Patent GB-1461147-A (GB)
Title: Process for the manufacture of free-flowing pulverulent rubber- filler mixtures which contain plasticiser oil
IPC: C08L7/02
Filed: 1974-05-09
Abstract: 1461147 Free-flowing pulverulent rubber-filler mixture CHEMISCHE WERKE HULS AG 9 May 1974 [12 May 1973] 20496/74 Heading C3P A process for the manufacture of a freeflowing, pulverulent rubber-filler mixture containing plasticizing oil, by combining a filler containing plasticizer oil with an aqueous emulsion of a rubber solution, and precipitating and drying the mixture is characterized in that the plasticizer oil is adsorptively bound on a finely divided filler in an amount of 1-100 parts by weight, relative to 100 parts by weight of the filler, the premix thus obtained, which continues to be free-flowing and pulverulent and consists of filler charged with plasticizer oil, is dispersed in water in the presence of an emulsifier, the resulting dispersion is intimately mixed with an aqueous emulsion of a synthetic rubber solution, this mixture is introduced into an aqueous precipitation bath which is at a temperature of 40-95‹ C. and contains water glass, preferably sodium silicate having a molar ratio of Na 2 O: SiO 2  of 2 : 1-1 : 4, in aqueous solution or an acid and water glass in aqueous solution or an acid, e.g. sulphuric acid and water glass in aqueous solution, whereby the rubber-filler mixture containing plasticizer oil is precipitated with simultaneous stripping-off of the rubber solvent, and the precipitated rubber-filler mixture is separated from the water and dried. Preferred emulsifiers are alkyl- or alkenylamine-oxyethylates of the general formula R<SP>1</SP>N(CH 2 CH 2 O) n H(CH 2 CH 2 O) m H in which R<SP>1</SP> is alkyl or alkenyl (C 1-30 ) and n, m are 1 to 80, e.g. laurylamine-, myristylamine-, cetylamine-, stearylamine- and oleylamine-oxyethylates, generally employed in alkaline solution in amounts which are not only 0À05-2% by weight based on the rubber but also 0À1-6% by weight based on the filler containing plasticizer oil. The filler may be carbon black or silica. The plasticizer oil may consist of aromatic, naphthenic or paraffinic hydrocarbons. The premix of filler and plasticizer oil by fluidizing and mixing the two components with one another in a fluidized bed. Preferred rubbers are polybutadiene, e.g. obtained by adiabatic polymerization of butadiene in the presence of a solvent and a catalyst system of a lithium-organic compound and a Lewis base and containing 25-50% of vinyl groups, a butadiene-styrene copolymer, an EPM polymer or an EPDM polymer. The process may be carried out continuously in a cylindrical container without inserts but provided with an inlet nozzle in the base for the supply of the mixture to be precipitated and a plurality of nozzles around that nozzle for the supply of a heating medium e.g. steam and the precipitants. Alternatively the mixture of aqueous plasticizer oil/filler dispersion and aqueous emulsion of the rubber solution is introduced together with hot aqueous precipitation liquid into a channel of rectangular or semi-circular cross-section. Conventional techniques are used for removing the water. The specific examples describe processes in which a premix of carbon black and plasticizer oil dispersed in water in the presence of laurylamine oxyethylate (n+m = 12) is mixed with an aqueous dispersion of polybutadiene, produced using a Li catalyst, using the same laurylamine oxyethylate as emulsifying agent.