| 摘要 |
An oxymethylene copolymer stabilised against heat is prepd. by heating the copolymer in an aq. medium contg. a bi-substd. cellulose ether. Pref. in the cellulose ether, (part of) the OH gps. in the anhydroglucose units are substd. by 2 different alkyl and hydroxyalkyl gps.; methyl ethers of cellulose contg. 2-4C hydroxyalkyl substits. are pref. The medium contains 0.01-10 wt.% w.r.t. the copolymer, of the cellulose ether deriv., and may contain a pH regulator. Pref., the medium is obtd. by addn. of water, the bi-substd. cellulose ether and opt. the pH regulator, to the same medium in which the copolymer has been synthesised. Treatment is at 130-165 deg.C.
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