KR102223789B1 - Manufacturing method of midsole with air bubble system - Google Patents

Abstract

The present invention relates to a manufacturing method of a midsole with an air bubble system applied. More specifically, unlike the prior art of installing a separate additional device inside a midsole for cushioning, it is possible to provide excellent cushioning properties such as air cushion while reducing product costs, manufacturing processes, and a defect rate, etc. by providing a manufacturing method capable of directly forming air bubbles inside a midsole. In addition, it is possible to form air bubbles in a regular shape and thereby more efficiently improve cushioning properties by providing a composition for a midsole suitable for the application of the air bubbles as described above.

Description

Manufacturing method of midsole with air bubble system {MANUFACTURING METHOD OF MIDSOLE WITH AIR BUBBLE SYSTEM}

The present invention provides a manufacturing method capable of directly forming an air bubble inside the midsole and a composition suitable therefor, unlike the prior art in which a separate additional device is installed inside the midsole for cushioning properties, thereby providing a product unit cost, a manufacturing process, and a defective rate. The present invention relates to a method for manufacturing a midsole to which an air bubble system is applied, which can provide excellent cushioning properties such as an air cushion while reducing the back.

Modern people enjoy various occupations and hobbies and wear shoes suitable for living environments such as trekking, mountaineering, walking, marine sports, and construction and industrial sites. Shoes in the past considered only the role of protecting the feet important, but depending on the change of consciousness and life, the shoes that disperse and remove the impact of the feet and act as a cushion became preferred.

In general, the structure of a shoe is composed of an upper, an insole, a midsole, and an outsole, and the midsole is the thickest and has an important function that is responsible for the comfort and cushioning of the foot.

To this end, various efforts have been made to improve the cushioning characteristics by designing the structure or shape of the midsole, improving the functionality of the material, or inserting a separate device in charge of cushioning, and as related prior art, Patent Documents 1 to 3 Etc.

However, the insert method of a separate device, which is installed to improve cushioning, has a nice design and excellent cushioning, but because of the method of bonding a new device, the problem of adhesion failure continues to occur, and time has passed due to the use of thermoplastic polyurethane material. It has a problem of discoloration along with it.

In addition, products with such performance have the disadvantage of forming an expensive product line because the unit price of the material is expensive and the process is difficult.

Patent Document 1: Republic of Korea Patent Publication No. 10-2001-0096902 "Air cushion type shoe midsole" Patent Document 2: Republic of Korea Utility Model Publication No. 20-0400116 "Shoe midsole with cushioning device" Patent Document 3: Republic of Korea Patent Publication No. 10-2010-0090047 "Shoe midsole airbag and shoes"

The present invention is to solve the above problems, and unlike the prior art in which a separate additional device is installed inside the midsole for cushioning properties, the present invention provides a manufacturing method capable of directly forming air bubbles inside the midsole. The task is to provide excellent cushioning properties such as air cushions while reducing unit cost, manufacturing processes, and defect rates.

In addition, by providing a composition for a midsole suitable for the application of air bubbles as described above, it is another object to enable the formation of air bubbles in a regular form and thereby improve cushioning properties more efficiently.

The present invention provides a method for manufacturing a midsole to which an air bubble system is applied, the steps of preparing a first-stage composition and a second-stage composition, respectively (S100); First-pressing the first-stage composition and the second-stage composition at a temperature of 60 to 80° C. to prepare a first-stage molded article and a second-stage molded article, respectively (S200); And after applying a releasing agent to the portion where the air bubble is to be formed in the first and second stage moldings, the first and second stage moldings are laminated to each other, and a second press at a temperature of 160 to 170°C. A method of manufacturing a midsole to which an air bubble system is applied, which comprises a step of crosslinking adhesion and foam molding (S300), as a means of solving the problem.

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The present invention provides a manufacturing method capable of directly forming air bubbles inside the midsole, unlike the prior art in which a separate additional device is installed inside the midsole for cushioning, thereby reducing product unit cost, manufacturing process and defect rate, etc. It can provide excellent cushioning properties such as air cushions, and furthermore, by providing a composition for midsole suitable for the application of air bubbles as described above, it is possible to form air bubbles in a regular form and thereby improve cushioning properties more efficiently. There is an effect that can be.

1 is a process flow diagram showing a method of manufacturing a midsole to which an air bubble system according to the present invention is applied
2 is a cross-sectional view schematically showing the structure of a midsole to which the air bubble system according to the present invention is applied

The present invention for achieving the above effect relates to a method of manufacturing a midsole to which an air bubble system is applied, and only parts necessary for understanding the technical configuration of the present invention are described, and the description of other parts distracts the gist of the present invention. It should be noted that it will be omitted so as not to be lost.

Hereinafter, a detailed description will be given of a method of manufacturing a midsole to which the air bubble system according to the present invention is applied.

The method of manufacturing the midsole to which the air bubble system according to the present invention is applied, as shown in FIGS. 1 and 2, includes a step (S100) of preparing a first-stage composition and a second-stage composition, respectively, and the first-stage composition and First-pressing the second-stage composition at a temperature of 60 to 80°C to prepare a first-stage molding and a second-stage molding, respectively (S200), and forming air bubbles from the first-stage moldings and the second-stage moldings After applying the releasing agent to the part to be formed, the first stage molding and the second stage molding are laminated to each other, and a second press at a temperature of 160 to 170° C. is performed to perform crosslinking adhesion and foam molding (S300).

Here, the air-bubble refers to an air filling space formed inside a shoe for the purpose of cushioning. Meanwhile, the release agent may be oil, silicone oil, surfactant, polyethylene glycol, polypropylene glycol, polyethylene wax, or the like, but is not limited thereto, and various known release agents may be used. In addition, it is preferable to use a mold having an intaglio or embossed pattern corresponding to the desired shape of the air bubble as the press mold.

Therefore, the present invention provides a manufacturing method capable of directly forming air bubbles inside the midsole, unlike the prior art in which a separate additional device is installed inside the midsole for cushioning, thereby reducing product unit cost, manufacturing process, and defect rate. While reducing, it is possible to impart excellent cushioning properties such as air cushions.

Here, if the manufacturing method and conditions are out of the above range, there is a concern that air bubbles may not be properly formed.

Next, a midsole composition suitable for the midsole to which the air bubble system according to the present invention is applied will be described in detail as follows.

The composition for a midsole according to the present invention is the first stage composition, based on 100 parts by weight of the thermoplastic polymer mixture in which 40 to 70% by weight of the first polymer and 30 to 60% by weight of the second polymer are mixed, and 3 to 5 parts by weight of a metal oxide Parts, 0.5 to 1.0 parts by weight of stearic acid, 10 to 20 parts by weight of a filler, 10 to 20 parts by weight of a tackifier, 3 to 5 parts by weight of a foaming agent, and 1 to 3 parts by weight of a crosslinking agent are mixed and used.

And as the second stage composition, based on 100 parts by weight of the thermoplastic polymer, 3 to 5 parts by weight of a metal oxide, 0.5 to 1.0 parts by weight of stearic acid, 10 to 30 parts by weight of a filler, 3 to 5 parts by weight of a foaming agent, and 1 to 3 parts by weight of a crosslinking agent. Mix and use part.

More specifically, the first polymer of the first stage composition is used alone or two or more selected from ethylene vinyl acetate copolymer, ethylene octene copolymer, or ethylene butene copolymer, and the second polymer is low-density polyethylene, high-density It is used alone or two or more kinds selected from polyethylene or olefin block copolymer.

Here, when the contents of the first polymer and the second polymer are out of the above range, there is a concern that the air bubbles are formed in an irregular shape, and the cushioning properties may be deteriorated.

In addition, the thermoplastic polymer of the second stage composition is used alone or in combination of two or more of an ethylene vinyl acetate copolymer, an ethylene octene copolymer, or an ethylene butene copolymer.

The metal oxide is added to control the crosslinking rate and accelerate the decomposition of the blowing agent, and zinc oxide, magnesium oxide, titanium oxide, calcium oxide, etc. may be used, but is not necessarily limited thereto, and various known metal oxides can be applied. Do. On the other hand, when the content of the metal oxide is out of the above range, there is a concern that the crosslinking rate and the foaming rate may decrease or the density of the foam may increase excessively.

The stearic acid is added to improve storage stability and processability, and if the content of stearic acid is out of the above range, there is a concern that it may not be easy to control processability.

The filler improves the mechanical strength and at the same time improves the durability of the midsole foam that supports the foot. Calcium carbonate, magnesium carbonate, silica, carbon black, talc, clay, etc. may be used. It is not possible to apply various known fillers. On the other hand, when the content of the filler is out of the above range, mechanical properties may be deteriorated, or agglomeration of the filler may occur, resulting in a decrease in dispersibility, resulting in foaming and crosslinking defects, which may make it difficult to form a product.

The tackifier allows the shape of the internal air bubble to be regularly formed during hot press molding and crosslinking bonding of the first and second molded products of different compositions. Kumaron-indene resin, terpene- Although phenolic resin, polybutene, or hydrogenated rosin ester may be used, it is not necessarily limited thereto, and various known tackifiers may be applied. On the other hand, when the content of the tackifier is out of the above range, there is a fear that the crosslinking adhesive strength between the first and second stage moldings decreases, or air bubbles are not formed therein and become clogged.

The foaming agent is a material that creates bubbles by blending with the thermoplastic polymer mixture of the present invention.Azodicarbonamide (ADCA), nitrosopentamethylene tetramine (DPT), toluene sulfonyl hydrazide (TSH), inorganic Alternatively, a capsule type foaming agent or the like may be used, but the present invention is not limited thereto, and various known foaming agents may be applied. On the other hand, if the content of the foaming agent is outside the above range, there is a concern that foaming may not be properly performed.

The crosslinking agent serves as a crosslinking role of each composition, and 2,5-bis(tertbutylperoxy)-2,5-dimethyl-3-hexene, ditertbutylperoxide, and 2,5-bis(tertbutylperoxy) -2,5-Dimethyl-hexene, dibenzoyl peroxide, bis(tertbutylperoxyisopropyl)benzene, butyl 4,4-bis(tertbutylperoxy)valerate, 1,1-bis(tertbutylperoxy) ) 3,3,5-trimethylchlorohexane, tertbutylperoxybenzoate, lauryl peroxide, dicumyl peroxide, etc. may be used, but are not necessarily limited thereto, and various known crosslinking agents may be applied. On the other hand, if the content of the crosslinking agent is out of the above range, there is a concern that foaming may not be properly formed or the foaming cell may burst.

On the other hand, in addition to the above-described materials of the present invention, conventional additives for foams used in this technical field, such as a crosslinking aid, may be further used.

Hereinafter, the present invention will be described in detail with reference to examples of the present invention, but the present invention is not necessarily limited only by the following examples.

1. Manufacture of midsole

(Examples 1 to 3 / Comparative Examples 1 to 3)

After preparing the first stage composition and the second stage composition respectively (S100), the first stage composition and the second stage composition are first pressed at a temperature of 60 to 80°C, respectively, to form the first stage molded article and the second stage molded article. After each manufacturing (S200), and after applying a releasing agent to the portion where the air bubble is to be formed in the first-stage molding and the second-stage molding, the first-stage moldings and the second-stage moldings are laminated to each other, and 160 to 170 It was prepared by crosslinking adhesion and foam molding by secondary pressing at a temperature of °C (S300). Here, the mixing ratio of each composition is as shown in [Table 1] below.

(Unit: parts by weight) division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 First stage
Composition First polymer
(Ethylene vinyl acetate) 40 60 70 80 60 60 Second polymer
(Low density polyethylene) 60 40 30 20 40 40 Metal oxide (zinc oxide) 3 3 3 3 3 3 Stearic acid One One One One One One Filler (silica) 10 20 10 10 5 10 Tackifier
(Kumaron Indensuji) 10 20 10 10 10 5 Crosslinking agent
(Dicumyl Peroxide) One One One One One One blowing agent
(Azodicarbonamide) 4 4 4 4 4 4 Second stage
Composition Ethylene vinyl acetate 100 100 100 100 100 100 Metal oxide (zinc oxide) 3 3 3 3 3 3 Stearic acid One One One One One One Filling agent (calcium carbonate) 10 10 10 10 10 10 Crosslinking agent
(Dicumyl Peroxide) One One One One One One blowing agent
(Azodicarbonamide) 4 4 4 4 4 4

2. Evaluation of the midsole

Specific gravity, hardness, tensile strength, elongation, elasticity, and air bubble shape of the midsoles according to the Examples and Comparative Examples were measured by the following test methods, and the results are shown in [Table 2] below.

(1) Specific gravity: Measured according to KS M 6519.

(2) Hardness: It was measured using an Asker C-type hardness tester in accordance with KS M 6518.

(3) Tensile strength and elongation: Measured by the method specified in KS M 6518 using a test piece with a thickness of about 3 mm. At this time, the number of test pieces used in the same test was set to 3, and if it deviated from the middle value of the measured value by 20% or more, it was calculated as an average value by measuring at least one additional time.

(4) Elasticity: In order to measure according to ASTM D 3574, it was measured under the following conditions using a ball drop type rebound resilience tester (TT502A).

Ball weight: 16.31g, drop height: 500mm, foam thickness: 10~15mm

(5) Air bubble shape: After first molding the first stage and second stage compounds manufactured through the above examples and comparative examples through a primary heat press under conditions of 60 to 80°C, respectively, at a temperature of 160 to 170°C. When the final molding was performed by the secondary heat press under the conditions, the shape of the air bubble inside the midsole was irregular or not formed and clogged, and the like was observed. There are 6 areas in which air bubbles are formed inside the midsole ◎, when air bubbles appear regularly in all areas ◎, when they appear somewhat irregularly in 5 areas ○, when air-bubbles are not formed in 4 or more areas and are blocked × Indicated.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 First stage
Specific gravity (g/cc) 0.212 0.215 0.210 0.201 0.205 0.203 Hardness (Type C, 22.5℃) 60 59 58 52 57 57 Tensile strength (kgf/cm ² ) 18.5 17.9 17.0 16.8 13.5 17.1 Elongation(%) 240 250 260 280 270 260 Elasticity (%, 22.5℃) 40 41 42 45 43 42 Second stage Specific gravity (g/cc) 0.198 0.198 0.198 0.198 0.198 0.198 Hardness (Type C, 22.5℃) 50 50 50 50 50 50 Tensile strength (kgf/cm ² ) 12.5 12.5 12.5 12.5 12.5 12.5 Elongation(%) 280 280 280 280 280 280 Elasticity (%, 22.5℃) 46 46 46 46 46 46 Air bubble shape ◎ ◎ ◎ × ○ ×

According to the progress of [Table 2], as a result of comparing the air bubble shapes of the midsoles prepared in Examples 1 to 3 and Comparative Example 1, Examples containing 30 to 60% by weight of low density polyethylene in the first stage composition The air bubble shape of the midsoles prepared in 1 to 3 appeared regularly. In the case of Comparative Example 1, when the composition of the first stage contains 20% by weight of low-density polyethylene, it is determined that the air bubbles between the first stage and the second stage are not formed and are blocked, and the content of the low-density polyethylene has a critical significance.

In the case of Comparative Example 2, when the content of silica, which is a filler, is 5 parts by weight per 100 parts by weight of the thermoplastic polymer mixture in the first stage composition, it can be seen that the mechanical strength falls by 20% or more. In addition, since it does not have durability enough to maintain the air bubbles between the first stage and the second stage, it is determined that the regularity of the air bubble shape is poor, and the content of the filler has a critical significance.

In the case of Comparative Example 3, when the content of the tackifier is 5 parts by weight with respect to 100 parts by weight of the thermoplastic polymer mixture in the first stage composition, crosslinking adhesion between the first and second stages is not effectively achieved during secondary hot press molding. It is determined that the internal air bubble space is not formed and collapsed, and the content of the tackifier has a critical significance.

As described above, the method of manufacturing a midsole to which the air bubble system according to the present invention is applied has been described through the above preferred examples and comparative examples, and its excellence has been confirmed, but those skilled in the art will be described in the following claims. It will be appreciated that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention.

Claims (3)

In the manufacturing method of the midsole to which the air bubble system is applied,
Preparing each of the first-stage composition and the second-stage composition (S100);
First-pressing the first-stage composition and the second-stage composition at a temperature of 60 to 80° C. to prepare a first-stage molded article and a second-stage molded article, respectively (S200); And
After applying a releasing agent to the part where the air bubble is to be formed in the first and second stage moldings, the first and second stage moldings are laminated to each other, followed by a secondary press at a temperature of 160 to 170°C. Cross-linking adhesion and foam molding step (S300); including,
The first-stage composition includes 3 to 5 parts by weight of metal oxide, 0.5 to 1.0 parts by weight of stearic acid based on 100 parts by weight of the thermoplastic polymer mixture in which 40 to 70% by weight of the first polymer and 30 to 60% by weight of the second polymer are mixed. , 10 to 20 parts by weight of a filler, 10 to 20 parts by weight of a tackifier, 3 to 5 parts by weight of a foaming agent, and 1 to 3 parts by weight of a crosslinking agent are mixed.
The second stage composition, based on 100 parts by weight of the thermoplastic polymer, 3 to 5 parts by weight of a metal oxide, 0.5 to 1.0 parts by weight of stearic acid, 10 to 30 parts by weight of a filler, 3 to 5 parts by weight of a foaming agent, and 1 to 3 parts by weight of a crosslinking agent Made by mixing,
The first polymer of the first stage composition is used alone or two or more selected from ethylene vinyl acetate copolymer, ethylene octene copolymer, or ethylene butene copolymer,
The second polymer of the first stage composition is used singly or two or more selected from among low-density polyethylene, high-density polyethylene, or olefin block copolymers, and
The thermoplastic polymer of the second stage composition is an ethylene vinyl acetate copolymer, an ethylene octene copolymer, or an ethylene butene copolymer. delete delete

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