Patent GB-574739-A (GB)
Title: Treatment of linear polymers with formaldehyde or formaldehyde-liberating substance
IPC: C08G18/84
Filed: 1942-05-06
Abstract: Linear polymers containing, as integral members of the main chain of atoms therein, groups of the structure <FORM:0574739/IV/1> but not containing, as integral members of the main chain of atoms therein, groups of the structure <FORM:0574739/IV/2> where X represents an oxygen or sulphur atom and Q represents an oxygen or sulphur atom or an NH or N-alkyl group, are heated in the presence of formaldehyde or a formaldehyde-liberating substance, whereby their softening points are markedly increased, their solubilities in organic liquids are very much reduced, and their flexibility is increased.  Plasticizers, pigments and fillers may be admixed with the products.  The linear polymers mentioned above include polymers, polythioureas, and N-alkyl derivatives thereof, as well as polycarbonates and polythiocarbamates.  It is preferred to effect the heating in the presence of an acid, an acid anhydride, or an acid-reacting salt, or in the presence of a material which is substantially neutral and remains so during any milling or other mixing operation prior to the heating, but which develops acidity during the heating, e.g. to 100-150 DEG  C.  Specified formaldehyde-liberating substances are paraformaldehyde, trioxane, dimethylolurea, trimethylolmelamine, hexamethylolmelamine, diphenylol-propane tetra-alcohol, methylolchloracetamide, methylol stearamide, N-methylol-p-toluenesulphonamide, dimethylolurea dimethyl ether, dimethylolurea dibutyl ether, N : N1-dimethyloluron dimethyl ether, 1 : 2-glycol methylene ether, di-(b -hydroxyethyl) formal, and hexamethylene - tetramine - zinc chloride complexes. Specified additions, in the presence of which heating may be carried out, are formic, glycollic, oxalic, succinic, maleic, stearic, adipic, tartaric, salicyclic, anthranilic, phthalic, citric, tannic, boric and phosphoric acids, phthalic and maleic anhydrides, phthalimide, potassium or sodium dihydrogen phosphate, butadiene sulphone, butadiene tetrabromide, 2 : 3-dimethylbutadiene sulphone, styrene dibromide, acetylene tetrabromide, tribromohydroquinone, 1-bromo-2-naphthol, 1 : 6-dibromo-2-naphthol, 1 : 4 : 6-tribromo-2-naphthol, 2 : 4-dibromo - 1 - naphthol, methyl a  : b -dibromo-propionate, p-chloroethyl a  : b  - dibromoisobutyrate, ethyl a  - bromopropionate, phenyl trichloroacetate, a  : a  : b -trichloro-propionitrile, trichloroacetamide, trichloroacetyldiethylamide, N-trichloroacetylanilide, N : N1-di-(trichloroacetyl) methylenediamine, N : N1-di-(trichloroacetyl) ethylenediamine, interpolymers of asymmetrical dichloroethylene and vinyl chloride, and chloranil.  Examples are given in which: (1) a polycarbamate obtained from hexamethylene glycol and hexamethylene diisocyanate is heated with paraformaldehyde in the presence of maleic anhydride; (2) a polyurea obtained from decamethylene diamine and hexamethylene diisocyanate is heated with para formaldehyde in the presence of maleic anhydride. Specifications 461,237, 524,795, 528,437, 530,267, 534,699, 535,139 and 32979/38 (as open to inspection under Sect. 91) are referred to.