GB2213490A

GB2213490A - A pneumatic vehicle tyre

Info

Publication number: GB2213490A
Application number: GB8828508A
Authority: GB
Inventors: Richard Michael Russell
Original assignee: Uniroyal GmbH
Current assignee: Uniroyal GmbH
Priority date: 1987-12-09
Filing date: 1988-12-07
Publication date: 1989-08-16
Anticipated expiration: 2008-12-07
Also published as: FR2629093A1; GB2213490B; IT1227655B; GB8828508D0; FR2629093B1; IT8822805A0

Abstract

The impermeability to gas of the carcase rubber mass of a pneumatic tyre is improved by the use of an epoxidised isoprene containing at least 20 mol% of oxiran.

Description

A PNEUMATIC VEHICLE TYRE The present invention relates to a pneumatic vehicle tyre having single-ply or multiple-ply carcase more especially a radial carcase in which the reinforcing support members are covered with a wettable or vulcanisable rubber mixture composition which comprises at least one elastomer which is highly impermeable to gas and has no inner layer.

In pneumatic vehicle tyres of this type, the carcase is significantly improved against the loss of air by the use of a mixture for the carcase which consists of styrene-butadiene copolymers with at least 20 parts per 100 parts of rubber of a type having a high styrene content or emulsion polymerised styrene-butadiene copolymers in which the bound styrene content is at least 30 parts per 100 parts of rubber and 40 parts per 100 of the rubber consist of elastomers or chopped elastomers having a good compounding adhesion. Such tyres from the subject matter of our UK Published Application No.

2198138.

The object of the present invention is to ensure relatively reduced loss of air through the carcase of the tyre which is at least as good as that provided by the means according to our above-numbered published application. This however is advantageously achieved by means of another elastomer component instead of the styrene-butadiene copolymers having a high styrene content used.

In accordance with the invention, the object is achieved by the use of an elastomer comprising an epoxidised polyisoprene with at least 20 mol % of oxiran instead of the styrene-butadiene copolymers. The polyisoprene may be a synthetic or a natural rubber.

The carcase, which consists of e.g. rayon, polyester, polyamide or polyaramide fabric or of steel fabric is covered on all sides by the epoxidised polyisoprene. By such means, the impermeability to gas is improved in comparison with standard carcase mixtures which have a butyl rubber inner layer or a similar inner layer and also in comparison with the carcase rubber mixture according to the above-numbered published application.

The rubber mixture for the carcase preferably comprises in accordance with an aspect of the invention 40 parts of natural rubber per 100 parts of rubber as the elastomer with satisfactory compounding adhesion and at least 20 parts per 100 parts of the rubber of an epoxidised polyisoprenwe which contains at least 20 mol % of oxiran. The improvement in the carcase intermediate pressure is indicated by the gas impermeability m2.10'17 S .Pa for a carcase mixture according to the invention in comparison with a standard mixture of chlorobutyl rubber which contains 40 parts per 100 parts of natural rubber and 60 parts per 100 parts of chlorobutyl rubber.

Example A standard rubber mix Carcase mixture for a butyl rubber inner layer Natural rubber 40 pphr 40 pphr Chlorobutyl rubber 60 pphr Natural rubber containing ENR 50 = 50 mol% oxiran - 60 pphr GPF N 660 carbon black 41 pphr 41 pphr Aromatic oil 6 pphr 6 ppht stearic acid 1.5 pphr 1.5 pphr Zinc oxide - 5.0 pphr n3TB accelerator 0.8 pphr DPG accelerator 0.1 pphr MBS accelerator - 1.5 pphr Sulphur 1.0 pphr 1.5 pphr Gas impermeability values for these two mixtures are A 30*C 1.9 1.7 m,10-17 500C 5.2 5.7 s.Fa 70 C 9.6 10.6 The figures for gas impermeability indicate that in the case of mixture A similar values are obtained for the butyl inner layer as for the new carcase rubber layer B, which are thus directly comparable. In the case of the carcase mixture which has expoxidised polyisoprene with at least 20 mol% of oxiran the previously normal inner layer can be dispensed with completely.

The carcase rubber mixture according to the invention takes over the gas impermeability function to such an extent that the carcase is now constructed without an inner layer and provides satisfactory values for gas impermeability. In comparison with the rubber mixture according to our above-numbered published application with which construction without an inner layer is also possible, the values obtained are further improved in comparison with the comparable values according to such published application.

Claims

1. A pneumatic vehicle tyre having a single-ply or multiple-ply carcase, more especially a radial carcase in which the reinforcing support members are covered with a wettable or vulcanisable rubber mixture compositions which comprises at least one elastomer which is highly impermeable to gas and has no inner layer in which the rubber mixture composition comprises an elastomer of expoxidised polyisoprene with at least 20 mol% of oxiran.

2. A pneumatic vehicle tyre as claimed in claim 1, in which the polyisoprene is a natural rubber or a synthetic polyisoprene.

3. A pneumatic vehicle tyre as claimed in claim 1 or 2, in which a rubber mixture for the carcase comprises at least 20 parts of epoxidised natural rubber with at least 20 mol % of oxiran and 40 parts of an elastomer or chopped elastomer with good compounding adhesion per 100 parts of rubber.

4. A pneumatic vehicle tyre substantially as hereinbefore described and exemplified.