Self-lubricating polymer coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of polymer composite materials, and relates to a self-lubricating polymer coating as well as a preparation method and application thereof. The coating comprises epoxy resin, a curing agent, a toughening agent, a solid lubricant, oil-containing microcapsules, nanoparticles, an organic solvent, a dispersing agent and a flatting agent. Wherein a core material of the oil-containing microcapsule is a mixture of poly-alpha-olefin oil and molybdenum disulfide nanosheets, and a wall material of the oil-containing microcapsule is carbohydrate or protein. Under the condition of high-load low-speed coupling friction, the microcapsules coated with PAO and MoS2 are continuously broken, controllable release, long-term lubrication and self-repairing are achieved, a nano-scale friction chemical transfer membrane can be rapidly constructed on the surface of a metal mating plate under the synergistic effect of the solid lubricant and nano-particles, and the dry friction coefficient reaches 0.05 or below. The coating material is particularly suitable for the surfaces of key parts of an automobile safety belt locking structure, and can remarkably improve the reliability and prolong the service life of an automobile safety system.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to a self-lubricating polymer coating, its preparation method, and its application in the surface of automotive seat belt locking structures. Background Technology

[0002] Seat belts are a core component of a vehicle's passive safety system, and the reliability of their locking structure directly affects the safety of occupants. Currently, most vehicles use purely mechanical inertial locking mechanisms. Their core components (such as locking blocks, locking plates, and locking claws) must maintain stable and reliable locking and disengagement functions under extreme conditions such as high speed, high load, and dry friction during long-term service. Therefore, constructing a solid lubricating coating on the surface of these critical metal components, which combines excellent friction reduction, wear resistance, and long service life, is a key technical means to improve the overall reliability of the seat belt system.

[0003] As the automotive industry moves towards lightweight and long-life designs, higher performance requirements are being placed on solid lubricant coatings. While traditional single-solid lubricant coatings (such as polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS2), and graphite) offer some friction reduction, the lubricating film is easily damaged and worn through under harsh operating conditions of high load, low speed, and reciprocating motion, making long-term lubrication difficult. To overcome this deficiency, existing technologies have developed a technique of combining lubricating oil or grease with a polymer matrix.

[0004] A common improvement method is to use polymer-grafted modified lubricating oil to introduce liquid lubricant into the coating. However, this method faces many challenges in practical applications, such as the complexity and high cost of the grafting modification process, and the tendency to have insufficient grafting, oil phase precipitation, and uneven dispersion in the matrix, which seriously restricts its large-scale production and practical application effects.

[0005] To address the aforementioned issues, microencapsulation technology has garnered significant attention in recent years. This technology encapsulates liquid lubricants (such as synthetic oils) within micro-containers formed from polymer wall materials (such as urea-formaldehyde resin, melamine resin, and polyurethane), creating an "oil reservoir" structure, which is then dispersed within the polymer coating matrix. When the coating is subjected to external stress or temperature stimuli during friction, the microcapsule wall ruptures, releasing the sealed lubricant to the friction interface. This achieves continuous lubricant replenishment and coating self-repair, potentially significantly extending the coating's service life. However, existing microencapsulation coating technologies still suffer from the following shortcomings: First, the interfacial bonding strength between the wall material and the coating matrix, as well as the microencapsulation's mechanical properties, need further improvement. Second, the oil film strength formed by the liquid lubricant under ultra-high contact pressure is limited, making it prone to being squeezed out of the friction interface, leading to lubrication failure. Furthermore, achieving precise coordination between microcapsule rupture and release and the film formation process at the friction interface to rapidly construct a stable solid-liquid composite lubricating film remains a technical challenge in this field.

[0006] Therefore, how to develop a polymer coating material that can achieve efficient and long-lasting lubrication under harsh working conditions of dry friction, high load and low speed, and whose preparation process is simple and cost controllable, and successfully apply it to the surface of key components such as automotive seat belt locking structures, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a self-lubricating polymer coating capable of achieving ultra-low friction coefficient and long-lasting wear resistance under harsh working conditions, as well as its preparation method.

[0008] The present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a self-lubricating polymer coating comprising the following components by weight percentage: Epoxy resin 20-35%; Hardener 3-10%; Toughening agent 5-10%; Solid lubricant 5-15%; Oil-containing microcapsules 2-8%; Nanoparticles 0.5-3%; Organic solvents 30-60%; Dispersant 0.1-3%; Leveling agent 0.1-3%; The core material of the oil-containing microcapsules is a mixture of polyalphaolefin oil and molybdenum disulfide nanosheets, and the wall material is carbohydrates or proteins.

[0010] Furthermore, the lateral dimension of the molybdenum disulfide nanosheets does not exceed 1 μm, the kinematic viscosity of the polyalphaolefin oil at 100℃ is ≤6 mm² / s, and the mass ratio of molybdenum disulfide nanosheets to polyalphaolefin oil in the core material is (1-5):(95-99).

[0011] Furthermore, the wall material is a mixture of maltodextrin and OSA-modified starch, or a mixture of maltodextrin and gum arabic, with a mixing mass ratio of 7:3.

[0012] Furthermore, the nanoparticles are at least one of silicon dioxide, aluminum oxide, silicon carbide, or titanium nitride with a particle size of less than 100 nm.

[0013] Furthermore, the epoxy resin is a phenolic epoxy resin, the toughening agent is a carboxyl-terminated nitrile rubber, the solid lubricant is polytetrafluoroethylene, and the curing agent is 4,4'-diaminodiphenyl sulfone.

[0014] Secondly, the present invention provides a method for preparing the self-lubricating polymer coating, comprising the following steps: (1) Molybdenum disulfide nanosheets were dispersed in polyα-olefin oil and subjected to ultrasonic treatment to obtain oil phase A; (2) Dissolve the wall material and nonionic surfactant in deionized water to obtain aqueous phase A; (3) The oil phase A is dropped into the aqueous phase A under shear conditions, and shear emulsification is performed to obtain a crude emulsion; (4) The crude emulsion is homogenized under high pressure to obtain a stable oil-in-water emulsion; (5) Spray dry the oil-in-water emulsion, collect the powder, and vacuum dry it to obtain oil-containing microcapsules; (6) Dissolve epoxy resin and toughening agent in organic solvent, add dispersant and leveling agent, mix well to obtain solution B; (7) Add nanoparticles, oil-containing microcapsules, curing agent and solid lubricant to solution B, grind and mix to obtain the self-lubricating polymer coating.

[0015] Furthermore, the pressure of the high-pressure homogenization in step (4) is 30-50 MPa, and the cycle is repeated 2-5 times.

[0016] Furthermore, the stable oil-in-water emulsion described in step (4) exhibits a distinct blue light and no oil layer precipitates after standing for 2 hours.

[0017] Furthermore, the inlet temperature of the spray dryer in step (5) is 150-180℃ and the outlet temperature is 90-100℃.

[0018] Furthermore, the grinding speed in step (7) is 1000-2000 rpm and the time is 1-6 h.

[0019] Thirdly, the present invention provides the application of the self-lubricating polymer coating described in any of the above technical solutions on the surface of the locking structure of an automotive seat belt.

[0020] This invention encapsulates liquid PAO oil and solid MoS2 nanosheets within a carbohydrate or protein wall material, forming a composite oil-containing microcapsule. Under dry friction, high-load, low-speed conditions, the high pressure, temperature, and shear force generated in the contact area of ​​the friction pair cause the microcapsule wall material to rupture, releasing the composite core material to the friction interface. At this point, the following synergistic effects occur: First, the released MoS2 nanosheets act as a solid lubricant, directly participating in lubrication. Their layered structure undergoes interlaminar slippage under shear force, providing basic lubrication. Simultaneously, under the influence of frictional heat and contact stress, the active sites exposed at the edges of the MoS2 nanosheets are activated by trace amounts of oxygen and water molecules in the environment. These active sites mainly include Mo atoms that are not fully coordinated on the inert basal plane of the MoS2 nanosheets, i.e., Lewis acid sites, which can attract the C–H and C–C electron clouds of PAO, promoting bond breaking.

[0021] Meanwhile, unsaturated Mo atoms at the edges of MoS2 and friction-induced MoS2 atoms... x Non-stoichiometric phases and MoO x The oxides; carboxyl groups (-COOH), hydroxyl groups (-OH), ether bonds, and C=C double bonds on the surface of the CTBN-toughened epoxy coating; and Si–OH hydroxyl groups and oxygen vacancies on the surface of nano-SiO2. These sites are all Lewis acid / protic acid / free radical active centers, capable of catalyzing the formation of short-chain alkanes, alkenes, and active carbon (including free radicals and carbocations) from PAO long-chain alkanes. These active substances are adsorbed onto the surface of the metal friction pair through van der Waals forces, forming a primary adsorption film that prevents direct contact between the friction pairs. The primary adsorption film further evolves into a composite boundary lubrication film composed of MoS2, carbonaceous thin films, and transferred ceramic particles, ultimately achieving ultra-low friction and forming an amorphous carbonaceous lubrication film in situ at the friction interface.

[0022] Other components in the coating material play a synergistic role during friction: Carboxyl-terminated nitrile butadiene rubber (CTBN) undergoes stretching, yielding, and creasing under shearing, providing elasticity and absorbing energy, effectively inhibiting coating peeling. At the same time, CTBN reacts chemically with the epoxy resin through the carboxyl and hydroxyl groups on its surface, forming an "epoxy-CTBN elastic support layer" together with the epoxy resin. Meanwhile, MoS2 in the solid microcapsules undergoes edge oxidation, interface anchoring, and lamellar exfoliation, while PAO is pyrolyzed under the catalysis of MoS2 and the active sites of the coating to form a carbonaceous lubricating film. The four components work together to form an integrated wear-resistant and friction-reducing film of "epoxy-CTBN elastic support layer + MoS2 / carbon composite lubricating layer". Nano-SiO2 serves as a nano-reinforcement and chemical anchoring point. MoS2 and PTFE achieve ultra-low friction through layered slip and fluorocarbon transfer film, respectively. Meanwhile, PAO is rapidly catalytically decomposed by MoS2, SiO2, and epoxy active sites. This five-component system is coupled with catalytic decomposition and oxidative reconstruction through interfacial bonding such as Si-OC, Mo-O-Si, ester bonds, and fluoride bonds to form an integrated composite boundary lubricating film with high toughness, high hardness, ultra-low friction, and high stability, achieving synergistic toughening, synergistic friction reduction, and synergistic wear resistance.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are: 1. Ultra-low coefficient of friction: The coating of this invention can achieve a coefficient of friction as low as 0.05 under dry friction conditions, which is significantly better than conventional coatings.

[0024] 2. Excellent wear resistance: The coating of this invention can achieve a volumetric wear rate as low as 10% under high load and low speed conditions. -7 The wear resistance is on the order of mm³ / N·m, achieving an order of magnitude improvement over conventional coatings.

[0025] 3. High load adaptability: The coating of this invention can still maintain stable lubrication under contact stress of 200MPa, meeting the usage requirements of key components such as automotive seat belt locking structures.

[0026] 4. Long-lasting lubrication and self-repair: This invention achieves controlled release and continuous replenishment of lubricant through the "oil reservoir" structure of oil-containing microcapsules, and performs in-situ repair on worn areas, significantly extending the service life of the coating.

[0027] 5. Synergistic effect of multiple components: This invention achieves multiple functions of "toughening + strengthening + lubrication + catalysis" through the synergistic effect of oil-containing microcapsules, toughening agents, nanoparticles and solid lubricants.

[0028] 6. The preparation method has strong universality: oil-containing microcapsules prepared using different wall materials can achieve similar excellent performance, and the technical solution has wide applicability and industrial promotion value. Attached Figure Description

[0029] Figure 1 The image shows a micrograph of the wear track morphology of the coating sample prepared in Comparative Example 1 after a tribological test, with a magnification of 50x. Figure 2 The image shows a micrograph of the wear track morphology of the coating sample prepared in Comparative Example 2 after a tribological test, with a magnification of 50x. Figure 3 The image shows a micrograph of the wear track morphology of the coating sample prepared in Comparative Example 3 after a tribological test, with a magnification of 50x. Figure 4 The image shows a micrograph of the wear track morphology of the coating sample prepared in Comparative Example 4 after a tribological test, with a magnification of 50x. Figure 5 The image shows a micrograph of the wear track morphology of the coating sample prepared in Example 1 after a tribological test, magnified by 50x. Figure 6 The image shows a micrograph of the wear track morphology of the coating sample prepared in Example 2 after a tribological test, magnified by 50x. Figure 7 The image shows a micrograph of the wear track morphology of the coating sample prepared in Example 3 after a tribological test, magnified by 50x. Figure 8 The image shows a micrograph of the wear track morphology of the coating sample prepared in Example 4 after a tribological test, magnified by 50x. Figure 9 The image shown is a micrograph of the wear track morphology of the coating sample prepared in Example 5 after a friction and wear test, magnified by 50x. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0033] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] Comparative Example 1: Preparation method of pure epoxy resin coating 50 g of phenolic epoxy resin F51 was dissolved in 50 g of a mixed solvent, which consisted of butyl acetate, butanone, and anhydrous ethanol in a mass ratio of 1:1:1. 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 1.15 g of a low molecular weight unsaturated acidic polycarboxylic acid polyester-polysiloxane copolymer dispersant (brand name BYK-220S), and 1.15 g of a polyester-modified polydimethylsiloxane solution leveling agent (brand name BYK-310S) were added. The mixture was stirred at 1000 rpm for 5 min. After spraying and drying the solvent, the mixture was placed in a 200 ℃ forced-air drying oven for 2 h to cure, and its tribological properties were verified.

[0035] Comparative Example 2: Preparation method of carboxyl-terminated butadiene-acrylonitrile rubber toughened epoxy resin coating 50 g of phenolic epoxy resin F51 and 10 g of carboxyl-terminated nitrile butadiene rubber were dissolved in 60 g of a mixed solvent, which consisted of butyl acetate, butanone, and anhydrous ethanol in a mass ratio of 1:1:1. 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 1.35 g of a low molecular weight unsaturated acidic polycarboxylic acid polyester-polysiloxane copolymer dispersant (brand name BYK-220S), and 1.35 g of a polyester-modified polydimethylsiloxane solution leveling agent (brand name BYK-310S) were added. The mixture was stirred at 1000 rpm for 5 min. After spraying and drying the solvent, the mixture was placed in a 200 ℃ forced-air drying oven for 2 h to verify its tribological properties.

[0036] Comparative Example 3: Preparation method of nano-silica modified carboxyl-terminated butadiene-acrylonitrile rubber toughened epoxy resin coating 50 g of phenolic epoxy resin F51 and 10 g of carboxyl-terminated butadiene-acrylonitrile rubber were dissolved in 60 g of a mixed solvent, which consisted of butyl acetate, butanone, and anhydrous ethanol in a mass ratio of 1:1:1. 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 1.35 g of 50 nm nano-SiO2 particles, 1.36 g of a low molecular weight unsaturated acidic polycarboxylic acid polyester-polysiloxane copolymer dispersant (Brand: BYK-220S), and 1.36 g of a polyester-modified polydimethylsiloxane solution leveling agent (Brand: BYK-310S) were added. The mixture was stirred at 1000 rpm / min for 5 min. The stirred liquid was then ground in a coating mill at 1500 rpm / min for 2 h. After spraying with a drying solvent, the mixture was cured in a 200 ℃ forced-air drying oven for 2 h to verify its tribological properties.

[0037] Comparative Example 4: Preparation method of carboxyl-terminated butadiene-acrylonitrile rubber toughened epoxy resin coating synergistically modified with nano-silica and polytetrafluoroethylene 50 g of phenolic epoxy resin F51 and 10 g of carboxyl-terminated butadiene-acrylonitrile rubber were dissolved in 60 g of a mixed solvent, which consisted of butyl acetate, butanone, and anhydrous ethanol in a mass ratio of 1:1:1. 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 1 g of SiO2 particles with a particle size of 50 nm, 15 g of polytetrafluoroethylene powder with a particle size of 1 μm, 1.51 g of a low molecular weight unsaturated acidic polycarboxylic acid polyester-polysiloxane copolymer dispersant (brand name BYK-220S) and 1.51 g of polyester-modified polydimethylsiloxane solution leveling agent (brand name BYK-310S) were added. The mixture was stirred at 1000 rpm / min for 5 min. After stirring, the mixture was ground at 1500 rpm / min for 2 hours in a coating mill. After spraying with drying solvent, it was placed in a 200 ℃ forced-air drying oven for 2 hours to verify its tribological properties.

[0038] Example 1: Preparation method of pure epoxy resin coating modified with oil-containing microcapsules 1 g of MoS2 nanosheets with a particle size of 500 nm were weighed and added to 99 g of PAO4 synthetic base oil. The kinematic viscosity of the PAO4 synthetic base oil at 100 °C was approximately 4 mm² / s. The mixture was first initially dispersed by low-speed stirring at 100 rpm / min for 1 h. Then, the initially dispersed liquid was ultrasonically treated in an ice-water bath at 0 °C using a 300 W ultrasonic disruptor. The ultrasonic treatment frequency was 5 s for continuous operation followed by 5 s intermittent operation to prevent continuous operation from increasing the ice-water bath temperature and causing the nanosheets to settle, resulting in a uniform black suspended oil phase A. Weigh 30 g of mixed wall material (21 g maltodextrin + 9 g OSA starch) and 0.5 g polysorbate 80, heat in a water bath to 60 ℃ and dissolve in 170 g of deionized water, stir magnetically until completely clear to obtain aqueous phase A; The black suspended oil phase A was slowly dripped into the aqueous phase A at a shear rate of 8000 rpm and sheared continuously for 10 min to obtain a crude emulsion. The crude emulsion was transferred to a high-pressure homogenizer and homogenized three times at 40 MPa to obtain a fine, uniform, and stable oil-in-water emulsion exhibiting a distinct blue sheen. After standing for 2 hours, no oil layer should have separated. The above-mentioned stable oil-in-water emulsion was added to a centrifugal spray dryer. After the inlet temperature and outlet temperature stabilized at 170℃ and 95℃ respectively, the feed was started. The feed pump speed was 5 mL / min. The light gray to dark gray fine powder below the separator was collected. The obtained powder was placed in a 40℃ constant temperature vacuum drying oven and dried for 4 hours to remove residual moisture, finally obtaining co-encapsulated oil-containing microcapsules.

[0039] 50 g of phenolic epoxy resin F51 was dissolved in 50 g of a mixed solvent, which consisted of butyl acetate, butanone, and anhydrous ethanol in a mass ratio of 1:1:1. 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 3.45 g of the oil-containing microcapsules prepared above, 1.18 g of a low molecular weight unsaturated acidic polycarboxylic acid polyester-polysiloxane copolymer dispersant (brand name BYK-220S), and 1.18 g of a polyester-modified polydimethylsiloxane solution leveling agent (brand name BYK-310S) were added. The mixture was stirred at 1000 rpm for 5 min. After spraying and drying the solvent, the mixture was placed in a 200 ℃ forced-air drying oven for 2 h to cure, and its tribological properties were verified.

[0040] Example 2: Preparation method of toughened epoxy resin coating of carboxyl-terminated butadiene-acrylonitrile rubber modified with oil-containing microcapsules The preparation method of the oil-containing microcapsules is the same as in Example 1; 50 g of phenolic epoxy resin F51 and 10 g of carboxyl-terminated butadiene-acrylonitrile rubber were dissolved in a mixed solvent of 60 g of butyl acetate, butanone, and anhydrous ethanol (mass ratio 1:1:1). Then, 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 4.05 g of the oil-containing microcapsules prepared above, 1.39 g of low molecular weight unsaturated acidic polycarboxylic acid polyester and polysiloxane copolymer dispersant (brand name BYK-220S) and 1.39 g of polyester-modified polydimethylsiloxane solution leveling agent (brand name BYK-310S) were added. The mixture was stirred at high speed at 1000 rpm / min for 5 min. After spraying and drying the solvent, the mixture was placed in a 200 ℃ forced-air drying oven for 2 h to cure and verify its tribological properties.

[0041] Example 3: Preparation method of toughened epoxy resin coating of carboxyl-terminated butadiene-acrylonitrile rubber synergistic modification with oil-containing microcapsules / nano silica The preparation method of the oil-containing microcapsules is the same as in Example 1; 50 g of phenolic epoxy resin F51 and 10 g of carboxyl-terminated butadiene-acrylonitrile rubber were dissolved in a mixed solvent of 60 g of butyl acetate, butanone, and anhydrous ethanol (mass ratio 1:1:1). Then, 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 1.35 g of 50 nm nano-SiO2 particles, 4.09 g of the prepared oil-containing microcapsules, 1.40 g of low molecular weight unsaturated acidic polycarboxylic acid polyester-polysiloxane copolymer dispersant (Brand: BYK-220S), and 1.40 g of polyester-modified polydimethylsiloxane solution leveling agent (Brand: BYK-310S) were added. The mixture was stirred at 1000 rpm / min for 5 min. The stirred liquid was then ground in a coating mill at 1500 rpm / min for 2 h. After spraying with a drying solvent, the mixture was cured in a 200 ℃ forced-air drying oven for 2 h to verify its tribological properties.

[0042] Example 4: Preparation method of OSA starch oil-containing microcapsules / polytetrafluoroethylene / nano silica synergistic modification of carboxyl-terminated butadiene-acrylonitrile rubber toughened epoxy resin coating The preparation method of the oil-containing microcapsules is the same as in Example 1; 50 g of phenolic epoxy resin F51 and 10 g of carboxyl-terminated butadiene-acrylonitrile rubber were dissolved in a mixed solvent of 60 g butyl acetate, butanone, and anhydrous ethanol (mass ratio 1:1:1). Then, 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 1.35 g of SiO2 particles with a particle size of 50 nm, 15 g of polytetrafluoroethylene powder with a particle size of 1 μm, 4.54 g of oil-containing microcapsules prepared in the above steps, 1.56 g of low molecular weight unsaturated acidic polycarboxylic acid polyester and polysiloxane copolymer dispersant (brand name BYK-220S) and 1.56 g of polyester modified polydimethylsiloxane solution leveling agent (brand name BYK-310S) were added. The mixture was stirred at high speed at 1000 rpm / min for 5 min. After stirring, the mixture was ground at 1500 rpm / min for 2 hours in a coating mill. After spraying with drying solvent, it was placed in a 200 ℃ forced-air drying oven for 2 hours to verify its tribological properties.

[0043] Example 5: Preparation method of toughened epoxy resin coating of end-carboxyl butadiene nitrile rubber synergistically modified with gum arabic oil microcapsules / polytetrafluoroethylene / nano silica In the preparation method of oil-containing microcapsules, the wall material was replaced with 21 g maltodextrin + 9 g gum arabic, and the rest of the method was the same as in Example 1; 50 g of phenolic epoxy resin F51 and 10 g of carboxyl-terminated butadiene-acrylonitrile rubber were dissolved in a mixed solvent of 60 g butyl acetate, butanone, and anhydrous ethanol (mass ratio 1:1:1). Then, 15 g of latent curing agent 4,4'-diaminodiphenyl sulfone, 1.35 g of SiO2 particles with a particle size of 50 nm, 15 g of polytetrafluoroethylene powder with a particle size of 1 μm, 4.54 g of oil-containing microcapsules prepared in the above steps, 1.56 g of low molecular weight unsaturated acidic polycarboxylic acid polyester and polysiloxane copolymer dispersant (brand name BYK-220S) and 1.56 g of polyester modified polydimethylsiloxane solution leveling agent (brand name BYK-310S) were added. The mixture was stirred at high speed at 1000 rpm / min for 5 min. After stirring, the mixture was ground at 1500 rpm / min for 2 hours in a coating mill. After spraying with drying solvent, it was placed in a 200 ℃ forced-air drying oven for 2 hours to verify its tribological properties.

[0044] Test methods and results Friction and wear performance tests were conducted on the above comparative examples and embodiments. The testing equipment was a universal friction testing machine. The mating part was a 100Cr6 bearing steel ball with a diameter of 10 mm, and the coated sample was an automotive seat belt locking component. The test conditions were: load 100 N, stroke length 5 mm, reciprocating frequency 120 t / min, test duration 60 s, dry friction condition.

[0045] Calculations show that under a 100N load, the maximum contact stress between the steel ball and the coating surface is approximately 200MPa, which is comparable to the actual stress experienced by the locking structure of a car seatbelt under emergency locking conditions.

[0046] Formula for calculating volumetric wear rate:

[0047] in, Δm The difference in mass between the samples before and after the test , ρ Density of the sample coating , F Force applied in the normal direction , Rotational speed , t Rotation time .

[0048] The test results are shown in Table 1 and Figure 1-9 As shown.

[0049] Table 1. Friction coefficients and volumetric wear rates of the comparative examples and embodiments.

[0050] Based on the pure epoxy resin coating of Comparative Example 1, Comparative Examples 2, 3, and 4 were respectively supplemented with carboxyl-terminated butadiene-acrylonitrile rubber, nano-silica, and polytetrafluoroethylene. From the wear rate data in Table 1 and... Figures 1 to 4 The wear track width, depth, and morphology show that the addition of toughening agents and trace additives can reduce the coefficient of friction and wear track width of the coating, and improve the coating toughness to a certain extent. Specifically, Comparative Example 1 (pure epoxy resin coating) is as follows: Figure 1 As shown, the wear tracks are wide and deep, with large areas of spalling on the surface. The coefficient of friction is 0.198, and the volumetric wear rate is 1.25 × 10⁻⁶. -4 mm³ / N·m; Comparative Example 2 (CTBN toughened epoxy resin coating) Figure 2 As shown, the area of ​​wear scarring decreased, but the wear scar depth did not improve significantly. The coefficient of friction decreased to 0.173, but the volumetric wear rate increased to 4.38 × 10⁻⁶. -4 mm³ / N·m; Comparative Example 3 (CTBN + nano-SiO2 modified epoxy resin coating) Figure 3 As shown, the wear track width narrowed slightly, and the coefficient of friction further decreased to 0.153, but the volumetric wear rate remained as high as 9.62 × 10⁻⁶. -4 mm³ / N·m; Comparative Example 4 (CTBN + nano-SiO2 + PTFE modified epoxy resin coating) Figure 4 As shown, the wear track width is significantly narrower, the surface is smoother, the coefficient of friction is significantly reduced to 0.110, and the volumetric wear rate is significantly reduced to 1.79 × 10⁻⁶. -5 mm³ / N·m. The above results indicate that the gradual introduction of toughening agents, nanoparticles, and solid lubricants can improve coating performance. However, the dry friction conditions are quite harsh, and the polymer coating is often rapidly crushed under high loads, making it difficult to support applications under high load and low speed conditions. The friction coefficient of Comparative Example 4 is still higher than 0.10, failing to reach the ultra-low friction level.

[0051] In this invention, a small amount of oil-containing microcapsules are added to the pure epoxy resin in Example 1, which can improve the toughness and wear resistance of the coating. For example... Figure 5 As shown, with Figure 1 Compared to the previous method, the wear marks were slightly improved but still showed significant wear, with a coefficient of friction of 0.172 and a volumetric wear rate of 8.51 × 10⁻⁶. -4 mm³ / N·m. Example 2 further incorporates carboxyl-terminated nitrile butadiene rubber based on Example 1. Under shear, it undergoes stretching, yielding, and crazing, providing elasticity, absorbing energy, and inhibiting coating peeling. For example... Figure 6As shown, the wear marks are significantly shallower and the surface is smoother. Combined with the oil-containing microcapsules, under the high-temperature, high-pressure shearing action at the friction interface, the carboxyl-terminated butadiene-acrylonitrile rubber toughened epoxy coating undergoes oxidation, bonding, and cross-linking through surface carboxyl groups, hydroxyl groups, and double bonds. Simultaneously, MoS2 in the oil-containing microcapsules undergoes edge oxidation, interface anchoring, and lamellar exfoliation. PAO, catalyzed by MoS2 and the active sites of the coating, decomposes to form a carbonaceous lubricating film. These four elements synergistically form an integrated wear-resistant and friction-reducing film of "epoxy-CTBN elastic support layer + MoS2 / carbon composite lubricating layer," achieving high toughness, low friction, and long service life. The coefficient of friction is reduced to 0.156, and the volumetric wear rate is significantly reduced to 4.32 × 10⁻⁶. -5 mm³ / N·m. To further reduce the coefficient of friction and improve wear resistance, nano-silica and polytetrafluoroethylene were introduced, as in Examples 3 and 4. Figure 7 and Figure 8 As shown, the wear marks become narrower. Figure 8 (Example 4) exhibits extremely narrow wear tracks and almost no visible surface damage. Nano-SiO2 serves as a nano-reinforcement and chemical anchoring point. MoS2 and PTFE achieve ultra-low friction through layered slip and fluorocarbon transfer films, respectively. Simultaneously, PAO is rapidly catalytically decomposed by MoS2, SiO2, and epoxy active sites. This five-component system, through interfacial bonding via Si-OC, Mo-O-Si, ester bonds, and fluoride bonds, coupled with catalytic decomposition and oxidative reconstruction, forms an integrated composite boundary lubricating film possessing high toughness, high hardness, ultra-low friction, and high stability, achieving synergistic toughening, synergistic friction reduction, and synergistic wear resistance. In Example 3, the coefficient of friction decreased to 0.071, and the volumetric wear rate decreased to 9.52 × 10⁻⁶. -6 mm³ / N·m; In Example 4, the coefficient of friction was reduced to 0.045, and the volumetric wear rate was reduced to 1.17×10⁻⁶. -7 mm³ / N·m, achieving optimal performance. Furthermore, in Example 5, the wall material was replaced with gum arabic, while the remaining components were the same as in Example 4, such as... Figure 9 As shown, the morphology of the wear marks and Figure 8 Similar to each other, the coefficient of friction is 0.047, and the volumetric wear rate is 1.24 × 10⁻⁶. -7 The ratio of mm³ / N·m is almost identical to that in Example 4, demonstrating that the oil-containing microcapsules prepared by different synthesis methods of this patent all have good effects, and the technical solution has universality.

[0052] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0054] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A self-lubricating polymer coating, characterized in that, Includes the following components by mass percentage: Epoxy resin 20-35%; Hardener 3-10%; Toughening agent 5-10%; Solid lubricant 5-15%; Oil-containing microcapsules 2-8%; Nanoparticles 0.5-3%; Organic solvents 30-60%; Dispersant 0.1-3%; Leveling agent 0.1-3%; The core material of the oil-containing microcapsules is a mixture of polyalphaolefin oil and molybdenum disulfide nanosheets, and the wall material is carbohydrates or proteins.

2. The self-lubricating polymer coating according to claim 1, characterized in that, The transverse dimension of the molybdenum disulfide nanosheets does not exceed 1 μm, the kinematic viscosity of the polyalphaolefin oil at 100℃ is ≤6 mm² / s, and the mass ratio of molybdenum disulfide nanosheets to polyalphaolefin oil in the core material is (1-5):(95-99).

3. The self-lubricating polymer coating according to claim 1, characterized in that, The wall material is a mixture of maltodextrin and OSA-modified starch, or a mixture of maltodextrin and gum arabic, with a mixing mass ratio of 7:

3.

4. The self-lubricating polymer coating according to claim 1, characterized in that, The nanoparticles are at least one of silicon dioxide, aluminum oxide, silicon carbide, or titanium nitride with a particle size of less than 100 nm.

5. The self-lubricating polymer coating according to claim 1, characterized in that, The epoxy resin is phenolic epoxy resin, the toughening agent is carboxyl-terminated nitrile rubber, the solid lubricant is polytetrafluoroethylene, and the curing agent is 4,4'-diaminodiphenyl sulfone.

6. A method for preparing a self-lubricating polymer coating as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Molybdenum disulfide nanosheets were dispersed in polyα-olefin oil and subjected to ultrasonic treatment to obtain oil phase A; (2) Dissolve the wall material and nonionic surfactant in deionized water to obtain aqueous phase A; (3) The oil phase A is dripped into the aqueous phase A under shear conditions to emulsify it and obtain a crude emulsion; (4) The crude emulsion is subjected to high-pressure homogenization to obtain a stable oil-in-water emulsion; (5) Spray dry the oil-in-water emulsion, collect the powder, and vacuum dry it to obtain oil-containing microcapsules; (6) Dissolve epoxy resin and toughening agent in organic solvent, add dispersant and leveling agent, mix well to obtain solution B; (7) Add nanoparticles, oil-containing microcapsules obtained in step (5), curing agent and solid lubricant to solution B, grind and mix them to obtain the self-lubricating polymer coating.

7. The preparation method according to claim 6, characterized in that, The pressure of high-pressure homogenization in step (4) is 30-50 MPa, and the cycle is repeated 2-5 times.

8. The preparation method according to claim 6, characterized in that, The inlet temperature of the spray dryer in step (5) is 150-180℃ and the outlet temperature is 90-100℃.

9. The preparation method according to claim 6, characterized in that, The grinding speed in step (7) is 1000-2000 rpm and the time is 1-6 h.

10. The application of a self-lubricating polymer coating as described in any one of claims 1 to 5 on the surface of an automotive seatbelt locking structure.

Images