Patent GB-491969-A (GB)
Title: Improvements relating to artificial textile materials, films, foils and the like
IPC: D01F2/28
Filed: 1937-03-15
Abstract: Filaments, ribbons, fabrics, films, and like materials having a basis of cellulose acetate or other cellulose ester or ether, containing a plasticizer or other substance soluble in a liquid which is a non-solvent for the cellulose derivative, are rendered more resilient by dissolving out at least a part of the plasticizer or other substance, and simultaneously or immediately thereafter impregnating the materials with a substance or mixture of substances which are capable of reacting to form a resinous condensation product, and heating the materials to effect the condensation.  The treated, materials have a high resistance to creasing, and their affinity for acid dyes and resistance to water are increased.  Removal of plasticizer and impregnation with the resin-forming substances may be effected in a single bath.  The solvent for the plasticizer may have a swelling action on the cellulose derivative.  The plasticizer may be an alkyl phthalate, benzyl acetate, an acetin, tribenzoyl glycerine, an aryl phosphate, or an alkyl tartrate.  Other readily removable substances which may be present in the cellulose derivative are ethyl lactate, diacetone alcohol, lactic acid, citric acid, alcohol or acetone soluble portions of resins such as rosin, shellac, and kauri.  Liquids which may be used for removing the plasticizer or other ingredient are methanol, ethanol, methylal, ethylal, methyl formate, methyl acetate, aqueous solutions of acetone, methyl ethyl ketone, or dioxane.  The synthetic resin components may be added in the form of an intermediate reaction product such as di-methylol urea.  Urea and formaldehyde may be used in the proportion of three molecules of urea to two of formaldehyde.  Other resin components are acetaldehyde, benzaldehyde, furfurol, and acrolein, and thiourea, dicyandiamide, guanidine, biuret, methyl urea and ethyl urea. Resins of the diphenylolpropane formaldehyde type may be formed in the materials.  Condensation may be effected by passing the materials through a heated atmosphere or over heated rolls.  After the drying step preparatory to the final heating the materials may be subjected to brushing, beating, or other treatment to remove resin-forming substances from the outside and to prevent the formation of a coating.  Similar treatment may be carried out after the final heating.  The materials may be scoured with a dilute alkaline solution.  In an example, cellulose acetate yarns containing dimethyl phthalate are woven into fabric which is then soaked in a methanol solution of a ureaformaldehyde reaction product.  This reaction product is obtained by adding caustic potash to a solution of urea and formaldehyde in methanol, heating for a few minutes, cooling, adding acetic anhydride, and before use, acidifying with sulphuric acid.  The reaction product may be formed in aqueous methanol, aqueous caustic soda being added before the heating, and acetic acid being added after heating and cooling.  The fabric is removed from the solution, dried in air, and heated to effect condensation of the resin components.  It is then passed through a fabric breaker. Effects such as embossing or crimping produced on the treated materials are more permanent. The polymerization or condensation may be localized. Specification 485,199 is referred to.  The Provisional Specification refers also to Specification 485,372.