| 摘要 |
1444789 Trioxan bulk copolymerization procedure HOECHST AG 20 Dec 1973 [23 Dec 1972] 59119/73 Heading C3P Trioxane-cyclic acetal copolymers are obtained by (a) forming a mixture of the monomers (at least 90% trioxan) and a cationic catalyst by mixing at 62‹ to 115‹ C. to give a homogeneous liquid mixture, (b) cooling the mixture sufficiently rapidly that solidification occurs without the liquid mixture becoming turbid, and (c) polymerizing the solid mixture thereby produced by heating to a temperature of 62‹ to 130‹ C. while maintaining it in the solid state. Step (b) may be carried out by contacting the mixture in the form of a thin film with cooled surfaces, or by contact with cooled extruders or kneaders. The catalyst may be diluted with gaseous or liquid diluents, while the resulting polymers may be stabilized by hydrolytic or thermal degradation and/or by the addition of stabilizers prior to use as a moulding composition. Examples refer to the copolymerization of trioxan with dioxolan, 1,3-dioxan, 1,3-dioxepane, or 4-methyl-1,3-dioxolan, in the presence of methylal as regulator and BF 3 .Et 2 O, HClO 4 , BF 3 or Pl 3 C.PF 6 as catalysts, using the specified technique, the process being carried out in a collapsible aluminium tube. |
