Method for rapid drying of a polybenzazole fiber
AssigneeThe Dow Chemical Company
InventorsJang-hi Im, Chieh-Chun Chau, Hiroki Murase, Tooru Kitagawa, Takaharu Ichiryu
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Abstract
Polybenzazole fibers can be rapidly dried without undue fiber damage by exposing them to two or more set point temperatures with the temperatures being selected relative to the residual moisture content of the fiber. The residence time required for the fiber at each progressively higher temperature can be reduced if the fiber is always in full contact with the set point temperature of the drying equipment.
Claims31
A process to rapidly reduce the moisture content of a polybenzazole fiber from above 30 percent by weight to 12 percent by weight or less of the fiber while minimizing damage to the fiber, which comprises heating the fiber with at least two heating devices arranged in sequence, each having a set point temperature, wherein (a) each heating device has a set point temperature of at least about 140.degree. C., (b) each heating device after the first device has a set point temperature the same or above the set point temperature of the proceding device, (c) the set point temperature of at least one heating device is set higher than the preceding device, and (d) the set point temperatures of the heating devices are set relative to the residual moisture content of the fiber.
A process to rapidly dry a polybenzazole fiber that initially contains more than 30 percent RMC, while minimizing damage to said fiber, said process comprising the step of exposing said fiber sequentially to two or more temperatures, wherein said temperatures are selected relative to the percent residual moisture content of said fiber, and wherein each temperature selected is hotter than the previous temperature, and wherein the final percent residual moisture content of said fiber after it has been exposed to said two or more temperatures is about twelve percent or less.
Dependencies are inferred from the claim text.