KR20070022419A - Ethylene vinyl Acetate CopolymerEVA compounds for a footwear sole, Method for producing a sponge by using thereof and a sponge - Google Patents

Abstract

The present invention relates to an ethylene vinyl acetate copolymer composition for footwear, and more specifically, by applying the expansion coefficient of the cork itself and the expansion ratio of the ethylene vinyl acetate copolymer composition (hereinafter referred to as EVA) by adding the cork powder at the same time with the compounding Provided are an ethylene vinyl acetate copolymer composition for producing a foam for a shoe sole (insole, midsole and sole) and a method for producing a sponge using the same.

Cork, sponge, EVA, crosslinking agent, softener, foaming agent, sole

Description

Ethylene vinyl Acetate Copolymer (EVA) compounds for a footwear sole, Method for producing a sponge by using approximately and a sponge}

1 is a process chart showing a method of manufacturing a shoe sole manufacturing sponge of the present invention.

The present invention relates to an ethylene vinyl acetate copolymer composition for footwear, and more specifically, by applying the expansion coefficient of the cork itself and the expansion ratio of the ethylene vinyl acetate copolymer composition (hereinafter referred to as EVA) by adding the cork powder at the same time with the compounding The present invention relates to an ethylene vinyl acetate copolymer composition for producing a foam for a shoe sole (insole, midsole and sole) and a method for producing a sponge using the same.

Typically, the window of the shoe is very important physical properties required according to the characteristics of each part, such as constant hardness, tensile force, elongation, attractive force, restoring force, shock absorption, wear, non-slip, moldability.

Conventional shoe sole sponges are mostly made using a thermoplastic synthetic resin sponge. Since most synthetic resin sponges have excellent moldability due to the thermoplastic properties of the resin and workability is very easy, most synthetic resin sponges are used.

On the other hand, because the heat resistance is very weak and the compression deformation is bad, the synthetic resin sponge used in the insole becomes thinner about a week after wearing sneakers, because the synthetic resin sponge is weak in heat and the compression deformation is bad.

Midsoles of shoes are the same.

Such weak heat resistance and compressive deformation are the biggest disadvantages of the synthetic resin sponge, although there are differences depending on the hardness of the parts.

Conventional methods of manufacturing synthetic resin sponges are widely known, but briefly summarized, after mixing the EVA resin with a blowing agent, a crosslinking agent, a preparation agent, etc., first mixing in a mixer, and then performing a second mixing operation in a rougegi sheet, and then sheeting about 2 to 4 mm thick in a calendar. After cooling, it is manufactured by compression heating in a heat press after cooling. At this time, the specification of the flat sheet is different depending on the mold size and the expansion ratio.

On the other hand, natural cork, which has many important physical properties such as high heat resistance, lightness, moisture control, shock absorption, and resilience, is powdered and manufactured by mixing with synthetic resin or by applying adhesive treatment to cork powder and compressing the sheet. It is also used to make a shoe sole, but when manufactured using the cork powder is very expensive and has a disadvantage of poor workability has been limited to some special cases are used.

In addition, in order to take advantage of the thermoplastic synthetic resin sponge and natural cork, the sheet manufactured using the synthetic resin sponge and the cork powder is made to a certain standard, and then subjected to adhesive processing, and then put into a molding mold and compressed to manufacture a shoe sole using a thermal cooling method. . However, this method is difficult to mold the shape of high cost and difficulty due to the increase of the work process (gluing, cutting, etc.).

Accordingly, the present invention is to solve the conventional problems as described above, ethylene vinyl acetate copolymer composition suitable for the characteristics of the sole by mixing a large amount of cork by adjusting the physical properties of the natural cork excellent physical properties and synthetic resin sponge well It is a technical problem to provide a method for manufacturing a shoe sole manufacturing sponge using the same and a shoe sole manufacturing sponge.

The present invention that solved the above technical problem is composed of 100 parts by weight of ethylene vinyl acetate copolymer, 5 to 50 parts by weight of cork fine powder, 0.5 to 2.5 parts by weight of softener, 0.5 to 1.5 parts by weight of crosslinking agent and 2.0 to 8.0 parts by weight of blowing agent. An ethylene vinyl acetate copolymer composition for footwear is provided.

In the present invention, 100 parts by weight of ethylene vinyl acetate copolymer, 5 to 50 parts by weight of cork fine powder, 0.5 to 2.5 parts by weight of a softener, and 0.5 to 1.5 parts by weight of a crosslinking agent were put into a mixer, and mixed at a temperature of 80 to 90 ° C. for 12 to 14 minutes. After the first mixing step of mixing for 1 to 3 minutes by adding 2.0 to 8.0 parts by weight of the blowing agent, the second mixing the primary blended mixture for 13 to 17 minutes at a surface temperature 70 ~ 80 ℃ in a mixing roll which is a secondary mixer Mixing step, the step of cooling and aging the second blended blend at room temperature for 2 hours or more, the third blending step of remixing the blend in a mixing roll for 13-17 minutes at a surface temperature of 70 ~ 80 ℃, the mixed The compound is cut in three calenders to have a width of 500 m / m and a length of 1000 m / m and a thickness of 2 to 3 m / m, followed by cooling and aging at room temperature for at least 2 hours. The cooled compound is weighed according to mold specifications and then put into a mold. 152 ~ 158 ℃ temperature, 160kgf / ㎠ pressure In the press foaming step of vulcanizing and foaming for 42 minutes and provides a sponge manufacturing method for a shoe sole, characterized in that consisting of a step of cooling the sponge produced in the press foaming step.

The present invention also provides a shoe sole manufacturing sponge manufactured by the method described above.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Accompanying drawings Figure 1 is a process diagram showing the manufacturing process of the shoe sole manufacturing sponge of the present invention.

It is to be proposed in the present invention to propose a shoe sole manufacturing sponge and an ethylene vinyl acetate copolymer composition for preparing the sponge that can simultaneously have the excellent workability and advantages of the thermoplastic sponge while maximizing the advantages of natural cork. .

That is, the ethylene vinyl acetate copolymer (hereinafter referred to as EVA), the crosslinking agent, the softener, the foaming agent, and the cork powder are first mixed in a mixer, then remixed in a secondary mixer mixing roll, cooled, compressed into a hot press, and foamed. Let's do it. At this time, when the cork particles are connected, it becomes an open cell, which requires a lot of attention. The sponge thus prepared contains EVA and cork at the same time, thereby simultaneously possessing physical properties of the synthetic resin sponge and cork.

Detailed composition ratio and manufacturing method thereof will be described with reference to FIG. 1.

The ethylene vinyl acetate copolymer composition according to the present invention consists of ethylene vinyl acetate copolymer, cork fine powder, softener, crosslinking agent and blowing agent.

Here, the ethylene vinyl acetate copolymer is used in the conventional one, and the fine cork powder is used to powder to an average particle diameter of 0.1 ~ 3.0㎜ using a normal natural cork, to 100 parts by weight of ethylene vinyl acetate copolymer It is preferable to add 5-50 weight part with respect to. If the added amount is less than 5 parts by weight, there is a problem that the physical properties of the cork can not be expected, if it exceeds 50 parts by weight, there is a problem that the rise in manufacturing cost, the foamability and the workability is significantly reduced. In addition, when the average particle diameter of the cork powder to be used is less than 0.1 mm, the cork particles are fine and the cork shape does not appear well. there is a problem.

Stearic acid is used as the softener used in the present invention, and the amount thereof is preferably 0.5 to 2.5. If the added amount is less than 0.5 parts by weight, there is a problem of reduced flexibility and poor mixing operation, and if it exceeds 2.5 parts by weight, the problem of leaching on the surface or deteriorated physical properties. In addition to the stearic acid described above, other emollients commonly used within the scope of not inhibiting the present invention can be used.

The crosslinking agent used in the present invention uses DCP (Dicumyl Peroxide), and the amount thereof is preferably 0.5 to 1.5. If the added amount is less than 0.5 parts by weight, there is a problem of uncured phenomena or a long vulcanization time, resulting in a decrease in productivity. When it is more than 1.5 parts by weight, excess vulcanization occurs, resulting in a decrease in foaming rate and poor foaming. This deterioration problem occurs. In addition to the above DCP, other crosslinking agents usually used in a range that does not inhibit the present invention can be used.

The blowing agent used in the present invention uses azodicarbonamide (AD, Azodicarbonamide), the amount is preferably 2.0 ~ 8.0. If the amount is less than 2.0 parts by weight, there is a problem in that the function of the sponge is lost due to high hardness and high specific gravity due to low foaming. If it exceeds 8.0 parts by weight, the sponge may be defective due to excessive foam gas. there is a problem. In addition to the azodicarbonamide, a blowing agent usually used in a range that does not inhibit the present invention can be used.

In the present invention, various blending resins, rubbers or other fillers may be further added to control the physical properties according to the use of the sole (insole, midsole, and sole) in the range that does not inhibit the present invention in addition to the above-described composition. have.

Referring to the process for producing a sponge used to manufacture a shoe sole using the ethylene vinyl acetate copolymer composition of the present invention configured as described above are as follows.

First, 100 parts by weight of ethylene vinyl acetate copolymer, 5 to 50 parts by weight of cork fine powder, 0.5 to 2.5 parts by weight of softener, and 0.5 to 1.5 parts by weight of crosslinking agent are added to a mixer, and mixed at a temperature of 80 to 90 ° C. for 12 to 14 minutes, followed by foaming agent 2.0 to 8.0 parts by weight was added and mixed in the primary mixer for 1 to 3 minutes (S100, S110), and the mixture was mixed firstly in a mixing roll which is a secondary mixer at a surface temperature of 70 to 80 ℃ for 13 to 17 minutes at room temperature After cooling and ripening for at least 2 hours at (S120, S130), the aged compound was remixed for 13 to 17 minutes at a surface temperature of 70 to 80 ℃ in a mixing roll, and then 500 m / m length and 1000 m / m thickness in three calenders. Cut to 2 ~ 3m / m and cooled and aged at room temperature for 2 hours or more (S140, S150, S160), and the basis weight according to the mold specification (Balance weight: 620 × 1140 × 19m / m Weight is 11,500g), and then put into mold, and then the temperature is 152 ~ 158 ℃, 16 After pressing foaming and foaming for 42 minutes at a pressure of 0 kgf / cm 2, the sponge is naturally cooled at room temperature to prepare a sponge (S170, S180, S190, and S200).

The input weight of the compound is basis weight differently according to the mold specification and the input weight calculation method is as shown in Equation 1 below.

Equation  One

Input weight = (width × length × height of mold) / specific gravity of compression compound

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. However, the present invention is not limited by the following examples.

Example 1

100 parts by weight of EVA copolymer, 40 parts by weight of fine cork powder, 1.3 parts by weight of stearic acid as a softener, 0.9 parts by weight of DCP as a crosslinking agent and 6.1 parts by weight of AD as a blowing agent were mixed first in a 75 liter capacity Lida group, and the primary mixture was mixed. Secondary mixing in the mixing roll, and then cooled and aged at room temperature, the third mixture is mixed again in the mixing roll. The third mixture is prepared in three calenders, and the sheet is 500 × 1000 × 2m / m in size. Naturally cooled, 11,500 g of the weight is added to a mold of 620 × 1140 × 19m / m and foamed in a hot press. After the preparation, specimens were prepared in a size of 150 m / m horizontal 200 m / m thickness 10 m / m and tested for various physical properties. The results are shown in Table 1.

Comparative Example 1

1.3 parts by weight of stearic acid as a softener, 0.9 parts by weight of DCP as a crosslinking agent and 6.1 parts by weight of AD as a blowing agent were mixed with 100 parts by weight of the EVA co-condensate to prepare a sponge in the same manner as in Example 1, and then specimens were prepared and tested for various physical properties. The results are shown in Table 1.

<Table 1>

 Property item  Reference value  Example  Comparative example  Seal  10.0 or more  14kg / ㎠  15kg / ㎠  Fragment  6.0 and above  8kg / cm  9 kg / cm  Elongation  80 or more  110%  180%  Shrink  1.0 or less  0.3%  0.8%  Hardness  C TYPE  48 °  40 °  importance  0.26 or less  0.23  0.19  Axial strain  65% or less  55%  65%

As shown in the results, it can be seen that the physical properties of the compressive strain and the shrinkage hardness are significantly increased compared to the synthetic resin sponge by the cork particles.

When manufacturing various shoe soles using the sponges prepared as described above, the synthetic resins and cork have the same properties as those of synthetic resins or cork-only sponges. Complementary effect makes it possible to manufacture a shoe sole excellent in various physical properties, it is excellent in hardness, permanent compression strain compared to a shoe sole made of conventional synthetic resin.

As described above, the sole composition according to the present invention is mixed with various blends by adding natural cork powder to ethylene vinyl acetate copolymer, and then, when manufacturing the sole sponge using the mixture, physical properties of the synthetic resin and cork This complementary action has the effect of improving the various physical properties required for the production of the shoe sole, such as compression deformation, heat resistance.

In addition, the problem of work processability and cost increase, which is a problem when manufactured only with cork, is also improved by mixing composition with synthetic resin.

Claims (8)

100 parts by weight of ethylene vinyl acetate copolymer, 5 to 50 parts by weight of cork fine powder, 0.5 to 2.5 parts by weight of softener, 0.5 to 1.5 parts by weight of crosslinking agent and 2.0 to 8.0 parts by weight of foaming agent. Coalescing composition. The sole ethylene vinyl acetate copolymer composition according to claim 1, wherein the cork fine powder has an average particle diameter of 0.1 to 3.0 mm. The sole ethylene vinyl acetate copolymer composition according to claim 1, wherein the softener is stearic acid. The sole ethylene vinyl acetate copolymer composition according to claim 1, wherein the crosslinking agent is DCP. The method of claim 1 wherein the blowing agent is ethylene vinyl acetate copolymer composition, characterized in that the azodicarbonamide. 100 parts by weight of ethylene vinyl acetate copolymer, 5 to 50 parts by weight of cork fine powder, 0.5 to 2.5 parts by weight of softener, 0.5 to 1.5 parts by weight of crosslinking agent, were mixed in a mixer at a temperature of 80 to 90 ° C. for 12 to 14 minutes, and then foaming agent 2.0 to 8.0. First mixing process by mixing 1 to 3 minutes by weight, A secondary mixing step of mixing the first blended blend for 13 to 17 minutes at a surface temperature of 70 ~ 80 ℃ in a mixing roll which is a secondary mixer, Cooling and aging the secondary mixed formulation at room temperature for at least 2 hours, Tertiary mixing process of re-mixing the compound for 13 to 17 minutes at a surface temperature of 70 ~ 80 ℃ in a mixing roll, The mixed compound is cut in three calenders to have a thickness of 500mm length 1000mm thickness 2-3mm, cooling and aging at room temperature for 2 hours or more, Press cooled step of weighing the cooled compound according to the mold specification and then injecting into the mold for vulcanization and foaming for 42 minutes at a temperature of 152 ~ 158 ℃, 160kgf / ㎠ and Method for producing a shoe sole sponge, characterized in that consisting of a step of cooling the sponge produced in the press foaming process. The method of claim 6, wherein the average particle diameter of the fine cork powder is 0.1 ~ 3.0mm. A sponge for a shoe sole, which is produced by the method of claim 6.

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