Patent GB-603944-A (GB)
Title: Fabrics suitable for use as insect-screens
IPC: D03D15/00
Filed: 1945-11-06
Abstract: An open mesh woven fabric suitable for insect screens comprises high tenacity heavy denier threads of a cellulose derivative or of regenerated cellulose coated with at least their own weight of a derivative of cellulose of low water absorption.  The heavy denier thread may be of cellulose acetate or other organic ester of cellulose and the ester may be saponified by any known saponifying agent if desired.  It may be a monofil, a multifilament yarn, or an association of several multifilament yarns.  Stretching to give high tenacity may be carried out simultaneously with or after spinning. The thread prior to coating should be of 250-500 denier or even more. Suitable low water absorption cellulose derivatives are ethyl celluloses of 41-55 per cent ethoxy content, cellulose propionates of 54-67 per cent combined propionic acid, or mixed organic acid esters such as cellulose acetate - propionate and cellulose acetate-butyrate.  The coating is built up to the required weight in a series of operations each applying the derivative in a volatile solvent such as benzene or a mixture of benzene and acetone, the solvent being evaporated off before the application of the next layer.  The solution of the derivative may contain 5-15 per cent by weight.  Ultra-violet proofing agents such as the bisulphates of quinine, quinidine, and cinchonine, and the dihydrochlorides of quinine and cinchonine may be incorporated in the coating solution in amounts from 0.1-5 per cent on the weight of the cellulose derivative.  If desired, these compounds may be present only in the outer layers.  Dyed fabrics may be produced by dyeing at any convenient stage in the process.  In an example a yarn of 480 denier is produced by doubling together four ends of a cellulose acetate yarn containing 120 filaments, stretched to 1000 per cent of its original length and having a denier of 120.  The yarn is then drawn through a 7 per cent solution of ethyl cellulose of 40 per cent ethoxy content in benzene and then through a drying tower at 135 DEG F., the length of path in the tower being 6 feet.  Seven applications are made, giving a coating equal in weight to the yarn.ALSO:An open-mesh woven fabric suitable for insect screens comprises high tenacity heavy denier threads of a cellulose derivative or of regenerated cellulose coated with at least their own weight of a derivative of cellulose of low water absorption.  The heavy denier thread may be of cellulose acetate or other organic ester of cellulose and the ester may be saponified by any known saponifying agent if desired.  It may be a monofil, a multifilament yarn, or an association of several multifilament yarns.  Stretching to give high tenacity may be carried out simultaneously with or after spinning. The thread prior to coating should be of 250-500 denior or even more. Suitable low water absorption cellulose derivatives are ethyl celluloses of 41-55 per cent ethoxy content, cellulose propionates of 54-67 per cent combined propionic acid, or mixed organic acid esters such as cellulose acetate-propionate and cellulose acetate-butyrate. The coating is built up to the required weight in a series of operations each applying the derivative in a volatile solvent, such as benzene or a mixture of benzene and acetone, the solvent being evaporated off before the application of the next layer.  The solution of the derivative may contain 5-15 per cent by weight. Ultraviolet proofing agents such as the bisulphates of quinine, quinidine, and cinchronine, and the dihydrochlorides of quinine and cinchonine may be incorporated in the coating solution in amounts from 0.5-5 per cent on the weight of the cellulose derivative.  If desired, these compounds may be present only in the outer layers. Dyed fabrics may be produced by dyeing at any convenient stage in the process.  In an example a yarn of 480 denier is produced by doubling together four ends of a cellulose acetate yarn containing 120 filaments, stretched to 1000 per cent of its original length and having a denier of 120.  The yarn is then drawn through a 7 per cent solution of ethyl cellulose of 48 per cent ethoxy content in benzene and then through a drying tower at 135 DEG  F., the length of path in the tower being 6 feet.  Seven applications are made giving a coating equal in weight to the yarn.