Patent GB-718581-A (GB)
Title: Improvements in and relating to synthetic lubricating oils
Inventor: AIRS RAYMOND SPENCER
IPC: C10M169/00
Filed: 1952-11-19
Abstract: Lubricating compositions are obtained by adding a polymer of an ester of acrylic acid or a 1-alkylacrylic acid and a salt of an aromatic carboxylic acid or of a phenol with a metal of Group II of the Periodic Table to the synthetic lubricating oil obtained by heating a mixture of 2 or more liquid esters of formula (RCOOR1)2, in which R is a divalent radical and R1 is an alkyl, cycloalkyl or aralkyl radical of 4 or more carbon atoms, with an alkali metal at a temperature between the melting-point of the metal and 200 DEG C. for at least an hour.  The Group II metal is added in sufficient quantity to give a proportion of from 0.01 to 1.0 per cent. by weight in the final product and the polymer is present in a proportion of 2 to 30 per cent. by weight.  In an example, a mixture of equal parts of di- (3, 5, 5-trimethyl-hexyl) sebacate and "Acryloid 710" (a polymer of either methyl acrylate or methyl methacrylate) is mixed with the lubricant obtained by heating a mixture of di- (3, 5, 5-trimethyl-hexyl) sebacate and di- (2-ethyl-hexyl) sebacate in the presence of sodium; a mineral oil solution of a calcium salt of a para-octyl phenol-formaldehyde is then blended into the mixture. Specification 703,445 is referred to.ALSO:Synthetic lubricating oils are obtained by a method comprising heating a mixture of 2 or more normally liquid esters, each of which is of the general formula R(COOR1)2, in which R is a divalent hydrocarbon radical and R1 is an alkyl, cycloalkyl or aralkyl hydrocarbon radical containing 4 or more carbon atoms and in which the R1 radicals may be the same or different, with an alkali metal at a temperature above the melting-point of the metal and below 200 DEG  C. for a period of at least one hour.  Suitable esters are preferably those derived from aliphatic acids, e.g. malonic, ethylmalonic, succinic, methylsuccinic, 1,1- or 1,2-diethylsuccinic, glutaric, 1- or 2-methylglutaric, 1,3-diethylglutaric, adipic, 1- or 2-methyladipic, pimelic, 1,2,5-trimethylpimelic, suberic, azelaic, sebacic, nonane-1,9-dicarboxylic and decane-1,10-dicarboxylic acids.  Esters derived from aromatic dicarboxylic acids such as phthalic acid may also be used.  The alcohols from which the esters are derived are preferably branched chain alcohols. Typical esters which may be used are di - (2 - methylheptyl) adipate, di - (3,5,5 - trimethyl hexyl) adipate or sebacate, di-(3-ethylhexyl) adipate or sebacate, di-(2-ethylhexyl) adipate or sebacate, dihexyl pimelate, di-isobutyl sebacate, di-isobutyl malonate, di-(1-ethylpropyl) azelate and di-isobutyl ethylmalonate.  Liquid esters derived from commercial mixtures of alcohols containing a substantial proportion of branched chain alcohols, such as alcohols made by the Oxo process, are also suitable.  Sodium is the preferred alkali metal and the esters are preferably subjected to the process in an oxygen-free atmosphere. In the examples: (a) a mixture of di-(3,5,5-trimethylhexyl) sebacate is heated with di-(2-ethylhexyl) sebacate in the presence of sodium; (b) a mixture of di-(3,5,5-trimethylhexyl) sebacate is heated with a commercial mixture of primary aliphatic alcohols containing from 7 to 9 carbon atoms.  Specifications 703,445, [Group IV (a)], is referred to.ALSO:Synthetic lubricating oils are obtained by heating a mixture of 2 or more normally liquid esters, each of which is of the general formula R(COOR1)2 in which R is a divalent hydrocarbon and R1 is an alkyl, cyclo alkyl or aralkyl hydrocarbon radical of 4 or more carbon atoms, the R1 radicals being the same or different, with an alkali metal at a temperature above the melting point of the metal but not above 200 DEG C. for at least an hour.  In the examples lubricating oils were obtained by heating (a) di (3.5, 5-trimethylhexyl) sebacate and di (2-ethylhexyl) sebacate in the presence of sodium; (b) di 3.5 5-trimethylhexyl) sebacate and the ester of sebacic acid with a commercial mixture of primary aliphatic alcohols containing 7-9 carbon atoms in the presence of sodium.  These lubricating oils may be used as base lubricating oils in compositions of the type claimed in Specification 703,445, e.g. a lubricating composition may be obtained by mixing a lubricating oil prepared as described above with 2 to 30 per cent. by weight of a polymer of an ester of acrylic acid or a 1-alkylacrylic acid, the mixture also containing sufficient of a salt of an aromatic carboxylic acid or of a phenol with a metal of Group II of the Periodic Table to give a metal content to the composition of from 0.01 to 1.0 per cent. by weight.  Small quantities of mineral lubricating oils may be added to the lubricants.  Extreme pressure additives, e.g. trialkyl, triaryl or trialkaryl phosphates, monobutyl trichloromethane phosphonate or its amine salts and antioxidants may also be added. Other materials may be added to give special properties, e.g. the complex ester ethers obtained by condensing alkyline oxides with carboxylic acids.