KR102503005B1 - Method for making a dual midsole - Google Patents

Abstract

The present invention relates to a method for forming a double midsole of a shoe.
The present invention includes the steps of preparing an EVA flat plate, cutting the EVA flat plate to separate the lower midsole model, forming a spandex adhesive layer on the upper surface of the lower midsole model, and the lower midsole model on which the spandex adhesive layer is formed. In a mold consisting of a lower mold and an upper mold for a lower midsole, forming a lower midsole in a form in which the thickness is reduced as the edge extends upward compared to the inside, and the upper mold for the lower midsole is separated from the lower mold Moving to the upper midsole molding line with a conveyor, injecting polyurethane into the inside surrounded by the edge of the lower midsole located inside the cavity of the lower mold, and covering the upper surface of the injected polyurethane with a TPU film on it approaching and rotating the upper mold for the upper midsole so that the upper midsole made of foamed polyurethane material is integrally molded under the interposition of the spandex adhesive layer, and the step of separating the molded double midsole by opening the upper mold for the upper midsole. .
The spandex adhesive layer interposed on the bonding surface between the lower midsole made of EVA and the upper midsole made of polyurethane according to the present invention has the advantage of excellent initial adhesiveness and excellent aging adhesiveness.

Description

Double midsole molding method {METHOD FOR MAKING A DUAL MIDSOLE}

The present invention relates to a midsole located in the middle along with an outsole and an insole constituting the bottom material of a shoe, and in particular, through a single mold, two layers having different physical properties are integrated while maintaining high initial and aging adhesiveness It relates to a double midsole molding method to be molded into a modified midsole.

Most shoes consist of an outsole located between the sole of the wearer's foot and the ground, and an upper that extends upward from the circumference of the outsole to cover the top of the foot. It is common to have a triple layer of an outsole, an insole in contact with the wearer's sole, and a midsole located between them and mainly responsible for a cushioning function.

At this time, in order to smoothly exhibit the cushioning function of the midsole, not only elasticity to absorb loads or shocks, but also lightness and durability are required. Considering these characteristics, polyolefin elastomer (POE: Polyolefin Elastomer-based EVA (Ethylene Vinyl Acetate), polyurethane, and foamed polyurethane are being applied to shoe midsoles.

However, in view of the fact that a midsole made of only a single material has limitations in expressing sufficient functions, Patent Registration No. 10-1021289 describes the above-described requirements of a rigid polyurethane midsole having a central concave portion surrounded by an outer periphery through a double foam molding method. By forming a double midsole with a soft polyurethane joint member laminated on the groove part, when the shoe wearer lands, the hard polyurethane midsole and the soft polyurethane joint member around the concave groove are compressed and deformed in different behaviors, so that the load is sequentially absorbed, there is.

On the other hand, Patent Registration No. 10-1231548 is an invention related to a mold for molding a midsole in which double foam layers are integrally molded, and on one side of a lower mold having a molding space thereon, the middle cover mold is rotatably hinged The upper cover mold is rotatably coupled to the lower end of the lower mold to supply foam to the pre-molded lower midsole, and the upper cover mold is rotated toward the lower mold for pressurization. A mold for integrally molding a double midsole so that the upper midsole is formed by doing so has been disclosed.

However, in the double midsole obtained by the above two inventions, the boundary of the double layer, that is, the adhesive force at the bonding surface is weak, so that partially lifted parts are found. Problems are pointed out. In addition, the double midsole is unsatisfactory in terms of lightness, durability, and comfort except for shock absorption, as the constituent materials constituting the upper and lower midsoles are made of foamed polyurethane of substantially the same material with only slightly different modulus of elasticity. There are criticisms, and improvements are being made in this regard.

The present invention was invented with the disadvantages and problems pointed out in relation to the conventional double midsole for shoes in mind, and is composed of upper and lower midsole materials having different physical properties, so that shock absorption and light weight characteristics are all in one In addition, the adhesive layer of spandex material is interposed on the adhesive surface of the upper and lower midsole, so that the initial adhesiveness on the joint surface of the upper and lower midsole as well as the aging adhesiveness is increased. It is an object of the invention to provide a.

The object of the present invention is to prepare an EVA flat plate, cut and separate a foot-shaped lower midsole model from the EVA flat plate, form a spandex adhesive layer on the upper surface of the separated lower midsole model, Forming a lower midsole in a form in which the thickness is reduced while the edge extends upward compared to the inside by molding the lower midsole model on which the spandex adhesive layer is formed in a mold composed of a lower mold and an upper mold for the lower midsole; Moving the upper mold for the lower midsole of the lower mold to the upper midsole molding line by a conveyor in a state where the upper mold for the lower midsole is separated; injecting polyurethane into the inside of the moved lower mold surrounded by the edge extension of the lower midsole; In a state where a thermoplastic polyurethane (TPU) film is covered on the upper surface of the polyurethane, the upper mold for the upper midsole is approached and rotated from above so that the upper midsole is integrally molded with the spandex adhesive layer interposed, and for the upper midsole This is achieved through a double midsole molding method comprising the steps of opening the upper mold and separating the molded double midsole.

A series of steps for the double midsole molding method of the present invention will be described in detail in order.

First, flat EVA is prepared. At this time, the flat EVA is preferably foamed EVA in terms of weight reduction, and the thickness is preferably 15 to 30 mm.

Next, the flat EVA is cut into a shape of a foot sole, separated from the lower midsole model, and a spandex adhesive layer is formed on the upper surface thereof. The formation of the spandex adhesive layer is performed by applying a liquid adhesive to either the lower surface of the spandex fabric or the upper surface of the flat EVA so that the two members can be bonded. On the other hand, it is also possible to take out a lower midsole model in the form of a foot sole with spandex fabric attached to the entire upper surface of the flat EVA.

The spandex fabric forming the spandex adhesive layer has high elasticity and tear strength, and particularly has excellent adhesion to polyurethane.

Subsequently, in a state where the lower midsole model to which the spandex adhesive layer is adhered is placed in the lower mold, the upper mold for the lower midsole rotatably coupled to the lower mold is rotated toward the lower mold so that the pressurized state is maintained in the middle of the mold itself. The lower midsole having a fin-shaped outer periphery in which the thickness is reduced while the edge extends upward compared to the inner side by sequential operation of the provided heating and cooling devices is formed.

As is known, since EVA material, especially foamed EVA, has low tear strength, wrinkles or partial tears are likely to occur on the surface when it is deformed under a load. As the adhesive layer made of spandex fabric with excellent elasticity and elasticity is formed, the molded lower midsole completed by reinforcement of the spandex adhesive layer during the molding process accompanied by shape change due to pressure and heat in the mold as described above does not have any surface defects or damages. Without this, molding is performed in a predetermined intended shape.

The lower midsole molded in this manner is surrounded by an upwardly extending outer periphery, and serves as a formwork when liquid polyurethane is injected to form the upper midsole later.

Next, the upper mold for the lower midsole is separated from the lower mold, and the lower mold in which the molded lower midsole remains in the cavity is moved to the upper midsole molding line on a conveyor, after which the upper mold for the lower midsole is The upper mold for the upper midsole is coupled to the removed position.

Subsequently, liquid polyurethane is injected into the concave inside of the lower midsole surrounded by the upwardly extending outer periphery in the lower mold, and the upper mold for the upper midsole is covered so that the polyurethane is foamed so that the upper midsole is integrally molded on the lower midsole. It will be done.

On the other hand, in the case of a molded product obtained by molding EVA, a POE-based material, in a mold, the surface is smooth due to the nature of the material, and soapy water contacted during the molding process remains slippery, so washing is required, and UV irradiation using a UV device is required. It is known that adhesion, especially with polyurethane, is obtained only when the surface is activated through

In this way, when polyurethane is foamed on the EVA surface without being activated by UV irradiation, satisfactory adhesion at the contact surface cannot be expected due to the difference in physical properties between the two materials. However, the problem is that when the surface of EVA is irradiated with UV, the EVA composition shrinks, swells, and in some cases is distorted during the irradiation process, so it is not realistic to expect improved adhesion between EVA and polyurethane through UV irradiation. does not exist.

Accordingly, in the present invention, in order to form an integrated midsole through smooth bonding between a lower midsole made of EVA material and an upper midsole made of foamed polyurethane formed thereon, a spandex adhesive layer is formed at the junction of the two midsole parts having different material characteristics. The intervening configuration is the primary feature of the invention.

That is, in the present invention, the upper midsole made of polyurethane material is not directly bonded on the contact surface with the lower midsole made of EVA material, but the foamed polyurethane material is placed on the surface of the spandex adhesive layer bonded to the upper surface of the lower midsole made of EVA material through an adhesive. Since the upper midsole of is molded by adhesion, the lower midsole and upper midsole, which are made of different materials, are integrated with improved adhesive strength through the spandex adhesive layer interposed therebetween.

In particular, since spandex fabric has excellent initial adhesion with polyurethane as well as excellent aging adhesion and has elasticity equal to or higher than that of polyurethane, complete adhesion is not achieved even in some of the entire adhesion area during the mold molding process, or it takes time after adhesion. As time passes, the phenomenon of spreading the adhesive part does not occur.

On the other hand, during the upper midsole molding process, polyurethane is injected and the upper mold for the upper midsole is approached and rotated in a state where the upper midsole is covered with a TPU film, so that the surface of the upper midsole is sealed by the TPU film and moisture permeation is prevented.

When the molding of the upper midsole by the foaming of the polyurethane is completed, the upper mold for the upper midsole is opened, the molded double midsole is separated from the mold, and the TPU film extending to the edge is cut and removed according to the method of the present invention A double midsole is obtained.

As described above, in the method of the present invention, spandex with excellent adhesion to polyurethane, including elasticity and elasticity, on the adhesive surface between the lower midsole made of EVA and the upper midsole made of polyurethane, which has different material characteristics and has low adhesiveness to each other. With the spandex adhesive layer made of fabric interposed therebetween, the upper midsole made of foamed polyurethane is integrally molded on top of the lower midsole made of EVA, so that the initial adhesiveness and aging adhesiveness at the junction of the two midsoles are excellent.

In addition, in the present invention, in forming the double midsole, the lower midsole is molded using the lower mold, and the molded lower midsole is left as it is without demolding from the original lower mold and transferred to the upper midsole molding line to form the lower midsole. By injecting and foaming liquid polyurethane into the mold provided on the upper part so that the upper midsole is integrally molded, the double midsole molding process can be simplified and the manufacturing cost can be reduced.

1 to 5 show the step-by-step process of the double midsole molding method according to the present invention,
1 is an EVA flat plate and a lower midsole model separated therefrom;
2 (a) and (b) are the states before and after the spandex fabric is attached to the lower midsole model,
Figure 3 shows that the lower midsole on which the spandex adhesive layer is formed is inserted into the lower mold,
Figure 4 (a) shows the lower midsole molded in the lower mold,
(B) shows the appearance by separating the molded lower midsole,
5(a) shows that the upper midsole is integrally molded with the lower midsole in the lower mold,
(B) is a perspective view of the molded double midsole,
(C) is a cross-sectional view of AA line of (B).

The above object of the present invention and the specific points including the detailed configuration and control conditions performed in each step from the initial process to the completion process of the double midsole are schematically showing the molding method according to one embodiment of the present invention. It will be clearly understood through the following description with reference to.

First, FIG. 1 is the first step of the double midsole molding method according to the present invention, in which the lower midsole model 2a cut into a sole shape is separated from the EVA flat plate 1 as shown. The EVA plate 1 is foamed EVA and has a thickness of 18 mm.

Next, (a) of FIG. 2 is the state before attaching the spandex fabric (3a) to the surface of the lower midsole model (2a) separated from the EVA flat plate (1), and (b) is the lower midsole model after the bonding is completed. (2a) shows a state in which the spandex adhesive layer 3 is formed on the surface. At this time, the spandex fabric (3a) is a synthetic fiber made of elastic yarn of polyurethane fiber that is generally sold on the market, and among them, an adhesive is applied to the bottom surface that is adhered to the surface of the lower midsole model (2a). The upper surface, which is made of a smooth surface and later adhered to the upper midsole made of polyurethane, has a fine wavy surface that slightly reveals the thickness of the fiber thread.

Next, FIG. 3 shows a state immediately before the lower midsole model 2a to which the spandex adhesive layer 3 is attached is inserted into the lower mold 10. The lower midsole model 2a in the shown state is lower mold 10 It is seated in the cavity 11 of At this time, the size and shape of the bottom surface of the cavity 11 tends to coincide with the lower midsole model 2a adjacent thereto, but the inner surface of the cavity 11 may have a gap with the side of the corresponding lower midsole model 2a. there is.

After the lower midsole model 2a is seated inside the lower mold 10, the upper mold 20 for the lower midsole is hinged so that the molding protrusion 21 faces the cavity 11 of the lower mold 10 Compressive force is applied to the lower midsole model 2a in the cavity 11 by allowing the approach rotation to occur. At this time, the movement of the upper mold 20 for the lower midsole is stopped when the forming surface of the molding protrusion 21 comes into contact with the cavity forming surface of the lower mold 10, and the pressing contact state of these two molds fixes the two molds. It is maintained by mounting fixtures.

In such a press-contact state between the molds, the heating device provided in the mold itself is heated to, for example, about 150 ° C, so that the lower midsole model 2a made of EVA material located therein is deformed After that, Cool air was supplied through the cooling passage of the mold to cool the mold and the molded lower midsole.

On the other hand, (a) of FIG. 4 separates and rotates the upper mold 20 for the lower midsole after the series of molding processes from the lower mold to the lower midsole model 2a in FIG. It shows the lower midsole 2 molded inside the cavity 11 of the lower mold, and (B) shows the lower midsole of (A) separated to show the appearance. In the actual work according to the present invention, the molded lower midsole 2 in the lower mold 10 is not separated as shown in (b) of FIG. 4 .

As shown in (b) of FIG. 4, the lower midsole (2), which has been molded, has a reduced overall thickness compared to the lower midsole model (2a) before molding, and the edge part extends upward in a pin shape to wrap around the inside. Forming a mold.

One of the noteworthy facts is that the spandex adhesive layer 3 on the surface of the lower midsole 2, which has undergone significant deformation, becomes one body with the bonding surface of the lower midsole 2 made of EVA attached to its bottom and is deformed together. It can be seen that it has been elongated.

Next, the upper mold 20 for the lower midsole is separated from the lower mold 10, and the lower mold 10 in which the molded lower midsole 2 remains is moved to the upper midsole molding line by using a conveyor. After that, the upper mold for the upper midsole is mounted at the position where the upper mold for the lower midsole is removed.

Subsequently, liquid polyurethane is injected into the concave inside of the lower midsole 2 surrounded by the upwardly extending outer periphery in the lower mold 10, and the upper part for the lower midsole is covered so that the polyurethane is foamed so that the upper midsole becomes the lower midsole. Molding is done integrally on top.

In (a) of FIG. 5, after the foaming of the polyurethane injected into the upper part of the lower midsole in the lower mold and molding into a predetermined shape is completed, the upper mold 30 for the upper midsole is tilted and the upper midsole 4 is placed on the upper part of the lower midsole. This integrally molded double midsole is shown, (b) is a perspective view of the molded double midsole (5), and (c) is a cross-sectional view along line A-A of (b). Although not shown in the drawings, a TPU film is closely adhered to the upper surface of the upper midsole 4 to prevent moisture from penetrating into the inside through the surface of the upper midsole.

As shown in (c) of FIG. 5, the cross-section of the upwardly extending portion where the edge of the double midsole 5, which has been molded, becomes thinner, is centered on the inner spandex adhesive layer 3 (or the upper and lower surfaces). E) It can be seen that the lower surface of the upper midsole and the upper surface of the lower midsole are deformed and stretched as one body with the spandex adhesive layer (3).

1. EVA Reputation
2a. lower midsole model
2. Lower midsole
3a. spandex fabric
3. Spandex adhesive layer
4. Upper midsole
5. Double midsole
10. Lower mold
11. Cavity
20. Upper mold for lower midsole
21. Forming projections
30. Upper mold for upper midsole

Claims (4)

In the double midsole molding method of shoes;
Preparing an EVA reputation;
Cutting the EVA flat plate to separate the lower midsole model;
Forming a spandex adhesive layer on the upper surface of the lower midsole model;
In a state where the lower midsole model on which the spandex adhesive layer is formed is positioned in the lower mold, the upper mold for the lower midsole rotatably coupled to the lower mold is rotated toward the lower mold to maintain a pressurized state. A heating device provided in the middle mold itself. Forming a lower midsole having a fin-shaped outer periphery in which the thickness is reduced as the edge extends upward compared to the inner side by sequential operation of the cooling device and the cooling device;
Separating the upper mold for the lower midsole from the lower mold and moving the lower mold in which the molded lower midsole remains in the cavity to an upper midsole molding line by a conveyor;
coupling the upper mold for the upper midsole to the position where the upper mold for the lower midsole of the moved lower mold is removed, and injecting polyurethane into the concave inside surrounded by the edge of the lower midsole located inside the cavity of the lower mold;
In a state where the TPU film is covered on the upper surface of the injected polyurethane, the upper mold for the upper midsole is rotated approaching therefrom so that the upper midsole made of foamed polyurethane is integrally molded under the interposition of the spandex adhesive layer, and
A double midsole molding method characterized in that it consists of the step of opening the upper mold for the upper midsole and separating the molded double midsole. The double midsole molding method according to claim 1, wherein the EVA flat plate is a foamed EVA flat plate. delete A double midsole characterized in that it is molded according to any one of claims 1 and 2 above.

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