IE38118L - Tyres, internal lubricant - Google Patents

Abstract

1443929 Lubricating tyre and wheel assemblies after tyre deflation DUNLOP Ltd 23 July 1973 [29 July 1972] 35576/72 Heading B7C A pneumatic tyre and wheel rim assembly comprises a lubricant composition for lubricating regions of the interior surface of the tyre which engage when the tyre is running in a deflated condition, e.g. as a result of a puncture. The composition comprises a blend of a non- volatile rubber-rubber lubricant and a mixture of volatile liquids which boil under a pressure of 760 mm at temperatures in the range 65‹C to 135‹C. (By "non-vclatile lubricant" is meant a lubricant which does not boil at the stated pressure under 160‹C and by "volatile liquid" is meant a liquid which boils at the stated pressure at or below 135‹C). The composition preferably includes a puncpuncture sealing material. When sealing of a puncture occurs the volatile liquids will partially reinflate the tyre. The viscosity of the lubricant at a temperature of 75‹C-130‹C is preferably in the range 5-2,000 centipoises, and the preferred viscosity of the lubricant and volatile liquids is 30-1,000 centipoises at 75‹C. Prior to deflation the composition or part of it may be retained as a gel, which breaks down under shear or by release of a dilatant when deflation occurs. The puncture sealing material may be chopped cotton, wool, asbestos or synthetic fibres of .0001 inch diameter and 0À1 inch length. Graphite, mica, or crumb rubber may be used with, or instead of, the fibrous material. Preferred volatile liquids are water and an alcohol (e.g. ethyl alcohol). The water may also contain non-volatile additives such as cellulose derivatives, e.g. carboxy methyl, cellulose, hydroxy ethyl cellulose; surface active agents--- cationic, acionic and non-ionic; and soaps. The 1.quid components of the composition are preferably miscible with water. The liquid components of the composition should not freeze at temperatures above - 20‹C and preferable - 50‹C. The composition may include a detergent and a defoaming agent. A dispersant may be used when fibres or other insoluble solids are present in the composition. The composition may include an antioxidant or other antidegradant, bactericide, wetting agent and viscosity index improver, and corrosion inhibitor, and preferably has a specific gravity less than 1.4. The composition may be loose within the tyre chamber or may be contained in enclosing means which release the composition on tyre deflation as disclosed in Specification 1,359,461. Preferably the composition is divided into two parts, the volatile liquids and a portion of the lubricant being enclosed as above, and the remainder of the lubricant being made into a gel and coated on the interior surface of the tyre. Any solid ingredients will then be carried by the gel. In one Example the tyre has a two ply, radial, rayon cord carcass, and a folded rayon cord breaker. The preferred composition includes as liquid - 231 mil of a poly(oxyalkylene) glycol, 46 mil water, and 23 mil 74 over proof ethyl alcohol. The viscosity of the liquid is approximately 300, 140 and 100 centipoises at 50, 70 and 135‹C respectively. The composition also includes 15 gms of shredded polythene film, and 1.5 gms of nylon fibres 1 mm long, denier 3. [GB1443929A]