JPH0826172B2 - Rubber composition for shoe soles - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a rubber composition for shoe soles.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Publication No. 48-11572 proposes a non-vulcanizable rubber compound prepared by compounding a natural rubber with a styrene-butadiene block copolymer or a styrene-isoprene block copolymer.

However, a rubber product molded from this compound has a low modulus and excellent slip resistance, but is poor in heat resistance and weather resistance and is used under extreme conditions such as shoe soles. As a result, it had a drawback of lacking durability.

Therefore, in rubber compounds such as shoe soles that require low modulus and slip resistance, natural rubber, isoprene rubber, diene rubber such as styrene-butadiene rubber, and a large amount of aromatic oil or naphthene oil are used. Since a mineral oil softener such as paraffin oil was added, after molding the shoe sole,
The leaching of the softening agent from the inside of the shoe sole causes bleeding, and the shoe sole is contaminated and the softening agent bleeding on the shoe sole surface deteriorates the slip resistance.

[0005]

SUMMARY OF THE INVENTION The present invention has a low modulus, slip resistance, heat resistance, cut resistance, weather resistance, and blur resistance.
It is intended to provide a rubber shoe sole having excellent dengue property.

[0006]

According to the present invention, 100 parts by weight of polyisoprene rubber is added to styrene block A.
3 to 30 parts by weight of a block copolymer having a styrene content of 5 to 50% by weight and 70% or more of the isoprene portion being hydrogenated and having a molecular weight of 70,000 to 400,000, and a petroleum-based polymer. JISK after crosslinking by adding 10 to 20 parts by weight of a softening agent and a conventional rubber compounding chemical
6301 Spring type hardness test A type hardness of 50 ~
The rubber composition for shoe soles is characterized in that it is 75.

In the present invention, as the polyisoprene rubber, synthetic rubber such as natural rubber and cis1.4 polyisoprene is used.

In the present invention, as the block copolymer of styrene and isoprene, a diblock copolymer of styrene and isoprene, or a triblock copolymer of styrene, isoprene and styrene is used. At least 70% of the constituent isoprene is hydrogenated. If the hydrogenation rate is less than that, the heat resistance and weather resistance of the obtained shoe sole will decrease. The molecular weight of the block copolymer of the present invention is limited to 70,000 to 400,000, as the molecular weight becomes lower than that, the mechanical strength such as tensile strength and elongation tear strength of the obtained shoe sole decreases. There is a drawback that the block copolymer bleeds on the surface of the shoe sole, and if the molecular weight is higher than that, there is a problem in that the viscosity increases at the time of molding the shoe sole and the mold flow is bad, resulting in a molded piece. In the present invention, the block copolymer has a styrene content of 5 to 50% by weight.
The reason is that if the styrene content is less than that, mold flow at the time of shoe sole molding becomes poor, and there is a problem in moldability,
Further, if the styrene content is more than that, there is a drawback that the flexibility, heat resistance and cut resistance of the obtained shoe sole are lowered. In the present invention, the addition amount of the block copolymer of styrene and isoprene is limited to 3 to 30 parts by weight based on 100 parts by weight of the polyisoprene rubber because the soles obtained when the addition amount is less than that. Tear strength, cut resistance,
This is because the heat resistance, weather resistance, wear resistance, and bleeding resistance are reduced, and if the amount added exceeds that value, the hardness of the obtained sole, 300% modulus, tensile strength, and wear resistance are reduced. . In the present invention, if necessary, general-purpose synthetic rubber such as styrene-butadiene rubber or butadiene rubber may be added to improve the moldability and wear resistance of the shoe sole.

In the present invention, aromatic petroleum oil, naphthene oil, paraffin oil and the like are used as petroleum softener. In the present invention, the amount of the petroleum-based softening agent added is limited to 10 to 20 parts by weight with respect to 100 parts by weight of the polyisoprene rubber, because the hardness of the obtained sole becomes higher when the addition amount is less than that. Too much, the flexibility and anti-slip properties of the sole will be reduced, and if the amount added exceeds this, the hardness of the obtained sole will be too low, the resilience of the sole will be reduced, and the blistering of the sole will be poor. Moreover, there is a drawback that the leaching of the softening agent from the sole causes the bridging.

In the present invention, a filler such as carbon black, white carbon, calcium carbonate, magnesium silicate, aluminum silicate, sulfur, dicumylperoxide, 1.1-bis (t-butylperoxide) is further added.
(Oxy) 3.3.5 Crosslinking agents such as organic peroxides such as trimethylcyclohexane, crosslinking accelerators such as dibenzothiazyl disulfide, 2-methylcaptobenzothiazole, tetramethylthiuram disulfide, etc. Rubber compounding chemicals such as auxiliaries, activators, antiaging agents, foaming agents, foaming auxiliaries and pigments are added.

In the present invention, the hardness of the rubber composition for shoe soles after cross-linking is limited to 50 to 75. The reason is that if the hardness is lower than that, the wear resistance is lowered, and if the hardness is higher than that, the rubber composition is flexible. This is because the anti-slip property is reduced.

The materials prepared as described above are blended and kneaded by a Banbury mixer, a kneading roll, etc., and the dough for sheeting is taken out, and if necessary, cut into pellets, ribbons, press molding, injection. The shoe sole is molded and crosslinked by molding or the like.

[0013]

[Examples] The rubber compounds shown in Examples 1 to 3 in the upper part of Table 1 were taken out to a thickness of 5 mm with a Banbury mixer and weighed and filled into a mold, and the press gel was applied at 160 ° C for 12 minutes. -The shoe sole was press-molded by heating and pressurizing with a pressure of 100 kg / cm ² , and the sole was similarly molded according to a comparative example, and the modulus, tensile strength, stretch ratio, tear strength, cut resistance, heat resistance, The weather resistance, anti-slip property, abrasion resistance and bridging resistance are compared and shown in the lower part of Table 1.

[0014]

As is clear from the comparative test results in the lower part of Table 1, the shoe soles obtained in Examples 1, 2 and 3 are superior in tensile strength and tear strength to the shoe soles obtained in Comparative Examples. It had strength, cut resistance, heat resistance, weather resistance, abrasion resistance and bridging resistance.

[0015]

[Table 1] Note 1 Septon (manufactured by Kuraray Co., Ltd.) Molecular weight about 100,000 Styrene content 13% Hydrogenation rate to isoprene 97% Note 2-6 Vulcanized rubber physical test method JISK6301-1
According to 975 Note 7 Sharpness with a sharp edged tool is visually compared with Comparative Example 1. Note 8: Garoon method is performed at 70 ° C ± 1 ° x 24H, and the residual ratio is a tensile strength of 120% or more and an elongation of 100% or more. ◎, Tensile strength 115% or more Elongation 95% or more ○, Tensile strength 100% or less Elongation 90% or less X Note 9 Outdoor exposure test (under-glass method) No change for 6 months or more ◎, 4 ~ Cracks changed in 6 months ○ Cracks changed in March to April △. Note 10 Place a test piece on a rubber mat, apply a constant load (w) on it, and pull one end of the test piece with a spring balance at a constant force and speed. With the value F, the static friction coefficient Ms = F / W was calculated and compared. The comparative example 1 is set as an index of 100, and 130 or more is excellent, and 100 to 1
30 is judged as ○. * 11 The abrasion amount was set as Comparative Example 1 using the Akron abrasion tester and compared with the standard.

Claims (1)

[Claims] 1. A molecular weight 70 comprising styrene block A and isoprene block B per 100 parts by weight of polyisoprene rubber, having a styrene content of 5 to 50% by weight, and at least 70% of the isoprene portion being hydrogenated. 1,000
˜400,000 block copolymer 3 to 30 parts by weight, petroleum-based softener 10 to 20 parts by weight, and a conventional rubber compounding chemical are added, and the hardness according to JIS K6301 spring type hardness test A type after crosslinking is 50 to 75. A rubber composition for shoe soles, which is 75.