Lubricant base oil and lubricating oil composition

Abstract

A lubricant base oil composed of an ester. The ester includes a component (A) derived from trimethylolpropane in a molar percentage A.sub.mol % of 25 to 42 mol %; components (B) derived from monovalent straight-chain saturated fatty acids each having a carbon number of 8 to 12 in a molar percentage B.sub.mol % of 33 to 55 mol %: and a component (C) derived from adipic acid in a molar ratio C.sub.mol % of 12 to 34 mol %. The components (B) include lauric acid in a molar percentage of 5 to 50 mol %, and (B.sub.COOH+C.sub.COOH)/A.sub.OH is 0.90 to 1.02. A.sub.OH represents a hydroxyl equivalent of the component (A), B.sub.COOH represents a carboxyl group equivalent of the components (B); and C.sub.COOH represents a carboxyl group equivalent of the component (C).

Claims

1. A gear oil comprising an ester, said ester comprising: a component (A) derived from trimethylolpropane in a molar percentage A.sub.mol % of 25 to 42 mol %; components (B) derived from monovalent straight-chain saturated fatty acids each having a carbon number of 8 to 12 in a molar percentage B.sub.mol % of 33 to 55 mol %: and a component (C) derived from adipic acid in a molar ratio C.sub.mol %of 15 to 30 mol %, wherein said components (B) derived from said monovalent straight-chain saturated fatty acids each having a carbon number of 8 to 12 comprise a component derived from lauric acid in a molar percentage of 5 to 50 mol %, and wherein (B.sub.COOH+C.sub.COOH/A.sub.OH is 0.90 to 1.02, in the above formula: A.sub.OH represents a hydroxyl equivalent of said component (A) derived from trimethylolpropane, B.sub.COOH represents a carboxyl group equivalent of said components (B) derived from said monovalent straight-chain saturated fatty acids each having a carbon number of 8 to 12, and C.sub.COOH represents a carboxyl group equivalent of said component (C) derived from adipic acid.

2. A gear oil composition comprising: 100 mass percent of said gear oil of claim 1; and 0.1 to 3.0 mass percent of (D) a quinoline derivative.

3. The gear oil as claimed in claim 1, wherein said monovalent straight-chain saturated fatty acids consist of lauric acid, caprylic acid, and pelargonic acid, or consist of lauric acid, caprylic acid and capric acid, or consist of lauric acid, caprylic acid and undecylic acid.

4. The gear oil as claimed in claim 1, wherein said molar percentage A.sub.mol % of said component (A) derived from trimethylolpropane is 27 to 40 mol %.

5. The gear oil as claimed in claim 1, wherein said molar percentage B.sub.mol % of said components (B) derived from said monovalent straight-chain saturated fatty acids is 40 to 53 mol %.

6. The gear oil as claimed in claim 1, adapted for use in a wind turbine generator system.

7. A gear oil composition comprising: 100 mass percent of the gear oil as claimed in claim 1; and an extreme pressure additive in a ratio of 0.1 to 5.0 mass parts.

8. The gear oil composition as claimed in claim 7, further comprising 0.1 to 5.0 mass percent of (D) a quinoline derivative.

Description

EXAMPLES

(1) The present invention will be described further in detail below, referring to the following inventive and comparative examples.

Inventive Examples 1 to 4: Comparative Examples 1 to 6

(2) (Synthesis of Lubricant Base Oils of I to X)

(3) Into a four-necked flask of 5 liters equipped with a thermometer, a tube for introducing nitrogen, agitator and air-cooling tube, predetermined amounts of trimethylolpropane (TMP) supplied by NOF corporation, NAA-82 (Caprylic acid for industrial use having a content of caprylic acid of 99 percent), NAA-102 (capric acid for industrial use having a content of capric acid of 99 percent), NAA-122 (lauric acid for industrial use having a content of lauric acid of 99 percent) were charged. They were reacted under nitrogen flow at 240 C. at ambient pressure while the water generated by the reaction was evaporated.

(4) As to the lubricant base oils I to X obtained as described above, the molar percentage of each component was analyzed using .sup.1H NMR. Further, as to the composition of (B) monovalent straight-chain saturated fatty acid, the molar percentage of each component was measured by gas chromatography. The results of the measurement was shown in tables 1 and 2.

(5) (Acid Value)

(6) It was measured according to Japanese Industrial Standards JIS K0070.

(7) (Kinematic Viscosity at 40 C.)

(8) It was measured according to Japanese Industrial Standards JIS K 2283

(9) (Pour Point)

(10) It was measured according to Japanese Industrial Standards JIS K 2269 at an interval of 1 C.

(11) (Test of Wear Resistance and Load-Carrying Capacity)

(12) As to the lubricant base oils I to X, for evaluating the extreme pressure performance upon adding the extreme pressure additive, 1.2 mass parts of HiTEC 343 (supplied by Afton Chemical Corporation; package of additives containing sulfurized olefin for gear oil) (extreme pressure additive E-1) was added to 100 mass parts of the lubricant base oil, followed by the following tests. The results of the measurement were shown in tables 1 and 2.

(13) (Shell Four-Ball Wear Test)

(14) Using a high-speed Shell four-ball testing machine, wear scar diameter (m) was measured according to ASTM D4172. As the wear scar diameter (m) is smaller, the wear resistance is better.

(15) (Shell Four-Ball Load-Carrying Capacity Test)

(16) Using a high-speed Shell four-ball testing machine, the maximum anti-seizure load was measured according to ASTM D1783. As the maximum anti-seizure load is larger, the extreme pressure performance is better.

(17) (Biodegradation Test)

(18) Biodegradation test was performed according to OECD301 F. In the case that the biodegradability measured by the test is 60 percent or higher, it is satisfied standards as a biodegradable lubricant oil according to ECO MARK OFFICE of Public Interest Incorporated foundation Japan Environment Association. According to this test, it is qualified in the case that the biodegradability is 60 percent or higher and disqualified in the case that biodegradability is below 60 percent.

(19) TABLE-US-00001 TABLE 1 Inventive Examples 1 2 3 4 Lubricant base oil I II III IV A.sub.mol % (mol %) 30.3 30.4 30.3 31.7 B.sub.mol % (mol %) 49.0 48.8 49.0 48.0 C.sub.mol % (mol %) 20.7 20.7 20.7 20.3 B.sub.mol/A.sub.mol 1.62 1.60 1.61 1.51 Molar percentage (mol %) of component 25.2 7.0 44.0 24.8 derived from lauric acid in (B) Molar percentage (mol %) of component 28.9 38.0 22.6 28.9 derived from capric acid in (B) Molar percentage (mol %) of component 45.9 55.1 33.3 46.3 derived from caprylic acid in (B) (B.sub.COOH + C.sub.COOH)/A.sub.OH 0.99 0.99 0.99 0.93 Evaluation Acid value (mgKOH/g) 2.6 2.7 2.8 1.9 of property Kinematic viscosity at 40 C. (mm2/s) 323 325 330 301 Pour point ( C.) 38 41 25 37 Tests of wear Shell four-ball wear test 310 420 305 350 resistance and (wear scar diameter (m) load-carrying Shell four-ball load-carrying capacity test 126 100 126 100 capacity (maximum anti-seizure load: kg) Biodegradability test Qualified Qualified Qualified Qualified

(20) TABLE-US-00002 TABLE 2 Comparative Examples 1 2 3 4 5 6 Lubricant base oil V VI VII VIII IX X A.sub.mol% (mol %) 30.4 30.3 33.3 28.9 28.5 37.0 B.sub.mol% (mol %) 48.8 49.0 46.4 51.4 61.5 25.2 C.sub.mol% (mol %) 20.7 20.7 20.3 19.7 10.0 37.8 B.sub.mol/A.sub.mol 1.60 1.61 1.39 1.78 2.16 0.68 Molar percentage (mol %) of component derived from 0.0 57.2 24.8 25.1 25.3 25.2 lauric acid in (B) Molar percentage (mol %) of component derived from 40.5 17.6 29.2 29.1 28.8 29.0 capric acid in (B) Molar percentage (mol %) of component derived from 59.5 25.2 46.0 45.7 45.9 45.8 caprylic acid in (B) (B.sub.COOH + C.sub.COOH)/A.sub.OH 0.99 0.99 0.87 1.05 0.95 0.91 Evaluation of Acid value (mgKOH/g) 2.4 2.9 0.8 6.0 2.0 1.5 property Kinematic viscosity at 40 C. (mm2/s) 329 355 321 305 43 4110 Pour point ( C.) 45 10 35 40 15 25 Tests of wear Shell four-ball wear test 650 400 590 620 661 305 resistance and load- Shell four-ball load-carrying capacity 80 126 80 80 64 126 carrying capacity test (maximum anti-seizure load: kg) Biodegradability test Qualified Qualified Qualified Qualified Qualified Disqualified

(21) As shown in table 1, it is proved that the lubricant base oils I to IV have excellent biodegradability, good low-temperature fluidity and excellent extreme pressure performance upon adding an extreme pressure additive.

(22) On the other hand, as shown in table 2, according to the comparative example 1, the molar percentage of the component derived from lauric acid in (B) is low, so that the extreme pressure performance is deteriorated.

(23) According to the comparative example 2, the molar percentage of the component described from lauric acid in (B) is high, so that the pour point is high and the low-temperature fluidity is low.

(24) According to the comparative example 3, the value (B.sub.C00H+C.sub.COOH)/A.sub.OH is low, so that the extreme pressure performance is deteriorated.

(25) According to the comparative example 4, (B.sub.COOH+C.sub.COOH)/A.sub.OH is high, so that the extreme pressure performance is deteriorated.

(26) According to the comparative example 5, the molar percentage B.sub.mol % of (B) component derived from the monovalent straight-chain saturated fatty acid having a carbon number of 8 to 12 is high and the molar percentage C.sub.mol % of (C) component derived from adipic acid is low, so that the fluidity at low temperature is low and extreme pressure performance is deteriorated.

(27) According to the comparative example 6, the molar percentage B.sub.mol % of (B) component derived from the monovalent straight-chain saturated fatty acid having a carbon number of 8 to 12 is low and the molar percentage C.sub.mol % of (C) component derived from adipic acid is high, so that the biodegradability was disqualified.

Inventive Examples 5 to 11

(28) As to the lubricant base oils I to IV prepared as described above, the following additives were blended to prepare lubricating oil compositions.

(29) (Preparation of Lubricating Oil Composition)

(30) In a four-necked flask of 5 liters equipped with a thermometer, tube for introducing nitrogen, agitator and a Dimroth condenser, the following additives were added to each of the ester base oils I to IV synthesized as described above in blending ratios described in table 3. The agitation and mixing were performed at 80 C. for 1 hour. After the mixing, the pressure was reduced at 150 C. and 50 mmHg for 2 hours to prepare the respective lubricating oil compositions of the inventive examples 5 to 11 listed in table 3.

(31) (Antioxidant D-1)

(32) Vanlube RD (supplied by R. T. Vandervilt, Inc.: polymerized product of 2,2,4-trimethyl-1,2-dihydroquinoline) (Antioxidant D-2)

(33) NONFLEX AW (supplied by Seiko Chemical Corporation; 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline)

(34) (Extreme Pressure Additive E-1)

(35) HiTEC 343 (supplied by Afton Chemical Corporation; package of additives containing sulfurized olefin for gear oil)

(36) (Extreme Pressure Additive E 2)

(37) Lubrizol 5060 (supplied by Lubrizol corporation: SP-based additive package for gear oil)

(38) (Extreme Pressure Additive E-3)

(39) Lubrizol 5064 (supplied by Lubrizol corporation: SP-based additive package for gear oil)

(40) (Extreme Pressure Additive E 4)

(41) Lubrizol IG93MA (supplied by Lubrizol corporation: SP-based additive package for gear oil)

(42) (Common Additives)

(43) As the common additive components other than the additives (D-1), (D-2), (E-1), (E-2), (E-3) and (E-4), the following compounds were blended in a total amount of L1.02 mass percent.

(44) Dibutylhydroxytoluene (BHT): 0.3 mass percent

(45) N,N-bis (2-ethylhexyl)-(4 or 5)

(46) -methyl-1H-benzotriazol-1-methylamine (Metal deactivator: Irgamet 39 supplied by BASF corporation): 0.05 mass percent

(47) (Evaluation of Lubricating Oil Composition)

(48) The thus prepared lubricating oil composition was subjected to the following evaluations and the results were shown in table 3.

(49) (RPVOT Test)

(50) Oxidation Stability Test of Lubricating oil (RPVOT) was preformed according to Japanese industrial standards (JIS K2514-3 (2013)). Numerical values shown in table 3 indicate time periods (minutes) required for the reduction of the pressure from the maximum pressure by 175 kPa. As the numerical value is larger, the oxidation stability is higher.

(51) (Shell Four-Ball Wear Test)

(52) Using a high-speed Shell four-ball testing machine, wear scar diameter (m) was measured according to ASTM D4172. As the wear scar diameter (m) is smaller, the wear resistance is better.

(53) (Shell Four-Ball Load-Carrying Capacity Test)

(54) Using a high-speed Shell four-ball testing machine, the maximum anti-seizure load was measured according to ASTM D1783. As the maximum anti-seizure load is larger, the extreme pressure performance is better.

(55) (Rust-Prevention Performance Test)

(56) The rust-prevention performance test of a lubricant oil (Artificial sea water) was performed according to Japanese Industrial Standards JIS K 2510. Although the above test is conventionally completed in 24 hours, the present test was continued for two weeks and the results of the rust-prevention performance was evaluated after the two weeks.

(57) (Thermal Stability Test)

(58) The thermal stability test of a lubricant oil is performed using a turntable testing machine according to Japanese Industrial Standards JIS K2540 at 170 C. for 24 hours. According to the test, in the case that precipitates and sludge was not generated, it is described no sludge in the table, indicating that the thermal stability is high. On the other hand, in the case that the precipitate or sludge is generated, it was described presence of sludge in table 3, indicating that the thermal stability is low.

(59) (Flash Point)

(60) Flash point was measured using Cleveland open-cup tester according to Japanese industrial Standards JIS K 2565. As the flash point is higher in the test, the flame retardant property is better.

(61) (Foaminess/Foam Stability Test)

(62) It was measured at sequence I (24 C.) according to Japanese Industrial Standards JIS K2518. As the numerical value is smaller, the foaminess is inferior and defoaming property is higher.

(63) (Biodegradability Test)

(64) Biodegradation test was performed according to OECD 301 F. In the case that the biodegradability measured by the test is 60 percent or higher, it is qualified as a biodegradable lubricant oil according to the standards of ECO MARK OFFICE of Public Interest Incorporated foundation Japan Environment Association. According to this test, it is qualified in the case that the biodegradability is 60 percent or higher and disqualified in the case that biodegradability is below 60 percent.

(65) TABLE-US-00003 TABLE 3 Inventive Examples 5 6 7 8 Blend Lubricant base oil (I) 100 (II) 100 (III) 100 (IV) 100 composition Antioxidant D-1 1.2 1.2 1.2 1.2 (masss %) Extreme pressure agent E-1 2.0 2.0 2.0 2.0 Extreme pressure agent E-2 Extreme pressure agent E-3 Extreme pressure agent E-4 Common additives 0.35 0.35 0.35 0.35 Evaluation RPVOT test (minutes) 565 545 555 530 Results Shell four-ball wear test 315 430 313 338 (wear scar diameter (m)) Shell four-ball load-carrying capacity test 126 100 126 100 (maximum anti-seizure load: kg) Rust-prevention performance test No rust No rust No rust No rust (Artificial sea water: 2 week) Thermal stability test No sludge No sludge No sludge No sludge Flash point ( C.) 298 286 308 278 (Foaminess/Foam stability test (ml/ml) 0/0 0/0 0/0 0/0 Pour point ( C.) 40 40 28 37 Biodegradability test Qualified Qualified Qualified Qualified Inventive Examples 9 10 11 Blend Lubricant base oil (I) 100 (II) 100 (III) 100 composition Antioxidant D-1 1.2 1.2 (masss %) Antioxidant D-2 2.0 Extreme pressure agent E-2 2.5 Extreme pressure agent E-3 5.0 Extreme pressure agent E-4 3.0 Common additives 0.35 0.35 0.35 Evaluation RPVOT test (minutes) 510 560 555 Results Shell four-ball wear test 370 315 377 (wear scar diameter (m)) Shell four-ball load carrying capacity test 100 100 126 (maximum anti-seizure load: kg) Rust-prevention performance test No rust No rust No rust (Artificial sea water: 2 week) Thermal stability test No sludge No sludge No sludge Flash point ( C.) 302 278 290 (Foaminess/Foam stability test (ml/ml) 0/0 10/0 5/0 Pour point ( C.) 38 38 28 Biodegradability test Qualified Qualified Qualified

(66) As described in the inventive examples 5 to 11 shown in tables 1 to 3, it is proved that the lubricating oil compositions I to IV within the scope of claims have excellent biodegradability, excellent low-temperature fluidity, excellent extreme pressure performance, high oxidation stability and high thermal stability upon blending various kinds of additives.

INDUSTRIAL APPLICABILITY

(67) The lubricant base oil of the present invention has excellent biodegradability, excellent low-temperature fluidity, and excellent extreme pressure performance upon blending an extreme pressure additive. The base oil is thus suitable for a base oil for a gear oil or the like and may particularly preferably used in a speed increaser of a wind turbine generation system. Even in the case that the base oil is leaked out, the base oil has excellent biodegradability to reduce the load, onto the environment.