GB669059A - Improvements in and relating to the treatment of artificial polythiourea threads, filaments, fibres and the like - Google Patents

Abstract

Polythiourea threads are immersed in an aqueous bath containing an aldehyde or a substance yielding an aldehyde under the conditions of treatment, washed until they are substantially free from the contents of the bath and then dried. The treatment renders them dimensionally stable and resistant to boiling water. The preferred aldehyde is formaldehyde, which may be used as such or produced by the conditions of the treatment from hexamethylene tetramine. Other aldehydes which may be used are acetaldehyde and glyoxal. A suitable bath may contain about 8 to 20 per cent by weight of formaldehyde and about 2 per cent of sulphuric acid. The sulphuric acid content should not exceed 5 per cent. The treatment may be carried out at room temperature, but temperatures of from 30 DEG to 50 DEG C. are preferred. The time of treatment depends on the concentration of aldehyde and the temperature of the bath but may be from 15 minutes to 2 hours or more. If desired, the threads may be hardened in a series of baths at increasing temperatures using rollers or reels, partly or completely immersed in the baths. The threads may be stretched before, during or after the treatment. In an example (all percentages by weight) polythiourea threads are immersed for 1 hour at 50 DEG C. in an aqueous solution containing 10 per cent formaldehyde and 2 per cent sulphuric acid. They are then washed and dried. On heating under pressure for 1 hour in water at 160 DEG C. they are substantially unaffected. Specifications 524,795, 534,699, 574,739 and 660,905 are referred to.ALSO:Fabrics, either knitted or woven, comprising polythiourea threads are immersed in an aqueous bath containing an aldehyde or a substance yielding an aldehyde under the conditions of treatment, washed until they are substantially free from the contents of the bath and then dried. The treatment renders them dimensionally stable and resistant to boiling water. The preferred aldehyde is formaldehyde, which may be used as such or produced by the conditions of the treatment from hexamethylene tetramine. Other aldehydes which may be used are acetaldehyde and glyoxal. A suitable bath may contain about 8 to 20 per cent by weight of formaldehyde and about 2 per cent of sulphuric acid. The sulphuric acid content should not exceed 5 per cent. The treatment may be carried out at room temperature, but temperatures of from 30 DEG to 50 DEG C. are preferred. The time of treatment depends on the concentration of aldehyde and the temperature of the bath but may be from 15 minutes to 2 hours or more. If desired, the fabrics may be hardened in a series of baths at increasing temperatures using rollers or reels, partly or completely immersed in the baths. Specifications 524,795, 534,699, 574,739 and 660,905, [Group IV (a)], are referred to.