Verfahren zur Herstellung einer synthetischen Acrylfaser

摘要

1,230,392. Wet-spinning acrylic filaments having non-circular cross-sections. JAPAN EXLAN CO. Ltd. 25 June, 1968 [28 June, 1967], No. 30328/68. Heading B5B. Acrylonitrile filaments of non-circular crosssection having an R F value of from 1À6 to 9À0 are produced by extruding a solution in a concentrated aqueous solution of an inorganic salt or salts of a polyacrylonitrile or of a copolymer of acrylonitrile with at least one ethylenically unsaturated monomer, which copolymer contains at least 50% by weight of acrylonitrile units, through a non-metallic spinneret formed from an inert material such as a synthetic resin, said material having a conductivity not exceeding 5Î10-3 cal. cm.-1 sec.-1 deg.-1 into an aqueous coagulating bath, the spinneret being provided with orifices of non-circular crosssection in which the ratio of the length of the long axis of the cross-section of the orifice to the length of the short axis thereof is 2 to 9, the temperature of the coagulating bath not exceeding 10‹ C. and that of the spinning solution being at least 30‹ C. higher than that of the coagulating bath and the "jet drafting" ratio S J on extrusion satisfying the relationship 4 # R. J S J in which S J is defined as the ratio of the linear speed of travel of the coagulated filaments as they travel over and in contact with the first godet they meet after leaving the coagulating bath to the average linear velocity of the spinning solution passing through the orifice. The spinning may be carried out under conditions which satisfy the relationship R F = 0À4 R J .S J in which R F is the ratio of the long axis of the filament cross-section to the short axis thereof. The value of R F may be 2 to 6. The inorganic salt may be ammonium, sodium, potassium or calcium thiocyanate or zinc or calcium chloride or perchlorate. The spinneret may be made of a synthetic resin which does not exhibit thermal deformation until it is heated to 70‹ C. or above and which has a bonding strength of at least 700 kg./cm.2 when measured by ASTM methods D648 and D790 respectively. The spinneret may be made of a paper reinforced phenolic resin or an epoxy resin. In the two examples the spinning solution is prepared by dissolving a copolymer consisting of 91% by weight of acrylonitrile and 9% by weight of methyl acrylate in a 44% aqueous solution of sodium thiocyanate, the polymer concentration in the spinning solution being 11À3%.