JPS638160B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the petroleum industry, and more particularly to a method for removing solid impurities in the purification process of a non-aqueous solution of an anti-sludge lubricant additive containing solid impurities originating from the synthesis reaction of the anti-sludge lubricant additive. . The present invention is useful for improving the operational performance of lubricating oils, and more particularly automotive oils. The use of additives in lubricating oils can reduce wear and deposits on automotive parts, thereby increasing engine reliability and extending its service life. One of the most important classes of lubricating oil additives used in internal combustion engines are anti-sludge agents or detergents. Adding this additive to lubricating oils can prevent carbonaceous impurities (resins and residues) from depositing on engine components. The effect of anti-sludge agents is to keep insoluble products formed in the oil and carbonaceous compounds that enter the oil from the outside in a finely dispersed state, thereby eliminating the deposit of these products on engine parts. Based on what you do. Anti-sludge lubricating oil additives include barium or calcium salts of polymeric hydrocarbon sulfonic acids, barium salts of alkylphenol disulfides, calcium diester dithiophosphates, oily solutions of zinc dialkyldithiophosphates and barium alkylphenols. It has been known. Known methods for removing impurities from anti-sludge agents, such as sulfonates, are based on separating the impurities from a dehydrated solution. To this end, the water is distilled off from the anti-sludge agent after the synthesis step and the water-free anti-sludge solution is then repeatedly filtered or centrifuged. Repeated centrifugation of the anti-sludge solution was first carried out in a centrifuge with a separation factor of 1000, and then
Partially purified anti-sludge solution with separation factor
15,000 centrifuge to finally separate the solid phase. This conventional impurity separation method had low efficiency. This is based on the small difference in mass between the dispersoid and the dispersion medium and the small particle size of the compound particles contained therein. The pollution degree of solid impurities of the sludge inhibitor treated by the prior art is 2000-5000 mg/100 g of product, which contains 10 times more impurities than the world standard value, ie less than 500 mg/100 g. Furthermore, since the centrifuge and separation equipment are used for a long time, energy consumption is large. There are also other known methods of separating impurities from anti-sludge agents (see US Pat. No. 3,523,896).
According to this method, 0.3 to 10% by weight of water and 1 to 15% by weight of methanol are added to the sludge inhibitor prepared by the prior art to improve its composition.
However, before the impurities are removed, this liquid is distilled at a temperature of 240-300°C and the diluent and anti-sludge containing the balance of water and methanol are sent to the filter. Cloth is used as the material, and the resulting liquid is sent to a distillation device. According to this method, methanol and water are separated before the step of separating impurities from the anti-sludge agent. However, the method of purifying the sludge inhibitor, which involves separating impurities from a dehydrated solution, is not only labor-intensive and inefficient, but also fails to provide a highly pure product with a contamination level of 500 mg/100 g or less. The aim of the invention is to eliminate the above-mentioned drawbacks. It is an object of the present invention to provide a method for removing impurities from anti-sludge lubricating oil additives to improve their dirtiness with respect to impurities. The above object of the present invention is to add a polar liquid having a dielectric constant of 17 or more from 0.025 to 0.025 to a lubricating oil additive solution for preventing sludge.
This can be accomplished by a process for removing impurities in anti-sludge lubricant additives by adding 10% by weight and then separating the impurities by phase separation. The present invention makes it possible to remove impurities in the particle size fraction of 0.5 to 5μ, which are difficult to remove, after producing an additive for preventing sludge, thereby producing an anti-sludge agent with an impurity content of 500 mg or less/100 g. We were able to. Furthermore, the present invention simplifies the purification device and provides a labor-intensive multistage centrifugal separation purification device.
That is, a centrifuge with a separation factor of 1000 and an ultracentrifuge with a separation factor of 15000 were replaced with a single automatic centrifuge or sedimentation device. This is because after coagulating the impurity, the settling rate of this impurity increases to 1000 times the settling rate of the impurity in the initial additive. According to the present invention, it is desirable to add a polar solution adsorbed on a solid support to the anti-sludge solution. Furthermore, according to the present invention, the amount of solid carrier used can be reduced by
A range of 0.01 to 10% by weight of the anti-sludge agent is recommended. Furthermore, according to the present invention, it is preferred that the particle size of the solid carrier is 5 to 10 times the fraction particle size of 0.5 to 5 microns, which accounts for most of the solid impurities in the sludge inhibitor. According to the present invention, the polar solution with which the surface of the solid support is wetted is a solution having a relative dielectric constant of 17 or more, so that the heterogeneous coagulation of impurities can be carried out more quickly and effectively. This is because the rate of coagulation is proportional to the area of the interface, and by increasing the surface area of the solid carrier, the rate of purification of the sludge inhibitor can be substantially increased. During the purification of the anti-sludge agent, it is recommended to use calcium hydroxide or calcium carbonate as a solid carrier in order to prevent the introduction of external impurities into this solution. In an embodiment of the invention, after the polar solution is added to the anti-sludge solution, a non-uniform electrostatic field generated by a pulsed voltage of constant polarity is applied for phase separation. A non-uniform electrostatic field means an electrostatic field generated between electrodes having different areas, and a non-uniformity coefficient means a ratio between electrode areas. According to the invention, it is recommended to use an electrostatic field with a strength of 0.1-5 kV/cm and a non-uniformity factor of 5-50. By using a non-uniformly oriented electrostatic field, the rate of phase separation can be substantially increased to rapidly and effectively remove impurities from the anti-sludge agent. Furthermore, the above embodiments of the invention are capable of precipitating and separating impurities within a single device. Other objects and benefits of the present invention will become more apparent from the following detailed description and examples of methods for removing solid impurities from anti-sludge additives added to lubricating oils. The sludge inhibitors that can remove solid impurities according to the present invention are as follows. That is, barium or calcium salts of polymeric hydrocarbon sulfonic acids, calcium alkylsalicylates, barium salts of alkylphenol disulfides, calcium diester dithiophosphates, oily solutions of zinc dialkyldithiophosphates and barium alkylphenols. As is well known, after the sludge inhibitor is synthesized, the impurities present in it are mainly calcium hydroxide and calcium carbonate, and of these impurities, the fraction with a particle size of 0.5 to 5μ accounts for about 70% by weight, and the particles The fraction with a diameter of 4μ or less is about 30% by weight. When the anti-sludge agent added to the lubricating oil is subjected to phase separation, for example, by centrifugation, it is preferred according to the present invention that the coagulation and precipitation of impurities be carried out in the presence of a polar liquid with a dielectric constant of 17 or more. Examples of polar liquids with a dielectric constant of 17 or higher include ketones such as acetone and methyl ethyl ketone;
Alcohols such as methanol, ethanol, propanol, butanol, isopropanol, isobutanol, ethylene glycol, aqueous solutions of glycerol, water, and aqueous solutions of alkali or alkaline earth metal nitrates can be used. The addition of polar compounds to precipitate contaminating impurities is based on the fact that the polar compounds are selectively adsorbed onto the hydrophilic particles of the solid phase of the impurities. Therefore, the water wets the inorganic particles that are the contaminants in the anti-sludge agent rather than the anti-sludge molecules. This is clear by comparing the heat of adsorption of water molecules to these molecules, which is 1.88 cal/g for calcium sulfonate molecules of the sludge inhibitor, while that of impurity particles recovered from the unpurified sludge inhibitor solution. It is 25 to 26 cal/g. As the anti-sludge molecules detach from the impurity particles when they are adsorbed by water, the particles lose stability and coagulate outside the wetted area. It has been found that the amount of polar solution having the above properties added to the sludge inhibitor to be purified is preferably from 0.25 to 10% by weight. This value ensures that the added polar liquid is completely adsorbed onto the impurity particles without forming a separate phase and is then virtually completely removed along with the impurities when separating the phases of the anti-sludge solution. It was decided that The residue formed by coagulation of solid particles precipitates according to the principle of coprecipitation of particles, forms a clear interface, and undergoes phase separation. The larger aggregates produced are accompanied by smaller particles, which are adsorbed onto the residue and have a significant effect of clarifying the liquid. The anti-sludge solution is highly stable when no coagulant is added, which is a polar solution with a dielectric constant greater than 17. When the amount of coagulant added is less than 0.025% by weight, the impurity particles do not coagulate, which can be explained by the high solubility of the anti-sludge agent.
When the amount of coagulant added exceeds 1.0% by weight, the stability of impurity particles in the sludge inhibitor solution is lost, and the coagulation process of impurities begins to proceed.
Do not exceed mm/h. When the amount of polar solution added increases to 10.0% by weight, the rate of impurity residue formation and its sedimentation rate decreases even without using forced separation method.
Reaching over 200mm/h. Therefore, if the amount of polar solution added in the anti-sludge solution is 5 to 10% by weight, the phase separation step can be carried out in a sedimentation device. The mixing of the polar solution and the anti-sludge agent is preferably carried out using a high speed mechanical stirrer at 5000 rpm to enhance the coagulation effect. Coagulation in industrial equipment is carried out in hydraulic mixers. However, if a polar solution adsorbed on a solid support with a particle size of 2.5 to 50 microns is added to the anti-sludge solution, a similar coagulation effect can be obtained without the use of a hydraulic mixer. As solid carriers, various inorganic salts such as sodium chloride, sodium carbonate, sodium nitrate, calcium nitrate can be used, and hydrophilic powders such as filtroperlite, silica gel, Hyfura supergel can be used.
However, it is recommended to use calcium hydroxide or calcium carbonate as solid carrier. This is because these compounds are the basic constituents of impurities in the anti-sludge agent and the addition of this carrier to the anti-sludge solution does not create additional contamination. As mentioned above, the particle size of the impurity fraction that is difficult to remove is 0.5 to 5μ, so the particle size of the carrier is 5 to 10 times larger than the particle size of this fraction, that is, 2.5 to 50μ.
Should be. On the one hand, when the particle size difference between the solid impurity and the carrier is large, heterogeneous coagulation is carried out quickly and effectively, but on the other hand, when the particle size of the carrier increases, its specific surface area decreases and the coagulation effect becomes less effective. Decrease. It is optimal to select the ratio of the particle sizes of the solid impurity and the carrier to the above ratio, and the effect of heterogeneous coagulation is the best. When a polar solution adsorbed on a solid support is added to the anti-sludge agent, it is necessary that the polar solution be in the form of a thin film that is close to the thickness of a monolayer. In this state, the coagulation effect of the polar solution is large, and therefore the effect of purifying the sludge inhibitor is large. Taking into account this point and the above-mentioned optimum amount of polar solution added, it can be decided to add a carrier with a wetting ratio of 0.1 to 50% in the range of 0.01 to 10% by weight relative to the weight of the sludge inhibitor. It has been found that adding a polar solution to the anti-sludge agent substantially changes the electrodynamic properties of the solid impurity. That is, the electrophoresis of the precipitated impurity particles in an electric field increases three to four times, and the zeta potential of the solid impurity increases as the difference in dielectric constant between the dispersoid and the dispersion medium increases. In the absence of a polar solution, the impurity particles in the anti-sludge agent have a weak positive charge, and the circulation between the electrodes in the electric field and the phenomenon of electrical double layer are not observed, and these electrodynamic Nature doesn't really matter. By weight of anti-sludge lubricant additive
When 0.025-10% by weight of a polar solution is added to the anti-sludge agent, the zeta potential of the impurity particles increases and unidirectional electrophoresis is observed. That is, a solid phase is deposited on the electrode. When the deposited impurities were electrophoretically coagulated and electrodynamically investigated, it was found that the deposited electrode surface had a positive charge. Due to this property, the surface of the deposited electrode can be easily cleaned by changing the discharge polarity of the deposited electrode for 10 to 15 seconds. When the deposition electrode is a rotating disk, the resulting substantially liquid-free deposit of solid impurities can be continuously removed with a blade-like member. Therefore, if the anti-sludge solution is phase-separated in a non-uniform electrostatic field generated by a pulsed voltage of constant polarity after adding a polar solution, impurities in the anti-sludge agent can be quickly and effectively removed. found. This phase separation embodiment allows the coagulation and separation of impurities in the anti-sludge agent to be removed in a single device. The strength range of the electrostatic field used in the method of the present invention is 0.1 to 5 kV/cm, and the nonuniformity coefficient range of the electrostatic field is 5 to 50 units. Also, to create an electrostatic field, a rectified voltage that does not smooth the R-C circuit,
That is, it is preferable to use a constant polarity pulse voltage having a half-wave frequency of 100 Hz. As the electrostatic field strength increases, the electrophoretic velocity of impurity particles in the anti-sludge agent increases, but the value of the electrostatic field strength at which dielectric breakdown is observed in solutions containing 0.025 to 10% by weight of polar solution is Must not be exceeded. Conditions in which the electrostatic field strength is 1 to 3 kV/cm are optimal for coagulation and separation of impurity particles. The electrostatic field non-uniformity factor varies depending on the solid phase content in the anti-sludge agent. The higher the solid phase content, the higher the non-uniformity coefficient of the electrostatic field. Solid phase content is 7840
When changing from mg/100g to 770mg/100g,
Change the non-uniformity factor from 50 to 5. EXAMPLE 1 This example describes a method for removing impurities from a petroleum sulfonic acid calcium salt-based sludge inhibitor prepared by a known method as described below. As a raw material for preparing the calcium sulfonate salt, an oily solution containing 40 to 60% sulfonic acid with a viscosity of 40 to 60 cSt at a temperature of 50 °C is obtained by sulfonating petroleum with a molecular weight of 350 or more and a viscosity of 10 to 14 cSt at a temperature of 50 °C. was generated. The ash content of the sulfonate is at least 5% by weight
To obtain a neutral sulfonic acid calcium salt with a pH of 7, put this oily sulfonic acid solution into a blender,
Add mineral oil with a viscosity of 10 to 14 cSt at a temperature of 50°C as a diluent to determine the viscosity of the total solution at a temperature of 100°C.
Calcium hydroxide was added after pre-reduction to 20-25 cSt. To determine the ash content of the sulfonate, a portion of the sulfonic acid calcium salt solution in the presence of the sulfonic acid is weighed, evaporated to dryness, and the resulting solid residue is sintered until a quantitative amount is obtained. did. Further, the above suspension was stirred at a speed of 1460 rpm.
Note that petroleum sulfonic acid was neutralized with calcium hydroxide at a temperature range of 80 to 95°C. The ash content of the sulfonate is at least 5% by weight
After preparing the neutral sulfonic acid calcium salt with pH=7, the alkalinity is 100-130 mg KOH/100 g, and the ash content of the sulfonate is at least
A high ash petroleum sulfonic acid calcium salt of 17% by weight was prepared. This ash content and alkalinity are necessary to impart the desired properties to the anti-sludge agent. For this purpose, 20% phenol was added as a catalyst to the neutral calcium sulfonate in the mixer to complete the production of high ash calcium sulfonate. Next, 6-7% by weight of calcium hydroxide was also added to the mixer. The resulting mixture was heated to a temperature of 102°C and kept at this temperature for 1 hour. The reaction product is then gradually heated to a temperature of 125°C to evaporate the water,
The reaction product was kept at this temperature for 1 hour. The reaction product was then passed with 5% by volume of CO ₂ for 2 hours at 0.7 atmospheres gauge pressure and 125°C. The temperature of the reaction product was then lowered to 80°C and the pressure was brought to atmospheric pressure. The reaction was considered complete if the resulting oily calcium sulfonate solution had a sulfonate ash content of 17% by weight. For a thorough analysis, the product in the resulting oily solution is sucked into a vacuum column and the vacuum level is 30-40 mm.
With Hg, the temperature was gradually increased to 180-200°C to evaporate the catalyst phenol and remove it until its content was below 0.5% by weight. The initial turbidity of the sulfonate anti-sludge solution thus obtained was 3850 mg/100 g. The resulting sludge inhibitor solution has a specific gravity of 0.7~
0.8, a solvent consisting of hydrocarbons with a boiling point range of 80-120℃
Added 50% by weight. Next, 7.5% by weight of water (relative dielectric constant 78.3) was added to this solution at room temperature. After centrifugation for 5 minutes in a centrifuge with a separation factor of 1000, a sulfonate sludge inhibitor with an impurity content of 110 mg/100 g was obtained. Example 2 The impurity content of an oily anti-sludge solution consisting of calcium alkyl salicylate prepared by a known method was 7950 mg/100 g. 100g of this solution
2 g of a 20% carrier suspension was added to the solution at a temperature of 125°C. The carrier had a particle size of 2.5-50μ and the suspension was prepared by adding a mineral oil diluent with a viscosity of 10-14 cSt at a temperature of 50°C. For this preparation, 5% by weight of water (dielectric constant 78.3) based on the weight of the carrier was added with vigorous stirring. The coagulated precipitate was centrifuged in a centrifuge with separation factors of 1000 and 15000. Separation factor 1000 1st
After centrifugation, the impurity content of the sludge inhibitor is 540mg/100g (solid impurity content 0.011% by weight)
It was hot. After the second centrifugation with a separation factor of 15000, the impurity content of the anti-sludge agent is 90mg/100g
(Solid impurity content: 0.008% by weight). Example 3 The impurity content of an oily anti-sludge solution consisting of a sulfonate salt was 7840 mg/100 g. Glycerin (relative dielectric constant
10 g of suspension of 42.4) was added. Suspension temperature 50
It was prepared in a mineral oil diluent with a viscosity of 10-14 cSt at °C, to which 50% by weight of the carrier weight of glycerin was added while stirring vigorously. The coagulated precipitate has a separation factor of 1000 and 15000
Separated using a centrifuge. After the first centrifugation with a separation factor of 1000, the impurity content of the anti-sludge agent is 650 mg/100 g (solid impurity content 0.035% by weight)
It was hot. After the second centrifugation with a separation factor of 15000, the impurity content of the anti-sludge agent is 150mg/100g
(Solid impurity content: 0.02% by weight). Example 4 The impurity content of an oily anti-sludge solution consisting of a barium salt of an alkylphenol disulfide was 2100 mg/100 g. Hydrocarbons having a specific gravity of 0.7 to 0.73 and a boiling point range of 80 to 130°C were added to 100 g of this solution at a volume ratio of 1:1.5. While stirring this at a temperature of 60℃, a 50% suspension of silica gel carrier with a particle size of 2.5 to 50μ is prepared.
Added 20g. This suspension was prepared with a hydrocarbon solvent, and an aqueous solution of methyl ethyl ketone (relative dielectric constant 18.6) was added to this with vigorous stirring to obtain a carrier with a 0.5
It was expressed as weight%. After centrifuging for 5 minutes at a separation factor of 1000, the impurity content of the anti-sludge agent was 100 mg/100 g (solid impurity content 0.009% by weight). Example 5 An oily anti-sludge solution consisting of barium petroleum sulfonate prepared as described in Example 1 had an initial slurry concentration of 6400 mg/100 g. This solution 100
A hydrocarbon solvent having a specific gravity of 0.7 to 0.73 and a boiling point range of 80 to 130° C. was added to the solution in a volume ratio of 1:1.5. While vigorously stirring this mixture at a temperature of 60°C, a 10% by weight aqueous solution of 0.1M/isopropanol (relative dielectric constant 18.3) was prepared.
added. After centrifuging for 5 minutes at a separation factor of 1000, the impurity content of the anti-sludge agent was 110 mg/100 g (solid impurity content 0.020% by weight). Example 6 Oily anti-sludge solution consisting of barium petroleum sulfonate with an initial degree of contamination of 6400 mg/100 g
A hydrocarbon solvent having a specific gravity of 0.7 to 0.73 and a boiling point range of 80 to 130° C. was added to 100 g at a volume ratio of 1:1.5. While vigorously stirring this mixture at a temperature of 60℃, the dielectric constant
0.75% by weight of a 0.1M/aqueous calcium nitrate solution, which is a polar liquid of 17 or higher, was added. After centrifuging for 5 minutes at a separation factor of 1000, the impurity content of the anti-sludge agent was 80 mg/100 g (solid impurity content 0.02% by weight). Example 7 An oily anti-sludge solution consisting of calcium diester dithiophosphate has an initial turbidity of 3850.
mg/100g. 100g of this solution has a specific gravity of 0.7.
~0.73, a hydrocarbon solvent with a boiling point range of 80-130°C was added in a volume ratio of 1:1.5. The resulting mixture was heated to a temperature of 60
Water (dielectric constant 78.3) with vigorous stirring at 7.5 °C
Weight % added. After centrifuging for 5 minutes at a separation factor of 1000, the impurity content of the anti-sludge agent was 110 mg/100 g (solid impurity content 0.10% by weight). Example 8 The initial turbidity of an anti-sludge solution consisting of calcium petroleum sulfonate was 7840 mg/100 g (solid impurity content 3.9% by weight). While stirring this solution at a temperature of 60° C., 1.0% by weight of water (relative permittivity: 78.3) was added. Next, add this mixture to a strength of 1.5 kv/cm.
It was treated with an electrostatic field with a non-uniformity factor of 50. Coagulation and separation of impurities from the anti-sludge solution was carried out in the same apparatus. After carrying out this electrostatic field treatment for 15 minutes, the degree of turbidity of the obtained sludge inhibitor was 380 mg/100 g (solid impurity content 0.018% by weight). Example 9 An anti-sludge solution consisting of a barium salt of an alkylphenol disulfide was prepared with an initial level of turbidity.
It was 2100 mg/100 g (solid impurity content 1.2% by weight). While stirring this solution at a temperature of 60°C, 0.09% by weight of water (relative dielectric constant: 78.3) was added. This mixture was treated with an electrostatic field having a strength of 2.5 kv/cm and a nonuniformity factor of 25. Coagulation and separation of impurities from the anti-sludge solution were carried out simultaneously in the same apparatus. After performing this electrostatic field treatment for 15 minutes, the pollution degree of the obtained anti-sludge solution was 40 mg/100 g.
(solid impurity content 0.010% by weight). Example 10 An anti-sludge solution consisting of zinc dialkyldithiophosphate and barium alkylphenol had an initial turbidity of 770 mg/100 g (solid impurity content 0.8).
weight%). While stirring 100 g of this solution at a temperature of 60°C, 0.025% by weight of water (relative permittivity: 78.3) was added. This mixture was treated with an electrostatic field having a strength of 1.5 kv/cm and a nonuniformity factor of 5. Coagulation and separation of impurities from this solution were performed in the same apparatus. After performing this electrostatic field treatment for 15 minutes, the pollution degree of the obtained solution was 185 mg/100 g (solid impurity content
0.010% by weight). Example 11 An anti-sludge solution consisting of calcium petroleum sulfonate had an initial turbidity of 3290 mg/100 g (solid impurity content 4.7% by weight). While stirring this solution at a temperature of 60℃, add 0.5% by weight of water (relative permittivity
78.3) was added. This mixture has a strength of 1kv/cm,
It was treated with an electrostatic field with a non-uniformity factor of 10. Coagulation and separation of impurities from this solution were performed in the same apparatus. After carrying out this electrostatic field treatment for 30 minutes, the resulting anti-sludge agent had a turbidity of 211 mg/100 g (solid impurity content 0.01% by weight). Example 12 An anti-sludge solution of calcium petroleum sulfonate prepared by the method described in Example 1 had an initial turbidity of 3290 mg/100 g (solid impurity content 4.7% by weight). Pour this solution at a temperature of 60℃
Water (relative permittivity 78.3) 0.5% by weight while stirring with
added. This mixture was treated with an electrostatic field having a strength of 3 kv/cm and a non-uniformity factor of 10. Coagulation and separation of impurities from this solution were performed in the same apparatus. After carrying out this electrostatic field treatment for 30 minutes, the obtained sludge inhibitor had a turbidity of 69 mg/100 g (solid impurity content 0.01% by weight). Comparative Example 1a This is similar to Example 1 except that the amount of water used was increased to 780% by weight of additive. This amount of water is equal to the amount of water used in Example 1 described in JP-A-37-1274 as an example of the prior art. Comparative Example 1b This is the same as Example 1 except that the amount of water used was increased to 1150% by weight. This amount of water is equal to the amount of water in Example 2 described in the above publication. Comparing Comparative Examples 1a and 1b with Example 1, the first
As shown in the table, a significant amount of solid impurities remain.

[Table] Comparative Example 2 The initial solution of anti-sludge lubricant additive was
It was a petroleum sulfonic acid calcium salt with an impurity content of 6290 g/100 g and a solid impurity content of 4.7% by weight. While stirring this solution at a temperature of 60°C, 0.01% by weight of water was added. An electrostatic field with a strength of 2 kv/cm and a nonuniformity factor of 10 was applied to this mixture. Solid impurities flocculated and precipitated and were separated from the solution in the same apparatus. The lubricating oil additive after being treated in an electrostatic field for 30 minutes has an impurity content of 850mg/100g, solid impurity content
It was 0.04% by weight. Comparative Example 3 The initial solution of anti-sludge lubricant additive was
It was a sulfonic acid calcium salt with an impurity content of 6400 mg/100 g and a solid impurity content of 4.8% by weight. While stirring this solution at a temperature of 60°C, 15% by weight of water was added. The lubricating oil additive separated for 5 minutes in a centrifuge with a separation factor of 1000 had an impurity content of 940 mg/100 g and a solid impurity content of 0.05% by weight. Comparative Example 4 The initial solution of anti-sludge lubricant additive was
It was a sulfonic acid calcium salt with an impurity content of 7100 mg/100 g and a solid impurity content of 5.1% by weight. While stirring this solution at a temperature of 60°C, 5% by weight of tertiary butyl alcohol having a dielectric constant of 12.3 was added. After being centrifuged for 5 minutes at a separation factor of 1000, the lubricating oil additive had an impurity content of 1250 mg/100 g and a solid impurity content of 0.12% by weight. As is clear from the above Comparative Examples 1 to 3, the amount of polar solution added as defined in claim 1 is 0.025
-10% by weight or when the dielectric constant exceeds 17, it is impossible to obtain a purity of less than 500 mg/100 g of impurity content, which is the international standard for lubricating oil additives for preventing sludge.

Claims (1)

[Scope of Claims] 1. In the process of purifying a non-aqueous solution of a sludge-preventing lubricating oil additive containing solid impurity particles derived from the synthesis reaction of the sludge-preventing lubricating oil additive, this non-aqueous solution has a dielectric constant. A method for removing solid impurities from anti-sludge lubricating oil additives, comprising adding 0.025 to 10% by weight of a polar liquid of 17 or higher based on the weight of the lubricating oil additive, and then separating solid impurity particles by phase separation. . 2. A method for removing solid impurities in a lubricating oil additive for preventing sludge according to claim 1, wherein the polar liquid adsorbed on a solid carrier is added to a non-aqueous solution of the lubricating oil additive for preventing sludge. 3. A non-uniform electrostatic field generated by a pulsed voltage of constant polarity is applied to the non-aqueous solution of the anti-sludge lubricating oil additive to which the polar liquid has been added for phase separation. Method for removing solid impurities in anti-sludge lubricating oil additives as described. 4. A method for removing solid impurities in anti-sludge lubricating oil additives according to claim 3, using an electrostatic field with a strength of 0.1-5 kv/cm and a non-uniformity factor of 5-50. 5. A method for removing solid impurities from a lubricating oil additive for preventing sludge according to claim 2, wherein calcium hydroxide or calcium carbonate is used as the solid carrier. 6. The method for removing solid impurities from a lubricating oil additive for preventing sludge according to claim 2, wherein the amount of the solid carrier added is 0.01 to 1.0% by weight of the lubricating oil additive for preventing sludge. 7. Removal of solid impurities in the lubricating oil additive for preventing sludge according to claim 2, wherein the particle size of the carrier particles is 5 to 10 times the fraction particle size of 0.5 to 5μ, which accounts for the majority of the impurity particles. Method.