. can do.

In a preferred embodiment, the main material and the subsidiary material can be integrally foamed by containing the blowing agent in the submaterial insert and molding and inserting it below the foaming temperature of the blowing agent.

On the other hand, according to another field of the present invention, an injection foam having a heterogeneous material region molded by the above-described manufacturing method is provided.

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 an injection foam having a heterogeneous region, Figure 2 is a cross-sectional view taken along the line I-I of FIG. As can be seen from these figures, the outsole 1 has the shape of soles of shoes, in particular, sports shoes as a whole, and has a shape in which the midsole, which is a foam that has been separated from the conventional sports shoes, and the outsole made of rubber are integrated.

The outsole 1 has a main material region 2 covering almost most of the region, and a first submaterial region 3 and a second submaterial region 4 formed in a partial region of the bottom surface. The resin material of the main material region 2 and the submaterial regions 3 and 4 is selected to be capable of mutual crosslinking reaction when the resin materials in each region contact each other and react under predetermined conditions, and these are preferably the same as each other. Polyurethane, polystyrene, EVA (Ethyl Vinyl Acetate), PVC, TPR (Thermoplastic Rubber), and the like may be used as the foaming resin material for the main material region 2 and the subsidiary material regions 3 and 4, and EVA is most preferred. .

Subsidiary material regions 3 and 4 are inserted in the form of solids that have been preformed in the foam mold, and the main material region 2 is filled in a fluid liquid state and aged together for a predetermined time under predetermined temperature conditions and then foamed together. . The main material region 2 and the submaterial regions 3 and 4 are integrally joined by crosslinking reaction when aged under a predetermined temperature condition for foaming in the critical region 5, which is a border portion adjacent to each other.

The main material region 2 and the subsidiary material regions 3 and 4 may be configured so that the foam density, hardness, elasticity or color of the finished product is different by varying the content or type of blowing agent or additive blended with the resin material. Can be. As a result, it is possible to form submaterial areas 3 and 4 having high foaming density and high hardness in areas where wear resistance is required. In some cases, application of various color designs, for example, formation of color symbol marks, etc. It is possible to form subtone areas having different colors to obtain a two-tone color or a multitone color product.

3 is a cross-sectional view of a mold for forming an outsole having such a material region. In this figure, the cavity 13 in the mold 10 is simplified somewhat differently from the product of FIG. 1 for convenience of explanation and illustration.

The metal mold | die 10 has the lower die 12 in which the cavity 13 is formed in the upper surface, and the upper die 14 which seals the upper part of the cavity 13. As shown in FIG. 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.

4 is a plan view of the lower die 12. Referring to FIG. 3, the first sub-material for forming the submaterials 3 and 4 of the outsole 1 in the cavity 13 of the lower die 12 is shown. The cavity area 15 and the second sub material cavity area 17 are provided. These submaterial cavity regions 15 and 17 are partitioned from the remaining main material cavity regions by isolation ribs 16 and 18 formed to protrude a predetermined height from the bottom surface of the cavity 13. The lower die 12 is also provided with a main material runner 21 running from the main material inlet 20 and connected to the cavity 13 through a communication path formed in the upper die 14. As a result, the main foaming material supplied from the main material inlet 20 is supplied to the cavity 13 through the main material runner 21.

Hereinafter, referring to FIGS. 5 to 7, a manufacturing process of an outsole having a heterogeneous material region will be described in sequence.

First, in the mold 10 as shown in FIG. 3, the upper die 14 is opened by the driving means (not shown) to open the cavity 13, and the material cavity regions 15 and 17 in the opened cavity 13 are first opened. ), The material inserts 3a and 4a which are previously molded are inserted. Then, the upper die 14 and the lower die 12 are moved relative to close the cavity 13 as shown in FIG. When the cavity 13 is closed, the main foaming material is injected through the main material inlet 20, whereby the main foaming material is filled in the cavity 13 as shown in FIG. 6.

The main foaming material is a resin material such as polyurethane, polystyrene, EVA, PVC, TPR and the like as a main component, and contains a blowing agent, and is injected into the cavity 13 in a flowable liquid state. The submaterial inserts 3a and 4a are made of a main foaming material and a material capable of crosslinking reaction, preferably the same resin material as the main component, and are preformed solids by a molding method such as injection and extrusion. Is inserted in. It has been found that EVA is most preferred in practice as the resin material constituting the main components of the main foam material and the submaterial inserts 3a and 4a. Here, the submaterial inserts 3a and 4a may also contain a blowing agent. When the submaterial inserts 3a and 4a contain a foaming agent, the submaterial inserts 3a and 4a are molded below the active temperature of the blowing agent and inserted into the cavity 13 in an unfoamed state, and the main foaming material is used in the foaming process. Foamed with the foamed material. The main foaming material and the submaterial inserts 3a and 4a vary in the amount of the blowing agent or the type of the additive, and thus may exhibit different density, hardness or color after completion of the foam molding.

In the state in which the main foaming material is filled as shown in FIG. 6, the mold 10 maintains the cavity 13 for a aging time of about 6 to 10 minutes at a temperature of about 170 to 190 degrees, for example, in the case of EVA. During the aging time under these temperature conditions, each foam material undergoes an active crosslinking reaction on its own, while the surface of the material inserts 3a and 4a is activated in the region where the main foam material and the material inserts 3a and 4a are in contact with each other. Both materials are crosslinked with each other to be integrated.

After sufficient maturation time has elapsed, the upper die 14 is moved upward by a driving means (not shown). At this time, the foamed material which has undergone sufficient crosslinking in the cavity 13 by expanding the foaming gas while the cavity 13 is opened is expelled from the cavity 13 while rapidly expanding as shown in FIG. 7. The outsole 1, which is a product separated from the cavity 13, has submaterial materials 3 and 4 formed in an island shape in the main material area 2 by submaterial inserts 3a and 4a, and is subsequently processed such as trimming thereafter. It will be shipped to the finished product through the procedure. The submaterial regions 3 and 4 have a different color or hardness than the main material region 2 depending on the composition of the submaterial inserts 3a and 4a.

As described above, an outsole having heterogeneous regions can be easily manufactured in a single mold. Such a manufacturing method can be widely applied not only to the outsole, but also to injection-foaming products having various shapes and functions.

As described above, according to the present invention, an injection-foaming product having a heterogeneous material region having different physical properties, shapes, or colors, and which can be applied to a wide range of designs, can be obtained at low cost and easily.

Claims (5)

(correction) In the method for producing an injection foam having a heterogeneous material region, Preparing a main foaming material containing a resin material and a blowing agent; Molding a material insert comprising a resin material capable of crosslinking and reacting with the main foam material and having different physical properties from the main foam material; Forming a predetermined material cavity area in the cavity of the foam molding die; Inserting the solid submaterial insert into the submaterial cavity region; Filling the liquid main foam material into the cavity; A method of manufacturing an injection foam having a heterogeneous material region, the method comprising maintaining the mold at a predetermined reaction temperature for a predetermined aging time and then foaming the mold by opening the mold. The method of claim 1, And the main foam material and the submaterial insert are composed of the same resin material as a main component, and at least one of a color and a foaming density is different. The method of claim 2, And the resin material of the cavity is EVA. The method of claim 3, And wherein the submaterial insert contains a blowing agent and is molded at a foaming temperature of the blowing agent at or below. In the foam injection, An injection foam having a heterogeneous material region molded by the manufacturing method according to any one of claims 1 to 4.

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