GB835801A - Improvements in or relating to mastics - Google Patents

Abstract

A mastic coating composition comprises a binder, said binder including from 20 to 40% of the binder of an isobutylene polymer or copolymer plasticized with from 20 to 60% of the binder of an asphaltene-free chemical condensation product obtained by subjecting a precipitated fraction of a natural paraffinic crude oil distillation residue to air oxidation having an iodine number below 40, a ball and ring softening point above 110 DEG F. and up to 200 DEG F., an average molecular weight of at least 1900, at least 40 carbon atoms per double bond, a susceptibility to penetration with temperature change of less than 2 units per DEG F. within the range of 30 DEG F. to 60 DEG F. and substantially complete solubility in 88 DEG Baume Naphtha. The isobutylene polymer may be a copolymer of isobutylene with styrene or isoprene, e.g. butyl rubber. The binder may also comprise a flame retardant such as chlorinated paraffin wax, a fibrous filler such as asbestine or asbestos, a non-fibrous filler such as micaceous talc, antimony oxide, ground vegetable cork or a gelling agent, e.g. of the bentonitic type, to render the composition thixotropic. The binder may be applied e.g. by brushing, spraying or trowelling, to form coatings on moulded and other thermal insulation in solution in an organic solvent, e.g. xylol, petroleum fraction or methyl isobutyl ketone, to which denatured alcohol or water and a wetting agent may be added to control the flow. The surface of the insulation, e.g. magnesia block, fibre glass, foam glass, mineral wool or cork board, may be covered with wire netting or a similar material such as woven glass fabric prior to coating to secure the coating to the insulation. U.S.A. Specification 2,337,336 is referred to.ALSO:A mastic coating composition comprises a binder containing from 20 to 40% of an isobutylene polymer or copolymer plasticized with from 20 to 60% of the binder of an asphaltene-free chemical condensation product obtained by subjecting a precipitated fraction of a natural paraffinic crude oil distillation residue to air oxidation, having an iodine number below 40, a ball and ring softening point above 110 DEG F. and up to 200 DEG F., an average molecular weight of at least 1900, at least 40 carbon atoms per double bond, a susceptibility to penetration with temperature change of less than 2 units per DEG F. within the range of 30 DEG F. to 60 DEG F. and substantially complete solubility in 88 DEG Baume Naphtha. The isobutylene polymer may be a copolymer of isobutylene and styrene or isoprene, e.g. butyl rubber. The binder may also comprise a flame-retardant such as chlorinated paraffin wax, a fibrous filler such as asbestine or asbestos, a non-fibrous filler such as micaceous talc, antimony oxide, ground vegetable cork or a gelling agent e.g. of the bentonitic type, to render the composition thixotropic. The binder may be applied to form coatings on moulded and other thermal insulation in solution in an organic solvent, e.g. xylol, petroleum fractions or methyl isobutyl ketone, to which denatured alcohol or water and a wetting agent, e.g. alkyl aryl polyether alcohol or dioctyl sodium sulphosuccinate, may be added to control the flow of the composition. U.S.A. Specification 2,337,336 is referred to.