Patent GB-515467-A (GB)
Title: Improvements in or relating to the production of cast synthetic resins
IPC: C08L61/02
Filed: 1938-02-28
Abstract: 515,467. Resinous condensation products. LOSS, K. Feb. 28, 1938, Nos. 6266 and 6267. Convention dates, Feb. 27, 1937, and March 13, 1937.. [Class 2(iii)] Machinable cast resins are obtained by condensing phenol and formaldehyde with the aid of an alkaline catalyst, mixing the product with a condensation product of acetone and formaldehyde, heating the mixture to effect further condensation, acidifying, preferably with an organic acid, distilling, casting and hardening. Urea, with or without phenol, may replace part of the acetone ; or a urea-formaldehyde condensate may be added to the mixture prior to heating. Alternatively, the phenol and formaldehyde may be first condensed under alkaline, and then under acid conditions until the resin separates, the resin being then mixed with an acetone-formaldehyde condensate and the mixture distilled, cast and hardened. In both processes, urea may be added during distillation to expedite hardening and to increase opacity. As a modification, one of the condensates may be replaced by the initial materials. The acetoneformaldehyde condensate is preferably formed by condensing 1 mol of acetone with 4-6 mols of urea in the presence of a small amount of basic catalyst, the reaction being stopped when a colourless, water-soluble alcohol-like condensate is obtained. Acetaldehyde may replace part of the formaldehyde, and acetone may be replaced by methyl ethyl ketone, butyl ketone or other ketones. Colourless or coloured, transparent, translucent or opaque products are obtained. Plasticizers may be added to reduce opacity..Examples 3, 5 and 7 illustrate the working up of mixed condensates and Example 6 the further addition of a urea-formaldehyde condensate ; in'Examples 1 and 2, part of the acetone is replaced, respectively, by urea and phenol, and urea. In Example 4, a phenol-formaldehyde resin, obtained by alkaline, followed by acid condensation, is mixed with an acetone-formaldehyde condensate and distilled. Example' 8 illustrates the working up of a phenol-formaldehyde condensate with acetone and formaldehyde, and Examples 9 and 10, the working up of an acetone formaldehyde condensate with phenol and formaldehyde. In Examples 1 and 5 methylphthalyl-ethyl glycollate is added during distillation ; Example 7 further refers to glycerine or triacetone as plasticizer. The Specification as open to inspection under Sect. 91 includes also the similar working-up of phenol-formaldehyde and urea-formaldehyde condensates, and of urea-formaldehyde and acetone-formaldehyde condensates. Phenol may be replaced by cresol or higher homologues and thiourea may replace urea. Examples 1, 4-8 and 12-16 involve the separate preparation of phenol-formaldehyde and' urea-formaldehyde condensation products in the presence of basic catalysts, viz. caustic soda or potash or potassium carbonate for phenol and caustic soda, ammonia, ammonium sulphide and pyridine for urea. Other examples involve the working up of a phenol-formaldehyde condensation product with urea and formaldehyde, either before (11, 18) or after (9) acidification ; or (17) with an acid-condensed urea-formaldehyde product after acidification. Example 23 refers to the working up of acetone-formaldehyde and urea-formaldehyde condensates. ' Examples 5, 8-10, 12-14 and 16 include plasticizers, viz. methyl-phthalyl-ethyl glycollate, glycerine and amyl acetate. This subject-matter does not appear in the Specification as accepted.