Composite self-lubricating microcapsule filler, preparation method and application

Abstract

The invention provides a composite self-lubricating microcapsule filler as well as a preparation method and application thereof, and belongs to the technical field of lubricating materials. The composite self-lubricating microcapsule filler comprises microcapsules and a two-dimensional material represented by graphene (Gr), wherein the microcapsules comprise various microcapsules wrapping a single core material or microcapsules wrapping a composite core material; the microcapsule is prepared by adopting an in-situ polymerization method, and a core material of the microcapsule comprises a lubricant and liquid crystal. The liquid crystals and the two-dimensional material can generate a size synergistic effect, so that the liquid crystals can be orderly arranged on the plane of the two-dimensional material. And mixing the microcapsule wrapping the single lubricant and the single liquid crystal with graphene according to a ratio of (50-150): (1-5): (2-8) to obtain the composite self-lubricating microcapsule filler. The composite self-lubricating microcapsule filler can generate a good synergistic effect, and can be applied to a polymer lubricating base material to obtain a composite lubricant with excellent performance.

Description

Technical Field

[0001] The invention relates to a composite self-lubricating microcapsule filler, a preparation method and application thereof, and belongs to the technical field of lubricating materials. Background Art

[0002] With the development of industry, the failure of mechanical equipment materials due to friction and wear caused by contact movement during use is still a major problem. Therefore, the demand for high-performance lubricating materials in the field of friction lubrication is increasing day by day, in order to continuously reduce the friction and wear coefficient of equipment materials and increase the service life of equipment. The traditional external lubrication method is to directly add lubricant to the interface of two friction surfaces. This method has limitations under certain conditions, and the lubrication effect is poor under specific working conditions, which is easy to cause equipment failure and damage.

[0003] Under extremely harsh conditions, such as high temperature, humidity, vacuum, heavy load, high speed, strong oxidation and corrosion environment, liquid lubricants are no longer applicable. At this time, epoxy resin polymer coatings can be used to protect the contact surfaces in relative motion. However, compared with liquid lubrication, pure epoxy resin polymer solid lubricant coatings have poor wear resistance, high friction coefficient, and limited wear and friction reduction performance. In the prior art, the liquid lubricant is combined with the polymer solid lubricant matrix by filling microcapsules containing liquid lubricants in the polymer matrix. The microcapsules in this composite lubricant will break under friction and shear, and the liquid lubricant will leak out from the broken microcapsules to form solid-liquid synergistic lubrication, thereby improving the friction reduction performance of the substrate. Summary of the invention

[0004] The invention provides a composite self-lubricating microcapsule filler containing base oil and thermotropic liquid crystal, and a preparation method and application thereof.

[0005] The composite self-lubricating microcapsule filler contains a certain mass ratio of microcapsules filled with lubricating oil PAO6, microcapsules filled with liquid crystal 5CB and graphene. Under the action of friction, liquid crystal 5CB and lubricating oil PAO6 overflow from the worn microcapsules. The hexagonal structure of graphene can induce the liquid crystal 5CB containing cyanobiphenyl groups and alkyl tails to be highly ordered on the graphene surface based on the stacking interaction of strong π bonds. In addition, the side distance of the graphene hexagonal lattice (2.42 Å) and the bond length of the CC bond of the alkyl tail of the liquid crystal 5CB (1.52 Å) are very matched in size, which also promotes the orderliness of the arrangement of the liquid crystal 5CB. The ordered stacking of the above-mentioned liquid crystal 5CB on the graphene surface can reduce the wrinkles of graphene and inhibit the agglomeration of graphene, so that the lubricity of graphene can be fully exerted; on the other hand, graphene can also balance the changes in the mechanical properties of the filled polymer lubricating matrix caused by the filler, and maximize the mechanical properties of the polymer lubricating matrix. In summary, the composite self-lubricating filler composed of liquid crystal 5CB microcapsules, lubricating oil PAO6 microcapsules and graphene can produce good synergistic effects. The application of this filler in polymer lubricating matrix can obtain a composite lubricant with excellent performance.

[0006] The specific technical solutions are as follows:

[0007] The present invention provides a composite self-lubricating microcapsule filler, comprising microcapsules and two-dimensional materials; the microcapsules are multiple microcapsules encapsulating a single core material, or microcapsules encapsulating a composite core material; the multiple microcapsules encapsulating a single core material include microcapsules encapsulating a single lubricant and microcapsules encapsulating a single liquid crystal; the microcapsules encapsulating a composite core material are microcapsules encapsulating a composite core material of a lubricant and a liquid crystal;

[0008] The liquid crystal is used to produce a size synergistic effect with the two-dimensional material, so that the liquid crystal can be arranged in an orderly manner on the plane of the two-dimensional material.

[0009] Optionally, the lubricant includes mineral oils such as polyalphaolefins and silicone oils, or bio-oils such as linseed oil and tung oil;

[0010] The liquid crystal is a thermotropic liquid crystal, selected from one or more of liquid crystal 5CB, liquid crystal 6CB and liquid crystal 7CB;

[0011] The microcapsule shell material is urea-formaldehyde resin;

[0012] The two-dimensional material is graphene and its derivatives.

[0013] Optionally, in the composite self-lubricating microcapsule filler, the mass ratio of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal, and graphene is (50-150): (1-5): (2-8).

[0014] Preferably, in the composite self-lubricating microcapsule filler, the mass ratio of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal, and graphene is (75-125): (1-3): (3-5).

[0015] The present invention also provides a method for preparing a composite self-lubricating microcapsule filler, the method comprising the following steps:

[0016] Step 1, preparing microcapsules: preparing a solution of monomer raw materials for preparing microcapsule shell materials, adding an emulsifier for emulsification, and then adding a single microcapsule core material, and in-situ polymerization to obtain a microcapsule encapsulating the single core material;

[0017] Step 2, mixing the microcapsules with different wrapped single core materials prepared in step 1, and then mixing with graphene to obtain a composite self-lubricating microcapsule filler.

[0018] Optionally, the specific steps of step 1 are:

[0019] Step 101, preparing a solution of urea, resorcinol, ammonium chloride and water, adding polyvinyl alcohol for emulsification, and adjusting the pH to acidic;

[0020] Step 102, adding a single core material to the reaction solution obtained in step 1-1, and heating to 70° C.;

[0021] Step 103, adding formaldehyde to the reaction solution obtained in step 1-2, maintaining the temperature at 70° C. to obtain microcapsules;

[0022] The single core material is a lubricant or a liquid crystal;

[0023] The lubricant is polyalphaolefin, silicone oil, linseed oil or tung oil;

[0024] The liquid crystal is selected from thermotropic liquid crystals, including liquid crystal 5CB, liquid crystal 6CB and liquid crystal 7CB;

[0025] Preferably, the specific steps of step 102 are:

[0026] Step 102, mixing the single core material with dibutyl phthalate, adding the mixture to the reaction solution obtained in step 101, and heating the mixture to 70°C.

[0027] The present invention also provides an application of a composite self-lubricating microcapsule filler, and the application is specifically:

[0028] A composite self-lubricating microcapsule filler is added to a polymer lubricating base to obtain a composite lubricant, in which the mass ratios of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal and graphene in the composite lubricant are 5%-20%, 0.1%-0.5% and 0.2%-0.8% respectively.

[0029] Preferably, in the composite self-lubricating microcapsule filler, the mass ratios of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal, and graphene to the composite lubricant are 7.5% to 12.5%, 0.1% to 0.3%, and 0.3% to 0.5%, respectively.

[0030] Optionally, the polymer lubricating matrix is ​​epoxy resin.

[0031] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects:

[0032] The present invention uses microcapsule technology to encapsulate liquid lubricants, and adds them to a polymer matrix (epoxy resin) together with graphene to obtain a composite lubricant material. When the composite lubricant material is subjected to external force, the liquid lubricant PAO6 and liquid crystal 5CB in the microcapsules will be released to form a lubricating layer that acts as a liquid lubricant, thereby reducing friction and preventing direct surface contact. In addition, the presence of microcapsules can continuously release new lubricants during the wear process, so that the material continues to maintain self-lubricating properties, and the cavity left by the rupture of the microcapsules can collect wear debris to reduce abrasive wear. The addition of graphene can not only further improve the tribological properties, but also balance the changes in the mechanical properties of the epoxy resin material caused by the microcapsules. Through the synergistic effect of microcapsules and graphene, while improving the lubrication properties of the epoxy resin material, its mechanical properties can be maintained or even enhanced to the maximum extent.

[0033] Under the optimal addition ratio of multiple single core material microcapsules and graphene, the wear rate of the composite lubricant material was reduced by 96.10% compared with pure epoxy resin, showing excellent wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 SEM images of the microcapsules’ structure and morphology: (a) urea-formaldehyde resin microcapsules (@UF) without core material, (b) PAO6@UF, and (c) 5CB@UF.

[0036] Figure 2 The friction coefficient and wear volume of epoxy resin composite lubricating materials with different fillers added: (a) is the curve of friction coefficient changing with time, and (b) is the average friction coefficient and wear volume.

[0037] Figure 3SEM images of wear scars of different epoxy resin-based composite lubricant materials: (a) pure epoxy resin, (b) epoxy resin with 10wt% PAO6@UF added, (c) epoxy resin with 0.2wt% 5CB@UF added, (d) epoxy resin with 0.4wt% Gr added, (e) epoxy resin with 10 wt% PAO6@UF and 0.2wt% 5CB@UF added, (f) epoxy resin with 10wt% PAO6@UF and 0.4wt% Gr added, (g) epoxy resin with 10 wt% PAO6@UF, 0.2wt% 5CB@UF and 0.4wt% Gr added. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] A composite self-lubricating microcapsule filler, comprising microcapsules and two-dimensional materials; the microcapsules are multiple microcapsules encapsulating a single core material, or microcapsules encapsulating a composite core material; the multiple microcapsules encapsulating a single core material include microcapsules encapsulating a single lubricant and microcapsules encapsulating a single liquid crystal; the microcapsules encapsulating a composite core material are microcapsules encapsulating a composite core material of a lubricant and a liquid crystal;

[0040] The liquid crystal and the two-dimensional material can produce a size synergistic effect, so that the liquid crystal can be arranged in an orderly manner on the plane of the two-dimensional material.

[0041] Optionally, the lubricant includes polyalphaolefin, mineral oil such as silicone oil, or bio-oil such as linseed oil and tung oil; the polyalphaolefin may be lubricating oil PAO4, PAO6, PAO10.

[0042] The liquid crystal is a thermotropic liquid crystal, including liquid crystal 5CB, liquid crystal 6CB and liquid crystal 7CB;

[0043] The microcapsule shell material is urea-formaldehyde resin;

[0044] The two-dimensional material is graphene and its derivatives.

[0045] Optionally, in the composite self-lubricating microcapsule filler, the mass ratio of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal, and graphene is (50-150): (1-5): (2-8). This mass ratio can effectively reduce the friction coefficient of the polymer lubricating substrate. A more preferred mass ratio of the above three is (75-125): (1-3): (3-5).

[0046] The present invention also provides a method for preparing a composite self-lubricating microcapsule filler, the method comprising the following steps:

[0047] Step 1, preparing microcapsules: preparing a solution of monomer raw materials for preparing microcapsule shell materials, adding an emulsifier for emulsification, and then adding a single microcapsule core material, and in-situ polymerization to obtain a microcapsule encapsulating the single core material;

[0048] Step 2, mixing the microcapsules with different wrapped single core materials prepared in step 1, and then mixing with graphene to obtain a composite self-lubricating microcapsule filler.

[0049] Optionally, the specific steps of step 1 are:

[0050] Step 101, urea, resorcinol, ammonium chloride and water are prepared into a solution, polyvinyl alcohol is added for emulsification, and the pH is adjusted to acidic. In this step, ultrasonic dispersion can be used to completely dissolve the urea, resorcinol and ammonium chloride solution. The purpose of adjusting the pH to acidic is to activate the reactants so as to carry out the subsequent urea-formaldehyde resin polycondensation reaction.

[0051] Step 102, adding a single core material to the reaction solution obtained in step 1-1, and heating to 70° C.;

[0052] Step 103, adding formaldehyde to the reaction solution obtained in step 1-2, maintaining the temperature at 70° C. to obtain microcapsules;

[0053] The single core material includes a lubricant or a liquid crystal;

[0054] The lubricant includes polyalphaolefin (lubricating oil PAO6), silicone oil, linseed oil or tung oil;

[0055] The liquid crystal is a thermotropic liquid crystal, including liquid crystal 5CB, liquid crystal 6CB and liquid crystal 7CB;

[0056] Preferably, the specific steps of step 102 are:

[0057] Step 102, after mixing the single core material with dibutyl phthalate, add the mixture to the reaction solution obtained in step 101, and heat to 70° C. Dibutyl phthalate is a repairing agent, and as a core material, it can repair the wear marks on the friction surface.

[0058] The present invention also provides an application of a composite self-lubricating microcapsule filler, and the application is specifically:

[0059] A composite self-lubricating microcapsule filler is added to a polymer lubricating base material to obtain a composite lubricant, wherein the mass ratios of microcapsules encapsulating the lubricant, microcapsules encapsulating the liquid crystal, and graphene in the composite self-lubricating microcapsule filler are 5% to 20%, 0.1% to 0.5%, and 0.2% to 0.8% respectively. This mass ratio can effectively reduce the friction coefficient of the composite lubricant and reduce the wear volume of the composite lubricant.

[0060] The more preferred mass ratios of the above three are 7.5% to 12.5%, 0.1% to 0.3% and 0.3% to 0.5%, respectively.

[0061] Optionally, the polymer lubricating matrix is ​​epoxy resin.

[0062] Example 1 Preparation of microcapsules

[0063] S1 Urea, resorcinol, ammonium chloride and deionized water were mixed in a mass ratio of 10:1:1:400 to obtain a prefabricated solution (the following description is based on 10 g of urea). The prefabricated solution was stirred continuously with a magnetic stirrer (speed 500 rpm) for 30 minutes, and then the undissolved drugs were ultrasonically treated with a cell crusher. The power was set to 720 W, the ultrasonic time / interval time ratio was 1:5, the ultrasonic dispersion time was 15 minutes, and the ultrasonic transmitting probe was inserted about 1.5 cm below the sample liquid surface. After the drugs were completely dissolved and mixed, 0.5 g of emulsifier polyvinyl alcohol was injected, and then the magnetic stirrer was used to stir continuously (speed 300 rpm) for 5 minutes to wait for emulsification. After emulsification, the pH value of the solution was adjusted to 3.5 with dilute hydrochloric acid.

[0064] S2 Transfer the solution to a three-necked flask as a reaction vessel and stir it continuously with a magnetic stirrer (speed 500 rpm) for later use. Then slowly drip the core material - 20 ml lubricant PAO6 and 20 ml repair agent DPB (dibutyl phthalate) or 20 ml liquid crystal 5CB and 20 ml repair agent DBP (core material amount corresponds to 10 g urea amount) - into the aqueous phase in the three-necked flask through a constant pressure funnel, and the dripping is completed in about 20 minutes. Then heat it in a water bath (the water bath temperature is set to 70°C), and increase the stirring speed of the magnetic stirrer to 700 rpm.

[0065] The above-mentioned repair agent DBP can be omitted, and the corresponding amounts of lubricating oil PAO6 and liquid crystal 5CB are adjusted to 40 ml to correspond to the amount of urea 10 g.

[0066] S3 Weigh 26 g of formaldehyde (this dose corresponds to 10 g of urea) and pour it into a three-necked flask. Insert a condenser into one of the flask ports and plug the other two flask ports with rubber stoppers to prevent the formaldehyde from volatilizing due to heat and affecting the preparation effect. Continue heating in a water bath and stirring for 4 hours, then stop the reaction. After cooling to room temperature, remove the device and pour out the stock solution. Use a suction filter to filter and wash it. Finally, use a constant temperature drying oven (25°C) to dry it to obtain a light yellow or white powder. The two microcapsules coated with a single core material are respectively recorded as PAO6@UF and 5CB@UF (the SEM images of the microcapsules are shown in Figure 2). Figure 1 as shown).

[0067] Example 2-6 Preparation of composite self-lubricating microcapsule filler

[0068] The PAO6@UF, 5CB@UF and Gr prepared in Example 1 were mixed in a certain proportion to obtain a composite self-lubricating microcapsule filler, as shown in the following table:

[0069]

[0070] Examples 7-11 will take epoxy resin as an example of a polymer lubricating substrate to illustrate the preparation and application of the composite lubricating material of the present invention.

[0071] Example 7-11 Preparation of composite lubricating material

[0072] The composite self-lubricating microcapsule filler is prepared according to a certain mass ratio, added to the epoxy resin A glue and evenly dispersed by ultrasonic, and then the B glue is added to obtain a composite material. After the above composite material is fully mixed, it is vacuum dried at a constant temperature of 60°C for 72 hours to obtain a composite lubricating material. The details are shown in the following table:

[0073]

[0074] It should be noted that, according to the mass ratio of the two single core material microcapsules given in Example 2-6 and referring to the preparation method of Example 1, those skilled in the art can first prepare composite core material microcapsules by mixing the two single core materials (PAO6 and 5CB) in the mass ratio of Example 2-6, so that the mass ratio of PAO6 and 5CB in the composite core material microcapsules corresponds to that in Example 2-6; secondly, prepare microcapsule fillers by referring to the mass ratio of the filler components in Example 2-6, so that the mass ratio of PAO6, 5CB and graphene in the microcapsule fillers corresponds to that in Example 2-6; finally, incorporate the composite core material microcapsules into the epoxy resin by referring to the mass ratios of Examples 7-11 respectively, and the performance of the finally obtained composite lubricating material is similar to that in Examples 7-11.

[0075] The above-mentioned liquid crystal 5CB can be replaced by thermotropic liquid crystals such as liquid crystal 6CB and liquid crystal 7CB, and the performance of the finally obtained composite lubricating material is similar to that of Examples 7-11.

[0076] The above graphene can be replaced by a graphene derivative (such as graphene oxide, etc.), and the performance of the final composite lubricating material is similar to that of Examples 7-11.

[0077] The properties of the composite lubricating material described in Example 9 were selected for characterization. The friction coefficient and wear volume of the epoxy resin composite lubricating material with different fillers added were as follows: Figure 2 As shown: Pure epoxy resin has severe wear and the largest wear volume. When 10 wt% @UF microcapsules or 0.4 wt% Gr are added, the wear reduction effect is equivalent. After adding microcapsules coated with PAO6 or 5CB, the wear volume of the composite lubricant is significantly reduced. In particular, the wear resistance of the composite material with two microcapsules added at the same time is significantly better than that of the composite material doped with one microcapsule. The results show that the composite lubricant with 10 wt% PAO6@UF, 0.2 wt% 5CB@UF and 0.4 wt% Gr added at the same time has almost no wear marks, which is 96.10% lower than the wear of pure epoxy resin, showing excellent wear resistance.

[0078] The corresponding wear scar SEM image ( Figure 3 ) also confirmed the wear resistance of the above composite lubricant: when 10wt% PAO6@UF and 0.2wt% 5CB@UF microcapsules were added at the same time, adhesive wear basically disappeared and turned into a plowing effect, and the wear surface became smoother. When 10wt% PAO6@UF and 0.4wt% Gr were added at the same time, the adhesive wear was greatly weakened compared to the wear surface with a single filler, and only small pits existed on the surface, and there was also slight abrasive wear. Flake graphene was also observed on the wear surface. Figure 3 As shown in (g), the wear scar surface of the epoxy resin material with 10wt% PAO6@UF, 0.2wt% 5CB@UF and 0.4wt% Gr added at the same time is very smooth, and almost no wear is observed. This is the result of the self-lubrication of the surface of the composite lubricating material effectively inhibiting surface fatigue wear. The wear on the surface of the composite lubricating material during sliding causes the microcapsules to rupture and release lubricants and repair agents. The lubricant core material works synergistically with graphene to form a lubricating film on the surface to protect the friction surface. At the same time, graphene fills the pits to reduce surface wear.

[0079] By replacing other microcapsule core materials and two-dimensional materials described in the specification of the present invention, the performance of the composite self-lubricating microcapsule filler obtained is similar to that of Example 4, and the performance of the composite lubricant modified by using the filler is similar to that of Example 9, which will not be described in detail here. The principle is that there is a size synergistic effect between the liquid crystal substance and the two-dimensional material, so that the liquid crystal material can be orderly arranged on the plane of the two-dimensional material.

[0080] In addition, the improvement of the anti-wear performance of epoxy resin by the present invention is also significantly better than the prior art of adding other fillers to epoxy resin, as illustrated below:

[0081] Li et al. prepared tung oil microcapsules and studied the tribological properties of epoxy resin doped with tung oil microcapsules. When 10 wt% of tung oil microcapsules were added, the friction coefficient was reduced by 17.3% and the wear rate was reduced by 78.6% compared with the use of epoxy resin as a lubricating material alone. (LI H, CUI Y, LI Z, et al. Fabrication of microcapsules containing dual-functional tung oil and properties suitable for self-healing and self-lubricating coatings[J]. Progress in Organic Coatings, 2018, 115: 164-71.)

[0082] KY EAYAL AWWAD et al. added 4.5wt% Gr to epoxy resin, reducing the friction coefficient and wear of epoxy resin by 36% and 75% respectively by reducing 4.5wt% GNP. (AWWAD K, BFYOUSIF, FALLAHNEZHAD K, et al. Influence of graphene nanoplatelets on mechanical properties and adhesive wear performance of epoxy-based composites[J]. Friction, 2021, 9(04): 856-875.)

[0083] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope determined by the claims.

Claims

1. A composite self-lubricating microcapsule filler, It is characterized in that It includes microcapsules and two-dimensional materials; the microcapsules are multiple microcapsules encapsulating a single core material, or microcapsules encapsulating a composite core material; the multiple microcapsules encapsulating a single core material include microcapsules encapsulating a single lubricant and microcapsules encapsulating a single liquid crystal; the microcapsules encapsulating a composite core material are microcapsules encapsulating a composite core material of a lubricant and a liquid crystal; The liquid crystal is used to generate a size synergistic effect with the two-dimensional material, so that the liquid crystal can be arranged in an orderly manner on the plane of the two-dimensional material.

2. The composite self-lubricating microcapsule filler according to claim 1, It is characterized in that The lubricant is mineral oil or bio-oil; the mineral oil is poly-alpha-olefin or silicone oil; the bio-oil is linseed oil or tung oil; The liquid crystal is a thermotropic liquid crystal, selected from one or more of liquid crystal 5CB, liquid crystal 6CB and liquid crystal 7CB; The microcapsule shell material is urea-formaldehyde resin; The two-dimensional material is graphene and its derivatives.

3. The composite self-lubricating microcapsule filler according to claim 2, It is characterized in that In the composite self-lubricating microcapsule filler, the mass ratio of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal, and graphene is (50-150): (1-5): (2-8).

4. The composite self-lubricating microcapsule filler according to claim 3, It is characterized in that In the composite self-lubricating microcapsule filler, the mass ratio of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal, and graphene is (75-125): (1-3): (3-5).

5. A method for preparing the composite self-lubricating microcapsule filler according to claim 3 or 4, It is characterized in that The steps include: Step 1, preparing microcapsules: preparing a solution of monomer raw materials for preparing microcapsule shell materials, adding an emulsifier for emulsification, and then adding a single microcapsule core material, and in-situ polymerization to obtain a microcapsule encapsulating the single core material; Step 2, mixing the microcapsules with different wrapped single core materials prepared in step 1, and then mixing with graphene to obtain a composite self-lubricating microcapsule filler.

6. The method according to claim 5, It is characterized in that The specific steps of step 1 are: Step 101, preparing a solution of urea, resorcinol, ammonium chloride and water, adding polyvinyl alcohol for emulsification, and adjusting the pH to acidic; Step 102, adding a single core material to the reaction solution obtained in step 101, and heating to 70° C.; Step 103, adding formaldehyde to the reaction solution obtained in step 102, maintaining the temperature at 70° C. to obtain microcapsules; The single core material is a lubricant or a liquid crystal.

7. The method according to claim 6, It is characterized in that The specific steps of step 102 are: Step 102, mixing the single core material with dibutyl phthalate, adding the mixture to the reaction solution obtained in step 101, and heating the mixture to 70°C.

8. An application of the composite self-lubricating microcapsule filler according to claim 3 or 4, It is characterized in that The application is specifically: A composite self-lubricating microcapsule filler is added to a polymer lubricating base to obtain a composite lubricant, in which the mass ratios of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal and graphene in the composite lubricant are 5%-20%, 0.1%-0.5% and 0.2%-0.8% respectively.

9. The use according to claim 8, It is characterized in that In the composite self-lubricant filler, the mass ratios of microcapsules encapsulating a single lubricant, microcapsules encapsulating a single liquid crystal, and graphene in the composite lubricant are 7.5% to 12.5%, 0.1% to 0.3%, and 0.3% to 0.5%, respectively.

10. The use according to claim 9, It is characterized in that The polymer lubricating base material is epoxy resin.

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