JP2017088757A - Fullerene-containing mineral oil and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mineral oil having suppressed viscosity to low even when fullerene or an additive are mixed.SOLUTION: There is provided a mineral oil containing a mineral oil containing no fullerene (hereafter called "base oil"), an additive having an aromatic ring and fullerene, wherein no particle with 1 μm or more is contained in the mineral oil of 10 ml, the fullerene content is 0.1 to 50 mass% based on the additive and 0.001 to 0.5 mass% based on the base oil.SELECTED DRAWING: None

Description

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

  Additives are added to the mineral oil to improve its properties so that it is suitable for its use. Attempts have been made to add fullerene as an additive to improve the properties. However, since fullerenes are difficult to dissolve directly in mineral oil, attempts have been made to previously dissolve fullerenes in unsaturated fatty acids, carboxylic acid ester oils, surfactants, organic solvents and the like that dissolve fullerenes.

  For example, Patent Document 1 states that “a lubricating oil composition and a grease composition that can greatly improve the lubrication life at high temperatures associated with the severe use of rolling bearings. The lubricating oil composition used for rolling bearings is lubricating oil. The fullerene is blended in an amount of 0.05 to 10% by mass based on the entire composition, and the grease composition contains a base oil and a thickener, and the fullerene is added in an amount of 0.05 to It is disclosed that 10% by mass is blended, and in these compositions, the fullerene is blended as a blending agent dispersed in an organic solvent dissolved in the base oil of the composition.

  Further, Patent Document 2 states that “a method for producing a saturated hydrocarbon solution of fullerene capable of preparing a saturated hydrocarbon solution in which fullerene is dissolved in a high concentration and stably. Fullerene is dissolved in toluene or cyclohexane in advance, Preparation of a saturated hydrocarbon solution in which saturated hydrocarbons are mixed and toluene or cyclohexane is distilled off from the mixture under reduced pressure to dissolve fullerenes, while liquid paraffin, for example, is 100 ppm or less in liquid paraffin. It has been disclosed that it is common to mix other unsaturated fatty acids, carboxylic acid ester oils, and fullerene solubilizers such as surfactants.

JP2011-068899A JP2011-256095

  However, the inclusion of commonly used additives increases the viscosity of the mineral oil. On the other hand, in order to remove impurities, the mineral oil production process requires an impurity removal process such as filtering and centrifugation. However, when an additive is added, the viscosity changes, so stable filtering and centrifugation are necessary. Therefore, it has been difficult to stably produce an additive-containing mineral oil. Therefore, there is a demand for a fullerene-containing mineral oil whose viscosity is kept low even when fullerenes and additives are mixed.

The present invention includes the following inventions.
(1) Mineral oil containing no fullerene (hereinafter referred to as “base oil”), an additive having an aromatic ring, and a mineral oil containing fullerene, wherein 10 μm or more of particles are contained in 10 ml of the mineral oil. The mineral oil in which the fullerene content is 0.1 to 50% by mass with respect to the additive and 0.001 to 0.5% by mass with respect to the base oil.
(2) The mineral oil according to item (1), wherein the additive is an antioxidant.
(3) The mineral oil according to (1) or (2) above, wherein the additive has a molecular weight of 1000 or less.
(4) The mineral oil according to any one of (1) to (3) above, wherein the additive is a compound having a phenyl group which may have a substituent.
(5) The mineral oil according to any one of (1) to (3) above, wherein the additive is tricresyl phosphate or thiadiazole.

  The mineral oil of the present invention has a low viscosity even when fullerene is dissolved at a high concentration.

  The inventor has found that a mixture of an additive having an aromatic ring, fullerene and mineral oil can suppress an increase in viscosity, and has completed the invention based on the findings. Details will be described below.

(Fullerene)
Various fullerenes can be used in the present invention. For example, C60 and C70 which are relatively easily available, higher order fullerenes, or a mixture thereof can be used. Among fullerenes, C60 and C70 are preferable, and C60 is more preferable. In the case of a mixture, it is preferable that 50 mass% or more of C60 is contained. This is because C60 is more spherical and easily exhibits the bearing effect described later.

(Improved solubility and lubricity)
Fullerenes are multifunctional and have a very small spherical structure. C60 is a spherical shape composed of 20 faces of a 6-membered ring and 32 faces of a 12-faced 5-membered ring, and its diameter is 0.7 nm at the position of the atom, and about 1 nm considering the existence of an electron cloud. Higher order fullerenes such as C70 also have the same 12-sided 5-membered ring, and the number of 6-membered rings increases. This nano-sized fullerene rotates on the sliding surface, so that a lubricity effect due to the bearing effect is expected. Furthermore, it is said that it exists as an extreme pressure additive when it exists between sliding surfaces.

  However, since fullerene hardly dissolves in the mineral oil that is most widely used as a lubricating oil, the methods that have been studied in the past have been insufficient in terms of solubility and extreme pressure additive effect. For example, if fullerene is dissolved beforehand in an organic solvent (for example, toluene) and the solution is mixed with mineral oil, the organic solvent dissolves in mineral oil, so it appears that the fullerene has dissolved, but if the organic solvent is removed under reduced pressure or volatilized, Fullerene precipitated again. In addition, it was difficult to achieve the effect of an extreme pressure additive only when fullerene was dissolved in mineral oil. In order for sufficient lubrication between the sliding surfaces to work, there must be a necessary amount of lubricating oil between the metal surfaces that make up the sliding surface, and a bond is created at the contact point between the metal surface and the metal surface. However, the extreme pressure additive effect is that the additive is coordinated to the surface of the metal, and even when the sliding surface is overloaded and the lubricant runs out, the additive remains on the surface. It works to prevent contact between metal surfaces. However, since many oxides exist on the surface of the metal, it was difficult to directly coordinate fullerene having no hydrophilic property to the metal surface, and the effect of the extreme pressure additive was small.

  As in the present invention, it is a functional group having a polarity for coordination to the metal surface and has a strong interaction with fullerene, and further has an antioxidant effect and an extreme pressure addition effect. The solubility and extreme pressure additive effect can be improved by mixing the additive with fullerene and mineral oil.

(Base oil)
As the base oil used in the previous step, a mineral oil containing no fullerene can be used. Mineral oil used as a lubricant is generally one in which double bonds contained therein are converted to saturated hydrocarbons by hydrogenation. Mineral oil is divided into paraffinic and naphthenic types. Specific examples include engine oil, mineral oil, microcrystalline wax, ceresin, liquid paraffin, vacuum pump oil, compressor oil, spindle oil, dynamo oil, turbine oil, machine oil, and gear oil.

(Additives with aromatic rings)
As an additive having an aromatic ring, viscosity index improver, detergent dispersant, pour point depressant, extreme pressure additive, solid lubricant, oil improver, antioxidant, rust inhibitor, corrosion inhibitor, Demulsifiers, antifoaming agents, etc. are included.

  Viscosity index improvers include polyalkylstyrene, styrene-diene copolymer hydride additives, detergent dispersants such as benzylamine succinic acid derivatives and alkylphenolamines, and pour point depressants such as chlorinated paraffins. Naphthalene condensate, chlorinated paraffin-phenol condensate, polyalkylstyrene, etc., extreme pressure additives include dibenzyl disulfide, allyl phosphate, allyl phosphite, amine salt of allyl phosphate, allyl thiophosphate Antioxidants such as amine salts of allyl thiophosphates and naphthenic acids include dibutylhydroxytoluene (BHT), butylhydroxyanisole (BHA), 2,6-ditertiary-butyl-paracresol (DBPC), 3-arylbennes Zofran-2-one (intramolecular cyclic ester of hydroxycarboxylic acid), phenyl-alpha-naphthylamine, dialkyldiphenylamine, benzotriazole, etc., as corrosion inhibitors, dialkylnaphthalene sulfonate, etc. Demulsifiers, alkylbenzene sulfonate And so on. These additives can dissolve fullerenes well.

  Here, the “well dissolved state” means that the fullerene is contained almost uniformly in the base oil and / or mineral oil in the desired application form. For example, a state in which fullerene particles are present in a uniform floating state in the base oil and / or mineral oil, or a state in which the particles are substantially dissolved without agglomeration can be mentioned.

  Non-aggregation can be determined by the fact that when 10 ml of mineral oil is filtered through a filter paper (for example, a 0.1 μm membrane filter), particles of 1 μm or more do not remain on the filter paper. Further, the residue containing the aggregated particles of fullerene is used as an impurity. The amount of fullerene is preferably 0.5 to 50% by mass with respect to the amount of additive added to mineral oil. For example, when the fullerene concentration of the mineral oil to be finally obtained is 0.01 to 0.5% by mass, 1 to 10% by mass of the additive is added to the mineral oil, and in that case, 0.5% to the additive. Add ~ 50 wt% fullerene.

  When mineral oil is used as a lubricating oil, the mineral oil that contains many aromatic rings and double bonds may lack chemical stability. This is because the aromatic ring has a relatively large interaction force with the outside. In the present invention, the additive has an aromatic ring. If the mineral oil molecule has an aromatic ring, decomposition may occur from that point, but in the case of an additive, the additive's aromatic ring absorbs changes in the outside world, thereby affecting the action of the additive. This is because of the manifestation, and it is not a problem that the additive has an aromatic ring. Furthermore, by adding fullerene having a function as a radical catcher, the aromatics of the additive itself are also stabilized.

  Antioxidants containing no aromatic ring, for example, trialkyl phosphite (for example, ADEKA 3010 CAS-No. 25448-3), dialkyl diphosphite (for example, ADEKA PEP-8 CAS-No. 3806-6, thioether type) Addition of antioxidants (ADEKA AO-412S CAS-No. 29598-76-3, ADEKA AO-503 CAS-No. 10595-72-9) increases the viscosity of the mineral oil.

  On the other hand, the additive having an aromatic ring as described above does not increase the viscosity even when added to mineral oil. Furthermore, it is preferable to select an additive having an aromatic ring that does not increase the viscosity of the mineral oil even when added to the mineral oil (for example, the viscosity increase rate is preferably 5% or less).

  As the additive having an aromatic ring, an additive having a molecular weight of 1000 or less (more preferably 900 to 300) is preferable among the additives described above. This is because the viscosity of the low molecular weight is difficult to increase. Although those having a small molecular weight are likely to volatilize, in the present invention, since they are mixed with fullerene, volatility can be suppressed by interaction with fullerene. For example, allyl phosphite (ADEKA TPP CAS-No. 101-02-0 can be mentioned.

  Further, the additive having an aromatic ring is preferably a compound having a phenyl group (hereinafter simply referred to as “phenyl group”) which may have a substituent. This is because such an additive having a phenyl group has a small change in viscosity of the added mineral oil even if the amount of fullerene to be dissolved changes.

  Accordingly, an additive having a phenyl group as an aromatic ring having a molecular weight of 1000 or less is more preferable from the viewpoints of solubility of fullerene, securing low viscosity, and suppression of volatility by fullerene.

  The additive having an aromatic ring is preferably one that works as an antioxidant or an extreme pressure additive in accordance with the use form of the mineral oil.

(Production method)
The method for producing a mineral oil of the present invention is obtained through a pre-process for obtaining a base oil containing an additive having an aromatic ring and a fullerene, and an impurity removal process for removing impurities contained in the base oil after the pre-process. Hereinafter, an example of an embodiment of the mineral oil production of the present invention will be described in detail.

(pre-process)
As a pre-process for obtaining a base oil containing an additive having an aromatic ring and a fullerene, (1) a process of dissolving the fullerene in the additive and then dissolving the additive in the base oil; (2) a base oil of the additive A step comprising any step of dissolving the fullerene in the base oil after being dissolved in the base oil and (3) a step of dissolving the additive and fullerene together in the base oil can be used. (1) can dissolve fullerene efficiently, (2) can be applied to a base oil in which additives are already mixed, and (3) is preferable because the process can be shortened.

  In the pre-process of (1), for example, 0.1 to 50% by mass of fullerene is added to the additive, and after stirring for 3 to 48 hours using a stirrer or the like, the final step in the mineral oil is performed. Stir into the base oil prepared in advance so that the fullerene concentration is a predetermined concentration. As the amount of the base oil, for example, 0.001 to 0.5% by mass of fullerene is preferably added to the base oil. Since fullerene is dissolved in an additive having an aromatic ring, fullerene can be sufficiently dissolved. Here, the amount of fullerene with respect to the base oil is 0.001 to 0.5% by mass. If it is less than 0.001% by mass, the addition effect as an extreme pressure additive cannot be expected, and 0.5% by mass. It is because it will aggregate and a precipitate will produce | generate if it exceeds.

  After the fullerene is added to the additive and the stirring treatment is performed, that is, before the addition to the base oil, an impurity removal step may be provided. The impurity removal treatment can be carried out in the same manner as the treatment in the impurity removal step described later, but can be carried out by a simple treatment method because the treatment target is a small amount before the mineral oil addition. Further, it is preferable to carry out the removal treatment at this time, since impurities derived from the fullerene raw material and undissolved fullerene are removed, so that the load of the removal treatment described later is reduced. For example, since a filter having a mesh smaller than that of the filter used at this time can be used in the removal treatment step, the degree of refinement of the final mineral oil is further improved.

  In the pre-process of (2), for example, after adding the additive to the base oil prepared in advance and stirring the mixture, 0.1 to 50% by mass of fullerene is added to the additive added to the base oil. Then, stirring is performed for 3 to 48 hours using a stirrer or the like. The amount of base oil is the amount of base oil calculated backward from the amount of fullerene to be added so that the final fullerene concentration is obtained. Since fullerene is dissolved in a base oil containing an additive having an aromatic ring, fullerene can be sufficiently dissolved. Here, it is preferable to add 0.001 to 0.5 mass% of the fullerene amount with respect to the base oil. This is because if it is less than 0.001% by mass, the effect of adding fullerene cannot be expected, and if it exceeds 0.5% by mass, it aggregates and precipitates.

  In the pre-process of (3), for example, fullerene and an additive are added to a base oil prepared in advance so that the fullerene concentration is 0.1 to 50% by mass with respect to the additive, followed by stirring using a stirrer or the like. Apply processing. The amount of base oil is the amount of base oil calculated backward from the amount of fullerene to be added so that the final fullerene concentration is obtained. Since the additive having an aromatic ring and fullerene are dissolved in the base oil, the fullerene can be sufficiently dissolved. Here, it is preferable to add 0.001 to 0.5 mass% of the fullerene amount with respect to the base oil. This is because if it is less than 0.001% by mass, the effect of adding fullerene cannot be expected, and if it exceeds 0.5% by mass, it aggregates and precipitates.

(Impurity removal process)
The base oil obtained in the previous process contains, as impurities, fullerene aggregates, which are impurities derived from fullerene raw materials, undissolved fullerene, impurities derived from mineral oil, particles mixed in the manufacturing process, etc. If is used as the mineral oil of the product as it is, there is a risk that problems such as wear of the sliding member in contact with the mineral oil may occur. Therefore, an impurity removal step (filtering) for removing impurities is provided. The present invention is preferably used in an impurity removal process including a process that is susceptible to the influence of viscosity. For example, (1) a removal process using a membrane filter, (2) a removal process using a centrifuge, and a combination thereof. Can be mentioned. From the viewpoint of filtration time, (1) is preferred when obtaining a small amount of mineral oil, and (2) is preferred when obtaining a large amount of mineral oil.

  In the removal step (1), for example, the base oil obtained in the previous step is filtered using a mesh filter with a small mesh (for example, a 0.1-1 μm mesh membrane filter) and recovered as a mineral oil after removing impurities. To do. It is preferable to reduce the pressure during filtration because the time can be shortened. Since the base oil obtained in the previous step is a base oil containing an aromatic ring-containing additive and fullerene, the viscosity is kept low, so that flocs are less likely to occur when fullerenes aggregate during filtration, Filtering is stable. Therefore, filtering processing can be performed in a short time. In addition, because of low viscosity, formation of nanoparticle flocs hardly occurs, so a mesh filter with a small mesh can be used, and a mineral oil with a high degree of purification can be obtained. Moreover, what has a phenyl group as an additive which has an aromatic ring is preferable. This is because, even if the amount of dissolved fullerene changes, the change in viscosity is small, so that the removal treatment can be performed stably without causing clogging or a decrease in filtration rate during filtering.

  In the removing step (2), for example, the base oil obtained in the previous step is subjected to a centrifugal separation process, and the supernatant is recovered as a mineral oil after removing impurities. Since the base oil obtained in the previous step is a base oil containing an additive having an aromatic ring and fullerene, the viscosity is kept low, and it can be centrifuged for a short time or at a low speed. . Since the viscosity is low, the particles can be easily settled by centrifugation, and the particles can be easily separated and removed from the mineral oil, so that a mineral oil with a high degree of purification can be obtained. Moreover, what has a phenyl group as an additive which has an aromatic ring is preferable. This is because even if the amount of dissolved fullerene changes, the change in viscosity is small, so that separation does not become difficult and stable removal treatment can be performed.

(Use as mineral oil additive)
You may manufacture fullerene containing mineral oil by performing the process of adding the mineral oil obtained by the method mentioned above to the mineral oil which melt | dissolves base oil as a composition for mineral oil addition. This is because the mineral oil obtained in the previous step contains fullerenes in a high concentration, so that sufficient characteristics derived from fullerenes can be obtained even by further dilution. The additive composition can be added to the same mineral oil as the mineral oil that is the base oil of the composition, or it can be added to a different mineral oil. Examples of the different kinds of mineral oils include mineral oils with different additives, paraffinic and naphthenic mineral oils, mineral oils having different compositions thereof, mineral oils mixed with synthetic oils, and mineral oils mixed with vegetable oils.

(Obtained mineral oil)
The mineral oil produced in the present invention becomes a mineral oil in which fullerene is dissolved at a high concentration and the viscosity is kept low. Specifically, the viscosity difference is + 5% or less with respect to the viscosity of the mineral oil not containing fullerene, and the fullerene has a phenyl group and a molecular weight of 1000 or less. 50% by mass, 0.001 to 0.5% by mass with respect to the base oil, and a fullerene-containing mineral oil that does not contain particles of 1 μm or more in 10 ml of mineral oil. Such mineral oil can be suitably used as a lubricating oil because the desired high-concentration fullerene is dissolved to reduce impurities.

(Other)
Since the mineral oil of the present invention can be stably filtered, recycled mineral oil can also be used as a base oil within the scope of the present invention.

  In the present invention, an organic solvent or other conventionally used medium for assisting the solubility of fullerene can be appropriately added within the scope of the object of the present invention.

  In the present invention, an antiwear agent, a rust inhibitor, a cleaning dispersant, a viscosity index improver, a pour point depressant, and an antifoaming agent are appropriately added within the scope of the present invention in accordance with the use form of the mineral oil. You can also

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be modified or changed.

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

Example 1
Mineral oil (manufactured by ULVAC Kiko Co., Ltd .; SMR-100) was prepared as a base oil. Mixed fullerene (frontier carbon) in 1.5 L of mineral oil containing 5.6% by mass of tricresyl phosphate (special grade of Wako Pure Chemical Industries, Ltd.) (tricresyl phosphate) (molecular weight 1000 or less) as an additive having a phenyl group Co., Ltd. nanom (registered trademark) mix ST C60: 60%, C70: 25%, including other higher-order fullerenes) was added 7.5g (8.93 mass% with respect to the additive), stirrer And stirred for 36 hours. Next, it filtered by passing through a 0.1 μm mesh membrane filter to obtain a mineral oil containing 1.5 L of mixed fullerene. This mineral oil was confirmed to contain 0.38% by mass of fullerene by measuring the concentration by the UV method. The additive used is effective as an antioxidant and an extreme pressure additive.

  Viscosity was evaluated by measuring the viscosity using an E-type viscometer (Tokimec Co., Ltd.) and evaluating the increase rate relative to the base oil before adding the additive and fullerene.

  The solubility of fullerene was evaluated by measuring the absorbance (381 nm) using UV measurement (Shimadzu Corporation; UV-visible spectrophotometer UV-1700). A solubility of 0.05% by mass or more with respect to the mineral oil was indicated by ◯, less than 0.05% by mass was indicated by Δ, and less than 0.01% by mass was indicated by x.

The evaluation of filtering was performed by filtering 1.5 L of the obtained mineral oil through a 0.1 μm membrane filter and observing the filter.
The evaluation of impurities in the obtained mineral oil was conducted by observing the residual on the membrane filter after filtration with an electron microscope (SEM), and when particles of 1 μm or more were not confirmed (that is, 1 μm or more in 10 ml of mineral oil) It is said that the particles are not included.) “No problem”.

(Examples 2-4, Comparative Example 1, Comparative Example 2)
Mineral oil was obtained in the same manner as in Example 1 except that the amounts of additives and fullerenes were changed as shown in Table 1.

In each example and comparative example, the following products were used as additives.
Thiadiazole; Dainippon Ink Co., Ltd. Dilube R-100 (2,5-bis- (n-nonyldithio) -1.3.4-thiadiazole)
Dibenzyl disulfide; Wako Pure Chemical Industries, Ltd. First grade tributyl phosphate; Tokyo Chemical Industry Co., Ltd. special grade polymethacrylate; Sanyo Kasei Co., Ltd .: Include V815, number average molecular weight 20000

  The results of the above examples and comparative examples are shown in Table 1.

  As shown in Table 1, it can be seen that, in comparison with the comparative example having no aromatic ring, each of the examples having an aromatic ring can perform a stable filtering process and reduce impurities. Moreover, it turns out that the mineral oil obtained in the Example has low viscosity suppressed. In Examples 1 to 4 using an additive having a phenyl group having a substituent, it can be seen that there is no increase in viscosity even if the content of fullerene is changed.

(Example 5)
Mineral oil was obtained in the same manner as in Example 1 except that the fullerene was dissolved in the additive and then the obtained fullerene-containing additive was added to the base oil. The viscosity, solubility of fullerene, filtering status, and impurity status were the same as in Example 1.

(Example 6)
A mineral oil was obtained in the same manner as in Example 1 except that the additive and fullerene were added together to the base oil. The viscosity, solubility of fullerene, filtering status, and impurity status were the same as in Example 1.

(Example 7)
When 50 ml of a part of the mineral oil obtained in Example 2 is further added to 950 ml of the same mineral oil as the base oil and mixed, a mineral oil having a fullerene concentration of 0.019% is obtained with the viscosity unchanged. I was able to.

Claims (5)

A mineral oil containing no fullerene (hereinafter referred to as “base oil”), an additive having an aromatic ring, and a mineral oil containing fullerene,
10 ml of the mineral oil does not contain particles of 1 μm or more,
Mineral oil whose said fullerene content is 0.1-50 mass% with respect to an additive, and is 0.001-0.5 mass% with respect to a base oil.   The mineral oil according to claim 1, wherein the additive is an antioxidant.   The mineral oil according to claim 1 or 2, wherein the additive has a molecular weight of 1000 or less.   The mineral oil according to any one of claims 1 to 3, wherein the additive is a compound having a phenyl group which may have a substituent. The mineral oil according to any one of claims 1 to 3, wherein the additive is tricresyl phosphate or thiadiazole.