| 摘要 |
Process for prepn. of opt. alkoxylated (OR) polyorganosiloxane resins (POS), by non-hydrolytic condensn. at least between alkoxysilyl units (Mo1) and halogenosilyl units (Mo2) on the same silane (homocondensn.) or on different silanes (heterocondensation), in the presence of a Lewis acid type catalyst, the condensn. producing IDENTICAL Si - O - Si IDENTICAL bonds and coproducts XR where X = halogen, wherein (I) the POS contains siloxy units D (SiO2/2), T (SiO3/2) and/or Q (SiO4/2) and opt. M (SiO1/2), (ii) the catalyst is chosen from metal cpds. of a metal of gp. IIIB, IVB or VB and (iii) the reaction temp. and the initial ratio OR/X are adjusted such that condensn. takes place virtually exclusively between the units Mo1 and Mo2 to the virtual exclusion of parasitic condensn. between two alkoxy gps. OR with the formation of R2O as by-product. Pref. the metal cpds. are esp. carboxylates, halides, (cyclo)alkyl halides, alkoxides, oxyhalides or mixts. of these, esp. a cpd. chosen from TiCl4, TiBr4, (PhO)2, TiCl2, CpTiCl3, Cp2VCl2, VCl3, VOCl3, ZrCl4, ZrBr4, Zr(OEt)4, Cp2ZrCl2, Cp2ZrHCl, Cp2ZrMe2, (C5Me5)2, ZrCl2, (C5Me5)ZrCl3, CpZrCl3/2-tetrahydrofuran, HfCl4, NbCl5 or mixts. of these, Zr derivs. being partic. pref. (Cp = cyclopentadienyl). The reaction temp. is pref. 70-210, (100-180), (130-150) deg.C. The reaction temp. and catalyst are pref. chosen such that the ave. level of R2O formed is less than 10 wt.%, pref. less than 5 wt.% and esp. less than 4 wt.% w.r.t. the coproduct RX. The reaction is pref. carried out in a sealed reactor with means for venting gases formed during the reaction. |
