KR20060092457A - Thermoplastic elastomer compounds for footwear outsole with enhanced abrasion resistance - Google Patents

Abstract

The present invention relates to a thermoplastic rubber composition for improved shoe outsole, and more particularly, to a styrene-based thermoplastic rubber, high styrene resin masterbatch, high impact polystyrene, and polystyrene. By blending the resin selected from), the injection molding is possible while the wear resistance is improved, reducing the occurrence of debris during wear, which is the biggest weakness of the conventional rubber outsole rubber, and compared with the conventional styrene thermoplastic rubber for shoe outsole A thermoplastic rubber composition for shoe outsoles that can be manufactured at similar cost.

Abrasion Resistant, Shoe Sole, Thermoplastic Rubber, Debris

Description

Thermoplastic elastomer compounds for footwear outsole with enhanced abrasion resistance}

1 is a result of observing the debris test results of the specimen prepared in Comparative Example 1 with an optical microscope.

2 is a result of observing the debris test results of the specimen prepared in Example 1 with an optical microscope.

3 is a result of observing the debris test results of the specimen prepared in Example 2 with an optical microscope.

4 is a result of observing the debris test results of the specimen prepared in Example 3 with an optical microscope.

5 is a result of observing the debris test results of the specimen prepared in Example 4 with an optical microscope.

The present invention relates to a thermoplastic rubber composition for injection-resistant wear outsole, more specifically, a styrene-based thermoplastic rubber, high styrene resin masterbatch (High styrene resin masterbatch), high impact polystyrene (High Impact Polystyrene) and By blending a resin selected from polystyrene, the present invention relates to a thermoplastic rubber composition for shoe outsole, which is capable of injection molding and improves abrasion resistance, thereby reducing the occurrence of debris during wear, which is the biggest weakness of the conventional shoe sole thermoplastic rubber.

In general, thermoplastic rubbers have the characteristics that injection molding is possible compared to thermosetting rubbers and there is no need to add a crosslinking process, thereby enabling high efficiency of mass production and productivity. In addition, it has many advantages, such as the characteristics of environmentally friendly materials, such as re-processing to suppress the occurrence of scrap.

However, styrene-butadiene block copolymer (SBS), which is a thermoplastic rubber used for shoe outsoles, is significantly lower in abrasion resistance than thermosetting rubbers widely used for shoe outsoles, and thus does not require high physical properties such as children's shoes or women's shoes. Some are used only in low-cost products.

On the other hand, urethane-based thermoplastic elastomer (TPU), which has the advantages of excellent mechanical strength and wear resistance, is expensive and has a disadvantage in that weather resistance and grip characteristics are inferior to those of thermosetting rubber, making it difficult to use as a shoe outsole.

Therefore, many researches such as blends have been carried out to compensate for these disadvantages, but injection molding is possible, but wear resistance is improved enough to be used for shoe outsoles, and thermoplastic rubbers have not yet appeared to replace conventional thermosetting rubbers for shoe outsoles.

Accordingly, an object of the present invention for solving the problems as described above is to provide a thermoplastic rubber composition capable of injection molding to improve the wear resistance to reduce the occurrence of debris during wear, which is the biggest weakness of the conventional rubber outsole thermoplastic rubber have.

It is still another object of the present invention to provide a thermoplastic rubber composition for shoe outsoles, which is similar in cost to conventional shoe styrene-based thermoplastic rubbers.

Accordingly, the inventors of the present invention have made efforts to meet the above expectations, and as a result, styrene-based thermoplastic rubber, high styrene resin masterbatch, high impact polystyrene, or polystyrene Thermoplastic resin composition obtained by blending the selected resins with melt compounding method enables injection molding, but also improves abrasion resistance, thereby reducing the occurrence of debris during wear, which is the biggest weakness of the conventional rubber outsole thermoplastic rubber. The present invention was completed.

The present invention 70 to 90 parts by weight of styrene-based thermoplastic rubber; 100 parts by weight of a styrene-based thermoplastic rubber mixture consisting of 10 to 30 parts by weight of one or more mixtures selected from high styrene resin masterbatch, high impact polystyrene and polystyrene; Characterized by the thermoplastic rubber composition for a shoe outsole comprising 1 to 5 parts by weight of filler for rubber, 0.5 to 5 parts by weight of processing oil based on 100 parts by weight of the styrene-based thermoplastic rubber mixture.

The present invention also includes a shoe outsole made of the thermoplastic rubber composition.

Hereinafter, the present invention will be described in detail.

The present invention enables injection molding, but also improves wear resistance, thereby reducing debris during wear, which is the weakest point of conventional thermoplastic rubber for shoe outsole, and can be manufactured at a cost similar to that of conventional styrene thermoplastic rubber for shoe outsole. A thermoplastic rubber composition for shoe outsoles designed to

As a method for improving the wear resistance of styrene-butadiene block copolymer (SBS), a thermoplastic rubber used for shoe outsoles, research and development has been conducted to blend a polymer resin having better wear resistance than styrene-butadiene block copolymer. .

However, even when blending polymers having excellent wear resistance as described above, injection molding is possible and at the same time wear resistance is improved enough to be used for shoe outsole, thermoplastic rubber having properties that can replace the existing thermosetting rubber for shoe outsole is not developed. I couldn't.

The most significant influence on the wear of rubber is the ridge that is produced when the rubber wears, and the ridge is bent in the rubbing direction when the rubber is rubbed, in which case tension occurs in the rubbing direction and consequently the tip of the ridge. The part is broken down, where the broken part is a small piece of rubber called debris produced when the rubber wears out.

The inventors of the present invention have noted that the debris occupies most of the worn portion of the rubber, it was conceived that increasing the breaking strength of the tip portion can improve the wear resistance.

That is, it is possible to reduce the formation of debris by blending a polymer having a stronger fracture strength than the styrene-based thermoplastic rubber to improve the fracture strength, and eventually improve the wear resistance of the rubber composition according to the reduction of the fragment formation. There is this.

Therefore, the present inventors, unlike the conventional method to improve the wear resistance by blending a polymer with excellent wear resistance, although the wear resistance is better than the conventional styrene-based thermoplastic rubber, the miscibility is better than the styrene-based thermoplastic rubber, and the breaking strength than the styrene-based thermoplastic rubber It is a feature of the technical construction to mix styrene resin having excellent qualities.

Therefore, in the present invention, by blending a styrene-based thermoplastic rubber and a resin selected from a high styrene resin masterbatch, high impact polystyrene and polystyrene, injection molding is possible, but wear resistance is improved to improve the physical properties to be used for outsoles of shoes, The present invention has invented a thermoplastic rubber composition for shoe outsoles that can be manufactured at a cost similar to that of conventional styrene-based thermoplastic rubbers.

Hereinafter, each component constituting the rubber outsole rubber composition of the present invention will be described in detail.

First, the base material of the rubber outsole shoe composition of the present invention contains 70 to 90 parts by weight of styrene-based thermoplastic rubber. The most suitable of these styrene-based thermoplastic rubber is styrene-butadiene block copolymer (SBS), in particular, it is preferable to use a styrene content of 25 to 45% by weight. At this time, if the amount of the styrene-based thermoplastic rubber is less than 70 parts by weight, there is a problem that the elasticity is lowered. If the amount is more than 90 parts by weight, the blend characteristics are deteriorated.

In addition to the styrene-based thermoplastic rubber, 10 to 30 parts by weight of one or more mixtures selected from high-styrene resin masterbatch, high-impact polystyrene, and polystyrene may be used as a base material of the rubber composition for shoe outsole of the present invention. When it is less than 10 parts by weight, there is no blending effect, and when it exceeds 30 parts by weight, there is a problem in that the elasticity is lowered while the hardness is increased.

The high styrene resin masterbatch is a masterbatch of styrene-butadiene copolymer latex having a styrene content of 20 to 30% by weight and a high styrene resin latex and having a total styrene content of 60 to 70% by weight. It is recommended to use a resin masterbatch. Such a high styrene resin masterbatch also plays a role as a plasticizer at high temperature in rubber compounding, thereby improving workability and also improving tear resistance and flex resistance.

The high-impact polystyrene is a functional resin copolymerized with styrene monomer and butadiene, which serves to improve the fragility, which is one of the major drawbacks of polystyrene, but preferably 6 to 12 wt% of butadiene.

Since the polystyrene is colorless and transparent, the coloring is free and the thermal stability and fluidity are good at the time of dissolution. Particularly suitable for injection molding, the dimensional stability of the molded article is good.

The present invention may be used 1 to 5 parts by weight of a rubber filler with respect to 100 parts by weight of the base material, the fillers that can be used as a conventional rubber filler can be used according to the choice of those skilled in the art, preferably It is better to use silica. In addition, in order to reduce friction, process oils such as silicone oil may be used in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the base material. In addition, antioxidants commonly used in the art and zinc stearate to prevent adhesion during kneading Various additives, such as lubricant, can be suitably selected and used.

As described above, the styrene-based thermoplastic rubber is selected from high-styrene resin masterbatch, high-impact polystyrene, and polystyrene, and is based on blending by melt compounding method. Here, silica, antioxidant, and other additives are used as fillers for general rubber. The mixture obtained by injecting into a hermetic mixer to be uniformly dispersed is more finely dispersed using an open roll mill, and the material thus obtained is prepared in pellet form using an extruder and then used by injection processing.

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

Examples 1-4 and Comparative Examples

Next, the composition shown in Table 1 was introduced into a hermetic mixer, and kneaded by melt compounding for 5 to 10 minutes to uniformly disperse the composition. At this time, the temperature inside the mixer may be maintained at about 150 ° C. to minimize molecular chain breakage due to shear force and aging due to heat.

After the kneading step described above, the open roll mill was finely dispersed in a mixture at a temperature in the range of 100 to 130 ° C. to prepare a thermoplastic rubber composition, and after a suitable amount was put into a closed mold having a thickness of 2-3 mm, a press machine was used. Press for 3 to 5 minutes at a high temperature / high pressure of 140 ~ 160 ℃, 150 kg / ㎠ using a cold press, 2 to 4 minutes at a low temperature / high pressure of 100 kg / ㎠ at a temperature around 20 ℃ using a cold press The specimen was prepared by pressing.

Test Example

Physical properties of the specimens prepared according to Examples 1 to 4 and Comparative Examples were measured by the following methods, and the results are shown in Table 1 below.

1. Hardness: measured using the method of ASTM D2240.

2. Specific gravity: It was measured using an automatic specific gravity measuring device (model MS-2150) of Ueshima in the skin-on state.

3. Tear strength was measured using the method of KS M6518.

4. Wear resistance (NBS): NBS wear test (KS M6625) was used to measure the wear resistance characteristics of the test specimen was calculated by the following equation (1).

In Equation 1, AI is the wear resistance (%), R ₁ is the number of revolutions required to wear 2.54 mm of the specimen to be tested, R ₂ is the wear rate of the reference specimen (RMA) 2.54 mm to wear Average rotation speed.

5. Wear resistance (DIN): DIN wear test (DIN 53516) was used to measure the wear resistance of the test specimen and was calculated by the following equation.

In Equation 2, m ₁ is the weight of the specimen before the test (g), m ₂ is the weight of the specimen after the wear test (g), d is the density of the specimen, g is the weight loss of the DIN standard rubber Wear rating shown.

6. Melt Index (Melt Index): Measured according to ASTM D 1238.

7. Debris test: In order to observe the change of debris generated during wear, which is a major disadvantage of styrenic thermoplastics, the surface of the specimen was made different from each other by applying a certain distance (10 cm) to the glass plate. After repeated cycles, the glass plate surface was observed using an optical microscopy. The optical microscope observation results are shown in the accompanying drawings, FIGS. 1 to 5.

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Substrate (part by weight) Styrenic thermoplastics ¹⁾ 80 80 80 80 100 Gostyrene resin batch ²⁾ 20 - - - - High Impact Polystyrene 3) - 20 - - - Polystyrene 4) - - 20 20 - Additives (parts by weight) Processing oil5) - - - One - Filler ⁶⁾ - - - 5 - Zinc stearate - - - 1.2 - Antioxidant ⁷⁾ 0.1 0.1 0.1 0.1 0.1 Properties Shore A type 69 73 74 83 74 importance 0.96 0.96 0.96 0.98 0.94 Abrasion Resistance (NBS,%) 293 419 418 430 240 Tear strength (kgf / cm) 64 78 73 78 58 Wear resistance (DIN, ㎣ loss) 67 64 67 62 89 Melt Index 200 ?? / 5kg (g / 10min) 4.33 3.24 4.44 4.35 4.68 1) KTR601 (styrene-butadiene block copolymer), Kumho Petrochemical 2) KHS68, Kumho Petrochemical 3) HI-425, Kumho Petrochemical 4) GP-125, Kumho Petrochemical 5) KF-96 ( Silicone oil), Shin-Etsu Co., Ltd. 6) Z-155 (Silica), Rhodia Kofran Co., Inc. 7) SONGNOX 1010, Songwon Industrial Products

As shown in Table 1, the specimens obtained in Examples 1 to 4 of the present invention have superior wear resistance and tear resistance than Comparative Example 1 using only styrene-butadiene block copolymers used as conventional thermoplastic rubbers for shoe soles. It can be seen that the melting index is similar to Comparative Example 1 using only the styrene-butadiene block copolymer as a substrate.

That is, in the case of DIN wear, the smaller the wear value, the better the wear resistance. In the case of NBS wear, the higher the value, the better the wear resistance.

As shown in Table 1, the specimen using the thermoplastic rubber composition for shoe outsole prepared according to Examples 1 to 4 of the present invention, the wear resistance is 62 ~ 67 as a result of DIN wear test, the conventional shoe outsole for the comparative example It was confirmed that the wear of the specimen made of the styrene-butadiene block copolymer (SBS), which is a thermoplastic rubber, was also improved compared to 89. In addition, the results of the NBS abrasion test also shows that the specimens made from the thermoplastic rubber composition for shoe outsole prepared according to Examples 1 to 4 of the present invention wear resistance 293 ~ 419, styrene which is a conventional thermoplastic rubber for shoe outsole shown as a comparative example It was confirmed that the wear of the specimen made of butadiene block copolymer (SBS) was also improved compared to 240.

Meanwhile, as shown in FIGS. 1 to 5, fragment generation, which is one of the biggest drawbacks of the wear of the thermoplastic rubber for shoe sole, is that the fragment generation of the specimen obtained in Examples 1 to 4 of the present invention is conventional shoe sole. It can be seen that the styrene-butadiene block copolymer used as the thermoplastic rubber for the resin is much reduced than the comparative example 1 using only as a substrate.

As described above, according to the present invention, the thermoplastic rubber composition capable of injection molding can reduce debris during wear, which is the biggest weakness of the conventional thermoplastic rubber for shoe outsole, and thus has improved wear resistance. Can be obtained.

Claims (2)

70 to 90 parts by weight of styrenic thermoplastic rubber; 100 parts by weight of a styrene-based thermoplastic rubber mixture consisting of 10 to 30 parts by weight of a mixture of one or more selected from high styrene resin masterbatch, high impact polystyrene, and polystyrene; 1 to 5 parts by weight of a filler for rubber and 0.5 to 5 parts by weight of processing oil, based on 100 parts by weight of the styrene-based thermoplastic rubber mixture. A shoe outsole made of the rubber composition of claim 1.

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