Organic elastomer surface treatment method

Abstract

The invention belongs to the technical field of material surface treatment, and particularly relates to an organic elastomer surface treatment method which comprises the following steps: creating active sites on the surface through plasma or flame treatment, and sequentially coating a high-temperature-resistant interface agent and a high-temperature-resistant coating containing a damp-heat-resistant composite additive, the damp-heat-resistant composite additive is formed by modifying potassium titanate whiskers with silane and aluminum dihydrogen phosphate and then compounding the modified potassium titanate whiskers with metal oxide. Through the synergistic effect of all links, the adhesive force, damp heat resistance and high temperature resistance of the elastomer and a coating are remarkably improved, the organic elastomer can be stably used in a high-temperature, high-humidity and high-pressure environment, the application range of the organic elastomer is effectively expanded, and the practicability is high.

Description

Technical Field

[0001] This invention relates to the field of material surface treatment technology, and more specifically to a method for surface treatment of organic elastomers. Background Technology

[0002] Heavy oil, as an important strategic alternative resource, relies on thermal recovery technologies (such as steam injection and steam drive) for efficient extraction. These technologies operate under extreme conditions, placing unprecedented demands on downhole equipment, especially key organic elastomer components such as packer sleeves inside the well and sealing gaskets for external flange connections. These components are typically made of organic elastomer materials such as fluororubber and hydrogenated nitrile rubber. However, organic elastomers have low surface energy and strong chemical inertness, requiring surface treatment to adhere functional coatings. Existing technologies often employ sandblasting, solvent cleaning, or simple chemical treatments. However, these methods only achieve bonding through physical anchoring or weak chemical bonds. Under the high-humidity environment of 350℃, 20MPa, and high humidity during heavy oil thermal recovery, the interface is prone to hydrolysis, oxidative degradation, and stress relaxation. Coatings typically exhibit blistering, cracking, or peeling within 7 days, failing to meet the sealing requirements of a complete injection-production cycle.

[0003] Patent application number CN202110687716.3 discloses a rubber surface treatment agent, its preparation method, and a rubber surface treatment process. The rubber surface treatment agent of this invention comprises: a main solvent, 100 parts by weight; a coagulant, 3-20 parts by weight; functional additive A, 1-15 parts by weight; and functional additive B, 0.1-5 parts by weight. The main solvent is one or a combination of the following solvents: n-heptane, cycloheptane, C11-C33 chain alkanes, and C11-C33 cyclic alkanes. The surface treatment agent comprises C11-C33 chain alkanes with one or more functional groups including hydroxyl, ester, carbonyl, and carboxyl groups, and C11-C33 cyclic alkanes with one or more functional groups including hydroxyl, ester, carbonyl, and carboxyl groups; functional additive A is one or a combination of ethers, esters, alcohols, and ketones; functional additive B is one or a combination of natural rubber, styrene-butadiene rubber, nitrile rubber, styrene rubber, vinyl chloride rubber, ethylene propylene diene monomer (EPDM) rubber, butyl rubber, cis-butadiene rubber, isoprene rubber, and chloroprene rubber. This surface treatment agent can efficiently increase the coefficient of friction on rubber surfaces and is safe and environmentally friendly. However, this solution aims to form a texture by dissolving with the latex surface, which is a physical bond. Furthermore, the main solvent and functional additives of this treatment agent are all conventional organic materials with thermal decomposition temperatures far below 350°C. Therefore, under the continuous high temperatures of heavy oil thermal recovery, the bonding strength of this treatment agent layer is very weak, and it will quickly volatilize, thermally decompose, or carbonize. Not only will it fail to provide protection, but its residues may also contaminate the medium or accelerate the aging of the matrix, making it unsuitable for use in the field of heavy oil thermal recovery.

[0004] Patent application CN202211228017.3 discloses a silicone rubber surface treatment agent and its preparation method. The silicone rubber surface treatment agent comprises the following raw materials in parts by weight: 20-40 parts of methyl MQ resin; 40-160 parts of α,ω-dihydroxy polysiloxane; 0.2-10 parts of coupling agent; 0.05-1 part of catalyst; and 1000-1600 parts of solvent. After curing, the silicone rubber surface treatment agent in this application can achieve the strength of the rubber compound itself and significantly reduce the surface tackiness caused by directly using pressure-sensitive adhesives in the prior art. This makes the silicone substrate treated with the silicone rubber surface treatment agent easier to store and place, reducing storage and management costs. However, the original design of this invention was to improve the adhesion of silicone rubber to other materials (such as plastics, metals or coatings) under normal conditions. The core components are methyl MQ resin and α,ω-dihydroxy polysiloxane. The upper limit of the conventional long-term use temperature of such silicone components is mostly 200-250℃, which is far lower than the 350℃ operating temperature required for the thermal recovery of heavy oil in oil wells. Therefore, it cannot meet the core requirement of long-term reliable protection of oil well sealing gaskets.

[0005] Therefore, developing an organic elastomer surface treatment method that can achieve strong interfacial bonding, long-term resistance to damp heat and humidity, and adaptability to high temperature and high pressure variable working conditions has become a key requirement for improving the efficiency and safety of heavy oil extraction. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a surface treatment method for organic elastomers. This method involves constructing active sites on the surface of the organic elastomer using plasma or flame, achieving precise interfacial bonding with a high-temperature resistant interface agent, and combining this with the application of a high-temperature resistant coating containing moisture-resistant composite additives and a gradient curing process. This results in a surface treatment system that significantly improves the adhesion between the organic elastomer and the coating, possesses excellent moisture-heat and high-temperature resistance, and can stably operate in harsh environments with high temperature, high humidity, and high pressure, effectively expanding the application scenarios of organic elastomers.

[0007] The technical solution of the present invention to solve the above problems is as follows: A method for surface treatment of organic elastomers includes the following steps: (1) Active sites are created on the surface of organic elastomers by means of plasma or flame methods; (2) Treat the surface with a high-temperature resistant interface agent so that the active sites are combined with the high-temperature resistant interface agent; (3) Apply the high-temperature resistant coating to the surface of the organic elastomer so that the high-temperature resistant coating is combined with the high-temperature resistant interface agent on the surface of the organic elastomer.

[0008] Furthermore, the high-temperature resistant coating comprises the following raw materials in parts by weight: 45-55 parts of silicone resin, 8-10 parts of toughening agent, 6-8 parts of moisture-resistant composite additive, 15-20 parts of curing agent, 0.5-0.8 parts of defoamer, and 30-35 parts of solvent.

[0009] Furthermore, the preparation method of the anti-humid heat composite additive is as follows: Step A: Add potassium titanate whiskers and talc powder to anhydrous ethanol and ultrasonically disperse for 30-40 min. Adjust the pH to 3.5-4.0, raise the temperature to 65-70℃, add γ-aminopropyltriethoxysilane solution, and then react for 2.5-3 h to obtain intermediate product 1. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 85-90℃, keep the temperature for 3-4 hours, and then proceed with post-treatment to obtain intermediate product 2. Step C: Perform gradient drying on intermediate product 2. First stage: pre-dry at 75-85℃ for 110-130 min; second stage: cure at 145-155℃ for 110-130 min; third stage: cure at 215-225℃ for 80-100 min to obtain intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide for 10-12 minutes, then add zinc oxide and continue mixing for 5-10 minutes. Then add boron nitride and perform post-treatment to obtain the anti-humid heat composite additive.

[0010] Further, in step A, the mass ratio of potassium titanate whiskers, talc, γ-aminopropyltriethoxysilane, and anhydrous ethanol is 25-30:12-15:1.5-2:76-95; the γ-aminopropyltriethoxysilane solution uses anhydrous ethanol as a solvent and has a concentration of 4.5-5.5%; in step B, the mass ratio of aluminum dihydrogen phosphate to potassium titanate whiskers in step A is 4-6:25-30; the aluminum dihydrogen phosphate solution uses deionized water as a solvent and has a concentration of 18-22%; in step D, the mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step A is 0.8-1.2:1.6-2.4:2-3:15-18:25-30.

[0011] Furthermore, the toughening agent is one or more of short carbon fiber, zirconium oxide fiber, aluminum silicate fiber, and polycrystalline mullite fiber; the curing agent is an isocyanate curing agent; the defoamer is an organosilicon defoamer; and the solvent is xylene.

[0012] Furthermore, the preparation method of the high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing them to a fineness ≤30μm, adding a curing agent, stirring for 15-20min, and maturing for 20-30min to obtain the coating.

[0013] Furthermore, the preparation method of the high-temperature resistant interface agent is as follows: Step a: Phenylacetyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water are reacted under nitrogen and 35±1℃ for 9.5-10.5h, then heated to 75-85℃ for 50-70min, and cooled to 55-65℃ to obtain the prepolymer; Step b: Disperse the prepolymer and hydrogen-containing silicone oil for 15-25 minutes, then add platinum catalyst and continue dispersing for 5-10 minutes, then add toluene to obtain a high-temperature resistant interface agent.

[0014] Further, in step a, the weight ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid, and deionized water is 55:13-17:8-12:75-85:0.4-0.6:1.5-2:10-15; in step b, the weight ratio of prepolymer, hydrogen-containing silicone oil, and platinum catalyst is 100:8-9:0.15-0.2, the solid content of the high-temperature resistant interface agent is 45-55%, and the viscosity is 100-160 mPa·s.

[0015] Furthermore, the plasma treatment uses a mixture of argon and oxygen gas with a power of 300-500W and a treatment time of 60-120s; the flame treatment uses a natural gas flame with a flame temperature of 800-1000℃ and an exposure time of 1-3s.

[0016] Furthermore, the coating thickness of the high-temperature resistant interface agent is 8-15 μm, and after surface drying at room temperature, it is cured at 60-80℃ for 1.5-2.5 h; the coating thickness of the high-temperature resistant coating is 80-150 μm, and after application, it is cured in a gradient manner: 75-85℃×1h, 145-155℃×1h, 245-255℃×2h, and 345-355℃×3h.

[0017] The present invention has the following beneficial effects: This invention significantly improves the overall performance of organic elastomer surface treatment through the synergistic effect of anti-humidity and heat composite additives, high-temperature resistant interface agents, and surface activation treatment. The anti-humidity and heat composite additive uses potassium titanate whiskers, surface-modified with γ-aminopropyltriethoxysilane and aluminum dihydrogen phosphate, to construct a stable Al-OP-Si chemical bond network on the whisker surface. This network firmly connects the inorganic filler to the organosilicon resin matrix, forming a three-dimensional cross-linked framework that effectively restricts the thermal motion of molecular chains at high temperatures and prevents water molecule penetration. Vanadium pentoxide and molybdenum trioxide can generate a self-healing glassy compound in high-temperature and high-humidity environments, filling microcracks in the coating. The layered barrier structure formed by zinc oxide and boron nitride creates a labyrinth effect on water vapor diffusion, thereby significantly enhancing the coating's resistance to damp heat. High-temperature resistant interface agents introduce phenyl rigid structures and vinyl active groups onto the surface of elastomers through the hydrolytic condensation reaction of phenyltrimethoxysilane, diphenyldimethoxysilane, and vinyltrimethoxysilane. The phenyl structure endows the interface layer with excellent thermal oxidation stability, maintaining structural integrity even at 350℃. The vinyl groups undergo cross-linking reactions with the organosilicon resin in the coating during curing, forming a continuous chemical bond network from the substrate to the coating, effectively improving the interfacial bonding strength. Plasma or flame treatment introduces active sites such as hydroxyl and silanol groups onto the surface of the organic elastomer through high-energy oxidation, raising the surface energy from a low-energy state to a high-energy state. This provides chemical anchoring points for the high-temperature resistant interface agent, realizing the transformation from physical adsorption to chemical bonding, and significantly improving the coating wettability and initial adhesion.

[0018] Furthermore, this invention constructs an integrated surface treatment system comprising "plasma / flame substrate activation - dedicated high-temperature resistant interface agent bonding - modified moisture-resistant coating protection." These steps are not simply superimposed but rather form a synergistic overall mechanism. The active sites created by plasma or flame treatment provide the prerequisite for the bonding of the high-temperature resistant interface agent, which in turn enables precise bonding between the active sites and the coating. The moisture-resistant composite additive optimizes the coating's own performance while forming a coherent chemical cross-linking network with the high-temperature resistant interface agent and the activated substrate. This not only significantly improves the adhesion and destructive strength between the organic elastomer and the coating but also endows the composite system with excellent moisture-resistant and high-temperature resistance. It can maintain structural stability for a long time under harsh environments of high temperature, high humidity, and high pressure, effectively preventing coating failures such as blistering, cracking, and peeling. This system perfectly solves the technical defects of weak interfacial bonding and insufficient resistance to harsh environments in traditional organic elastomer surface treatments, significantly expanding the application range of organic elastomers in high-end sealing, high-temperature protection, and other fields. Attached Figure Description

[0019] Figure 1 The diagram shows the destructive strength results for Examples 1-4 and Comparative Examples 1-5; Figure 2The graph shows the results of the damage strength retention rate of Examples 1-4 and Comparative Examples 1-5. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] All raw materials used in the following examples are commercially available products. The silicone resin used is Wacker Ren60, with a maximum thermal stability of 650℃, from Foshan Shengchuangda Chemical Co., Ltd.; the short carbon fiber is short-cut carbon fiber, 3mm in length and 8-10μm in diameter, from Changzhou Yaobang Friction Materials Factory; the zirconia fiber has a fineness of 5000 mesh and a purity of 99.9%, from Lianyungang Rongbai New Materials Co., Ltd.; the aluminosilicate fiber has a length of 2mm and a purity of 91%, from Hebei Leijiang New Materials Technology Co., Ltd.; the polycrystalline mullite fiber has a bulk density of 3.5kg / m³ and a flexural strength of 10MPa, from Shandong Haixin Refractory Materials Co., Ltd.; the isocyanate curing agent has an effective ingredient content of 99%, from BASF HI100, from Guanjiuzhou (Shandong) Energy Technology Co., Ltd.; the silicone defoamer has an effective ingredient content of 5%, from Shandong Wanhua Tianhe New Materials Co., Ltd.; the potassium titanate whiskers have a length of 5-30μm and an effective ingredient content of... Content 98%, Wuhan Kemike Biomedical Technology Co., Ltd.; Talc powder with silica content 61.2%, 800 mesh, moisture content ≤0.19%, Lingshou County Chengyang Mining Co., Ltd.; Boron nitride with effective ingredient content 99.5%, 4500 mesh micro powder, Dongguan Dongchao New Material Technology Co., Ltd.; Zinc oxide 5-100nm, effective ingredient content ≥99.9%, Henan Hengyu Chemical Co., Ltd.; Antioxidant is BASF Irganox PS-802FL, effective ingredient content 99%, Guangdong Taiyang Chemical Materials Technology Co., Ltd.; Hydrogen-containing silicone oil is hydrogen-capped phenyl polysiloxane, effective ingredient content 99%, model MY233, Anhui Mingyi Silicon Industry Co., Ltd.; Platinum catalyst is Karstedt platinum catalyst, effective ingredient content 99%, Hubei Shineng Chemical Technology Co., Ltd.

[0022] Example 1 A method for surface treatment of organic elastomers includes the following steps: (1) Active sites are created on the surface of organic elastomers by means of plasma or flame methods; (2) Treat the surface with a high-temperature resistant interface agent so that the active sites are combined with the high-temperature resistant interface agent; (3) Apply the high-temperature resistant coating to the surface of the organic elastomer so that the high-temperature resistant coating is combined with the high-temperature resistant interface agent on the surface of the organic elastomer.

[0023] The high-temperature resistant coating comprises the following raw materials in parts by weight: 45 parts of silicone resin, 8 parts of toughening agent, 6 parts of moisture-resistant composite additive, 15 parts of curing agent, 0.5 parts of defoamer, and 30 parts of solvent. The toughening agent is short carbon fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0024] The preparation method of the anti-humid heat composite additive is as follows: Step A: Potassium titanate whiskers and talc powder were added to anhydrous ethanol and ultrasonically dispersed at a frequency of 40 kHz and a power of 500 W for 35 min. The pH was adjusted to 3.5-4.0 with 10% dilute acetic acid solution, and the temperature was raised to 68℃. γ-aminopropyltriethoxysilane solution was added dropwise at a rate of 1.5 mL / min while stirring at 500 rpm. After the addition was complete, the temperature was kept constant and the reaction continued for 2.7 h to obtain intermediate product 1. The mass ratio of potassium titanate whiskers, talc powder, γ-aminopropyltriethoxysilane, and anhydrous ethanol was 27:14:1.8:85. The γ-aminopropyltriethoxysilane solution used anhydrous ethanol as the solvent and had a concentration of 5%. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 88℃, and maintain the temperature at 300 rpm for 3.5 h. Then centrifuge at 3500 rpm for 10 min, and wash twice with anhydrous ethanol to obtain intermediate product 2. The mass ratio of aluminum dihydrogen phosphate to potassium titanate whiskers in step A is 5:27. The aluminum dihydrogen phosphate solution uses deionized water as solvent and has a concentration of 20%. Step C: The intermediate product 2 is subjected to gradient high temperature treatment. The first stage is pre-drying at 80℃ for 120 min, the second stage is curing at 150℃ for 120 min, and the third stage is curing at 220℃ for 90 min to obtain the intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide at 2000 rpm for 11 min, then add zinc oxide and continue mixing for 8 min. Then add boron nitride to xylene using a spray device. The mass ratio of boron nitride to xylene is 1:4, the speed is 1200 rpm, the spray pressure is 0.2 MPa, and the feeding time is 20 min. Then, vacuum degassing is performed under a vacuum degree of -0.08 MPa for 20 min to obtain the anti-humid heat composite additive. The mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step A is 1:2:2.5:16:28.

[0025] The preparation method of the high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive and defoamer to solvent and dispersing at 1500 rpm until the fineness is ≤30μm, adding curing agent, stirring at 600 rpm for 15 min, and maturing for 20 min to obtain the coating.

[0026] The preparation method of the high-temperature resistant interface agent is as follows: Step a: Phenylacetyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water are reacted under nitrogen, 34°C and 300 rpm for 9.5 h, then the temperature is raised to 75°C and reacted for 50 min, and then cooled to 55°C to obtain a prepolymer, wherein the weight ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water is 55:13:8:75:0.4:1.5:10; Step b: Disperse the prepolymer and hydrogen-containing silicone oil under nitrogen at 1000 rpm for 15 min, then add platinum catalyst and continue dispersing for 5 min, then add toluene to obtain a high-temperature resistant interface agent with a solid content of 45% and a viscosity of 100 mPa·s, wherein the weight ratio of prepolymer, hydrogen-containing silicone oil and platinum catalyst is 100:8:0.15.

[0027] The plasma treatment uses a mixture of argon and oxygen in a volume ratio of 4:1, with a power of 300W and a treatment time of 60s; the flame treatment uses a natural gas flame with a flame temperature of 800℃ and an exposure time of 1s, and is performed twice.

[0028] The coating thickness of the high-temperature resistant interface agent is 8μm, and after surface drying at room temperature, it is cured at 60℃ for 1.5h; the coating thickness of the high-temperature resistant coating is 80μm, and after application, it is cured in a gradient manner: 75℃×1h, 145℃×1h, 245℃×2h, 345℃×3h.

[0029] Example 2 A method for surface treatment of organic elastomers includes the following steps: (1) Active sites are created on the surface of organic elastomers by means of plasma or flame methods; (2) Treat the surface with a high-temperature resistant interface agent so that the active sites are combined with the high-temperature resistant interface agent; (3) Apply the high-temperature resistant coating to the surface of the organic elastomer so that the high-temperature resistant coating is combined with the high-temperature resistant interface agent on the surface of the organic elastomer.

[0030] The high-temperature resistant coating comprises the following raw materials in parts by weight: 55 parts of silicone resin, 10 parts of toughening agent, 8 parts of moisture-resistant composite additive, 20 parts of curing agent, 0.8 parts of defoamer, and 35 parts of solvent. The toughening agent is zirconium oxide fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0031] The preparation method of the anti-humid heat composite additive is the same as in Example 1.

[0032] The preparation method of the high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding curing agent; stirring at 600 rpm for 20 min; and maturing for 30 min to obtain the coating.

[0033] The preparation method of the high-temperature resistant interface agent is as follows: Step a: Phenylacetyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water are reacted under nitrogen, 36°C and 300 rpm for 10.5 h, then the temperature is raised to 85°C and reacted for 70 min, and then cooled to 65°C to obtain a prepolymer, wherein the weight ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water is 55:17:12:85:0.6:2:15; Step b: Disperse the prepolymer and hydrogen-containing silicone oil under nitrogen at 1000 rpm for 25 min, then add platinum catalyst and continue dispersing for 10 min, then add toluene to obtain a high-temperature resistant interface agent with a solid content of 55% and a viscosity of 160 mPa·s, wherein the weight ratio of prepolymer, hydrogen-containing silicone oil and platinum catalyst is 100:9:0.2.

[0034] The plasma treatment uses a mixture of argon and oxygen in a volume ratio of 4:1, with a power of 500W and a treatment time of 120s; the flame treatment uses a natural gas flame with a flame temperature of 1000℃ and an exposure time of 3s, and is performed twice.

[0035] The coating thickness of the high-temperature resistant interface agent is 15μm, and after surface drying at room temperature, it is cured at 80℃ for 2.5h; the coating thickness of the high-temperature resistant coating is 150μm, and after application, it is cured in a gradient manner: 85℃×1h, 155℃×1h, 255℃×2h, 355℃×3h.

[0036] Example 3 A method for surface treatment of organic elastomers includes the following steps: (1) Active sites are created on the surface of organic elastomers by means of plasma or flame methods; (2) Treat the surface with a high-temperature resistant interface agent so that the active sites are combined with the high-temperature resistant interface agent; (3) Apply the high-temperature resistant coating to the surface of the organic elastomer so that the high-temperature resistant coating is combined with the high-temperature resistant interface agent on the surface of the organic elastomer.

[0037] The high-temperature resistant coating comprises the following raw materials in parts by weight: 50 parts of silicone resin, 9 parts of toughening agent, 7 parts of moisture-resistant composite additive, 18 parts of curing agent, 0.6 parts of defoamer, and 32 parts of solvent. The toughening agent is polycrystalline mullite fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0038] The preparation method of the anti-humid heat composite additive is the same as in Example 1.

[0039] The preparation method of the high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding curing agent; stirring at 600 rpm for 18 min; and maturing for 25 min to obtain the coating.

[0040] The preparation method of the high-temperature resistant interface agent is as follows: Step a: Phenylacetyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water are reacted under nitrogen, 35°C and 300 rpm for 10 h, then the temperature is raised to 80°C and reacted for 60 min, and then cooled to 60°C to obtain a prepolymer, wherein the weight ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water is 55:15:10:80:0.5:1.8:15; Step b: Disperse the prepolymer and hydrogen-containing silicone oil under nitrogen at 1000 rpm for 20 min, then add platinum catalyst and continue dispersing for 8 min, then add toluene to obtain a high-temperature resistant interface agent with a solid content of 50% and a viscosity of 140 mPa·s, wherein the weight ratio of prepolymer, hydrogen-containing silicone oil and platinum catalyst is 100:8.5:0.17.

[0041] The plasma treatment uses a mixture of argon and oxygen in a volume ratio of 4:1, with a power of 400W and a treatment time of 100s; the flame treatment uses a natural gas flame with a flame temperature of 900℃ and an exposure time of 2s, and is performed twice.

[0042] The coating thickness of the high-temperature resistant interface agent is 10 μm, and after surface drying at room temperature, it is cured at 70℃ for 2 hours; the coating thickness of the high-temperature resistant coating is 110 μm, and after application, it is cured in a gradient manner: 80℃×1h, 150℃×1h, 250℃×2h, 350℃×3h.

[0043] Example 4 A method for surface treatment of organic elastomers includes the following steps: (1) Active sites are created on the surface of organic elastomers by means of plasma or flame methods; (2) Treat the surface with a high-temperature resistant interface agent so that the active sites are combined with the high-temperature resistant interface agent; (3) Apply the high-temperature resistant coating to the surface of the organic elastomer so that the high-temperature resistant coating is combined with the high-temperature resistant interface agent on the surface of the organic elastomer.

[0044] The high-temperature resistant coating comprises the following raw materials in parts by weight: 50 parts of silicone resin, 9 parts of toughening agent, 7 parts of moisture-resistant composite additive, 18 parts of curing agent, 0.6 parts of defoamer, and 32 parts of solvent. The toughening agent is polycrystalline mullite fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0045] The preparation method of the anti-humid heat composite additive is as follows: Step A: Potassium titanate whiskers and talc powder were added to anhydrous ethanol and ultrasonically dispersed at a frequency of 40 kHz and a power of 500 W for 30 min. The pH was adjusted to 3.5-4.0 with 10% dilute acetic acid solution, and the temperature was raised to 65℃. γ-aminopropyltriethoxysilane solution was added dropwise at a rate of 1.5 mL / min while stirring at 500 rpm. After the addition was complete, the temperature was kept constant and the reaction continued for 2.5 h to obtain intermediate product 1. The mass ratio of potassium titanate whiskers, talc powder, γ-aminopropyltriethoxysilane, and anhydrous ethanol was 25:12:1.5:76. The γ-aminopropyltriethoxysilane solution used anhydrous ethanol as the solvent and had a concentration of 4.5%. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 85℃, and maintain the temperature at 300 rpm for 3 hours. Then centrifuge at 3500 rpm for 10 minutes, and wash twice with anhydrous ethanol to obtain intermediate product 2. The mass ratio of aluminum dihydrogen phosphate to potassium titanate whiskers in step A is 4:25. The aluminum dihydrogen phosphate solution uses deionized water as solvent and has a concentration of 18%. Step C: The intermediate product 2 is subjected to gradient high temperature treatment. The first stage is pre-drying at 85℃ for 110 min, the second stage is curing at 155℃ for 110 min, and the third stage is curing at 225℃ for 80 min to obtain the intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide at 2000 rpm for 10 min, then add zinc oxide and continue mixing for 5 min. Then add boron nitride to xylene using a spray device. The mass ratio of boron nitride to xylene is 1:4, the speed is 1200 rpm, the spray pressure is 0.2 MPa, and the feeding time is 20 min. Then, vacuum degassing is performed under a vacuum degree of -0.08 MPa for 20 min to obtain the anti-humid heat composite additive. The mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step A is 0.8:1.6:2:15:25.

[0046] The preparation method of the high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding curing agent; stirring at 600 rpm for 18 min; and maturing for 25 min to obtain the coating.

[0047] The preparation method of the high-temperature resistant interface agent is as follows: Step a: Phenylacetyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water are reacted under nitrogen, 35°C and 300 rpm for 10 h, then the temperature is raised to 80°C and reacted for 60 min, and then cooled to 60°C to obtain a prepolymer, wherein the weight ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water is 55:15:10:80:0.5:1.8:15; Step b: Disperse the prepolymer and hydrogen-containing silicone oil under nitrogen at 1000 rpm for 20 min, then add platinum catalyst and continue dispersing for 8 min, then add toluene to obtain a high-temperature resistant interface agent with a solid content of 50% and a viscosity of 140 mPa·s, wherein the weight ratio of prepolymer, hydrogen-containing silicone oil and platinum catalyst is 100:8.5:0.17.

[0048] The plasma treatment uses a mixture of argon and oxygen in a volume ratio of 4:1, with a power of 400W and a treatment time of 100s; the flame treatment uses a natural gas flame with a flame temperature of 900℃ and an exposure time of 2s, and is performed twice.

[0049] The coating thickness of the high-temperature resistant interface agent is 10 μm, and after surface drying at room temperature, it is cured at 70℃ for 2 hours; the coating thickness of the high-temperature resistant coating is 110 μm, and after application, it is cured in a gradient manner: 80℃×1h, 150℃×1h, 250℃×2h, 350℃×3h.

[0050] Comparative Example 1 A method for surface treatment of organic elastomers includes the following steps: (1) Active sites are created on the surface of organic elastomers by means of plasma or flame methods; (2) Treat the surface with a high-temperature resistant interface agent so that the active sites are combined with the high-temperature resistant interface agent; (3) Apply the high-temperature resistant coating to the surface of the organic elastomer so that the high-temperature resistant coating is combined with the high-temperature resistant interface agent on the surface of the organic elastomer.

[0051] The high-temperature resistant coating comprises the following raw materials in parts by weight: 50 parts of silicone resin, 9 parts of toughening agent, 1 part of moisture-resistant composite additive, 18 parts of curing agent, 0.6 parts of defoamer, and 32 parts of solvent. The toughening agent is polycrystalline mullite fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0052] The preparation method of the anti-humid heat composite additive is as follows: Step A: Potassium titanate whiskers and talc powder were added to anhydrous ethanol and ultrasonically dispersed at a frequency of 40 kHz and a power of 500 W for 30 min. The pH was adjusted to 3.5-4.0 with 10% dilute acetic acid solution, and the temperature was raised to 40℃. γ-aminopropyltriethoxysilane solution was added dropwise at a rate of 1.5 mL / min while stirring at 500 rpm. After the addition was complete, the temperature was kept constant and the reaction continued for 2.5 h to obtain intermediate product 1. The mass ratio of potassium titanate whiskers, talc powder, γ-aminopropyltriethoxysilane, and anhydrous ethanol was 25:25:1.5:76. The γ-aminopropyltriethoxysilane solution used anhydrous ethanol as the solvent and had a concentration of 4.5%. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 50°C, and maintain the temperature at 300 rpm for 1 hour. Then centrifuge at 3500 rpm for 10 minutes, and wash twice with anhydrous ethanol to obtain intermediate product 2. The mass ratio of aluminum dihydrogen phosphate to potassium titanate whiskers in step A is 1:25. The aluminum dihydrogen phosphate solution uses deionized water as solvent and has a concentration of 18%. Step C: The intermediate product 2 is subjected to gradient high temperature treatment. The first stage is pre-drying at 40℃ for 110 min, the second stage is curing at 80℃ for 110 min, and the third stage is curing at 225℃ for 80 min to obtain the intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide at 2000 rpm for 10 min, then add zinc oxide and continue mixing for 5 min. Then add boron nitride to xylene using a spray device. The mass ratio of boron nitride to xylene is 1:4, the speed is 1200 rpm, the spray pressure is 0.2 MPa, and the feeding time is 20 min. Then, vacuum degassing is performed under a vacuum degree of -0.08 MPa for 20 min to obtain the anti-humid heat composite additive. The mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step A is 0.8:1.6:2:15:15.

[0053] The preparation method of the high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding curing agent; stirring at 600 rpm for 10 min; and maturing for 25 min to obtain the coating.

[0054] The preparation method of the high-temperature resistant interface agent is as follows: Step a: Phenylacetyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water are reacted under nitrogen, 35°C and 300 rpm for 1 hour, then heated to 80°C and reacted for 60 minutes, and then cooled to 60°C to obtain a prepolymer, wherein the weight ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water is 10:10:10:80:0.5:1.8:15; Step b: Disperse the prepolymer and hydrogen-containing silicone oil under nitrogen at 1000 rpm for 5 min, then add platinum catalyst and continue dispersing for 8 min, then add toluene to obtain a high-temperature resistant interface agent with a solid content of 50% and a viscosity of 140 mPa·s, wherein the weight ratio of prepolymer, hydrogen-containing silicone oil and platinum catalyst is 100:5:0.1.

[0055] The plasma treatment uses a mixture of argon and oxygen in a volume ratio of 4:1, with a power of 400W and a treatment time of 10s; the flame treatment uses a natural gas flame with a flame temperature of 900℃ and an exposure time of 0.5s, and is performed twice.

[0056] The coating thickness of the high-temperature resistant interface agent is 10 μm; the coating thickness of the high-temperature resistant coating is 110 μm, and the coating is cured in a gradient manner: 80℃×1h, 150℃×1h, 250℃×2h.

[0057] Comparative Example 2 An organic elastomer surface treatment method, wherein the moisture-resistant composite additive is replaced by commercially available potassium titanate whiskers, and all other aspects are the same as in Example 1.

[0058] Comparative Example 3 An organic elastomer surface treatment method, wherein the high-temperature resistant interface agent is replaced by commercially available silane coupling agent KH-550, and all other aspects are the same as in Example 1.

[0059] Comparative Example 4 An organic elastomer surface treatment method omits the step of creating active sites on the organic elastomer surface by plasma or flame method, and the rest is the same as in Example 1.

[0060] Comparative Example 5 An organic elastomer surface treatment method, wherein the heat-resistant composite additive is replaced by commercially available potassium titanate whiskers, the high-temperature resistant interface agent is replaced by commercially available silane coupling agent KH-550, and the step of creating active sites on the organic elastomer surface by plasma or flame method is omitted, and the rest is the same as in Example 1.

[0061] Performance testing The selected organic elastomer is fluororubber, a material commonly used in the inner casing of oil wells.

[0062] Destructive strength: Tested in accordance with the requirements of GB / T 5210-2006 "Paints and Varnishes - Pull-off Adhesion Test".

[0063] Adhesion rating: The cross-cut test shall be conducted in accordance with the requirements of GB / T 9286-2021 "Paints and Varnishes Cross-cut Test". The cut spacing shall be 2 mm when the coating thickness is 61 μm-120 μm and 3 mm when the coating thickness is 121 μm-250 μm.

[0064] Moisture and heat resistance: The specimens treated with organic elastomer surface treatment were placed at a temperature of 350±5℃, relative humidity of 95±5%, and 20MPa for 7 days. The specimens were observed for blistering, cracking, peeling, etc., and the retention rate of breaking strength was tested.

[0065] The performance test results are shown in Table 1. Figure 1-2 As shown.

[0066] Table 1 Performance Test Results From Table 1 and Figure 1 , 2 It can be seen that the adhesion and damp heat resistance of Comparative Example 1 are significantly reduced compared with the example. This is mainly due to the severe deficiency of the content of its key components and the complete deviation of the preparation process. These defects together weaken the cohesive strength and interfacial bonding ability of the coating. Under high temperature, high humidity and high pressure environment, water vapor quickly penetrates to the interface, causing blistering, micro-cracks and adhesion failure, and the destructive strength is significantly reduced.

[0067] From Table 1 and Figure 1 , 2 It is evident that the damp heat resistance and adhesion of Comparative Example 2 decreased compared to the Example. This is because Comparative Example 2 used commercially available potassium titanate whiskers directly to replace the damp heat resistant composite additive, resulting in a performance degradation due to the lack of multi-component, multi-layered synergistic protection. Due to the absence of an Al-OP-Si chemical grafting layer, the potassium titanate whiskers and resin matrix only exhibit physical mixing without chemical bonding, leading to a low interfacial bonding energy. Under damp heat conditions, water molecules readily wet the surface of the hydrophilic whiskers, forming continuous penetration channels along the whisker-resin interface, accelerating interfacial hydrolysis and coating blistering. Unmodified whiskers cannot participate in the construction of a three-dimensional cross-linked network, resulting in discontinuous stress transmission within the coating, leading to the initiation and propagation of microcracks under temperature and pressure cycling. The absence of a heat-resistant aluminum dihydrogen phosphate protective layer on the whisker surface exacerbates interfacial debonding at high temperatures due to the difference in thermal expansion coefficients between the whiskers and resin, significantly reducing adhesion and failing to meet damp heat resistance standards.

[0068] From Table 1 and Figure 1 , 2 It can be seen that the damp heat resistance and adhesion of Comparative Example 3 decreased compared to the examples. This is because Comparative Example 3 used silane coupling agent KH-550 instead of the high-temperature resistant interface agent, resulting in the interface bonding mechanism changing from strong chemical cross-linking to weaker physical adsorption and a small number of single-point bonds. The high-temperature resistant interface agent contains various functional groups such as phenyl and vinyl groups, and can undergo extensive chemical cross-linking reactions with the active sites of the substrate and functional groups (such as Si-H bonds) in the coating to form a strong network structure. KH-550, as a small molecule coupling agent, can bond with the substrate, but its molecular structure and reactive sites are limited, and it cannot form the same strong and tough interface layer. In high temperature and high humidity environments, water molecules can more easily penetrate and destroy this weak interface bonding, leading to local blistering or even sheet-like peeling of the coating, resulting in a sharp deterioration in adhesion.

[0069] From Table 1 and Figure 1 , 2 It is evident that the performance of Comparative Example 4 is severely degraded compared to the Examples because the crucial surface activation step of plasma or flame treatment was completely omitted. The fundamental purpose of this step is to create numerous active sites, such as hydroxyl and carboxyl groups, on the surface of the inert organic elastomer. These active sites are the basis for the subsequent strong chemical bonding (such as Si-OC covalent bonds) between the interface agent and the matrix. Without this step, the inherent characteristics of the organic elastomer—low surface energy and strong chemical inertness—are not improved. Even with a high-temperature resistant interface agent, effective wetting and firm chemical anchoring are difficult to achieve; the high-temperature resistant interface agent is more of a physical adhesion. Under extreme conditions of high temperature, high pressure, and high humidity, moisture will rapidly penetrate and accumulate along this weak interface, leading to large-area blistering and peeling of the coating, resulting in extremely low destructive strength.

[0070] From Table 1 and Figure 1 , 2 It is evident that, compared to the examples, Comparative Example 5 exhibits the most severe decline in humid heat resistance and adhesion. This is because Comparative Example 5 simultaneously suffers from three defects: unmodified potassium titanate whiskers, KH-550 interface agent substitution, and lack of surface activation. These defects create a synergistic negative effect. The absence of active sites on the surface prevents the interface agent from chemically anchoring, the decomposition and carbonization of KH-550 at high temperatures further weakens the interfacial bonding, and the unmodified whiskers become rapid channels for moisture penetration. The combined effect of these three factors causes a complete collapse of the overall structural integrity of the coating system, from the substrate to the interface and then to the coating itself. Under humid heat conditions, moisture penetrates unimpeded from the elastomer surface, diffuses along the carbonized brittle interfacial layer, and migrates into the coating interior through the hydrophilic whisker network, causing overall coating swelling, internal stress concentration, and structural damage. Due to the lack of any effective chemical bonding or reinforcement mechanism, the coating rapidly fails in high-pressure steam environments, resulting in a catastrophic decline in humid heat resistance and adhesion.

[0071] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for surface treatment of organic elastomers, characterized in that, Includes the following steps: (1) Active sites are created on the surface of organic elastomers by means of plasma or flame methods; (2) Treat the surface with a high-temperature resistant interface agent so that the active sites are combined with the high-temperature resistant interface agent; (3) Apply the high-temperature resistant coating to the surface of the organic elastomer so that the high-temperature resistant coating is combined with the high-temperature resistant interface agent on the surface of the organic elastomer.

2. The method for surface treatment of organic elastomers according to claim 1, characterized in that, The high-temperature resistant coating comprises the following raw materials in parts by weight: 45-55 parts of silicone resin, 8-10 parts of toughening agent, 6-8 parts of moisture-resistant composite additive, 15-20 parts of curing agent, 0.5-0.8 parts of defoamer, and 30-35 parts of solvent.

3. The method for surface treatment of organic elastomers according to claim 2, characterized in that, The preparation method of the anti-humid heat composite additive is as follows: Step A: Add potassium titanate whiskers and talc powder to anhydrous ethanol and ultrasonically disperse for 30-40 min. Adjust the pH to 3.5-4.0, raise the temperature to 65-70℃, add γ-aminopropyltriethoxysilane solution, and then react for 2.5-3 h to obtain intermediate product 1. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 85-90℃, keep the temperature for 3-4 hours, and then proceed with post-treatment to obtain intermediate product 2. Step C: Perform gradient drying on intermediate product 2. First stage: pre-dry at 75-85℃ for 110-130 min; second stage: cure at 145-155℃ for 110-130 min; third stage: cure at 215-225℃ for 80-100 min to obtain intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide for 10-12 minutes, then add zinc oxide and continue mixing for 5-10 minutes. Then add boron nitride and perform post-treatment to obtain the anti-humid heat composite additive.

4. The organic elastomer surface treatment method according to claim 3, characterized in that, In step A, the mass ratio of potassium titanate whiskers, talc, γ-aminopropyltriethoxysilane, and anhydrous ethanol is 25-30:12-15:1.5-2:76-95; the concentration of the γ-aminopropyltriethoxysilane solution is 4.5-5.5% using anhydrous ethanol as the solvent; in step B, the mass ratio of aluminum dihydrogen phosphate to potassium titanate whiskers in step A is 4-6:25-30; the concentration of the aluminum dihydrogen phosphate solution is 18-22% using deionized water as the solvent; in step D, the mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step A is 0.8-1.2:1.6-2.4:2-3:15-18:25-30.

5. The method for surface treatment of organic elastomers according to claim 2, characterized in that, The toughening agent is one or more of short carbon fiber, zirconium oxide fiber, aluminum silicate fiber, and polycrystalline mullite fiber; the curing agent is an isocyanate curing agent; the defoamer is an organosilicon defoamer; and the solvent is xylene.

6. The method for surface treatment of organic elastomers according to any one of claims 1-5, characterized in that, The preparation method of the high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing them to a fineness ≤30μm, adding curing agent, stirring for 15-20min, and maturing for 20-30min to obtain the coating.

7. The method for surface treatment of organic elastomers according to claim 1, characterized in that, The preparation method of the high-temperature resistant interface agent is as follows: Step a: Phenylacetyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid and deionized water are reacted under nitrogen and 35±1℃ for 9.5-10.5h, then heated to 75-85℃ for 50-70min, and cooled to 55-65℃ to obtain the prepolymer; Step b: Disperse the prepolymer and hydrogen-containing silicone oil for 15-25 minutes, then add platinum catalyst and continue dispersing for 5-10 minutes, then add toluene to obtain a high-temperature resistant interface agent.

8. The method for surface treatment of organic elastomers according to claim 7, characterized in that, In step a, the weight ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, toluene, antioxidant, oxalic acid, and deionized water is 55:13-17:8-12:75-85:0.4-0.6:1.5-2:10-15; in step b, the weight ratio of prepolymer, hydrogen-containing silicone oil, and platinum catalyst is 100:8-9:0.15-0.2, the solid content of the high-temperature resistant interface agent is 45-55%, and the viscosity is 100-160 mPa·s.

9. The method for surface treatment of organic elastomers according to claim 1, characterized in that, The plasma treatment uses a mixture of argon and oxygen gas with a power of 300-500W and a treatment time of 60-120s; the flame treatment uses a natural gas flame with a flame temperature of 800-1000℃ and an exposure time of 1-3s.

10. The method for surface treatment of an organic elastomer according to claim 1, characterized in that, The coating thickness of the high-temperature resistant interface agent is 8-15μm, and after surface drying at room temperature, it is cured at 60-80℃ for 1.5-2.5h; the coating thickness of the high-temperature resistant coating is 80-150μm, and after application, it is cured in a gradient manner: 75-85℃×1h, 145-155℃×1h, 245-255℃×2h, 345-355℃×3h.

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