Polyurea type water-based lubricant additive, preparation method thereof and water-based lubricant

Abstract

The invention provides a polyurea type water-based lubricating additive, a preparation method thereof and a water-based lubricant, and relates to the technical field of lubricating materials. The molecular chain of the polyurea type water-based lubricating additive provided by the invention contains water-soluble carboxylate radicals, so that the polyurea type water-based lubricating additive has excellent hydration capability, and meanwhile, the additive can be adsorbed on the surface of a metal substrate through the carboxylate radicals with negative electricity, so that a good interface adsorption film is formed, and the friction coefficient of a lubricating agent is reduced; a large number of ureido groups in the polyurea type water-based lubricant additive can form a hydrogen bond network, and meanwhile, hydrophobic groups of quaternary ammonium salt cations can establish a hydrophobic region, so that the stability of a polymer network is improved, and finally, the bearing capacity of a water-based lubricant is improved; carboxylate anions and quaternary ammonium cations in the polyurea type water-based lubricating additive do not corrode a substrate in friction. Therefore, the polyurea type water-based lubricating additive has excellent antifriction and antiwear capacity and bearing capacity, is free of corrosion, and can effectively improve the lubricating property of the water-based lubricating agent.

Description

Technical Field

[0001] The invention relates to the technical field of lubricating materials, and in particular to a polyurea type water-based lubricating additive and a preparation method thereof and a water-based lubricant. Background Art

[0002] With the improvement of environmental awareness and the in-depth study of the concept of sustainable development, traditional oil-based lubricants are facing challenges due to their flammability, explosiveness and environmental pollution. Water-based lubricants have received widespread attention from various industries due to their green, low-toxicity, flame retardant and good cooling performance. However, the lubrication performance, load-bearing capacity and corrosion resistance of water-based lubricants are inferior to those of oil-based lubricants, which limits their application in the industrial field. Therefore, the development of efficient additives to improve the lubrication performance and corrosion resistance of water-based lubricants is of great significance to the lubrication field.

[0003] Currently, water-based lubricants are mainly composed of small molecule additives, but small molecule lubricating additives have low viscosity and weak interface adsorption stability, resulting in poor friction reduction and load-bearing performance. In addition, small molecule lubricating additives are highly corrosive, which limits their application in water-based lubrication. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a polyurea type water-based lubricating additive and a preparation method thereof and a water-based lubricant. The polyurea type water-based lubricating additive provided by the present invention has excellent anti-friction and anti-wear capabilities and load-bearing performance, is non-corrosive, and can effectively improve the lubricating performance of water-based lubricants.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a polyurea type water-based lubricating additive having a structure shown in Formula I:

[0007]

[0008] In formula I, n is an integer between 10 and 100;

[0009] R 1 for

[0010] R 2 + for

[0011] The present invention provides a method for preparing the polyurea water-based lubricating additive described in the above technical solution, comprising the following steps:

[0012] Lysine, ammonium hydroxide and water are mixed for acid-base neutralization reaction to obtain an ionic liquid; the ammonium hydroxide is benzyltrimethylammonium hydroxide, tetrabutylammonium hydroxide or hexadecyltrimethylammonium hydroxide;

[0013] The ionic liquid is mixed with a diisocyanate and an organic solvent to carry out a polymerization reaction to obtain a polymerization product; the diisocyanate is hexamethylene diisocyanate, isophorone diisocyanate or 4,4'-dicyclohexylmethane diisocyanate;

[0014] The polymerization product is terminated with di-n-butylamine to obtain the polyurea type water-based lubricating additive.

[0015] Preferably, the molar ratio of lysine to ammonium hydroxide is (1.0-1.1):1.

[0016] Preferably, the temperature of the acid-base neutralization reaction is 0-4°C and the time is 48-72h.

[0017] Preferably, the molar ratio of the ionic liquid to the diisocyanate is (0.9-1):1.

[0018] Preferably, the polymerization reaction is carried out at a temperature of 15 to 25° C. and for a time of 10 to 30 minutes.

[0019] Preferably, the molar ratio of di-n-butylamine to ionic liquid is (0.1-1):1.

[0020] Preferably, the end-capping temperature is 15-25° C. and the time is 10-90 min.

[0021] The present invention provides a water-based lubricant, comprising water and a water-based lubricating additive, wherein the water-based lubricating additive is the polyurea-type water-based lubricating additive described in the above technical solution or the polyurea-type water-based lubricating additive prepared by the preparation method described in the above technical solution.

[0022] Preferably, the mass fraction of the water-based lubricating additive in the water-based lubricant is 0.5-5%.

[0023] The present invention provides a polyurea type water-based lubricating additive having a structure shown in Formula I, containing urea groups and water-soluble carboxyl groups, wherein the carboxyl groups are paired with quaternary ammonium salt cations. The molecular chain of the polyurea type water-based lubricating additive provided by the present invention contains water-soluble carboxyl groups, so it has excellent hydration ability, and the negatively charged carboxyl groups are conducive to the adsorption of the lubricating additive on the surface of the metal substrate to form a good interface adsorption film, which is conducive to reducing the friction coefficient of the lubricant; a large number of urea groups in the polyurea type water-based lubricating additive can form a hydrogen bond network, and the hydrophobic groups of the quaternary ammonium salt cations can establish hydrophobic regions, thereby improving the stability of the polymer network and ultimately improving the carrying capacity of the water-based lubricant; and the carboxylate anions and quaternary ammonium cations in the polyurea type water-based lubricating additive will not corrode the substrate during friction, solving the problem that the water-based lubricating additive is prone to corrosion. Therefore, the polyurea type water-based lubricating additive provided by the present invention has excellent friction reduction and anti-wear ability, load-bearing capacity and is non-corrosive, and can effectively improve the lubrication performance of the water-based lubricant. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The NMR characterization results of the polyurea water-based lubricant additive (HDI-ILs) prepared in Example 1;

[0025] Figure 2 The NMR characterization results of the polyurea water-based lubricating additive (IPDI-ILs) prepared in Example 2;

[0026] Figure 3 The friction coefficient curves of pure water and water-based lubricants prepared with small molecule ionic liquids (ILs), polyurea-type water-based lubricant additives (HDI-ILs) of Example 1 and polyurea-type water-based lubricant additives (IPDI-ILs) of Example 2 under a fixed load of 100N are compared;

[0027] Figure 4 The friction load-bearing capacity of water-based lubricants added with different concentrations of polyurea-type water-based lubricating additives (IPDI-ILs) prepared in Example 2 under loads varying from 100 to 1000 N (the addition amount of IPDI-ILs in the water-based lubricant was 0.5 wt%, 1 wt%, 2 wt%, and 3 wt%, respectively);

[0028] Figure 5 Comparison of friction coefficient curves of water-based lubricants prepared with polyurea-type water-based lubricant additives of Example 3 and Example 4;

[0029] Figure 6 The morphology of the wear spots on the friction pair surface under an electron microscope after the friction test of the water-based lubricant prepared with pure water and the polyurea-type water-based lubricant additive (IPDI-ILs) prepared in Example 2, Figure 6In (a), it corresponds to pure water, and in (b), it corresponds to the water-based lubricant prepared with IPDI-ILs of Example 2. Detailed implementation mode

[0030] The present invention provides a polyurea-based water-based lubricating additive having the structure shown in Formula I:

[0031]

[0032] In Formula I, n is an integer between 10 and 100;

[0033] R 1 is

[0034] R 2 + is

[0035] In the present invention, preferably, n is 10 to 50, and more preferably 12 to 20.

[0036] The polyurea-based water-based lubricating additive provided by the present invention contains urea groups and ionic liquid units. The polyurea-based water-based lubricating additive provided by the present invention has good hydration ability and a large number of hydrogen bonds, can effectively reduce the friction coefficient of water as an additive, reduce the corrosion problem of water-based lubricants, and at the same time improve the load-carrying capacity of water-based lubricants, and can be used as a new water-based lubricating additive in the industrial field.

[0037] The present invention provides a preparation method of the polyurea-based water-based lubricating additive described in the above technical solution, including the following steps:

[0038] Mix lysine, ammonium hydroxide and water to carry out an acid-base neutralization reaction to obtain an ionic liquid; the ammonium hydroxide is benzyltrimethylammonium hydroxide, tetrabutylammonium hydroxide or cetyltrimethylammonium hydroxide;

[0039] Mix the ionic liquid with a diisocyanate and an organic solvent to carry out a polymerization reaction to obtain a polymerization product; the diisocyanate is hexamethylene diisocyanate, isophorone diisocyanate or 4,4'-dicyclohexylmethane diisocyanate;

[0040] Block the polymerization product with di-n-butylamine to obtain the polyurea-based water-based lubricating additive.

[0041] In the present invention, unless otherwise specified, the raw materials involved are all commercially available products in the art.

[0042] The present invention mixes lysine, ammonium hydroxide and water to carry out acid-base neutralization reaction to obtain an ionic liquid. The present invention has no special requirements for the lysine, and lysine well known to those skilled in the art can be used. In the present invention, the ammonium hydroxide is benzyltrimethylammonium hydroxide, tetrabutylammonium hydroxide or hexadecyltrimethylammonium hydroxide; the molar ratio of lysine to ammonium hydroxide is preferably (1.0-1.1):1; the mass of the lysine and ammonium hydroxide is preferably 10-50% of the total mass of lysine, ammonium hydroxide and water, and can be 10%, 20%, 30%, 40% or 50%.

[0043] In the present invention, the method of mixing lysine, ammonium hydroxide and water is preferably:

[0044] dissolving lysine in water to obtain a lysine solution;

[0045] Dissolving ammonium hydroxide (in this embodiment of the present invention, the ammonium hydroxide is added in the form of an aqueous solution) in water to obtain an ammonium hydroxide solution;

[0046] The lysine solution was added dropwise into the ammonium hydroxide solution.

[0047] In the present invention, the temperature of the acid-base neutralization reaction is preferably 0-4°C, and can be 0, 1, 2, 3 or 4°C. The time is preferably 48-72h, and can be 48, 60 or 72h. The time of the acid-base neutralization reaction is calculated from the completion of the dropwise addition of the lysine solution.

[0048] In the present invention, the reaction formula involved in the acid-base neutralization reaction is as follows:

[0049]

[0050] After the acid-base neutralization reaction is completed, the present invention preferably performs rotary evaporation and vacuum drying on the obtained reaction solution in sequence to obtain the ionic liquid. In the present invention, the vacuum drying time is preferably 3 days. The present invention removes most of the water in the obtained reaction solution by the rotary evaporation, and removes the residual water by the vacuum drying.

[0051] After the ionic liquid is obtained, the present invention mixes the ionic liquid with diisocyanate and an organic solvent to carry out polymerization reaction to obtain a polymerization product.

[0052] In the present invention, the diisocyanate is hexamethylene diisocyanate, isophorone diisocyanate or 4,4'-dicyclohexylmethane diisocyanate; the molar ratio of the ionic liquid to the diisocyanate is preferably (0.9 to 1):1. In the present invention, the organic solvent is preferably an alcohol solvent, and the alcohol solvent is preferably isopropyl alcohol; the mass of the ionic liquid and the diisocyanate is preferably 10 to 30% of the total mass of the ionic liquid, the diisocyanate and the organic solvent, and can be 10%, 15%, 20%, 25% or 30%.

[0053] In the present invention, the method for mixing the ionic liquid with the diisocyanate and the organic solvent is preferably as follows:

[0054] Dissolve the ionic liquid in the organic solvent to obtain an ionic liquid solution;

[0055] Dissolve the diisocyanate in the organic solvent to obtain a diisocyanate solution;

[0056] Place the ionic liquid solution at room temperature and carry out mechanical stirring; then drop the diisocyanate solution into the ionic liquid solution; the dropping time is preferably 5 to 10 min.

[0057] In the present invention, the temperature of the polymerization reaction is preferably 15 to 25 °C (in the examples of the present invention, the polymerization reaction is carried out at room temperature, that is, no additional heating or cooling is required), and the time is preferably 10 to 30 min, and can be 10, 15, 20, 25 or 30 min; the time of the polymerization reaction is calculated from the completion of the dropping of the diisocyanate solution. In the examples of the present invention, after the dropping of the diisocyanate solution is completed, it is preferred to add isopropyl alcohol to the reaction system to prevent the system viscosity from being too high and causing more local heat release and side reactions.

[0058] In the present invention, the polymerization reaction is a copolymerization of diisocyanate and ionic liquid-based diamine, and the involved reaction formula is as follows:

[0059]

[0060] After obtaining the polymerization product, the present invention caps the polymerization product with di-n-butylamine to obtain the polyurea-based water-based lubricating additive.

[0061] In the present invention, the molar ratio of the di-n-butylamine to the ionic liquid is preferably (0.1 to 1):1, more preferably 0.1:1; the di-n-butylamine is used as a capping agent.

[0062] In the present invention, after the completion of the above-mentioned polymerization reaction, no post-treatment is required, and the reaction solution obtained by the polymerization reaction is directly end-capped with di-n-butylamine. In the present invention, di-n-butylamine is preferably dissolved in an organic solvent to obtain a di-n-butylamine solution; and the di-n-butylamine is added to the reaction solution obtained by the polymerization reaction for end-capping. In the present invention, the organic solvent is preferably the same as the organic solvent described in the above technical solution, and the amount ratio of the di-n-butylamine to the organic solvent is preferably 0.39-0.65 g:10 mL.

[0063] In the present invention, the end-capping temperature is preferably 15 to 25° C. (the end-capping in the embodiment of the present invention is performed at room temperature, i.e., no additional heating or cooling is required), and the time is preferably 10 to 90 minutes. The present invention uses di-n-butylamine for end-capping to consume the isocyanate that has not yet reacted with the ionic liquid. As a secondary amine, di-n-butylamine has a lower reactivity with isocyanate than primary amine, so the end-capping reaction is easy to control.

[0064] After the end-capping is completed, the present invention preferably centrifuges the obtained reaction solution, dialyzes the supernatant and freeze-dries it in sequence to obtain the polyurea-type water-based lubricating additive. In the present invention, the centrifugal speed is preferably 5000-8000 rpm, and the time is preferably 10-15 min; the molecular weight cutoff of the dialysis bag used in the dialysis is preferably 3500 Da, and the dialysis time is preferably 1-3 days. The present invention removes small molecules in the supernatant through the dialysis; the freeze-drying time is preferably 3-7 days.

[0065] The present invention provides a water-based lubricant, comprising water and a water-based lubricating additive, wherein the water-based lubricating additive is the polyurea-type water-based lubricating additive described in the above technical solution or the polyurea-type water-based lubricating additive prepared by the preparation method described in the above technical solution. In the present invention, the mass fraction of the water-based lubricating additive in the water-based lubricant is preferably 0.5-5%, and can be 0.5%, 1%, 2%, 3%, 4% or 5%. The water-based lubricant provided by the present invention has excellent lubricating properties, load-bearing capacity and is non-corrosive, and can be widely used in the field of lubrication. The present invention has no special requirements for the application method of the water-based lubricant, and the application method familiar to those skilled in the art can be used.

[0066] In order to further illustrate the present invention, the polyurea water-based lubricant additive and its preparation method and water-based lubricant provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0067] Example 1

[0068] Take 58.50g (0.4mol) of lysine and dissolve it in 100mL of water to obtain a lysine solution; take 167g of a 40wt% benzyltrimethylammonium hydroxide aqueous solution (containing 0.4mol of benzyltrimethylammonium hydroxide) and dissolve it in 200mL of water, and add it dropwise to the lysine solution, and react in an ice-water bath for 48h; after rotary evaporation to remove a certain amount of water, vacuum dry for 3 days to obtain an ionic liquid (referred to as lysine-benzyltrimethylammonium, abbreviated as ILs);

[0069] 8.41 g (0.05 mol) of hexamethylene diisocyanate was dissolved in 20 mL of isopropanol to obtain a hexamethylene diisocyanate solution; 14.77 g (0.05 mol) of lysine-benzyltrimethylammonium was dissolved in 40 mL of isopropanol to obtain a lysine-benzyltrimethylammonium isopropanol solution; the lysine-benzyltrimethylammonium isopropanol solution was placed at room temperature for mechanical stirring; the hexamethylene diisocyanate solution was then slowly added dropwise to the lysine-benzyltrimethylammonium isopropanol solution. The dropping time is 10 minutes, and then 23 mL of isopropanol is added to continue the reaction for 10 minutes; 0.65 g (0.005 mol) of di-n-butylamine is dissolved in 10 mL of isopropanol to block the residual isocyanate for 10 minutes; after the reaction is completed, centrifuge at 5000 rpm for 15 minutes, dialyze the supernatant (the molecular weight cutoff of the dialysis bag is 3500 Da) for 3 days, and then freeze-dry for 3 days to obtain a polyurea-type water-based lubricating additive, which is recorded as HDI-ILs (with an average degree of polymerization of 13).

[0070] Example 2

[0071] 14.62 g (0.1 mol) of lysine was dissolved in 50 mL of water to obtain a lysine solution; 41.81 g of a 40 wt% benzyltrimethylammonium hydroxide aqueous solution (containing 0.1 mol of benzyltrimethylammonium hydroxide) was dissolved in 50 mL of water, and added dropwise to the lysine solution, and reacted in an ice-water bath for 48 h; a certain amount of water was removed by rotary evaporation, and then vacuum dried for 3 days to obtain an ionic liquid (referred to as lysine-benzyltrimethylammonium, abbreviated as ILs);

[0072] 2.22 g (0.01 mol) of isophorone diisocyanate was dissolved in 11.11 g of isopropanol to obtain an isophorone diisocyanate solution; 2.95 g (0.01 mol) of lysine-benzyltrimethylammonium was dissolved in 14.77 g of isopropanol to obtain a lysine-benzyltrimethylammonium isopropanol solution; the lysine-benzyltrimethylammonium isopropanol solution was placed at room temperature for mechanical stirring; the isophorone diisocyanate solution was then slowly added dropwise to the lysine-benzyltrimethylammonium isopropanol solution. The solution was added for 5 minutes, and then 10 g of isopropanol was added to continue the reaction for 15 minutes; 0.13 g (0.001 mol) of di-n-butylamine was dissolved in 10 mL of isopropanol to cap the residual isocyanate for 10 minutes; after the reaction was completed, the solution was centrifuged at 5000 rpm for 15 minutes, and the supernatant was dialyzed (the molecular weight cutoff of the dialysis bag was 3500 Da) for 3 days, and then freeze-dried for 3 days to obtain a polyurea-type water-based lubricating additive, which was recorded as IPDI-ILs (with an average degree of polymerization of 12).

[0073] Example 3

[0074] 14.62 g (0.1 mol) of lysine was dissolved in 50 mL of water to obtain a lysine solution; 52 g of a 50 wt% aqueous solution of tetrabutylammonium hydroxide (containing 0.1 mol of tetrabutylammonium hydroxide) was dissolved in 50 mL of water and added dropwise to the lysine solution, and reacted in an ice-water bath for 48 h; a certain amount of water was removed by rotary evaporation and vacuum dried for 3 days to obtain an ionic liquid (referred to as lysine-tetrabutylammonium);

[0075] Take 5.05 g (0.03 mol) of hexamethylene diisocyanate and dissolve it in 20 mL of isopropanol to obtain a hexamethylene diisocyanate isopropanol solution; take 11.63 g (0.03 mol) of lysine-tetrabutylammonium and dissolve it in 40 mL of isopropanol to obtain a lysine-tetrabutylammonium isopropanol solution; place the lysine-tetrabutylammonium isopropanol solution at room temperature and stir it mechanically; then slowly drop the hexamethylene diisocyanate isopropanol solution into the lysine-tetrabutylammonium isopropanol solution. The dropping time is 10 minutes, and then 13 mL of isopropanol is added to continue the reaction for 15 minutes; 0.39 g (0.003 mol) of di-n-butylamine is dissolved in 10 mL of isopropanol to block the residual isocyanate, and the reaction is continued for 10 minutes; after the reaction is completed, centrifuge at 5000 rpm for 15 minutes, dialyze the supernatant (the molecular weight cutoff of the dialysis bag is 3500 Da) for 3 days, and then freeze-dry for 3 days to obtain a polyurea-type water-based lubricating additive (with an average degree of polymerization of 18).

[0076] Example 4

[0077] 14.62 g (0.1 mol) of lysine was dissolved in 50 mL of water to obtain a lysine solution; 301.6 g of a 10% hexadecyltrimethylammonium hydroxide aqueous solution (containing 0.1 mol of hexadecyltrimethylammonium hydroxide) was added dropwise to the lysine solution, and the mixture was reacted in an ice-water bath for 48 h; a certain amount of water was removed by rotary evaporation, and then vacuum dried for 3 days to obtain an ionic liquid (referred to as lysine-hexadecyltrimethylammonium);

[0078] 5.05 g (0.03 mol) of hexamethylene diisocyanate was dissolved in 20 mL of isopropanol to obtain a hexamethylene diisocyanate isopropanol solution; 12.89 g (0.03 mol) of lysine-hexadecyltrimethylammonium was dissolved in 40 mL of isopropanol to obtain a lysine-hexadecyltrimethylammonium isopropanol solution; the lysine-hexadecyltrimethylammonium isopropanol solution was placed at room temperature and mechanically stirred; the hexamethylene diisocyanate isopropanol solution was then slowly added dropwise to the lysine-hexadecyltrimethylammonium solution. The methylammonium isopropanol solution was added for 10 minutes, and then 13 mL of isopropanol was added to continue the reaction for 15 minutes; 0.39 g (0.003 mol) of di-n-butylamine was dissolved in 10 mL of isopropanol to block the residual isocyanate, and the reaction was continued for 10 minutes; after the reaction was completed, the solution was centrifuged at 5000 rpm for 15 minutes, and the supernatant was dialyzed (the molecular weight cutoff of the dialysis bag was 3500 Da) for 3 days, and then freeze-dried for 3 days to obtain a polyurea-type water-based lubricating additive (with an average degree of polymerization of 15).

[0079] Characterization and performance testing

[0080] (1) The polyurea water-based lubricating additives prepared in Examples 1 and 2 were characterized by H NMR spectroscopy. The results are shown in Figure 1 and Figure 2 .

[0081] Figure 1 The NMR characterization results of the polyurea water-based lubricant additive (HDI-ILs) prepared in Example 1 are as follows: Figure 2 The NMR characterization results of the polyurea type water-based lubricating additive (IPDI-ILs) prepared in Example 2 indicate that the additive with the above structure was successfully synthesized.

[0082] (2) Tribological performance test

[0083] The small molecule ionic liquid ILs (lysine-benzyltrimethylammonium) prepared in Example 2, the polyurea type water-based lubricating additive (HDI-ILs) prepared in Example 1, and the polyurea type water-based lubricating additive (IPDI-ILs) prepared in Example 2 were added to water to obtain a 2% by mass aqueous solution, i.e., a water-based lubricant; and pure water was used as a control.

[0084] Test conditions:

[0085] The German SRV4 friction and wear tester was used to conduct a 30-minute friction coefficient evaluation test at a temperature of 25°C, with a fixed load of 100N and a variable load of 100 to 1000N (the load increased by 50N every 2 minutes during the variable load process), a frequency of 25Hz, and an amplitude of 1mm. The steel ball used in the experiment was a GCr15 bearing steel with a diameter of 10mm, and the block used for the lower sample was a GCr15 steel block with a diameter of 24mm and a height of 7.9±0.1mm (average hardness 729HV).

[0086] Test results:

[0087] Figure 3 The friction coefficient curves of pure water and water-based lubricants (mass fraction 2%) prepared with small molecule ionic liquids (ILs), polyurea-type water-based lubricant additives (HDI-ILs) of Example 1 and polyurea-type water-based lubricant additives (IPDI-ILs) of Example 2 under a fixed load of 100 N are compared. The friction coefficients of the water-based lubricants with the polyurea-type water-based lubricant additives prepared in Example 1 and Example 2 are 0.14 and 0.12, respectively, the friction coefficient of pure water is 0.35, and the friction coefficient of the water-based lubricant with the small molecule ionic liquids (ILs) is 0.21, indicating that the polyurea-type water-based lubricant additive can effectively reduce the friction coefficient of water, and the friction coefficient has good stability.

[0088] Figure 4 The friction load capacity of water-based lubricants added with different concentrations of polyurea-type water-based lubricant additives (IPDI-ILs) prepared in Example 2 under loads varying from 100 to 1000 N (the addition amount of IPDI-ILs in the water-based lubricant is 0.5wt%, 1wt%, 2wt%, and 3wt%, respectively). Figure 4 It can be seen that with the increase of concentration, the load-bearing capacity of the water-based lubricant is greatly improved, and failure occurs at a maximum of 1000N.

[0089] Figure 5 The friction coefficient curves of the water-based lubricant (added at 3 wt%) prepared with the polyurea-type water-based lubricant additives of Example 3 and Example 4 are compared. Figure 5 It can be seen that the friction coefficients of the water-based lubricants corresponding to the polyurea water-based lubricating additives prepared in Example 3 and Example 4 are 0.12 and 0.1 respectively, both of which can make the water-based lubricants have a lower and more stable friction coefficient.

[0090] (3) Corrosion resistance evaluation

[0091] After the tribological performance test in (2) was performed using an SRV4 friction and wear tester, the wear spot area was rinsed with water and anhydrous ethanol in turn, and after drying, the wear spot was observed under a scanning electron microscope.

[0092] Figure 6 The morphology of the wear spots on the friction pair surface under an electron microscope after the friction test of the water-based lubricant prepared with pure water and the polyurea-type water-based lubricant additive (IPDI-ILs) prepared in Example 2, Figure 6 (a) corresponds to pure water, and (b) corresponds to the water-based lubricant prepared with IPDI-ILs of Example 2. Figure 6 It can be seen that after using the polyurea type water-based lubricating additive of Example 2, the wear area is significantly reduced and there is no obvious pitting corrosion.

[0093] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A polyurea type water-based lubricating additive, characterized in that: It has the structure shown in formula I: In formula I, n is an integer between 10 and 100; R1 is R2 + for 2. The method for preparing the polyurea type water-based lubricating additive according to claim 1, characterized in that: The following steps are involved: Lysine, ammonium hydroxide and water are mixed for acid-base neutralization reaction to obtain an ionic liquid; the ammonium hydroxide is benzyltrimethylammonium hydroxide, tetrabutylammonium hydroxide or hexadecyltrimethylammonium hydroxide; The ionic liquid is mixed with a diisocyanate and an organic solvent to carry out a polymerization reaction to obtain a polymerization product; the diisocyanate is hexamethylene diisocyanate, isophorone diisocyanate or 4,4'-dicyclohexylmethane diisocyanate; The polymerization product is terminated with di-n-butylamine to obtain the polyurea type water-based lubricating additive.

3. The preparation method according to claim 2, characterized in that: The molar ratio of lysine to ammonium hydroxide is (1.0-1.1):

1.

4. The preparation method according to claim 2 or 3, characterized in that: The temperature of the acid-base neutralization reaction is 0-4°C and the time is 48-72h.

5. The preparation method according to claim 2, characterized in that: The molar ratio of the ionic liquid to the diisocyanate is (0.9-1):

1.

6. The preparation method according to claim 2 or 5, characterized in that: The polymerization reaction temperature is 15-25° C. and the reaction time is 10-30 minutes.

7. The preparation method according to claim 2, characterized in that: The molar ratio of the di-n-butylamine to the ionic liquid is (0.1-1):

1.

8. The preparation method according to claim 2 or 7, characterized in that: The end-capping temperature is 15-25° C. and the time is 10-90 min.

9. A water-based lubricant, characterized in that: The invention comprises water and a water-based lubricating additive, wherein the water-based lubricating additive is the polyurea-type water-based lubricating additive according to claim 1 or the polyurea-type water-based lubricating additive prepared by the preparation method according to any one of claims 2 to 8.

10. The water-based lubricant according to claim 9, characterized in that The mass fraction of the water-based lubricating additive in the water-based lubricant is 0.5-5%.

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