Latex coagulation process using lignin compound
AssigneePolysar Limited
InventorsMelvin John George Davidson, Richard Helmut Wunder
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Abstract
Synthetic styrene-conjugated diolefin polymers, e.g. SBR rubbers, are recovered from their aqueous polymerization emulsion by coagulation with acid and a lignin compound. The conventional use of sodium chloride as a coagulant is avoided so as to overcome the problem of sodium chloride in the effluent. By this process of the invention, a rubber crumb of increased porosity is obtained, which is easier to dry.
Claims5
A process of recovering synthetic styrene-conjugated diolefin polymers from aqueous latex which comprises coagulating the latex, in the substantial absence of sodium chloride, at a temperature of from about 100.degree. F. to about 180.degree. F. in the presence of sufficient sulphuric acid to maintain the pH of coagulation at about 2.5 to about 3.5 and subsequently separating the coagulated polymer from the serum, the improvement being the addition of from about 0.2 to about 5 parts by weight, per 100 parts by weight of dry polymer solids, of a lignin compound selected from powdered lignin, sodium lignate, potassium lignate and ammonium lignate.
Dependencies are inferred from the claim text.