Patent GB-776346-A (GB)
Title: Improvements relating to the treatment of textile materials comprising fibres of cellulose triacetate
Inventor: FINLAYSON DONALD
IPC: D06M13/12
Filed: 1953-11-25
Abstract: Textile materials comprising fibres of cellulose triacetate (i.e. cellulose acetate of acetyl value 59-62.5 per cent) of a normal degree of crystallinity are treated with an organic liquid which is a swelling agent for cellulose triacetate to increase the degree of crystallinity.  Cellulose triacetate fibres of a normal degree of crystallinity are defined as cellulose triacetate fibres as first obtained by melt-spinning or wet- or dry-spinning processes, or by completely acetylating unoriented, partly acetylated, cellulose filamentary materials.  The term "organic liquid" includes liquid mixtures of which at least one component is organic, and the term "swelling agent" denotes substances which, under the treatment conditions employed, are capable of swelling but not of dissolving cellulose triacetate.  Preferred swelling agents are the normally liquid aromatic hydrocarbons, alkyl halides of boiling point above 50 DEG  C., acetone-water mixtures containing 30-70 per cent by weight of acetone and mixtures of acetone and a monohydric alcohol containing 1-4 carbon atoms in the molecule, the mixture containing 20-70 per cent by weight of acetone.  Monohydric alcohols containing 1-4 carbon atoms in the molecule are less effective swelling agents. Aromatic hydrocarbons and nonsolvent alkyl halides of boiling point above 50 DEG  C., e.g. propyl bromide, are preferably used at about 60-90 DEG  C., but acetone-water and acetone-alcohol mixtures can be used at temperatures down to about 15 DEG  C., and particularly at 15-40 DEG  C.  In an example, two portions of a fabric woven from a melt-spun cellulose triacetate yarn are immersed for 2 and 6 hours respectively in boiling benzene, drained and freed from benzene by evaporation.  In a second example, two more pieces of the same fabric are treated for 20 minutes with a mixture of equal parts by weight of acetone and water and a mixture of 40 per cent by weight of acetone and 60 per cent by weight of ethyl alcohol respectively at about 20 DEG  C.  The process increases the safe ironing temperature of cellulose triacetate woven fabrics from the usual value of about 170-180 DEG  C. to a temperature substantially higher than 180 DEG C., for example about 200-230 DEG  C.  The sticking temperature of the fabric, i.e. the lowest temperature at which a heated iron, after standing on the fabric for 10 seconds, causes the fabric to stick to its surface, is correspondingly raised, e.g. by at least 10 DEG  C. The tendency of the textile material to shrink slightly during the treatment is preferably prevented or reduced by keeping the material under tension.  The process also improves the dimensional stability of the textile material at elevated temperatures, e.g. 220-235 DEG C., reduces its tendency to creep under load in hot water and increases its tenacity.  Specifications 448,816, 448,817, 448,917, [all in Group IV], 687,414, 719,853, 719,860, 721,674, 726,900, 731,930, 748,712, [Group XX], and 758,442 are referred to.