KR20100082549A - Tire rubber composition for cacas with improved scorch resistance - Google Patents

Abstract

PURPOSE: A tire rubber composition for a tire cacas is provided to improve the scorch resistance without using a separate scorch retarder by applying a thiabicyclo nonane system compound. CONSTITUTION: A tire rubber composition for a tire cacas contains 1.5~2 parts of sulfenamide system compound by weight as a first vulcanization accelerator, and 1.5~2 parts of thiabicyclo nonane system compound by weight as a second vulcanization accelerator, for 100 parts of raw rubber by weight. The sulfenamide system compound is either N-cyclohexylbezothiazole-2-sulfenamide or N-oxyethylbenzothiazole-2-sulfenamide.

Description

TIRE RUBBER COMPOSITION FOR CACAS WITH IMPROVED SCORCH RESISTANCE}

The present invention relates to a rubber composition for tire carcass, and more particularly, to a tire carcass that improves scorch resistance without using a scorch retardant by applying a thiabicyclononane compound together with a sulfenamide compound. It relates to a rubber composition for.

The conventional tire industry continues to strive not only to improve product quality, but also to improve productivity and reduce costs, but the vulcanization process has limited productivity improvement in tire manufacturing.

When vulcanizing various elastomers such as standard Malaysian rubber (SMR), epoxidized natural rubber (ENR), diene rubber and ethylene propylene copolymer rubber with sulfur, the vulcanization accelerator to give elasticity of raw rubber The use of is essential.

The sulfenamide system, which is most used among vulcanization accelerators, has excellent scorch resistance, can increase the vulcanization rate, and shows good properties in terms of rubber properties such as tensile strength and elongation.

In addition, the thiuram-based vulcanization accelerator can increase the vulcanization rate, improve the vulcanization density, and form monosulfide having excellent thermal stability in the crosslinked structure, so it is used alone for the purpose of improving heat aging resistance and breakdown resistance. However, when used in combination with a sulfenamide-based vulcanization accelerator, it may be used together because a synergistic effect of promoting the vulcanization rate can be obtained.

That is, by using the sulfenamide compound as the primary vulcanization accelerator and the thiuram compound as the secondary vulcanization accelerator, the secondary vulcanization accelerator together with the primary vulcanization accelerator promotes the vulcanization reaction to increase the vulcanization rate.

However, when the primary and secondary vulcanization accelerators are used in combination as described above, the vulcanization reaction may be promoted, but on the other hand, the scorch resistance may be reduced, thereby causing the reduction of field rolling processability and compoundability in the extrusion or rolling process.

Therefore, in order to prevent the fall of processability in such a compounding and rolling process, in general, scorch retardants such as N-cyclohexylthioptalimide and phenylenediamine derivatives are added, which increases compound rubber cost. Therefore, the development of a rubber composition that improves the scorch resistance by using the primary and secondary vulcanization accelerators but does not add a scorch retardant does not involve cost increase and does not involve a reduction in formulation and rolling processability. It's urgent.

The present invention uses a sulfenamide-based compound as a primary vulcanization accelerator, and adds a separate scorch retardant while using a thiabicyclononane-based compound as a secondary vulcanization accelerator. Even if it does not, it is providing the rubber composition for tire carcass which improved scorch resistance.

The rubber composition for tire carcass according to the present invention contains 1.5 to 2.0 parts by weight of a sulfenamide compound as a primary vulcanization accelerator and 1.5 to 2.0 parts by weight of a thiabicyclononane compound as a secondary vulcanization accelerator based on 100 parts by weight of the raw material rubber. Characterized in that.

The raw material rubber used in the present invention is not particularly limited in its kind, and it is preferable to use a mixed rubber composed of natural rubber and synthetic rubber alone or in a mixture thereof, and in the case of mixed rubber, the mixing ratio between rubbers is particularly limited. The synthetic rubber is not particularly limited in kind, and for example, styrene butadiene rubber (SBR), modified styrene butadiene rubber, butadiene rubber (BR), modified butadiene rubber, neoprene rubber, chlorosulfonated polyethylene rubber, Epichlorohydrin rubber, fluorine rubber, silicone rubber, nitrile rubber, hydrogenated nitrile rubber, nitrile butadiene rubber (NBR), modified nitrile butadiene rubber, chlorinated polyethylene rubber, styrene ethylene butylene styrene (SEBS) rubber, ethylene propylene Rubber, Ethylene Propylene Diene (EPDM) Rubber, Hypalon Rubber, Chloroprene Rubber, Ethylene Vinyl Acetate Thigh rubber, acrylic rubber, hydrin rubber, vinyl benzyl chloride styrene butadiene rubber, bromomethyl styrene butyl rubber, maleic acid styrene butadiene rubber, carboxylic acid styrene butadiene rubber, epoxy isoprene rubber, maleic acid ethylene propylene rubber, carboxylic acid 1 type (s) or 2 or more types chosen from nitrile butadiene rubber and brominated polyisobutyl isoprene-co-paramethylstyrene can be used in mixture.

The sulfenamide compounds used in the present invention can not only increase the vulcanization rate as a vulcanization accelerator but also improve rubber properties such as scorch resistance, tensile strength and elongation.

There is no restriction | limiting in particular in the kind, The said sulfenamide type compound is 1 type chosen from N-cyclohexyl benzothiazole-2- sulfenamide, N-oxyethyl benzothiazole-2- sulfenamide, etc., for example. Alternatively, two or more kinds thereof may be mixed and used, and the amount thereof is preferably used in an amount of 1.5 to 2.0 parts by weight based on 100 parts by weight of the raw material rubber. It is not preferable due to, and exceeding 2.0 parts by weight may cause scorch instability due to the excessive use of the vulcanization accelerator and lowering the tensile properties of the rubber.

Thiacyclocyclononane-based compound used in the present invention is a type of paraffinic hydrocarbon, sulfur is located at the 3,3,1 position, and the electronic effect is increased due to the adjacent sulfur, which is generally higher than the sulfenamide-based compound. It is more active and also reacts with zinc oxide (ZnO) to produce a zinc-vulcanization accelerator complex, so that the steric hindrance is great, and the zinc-vulcanization accelerator complex finally induces vulcanization reaction of sulfur and rubber. In addition, the vulcanization rate can be increased, and heat aging resistance is also improved. In the present invention, by using the thiabicyclononane compound in combination with a sulfenamide compound, a synergistic effect of further accelerating the vulcanization rate can be obtained, and the effect of further improving scratch resistance and heat aging resistance can be obtained.

The thiabicyclononane-based compound is not particularly limited in its kind, and examples thereof include 1,5-dimercapto-9-thiabicyclo [3,3,1] nonane represented by the following general formula, The amount used is preferably 1.5 to 2.0 parts by weight based on 100 parts by weight of the raw material rubber. If the amount is less than 1.5 parts by weight, it is not preferable because it does not properly perform a role as a vulcanization accelerator to promote the reaction with the rubber and induce a desired reaction. If not more than 2.0 parts by weight, it is not preferable because it does not induce a selective reaction with the rubber and cause a decrease in physical properties.

In the rubber composition of the present invention, in addition to the above-mentioned components, additives commonly used in the rubber composition for tire carcass, such as fillers, zinc oxide, stearic acid, process oil, anti-aging agent and sulfur, etc. It can mix | blend with.

The rubber composition for tire carcass of the present invention can improve scorch resistance without using a separate scorch retarder by applying a sulfenamide compound as a primary vulcanization accelerator and a thiabicyclononane compound as a secondary vulcanization accelerator. Has the effect.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on an Example. However, this invention is not limited by the following Example.

Comparative Example and Example

According to the composition of Table 1, natural rubber and styrene butadiene rubber and carbon black, zinc oxide, process oil, stearic acid and a vulcanization accelerator are blended in a half-barrier mixer and released at 160 ℃, then left at room temperature for 24 hours, the Next, an anti-aging agent, sulfur, and a vulcanization accelerator were added to the half-barrier mixer, and then blended to prepare a rubber composition, followed by vulcanization at 160 ° C. for 25 minutes to prepare a rubber specimen. To see the effect of mixing -9-thiabicyclo [3,3,1] nonane with N-cyclohexylbenzothiazole-2-sulfenamide, the primary vulcanizing agent, scorch time, vulcanization time, The vulcanization rate and the maximum torque were measured, and the results are shown in Table 2 below.

TABLE 1

                                          (Unit: parts by weight)

Item Comparative example Example Natural rubber 80 80 Styrenebutadiene rubber 20 20 Carbon black (N660) 50 50 Zinc oxide 5 5 Stearic acid 2.5 2.5 Process oil 5 5 Primary Vulcanization Accelerator ¹⁾ 2 2 2nd vulcanization accelerator ²⁾ - 1.5 Anti-aging agent ³⁾ 2.5 2.5 brimstone 4 4

Note 1) N-cyclohexylbenzothiazole-2-sulfenamide

2) 1,5-dimercapto-9-thiabicyclo [3,3,1] nonane

3) Polymerized 2,2,4-trimethyl-1,2-dihydroquinoline

TABLE 2

Comparative example Example Scorch time (minutes) 16.5 18.2 Vulcanization time (t90, min) 8.9 8.4 Vulcanization Rate (t9-t10, Min) 5.5 4.5 Torque (dNm) 23.4 21.5

Note) 1) Scorching time: This value shows the scorch stability. The longer the scorch time, the better the scorch stability and the better the scorch resistance.

2) The vulcanization characteristics were carried out at 160 ° C. using a moving die rheometer (MDR) to measure the vulcanization time, vulcanization speed and maximum torque value.

As shown in Table 2, it can be seen that the Example has excellent scorch generation time and vulcanization characteristics, and excellent scorch resistance due to the stability of the scorch time compared to the comparative example.

Claims (3)

Rubber for tire carcass, comprising 1.5 to 2.0 parts by weight of sulfenamide compound as the primary vulcanization accelerator and 1.5 to 2.0 parts by weight of thiabicyclononane compound as the secondary vulcanization accelerator based on 100 parts by weight of the raw material rubber. Composition. The rubber composition for tire carcass according to claim 1, wherein the sulfenamide compound is N-cyclohexylbenzothiazole-2-sulfenamide or N-oxyethylbenzothiazole-2-sulfenamide. The rubber composition for tire carcass according to claim 1, wherein the thiabicyclononane compound is 1,5-dimercapto-9-thiabicyclo [3,3,1] nonane.