Manufacturing and Testing Rubber-Coated Automobile Fabrics 270060

MORE than 13,000,000 yd. of rubber-coated top-material was produced in this Country in 1926, and, in addition, approximately 6,000,000 yd. of other types of material, including pyroxylin and oil-coated fabrics, was used for automobile tops. Principal ingredients entering into the manufacture of rubber-coated top and deck material are base fabrics, crude and reclaimed rubber, naphtha, sulphur, accelerators, antioxidants, inert fillers, softeners, and varnishes.

Methods of manufacture are much like those used in the production of cellulose-nitrate or pyroxylin-coated fabrics, and the types of fabric used and their preparation are similar. Processes of preparing the rubber compound, applying it to the fabric, varnishing the surface and embossing the material are described briefly.

The major part of the paper is devoted to detailed description of tests applied to the materials used and to the finished product to assure superior quality and serviceability of the material for the uses to which it is to be put. These include stress-strain tests on the rubber compound, both new and aged; scrub-tests of the coated fabric in a motor-driven scrubbing machine; accelerated aging-tests in an oven for 4 days at a temperature of 158 deg. fahr., by exposure to ultra-violet light, and by a new method of subjecting it to oxygen at a pressure of 300 lb. per sq. in. and a temperature of 140 deg. fahr.; fold tests in a motor-driven machine to determine the breaking end-point; hydrostatic tests to determine its permeability by water; anchorage tests to measure adhesion of the coating to the base fabric and the strength of combining of double-texture material; tests for sulphur blooming of the rubber; weather-exposure tests for 1 year; tests for resistance of the coating to cracking along the edges of folds; and analyses of the base fabric for structure and the rubber coating for weight.

Some of these tests can be made by the car or body manufacturer, but others cannot. It is hoped, however, that many of them will be applicable to work in the automobile plant and will be found of value. It is not necessary to employ all the tests in the case of a coated fabric for any specific purpose; the purchaser need only specify and apply those which indicate the qualities necessary for that purpose. Some of the tests can be written into the purchase specifications; others are of greater use in deciding what types or makes of top material are best.

Discussion brings out the fact that the du Pont company is working to develop an accelerated test to take the place of the exposure test; on a test to combine the effect of ultra-violet light with that of alternating heat and cold; and on the development of a serviceable colored-rubber decking-material. Relative desirability of rubber-coated and pyroxylin-coated fabrics for top material is also discussed; and blooming is said not to injure the aging quality of the rubber coating.