GB439777A - Process for the preparation of dry rubber in finely divided solid condition by spraying latex in a drying atmosphere - Google Patents

Abstract

In the process for preparing rubber powder by spraying latex in a drying atmosphere, the latex has mixed therewith a substance or substances, which during the drying forms a new substance which is deposited as a non-soluble, preferably non-hygroscopic, coating on the rubber particles. Numerous examples are given. Farina dissolved in acidified water, and a condensing agent such as formalin, phenol, or cresol, may be added to the latex, and form an insoluble resinous coating on drying. Soluble proteins such as glue, and tanning agents such as formaldehyde or tannin may also be used, and also the ingredients of synthetic resins, as phenol and aldehyde, or the first stage condensation products themselves. Soluble inorganic substances which are rendered insoluble by heat may also be used. Examples of these are soluble bicarbonates which are converted into insoluble carbonates during drying, and alkaline silicates. Substances may also be added which react with the serum constituents. Examples of these are lime dissolved in a sugar solution, zinc sulphate in ammoniacal solution, soluble silicates, or a small quantity of sulphur and zinc oxide, with or without accelerators, formaldehyde with anti-coagulants such as ammonia. Soluble reaction products may be washed out of the powder, which may also be rendered less liable to agglomerate by dusting with talc, magnesium oxide, zinc stearate, tricalcium phosphate, or the like. Specifications 316,006, [Class 70], and 388,341 are referred to.