Patent GB-572959-A (GB)
Title: Treatment of paper or textile fabrics
IPC: D21H17/19
Filed: 1943-02-15
Abstract: Paper and textile fabrics are impregnated or coated with polymerization products such as polyvinyl or polyacrylic compounds by exposing the materials to the vapour of one or more readily polymerizable compounds in the presence of persulphuric acid or a water-soluble persulphate and in the presence of a watersoluble oxy-acid of sulphur with reducing properties or a water-soluble salt of such acid.  The polymerizable compound may be a vinyl or vinylidene compound, e.g. acrylic acid, methacrylic acid, or an ester of one of these acids, or acrylonitrile, styrene, a vinyl ester or a vinyl ether.  The textile fabrics may be woven or knitted and may comprise fibres of wool, cotton, jute, regenerated cellulose, cellulose acetate, or synthetic linear polyamide.  The polymerizable compound should preferably have a high vapour pressure at temperatures below 100 DEG  C.  Methyl, ethyl, 2-ethylhexyl, octadecyl, b -ethoxyethyl and n-butyl methacrylate, and diallyl maleate are specified polymerizable compounds.  The treatment may be effected at 30-70 DEG  C.  The persulphuric acid or salt thereof may be applied by soaking the materials or impregnating them with a dilute aqueous solution of the reagent. Moisture is preferably present during the treatment with the vapour of polymerizable substance.  The vapour may be entrained in an oxygen-free gas such as carbon dioxide or nitrogen.  Water, alcohol, or other inert volatile liquid may be mixed with the compound being vaporized.  The salt of reducing properties may be a sulphite, hydrosulphite, sulphoxylate, pyrosulphite, bisulphite, or thiosulphate.  If sulphurous acid is used, it may be introduced by entraining a mixture of sulphur dioxide and water vapour with the vapour of the monomer in a carrier gas, or gaseous sulphur dioxide in admixture with a carrier gas may be passed through the paper or fabric which is moist with water.  When the conditions of treatment are such that only a small amount of polymer is formed on the fabric, the latter is given a soft feel.  Greater amounts of polymer give an oiled-silk appearance or give stiffened or delustred products.  The fabrics may be increased in weight by as much as 150 per cent.  Two or more treatments with the vapour of the monomer may be given.  In an example, cotton fabric is impregnated with a cold solution of about 1 per cent ammonium persulphate and 0.5 per cent sodium hydrosulphite in water.  The fabric is squeezed and then suspended in a chamber where it is exposed to the action of a current of methyl acrylate vapour and carbon dioxide.  In another example, cotton fabric impregnated with persulphate is exposed to a gaseous mixture of carbon dioxide, sulphur dioxide, water vapour, and methyl methacrylate vapour.  In other examples, woollen, rayon and nylon fabrics are treated.  In another example, absorbent paper is moistened with a dilute solution of ammonium persulphate and then exposed to the vapour of styrene mixed with sulphur dioxide and carbon dioxide. The treatment is repeated twice so that the increase in weight of the paper is 119 per cent.  Vapours of two or more monomers in admixture may be used so that a copolymer is formed on the materials.  Specification 559,787 is referred to.