Patent GB-689836-A (GB)
Title: Improved lubricating grease compositions
Filed: 1949-11-11
Abstract: A lubricating grease composition (see Group III) comprises a lubricating oil, a non-polymeric thickening agent which is an alkali metal salt of an organic acid, and a small proportion of a partially saponified polymeric compound, i.e. a polymeric compound containing both saponifiable groups and saponified groups, the saponified groups being those that may be produced by reacting the unsaponified polymeric compound with a metal oxide or hydroxide. Saponifiable groups which may be present in the partially saponified polymeric compound are carboxyl or esterified carboxyl groups, or their sulphur or selenium analogues, or cyano groups, while the saponified groups may contain sodium, potassium, lithium, calcium, barium or strontium. Suitable monomers for forming the polymeric compound to be partially saponified include (i) acrylic acid, methacrylic acid, higher homologues and other substituted products of acrylic acid, particularly amyl, octyl, dodecyl, hexadecyl and octadecyl acrylates and methacrylates, and (ii) amyl, dodecyl and octadecyl esters of alpha methyl crotonic acid, but general formul  of other classes of monomers including substituted vinyl benzoic acid, are given.  The monomers mentioned under (i) and related materials may be copolymerized with olefinic compounds such as styrene, butadiene, vinyl chloride, vinylidene chloride, tetrafluoroethylene, chlorotrifluoroethylene, ethylene, chlorinated styrene, beta-pinene, isobutylene, isoprene, acrylonitrile, vinyl acetate, chloroprene and maleic anhydride. Another polymeric compound which may be partially saponified is soya bean oil-modified pentaerythritol-pyromellitic acid alkyd resin.  In forming the partially saponified polymeric compounds, part of the saponifiable monomer may be saponified first and then copolymerized with unsaponified monomer, or the unsaponified monomer may first be polymerized and then partially saponified. The lubricating grease composition may be prepared by adding fatty acid to the lubricating oil, saponifying the fatty acid with alkali to produce the thickening agent, and then adding a mineral oil concentrate of the partially saponified polymeric compound. Alternatively, the unsaponified polymeric compound may be saponified in the lubricating oil at the same time as the fatty acid. Preparation of partial potassium salt of polyoctyl methacrylate. 0.5 gms. of solid potassium hydroxide is heated with 10 gms. of polyoctyl methacrylate (molecular weight about 10,000) in mineral oil solution. Preparation of partial metal salts of polycetyl methacrylate copolymer.-A small amount of solid sodium hydroxide, potassium hydroxide, calcium hydroxide or barium hydroxide octahydrate is heated with an alkyl methacrylate copolymer (molecular weight of about 20,000 and prepared from the mixture of alcohols, consisting predominantly of cetyl alcohol, obtained by the reduction of coconut oil fatty acids) in mineral oil solution.  Preparation of partial metal salts of polylauryl methacrylate copolymer.-A small amount of solid potassium hydroxide or lithium hydroxide is heated with an alkyl methacrylate copolymer (molecular weight about 20,000 and prepared from commercial lauryl alcohol) in mineral oil solution. Preparation of partial lithium salt of soya bean oil-modified pentaerythritol-pyromellitic acid alkyd resin.-Soya bean oil and pentaerythritol are heated together in presence of a small amount of sodium hydroxide and the mixture is cooled.  The cooled mixture is heated with pyromellitic anhydride and cooled again.  A mineral oil solution of the product is heated with a small amount of lithium hydroxide monohydrate.ALSO:A lubricating grease composition, comprising a lubricating oil and a non-polymeric thickening agent which is an alkali metal salt of an organic acid, has its resistance to emulsification in water increased by the addition of a small proportion of a partially saponified polymeric compound i.e. a polymeric compound containing both saponifiable groups and saponified groups, the saponified groups being those that may be produced by reacting the unsaponified polymeric compound with a metal oxide or hydroxide.  The lubricating oil may be a mineral oil or a synthetic oil, for example hydrocarbon lubricating oil derived from coal or an alkylene oxide polymer such as a polypropylene oxide polymer.  The non-polymeric thickening agent may be a substance of formula RXM where R is an aliphatic hydrocarbon group or an aralkyl group of 10-30 carbon atoms, which may contain substituents such as chlorine or bromine atoms or hydroxyl, etherified hydroxyl or mercapto groups, X is a carboxy, phosphonyl, sulphonyl or sulphate group and M is an alkali metal. Thus the thickening agent may be an alkali metal salt, for example sodium, potassium or lithium salt, of lauric, myristic, palmitic, stearic, oleic, arachidic, melissic, phenylacetic, cetyl benzoic, cetane sulphonic, dodecylbenzene sulphonic, dodecane phosphonic or lauryl sulphuric acid or an alkali metal salt of acids resulting from the oxidation of petroleum products, particularly petroleum waxes.  Saponifiable groups which may be present in the partially saponified polymeric compound are carboxyl or esterified carboxyl groups, or their sulphur or selenium analogues, or cyano groups, while the saponified groups may contain sodium, potassium, lithium, calcium, barium or strontium. Suitable monomers for forming (see Group IV(a)) the polymeric compound to be partially saponified include (i) acrylic acid, methacrylic acid, higher homologues and other substituted products of acrylic acid, particularly amply, octyl, dodecyl, hexadecyl and octadecyl acrylates and methacrylates, and (ii) p  amyl, dodecyl and octadecyl esters of alpha methyl crotonic acid, but general formulae of other classes of monomers are given.  The monomers mentioned under (i) and related materials may be copolymerized with olefinic compounds such as styrene, butadiene, vinyl chloride, vinylidene chloride, tetrafluorethylene, chlorotrifluorethylene, ethylene, chlorinated styrene, beta-pinene, isobutylene, isoprene, acrylonitrile, vinyl acetate, chloroprene and maleic anhydride.  Other polymeric compounds which may be partially saponified are cellulose derivatives, such as carboxy methyl cellulose which has been esterified with lauryl alcohol, and soyabean oil-modified pentaerythritol - pyromellitic acid alkyd resin (see Group IV(a)).  In forming the partially saponified polymeric compounds, part of the saponifiable monomer may be saponified first and then copolymerized with unsaponified monomer, or the unsaponified monomer may first be polymerized and then partially saponified.  The lubricating grease composition may be prepared by adding fatty acid to the lubricating oil, saponifying the fatty acid with alkali to produce the thickening agent, and then adding a mineral oil concentrate of the partially saponified polymeric compound. Alternatively, the unsaponified polymeric compound may be saponified in the lubricating oil at the same time as the fatty acid.  The lubricating grease composition may contain additional ingredients such as metal salts of organic acids of low molecular weight such as acetic acid, dyes, butene polymers, fillers, oxidation inhibitors, extreme pressure agents and corrosion inhibitors.  In the examples, lubricating grease compositions are described consisting of mineral lubricating oil, sodium stearate prepared from commercial stearic acid and one of the following: partial potassium salt of polyoctyl methacrylate, partial potassium, calcium, barium or sodium salt of polyalkyl methacrylate prepared from a mixture of alcohols obtained by the reduction of coconut oil fatty acids, lithium or potassium salt of polyalkyl methacrylate prepared from commercial lauryl alcohol, and the partial lithium salt of soyabean oil-modified pentaerythritol-pyromellitic acid alkyd resin.  In further examples, lubricating grease compositions are described consisting of mineral lubricating oil, the partial potassium salt of polyalkyl methacrylate prepared from a mixture of alcohols obtained by the reduction of coconut oil fatty acids, and either the sodium soap of tallow fatty acids or sodium dodecyl benzene sulphonate.  For comparison purposes, lubricating grease compositions consisting only of mineral lubricating oil and either sodium stearate prepared from commercial stearic acid or the sodium soap of tallow fatty acids are described. The Specification as open to inspection under Sect. 91 refers to the use of calcium barium or strontium salts as the thickening agent.  It also describes a lubricating grease composition consisting of mineral lubricating oil and the partial sodium salt of polyalkyl methacrylate prepared from a mixture of alcohols obtained by the reduction of coconut oil fatty acids.  This subject-matter does not appear in the Specification as accepted.