KR100523563B1 - A manufacturing method for mid-sole and unit-sole of shoe with improving traction - Google Patents

Abstract

The present invention relates to a method for manufacturing a shoe midsole and an integrated window for improved traction characteristics, and more specifically, by selectively using a crosslinking agent to specifically configure the base component, the optimal crosslinking is expressed according to the selection of the base component The foamed kneaded material showing various characteristics is prepared in sheet or pellet form, and is put in a mold for press at room temperature or preheated, and the foam is completed by press molding of compression molding or transfer molding under a constant temperature and pressure to perform thermal remolding process. It relates to the manufacturing method of shoe midsole or integral window without going through it, and it is possible to create various added values such as shortening process and reducing waste materials, improving environmental problems and economic benefits from raw material loss reduction compared to the existing thermal reshaping method. Polymers and additives which are disadvantages caused by the molding method There is no limitation of the present invention relates to a method for manufacturing shoe soles and integral soles capable of high physical properties.

Description

A manufacturing method for mid-sole and unit-sole of shoe with improving traction}

The present invention relates to a method for manufacturing a shoe midsole and an integrated window for improved traction characteristics, and more specifically, by selectively using a crosslinking agent to specifically configure the base component, the optimal crosslinking is expressed according to the selection of the base component The foamed kneaded material showing various characteristics is prepared in sheet or pellet form, and is put in a mold for press at room temperature or preheated, and the foam is completed by press molding of compression molding or transfer molding under a constant temperature and pressure to perform thermal remolding process. It relates to the manufacturing method of shoe midsole or integral window without going through it, and it is possible to create various added values such as shortening process and reducing waste materials, improving environmental problems and economic benefits from raw material loss reduction compared to the existing thermal reshaping method. Polymers and additives which are disadvantages caused by the molding method There is no limitation of the present invention relates to a method for manufacturing shoe soles and integral soles capable of high physical properties.

 In the case of the thermal reshaping method, the pre-fabrication method is first manufactured in the form of an approximate window shape through cutting and grinding, and then put into a mold and then heated and cooled. The shoe midsole or outsole was manufactured by reshaping by. When using this method, the cutting and grinding process is required, which leads to a complicated work process, a large amount of raw material loss, and the manufacture of the window through compression molding, resulting in a difference in specific gravity depending on the thickness of the window. There is a problem that appears differently in each part.

In order to solve this problem, a new thermal reshaping method was developed. Unlike the existing thermal reshaping method, the first preform is manufactured in the form of a window directly, and the second heating and cooling process is performed again without the cutting and grinding process. Molding produced shoe midsoles or outsoles. When using the new thermal reforming method as described above, the efficiency of the raw material loss and the improvement of the work process, which are a problem in the existing thermal reforming method, is quite efficient, but there is still a problem that the physical properties of each part of the window appear different according to the reforming process. . In addition, since the first preform is used as the second compression molding, the thickness of the skin layer is increased in the case of the midsole and the outsole thus produced, which causes problems in adhesiveness and surface glossiness.

The injection molding method was introduced to solve the problems in the thermal re-molding method, but the injection molding has a large initial investment cost and the flowability of the kneaded material is a big problem, resulting in the limitation of the use range of the polymer and the additive used.

Accordingly, the present inventors have made research efforts to solve the above problems, and as a result, specifically configure the base component, select and use the crosslinking agent to express the optimal crosslinking according to the selection of the base component, and the crosslinking rate regulator is an essential component The foamed kneaded material exhibiting various characteristics such as improved wear resistance and traction performance can be prepared in sheet form or pellet form, and then introduced into a mold for press at room temperature or preheated to be used at 150 to 170 ° C. and 100 to 150 kg / cm 2 pressure. The present invention was completed by knowing that the foam was completed by press molding for 10 minutes to directly manufacture a shoe midsole or an integral window.

Therefore, since the present invention manufactures the shoe midsole or integral window without undergoing the thermal reshaping process, compared to the conventional thermal reshaping method, the process is shortened and the waste material is reduced. It is an object of the present invention to provide a method for manufacturing shoe soles and integrally shaped soles that can be made of high value since there is no limitation of polymers and additives, which can create added value and are disadvantages caused by injection molding.

The present invention comprises 100 parts by weight of an essential component of 1,2-polybutadiene and one or more selected from ethylene-vinylacetate copolymer (EVA), ethylene / α-olefin copolymer and rubber; 1 to 6 parts by weight of blowing agent; 0.02 to 1.5 parts by weight of the organic peroxide crosslinking agent; 0.15 to 0.25 parts by weight of sulfur as a crosslinking rate controlling agent; And a method for manufacturing a shoe midsole or an integrated window obtained by pressing a mixture of foams containing 4 to 15 parts by weight of conventional additives into a mold and pressing for 5 to 10 minutes at a pressure of 150 to 170 ° C. and 100 to 150 kg / cm ^2. It is characterized by.

Referring to the present invention in more detail as follows.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing a foam which simultaneously exhibits the advantages of the injection molding method and the two-step thermal reshaping method, which are generally methods for manufacturing shoe windows in the manufacture of shoe soles or integral windows.

Hereinafter, the present invention will be described in detail.

First, the kneaded material for foam used to manufacture a shoe sole or integral window according to the present invention will be described below.

The kneaded product for the foam contains 1,2-polybutadiene as an essential component, and as ethylene-vinylacetate copolymer (EVA), ethylene / α-olefin copolymer or rubber (isoprene rubber, butadiene rubber, natural rubber, etc.) A foaming agent, a crosslinking agent, and an additive are blended with the polymer substrate thus formed, and the kneaded product is prepared in a sheet form or pellet form and put into a mold at room temperature or in a preheated state at 40 to 100 ° C. Except 1,2-polybutadiene and rubber in the polymer substrate, it is generally used in shoe midsoles or integral windows, and the present invention mainly uses butadiene structure by using 1,2-polybutadiene in a large amount as a main component of the substrate. Although it has made it possible to use a large amount of rubber | gum, as a base material, the said polymer can be used individually or in mixture.

The blowing agent is added to produce a foam, and an azo compound having a decomposition temperature of 150 to 210 ° C. is used, and it is preferable to use 1 to 6 parts by weight based on 100 parts by weight of the polymer substrate. If the amount is less than 1 part by weight, a foam having a specific gravity of 0.7 or more and a hardness of 70 (type C) or more is produced and has a problem in weight reduction. If the amount is more than 6 parts by weight, the specific gravity falls to 0.15 or less, which shows an excellent effect on weight reduction. However, there is a problem of poor mechanical properties and dimensional stability. In addition, if the decomposition temperature is less than 150 ℃ premature foaming occurs during the compound production, if it exceeds 210 ℃, the molding time of the foam takes 15 minutes or more, there is a problem that productivity is lowered. As the azo compound used as the blowing agent, azodicarbonamide can be mainly used, and various products controlled by the decomposition temperature mentioned above can be used.

The crosslinking agent is an organic peroxide crosslinking agent capable of sufficiently trapping the decomposition gas generated from the blowing agent and imparting high temperature viscoelasticity to the resin, using 0.02 to 1.5 parts by weight, and more preferably 0.05 to 1.0 part by weight. It is preferable that these are those whose 1 minute half life temperature is 130-180 degreeC. Its amount was less than 0.02 parts by weight and the lack of crosslinking prevented the high temperature viscoelasticity of the resin from decomposing the foam. When the content exceeded 1.5 parts by weight, the hardness was rapidly increased due to overcrosslinking and the foam bursted. Examples of such crosslinking agents include t-butylperoxyisopropyl carbonate, t-butylperoxy urinate, and t-butylperoxy as organic peroxide crosslinking agents as well as sulfur and insoluble sulfur which are widely used in rubber compounding. Acetate, di-t-butylperoxyphthalate, t-dibutylpooxymaleic acid, cyclohexanone peroxide, t-butyl cumyl peroxide, t-butylhydroperoxide, t-butylperoxybenzoate, dicumyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, methylethylketone peroxide, 2,5-dimethyl-2,5-di (benzoyloxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy (hexane, di-t-butylperoxide, 2,5-dimethyl-2,5- (t-butylperoxy) -3-hexane, n-butyl-4,4-bis (t) -Butyl peroxy) valerate, α, α'-bis (t-butylperoxy) diisopropylbenzene, etc. On the other hand, the present invention provides sulfur with the organic peroxide crosslinking agent. Insoluble sulfur is used as an essential component, etc. The sulfur was generally used in rubber compounding, but in the present invention, 1,2-polybutadiene, which is used as an essential component of the base material, uses an existing foam. When used, it is applied as a crosslinking rate adjusting agent which plays a role of solving the problem that the crosslinking rate is generally higher than the components commonly used, and it is necessarily used even when rubber is not used as a component of the substrate. By using sulfur as the crosslinking rate regulator with the organic peroxide crosslinking agent, it is possible to use a large amount of 1,2-polybutadiene in the present invention, unlike the conventional case, and the 1,2-polybutadiene is a rubber (butadiene structure ) Has a similar structure and excellent compatibility with rubber. Effect of the rubber can be applied can also be obtained.

The additive is commonly used in the manufacture of foams, such as metal oxides, stearic acid, antioxidants, zinc stearate, titanium dioxide, crosslinking aids, etc., which are generally used in manufacturing shoe midsoles or integral windows in order to improve processing properties and improve foam properties. It is also possible to use a variety of pigments in consideration of the additive of the color. The additive may be added 4 to 15 parts by weight based on 100 parts by weight of the substrate. As the metal oxide, zinc oxide, titanium oxide, cadmium oxide, magnesium oxide, mercury oxide, tin oxide, lead oxide, calcium oxide, etc. may be used to improve the physical properties of the foam, and may be used in an amount of 1 to 4 parts by weight based on 100 parts by weight of the substrate. Can be. In addition, in the present invention, it is preferable to use 0.05 to 0.5 parts by weight of triaryl cyanurate (TAC), which is a crosslinking aid, based on 100 parts by weight of the base material in order to adjust the molding time to 5 to 10 minutes when the press is 150 to 170 ° C. If the amount of the crosslinking aid is less than 0.05 parts by weight, the crosslinking aid has little effect. If the amount of the crosslinking aid exceeds 0.5 parts by weight, the foam bursts due to the crosslinking, similar to when the amount of the crosslinking agent exceeds 1.5 parts by weight.

      Stearic acid and zinc stearate form a foam cell finely and uniformly, facilitate demolding during foam molding, and generally 1 to 4 parts by weight based on 100 parts by weight of the substrate. The antioxidants include sonnoc, butylated hydroxy toluene (BHT) and songnox 1076 (songnox 1076, octadecyl 3,5-di-tert-butyl-r-hydroxy hydrocinnamate). When polybutadiene and rubber are used as a base material, it may be used to suppress yellowing and may be used in an amount of 0.25 to 2 parts by weight based on 100 parts by weight of the base material. Titanium dioxide is used as a pigment for white and functions the same as the metal oxide mentioned above, and may be used in an amount of 2 to 5 parts by weight.

The above components are sufficiently kneaded using a ban-bury mixer, open roll mill or kneader at a temperature range above the melting point of the substrate and below the decomposition point of the crosslinking agent and the blowing agent. After the kneaded product is made, it is prepared into a sheet or pellet to be suitable for press molding, and then put into a closed mold.

Next, in the step of press molding, press-molding by cross-linking and foaming by press molding at 150 to 170 ° C. and 100 to 150 kg / cm ^{2 for} 5 to 10 minutes, the foam is completed to directly manufacture a shoe midsole or an integral window. The press molding machine generally used in press molding can be used, and press molding is carried out by the compression molding method or the transfer molding method. In the press molding, if the mold temperature is less than 150 ℃ or the molding time is less than 5 minutes, sufficient decomposition of the crosslinking agent and the foaming agent cannot occur, and if the mold temperature exceeds 170 ℃ or the molding time exceeds 10 minutes, a part of the foam Discolored or unstable foams may be obtained, resulting in higher costs and higher productivity and overall costs. And, when the molding pressure is less than 100 kg / cm ² Molding time it takes more than 12 minutes, and the foam cells is increased and a problem that the physical properties are degraded, the effect of the pressure increase, as well as lead to the mold deformation when it is more than 150 kg / cm ² There is no.

In particular, the conventional press molding method manufactures a semi-finished product by using a press in one step, and then manufactures the product by thermal reforming using a press in two steps, whereas in the present invention, without the manufacturing process of the semi-finished product, that is, heat Direct shoe midsoles or integral windows are made without reshaping. In addition, compared to the conventional injection molding method, the existing equipment can be used first, thus reducing the cost of equipment investment, and since the injection process is unnecessary, the polymer having a melt index of 1 or less that impedes the flow of the compound and rubber that is difficult to use in injection It can be used without limitation to maintain the high physical properties of the foam.

As such, the present invention can take advantage of the existing thermal re-molding method and injection molding to shorten the manufacturing process compared to the thermal re-forming method, and the equipment investment cost is cheaper than the injection molding, and the flowability of the kneaded material is not limited, the thickness of the skin layer Invented a molding method in which problems such as adhesion and gloss caused by the increase can be improved. Furthermore, the sole according to the present invention has improved traction characteristics and surface gloss compared with conventional injection molding methods.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by Examples.

Example 1

Next, the surface temperature is 80-90 after mixing for about 10 minutes using a substrate and zinc oxide, stearic acid, zinc stearate, antioxidant, titanium dioxide, and sebum at 80-100 ° C. in the content shown in Table 1 below. Compounds were prepared using a crosslinking agent and a blowing agent in a roll mill at 0 ° C., and then a kneaded product for foam was prepared in a sheet shape having a thickness of about 3 mm.

The sheet-like kneaded product prepared as described above is introduced into the press mold by an amount of about 107% based on the capacity of the press mold, pressurized and heated at 170 ° C. and 150 kg / cm ² for 8 minutes, and then the mold is opened and depressurized. At the same time it was inflated to prepare a shoe midsole. Table 2 shows the results of measuring physical properties of the manufactured shoe midsole.

Since the shoe midsole directly molded by the primary compression molding uses a conventional press compared to the injection molding, it is possible to manufacture a shoe midsole having a low gloss, which is cheaper in equipment investment and has a high added value compared to the thermal reforming method. matter Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 materials Ethylene Vinyl Acetate Copolymer ¹ 50 50 - 100 100 1,2-polybutadiene ² 30 50 50 - - Butadiene rubber ³ 20 - 50 - - additive ZnO ⁴ 3 3 3 3 3 St / A ⁵ One One One One One Zn / St ⁶ One One One One One TiO ₂ ⁷ 5 5 5 5 5 Antioxidants ⁸ 0.3 0.5 0.75 - - PEG ⁹ 0.5 0.5 0.5 - - TAC ¹⁰ - - - - Crosslinking agent Sulfur ¹¹ 0.15 0.25 0.25 - - DCP ¹² 0.6 0.6 0.6 0.8 0.6 blowing agent Denatured ADCA ¹³ 1.4 1.4 1.4 4.0 1.4 ADCA ¹⁴ 1.4 1.4 1.4 - 1.4 1. DuPont EVA 360 2. RB820 of JSR, Japan 3. KBR01 of Kumho Petrochemical 4. No. 1 for rubber of Gilcheon Chemical 5. Stearic acid of LG Chemical 6. Jinx stearate of Songwon Industry Zinc stearate 7. Dupont R-902 8. Songwon Industrial Songnox1076 9. Polyethylene glycol of Korean polyol, molecular weight 4000 10. Triallyl cyanurate of Akzo 11. Miwon of Sulfur 12. Japanese NOF Dicumyl peroxide 13. Geumyang JTR (modified azodicarbonamide) 14. Geumyang AC 3000

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Example 2

In the content shown in Table 1 above, using a substrate, zinc oxide, stearic acid, zinc stearate, antioxidants, titanium dioxide, and sebum for about 10 minutes in a kneader at 100 to 110 ℃ surface temperature is 90 ~ Compounds were prepared using a crosslinking agent and a blowing agent in a roll mill at 100 ° C, and then a kneaded product for foaming was prepared in pellet form using an extruder at 90 to 100 ° C.

The pellet-like kneaded material prepared as described above is heated in a mold at a temperature of 165 ° C. and 150 kg / cm ² for 8 minutes by injecting 104% of the amount of the press-shaped pellet into the mold. Prepared. Table 2 shows the results of measuring physical properties of the manufactured integral shoe window.

Integral foam window for shoes that is directly molded by such compression molding uses existing presses and press molds compared to injection molding, so it is inexpensive to invest in equipment, and there is almost no difference in physical properties for each part and excellent traction characteristics compared to thermal reforming method. It was possible to manufacture an integral window for shoes.

Example 3

In the content shown in Table 1 above, using a substrate, zinc oxide, stearic acid, zinc stearate, antioxidants, titanium dioxide, and sebum for about 10 minutes in a kneader at 100 to 110 ℃ surface temperature is 90 ~ Compounds were prepared using a crosslinking agent and a blowing agent in a roll mill at 100 ° C., and then a kneaded product for foaming was prepared in a sheet shape having a thickness of about 3 mm.

After preheating the prepared sheet-like kneaded material at 50 ° C. to about 60 ° C., the mold is placed in a transfer mold with an amount of about 105% based on the capacity of the press die, and then molded for 8 minutes at 170 ° C. and 150 kg / cm ² . To produce a shoe-integrated window. Table 2 shows the results of measuring physical properties of the manufactured shoe sole.

Since the integrated foam window by transfer molding is not related to the flowability of polymers compared to injection molding, there is no restriction on the polymers and additives used, so it has excellent mechanical properties and high added value compared to the thermal reforming method. It was possible to produce an integral foam window for shoes with less gloss.

Comparative Example 1 (Thermal Reforming Method)

After mixing for about 10 minutes using a substrate and zinc oxide, stearic acid, zinc stearate, titanium dioxide in the content shown in Table 1 in a kneader at 80 ~ 100 ℃ and the crosslinking agent in a roll mill with a surface temperature of 80 ~ 90 ℃ After the compound was prepared using the blowing agent, a kneaded product for the foam was prepared in the form of a sheet having a thickness of about 3 mm. The kneaded material was manufactured in the sheet form about 3 mm thick.

The sheet-like kneaded material thus prepared was pressurized and heated for 40 minutes under conditions of 150 ° C. and 150 kg / cm ² , and then expanded at the same time with depressurization to prepare a primary sponge for shoe soles. The prepared primary sponge was manufactured in the shoe midsole according to the currently used pylon process. Table 2 shows the results of measuring physical properties of the manufactured shoe soles.

This process (thermal reshaping) causes an environmental problem caused by the generation of about 50 to 60% of waste materials and a cost increase due to the loss of raw materials, and there are technical problems in which physical properties vary depending on the part of the window.

Comparative Example 2 (Injection Molding Method)

The cross-linking agent in a roll mill having a surface temperature of 90 to 100 ° C. after about 10 minutes of mixing with a substrate and zinc oxide, stearic acid, zinc stearate, and titanium dioxide using a content shown in Table 1 in a kneader at 100 to 110 ° C. The compound was prepared using triallyl cyanurate (TAC), a crosslinking aid, and a blowing agent, and then pelletized using an extruder at 90 to 100 ° C.

Compound prepared as described above is injected into the screw of 90 ~ 110 ℃ through the hopper of the injection molding machine and injected into the mold having a temperature of 170 ℃ and mold pressure of 80 ~ 100 kg / cm ² and then molded for 420 seconds Opening and demoulding at the same time to manufacture a one-piece shoe. Table 2 shows the results of measuring physical properties of the manufactured soles.

The injection molding method has a limitation in the range of use of polymers (high MI, low molecular weight) due to the problem of flowability, which makes it difficult to achieve high physical properties of the foam window. It cannot be improved.

Test Example

The characteristics of the soles prepared according to Examples 1 to 3 and Comparative Examples 1 and 2 were tested in the following manner.

1. Specific gravity (density)

After removing the surface, the specific gravity of the foam was measured five times using an automatic specific gravity measurement device and the average value was taken.

2. Hardness

Hardness was measured according to ASTM D-2240 by cutting the middle portion of the foam and using an Asker C type hardness meter.

3. Tensile Strength and Elongation

The surface layer of the foam was removed, and the thickness was 3 mm. A test piece was made with a No. 2 mold knife, and tensile strength and elongation were measured according to ASTM D-142. At this time, five test pieces were used for the same test, and the tensile speed was 500 mm / min.

4. Tear strength

The tear test was measured according to ASTM D-3574 and ASTM D-634, respectively, and the measurement speed was measured five times at 100 mm / min and the average value was taken.

5. Burst tear strength

Three specimens were used in the same test to measure the tear tear characteristics of the sponge, and the measurement was further performed except for deviation of 20% or more from the median value at the time of measurement. The specimen type and dimensions used are shown below.

6. Permanent compression rate

The test piece prepared in the form of a cylinder having a diameter of 30 ± 0.05 mm by increasing the foam to 10 mm in thickness was measured according to ASTM D-3574. Place the specimen between two parallel metal plates, insert a spacer equal to 50% of the thickness of the specimen, compress it, and remove the specimen from the water compression apparatus after heat treatment for 6 hours in an air-circulating oven maintained at 50 ± 0.1 ° C. After cooling for 30 minutes at room temperature the thickness was measured. Three specimens were used in the same test, and the compression set was calculated by the following equation.

Where Cs is the permanent compressive shrinkage, t ₀ is the initial thickness of the specimen, t _f is the thickness of the specimen when cooled after heat treatment, and t _s is the thickness of the spacer.

7. Gloss Evaluation

In order to measure the light of the effervescent shoe sole, the light is reflected by reflecting the light at 60 ° (θ) using Garder's micro-Tri-gloss (made in Germany). It was.

8. Traction Evaluation

The static friction coefficient was measured using a friction tester (slip tester) to measure the starting angle (θ) of the slip and then obtained tanθ as the friction coefficient.

9. Wear resistance evaluation

Abrasion resistance was measured using an NBS abrasion tester and was calculated by the following equation.

characteristic unit Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Hardness C type 52 59 62 57 65 density g / cc 0.22 0.18 0.5 0.23 0.19 The tensile strength kg / cm ² 27 35 45 23 22 Elongation % 350 330 370 340 300 Tear strength kg / cm 12 11 19 11 9.5 Bursting tear strength kg / cm 3.0 3.2 4.0 3.1 2.5 Permanent compression % 40 50 20 58 60 ore 8 9 8 7 17 Traction μ 1.2 1.2 1.5 0.85 0.7 Wear resistance % 240 150 360 43 37

As shown in Table 2, the shoe sole of the embodiment according to the present invention has improved traction characteristics compared to the comparative example and it is possible to lower the hardness while having a high density (specific gravity) using rubber that is not suitable as an injection material. Also excellent was confirmed. In addition, the wear resistance was very good compared to the existing comparative example for the shoe was confirmed that it is suitable for the one-piece window.

As described above, the shoe window according to the present invention can be directly molded by primary compression molding or transfer molding, and the equipment investment is low because it uses presses and press molds compared to thermal remolding or injection molding. Since there is no restriction on the flowability of polymers and additives, it has excellent mechanical properties, almost no difference in physical properties for each part, and excellent traction characteristics and high added value. Is possible.

Claims (4)

100 parts by weight of a base material comprising an essential component of 1,2-polybutadiene and at least one selected from ethylene-vinylacetate copolymer (EVA), ethylene / α-olefin copolymer and rubber; 1 to 6 parts by weight of the blowing agent; 0.02-1.5 parts by weight of organic peroxide crosslinking agent; 0.15 to 0.25 parts by weight of sulfur as a crosslinking rate controlling agent; And a midsole for shoes, characterized in that obtained by kneading the mixture for foams mixed with conventional additives 4 to 15 parts by weight in a mold for 5 to 10 minutes at a pressure of 150 ~ 170 ℃, 100 ~ 150 kg / cm ² Method of manufacturing an integrated window. The method of claim 1, wherein the kneaded material for the foam is in the form of a sheet or pellets. The method according to claim 1, wherein the foamed kneaded product is introduced into a mold by preheating to room temperature or 40 to 100 ° C. The method of claim 1, wherein the press molding is a compression molding method or a transfer molding method.