Patent GB-687005-A (GB)
Title: Improvements in or relating to the production of artificial filaments and films having reduced swelling properties
IPC: D01F2/10
Filed: 1950-03-07
Abstract: A water-insoluble alkali-soluble polybasic acid-polyhydric alcohol linear condensation product containing residual free acid groups is incorporated into a film-forming substance having free hydroxyl groups during the manufacture of filaments, yarns, fibres, bristles, films and foils, and the so-formed products are treated, after their formation, with formaldehyde or a substance generating formaldehyde on heat treatment.  The film-forming substance may be regenerated cellulose, a cellulose derivative containing free hydroxyl groups, polyvinyl alcohol or a partially saponified polyvinyl acetal. Preferably the filaments, foils and the like are treated with formaldehyde in the presence of an acid catalyst, e.g. ammonium chloride.  Suitable condensation products are those from adipic acid and glycol or glycerine which are soluble in 4-10 per cent caustic soda.  They are prepared by heating equimolecular quantities of the reagents for 2-6 hours at 130-160 DEG  C. on an oil-bath until 90-95 per cent of the carboxyl groups are esterified (determined by the acid number).  The condensation product is preferably incorporated in the spinning solution, e.g. viscose, in the form of a 40-50 per cent solution in caustic soda.  The concentration of formaldehyde used is at most 10g. per litre.  The heat treatment is carried out at a temperature less than 90 DEG  C. and preferably between 80 DEG  and 90 DEG  C., complexes being formed in which the cellulose chains and the condensation product are joined by methylene bridges.  The materials after treatment undergo little or no deformation on washing.  In an example 20 c.c. of a 50 per cent solution in 6 per cent caustic soda of a glycerine-adipic acid condensation product is added to 10 litres of a viscose containing 6 per cent of caustic soda and 9 per cent of cellulose.  The viscose is matured to a salt point of 6 and spun into a bath containing 120g. of sulphuric acid, 250g. of sodium sulphate and 15g. of zinc sulphate per litre.  The filaments are stretched, washed, dried and desulphurized.  They are then impregnated with an aqueous solution containing 7g. of formaldehyde and 3.5g. of ammonium chloride per litre and washed at 80-85 DEG  C., causing the reaction to take place.  Specifications 601,694, 601,695, 601,696, [Group IV (c)], and 656,261 are referred to.ALSO:A water-insoluble alkali-soluble polybasic acid-polyhydric alcohol linear condensation product containing residual free acid groups is incorporated into a film-forming substance having free hydroxyl groups during the manufacture of filaments, yarns, fibres and like products, and the products are treated, after their formation, with formaldehyde or a substance generating formaldehyde on heat treatment.  The film-forming substance may be regenerated cellulose, a cellulose derivative containing free hydroxyl groups, polyvinyl alcohol or a partially saponified polyvinyl acetal. Preferably the filaments and the like are treated with formaldehyde in the presence of an acid catalyst, e.g. ammonium chloride. Suitable condensation products are those from adipic acid and glycol or glycerine which are soluble in 4 to 10 per cent caustic soda.  The concentration of formaldehyde used is at most 10 g. per litre.  The heat treatment is carried out at a temperature less than 90 DEG  C. and preferably between 80 and 90 DEG  C., complexes being formed in which the cellulose chains and the condensation product are joined by methylene bridges.  The materials after treatment undergo little or no deformation on washing.  In an example, a solution in caustic soda of a glycerine-adipic acid condensation product is added to viscose, which is spun into a bath containing sulphuric acid, sodium sulphate and zinc sulphate.  The filaments are stretched, washed, dried and desulphurized.  They are then impregnated with an aqueous solution containing 7 g. of formaldehyde and 3.5 g. of ammonium chloride per litre and washed at 80 DEG  to 85 DEG  C. causing the reaction to take place.  Specifications 601,694, 601,695, [both in Group IV (a)], 601,696 and 656,261 are referred to.