Patent GB-496122-A (GB)
Title: Process for treating fibrous materials with coagulable substances and article produced thereby
IPC: D06M15/39
Filed: 1937-04-23
Abstract: <PICT:0496122/IV/1> Fibrous materials, such as yarns, textiles, leather and paper are treated to improve their appearance and durability with a coagulable liquid composition of a film-forming cellulosic or resinous substance are heated to decrease the viscosity of the composition and promote penetration thereof while avoiding substantial concentration, then heated to a higher temperature to concentrate the composition and increase its viscosity without completely drying it and/or the composition is gelled without completely drying it, and the concentrated and/or gelled cellulosic or resinous substance is then coagulated.  The yarns or textiles may be of cotton, flax, ramie or mixtures thereof with each other or with artificial filaments.  Glassine, rag and bond papers are suitable for treatment.  Preferably, the fibrous materials are first wetted with the dispersing agent of the composition.  Suitable compositions are solutions or dispersions of cellulose derivatives or of cellulose, or of natural or synthetic resins such as polyvinyl resins glyptal resins or urea resins.  Alkali-soluble cellulose ethers are preferably employed. The composition may also contain fillers, wetting agents, protective colloids, softening agents or dyestuffs. Fibrous sheet material 10 on a supply roll 11 passes through the nip of rolls 12, 13 of a slop padder, containing the finishing composition in bath 14, into a chamber 15 heated by coils 16 and then into a second chamber 18 heated to a higher temperature by coils 19 to concentrate the composition by evaporation of the dispersion medium.  Excessive drying of the material may be avoided by maintaining a partial pressure of dispersion medium in the chamber 18.  The material then passes to a bath 20 to coagulate the composition on the material.  The composition may be applied by means other than slop padding.  Conditions are adjusted in chamber 15 to prevent loss of dispersion medium either by keeping the chamber closed and allowing equilibrium to be attained between liquid or vapour, or by introducing vapour of the dispersion medium into chamber 15 through port 23 and withdrawing it through port 24.  The reduction in viscosity of the composition is thus obtained without substantial concentration thereof.  In place of chambers 15, 18 a series of rollers may be used for heating the material.  While the composition is in its lower state of viscosity it may be supported on a tentering frame and subjected to swinging to promote penetration of the material.  The composition is concentrated before coagulation until it contains preferably less than 50 per cent but not less than 15 per cent of the volatile dispersion medium.  Gelling of the composition may be brought about either by the concentration or by treatment, e.g. in the chamber 18 during concentration with gases or with p  suitable radiation, or with liquids containing a gelling reagent or suitable for extracting the dispersion medium from the composition to produce a gel.  The concentrated and/or gelled composition may be coagulated by heat or by suitable chemical reagents.  In examples: (1) bleached cotton sheeting is passed through a water mangle, and then through a two-bowl mangle where it is treated with a composition containing a cellulose ether dispersed in aqueous sodium hydroxide.  Thence it is passed over a series of rollers heated to about 40 DEG  C. to reduce the viscosity of the composition, and then over a second series of rollers heated to 50-70 DEG  C. to evaporate 1/2 -\ba3/4 of the water in the composition. The composition is then coagulated by means of sulphuric acid solution; (2) a grey cotton sheeting is treated with a water mangle and viscose containing talc is applied in a slop padder.  The treated textile is then heated to 45 DEG  C., e.g. in chamber 15 and the viscose then gelled by heating to 70 DEG  C., e.g. in chamber 18. While the gel is still wet, the sheeting then passes to vat 20 containing a solution of sodium sulphate and sulphuric acid to coagulate the viscose.  The usual treatments follow.  Specifications 312,909, [Class 96], 353,495, and 374,298, [Group VIII], are referred to.