Patent GB-492271-A (GB)
Title: Improvements relating to artificial textile materials, films, ribbons and the like
IPC: C08L61/10
Filed: 1937-03-15
Abstract: Materials comprising cellulose derivative filaments, ribbons, films or the like, which are of hollow structure or contain closed cavities, or show under the microscope the characteristic pitted or fissured appearance of cellulose derivative materials delustred by hot aqueous media, or which possess a shell of higher density than the interior, are rendered highly resilient by impregnating the materials with a substance or mixture of substances which reacts in the materials under the influence of heat to produce a resinous water-insoluble condensation product, and heating to effect such reaction.  Instead of cellulose derivative materials, the materials treated may comprise regenerated cellulose filaments, ribbons, films, or the like which are of hollow structure or contain enclosed cavities.  The materials after treatment are rendered resistant to creasing, and more resistant to water, and their affinity for acid dyes is increased.  Effects such as crimping or embossing are more permanent.  The condensation of the resin components may be localized.  Cellulose derivative filaments of hollow structure may be obtained by dry spinning in such manner that rapid escape of volatile solvent produces the hollows.  The spinning solution may contain formaldehyde or other very volatile liquid or a dissolved gas such as ethyl chloride or acetylene.  Products having a shell of higher density than the core may be obtained by incorporating non-solvents such as xylene, and water in the spinning solution. Hollow filaments may be obtained by wet spinning using a hot coagulation bath which causes rapid evaporation of solvent constituents.  Films with hollows may be obtained by rapid extrusion on to a travelling support so that air is drawn in between the film and the support, or by sprinkling powder on to the support to provide nuclei for the formation of bubbles. Formed filaments or films of cellulose derivatives may be provided with fissures by subjecting them to delustring treatment with hot water, or soap solutions, or aqueous solutions of swelling agents. The resin components may be urea and formaldehyde.  Other aldehydes specified are acetaldehyde, benzaldehyde, furfurol, and acrolein.  Instead of urea there may be used thiourea, dicyandiamide, guanidine, biuret, phenols, diphenylol-propane. The resin components may be applied in solution in water or organic solvents. Condensation or polymerization of the resin components is affected by passing the materials through a heated atmosphere or over heated rolls.  The materials may be subjected to brushing, beating, or other treatment to remove resin material adhering to the outside of the materials, before or after the final heating.  In examples, cellulose acetate yarns containing hollows, or fissures, or having a shell of higher density than the core, are woven into fabrics which are then soaked in a methanol solution of a urea-formaldehyde resin obtained by mixing urea with formaldehyde in methanol, adding caustic potash, heating and then cooling rapidly, adding acetic anhydride, and then acidifying by adding a small quantity of sulphuric acid.  The material is then dried and heated.  Specifications 485,199 and 485,372 are referred to.