Patent GB-673642-A (GB)
Title: Shrinkproofing of textile materials containing natural or regenerated cellulose
IPC: D06M15/423
Filed: 1950-12-01
Abstract: Methylol formamide is prepared by reacting 3 mols. of formaldehyde with 2 to 6 mols. of formaldehyde, the temperature not being allowed to exceed 55 DEG  C.  The initial pH of the formaldehyde should be adjusted to 10 to 12 with sodium or potassium carbonate.  The reaction requires about 1 hour for completion.  The product in aqueous solution may be used for stabilizing textile materials comprising wholly or substantially natural or regenerated cellulose against dimensional shrinkage and for improving their crease-resistance (see Group IV (c)).ALSO:Textile materials containing a substantial amount of natural or regenerated cellulose are treated with an aqueous solution having a pH not greater than 5.0 and containing a condensation catalyst having of itself, or giving rise to an acid having, a dissociation constant of not less than 1.76 X 10-4 at 25 DEG  C., and the reaction product of formaldehyde and formamide in the molar ratio of 3 formaldehyde to between 2 and 6 formamide, removing excess solution above a desired pick-up, and then drying and curing said treated material so freed of excess solution. The process stabilizes the textile material against substantial dimensional shrinkage under repeated laundry washings.  The term "textile material" is intended to cover filaments and fibres, staple and yarns at any stage in the production thereof, and also knitted, woven or felted fabrics as well as garments or other articles made from such fabrics.  The textile material may be 100 per cent regenerated cellulose or cotton, or a blend of regenerated cellulose and wool in which the wool does not exceed 80 per cent of the material, wool and cotton, viscose rayon and cellulose acetate, casein and cotton, casein and viscose rayon and regenerated cellulose and nylon.  Suitable catalysts are aluminium chloride, oxalic acid, diammonium hydrogen phosphate, hydrochloric acid, ammonium nitrate, ammonium chloride and zinc chloride, and these are employed in amounts of at least 4 grams per litre of solution.  The formamide and formaldehyde are reacted at pH 10-12 at a temperature not exceeding 55 DEG  C. (see Group IV (b)).  The textile material after impregnation and squeezing is dried at a temperature below approximately 212 DEG  F. and then cured at a temperature above 212 DEG  F.  The pH of the impregnating solution is preferably between 3.5 and 4.1.  In an example a viscose rayon-wool fabric with a warp consisting of 60 per cent spun viscose rayon and 40 per cent wool is impregnated with a solution containing 200 g. per litre of the product obtained by reacting 357 g. of 37.5 per cent formaldehyde with 163 g. of formamide at a temperature below 55 DEG  C.  The initial pH of the formaldehyde was adjusted to 10-12 with sodium or potassium carbonate.  The impregnating solution also contains 30 g/litre of aluminium chloride.  After impregnation the material is squeezed to 100 per cent pick-up, and dried at 180 DEG  F. to is original dimensions.  It is then cured at 300 DEG  F. for 6 minutes, soaped, rinsed and dried.