Organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating and preparation method thereof

Abstract

The present invention relates to an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating and a preparation method thereof, which is composed of an epoxy resin, an epoxy hyperbranched polysiloxane and a polyamic acid. Wherein, HSiEp is a hyperbranched topological structure in which the main chain segment is Si-O-C prepared by a "one-pot method", and PAA is a solid powder prepared by a solvent-free ball milling method according to the principle of tribochemistry, which has the advantages of being simple and easy to operate. By introducing HSiEp and PAA into EP to form a semi-interpenetrating polymer network structure, the compatibility of PAA and EP is increased by using HSiEp containing a large number of active groups, and the strength, toughness and heat resistance of EP can also be improved by using its "flexible" Si-O-C segment and the aromatic ether segment and "rigid" benzene ring structure of PAA. The organic-inorganic hybrid supramolecular epoxy self-lubricating coating prepared by the present invention not only has excellent mechanical properties, but also has good film-forming property, heat resistance and medium resistance, and therefore can be applied to self-lubricating sealing coatings of contact sealing parts in the fields of aviation, aerospace, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer composite coatings and relates to an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating and a preparation method thereof. Background Art

[0002] Epoxy resin (EP) is widely used as a coating in aviation, aerospace, marine, and automotive applications due to its excellent adhesion, mechanical properties, chemical stability, low shrinkage, easy processing, and low cost. However, unmodified epoxy resins typically suffer from poor toughness, poor high-temperature resistance, low friction and wear resistance, and poor film-forming properties. Polyimide (PI) has some complementary properties to EP due to its high toughness, high- and low-temperature resistance, good film-forming properties, and excellent friction and wear resistance. However, PI and EP have poor compatibility and complex processing.

[0003] Polyamic acid (PAA), as a precursor to polyimide (PI), is a promising candidate for modified polyimide (EP). However, conventional PAA synthesis methods require large amounts of high-boiling-point aprotic polar solvents, and the product is difficult to store and prone to hydrolysis. Ball milling, based on the principles of tribochemistry, utilizes mechanical energy to induce chemical reactions or changes in the material's organization, structure, and properties, thereby producing new materials. This method is not only low-cost and simple to operate, but also highly efficient, highly productive, and amenable to large-scale production, providing a new approach for the preparation of PAA solid powders.

[0004] On the other hand, hyperbranched polysiloxanes (HBPSi), with their highly branched topology, multiple terminal reactive groups, low viscosity, and low surface energy, hold promise for enhancing the compatibility between PAA and EP while simultaneously improving the mechanical, tribological, and thermal properties of epoxy composites. However, conventionally prepared HBPSi often utilizes a hyperbranched topology with Si-O-Si as the primary chain segment. This method is not only complex and costly, but also prone to gelation and limited structural design. Our group utilized a simple one-pot method to prepare HBPSi with Si-OC as the primary chain segment. This HBPSi not only enhances the strength and toughness of the resin matrix through the "rigid-flexible" effect of the chain segments, but also utilizes its reactive groups (such as epoxy and hydroxyl groups) to enhance interfacial bonding with the resin matrix. Furthermore, structural design has enabled the preparation of hyperbranched modifiers with multifunctional properties, such as flame retardancy, dielectric properties, and friction and anti-wear properties. Furthermore, this method offers great potential for industrial production due to its low cost, simple process, and resistance to gelation. Therefore, designing and synthesizing a new type of HBPSi to strengthen PAA-modified EP will be a new breakthrough in the preparation of high-performance epoxy self-lubricating sealing coatings.

[0005] Based on this, this study used solvent-free ball milling and one-pot method to prepare PAA solid powder and epoxy hyperbranched polysiloxane (HSiEp), respectively, and used HSiEp to enhance the mechanical properties, friction properties and thermal properties of PAA / EP coating, thereby providing important technical support for the research and development of new high-performance epoxy self-lubricating sealing coatings. Summary of the Invention

[0006] Technical problems to be solved

[0007] To overcome the shortcomings of the prior art, the present invention proposes an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating and a preparation method, which addresses the problems of pure EP, such as poor toughness, poor high-temperature resistance, poor friction reduction and wear resistance, and poor film-forming properties. Furthermore, the traditional method requires a large amount of high-boiling-point aprotic polar solvents when synthesizing PAA, and the product is difficult to preserve and easily hydrolyzed.

[0008] The present invention proposes to prepare PAA solid powder through a simple, efficient, and environmentally friendly solvent-free ball milling method, and uses HSiEp to enhance the mechanical, frictional, and thermal properties of the PAA / EP coating, thereby providing a new approach for the research and development of epoxy self-lubricating sealing coatings for high-tech fields such as aviation and aerospace.

[0009] Technical Solution

[0010] An organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating, characterized in that the components, calculated by mass fraction, are: 1-100 parts of epoxy E-51, 0.5-5 parts of polyamic acid PAA solid powder, 2-12 parts of epoxy hyperbranched polysiloxane HSiEp and 10-60 parts of curing agent; the HSiEp has a hyperbranched topological structure with a main chain segment of Si-OC, and is introduced into the EP together with the PAA to form a semi-interpenetrating polymer network structure.

[0011] The curing agent includes 4,4'-diaminodiphenyl sulfone DDS, 4,4'-diaminodiphenylmethane DDM, methyltetrahydrophthalic anhydride MTHPA or triethylenetetramine TETA.

[0012] The structure of the HSiEp having a hyperbranched topological structure with a main chain segment of Si-OC is:

[0013]

[0014] The HSiEp having a hyperbranched topological structure with a main chain segment of Si-OC is prepared by a "one-pot method".

[0015] A method for preparing the organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating is characterized by the following steps:

[0016] Add 20-60 parts of high-boiling-point aprotic polar solvent to 0.5-5 parts of PAA solid powder, and after it dissolves, add 1-100 parts of epoxy E-51;

[0017] The mixture is reacted at 70-80° C. for 3-6 hours, and then 2-12 parts of HSiEp are added and stirred for reaction for 10-20 minutes. Then, 10-60 parts of a curing agent are added and stirred and dissolved to obtain a HSiEp / PAA / EP coating, i.e., an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating.

[0018] The HSiEp / PAA / EP coating is evenly sprayed on the metal surface by spraying at room temperature, and cured by gradient temperature increase. The curing process is as follows: curing at 130-150°C for 120-180 min, curing at 150-180°C for 180-240 min, and curing at 180-230°C for 120-180 min. After curing, it is naturally cooled to room temperature to obtain an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating.

[0019] The PAA solid powder is prepared by adding dianhydride and diamine in a molar ratio of 1:1 to 1:2 in a ball mill, weighing ball mill beads at a ball-to-material mass ratio of 1:1 to 5:1, stirring and uniformly mixing the raw materials and the ball mill beads, and finally placing the ball mill in a planetary ball mill at a speed of 400 to 600 rpm for 6 to 10 hours to obtain a yellow powdery solid, namely the PAA solid powder.

[0020] The dianhydride includes pyromellitic dianhydride, benzophenone dianhydride and hexafluorodianhydride; the diamine includes 4,4'-diaminodiphenyl ether, p-phenylenediamine and 4,4'-diaminodiphenyl sulfide.

[0021] The preparation method of HSiEp is as follows: A-1871 and diol are weighed in a molar ratio of 1:1.1 to 1:2, the temperature of the mixed system is raised to 110 to 140° C. under nitrogen protection until distillate flows out, and the mixture is kept for 3 to 6 hours to obtain a light yellow viscous liquid, namely HSiEp.

[0022] The diols include 1,3-propylene glycol, 1,4-butanediol and 1,5-pentanediol.

[0023] The high boiling point aprotic polar solvent includes N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAc or N-methylpyrrolidone NMP.

[0024] Beneficial effects

[0025] The present invention proposes an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating and a preparation method thereof. The coating is composed of an epoxy resin (EP), an epoxy-based hyperbranched polysiloxane (HSiEp), and polyamic acid (PAA). HSiEp is a hyperbranched topological structure with a Si-OC main chain segment prepared by a "one-pot method," while PAA is a solid powder prepared by a solvent-free ball milling method based on the principles of tribochemistry. This method does not require the use of large amounts of high-boiling-point polar aprotic solvents, is simple and easy to operate, and the product has the advantages of being easy to store and not prone to hydrolysis. By introducing HSiEp and PAA into EP to form a semi-interpenetrating polymer network structure, not only can the HSiEp containing a large number of active groups be utilized to increase the compatibility of PAA and EP, but its "flexible" Si-OC segment and the aromatic ether segment and "rigid" benzene ring structure of PAA can also be utilized to improve the strength, toughness, and heat resistance of EP. At the same time, due to its low surface energy, HSiEp also provides excellent friction reduction and anti-wear properties, thereby producing an organic-inorganic hybrid supramolecular epoxy self-lubricating coating with excellent overall performance. The organic-inorganic hybrid supramolecular epoxy self-lubricating coating prepared by the present invention not only exhibits excellent mechanical properties, but also possesses good film-forming properties, heat resistance, and media resistance. Therefore, it can be used as a self-lubricating sealing coating for contact sealing components in fields such as aviation and aerospace.

[0026] The present invention proposes an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating and its preparation method. PAA solid powder and HSiEp are prepared respectively by a simple and easy-to-operate solvent-free ball milling method and a "one-pot" method. HSiEp is then used to enhance the mechanical, frictional, and thermal properties of the PAA / EP coating.

[0027] Specifically, the introduction of HSiEp enhances the compatibility between PAA and EP, allowing the "flexible" aromatic ether segments and "rigid" benzene ring structure in PAA to not only enhance the strength and toughness of the epoxy composite coating but also significantly improve its thermal stability. Furthermore, the bond angle of the Si-OC bond in HSiEp lies between that of COC and Si-O-Si, resulting in the Si-OC segments possessing both the "rigidity" of COC segments and the "flexibility" of Si-O-Si segments. Therefore, the "rigidity" of HSiEp allows its aggregates, driven by intermolecular forces such as hydrogen bonds, to absorb and dissipate more impact energy within the semi-IPP network, thereby enhancing the strength of the epoxy composite coating. Furthermore, its "flexibility" allows the highly branched topology of HSiEp to readily form free volume within the epoxy matrix. According to the Simha-Boyer relationship, free volume contributes to toughness, ultimately further enhancing the strength and toughness of the HSiEp / PAA / EP composite coating. In addition, the adhesion between the epoxy composite coating and the metal substrate is not only due to the physical mechanical interlocking force, but also due to the hydrogen bonds, electrostatic forces and molecular bonds formed between the hydroxyl groups, epoxy groups and amino groups in HSiEp and PAA and the surface of the metal substrate, which further improves the adhesion of the epoxy composite coating. On the other hand, since HSiEp has low surface properties, it helps to form a friction film during the friction process and blocks the direct friction between the grinding ring and the epoxy composite coating. In addition, the excellent thermal stability of the epoxy composite coating enables the friction film to maintain good continuity and stability during a long period of friction and wear, so that the epoxy composite coating has excellent friction reduction and anti-wear properties. Therefore, the present invention also further provides important technical support for the research and development of epoxy self-lubricating sealing coatings in high-tech fields such as aviation and aerospace. The mechanism of HSiEp and PAA enhancing the mechanical properties and friction properties of modified epoxy self-lubricating coatings is as follows Figure 4 shown. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 :Infrared spectra of PMDA, ODA and PAA

[0029] As can be seen from the figure, 3321cm -1 The multiple absorption peaks appearing above and 1609cm -1 The medium-intensity absorption peaks that appear are the -NH stretching vibration peak and bending vibration peak of the primary amine in ODA, while only 3384 cm -1 and 3358cm -1 The primary amine-NH stretching vibration peak at 1609 cm -1The primary amine-NH bending vibration is also observed, and its peak intensity is significantly weakened. At the same time, the infrared spectrum of PAA is found at 1771 cm -1 The peak intensity of the anhydride C=O symmetric stretching vibration peak at 3500-2500 cm is also significantly weaker than that of PMDA. The above analysis preliminarily indicates that PMDA reacts with ODA and consumes the functional groups required for the reaction. Further observation of the infrared spectrum of PAA also reveals that the peak at 3500-2500 cm -1 The broad and scattered absorption peak is the OH stretching vibration peak of the carboxyl group, while the C=O stretching vibration peak of the carboxyl group is located at 1716cm -1 The C=O stretching vibration peak and NH bending vibration peak of imide are located at 1653 cm -1 and 1542cm -1 At the same time, 1013cm -1 The COC stretching vibration peak of aromatic ether can also be observed. Comprehensive analysis shows that PAA solid powder was successfully prepared by solvent-free ball milling.

[0030] Figure 2 :Infrared spectra of A-1871, BDO, HSiEp, distillate and standard ethanol

[0031] Figure 2 You can see 3321cm -1 is the -OH stretching vibration peak of BDO. A-1871 has no -OH absorption peak in this region, but HSiEp has an absorption peak at 3425 cm -1 The -OH absorption peak is broad and red-shifted, which is due to the formation of intermolecular hydrogen bonds by HSiEp, resulting in the red-shift of the -OH absorption peak. At the same time, a peak at 1097 cm-1 can be observed in the A-1871 spectrum. -1 The Si-OC stretching vibration peak of HSiEp is red-shifted to 1097 cm -1 , and 795cm -1 The Si-C stretching vibration peak at 100 nm was also detected in the HSiEp spectrum. Furthermore, infrared characterization of the distillate and standard ethanol revealed that their infrared spectra remained essentially identical. This comprehensive analysis confirmed the successful preparation of HSiEp.

[0032] Figure 3 :Friction properties of HSiEp / PAA / EP self-lubricating coatings

[0033] Figure 3As can be seen in the figure, with the introduction of HSiEp and PAA, the friction coefficient and wear volume of the HSiEp / PAA / EP self-lubricating coating both decrease first and then increase. Sample 3 achieves a friction coefficient of approximately 0.23, at which point its wear volume reaches its minimum. This is likely due to the low surface energy of HSiEp, which facilitates the formation of a tribofilm and effectively reduces friction. Furthermore, the large number of rigid benzene rings in PAA enhances the thermal stability of the coating and tribofilm, thereby improving the coating's wear resistance.

[0034] Figure 4 :Mechanism of mechanical and tribological properties of HSiEp and PAA-enhanced modified epoxy self-lubricating coatings DETAILED DESCRIPTION

[0035] The present invention will now be further described with reference to the embodiments and accompanying drawings:

[0036] Step 1: Prepare PAA solid powder by solvent-free ball milling. First, weigh dianhydrides and diamines in a molar ratio of 1:1 to 1:2 into a ball mill. Then, weigh ball mill beads at a ball-to-material ratio of 1:1 to 5:1 and stir to mix thoroughly. Finally, place the mill in a planetary ball mill and mill at 400-600 rpm for 6-10 hours to obtain a yellow powdery solid, PAA. The dianhydrides are pyromellitic dianhydride, benzophenone dianhydride, and hexafluorodianhydride; the diamines are 4,4'-diaminodiphenyl ether, p-phenylenediamine, and 4,4'-diaminodiphenyl sulfide.

[0037] Step 2: Prepare HSiEp using a one-pot method. First, mix 3-(2,3-epoxypropyloxy)propyltriethoxysilane (A-1871) with a diol in a molar ratio of 1:1.1 to 1:2. Under nitrogen, heat the mixture to 110-140°C until distillate flows out. Maintain this temperature for 3-6 hours to obtain HSiEp. The diols are 1,3-propylene glycol, 1,4-butanediol, and 1,5-pentanediol.

[0038] Step 3: Preparation of HSiEp / PAA / EP coating: Weigh (0.5-5) parts by mass of PAA solid powder into a beaker, add (20-60) parts of a high-boiling-point aprotic polar solvent, and after dissolution, add (1-100) parts of epoxy E-51 and react at (70-80)°C for (3-6) hours. Then, add (2-12) parts of HSiEp and stir for (10-20) minutes. Then, add (10-60) parts of curing agent and stir to dissolve to obtain the HSiEp / PAA / EP coating. The high-boiling-point aprotic polar solvent is: N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP); the curing agent is: 4,4'-diaminodiphenyl sulfone (DDS), 4,4'-diaminodiphenylmethane (DDM), methyltetrahydrophthalic anhydride (MTHPA) or triethylenetetramine (TETA).

[0039] Step 4: Preparation of the HSiEp / PAA / EP self-lubricating coating. The HSiEp / PAA / EP coating was evenly sprayed onto the tinplate surface at room temperature and cured by gradient temperature increase. The curing process was as follows: curing at (130-150)°C for (120-180) min, curing at (150-180)°C for (180-240) min, and curing at (180-230)°C for (120-180) min. After curing, the coating was naturally cooled to room temperature to obtain an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating.

[0040] Example 1

[0041] (1) Preparation of PAA by solvent-free ball milling

[0042] Dianhydride and diamine were weighed in a molar ratio of 1:1.1 in a ball mill jar. Then, ball mill beads were weighed in a ball-to-material mass ratio of 2:1 and the three were stirred and mixed evenly. Finally, the ball mill jar was placed in a planetary ball mill and ball milled at 560 rpm for 10 h to obtain a yellow powdery solid, namely PAA.

[0043] (2) One-pot preparation of HSiEp

[0044] A-1871 and 1,4-butanediol were weighed in a three-necked flask at a molar ratio of 1:2. Under nitrogen, the temperature of the mixture was raised to 120°C until distillate flowed out. The distillation temperature was recorded. After the distillation temperature dropped, the temperature was continued to be raised to 130°C and maintained for 3 h to obtain a light yellow viscous liquid, which was HSiEp.

[0045] (3) Preparation of HSiEp / PAA / EP coating

[0046] Weigh 0.75 parts of PAA solid powder into a beaker, add 30 parts of DMAc, and after it dissolves, add 100 parts of epoxy E-51 and react at 75°C for 3 hours. Then add 6 parts of HSiEp and stir to react for 10 minutes. Then add 30 parts of DDS and stir to dissolve to obtain HSiEp / PAA / EP coating.

[0047] (4) Preparation of HSiEp / PAA / EP self-lubricating coating

[0048] The HSiEp / PAA / EP coating was evenly sprayed on the tinplate surface by spraying at room temperature, and then cured by gradient temperature increase. The curing process was as follows: curing at 130°C for 120 min, curing at 170°C for 180 min, and curing at 230°C for 120 min. After curing, it was naturally cooled to room temperature to obtain an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating.

[0049] Example 2

[0050] (1) Preparation of PAA by solvent-free ball milling is the same as in Example 1

[0051] (2) Preparation of HSiEp by "one-pot method" is the same as in Example 1

[0052] (3) Preparation of HSiEp / PAA / EP coating

[0053] Weigh 1.5 parts of PAA solid powder into a beaker, add 30 parts of DMAc, and after it dissolves, add 100 parts of epoxy E-51 and react at 75°C for 3 hours. Then add 6 parts of HSiEp and stir to react for 10 minutes. Then add 30 parts of DDS and stir to dissolve to obtain HSiEp / PAA / EP coating.

[0054] (4) Preparation of HSiEp / PAA / EP self-lubricating coating is the same as in Example 1

[0055] Example 3

[0056] (1) Preparation of PAA by solvent-free ball milling is the same as in Example 1

[0057] (2) Preparation of HSiEp by "one-pot method" is the same as in Example 1

[0058] (3) Preparation of HSiEp / PAA / EP coating

[0059] Weigh 2.25 parts of PAA solid powder into a beaker, add 30 parts of DMAc, and after it dissolves, add 100 parts of epoxy E-51 and react at 75°C for 3 hours. Then add 6 parts of HSiEp and stir to react for 10 minutes. Then add 30 parts of DDS and stir to dissolve to obtain HSiEp / PAA / EP coating.

[0060] (4) Preparation of HSiEp / PAA / EP self-lubricating coating is the same as in Example 1

[0061] Example 4

[0062] (1) Preparation of PAA by solvent-free ball milling is the same as in Example 1

[0063] (2) Preparation of HSiEp by "one-pot method" is the same as in Example 1

[0064] (3) Preparation of HSiEp / PAA / EP coating

[0065] Weigh 3 parts of PAA solid powder into a beaker, add 30 parts of DMAc, and after it dissolves, add 100 parts of epoxy E-51 and react at 75°C for 3 hours. Then add 6 parts of HSiEp and stir to react for 10 minutes. Then add 30 parts of DDS and stir to dissolve to obtain HSiEp / PAA / EP coating.

[0066] (4) Preparation of HSiEp / PAA / EP self-lubricating coating is the same as in Example 1

[0067] Example 5

[0068] (1) Preparation of PAA by solvent-free ball milling is the same as in Example 1

[0069] (2) Preparation of HSiEp by "one-pot method" is the same as in Example 1

[0070] (3) Preparation of HSiEp / PAA / EP coating

[0071] Weigh 1.5 parts of PAA solid powder into a beaker, add 30 parts of DMAc, and after it dissolves, add 100 parts of epoxy E-51 and react at 75°C for 3 hours. Then add 2 parts of HSiEp and stir to react for 10 minutes. Then add 30 parts of DDS and stir to dissolve to obtain HSiEp / PAA / EP coating.

[0072] (4) Preparation of HSiEp / PAA / EP self-lubricating coating is the same as in Example 1

[0073] Example 6

[0074] (1) Preparation of PAA by solvent-free ball milling is the same as in Example 1

[0075] (2) Preparation of HSiEp by "one-pot method" is the same as in Example 1

[0076] (3) Preparation of HSiEp / PAA / EP coating

[0077] Weigh 1.5 parts of PAA solid powder into a beaker, add 30 parts of DMAc, and after it dissolves, add 100 parts of epoxy E-51 and react at 75°C for 3 hours. Then add 4 parts of HSiEp and stir to react for 10 minutes. Then add 30 parts of DDS and stir to dissolve to obtain HSiEp / PAA / EP coating.

[0078] (4) Preparation of HSiEp / PAA / EP self-lubricating coating is the same as in Example 1

[0079] Example 7

[0080] (1) Preparation of PAA by solvent-free ball milling is the same as in Example 1

[0081] (2) Preparation of HSiEp by "one-pot method" is the same as in Example 1

[0082] (3) Preparation of HSiEp / PAA / EP coating

[0083] Weigh 1.5 parts of PAA solid powder into a beaker, add 30 parts of DMAc, and after it dissolves, add 100 parts of epoxy E-51 and react at 75°C for 3 hours. Then add 8 parts of HSiEp and stir to react for 10 minutes. Then add 30 parts of DDS and stir to dissolve to obtain HSiEp / PAA / EP coating.

[0084] (4) Preparation of HSiEp / PAA / EP self-lubricating coating is the same as in Example 1

[0085] Example 8

[0086] (1) Preparation of PAA by solvent-free ball milling is the same as in Example 1

[0087] (2) Preparation of HSiEp by "one-pot method" is the same as in Example 1

[0088] (3) Preparation of HSiEp / PAA / EP coating

[0089] Weigh 1.5 parts of PAA solid powder into a beaker, add 30 parts of DMAc, and after it dissolves, add 100 parts of epoxy E-51 and react at 75°C for 3 hours. Then add 10 parts of HSiEp and stir to react for 10 minutes. Then add 30 parts of DDS and stir to dissolve to obtain HSiEp / PAA / EP coating.

[0090] (4) Preparation of HSiEp / PAA / EP self-lubricating coating is the same as in Example 1

[0091] The performance test and analysis of the HSiEp / PAA / EP self-lubricating coating prepared accordingly in the examples are shown in the accompanying drawings of the specification.

[0092] This invention proposes an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating and its preparation method. PAA solid powder and epoxy hyperbranched polysiloxane (HSiEp) are prepared using solvent-free ball milling and a one-pot process, respectively. HSiEp is used to enhance the mechanical, tribological, and thermal properties of the PAA / EP coating. This provides a new solution and approach to addressing the challenges of epoxy self-lubricating sealing coatings in high-tech fields such as aviation and aerospace. Furthermore, this preparation method is simple, cost-effective, and amenable to industrial production, thus offering significant potential for application in civilian applications.

[0093] Table 1 shows the thickness, adhesion, impact strength, and flexibility of the HSiEp / PAA / EP self-lubricating coating. It can be seen that the pure EP coating is relatively thick, reaching 55.73 μm. This is due to the poor film-forming properties of pure EP, resulting in a thicker coating. Furthermore, the pure EP coating has poor adhesion, impact strength, and flexibility, reaching levels 3, 5 cm, and 2.0 mm, respectively. However, with the introduction of HSiEp and PAA, the film-forming properties of the HSiEp / PAA / EP self-lubricating coating are enhanced, maintaining a coating thickness of 25 ± 5 μm. Its adhesion, impact strength, and flexibility are significantly improved, reaching levels 1, 50 cm, and 0.5 mm, respectively.

[0094] Table 1 Mechanical properties of HSiEp / PAA / EP self-lubricating coating

[0095]

[0096] The above content is a further detailed description of the present invention in combination with specific embodiments. It cannot be considered that the specific implementation methods of the present invention are limited to these. Although the embodiments of the present invention are not disclosed, they can be foreseen and determined by those skilled in the art.

Claims

1. An organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating, characterized in that The components, calculated by mass fraction, are: 1-100 parts of epoxy E-51, 0.5-5 parts of polyamic acid PAA solid powder, 2-12 parts of epoxy hyperbranched polysiloxane HSiEp, and 10-60 parts of curing agent; the HSiEp has a hyperbranched topological structure with a main chain segment of Si-OC, and is introduced into the EP together with the PAA to form a semi-interpenetrating polymer network structure; The curing agent includes 4,4'-diaminodiphenyl sulfone DDS, 4,4'-diaminodiphenylmethane DDM, methyltetrahydrophthalic anhydride MTHPA or triethylenetetramine TETA; The structure of the HSiEp having a hyperbranched topological structure with a main chain segment of Si-OC is: 。 2. The organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating according to claim 1, characterized in that: The HSiEp having a hyperbranched topological structure with a main chain segment of Si-OC is prepared by a "one-pot method".

3. A method for preparing the organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating according to claim 1 or 2, characterized in that Here are the steps: Add 20-60 parts of a high-boiling-point aprotic polar solvent to 0.5-5 parts of PAA solid powder, wait for it to dissolve, and then add 1-100 parts of epoxy E-51; The mixture is reacted at 70-80°C for 3-6 hours, and then 2-12 parts of HSiEp are added and stirred for reaction for 10-20 minutes. Then, 10-60 parts of a curing agent are added and stirred to dissolve to obtain a HSiEp / PAA / EP coating, i.e., an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating. The HSiEp / PAA / EP coating was evenly sprayed onto the metal surface by spraying at room temperature and cured by gradient temperature increase. The curing process was as follows: curing at 130-150°C for 120-180 min, curing at 150-180°C for 180-240 min, and curing at 180-230°C for 120-180 min. After curing, the coating was naturally cooled to room temperature to obtain an organic-inorganic hybrid supramolecular epoxy self-lubricating sealing coating.

4. The method according to claim 3, wherein: The PAA solid powder is prepared by adding dianhydride and diamine in a molar ratio of 1:1 to 1:2 in a ball mill, weighing ball mill beads at a ball-to-material mass ratio of 1:1 to 5:1, stirring and uniformly mixing the raw materials and the ball mill beads, and finally placing the ball mill in a planetary ball mill at a speed of 400 to 600 rpm for 6 to 10 hours to obtain a yellow powdery solid, namely the PAA solid powder.

5. The method according to claim 4, characterized in that: The dianhydrides include pyromellitic dianhydride, benzophenone dianhydride and hexafluorodianhydride; the diamines include 4,4'-diaminodiphenyl ether, p-phenylenediamine and 4,4'-diaminodiphenyl sulfide.

6. The method according to claim 3, wherein: The preparation method of HSiEp is as follows: A-1871 and diol are weighed in a molar ratio of 1:1.1-1:2, the temperature of the mixed system is raised to 110-140° C. under nitrogen protection until distillate flows out, and the mixture is kept for 3-6 hours to obtain a light yellow viscous liquid, namely HSiEp.

7. The method according to claim 6, characterized in that: The diols include 1,3-propylene glycol, 1,4-butanediol, and 1,5-pentanediol.

8. The method according to claim 3, wherein: The high boiling point aprotic polar solvent includes N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAc or N-methylpyrrolidone NMP.

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