KR100357907B1 - Composite of sponge foam for outsole - Google Patents

Abstract

The present invention relates to a foam composition for shoe outsole, and more particularly to a foam composition for shoe outsole, comprising a rubber component selected from isoprene rubber and butadiene rubber and 1,2-polybutadiene and ethylene / α-olefin copolymer It is based on a blend of resin components, and contains a common crosslinking agent, a foaming agent and an additive for rubber, presses, crosslinks and foams, and has a broader hardness range and lower specific gravity than conventional commercialized resin or rubber foams. The present invention relates to a foam composition for shoe outsole, which is not only excellent in wear resistance and elasticity but also light in weight and excellent in dimensional stability.

Description

Foam composition for shoe outsole {Composite of sponge foam for outsole}

The present invention relates to a foam composition for shoe outsole, and more particularly to a foam composition for shoe outsole, comprising a rubber component selected from isoprene rubber and butadiene rubber and 1,2-polybutadiene and ethylene / α-olefin copolymer It is based on a blend of resin components, and contains a common crosslinking agent, a foaming agent and an additive for rubber, presses, crosslinks and foams, and has a broader hardness range and lower specific gravity than conventional commercialized resin or rubber foams. The present invention relates to a foam composition for shoe outsole, which is not only excellent in wear resistance and elasticity but also light in weight and excellent in dimensional stability.

Currently used shoe outsole material can be classified into non-foamed and foamed according to the form. Up to now, the non-foam body that uses most kinds of rubber as a shoe outsole has been the dominant type, but as the demand for lightweight shoes increases, the demand for foam for shoe outsoles is increasing rapidly. Such foams include ethylene vinyl acetate copolymer, 1,2-polybutadiene, ethylene / α-olefin copolymer, natural rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR) and chlorosulfonated polyethylene (CSM) Is used as a base material or blended thereof, and a foam which contains a conventional additive and a blowing agent and is produced by a press or an injection method is widely used as a shoe outsole.

Rubber-based foam is not only excellent slip resistance and excellent elasticity, but also very suitable as a low-hard shoe outsole, but has a problem of inferior dimensional stability due to high heat shrinkage. The thermal contraction of such rubber foams can be solved by leaving it in an oven for about 20 hours or more at 70 ° C., and the specific gravity of the foams subjected to this process is higher than that of the resin foams in the range of 0.6 to 0.8. On the other hand, resin-based foams have high dimensional stability and are suitable for high foaming ratio, so that they have better weight reduction characteristics than rubber-based foams, but have high hardness and poor slip resistance.

Therefore, the present invention, as a result of research efforts to solve the problems of the conventional shoe outsole foam, the rubber component selected from isoprene rubber and butadiene rubber as a base material in the conventional shoe outsole foam, 1,2-polybutadiene and ethylene It is based on a blend of resin components composed of / α-olefin copolymers, which contains a conventional crosslinking agent, a foaming agent and an additive for rubber, and is crosslinked and foamed by applying a conventional press method as it is, thereby achieving low specific gravity. It is an object of the present invention to provide a foam composition for shoe outsole having excellent wear resistance and elasticity while maintaining.

The present invention is based on a rubber or resin component and blends thereof, in which the foam composition for shoe outsoles containing a filler, an activator, a foaming agent and a conventional rubber additive,

The substrate is a shoe sole foam containing 30 to 60% by weight of the rubber component selected from isoprene rubber and butadiene rubber and 40 to 70% by weight of the resin component consisting of 1,2-polybutadiene and ethylene / α-olefin copolymer The composition is characterized by that.

The present invention will be described in more detail as follows.

The present invention is a shoe sole foam having a low specific gravity and excellent wear resistance manufactured based on a blend of a rubber component selected from isoprene rubber and butadiene rubber and a resin component composed of 1,2-polybutadiene and ethylene / α-olefin copolymer. It relates to a composition.

In the present invention, a blend of rubber and resin is used as a base material of a shoe outsole, and the rubber usage is changed for hardness control.

As the rubber used in the present invention, a mixture of one or two selected from isoprene rubber, butadiene rubber, and natural rubber is used at 30 to 60% by weight. At this time, when the content of the rubber component is less than 30% by weight, the hardness appears to be 75 C or more, so it is unsuitable as a foam for shoe outsoles, whereas when it exceeds 60% by weight, there is a problem that heat treatment is required for 1 hour or more. In particular, the isoprene rubber shows an excellent effect on the low hardness characteristics, when the resin composition exceeds 50% by weight, the isoprene rubber is blended with 10 to 20% by weight of the total composition to facilitate the hardness control.

In the present invention, 40 to 70% by weight of a resin composed of 1,2-polybutadiene and an ethylene / α-olefin copolymer is used. At this time, if the use content is less than the above range, there is a problem that the dimensional stability and wear resistance is remarkably inferior, on the other hand, since the hardness exceeds 75 C, it is not suitable as a shoe outsole foam and the foam is brittle. In particular, the resin component constituting the substrate has a feature in which the 1,2-polybutadiene and the ethylene / α-olefin copolymer have a weight ratio of 10:90 to 90:10.

Silica is used as the filler used in the foam for shoe outsole of the present invention, and its content is used in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the substrate. At this time, when the amount of the filler used is less than 0.5 parts by weight, there is a problem in that the wear resistance is poor, whereas when it is more than 20 parts by weight, it is difficult to manufacture the foam, which is not preferable.

Polyethyleneglycol (PEG 4000) is used as an activator for inhibiting the deactivation of an additive such as a crosslinking agent due to the adsorption characteristic of silica used as the filler, and the content thereof is used at 5 to 7.5 wt% based on silica. do.

As a blowing agent used in the foam for shoe outsole of the present invention, an azo compound having a decomposition temperature of 150 to 160 is used, and is used in an amount of 1 to 6 parts by weight based on 100 parts by weight of the substrate. When the use amount of the blowing agent is less than 1 part by weight, there is a problem in that a foam having a specific gravity of 0.7 or more and a hardness of 70 or more is produced. When the content of the foaming agent is more than 6 parts by weight, the specific gravity drops to 0.25 or less. The problem of inferior stability occurs. When the decomposition temperature of the blowing agent is 150 ° C. or less, premature foaming occurs during compounding, and since the blowing agent having 160 ° C. or more requires 15 minutes or more of press time (molding time), the productivity is not preferable.

In addition, sulfur and an organic peroxide crosslinking agent having a half-life temperature of 130 to 200 ° C. for 1 minute are used in order to sufficiently collect the decomposition gas generated above the decomposition temperature of the foam and impart high temperature viscoelasticity to the resin. 0.02 to 1.5 parts by weight, preferably 0.05 to 1.0 part by weight. If the amount is less than 0.02 parts by weight, the crosslinking is insufficient, so that the high temperature viscoelasticity of the resin is not maintained when the foam is decomposed. If the content exceeds 1.5 parts by weight, the hardness is rapidly increased due to overcrosslinking, and the foam bursts.

Examples of such crosslinking agents include t-butylperoxyisopropyl carbonate, t-butylperoxylaurylate 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-butyldiperoxyphthalate, t-dibutylperoxymaleic acid, cyclohexanone peroxide, t-butylcumylperoxide, t-butylhydroperoxide, t-butylperoxybenzoate, dicumylperoxide, 1,3-bis (t-butylperoxyisopropyl) benzene, methylethylketone peroxide, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5- Di (t-butylperoxy) hexane, di-t-butylperoxide, 2,5-dimethyl-2,5- (t-butylperoxy) -3-hexyne, n-butyl-4,4-bis ( t-butylperoxy) valerate, alpha (alpha) '-bis (t-butylperoxy) diisopropyl benzene, etc. are mentioned.

In addition, in the present invention, it is essential to control the crosslinking time (t ₉₀ ) in order to shorten the molding time, and to control the molding time to 5 to 10 minutes when the press is 150 to 160 ° C., as triallyl cyanurate ( TAC) is used in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the substrate. If the crosslinking aid is used less than 0.05 parts by weight, there is little effect of the crosslinking aid, and if it exceeds 0.5 parts by weight, the foam bursts due to overcrossing, similar to when the amount of the crosslinking agent exceeds 1.5 parts by weight.

In addition, the present invention uses the above additives and conventional additives used in preparing foams such as metal oxides such as zinc oxide and titanium oxide, stearic acid, and various pigments may be used in consideration of color.

Referring to the manufacturing process of the shoe outsole foam according to the present invention made of the above composition components are as follows.

First, a compound in which a rubber compound, a crosslinking agent, and a foaming agent are mixed into a polymer system based on a blend of 1,2-polybutadiene and an ethylene / α-olefin copolymer in isoprene rubber or butadiene rubber in a sheet form. The foamed product can be produced by cross-linking and foaming by pressing in a sealed mold and pressing for 5 to 10 minutes at a high temperature and high pressure of 150 to 160 ° C and 100 to 150 kg / cm 2 using a press. When the foam is heat-treated at 70 ° C. for 0.5 to 1 hour and then cut into a predetermined size using a cutter, a foam for shoe outsole having a specific gravity having a low specific gravity in the range of 0.3 to 0.65 can be produced.

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

Examples 1-4 and Comparative Examples 1-2

The foam composition for shoe outsole was prepared in the composition and content as shown in Table 1 using the following method.

A 1,2-polybutadiene and ethylene / α-olefin copolymer is blended into isoprene rubber using a hermetic mixer, and zinc oxide, stearic acid, silica, and PEG 4000 are added to the blend of rubber and resin as a base uniformly. Kneaded until dispersed. Then, when the crosslinking agent, the crosslinking aid and the blowing agent were added, the internal temperature of the hermetic mixer was 110 ° C. or lower, and further kneaded for about 5 minutes. After the closed mixing process, the additives are finely dispersed using an open roll mill, manufactured in a sheet form using calendar rolls, and then cut into a predetermined size and put into a mold under conditions of 150 to 160 ° C. and 100 to 150 kg / cm 2. And press-molded for 5 to 10 minutes to prepare a foam. The foam thus obtained is subjected to a heat treatment process for about 40 minutes in an oven at about 70 ° C., whereby the heat shrinkage rate (a measure of dimensional stability) appears within 1%.

The physical properties of the foam compositions for shoe outsoles prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were tested in the following manner, and the results are shown in Table 2 below.

[Test Methods]

① Hardness: measured using ASTM D2240 method.

② Specific gravity: Measured using a model DMA-3 which is an automatic specific gravity measuring device of Ueshima in the skin-on state.

③ Tensile strength: measured using ASTM D-412 method.

④ Abrasion resistance (NBS): NBS wear tester (ASTM 1630) was used to measure the wear resistance of the foam, the wear resistance was measured as follows.

⑤ Akron: It was measured using the method according to KSM 6624.

⑥ heat treatment: heat treatment was performed at 70 ℃.

As shown in Table 2, Examples 1 to 4 have excellent physical properties, whereas Comparative Example 1 has a limit for lowering the hardness, and wear resistance is about 35% or less than that of the foam of the present invention. , Comparative Example 2 shows low hardness properties, but the productivity is low because the specific gravity is high, the dimensional stability is poor, and a heat treatment step of 20 hours or more is required. That is, the rubber foam is superior to the wear resistance of the resin foam, but it can be seen that about 60% or less than the wear resistance of the foam for outsole of the present invention.

As described above, the foam composition for shoe outsole of the present invention is based on a blend of a rubber component selected from isoprene rubber and butadiene rubber and a resin component selected from 1,2-polybutadiene and ethylene / α-olefin copolymer. By containing crosslinking agent, foaming agent, and rubber additives, and pressing, crosslinking, foaming, and molding, it is suitable for use on shoe outsoles because it contributes to the weight reduction of shoes due to its excellent wear resistance, dimensional stability and elasticity at low specific gravity. .

Claims (3)

Based on rubber or resin components and blends thereof, 0.5 to 20 parts by weight of filler, 1 to 6 parts by weight of foaming agent, 0.02 to 1.5 parts by weight of crosslinking agent, and 5 to about 1 part by weight of 100 parts by weight of the substrate described above. A foam composition for shoe insoles containing 7.5% by weight of an activator, The substrate contains 30 to 60% by weight of the rubber component selected from isoprene rubber and butadiene rubber and 40 to 70% by weight of the resin component composed of 1,2-polybutadiene and ethylene / α-olefin copolymer. Foam composition for shoe outsoles. The foam composition for shoe insole according to claim 1, wherein the resin component constituting the substrate comprises 1,2-polybutadiene and an ethylene / α-olefin copolymer having a weight ratio of 10:90 to 90:10. . The foam composition for shoe outsoles according to claim 1, wherein the foam composition for shoe outsoles has a specific gravity of 0.3 to 0.65.