Patent GB-666360-A (GB)
Title: Polysiloxane grease and methods of preparation
Filed: 1949-08-25
Abstract: A grease consists essentially of a liquid organo polysiloxane containing 1.9 to 2.5 organic radicals per silicon atom, the radicals being methyl and/or phenyl and/or tolyl radicals, and a minor amount of an alkali or alkaline earth metal salt of an alicyclic substituted fatty acid in which the fatty acid chain length is from 2 to 6 carbon atoms.  The substituted fatty acids specified are: cyclohexyl-acetic, -propionic, -butyric, -valeric and -caproic acids; a -butylcyclohexylacetic, g -ethylcyclohexylbutyric, a  - 4 - diterbutylcyclo-hexylbutyric, a  - 4 - disecbutylcyclohexylbutyric, 2 - cyclohexenecaproic, pentalaneacetic and cyclopentylvaleric acids. The metal salt may be dispersed in the siloxane by dissolving both in a common solvent and evaporating the latter, or the salt may be introduced directly into the siloxane and dissolved by heating and agitating the mixture, or the salt may be formed in situ by adding an aqueous solution of the metal hydroxide to a solution of the acid in the siloxane.  The amount of alkali added may be less than equal to or more than that required to react with the acid.  In examples greases are made from phenylmethylpolysiloxane, cyclohexylcaproic acid and (1, 2, 11, 12) lithium hydroxide; (4) barium hydroxide; (5) sodium hydroxide; (6) strontium hydroxide, and (7) potassium hydroxide; lithium hydroxide, cyclohexylcaproic acid, and (8) dimethylpolysiloxane; (9) tolylmethylpolysiloxane, and (10) a polysiloxane containing 90 mol. per cent p  phenylmethylsiloxane and 10 mol. per cent of trimethylsiloxane.ALSO:Pentalaneacetic acid <FORM:0666360/IV (b)/1> may be prepared by heating hydroxytetrahydro-nor-dicyclopentadiene with fused alkali metal hydroxide at 270 DEG  to 375 DEG  C.  U.S. Specification 2,560,242, which is referred to, discloses the preparation of a -4-ditertiarybutylcyclohexyl-butyric acid and a -4-di-secondarybutylcyclo-hexylbutyric acid.ALSO:A lubricating grease consists essentially of a liquid organo polysiloxane containing 1.9-2.5 organic radicles per silicon atom, the radicles being methyl and/or phenyl and/or tolyl radicles, and a minor amount of an alkali or alkaline earth metal salt of an alicyclic substituted fatty acid in which the fatty acid chain length is from 2 to 6 carbon atoms. The substituted fatty acids specified are: cyclohexyl -acetic, -propionic, -butyric, -valeric and -caproic acids; a-butylcyclohexylacetic, g -ethylcyclohexylbutyric, a-4-diterbutylcyclohexylbutyric, a-4-disecbutylcyclohexylbutyric, 2-cyclohexenecaproic, pentalaneacetic and cyclopentylvaleric acids. The metal salt may be dispersed in the siloxane by dissolving both in a common solvent and evaporating the latter, or the salt may be introduced directly into the siloxane and dissolved by heating and agitating the mixture, or the salt may be formed in situ by adding an aqueous solution of the metal hydroxide to a solution of the acid in the siloxane.  The amount of alkali added may be less than, equal to or more than that required to react with the acid.  In examples, greases are made from phenylmethylpolysiloxane, cyclohexylcaproic acid and (1, 2, 11, 12) lithium hydroxide, (4) barium hydroxide, (5) sodium hydroxide, (6) strontium hydroxide, and (7) potassium hydroxide; lithium hydroxide, cyclohexylcaproic acid and (8) dimethylpolysiloxane, (9) tolylmethylpolysiloxane and (10) a polysiloxane containing 90 mol per cent phenylmethylsiloxane and 10 mol per cent trimethylsiloxane.