GB685177A - Improvements in aqueous dispersions of butyl rubber-natural rubber blends - Google Patents

Abstract

A dispersion of vulcanized particles of a blend of butyl rubber and natural rubber in aqueous medium contains a dispersing agent, e.g. an alkali metal, ammonium or amine soap, or a glycol ester, of a saturated or unsaturated fatty acid having 10-20 carbon atoms, a protein, or colloidal clay. The butyl rubber is obtained by the polymerization of 99.5-85 per cent of an iso-olefine, e.g. isobutylene, 2-methyl butene-1, 2-ethyl butene-1, with 0.5-15 per cent of a conjugated diene, e.g. butadiene-1,3, isoprene, 2,3 - dimethyl butadiene - 1,3, piperylene. The soap-forming fatty acid is exemplified by capric, undecanoic, lauric, myristic, palmitic, margaric, stearic, oleic, linoleic and arachidic acids and the mixtures of fatty acids with rosin acids in tall oil acids. The ratio of natural to butyl rubber may be from 1 : 10 to 1 : 1. The soap may be 3 to 15 per cent of the blend. A tackifying resin, exemplified by wood rosin and hydrogenated and esterified modifications thereof, coumarone-indene resins, terpene resins, asphalt and allied bitumens, may be incorporated, preferably in amount not exceeding twice the weight of the blend. Examples are concerned with preparing the blend by mixing butyl rubber into smoked sheet banded on a rubber mill, mixing a fatty acid and aqueous ammonia, or aqueous ammonia and potassium hydroxide, and, if desired, the tackifying resin, into the blend to produce a dispersion thereof, adding aqueous pastes of sulphur, zinc oxide and zinc dibutyl dithiocarbamate, and, if desired, sym. di-b -naphthyl-p-phenylene diamine, and vulcanizing the particles of the blend by heating the so-compounded dispersion for 18-24 hours at 60 DEG C. Specification 679,336 is referred to.ALSO:IV (a) A dispersion of vulcanized particles or a blend of butyl rubber and natural rubber in aqueous medium contains a dispersing agent, e.g. an alkali metal, ammonium or amine soap, or a gly col ester, of a saturated or unsaturated fatty acid having 10-20 carbon atoms, a protein, or colloidal clay. The ratio of natural to butyl rubber may be from 1 : 10 to 1 : 1. Soap, if em ployed as dispersing agent, may be 3-15 per cent of the blend. A tackifying agent, exempli fied by wood rosin and hydrogenated and esteri fied modifications thereof, coumarone-indene resins, terpene resins, asphalt and allied bitu mens may be incorporated, preferably in amount not exceeding twice the weight of the blend. Examples are concerned with preparing the blend by mixing butyl rubber into smoked sheet banded on a rubber mill, mixing a fatty acid and aqueous ammonia, or aqueous ammonia and potassium hydroxide, and, if desired, the tackifying resin, into the blend to produce a dis persion thereof, adding aqueous pastes of sul phur, zinc oxide and zinc dibutyl dithiocarbam ate, and, if desired symmetrical di-b -naphthylp-phenylene diamine, and vulcanizing the par ticles of the blend by heating the so-compounded dispersion for 18-24 hr, at 60 DEG C. Specifica tion 679,336 is referred to.