Patent GB-542659-A (GB)
Title: Improvements in the manufacture of stiffened fibrous materials
IPC: D06M23/14
Filed: 1941-06-19
Abstract: 542,659. Treating textiles &c. with liquids &c. ; wearing apparel; surgical splints &c. ; instep supports. FRANKFURTHER, - P. June 19, 1941, No. 10620/40. [Class 15 (ii)] [Also in Groups VI, VII and VIII] Fibrous materials or articles, having a stiffness at least equal to that of whalebone, celluloid stiffening bars, thin metal bars or stiffening wires, or of strongly stiffened bands such as starched or plaster bandages, and which lose their stiffness when heated but regain it upon cooling, are obtained by impregnating flexible fibrous materials or articles with a waterinsoluble, thermoplastic, natural or synthetic resin having a softening point above 40‹ C. in amounts of at least 50 per cent. of the weight of the materials to be impregnated, and subjecting the resin while free from solvent during or after the impregnation to the action of heat without the application of pressure or of a shaping operation. The treated materials may subsequently be shaped while hot, e.g. by bending, and they retain their shape and stiffness when cold. The resin may be a polyvinyl acetate or other polyvinyl compound. The heat treatment imparts greater stiffness upon cooling than is obtainable by impregnation alone, and the stiffness obtained is increased by raising the temperature of the treatment, the maximum stiffness being obtained when the resin has been heated at or above its softening temperature. The materials may subsequently be subjected to a hot pressing treatment. The resin may be applied in molten condition or as a solution in a volatile solvent or as an emulsion of such a solution in water or other non-solvent and it may be applied by immersion, brushing, or spraying. The degree of stiffness may be increased by rapidly cooling the impregnated material while still hot, e.g. by a blast of cold air, or by pressing in a cold press. Stiffness may be increased by subjecting the material to the action of formaldehyde, tannic acid or other substance which has a hardening action on the resin. Woven, knitted, or felted fabrics, or cords, threads, leather, or paper may be treated: Several layers of fabric may be united by sewing or other means before or after impregnation. The layers may be agglutinated by the resin during the treatment. Softening agents may be incorporated to improve the adhesive properties of the resin. Penetration of the resin may be enhanced by prior treatment of the material with a solvent for the resin or with a wetting agent. The concentration of the resin solution may be 15 per cent. or more. The elasticity of the resin may be increased by adding dibutyl phthalate, benzyl benzoate, or other softener to the solution, or by first treating the material with a dispersion of rubber. Knitted fabrics including those of artificial silk may be used as interlinings for stiffening garments. The treatment may be conducted so that portions of the material treated are rendered less stiff than others, e.g. the edges and ends of corset stays may be rendered less stiff than the rest. Parts to be rendered less stiff may be made of less permeable material, or may receive less of the resin solution or more of the softening agent, or may be heated at a lower temperature. The material may be subjected to operations such as sewing after the impregnation and before the final heating. A water-soluble plasticizer, e.g. triacetin may be incorporated to facilitate sewing or other working operation and it may subsequently be removed by washing. The stiffened articles, particularly when used as surgical bandages, may be porous to air or water and if necessary holes may be punched in the material. A resist of wax may be applied over certain areas so that they remain unaffected by the resin treatment and remain porous after removal of the resist, or the resin may be applied through a stencil. The process is applicable to the treatment or production of stiffeners for hat brims, hat decorations, stiffened frills, stiffeners for the front edges of collars, basket work, artificial flowers, belts, toys made wholly or in part of stiffened fabric such as dolls' heads, bandages, splints, or instep supports. A surgical bandage is made by dipping a strip of flannel in a solution of a mixture of medium and highviscosity polyvinyl acetate in acetone. The material is dried and then heated to 100‹ C. It is wound into a roll while still soft and then cooled. When it is to be applied to the body it is softened by gentle heating, and then cooled on the body. An instep support is made by impregnating a piece of felt, drying, heating, and then shaping while hot. Two or more layers of felt may be impregnated and then united. A layer of wool or cork may be secured to the upper surface of the felt instep support or between two or more of the layers of felt. An additional layer of impregnated felt or other fibrous material may be united to the under side of the support in the region of the arch.