JP2018168356A - Lubricant composition and its manufacturing method - Google Patents

Abstract

To provide a lubricant composition being highly flexibly compounded with an additive.SOLUTION: A lubricant composition of the present invention comprises a base oil and a fullerene. The lubricant composition comprises per 10 ml less than one particle having a major axis of 1 μm or more.SELECTED DRAWING: None

Description

  The present invention relates to a fullerene-containing lubricating oil composition and a method for producing the same.

  In recent years, with the increase in speed, efficiency, and energy saving, there has been a strong demand for improving the performance of lubricating oils used in automobiles, home appliances, industrial machines, and the like. Various additives such as an antioxidant, an extreme pressure additive, a rust inhibitor, and a corrosion inhibitor are blended in order to improve the characteristics so as to be suitable for the application. Furthermore, a lubricant having a high flash point is required for easy safety management.

  In order to meet these demands, Patent Document 1 discloses that fullerenes, which are nanocarbon particles, are used in lubricating base oils such as mineral oils and ester oils in order to simultaneously improve a plurality of performances such as low friction, torque increase, and fuel saving. In addition, an additive composition for engine lubricating oil containing an organic solvent, a viscosity index improver, a friction modifier, and a cleaning dispersant is disclosed.

  Patent Document 2 shows that the oxidation of the base oil constituting the composition can be suppressed by blending fullerene into the lubricating oil composition or the grease composition. Patent Documents show that such a lubricating oil composition or grease composition has excellent high-temperature durability, and the high-temperature durability of a rolling bearing lubricated with the lubricating oil or a rolling bearing encapsulating the grease composition is improved. 2 is disclosed.

  In Patent Document 3, a polyol ester is used as a base oil, and two kinds of aromatic amine antioxidants, alkylated diphenylamine and alkylated phenylnaphthylamine, a phosphite antioxidant, and a boron-containing extreme pressure agent are blended. Thus, a high temperature lubricating oil composition is described which has improved evaporation resistance and low residue properties and has a high flash point.

JP 2008-266501 A JP 2011-68899 A JP 2011-184604 A

  However, the high flash point lubricating oil composition obtained by blending the additive has a high viscosity. Since viscosity resistance increases, it is not preferable from the viewpoint of energy saving effect. On the other hand, when it was going to keep viscosity low, it was difficult to mix | blend the said additive with a lubricating oil composition, and it was difficult to obtain a high flash point. Furthermore, in a lubricating composition to which fullerene is simply added, when fullerene aggregates, there is a concern that not only performance deterioration as a lubricant but also flash point may be lowered. Thus, the blending of the additive into the lubricating oil composition has such a limitation.

The present inventors have been made in view of the above circumstances, and an object of the present invention is to provide a lubricating oil composition in which the degree of freedom of additives to be added is improved.

In order to solve the above problems, the present invention includes the following [1] to [6].
[1] A lubricating oil composition comprising a base oil and fullerene and having less than 1 particle having a major axis of 1 μm or more per 10 ml.
[2] The lubricating oil composition according to [1], wherein the base oil is mineral oil or synthetic oil.
[3] the fullerene _is, the lubricating oil composition according to item [1] or [2] is a mixture containing _{C 60} and _{C 70.}
[4] The lubricating oil composition according to any one of [1] to [3], further including an additive.
[5] The lubricating oil according to any one of [1] to [4], wherein the base oil and the raw material fullerene are mixed, and the step of extracting the fullerene into the base oil and the step of removing the insoluble components are sequentially performed. A method for producing the composition.
[6] The method for producing a lubricating oil composition according to [5], further including a step of diluting with a base oil after the step of removing insoluble components.

  According to the present invention, it is possible to provide a lubricating oil composition having a high degree of freedom of additives to be blended.

Hereinafter, an embodiment of the present invention will be described in detail.
The lubricating oil composition obtained in the present embodiment contains a base oil and fullerene, and has less than 1 particle having a major axis of 1 μm or more per 10 ml. Since there are few particles (particularly aggregated particles of fullerene) that cause the fullerene to further aggregate, a stable fullerene-containing lubricating oil composition can be obtained.
(Base oil)
The base oil used in the present embodiment is not particularly limited, but it is preferable to use mineral oils and synthetic oils that are generally widely used as base oils for lubricating oils.

  The mineral oil is generally obtained by converting double bonds contained therein into saturated hydrocarbons by hydrogenation. Examples thereof include paraffinic and naphthenic base oils.

  Examples of the synthetic oil include synthetic hydrocarbon oil, ether oil, and ester oil. More specifically, poly α-olefin, diester, polyalkylene glycol, polyalphaolefin, polyalkyl vinyl ether, polybutene, isoparaffin, olefin copolymer, alkylbenzene, alkylnaphthalene, diisodecyl adipate, monoester, dibasic acid ester, Tribasic acid ester, polyol ester (trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate, etc.), dialkyl diphenyl ether, alkyl diphenyl sulfide, polyphenyl ether, silicone lubricant (Such as dimethyl silicone) and perfluoropolyether can be preferably used. More preferable examples include poly α-olefin, diester, polyol ester, polyalkylene glycol, polyalkyl vinyl ether, and the like.

These mineral oils and synthetic oils may be used alone, or two or more kinds of base oils selected from these may be mixed and used in an arbitrary ratio.

(Fullerene)
The fullerene used in the present embodiment is not particularly limited, and various types can be used. For example, C ₆₀ or C ₇₀ , higher order fullerene, or a mixture thereof can be used. From the viewpoint of availability, C ₆₀ and C ₇₀ are preferable among the fullerenes, and C ₆₀ is more preferable. In the case of a fullerene mixture, C ₆₀ is preferably contained in an amount of 50% by mass or more.

  In the lubricating oil composition of the present embodiment, fullerene is less agglomerated and has less than one particle having a major axis of 1 μm or more per 10 ml of the lubricating oil composition. This confirmation can be performed by a method of an embodiment described later.

  In the lubricating oil composition of the present embodiment, the concentration of fullerene is preferably 0.001 to 2.0% by mass, more preferably 0.05% to 1.5% by mass, and still more preferably. 0.05% to 1.0% by mass. If the fullerene concentration is 0.001% by mass or more, the effects of reducing the friction coefficient and improving the flash point can be sufficiently expected. If the fullerene concentration is 2% by mass or less, the possibility that aggregated particles precipitate even when left for a long time is further reduced.

(Additive)
An additive can be blended with the lubricating oil composition of the present embodiment in order to improve various properties. Such additives are not particularly limited, for example, commercially available antioxidants, viscosity index improvers, extreme pressure additives, cleaning dispersants, pour point depressants, corrosion inhibitors, solid lubricants, At least one kind of oiliness improver, rust inhibitor, demulsifier, antifoaming agent, hydrolysis inhibitor and the like can be blended.

  As an additive, those having an aromatic ring are preferable because fullerenes are less likely to aggregate. For example, antioxidants include dibutylhydroxytoluene (BHT), butylhydroxyanisole (BHA), 2,6-di-t-butyl-paracresol (DBPC), 3-arylbenzofuran-2-one (hydroxycarboxylic acid) Intramolecular cyclic esters), phenyl-alpha-naphthylamine, dialkyldiphenylamine, benzotriazole, etc., viscosity index improvers such as polyalkyl styrene, styrene-diene copolymer hydride additives, etc. Benzyl disulfide, allyl phosphate ester, allyl phosphite ester, allyl phosphate ester amine salt, allyl thiophosphate ester, allyl thiophosphate amine salt, naphthenic acid, etc. As pour point depressants, such as alkylphenolamines, chlorinated paraffin-naphthalene condensate, chlorinated paraffin-phenol condensate, polyalkylstyrene, etc. May include dialkylnaphthalene sulfonate.

(Production method)
The method for producing a lubricating oil composition of the present embodiment includes a first step of mixing a base oil and fullerene, extracting the fullerene into the base oil to obtain a mixture of the base oil and fullerene, and the mixture. A second step of removing the insoluble matter to obtain a lubricating oil composition is included. Furthermore, the lubricating oil composition obtained in the second step may be diluted with a base oil to include a third step of obtaining a lubricating oil composition having a desired fullerene concentration.

(First step)
The raw material fullerene and the base oil are mixed, and the fullerene is extracted into the base oil. Preferably, the extraction is performed with stirring for about 3 to 48 hours while heating around room temperature or as necessary. Stirring may be performed using a general stirrer, but preferably, it is easy to extract to a desired fullerene concentration in a short time by using an ultrasonic dispersing device, a homogenizer, a ball mill, a bead mill, or the like. The amount of raw material fullerene charged is, for example, 1.2 to 5 times the amount of fullerene that gives a desired fullerene concentration relative to the base oil in consideration of the fullerene concentration of the lubricating oil composition to be finally prepared. More preferably 1.2 to 3 times. By setting it to 1.2 times or more, the amount of extractable dissolved substance increases, and a desired fullerene concentration can be easily obtained in a short time. Moreover, it becomes easy to remove an unnecessary thing by the 2nd process mentioned later by setting it as 5 times or less. Furthermore, the consumption of raw material fullerene is suppressed and it is economical.

(Second step)
The mixture obtained in the first step contains, as insoluble particles, undissolved aggregates of fullerene, possibly base oil impurities, particles mixed in the manufacturing process, and the like. These particles may further cause inconveniences such as fullerene aggregates and wear of sliding members. Therefore, a second step of removing the insoluble matter is provided. As the second step, it is sufficient that the insoluble matter can be removed until less than one particle having a major axis of 1 μm or more per 10 ml of the lubricating oil composition. For example, a removal method by filtration, a removal method by centrifugation, and a combination of these removal methods And so on. From the viewpoint of processing time, filtration is preferable when a small amount of lubricating oil composition is obtained, and when a large amount of lubricating oil composition is obtained, it is preferable to use filtration after centrifugation or centrifugation.

  In the removal method by filtration, for example, the mixture of fullerene and base oil obtained in the first step is filtered using a membrane filter having a pore size of 0.1 to 1 μm to remove insoluble matters, and a lubricating oil composition As recovered. This filtration is preferred because suction filtration can shorten the time.

  In the removal method by centrifugal separation, for example, the mixture of fullerene and base oil obtained in the first step is subjected to centrifugal separation treatment, and the supernatant is recovered as a lubricating oil composition after removal of insoluble matters.

(Third process)
Furthermore, the same or different base oil as the base oil used in the first step is used so that the lubricating oil composition obtained in the second step has a desired fullerene concentration in the composition. A third step of diluting with can also be included. Hereinafter, unless otherwise specified, the base oil used in the first step is simply referred to as “base oil”, and the base oil used in the third step is referred to as “diluted base oil”.

(Addition of additives)
The above-mentioned additive can be added to the lubricating oil composition according to the present embodiment in any of the first to third steps. For example, a method of adding an additive to at least one of the base oil used in the first step, the mixture obtained in the first step, the lubricating oil composition obtained in the second step, the base oil used for dilution in the third step, etc. Is mentioned. Additives that contain or may cause insoluble components are preferred because they are added before removal of unnecessary materials in the second step, so that insoluble components derived from the additives are removed. If it is an additive that does not have such a risk, it may be added after removing unnecessary materials in the second step.

(Use)
The lubricating oil composition of the present embodiment is an industrial gear oil; hydraulic hydraulic oil; compressor oil; refrigeration oil; cutting oil; rolling oil, press oil, forging oil, drawing oil, drawing oil, punching oil, etc. It can be used for various applications such as oil; heat treating oil, metal working oil such as electric discharge machining oil; slip guide surface oil; bearing oil; rust preventive oil; Furthermore, the lubricating oil composition of the present embodiment tends to be a composition having a low pour point, and is particularly useful in applications where the lower the pour point, such as engine oil, is better.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the present invention described in the claims. Deformation / change is possible.

  Examples of the present invention will be described below. In addition, this invention is not limited only to a following example.

(Measurement of fullerene concentration)
The fullerene concentration was measured by measuring the absorbance at 381 nm of the toluene solution of the sample using a spectrophotometer (Shimadzu Corporation; UV-visible spectrophotometer UV-1700). A calibration curve prepared in advance with a toluene solution of the same type of fullerene (the raw material fullerene described later) was used.

(Measurement of the number of particles of 1 μm or more)
After leaving the lubricating oil composition at 30 ° C. for 3 days, 10 ml of the lubricating oil composition was filtered with a 0.1 μm membrane filter, and this filtered surface was observed with a scanning electron microscope to count particles having a major axis of 1 μm or more. This filtration to scanning electron microscope observation was repeated three times to obtain an average value of the number of particles.

(Measurement of viscosity)
Using a rotational viscometer (Brookfield digital viscometer DV-E, spindle SC4-18, rotation speed 50 rpm), the viscosity was measured using the lubricating oil composition as a sample. In addition, the viscosity increase rate measured the viscosity similarly about the base oil used for the sample, and calculated | required as follows.
Viscosity increase rate (%) = ([viscosity of sample] / [viscosity of base oil] -1) × 100

(Measurement of friction coefficient)
Using the lubricating oil composition as a sample, a friction coefficient was measured using a pin-on-disk tribometer (manufactured by Antonparr) under the conditions of a load of 2 N, a rotational speed of 100 rpm, and a rotational speed of 3000 times.

(Measurement of film thickness of lubricating oil composition)
40 μl of a lubricating oil composition is dropped on a substrate (13 × 13 × 5 mm) of a high carbon chrome bearing steel material SUJ2 (JIS G 4805: 2008), and each is carried out for 20 seconds at 500, 1000, 1500, 2500 rpm using a spin coater. Processed. About the obtained board | substrate, the film thickness of the lubricating oil composition was measured with the film thickness meter (microspectrophotometer film thickness meter OPTM-A1, Otsuka Electronics Co., Ltd. product).

(Measure flash point)
The flash point was measured according to the PMCC method (Pen schema Lutens sealed type) using a lubricating oil composition based on mineral oil as a sample. The apparatus uses an Ebel sealed automatic flash point tester (Tanaka Scientific Instruments Manufacturing Co., Ltd.) and takes 70 ml of the stirred sample (about 70 ml when filled to the mark of the sample cup) in the sample cup. The temperature rise measurement was started at 5-6 ° C./min, 90-120 rpm, and the flash point was measured.

(Measure pour point)
The pour point was evaluated according to JIS-2269 (pour point of crude oil and petroleum products and cloud point test method of petroleum products). The apparatus uses a circulating low-temperature thermostat (manufactured by Thomas Scientific Instruments Co., Ltd.), warms a 45 ml sample taken in a test tube to 45 ° C., and then cools it by a prescribed method. Whenever the temperature of the sample dropped 2.5 ° C, the test tube was removed from the cooling bath, the temperature when the sample stopped moving for 5 seconds was read, and the temperature obtained by adding 2.5 ° C to this value was taken as the pour point. .

(material)
The following products were used in each example and comparative example.
Raw material fullerene: nanom (registered trademark) mix ST manufactured by Frontier Carbon Co., Ltd. (C ₆₀ : 60% by mass, C ₇₀ : 25% by mass, the balance being a mixture of other higher fullerenes.)
Mineral oil; Diana Fresia P-46 manufactured by Idemitsu Oil Co., Ltd.
POE; Nistar Co., Ltd. Unistar MB-808B
PAO; SpectraSyn ^TM 2C manufactured by ExxonMobil
PAG; Daphne Hermetic Oil PS manufactured by Idemitsu Kosan Co., Ltd.
PVE: Idemitsu Kosan Co., Ltd. Daphne Hermetic Oil FVC32D
Tricresyl phosphate; manufactured by Wako Pure Chemical Industries, Ltd. Special grade tricresyl phosphate (molecular weight 1000 or less)
BHT; 2,6-di-tert-butyl-p-cresol manufactured by Tokyo Chemical Industry Co., Ltd.

Example 1
As a base oil, 250 g of mineral oil and 0.375 g of the raw material fullerene were mixed and stirred at room temperature using a stirrer for 36 hours. Next, the solution was filtered through a membrane filter having a pore size of 0.1 μm to obtain a filtrate containing fullerene. The fullerene concentration of this filtrate was 0.135% by mass. The filtrate was diluted with 88 g of the same type of diluted base oil as the base oil to obtain a lubricating oil composition having the fullerene concentrations shown in Table 1. Furthermore, the measurement described in Table 1 was performed on this lubricating oil composition.

(Examples 2 to 7)
Table 1 shows the same operation and measurement (except for the flash point measurement) as in Example 1, except that the type of base oil, the amount of raw material fullerene charged and the amount of diluted base oil were changed as shown in Table 1. Obtained results.

(Comparative Examples 1-5)
In Comparative Examples 1 to 5, mineral oil, POE oil, PAO oil, PAG oil, and PVE oil were used as base oils, and these base oils were only filtered through a membrane filter having a pore size of 0.1 μm. It was handled as a lubricating oil composition and measured in the same manner as in Example 1. However, the flash point was measured only when the base oil was mineral oil.

(Comparative Example 6)
Mineral oil 250g and raw material fullerene 1.256g were mixed, and it stirred for 36 hours using the stirrer at room temperature, and obtained the mixture of mineral oil and fullerene. When calculated from the charged amount of raw material fullerene, the fullerene concentration in the mixture is 0.5 mass%. The mixture was not filtered through a membrane filter, and the resulting mixture was treated as a lubricating oil composition, and measurements were performed in the same manner as in Example 1.

(Comparative Example 7)
Operations and measurements were performed in the same manner as in Comparative Example 6 except that 5.102 g of raw material fullerene was used and the fullerene concentration in the mixture calculated from the charged amount of raw material fullerene was 2.0 mass%.

The evaluation results of Examples 1 to 7 and Comparative Examples 1 to 7 are shown in Table 1.

  About the lubricating oil composition of each Example and each comparative example, as shown in Table 1, with respect to Examples 1-7, a fullerene is not impregnated in Comparative Examples 1-5, and an insoluble matter is not included in Comparative Examples 6-7. Not removed. As a result, it can be seen that, in comparison with these comparative examples, in the examples, the friction coefficient is small and good lubricity is exhibited, the flash point is increased and the film thickness is increased. For this reason, the seizure phenomenon can be further suppressed by running out of oil on the friction surface. Furthermore, it can be seen that the viscosity does not increase in this example even though the characteristics are improved. Further, in the lubricating oil compositions of the examples, the number of particles having a major axis of 1 μm or more was less than one. This is thought to be because growth of further aggregated particles of fullerene was suppressed by removing aggregated particles as much as possible. The reason why the effects as in Examples are not obtained in Comparative Examples 6 to 7 is considered to be because there are many aggregated grains.

  Furthermore, in Examples 1, 4, 5, 6, and 7, it can be seen that the pour point is lowered as compared with Comparative Examples 1, 2, 3, 4, and 5, respectively. Therefore, a lubricating oil composition that can be used at a lower temperature than the base oil can be obtained.

(Example 8)
Using tricresyl phosphate as an additive, the mineral oil used as the base oil is added so that the additive is 5.6% by mass, and then 250 g of this additive-containing mineral oil and 0.375 g of the raw material fullerene are mixed, The mixture was stirred for 36 hours using a stirrer. Next, this mixture was filtered through a membrane filter having a pore size of 0.1 μm to obtain a filtrate. The filtrate was diluted with the additive-containing mineral oil so that the fullerene concentration was 0.1% by mass to obtain a lubricating oil composition. The measurement described in Table 2 was performed on this lubricating oil composition.

(Examples 9 and 10)
The same operation and measurement as in Example 8 were performed except that the type of base oil, the type of additive, the charged amount of fullerene, and the amount of diluted base oil were changed as shown in Table 2.

(Comparative Example 8)
The tricresyl phosphate was used as an additive, and 5.6% by mass of the additive was added to mineral oil as a base oil, followed by filtration through a membrane filter having a pore size of 0.1 μm. The filtrate was treated as a lubricating oil composition and measured in the same manner as in Example 8.

(Comparative Examples 9 and 10)
The same operation as in Comparative Example 8 was performed except that the type of base oil and the type of additive were changed as shown in Table 1.

  The results of Examples 8-10 and Comparative Examples 8-10 are shown in Table 2.

In Table 2, in the lubricating oil compositions of Examples 8 to 10 containing an additive, in addition to the same effects as in Examples 1 to 7 such as the coefficient of friction and the film thickness, the viscosity increases even when the additive is added. Is suppressed. Therefore, there are few restrictions by a viscosity and the kind and quantity of an additive can be selected more freely.

Claims (6)

  A lubricating oil composition comprising a base oil and fullerene and having less than one particle having a major axis of 1 μm or more per 10 ml.   The lubricating oil composition according to claim 1, wherein the base oil is a mineral oil or a synthetic oil. The lubricating oil composition according to claim 1, wherein the fullerene is a mixture containing C ₆₀ and C ₇₀ .   Furthermore, the lubricating oil composition in any one of Claims 1-3 containing an additive.   The manufacturing method of the lubricating oil composition in any one of Claims 1-4 which mix a base oil and raw material fullerene, and perform the process of extracting fullerene in base oil, and the process of removing an insoluble component one by one. Furthermore, the manufacturing method of the lubricating oil composition of Claim 5 including the process of diluting with a base oil after the process of removing an insoluble component.