| 摘要 |
Free-flowing powders are made by co-precipitating unvulcanized rubber from a butadiene-styrene copolymer, polybutadiene, a butadiene-acrylonitrile copolymer or polyisoprene latex and an inert carrier, e.g. barytes, perlite, fly ash, ground quartz, carbon black, soapstone or limestone, from an aqueous suspension thereof, to form particles capable of passing a 60-mesh U.S. standard screen (aperture 0.0097 inch), drying, and, if necessary, comminuting the dried precipitate, the powder containing 10-50 per cent of rubber and 90-50 per cent of carrier. Examples are concerned with coagulating a mixture of a 30 per cent GR-S Type I latex and a soapstone slurry and a mixture of a 30 per cent GR-S Type II latex and a barytes slurry. Specification 767,682, [Group V], is referred to.ALSO:Free-flowing powders are made by co-precipitating unvulcanized rubber from latex and an inert carrier, e.g. barytes, perlite, fly ash, ground quartz, carbon black, soapstone or limestone, from an aqueous suspension thereof, to form particles capable of passing a 60-mesh U.S. standard screen (aperture 0,0097 in.), drying, and, if necessary, comminuting the dried precipitate, the powder containing 10-50 per cent of rubber and 90-50 per cent of carrier. An example is concerned with adjusting an aqueous slurry of barytes having particles of 1-25 micron size to pH 9, mixing the slurry with 30 per cent GR-S Type II latex, coagulating the mixture by adding 0,5 per cent aluminium sulphate solution, filtering off the precipitate and drying it to 25-30 per cent water content, extruding the partly dried product as rods, drying the rods to less then 0,5 per cent water content, and then pulverizing them. Other examples are concerned with coagulating mixtures of a natural rubber latex and a barytes slurry, a 30 per cent GR-S Type I latex and a soapstone slurry, a rubber latex and a limestone slurry. Road construction compositions are made by mixing the powders with powdered or liquid asphalt, or by first mixing the powder with an asphalt solvent such as fuel oil, diesel oil or light lubricating oil and incorporating this mixture into a mixture of asphalt and crushed limestone, slate, slag, gravel or the like. Specification 767,682 is referred to.
|
