KR100815007B1 - Tire tread rubber composition - Google Patents

Abstract

A rubber composition for tire treads is provided to impart improved traction quality and braking performance to a tire while maintaining good wear resistance and other physical properties of rubber. A rubber composition for tire treads comprises: 100 parts by weight of base rubber; and 1-30 parts by weight of crushed vulcanized rubber. The crushed vulcanized rubber comprises, based on 100 parts by weight of the base rubber, 50-100 parts by weight of silica, 4-8 parts by weight of a silane coupling agent, 0.5-5 parts by weight of zinc oxide, 0.5-5 parts by weight of stearic acid, 0.5-5 parts by weight of an antioxidant, 0.5-5 parts by weight of sulfur and 0.5-5 parts by weight of an accelerator. Additionally, the crushed vulcanized rubber has an average size of 0.001-2.0 mm and a vulcanization degree of 30-80%.

Description

Rubber composition for tire treads {TIRE TREAD RUBBER COMPOSITION}

The present invention relates to a rubber composition for tire treads, and more particularly, to a rubber composition for tire treads having improved traction by applying rubber crushed powder.

For conventional rubber materials, traction and wear show a trade-off relationship. Reducing the branch structure in the styrene-butadiene rubber, the main raw material rubber for tire tread rubber, that is, reducing the styrene content, leads to increased wear, but lower traction performance. Conversely, increasing the styrene content increases traction performance but decreases wear performance.

In order to overcome this relationship, the contents of the polymerization of the butadiene in the form of high vinyl content in the styrene butadiene rubber to the high vinyl content has been proposed and used in many tires. In addition, in line with this trend, the traction performance is further maximized by using silica as a filler. However, the inverse relationship between wear and traction characteristics remains a difficult problem to solve.

Korean Patent Laid-Open Publication No. 2007-0014518 provides an example of application to a tread blend using clam shells as a ground product. The clamshell pulverization is described in this patent to maintain the strength of the rubber composition, but not to fall off the tire surface after abrasion, to serve as a spike to improve the ice sheet friction coefficient.

However, clamshells with very high strengths exhibit very different properties from rubbers, resulting in poor adhesion after kneading, which can lead to tire release and also act as a major cause of deterioration of rubber properties. do. In order to overcome this point, if the clam shell pulverized product is applied in a very small size, it is difficult to give a great help to the ice friction coefficient proposed in the patent.

Korean Patent Publication No. 1996-0031528 discloses a method of pulverizing rubber and applying it to a tire tread rubber in powder form. The pulverized rubber composition is composed of polynorbornene and high styrene rubber, carbon black, process oil, and chemicals, and relates to a four season tread rubber composition with improved traction performance and fuel economy. However, in the example according to the present invention, the compatibility between the polynorbornene rubber and the styrene rubber may be present in two rubber forms, and there may be a problem in miscibility even when applied to a tire tread compound as a ground product.

It is an object of the present invention to provide a rubber composition for tire treads having improved traction performance and braking performance of a tire by adjusting the degree of vulcanization and size of rubber pulverized powder to solve the above problems.

The tire tread rubber composition of the present invention is characterized by comprising 1 to 30 parts by weight of rubber vulcanizate with respect to 100 parts by weight of raw rubber.

Rubber crushed powder used in the tire tread rubber composition of the present invention is based on 100 parts by weight of the base rubber, 50 to 100 parts by weight of silica, 4 to 8 parts by weight of the silane coupling agent, 0.5 to 5 parts by weight of zinc oxide, 0.5 stearic acid 0.5 It is characterized by consisting of -5 parts by weight, 0.5-5 parts by weight of a preservative, 0.5-5 parts by weight of sulfur and 0.5-5 parts by weight of accelerator.

In the tire tread rubber composition of the present invention, the content of the rubber pulverized product is preferably 1 to 30 parts by weight, but when it is less than 1 part by weight, the improvement in performance does not appear, and the physical property is more than 30 parts by weight. It is not desirable to fall.

In the rubber vulcanizate used in the present invention, the base rubber may be NSBR (acrylonitrile-styrenebutadiene rubber), VBC-SBR (vinylbenzyl chloride-styrenebutadiene rubber), pyridine-styrenebutadiene rubber, carboxylic Preference is given to using any one selected from acrylonitrile-styrenebutadiene rubber. The content of acrylonitrile, vinylbenzyl chloride, pyridine, and carboxylic acrylonitrile in each of the raw material rubbers is preferably 0.1 to 20% by weight based on the total weight of the base rubber. If it is not caused, it is not preferable, and when it exceeds 20% by weight, gelation phenomenon occurs in the raw material rubber, which is not preferable in terms of elasticity of rubber.

The average size of the crushed rubber vulcanizate is preferably 0.001mm ~ 2.0mm, if less than 0.001mm is not preferable because the characteristics of the crushed product is not preferable, when exceeding 2.0mm when applied to the rubber tread rubber composition It is not preferable because the physical properties fall.

In addition, the degree of vulcanization of the rubber vulcanizate is preferably 30 to 80%, when the degree of vulcanization is less than 30%, it is incorporated into the rubber tread rubber composition, and the characteristics as a pulverized product disappear. If exceeded, the physical properties of the rubber decrease, which is not preferable.

In the rubber composition of the present invention, conventional additives added to a general tire tread rubber composition may be further blended with, for example, carbon black, zinc oxide, stearic acid, preservatives, sulfur, accelerators.

Hereinafter, the present invention will be described in more detail with reference to the following Examples and Comparative Examples. The following examples are merely examples for illustrating the present invention, and do not limit the protection scope of the present invention.

Production Example

To prepare a rubber vulcanizate (average size 0.1mm, vulcanization degree 70%) according to the composition shown in Table 1, and then to measure the dynamic characteristics results are shown in Table 2.

                                                             (Unit: weight part) division Preparation Example 1 Preparation Example 2 Preparation Example 3 ¹⁾ Styrene Butadiene Rubber 100 0 0 ²⁾ NSBR 0 100 0 ³⁾ VBC-SBR 0 0 100 ⁴⁾ tertiary amine 0 0 8 Silica 80 80 80 ⁵⁾ Silane coupling agent 6.4 6.4 6.4 Zinc oxide 3 3 3 Stearic acid 2 2 2 Labor 2 2 2 sulfur 1.8 1.8 1.8 accelerant 1.5 1.5 1.5

1) Styrene Butadiene Rubber (SBR): Styrene content 40.5 wt%

2) NSBR: Acrylonitrile-styrene-butadiene rubber

         Acrylonitrile content 3% by weight, styrene content 40.5% by weight

3) VBC-SBR: vinylbenzylchloride-styrene-butadiene rubber

            VBC content 3% by weight, styrene content 40.5% by weight

4) Tertiary amine: N, N-dimethylstearylamine

            To react with VBC to show the affinity of the OH group of silica

            Used to

5) Silane coupling agent: TESPT (bis- (3-triethoxysilylpropyl) tetrasulfane)

                                                          (Unit: Relative Index) division Preparation Example 1 Preparation Example 2 Preparation Example 3 Hardness 100 100 100 300% -modulus 100 115 113 The tensile strength 100 105 103 Elongation 100 98 101 Tg (℃) -10 -1.3 -2.1 0 ℃ tanδ 100 121 118 70 ℃ tanδ 100 98 99

Tg represents the glass transition temperature, and each test value represents an index.

The higher 0 ° C tanδ is indicative of better traction performance and the lower 70 ° C tanδ is used as an indicator of superior rolling resistance.

Example  And Comparative example

The tread rubber compositions of Examples and Comparative Examples were prepared according to the composition of Table 3 below, and after the production specimens were prepared, the physical properties were evaluated according to ASTM standards, and the results are shown in Table 3 below.

Table 3 and Table 4 below are the contents of the size evaluation of the rubber vulcanized crushed product.

Comparative Example 1

80 parts by weight of carbon black, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of sulfuric acid agent, 1.8 parts by weight of sulfur, and 1.5 parts by weight of accelerator as the raw material rubber, based on 100 parts by weight of styrene butadiene rubber as the raw material rubber. Tire tread rubber compositions were prepared.

Comparative Example 2

A tread rubber composition for a tire was prepared using the same composition as in Comparative Example 1, except that 10 parts by weight of the crushed rubber vulcanizate having a composition of Preparation Example 2 and having an average size of 0.0009 mm was added.

<Example 1>

A tread rubber composition for a tire was prepared using the same composition as in Comparative Example 1, except that 10 parts by weight of the rubber crushed powder having a composition of Preparation Example 2 and having an average size of 0.1 mm were added thereto.

<Example 2>

A tread rubber composition for a tire was prepared using the same composition as in Comparative Example 1, except that 10 parts by weight of the rubber crushed crushed product having the composition of Preparation Example 2 and having an average size of 1.0 mm were added thereto.

Comparative Example 3

A tread rubber composition for a tire was prepared using the same composition as in Comparative Example 1, except that 10 parts by weight of the crushed rubber vulcanizate having the composition of Preparation Example 2 and having an average size of 2.1 mm were added thereto.

                                                        (Unit: weight part) division Comparative Example 1 Comparative Example 2 Example 1 Example 2 Comparative Example 3 ¹⁾ Styrenebutadiene rubber (when oil is contained) 100 (137.5) 100 (137.5) 100 (137.5) 100 (137.5) 100 (137.5) ²⁾ rubber crushed products 0 10 10 10 10 ³⁾ carbon black 80 80 80 80 80 Zinc oxide 3 3 3 3 3 Stearic acid 2 2 2 2 2 ⁴⁾ labor 2 2 2 2 2 sulfur 1.8 1.8 1.8 1.8 1.8 ⁵⁾ accelerator 1.5 1.5 1.5 1.5 1.5

1) Styrenebutadiene rubber: Styrene content 23.5 wt%, Aromatic content 37.5 wt%

2) Rubber vulcanized pulverized product: The rubber vulcanized pulverized product of Preparation Example 2 to which NSBR 100 parts by weight is applied as a raw material rubber, the degree of vulcanization is 70%, the size of each embodiment is the same as mentioned above.

3) Carbon Black: Iodine 45mg / g, DBP Adsorption 126ml / 100g

4) Kneading agent (Kumanox-13): N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine

5) Accelerator (NS): N-tertiary-butyl-2-benzothiazolesulfenamide

                                                          (Unit: Relative Index) division Comparative Example 1 Comparative Example 2 Example 1 Example 2 Comparative Example 3 Hardness 100 102 101 99 99 300% modulus 100 105 104 103 101 The tensile strength 100 102 101 98 72 Elongation 100 98 102 92 63 * Skid resistance 100 94 104 112 102

* Skid resistance: This resistance is applied to the simulated road surface condition of the floor when the test rubber specimen is moved in the weight direction and used as an indirect evaluation index of tire traction. The higher the index, the better.

As can be seen from the above results, when the size of the rubber vulcanizate is less than 0.001 mm, there is no improvement in the skid resistance, and when the size exceeds 2.0 mm, the tensile strength and the elongation rate are decreased.

Table 5 and Table 6 show the evaluation according to the degree of vulcanization of the rubber vulcanizate pulverization.

<Comparative Example 4>

To the rubber composition of the same composition as in Comparative Example 1, 10 parts by weight of a vulcanized powder having a composition of Preparation Example 2 of 28% rubber vulcanizate was added.

<Example 3>

To the rubber composition of the same composition as in Comparative Example 1, 10 parts by weight of a vulcanized crushed product having a composition of Preparation Example 2 of 50%.

<Example 4>

To the rubber composition of the same composition as in Comparative Example 1, 10 parts by weight of a vulcanized pulverized product having a composition of Preparation Example 2 of 70%.

Comparative Example 5

To the rubber composition of the same composition as in Comparative Example 1, 10 parts by weight of a vulcanized crushed product having a composition of Preparation Example 2 of 90%.

                                                         (Unit: weight part) division Comparative Example 1 Comparative Example 4 Example 3 Example 4 Comparative Example 5 Styrenebutadiene rubber (when oil is contained) 100 (137.5) 100 (137.5) 100 (137.5) 100 (137.5) 100 (137.5) ¹⁾ Rubber crushed powder 0 10 10 10 10 Carbon black 80 80 80 80 80 Zinc oxide 3 3 3 3 3 Stearic acid 2 2 2 2 2 Labor 2 2 2 2 2 sulfur 1.8 1.8 1.8 1.8 1.8 accelerant 1.5 1.5 1.5 1.5 1.5

1) Rubber crushed products: 100 parts by weight of NSBR is applied as raw rubber.

          1.0 mm, and the vulcanization degree for each embodiment is as mentioned above.

                                                            (Unit: Relative Index) division Comparative Example 1 Comparative Example 4 Example 3 Example 4 Comparative Example 5 Hardness 100 101 102 99 102 300% modulus 100 102 99 103 105 The tensile strength 100 105 102 98 64 Elongation 100 103 101 92 54 * Skid resistance 100 100 105 112 102

As can be seen from the above results, when the vulcanization degree of the rubber vulcanizate is less than 30%, there is no improvement in the skid resistance, and when the vulcanization degree is 90%, the tensile strength and the elongation rate are decreased.

Tables 7 and 8 show the evaluation of rubber composition by base rubber composition.

<Example 5>

To the rubber composition of the same composition as Comparative Example 1 was added 10 parts by weight of the rubber vulcanized pulverized product of Preparation Example 3 to which 100 parts by weight of VBC-SBR was applied as the base rubber.

Comparative Example 6

To the rubber composition of the same composition as Comparative Example 1 was added 10 parts by weight of the rubber vulcanized pulverized product of Preparation Example 1 to which 100 parts by weight of SBR was applied.

                                                              (Unit: weight part) division Comparative Example 1 Example 4 Example 5 Comparative Example 6 Styrenebutadiene rubber (when oil is contained) 100 (137.5) 100 (137.5) 100 (137.5) 100 (137.5) ¹⁾ Rubber crushed powder 0 10 10 10 Carbon black 80 80 80 80 Zinc oxide 3 3 3 3 Stearic acid 2 2 2 2 Labor 2 2 2 2 sulfur 1.8 1.8 1.8 1.8 accelerant 1.5 1.5 1.5 1.5

1) Rubber pulverized product: The size is 1.0mm, the degree of vulcanization is 70%, the raw material rubber

          As mentioned above.

                                                              (Unit: Relative Index) division Comparative Example 1 Example 4 Example 5 Comparative Example 6 Hardness 100 99 101 100 300% modulus 100 103 102 102 The tensile strength 100 98 94 90 Elongation 100 92 93 86 * Skid resistance 100 112 110 98

As can be seen from the above results, when NSBR and VBC-SBR are applied as base rubbers of rubber crushed powder, the skid resistnce is improved. However, in the case of Comparative Example 6 in which styrene butadiene rubber is applied, Does not represent.

As can be seen from the above, the tire tread rubber composition of the present invention can improve the traction performance and the braking performance of the tire by adding rubber vulcanized powder having a specific size and vulcanization degree of a specific composition.

Claims (3)

It comprises 1 to 30 parts by weight of rubber vulcanized pulverized product with respect to 100 parts by weight of raw material rubber, wherein the rubber vulcanized pulverized product is composed of 50 to 100 parts by weight of silica and 4 to 8 of silane coupling agent based on 100 parts by weight of base rubber. It is composed of parts by weight, 0.5-5 parts by weight of zinc oxide, 0.5-5 parts by weight of stearic acid, 0.5-5 parts by weight of furnace agent, 0.5-5 parts by weight of sulfur and 0.5-5 parts by weight of accelerator, and the average size is 0.001-2.0 mm, the vulcanization degree is 30 to 80%, the rubber composition for tire treads. The rubber base pulverized product according to claim 1, wherein the base rubber is acrylonitrile-styrenebutadiene rubber, vinylbenzyl chloride-styrenebutadiene rubber, pyridine-styrenebutadiene rubber, carboxylic acrylonitrile-styrenebutadiene rubber Rubber composition for tire treads, characterized in that one selected from. 3. The tire tread rubber according to claim 2, wherein the content of acrylonitrile, vinylbenzyl chloride, pyridine or carboxylic acrylonitrile in the base rubber is 0.1 to 20% by weight in the total weight of the base rubber. Composition.