KR20010096799A - Rubber Composition for Tire Improved Reversion Character - Google Patents

Abstract

The present invention relates to a rubber composition for tires with improved reversion phenomenon.

In the known rubber composition for tires, the present invention relates to bis- (N, N'-di-2-ethylhexyl-thiophosphoryl) polysulfide (bis- (N) as a vulcanization accelerator with respect to 100 parts by weight of natural rubber as a raw material rubber. , N'-di-2-ethylhexylthiophosphoryl) polysulfide) is added to improve the reversion properties of natural rubber.

Description

Rubber Composition for Tire Improved Reversion Character

The present invention relates to a rubber composition for tires having improved reversion phenomena, and more particularly, to bis- (N, N'-di-2-ethylhexyl) in a known rubber composition for which tires are used as natural rubber. A thiophosphoryl) polysulfide (bis- (N, N'-di-2-ethylhexylthiophosphoryl) polysulfide) is used as a vulcanization accelerator, and relates to a rubber composition for tires that improves the reversion properties of natural rubber.

Reversion means that the rubber composition, which mainly uses natural rubber as a raw material rubber, is decomposed to a polysulfide-type bond when it is overheated to a high temperature, so that it is crosslinked by a monosulfide or disulfide-type bond. This means that the physical properties of the rubber decreases due to the change in form. In the case of natural rubber, there is a lot of methyl groups (-CH ₃ ) around the double bond, which causes such physical property deterioration.

Sulfur vulcanized products of rubber composition, which mainly use natural rubber as raw material rubber, have lower physical properties than proper vulcanization when high-temperature over-curing, and when aging is progressed when using products manufactured using such rubber There is a problem that falls rapidly.

The present invention adds bis- (N, N'-di-2-ethylhexyl-thiophosphoryl) polysulfide as a vulcanization accelerator to a rubber composition mainly using natural rubber as a raw material rubber to solve the above-mentioned problems. The purpose is to improve the reversion properties of natural rubber.

In the known rubber composition for tires, the present invention relates to bis- (N, N'-di-2-ethylhexyl-thiophosphoryl) polysulfide (bis- (N) as a vulcanization accelerator with respect to 100 parts by weight of natural rubber as a raw material rubber. , N'-di-2-ethylhexylthiophosphoryl) polysulfide) is added to improve the reversion properties of natural rubber. When the vulcanization accelerator used in the present invention is used in an amount of 0.5 parts by weight or less, the reversion improvement effect is inadequate due to a small amount, and when 5.0 parts by weight or more is used, the improvement effect is not increased any more. As a result, more than the amount that can participate in the crosslinking reaction is added, so that the reaction cannot appear.

Meanwhile, the structure of bis- (N, N'-di-2-ethylhexyl-thiophosphoryl) polysulfide used as a vulcanization accelerator in the present invention is as follows.

In said formula, x represents 3-8.

Hereinafter, the present invention will be described by the following comparative examples and examples. However, these comparative examples and examples do not limit the technical scope of the present invention.

Comparative Example

Rubber composition using 100 parts by weight of natural rubber, 5 parts by weight of zinc oxide (ZnO # S), 35 parts by weight of carbon black, 2 parts by weight of stearic acid, 2.5 parts by weight of vulcanizing agent, and 0.7 parts by weight of commonly used vulcanization accelerator. After the rubber specimen was prepared by vulcanization at a temperature of 160 ° C. for 12-15 minutes in a Banburi mixer, the rubber specimen was prepared with Mooney, rheometer and tensile properties (hardness, 300 modulus, tensile strength). , Elongation) and the like are shown in Table 1 below.

<Example 1-4>

A rubber specimen was prepared in the same manner except that 1.0 to 4.0 parts by weight of the vulcanization accelerator in the rubber composition of the comparative example was used as bis- (N, N'-di-2-ethylhexyl-thiophosphoryl) polysulfide. Prepared and measured the Mooney (Mooney), rheometer (Rheo), tensile properties (hardness, 300 modulus, tensile strength, elongation) and the results are shown in Table 1 below.

Table 1. Rubber compositions and physical property measurement results of Comparative Examples and Examples

Comparative example Example 1 Example 2 Example 3 Example 4 Natural rubber 100 100 100 100 100 Zinc oxide 5 5 5 5 5 Carbon black 35 35 35 35 35 Stearic acid 2 2 2 2 2 Vulcanizing agent 2.5 2.5 2.5 2.5 2.5 Vulcanization accelerator (Ⅰ) * 0.7 - - - - Curing accelerator (Ⅱ) ** - 1.0 2.0 3.0 4.0 Mooney @ 100 ℃ Viscosity 83 82 80 80 81 Mooney @ 125 ℃ T ₅ 12.3 11.7 11.5 10.9 9.9 RheO @ 160 ℃ T ₄₀ 3.7 2.8 2.9 2.8 2.6 T ₉₀ 6.7 5.9 5.8 5.3 5.0 T _max 44.1 42.9 43.9 45.4 45.2 RheO @ 160 ℃ Torque 4.10 3.28 3.37 3.42 3.60 Torque 27.97 29.88 30.04 31.28 32.49 Final torque 19.50 24.02 25.00 24.68 26.57 Revision () 35.5 22.0 18.9 23.7 20.5 Tensile Properties burglar 70 71 71 70 70 300 modulus 167 185 192 190 198 The tensile strength 268 249 259 252 248 Elongation () 467 413 438 422 416

* Vulcanization accelerator (I) represents N-t-butylbenzothiazole-Z-selfenamide (NS).

** Vulcanization accelerator (II) stands for bis- (N, N′-di-2-ethylhexyl-thiophosphoryl) polysulfide.

As can be seen in Table 1, Comparative Examples using a vulcanization accelerator different from Example 1-4 using bis- (N, N'-di-2-ethylhexyl-thiophosphoryl) polysulfide as a vulcanization accelerator in the present invention Looking at the vulcanization characteristics, the vulcanization time tends to be slightly shortened, but it can be seen that the variability is not a problem for fairness. In the case of various physical properties, the rubber specimens of Comparative Examples and Examples were almost similar, but the reversion property of Example 1-4 specimens of the present invention can be seen to be improved than that of Comparative Examples.

Claims (2)

In known rubber compositions for tires, a reversion phenomenon using bis- (N, N'-di-2-ethylhexyl-thiophosphoryl) polysulfide, in which the vulcanization accelerator can be represented by the following structure: This improved rubber composition for tires In said formula, x represents 3-8. The bis- (N, N'-di-2-ethylhexyl-thiophosphoryl) polysulfide used as a vulcanization accelerator is used in an amount of 0.5 to 5.0 parts by weight based on 100 parts by weight of natural rubber as a raw material rubber. Rubber composition for tires with improved reversion