GB1382030A - Covers for conveyor belts - Google Patents

Abstract

1382030 Laminated conveyer belts COAL INDUSTRY (PATENTS) Ltd 18 Aug 1972 [18 Aug 1971] 38814/71 Heading B5N A fabric reinforced conveyer belt comprises as the cover thereof, a thermoplastic composition which comprises at least 10% of coal pitch, between 18 and 65% of a polymeric thermoplastic material compatible with the coal pitch, 1 to 20% of finely divided fibrous material, at least 10% of a plasticizer for the polymeric thermoplastic material and at least 0À2% of an anti-static agent, the percentages being by weight and based on the total composition. A coal pitch is defined as being a tar or pitch formed by the destructive distillation of coal, or a similar material formed by the extraction of soluble or solubilizable components of coal into solvents. The belt may be formed by coating sheets of fabric to form multiply belts with for example a polyvinyl chloride mixture and laminating the sheets together under heat and pressure, e.g. on a drum or on a stationary press, the thermoplastic composition for the cover being laminated therewith during or after lamination of the core. The polymeric thermoplastic material may be polyvinyl chloride, a copolymer of vinyl chloride with a suitable monomer, e.g. vinylidene dichlbride or vinylacetate, or a mixture thereof. The fibres are preferably organic fibres, e.g. cotton, cellulose, polyamide or polyester fibres, at least 75% by number thereof having a length of less than about 15 mm. The plasticizer may be an ester, e.g. a diester of an aliphatic or aromatic dicarboxylic acid, a phosphate ester or a low molecular weight diol-dicarboxylic acid polyester, many suitable plasticizers being specified. The anti-static agent may be a quaternary amminium salt, e.g. a tetraalkyl ammonium salt, a polyether, a long chain amine or amide, an oxyalkylated or polyoxyalkylated amine or a sulphonate, many such compounds being specified. The composition may also contain a suitable quantity of a material having similar properties to coal pitch, e.g. bituminous material formed from petroleum oil. Natural or synthetic rubber, e.g. a chloroprene rubber, an ethylene-propylene rubber, an isoprene rubber, a styrene-butadiene rubber, an acrylonitrilebutadiene-styrene rubber, a chlorosulphonated polyethylene rubber, a nitrile rubber or a copolymer of acrylonitrile with butadiene or styrene may be included in the composition as may a fire-retardant substance, e.g. a brominated organic compound or antimony trioxide alone or in admixture with a further fire-retardant substance, e.g. ammonium fluoroborate, dichlorane or a chlorinated wax, fillers, e.g. carbon black or chalk or extenders, e.g. chlorinated hydrocarbons.