KR101292868B1 - Nano diamond having surface coated hydrophobical silane, method for manufacturing the same, and engine oil including the same - Google Patents

Abstract

Nanodiamond according to an embodiment of the present invention may be surface-coated with hydrophobic silane is uniformly dispersed without aggregation in oil. That is, hydrophobic groups may be provided to nanodiamonds having hydrophilic properties to improve dispersibility in hydrophobic solutions such as oils. Therefore, in one side of the present invention by treating the surface of the nanodiamonds with a hydrophobic group, by using such nanodiamonds as an engine oil additive, the dispersibility is improved in the engine oil can be improved wear resistance of the engine oil. In addition, the method for producing nanodiamonds according to one embodiment of the present invention can produce nanodiamonds surface-treated hydrophobicly without using a complicated device such as an autoclave.

Description

Nano diamond surface-coated with hydrophobic silane, a method for manufacturing the same, and an engine oil including the same {NANO DIAMOND HAVING SURFACE COATED HYDROPHOBICAL SILANE;

Disclosed are nanodiamonds surface-coated with hydrophobic silanes, methods for preparing the same, and engine oils comprising the same. More specifically, disclosed are nanodiamonds surface-coated with hydrophobic silanes having greatly improved dispersibility in engine oil, a method for preparing the same, and an engine oil including the same.

Recently, the use of lubricating oil has been increased under severe conditions such as high temperature, high load, and high speed, along with miniaturization and high speed of various rotating apparatuses, and development of high performance lubricating oil with excellent thermal oxidation stability is required. In order to be used in various mechanical devices such as reduction gears (consisting of gears, bearings, etc.) in the field of steelworks, high performance lubricants having excellent wear resistance are required.

Diamonds are known to have the highest value among gemstones, but are attracting attention as materials having excellent properties in almost all industries, including electronics and chemicals. Diamond has advantages such as high hardness, light transmittance over a wide range, chemical stability, high thermal conductivity, low thermal expansion, and electrical insulation. Recently, with the rapid development of nanotechnology, methods for producing diamond powder or thin film for effectively applying diamond properties have been developed. Among these diamond powders, micron size has already been widely used industrially.

Diamond powder has been applied as a coating agent on metal surfaces, polymer and rubber composites, abrasives, oil additives and the like. Diamond powder has a merit in that it is theoretically colorless and transparent so that its presence cannot be detected in appearance even when used as a coating agent or dispersed in a polymer plastic. However, although nano diamonds (NDs) are manufactured in a crystalline form, they may have impurities around the surface due to their strong surface reactivity. In this regard, various methods such as a method of oxidizing the surface to remove impurities from the surface of the nanodiamond and increase the applicability have been developed.

In the case where the nanodiamonds are surface treated, the nanodiamonds are expected to have various uses. Specifically, the surface-treated nanodiamonds may be added to a coating agent, a lubricating oil raw material, a polymer plastic, a ceramic hybrid material, or the like to impart functionality. Since nanodiamonds have hydrophilic properties, they are easy to disperse in polar solutions, but very difficult to disperse in hydrophobic solutions such as oils.

Until now, the method of treating the surface of nanodiamond with carboxyl group, amine group, etc. has been reported, but in the case of silane surface treatment which can be used for dispersing polymer filler or engine oil, it takes long treatment time and uses harmful solvent such as toluene and water. There has been a problem with removal, and has not been attempted.

Provided are nanodiamonds surface-coated with a hydrophobic silane having greatly improved dispersibility in engine oil, a method for preparing the same, and an engine oil including the same.

Nanodiamond according to an embodiment of the present invention is surface-coated with hydrophobic silane (hydrophobic silane).

In the nanodiamond according to one aspect of the present invention, the hydrophobic silane, octadecyl-trichloro-silane (OTS) and pentadecyl-trichloro-silane (Pentadecyl-Trichloro-Sillane, OTS) It can be selected from the group consisting of.

According to another aspect of the present invention, there is provided a method of preparing nanodiamonds, adding nanodiamonds to an alcohol solvent to form a first mixture, adding an acidic substance to the first mixture to form a second mixture, and Adding a hydrophobic silane to the second mixture and sonicating.

In the method for producing nanodiamonds according to one aspect of the present invention, the alcohol solvent may be selected from the group consisting of ethanol, methanol and isopropyl alcohol.

In the method for producing nanodiamonds according to one aspect of the present invention, the acidic material may be selected from the group consisting of hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ) and acetic acid (acetic acid).

In the method for producing nanodiamonds according to one aspect of the present invention, the hydrophobic silane, octadecyl-trichloro-silane (OTS) and pentadecyl-trichloro-silane (Pentadecyl-Trichloro-Sillane, OTS).

In the method of producing nanodiamonds according to one aspect of the present invention, the acidic material is mixed in a ratio of 0.4% by volume to 1.2% by volume with respect to the nanodiamonds, and the hydrophobic silane is 0.4% by volume with respect to 1.2% by volume with respect to the nanodiamonds. It can be mixed with.

In the method of manufacturing a nanodiamond according to one side of the present invention, the ultrasonication step may be performed in the range of 10 ~ 100 Watt (Watt).

The engine oil according to another embodiment of the present invention is selected from the group consisting of Octadecyl-Trichloro-Sillane (OTS) and Pentadecyl-Trichloro-Sillane (OTS) Nanodiamonds surface-coated with hydrophobic silanes.

Nanodiamond according to an embodiment of the present invention may be surface-coated with hydrophobic silane is uniformly dispersed without aggregation in oil. That is, hydrophobic groups may be provided to nanodiamonds having hydrophilic properties to improve dispersibility in hydrophobic solutions such as oils. Therefore, in one side of the present invention by treating the surface of the nanodiamonds with a hydrophobic group, by using such nanodiamonds as an engine oil additive, the dispersibility is improved in the engine oil can be improved wear resistance of the engine oil. In addition, the method for producing nanodiamonds according to one embodiment of the present invention can produce nanodiamonds surface-treated hydrophobicly without using a complicated device such as an autoclave.

Figure 1a is a view showing the SEM measurement results of the nanodiamond prepared in Example 1. Figure 1b is a view showing the SEM measurement results of the nanodiamond prepared in Example 2. Figure 1c is a view showing the SEM measurement results of the nanodiamond prepared in Example 4.
Figure 2a is a view showing the dispersibility test results of the engine oil prepared in Example 5. Figure 2b is a view showing the dispersibility test results of the engine oil prepared in Example 6.
3 is a view showing the results of analyzing the wear test performed on the oil prepared in Example 7 and Comparative Examples 1, 2, 3 with an optical microscope (OM).
4A to 12C show the results of testing the dispersibility of hydrophobic silane-coated nanodiamonds prepared in the same manner as in Example 2 after changing the volume of HCl and OTS to 2 ml, 4 ml, and 6 ml, respectively. to be.
13A to 13B are diagrams illustrating delta T graphs for respective ratios of HCl and OTS in FIGS. 4A to 12C.
14A to 14B are diagrams illustrating delta BS graphs for respective ratios of HCl and OTS in FIGS. 4A to 12C.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Nanodiamond according to an embodiment of the present invention is surface-coated with hydrophobic silane (hydrophobic silane). In one aspect of the invention, the hydrophobic silane is selected from the group consisting of octadecyl-Trichloro-Sillane (OTS) and pentadecyl-Trichloro-Sillane (OTS) Can be. In addition, the hydrophobic silane may be a silane having a variety of chain lengths (chain length), it is not limited to the above examples.

Among the silanes having various chain lengths, the shorter chain length silane is cheaper and more economical and coated. The long chain length silane has excellent dispersibility. In one side of the present invention by using a silane having a variety of chain length it can provide a silane that can be applied for multi-purpose by coating the chain of silane.

Therefore, the nanodiamond according to one side of the present invention can be surface-coated with hydrophobic silane can be uniformly dispersed without aggregation in oil. That is, hydrophobic groups may be provided to nanodiamonds having hydrophilic properties to improve dispersibility in hydrophobic solutions such as oils.

In addition, in one side of the present invention by using the nanodiamonds treated with a hydrophobic group on the surface of the nanodiamonds as an engine oil additive, dispersibility is improved in the engine oil, thereby improving wear resistance of the engine oil.

According to another aspect of the present invention, there is provided a method of preparing nanodiamonds, adding nanodiamonds to an alcohol solvent to form a first mixture, adding an acidic substance to the first mixture to form a second mixture, and Adding a hydrophobic silane to the second mixture and sonicating.

Nanodiamond is added to the alcohol solvent to hydrophobically surface the nanodiamond surface. In this case, the alcohol solvent may be selected from the group consisting of ethanol, methanol and isopropyl alcohol, but is not limited thereto. In addition, the amount in which the alcohol solvent and the nanodiamond are mixed is not particularly limited. However, the alcohol solvent may be provided in an amount sufficient to disperse the following hydrophobic silane well.

Thereafter, an acidic substance is added to the alcohol solvent mixed with the nanodiamonds. In this case, the acidic material may be selected from the group consisting of hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ) and acetic acid (acetic acid), but is not limited thereto.

The pH of the mixture may be changed by adding the acidic material, and thus the dispersibility of the nanodiamonds coated with the hydrophobic silanes described below may be changed. In one side of the invention the pH of the mixture according to the addition of the acidic material may be pH 5.0 ~ pH 4.5.

Thereafter, hydrophobic silane is added to the acidic substance at a predetermined ratio and then ultrasonicated. In this case, the hydrophobic silane may be selected from the group consisting of octadecyl-Trichloro-Sillane (OTS) and pentadecyl-Trichloro-Sillane (OTS), but various The silane material having a chain is not limited thereto.

In one aspect of the present invention, the acidic material may be mixed at a ratio of 0.4% by volume to 1.2% by volume with respect to nanodiamonds, and the hydrophobic silane may be mixed at a ratio of 0.4% by volume to 1.2% by volume with respect to nanodiamonds. As confirmed in the following examples, the dispersibility of nanodiamonds when the hydrophobic silane is 0.4% by volume is excellent, and the dispersibility of the nanodiamonds is 0.4% by volume or more when the acidic material is 0.4% by volume. It can be seen that better. In addition, it can be seen that the dispersibility of the nanodiamonds is better when the acidic substance and the hydrophobic silane are mixed at a ratio of 0.8% by volume or 1.2% by volume rather than 0.4% by volume, respectively.

The ultrasonication may be performed in the range of 10 to 100 watts, and preferably in the range of 20 to 50 watts. Here, the ultrasonic treatment refers to the irradiation of ultrasonic waves to coat the silane on the surface of the nanodiamond. The sonication may be performed for a certain time, for example for 2 hours or more. In addition, the sonication may be performed a plurality of times, in order to prevent the agglomeration or sedimentation of some nanodiamond particles after the initial sonication. In the ultrasonic treatment, the longer the duration of the initial sonication, the longer the nanodiamond particles maintain dispersibility in the solvent and the longer the reaction, so that more nano diamond particles may be coated. However, in order to prevent the particles from agglomerating or settling as described above, two or more ultrasonic treatments may be performed.

Therefore, the method for producing nanodiamonds according to one embodiment of the present invention can produce nanodiamonds surface-treated hydrophobicly without using a complicated device such as an autoclave. In addition, it is possible to secure a price competitiveness because the use of low-cost silane has a large cost reduction effect in mass production.

Hereinafter, embodiments of the present invention will be described in detail.

Example 1 After adding 5 g of nanodiamond to 500 ml of ethanol, the mixture was stirred for 1 minute with a stirrer to prepare a first mixture. Thereafter, 2 ml of 0.025 M hydrochloric acid (HCl) was added to the first mixture, which was then stirred with a stirrer to prepare a second mixture. Thereafter, 1 ml of octadecyl-trichloro-silane was added to the second mixture, followed by ultrasonic treatment for 2 hours, followed by drying to obtain nanodiamond powder.

(Example 2) After adding 5 g of nanodiamond to 500 ml of ethanol, the mixture was stirred for 1 minute with a stirrer to prepare a first mixture. Thereafter, 2 ml of 0.025 M hydrochloric acid (HCl) was added to the first mixture, which was then stirred with a stirrer to prepare a second mixture. Thereafter, 2 ml of octadecyl-trichloro-silane was added to the second mixture, followed by ultrasonic treatment for 2 hours, followed by drying to obtain nanodiamond powder.

Example 3 After adding 5 g of nanodiamond to 500 ml of ethanol, the mixture was stirred for 1 minute with a stirrer to prepare a first mixture. Thereafter, 1 ml of 0.025 M hydrochloric acid (HCl) was added to the first mixture, which was then stirred with a stirrer to prepare a second mixture. Thereafter, 2 ml of octadecyl-trichloro-silane was added to the second mixture, followed by ultrasonic treatment for 2 hours, followed by drying to obtain nanodiamond powder.

(Example 4) 10% by weight of the nanodiamonds prepared in Example 1 were dispersed in an engine oil (Helix) to prepare an engine oil to which nanodiamonds were added.

Example 5 An engine oil to which nanodiamonds were added was prepared by dispersing 10 wt% of the nanodiamonds prepared in Example 2 in an engine oil (Helix).

Figure 1a is a view showing the SEM measurement results of the nanodiamond prepared in Example 1. It was confirmed that the silane was not coated when it was seen that no Si element was observed in FIG. 1A.

Figure 1b is a view showing the SEM measurement results of the nanodiamond prepared in Example 2. It can be seen that the silane was coated on the surface of the nano diamond as the Si element was present in FIG. 1B.

As a result, when the octadecyl-trichloro-silane is added at least 0.4% by volume compared to the nanodiamond from Figure 1b it can be seen that the coating layer is safely coated.

Figure 1c shows the SEM measurement results of the nanodiamonds prepared in Example 3, it was confirmed that the silane was not coated because the Si element could not be measured. Compared with Example 2, when the amount of HCl was reduced to 1 ml as in Example 3, the silane was not coated, and it was confirmed that HCl should be added more than 0.4% by volume.

As a result, as shown in Figures 1a to 1c, octadecyl-trichloro-silane is added to the silane to be added at least 0.4% by volume relative to the nanodiamond, and HCl is also known to be coated by the addition of 0.4% by volume or more relative to the nanodiamond. Can be.

Figure 2a is a view showing the dispersibility test results of the engine oil prepared in Example 4. In Figure 2a it was confirmed that the oil dispersibility is not good because the silane is not coated.

Figure 2b is a view showing the dispersibility test results of the engine oil prepared in Example 5. In Figure 2b it was confirmed that the dispersibility of the nano-diamond surface-coated with hydrophobic silane. That is, it can be seen from FIG. 2b that the delta T and delta BS values with time change show a certain value, or that the lower the slope, the more stable the dispersibility of the nanodiamonds.

Here, delta T and delta BS represent the rate of change of Transmission (T) and BackScattering (BS). When the particles are settled or aggregated, since delta T and delta BS are large, dispersibility is not good. Thus, as shown in FIG. 2B, the delta T and delta BS values as shown in FIG. It can be seen that the lower the better the dispersibility of the nanodiamonds.

(Example 6) 1 volume% of the engine oil prepared in Example 5 was put back into the engine oil (helix) to prepare an oil for wear test. That is, a part of the engine oil prepared in Example 5 was diluted to 1/100 in the engine oil (helix) to prepare a wear test oil.

Example 6 The oil obtained in the wear track (wear track) is 6 nm in diameter loaded with a Al ₂ O ₃ on the gray cast iron substrate (load) 10 N, the rotation speed (rotation speed) 10 cm / s , distance 1 km conditions Abrasion tests were performed at.

(Comparative Example 1) An abrasion test was performed on engine oil (helix) not containing nanodiamonds under the same conditions as described above.

(Comparative Example 2) Abrasion test was carried out under the same conditions as above using a nanotablet oil of Nanotechnology, a commercial product.

Comparative Example 3 A wear test was performed under the same conditions as described in Example 6 using Sinta's nanodiamonds.

3 is a view showing the results of analyzing the wear test performed on the oil prepared in Example 6 and Comparative Examples 1, 2, 3 with an optical microscope (OM). In Figure 3, Example 6 is Nano Diamond Oil (1%), Comparative Example 1 is Shell co. Helix oil, Comparative Example 2 is Nano Doctor Oil (4%), Comparative Example 3 is Sinta Nano Diamond Oil, the substrate is a gray cast iron.

Referring to FIG. 3, it was confirmed that the oil in which the nanodiamonds prepared in Example 6 were dispersed showed the shape of the substrate track most clearly, and thus the wear reduction effect was excellent.

4a to 12c is a view showing the results of testing the dispersibility of the hydrophobic silane-coated nanodiamond prepared in the same manner as in Example 2 after changing the volume of HCl and OTS to 2 ml, 4 ml, 6 ml, respectively to be.

4A to 12C, the ratio of HCl: OTS is based on ml, and when converted into volume%, 2 ml means 0.4 volume%, 4 ml means 0.8 volume%, and 6 ml means 1.2 volume%.

4A to 6C, it can be seen that the amount of OTS has the best dispersibility of nanodiamonds when the amount of OTS is 2 ml (0.4 vol%), among which the amount of HCl is 2 ml (0.4 vol%). 4 ml (0.8% by volume), 6 ml (1.2% by volume) it can be seen that the better dispersibility.

7A to 9C and 10A to 12C, when HCl is 4 ml (0.8% by volume) and 6 ml (1.2% by volume), respectively, the dispersibility of the nanodiamonds varies according to OTS. It can be confirmed that there is no.

Each figure in FIGS. 4C-12C shows Transmission (T) and BackScattering (BS) showing the bottle of the actual sample over time as a graph on Turbiscan. On this figure it can be seen that over time the nanodiamonds settle from the top of the actual sample bottle.

13A to 13B are diagrams illustrating delta T graphs for respective ratios of HCl and OTS in FIGS. 4A to 12C.

14A to 14B are diagrams illustrating delta BS graphs for respective ratios of HCl and OTS in FIGS. 4A to 12C.

Referring to FIGS. 13A to 14B, the total dispersion test results of nanodiamonds coated with hydrophobic silane showed that OTS is 0.4% by volume and HCl is changed to 0.4% by volume, 0.8% by volume, and 1.2% by volume. Dispersibility was shown. Furthermore, it could be seen that when OTS is 0.4% by volume and HCl is 0.4% by volume, OTS is 0.4% by volume, HCl is 0.8% by volume and 1.2% by volume, which shows better dispersibility.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (9)

delete delete Adding nanodiamonds to the alcohol solvent to form a first mixture;
Adding an acidic substance to the first mixture to form a second mixture; And
To the second mixture is added a hydrophobic silane selected from the group consisting of octadecyl-Trichloro-Sillane (OTS) and pentadecyl-Trichloro-Sillane (OTS) and ultrasonically Processing;
Lt; / RTI >
The acidic material is mixed in a ratio of 0.4% to 1.2% by volume relative to the nanodiamond,
The hydrophobic silane is mixed at a ratio of 0.4% by volume to 1.2% by volume with respect to the nanodiamond,
The acidic material is selected from sulfuric acid (H ₂ SO ₄ ) and acetic acid (acetic acid),
The ultrasonication step is to be carried out two or more times for 2 hours or more in the range of 20 to 50 Watts (Watt),
Method for preparing nanodiamonds surface-coated with hydrophobic silanes.
The method of claim 3,
The alcohol solvent is selected from the group consisting of ethanol, methanol and isopropyl alcohol.
delete delete delete delete delete

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