Abstract:
A lubricating oil exhibiting superior specific features particularly for metal plastic processing is provided, which lubricating oil comprises at least one member selected from the group consisting of compounds expressed by the formulas I, II, III, IV or V: ##STR1## wherein R 1  is alkyl, alkenyl, hydroxyalkyl, hydroxyalkenyl or phenyl and R 2  and R 3  each are CH 2  OCOR 1 , CH 2  OH or H wherein R 1  is above; ##STR2## wherein R&#39; 1  and R&#39; 2  each are alkyl, alkenyl, hydroxyalkyl, hydroxyalkenyl or phenyl, n is an integer of 1-3 and X is alkyl, alkenyl or phenyl.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an oxazoline compound, an imidazoline ester and an imidazoline acid amide compound having superior lubricating properties. More particularly it relates to a lubricating oil agent exhibiting superior specific features at the time of metal plastic processings such as cold rolling processing, cutting processing, draw processing, press processing, etc. of metals and at the time of spinning of synthetic fibers. 
     2. Description of the Related Art 
     In recent years, the use conditions of lubricating oils have come to be severe accompanying a rapid development of various mechanical industries and hence superior lubricating specific features have come to be required for the oils. 
     Cold rolling oils used for thin steel sheets are roughly classified into those containing animal or plant oils and fats such as beef tallow, lard, rape oil, palm oil, coconut oil, etc. As the base oil thereof and those containing mineral oils as the base oil thereof. In recent years, high-speed rolling, high pressure rolling and mill clean rolling have been desired accompanying energy saving and improvement in the production efficiency. Rolling oils using animal or plant oils and fats as the base oil thereof are suitable for a high-load or high-speed rolling, but if a steel sheet subjected to cold rolling is directly annealed without degreasing oil matters adhered onto the steel sheet, stains occur on the surface of the steel sheet during its annealing step. In short, the above-mentioned rolling oils are superior in the lubricating properties, but unsuitable in the mill cleanability. 
     On the other hand, in the case where rolling oils using mineral oils as the base oil thereof are used for cold rolling, even if a cold thin steel sheet is directly annealed, no surface stain occurs; hence the oils are superior in the mill cleanability, but deficient in the high-load or high-speed rolling properties. 
     In general, in the case where rolling oils using mineral oils as the base oil thereof are used, an oiliness improver has been added thereto and the resulting blend has been used in order to enhance the lubricating properties for rolling; such oiliness improvers being as animal or plant oils and fats, fatty acids e.g. capric acid, lauric acid, myristic acid, stearic acid, oleic acid, linoleac acid, etc., or synthetic esters such as monoesters, diesters or polyol esters of trimethylolpropane, pentaerythritol, 2-ethylhexylalcohol, etc., as described in Oil Chemistry, &#39;73, November, p. 695-706, but the quantity of the foregoing compounds added has been adjusted to a narrow range in order to retain the mill cleanability. Thus, various researches on cold rolling oils which can satisfy both the high lubricating properties and the high mill-cleanability have been carried but (e.g. Japanese Patent Application Laid-open Nos. Sho 56-135600 and Sho 59-80498), but at present, such oils have not yet been found. 
     On the other hand, lubricants used for metal-cutting processing or metal-grinding processing have been composed by suitably mixing mineral oils, animal or plant oils and fats, high-pressure additives, surfactants, anti-foaming agents, metal rust proof agents, antioxidants, antiseptics, antifungal agents, etc. depending on the use. Cutting lubricants have usually been used by diluting them with water to 10 to 100 times, but water-insoluble cutting lubricants have also been used in same cases. 
     The fundamental conditions of cutting or grinding oils to be furnished with are lubricating properties, cooling properties, rust proof properties and other incidental conditions such as those deficient in foaming properties, hand-roughening properties, toxicity to men and beasts, smells, etc. Although cutting or grinding oils are varied in the manner of giving weight, on what properties they should be furnished with, depending on their uses and conditions, they should be furnished with the above-mentioned properties in a well-balanced manner. However, conventional cutting or grinding oils could not have satisfied the above-mentioned conditions. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a synthetic lubricating oil having a molecular structure designed so as to afford superior lubricating characteristics when the use conditions of lubricating oils have come to be severe in recent years. 
     Another object of the present invention is to provide a synthetic lubricant which has high lubricating properties and a high stability and is difficultly deteriorated due to microorganisms and difficultly putrefies. 
     Still another object of the present invention is to provide a cold rolling oil for steel which contributes to improvement in the production efficiency such as energy saving, step saving, etc.; is stable to heat or mechanical shear generated at a high speed or under a high pressure; is also stable to chemical reactions such as oxidation, decomposition, polymerization, etc.; and yields no thermal decomposition residue and does not easily volatize at the annealing step; hence has both of the surface cleanability of steel sheets (mill cleanability) and high lubricating properties. 
     Further still another object of the present invention is to provide a cutting or grinding oil which has superior lubricating properties, cooling properties and rust proof properties; raises no problem of toxicity to men and beasts; and difficultly putrefies. 
     The present invention resides in a lubricating oil comprising at least one member selected from the group consisting of compounds expressed by the following formulas I, II, III, IV or V: ##STR3## wherein R 1  represents an alkyl group, an alkenyl group, a hydroxyalkyl group, a hydroxyalkenyl group each of 5 or more carbon atoms or a phenyl group; R 2  and R 3  each represent CH 2  OCOR 1 , CH 2  OH or H wherein R 1  is as defined above; ##STR4## wherein R&#39; 1  and R&#39; 2  each represent an alkyl group, an alkenyl group, a hydroxyalkyl group, a hydroxyalkenyl group each of 5 or more carbon atoms or a phenyl group; n represents an integer of 1 to 3; and X represents an alkyl group, an alkenyl group each of 2 to 34 carbon atoms or a phenyl group. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Lubricating oils referred to herein mean those which are broadly usable for various uses such as metal plastic processing oils e.g. cutting oil, grinding oil, draw processing oil, press processing oil, rolling oil, etc., mechanical lubricating oils, etc. Cold rolling oils for steels composed mainly of synthetic oils of the present invention have such superior characteristics that they have high lubricating properties and high mill cleanability; they make it possible to carry out rolling of thin steel sheets and directly anneal the resulting materials without degreasing them; furher they have lubricating properties, cooling properties and rust proof properties as cutting oil or grinding oil; and no problem is raised on hand-roughening properties, toxicity to men and beasts, smell, etc. 
     The oxazolines of the above formula (I) may generally be prepared by subjecting monoethanolamine, 2-methyl-2-amino-1,3-propanediol or 2-amino-2-hydroxymethyl-1,3-propanediol and a monocarboxylic acid to dehydration-condensation and cyclization reactions. 
     Examples of the monocarboxylic acid used in the above preparation are saturated fatty acids, unsaturated fatty acids, hydroxyfatty acids, synthetic, branched chain fatty acids each of 6 or more carbon atoms and aromatic carboxylic acids such as benzoic acid, salicylic acid, etc. 
     As the fatty acids, those of 6 to 30 carbon atoms are preferred such as hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid, montanic acid, palmitooleic acid, oleic acid, erucic acid, ricinolic acid, hydroxystearic acid, linolic acid, linoleic acid, isooctylic acid, isodecanoic acid, isolauric acid, isomyristic acid, isopalmitic acid, isostearic acid, isoarachic acid, etc. Further, natural fatty acids such as lanolin fatty acids, fish oil fatty acids, soybean oil fatty acids, coconut fatty acids, beef tallow fatty acids, hydrogenated fatty acids of the foregoing, etc. may also be used. The reason why the carbon atom number of the fatty acids is limited to 6 or more, is that if synthetic oils the raw materials of which are fatty acids having a carbon atom number less than 6 are used, the extent of improving the objective lubricating properties is small. On the other hand, the upper limit of the carbon atom number of the fatty acids has no particular limitation, but the preferred range of the carbon atom number of the fatty acids is 30 or less since cheap fatty acids are commercially available within such a range. 
     The imidazoline ester compounds expressed by the above-mentioned formula (II) may generally be obtained by subjecting N-aminoethylethanolamine and a monocarboxylic acid to dehydration-condensation reaction. 
     The bisimidazoline ester compounds expressed by the above-mentioned formula (III) may be obtained by subjecting a dibasic acid of 4 to 36 carbon atoms and N-aminoethylethanolamine to dehydration-condensation and cyclization reactions and then subjecting the resulting hydroxybisimidazoline and a monocarboxylic acid to esterification reaction. 
     The imidazoline acid amide compounds expressed by the above-mentioned formula (IV) may be obtained by subjecting a polyethylenepolyamine selected from among ethylenediamine, diethyltriamine, triethylenetetramine and tetraethylenepentamine and a monocarboxylic acid to dehydration-condensation and cyclization reactions. 
     The bisimidazoline acid amide compounds expressed by the above-mentioned formula (V) may be obtained by subjecting a dibasic acid of 4 to 36 carbon atoms and a polyethylenepolyamine to dehydration-condensation and cyclization reaction and then subjecting the resulting aminoethylbisimidazoline and a monocarboxylic acid to amidization reaction. 
     As the monocarboxylic acid used in the above-mentioned preparation, the above-mentioned saturated fatty acids, unsaturated fatty acids, hydroxyfatty acids, synthetic, branched chain fatty acids each of 6 or more carbon atoms or aromatic carboxylic acids may be used. 
     As the dibasic acid, dibasic fatty acids of 4 to 36 carbon atoms such as succinic acid, maleic acid, fumaric acid, adipic acid, azelaic acid, sebacic acid, dodecanediacid, brassylic acid, eicosadiacid, dimer acids, etc. and phthalic acid are commercially cheaply available. 
     Further, the reason that the n value of the amidized products in the formulas (IV) and (V) is limited to 1 to 3 is that if the n value exceeds 4, compounds having such values are difficult to be commercially available; hence they are unfavorable for the lubricating oils of the present invention. 
     The synthetic oils of the present invention may also be singly used for rolling oils, lubricating oils for metal plastic processings such as cutting, grinding or draw processing oils, lubricating oils for internal combustion engine, spinning lubricants for synthetic fibers. Further, the synthetic oils may be used in admixture with other base oils such as mineral oils, animal or plant oils or existing synthetic esters generally used. Further, an emulsifier may be added thereto depending on the objects and used in the form of an emulsion. Further, the synthetic oils may also be used in combination with emulsifiers, fatty acids, antioxidants, corrosion-resistant agents, antiseptics, antifungal agents, etc. conventionally used as additives to practical lubricating oils. 
     When the synthetic oils of the present invention are used in admixture with other base oils, etc., addition thereof in one % by weight or more, preferably 20% by weight or more stabilizes the specific features thereof. 
     Next, preparation examples of the oxazoline compounds, imidazoline ester compounds and imidazoline acid amide compounds will be described below. 
     Preparation example 1 (a compound of the formula (I)) 
     Into a four-necked flask equipped with a stirrer, aa thermometer, a nitrogen gas-blowing-in tube and a water separator were fed isostearic acid (Emersol 871, tradename of a product made by Emery Industry Incorporated) (2.8 mols) and 2-amino-2-hydroxymethyl-1,3-propanediol (one mol), followed by reacting these materials under a xylene solvent reflux at 180° to 260° C. until a calculated quantity of water was distilled off. The time required therefor was 9 hours. After completion of the reaction, xylene was distilled off, followed by decolorizing the residue with white clay and filtering off the white clay to obtain the objective reaction product (Sample No. A) (821 g). 
     Preparation example 2 (compounds of the formula (I)) 
     In the same manner as in Preparation example 1, into a four-necked flask were fed lanolin fatty acids (2 mols) and 2-methyl-2-amino-1,3-propanediol (2 mols), followed by reacting these materials under xylene solvent reflux at 180° to 260° C. until a calculated quantity of water was distilled off. The time required therefor was 7 hours. After completion of the reaction, xylene was distilled off, followed by decolorizing the residue with white clay and filtering off the white clay to obtain the objective reaction product (Sample number B) (712 g). Oxazoline compounds (Sample Nos. C and D) prepared in the same manner as above are shown in Table 1. 
     
                                           TABLE 1__________________________________________________________________________Oxazoline synthetic lubricant                             Hue                                Viscosity                                       AcidSample No. R.sub.1     R.sub.2    R.sub.3                             (G)                                (cps 150° C.)                                       value__________________________________________________________________________A     Isostearic acid             Same as the left                        Same as                             6  51     2.1 alkyl residual group   the leftB     Lanolin fatty acid             H          CH.sub.2 OH                             8  98     1.2 alkyl residual groupC     Isooctylic acid             Beef tallow fatty acid                        Same as                             6  72     3.3 alkyl residual group             alkyl residual group                        the leftD     12-Hydroxystearic acid             H          H    5  69     1.8 alkyl residual group__________________________________________________________________________ 
    
     Preparation example 3 (a compound of the formula (II)) 
     Into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas-blowing-in tube and a water separator were fed coconut oil fatty acids (4 mols) and N-aminoethylethanolamine (2 mols), followed by reacting these materials under xylene solvent reflux at 180° to 240° C. until a calculated quantity of water was distilled off. The time required therefor was 7 hours. After completion of the reaction, xylene was distilled off, followed by decolorizing the residue with white clay and filtering off the white clay to obtain the objective reaction product (sample No. E) (820 g). 
     Preparation example 4 (a compound of the formula (III)) 
     In the same manner as in Preparation example 3, into a four-necked flask were fed adipic acid (1.5 mol) and N-aminoethylethanolamine (3 mols), followed by reacting these materials under xylene solvent reflux at 180° to 240° C. until a calculated quantity of water was distilled off. The time required therefor was 8 hours, Oleic acid (2.9 mols) was then fed, followed by carrying out reaction at 180° to 230° C. for 5 hours until a calculated quantity of water was distilled off, followed by distilling off xylene, decolorizing the residue with white clay and filtering off the white clay to obtain the objective reaction product (Sample No. H) (1.060 g). 
     Preparation example 5 (a compound of the formula (IV)) 
     In the same manner as in Preparation example 3, into a four-necked flask were fed isostearic acid (Emersol 871; product made by Emery Industry Incorporated) (1.5 mol) and diethylenetriamine (1.8 mol), followed by reacting these materials under xylene solvent reflux at 180° to 260° C. until a calculated quantity of water was distilled off. The time required was 7 hours. After completion of the reaction, xylene and unreacted diethylenetriamine were distilled off under reduced pressure, followed by feeding benzoic acid (1.5 mol) and carrying out reaction under xylene solvent reflux at 180° to 220° C. for 4 hours until a calculated quantity of water was distilled off, thereafter distilling off xylene, decolorizing the residue with white clay and filtering off the white clay to obtain the objective reaction product (Sample No. J) (680 g). 
     Preparation example 6 (a compound of the formula (V)) 
     In the same manner as in Preparation example 3, into a four-necked flask were fed dimer acid (Haridimer 300; tradename of product made by Harima Kasei Company) (one mol) and triethylenetetramine (2 mols), followed by reacting these materials under xylene solvent reflux at 180° to 260° C. until a calculated quantity of water was distilled off. The time required therefor was 7 hours. Beef tallow fatty acids (1.9 mol) were then fed, followed by carrying out reaction at 180° to 230° C. for 3 hours until a calculated water was distilled off, successively distilling off xylene, decolorizing the residue with white clay and filtering off the white clay to obtain the objective reaction product (Sample No. M) (830 g). Similarly, imidazoline synthetic esters and imidazoline acid amides were prepared. The formers are shown in Table 2 and 3 and the latters are shown in Tables 4 and 5. 
     
                       TABLE 2______________________________________Imidazoline esters of the formula (II)                             Viscosity                                    TotalSample                       Hue  (cps/  amineNo.   R.sub.1     R.sub.2    (G)  50° C.)                                    value______________________________________E     Coconut oil Same as    6     85    98 fatty acid  the left alkyl residual groupF     Isostearic acid             Same as    5    118    79 alkyl residual             the left groupG     Phenyl      Oleic acid 9    104     106             alkyl residual             group______________________________________ 
    
     
                       TABLE 3______________________________________Imidazoline esters of the formula (III)                             Viscosity                                    TotalSample                       Hue  (cps/  amineNo.   R.sub.1     R.sub.2    (G)  50° C.)                                    value______________________________________H     Adipic acid Oleic acid 7    172    112 alkyl residual             alkyl residual group       groupI     Dodecanedionic             Fish oil-  4    229     97 acid        hydrogenated alkyl residual             fatty acid group       alkyl residual             group______________________________________ 
    
     
                       TABLE 4______________________________________Imidazoline acid amide compounds of the formula (IV)                                Vis-Sam-                                 cosity                                      Totalple                             Hue  (cps/ amineNo.  R.sub.1     R.sub.2    n   (G)  50° C.)                                      value______________________________________J    Isostearic acid            Benzoic acid                       1   8    197   105alkyl residual            alkyl residualgroup       groupK    Tall oil fatty            Same as    1   7    181    80acid alkyl  the leftresidual groupL    Castor oil  Same as    3   8    295   176fatty acid  the leftalkyl residualgroup______________________________________ 
    
     
                       TABLE 5______________________________________Imidazoline acid amide compounds of the formula (V)Sam-                                Viscosity                                      Totalple                            Hue  (cps/  amineNo.  R.sub.1    R.sub.2    n   (G)  50° C.)                                      value______________________________________M    Dimer acid Beef tallow                      2   9    380    141alkyl residual           fatty acidgroup      alkyl residual           groupN    Phthalic acid           Soybean oil                      1   8    215    118alkyl residual           fatty acidgroup      alkyl residual           group______________________________________ 
    
    
    
     EXAMPLE 1 
     Test directed to general specific features in the metal plastic processing 
     The test results of the properties of the lubricating oil of the present invention were compared with those of conventional lubricating oils and these results are shown in Table 6. 
     The coefficient of friction and anti-seizing properties were measured by means of Bowden tester and the heat resistance was measured by means of a thermobalance. 
     Test by means of Bowden tester 
     The surface of a low carbon steel sheet was coated with various sample lubricants and the coated surface was pressed by a steel ball of 3/16 inch diameter under a load of 3 kg (hertz pressure: 223 kg/mm 2 ) and the ball was slided in reciprocating manner at a rate of 4 mm/sec to measure the number of times of sliding (anti-seizing properties) at which the coefficient of friction of the coated lubricants reached 0.15. 
     Test by means of thermobalance 
     A sample lubricant (35 mg) was placed in a platinum crucible, followed by gradually heating it at a rate of 5° C. each minute in He atmosphere and measuring the heating temperature at which the sample lubricant decomposed and burnt off. 
     In the Bowden test, the test was carried out under plastic processing conditions of steel sheet as close to the actual ones as possible; the test temperature was made 200° C. taking into account the heat generation due to plastic deformation; and as the steel sheet, a mild steel sheet which easily caused plastic deformation was used. 
     The coefficient of friction corresponds to the power required at the time of actual processing and the anti-seizing properties correspond to the occurrence of seizing marks and the life of tool. 
     Further, in the test by means of thermobalance, it can be said that the higher the temperature at which the sample lubricant burns off, the better the heat resistance. 
     EXAMPLE 2 
     Rolling lubricating oil 
     With a mineral oil or palm oil usually used as a base oil for practical rolling oils were blended an emulsifier, a fatty acid and an oxidant, usually used as additives and the synthetic ester of the present invention to prepare rolling oils, and lubricating properties and annealing properties of the oils were evaluated. 
     An emulsion rolling was carried out be means of a two-stage roll type rolling machine, with a rolling material (spcc) (1.2×20×200 mm) and under condition of an oil matter concentration of 3% and a bath temperature of 50° C., and a rolling load at a draft of 40% was measured to evaluate the rolling lubricating properties. Further, as to the annealing properties, a steel sheet rolled with a sample emulsion was heaped up, as it was, in a number of several tens sheets, followed by fixing these sheets with a steel band having a small width and annealing them in a small type annealing oven. 
     As to the heating condition at the time of the annealing, the steel sheets was heated up to 600° C. in an atmosphere of HNX gas (H 2  : 5%) at a rate of 120 ml/min. and at a temperature-raising rate of 10° C./min., followed by keeping the temperature at 600° C. for one hour, then allowing it to cool down, thereafter applying a cellophane tape onto the steel surface to collect the matter attached thereonto, applying the resulting tape onto a white paper and judging the extent of stains visually to evaluate the surface cleanability of the steel sheet. The test results are collectively shown in Table 7. 
     EXAMPLE 3 
     Cutting oil 
     The results of the durability test, four-ball friction test for lubricant and α-model lubricating property test of a cutting oil having the substance of the present invention blended therein (Sample Nos. 1-4) are shown in Table 8. Sample Nos. 5 and 6 each show a commercially available cutting oil. 
     
                                           TABLE 6__________________________________________________________________________                            Test results                                  Anti-  Sample lubricant                seizing                                       Heat      Blended                     property                                       resis-  Sample      amount                Coefficient                                  (fre-                                       tance  No. 1*      (%)  other blended agents                            of friction                                  quencies)                                       (°C.)__________________________________________________________________________Lubricating  A   100                   0.050 84   470oil of the  B   100                   0.055 82   420present  C   100                   0.045 89   500invention  D   100                   0.055 78   450  A   30   Machine oil 65%  0.065 70   415           Stearine oil 5%  C   10   Beef tallow 30%, Machine oil 55%                            0.060 75   430           Nonionic surfactant 5%  D   30   Machine oil 25%, Beef tallow 25%                            0.065 66   420           Octyl stearate 15%           Nonionic surfactant 5%Conventional    Machine oil 100% 0.120 4    355lubricating     Stearic acid 100%                            0.070 11   360oil             Beef tallow 100% 0.065 26   430           Machine oil 35%, Beef tallow 35%                            0.080 29   400           Octyl stearate 30%__________________________________________________________________________ *Nos. A-D each indicate the same ester component as those of Samples Nos. in Table 1. 
    
     
                                           TABLE 7__________________________________________________________________________            Emulsion.sup.5            Comp.                Synthetic ester (content: 45%)            ex. 1                Sample No. A                       Sample No. B                              Sample No. C                                     Sample No. D__________________________________________________________________________Composition  Mineral oil            55  50.5   50     50     50.5of rolling  Purified Oil and fat            40  --     --     --     --oil*   Palmitic acid            2.5 2.5    2.5    2.5    2.5  Antioxidant.sup.1            1   1      1      1      1  Emulsifier.sup.2            1.5 1      1.5    1.5    1Ratio of rolling loads.sup.3            1.00                0.95   0.97   0.93   0.96(lubricating properties)Annealing properties.sup.4            x˜ Δ                ⊚ ˜○                       ⊚ ˜○                              ⊚˜                                     ⊚                                     ˜○__________________________________________________________________________                                     1 *Composition of rolling oil wt. % .sup.1 Antioxidant, 2,6tert-butyl-4-methylphenol .sup.2 Emulsifier, polyoxyethylenenonylphenylether (HLB 11.5) .sup.3 Ratio of rolling loads, value based on Comparative ex. 1 .sup.4 Evaluation of the surface cleanability of steel sheet  ⊚  Stain occurrence, none  ○  Stain occurrence, very slight Δ Stain occurrence, apparent  x Stain occurrence, much .sup.5 Practically used emulsion, oil content 3% Nos. A˜D each indicate the same ester content as those of the Nos. in Table 1. 
    
     
                                           TABLE 8__________________________________________________________________________                      Compressive.sup.2                             Seizing.sup.3                                  Attrition.sup.3Sample             Durablity.sup.1                      strength                             load widthNo. Blending (%)   Test    (kg/cm.sup.2)                             (kg) (mm)__________________________________________________________________________1   Sample No. A           40%              Unchanged,                      &gt;22    &gt;315 2.8    Liquid paraffin           60%              flowable2   Sample No. B           55%              Unchanged,                      &gt;20    &gt;315 2.9    Liquid paraffin           40%              flowable    Coconut oil 5%3   Sample No. C           40%              Unchanged,                      &gt;25    &gt;315 2.5    Liquid paraffin           60%              flowable4   Sample No. D           60%              Unchanged,                      &gt;23    &gt;315 2.7    Liquid paraffin           40%              flowable5   Commercially available              Cured into                      5      160  5    general-purpose product              varnish form    Spindle oil 90%    Fatty oil content           10%6   Commercially available              Discolored into                      15     &gt;315 3.5    general-purpose product              black-brown,    Spindle oil 93%              flowable    Fatty oil content           5%    Chlorine content           2%__________________________________________________________________________ Note .sup.1 Coldrolled steel sheet was dipped in a sample oil, followed by pulling up the sheet, allowing it to still stand horizontally at an indoo place near a window where no direct sunlight is shined and observing the condition of the steel. .sup.2 Using a sodatype fourball tester according to JIS K2519 and applying a series of loads each at a rate of 0.5 kg/cm.sup.2 per minute a 220 rpm, the lubricating properties of a cutting oil according to the present invention were compared with those of a commercially available cutting oil. .sup.3 Using an model LFWtype tester according to ASTM D2714, a series of loads each at a rate of 15 kg/min. were applied up to 315 kg onto a test piece at 300 rpm at 110° F., and the attrition width and seizing load of the resulting piece were measured. 
    
     EXAMPLE 4 
     Aqueous cutting oil 
     Aqueous cutting oils (Sample Nos. 7-10) having the substances of the present invention blended therein were prepared and these oils were each diluted with sterilized water into 5% by weight to prepare testing solution, which are shown in Table 9. 
     Using these testing solution shown in Table 9, tests shown in Table 10 were carried out. 
     
                                           TABLE 9__________________________________________________________________________Blending example (%)    Substance of                      AntisepticSample    the present     Chlorinated                     Anionic                           Nonionic                                 (TriazineNo. invention Mineral oil               paraffin                     surfactant                           surfactant                                 compound)__________________________________________________________________________7   Sample No. A       40         30    10    14    5     18   Sample No. B       50         30    --    15    5     --9   Sample No. C       30         50    5     9     5     110  Sample No. D       50         40    5     --    5     --11  --        55    15    23    5     2__________________________________________________________________________ 
    
     
                                           TABLE 10__________________________________________________________________________         Blending sample No.Measurement item         7    8    9    10   11__________________________________________________________________________Appearance change.sup.1         ○              ○                   ○                        ○                             ΔSmell.sup.2   ○              ○                   ○                        ○                             ΔpH            8.6  9.2  9.0  9.1  9.0Number of fungi/ml.sup.3         10 or less              10 or less                   10 or less                        10 or less                             5 × 10.sup.2Rust proof properties (24 h).sup.4         ⊚              ⊚                   ⊚                        ⊚                             ΔCoefficient of friction.sup.5         0.16 0.14 0.20 0.13 0.25Compressive strength (kg).sup.6         16.5 16.0 15.5 18.0 10.0__________________________________________________________________________ 
    
     EXAMPLE 5 
     Using the lubricating oils of the present invention (Sample Nos. E-N in Tables 2-5), tests directed to specific features in metal plastic processing were carried out in the same manner as in Example 1. The results are shown in Table 11. 
     EXAMPLE 6 
     Rolling lubricating oil 
     Using the synthetic esters of the present invention (Sample Nos. E, F, I, J, L and M), rolling oil emulsions having compositions as indicated in Table 12 were prepared and rolling lubricating properties and annealing properties were tested in the same manner as in Example 2. The results are shown in Table 12. 
     EXAMPLE 7 
     Cutting rolling oil 
     The durability tests, four-ball lubricating properties tests and α-model lubricating properties tests of the cutting oils (Sample Nos. 1-4) having the substances of the present invention blended therein were carried out. The results are shown in Table 13. Sample Nos. 5 and 6 indicates commercially available cutting oils. 
     EXAMPLE 8 
     Aqueous cutting oil 
     As shown in Table 14, aqueous cutting oils (Sample Nos. 7-11) having the substances of the present invention blended therein were prepared, followed by diluting the oils into 5% by weight to prepare testing solutions. Sample No. 12 shows comparative example. 
     Using the blending examples shown in Table 14, tests shown in Table 15 were carried out. 
     
                       TABLE 11______________________________________               Test results                         Anti-                         seizing HeatSample lubricant      Co-effi-                         proper- resis-Sample Blended                 cient of                               ties  tanceNo.*  amount   Other blending agents                         friction                               (°C.)                                     (%)______________________________________Lubricating oils of the present inventionE     100                       0.055 77    450F     100                       0.050 80    460G     100                       0.055 78    445H     100                       0.045 86    470I     100                       0.040 88    500J     100                       0.050 80    455K     100                       0.050 82    445L     100                       0.050 80    465M     100                       0.030 92    470N     100                       0.040 88    460E     30       Machine oil                     65%   0.065 66    420          Stearic acid                     5%F     10       Beef tallow                     30%   0.060 70    425          Machine oil                     55%          Nonionic          surfactant 5%H     30       Machine oil                     25%   0.055 75    430          Beef tallow                     25%          Octyl stearate                     15%          Nonionic          surfactant 5%Conventional lubricating oil    Machine oil             100%    0.120   4     355    Stearic acid             100%    0.070   11    360    Beef tallow             100%    0.065   26    430    Machine oil             35%     0.080   29    400    Beef tallow             35%    Octyl stearate             30%______________________________________ *Nos. E-N indicate the same ester components as those of Sample Nos. in Tables 2-5. 
    
     
                                           TABLE 12__________________________________________________________________________            Emulsion.sup.5                  Synthetic ester (content: 45%)            Comp. ex.                  Sample                      Sample                          Sample                              Sample                                  Sample                                      Sample            1     No. E                      No. F                          No. I                              No. J                                  No. L                                      No. M__________________________________________________________________________Composition  Mineral oil            55    50  50.5                          50  50  50  50.5of rolling  Purified oil and fat            40    --  --  --  --  --  --oil*   Palmitic acid            2.5   2.5 2.5 2.5 2.5 2.5 2.5  Antioxidant.sup.1            1     1   1   1   1   1   1  Emulsifier.sup.2            1.5   1.5 1   1.5 1.5 1.5 1Ratio of rolling loads.sup.3            1.00  0.96                      0.95                          0.93                              0.94                                  0.92                                      0.92(lubricating properties)Annealing properties.sup.4            x˜ Δ                  ⊚ ˜ ○                      ⊚ ˜ ○                          ⊚ ˜ ○                              ⊚ ˜ ○                                  ○                                      ○__________________________________________________________________________ *Composition of rolling oil wt. % .sup.1 Antioxidant, 2,6tert-butyl-4-methylphenol .sup.2 Emulsifier, polyoxyethylenenonylphenylether (HLB 11.5) .sup.3 Ratio of rolling loads, value based on Comparative example 1 .sup.4 Evaluation of the surface cleanability of steel sheet  ⊚  Stain occurrence, none  ○  Stain occurrence, very slight Δ Stain occurrence, apparent x Stain occurrence, much .sup.5 Practically used emulsion, oil content 3% 
    
     
                                           TABLE 13__________________________________________________________________________                      Compressive                             Seizing.sup.3                                  Attrition.sup.3Sample             Durability.sup.1                      strength                             load widthNo. Blending (%)   test    (kg/cm.sup.2)                             (kg) (mm)__________________________________________________________________________1   Sample No. A           40%              Unchanged,                      &gt;22    &gt;315 2.9    Liquid paraffin           60%              Flowable2   Sample No. D           55%              Unchanged                      &gt;26    &gt;315 2.6    Liquid paraffin           40%              Flowable    Coconut oil 5%3   Sample No. H           40%              Unchanged,                      &gt;24    &gt;315 2.7    Liquid paraffin           60%              Flowable4   Sample No. J           60%              Unchanged,                      &gt;25    &gt;315 2.6    Liquid paraffin           40%              Flowable5   Commercially available              Cured into                      5      160  5    general-purpose product              varnish form    Spindle oil 90%    Fatty oil content           10%6   Commercially available              Discolored into                      15     &gt;315 3.5    general-purpose product              black-brown,    Spindle oil 93%              Flowable    Fatty oil content           5%    Chlorine content           2%__________________________________________________________________________ Note .sup.1 Coldrolled steel sheet was dipped in a sample oil, followed by pulling up it, allowing it to stand still horizontally at an indoor place near a window where direct sunlight is not shined, and observing its condition. .sup.2 Using a Sodatype fourball tester according to JIS KL519 and applying loads each at a rate of 0.5 kg/cm.sup.2 per min. at 220 rpm, the lubricating properties of the cutting oils of the present invention were compared with those of commercially available cutting oil. .sup.3 Using an model LFW1 type tester according to ASTM D2714, and applying loads each at a rate of 15 kg/min. at 300 rpm and at 110° C. up to 315 kg, the attrition width of the resulting test piece and the seizing load were measured. 
    
     
                                           TABLE 14__________________________________________________________________________Blending example (%)    Substance of                    AntisepticSample    the present     Chlorinated                     Anionic                           Nonionic                               (triazineNo. invention Mineral oil               paraffin                     surfactant                           surfactant                               compound)__________________________________________________________________________7   Sample No. E       40         30    10    14    5     18   Sample No. G       50         30    --    15    5     --9   Sample No. I       30         50    5     9     5     110  Sample No. M       50         40    5     --    5     --11  Sample No. N       40         40    14    --    5     112  --        55    15    23    5     2__________________________________________________________________________ 
    
     
                                           TABLE 15__________________________________________________________________________         Blending sample No.Measurement item         7    8    9    10   11   12__________________________________________________________________________Change in appearance.sup.1         ○              ○                   ○                        ○                             ○                                  ΔSmell.sup.2   ○              ○                   ○                        ○                             ○                                  ΔpH            9.1  9.2  9.1  9.0  9.2  9.0Number of fungi/ml.sup.3         10 or less              10 or less                   10 or less                        10 or less                             10 or less                                  5 × 10.sup.2Rust proof properties (24 h).sup.4         ⊚              ⊚                   ⊚                        ⊚                             ⊚                                  ΔCoefficient of friction.sup.5         0.15 0.16 0.18 0.12 0.13 0.25Compressive strength         16.5 16.5 16.0 18.0 18.5 10.0__________________________________________________________________________ Note .sup.1 to .sup.6 in Table 15 are as described in Table 10. 
    
     The synthetic ester compounds of the present invention prepared from a nitrogen-containing polyol and a fatty acid are far superior in the aspect of lubricating properties and stability to conventional lubricating oils, and usable as lubricating oils for various industries such as rolling oils, hydraulic fluids, cutting-grinding oils, lubricating oils for metal plastic processing, lubricating oils for internal engines, spinning lubricant for synthetic fibers, etc. 
     For example, the rolling oils composed of the synthetic ester compounds of the present invention more improve the rolling lubricating properties of steel sheets as compared with cold rolling oils using existing synthetic esters; hence energy saving such as reduction in the power cost and resources-saving effect are brought about. Further, the oils are also superior in the annealing properties, can omit conventional electrolytic degreasing and can reduce equipment cost. 
     Further, the synthetic ester compounds can constitute a high performance lubricant which has superior lubricating properties at the time of cutting or grinding and also can sufficiently satisfy various use conditions such as smell, stability, etc. 
     Further, at the time of processing lubrication, sufficient lubrication is ensured even under severe conditions such as high-speed processing and it is possible to make the processing smooth and efficient. 
     Furthermore, it is possible to prevent the quality reduction of products which occurs due to lubricating insufficiency such as seizing marks; attrition or breakage of tools is prevented; the quality of products in enhanced; and the life of tools is notably prolonged. 
     Further, many superior effects are brought about such as reduction in the power required at the time of processing, more promotion of resources saving, energy saving, etc.