Patent GB-382271-A (GB)
Title: Process for the manufacture of artificial resins, moulding compositions and artificial masses by condensation of dicyandiamide with formaldehyde
IPC: C08G12/16
Filed: 1931-07-09
Abstract: The manufacture of hydrophobe resins by condensing dicyandiamide with formaldehyde is conducted at an acidity less than pH 5, preferably at pH 8-10, whereby the sensitiveness of the products to water is reduced.  The condensation may be effected in the presence of substances splitting off hydroxyl ions and with or without the addition of buffer mixtures.  The reaction mixtures may be boiled and then cooled or diluted to precipitate the resin, which may then be washed, melted, and mixed with fibrous fillers.  Alternatively, the hot condensation solution may be mixed with the fillers and the mixture dried.  The condensation may also be effected below the boiling point or under raised pressure.  The products can be moulded under heat and (or) pressure, care being taken that a little water remains in the products, to facilitate moulding.  The products can be improved by incorporating metal salts with the resins or the moulding powders; salts specified are copper sulphate, zinc chloride, lead nitrate, nickel sulphate, cobalt chloride, aluminium sulphate, stannous chloride, barium chloride, and mercury chloride.  In the examples, (1) dicyandiamide (1 mol.) is dissolved in formaldehyde solution (1\se mol.), caustic soda solution is added, and the mixture is boiled and mixed while hot with cellulose; the product is dried until about 5 per cent of water is present, mixed if desired with pigments, and moulded under heat and pressure; (2) dicyandiamide (1 mol.) is dissolved in formaldehyde solution (2 mols.), caustic soda solution is added, and the mixture is heated to 80 DEG  C. and then worked up as in example (1); (3) 1-2 per cent of stannous chloride is incorporated in the moulding compositions obtained in examples (1) and (2); (4) the condensation is allowed to proceed only so far that a coldmoulding composition is obtained, the final polymerization and drying being effected after moulding; (5) paper or fabric is impregnated with the reaction solution in its initial or final state, and after drying and polymerizing, the products are compressed to form laminated articles. Specifications 314,358 and 323,047, [both in Class 2 (iii), Dyes &c.], also are referred to.ALSO:Hydrophobe resins, prepared by condensing dicyandiamide with formaldehyde at an acidity less than pH5, preferably at pH8-10, are mixed with fibrous fillers, or alternatively, the hot condensation solution is mixed with the fillers and the mixture dried.  The products can be moulded under heat and/or pressure, care being taken that a little water remains in the products, to facilitate moulding.  The products can be improved by incorporating metal salts with the resins or the moulding powders; salts specified are copper sulphate, zinc chloride, lead nitrate, nickel sulphate, cobalt chloride, aluminium sulphate, stannous chloride, barium chloride, and mercury chloride.  In examples, (1) dicyandiamide (1 mol.) is dissolved in formaldehyde solution (1,5 mol.), caustic soda solution is added, and the mixture is boiled and mixed while hot with cellulose; the product is dried until about 5 per cent of water is present, mixed if desired with pigments, and moulded under heat and pressure; (2) dicyandiamide (1 mol.) is dissolved in formaldehyde solution (2 mols.), caustic soda solution is added, and the mixture is heated to 80 DEG  C. and then worked up as in example (1); (3) 1-2 per cent of stannous chloride is incorporated in the moulding compositions obtained in examples (1) and (2); (4) the condensation is allowed to proceed only so far that a cold-moulding composition is obtained, the final polymerization and drying being effected after moulding; (5) paper or fabric is impregnated with the reaction solution in its initial or final state, and after drying and polymerizing, the products are compressed to form laminated articles. Specifications 314,358 and 323,047, [both in Class 22, Cements &c.], also are referred to.