GB305490A - Process for the manufacture of rubber pastes - Google Patents

Abstract

305,490. I. G. Farbenindustrie Akt.- Ges. Feb. 3, 1928, [Convention date]. Emulsions, making.-A reversible rubber paste which can be homogeneously mixed with fillers, vulcanizing agents, and the like, is prepared from natural latex, the latex of synthetic rubber, or a latex-like substance or mixture by treatment with a water-soluble cellulose ether or a solution thereof, heating to produce a precipitate, and separating the latter from water. On heating the cellulose ether is precipitated in gelatinous form carrying with it the rubber particles, and water is largely removed by means such as clarification, filtration, pressing or centrifuging. The paste may be used in place of latex for all purposes, such as painting and adhesive purposes, and can be diluted to a milk preferably in the presence of protective colloids. It is desirable to remove the emulsifying agent wholly or partially from synthetic rubber emulsions before the concentration process. In one example, 100 kgs. of 20 per cent ammonia-preserved natural latex are mixed with 2 kgs. of a cellulose methylether at 15‹ C., heated to 55‹ C., and the precipitate extracted in a bag on a heated centrifuge. The product is stated to contain upwards of 50 per cent rubber in a short time. In another example 50 kgs. of latex obtained by the polymerization of isoprene with an aqueous solution of Turkey red oil and sodium phosphate are mixed at 15‹ C. with 15 kgs. of a 10 per cent solution of trimethyl cellulose;'after standing for some hours at ordinary temperatures, when two layers are formed, the upper aqueous layer of rubber-free liquid can be drawn off, the latex then being heated to 40‹-60‹ C., and the paste extracted as before.