Lubricating oil composition

Abstract

A lubricating oil composition containing a lubricating base oil and on the basis of the total mass of the composition, (A) a boron-containing ashless dispersant in an amount of 100 to 500 ppm by mass as boron, (B) a phosphorous additive in an amount of 300 to 800 ppm by mass as phosphorus, (C) an amide- and/or imide-based friction modifier in an amount of 1 to 4 percent by mass, and (D) an alkali metal- and/or alkaline earth metal-based detergent in an amount of 100 to 300 ppm by mass as metal, and having a 40 C. kinematic viscosity of 30 mm2/s or lower is provided. The lubricating oil composition, which has a low viscosity to improve fuel efficiency, also has superior anti-wear, anti-seizure, and anti-shattering properties, even when the composition is degraded by oxidation or by the elution of compounds from sealing materials after long term use.

Claims

1. A lubricating oil composition comprising a lubricating base oil and on the basis of the total mass of the composition, (A) a boron-containing ashless dispersant in an amount of 100 to 500 ppm by mass as boron, (B) a phosphorus additive in an amount of 300 to 800 ppm by mass as phosphorus, (C) an amide- and/or imide-based friction modifier in an amount of 1 to 4 percent by mass, and (D) an alkali metal- and/or alkaline earth metal-based detergent in an amount of 100 to 300 ppm by mass as metal, wherein the composition has a 40 C. kinematic viscosity of 25 mm.sup.2/s or lower and a 100 C. kinematic viscosity of 6.5 mm.sup.2/s or lower, wherein Component (B) comprises a combination of a phosphite ester and phosphoric acid having a ratio ([P2]/[P1]) of the phosphorus amount [P2] of the phosphoric acid to the phosphorus amount [P1] of the phosphite ester of 0.2 to 1.0; wherein Component (D) comprises a metallic detergent having a base number of less than 150 mgKOH/g and has a ratio ([M]/[P]) of the metal amount [M] of the metallic detergent to the phosphorus amount [P] of Component (B) of 0.06 to 0.25; wherein the phosphite ester is a phosphite ester having an (alkyl)aryl group having 6 to 12 carbon atoms and the metallic detergent is a calcium sulfonate detergent.

2. The lubricating oil composition according to claim 1, wherein Component (D) further comprises a metallic detergent having a base number of 200 mgKOH/g or greater.

3. The lubricating oil composition according to claim 1, further comprising (E) a thiadiazole in an amount of 250 to 1000 ppm by mass as sulfur on the basis of the total mass of the composition.

4. The lubricating oil composition according to claim 1, wherein the composition is used in a vehicle transmission.

5. The lubricating oil composition according to claim 1, wherein the amide-based friction modifier of Component (C) comprises compounds represented by formula (3): ##STR00004## wherein R.sup.2 is a hydrocarbon or functionalized hydrocarbon group having 1 to 30 carbon atoms, R.sup.3 is a hydrocarbon or functionalized hydrocarbon group having 1 to 30 carbon atoms or hydrogen and R.sup.4 is a divalent hydrocarbon or functionalized divalent hydrocarbon group having 1 to 10 carbon atoms.

6. The lubricating oil composition according to claim 5, wherein in formula (3), R.sup.3 is hydrogen.

7. The lubricating oil composition according to claim 1, wherein the imide-based friction modifier of Component (C) comprises compounds represented by formula (4) or (5): ##STR00005## wherein R.sup.5 and R.sup.6 are each independently an alkyl or alkenyl group having 8 to 30 carbon atoms, R.sup.7 and R.sup.8 are each independently an alkylene group having 1 to 4 carbon atoms, R.sup.9 is hydrogen or an alkyl or alkenyl group having 1 to 30 carbon atoms and n is an integer of 1-7.

8. The lubricating oil composition according to claim 1, wherein Component (D) further comprises a metallic detergent having a base number of 200 mgKOH/g or greater and is a calcium salicylate detergent.

Description

EXAMPLES

(1) Hereinafter, the present invention will be described in more detail by way of the following examples and comparative examples, which should not be construed as limiting the scope of the invention.

(2) The base oils and various additives used in examples and comparative examples are as follows.

(3) [Base Oil]

(4) (1) Mineral oil A: 100 C. kinematic viscosity 2.5 mm.sup.2/s, viscosity index 96, S content 0.1 percent by mass or less

(5) (2) Mineral oil B: 100 C. kinematic viscosity 4.2 mm.sup.2/s, viscosity index 125, S content 0.1 percent by mass or less

(6) [Component A]

(7) (1) Boron-containing succinimide: Mw 3200, N content 2.2 percent by mass, B content 0.46 percent by mass, bis compound

(8) [Component B]

(9) (1) Phosphite ester: diphenyl hydrogen phosphite

(10) (2) Phosphoric Acid

(11) [Component C]

(12) (1) Amide-based friction modifier: reaction product of glycolic acid and an amine containing octadecylamine as the main component

(13) (2) Imide-based friction modifier: reaction product of tetradecylsuccinic anhydride and triethylenetetramine

(14) [Component D]

(15) (1) Low base number detergent: calcium sulfonate, base number 15 mgKOH/g, Ca content 2.5 percent by mass

(16) (2) High base number detergent A: calcium salicylate, base number 225 mgKOH/g, Ca content 8.0 percent by mass

(17) (3) High base number detergent B: calcium sulfonate, base number 300 mgKOH/g, Ca content 12.0 percent by mass

(18) [Component E]

(19) (1) Thiadiazole: 1,3,4-thiadiazole compound

(20) [Other Performance Additives]

(21) (1) Mixture of anti-oxidant, viscosity index improver, friction modifier, sealing agent, and metal deactivator

Examples 1 to 11 and Comparative Examples 1 to 8

(22) Lubricating oil compositions of Examples 1 to 11 (prepared to have a 100 C. kinematic viscosity of 5.5 mm.sup.2/s) set forth in Table 1 and those of Comparative Examples 1 to 8 for comparison set forth in Table 2 were prepared and evaluated in respect of (1) anti-wear properties and (2) anti-seizure properties (extreme pressure properties) when they were fresh and after they were subjected to an oxidation stability test and a rubber immersion test. The results are also set forth in Tables 1 and 2. The ratio of each base oil is on the basis of the total mass of the oil, and the amount of each additive is on the basis of the total mass of the composition.

(23) (1) Anti-Wear Properties

(24) Anti-wear properties were evaluated by measuring the wear scar diameter in a Shell four-ball test in accordance with ASTM D4172 where the load was 392 N, the revolution number was 1900 rpm and the oil temperature was 100 C. and the balls are slid to each other for one hour.

(25) (2) Anti-Seizure Properties

(26) Anti-seizure properties were evaluated by measuring the weld load (WL) in a Shell four-ball test in accordance with ASTM D2783 at a revolution number of 1800 rpm and room temperature.

(27) (3) Oxidation Stability Test

(28) An oxidation stability test was carried out at an oil temperature of 150 C. for 96 hours in accordance with JIS K 2514.

(29) (4) Sealing Material Immersion Test

(30) A sealing material immersion test was carried out by immersing an acrylic rubber material (T712) in oil kept at a temperature of 150 C. for 240 hours in accordance with JIS K 6258.

(31) (5) Anti-Shudder Life

(32) Anti-shudder life was evaluated with JASO M349-2010.

(33) As apparent from the results set forth in Tables 1 and 2, the compositions of the examples according to the present invention have been found to have high load bearing properties equivalent to those of the compositions when they are fresh even after being subjected the oxidation stability test and rubber immersion test. Whilst, the comparative examples do not meet any of the structural requirements of the present invention and thus were extremely poor in anti-wear properties and/or anti-seizure properties compared with those of the composition when they are fresh after being subjected to the oxidation stability test and/or rubber immersion test.

(34) TABLE-US-00001 TABLE 1 Example Example Example Example Example Example Example Example Example Example Example 1 2 3 4 5 6 7 8 9 10 11 Lubricating Mineral oil A % 60 60 60 60 60 60 60 60 60 60 60 base oil Mineral oil B % 40 40 40 40 40 40 40 40 40 40 40 Performance A Boron-containing succinimide [B] ppm/B 250 150 450 250 250 250 250 250 250 250 250 additives B Phosphoric acid [P2] ppm/P 200 200 200 100 100 50 350 0 200 100 200 Phosphite ester [P1] ppm/P 400 200 600 500 300 550 250 600 600 400 400 Phosphorus amount Total [P] ppm/P 600 400 800 600 400 600 600 600 800 500 600 P ratio: [P2]/[P1] 0.5 1 0.33 0.2 0.33 0.09 1.4 0 0.33 0.25 0.5 A/B Boron-containing succinimide [B]]/ 0.42 0.38 0.56 0.42 0.63 0.42 0.42 0.42 0.31 0.5 0.42 Phosphorus additive [P] C Amide-based FM mass % 3 4 2 3 3 3 3 3 3 Imide-based FM mass % 2 3 D Ca sulfonate (less than 50 mgKOH/g) ppm/Ca 100 50 50 50 100 100 100 100 30 150 0 Ca salicylate (200 mgKOH/g) ppm/Ca 100 200 200 100 100 100 100 100 200 Ca sulfonate (400 mgKOH/g) ppm/Ca 50 100 Ca amount Total 200 250 250 100 200 200 200 200 130 250 200 D/B Low base number Ca amount/ 0.167 0.125 0.063 0.083 0.25 0.167 0.167 0.167 0.038 0.3 0 Phosphorus amount [P] E Thiadiazole ppm/S 540 360 900 540 540 540 540 540 540 540 540 Others Other performance additives 9 9 9 9 9 9 9 9 9 9 9 40 C. kinematic viscosity mm.sup.2/s 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 100 C. kinematic viscosity mm.sup.2/s 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 Test Anti-wear properties Fresh oil mm 0.38 0.42 0.42 0.43 0.42 0.46 0.47 0.48 0.51 0.48 0.55 Oxidation stability test: mm 0.39 0.42 0.44 0.44 0.44 0.48 0.48 0.48 0.52 0.52 0.56 after ISOT degradation Sealing material immersion mm 0.39 0.43 0.43 0.44 0.44 0.48 0.48 0.49 0.53 0.52 0.57 test: after immersion Anti-seizure properties Fresh oil N 1961 1961 1961 1961 1961 1961 1961 1961 1961 1961 1569 Oxidation stability test: N 1961 1961 1961 1961 1961 1961 1961 1961 1961 1569 1569 after ISOT degradation Sealing material immersion N 1961 1961 1961 1961 1961 1961 1961 1961 1961 1569 1569 test: after immersion Anti-shudder life h >300 >300 >300 >300 >300 >300 >300 >300 >300 >300 >300

(35) TABLE-US-00002 TABLE 2 Compar- Compar- Compar- Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative ative ative ative Example Example Example Example Example Example Example Example 1 2 3 4 5 6 7 8 Lubri- Mineral oil A % 60 60 60 60 60 60 60 60 cating Mineral oil B % 40 40 40 40 40 40 40 40 base oil Perform- A Boron-containing ppm/B 50 600 250 250 250 250 250 250 ance succinimide [B] additives B Phosphoric acid [P2] ppm/P 200 200 100 300 200 200 100 200 Phosphorus acid ester [P1] ppm/P 200 400 100 600 400 400 300 400 Phosphorus amount Total [P] ppm/P 400 600 200 900 600 600 400 600 P ratio: [P2]/[P1] 1 0.5 1 0.5 0.5 0.5 0.33 0.5 A/B Boron-containing succinimide 0.13 1 1.25 0.28 0.42 0.42 0.63 0.42 [B]]/Phosphorus additive [P] C Amide-based FM mass % 3 3 3 3 0.5 5 3 3 Imide-based FM mass % D Ca sulfonate (less than ppm/Ca 100 100 50 100 100 100 30 50 50 mgKOH/g) Ca salicylate ppm/Ca 150 100 100 100 100 100 50 300 (200 mgKOH/g) Ca sulfonate ppm/Ca (400 mgKOH/g) Ca amount Total 250 200 150 200 200 200 80 350 D/B Low base number Ca amount/ 0.25 0.167 0.25 0.111 0.167 0.167 0.075 0.083 Phosphorus amount [P] E Thiadiazole ppm/S 540 540 540 540 540 540 540 540 Others Other performance additives 9 9 9 9 9 9 9 9 40 C. kinematic viscosity mm.sup.2/s 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 100 C. kinematic viscosity mm.sup.2/s 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 Test Anti-wear properties Fresh oil mm 0.54 0.54 0.65 0.51 0.61 0.52 0.54 0.58 Oxidation stability test: mm 0.54 0.65 0.66 0.52 0.61 0.54 0.68 0.61 after ISOT degradation Sealing material immersion mm 0.61 0.54 0.64 0.65 0.6 0.65 0.55 0.6 test: after immersion Anti-seizure properties Fresh oil N 1569 1569 1569 1961 1569 1961 1569 1569 Oxidation stability test: N 1569 1236 1569 1569 1569 1569 1236 1569 after ISOT degradation Sealing material immersion N 1236 1569 1569 1236 1569 1236 1569 1569 test: after immersion Anti-shudder life h >300 216 >300 288 144 >300 >300 240