Patent GB-573482-A (GB)
Title: Improvements in or relating to the production of derivatives of linear polyamides
IPC: C08G69/50
Filed: 1943-06-02
Abstract: Derivatives of polyamides (including polyesteramides) are formed by reacting linear polyamides having hydrogen-bearing amide groups with formaldehyde and with an alcohol, mercaptan, amide or amine, the polyamide being in solution in an oxygen-containing acid, or being in a pulverised form, the reaction being conducted in the presence of an oxygen-containing acid as catalyst. Suitable oxygen-containing acids are formic, trimethylacetic, chloracetic, benzoic, maleic, p-toluenesulphonic, and the acids of phosphorus.  The preferred temperature range for the solution method is 25 DEG  to 75 DEG  C. The degree of substitution of the polyamide may be varied over a wide range by varying the conditions of the reaction, e.g. the temperature, time, or concentrations of formaldehyde and water.  When using pulverised polyamide the temperature is preferably between 75 DEG  and 200 DEG  C., and the reaction is performed in a sealed vessel.  The acid concentration varies with the nature of the acid. For phosphoric it is 1-2 per cent but it may be as high as 10 per cent. Suitable alcohols are methanol, ethanol, propanol, butanol, isobutanol, cyclohexanol, furfuryl alcohol, methoxymethyl alcohol, octyl alcohol, lauryl alcohol, stearyl alcohol, allyl alcohol, oleyl alcohol, dimethyl (vinyl and ethinyl) carbinol, benzyl alcohol, hydroxyacetic acid, methyl hydroxyacetate, ethanolformamide, dimethyl - b  - hydroxyethylamine, ethylene glycol, glycerol. triethanolamine. Preferably, the alcohol contains less than 8 carbon atoms/molecule. Monohydric straight chain alcohols with 12 or more carbon atoms/molecule may be used to impart good water resistance if desired.  Suitable mercaptans are ethyl or butyl mercaptan, ethanedithiol, 1-thiosorbitol, allyl mercaptan, and mercaptoacetic acid.  Suitable amides and amines are formamide, acetamide, N-methyl acetamide, adipamide, benzamide, acetanilide, p - toluenesulphonamide, butanesulphonamide, N-methylbenzenesulphonamide, diethylamine, methylamine, piperazine, hexamethylenediamine, ethanolamine, allylamine and morpholine.  The process of the invention markedly affects the properties of the polyamides, notably their softening temperature, solubility, elasticity and pliability. A table is given comparing the properties of two treated polyamides with those of the untreated material.  The modified polyamides may be soluble in aqueous ethanol, and mixtures of alcohols and chlorinated hydrocarbons, e.g. methanol-chloroform mixtures.  The solutions are useful for making clear films or for coatings. Sheets of the polyamide derivatives may be formed on conventional milling equipment.  Fabrics coated with the derivative are useful for leather substitutes.  The materials are resistant to penetration by gasoline and gasoline-benzene resistors.  They may be spun into filaments, varns, bristles and the like, or used for moulded articles, electric insulation, adhesives, or impregnating agents.  They may be mixed with plasticisers such as sulphonamides and phenols, with proteins, with resins, e.g. phenol-formaldehyde, or sulphonamide-formaldehyde, pigments, e.g. carbon black or titanium dioxide, dyes, cellulose derivatives, antioxidants or with other modifying agents.  Examples describe: (1) treatment of polyhexamethylene adipamide, dissolved in formic acid with paraformaldehyde and methanol.  The solution was poured into a mixture of acetone and water and was made basic with ammonia.  The product separated as a white granular solid.  A transparent film was prepared by dry-casting a solution of the product in 80 per cent ethanol; (2) solid polyhexamethylene adipamide was treated in a sealed vessel with paraformaldehyde, methanol, and a little phosphoric acid.  The product-a translucent gel-was dissolved in hot 95 per cent ethanol containing enough ammonia to neutralise the acid, and the solution poured into water to precipitate the product as a soft plastic mass; (3) a solution of an interpolyamide from hexamethylenediammonium adipate and sebacate in formic acid was treated with paraformaldehyde and benzyl alcohol, then diluted with ethanol and the product precipitated with caustic soda; (4) similar to (3), methyl hydroxy-acetate being used instead of benzyl alcohol. Films were prepared by dry-casting a solution of the product in aqueous ethanol; (5) a solution of polyhexamethylene adipamide in formic acid was treated with an aqueous solution containing formaldehyde and methanol.  Methyl formate poured into the solution precipitated the product as a fine white powder; (6) a solution of polyhexamethylenediammonium adipamide in formic acid was treated with paraformaldehyde and ethyl mercaptan.  Pouring the solution into caustic soda precipitated the product as a white fibrous solid; (7) a solution of polyhexamethylene diammonium adipamide in formic acid was treated with paraformaldehyde and aniline.  A reddish solid product was precipitated by addition of caustic soda to the solution; (8) a similar solution was treated with acetamide and paraformaldehyde and poured into caustic soda.  The product separated as a spongy white solid, soluble in hot 95 per cent ethanol and in acetic acid; (9) a similar solution was treated with paraformaldehyde and hydroxyacetic acid, added to an acetone-water mixture, and treated with aqueous ammonia.  A white solid separated, soluble in hot aqueous alcohol. Specifications 461,236, 461,237, 474,999, 534,698 and 537,009 are referred to.