GB408689A - Improvements in or relating to the dehydration of resins - Google Patents

Abstract

Heat sensitive synthetic resins are completely dehydrated by spraying or dispersing the aqueous mixture containing the resin into a stream of gas heated to a temperature above the boiling point of water at the existing pressure. The mixture, e.g. a resinoid produced by digesting 100 parts phenol, 69 parts formaldehyde and 1 part oxalic acid, is sprayed by air or steam heated to 250--300 DEG C. into the top of a cylindrical chamber the lower part of which is cooled by a counter current of cool air or provided with a cool metallic surface from which the dried particles can easily be removed in spherical or fibrous form. The resins may be mixed with hardening-agents, fibrous fillers, dyes, or other synthetic or natural resins. Other gases, e.g. carbon dioxide, helium, &c. or vapours of diphenyl dioxide may be used as the dryingagent.ALSO:Heat sensitive synthetic resins, such as phenol-formaldehyde, glycerol-phthalic anhydride, urea-formaldehyde, and cumarone resins with or without the addition of dyes, plasticizers, solvents or modifying agents, are completely dehydrated by spraying or dispersing the aqueous mixture containing the resin into a stream of gas heated to a temperature above the boiling point of water at the existing pressure. The mixture, e.g. a resinoid produced by digesting 100 parts phenol, 69 parts formaldehyde and 1 part oxalic acid, is sprayed by air or steam heated to 250--300 DEG C. into the top of a cylindrical chamber, the lower part of which is cooled by a counter current of cool air or provided with a cool metallic surface from which the dried particles can easily be removed in spherical or fibrous form. The resins may be mixed with hardening-agents, fibrous fillers, dyes, or other synthetic or natural resins. Other gases, e.g. carbon dioxide helium &c. or vapours of diphenyl dioxide may be used as the drying agent.