| 摘要 |
973,094. Wet spinning cellulose ester solutions. CELANESE CORPORATION OF AMERICA. Aug. 9, 1961 [Aug. 10, 1960], No. 28753/61. Drawings to Specification. Heading B5B. Filaments &c. are produced from a cellulose ester by a wet-spinning process in which both the spinning solution and the coagulant are initially virtually non-conducting liquids, wherein the electrical conductivity of the coagulant in the spinning zone is controlled so as to maitain positive the value of the formula C<SP>2</SP> - 7C + 10, where C is the conductivity in micromhos per centimetre cube at the temperature of the coagulant. Spent coagulant may be removed from the spinning zone, treated with an ion exchange resin to reduce its conductivity and then returned to the spinning zone. The coagulant may contain a non-ionic dispersing agent to assist in keeping suspended cellulose triacetate fines suspended, e.g. the higher fatty acid esters of polyalkylene glycols. Spent coagulant may be removed from the spinning zone, an electrolyte such as calcium acetate or sodium acetate added to raise its conductivity and, after allowing solids to settle out, supernatant liquor may be returned to the spinning zone. The spinning solution may comprise cellulose triacetate dissolved in a solvent comprising a major proportion ofmethylene chloride and the coagulant may comprise methylene chloride and methanol in which the methylene chloride concentration expressed as percentage by weight is equal to 75“ - TŒ5, where T is the temperature of the coagulant in degrees Centigrade. By maintaining the conductivity of the electrolyte at a value as specified, the deposition of solids on the inside of the spinning equipment and the resulting progressive deterioration in the quality of the filaments can be prevented. |
