Textiles: spinning – twisting – and twining – Strand structure – Multifilament yarns
Patent
1987-02-11
1988-12-27
Watkins, Donald
Textiles: spinning, twisting, and twining
Strand structure
Multifilament yarns
57902, 152451, D02G 302, D02G 348
Patent
active
047931310
DESCRIPTION:
BRIEF SUMMARY
1. [Technical Field]
The present invention relates to a tire cord made of polyvinyl alcohol which is excellent in tensile strength, initial modulus and fatigue resistance and can give a pneumatic tire exhibiting excellent controllability, durability and quality reproducibility and low fuel consumption in high-speed running.
2. [Background Art]
There are three kinds of pneumatic tires depending upon the arrangement of cord or the direction thereof, i.e., bias, radial and belted bias tires, among which radial and belted bias tires are thought to be excellent in controllability in high-speed running owing to the retainer effect on the belt part.
As motorization has proceeded, the reinforcing material for the belt part of the above radial and belted bias tires has been required not only to have high strength, modulus, dimensional stability, impact resistance, adhesion, compressive modulus and stiffness and low growth, but also to be of low specific gravity and low cost.
Recently, as the construction of superhighway has proceeded, belted bias or radial tires which are excellent in controllability in high-speed running have spread. Among them, a radial tire having a belt made of steel fiber is particularly noted. However, such a radial tire is designed with too much regard to controllability. Therefore, the unevenness of a road tends to directly affect the car body to result in uncomfortable ride and residence. Further, the radial tire produces hideous noise in running. That is to say, the grounding part of a tire having a belt made of steel fiber is so rigid that the unevenness of a road directly affects the car body. Therefore, when the car runs on an uneven road, the car vibrates vigorously to result in uncomfortable ride and residence. Further, a steel fiber cord has essential disadvantages in that it tends to rust unlike an organic fiber cord, thus resulting in unsufficient durability and that the fiber has a high specific gravity to therefore give a heavy tire, thus increasing fuel consumption.
Under the above circumstances, a tire cord having a belt made of a combination of steel fiber and aramid fiber (for example, a product of Du Pont; "Kevlar") has been proposed as a tire cord which absorbs vibration due to the unevenness of a road as completely as possible to thereby improve comfortableness in riding. However, this tire cord has not widely been used as yet, and finds only limited uses, because the cost of the aramid fiber is high and the design and production of a tire containing such a tire cord are difficult.
A polyvinyl alcohol yarn has long been used as a tire cord. However, the polyvinyl alcohol fiber was too poor in fatigue resistance substantially to be used as a reinforcing material for the carcass of a radial tire. To improve the fatigue resistance of a polyvinyl alcohol yarn, a process for producing a polyvinyl alcohol yarn cord wherein the conditions of upper and lower twisting of the polyvinyl alcohol cord are specified has been proposed in Japanese patent publication No. 46-33601. However, the essential defect in fatigue resistance of a polyvinyl alcohol yarn could not be remarkably improved by this process aiming at improving the belt part from the viewpoint of the design thereof. Further, a cord obtained by intertwining three polyvinyl alcohol raw yarns of 1200 denier (d) according to the prior art exhibited a breaking strength of at most about 30 kg an a tensile strength of at most about 7.5 g/d. Thus, it was remarkably inferior in mechanical strength to the above aramid yarn cord.
Under these circumstances, Japanese patent application Kokai publication No. 59-130314 discloses a spinning process which comprises introducing a solution of a high-molecular weight polyvinyl alcohol having a molecular weight of at least 500,000 maintained at a high temperature via a spinneret into a cooling bath to form a rubbery fibrous gel from the introduced solution and removing the solvent from the rubbery fibrous gel by extraction to obtain a polyvinyl alcohol yarn having a tensile strength of at leas
REFERENCES:
patent: 3597303 (1971-08-01), Tanaka
patent: 3826298 (1974-07-01), Tanaka et al.
patent: 4603083 (1986-07-01), Tanaka et al.
patent: 4698194 (1987-10-01), Tanaka et al.
Katoh Mituo
Mizuno Masaharu
Toray Industries Inc.
Watkins Donald
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