Mineral composite rubber reinforcing material and use thereof

Abstract

The present application relates to rubber reinforcing material technical field, propose a kind of mineral composite type rubber reinforcing material and its application.A kind of mineral composite type rubber reinforcing material, including following weight parts component raw materials: white carbon black 10~60 parts, black mica 30~85 parts, feldspar powder 5~10 parts;Feldspar powder is composed of mass ratio 1~2:1:1 of potassium feldspar, calcium feldspar, sodium feldspar.By the above technical scheme, solve the problem that rubber reinforcing material in the related art is applied in rubber products, and the wear resistance of rubber products is poor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber reinforcing materials, in particular, relates to a mineral composite rubber reinforcing material and its application. BACKGROUND

[0002] In the development history of the rubber industry, with the continuous improvement of the performance requirements of rubber products in various application fields, the development of high-performance rubber reinforcing materials has become a key technical requirement. Traditional rubber reinforcing methods, such as using carbon black, although can improve the performance of rubber to some extent, but there are problems such as high cost, large energy consumption in production process and certain pollution to the environment, at the same time, single reinforcing material has limitations in improving the performance of rubber in many aspects, which is difficult to meet the comprehensive requirements of modern industry on rubber products in high strength, high wear resistance, high aging resistance and good processing performance.

[0003] Mineral reinforcing materials are rich in resources and relatively low in price, and their combination with rubber not only can reduce the cost of rubber products, but also can improve the performance of rubber by using the special performance of mineral reinforcing materials, which provides strong technical support for the wide application of rubber products in the fields of tires, rubber product industry, shoe sole manufacturing, etc.

[0004] However, in the research and application of mineral composite rubber reinforcing materials, there are still some challenges. In terms of wear resistance, the wear resistance of mineral composite rubber reinforcing materials has limited improvement, and the wear resistance decays quickly in complex environments, which seriously limits its application in more fields. Poor wear resistance not only shortens the service life of the product and affects its performance, such as tires, conveyor belts, seals, etc., due to poor wear resistance, the surface will quickly wear out, and the internal structure will also be damaged, greatly shortening the normal use cycle of the product. In the application of tires, poor wear resistance will cause the tire pattern to wear quickly, reduce the friction between the tire and the ground, and cause insufficient grip, which is prone to skidding during driving, especially on wet roads or at high speeds, which greatly increases the risk of traffic accidents. Poor wear resistance also limits the application range of the product and increases the maintenance cost. For example, in some high-friction and high-wear industrial production environments (mines, ports, etc.), rubber products with poor wear resistance cannot meet the demand for long-term stable operation, which greatly limits the application field of the material, hinders its market expansion and technology popularization, and requires regular inspection and replacement of worn parts, increasing the workload and cost of maintenance.

[0005] Therefore, it is urgent to develop a mineral composite rubber reinforcing material that can improve the wear resistance of rubber products when applied in rubber products. SUMMARY

[0006] The application provides a mineral composite rubber reinforcing material and application thereof, and solves the problem of poor wear resistance of rubber products in the related art.

[0007] The technical scheme of the application is as follows: the application provides a mineral composite rubber reinforcing material, which comprises the following components by weight: 10-60 parts of white carbon black, 30-85 parts of black mica, and 5-10 parts of feldspar powder; the feldspar powder is composed of potassium feldspar, calcium feldspar and sodium feldspar at a mass ratio of 1-2:1:1.

[0008] As a further technical scheme, the average particle size of the white carbon black is 1000 mesh, the average particle size of the black mica is 800 mesh, and the average particle size of the feldspar powder is 500 mesh.

[0009] In the application, the different particle sizes of the minerals can form a grading effect in the rubber, the black mica and the feldspar powder with large particle sizes can serve as a support framework, and the white carbon black with small particle sizes can be filled in the gaps, so that the uniformity of the whole system is further improved, the performance defects caused by local aggregation or uneven dispersion are avoided, the consistency of the performance of the rubber products is ensured, and the flowability and plasticity of the rubber compound are adjusted by the cooperation of the components with different particle sizes, so that the stability of the processing process and the dimensional accuracy of the products are ensured.

[0010] As a further technical scheme, the potassium feldspar has an alumina content of 16wt%, a sodium oxide content of 5wt%, a silicon dioxide content of 67wt%, a Mohs hardness of 6, and a potassium oxide content of >8wt%.

[0011] As a further technical scheme, the calcium feldspar has an alumina content of 38wt%, a sodium oxide content of 3wt%, a silicon dioxide content of 56wt%, a Mohs hardness of 4, and a potassium oxide content of <8wt%.

[0012] As a further technical scheme, the sodium feldspar has an alumina content of 13wt%, a sodium oxide content of 6.5wt%, a silicon dioxide content of 65wt%, and a Mohs hardness of 5.

[0013] In the application, 16wt% of alumina in potassium feldspar builds a stable support framework in the rubber matrix, giving the rubber excellent deformation resistance, maintaining shape stability when facing external impact, and 67wt% of silicon dioxide enhances the interaction with rubber molecules due to its high specific surface area and activity; 38wt% of alumina in calcium feldspar further enhances the structural strength of the rubber, and the Mohs hardness of 4 makes it have a certain flexibility, and the high hardness of potassium feldspar is combined with the hardness of calcium feldspar, which uniformly disperses the stress and avoids local damage caused by stress concentration; the Mohs hardness of sodium feldspar is 5, between potassium and calcium feldspar, which plays a transition and coordination role, making the stress distribution in the composite material more uniform, and the three kinds of feldspar cooperate through composition and hardness to significantly improve the wear resistance of rubber products.

[0014] As a further technical solution, the mass ratio of the white carbon black, black mica and feldspar powder to the N-tert-butyl acrylamide compound is 5-8:100.

[0015] In the application, the carbon-carbon double bond contained in the N-tert-butyl acrylamide compound has high reactivity, and during the rubber vulcanization process, the carbon-carbon double bond acts as a "bridge" to connect different rubber molecular chains, gradually building a chemical crosslinking network and improving the mechanical strength of the rubber product; the tert-butyl group has a significant steric hindrance effect, which makes the mineral filler more uniformly dispersed in the rubber matrix, avoids the occurrence of filler agglomeration, fully plays the reinforcing role of the mineral filler, and further significantly improves the mechanical strength of the rubber product.

[0016] As a further technical solution, the N-tert-butyl acrylamide compound includes one or both of N-tert-butyl acrylamide and N-tert-butyl methacrylamide.

[0017] The application also provides a preparation method of a mineral composite rubber reinforcing material, which comprises the following steps: dissolving an N-tert-butyl acrylamide compound in ethyl acetate to obtain a solution with a concentration of 3wt%, adding white carbon black, black mica and feldspar powder, and drying after mixing to obtain the mineral composite rubber reinforcing material.

[0018] In the application, ethyl acetate is used as a dispersion medium, so that the surface of the mineral filler is uniformly wetted, and during the mixing process, the N-tert-butyl acrylamide compound can interact with the active sites on the surface of the mineral filler to enhance the bonding force between them, and after drying, the tight bonding state is preserved, and after the mineral composite rubber reinforcing material is applied to rubber, it can significantly enhance the interfacial bonding force between rubber and reinforcing material, fully play the role of the reinforcing material, and further improve the mechanical strength of the rubber product.

[0019] As a further technical solution, the temperature for dissolving is 20℃.

[0020] As a further technical solution, the mixing time is 2h.

[0021] The application also provides application of the mineral composite rubber reinforcing material in rubber products.

[0022] As a further technical solution, the rubber product comprises the following components by weight: 100 parts of styrene butadiene rubber, 1-2 parts of stearic acid, 5-8 parts of zinc oxide, 40-60 parts of the mineral composite rubber reinforcing material, 1-3 parts of sulfur, 0.5-1.5 parts of accelerator DM, 1-1.5 parts of accelerator NS, and 3-5 parts of polyethylene glycol.

[0023] As a further technical solution, the mass ratio of the styrene butadiene rubber to the mineral composite rubber reinforcing material is 10:4-5, for example, 5:2, 5:2.1, 5:2.2, 5:2.3, 5:2.4, 2:1, and preferably 2:1.

[0024] As a further technical solution, the rubber product comprises the following components by weight: 100 parts of styrene butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 50 parts of the mineral composite rubber reinforcing material, 2 parts of sulfur, 0.5 parts of accelerator DM, 1 part of accelerator NS, and 3 parts of polyethylene glycol.

[0025] As a further technical solution, the rubber product can also be any rubber product using natural rubber or synthetic rubber as a raw material.

[0026] As a further technical solution, the synthetic rubber comprises one or more of styrene butadiene rubber, nitrile butadiene rubber, ethylene propylene rubber, chlorobutyl rubber, and polyurethane rubber.

[0027] As a further technical solution, the ethylene propylene rubber can be a ternary ethylene propylene rubber, for example, 6950, 2470, 8550, S552-1, 512F, 3072, and 3092.

[0028] The application also provides a preparation method of the rubber product, which comprises the following steps: mixing the raw materials, mixing and then vulcanizing and forming to obtain the rubber product.

[0029] As a further technical solution, the mixing time is 20-30 min.

[0030] As a further technical solution, the vulcanization temperature is 150-160 DEG C, and the time is 10-15 min.

[0031] The working principle and advantages of the application are as follows:

[0032] 1. In this invention, silica, as an important reinforcing filler, has a special surface structure and chemical activity that can tightly bind with rubber molecules to form a strong network structure, which greatly enhances the wear resistance of rubber. Feldspar powder, composed of potassium feldspar, calcium feldspar, and sodium feldspar, has a certain hardness and rigidity, which, like a rigid skeleton, can effectively improve the overall hardness and rigidity of rubber products and enhance their wear resistance.

[0033] 2. In this invention, potassium feldspar, calcium feldspar, and sodium feldspar are used simultaneously. Although potassium feldspar, calcium feldspar, and sodium feldspar are all framework-structured aluminosilicate minerals, their crystal structures differ. Potassium ions in potassium feldspar have a larger radius, occupying more space in the crystal structure and forming a relatively loose framework; calcium ions in calcium feldspar have a moderate radius, resulting in a relatively regular structure; sodium ions in sodium feldspar have a smaller radius, leading to a relatively compact crystal structure. When these three feldspars are used in combination, their crystal structures can fill and support each other, forming a denser and more stable composite structure, thereby improving the wear resistance of rubber products.

[0034] 3. The raw materials used in this invention, such as silica, talc, and feldspar powder, are all common mineral materials with wide availability and relatively low prices. Through reasonable formula design, the performance advantages of these mineral materials are fully utilized, achieving rational resource utilization. While ensuring the high performance of rubber products, production costs are effectively reduced, and the market competitiveness of the products is improved, resulting in good economic and social benefits. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] In the following examples and comparative examples:

[0037] Silica: Average particle size is 1000 mesh;

[0038] Black talc: average particle size is 800 mesh;

[0039] Potassium feldspar: average grain size is 500 mesh;

[0040] Anorthite: average grain size is 500 mesh;

[0041] Sodium feldspar: average grain size is 500 mesh;

[0042] Polyethylene glycol: Model number PEG-4000;

[0043] Styrene butadiene rubber: type 1502.

[0044] Example 1

[0045] A mineral composite type rubber reinforcing material, comprising the following components by weight: 10 parts of white carbon black, 85 parts of black mica, 5 parts of feldspar powder; wherein the feldspar powder is composed of potassium feldspar, calcium feldspar and sodium feldspar in a mass ratio of 1:1:1;

[0046] A preparation method of a rubber product, comprising the following steps: mixing 100 parts of styrene butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 50 parts of the mineral composite type rubber reinforcing material, 2 parts of sulfur, 0.5 parts of accelerator DM, 1 part of accelerator NS and 3 parts of polyethylene glycol, mixing for 20 min, and then vulcanizing at 150 DEG C for 15 min to obtain the rubber product.

[0047] Example 2

[0048] A mineral composite type rubber reinforcing material, comprising the following components by weight: 40 parts of white carbon black, 52 parts of black mica, 8 parts of feldspar powder; wherein the feldspar powder is composed of potassium feldspar, calcium feldspar and sodium feldspar in a mass ratio of 1:1:1;

[0049] A preparation method of a rubber product, comprising the following steps: mixing 100 parts of styrene butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 50 parts of the mineral composite type rubber reinforcing material, 2 parts of sulfur, 0.5 parts of accelerator DM, 1 part of accelerator NS and 3 parts of polyethylene glycol, mixing for 25 min, and then vulcanizing at 155 DEG C for 12 min to obtain the rubber product.

[0050] Example 3

[0051] A mineral composite type rubber reinforcing material, comprising the following components by weight: 60 parts of white carbon black, 30 parts of black mica, 10 parts of feldspar powder; wherein the feldspar powder is composed of potassium feldspar, calcium feldspar and sodium feldspar in a mass ratio of 1:1:1;

[0052] A preparation method of a rubber product, comprising the following steps: mixing 100 parts of styrene butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 50 parts of the mineral composite type rubber reinforcing material, 2 parts of sulfur, 0.5 parts of accelerator DM, 1 part of accelerator NS and 3 parts of polyethylene glycol, mixing for 30 min, and then vulcanizing at 160 DEG C for 10 min to obtain the rubber product.

[0053] Example 4

[0054] Compared with example 1, the difference of example 4 is that the feldspar powder is composed of potassium feldspar, calcium feldspar and sodium feldspar in a mass ratio of 2:1:1.

[0055] Example 5

[0056] Example 5 is different from Example 4 in that the black slate (average particle diameter of 800 mesh), the potassium feldspar (average particle diameter of 500 mesh), the calcium feldspar (average particle diameter of 500 mesh), and the sodium feldspar (average particle diameter of 500 mesh) are replaced with the black slate (average particle diameter of 1000 mesh), the potassium feldspar (average particle diameter of 1000 mesh), the calcium feldspar (average particle diameter of 1000 mesh), and the sodium feldspar (average particle diameter of 1000 mesh).

[0057] Example 6

[0058] Example 6 is different from Example 4 in that the white carbon black (average particle diameter of 1000 mesh) is replaced with the white carbon black (average particle diameter of 1200 mesh).

[0059] Example 7

[0060] Example 7 is different from Example 4 in that the black slate (average particle diameter of 800 mesh), the potassium feldspar (average particle diameter of 500 mesh), the calcium feldspar (average particle diameter of 500 mesh), and the sodium feldspar (average particle diameter of 500 mesh) are replaced with the black slate (average particle diameter of 500 mesh), the potassium feldspar (average particle diameter of 300 mesh), the calcium feldspar (average particle diameter of 300 mesh), and the sodium feldspar (average particle diameter of 300 mesh).

[0061] Example 8

[0062] Example 8 is different from Example 4 in that the black slate (average particle diameter of 800 mesh), the potassium feldspar (average particle diameter of 500 mesh), the calcium feldspar (average particle diameter of 500 mesh), and the sodium feldspar (average particle diameter of 500 mesh) are replaced with the black slate (average particle diameter of 800 mesh), the potassium feldspar (average particle diameter of 400 mesh), the calcium feldspar (average particle diameter of 400 mesh), and the sodium feldspar (average particle diameter of 400 mesh).

[0063] Example 9

[0064] Example 9 is different from Example 4 in that the black slate (average particle diameter of 800 mesh), the potassium feldspar (average particle diameter of 500 mesh), the calcium feldspar (average particle diameter of 500 mesh), and the sodium feldspar (average particle diameter of 500 mesh) are replaced with the black slate (average particle diameter of 800 mesh), the potassium feldspar (average particle diameter of 600 mesh), the calcium feldspar (average particle diameter of 600 mesh), and the sodium feldspar (average particle diameter of 600 mesh).

[0065] Example 10

[0066] Example 10 differs from Example 4 in that the potassium feldspar (alumina content of 16wt%, sodium oxide content of 5wt%, silica content of 67wt%, Mohs hardness of 6, potassium oxide content >8wt%) is replaced with an equal amount of potassium feldspar (alumina content of 16.85wt%, sodium oxide content of 3wt%, silica content of 63wt%, Mohs hardness of 6, potassium oxide content >12wt%).

[0067] Example 11

[0068] Example 11 differs from Example 4 in that the potassium feldspar (alumina content of 16wt%, sodium oxide content of 5wt%, silica content of 67wt%, Mohs hardness of 6, potassium oxide content >8wt%) is replaced with an equal amount of potassium feldspar (alumina content of 13wt%, sodium oxide content of 2wt%, silica content of 46wt%, Mohs hardness of 4, potassium oxide content >8wt%).

[0069] Example 12

[0070] Example 12 differs from Example 4 in that the preparation method of the mineral composite rubber reinforcing material is different, and the preparation method of the present example comprises the following steps: dissolving N-tert-butyl acrylamide in ethyl acetate to obtain a solution with a concentration of 3wt%, adding 10 parts of white carbon black, 85 parts of black mica, and 5 parts of feldspar powder; wherein the feldspar powder is composed of potassium feldspar, calcium feldspar, and sodium feldspar in a mass ratio of 1:1:1, and the mass ratio of the white carbon black, black mica, and feldspar powder to the solute N-tert-butyl acrylamide in the solution with a concentration of 3wt% is 1:20; after mixing for 2h, drying is performed to obtain the mineral composite rubber reinforcing material.

[0071] Example 13

[0072] Example 13 differs from Example 12 in that the mass ratio of the white carbon black, black mica, and feldspar powder to the solute N-tert-butyl acrylamide in the solution with a concentration of 3wt% is 2:25.

[0073] Example 14

[0074] Example 14 differs from Example 13 in that the N-tert-butyl acrylamide is replaced with an equal amount of N-tert-butyl methacrylamide.

[0075] Comparative Example 1

[0076] Comparative Example 1 differs from Example 1 in that the mineral composite rubber reinforcing material comprises the following components in parts by weight: 10 parts of white carbon black, 85 parts of black mica.

[0077] Comparative Example 2

[0078] Comparative Example 2 is different from Example 1 in that the mineral composite rubber reinforcing material comprises the following components by weight: 10 parts of white carbon black, 85 parts of black mica, and 5 parts of feldspar powder; wherein the feldspar powder is composed of potassium feldspar and calcium feldspar in a mass ratio of 1:1.

[0079] Comparative Example 3

[0080] Comparative Example 3 is different from Example 1 in that the mineral composite rubber reinforcing material comprises the following components by weight: 10 parts of white carbon black, 85 parts of black mica, and 5 parts of feldspar powder; wherein the feldspar powder is composed of potassium feldspar and sodium feldspar in a mass ratio of 1:1.

[0081] Comparative Example 4

[0082] Comparative Example 4 is different from Example 1 in that the mineral composite rubber reinforcing material comprises the following components by weight: 10 parts of white carbon black, 85 parts of black mica, and 5 parts of feldspar powder; wherein the feldspar powder is composed of calcium feldspar and sodium feldspar in a mass ratio of 1:1.

[0083] Comparative Example 5

[0084] Comparative Example 5 is different from Example 1 in that the mineral composite rubber reinforcing material is only carbon black N220.

[0085] Experimental Example 1

[0086] The mineral composite rubber reinforcing materials prepared in Examples 1-11 and Comparative Examples 1-5 are applied to rubber products, and the DIN abrasion volume of the samples is tested according to the test method specified in DIN ISO 4649.

[0087] The test results are shown in Table 1:

[0088] Table 1 Performance test results of rubber products prepared in Examples 1-11 and Comparative Examples 1-5

[0089]

[0090] As can be seen from Table 1, when the mineral composite rubber reinforcing material comprises feldspar powder, and the feldspar powder is composed of potassium feldspar, calcium feldspar, and sodium feldspar in a mass ratio of 1-2:1:1, the wear resistance of the rubber product can be improved.

[0091] Experimental Example 2

[0092] The mineral composite rubber reinforcing material prepared in Example 4 and Examples 12-14 was applied to rubber products, and the tensile strength of the rubber products was tested according to the test method specified in GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized or Thermoplastic Rubber".

[0093] The test results are shown in Table 2:

[0094] Table 2 Test results of the rubber products prepared in Example 4 and Examples 12-14

[0095]

[0096] As shown in Table 2, when the raw material of the mineral composite rubber reinforcing material further comprises an N-tert-butyl acrylamide compound, the mechanical strength of the rubber product can be further improved.

[0097] Experimental Example 3

[0098] 1. Shore hardness: The mineral composite rubber reinforcing material prepared in Example 13 was applied to rubber products, and the Shore hardness of the rubber products was tested according to the test method specified in GB / T 531.1-2008 "Vulcanized or Thermoplastic Rubber - Test Methods for Indentation Hardness - Part 1: Durometer Hardness (Shore Hardness)", type A, and the sample thickness was 6 mm.

[0099] 2. Elongation at break: The mineral composite rubber reinforcing material prepared in Example 13 was applied to rubber products, and the elongation at break of the rubber products was tested according to the test method specified in GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized or Thermoplastic Rubber", the sample was prepared into a dumbbell-shaped sample, type 2, and the elongation at break of the sample was tested.

[0100] 3. Aging resistance: The mineral composite rubber reinforcing material prepared in Example 13 was applied to rubber products, and the tensile strength and elongation at break of the rubber products after aging were determined according to the test method specified in GB / T 3512-2014 "Vulcanized or Thermoplastic Rubber - Hot Air Accelerated Aging and Heat Resistance Test", after aging at 100℃ for 70 h.

[0101] 4. Tear strength: The mineral composite rubber reinforcing material prepared in Example 13 was applied to rubber products, and the tear strength of the rubber products was determined according to the test method specified in GB / T 529-2008 "Determination of Tear Strength of Vulcanized or Thermoplastic Rubber (Pant, Right Angle and Crescent Shape Samples)", and the test method was method B.

[0102] The test results are shown in Table 3.

[0103] Table 3. Test results of the properties of the rubber products prepared in Example 13

[0104]

[0105] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A mineral composite rubber reinforcing material, characterized in that, The raw materials include the following components in parts by weight: 10-60 parts of precipitated silica, 30-85 parts of black talc, and 5-10 parts of feldspar powder; wherein the feldspar powder is composed of potassium feldspar, calcium feldspar, and sodium feldspar in a mass ratio of 1-2:1:

1. The average particle size of the silica is 1000 mesh, the average particle size of the talc is 800 mesh, and the average particle size of the feldspar powder is 500 mesh. The raw materials also include N-tert-butylacrylamide compound, and the mass ratio of the silica, black talc, and feldspar powder to the N-tert-butylacrylamide compound is 5~8:

100.

2. The mineral composite rubber reinforcing material according to claim 1, characterized in that, The potassium feldspar has an alumina content of 16 wt%, a sodium oxide content of 5 wt%, a silicon dioxide content of 67 wt%, a Mohs hardness of 6, and a potassium oxide content of >8 wt%.

3. The mineral composite rubber reinforcing material according to claim 1, characterized in that, The albite has an alumina content of 13 wt%, a sodium oxide content of 6.5 wt%, a silica content of 65 wt%, and a Mohs hardness of 5.

4. The mineral composite rubber reinforcing material according to claim 1, characterized in that, The N-tert-butylacrylamide compound includes one or both of N-tert-butylacrylamide and N-tert-butylmethylacrylamide.

5. The application of a mineral composite rubber reinforcing material in rubber products, characterized in that, The mineral composite rubber reinforcing material is a mineral composite rubber reinforcing material as described in any one of claims 1 to 4.

6. The application of the mineral composite rubber reinforcing material according to claim 5, characterized in that, The rubber product comprises the following raw materials in parts by weight: 100 parts styrene-butadiene rubber, 1-2 parts stearic acid, 5-8 parts zinc oxide, 20-60 parts mineral composite rubber reinforcing material, 1-3 parts sulfur, 0.5-1.5 parts accelerator DM, 1-1.5 parts accelerator NS, and 3-5 parts polyethylene glycol.

7. The application of the mineral composite rubber reinforcing material according to claim 6, characterized in that, The mass ratio of the styrene-butadiene rubber to the mineral composite rubber reinforcing material is 10:4~5.

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