Patent GB-594960-A (GB)
Title: Compounded lubricating oil
Filed: 1944-10-12
Abstract: A lubricating oil composition especially suitable for use in aviation engines contains (i) a small proportion of an oil-miscible metal salt of the condensation product of formaldehyde or acetaldehyde with a compound having an aromatic nucleus with both a hydroxyl and a hydrocarbon substituent group, the ortho position in the aromatic nucleus with respect to the hydroxyl group being unsubstituted, and (ii) a small proportion of one or more of the substances phenyl-a-naphthylamine, zinc dialkyl- or dicycloalkyldithiophosphate, tetramethyldiamino diphenylmethane and oil-soluble sulphur-containing anti-oxidants which are free from corrosive sulphur, substantially free from polar and metallic radicles and contain a minimum of about 7 carbon atoms per molecule. Sulphur-containing anti-oxidants mentioned as being suitable are mercaptans, butyl or other higher alkyl thiophenes, thionaphthols, alkyl thionaphthols, organic disulphides, organic polysulphides containing the <FORM:0594960/III/1> in which n is 1 or 2 and m is an integer, thiazoles and reaction products of sulphur with substances containing an olefinic double bond.  The lubricating oil composition may also contain other additives such as blooming agents, pour-point depressants, viscosity improvers, anti-oxidants, extreme pressure agents, antifoaming agents detergents, and corrosion inhibitors. Detergents mentioned are the metal or nitrogen base salts of detergent-forming acidic substances of which a large number are specified, alkaline earth phosphate or thiophosphate diesters, alkaline earth diphenolates alkaline earth salts of diphenol mono- and poly-sulphides, phosphatides, fatty oils and voltolised fatty or mineral oils.  Many antioxidants of the phenolic, aminophenol or amino type are specified and alkali metal and alkaline earth salts of sulphonic acids and fatty acids are mentioned as suitable corrosion inhibitors.  In the examples lubricating oil compositions contain as the first ingredient a compound referred to as the calcium salt of methylene bis p-iso-octylphenol which is prepared by condensing phenol with di-isobutylene, reacting the product with formaldehyde and then forming the calcium salt by treating with lime.  As the second ingredient the compositions contain either (a) sulphurised paraffin wax olefin prepared by chlorination of paraffin wax, dehydrochlorination of the chlorinated product to produce olefins and sulphurisation of the latter, (b) sulphurised sperm oil, (c) dibenzyl disulphide, (d) dodecyl disulphide, (e) sulphurised methyl pentadiene polymer, (f) N.N1-tetramethyl-p.p1-diamino-diphenylmethane and calcium petroleum sulphonate, (g) phenyl-a-naphthylamine and calcium petroleum sulphonate or (h) N.N.1-tetramethyl-p.p1-diamino-diphenylmethane, phenyl-a-naphthylamine and calcium petroleum sulphonate.  Tests are described in which the lubricating oil compositions of the examples are compared with lubricating oil compositions containing either (1) calcium salt of methylene bis p-iso-octyl phenol only, (2) calcium salt of methylene bis p-iso-octyl phenol and either or both of barium dialkyl dithiophosphate and calcium petroleum sulphonate, or (3) barium dialkyl dithiophosphate only.  U.S.A. Specification 2,042,880 is referred to.  The Specification as open to inspection under Sect. 91 refers to ingredient (i) of the lubricating oil composition as being an oil-miscible metal salt of the condensation product of a low molecular weight aldehyde with a compound having a hydroxyl radical attached to an aromatic nucleus.  This subject-matter does not appear in the Specification as accepted.