Australian Wool Textile Research (continued)

This work on the influence of chemicals on dye absorption also led to the discovery that the presence of high concentrations of urea in dye liquors greatly accelerates the rate of absorption of dyes by wool. This discovery was used as the basis for new process development, both in Australia and overseas. Thus, CSIRO developed a machine for continuous application of dye to wool top,[45] dyeing being completed in less than 10 minutes, with considerable energy savings, much reduced fibre damage, and virtually no effluent.

With changing consumer requirements through the 1960s, it became clear that there was a need for treatments for wool for certain markets, e.g. uniforms for institutional use, which imparted permanent press as well as full machine-washability. Using resins that were already commercially available, CSIRO, Geelong, developed the process[46] referred to above which entailed treating finished (pressed) garments with the resin in solvent (in a dry-cleaning machine) and then steaming the garments in a special oven or autoclave. The steaming completed the curing of the resin which held the crease in place while being set permanently by the steam.

The chlorine-Hercosett shrink-proofing process -and subsequent modifications of it[47] -are now in widespread use, as already mentioned. The process is principally used for wool in top form, and, while this feeds several market sectors, e.g. worsted knitting yarns for both hand- and machine-knitting, it cannot be used for the woollen system, and there are difficulties in the application of the process to fabric, whatever the system of processing.

In an effort to expand the points in processing at which wool can be shrink-proofed, the 1970s saw research turn to the development of new polymer systems that could be applied to fabric by continuous padding machines. This required that the polymers be water soluble or dispersible. A range of polyurethanes had already been developed in Germany for shrink-proofing wool from dry-cleaning machines, but the polymers were not capable of application from water. Innovative chemistry[48] by scientists at the Melbourne CSIRO Division overcame this problem by making the poly-urethane pre-polymer water-soluble. In developing the process to the industrial level at the Geelong laboratory, these polymers were applied in admixture with water-dispersible polyacrylates to give very good shrink-resistance on wool fabric by a pad-dry sequence. Out of this came the Sirolan BAP process,[49] which is now the main way of shrink-proofing wool in fabric form.

The 1970s also saw the full development of the Sirospun spinning process.[50] As we have seen, the self-twist spinning system was successful in enabling twofold yarns to be produced much faster than by the conventional ring spinning method.

It was still necessary, however, to apply unidirectional twist to these and conventional yarns in a second operation. Moreover, self-twist required new machines rather than modifications to existing ones, and by their nature these machines were not capable of producing single yarns -a requirement for knitwear, for example.

Australian Academy of Technological Sciences and Engineering