Volatile siloxanes, particularly those of a cyclic nature, are removed from high viscosity silicone polymers and high viscosity silicone compositions by evaporation in a short path evaporator.

Disclosed is a composition comprising a silicon-containing compound represented by the general formula (1) mentioned in the description of the present application, at least one compound of the general formula (2-1) or (2-2) in which m is an integer of 3 or greater mentioned in the description of the present application, and optionally a compound represented by the general formula (3). The total amount of the silicon-containing compound of the general formula (2-1) or (2-2) in which m is an integer of 3 or greater is more than 0 ppm and 46,000 ppm or less based on the total weight of the silicon-containing compounds of the general formulas (1), (2-1), (2-2), and (3). The composition is used for producing a polyimide precursor obtained by copolymerizing a silicon-containing compound, tetracarboxylic dianhydride, and diamine.

Disclosed is a composition comprising a silicon-containing compound represented by the general formula (1) mentioned in the description of the present application, at least one compound of the general formula (2-1) or (2-2) in which m is an integer of 3 or greater mentioned in the description of the present application, and optionally a compound represented by the general formula (3). The total amount of the silicon-containing compound of the general formula (2-1) or (2-2) in which m is an integer of 3 or greater is more than 0 ppm and 46,000 ppm or less based on the total weight of the silicon-containing compounds of the general formulas (1), (2-1), (2-2), and (3). The composition is used for producing a polyimide precursor obtained by copolymerizing a silicon-containing compound, tetracarboxylic dianhydride, and diamine.

Fluids incorporated into intraocular lenses and their methods of use. In some embodiments the fluids are silicone oils, and in some embodiments they are used in accommodating intraocular lenses.

Fluids incorporated into intraocular lenses and their methods of use. In some embodiments the fluids are silicone oils, and in some embodiments they are used in accommodating intraocular lenses.

Processes are described for purifying acidic, preferably superacidic, in particular trifluoromethanesulfonic acid-acidified, end-equilibrated acetoxysiloxanes, wherein the acidic, preferably superacidic, in particular trifluoromethanesulfonic acid-acidified, acetic anhydride-containing and optionally acetic acid-containing equilibrated, preferably end-equilibrated acetoxysiloxane, which is optionally dissolved in an inert solvent, is contacted with a base, the precipitate is filtered off thereafter and then the filtrate obtained is optionally purified by distillation.

An organic polysilane, which can produce signals respectively derived from a SiO bond, an alkoxy group and a hydroxy group at levels equal to or lower than the detection limits in .sup.29Si and .sup.13C CP/MAS NMR analysis, can be produced by a method which includes: polymerizing an organic dihalosilane in an aprotic solvent in the presence of an alkali metal and/or an alkali earth metal to produce a mixture containing an organic polysilane having a terminal halogeno group; adding a solution containing an organic lithium compound and an aprotic polar solvent to the mixture to inactivate the organic polysilane having the terminal halogeno group; and then adding a protic polar solvent to the resultant mixture to deactivate the alkali metal and/or the alkali earth metal.

An organic polysilane, which can produce signals respectively derived from a SiO bond, an alkoxy group and a hydroxy group at levels equal to or lower than the detection limits in .sup.29Si and .sup.13C CP/MAS NMR analysis, can be produced by a method which includes: polymerizing an organic dihalosilane in an aprotic solvent in the presence of an alkali metal and/or an alkali earth metal to produce a mixture containing an organic polysilane having a terminal halogeno group; adding a solution containing an organic lithium compound and an aprotic polar solvent to the mixture to inactivate the organic polysilane having the terminal halogeno group; and then adding a protic polar solvent to the resultant mixture to deactivate the alkali metal and/or the alkali earth metal.

A method for preparing organopolysiloxane resins, including the steps below: (1) using an alkoxysilane, a capping agent and an acidic compound as raw materials; (2) mixing all the raw materials uniformly, and the capping agent, the alkoxysilane and the acidic compound have a mole ratio from 0 to 40:1:0.2 to 5; (3) performing a polycondensation reaction at a temperature of 40-150 C. in 2-20 h; (4) adjusting the reaction product to neutral, and obtaining a product of organopolysiloxane resin after purification. Preparation of organopolysiloxane resins with the present application method has benefits on less environmental pollution, low energy consumption, efficient productivity, high yield of silicone resin with excellent performance.

A method for preparing organopolysiloxane resins, including the steps below: (1) using an alkoxysilane, a capping agent and an acidic compound as raw materials; (2) mixing all the raw materials uniformly, and the capping agent, the alkoxysilane and the acidic compound have a mole ratio from 0 to 40:1:0.2 to 5; (3) performing a polycondensation reaction at a temperature of 40-150 C. in 2-20 h; (4) adjusting the reaction product to neutral, and obtaining a product of organopolysiloxane resin after purification. Preparation of organopolysiloxane resins with the present application method has benefits on less environmental pollution, low energy consumption, efficient productivity, high yield of silicone resin with excellent performance.