Process for preparing organosilicon materials

摘要

A cured rubber is obtained spontaneously upon mixing (A) a hydroxy-terminated siloxane of the formula , (B) a silane of the formula R1bSi(ON=X)4-b in amount such that there is at least one ON=X radical per sibonded OH group in the siloxane, (C) a carboxylic acid anhydride of the formula AcOAc in amount such that there is at least 0.66 mol. of the anhydride per ON=X radical and (D) MgO in amount such that there is at least 0.33 mol. of MgO per ON=X radical in (B), in which components each X is a divalent radical of the formula in which R11 is a divalent hydrocarbon (h.c.) or halohydrocarbon radical, R is a saturated or unsaturated monovalent h.c. or halo-h.c. radical, R1 is H, R or a cyanoalkyl radical, a has an average value of from 1.9 to 2.1, b is 0 or 1 and Ac is a saturated aliphatic monoacyl radical derived from a carboxylic acid containing at lesat 2 C atoms. Silanes (B) are described in the parent Specification. Components (C) specified are isobutyric, acetic, hexoic, 2-ethylhexoic, octanoic, stearic and acetic butyric anhydrides. In modifications, an oxime-terminated di-organosiloxane is substituted (1) for silane (B), and (2) for components (A) and (B), but in these cases the reaction must be effected in the presence of moisture. The reaction can be effected at elevated temperatures or, if desired, in the presence of condensation catalysts. The compositions may also contain resinous siloxanes, plasticizing siloxanes, fillers and conventional additives. Examples are given.