Composite self-lubricating microcapsule filler, preparation method and application

Abstract

The present invention provides a composite self-lubricating microcapsule filler, its preparation method, and application, belonging to the technical field of lubricating materials. The composite self-lubricating microcapsule filler comprises microcapsules and a two-dimensional material represented by graphene (Gr). The microcapsules include a variety of microcapsules encapsulating a single core material or microcapsules encapsulating a composite core material. The microcapsules are prepared by an in-situ polymerization method, and the core material of the microcapsules comprises a lubricant and a liquid crystal. The liquid crystal and the two-dimensional material produce a size synergistic effect, enabling the liquid crystal to be arranged in an orderly manner on the plane of the two-dimensional material. The composite self-lubricating microcapsule filler is obtained by mixing the microcapsules encapsulating a single lubricant and a single liquid crystal with the graphene in a ratio of (50-150):(1-5):(2-8). The composite self-lubricating microcapsule filler exhibits excellent synergistic effects and, when applied to a polymer lubricating substrate, can produce 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 motion during use remains a major problem. Therefore, the demand for high-performance lubricants in the field of friction lubrication is increasing, in order to continuously reduce the friction and wear coefficient of equipment materials and extend equipment service life. Traditional external lubrication methods directly add lubricant to the interface between two friction surfaces. This method has limitations under certain conditions and is not effective in lubrication under certain operating conditions, which can easily cause equipment failure and damage.

[0003] Under extremely harsh conditions, such as high temperature, humidity, vacuum, heavy load, high speed, strong oxidation and corrosive environment, liquid lubricants are no longer applicable. In this case, epoxy resin polymer coatings can be used to protect the contact surfaces in relative motion. However, compared with liquid lubrication, simple 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 the polymer matrix with microcapsules containing liquid lubricant. The microcapsules in this composite lubricant will break under the action of friction and shear, and the liquid lubricant will leak out of the broken microcapsules, forming 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 microcapsules filled with lubricant PAO6, microcapsules filled with liquid crystal 5CB, and graphene in a certain mass ratio. Under friction, the liquid crystal 5CB and lubricant PAO6 escape from the worn microcapsules. The hexagonal structure of graphene, through strong π-bond stacking interactions, induces highly ordered stacking of the liquid crystal 5CB containing cyanobiphenyl groups and alkyl tails on the graphene surface. Furthermore, the close match between the edge-to-edge distance of the graphene hexagonal lattice (2.42 Å) and the C-C bond length of the alkyl tail of the liquid crystal 5CB (1.52 Å) also promotes the orderliness of the liquid crystal 5CB arrangement. This ordered stacking of the liquid crystal 5CB on the graphene surface reduces graphene wrinkling and inhibits graphene aggregation, thereby fully utilizing the lubricity of graphene. Furthermore, the graphene also balances the changes in the mechanical properties of the polymer lubricated matrix caused by the filler, maximizing or even enhancing the mechanical properties of the polymer lubricated 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 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.

[0009] Optionally, the lubricant includes mineral oils such as polyalphaolefins and silicone oil, 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, which comprises 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 microcapsules encapsulating the single core material;

[0017] Step 2: Mix the microcapsules with different wrapped single core materials prepared in step 1, and then mix them 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 the 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 reaction temperature at 70° C. to obtain microcapsules;

[0022] The single core material is a lubricant or 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] In step 102, the single core material is mixed with dibutyl phthalate, and then added to the reaction solution obtained in step 101, and heated to 70°C.

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

[0028] A composite self-lubricating microcapsule filler is added to a polymer lubricating base to obtain a composite lubricant. In the composite self-lubricating microcapsule filler, 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] The technical solution provided by the present invention has at least the following beneficial effects compared with the prior art:

[0032] This invention utilizes microcapsule technology to encapsulate a liquid lubricant and, along with graphene, add it to a polymer matrix (epoxy resin) to create a composite lubricant material. When this composite lubricant is subjected to external forces, the liquid lubricant PAO6 and liquid crystal 5CB within the microcapsules are released, forming a lubricating layer that acts as a liquid lubricant, thereby reducing friction and preventing direct surface contact. Furthermore, the presence of the microcapsules allows for the continuous release of new lubricant during wear, maintaining the material's self-lubricating properties. The cavities left by ruptured microcapsules collect wear debris, reducing abrasive wear. The addition of graphene not only further improves tribological properties but also balances the effects of the microcapsules on the mechanical properties of the epoxy resin. Through the synergistic effect of the microcapsules and graphene, the epoxy resin material's lubrication properties are improved while its mechanical properties are maximized or even enhanced.

[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: (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 10wt% PAO6@UF and 0.2wt% 5CB@UF added, (f) epoxy resin with 10wt% PAO6@UF and 0.4wt% Gr added, and (g) epoxy resin with 10wt% PAO6@UF, 0.2wt% 5CB@UF, and 0.4wt% Gr added. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments 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 a two-dimensional material; the microcapsules are a plurality of microcapsules encapsulating a single core material, or microcapsules encapsulating a composite core material; the plurality of 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, which comprises 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 microcapsules encapsulating the single core material;

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

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

[0050] In 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 an acidic state. 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 an acidic state is to activate the reactants for the subsequent urea-formaldehyde resin polycondensation reaction.

[0051] Step 102, adding the 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 reaction 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] In step 102, the single core material is mixed with dibutyl phthalate, added to the reaction solution obtained in step 101, and heated to 70° C. Dibutyl phthalate is a repair agent and can repair wear marks on the friction surface as a core material.

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

[0059] A composite lubricant is prepared by adding a composite self-lubricating microcapsule filler to a polymer lubricating base material. The mass ratios of lubricant-encapsulating microcapsules, liquid crystal-encapsulating microcapsules, and graphene in the composite lubricant are 5% to 20%, 0.1% to 0.5%, and 0.2% to 0.8%, respectively. This mass ratio effectively reduces the friction coefficient and 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: Mix urea, resorcinol, ammonium chloride, and deionized water in a mass ratio of 10:1:1:400 to prepare a preformed solution (10 g of urea is used as a reference in all descriptions below). Stir the preformed solution continuously (500 rpm) for 30 minutes using a magnetic stirrer. Then, sonicate the undissolved drug using a cell disrupter. The power setting is 720 W, the sonication time / interval ratio is 1:5, and the sonication dispersion time is 15 minutes. The ultrasonic transmitter probe is inserted approximately 1.5 cm below the sample liquid surface. Once the drug is completely dissolved and mixed, inject 0.5 g of the emulsifier, polyvinyl alcohol. Stir continuously (300 rpm) using a magnetic stirrer for 5 minutes until emulsification occurs. After emulsification, adjust the solution pH to 3.5 using dilute hydrochloric acid.

[0064] S2: Transfer the solution to a three-necked reaction flask and stir continuously with a magnetic stirrer (500 rpm) until ready for use. Then, slowly add the core material—20 ml of lubricant PAO6 and 20 ml of the repair agent DPB (dibutyl phthalate) or 20 ml of liquid crystal 5CB and 20 ml of the repair agent DBP (the amount of core material corresponds to 10 g of urea)—dropwise to the aqueous phase in the three-necked flask via a constant pressure funnel. The addition should be complete over approximately 20 minutes. The mixture is then heated in a water bath (set to 70°C) and the magnetic stirrer speed is increased 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 urea amount of 10 g.

[0066] S3: Weigh 26 g of formaldehyde (this dosage corresponds to 10 g of urea) and pour it into a three-necked flask. Insert a condenser into one of the flask openings and plug the other two flask openings with rubber stoppers to prevent the formaldehyde from volatilizing due to heat and affecting the preparation effect. Continue heating and stirring in a water bath for 4 hours, then stop the reaction. After cooling to room temperature, dismantle the apparatus and pour out the original solution. Use a suction filter to filter and wash it, and finally dry it in a constant temperature drying oven (25°C) to obtain a light yellow or white powder. The two microcapsules coated with a single core material are respectively designated as PAO6@UF and 5CB@UF (the structural morphology SEM image of the microcapsules is shown in Figure 2). Figure 1 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 use epoxy resin as an example of a polymer lubricating base material to illustrate the preparation and application of the composite lubricating material of the present invention.

[0071] Examples 7-11 Preparation of composite lubricating materials

[0072] A composite self-lubricating microcapsule filler was prepared according to a specific mass ratio and added to epoxy resin glue A for uniform ultrasonic dispersion. Then, glue B was added to obtain a composite material. After the composite material was thoroughly mixed, it was vacuum-dried at 60°C for 72 hours to cure, resulting in 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 mix the two single core materials (PAO6 and 5CB) in the mass ratio according to Example 2-6 to prepare composite core material microcapsules, 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 with reference 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 with reference 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 final 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 obtained 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 exhibits severe wear, with the largest wear volume. When 10 wt% @UF microcapsules or 0.4 wt% Gr are added, the wear reduction effect is comparable. 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 containing both microcapsules is significantly better than that of the composite containing only one microcapsule. The results show that the composite lubricant containing 10 wt% PAO6@UF, 0.2 wt% 5CB@UF, and 0.4 wt% Gr exhibits almost no wear, reducing wear by 96.10% compared to pure epoxy resin, demonstrating excellent wear resistance.

[0078] The corresponding wear scar SEM image ( Figure 3 ) also confirmed the wear resistance of the above-mentioned composite lubricant: when 10wt% PAO6@UF and 0.2wt% 5CB@UF microcapsules were added at the same time, the 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. 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 and graphene work synergistically 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 the other microcapsule core materials and two-dimensional materials described in this specification, the resulting composite self-lubricating microcapsule filler exhibited similar performance to that of Example 4. The performance of the composite lubricant modified with this filler was similar to that of Example 9, and these details are omitted here. The underlying principle is that the size synergy between the liquid crystal and the two-dimensional material allows the liquid crystal to align in an orderly manner on the two-dimensional surface.

[0080] In addition, the present invention also significantly improves the anti-wear performance of epoxy resins over the prior art of adding other fillers to epoxy resins, as illustrated below:

[0081] Li et al. prepared tung oil microcapsules and studied the tribological properties of epoxy resin doped with them. When 10 wt% of tung oil microcapsules were added, the friction coefficient decreased by 17.3% and the wear rate by 78.6%, compared to using epoxy resin alone as a lubricant. (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 4.5 wt% Gr to epoxy resin, reducing the friction coefficient and wear loss of epoxy resin by 36% and 75%, respectively. (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 foregoing description is merely a specific embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any person skilled in the art will readily conceive of various equivalent modifications or substitutions within the technical scope disclosed herein, and such modifications or substitutions are intended to be encompassed within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection defined in the claims.

Claims

1. A composite self-lubricating microcapsule filler, characterized in that: The invention comprises 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; The lubricant is mineral oil or bio-oil; the mineral oil is polyalphaolefin or silicone oil; the bio-oil is linseed oil or tung oil; The liquid crystal is a thermotropic liquid crystal selected from 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; 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).

2. The composite self-lubricating microcapsule filler according to claim 1, 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).

3. A method for preparing the composite self-lubricating microcapsule filler according to claim 1, 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 microcapsules encapsulating the single core material; Step 2: Mix the microcapsules with different wrapped single core materials prepared in step 1, and then mix them with graphene to obtain a composite self-lubricating microcapsule filler.

4. The method according to claim 3, wherein 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 the 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 reaction temperature at 70° C. to obtain microcapsules; The single core material is a lubricant or liquid crystal.

5. The method according to claim 4, wherein The specific steps of step 102 are: In step 102, a single core material is mixed with dibutyl phthalate, and then added to the reaction solution obtained in step 101, and heated to 70°C.

6. An application of the composite self-lubricating microcapsule filler according to claim 1, 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 the composite self-lubricating microcapsule filler, 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.

7. The use according to claim 6, 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.

8. The use according to claim 7, characterized in that The polymer lubricating base material is epoxy resin.

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