KR20010106741A - Rubber composition for skimming steel cord - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for coating a steel cord of a tire, wherein the natural rubber or isoprene rubber is used as the main component rubber, and the polyoctenamer is contained in the conventional rubber composition containing carbon black, cobalt salt and additives. It contains 1 to 15 parts by weight with respect to the part, which serves to lower the viscosity during processing, and greatly increases the modulus of the rubber after vulcanization, thereby suppressing cracking and growth of the rubber part of the belt part by reducing the amount of deformation during tire driving. can do.

Description

Rubber composition for coating steel cord of tires {Rubber composition for skimming steel cord}

The present invention relates to a rubber composition for coating a steel cord of a tire, and more particularly, by adding polyoctenamer to a conventional rubber composition to lower the viscosity during processing while greatly increasing the modulus of rubber after vulcanization. The present invention relates to a rubber composition capable of suppressing cracking and growth of belt rubber due to a reduction in deformation amount during tire travel.

While driving the vehicle, the belt part of the radial tire is subjected to strong stress and severe deformation. If such deformation and stress change continue for a long time, fatigue accumulates, causing cracks between the brass cord coated steel cord and rubber. do. If the deformation and stress concentration continue as the crack occurs, the crack grows gradually and eventually leads to breakage, which causes serious problems in the stability of the tire. Such cracking and crack growth of rubber are known to be closely related to the deformation amount of the tire belt portion and the fatigue resistance of the rubber.

In other words, if the modulus of the rubber is increased, the amount of deformation of the belt portion is relatively reduced while driving the tire, thereby greatly reducing the occurrence and growth of cracks.

As a method for increasing the modulus of rubber, a method of adding a large amount of sulfur, increasing the amount of carbon black added, and a method of increasing the modulus of rubber using a resin are used.

However, excessive use of sulfur greatly reduces rubber fatigue, breaking energy, and heat aging resistance, and has a problem of deterioration of adhesion due to precipitation of sulfur during processing.

In addition, the use of a large amount of carbon black increases the heat generation of the rubber while running the tire to reduce the durability of the tire, generates a high heat even during processing has the disadvantage of lowering the physical properties and adhesion of the rubber. In addition, the use of the resin also causes a high viscosity rise during processing, making it difficult to process.

Accordingly, the present inventors, while trying to solve the problem in the method of increasing the modulus of the conventional rubber, adding a polyoctenamer to the rubber composition containing a natural rubber and isoprene rubber as a main component and containing a cobalt salt As a result, the present invention has been found to be able to reduce the occurrence of cracks and growth of the rubber part of the belt by reducing the amount of deformation during tire driving by greatly increasing the modulus of the rubber after vulcanization during the processing. .

Accordingly, an object of the present invention is to provide a rubber composition for coating a steel cord having high modulus and excellent fatigue resistance.

The rubber composition for tire steel cord coating of the present invention for achieving the above object is a rubber composition for tire steel cord coating comprising natural rubber or isoprene rubber as a main component rubber, and containing carbon black, cobalt salt and additives therein, It is characterized in that the polyoctenamer is added to the composition in an amount of 1 to 15 parts by weight based on 100 parts by weight of the main component rubber.

The present invention will be described in more detail as follows.

The rubber composition for tire steel cord coating of the present invention is composed of natural rubber or synthetic isoprene rubber as a main component rubber, and various kinds of zinc oxide, carbon black or silica-based fillers, and sulfur, as well as conventional rubber composition for tire steel cord coating. It is the thing which added the polyoctenamer as what mix | blended the additive, It is characterized by the above-mentioned.

Polyoctenamer refers to a polymer in which a cyclooctene is ring-opened, and the ratio of polyoctenamer is 10 or more. The poly octenamer crystallizes upon expansion, exhibiting high tensile strength and tear strength, and having a large amount of unsaturated groups, not only vulcanization by sulfur, but also high crosslinking efficiency, greatly increases modulus after vulcanization.

Particularly, the polyoctenamer has a melting point of about 50 ° C., which is in a liquid state during processing, and serves to lower the viscosity of the rubber by serving as a processing aid.

As a result, the polyoctenamer plays a role of lowering the viscosity during processing, and greatly increases the modulus of the rubber after vulcanization, thereby suppressing cracking and growth of the rubber part of the belt due to a reduction in the amount of deformation during tire travel.

Polyoctenamers that serve this role may be commercially available or may be prepared using the methods disclosed in US Pat. No. 3,943,116.

This patent discloses polyoctenamers having a high cis content by polymerizing cyclooctene and / or 1,5-cyclooctadiene using a catalyst system composed of an organosilicon compound, a tungsten halide salt, and an organoaluminum compound. Prepared.

On the other hand, the rubber composition for coating a tire steel cord of the present invention is a conventional one made of natural rubber or synthetic isoprene rubber as a main component, and cobalt salt is added thereto.

In general, cobalt salts have an excellent effect on preventing corrosion, and are a compound generally added to the rubber composition for coating the steel cord of a tire by preventing corrosion of the steel cord.

Cobalt salts include conventional cobalt salts such as cobalt naphthenate, and certain cobalt boron complexes. In the case of cobalt boron complexes, the bond between B and O is weak, so that the borate portion and the cobalt salt may easily fall off. In addition to acting as an adhesion enhancer, which is a common cobalt salt, the borate portion acts as a buffer to adjust the pH (pH) at the rubber and steel cord interface, maintaining a pH of about 7 to 9 It is more preferable to prevent corrosion.

Thus, cobalt salt is normally added at 1-3 weight part with respect to 100 weight part of main component rubber | gum.

In addition, it is a matter of course that the rubber composition of the present invention can use an additive used in a rubber composition for coating a conventional tire steel cord.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Examples 1-3 and Comparative Example 1

As shown in Table 1 below, each component was combined to prepare a rubber composition.

Example Comparative Example 1 One 2 3 Natural rubber 100 100 100 100 Carbon black 58 58 58 58 Zinc oxide 10 10 10 10 Polyoctenamer 3 6 9 - Stearic acid One One One One Anti-aging 3 3 3 3 Cobalt naphthenate 2 3 3 3 brimstone 8.5 8.5 8.5 8.5 accelerant 1.1 1.1 1.1 1.1 Carbon Black Co., Ltd .: Carbon black antiaging agent having a nitrogen adsorption surface area of 70 to 100 m 2 / g and a DBP oil absorption of 60 to 100 ml / 100 g: N-phenyl-N '-(1,3-dimethylbutyl) -p- phenylenediamine, Accelerator: N, N-dicyclohexyl-2-benzothiazole sulfenamide Polyoctenamer: manufactured by Schill & Seilacher

Experimental Example

The rubber compositions obtained according to Examples 1 to 3 and Comparative Example 1 were vulcanized at 150 ° C. for 30 minutes to prepare specimens for evaluation.

On the other hand, the pattern viscosity, 100 modulus, tensile strength, fatigue resistance, adhesive strength between rubber and steel cord were evaluated, and the results are shown in Table 2 below.

Here, the evaluation of the adhesion between the rubber and the steel cord is the result of performing according to ASTM D 2229-80 method.

Example Comparative Example 1 One 2 3 Pattern viscosity (125 ℃) 61 57 55 64 100 modulus (kg / ㎠) 60 65 67 56 Tensile Strength (kg / ㎠) 243 240 231 242 Cycle 19,407 18,257 17,326 18,925 Rubber / Steel Cord Adhesion (kgf / in) 116 118 123 120

From the results in Table 2, it can be seen that the rubber composition according to the present invention has a low viscosity during processing, the modulus after vulcanization is high, and the fatigue resistance is excellent despite the high modulus.

As a result, it can be seen that crack generation and growth of the belt portion rubber due to the reduction in the amount of deformation during tire travel can be suppressed.

As described in detail above, in the case of adding polyoctenamer to the rubber composition for coating a steel cord according to the present invention, while reducing the viscosity during processing, the rubber modulus is greatly increased after vulcanization during tire driving. It is possible to suppress cracking and growth of the belt rubber due to the decrease in the amount of deformation.

Claims (2)

In the rubber composition for tire steel cord coating comprising natural rubber or isoprene rubber as a main component rubber, and containing carbon black, cobalt salt and additives, The composition is a rubber composition for coating a tire steel cord, characterized in that it comprises 1 to 15 parts by weight of polyoctenamer relative to 100 parts by weight of the main component rubber. The rubber composition for coating a tire steel cord according to claim 1, wherein the polyoctenamer is a polymer obtained by ring-opening cyclooctene, and the ratio of polyoctenamer is 10 or more.