KR20010081540A - High performance thermoplastic rubber with low mfi - Google Patents

Abstract

PURPOSE: Provided is a composition of high quality thermoplastic rubber which has good abrasion resistant, tearing strength and tensile strength properties. Conventional thermoplastic rubber is used in cheap products because it has poor mechanical strength and abrasion strength compared with thermoset rubber whose main use is a shoe sole material. CONSTITUTION: The composition comprises polystyrene thermoplastic rubber alone or thermoplastic resins such as thermoplastic olefin resin, ethylene/α-olefin copolymer, ethylene/vinylacetate copolymer in a ratio of 5-25wt.% to the polystyrene or blend with thermoset resins like natural rubber, synthetic rubber in the amount of not interfering thermoplastic character which is 3-15wt.%, together with usual additives such as an anti-oxidant, an anti-abrasion agent, a UV stabilizer and an improver for processing like silicone oil or silicone rubber of 0.5-7wt.%. The composition is characterized in that 5-25wt.% cheap shoe sole scraps of thermoplastic rubber is utilized and the melt flow index (MFI) is 0.01-10.

Description

High physical thermoplastic rubber composition. {HIGH PERFORMANCE THERMOPLASTIC RUBBER WITH LOW MFI}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high physical thermoplastic rubber composition characterized by molding by heating and cooling, and in particular, a high physical thermoplastic rubber composition which not only has excellent wear resistance, tensile strength and tear strength, but also exhibits high tensile strength as compared with thermosetting rubber. It is about.

In general, thermoplastic rubbers are capable of automation (injection) of molding methods, can suppress generation of waste materials, and are frequently used for shoe outsoles due to ease of coloration and the like.

However, these thermoplastic rubbers are used mainly for low-cost products due to their poor mechanical properties. In particular, the thermoplastic rubbers do not require high physical properties such as children's shoes or women's shoes due to their low mechanical strength and abrasion resistance compared to thermosetting rubbers that are generalized for shoe outsoles. This is mainly used for.

On the other hand, thermosetting rubber is generally used for shoe outsoles because of excellent physical properties and appearance characteristics compared to thermoplastic rubber compositions, but since it is thermosetting, it is difficult to recycle waste scraps generated during molding, which may cause environmental problems. Weight reduction (specific gravity 1.12-1.15) has a difficult problem.

On the other hand, thermoplastic rubber can be manufactured by injection molding, has less waste materials, can be reused, and can be lightened by more than 10% compared to thermosetting rubber. However, it has low mechanical strength and abrasion resistance. There is a limit to the use.

Accordingly, an object of the present invention for solving the above problems is to provide a high physical thermoplastic rubber composition excellent in wear resistance, tensile strength and tear strength.

Another object of the present invention is to use a high-temperature thermoplastic rubber composition that can be used to produce a high physical shoe sole with excellent moldability because the cross-linking process by pressurization / heating press is not necessary while using the existing thermosetting rubber production equipment as it is. In providing.

The present invention according to the first aspect for achieving the above object is to use styrene-based thermoplastic rubber alone or styrene-based thermoplastic resin, ethylene / α-olefin copolymer, ethylene / vinyl acetate A thermoplastic rubber composition prepared by mixing a thermoplastic resin such as a copolymer or a thermosetting rubber such as natural rubber or synthetic rubber in a range that does not impair thermoplastic as a whole, is prepared by mixing rubber additives. .

Hereinafter, preferred embodiments of the present invention will be described in detail. In describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

The present invention is based on using styrene-based thermoplastic rubber alone or blending styrene-based thermoplastic resin, olefin-based thermoplastic resin, ethylene / α-olefin copolymer, and ethylene / vinylacetate copolymer. Rubber additives such as fillers, abrasion resistance improvers, processing improvers, antioxidants, UV stabilizers and other additives are added to disperse uniformly to form sheets or pellets using a calender, roll or extruder, and then again. It is a thermoplastic rubber composition characterized in that the shoe outsole is manufactured by heating and cooling in a press. The wear resistance, tensile strength and tear strength may be superior to those of a styrene-based thermoplastic rubber composition characterized by injection molding. In addition, it exhibits higher tensile strength than thermosetting rubber. And it relates to the physical properties of the thermoplastic rubber composition.

In the present invention, since the thermoplastic rubber composition adopts a compression molding method by heating and cooling rather than molding by injection, there is no limitation on the melt flow index of the thermoplastic rubber composition, so that a high molecular weight thermoplastic resin can be used. In addition to the additives that can not be used in the composition for injection molding can also be applied to the high physical properties, and furthermore, because the composition is basically thermoplastic, it is possible to reuse the waste materials generated during the molding process.

On the other hand, styrene-based thermoplastic rubber is mainly used to manufacture the thermoplastic rubber composition of the present invention, in order to improve hardness and physical properties, improve workability or improve weather resistance, an olefin-based thermoplastic resin, ethylene / α-olefin copolymer, ethylene / vinyl It is possible to blend an acetate copolymer or the like, and furthermore, it is also possible to use a thermosetting rubber within a range that does not inhibit thermoplasticity as the entire substrate.

Styrene-based thermoplastic rubbers usable in the present invention may be those having an styrene content of 25 to 45% and containing oil. Styrene-based thermoplastic rubber having a styrene content of 25% or less has low hardness and is not suitable for shoe outsoles, and styrene-based thermoplastic rubber having 45% or more has high hardness and poor elasticity.

In the present invention, the substrate is based on styrene-based thermoplastic rubber, but, if necessary, within the range of not inhibiting thermoplastic resins or thermoplastics such as olefinic thermoplastic resin, ethylene / α-olefin copolymer, ethylene / vinylacetate copolymer, etc. It is possible to blend thermosetting rubbers including natural rubber and synthetic rubber.

Blend ratio of the thermoplastic resin or thermosetting rubber is most suitable when 5 to 15 parts by weight, there is no blending effect at 5 parts by weight or less, and if it exceeds 15 parts by weight, there is a problem that the elasticity is lowered as the hardness increases. In particular, when blending natural rubber or synthetic rubber as a type of thermosetting rubber, it is possible to improve appearance characteristics or workability, but when blended in a large amount, thermoplastics may be lost or physical properties may be lowered and hardness may be lowered. Synthetic rubber blendable to styrene thermoplastic rubber is not particularly limited, but diene-based synthetic rubber such as butadiene rubber and styrene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylonitrile butadiene rubber, and the like, It is possible to use.

In the present invention, silica may be used as a reinforcing filler to improve wear resistance. The amount of silica used is preferably 1 to 5 parts by weight based on 100 parts by weight of the base material. At 5 parts by weight or more, the workability and working environment and dispersibility are reduced, and at 1 part by weight or less, the effect of improving the wear resistance cannot be expected.

Meanwhile, paraffinic oil, naphthenic oil, aromatic oil, silicone oil and silicone rubber may be used to improve processability. When using paraffin oil, silicone oil and silicone rubber, the weather resistance is particularly good. Naphthenic oils and aromatic oils are not only inferior in weatherability compared to paraffinic oils, but also have a dark color, which limits their application. The amount of paraffinic oil is suitably 30 parts by weight or less based on 100 parts by weight of the base material, and the amount of the oil is different depending on the styrene content and the melt index (MI) of the styrene-based thermoplastic rubber. The higher the styrene content and the lower the melt index (MI), the higher the oil consumption. The lower the styrene content and the higher the melt index (MI), the lower the oil consumption is desirable. The amount of oil changes the flowability of the rubber composition other than processability, resulting in an increase in the melt index (MI). The melt index (MI) of the thermoplastic rubber composition used in the injection molding process is generally 15 g / 10 min or more, so the rubber Although the high molecular weight of the composition is impossible to show the improvement in physical properties, the thermoplastic rubber composition developed in the present invention can be applied to a melt index of less than 15g / 10min, it is possible to use a high molecular weight thermoplastic resin Rubber compositions of physical properties can be prepared. The silicone oil and the silicone rubber may be used in an amount of 0.5 to 7 parts by weight based on 100 parts by weight of the base material. If it is 0.5 parts by weight or less, there is no addition effect, and in the case of 7 parts by weight or more, workability is inferior and there is little effect of improving physical properties compared to the amount added.

In the present invention, it is possible to use a heat stabilizer, an antioxidant and an ultraviolet stabilizer to improve the durability of the thermoplastic rubber composition, and also to use a lubricant such as zinc stearate to prevent adhesion of the composition during kneading. It is possible.

The present invention is characterized in that the shoe outsole is manufactured by heating and cooling using the above-mentioned thermoplastic rubber composition. As it has a matting effect, it is possible to produce high value products with excellent texture. Furthermore, as mentioned above, since the composition itself is basically thermoplastic, it is possible to recycle waste scrap, thereby producing environmentally friendly products.

Referring to the method for manufacturing a shoe outsole by heating and cooling using the high-temperature thermoplastic rubber composition prepared as described above. However, the scope of the present invention once again reveals that the thermoplastic rubber composition for shoe outsole suitable for such a manufacturing method is not a method for producing a shoe outsole by heating and cooling.

An example of a shoe outsole manufacturing method by heating and cooling will be described. First, the rubber composition is prepared in a sheet or pellet form and put into a closed mold, and then the press machine is pressed at 140 to 160 ° C. and 100 kg / cm ² . By pressing for 3 to 5 minutes under high temperature / high pressure and 5 to 7 minutes under low temperature / high pressure of 100 kg / cm ² below 20 ° C., an outsole having excellent tensile strength and wear resistance can be manufactured.

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

5 parts by weight of paraffin oil, 1 part by weight of silicone oil, 0.25 parts by weight of antioxidant, 0.3 part by weight of UV stabilizer, and wax 0.2 by 100 parts by weight of styrene thermoplastic rubber LG501 and LG475 blended at 40% by weight and 60% by weight, respectively. The parts by weight were introduced into a hermetic mixer and kneaded for 7 to 10 minutes so as to be uniformly dispersed. At this time, the internal temperature should be maintained around 150 ℃ to minimize the molecular chain is cut by the shear force of the processing equipment.

After such a kneading process, when finely dispersed using an open roll mill, a high physical thermoplastic rubber composition is produced, and the sheet thickness or pellets must be different according to the model of the product manufactured by the heating / cooling method. In order to compare the properties of the high-molecular thermoplastic rubber composition thus prepared, it was placed in a closed 2 ~ 3mm thick flat plate mold, and then pressed for 3 ~ 5 minutes under high temperature / high pressure of 140 ~ 160 ° C and 100kg / cm ² using a press. After pressing, the specimen was prepared by pressing it for 5 to 7 minutes under low temperature / high pressure of 100 kg / cm ² or less at 20 ° C. or less.

Example 2

100 parts of 70 wt% and 30 wt% of LG501 and LG485, styrene thermoplastic rubbers, 7.5 parts by weight of paraffinic oil, 1 part by weight of zinc stearate, 5 parts by weight of silica, 0.25 parts by weight of antioxidant, and UV stabilizer 0.3 Part by weight and 0.2 part by weight of wax were added to the hermetic mixer, and prepared in the same manner as in Example 1 above.

Example 3

10 parts by weight of paraffinic oil and 1.2 parts by weight of zinc stearate to 100 parts by weight of styrene thermoplastic rubbers LG501, LG475, KTR201 and LDPE724, which are polyolefin resins, in 15%, 40%, 35%, and 10%, respectively. , 1 part by weight of silicone oil, 5 parts by weight of silica, 0.25 parts by weight of antioxidant, 0.3 parts by weight of UV stabilizer, and 0.2 parts by weight of wax were added to a hermetic mixer, and manufactured in the same manner as in Example 1 above.

Comparative Example 1

7.5 parts by weight of paraffinic oil, 0.25 parts by weight of antioxidant, 0.3 parts by weight of UV stabilizer, and 0.2 parts by weight of wax are added to 100 parts of LG501 and LG475 blended with styrene thermoplastic rubber at 40% and 60% by weight, respectively. After that, it was prepared in the same manner as in Example 1.

Comparative Example 2

The physical properties of STE601 of Kumho Petrochemical commercialized and commercialized for shoe outsoles are shown as comparative examples.

On the other hand, the above-described compositions of Examples 1 to 3 and Comparative Examples 1 and 2 and the component ratio thereof are described in detail in Table 1.

[Test Methods]

Hardness: Measured using the method of ASTM D2240.

Specific gravity: The measurement was performed using a model DMA-3, an automatic specific gravity measurement device of Ueshima Corporation, in the skin-on state.

Tensile strength, tear strength: measured using the method of ASTM D-412.

Abrasion resistance (NBS): NBS (ASTM1630) was used to measure the wear resistance of the blowing agent and was calculated by the following equation.

Melt index (MI) was measured according to KS M3070.

On the other hand, the physical properties of the high-temperature thermoplastic rubber compositions prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were tested in the following manner, and the results are shown in Table 2.

That is, as shown in Table 2 to be described later, Examples 1 to 3 have excellent abrasion resistance in physical properties, whereas Comparative Example 1 has superior tensile strength as compared to Comparative Example 2, but the wear resistance is high physical property thermoplastic rubber of the present invention. Compared to the composition showed a level of less than about 35%, in Comparative Example 2 is a thermoplastic rubber composition produced in the past, it can be seen that the tensile strength and wear resistance is significantly lower than the thermoplastic rubber composition of the present invention.

As described above, the present invention has excellent wear resistance compared to the conventional thermosetting rubber not only can be replaced for the outsole of the shoe, but also can be used as it is, existing equipment is more economical, because it does not incur the expense of facility reinvestment Since waste materials are reusable, there is an increased effect of significantly reducing industrial waste and solving environmental pollution problems.

Claims (6)

In the thermoplastic rubber composition, Natural rubber within the range of not using styrene-based thermoplastic rubber alone or thermoplastic resins such as olefin-based thermoplastic resin, ethylene / α-olefin copolymer, ethylene / vinylacetate copolymer, or thermoplastic in styrene-based thermoplastic rubber Based on a blend of thermosetting rubbers, including synthetic rubbers, and by adding uniform fillers, abrasion improvers, processing improvers, antioxidants, UV stabilizers and other additives, which are common rubber additives, to uniformly disperse Or it is made of a sheet (sheet) or pellet form using an extruder, characterized in that the high physical thermoplastic rubber composition. The high physical property according to claim 1, wherein the blend ratio of thermoplastic resin such as olefin-based thermoplastic resin, ethylene / α-olefin copolymer, ethylene / vinylacetate copolymer blended to the polystyrene is 5 to 25% by weight. Thermoplastic rubber composition. The high physical thermoplastic rubber composition of claim 2, wherein the blend ratio of natural rubber and synthetic rubber is 3 to 15% by weight when the natural rubber and synthetic rubber are blended. The high physical thermoplastic rubber composition according to claim 1, wherein the melt flow index (MFI) of the thermoplastic rubber composition is 0.01 to 10. The high physical thermoplastic rubber composition according to claim 1, wherein 0.5 to 7 parts by weight of silicone oil or silicone rubber is used as a processing aid or a processing material preforming agent of the thermoplastic rubber composition. The high physical thermoplastic rubber composition according to claim 1, wherein 5 to 25 parts by weight of waste scrap generated when the shoe outsole is manufactured using the thermoplastic rubber composition is used.