Organopolysiloxane composition having improved heat stability

Abstract

The reaction product of a cerium salt of an organic carboxylic acid which is soluble in an aromatic hydrocarbon or a chlorinated hydrocarbon solvent with an alkali metal siloxanolate having an average of at least three siloxane units per molecule is employed as a heat stability additive in silicone fluids and silicone elastomers.

That which is claimed is: 
     
       1. A method for improving the heat stability of organosilicon compounds in which the substituents on the silicon are monovalent hydrocarbon or halogenated monovalent hydrocarbon radicals having 1 to 30 carbon atoms comprising adding thereto the reaction product of a cerium salt of an organic carboxylic acid which is soluble in an aromatic hydrocarbon solvent or a chlorinated hydrocarbon solvent with an alkali metal siloxanolate having an average of at least three organosiloxane units per molecule and in which the substituents on the silicon are methyl, ethyl, phenyl, vinyl or 3,3,3-trifluoropropyl. 
     
     
       2. The method of claim 1 wherein the organosilicon compound is an organosiloxane fluid or an organosiloxane elastomer. 
     
     
       3. The method of claim 1 wherein the cerium salt of an organic carboxylic acid is cerium 2-ethylhexoate or cerium naphthoate. 
     
     
       4. The method of claim 1 wherein the alkali metal siloxanolate is potassium dimethylsiloxanolate, sodium dimethylsiloxanolate, potassium methylphenylsiloxanolate or sodium methylphenylsiloxanolate. 
     
     
       5. The method of claim 1 wherein the alkali metal siloxanolate is an essentially linear diorganosiloxane wherein the organic radicals bonded to silicon are selected from the group consisting of methyl, ethyl, phenyl, vinyl and 3,3,3-trifluoropropyl, one of the endblocking units being an alkali metal siloxanolate unit and the other endblocking unit being a triorganosiloxy unit wherein the organic substituents are as above defined. 
     
     
       6. The method of claim 1 wherein the reaction is carried forward in an aromatic hydrocarbon solvent or a chlorinated hydrocarbon solvent. 
     
     
       7. The method of claim 1 wherein the reaction is carried forward at reflux temperature of the mixture. 
     
     
       8. The method of claim 1 wherein the ratio of the alkali metal siloxanolate to the cerium salt of an organic carboxylic acid employed in the reaction is such that there is 1 to 5 alkali metal siloxanolate units per cerium atom present. 
     
     
       9. A heat stabilized organosilicon compound consisting essentially of an organosiloxane fluid or an organosiloxane elastomer in which fluid or elastomer the substituents on the silicon are monovalent hydrocarbon or monovalent halohydrocarbon radicals of 1 to 30 carbon atoms containing as an additive, 0.5 to 5 percent by weight of the compound of a cerium siloxanolate in which siloxanolate the substituents on the silicon are methyl, ethyl, phenyl, vinyl or 3,3,3-trifluoropropyl. 
     
     
       10. The heat stabilized organosilicon compound of claim 9 wherein the additive is prepared by reacting a cerium salt of an organic carboxylic acid which is soluble in aromatic hydrocarbon solvents or chlorinated hydrocarbon solvents with a potassium or sodium siloxanolate.