GB614625A - Improvements in the production of condensation polymers - Google Patents

Abstract

<PICT:0614625/III/1> Linear condensation polymers are produced by heating a polymer-forming reaction mass by infra-red radiation while the mass is in the form of a thin layer, preferably of a thickness less than 0.025 in. The mass is heated and allowed to cool in an inert atmosphere, for example nitrogen or hydrogen. Polyamides, e.g. polyhexamethylene adipamide, polyesters and nitrogen-containing polymers may be prepared (see Group IV (a)). The reaction mass may be in the form of a fine powder or brought to a liquid or semi-liquid condition by adding a solvent or non-solvent, e.g. phenol, cresols, or xylenols. To assist in p uniform heating, the support for the mass may be vibrated, and its surface may be blackened. In the apparatus shown, the reaction mass is fed from a hopper 23 on to a travelling band 21 in a chamber 20, and formed into a thin layer by an adjustable blade 31. Heating is effected by infra-red lamps 33, and the surface behind the lamps may be coated with a reflecting material, e.g. gold or aluminium; gas-heated refractory materials may also be used for the heating. The temperature of the reaction mass is raised to 200-300 DEG C., preferably 220-270 DEG C., the product cooled while passing through the left-hand part of the chamber 20, and removed from the band by a blade 34; inert gas is introduced at 36 and leaves at 37. The process may also be carried out in an apparatus (Figs. 1 and 2, not shown) comprising tiers of chambers in which shallow trays containing the reaction mass are supported on rollers.ALSO:Linear condensation polymers are produced by heating a polymer-forming reaction mass by infra-red radiation, while the mass is in the form of a thin layer, preferably of a thickness less than 0.025 in. The mass is heated and allowed to cool in an inert atmosphere, for example nitrogen or hydrogen. Polyamides may be prepared according to Specifications 601,123, 610,304 and 610,311; from aminocaproic acid or higher homologues of this acid; or from dicarboxylic acids (or their esters and amides) and diamines. Suitable acids are adipic, suberic, sebacic, brassylic, paraphenylene di-acetic and terephthalic acids; suitable amines are tetramethylene, pentamethylene, hexamethylene, and decamethylene diamines; paraxylylene and metaphenylene diamines; and piperazine. Polyesters may be prepared from dihydroxy compounds (e.g. tetramethylene and hexamethylene glycols) and the dicarboxylic acids listed above; or from hydroxycarboxylic acids. Nitrogen-containing polymers may be prepared according to Specifications 612,609 and 613,020. The reaction mass may be in the form of a fine powder or brought to a liquid or semi-liquid condition by adding a solvent or non-solvent, e.g. phenol, cresols, or xylenols. In the production of polyhexamethylene adipamide from hexamethylene di-ammonium adipate mixed with xylenol, the reaction product is purified by dissolving in formic acid and pouring into acetone. The reaction mass is heated by infra-red lamps or gas-heated refractory material to the required temperature (e.g. 200 DEG -300 DEG C., and preferably 220 DEG -270 DEG C.) on shallow trays in a chamber, or spread on a travelling band which passes through the chamber (see Groups III and XI).