| 摘要 |
PCT No. PCT/JP91/01089 Sec. 371 Date Mar. 30, 1992 Sec. 102(e) Date Mar. 30, 1992 PCT Filed Aug. 15, 1991 PCT Pub. No. WO92/03487 PCT Pub. Date Mar. 5, 1992.Cyclic polyoxymethylene having a number-average molecular weight of 500 to 5,000 is obtained by solid state cyclization reaction of an alkalidegradative linear oxymethylene homopolymer in the presence of a medium containing a cationic catalyst. The cyclization is effected at 10 DEG to 150 DEG C. for 1 to 500 minutes in an organic liquid medium. The reaction mixture obtained by the cyclization is treated with an alkaline medium to hydrolyze and remove away unreacted linear polyoxymethylene homopolymer, and isolate the cyclic polyoxymethylene. The product has a sharp molecular weight distribution and is useful as a resin improver.
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