JP4916687B2 - engine oil - Google Patents

Description

The present invention relates to engine oil.

The engine oil includes, for example, a base oil containing a lubricant such as hexagonal boron nitride (hereinafter referred to as “hBN”), graphite, molybdenum disulfide, tetrafluoroethylene resin (PTFE), and an organic molybdenum compound. There are advantages and disadvantages depending on the type of lubricant. Graphite and molybdenum disulfide have good heat resistance but are black and opaque, so it is difficult to determine the deterioration time of engine oil. Moreover, since molybdenum disulfide has a large specific gravity, there is a problem that it tends to precipitate in engine oil. PTFE is white and has low friction, but generates hydrogen fluoride that decomposes at a low temperature of about 300 ° C. and corrodes the metal constituting the engine. Since the organomolybdenum compound is a liquid, there is no problem of precipitation like a solid lubricant, and there is an advantage that it enters into a narrow gap, but the heat-resistant temperature is as low as 200 ° C. or less.

On the other hand, since hBN is a white powder, it is easy to determine the deterioration time of the engine oil, and since the specific gravity is small, it is difficult to settle, is stable up to around 1000 ° C., and has a cleavage property due to the scale shape. So it has excellent lubricity. However, when pulverized to 1 μm or less in order to improve dispersibility in engine oil, the scale shape is lost and the cleaving property is reduced, so that the lubricating performance is not improved as expected, but rather boron atoms (B) and nitrogen atoms. There is a concern that the wear resistance is expressed by the strong covalent bond (N) and the engine is damaged.

Therefore, the average particle size is more than 1.0 μm to 3.0 μm or less, the maximum particle size is 15 μm or less, the graphitization index (GI) by powder X-ray diffraction method is 4.0 or less, and the boron oxide content is 0.5 to 5 It has been proposed that hBN powder in mass% is used as a lubricant for engine oil (Patent Document 1). As a result, the above problems have been considerably improved, but there is still room for improvement in order to satisfy today's demands for further improvement in fuel consumption (improvement of economy) and output (improvement in comfort).
JP 2003-336087 A

An object of the present invention is to provide an engine oil with further improved fuel efficiency and output.

The present invention is an engine oil comprising a base oil containing hBN powder having a sedimentation rate defined below of 5% or less. The present invention also provides hexagonal nitriding having an average particle diameter of 1 to 3 μm, a boron oxide content of 0.2 to 5% by mass, and a graphitization index (GI) by X-ray diffraction method of 4 to 15. Boron powder (BN1) and hexagonal boron nitride powder (BN2) of 1.5 or more and less than 4 are contained in the base oil in a mass ratio of BN1 / BN2 of 0.4 to 2.4. An engine oil characterized by In any engine oil, the content of hBN powder is preferably 0.1 to 10 g with respect to 1 liter of base oil, and the base oil has a viscosity of 0.3 to 0.00 at a liquid temperature of 20 ° C. It is preferable to show 6 mPa · s.

According to the engine oil of the present invention, both fuel consumption and output are improved.

In the present specification, “hexagonal boron nitride powder (hBN powder) having a sedimentation rate of 5% or less” means that 5 g of hBN powder is added to 1 liter of castor oil at a liquid temperature of 20 ° C., and a paddle type stirring mixer (For example, a product name “Three-one motor (model: BL1200)” manufactured by Shinto Kagaku Co., Ltd.) is mixed for 5 minutes at a rotation speed of 600 rpm, and the mixed solution is placed in a sample bottle (volume 50 ml) at a height of 50 mm from the bottom. The sample was collected and allowed to stand at room temperature for 24 hours, and the liquid level height (h1) of the mixed solution and the height of the precipitation layer of hBN powder (h2) were measured, and the sedimentation rate (%) = (h1−h2) × 100 / h1, defined as hBN powder having a sedimentation rate of 5% or less. Since h1 and h2 can be easily confirmed visually, they can be measured with a micrometer.

If hBN powder having a sedimentation rate exceeding 5% is used as a lubricant, the intended purpose cannot be sufficiently achieved. The sedimentation rate of the hBN powder of Patent Document 1 is about 6 to 8%.

An hBN powder having a sedimentation rate of 5% or less can be produced by controlling the crystallinity of the hBN powder having an average particle diameter of 1 to 3 μm and a boron oxide content of 0.2 to 5% by mass. . Specifically, BN1 is an hBN powder having an average particle diameter of 1 to 3 μm and a boron oxide content of 0.2 to 5 mass%, and having a graphitization index (GI) by X-ray diffraction method of 4 to 15. And BN2 which is 1.5 or more and less than 4 can be manufactured by mixing the mass ratio of BN1 / BN2 in a ratio of 0.4 to 2.4. Increase / decrease of the sedimentation rate within the range of 5% or less is possible, for example, by changing the mass ratio of BN1 / BN2.

If the average particle size of the hBN powder is less than 1 μm, it cannot be said that it is a scaly shape any more, and if it exceeds 3 μm, the dispersibility is lowered, and neither of them sufficiently improves fuel consumption and output. The maximum particle size of the hBN powder is preferably 15 μm or less, particularly preferably 10 μm or less, in consideration of making it difficult for the oil filter to be clogged.

The boron oxide content of the hBN powder prevents lubrication, prevents engine damage due to the development of wear resistance, and corrodes engine components due to ammonia produced by (hydrolysis) decomposition of boron nitride. From the viewpoint of prevention, the content is preferably 0.2% by mass or more. On the other hand, if the content of boron oxide is too large, it has an adhesive action and agglomeration of hBN may cause clogging of the oil filter. Therefore, the content is preferably 5% by mass or less.

As for the graphitization index (GI) of the hBN powder used in the present invention, BN1 is 4 to 15, and BN2 is 1.5 or more and less than 4. When the GI of BN1 is less than 4, the effect of improving the output is not sufficient, and when it exceeds 15, the particles contain a lot of aggregated particles. On the other hand, if the GI of BN2 is less than 1.5, the content of boron oxide is small, so that a large amount of ammonia may be generated by (hydrolysis), and if it is 4 or more, the fuel efficiency improvement effect will not be sufficient. Further, if the mass ratio of BN1 / BN2 is less than 0.4, there is an output improvement effect, but there is no sufficient fuel consumption improvement effect. If it exceeds 2.4, there is a fuel consumption improvement effect, but there is no sufficient output improvement effect.

GI is expressed by the equation GI = area {(100) + (101)} / from the integral intensity ratio (ie, area ratio) of (100), (101) and (102) diffraction lines in the X-ray diffraction pattern of hBN powder. Area (102) (J. Thomas. Et.al, J. Am. Chem. Soc., 84, 4619 [1962]). GI is an index of crystallinity, and the higher the crystallinity, the smaller this value and the scale shape develops. A fully crystallized (graphitized) hBN powder has a GI of about 1.6.

The amount of hBN powder having a sedimentation rate of 5% or less or the total hBN powder of BN1 and BN2 is preferably 0.1 to 10 g per 1 liter of base oil. The base oil may be any of mineral oil, synthetic oil, linseed oil, castor oil, oleic acid, lauric acid, stearic acid, etc., and the viscosity at a liquid temperature of 20 ° C. is 0.3 to 0.6 mPa · s. Is more preferable.

In this specification, each physical property was measured as follows.
(1) Average particle size and maximum particle size Measured by laser diffraction / scattering method. As a particle size distribution analyzer, a trade name “Microtrac SPA-7997” manufactured by LEEDS & NORTHRUP was used.
(2) GI value Measured with a powder X-ray diffractometer (“Geiger Flex 2013” manufactured by Rigaku Corporation).
(3) Content of boron oxide Methanol was added to the hBN powder, and trimethyl borate was produced by the reaction of boron oxide and methanol, and then heated at 80 ° C. to volatilize the trimethyl borate. Then, after heating at 120 ° C. to volatilize all excess methanol, the mass was measured and quantified by the reduced amount from before methanol addition.
(4) Fuel economy and output engine oil (trade name “SH Special” manufactured by Nissan Motor Co., Ltd., viscosity at 20 ° C .: 0.5 mPa · s) The amount of hBN powder shown in the table per liter is added to the vehicle ( The product name “Capella” manufactured by Mazda Motor Co., Ltd., with a displacement of 1.8 liters) was run for 1000 km, and the output and fuel consumption based on the 10.15 mode method were measured on a chassis dynamo device.

Examples 1-10
Production of BN1 Commercially available hBN powder {trade name “DENCABORON NITRIDE (GRADE SP-2)” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size: 4.0 μm, maximum particle size: 59.7 μm, GI: 9.7, Boron oxide content of 0.6% by mass} using a jet crusher (trade name “Single Track Jet Mill (model: STJ-200)” manufactured by Seishin Enterprise Co., Ltd.), supply amount of 0.5 kg / hr, conveyance After pulverization under the condition of an air pressure of 0.5 MPa, BN1 was manufactured by airflow classification using a cyclone classifier. The measurement results of the average particle size, maximum particle size, GI and boron oxide content of BN1 are shown in the table.

Production of BN2 Commercially available hBN powder {trade name “DENCABORON NITRIDE (GRADE HGP)” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 5.0 μm, maximum particle size 42.2 μm, GI 1.0, boron oxide BN2 was produced in the same manner as the production conditions for BN1, except that the content was 0.2% by mass}. The measurement results of the average particle size, maximum particle size, GI and boron oxide content of BN2 are shown in the table.

BN1 and BN2 were weighed into a polyethylene bag at the ratio shown in Table 1, and manually mixed for 5 minutes, and then the sedimentation rate of hBN powder was measured. Add this hBN powder to a commercially available base oil (trade name “SH Special” manufactured by Nissan Motor Co., Ltd., viscosity at 20 ° C. is 0.5 mPa · s) at the rate shown in the table and stir and mix for 5 minutes to engine. An oil was prepared. The fuel consumption and output of the engine oil were measured according to the above. The results are shown in the table.

Examples 11-14
Example 1 except that the carrier air pressure was crushed under the conditions of 0.7 MPa (Example 11), 0.4 MPa (Example 12), 0.45 MPa (Example 13), or 0.3 MPa (Example 14). In the same manner, BN1 was produced. An engine oil was prepared in the same manner as in Example 1 except that these BN1s were used in place of BN1 of Example 1.

Example 15
Commercially available boric acid (reagent manufactured by Kanto Chemical Co., Inc.) and melamine (manufactured by Mitsui Chemicals Inc.) were mixed at a mass ratio of 1: 1 and baked at 2000 ° C. for 7 hours under a nitrogen flow. BN1 was obtained in the same manner as in Example 1 except that the obtained fired product was dispersed in a 0.5 mass% nitric acid aqueous solution, stirred for 1 hour, washed with water, and dried and pulverized at 120 ° C for 24 hours. Manufactured. An engine oil was prepared in the same manner as in Example 1 except that this BN1 was replaced with BN1 of Example 1.

Example 16
BN1 was produced in the same manner as in Example 15 except that the mixture of boric acid and melamine was calcined at 1300 ° C. for 4 hours under nitrogen flow. An engine oil was prepared in the same manner as in Example 1 except that this BN1 was replaced with BN1 of Example 1.

Example 17
Commercially available hBN powder {trade name “DENCABORON NITRIDE (GRADE GP)” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size is 8.2 μm, maximum particle size is 59.7 μm, GI is 1.2, boron oxide content is BN1 was produced in the same manner as in Example 1 except that 0.1% by mass} was used. An engine oil was prepared in the same manner as in Example 1 except that this BN1 was replaced with BN1 of Example 1.

Example 18
Commercially available hBN powder {trade name “DENCABORON NITRIDE (GRADE SGPS)” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size of 11.0 μm, maximum particle size of 59.7 μm, GI of 2.0, boron oxide content BN1 was produced in the same manner as in Example 1 except that 5.0% by mass} was used and pulverized under the condition of a conveyance air pressure of 0.7 MPa. An engine oil was prepared in the same manner as in Example 1 except that this BN1 was replaced with BN1 of Example 1.

Examples 19-22
Example 1 except that the carrier air pressure was crushed under the conditions of 0.7 MPa (Example 19), 0.4 MPa (Example 20), 0.45 MPa (Example 21), or 0.3 MPa (Example 22). BN2 was produced in the same manner as described above. An engine oil was prepared in the same manner as in Example 1 except that these BN2s were used in place of BN2 of Example 1.

Example 23
Except that the mixture of boric acid and melamine was calcined at 1300 ° C. for 4 hours under nitrogen flow, the calcined product was produced in the same manner as in Example 15, and the same as in Example 1 except that it was pulverized. Thus, BN2 was produced. An engine oil was prepared in the same manner as in Example 1 except that this BN2 was used in place of BN2 in Example 1.

Example 24
Commercially available hBN powder {trade name “DENCABORON NITRIDE (GRADE GP)” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size is 8.2 μm, maximum particle size is 59.7 μm, GI is 1.2, boron oxide content is BN2 was produced in the same manner as in Example 1 except that 0.1% by mass} was used. An engine oil was prepared in the same manner as in Example 1 except that this BN2 was used in place of BN2 in Example 1.

Example 25
Commercially available hBN powder {trade name “DENCABORON NITRIDE (GRADE SGPS)” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size of 11.0 μm, maximum particle size of 59.7 μm, GI of 2.0, boron oxide content BN2 was manufactured in the same manner as in Example 1 except that the pulverization was performed under the condition of 5.0 mass%} and the conveyance air pressure was 0.7 MPa. An engine oil was prepared in the same manner as in Example 1 except that this BN2 was used in place of BN2 in Example 1.

Comparative Example 1
Commercially available hBN powder (trade name “DENCABORON NITRIDE (grade: SGP: average particle size 18.0 μm, maximum particle size 59.6 μm), GI = 1.0, boron oxide content 0.1 mass, manufactured by Denki Kagaku Kogyo Co., Ltd. %) "Was pulverized under the condition of a carrier air pressure of 0.45 MPa, and classified, and the average particle size was 2.6 μm, the maximum particle size was 14.4 μm, the GI was 1.0, and the boron oxide content was 0.2 mass. (The characteristics are described in the BN1 column of the table for convenience.) Except that this hBN powder was used in place of BN1 and BN2 of Example 1, the same as Example 1 was used. An engine oil was prepared.

Comparative Example 2
An engine oil was prepared in the same manner as in Comparative Example 1 except that the amount of hBN powder added was Example 4.

The engine oil of the present invention can be used for gasoline engines, diesel engines, etc. of four-wheeled vehicles, two-wheeled vehicles, motorbikes, large ships such as tankers, small ships such as motor boats, and the like.

Claims (2)

Hexagonal crystal having an average particle diameter of 1 to 3 μm, a maximum particle diameter of 15 μm or less, a boron oxide content of 0.2 to 5% by mass, and a graphitization index (GI) by X-ray diffraction method of 4 to 15 Boron nitride powder (BN1) and hexagonal boron nitride powder (BN2) of 1.5 or more and less than 4 are added to 1 liter of base oil at a mass ratio of BN1 / BN2 of 0.4 to 2.4. An engine oil characterized by containing 0.1 to 10 g . The engine oil according to claim 1 , wherein the base oil has a viscosity at a liquid temperature of 20 ° C of 0.3 to 0.6 mPa · s.