GB895678A - Sealing composition - Google Patents

Abstract

A polymerizable composition, useful for sealing joints, e.g between concrete pavements in aerodromes comprises a polysulphide liquid polymer and coal tar, The polymer is defined as containing at least three disulphide linkages per molecule, and as being at least bifunctional, at least one of the functions being a mercaptan group. Other functional groups which may be present are hydroxy, allyl, carboxyl. Alkyl or aryl groups may also be present. Preferred polymers have the formula HS-(RSS)n-RSH, wherein n has a value from 20 to 45 and R is -C2H4OCH2OC2H4-. The preferred tar is one with a viscosity between 20 seconds Saybolt Furol at 77 DEG F. and 150 seconds Saybolt Furol at 210 DEG F. High viscosity tar may be used if thinned with an aromatic solvent. Extenders or fillers, e.g. hard clay, carbon black, slate flour, silica, limestone or asbestine may be added. Conventional curing agents may be added, e.g. lead peroxide, an organic peroxide or metallic oxides in presence of hexamethylenetetramine. Lecithin may be added as a viscosity reducer, and stearic acid as a polymerization retarder. In a typical example two mixtures are prepared, one containing coal tar, clay, lead peroxide and lecithin, and the other polysulphide liquid, coal tar, clay and lecithin. The liquids are mixed just before use. Polymerization starts immediately and is complete within 48 hours. U.S.A. Specification 2,466,963 is referred to.