| 摘要 |
PURPOSE:To uniformly disperse lubricant by a method wherein the rotational frequency of a mold is controlled within the specified range at the early stage of polymerization and, after that, gradually raised in the specified period of time to the specified rotational frequency and, after that, said rotational frequency is held until the polymerization completes. CONSTITUTION:When polymerizable lactam solution, which is prepared by dispersing lubricant, anionic polymerization catalyst and polymerization cocatalyst and the like in anhydrous omega-lactam, is poured in a centrifugal mold, which is preheated to 140-180 deg.C, so as to manufacture cast nylon pipe by polymerizing the lactam solution under the condition that the mold is being rotated. In that case, the rotational frequency of the mold at the early stage of polymerization is held at 100-300rpm. Next, the rotational frequency of the mold is gradually raised in 15-60 seconds to 500-900rpm. After that, the rotational frequency is held unchanged until the polymerization completes. Thus, the lubricant is uniformly dispersed in the cast nylon pipe and, at the same time, fine bubbles can be prevented from generating. |
