Improvements in and relating to elastic textile fabrics and yarns

777,449. Finishing fabrics. BLEACHERS ASSOCIATION, Ltd., and BRADFORD DYERS' ASSOCIATION, Ltd. Sept. 9, 1954 [Sept. 12, 1953], No. 25251/53. Class 42 (1). [Also in Group IX] Thermoplastic textile fabric is rendered elastic by mechanically shrinking it in a compressive shrinking machine to a predetermined length shorter than its normal length and setting the fibres in their shrunk condition by heating and cooling. Temperatures employed in the setting treatment are from 250‹ to 400‹ F. The shrinking is preferably effected on a machine as described in Specification 529,579 or in a machine employing a contracting surface as described in Specification 402,087, and imparts a fine crimp to the fibres. By " thermoplastic textile fabric " is meant a woven or knitted fabric which contains a substantial proportion of thermoplastic fibres. Such fibres may be made of polyamides, polyaminolactams, polyesters, polyacrylonitrile, polyvinyl or polyvinylidene esters, or co-polymers thereof. The degree of elasticity imparted may be controlled by varying the amount of shrinkage and by adjusting the temperature of the setting treatment. Shrinking and heat-treatment are preferably carried out simultaneously, but may be effected successively. In an example, a fabric of " Terylene " (Registered Trade Mark) was shrunk by 38 per cent at 350‹ F.; the fabric then had an extensibility under load of 25 per cent with 100 per cent elastic recovery. When used for electrical insulation, the elastic fabric is given one or more coatings of a, linseed oil base varnish which is baked on, e.g. by passing the fabric through a bath of the varnish and guiding it up and down a tower through which hot air circulates. Specifications 359,759, 371,976, 372,803 and 400,950 also are referred to.