Preparation method and application of high water-resistant zinc dialkyldithiophosphate additive

Abstract

This invention discloses a method for preparing a high water-resistant zinc dialkyl dithiophosphate additive. Specifically, the method involves: first, weighing an alkyl alcohol; then, under stirring conditions, adding phosphorus pentasulfide in batches to the alkyl alcohol; after the addition is complete, heating the reaction, followed by vacuum distillation, cooling, and filtration to obtain dialkyl dithiophosphate; second, stirring an aromatic solvent with zinc oxide to form a homogeneous phase; adding a fatty acid salt promoter and the intermediate dialkyl dithiophosphate; stirring; then adding zinc oxide in batches; after the addition is complete, heating and vacuum reactions are performed, followed by cooling; adding sulfides; and then heating, vacuum distillation, and filtration to obtain the high water-resistant zinc dialkyl dithiophosphate additive. This high water-resistant zinc dialkyl dithiophosphate additive can be used to formulate high-performance oil film bearing oils, giving the oil excellent water separation properties, anti-wear properties, and excellent filterability, hydrolytic stability, and outstanding load-bearing capacity.

Description

Technical Field

[0001] This invention belongs to the field of chemical material preparation technology, specifically relating to a method for preparing a high water-resistant dialkyl dithiophosphate zinc additive, and also relating to the application of this additive. Background Technology

[0002] Zinc dialkyl dithiophosphate (ZDDP) is widely used due to its excellent antioxidant, anti-wear, and anti-corrosion properties. Since its introduction in the 1940s, it has been an indispensable additive component in oils such as internal combustion engine oils, and has also been widely used in industrial oils such as gear oils and hydraulic oils.

[0003] ZDDP is typically added at a dosage of 0.5-1.0% in engine oils and 0.2-0.8% in industrial lubricants. Engine oils use ZDDP products primarily composed of neutral salts; industrial oils used in conditions containing water, such as hydraulic oils and oil film bearing oils, use ZDDP products primarily composed of basic salts. Over the past 30 years, most neutral ZDDP products have primarily used primary or secondary alkyl groups (3-8 C2 alkyl groups), while most basic ZDDP products have primarily used primary alkyl groups.

[0004] Oil film bearings are characterized by high load-carrying capacity, low coefficient of friction, and strong impact resistance. They are radial sliding bearings that use lubricating oil as the lubricating medium. The oil film system experiences significant temperature variations, making the oil prone to oxidation and deterioration, and it must withstand impact loads. To address these characteristics, foreign companies have developed three generations of oil film bearing oils. During use, industrial water inevitably mixes into oil film bearing oils, requiring them to maintain good anti-wear properties even in the presence of water and possess excellent oil-water separation capabilities under static conditions. Due to the specific performance requirements of oil film bearing oils, domestic lubricant research institutions and manufacturers have struggled to overcome bottlenecks and achieve significant progress. ZDDP (Zinc Dioxide Dismutase) plays a crucial role in improving load-carrying capacity, wear resistance, and oxidation resistance in oil film bearing oils, and it is essential that ZDDP products exhibit excellent water separation performance.

[0005] Chinese Patent (Application No.: 201110231801.5, Publication No.: CN102250139A) discloses a method for preparing alkyl thiophosphate, which involves dispersing phosphorus pentasulfide in a high-boiling-point solvent, adding an alcohol under vacuum, reacting to obtain thiophosphate, and then reacting thiophosphate with zinc oxide to obtain the product. The solvent used does not need to be removed and can be directly retained in the application system of alkyl thiophosphate as a solvent; however, when hydrogen sulfide is extracted under vacuum conditions, the alkyl alcohol is easily separated from the reaction system along with the hydrogen sulfide, resulting in incomplete reaction of diphosphorus pentasulfide. Therefore, the prepared product cannot achieve high hydrolytic stability and cannot be used in oil film bearing oils. Chinese patent (application number: 201711327221.X, publication number: CN107955035B) discloses a method for preparing diisooctyl dithiophosphate additives for hydraulic oils. This method involves adding isooctanol dropwise to an excess of diphosphorus pentasulfide; filtering out the solid diphosphorus pentasulfide after the reaction; adding excess zinc oxide; adding the prepared thiophosphate; and filtering the reagents after the reaction to obtain diisooctyl dithiophosphate. The diisooctyl dithiophosphate prepared by this method improves the water separation performance of hydraulic oils, but its application in oil film bearing oils is not mentioned. Existing technologies mostly focus on the anti-wear and anti-oxidation properties of zinc dialkyl dithiophosphate products, but rarely pay attention to the basic salt structure and its use in oil film bearing oils under aqueous conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a high water-resistant dialkyl dithiophosphate zinc additive, which exhibits excellent water separation performance, load-bearing capacity, and anti-wear properties in oil film bearing oil.

[0007] Another object of the present invention is to provide the application of the above-mentioned zinc dialkyl dithiophosphate additive in oil film bearing oil.

[0008] The technical solution adopted in this invention is a method for preparing a highly water-resistant dialkyl dithiophosphate zinc additive, which is implemented according to the following steps:

[0009] Step 1: Weigh the alkyl alcohol and add phosphorus pentasulfide in batches under rapid stirring. After the phosphorus pentasulfide is added, heat the reaction, then distill under reduced pressure, cool, and filter to obtain the intermediate dialkyl dithiophosphate.

[0010] Step 2: A certain amount of high flash point aromatic solvent and a certain amount of zinc oxide are stirred to form a homogeneous phase. The reaction system is still carried out under the condition of having an alkaline absorption device. Under certain conditions, fatty acid promoter and intermediate dialkyl dithiophosphate are added, and then zinc oxide is added in batches. After the addition is completed, the temperature is raised to a certain temperature and the reaction is carried out for a certain time. Then the reaction is carried out under reduced pressure for a certain time. Then the temperature is lowered and a certain amount of sulfide is added. The temperature is raised again and the reaction is carried out for a certain time. After the reaction is completed, the high water-resistant dialkyl dithiophosphate zinc additive is obtained by filtration.

[0011] The invention is further characterized in that,

[0012] In step 1, phosphorus pentasulfide is added in 5 to 10 batches; the molar ratio of alkyl alcohol to phosphorus pentasulfide is 4.0 to 5.0: 1.0; when adding phosphorus pentasulfide, the temperature of the reaction system is controlled not to exceed 60°C, and a negative pressure of -0.005 MPa to -0.02 MPa is maintained, and a sodium hydroxide solution absorption bottle is connected to the reaction system.

[0013] In step 1, the reaction temperature is 95–110℃, the reaction time is 2–4 h, and the vacuum distillation time is 2 h.

[0014] In step 2, the temperature is below 80°C when the fatty acid salt accelerator is added. The fatty acid salt accelerator is one or more of the sodium, calcium, and magnesium salts of butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid, whether normal or isomer.

[0015] In step 2, the stirring time is 10-60 minutes; zinc oxide is added in 3-5 batches.

[0016] In step 2, after the zinc oxide is added, the reaction temperature is 95-105℃ and the reaction time is 2-4 hours. The reduced pressure reaction temperature is 100℃ and the reduced pressure reaction time is 1-2 hours.

[0017] In step 2, after the sulfide is added, the reaction temperature is 95-105℃, the reaction time is 1-2h, the vacuum distillation temperature is 100-130℃, and the vacuum distillation time is 2-3h.

[0018] In step 2, the high flash point aromatic solvent is an aromatic oil or an alkyl naphthalene solvent oil with a flash point greater than 130℃, and the mass ratio of the aromatic solvent to zinc oxide is 0.50 to 1.5:1.0.

[0019] In step 2, the sulfide is any one of sulfur, ammonium sulfide, sodium sulfide, molybdenum sulfide, and tungsten sulfide; the molar ratio of sulfide to zinc oxide is 0.01 to 0.2:1.0.

[0020] The beneficial effects of this invention are:

[0021] (1) The high water-resistant dialkyl dithiophosphate zinc additive of the present invention can be used to formulate high-performance oil film bearing oil, giving the oil excellent water separation performance, anti-wear performance, and excellent filterability, hydrolytic stability, and outstanding load-bearing capacity. This additive can also be used in lubricating materials such as engine oils, industrial lubricants, and greases.

[0022] (2) The high water-resistant dialkyl dithiophosphate zinc additive of the present invention has a simple preparation process, good process stability, environmentally friendly reaction system and mild reaction conditions. Detailed Implementation

[0023] The present invention will now be described in detail through specific embodiments.

[0024] The preparation method of the highly water-resistant dialkyl dithiophosphate zinc additive of the present invention is specifically implemented according to the following steps:

[0025] Step 1: Weigh the alkyl alcohol and add phosphorus pentasulfide in 5 to 10 equal portions under rapid stirring. Control the temperature of the reaction system to not exceed 60°C and maintain a negative pressure of -0.005 MPa to -0.02 MPa. Connect the reaction system to an absorption bottle containing a 15% sodium hydroxide solution. After the phosphorus pentasulfide is added, raise the temperature to 95 to 110°C and maintain the temperature for 2 to 4 hours. Then, distill under reduced pressure for 2 hours at this temperature, cool down, and filter to obtain the intermediate dialkyl dithiophosphoric acid.

[0026] Alkyl alcohols are one or more of the normal or isomers of alkyl alcohols with 4-12 carbon atoms;

[0027] The molar ratio of alkyl alcohol to phosphorus pentasulfide is 4.0–5.0:1.0;

[0028] Step 2: A high-flash-point aromatic solvent is stirred with zinc oxide to form a homogeneous phase. A fatty acid salt accelerator is added at temperatures below 80°C, followed by the intermediate dialkyl dithiophosphate. The mixture is stirred for 10–60 minutes. A 15% sodium hydroxide solution is connected to the reaction system for absorption. Zinc oxide is then added in 3–5 batches. After the addition is complete, the temperature is increased and the reaction is carried out under reduced pressure. The temperature is then lowered to below 80°C, a sulfide is added, and the temperature is increased again for the reaction.

[0029] Vacuum distillation and filtration yielded a highly water-resistant zinc dialkyl dithiophosphate additive.

[0030] After zinc oxide is added, the reaction temperature is 95-105℃ and the reaction time is 2-4 hours. The reduced pressure reaction temperature is 100℃ and the reduced pressure reaction time is 1-2 hours.

[0031] After the sulfide is added, the reaction temperature is 95-105℃, the reaction time is 1-2h, the vacuum distillation temperature is 100-130℃, and the vacuum distillation time is 2-3h.

[0032] The fatty acid salt promoter is one or more of the sodium, calcium, and magnesium salts of butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid, either normal or isomer.

[0033] High flash point aromatic solvents refer to aromatic oils or alkyl naphthalene solvents with a flash point greater than 130℃, and the mass ratio of aromatic solvent to zinc oxide is 0.50 to 1.5:1.0;

[0034] The sulfide is any one of sulfur, ammonium sulfide, sodium sulfide, molybdenum sulfide, and tungsten sulfide; the molar ratio of sulfide to zinc oxide is 0.01 to 0.2:1.0.

[0035] The preparation method of the zinc dialkyl dithiophosphate additive of the present invention exhibits excellent water separation performance, load-bearing capacity, and anti-wear properties in oil film bearing oils. Furthermore, the preparation process of the present invention is simple and stable, and the reaction system is safe, environmentally friendly, highly controllable, and operates under mild reaction conditions.

[0036] Example 1

[0037] The preparation method of the highly water-resistant dialkyl dithiophosphate zinc additive of the present invention is as follows:

[0038] 110.4 g of 2,2-dimethylbutanol was added to a four-necked flask. Under rapid stirring, 55.6 g of phosphorus pentasulfide was added in five equal portions. The temperature of the reaction system was controlled not to exceed 60 °C. The reaction flask was kept under a negative pressure of -0.005 MPa to -0.015 MPa. The negative pressure system was connected to an absorption bottle containing a 15% sodium hydroxide solution. After the phosphorus pentasulfide was added, the temperature was raised to 100 °C and the reaction was stirred for 2.5 h. Then, the mixture was distilled under reduced pressure for 2 h at this temperature to distill off 7.6 g of the light component, yielding the intermediate dialkyl dithiophosphate.

[0039] In a four-necked reaction flask, 28g of aromatic solvent S270 and 9g of zinc oxide were stirred to form a homogeneous phase. The reaction was carried out under conditions with an alkaline absorption device. At 65°C, 5.8g of sodium laurate was added as a promoter. After stirring for 40 minutes, the intermediate dialkyl dithiophosphate (approximately 146g) was added, followed by the addition of 40g of zinc oxide in three portions. After the addition was complete, the temperature was raised to 102°C and the reaction was carried out for 3.5 hours. Then, the reaction was carried out under reduced pressure at the same temperature for 1.5 hours. After cooling, 3.8g of molybdenum sulfide was added, and the temperature was raised to 105°C and the reaction was carried out for 2 hours. Finally, the reaction was distilled under reduced pressure at 120°C for 1.5 hours. After the reaction was completed, the mixture was filtered to obtain a highly water-resistant zinc dialkyl dithiophosphate additive with a yield of approximately 91.5%.

[0040] Example 2

[0041] The preparation method of the highly water-resistant dialkyl dithiophosphate zinc additive of the present invention is as follows:

[0042] 145.6 g of 2-ethylhexanol was added to a four-necked flask. Under rapid stirring, 55.6 g of phosphorus pentasulfide was added in five equal portions. The temperature of the reaction system was controlled not to exceed 60 °C. The reaction flask was kept under a negative pressure of -0.005 MPa to -0.015 MPa. The negative pressure system was connected to an absorption bottle containing a 15% sodium hydroxide solution. After the addition of phosphorus pentasulfide was completed, the temperature was raised to 105 °C and the reaction was stirred for 2.5 h. Then, the mixture was distilled under reduced pressure for 2 h at this temperature to distill off 9.3 g of the light component, yielding the intermediate dialkyl dithiophosphoric acid.

[0043] In a four-necked reaction flask, 30g of aromatic solvent S270 and 12g of zinc oxide were stirred to form a homogeneous phase. The reaction was carried out under conditions with an alkaline absorption device. At 60°C, 7.2g of sodium stearate was added as a promoter. After stirring for 50 minutes, the previously synthesized intermediate dialkyl dithiophosphate (approximately 176g) was added, followed by the addition of 38g of zinc oxide in four portions. After the addition was complete, the temperature was raised to 105°C and the reaction was carried out for 3 hours. Then, the reaction was carried out under reduced pressure at the same temperature for 2 hours. After cooling, 2.7g of ammonium sulfide was added, and the temperature was raised to 105°C and the reaction was carried out for 2 hours. Finally, the reaction was distilled under reduced pressure at 125°C for 1.5 hours. After the reaction was completed, the mixture was filtered to obtain a highly water-resistant zinc dialkyl dithiophosphate additive with a yield of approximately 90.2%.

[0044] Example 3

[0045] The preparation method of the highly water-resistant dialkyl dithiophosphate zinc additive of the present invention is as follows:

[0046] 55.0 g of hexanol and 72 g of octanol were added to a four-necked flask. Under rapid stirring, 55.6 g of phosphorus pentasulfide was added in five equal portions. The temperature of the reaction system was controlled not to exceed 60 °C. The reaction flask was kept under a negative pressure of -0.005 MPa to -0.02 MPa. The negative pressure system was connected to an absorption bottle containing a 15% sodium hydroxide solution. After the phosphorus pentasulfide was added, the temperature was raised to 102 °C and the reaction was stirred for 3 h. Then, the mixture was distilled under reduced pressure for 2 h at this temperature, and 7.4 g of the light component was distilled off to obtain the intermediate dialkyl dithiophosphoric acid.

[0047] In a four-necked reaction flask, 28g of aromatic solvent S270 and 10g of zinc oxide were stirred to form a homogeneous phase. The reaction was carried out under conditions with an alkaline absorption device. At 70°C, 4.2g of sodium lauryl phosphate was added as a promoter. After stirring for 40 minutes, the previously synthesized intermediate dialkyl dithiophosphate (approximately 161g) was added, followed by the addition of 40g of zinc oxide in four portions. After the addition was complete, the temperature was raised to 105°C and the reaction was carried out for 3 hours. Then, the reaction was carried out under reduced pressure at the same temperature for 2 hours. After cooling, 3.6g of molybdenum sulfide was added, and the temperature was raised to 105°C and the reaction was carried out for 2 hours. Finally, the reaction was distilled under reduced pressure at 120°C for 1.5 hours. After the reaction was completed, the mixture was filtered to obtain a highly water-resistant zinc dialkyl dithiophosphate additive with a yield of approximately 91.7%.

[0048] The high water-resistant zinc dialkyl dithiophosphate additives prepared in Examples 1-3 of this invention are compared with conventional ZDDP products, as shown in Table 1.

[0049] Table 1. Analysis data of different zinc dialkyldithiophosphate additives

[0050] project Example 1 Example 2 Example 3 T202 T204 Comparative Example 1 Appearance Yellow liquid pale yellow liquid pale yellow liquid Amber liquid pale yellow liquid Yellow liquid Color intensity (undiluted) 1.5 1.0 1.0 2.0 1.5 1.5 Alkalinity, mgKOH / g 18.4 20.1 20.3 Undetectable 5.02 Undetectable Acid value, mgKOH / g 89.2 83.6 84.5 131.6 121.0 129.8 Sulfur content, % 15.44 14.56 14.88 16.18 14.99 15.96 Phosphorus content, % 7.29 7.21 7.33 7.74 7.48 7.70 Zinc content, % 9.04 8.82 8.98 8.55 9.55 8.21

[0051] Note: T202 is zinc n-butyl-n-octyl dithiophosphate; T204 is basic diisooctyl dithiophosphate; Comparative Example 1 is zinc didecyl dithiophosphate (refer to patent 201110231801.5).

[0052] The performance of Example 1, T204 and Comparative Example 1 in oil film bearing oil was investigated, and the results are shown in Table 2.

[0053] Table 2 Performance of ZDDP in oil film bearing oil

[0054]

[0055] As shown in Table 2, the product of this invention has superior performance in terms of water separation, oxidation resistance, load-bearing capacity, and wear resistance compared to conventional T204 products. The product of this invention is comparable to or even better than foreign oil film bearing oils. Due to the special structure of the dialkyl dithiophosphate zinc product in this invention, the stability and emulsification ability are well balanced in the presence of water, resulting in excellent overall performance.

[0056] The above describes embodiments of the present invention. Considering the poor water separation performance, wear resistance, and oxidation stability of zinc dialkyl dithiophosphate additives used in existing oil film bearing oil products, and the hazards of hydrogen sulfide spillage leading to operator injury or even poisoning, as well as environmental impacts, the present invention provides a method for preparing highly water-resistant zinc dialkyl dithiophosphate. When used in synergy with other additives in oil film bearing oils, this method results in oil film bearing oils exhibiting excellent water separation performance, load-bearing capacity, and wear resistance. Furthermore, the preparation process of the present invention is simple and stable, and the reaction system is safe, environmentally friendly, highly controllable, and operates under mild reaction conditions. This type of additive can also be applied to lubricating materials such as engine oils, industrial lubricants, and greases.

Claims

1. A method for preparing a highly water-resistant dialkyl dithiophosphate zinc additive, characterized in that, The specific steps are as follows: Step 1: Weigh the alkyl alcohol and add phosphorus pentasulfide in batches under rapid stirring. After the phosphorus pentasulfide is added, heat the reaction, then distill under reduced pressure, cool, and filter to obtain the intermediate dialkyl dithiophosphate. Phosphorus pentasulfide is added in 5 to 10 batches; the molar ratio of alkyl alcohol to phosphorus pentasulfide is 4.0 to 5.0: 1.0; when adding phosphorus pentasulfide, the temperature of the reaction system is controlled not to exceed 60°C, and a negative pressure of -0.005 MPa to -0.02 MPa is maintained, and a sodium hydroxide solution absorption bottle is connected to the reaction system. Step 2: Stir the high flash point aromatic solvent with zinc oxide to form a homogeneous phase, add fatty acid salt promoter and intermediate dialkyl dithiophosphate, stir, and then add zinc oxide in batches. After the addition is complete, carry out the heating reaction and the depressurization reaction, then cool down, add sulfide, carry out the heating reaction again, depressurization distillation, filter, and obtain the high water-resistant dialkyl dithiophosphate zinc additive. When adding the fatty acid salt accelerator, the temperature is below 80℃. The fatty acid salt accelerator is one or more of the sodium, calcium, and magnesium salts of butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid, whether normal or isomer. The sulfide is any one of sulfur, ammonium sulfide, sodium sulfide, molybdenum sulfide, and tungsten sulfide. The high flash point aromatic solvent is an aromatic oil with a flash point greater than 130℃, and the mass ratio of aromatic solvent to zinc oxide is 0.50~1.5:1.

0.

2. The preparation method of the high water-resistant dialkyl dithiophosphate zinc additive as described in claim 1, characterized in that, In step 1, the reaction temperature is 95–110°C, the reaction time is 2–4 h, and the vacuum distillation time is 2 h.

3. The preparation method of the high water-resistant dialkyl dithiophosphate zinc additive as described in claim 1, characterized in that, In step 2, the stirring time is 10-60 minutes; zinc oxide is added in 3-5 batches.

4. The preparation method of the high water-resistant dialkyl dithiophosphate zinc additive as described in claim 1, characterized in that, In step 2, after the zinc oxide is added, the reaction temperature is 95-105℃ and the reaction time is 2-4h. The reduced pressure reaction temperature is 100℃ and the reduced pressure reaction time is 1-2h.

5. The preparation method of the high water-resistant dialkyl dithiophosphate zinc additive as described in claim 1, characterized in that, In step 2, after the sulfide is added, the reaction temperature is 95-105℃, the reaction time is 1-2h, the vacuum distillation temperature is 100-130℃, and the vacuum distillation time is 2-3h.

6. The preparation method of the high water-resistant dialkyl dithiophosphate zinc additive as described in claim 1, characterized in that, In step 2, the molar ratio of sulfide to zinc oxide is 0.01 to 0.2:1.

0.

7. The application of the high water-resistant dialkyl dithiophosphate zinc additive prepared by the preparation method according to any one of claims 1-6 in oil film bearing oil.

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