Abstract
Evidence is presented showing that only a very small proportion of dihydroxydimethylol cyclic ethylene urea (DHDMEU) is fixed when a bath containing equal amounts of melamine-formaldehyde (MF) and DHDMEU precondensate solids at a pH of 2 is used in wet fixation. The presence of DHDMEU also suppresses fixation of the MF component. Under more acid conditions, where more efficient fixation of DHDMEU occurs, so that high smoothness and wrinkle recovery are obtained with either or both components, DHDMEU gives the lowest and MF the highest strength and abrasion resistance, with mixtures giving intermediate results.
Several MF precondensates of differing constitution have been compared in wet fixation by the continuous steaming and the cold batch procedures. In both cases, it was essential to maintain a high formaldehyde/melamine ratio on the fabric during the wet cure stage, so as to ensure adequate cross-linking in the final cure.
A novel method of wet fixation, involving passage of the impregnated fabric through a hot oil bath is described.