JP3818887B2 - Method for producing additive for lubricating oil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an additive for lubricating oil to be added to lubricating oil to be supplied to engines and gear boxes of automobiles and construction machines, or sliding parts of general machines.
[0002]
[Prior art]
Additives are added to engine oils used for lubricating engines such as automobiles and construction machinery for various purposes such as friction adjustment, viscosity index improvement, seizure prevention, and oxidation prevention. Among these, as an additive for friction adjustment, particularly for reducing the friction coefficient and wear, a material mainly composed of tetrafluoroethylene resin (polytetrafluoroethylene, PTFE) has been used.
[0003]
Tetrafluoroethylene resin is solid at room temperature. Although its own surface has a low coefficient of friction, its shape must be fine enough to be used as an additive for engine oil to be supplied to all parts of the engine that slide in a minute gap. Therefore, conventionally, when used as an engine oil additive, a tetrafluoroethylene resin is pulverized with a ball mill or the like to obtain a fine powder of about 10 to several μm.
[0004]
Such fine powders of tetrafluoroethylene resin are also supplied to the market from various manufacturers in the form as additives for lubrication. For example, from Asahi Glass Co., Ltd., a fine powdery tetrafluoroethylene resin having an average particle diameter (average particle diameter at 50 wt% by light transmission method) of 7 to 13 μm and a bulk density of 0.30 to 0.56 g / mL as an additive for lubrication ("Fullon (registered trademark) Lubricant L150J, L169J, L170J, L172J, L173J").
[0005]
[Problems to be solved by the invention]
The required characteristics of engine oil differ depending on the type of engine. The same applies to engine oil additives, and different additives are used for gasoline engines and diesel engines.
[0006]
One of the causes of the different required characteristics is an engine oil filter. Engine oil is filtered by a filter in order to prevent wear powder and the like from being sent to various parts of the engine, but the mesh (fineness) of the engine is greatly different between a gasoline engine and a diesel engine. That is, the diesel engine uses a finer mesh oil filter than the gasoline engine. Therefore, when an additive using fine powder of the conventional tetrafluoroethylene resin as described above is added to engine oil for diesel engines, the additive causes clogging in the oil filter, and engine oil is contained in each part of the engine. There is a problem that it is not delivered.
[0007]
As described above, the average particle diameter of the currently commercially available fine powder of tetrafluoroethylene resin is about 7 μm even at the finest. However, the mesh of an oil filter used in a diesel engine is about 1 μm, and conventional tetrafluoroethylene resin fine powder cannot be used as an additive for a diesel engine as it is. Therefore, it is conceivable to pulverize such a commercially available tetrafluoroethylene resin fine powder having an average particle size of about 7 μm with a ball mill to make it finer to about 1 μm, but with the ball mill, uniformly fine particles are obtained. There is a problem that it is difficult. If it is attempted to produce a fine powder having an evenly uniform particle size distribution and an average particle size of 1 μm or less, a very long time is required. However, even in such a case, the problem of deterioration of the base oil occurs due to such a long period of mechanical friction. Furthermore, the finer the powder, the easier it is for the fine powder particles to re-agglomerate, and eventually there is a problem that clogging of the filter cannot be eliminated.
[0008]
Therefore, as a result of intensive studies and experiments, the present inventor has achieved the above-described present invention.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the method for producing an additive for lubricating oil according to the present invention comprises adding tetrafluoroethylene resin fine powder to a base oil and subjecting it to a homogeneous dispersion treatment using a high-pressure homogenizer. Then, a pulverization process is performed by a ball mill so that the average particle size of the fine powder is 1 μm or less.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
A fine powder of ethylene tetrafluoride resin pulverized with a ball mill or commercially available is added to the base oil of the additive for lubricating oil. The fine powder of tetrafluoroethylene resin as a raw material may have an average particle diameter of about several tens to several μm. The amount of tetrafluoroethylene resin fine powder added to the base oil is 50 to 200 g (generally about 100 g) of tetrafluoroethylene resin fine powder per 1 L of base oil.
[0011]
This is continuously charged into a high-pressure homogenizer (pressure homogenizer) to perform a homogenous dispersion treatment. A high-pressure homogenizer is a machine that combines a high-pressure pump with a homogenous valve that can adjust the gap between the channels. The high-pressure pump uses a fluid to be treated (in this case, a mixture of base oil and fine powder of tetrafluoroethylene resin). ) And high pressure (homogeneous pressure; 500 to 2000 kg / cm ² ), and the high-pressure flow is ejected from the very fine gaps of the homogeneous valve to homogenize and disperse the fine powder suspension. It is. By adjusting the homogeneous pressure by the high-pressure pump and changing the size of the gap of the homogeneous valve, the homogeneous dispersion effect can be adjusted.
[0012]
Thereafter, the treatment liquid is put into a ball mill, and the fine powder is further pulverized so that the average particle diameter becomes 1 μm or less. Since the treatment liquid has been subjected to a homogenous dispersion treatment in advance, the pulverization treatment for reducing the average particle diameter to 1 μm or less with a ball mill can be completed in a short time, and there is almost no re-aggregation of the fine powder after the treatment.
[0013]
【The invention's effect】
By producing the additive by the method according to the present invention, the average particle diameter of the tetrafluoroethylene resin fine powder dispersed in the base oil can be reduced to 1 μm or less, and the dispersion state thereof becomes homogeneous. In addition, since the fine particles hardly reaggregate, a homogeneous dispersion state is maintained for a long time. Therefore, even if it is used in engine oil for diesel engines, the filter will not be clogged for a long period of time, and it can be added safely.
[0014]
Furthermore, the manufacturing time can be very short as compared with the case where no homogeneous dispersion treatment is performed. Moreover, since the temperature rise of the base oil at the time of a process can be suppressed, deterioration of a base oil can be suppressed to the minimum.
[0015]
As described above, the present invention was developed mainly for diesel engine oil additives, but it can be used for gasoline engine oils as well as the additive itself, such as gearboxes and pulverizers. It is also possible to add to the lubricating oil supplied to the sliding part of a general machine.
[0016]
【Example】
1st Example of the manufacturing method of the engine oil additive which concerns on this invention is described.
The fine powder of tetrafluoroethylene resin used is “Fluon (registered trademark) Lubricant L173J” manufactured by Asahi Glass Co., Ltd., and its properties are as follows.
Average particle size: 7μm
Bulk density: 0.30g / ml
Melting point: 330 ° C
Specific surface area: 8.2m ² / g
[0017]
“350NT” manufactured by Fuji Kosan Co., Ltd. was used as the base oil. Its properties are as follows.
Density (15 ° C): 0.890g / cm ²
Flash point: 230 ° C
Kinematic viscosity (40 ° C): 73.28mm ² / s
Kinematic viscosity (100 ° C): 8.2-10.2 mm ² / s
Viscosity index: 95
Pour point: -12.5 ° C
Residual carbon content: 0.03wt%
Total acid value: 0.02mgKOH / g
Color (ASTM): 1.5
Moisture: 100ppm
[0018]
After mixing these (hereinafter referred to as mixed oil), homogenous dispersion treatment was performed with a pressure homogenizer (high-pressure homogenizer) HA-4191 manufactured by Nippon Seiki Seisakusho. The structure of the main part of this homogenizer is shown in FIG.
[0019]
The mixed oil 11 applied with a high pressure (homogeneous pressure) of about 1500 kg / cm ² by the high pressure pump in the previous stage is supplied from the left side of FIG. 1, first hitting the surface of the homo valve 12 and changing its flow to a right angle, It ejects with explosive pressure outward from the minute gap 14 between the homovalve 12 and the homovalve seat 13. This jet flow collides with the inner surface of the breaker ring 15 provided around the gap 14, and further, the flow is changed to a right angle and discharged toward the low pressure portion 16. In such movement, the mixed oil 11 is given a large external shearing force, and among the fine powder of tetrafluoroethylene resin contained in the mixed oil 11, the aggregated and clustered particles are destroyed and individual fine particles are destroyed. Dispersed in powder. Further, among the tetrafluoroethylene resin fine powder, those having a particularly large particle size are pulverized, and the particle size distribution approaches a more uniform state.
[0020]
Thereafter, the average particle size of the fine powder can be easily reduced to 1 μm or less by pulverizing with a ball mill. Moreover, the once dispersed tetrafluoroethylene resin fine powder is maintained for a long time without being re-agglomerated.
[0021]
During the above-described production, particularly when performing homogeneous dispersion treatment with a high-pressure homogenizer, it is desirable that the temperature of the mixed oil 11 not exceed 40 ° C., for example, by using a cooling device. The reason for preventing the temperature of the mixed oil 11 from rising excessively in this way is as follows.
[0022]
First, the motility of the particles of the tetrafluoroethylene resin fine powder increases in proportion to the temperature of the mixed oil 11 increasing, and as a result, the particles easily reaggregate. In order to prevent this, it is necessary to suppress the temperature rise as much as possible.
[0023]
Secondly, the viscosity decreases in inverse proportion to the increase in the temperature of the mixed oil 11, but here, there is the following relationship between the viscosity and the shearing force.
S = D · η
S: Shear stress (kg / m · sec ² )
D: Shear rate (sec ^-1 )
η: Viscosity (kg / m · sec)
Therefore, when the shear rate is constant, the shear force is reduced in proportion to the decrease in the viscosity, that is, the cluster breaking effect and the large particle grinding effect are reduced.
[0024]
As described above, by preventing the temperature of the mixed oil 11 from rising excessively during the homogeneous dispersion treatment, the homogeneous dispersion effect in the base oil of the tetrafluoroethylene resin fine powder becomes more preferable. According to the experiments by the present inventors, it has been found that it is desirable to keep the treatment temperature in the high-pressure homogenizer at 40 ° C. or lower.
[0025]
In order to clarify the effect of the method for producing the engine oil additive according to the present invention, the mixed oil with the full oil lubrication L173J mixed with the base oil 350NT is pressurized at a pressure of 6 kg / cm ² and an oil filter of 1 μm mesh is applied. As a result, the oil filter was clogged when 20 L was passed. In contrast, when the engine oil additive produced in the above process was similarly passed through a 1 μm mesh oil filter, the oil filter was not clogged even when 60 L was passed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a main part of a homogenizer.
[Explanation of symbols]
11 ... Mixed oil 12 ... Homo valve 13 ... Homo valve seat 14 ... Gap 15 ... Breaker ring 16 ... Low pressure part

Claims (2)

After adding tetrafluoroethylene resin fine powder to the base oil and applying homogenous dispersion treatment using a high-pressure homogenizer, the ball powder is pulverized so that the average particle size of the fine powder is 1 μm or less. A method for producing an additive for lubricating oils. The method for producing an additive for lubricating oil according to claim 1, wherein the temperature of the object to be treated during the homogeneous dispersion treatment is maintained at 40 ° C or lower.

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