LUBRICATING OIL COMPOSITION

Abstract

A lubricating oil composition including 100 mass parts of (A) an ester compound, 0.05 to 1.5 mass parts of (B) an amine salt of an acidic phosphoric ester and 0.01 to 0.50 mass parts of (C) a monoesterified compound, wherein (A) the ester compound is an ester compound of trimethylolpropane, a straight-chain saturated fatty acid having a carbon number of 8 to 10 and adipic acid; (B) the amine salt is an amine salt of an acidic phophoric ester; and (C) the monoesterified compound is a monoesterified compound of an alkane diol having a carbon number of 3 to 8 and of succinic acid having an alkyl group having a carbon number of 8 to 18 or an alkenyl group having a carbon number of 8 to 18.

Claims

1. A lubricating oil composition comprising: 100 mass parts of (A) an ester compound described below; 0.05 to 1.5 mass parts of (B) an amine salt of an acidic phosphoric ester described below; and 0.01 to 0.50 mass parts of (C) a monoesterified compound described below, wherein: (A) said ester compound of trimethylolpropane, a straight-chain saturated fatty acid having a carbon number of 8 to 10 and adipic acid, said ester compound satisfying the relationship of TMP.sub.mol %:FA.sub.mol %:AD.sub.mol % of 20 to 40%:40 to 70%:5 to 25%, respectively, provided that TMP.sub.mol % is assigned to a molar percentage of a component derived from trimethylolpropane, FA.sub.mol % is assigned to a molar percentage of a component derived from said straight-chain saturated fatty acid having a carbon number of 8 to 10, and AD.sub.mol % is assigned to a molar percentage of adipic acid (B) said amine salt of said acidic phosphoric ester represented by the following formula (1): ##STR00003## wherein n represents an integer of 1 or 2, R represents an alkyl group having a carbon number of 4 to 6, and R represents hydrogen atom or an alkyl group having a carbon number of 11 to 14; and (C) said monoesterified compound of an alkane diol having a carbon number of 3 to 8 and of succinic acid having an alkyl group having a carbon number of 8 to 18 or an alkenyl group having a carbon number of 8 to 18.

Description

EXAMPLES

[0068] The present invention will be described further in detail below, referring to inventive and comparative examples.

(Synthesis of Ester Compounds I to V)

[0069] Into a four-necked flask of 5 liters equipped with a thermometer, a tube of introducing nitrogen gas, an agitator and an air-cooling tube, predetermined amounts of trimethylolpropane (TMP), NAA-82 supplied by NOF corporation (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) and adipic acid were charged. The mixture was reacted under nitrogen flow at 240 C. at ambient pressure while water generated during the reaction was evaporated, to obtain the ester compounds I to V.

(Synthesis of Ester Compound VI)

[0070] Predetermined amounts of trimethylolpropane (TMP), NAA-34 supplied by NOF corporation (oleic acid for industrial use) and dimer acid were charged into a four-necked flask of 5 liters equipped with a thermometer, a tube for introducing nitrogen gas, an agitator and an air-cooling tube, and then reacted under nitrogen gas flow at 240 C. under ambient pressure, while water generated during the reaction was evaporated, to obtain the ester compound VI.

[0071] As to the ester compounds I to VI obtained as described above, the molar percentages of the respective raw materials were measured by .sup.1H NMR and listed in table 1. Further, kinematic viscosities at 40 C. and at 100 C., flash point, acid value and viscosity index were measured and the results were shown in table 1.

TABLE-US-00001 TABLE 1 Ester compound I II III IV V VI Molar percentage trimethylolpropane 29.7 29.7 28.3 31.7 28.4 29.9 of component Fatty acid mixture of caprylic 54.1 54.1 52.9 41.1 62.1 derived from raw and capric acids material Adipic acid 14.1 14.1 16.4 24.0 8.1 (mol %) oleic acid 2.0 dimer acid 0.4 (FA.sub.COOH + AD.sub.COOH)/TMP.sub.OH 0.9 0.9 1.0 0.9 0.9 Physical values kinematic viscosity at 40 C. (mm2/s) 102.3 110.9 156.3 410.0 44.6 140.6 kinematic viscosity at 100 C. (mm2/s) 14.0 15.5 21.0 38.1 7.7 22.0 viscosity index 139 148 158 139 140 184 Flash point ( C., COC ) 280 282 286 290 258 290 acid value (mg KOH/g) 0.5 0.6 1.8 0.8 0.2 2.2

Inventive Examples 1 to 6 and Comparative Examples 1 to 10

(Preparation of Lubricating Oil Composition)

[0072] Additives were blended into each of the ester compounds I to VI obtained as described above, according to the following procedure, to prepare lubricating oil compositions of the inventive examples 1 to 6 and comparative examples 1 to 10.

[0073] The following additives were added, in blending ratios described in tables 2 and 3, respectively, into each of the ester compounds 1 to VI synthesized as described above, in a four-necked flask of 5 liters equipped with a thermometer, a tube for introducing nitrogen gas, an agitator and a Dimroth condenser. The thus obtained mixture was reacted at 80 C. for 1 hour by performing mixing by agitation to obtain each of the lubricating oil compositions.

[0074] Further, the following additives were used.

(Wear Prevention Agent)

[0075] (B) mono.dihexyl phosphate.C11 to C14 branched alkyl amine salt

[0076] (Reinchemie Ltd. RC 3760) [0077] (B) Branched butyl phosphate.C11 to C14 branched alkyl amine salt

[0078] (Reinchemie Ltd. RC 3740) [0079] tridecyl acid phosphate.trioctylamine salt

(Rust-Prevention Agent)

[0080] (C) Monoester of dodecenyl succinic acid and 1,2-propanediol (BASF corporation, IRGACOR L 1 2) [0081] Dodecenyl succinic acid alkylimide (imidized product of dodecenyl succinic acid and dodecylamine) [0082] N-oleoyl sarcosine [0083] N-hydroxyethyl oleyl imidazoline

(Oxidation Prevention Agent)

[0084] dibutyl hydroxytoluene (GHT)

(Metal Deactivator)

[0085] Benzotriazole derivative

[0086] (BASF Corporation, IRGAME T 39)

(Evaluation of Lubricating Oil Composition)

[0087] The thus prepared lubricating oil compositions were subjected to the following evaluation, and the results were described in tables 2 and 3.

(Biodegradability Test)

[0088] Biodegradability test was performed according to OECD 301C. In the case that the biodegradability measured by the test is 60 percent or higher, it is qualified 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 marked as X in the case that the biodegradability is below 60 percent, it is marked as in the case that the biodegradability is 60 percent or higher and below 70 percent, and it is marked as in the case that the biodegradability is 70 percent or higher.

[0089] (Oxidation Stability: RPVOT Test)

[0090] It was performed rubricating oil oxidation stability test (RPVOT test) based on Japanese industrial standards JIS K2514-3 (2013). The numerical values described in the tables indicate time periods (minutes) required for the pressure to be lowered from the maximum pressure by 175 kPa. As the numerical value is larger, the oxidation stability is better.

(Wear Resistance: Shell Four-Ball Wear Test)

[0091] 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.

(Rust-Prevention Performance Test)

[0092] The rust-prevention performance test (Artificial sea water) of the lubricant oils was performed according to Japanese Industrial Standards JIS K2510. Although the test is completed in 24 hours conventionally, the test was continued for 2 weeks and then the results of the prevention of rust are evaluated after the 2 weeks. According to the test, is marked in the case that the rust is not observed, and X is marked in the case that the rust was observed.

TABLE-US-00002 TABLE 2 Comparative Inventive Examples Examples 1 2 3 4 5 6 1 2 base oil ester compound I I II III IV V I I (mass parts) 100 100 100 100 100 100 100 100 Additives Wear (B) monodihexyl phosphateC11-14 0.5 0 0.3 0 0.5 0.5 0 0 (mass prevention branched alkyl amine salt parts) agent (B) Branched butyl phosphateC12 to C14 0 0.5 0 1.0 0 0 0 0 branched alkyl amine salt tridecyl acid phosphatetrioctylamine salt 0 0 0 0 0 0 0 0.5 Rust-prevention (C) Monoester of monopropenyltripropyl 0.15 0.15 0.15 0.10 0.15 0.15 0.15 0.15 agent succinic acid and 1,2-propanediol Dodecenyl succinic acid alkylimide 0 0 0 0 0 0 0 0 N-oleoyl sarcosine 0 0 0 0 0 0 0 0 N--hydroxyethyl oleyl imidazoline 0 0 0 0 0 0 0 0 Oxidation dibutyl hydroxytoluene 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 prevention (BHT) agent Metal Benzotriazole derivative 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 deactivator Per- Biodegradability test formance Oxidation stability (RPVOT) (min.) 247 251 218 350 265 218 240 235 Wear resistance (Wear scar diameter) (m) 311 359 362 298 305 415 688 574 Rust-prevention performance None None None None None None None None (Artificial sea water: Presence or absence of rust after 2 weeks)

TABLE-US-00003 TABLE 3 Comparative Examples 3 4 5 6 7 8 9 10 base oil ester compound II II II III III III IV VI (mass parts) 100 100 100 100 100 100 100 100 Additives Wear (B) monodihexyl phosphateC11-14 0 0 0 0 0 0 0 0.5 (mass prevention branched alkyl amine salt parts) agent (B) Branched butyl phosphateC12 to C14 0.5 0.5 0.5 0 5.0 1.0 5.0 0 branched alkyl amine salt tridecyl acid phosphatetrioctylamine salt 0 0 0 1.0 0 0 0 0 Rust-prevention (C) Monoester of monopropenyltripropyl 0 0 0 0 0.15 3.0 3.0 0.15 agent succinic acid and 1,2-propanediol Monoeater of dodecenylsuccinic acid 0.15 0 0 0 0 0 0 0 and lauric acid Dodecenyl succinic acid alkylimide 0 0.15 0 0 0 0 0 0 N-oleoyl sarcosine 0 0 0.15 0 0 0 0 0 N--hydroxyethyl oleyl imidazoline 0 0 0 0.15 0 0 0 0 Oxidation dibutyl hydroxytoluene (BHT) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 prevention agent Metal Benzotriazole derivative 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 deactivator Per- Biodegradability test X formance Oxidation stability (RPVOT) (min.) 222 256 245 232 110 248 249 38 Wear resistance (Wear scar diameter) (m) 370 361 353 692 315 510 545 298 Rust-prevention performance Present Present Present Present Absent Absent Absent Present (Artificial sea water: Presence or absence of rust after 2 weeks)

[0093] As described in the inventive examples 1 to 6 shown in table 2, it is proved that the lubricating oil composition of the present invention is excellent in biodegradability, rust-prevention performance against sea water, oxidation stability and lubricating property (wear resistance) upon adding various kinds of the additives.

[0094] According to the comparative example 1, as (B) the amine salt of the acidic phosphoric ester is not contained, the wear resistance of the lubricating oil composition is low.

[0095] According to the comparative example 2, (B) the amine salt of the acidic phosphoric acid ester is not contained and instead tridecyl acid phosphatetrioctylamine salt is contained. As a result, the wear resistance of the lubricating oil composition is low.

[0096] According to the comparative examples 3 to 6, (C) the monoesterified compound is not contained and the other components listed in table 3 are contained. As a result, the rust-prevention performance of each of the lubricating oil compositions is low and rust is generated.

[0097] According to the comparative example 7, the content of (B) the amine salt of the acidic phosphoric ester is high, and the oxidation stability of the lubricating oil composition is low.

[0098] According to the comparative example 8, the content of (C) monoesterified compound is high, and the wear resistance of the lubricating oil composition is low.

[0099] According to the comparative example 9, the contents of (B) the amine salt of the acidic phosphoric acid ester and (C) the monoesterified compound are high, and the wear resistance and biodegradability of the lubricating oil composition are low.

[0100] According to the comparative example 10, caprylic acid, capric acid and adipic acid are not blended and instead oleic acid and dimer acid are blended into the ester compound VI, the oxidation stability and rust-prevention performance of the lubricating oil composition are low.

Inventive Examples 7, 8 and 9

[0101] In the lubricating oil composition of the inventive example 1, as shown in table 4, only the oxidation prevention agent was changed to obtain each of the lubricating oil compositions of the inventive examples 7, 8 and 9. However, as shown in table 4, in the inventive examples 7, 8 and 9, a phenol-based oxidation prevention agent (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxypheny)-propionate]) was used. In the inventive examples 8 and 9, it was further used an amine-based oxidation prevention agent (4,4-bis(,-dimethyl benzyl) diphenylamine-4,4-dicumyl diphenyl amine or polymerized product of 2,2,4-trimethyl-1,2-dihydroquinoline). It was then performed measurements as the inventive examples 1 to 6, and the results are shown in table 4.

TABLE-US-00004 TABLE 4 Inventive Examples 7 8 9 base oil ester compound I I I (mass parts) 100 100 100 Additives Wear (B) monodihexyl phosphateC11-14 branched alkyl amine salt 0.5 0.5 0.5 (mass prevention (B) Branched butyl phosphateC12 to C14 branched alkyl amine salt 0 0 0 parts) agent tridecyl acid phosphatetrioctylamine salt 0 0 0 Rust- (C) Monoester of monopropenyltripropyl succinic acid and 1,2-propanediol 0.15 0.15 0.15 prevention Dodecenyl succinic acid alkylimide 0 0 0 agent N-oleoyl sarcosine 0 0 0 N--hydroxyethyl oleyl imidazoline 0 0 0 Oxidation pentaerythritol tetrakis 0.5 0.5 0.5 prevention [3-(3,5-di-tert-butyl-4-hydroxypheny)-propionate]) agent (4,4-bis(,-dimethyl benzyl) diphenylamine-4,4-dicumyl diphenyl amine 0 1 0 polymerized product of 2,2,4-trimethyl-1,2-dihydroquinoline 0 0 1 Metal deactivator Benzotriazole derivative 0.05 0.05 0.05 Performance Oxidation stability (RPVOT) (min.) Oxidation stability (RPVOT)(min.) 252 1140 995 Wear resistance: (Wear scar diameter)(m) 308 325 318 Rust-prevention performance (Artificial sea water: Present Present Present Presence or absence of rust after 2 weeks)

[0102] Further, as shown in table 4, the lubricating oil compositions of the inventive examples 7, 8 and 9 are excellent in biodegradability, rust-prevention performance against sea water, oxidation stability and lubricating property (wear resistance). In addition to this, it is proved that the oxidation stability of the lubricating oil composition of the present invention can be further improved by using the phenol-based oxidation prevention agent and amine-based oxidation prevention agent in combination,

INDUSTRIAL APPLICABILITY

[0103] The lubricating oil composition of the present invention is excellent in biodegradability, rust-prevention performance against sea water, oxidation stability and lubricating property (wear resistance), and may be preferably used for a bearing oil, hydraulic oil, gear oil or the like used in ocean-surrounding regions. It is thereby possible to reduce the load onto environment even in the case that the composition is leaked out, to maintain sufficiently high rust-prevention performance and to prevent failure of an apparatus in the case that the composition is contaminated with sea water.