Hydrogen energy equipment rubber sealing hydrogen-resistant wear-resistant composite coating and preparation method thereof

Abstract

The application discloses a rubber sealing hydrogen-resistant wear-resistant composite coating for hydrogen energy equipment and a preparation method thereof. The method comprises the following steps: firstly, MXene powder is obtained by etching a MAX phase; then, under the action of KH550, a modified epoxy resin is formed by modifying an epoxy resin EP with hydroxyl-terminated polydimethylsiloxane PDMS-OH; subsequently, a composite coating is formed by adding MXene dispersion liquid dispersed in a curing agent into the modified epoxy resin; and finally, a modified epoxy resin composite coating containing MXene is prepared on the surface of pretreated rubber by dip coating. The method has simple preparation process, high bonding strength of the composite coating and base, and can realize the dual protection of hydrogen resistance and wear reduction of the rubber base material, and can be used for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of material surface treatment technology, and in particular to a hydrogen-resistant and wear-resistant composite coating for rubber sealing of hydrogen energy equipment and its preparation method. Background Technology

[0002] Due to its high elasticity and malleability, rubber's surface coatings are required to remain intact, crack-free, and without peeling even under significant deformation. Currently, hydrogen barrier coatings are mostly reported on rigid plastics (such as polyethylene terephthalate and polyamide), with unknown bonding strength, while reports on soft rubber surfaces are extremely rare. Zhou et al. (Functionalized graphite nanosheet / organosilicon composite coatings with soft-hard structures: Excellent wear resistance and hydrogen barrier properties) prepared a graphite nanosheet / organosilicon composite coating on rubber surfaces using the sol-gel method. This coating exhibits certain hydrogen barrier and wear-resistant properties; however, the inevitable cracking during the curing process limits its hydrogen barrier and wear-resistant properties.

[0003] Currently, some research has been conducted on anti-wear and friction-reducing coatings for rubber surfaces. Bai et al. (Achieving a high adhesion and excellent wear resistance diamond-like carbon film coated on NBR rubber by Ar plasma pretreatment) deposited a diamond-like carbon (DLC) coating on the surface of nitrile rubber using plasma chemical vapor deposition, achieving a friction coefficient as low as approximately 0.2. Liu et al. (Effect of bias voltage on the tribological and sealing properties of rubber seals modified by DLC films) deposited a DLC coating on the rubber surface using DC magnetron sputtering, achieving the lowest friction coefficient at a bias voltage of -100V. However, the above coating preparation technologies have high barriers to entry, are expensive, and require large-scale equipment, making them unsuitable for large-scale industrial production.

[0004] In recent years, the application of two-dimensional nanomaterials in hydrogen barrier and wear resistance has attracted widespread attention. Among them, MXene, due to its unique high specific surface area and layered shear properties, has become a very promising barrier and lubrication coating material. In the research of MXene wear-resistant coatings, An et al. (Preparation of MXene / EP coating for promising anticorrosion and superlow friction properties) prepared an MXene epoxy resin composite coating and sprayed it on the surface of a steel substrate. The coating showed low friction coefficient and wear rate, but the coating was brittle and prone to fracture, and its bonding strength on soft rubber substrates was unknown.

[0005] Patent CN109880290A discloses a method for preparing epoxy resin / MXene composite material. This method incorporates MXene into epoxy resin, which effectively improves the tensile fracture strength of epoxy resin / MXene composite material, but the composite material is brittle.

[0006] Zhao et al. (Preparation and properties of polydimethylsiloxane-modified epoxy resins) used silane coupling agents as compatibilizers to modify epoxy resin (EP) with hydroxyl-terminated polydimethylsiloxane (PDMS-OH), finding that the copolymer had good compatibility and that the PDMS-OH-modified EP had higher impact strength. Verma et al. (A facile preparation of epoxy-polydimethylsiloxane (EP-PDMS) polymer coatings for marine applications) developed an EP / PDMS-OH composite coating for ship surfaces, finding that the addition of 30 wt% PDMS-OH increased the elastic modulus and adhesive strength of the coating. However, although the toughness of these coatings was enhanced to some extent, the formation of pores and cracks during thermosetting was still unavoidable, which was detrimental to the overall performance of the coating.

[0007] In addition, traditional research has directly incorporated MXene into epoxy resin. However, due to the poor compatibility between MXene and epoxy resin, MXene has poor dispersibility and agglomeration, which makes it difficult to enhance the density of the coating and limits its further application in anti-wear and friction-reducing coatings.

[0008] There is an urgent need for a composite coating that has a simple preparation process, higher density, stronger toughness, lower coefficient of friction and wear rate, and can effectively reduce the hydrogen permeability of rubber substrates. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a hydrogen-barrier and wear-resistant composite coating for rubber sealing in hydrogen energy equipment and its preparation method. This method employs a curing agent to pre-disperse MXene, enhancing its compatibility and dispersibility in the EP / PDMS-OH system and compensating for defects in the coating curing process. Under the action of a silane coupling agent, soft PDMS-OH chains are introduced into the rigid EP, imparting a certain degree of toughness to the epoxy resin, enabling it to remain smooth, intact, and without peeling even under large deformations of the rubber substrate. Simultaneously, utilizing the high specific surface area and layered shear properties of MXene, the overall structural density and bonding strength of the composite coating are improved, resulting in excellent barrier and self-lubricating properties, significantly reducing the hydrogen permeability, friction coefficient, and wear rate of the rubber substrate.

[0010] This invention provides a hydrogen-blocking and wear-resistant composite coating for rubber seals in hydrogen energy equipment and its preparation method, comprising the following steps:

[0011] Step 1: Treat the rubber substrate with sulfuric acid solution and silane coupling agent solution respectively;

[0012] Step 2: Ti3AlC2 is etched using a mixture of HCl and LiF, and the etched product is washed with deionized water. The etched product is intercalated with LiCl solution, and the intercalated solution is washed with deionized water. MXene is obtained by centrifugation and freeze-drying. The MXene powder is stirred and ultrasonically dispersed in the curing agent MTHPA to form an MTHPA-MXene dispersion.

[0013] Step 3: Add hydroxyl-terminated polydimethylsiloxane PDMS-OH to epoxy resin EP, and form a modified epoxy resin under the action of silane coupling agent;

[0014] Step 4: Add the MTHPA-MXene dispersion and accelerator to the modified epoxy resin, and sonicate while stirring to form a uniformly mixed composite coating. Perform vacuum defoaming treatment on the composite coating. Immerse the pretreated rubber substrate into the composite coating, pull it out, and heat and cure it in a vacuum drying oven.

[0015] Furthermore, the dimensions of the rubber substrate are...

[0016] Furthermore, MXene is made by etching Ti3AlC2.

[0017] Furthermore, the silane coupling agent is KH550; EP is E51 type resin.

[0018] Furthermore, PDMS-OH is a monohydroxy-terminated polydimethylsiloxane; the curing agent is methyltetrahydrophthalic anhydride (MTHPA); and the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0019] Furthermore, step 1 specifically includes the following steps:

[0020] Step S11: The rubber sample is ultrasonically washed with anhydrous ethanol and deionized water at an ultrasonic frequency of 33-35 kHz and a power of 300-500 W, and then dried at room temperature.

[0021] Step S12: The dried rubber sample from the previous step is first dispersed and soaked in a 5-10 mol / L sulfuric acid solution for 12-24 hours. Then, the soaked rubber sample is washed with 3% ammonia and deionized water and dried at room temperature.

[0022] Step S13: Disperse and immerse the dried rubber sample from the previous step in KH550 solution. The volume ratio of the solution is anhydrous ethanol:KH550:deionized water = 90-94:5-8:1-2. The immersion time is 12-24 hours. Then, wash the immersed rubber sample with deionized water and dry it at room temperature.

[0023] Furthermore, step 2 specifically includes the following steps:

[0024] Step S21: Add 4–6 g of LiF to 80–90 mL of 9–10 mol / L HCl and stir at room temperature to form an HF etching solution. Then, add 4–5 g of Ti3AlC2 powder to the etching solution and stir at room temperature for 24–48 h. Wash the reaction solution repeatedly with deionized water until the pH is greater than or equal to 6.

[0025] Step S22: Add 20-22 g / L of LiCl aqueous solution to the solution and stir at room temperature for 18-24 h; after stirring, wash the solution three times with deionized water; collect the supernatant by centrifugation at 3500-4000 rpm, and freeze-dry to obtain solid MXene powder;

[0026] In step S23, 0.2–0.4 g of MXene powder is stirred and ultrasonically dispersed into 80–85 g of MTHPA. The stirring time is 0.5–1 h, the ultrasonic time is 1–3 h, and the ultrasonic frequency and power are 33–35 kHz and 300–500 W, respectively, to obtain MTHPA-MXene dispersion.

[0027] Furthermore, step 3 specifically includes the following steps:

[0028] Step S31: 100-110g of EP is softened at 80-90℃ for 30-60min to obtain sufficient fluidity. Then, it is premixed with 20-25g of PDMS-OH for 10-20min. 5-10g of KH550 and 0.3-1g of dibutyltin dilaurate are added, and the mixture is stirred at 80-90℃ for 6-8h to form a modified epoxy resin.

[0029] Furthermore, step 4 specifically includes the following steps:

[0030] Step S41: Slowly add the MTHPA-MXene dispersion to the modified epoxy resin and add 1-3g of accelerator. Stir and sonicate at a speed of 2000-2500rpm, with an ultrasonic frequency and power of 33-35kHz and 300-500W respectively, for 30-60min to form a composite coating.

[0031] Step S42: Transfer the stirred composite coating to a vacuum drying oven and evacuate it. The vacuuming time is 30-60 minutes. Then, heat and sonicate it at 80-90°C with a frequency of 33-35 kHz and a power of 300-500 W to complete one degassing operation. Repeat the cycle until no more bubbles emerge from the solution to obtain the MXene / modified epoxy resin composite coating.

[0032] Step S43: The pretreated rubber sample is completely immersed in the composite coating using a dip-coating method and pulled out at a constant rate. The immersion time is 1–2 min, and the pulling rate is 100–200 mm / min. The coated rubber sample is then dried and cured in a constant temperature drying oven at 80–90℃ for 12–24 h to obtain a rubber sample coated with an MXene / modified epoxy resin composite coating.

[0033] The present invention also provides a hydrogen-blocking and wear-resistant composite coating for rubber sealing of hydrogen energy equipment, which is prepared by the above-described preparation method.

[0034] Compared with the prior art, the present invention can achieve at least the following beneficial effects:

[0035] First, the composite coating prepared by the present invention has uniformly dispersed MXene filling the pores and cracks generated during the curing process of the epoxy resin-terminated polydimethylsiloxane coating, thereby improving the overall density of the coating.

[0036] Secondly, the composite coating prepared by the present invention introduces soft hydroxyl-terminated polydimethylsiloxane into the hard epoxy resin through a silane coupling agent, which gives the epoxy resin a certain toughness. This will help the coating remain smooth, intact and crack-free even when the rubber substrate undergoes large deformation.

[0037] Third, the composite coating prepared by the present invention has good hydrogen barrier and anti-wear and friction reduction properties. The uniformly dispersed and two-dimensional sheet structure of MXene can effectively reduce the hydrogen permeability of the rubber substrate. At the same time, it can form an MXene-based self-lubricating layer during dry friction, thereby significantly reducing the coefficient of friction and wear rate of the coating.

[0038] Fourth, the preparation process provided by this invention is simple, the composite coating has high bonding strength with the substrate, and it can achieve dual protection of the rubber substrate in terms of hydrogen barrier and wear and friction reduction, which can be used for large-scale industrial production. Attached Figure Description

[0039] Figure 1 A schematic diagram of the preparation of the MXene / modified epoxy resin composite coating.

[0040] Figure 2a Scanning electron microscope (SEM) image of the modified epoxy resin coating surface obtained for comparison.

[0041] Figure 2b Scanning electron microscope (SEM) image of the cross-section of the modified epoxy resin coating obtained for comparison.

[0042] Figure 2c This is a scanning electron microscope image of the surface of the modified epoxy resin coating obtained in Example 1.

[0043] Figure 2d This is a scanning electron microscope (SEM) image of the cross-section of the modified epoxy resin coating obtained in Example 1.

[0044] Figure 3a The adhesion diagram of the modified epoxy resin coating obtained for comparison was obtained by cross-cut adhesion testing.

[0045] Figure 3b This is a bonding strength diagram of the modified epoxy resin coating obtained in Example 1, obtained by cross-cut adhesion testing.

[0046] Figure 3c This is a bonding strength diagram of the modified epoxy resin coating obtained in Example 2, obtained by cross-cut adhesion testing.

[0047] Figure 4a These are hydrogen permeation curves of coated rubber samples from different embodiments of the present invention.

[0048] Figure 4b The hydrogen permeability of the coated rubber samples in different embodiments of the present invention is shown.

[0049] Figure 5 The diagram shows the friction coefficients of coated rubber samples in different embodiments of the present invention. Detailed Implementation

[0050] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] According to embodiments of the present invention, the present invention provides a hydrogen-barrier and wear-resistant composite coating for rubber sealing materials of hydrogen energy equipment and its preparation method. Please refer to [link to relevant documentation]. Figure 1 :

[0053] Step 1: Substrate Pretreatment

[0054] The rubber substrate was treated with sulfuric acid solution and silane coupling agent solution, respectively.

[0055] Step 1 specifically includes the following steps:

[0056] Step S11: The rubber sample is ultrasonically washed with anhydrous ethanol and deionized water at an ultrasonic frequency of 33-35 kHz and a power of 300-500 W, and then dried at room temperature.

[0057] Step S12: The dried rubber sample from the previous step is first dispersed and soaked in a 5-10 mol / L sulfuric acid solution for 12-24 hours. Then, the soaked rubber sample is washed with ammonia water and deionized water with a mass fraction of 3-5% and dried at room temperature.

[0058] Step S13: The dried rubber sample from the previous step is dispersed and soaked in KH550 solution with a volume ratio of anhydrous ethanol:KH550:deionized water = 90-95:5-8:1-2. The soaking time is 12-24 hours. Then, the soaked rubber sample is washed with deionized water and dried at room temperature.

[0059] Step 2: MXene preparation

[0060] Ti3AlC2 was etched using a mixture of HCl and LiF, and the etched product was washed with deionized water. The etched product was intercalated with LiCl solution, and the intercalated solution was washed with deionized water. MXene was obtained by centrifugation and freeze-drying. The MXene powder was stirred and ultrasonically dispersed in the curing agent MTHPA to form an MTHPA-MXene dispersion.

[0061] Step 2 specifically includes the following steps:

[0062] Step S21: Add 4–6 g of LiF to 80–90 mL of 9–10 mol / L HCl and stir at room temperature to form an HF etching solution. Then, add 4–5 g of Ti3AlC2 powder to the etching solution and stir at room temperature for 24–48 h. Wash the reaction solution repeatedly with deionized water until the pH is greater than or equal to 6.

[0063] Step S22: Add 20-22 g / L of LiCl aqueous solution to the solution and stir at room temperature for 18-24 h; after stirring, wash the solution three times with deionized water; collect the supernatant by centrifugation at 3500-4000 rpm, and freeze-dry to obtain solid MXene powder;

[0064] Step S23: Stir and ultrasonically disperse 0-0.4g of MXene powder into 80-85g of MTHPA for 0.5-1h of stirring and 1-3h of ultrasonication for 33-35kHz and 300-500W of ultrasonication frequency and power, respectively, to obtain MTHPA-MXene dispersion.

[0065] Step 3: Preparation of modified epoxy resin

[0066] Hydroxyl-terminated polydimethylsiloxane (PDMS-OH) is added to epoxy resin (EP) to form a modified epoxy resin under the action of a silane coupling agent.

[0067] Step 3 specifically includes the following steps:

[0068] Step S31: 100-110g of EP is softened at 80-90℃ for 30-60min to obtain sufficient fluidity. Then, it is premixed with 20-25g of PDMS-OH for 10-20min. 5-10g of KH550 and 0.3-1g of dibutyltin dilaurate are added, and the mixture is stirred at 80-90℃ for 6-8h to form a modified epoxy resin.

[0069] Step 4: Preparation of composite coating

[0070] MTHPA-MXene dispersion and accelerator were added to the modified epoxy resin, and the mixture was stirred and sonicated to form a uniformly mixed composite coating. The composite coating was then subjected to vacuum defoaming treatment. The pretreated rubber substrate was immersed in the composite coating, stretched, and cured using a vacuum drying oven.

[0071] Step 4 specifically includes the following steps:

[0072] Step S41: Slowly add the MTHPA-MXene dispersion to the modified epoxy resin and add 1-3g of accelerator. Stir and sonicate at a speed of 2000-2500rpm, an ultrasonic frequency of 35kHz, a power of 500W, and a time of 30-60min to form a composite coating.

[0073] Step S42: Transfer the stirred composite coating to a vacuum drying oven and evacuate it. The vacuuming time is 30-60 minutes. Then, heat and sonicate it at 80-90°C with a frequency of 33-35 kHz and a power of 300-500 W to complete one degassing operation. Repeat the cycle until no more bubbles emerge from the solution to obtain the MXene / modified epoxy resin composite coating.

[0074] Step S43: The pretreated rubber sample is completely immersed in the composite coating using a dip-coating method and pulled out at a constant rate. The immersion time is 1–2 min, and the pulling rate is 100–200 mm / min. The coated rubber sample is then dried and cured in a constant temperature drying oven at 80–90℃ for 12–24 h to obtain a rubber sample coated with an MXene / modified epoxy resin composite coating.

[0075] According to an embodiment of the present invention, the size of the rubber substrate is MXene is made by etching Ti3AlC2; the silane coupling agent is KH550; EP is E51 type resin; PDMS-OH is monohydroxy-terminated polydimethylsiloxane; the curing agent is methyltetrahydrophthalic anhydride MTHPA; and the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0076] In this invention, a comparative example of a modified epoxy resin coating without MXene is given, and two examples of hydrogen-barrier and wear-resistant MXene / modified epoxy resin composite coatings containing different proportions of MXene are also given.

[0077] Comparative example:

[0078] A modified epoxy resin coating was prepared on the surface of nitrile rubber by dip coating, and the following steps were performed:

[0079] Step 1: Substrate Pretreatment

[0080] The size is The nitrile rubber samples were ultrasonically washed with anhydrous ethanol and deionized water at a frequency of 35 kHz and a power of 500 W, respectively, and then dried at room temperature. The dried rubber samples were then dispersed and immersed in a 5 mol / L sulfuric acid solution for 12 hours. The immersed rubber samples were then washed with 3% ammonia and deionized water, respectively, and dried at room temperature. Finally, the dried rubber samples were dispersed and immersed in a KH550 solution with a volume ratio of anhydrous ethanol:KH550:deionized water = 94:5:1 for 12 hours. The immersed rubber samples were then washed with deionized water and dried at room temperature.

[0081] Step 2: Preparation of modified epoxy resin

[0082] 100g of E51 resin was softened at 80℃ for 30min to obtain sufficient fluidity. Then it was premixed with 20g of PDMS-OH for 10min. Subsequently, 5g of KH550 and 0.3g of dibutyltin dilaurate were added, and the mixture was stirred at 80℃ for 6h to form a modified epoxy resin.

[0083] Step 3: Preparation of composite coating

[0084] 85g of MTHPA was slowly added to the modified epoxy resin, along with 1g of accelerator. The mixture was stirred and sonicated at 2000rpm, 35kHz, 500W for 30min to form a composite coating. The stirred composite coating was transferred to a vacuum drying oven and evacuated for 30min. It was then heated and sonicated at 80℃, 35kHz, and 500W to remove air bubbles. This process was repeated until no more air bubbles emerged from the solution, yielding the MXene / modified epoxy resin composite coating. The pretreated nitrile rubber sample was completely immersed in the composite coating using a dip-coating method and pulled out at a constant rate of 1min (immersion time 1min, pull-out rate 100mm / min). The coated nitrile rubber sample was then dried and cured in a constant temperature drying oven at 80℃ for 12h to obtain a nitrile rubber sample coated with the MXene / modified epoxy resin composite coating.

[0085] Example 1:

[0086] An MXene / modified epoxy resin composite coating was prepared on the surface of nitrile rubber by following these steps:

[0087] The substrate pretreatment in step 1 is the same as that in step 1 of the comparative example.

[0088] Step 2: Preparation of MXene

[0089] 4 g of LiF was added to 80 mL of 9 mol / L HCl and stirred at room temperature to form an HF etching solution. Then, 4 g of Ti3AlC2 powder was added to the etching solution and stirred at room temperature for 24 h. The solution was repeatedly washed with deionized water until the pH was greater than or equal to 6. A 20 g / L LiCl aqueous solution was added to the solution and stirred at room temperature for 18 h. After stirring, the solution was washed three times with deionized water. Finally, the supernatant was collected by centrifugation at 3500 rpm and freeze-dried to obtain solid MXene powder. 0.2 g of MXene powder was stirred and ultrasonically dispersed in 85 g of MTHPA for 0.5 h of stirring and 1 h of ultrasonication at a frequency of 35 kHz and a power of 500 W to obtain an MTHPA-MXene dispersion.

[0090] The preparation of the modified epoxy resin in step 3 is the same as that in step 2 of the comparative example.

[0091] Step 4: Preparation of composite coating

[0092] The MTHPA-MXene dispersion was slowly added to the modified epoxy resin, along with 1g of accelerator. The mixture was stirred and sonicated at a frequency of 35kHz, a power of 500W, a rotation speed of 2000rpm, and a time of 30min to form a composite coating. The stirred composite coating was transferred to a vacuum drying oven and evacuated for 30min per vacuum cycle. Subsequently, it was heated and sonicated at 80℃ with a frequency of 35kHz and a power of 500W to remove air bubbles. This process was repeated multiple times until no more air bubbles emerged from the solution, yielding the MXene / modified epoxy resin composite coating. The pretreated nitrile rubber sample was completely immersed in the composite coating using a dip-coating method and pulled out at a constant rate of 1min (immersion time 1min, pull-out rate 100mm / min). The coated rubber sample was then dried and cured in a constant temperature drying oven at 80℃ for 12h to obtain a nitrile rubber sample coated with the MXene / modified epoxy resin composite coating.

[0093] In this embodiment, the coating-substrate bonding performance is good, and the coating has good hydrogen barrier and wear-resistant properties.

[0094] Example 2:

[0095] An MXene / modified epoxy resin composite coating was prepared on the surface of nitrile rubber by following these steps:

[0096] Step 1: Substrate Pretreatment

[0097] The size is The nitrile rubber samples were ultrasonically washed with anhydrous ethanol and deionized water at a frequency of 33 kHz and a power of 300 W, respectively, and then dried at room temperature. The dried rubber samples were then dispersed and immersed in a 10 mol / L sulfuric acid solution for 24 hours. The immersed rubber samples were then washed with 5% ammonia and deionized water, respectively, and dried at room temperature. Finally, the dried rubber samples were dispersed and immersed in a KH550 solution with a volume ratio of anhydrous ethanol:KH550:deionized water = 90:8:2 for 24 hours. The immersed rubber samples were then washed with deionized water and dried at room temperature.

[0098] Step 2: Preparation of MXene

[0099] 6 g of LiF was added to 90 mL of 10 mol / L HCl and stirred at room temperature to form an HF etching solution. Then, 5 g of Ti3AlC2 powder was added to the etching solution and stirred at room temperature for 48 h. The solution was repeatedly washed with deionized water until the pH was greater than or equal to 6. A 22 g / L LiCl aqueous solution was added to the solution and stirred at room temperature for 24 h. After stirring, the solution was washed three times with deionized water. Finally, the supernatant was collected by centrifugation at 4000 rpm and freeze-dried to obtain solid MXene powder. 0.4 g of MXene powder was stirred and ultrasonically dispersed in 80 g of MTHPA for 1 h of stirring and 3 h of ultrasonication at a frequency of 33 kHz and a power of 300 W to obtain an MTHPA-MXene dispersion.

[0100] Step 3: Preparation of modified epoxy resin

[0101] 110g of E51 resin was softened at 90℃ for 60min to obtain sufficient fluidity. Then it was premixed with 25g of PDMS-OH for 20min. Subsequently, 10g of KH550 and 1g of dibutyltin dilaurate were added, and the mixture was stirred at 90℃ for 8h to form a modified epoxy resin.

[0102] Step 4: Preparation of composite coating

[0103] The MTHPA-MXene dispersion was slowly added to the modified epoxy resin, along with 3g of accelerator. The mixture was stirred and sonicated at a frequency of 33kHz, a power of 300W, a rotation speed of 2500rpm, and a time of 60min to form a composite coating. The stirred composite coating was transferred to a vacuum drying oven and evacuated for 60min per vacuum cycle. Subsequently, it was heated and sonicated at 90℃ with a frequency of 33kHz and a power of 300W to remove air bubbles. This process was repeated multiple times until no more air bubbles emerged from the solution, yielding the MXene / modified epoxy resin composite coating. The pretreated nitrile rubber sample was completely immersed in the composite coating using a dip-coating method and pulled out at a constant rate of 200mm / min for 2min. The coated rubber sample was then dried and cured in a constant temperature drying oven at 90℃ for 24h to obtain a nitrile rubber sample coated with the MXene / modified epoxy resin composite coating.

[0104] Please see Figures 2a to 2d The surfaces and cross-sections of the coatings prepared in the comparative example and Example 1 were subjected to SEM tests. The comparative example coating surface exhibited multiple pores surrounded by cracks, and the pores and cracks existed independently. However, the surface of the Example 1 coating showed more signs of stitching, which may be due to the introduction of MXene filling the pores and cracks formed during the epoxy resin curing process. Furthermore, the cross-section of the comparative example coating was uneven, with step-like wrinkles observed that were not flush with the cross-section between the coating and the substrate. In contrast, the cross-section of the Example 1 coating was generally smooth, exhibiting a straight, river-like pattern from top to bottom, and the cross-section between the coating and the substrate was flush, with no obvious defects observed. This indicates that the MXene sheets were well oriented and uniformly dispersed in the EP / PDMS-OH system, resulting in a denser coating structure, which provides a good foundation for the coating's performance. The comparative example surface showed more pores and cracks, forming rapid channels for hydrogen molecule diffusion and hindering stress transmission during metal-metal friction, leading to deterioration of tribological properties.

[0105] Please see Figure 3a , 3b For Examples 1 and 2, the adhesion between the coating and the substrate was tested using the cross-cut test method according to GB / T 9286-2021 "Paints and Varnishes - Cross-cut Test". It was found that the surface of the comparative example showed slight damage, with obvious peeling observed at the cut edges and grid intersections. In contrast, the surfaces of Examples 1 and 2 showed almost no coating peeling, and all cut edges were smooth and neat. These results indicate that the introduction of MXene enhances the adhesion between the coating and the substrate.

[0106] Please see Figure 4a and 4bThe hydrogen permeability of nitrile rubber, the comparative coating, and the coatings prepared in Examples 1 and 2 were tested at 0.1 MPa and 25°C. It was observed that the hydrogen permeability curves and hydrogen permeability of the coatings of Examples 1 and 2, which were doped with MXene sheets, were significantly lower than those of the substrate, decreasing by 67.9% and 23.8% respectively compared to the rubber substrate. In contrast, the hydrogen permeability of the undoped MXene coating decreased only slightly compared to the substrate. This indicates that the MXene sheets in the coatings played a good barrier role, giving the coatings excellent hydrogen barrier properties.

[0107] Please see Figure 5 Nitrile rubber, comparative coating, and coatings from Examples 1 and 2 were respectively applied to friction pairs with dimensions of [missing information]. Tribological properties were tested using GCr15 steel balls, under a load of 5 N, a test time of 1800 s, a reciprocating displacement of 3 mm, and a wear time of 30 min for both the substrate and the coating. The test results showed that all coatings significantly improved the friction resistance of the substrate. Compared with the nitrile rubber substrate, the average coefficients of friction for the comparative example, Example 1, and Example 2 were reduced by 82%, 88.3%, and 70.8%, respectively. This is because the coatings formed a lubricating layer on the substrate during friction, providing excellent lubrication. In summary, the sample in Example 1 exhibited the best anti-wear and friction-reducing performance. Although the different MXene doping amounts resulted in variations in the lubricating effect of the coatings, all coatings were able to largely prevent wear on the NBR substrate, thanks to the strong adhesion and high wear resistance of the coatings.

[0108] In summary, the composite coating prepared by this invention has uniformly dispersed MXene filling the pores and cracks generated during the curing process of the epoxy resin-terminated polydimethylsiloxane coating, thereby improving the overall density of the coating.

[0109] The composite coating prepared by the present invention introduces soft hydroxyl-terminated polydimethylsiloxane into rigid epoxy resin through a silane coupling agent, which imparts a certain toughness to the epoxy resin. This will help the coating remain smooth, intact and crack-free even when the rubber substrate undergoes large deformation.

[0110] The composite coating prepared by this invention has good hydrogen barrier and anti-wear and friction reduction properties. The uniformly dispersed and two-dimensional lamellar structure of MXene can effectively reduce the hydrogen permeability of the rubber substrate. At the same time, the coating can form a self-lubricating layer during dry friction, thereby significantly reducing the coefficient of friction and wear rate of the coating.

[0111] The preparation method provided by this invention is simple, and the composite coating has high bonding strength with the substrate, which can achieve dual protection of the rubber substrate in terms of hydrogen barrier and wear and friction reduction, and can be used for large-scale industrial production.

[0112] The above examples are merely specific implementation cases of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make certain modifications or alterations to the above-disclosed structure and technical content without departing from the scope of the present invention to create equivalent implementation cases. Any simple modifications, equivalent changes, and alterations made to the above implementation cases based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a rubber seal hydrogen barrier wear resistant composite coating for hydrogen energy equipment, characterized in that, The method comprises the following steps: Step 1: treating the rubber base material with a sulfuric acid solution and a silane coupling agent solution respectively; Step 2: etching Ti3AlC2 by using a mixed solution of HCl and LiF, washing the etching product with deionized water, intercalating the etched product by using a LiCl solution, washing the intercalated solution with deionized water, and obtaining MXene by centrifugation and freeze-drying; stirring and ultrasonically dispersing the MXene powder in a curing agent methyltetrahydrophthalic anhydride MTHPA to form a MTHPA-MXene dispersion liquid; Step 3: adding monohydroxyl-terminated polydimethylsiloxane PDMS-OH into an epoxy resin EP to form a modified epoxy resin under the action of a silane coupling agent; Step 4: adding the MTHPA-MXene dispersion liquid and an accelerator into the modified epoxy resin, stirring and ultrasonically dispersing to form a mixed and uniform composite coating, and performing vacuum defoaming treatment on the composite coating; immersing the pretreated rubber base material into the composite coating, performing pulling and lifting, and performing heating and curing by using a vacuum drying oven to obtain the rubber coating.

2. The method of claim 1, wherein the method is characterized by: The rubber base material has a size of φ 60 ~ 80 1 ~ 3 mm.

3. The method of claim 1, wherein the method is characterized by: The EP is an E51 type resin.

4. The method of claim 1, wherein the method is characterized by: The silane coupling agent is KH550, and the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

5. The method of claim 1, wherein the method is characterized by: Step 1 comprises the following steps: Step S11, ultrasonically washing the rubber sample with anhydrous ethanol and deionized water, and drying at room temperature, wherein the ultrasonic frequency and power are 33-35 kHz and 300-500 W respectively; Step S12, dispersing and immersing the dried rubber sample in a 5-10 mol / L sulfuric acid solution, and then washing the immersed rubber sample with 3-5% ammonia water and deionized water, and drying at room temperature; Step S13, dispersing and immersing the dried rubber sample in a KH550 solution, wherein the volume ratio of anhydrous ethanol: KH550: deionized water is 90-94: 5-8: 1-2, the immersion time is 12-24 h, and then washing the immersed rubber sample with deionized water and drying at room temperature.

6. The method of claim 1, wherein the method is characterized by: Step 2 comprises the following steps: Step S21, adding 4-6 g of LiF to 80-90 mL of 9-10 mol / L HCl to form an HF etching solution by stirring at room temperature; then, adding 4-5 g of Ti3AlC2 powder to the etching solution, and stirring at room temperature for 24-48 h, and repeatedly washing the reacted solution with deionized water until the pH is greater than or equal to 6; Step S22, adding 20-22 g / L LiCl aqueous solution to the solution, and stirring at room temperature for 18-24 h; after stirring, washing the solution with deionized water three times; centrifuging the supernatant at 3500-4000 rpm, and freeze-drying to obtain solid MXene powder; Step S23, 0.2-0.4 g MXene powder is stirred and ultrasonically dispersed into 80-85 g MTHPA, the stirring time is 0.5-1 h, the ultrasonic time is 1-3 h, the ultrasonic frequency and power are 33-35 kHz and 300-500 W respectively, to obtain a MTHPA-MXene dispersion.

7. The method of claim 1, wherein the method is characterized by: Step 3 comprises the following steps: Step S31, 100-110 g EP is softened at a temperature of 80-90 °C for 30-60 min to obtain sufficient fluidity, then it is premixed with 20-25 g PDMS-OH for 10-20 min, 5-10 g KH550 and 0.3-1 g dibutyltin dilaurate are added, and stirring is carried out at 80-90 °C for 6-8 h to form a modified epoxy resin.

8. The method of claim 1, wherein the method is characterized by: Step 4 comprises the following steps: Step S41, the MTHPA-MXene dispersion is slowly added to the modified epoxy resin described above, and 1-3 g of an accelerator is added, and stirring and ultrasonic are carried out at a speed of 2000-2500 rpm, an ultrasonic frequency of 33-35 kHz and a power of 300-500 W for 30-60 min to form a composite coating; Step S42, the stirred composite coating is transferred to a vacuum drying oven for vacuumizing, the single vacuumizing time is 30-60 min, then heating and ultrasonic are carried out at 80-90 °C, the ultrasonic frequency is 33-35 kHz and the power is 300-500 W to complete a bubble removing operation, and multiple cycles are carried out until no bubbles come out from the inside of the solution to obtain a MXene / modified epoxy resin composite coating; Step S43, the pretreated rubber sample is completely immersed in the composite coating by dip coating method, and is pulled out at a constant rate, the immersion time is 1-2 min, and the pulling rate is 100-200 mm / min; the coated rubber sample is dried and cured in a constant temperature drying oven, the curing temperature is 80-90 °C, and the curing time is 12-24 h to obtain a rubber sample coated with a MXene / modified epoxy resin composite coating.

9. A rubber seal hydrogen barrier wear resistant composite coating for hydrogen energy equipment, characterized by, Prepared by the preparation method of any one of claims 1-8. Prepared by the preparation method of any one of claims 1-8.

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