METHOD OF RECYCLING INSOLE SCRAP, PULVERIZED INSOLE SCRAP, AND FOAM FOR SHOE MANUFACTURED THEREBY

Abstract

A method of recycling a large amount of insole scrap stack is proposed. The method includes forming a plate-shaped stack made of flat-plate-shaped foam and woven fabric, separating an insole scrap stack from the plate-shaped stack, and forming a pulverized insole scrap having an average diameter of 0.05 to 0.7 mm by cool-pulverizing or freeze-pulverizing the insole scrap stack at 10° C. or less. The pulverized insole scrap may be used for manufacturing foam.

Claims

1. A method of recycling an insole scrap, the method comprising: forming a plate-shaped stack by disposing woven fabric on an upper surface of flat-plate-shaped foam in layers; separating the plate-shaped stack into a sole-shaped insole stack and an insole scrap stack from which the insole stack is removed; and forming a pulverized insole scrap having an average diameter of 0.05 to 0.7 mm by cool-pulverizing or freeze-pulverizing the insole scrap stack at 10° C. or less, wherein the pulverized insole scrap is for manufacturing foam.

2. The method of claim 1, further comprising: after the forming of the pulverized insole scrap, forming a foaming mixture in which foamable resins, foaming additives, and the pulverized insole scrap are mixed with each other; and forming a foam product by foaming the foaming mixture.

3. The method of claim 2, wherein, at the forming of the foaming mixture, 20 to 60 parts by weight of the pulverized insole scrap is mixed with 100 parts by weight of the foamable resins.

4. The method of claim 3, wherein the foam product obtained at the forming of the foam product is a foam for a shoe in a form of a flat plate.

5. Foam for a shoe manufactured by a method of recycling an insole scrap of claim 2.

6. A pulverized insole scrap for manufacturing foam, wherein the pulverized insole scrap has an average diameter of 0.05 to 0.7 mm by cool-pulverizing or freeze-pulverizing an insole scrap stack at 10° C. or less, the insole scrap stack being obtained by disposing woven fabric on an upper surface of flat-plate-shaped foam in layers and forming a plurality of sole-shaped openings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a perspective view of a plate-shaped stack in accordance with an embodiment of the present disclosure.

[0025] FIG. 2 is a diagram illustrating a state in which the plate-shaped stack of FIG. 1 is separated into an insole stack and an insole scrap stack.

[0026] FIG. 3 is an enlarged photograph of a pulverized insole scrap obtained by the present disclosure.

[0027] FIG. 4 is an enlarged photograph of foam obtained by Experimental example 1.

[0028] FIG. 5 is an enlarged photograph of foam obtained by Experimental example 4.

DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings such that those skilled in the art easily can practice the present disclosure. However, the present disclosure may be implemented in various ways without being limited to particular embodiments described herein. Further, in order to make the present disclosure clear, parts that are not related to the present disclosure will be omitted in the drawings. Like reference numerals denote like components throughout the specification.

[0030] It will be understood that the term “comprise” when used in this specification, specifies the presence of stated components but does not preclude the presence or addition of other components, unless otherwise defined.

[0031] FIG. 1 is a perspective view of a plate-shaped stack in accordance with an embodiment of the present disclosure, FIG. 2 is a diagram illustrating a state in which the plate-shaped stack of FIG. 1 is separated into an insole stack and an insole scrap stack, FIG. 3 is an enlarged photograph of a pulverized insole scrap obtained by the present disclosure, FIG. 4 is an enlarged photograph of foam obtained by Experimental example 1, and FIG. 5 is an enlarged photograph of foam obtained by Experimental example 4.

[0032] Each step of the present disclosure will be described in detail.

[0033] (1) Step of Forming Plate-Shaped Stack

[0034] As shown in FIG. 1, a woven fabric 20 is disposed in layers on an upper surface of a flat-plate-shaped foam 10, thus forming a plate-shaped stack 100. The woven fabric 20 is integrated with the flat-plate-shaped foam 10 via an adhesive or an adhesive film.

[0035] The flat-plate-shaped foam 10 is made by foam molding various materials such as polyurethane (PU) or ethylene-vinyl acetate (EVA), and is used as foam for the insole. To this end, a wide variety of technologies have been known.

[0036] (2) Step of Separating Insole Scrap Stack

[0037] As shown in FIG. 2, the plate-shaped stack 100 of FG. 1 is separated into a plurality of (four in this embodiment) sole-shaped insole stacks 110, and an insole scrap stack 120 obtained by removing the insole stacks 110.

[0038] In this embodiment, four insole stacks 110 are separated from one plate-shaped stack 100, but the number of the insole stacks may be changed in various ways.

[0039] The insole stack 110 is a part that will become an insole product, but is not the subject of the present disclosure.

[0040] A sole-shaped opening 121A is formed in the insole scrap stack 120 by removing the insole stack 110. In this embodiment, four openings 121 are formed.

[0041] In the related art, the insole scrap stack 120 is discarded. However, in the present disclosure, the insole scrap stack 120 is recycled.

[0042] Since the step of forming the plate-shaped stack and the step of separating the insole scrap stack are substantially equal to those of the related art, a detailed description thereof will be omitted herein.

[0043] (3) Formation of Pulverized Insole Scrap

[0044] The insole scrap stack 120 is subjected to cool-pulverizing or freeze-pulverizing at 10° C. or less, thus obtaining the pulverized insole scrap having the average diameter of 0.05 to 0.7 mm.

[0045] If the insole scrap stack 120 is subjected to simple pulverizing at room temperature, a pulverized insole scrap may form fluff in the woven fabric due to pulverizing heat generated during the simple pulverizing. When the foam is made of the pulverized insole scrap that has a non-uniform state while the fluff is formed, a defective quality such as a large amount of air bubbles may occur.

[0046] According to the present disclosure, in order to obtain the pulverized insole scrap having an overall uniform state without forming the fluff in the woven fabric, the insole scrap stack 120 is subjected to cool-pulverizing or freeze-pulverizing at 10° C. or less.

[0047] The term “cool-pulverizing” refers to an operation of pulverizing the insole scrap stack 120 while cooling it at the temperature of 10° C. or less using a chiller. Even if the pulverizing heat is generated when the insole scrap stack 120 is pulverized, this is absorbed by the chiller, thus preventing fluff from being formed in the woven fabric due to the pulverizing heat.

[0048] The term “freeze-pulverizing” generally refers to an operation of cooling waste resources, such as waste tires, waste rubber, or waste plastic, using a cooling source such as liquid nitrogen or liquefied natural gas at a very low temperature for pulverizing, and then pulverizing the waste resources into fine powder using a pulverizer.

[0049] The freeze-pulverizing method is used in other technical fields. However, the freeze-pulverizing method is merely applied to other technical fields because it is difficult to perform a pulverizing operation at room temperature.

[0050] The present disclosure adopts the cool-pulverizing method or the freeze-pulverizing method so as to obtain homogeneous pulverized matter without forming the fluff in the woven fabric of the pulverized insole scrap.

[0051] Meanwhile, when the average diameter of the pulverized insole scrap is less than 0.05 mm, energy required for pulverizing is excessively increased.

[0052] Furthermore, when the average diameter of the pulverized insole scrap is more than 0.7 mm, a large amount of air bubbles is formed in the foam made of the pulverized insole scrap, thus causing a defective quality.

[0053] (4) Step of Preparing Foaming Mixture

[0054] A foaming mixture is prepared by mixing foamable resins, foaming additives, and the pulverized insole scrap.

[0055] It is preferable that 100 parts by weight of the foamable resins be mixed with 20 to 60 parts by weight of the the pulverized insole scrap.

[0056] When 20 or more parts by weight of the pulverized insole scrap is mixed with 100 parts by weight of the foamable resins, tearing strength may be remarkably increased. When less than 20 parts by weight of the pulverized insole scrap is mixed with 100 parts by weight of the foamable resins, there is little change in tearing strength.

[0057] When more than 60 parts by weight of the pulverized insole scrap is mixed with 100 parts by weight of the foamable resins, it is difficult to perform a dispersing operation and a molding operation and consequently it is impossible to substantially obtain the foam.

[0058] The type and amount of the foamable resins and the foaming additives may be applied in various ways.

[0059] (5) Step of Forming Foam Product

[0060] The foaming mixture prepared in the foaming mixture preparing step is foamed, thus obtaining a foam product.

[0061] The foam product may have the shape of a flat plate, and may be foam for a shoe, particularly foam for an insole.

[0062] In the case of obtaining the foam for the shoe by the present disclosure, the insole scrap stack is pulverized in a shoe manufacturing plant to be recycled in an insole manufacturing process, and the insole scrap stack produced in the process of manufacturing the insole using the foam for the insole may be recycled again in the insole manufacturing process.

[0063] The foam product may not only be used as foam for a shoe, such as foam for an insole, foam for a midsole, foam for an outsole, but also may be used as foam for various purposes, such as industrial and architectural use.

EXPERIMENTAL EXAMPLE

Experimental Example 1

[0064] 6700 g of Ethylene Vinyl Acetate (EVA) resin and 2000 g of polyethylene (PE) resin as foamable resins, 600 g of cross-linking promoter, 600 g of foaming agent, and 100 g of cross-linking agent as foaming additives are mixed to form a foaming mixture.

[0065] Thereafter, the foaming mixture is mixed in a kneader, and the mixture passing through the kneader is dispersed and transformed into a sheet by a roll process and is cut to a proper size. Subsequently, a material in the shape of the cut sheet is put into a press, and heat is applied for a predetermined time to foam and thereby attain a foam product.

Experimental Examples 2 to 5

[0066] In a plate-shaped stack obtained by arranging foam manufactured by Experimental example 1 and woven fabric in layers, four sole-shaped openings are formed and the insole scrap stack is obtained. This is subjected to cool-pulverizing or freeze-pulverizing to have the average diameter of 0.5 mm, so that the pulverized insole scrap is obtained. FIG. 3 is an enlarged photograph of the pulverized insole scrap.

[0067] Subsequently, the pulverized insole scrap, Ethylene Vinyl Acetate (EVA) resin and polyethylene (PE) resin as the foamable resins, the cross-linking promoter, the foaming agent, and the cross-linking agent as the foaming additives are mixed as in the following Table 1 to form the foaming mixture, and then the corresponding foaming mixture is mixed, dispersed, and foamed, so that the foam product is obtained.

TABLE-US-00001 TABLE 1 Experi- Experi- Experi- Experi- Experi- mental mental mental mental mental example example example example example Type (unit: g) 1 2 3 4 5 foamable EVA 6700 6400 6200 5500 4700 resins resin PE resin 2000 1800 1500 1200 1000 Total 8700 8200 7700 6700 5700 Pulverized insole — 410 1540 2680 3420 scrap (8200 × (7700 × (6700 × (5700 × (diameter 0.5 mm) 5/100) 20/100) 40/100) 60/100) Cross-linking 600 600 600 600 600 promoter Foaming agent 600 600 600 600 600 Cross-linking 100 100 100 100 100 agent Total 10000 9910 10540 10680 10420

[0068] In other words, Experimental examples 2 to 5 show that 100 parts by weight of the foamable resins is mixed with 5 parts by weight, 20 parts by weight, 40 parts by weight, and 60 parts by weight of the pulverized insole scrap, respectively. When 100 parts by weight of the foamable resins is mixed with more than 60 parts by weight of the pulverized insole scrap, it is difficult to perform the dispersing operation and the molding operation and thereby it is impossible to obtain foam. Thus, experimental results therefor were excluded.

[0069] The hardness, the tensile strength, the elongation, and the tearing strength for foam manufactured by each of Experimental examples 1 to 5 were tested and their results are shown in the following Table 2.

TABLE-US-00002 TABLE 2 Experimental Experimental Experimental Experimental Experimental Type example 1 example 2 example 3 example 4 example 5 Hardness 29 29 30 31 31 (Asker C) Tensile Strength 15 16 16 16 16 (kg/cm2) Elongation (%) 250 250 250 250 250 Tear Strength 4.8 6.2 6.7 6.8 6.7 (kg/cm)

[0070] As seen in Table 2, it can be seen that the tear strength of Experimental examples 3 to 5 according to the present disclosure is remarkably improved as compared with that of Experimental example 1. It is to be understood that, when 100 parts by weight of the foamable resins is mixed with 20 or more parts by weight of the pulverized insole scrap, the tear strength of the foam is improved due to fibers forming the woven fabric.

[0071] FIG. 4 is an enlarged photograph of foam according to Experimental example 1, and FIG. 5 is an enlarged photograph of foam according to Experimental example 4.

[0072] While the present disclosure has been particularly described with reference to exemplary embodiments shown in the drawings, it will be understood by those of ordinary skill in the art that the exemplary embodiments have been described for illustrative purposes, and various changes and modifications may be made without departing from the spirit and scope of the present disclosure as defined by the appended claims. Accordingly, embodiments of the present disclosure are intended not to limit the technical idea of the invention but to illustrate the technical idea. For example, each component described as being a single one may be embodied in a distributed manner, and similarly, components described as being distributed may be embodied in a combined form.

[0073] It is to be understood that the scope of the present disclosure is defined solely by the following claims and equivalences thereof.

[0074] As described above, the present disclosure may be used to recycle an insole scrap produced as a by-product in a process of manufacturing an insole, and may be used to manufacture foam for a shoe with the insole scrap.