Patent GB-599847-A (GB)
Title: Improvements relating to the preparation of quaternary nitrogen salts of melamine-formaldehyde condensation products
IPC: D06M15/423
Filed: 1944-03-22
Abstract: Quaternary nitrogen salts of melamineformaldehyde condensation products are produced by heating an uncured melamine-formaldehyde condensation product, with a salt, advantageously an inorganic salt, of a tertiary nitrogen base at 30-80 DEG  C., a solvent, e.g. methanol or ethanol, optionally being present.  Advantageously, the molecule carries one alcohol-forming radical of at least six carbon atoms and preferred quaternary nitrogen salts are prepared from higher aliphatic alcohols such as octyl, decyl, dodecyl, tetradecyl or octadecyl alcohols; cycloaliphatic and aromatic alcohols also are specified, e.g. cyclohexanol, cycloaliphatic alcohols of more than four carbon atoms, obtainable by the catalytic reduction of naphthenic acids and benzyl alcohol and its homologues.  Preferred salts of tertiary nitrogen bases are those of tertiary amines and of pyridine and its homologues, specified amines being trimethylamine, triethylamine, pyridine, the picolines and the quinolines.  The products are soluble or easily dispersible in water, being applied in the coating or impregnation, e.g. of textiles, leather or paper with melamine resins which can then be rendered insoluble, but unable by simple heating.  In examples: (1) dry trimethylol melamine is refluxed with methyl alcohol containing a trace of oxalic acid and the pH is adjusted to 8.0 prior to concentrating the filtrate in vacuo to isolate the methylated methylol melamine, which is heated with commercial stearyl alcohol containing a trace of phthalic acid, reaction being completed at 130 DEG  C. in vacuo, and the resulting stearylated methylol melamine is finally heated at 60 DEG  C. for 30 minutes with paraformaldehyde and a 17 per cent pyridine hydrochloride solution in pyridine, cooled to 0 DEG  C. and poured into acetone to precipitate the pyridine salt which is isolated by drying at 50 DEG  C.; (2) dry tetramethylol melamine is refluxed with butyl alcohol and the butylated product heated with pyridine hydrochloride and 95 per cent ethyl alcohol; (3) solid methylated tetramethylol melamine and commercial octyl alcohol are heated and the resultant mono-octylated product is heated with pyridine hydrochloride in octyl alcohol; (4) solid methylated tetramethylol melamine heated with commercial lauryl alcohol, and the laurylated product is heated with paraformaldehyde and a 17 per cent pyridine hydrochloride solution in pyridine; (5) tetramethylol melamine is heated with pyridine acetate and 95 per cent ethyl alcohol; (6) pyridine sulphite is heated with laurylated trimethylol melamine; (7) tetramethylol melamine is heated with trimethylamine hydrochloride suspended in ethanol.  The precipitate obtained on heating to boiling a 10 per cent aqueous solution of the product cures to a water-insoluble residue on baking at 140-150 DEG  C.  Tetramethylol melamine is prepared by heating 1 molecule of melamine with 4 molecules of 37 per cent aqueous formaldehyde previously adjusted to pH 8.0, until solution occurs and then for an additional 15 minutes. Pyridine sulphite is prepared by absorbing 66 parts by weight of sulphur dioxide in 79 parts of pyridine.