Patent GB-808474-A (GB)
Title: Lubricating grease compositions
Filed: 1957-08-26
Abstract: A lubricating grease comprises a lubricating oil gelled with an inorganic gelling agent and a minor proportion of a polymerized lactam of a monoaminomonocarboxylic acid having a chain of at least five carbon atoms between carboxyl and amino groups, which polymer acts as a water-repellent.  The oil may be mineral oil such as a refined, semi-refined or unrefined paraffinic, naphthenic or asphaltic based oil with a viscosity of 50-4000 s.u.s. at 100 DEG  F. or a blend of such oils, or a synthetic oil such as an aliphatic diester of a dicarboxylic acid, e.g. dioctylphthalate, bis-(2-ethylhexyl) sebacate, or bis-(3,5,5-trimethylhexyl) sebacate, an ester of phosphoric or silicic acid, e.g. tritolyl phosphate or tetrakis-(2-ethylhexyl) silicate, a halocarbon oil, e.g. a fluorocarbon oil distilling above 200 DEG  C. or a silicone oil, e.g. one produced by the hydrolysis of a compound of the formula R2SiX2, where R is lower alkyl and X halogen or alkoxy which may be mixed with up to 25 mol. per cent of RSiX3 or RSiX3 and R3SiX; a list of suitable compounds and mixtures is given. The silicone oil used may have a viscosity of 25-3000 s.u.s. at 100 DEG  F., examples being dimethylsilicone polymer, phenylmethylsilicone polymer and chlorophenylmethylsilicone polymer.  The gelling agent is an inorganic colloid of amorphous or crystalline structure preferably as an aerogel, e.g. silica, alumina, magnesia, ferric oxide, nickel sulphide and mixtures thereof or a clay such as Georgia clay, attapulgite, Wyoming bentonite or hectorite.  The colloid may alternatively be incorporated by solvent transfer from water either directly using a surface-active agent or indirectly by first displacing the water with acetone or an alcohol and then displacing this with the oil.  Amounts of 2-20 per cent by weight of the whole composition of the gelling agent may be used.  Clays are preferably acidtreated with 2-10 per cent by weight of the clay of phosphoric, nitric or sulphuric acid.  The lactam is added as a monomer to the gelling agent at any stage before or after incorporation in the oil and polymerized by heating the composition to 100-500 DEG  F. for 1-48 hours to give a polymer of molecular weight no less than 500. Suitable lactams include cyclohexanone isoxime, the products of conversion or rearrangement of 2-, 3- or 4-methylcyclohexanone oxime or of 2-methylcycloheptanone isoxime, cycloheptanone isoxime, 2 - ethylcyclohexanone isoxime, cyclo-octanone isoxime, epsilon-caprolactam and the homologous eight-membered ring lactams such as suberone isoxime.  Amounts of 5-250 per cent by weight of the gelling agent may be used.ALSO:A composition used as a lubricating grease comprises a lubricating oil gelled to a grease consistency with an inorganic gelling agent and a minor proportion of a polymerized lactam of a monoamino-monocarboxylic acid having a chain of at least 5 carbon atoms between the amino and carboxyl groups. The lactam is added to the gelling agent at any convenient stage before or after incorporation in the oil and is polymerized by heating the composition to 100-500 DEG  F. for 1-48 hours to give a polymer of molecular weight not less than 500.  Suitable lactams include cyclohexanone isoxime, the products of rearrangement or conversion of 2-, 3- or 4-methylcyclohexanone oxime, cycloheptanone isoxime, the products of rearrangement of 2-methylcycloheptanone isoxime, 2-ethylcycloheptanone oxime, cyclooctanone isoxime, epsilon-caprolactam and the homologous eight - membered lactams such as suberone isoxime.  Preferably the ring contains no more than 14 members.  Amounts of 5-250 per cent by weight of the gelling agent may be used.  The gelling agent, used in amounts of 2-20 per cent by weight of the whole composition, may be colloidal, silica, alumina, magnesia, ferric oxide or nickel sulphide or a clay, which may be acid treated.  Oils specified are silicone oils, mineral oils, aliphatic diesters of dicarboxylic acids, esters of phosphoric or silicic acid and halocarbon oils.  The silicone oils suitable for use are those obtained by the hydrolysis and condensation of compounds of the formula R2SiX2, where R is lower alkyl and X is a hydrolysable halogen or alkoxy group or a mixture of alkylated silicon compounds containing at least 75 mol. per cent of the above dialkyl compounds with monoalkyl compounds of the formula RSiX3 or a mixture of monoalkyl and trialkyl compounds (R3SiX), generally the mixture having a composition corresponding to R4-zSiXz, where z is between 2.25 and 1.5.  Suitable dialkyl silicon compounds include dimethyl-, methyl ethyl-, diethyl- and methyl propyl-silicon dichlorides, dimethyl- and diethyl-silicon dibromides, dimethyl-dimethoxy-silicon and diethyl- and dimethyl-diethoxy-silicons.  The products preferably have between 1.75 and 4 carbon atoms per silicon atom, they should be high boiling liquids having a viscosity at 100 DEG  F. of 25-3500 s.s.u. Chlorinated and fluorinated silicones can also be used. Particularly useful polymers are dimethyl-, phenylmethyl- and chlorophenylmethyl-silicones.