Lubricant composition for gasoline engine and method for producing same

Abstract

Provided is a lubricating oil composition having excellent detergency and LSPI preventing performance, and specifically a lubricating oil composition including a base oil, a calcium detergent, and a magnesium detergent and/or a sodium detergent, wherein the content of the calcium detergent as converted into a calcium atom and a mass ratio of a magnesium atom (Mg) contained in the magnesium detergent and/or a sodium atom (Na) contained in the sodium detergent to a calcium atom (Ca) [(Mg and/or Na)/Ca] fall within the specific ranges.

Claims

1. A method, comprising lubricating a gasoline engine using a lubricating oil composition comprising: a base oil; a calcium salicylate; a magnesium sulfonate; a boron-containing succinimide; and optionally a non-borated succinimide, wherein: at least 220 ppm by mass of boron from the boron-containing succinimide is present; a content of the base oil is 70 mass % or more based on a whole amount of the composition; the calcium salicylate is the only calcium detergent present in the lubricating oil composition and a content of the calcium salicylate as converted into a calcium atom content is 800 to less than 2,000 ppm by mass based on the whole amount of the composition; the magnesium sulfonate is the only magnesium detergent present in the lubricating oil composition and a content of the magnesium sulfonate as converted to a magnesium atom content is 100 to 1,500 ppm by mass based on the whole amount of the composition; a mass ratio of the magnesium atom content, to the calcium atom content is 0.05 to 1.00; a content of nitrogen in the lubricating oil composition is less than 0.16 mass %; the lubricating oil composition has a kinematic viscosity at 100 C. of 3.8 to 12.5 mm.sup.2/s; wherein a maximum value of a heat flow of the lubricating oil composition is 325.5 mW or less, based on an amount of heat flow that occurs following a temperature rise from ambient temperature to 400 C. at a rate of 10 C./min, when 5 mg of the lubricating oil composition is applied to an aluminum pan, and a high-pressure differential scanning calorimeter is used to measure the heat flow at an air pressure of 10 atm; and a score of the hot tube test at 300 C. of the lubricating oil composition measured based on JPI-5S-55-99 is 7 or more.

2. The method according to claim 1, wherein the lubricating oil composition further comprises: a poly(meth)acrylate.

3. The method according to claim 1, wherein the content of the calcium salicylate in the lubricating oil composition, as converted into the calcium atom content, is 800 to 1,500 ppm by mass based on the whole amount of the composition.

4. The method according to claim 1, wherein the content of the magnesium sulfonate as converted to the magnesium atom content is 300 to 1000 ppm by mass or more based on the whole amount of the composition.

5. The method according to claim 1, wherein the lubricating oil composition comprises the non-borated succinimide and the boron-containing succinimide.

6. The method according to claim 5, wherein the content of nitrogen in the lubricating oil composition is 0.01 mass % or more to less than 0.16 mass %.

7. The method according to claim 5, wherein the lubricating oil composition comprises 600 ppm by mass or less of the boron-containing succinimide as converted into a boron atom content based on the whole amount of the composition.

8. The method according to claim 1, wherein a total base number of the magnesium sulfonate in the lubricating oil composition, by the perchloric acid method as prescribed in JIS K2501, is 150 to 650 mg/KOH.

9. The method according to claim 1, wherein the base oil is at least one selected from the group consisting of a mineral oil and a synthetic oil which are classified into Groups 3 to 5 of the base stock categories of the API (American Petroleum Institute).

10. The method according to claim 1, wherein the kinematic viscosity at 100 C. of the lubricating oil composition is 4.0 to 11.0 mm.sup.2/s.

11. The method according to claim 1, wherein the calcium salicylate consists of an overbased calcium salicylate.

12. A lubricating oil composition, comprising a base oil; a calcium salicylate; a magnesium sulfonate; a boron-containing succinimide; and optionally a non-borated succinimide, wherein: at least 220 ppm by mass of boron from the boron-containing succinimide is present; a content of the base oil is 70 mass % or more based on a whole amount of the composition; the calcium salicylate is the only calcium detergent present in the lubricating oil composition and a content of the calcium salicylate as converted into a calcium atom content is 800 to less than 2,000 ppm by mass based on the whole amount of the composition; the magnesium sulfonate is the only magnesium detergent present in the lubricating oil composition and a content of the magnesium sulfonate as converted to a magnesium atom content is 100 to 1,500 ppm by mass based on the whole amount of the composition; a mass ratio of the magnesium atom content, to the calcium atom content is 0.05 to 1.00; a content of nitrogen in the lubricating oil composition is less than 0.16 mass %; the lubricating oil composition has a kinematic viscosity at 100 C. of 3.8 to 12.5 mm.sup.2/s; a total content of non-borated succinimide and boron-containing succinimide, as converted into a nitrogen atom, is less than 0.07 mass %; wherein a maximum value of a heat flow of the lubricating oil composition is 325.5 mW or less, based on an amount of heat flow that occurs following a temperature rise from ambient temperature to 400 C. at a rate of 10 C./min, when 5 mg of the lubricating oil composition is applied to an aluminum pan, and a high-pressure differential scanning calorimeter is used to measure the heat flow at an air pressure of 10 atm; and a score of the hot tube test at 300 C. of the lubricating oil composition measured based on JPI-5S-55-99 is 7 or more.

Description

EXAMPLES

(1) The present invention is hereunder described in more detail by reference to Examples, but it should be construed that the present invention is by no means limited by these Examples. The content of each of atoms of lubricating oil compositions prepared in the Examples and Comparative Examples, the HTHS viscosity at 150 C. and the kinematic viscosity at 100 C. of lubricating oil compositions were measured and evaluated by the following methods.

(2) [Content of Each of Atoms of Lubricating Oil Composition]

(3) (Contents of Calcium Atom, Magnesium Atom, Sodium Atom, Phosphorus Atom, and Boron Atom)

(4) The measurement was performed in conformity with JIS-5S-38-92.

(5) (Content of Nitrogen Atom)

(6) The measurement was performed in conformity with JIS K2609.

(7) [HTHS Viscosity at 150 C. (High Temperature High Shear Viscosity)]

(8) A viscosity after shearing a lubricating oil composition as a measuring object at 150 C. and at a shear rate of 10.sup.6/s was measured in conformity with ASTM D4741.

(9) [Measurement of Kinematic Viscosity at 100 C.]

(10) A value as measured using a glass capillary viscometer in conformity with JIS K2283-2000.

Examples 1 to 10 and Comparative Examples 1 to 3

(11) In Examples 1 to 10, a base oil and various additives of the kinds and blending amounts shown in Table 1 were blended, and in Comparative Examples 1 to 3, a base oil and various additives of the kinds and blending amounts shown in Table 2 were blended, thereby preparing lubricating oil compositions having an HTHS viscosity at 150 C. of 2.6 mPa.Math.s, respectively.

(12) (Evaluation of Detergency)

(13) With respect to these lubricating oil compositions thus prepared, a hot tube test at 300 C. was performed based on the following method, thereby evaluating the detergency. The results are shown in Tables 1 and 2.

(14) (Hot Tube Test (at 300 C.))

(15) The measurement was performed by setting the test temperature to 300 C. and making other conditions in conformity with those of JPI-5S-55-99. Conforming to JPI-5S-55-99, a lacquer attached to a test tube after the test was evaluated between Point 0 (black) and Point 10 (colorless) and evaluated on 11 grades. It is meant that as the numerical value is larger, a deposit is less, and the detergency becomes better. As for the grade point, Points 7 or more are evaluated to be acceptable.

(16) (LSPI Preventing Performance of Lubricating Oil Composition)

(17) With respect to the lubricating oil composition of each of the Examples and Comparative Examples, a maximum value of a heat flow was measured based on the following method, thereby evaluating the LSPI preventing performance based on the maximum value of the heat flow. The results are shown in Tables 1 and 2.

(18) (Measurement of Maximum Value of Heat Flow)

(19) With respect to the prepared lubricating oil compositions, the generation of a heat flow following a temperature rise was analyzed using a high-pressure differential scanning calorimeter. A material in which 5 mg of a test oil was dropped in an aluminum pan was used as a measurement sample, an aluminum pan in which a test oil was not dropped was used as a standard. An air pressure was set to 10 atm, and the measurement was performed in an air atmosphere. The temperature rise was performed to 400 C. at a rate of 1.0 C./min. In general, when the temperature is raised, a lubricating oil composition causes the momentary heat generation at a specified temperature and burns. As the amount of heat generation on the occasion of causing the momentary heat generation at that time is larger, a combustion reaction is liable to be caused within a combustion chamber, namely LSPI is liable to be induced. Then, a maximum value of the heat flow corresponding to a heat generation rate was determined on a basis of the amount of heat generation on the occasion of causing the momentary heat generation. It may be said that as the maximum value is smaller, the LSPI preventing performance is more favorable. Values of 325.5 mW or less are evaluated to be acceptable.

(20) TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 Composi- Base oil Balance Balance Balance Balance Balance Balance Balance Balance Balance Balance tion Detergent A mass % 1.90 1.90 1.90 1.90 1.90 1.90 1.90 1.90 1.00 2.30 Detergent B mass % 0.11 0.32 1.08 1.62 0.32 0.32 Detergent C mass % 0.05 0.15 0.51 0.77 Viscosity index improver mass % 10.90 10.80 10.30 10.00 10.90 10.80 10.40 10.20 11.20 10.50 Pour-point depressant mass % 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 Anti-wear agent mass % 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 Dispersant A mass % 4.00 4.00 4.00 4.00 4.00 4.00 4.00 4.00 4.00 4.00 Dispersant B mass % 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 Antioxidant A mass % 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 Antioxidant B mass % 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 Other additives mass % 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Properties Calcium content ppmCa 1500 1500 1500 1500 1500 1500 1500 1500 800 1800 Magnesium atom content ppmMg 100 300 1000 1500 300 300 Sodium atom content ppmNa 100 300 1000 1500 (Mg + Na)/Ca *.sup.1 0.067 0.20 0.67 1.00 0.067 0.20 0.67 1.00 0.38 0.17 Nitrogen content *.sup.2 ppmN 650 650 650 650 650 650 650 650 650 650 Anti-wear agent ppmP 800 800 800 800 800 800 800 800 800 800 Dispersant A ppmN 400 400 400 400 400 400 400 400 400 400 Dispersant B ppmN 250 250 250 250 250 250 250 250 250 250 HTHS viscosity at 150 C. mPa .Math. s 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6 Kinematic viscosity at mm.sup.2/s 7.62 7.62 7.57 7.56 7.61 7.62 7.55 7.53 7.59 7.62 100 C. Evaluation Evaluation of detergency *.sup.3 7 8 8 8 9 9 9 10 7 8 Evaluation of LSPI preventing 325.4 324.5 324.2 324.2 325.3 324.5 324.2 324.0 324.4 325.1 performance *.sup.4

(21) TABLE-US-00002 TABLE 2 Comparative Example 1 2 3 Compo- Base oil Balance Balance Balance sition Detergent A mass % 3.10 1.90 0.40 Detergent B mass % 0.32 0.87 Detergent C mass % Viscosity index mass % 10.10 11.40 11.60 improver Pour-point mass % 0.20 0.20 0.20 depressant Anti-wear agent mass % 1.10 1.10 1.10 Dispersant A mass % 4.00 4.00 4.00 Dispersant B mass % 2.00 2.00 2.00 Antioxidant A mass % 0.50 0.50 0.50 Antioxidant B mass % 1.25 1.25 1.25 Other additives mass % 0.25 0.25 0.25 Properties Calcium content ppmCa 2400 1500 300 Magnesium ppmMg 300 800 atom content Sodium atom ppmNa content (Mg + Na)/Ca *.sup.1 0.13 2.67 Nitrogen ppmN 650 650 650 content *.sup.2 Anti-wear agent ppmP 800 800 800 Dispersant A ppmN 400 400 400 Dispersant B ppmN 250 250 250 Pour-point ppmN 420 420 420 depressant HTHS viscosity mPa .Math. s 2.6 2.6 2.6 at 150 C. Kinematic mm.sup.2/s 7.65 7.62 7.56 viscosity at 100 C. Evaluation Evaluation of 8 7 6 detergency *.sup.3 Evaluation of 326.1 325.8 LSPI preventing performance *.sup.4 (Note) The abbreviations and materials used, and so on in Tables 1 and 2 are as follows. ppmCa, ppmMg, ppmNa, ppmP, ppmN, and ppmB express the contents (ppm by mass) as converted into a calcium atom (Ca), a magnesium atom (Mg), a sodium atom (Na), a phosphorus atom (P), a nitrogen atom (N), and a boron atom (B), respectively. *.sup.1 (Mg + Na)/Ca expresses a mass ratio of the magnesium atom (Mg) and/or the sodium atom (Na) to the calcium atom (Ca) [(Mg and/or Na)/Ca]. *.sup.2 The nitrogen content is a sum total of the nitrogen contents contained in the dispersants A and B. *.sup.3 The numerical value in the column of evaluation of detergency is a grade point of the hot tube test (at 300 C.). *.sup.4 The numerical value in the column of evaluation of LSPI preventing performance is a value of the maximum value (mW) of the heat flow.

(22) The base oil and various additives used for preparing the lubricating oil composition of each of the Examples and Comparative Examples shown in Tables 1 and 2 are as follows. Base oil: Mineral oil classified into Group III of the base stock categories of the API, kinematic viscosity at 100 C.=4 mm.sup.2/s Detergent A: Overbased calcium salicylate, base number (by the perchloric acid method): 225 mgKOH/g, calcium content: 7.8 mass % Detergent B: Overbased magnesium sulfonate, base number (by the perchloric acid method): 410 mgKOH/g, magnesium content: 9.4 mass %, sulfur content: 2.0 mass % Detergent C: Overbased sodium sulfonate, base number (by the perchloric acid method): 450 mgKOH/g, sodium content: 19.5 mass %, sulfur content: 1.2 mass % Viscosity index improver: Polymethacrylate (PMA, Mw=430,000, Mn=130,000, Mw/Mn=3.3, resin component concentration: 17 mass %) Pour-point depressant: Polymethacrylate (PMA, Mw=50,000, Mn=30,000, Mw/Mn=1.7, resin component concentration: 66 mass %) Anti-wear agent: Primary alkyl ZnDTP (phosphorus content: 7.3 mass %, zinc content: 8.4 mass %) Dispersant A: Succinimide (polybutenyl succinic acid bisimide), nitrogen content: 1 mass % Dispersant B: Boron-containing succinimide (boron-containing polybutenyl succinic acid bisimide), nitrogen content: 1.23 mass %, boron content: 1.3 mass % Antioxidant A: Hindered phenol-based antioxidant Antioxidant B: Diphenylamine-based antioxidant Others: Defoaming agent and metal deactivator

(23) As shown in Table 1, it was confirmed that in the lubricating oil compositions of the Examples, the grade point of the hot tube test is high as 7 to 10, and the maximum value of the heat flow is 325.5 mW or less, and hence, the lubricating oil compositions of the Examples are excellent in not only detergency and LSPI preventing performance.

(24) On the other hand, as shown in Table 2, it was confirmed that in the lubricating oil composition of Comparative Example 1 in which the calcium detergent was excessively added, the maximum value of the heat flow is 326.1 mW, a value of which is more than 325.5 mW, and hence, the lubricating oil composition of Comparative Example 1 is inferior in LSPI preventing performance; and that the lubricating oil composition of Comparative Example 2 not containing the magnesium detergent and the sodium detergent is inferior in LSPI preventing performance. In addition, it was confirmed that in the lubricating oil composition of Comparative Example 3 in which the magnesium detergent was excessively contained, the grade point of the hot tube test is low as 6, and hence, the lubricating oil composition of Comparative Example 3 is inferior in detergency.