Tread buffings

Produce an alternative tyre tread material (from used tyre tread buffings). 

Irrespective of whether the source of waste rubber is whole tyres, tread buffings or GRG, the crumbing operation is sometimes carried out under cryogenic conditions (i.e., it is cooled to below around... 

This method involves the removal of mbber particles from tire tread by abrasion and is confined to the preparation of tire buffings, which is obtained as a by-product of retreading. It is a normal practice in industries to reuse tire buffings to make low-technical products by the revulcanization of the powder or by using the powder-sintering process. 

A process used in the retreading of pneumatic tyres, whereby the new tread rubber is applied by extruding and winding a ribbon of uncured rubber (approximately 35 mm wide and 2.5 mm thick) on to the buffed and solutioned tyre casing. Organic Chemistry... 

Other versions of the machine are designed for specific purposes, e.g., a twin ram machine capable of producing a continuous extrusion, and versions capable of applying tread rubber directly to a buffed tyre carcass whilst simultaneously forming the tread pattern. 

A large proportion of the circa 3.7 x 106 t/yr of natural mbber used in tires is consumed in tmck tires, off-the-road tires, and aircraft tires, all of which demand a low heat buildup performance. The retreading of tmck tires was also the province of natural mbber until the precured process was developed. Prior to the advent of this technique, the tack of natural mbber was essential for the unvulcanized mbber to adhere onto the buffed carcass, and the thickness of the shoulder region was such that the low heat buildup of natural mbber was essential to ensure that no failure occurred in service. With the precured tread process neither of these attributes were necessary and, synthetic mbber, which was and continues to be used, was found to give particularly good wear performance under low severity conditions, especially in the United States. However, work (56) has shown that natural mbber-based formulations can be developed which give a similar order of wear performance to the all-synthetic mbber tread, but with the additional benefit of lower rolling resistance, and hence better fuel economy. 

In the conventional retreading process an unvulcanised tread compound is extruded as a thick strip and a thin layer of a calendered cushion compound is bonded to this strip by passing between a pair of rollers. Then the compound strip with cushion is fixed on to the buffed casing of a tyre, after applying a solution of the cushion compound in naphtha, and vulcanised in a tyre mould. Since the assembly has to be kept in the... 

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