Patent GB-824114-A (GB)
Title: Improvements in or relating to lubricating compositions
Inventor: ELLIOTT JOHN SCOTCHFORD
IPC: C10M169/04
Filed: 1956-05-14
Abstract: A lubricating composition comprises one or more neutral saturated organic carboxylic acid esters and a minor proportion of (a) a compound containing the group -C-S-C-or -C-Se-C- and (b) an imidazole <FORM:0824114/III/1> pyrazole <FORM:0824114/III/2> or a 1,2,3-triazole <FORM:0824114/III/3> which has no sulphur atom in its molecule.  The esters have an acidity not exceeding 1 mg. KOH/gm. and are preferably di-esters of the formula R1OOC-R-COOR2 or complex esters of the formula R2OOC-R-COOR3OOC-R-COOR1, where R is a saturated aliphatic or alicyclic C2-8 hydrocarbon radical, R1 and R2 are alkyl or alkyl-substituted alicyclic radicals of at least 4 carbon atoms, and R3 is derived from the glycol or polyglycol HO-R3-OH.  The radicals R1, R2 and R3 may contain ether oxygen linkages but the esters should contain no atoms other than C, H and O.  Other suitable esters may be obtained by esterifying: a dicarboxylic acid (1 mol.) with (i) a glycol (2 mols.) and a monocarboxylic acid (2 mols.); (ii) a glycol (1 mol.), a monocarboxylic acid (1 mol.) and a monohydric alcohol (1 mol.); or (iii) a hydroxy monocarboxylic acid (2 mols.) and a monohydric alcohol (2 mols.); a glycol (1 mol.) with a hydroxy monocarboxylic acid (2 mols.) and monocarboxylic acid (2 mols.); a glycol or polyglycol (1 mol.) with a monocarboxylic acid (2 mols.); or a polyhydric alcohol such as trimethylol propane or pentaerythritol completely with a monocarboxylic acid.  There are several specific examples of such esters.  The ester, or mixture of esters, used should have a viscosity index above 100, a pour point below -40 DEG F., a boiling (or decomposition) point above 600 DEG  F. and a flash point above 350 DEG  F.  The preferred additives (a) are (i) di-(hydroxyaryl) thioethers as described in Specification 757,219; (ii) dibenzothiazines or dibenzoselenazines, e.g. phenothiazine, phenoselenazine, phenothiazene-3, phenothiazine-5-oxide, 10,101-diphenothiazine, 6,7-benzophenothiazine, or 3,7 difluorophenothiazine; and (iii) dialkyl selenide having at least 12 carbon atoms, e.g. dilauryl or dicetyl selenide.  The additives (b) are imidazoles, pyrazoles or 1,2,3-triazoles, e.g. imidazole (glyoxaline), benzimidazole, pyrazole, benzotriazole, 2-methyl benzimidazole, 3,5-dimethyl pyrazole or indazole.  The composition preferably comprises 0.05 to 5% wt. of (a) and 0.01 to 2% wt. of (b). Optional ingredients mentioned are mineral oil (up to 20% wt.); polymerized esters of acrylic and alkyl-substituted acrylic acids; other polyesters, e.g. of propylene glycol and sebacic acid; amines; neutral organic phosphate and phosphite esters; and metal petroleum sulphonates. Several tests are described to show the effect of various combinations of the additives listed above on di-(2-ethyl hexyl) sebacate, di-(3,5,5-trimethyl hexyl) sebacate and blends thereof with polynonyl methacrylate, 2-ethylhexyl 3,5,5-trimethylhexyl sebacate, a complex ester, and one another. Some of the tested compositions also contained calcium petroleum sulphonate and tri-m-tolyl phosphate.  According to the Provisional Specification, additive (b) may be any organic heterocyclic compound containing two or three nitrogen atoms and one -C=C- linkage in a 5-membered heterocyclic ring. Specifications 757,219, 757,241 and 793,115 are referred to.