GB484659A - Improvements in treatment of latex - Google Patents

Abstract

A purified rubber is obtained from latex by subjecting the latex to treatment to solubilize the nitrogenous material naturally present therein, removing the resulting aqueous solution, e.g. by centrifuging or creaming to leave a concentrated latex, diluting the concentrated with water, coagulating the diluted latex and finally washing and drying the resulting coagulum. The solubilization of the nitrogenous material may be effected by treating with an alkali such as sodium hydroxide, potassium hydroxide, ammonium hydroxide or the carbonates or phosphates of the alkali metals, with or without an emulsifier such as soap and with or without heat and pressure; when the digestion with alkali is complete, the latex may be partially neutralized and a stabilizer, e.g. a sulphonic ester of a higher alcohol, may be added. Alternatively, the solubilization may be effected by treating with enzymes such as papain and trypsin. The treated latex may be diluted prior to concentration particularly if it is to be concentrated by creaming, and the concentration, particularly if it is effected by centrifuging, may be effected a number of times diluting with water between each operation. Creaming agents specified are konyaku meal, gum tragacanth and Iceland moss with or without an emulsifier, e.g. potassium coconut oil soap; when heat decomposable creaming agents are employed, the cream may be heated before coagulation to decompose any residual creaming agent. After concentrating by creaming or centrifuging the latex is preferably diluted to a dry rubber content of not more than 5 per cent. The coagulating agent may be formic acid. Compounding materials, e.g. fillers, antioxidants, and coagulation accelerators such as b -naphthol which accelerates the coagulation of latex by acetic acid, may be added before coagulation.