Lubricating oil additive and preparation method thereof

Abstract

The invention provides a lubricating oil additive and a preparation method thereof, the lubricating oil additive takes a first compound and a second compound as monomers, and a covalent organic framework material is obtained through polymerization reaction under the action of a surfactant; wherein the first compound has a structure as shown in a formula I; the second compound has a structure as shown in a formula II; the surfactant is a quaternary ammonium salt type gemini surfactant containing a biphenyl group. The lubricating oil additive provided by the invention has good dispersion stability in base oil and good wear resistance, and can improve the wear resistance of lubricating oil under high load.

Description

Technical Field

[0001] The invention relates to the field of covalent organic framework materials, in particular to a lubricating oil additive and a preparation method thereof. Background Art

[0002] Lubricating oil is a liquid or semi-solid lubricant used in various types of automobiles and mechanical equipment. It mainly plays the role of lubrication, cooling, rust prevention, cleaning, sealing and buffering. In some heavy-load mechanical equipment, lubricating oil is required to withstand higher loads. However, it is difficult for lubricating oil to form a sufficiently thick fluid dynamic lubrication film under high loads, resulting in poor lubricity and anti-wear performance. Adding additives such as graphene and carbon nanotubes to the base oil of lubricating oil can improve the lubricity and anti-wear performance of lubricating oil to a certain extent. However, the dispersion stability of these additives in the base oil is poor, and the addition will affect the long-term stability of the lubricating oil. Additives are prone to stratification, precipitation, agglomeration and other problems in the base oil. Once the above problems occur, the additive particles may cause abrasive wear on the friction surface, which will aggravate the wear. Summary of the invention

[0003] The object of the present invention is to provide a lubricating oil additive to solve the problems of poor anti-wear performance and poor dispersion stability in base oil of the lubricating oil additive in the prior art.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A lubricating oil additive, a covalent organic framework material obtained by polymerization reaction of a first compound and a second compound as monomers under the action of a surfactant;

[0006] Wherein, the first compound has a structure as shown in formula (I); the second compound has a structure as shown in formula (II); the surfactant is a quaternary ammonium salt type gemini surfactant containing a biphenyl group;

[0007]

[0008] Preferably, the surfactant has a structure as shown in formula (III):

[0009]

[0010] Preferably, the molar ratio of the first compound to the second compound is 1:(0.8-1.2).

[0011] Preferably, the molar ratio of the surfactant to the first compound is (0.3-0.6):1.

[0012] The present invention also provides a method for preparing the lubricating oil additive, comprising the following steps: dissolving the second compound in an organic solvent, adding a surfactant and an aqueous solution of acetic acid thereto, then adding the first compound thereto, mixing evenly, and degassing, and obtaining the lubricating oil additive through reaction.

[0013] Preferably, the organic solvent is dioxane.

[0014] Preferably, the concentration of the second compound in the organic solvent is 0.01-0.05 mol / L.

[0015] Preferably, in the aqueous solution of acetic acid, the concentration of acetic acid is 2-5 mol / L.

[0016] Preferably, the degassing is at least three cycles of liquid nitrogen cooling-vacuuming-methanol thawing.

[0017] Preferably, the reaction is carried out under vacuum conditions, with the temperature being raised to 100-150° C. at a rate of 3-10° C. / min, and the reaction is carried out for 12-48 hours.

[0018] Preferably, the method for preparing the lubricating oil additive further comprises the steps of filtering the product after the reaction, and washing and drying the precipitate obtained by filtration with dichloromethane.

[0019] The lubricating oil additive of the present invention can be applied to any base oil of lubricating oils such as PAO, 500SN, PEG and MACs. The mass percentage of the lubricating oil additive in the base oil is 0.01-1wt%.

[0020] The above solution of the present invention includes at least the following beneficial effects:

[0021] (1) The lubricating oil additive of the present invention is a covalent organic framework material obtained by polymerization reaction of a first compound and a second compound as monomers under the action of a surfactant; wherein the first compound has a structure as shown in formula (I); the second compound has a structure as shown in formula (II); and the surfactant is a quaternary ammonium salt-type gemini surfactant containing a biphenyl group. The lubricating oil additive of the present invention has good dispersion stability in the base oil and good anti-wear performance, and can improve the anti-wear performance of the lubricating oil under high load.

[0022] Specifically, the first compound and the second compound have a relatively stable planar structure and can be used as monomers of a two-dimensional covalent organic framework material. After the aldehyde group in the first compound reacts with the amino group in the second compound, the two monomers are connected by a covalent bond, and their physical and chemical properties are relatively stable, and the interlayer force is weak, and relative sliding is easy to occur, which can reduce the friction coefficient. In particular, in the tri-thiophene group in the first compound, the sulfur atom has good adsorption performance for the metal surface, can be adsorbed on the surface of the metal friction pair, and the structural rigidity of the tri-thiophene group is strong, which helps to improve the strength of the lubricating film and improve its anti-wear performance under high load. The o-phenanthroline group of the second compound helps to adapt to the surface of the metal friction pair and form a uniform lubricating film to improve the lubrication performance. The surfactant forms micelles in the reaction system, which can be used as a template for crystal growth, guiding the crystal to grow in a specific direction to form a regular crystal structure. At the same time, the biphenyl group contained in the surfactant, due to its large planar structure and hydrophobicity, is easily combined with the conjugated structure in the monomer through π-π stacking and other effects, and is embedded in the lattice of the reaction product during the reaction to form an ordered composite structure to improve the dispersibility of the reaction product.

[0023] (2) The lubricating oil additive of the present invention, the surfactant has a structure as shown in formula (III). The surfactant contains not only a biphenyl group, but also two long-chain alkanes; the biphenyl group is embedded in the lattice of the two-dimensional covalent organic framework material, and the long-chain alkane is in a flexible stretched state around the lattice, which can form a certain steric hindrance effect. In particular, the twin structural characteristics make it excellent in preventing the agglomeration and precipitation of the lubricating oil additive. At the same time, the long-chain alkane has better compatibility with the base oil, which can further improve the dispersion stability of the lubricating oil additive in the base oil. DETAILED DESCRIPTION

[0024] In the embodiments of the present invention, if the specific conditions are not specified, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. Raw materials of different manufacturers and models do not affect the implementation of the technical solution of the present invention and the realization of the technical effects.

[0025] In the following examples, the first compound is trithiophene-2,6-dicarbaldehyde, CAS No. 67061-73-8, and has a structure as shown in formula (I);

[0026]

[0027] The second compound is 5,6-diamino-1,10-phenanthroline, CAS No. 168646-54-6, and has a structure as shown in formula (II);

[0028]

[0029] The quaternary ammonium salt type gemini surfactant containing a biphenyl group has a structure as shown in formula (III); the quaternary ammonium salt type gemini surfactant containing a biphenyl group can be prepared using existing technology, for example, it can be prepared using the method disclosed in Chinese patent document CN104001449B.

[0030]

[0031] Example 1

[0032] The lubricating oil additive of this embodiment is a covalent organic framework material obtained by polymerization reaction of the first compound and the second compound as monomers under the action of a surfactant;

[0033] The molar ratio of the first compound to the second compound is 1:0.8. The molar ratio of the surfactant to the first compound is 0.3:1. The surfactant is the quaternary ammonium salt type gemini surfactant containing a biphenyl group.

[0034] The preparation method of the lubricating oil additive described in this embodiment comprises the following steps: dissolving the second compound in an organic solvent, adding a surfactant and an aqueous solution of acetic acid thereto, then adding the first compound thereto, mixing evenly, and performing three cycles of liquid nitrogen cooling-vacuuming-methanol thawing for degassing, heating to 100° C. at a rate of 3° C. / min under vacuum conditions, reacting for 36 hours, filtering the product after the reaction, and washing and drying the filtered precipitate with dichloromethane to obtain the lubricating oil additive.

[0035] The organic solvent is dioxane, the concentration of the second compound in the organic solvent is 0.01 mol / L, and the concentration of the acetic acid in the aqueous solution is 5 mol / L.

[0036] Example 2

[0037] The lubricating oil additive of this embodiment is a covalent organic framework material obtained by polymerization reaction of the first compound and the second compound as monomers under the action of a surfactant;

[0038] The molar ratio of the first compound to the second compound is 1:1.2. The molar ratio of the surfactant to the first compound is 0.6:1. The surfactant is the quaternary ammonium salt type gemini surfactant containing a biphenyl group.

[0039] The preparation method of the lubricating oil additive described in this embodiment comprises the following steps: dissolving the second compound in an organic solvent, adding a surfactant and an aqueous solution of acetic acid thereto, then adding the first compound thereto, mixing evenly, and performing three cycles of liquid nitrogen cooling-vacuuming-methanol thawing for degassing, heating to 120° C. at a rate of 10° C. / min under vacuum conditions, reacting for 48 hours, filtering the product after the reaction, and washing and drying the filtered precipitate with dichloromethane to obtain the lubricating oil additive.

[0040] The organic solvent is dioxane, the concentration of the second compound in the organic solvent is 0.03 mol / L, and the concentration of the acetic acid in the aqueous solution is 2 mol / L.

[0041] Example 3

[0042] The lubricating oil additive of this embodiment is a covalent organic framework material obtained by polymerization reaction of the first compound and the second compound as monomers under the action of a surfactant;

[0043] The molar ratio of the first compound to the second compound is 1: 1. The molar ratio of the surfactant to the first compound is 0.4: 1. The surfactant is the quaternary ammonium salt-type gemini surfactant containing a biphenyl group.

[0044] The preparation method of the lubricating oil additive described in this embodiment comprises the following steps: dissolving the second compound in an organic solvent, adding a surfactant and an aqueous solution of acetic acid thereto, then adding the first compound thereto, mixing evenly, and performing three cycles of liquid nitrogen cooling-vacuuming-methanol thawing for degassing, heating to 150° C. at a rate of 6° C. / min under vacuum conditions, reacting for 12 hours, filtering the product after the reaction, and washing and drying the filtered precipitate with dichloromethane to obtain the lubricating oil additive.

[0045] The organic solvent is dioxane, the concentration of the second compound in the organic solvent is 0.05 mol / L, and the concentration of the acetic acid in the aqueous solution is 3 mol / L.

[0046] Example 4

[0047] The lubricating oil additive of this embodiment is a covalent organic framework material obtained by polymerization reaction of the first compound and the second compound as monomers under the action of a surfactant;

[0048] The molar ratio of the first compound to the second compound is 1: 1. The molar ratio of the surfactant to the first compound is 0.5: 1. The surfactant is the quaternary ammonium salt-type gemini surfactant containing a biphenyl group.

[0049] The preparation method of the lubricating oil additive described in this embodiment comprises the following steps: dissolving the second compound in an organic solvent, adding a surfactant and an aqueous solution of acetic acid thereto, then adding the first compound thereto, mixing evenly, and performing three cycles of liquid nitrogen cooling-vacuuming-methanol thawing for degassing, heating to 150° C. at a rate of 8° C. / min under vacuum conditions, reacting for 48 hours, filtering the product after the reaction, and washing and drying the filtered precipitate with dichloromethane to obtain the lubricating oil additive.

[0050] The organic solvent is dioxane, the concentration of the second compound in the organic solvent is 0.03 mol / L, and the concentration of the acetic acid in the aqueous solution is 5 mol / L.

[0051] Comparative Example 1

[0052] The lubricating oil additive of this comparative example has the same raw materials and the same preparation method as that of Example 4, and the only difference is that the first compound is replaced by thiophene-3,4-dicarboxaldehyde.

[0053] The thiophene-3,4-dicarbaldehyde, CAS No. 1073-31-0, has a structure as shown in Formula IV:

[0054]

[0055] Comparative Example 2

[0056] The lubricating oil additive of this comparative example has the same raw materials and the same preparation method as that of Example 4, and the only difference is that the second compound is replaced by o-phenylenediamine.

[0057] The o-phenylenediamine, CAS No. 95-54-5, has a structure as shown in Formula V:

[0058]

[0059] Comparative Example 3

[0060] The lubricating oil additive of this comparative example has the same raw materials and the same preparation method as that of Example 4, and the only difference is that the surfactant is replaced by dodecyltrimethylammonium bromide; the CAS number of the dodecyltrimethylammonium bromide is 1119-94-4.

[0061] Comparative Example 4

[0062] The raw materials and preparation method of the lubricating oil additive in this comparative example are the same as those in Example 4, and the only difference is that the surfactant is replaced by dodecyl dimethyl benzyl ammonium bromide, i.e., benzalkonium chloride.

[0063] Comparative Example 5

[0064] The lubricating oil additive of this comparative example has the same raw materials and the same preparation method as that of Example 4, and the only difference is that the surfactant is not added.

[0065] Comparative Example 6

[0066] The lubricating oil additive of this comparative example has the same raw materials and the same preparation method as that of Example 4, and the only difference is that the molar ratio of the surfactant to the first compound is 0.1:1.

[0067] Comparative Example 7

[0068] The lubricating oil additive of this comparative example has the same raw materials and the same preparation method as that of Example 4, and the only difference is that the molar ratio of the surfactant to the first compound is 0.8:1.

[0069] Comparative Example 8

[0070] The raw materials and preparation methods of the lubricating oil additive in this comparative example are the same as those in Example 4, and the only difference is that sodium dodecylbenzene sulfonate is added to the quaternary ammonium salt-type gemini surfactant containing biphenyl groups. The CAS number of the sodium dodecylbenzene sulfonate is 25155-30-0.

[0071] The molar ratio of the sodium dodecylbenzene sulfonate to the quaternary ammonium salt-type gemini surfactant containing a biphenyl group is 0.2:1.

[0072] Effect experiment example

[0073] In order to verify the technical effect of the preparation method of the lubricating oil additive of the present invention, the following experiments were conducted:

[0074] The lubricating oil additives were prepared by the methods in Examples 1-4 and Comparative Examples 1-8, and the lubricating oils were prepared respectively according to the following methods:

[0075] Poly-alpha-olefin (PAO) is used as base oil, the lubricant additive is added to the base oil, and ultrasonic dispersion is performed to obtain lubricant, wherein the mass percentage of the lubricant additive in the base oil is 0.5wt%.

[0076] The obtained lubricating oil was subjected to the following experiments:

[0077] (1) A four-ball friction and wear tester was used to test the friction coefficient and wear spot diameter to characterize the anti-wear and friction reduction capabilities of the lubricant. The test conditions were as follows: load 400N, speed 1200r / min, temperature 50℃, and time 60min.

[0078] (2) Using a four-ball friction and wear tester, test the maximum no-seizure load under the conditions specified in ASTM D2783 and GB / T 12583 (speed 1760 r / min, room temperature, time 10 s) to characterize the pressure-bearing capacity of the lubricant;

[0079] (3) The absorbance of the lubricating oil before standing, after standing for 7 days, and after standing for 30 days was tested by a UV-visible spectrophotometer, and the relative concentration after standing for 7 days (absorbance after standing for 7 days / absorbance before standing) and the relative concentration after standing for 30 days (absorbance after standing for 7 days / absorbance before standing) were calculated respectively to characterize the dispersion stability of the lubricating oil additive in the base oil.

[0080] After experimentation, the results are as follows:

[0081]

[0082]

[0083] According to the results of Examples 1-4 and Comparative Examples 1-8, the lubricating oil additive of the present invention has good dispersion stability in the base oil and good anti-wear performance, and can improve the pressure bearing capacity of the lubricating oil.

[0084] According to the results of Example 4 and Comparative Examples 1-2, the trithiophene structure and o-phenanthroline of the first compound and the second compound have a significant effect on the anti-wear performance and pressure bearing capacity of the lubricating oil additive, and also have an effect on the structural characteristics of the formed covalent organic framework material, thereby affecting the interaction between it and the surfactant, resulting in a certain degree of change in its dispersion stability in the base oil.

[0085] According to the results of Example 4 and Comparative Examples 3-5, the comprehensive performance of the lubricating oil additive shows the rule that no surfactant is added < quaternary ammonium surfactant of long-chain alkane < quaternary ammonium surfactant of long-chain alkane containing benzene ring < quaternary ammonium Gemini surfactant containing biphenyl group. It can be seen that the quaternary ammonium surfactant of long-chain alkane and the quaternary ammonium surfactant of long-chain alkane containing benzene ring can only slightly improve the comprehensive performance of the lubricating oil additive, and the quaternary ammonium Gemini surfactant of biphenyl group is more conducive to embedding in the lattice of the two-dimensional covalent organic framework material, thereby playing a role in improving the dispersion stability. The two-dimensional covalent organic framework material formed by the quaternary ammonium Gemini surfactant containing biphenyl group as a template can also achieve better wear resistance, which may be due to the biphenyl group as a rigid group connecting two long-chain alkanes, and its structure is more stable. The micelles formed in the reaction solution have a more stable and regular effect on the first compound and the second compound, and can better guide the reaction to proceed in a specific manner to form a regular covalent organic framework material.

[0086] According to the results of Example 4 and Comparative Examples 6-8, the dosage of the quaternary ammonium salt type Gemini surfactant containing biphenyl groups is too low and cannot fully play its role; the dosage of the quaternary ammonium salt type Gemini surfactant containing biphenyl groups is too high and cannot achieve good comprehensive performance. However, adding a small amount of the sodium dodecylbenzene sulfonate and compounding the quaternary ammonium salt type Gemini surfactant containing biphenyl groups can further improve its dispersion stability and have little effect on the anti-wear performance of the lubricating oil additive.

[0087] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A lubricating oil additive, characterized in that: A covalent organic framework material obtained by polymerization reaction of the first compound and the second compound as monomers under the action of a surfactant; Wherein, the first compound has a structure as shown in formula (I); the second compound has a structure as shown in formula (II); the surfactant is a quaternary ammonium salt type gemini surfactant containing a biphenyl group; 2. The lubricating oil additive according to claim 1, characterized in that: The molar ratio of the first compound to the second compound is 1:(0.8-1.2).

3. The lubricating oil additive according to claim 2, characterized in that: The molar ratio of the surfactant to the first compound is (0.3-0.6):

1.

4. A method for preparing the lubricating oil additive according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: dissolving the second compound in an organic solvent, adding a surfactant and an aqueous solution of acetic acid thereto, then adding the first compound thereto, mixing evenly, and degassing, and obtaining a lubricating oil additive through reaction.

5. The method for preparing the lubricating oil additive according to claim 4, characterized in that: The organic solvent is dioxane.

6. The method for preparing the lubricating oil additive according to claim 5, characterized in that: The concentration of the second compound in the organic solvent is 0.01-0.05 mol / L.

7. The method for preparing a lubricating oil additive according to claim 4, characterized in that: In the aqueous solution of acetic acid, the concentration of acetic acid is 2-5 mol / L.

8. The method for preparing a lubricating oil additive according to claim 4, characterized in that: The degassing is performed by at least three cycles of liquid nitrogen cooling-vacuuming-methanol thawing.

9. The method for preparing a lubricating oil additive according to claim 4, characterized in that: The reaction is carried out under vacuum conditions, with the temperature being raised to 100-150° C. at a rate of 3-10° C. / min, and the reaction is carried out for 12-48 hours.

10. The method for preparing a lubricating oil additive according to claim 4, characterized in that: The method also includes the steps of filtering the product after the reaction, and washing and drying the precipitate obtained by filtering with dichloromethane.

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