Oil composition for cutting and grinding by minimal quantity lubrication system

An oil composition consisting of:

• an ester of at least one polyhydric alcohol selected from dihydric alcohols, glycerin, polyglycerols, trimethylolalkanes and dimers to octamers thereof, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol and tetrahydric to decahydric alcohols and at least one monobasic acid selected from fatty acids having 2 to 24 carbon atoms, with the proviso that when the polyhydric alcohol is glycerin the ester is a monoester of glycerin, and at least one phosphorus compound selected from phosphate ester, acid phosphate ester, acid phosphate ester amine salt, chlorinated phosphate ester, phosphite ester and phosphorothionate, and optionally a sulfur compound;
• a mineral oil;
• at least one synthetic oil selected from poly-α-olefins, alkylbenzene, alkylnaphthalene, polyoxyalkylene glycol and polyphenyl ether;
• at least one antioxidant selected from 2,6-di-tert-butyl-p-cresol;
• 4,4′-methylenebis(2,6-di-tert-butylphenol), 4,4′-bis(2,6-di-tert-butylphenol), 4,4′-thiobis(6-tert-butyl-o-cresol), ascorbic acid, fatty acid ester of ascorbic acid, tocopherol, 3,5-di-tert-butyl-4-hydroxyanisole, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline, 2-(1,1-dimethyl)-1,4-benzenediole and 2,4,5-trihydroxybutyrophenone;
• at least one oiliness improver selected from alcohols, carboxylic acids, sulfides of unsaturated carboxylic acids, compounds represented by the following general formula (6):
• wherein R1 represents a hydrocarbon group having carbon atoms from 1 to 30, m1 is an integer from 1 to 6 and n1 is an integer from 0 to 5;
• compounds represented by the following general formula (7):
• wherein R2 represents a hydrocarbon group having carbon atoms from 1 to 30, m2 is an integer from 1 to 6 and n2 is an integer from 0 to 5;
• and esters other than monoesters of glycerin;
• extreme pressure additives except the aforementioned phosphorus compounds and sulfur compounds;
• at least one film forming agent selected from acrylic polymer, paraffin wax, microwax, slack wax and polyolefin wax;
• at least one water substituting agent selected from fatty acid amine salts;
• at least one solid lubricant selected from graphite, graphite fluoride, molybdenum disulfide, boron nitride and polyethylene powder;
• at least one corrosion inhibitor selected from amines, alkanoamines, amides, carboxylic acids, carboxylates, sulfonates, phosphoric acid, phosphates and partial esters of polyhydric alcohols;
• at least one metal passivator selected from benzotriazole and thiadiazole,
• at least one antifoaming agent selected from methylsilicone, fluorosilicone and polyacrylate;
• and
• at least one ashless dispersant selected from alkenylsuccinimide, benzylamine and polyalkenylamineaminoamide;
• wherein the ester is a base oil and is present in an amount of at least 50% by mass based on the total weight of the composition;
• and
• wherein amounts of said esters, phosphorous compound, optional sulfur compound, at least one synthetic oil, at least one antioxidant, at least one oiliness improver, compounds represented by general formula (7), extreme pressure additives, at least one film forming agent, at least one water substituting agent, at least one solid lubricant, at least one corrosion inhibitor, at least one metal passivator, at least one antifoaming agent, and at least one ashless dispersant are selected to configure the oil composition for use in cutting and grinding by minimal quantity lubrication.