Cord, method of producing same, and rubber-cord composite body

Abstract

A cord obtained by twisting a plurality of strands each composed of a plurality of filaments is provided. A circumferential surface of the filament is coated with unvulcanized rubber to improve rubber intrusion, thereby improving corrosion resistance and suppressing twisting-loss.

Description

TECHNICAL FIELD[0001]The present invention relates to a cord used for reinforcing a rubber product such as a tire and an industrial belt, method of producing same, and a rubber-cord composite body.RELATED ART[0002]A high strength is demanded for a cord used for reinforcing a tire, especially a tire for a construction vehicle, so that a cord made of a plurality of strands produced by twisting a plurality of filaments, which strands are further twisted to form a so-called multiple-twisting structure, is used for this purpose.[0003]In the production of the cord having a multiple-twisting structure, however, a strand is made from a plurality of filaments and then a plurality of strands are twisted to give the cord. Thus, it has more filaments and a more complicated twisting structure than a cord having a single twisting structure used for reinforcing, for example, a passenger vehicle. As a result, a tensile strength of the cord becomes smaller than the sum of tensile strengths of the co...

AI Technical Summary

Benefits of technology

[0007]Although the above-mentioned technique can suppress the twisting loss, it is demanded particularly for a cord used for reinforcing a tire to ensure corrosion resistance as a reinforcing material. That is, when the tire suffers an external injury, water intrudes from the external injury into the tire to reach the cords, which may corrode the cords. If any spaces exist inside the cords, the water disperses through the spaces in the axial direction of the cord and the corrosion area expands along the cord. This may cause a malfunction due to a separation with the corrosion area being as the origination of the separation. A characteristic capable of suppressing the intrusion of water into the inside of the cord, i.e. corrosion resistance, is, therefore, demanded particularly for a cord for reinforcing a tire in order to avoid such dispersion of the corrosion.

[0009]In order to improve the ability of the rubber to intrude into the strands constituting the cord, a commonly used means is that sufficient spaces extending from the outside of the strands to the inside of the strands are provided to allow the rubber to sufficiently intrude into the inside of the strand during a vulcanization step of a tire manufacturing process.

[0011]The object of the present invention is, therefore, to provide a cord structure capable of suppressing twisting loss and improving corrosion resistance particularly of a cord having a complicated multiple-twisting structure by allowing rubber to sufficiently intrude into the inside of strands constituting the cord.

[0012]The present inventor had dedicated to study a means for improving corrosion resistance of a cord having a complicated multiple-twisting structure and found it effective for allowing the rubber to sufficiently intrude into the inside of the strands during the vulcanization step of the tire manufacturing process to coat the filaments used for the production of the strands with unvulcanized rubber prior to twisting a plurality of the strands to form a cord. The present invention is completed in this way.

[0022]According to the present invention, the filaments constituting the strand are preliminarily coated with unvulcanized rubber, so that the unvulcanized rubber is allowed to flow and thus be distributed into the space between the filaments in the strand. The rubber, therefore, can sufficiently intrude into the inside of the strand, which enables to provide a cord having improved corrosion resistance and suppressed twisting reduction.

Problems solved by technology

That is, when the tire suffers an external injury, water intrudes from the external injury into the tire to reach the cords, which may corrode the cords.

This may cause a malfunction due to a separation with the corrosion area being as the origination of the separation.

The structure of the cord, thus, becomes complicated and it is difficult to provide spaces for allowing the rubber to sufficiently intrude into the inside of the strands.

As a result, the rubber cannot sufficiently intrude into the inside of the strands during the vulcanization step of the tire manufacturing process, so that improvement of the corrosion resistance is difficult.

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