Patent GB-429346-A (GB)
Title: Method of manufacturing condensation products from urea, formaldehyde, and hexamethylenetetramine
IPC: C08G12/00
Filed: 1933-11-25
Abstract: Urea, formaldehyde and hexamethylene tetramine are condensed in the presence or absence of solvents and at hydrogen ion concentrations, which, when measured in the initial formaldehyde are of greater acidity than a pH of 3 and with the urea present in a molecular proportion of at least 3 to 1 referred to the hexamethylenetetramine and preferably an integral multiple thereof from 15 to 30 to 1 and with formaldehyde present in a molecular proportion of between 2 and 1 to 1 referred to urea.  The whole of the ingredients may be mixed and heated until the mixture becomes acid or part of the urea and formaldehyde may be reacted with all the hexamethylenetetramine with the aid of heat and the residual urea and formaldehyde added to the product as such or as a partially condensed product or all the urea and formaldehyde may be reacted with part of the hexamethylenetetramine the residue being added slowly or the urea and formaldehyde may be condensed in the cold and the hexamethylenetetramine added.  As acid catalysts there may be used inorganic or organic acids compounds yielding acids or salts of acid reaction.  A small proportion of the urea may be replaced by other substances capable of reacting with formaldehyde such as urethane, formamide, acetamide, oxamide, thiourea or phenol.  The products may be worked up with or without fibrous or other filling materials and colouring matters to yield moulded products.  In examples (1) urea, with or without the addition of thiourea is condensed with formaldehyde in the presence of hexamethylenethetramine and oxalic acid; (4) urea is condensed with formaldehyde in the presence of hexamethylenetetramine and oxalic acid and a mixture of urea, thiourea and formaldehyde is added to the condensate; (5) urea and formaldehyde are condensed in the presence of hexamethylenetetramine and the comminuted product is mixed on heated rollers with a condensation product of urea and formaldehyde and cellulose, oxalic acid being added to the first condensate or to the blended product; (8) urea and formaldehyde are condensed in the presence of hexamethylenetetramine and a further quantity of hexamethylenetetramine is mixed with the condensate; (12) urea and phenol or urethane are condensed with formaldehyde in the presence of hexamethylenetetramine and oxalic acid and the product is mixed with further hexamethylenetetramine; (15) urea and formaldehyde are condensed in the presence of oxalic acid, hexamethylenetetramine added, and the product, after mixing with a condensate of urea, formaldehyde and oxalic acid is mixed with a further quantity of hexamethylenetetramine; (16) urea, acetamide and formaldehyde are condensed in the presence of oxalic acid and the product mixed with hexamethylenetetramine.  The Specification as open to inspection under Sect. 91 refers in general to the condensation of urea, formaldehyde and hexamethylenetetramine in the presence of acid catalyst and contains examples describing the condensation of urea and formaldehyde in the presence of hexamethylenetetramine and citric acid.  This subject-matter does not appear in the Specification as accepted.