Patent GB-688166-A (GB)
Title: A method of lubricating moving metallic parts
Inventor: FLETCHER HERBERT JAMES
Filed: 1951-01-02
Abstract: A lubricant comprises a liquid copolymeric siloxane having a degree of substitution greater than 2 and less than 3 organic radicals per silicon atom, the radicals being either (a) halogenated xenyl radicals having from 1 to 7 chlorine or bromine atoms, or (b) halogenated phenyl radicals having from 3 to 5 chlorine or bromine atoms and being present in such an amount that the ratio of halogen atoms to silicon atoms is from 0.05 to 3, the remaining organic radicals being selected from methyl and phenyl radicals so that at least 37 per cent of the total organic radicals are methyl radicals. The liquid copolymeric siloxanes may be used as such or compounded with a thickening agent to form a grease, provided that the grease contains at least 50 per cent of siloxane.  Suitable thickening agents are the alkali metal or alkaline earth metal salts of higher fatty acids or of alicyclic substituted fatty acids, wherein the fatty acid has a chain length of from 1 to 6 carbon atoms.  A number of such acids are specified, reference being made in this connection to Specification 666,360.  The general methods of preparation of these liquid copolymeric siloxanes and greases is given together with specific examples.  Specification 652,754 also is referred to.ALSO:A lubricant comprises a liquid co-polymeric siloxane having a p  degree of substition greater than 2 and less than 3 organic radicals per silicon atom and containing either (a) halogenated xenyl radicals having from 1 to 7 inclusive halogen atoms substituted therein, or (b) halogenated phenyl radicals having from 3 to 5 inclusive halogen atoms substituted therein, in both cases the halogen atoms being either chlorine or bromine and the halogenated radicals being present in such an amount that the ratio of halogen atoms to silicon atoms is from 0.05 to 3.  The other organic radicals, in both cases are either methyl or phenyl, and are selected in such a manner that at least 37 per cent of the total organic radicals are methyl radicals.  All the halogen atoms present are contained in the halogenated aryl radicals. These halogenated radicals may be substituted on Si atoms in a RSiO 3/2 , R2Sio or R3SiO 1/2 siloxane unit, the other radicals as stated above being methyl or phenyl.  The lubricants are particularly suitable for lubricating metallic bearing surfaces operating under high loads and at temperatures below -50 DEG C or above 150 DEG C. The liquid copolymeric siloxanes may be used as such or compounded with a thickening agent to form a grease, provided that the grease contains at least 50 per cent of siloxane.  Suitable thickening agents are the alkali metal or alkaline earth metal salts of higher fatty acids or of alicyclic substituted fatty acids wherein the fatty acid has a chain length of from 1 to 6 carbon atoms.  A number of such acids are specified, reference being made in this connection to Specification 666,360.  The general methods of preparation of these liquid copolymeric siloxanes and greases is given together with specific examples.  Specification 652,754 also is referred to.