Temperature-resistant and corrosion-resistant fluororubber-nylon composite belt and preparation method thereof

Abstract

The application relates to a temperature-resistant and corrosion-resistant fluororubber-nylon composite tape and a preparation method thereof. The composite tape comprises a nylon tape substrate, a glue layer and a fluororubber coating layer. The nylon tape substrate is subjected to alkali reduction treatment and infrared modification treatment. The glue layer comprises the following components in parts by weight: carboxylated polyamide resin 60-80 parts, hydroxylated polyamide resin 10-20 parts and epoxy silane coupling agent 5-10 parts. The fluororubber coating layer is formed through secondary photocuring crosslinking and comprises the following components in parts by weight: liquid fluororubber containing a photocurable functional group 70-85 parts, epoxy-modified liquid fluororubber 10-20 parts, photoinitiator 1.5-5 parts and active diluent 5-10 parts. The application combines the modification of the nylon substrate, the bridging of the bipolar polyamide in the glue layer and the interpenetrating network structure of the fluororubber layer, so that the coating layer and the substrate have excellent peeling strength, the combination strength retention rate is excellent under a high-temperature corrosion environment, and the problems of high energy consumption and incomplete vulcanization in the heat vulcanization process are avoided.

Description

Technical Field

[0001] This application relates to the field of polymer composite materials technology, and in particular to a temperature- and corrosion-resistant fluororubber-nylon composite tape and its preparation method. Background Technology

[0002] In drilling operations for oil, natural gas, and deep geothermal resources, the drill bit is installed at the very tip of the drill string, penetrating thousands of meters below the surface to directly break through rock formations. The drill bit typically requires the fixing or securing of various components, such as sensor wiring, measuring instrument harnesses, hydraulic lines, or wear-resistant protective elements. The working environment at this location is extremely harsh: temperatures can reach 200°C and above, while simultaneously enduring direct scouring from highly corrosive media such as high concentrations of hydrogen sulfide, carbon dioxide, and drilling fluid chemical additives, accompanied by severe vibration and impact. Ordinary binding and fixing materials (such as conventional nylon cable ties, metal cable ties, and ordinary rubber cable ties) cannot simultaneously withstand such ultra-high temperatures and strong chemical corrosion, easily leading to aging and brittleness, stress relaxation, corrosion fracture, or loosening and detachment. This can cause drill bit sensor failure, signal interruption, or even damage to the drill bit itself, resulting in serious downhole accidents and economic losses.

[0003] To improve the temperature and corrosion resistance of drill bit binding tapes, the industry has been exploring the combination of fluororubber and high-strength nylon substrates to create fluororubber-nylon composite tapes. Existing technologies typically employ high-temperature, long-duration thermal vulcanization processes (such as peroxide or bisphenol vulcanization systems) to cross-link the fluororubber onto the nylon surface. However, this process has significant drawbacks: firstly, it is energy-intensive, requires substantial equipment investment, and has a vulcanization cycle lasting several hours, significantly increasing production costs; secondly, the vulcanization process releases sulfur-containing byproducts and volatile organic compounds, failing to meet environmental protection requirements; and thirdly, for thin, long composite tapes, thermal vulcanization struggles to achieve uniform cross-linking, easily resulting in incomplete vulcanization in localized areas. Drill bit tapes, operating under vibration and high-temperature corrosion, require extremely high material uniformity, and any localized defects can lead to premature failure of the entire tape downhole. Furthermore, the natural bonding between fluororubber and the highly polar nylon is poor, and existing surface treatment methods (such as simple acid-base etching) have limited effectiveness, further exacerbating the reliability risks associated with uneven vulcanization.

[0004] Therefore, for composite tape products used to fix components such as sensors and pipelines in the working environment of drill bits (high temperature, high pressure, strong corrosion, strong vibration), how to abandon the traditional hot vulcanization process, simplify the production process, reduce energy consumption costs, and achieve environmentally friendly manufacturing, while ensuring that the fluororubber coating and the nylon substrate have high and uniform bonding strength, so that the composite tape can maintain its complete and tight fixing function under long-term high temperature of 200°C and above, erosion by corrosive media such as hydrogen sulfide, and continuous vibration and impact, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To improve the high-temperature resistance and corrosion resistance of fluororubber-nylon composite tapes, this application provides a high-temperature and corrosion-resistant fluororubber-nylon composite tape and its preparation method.

[0006] In a first aspect, this application provides a temperature- and corrosion-resistant fluororubber-nylon composite tape, employing the following technical solution: A temperature- and corrosion-resistant fluororubber-nylon composite tape includes a nylon tape substrate, an adhesive layer, and a fluororubber coating. The adhesive layer is coated on the surface of the nylon tape substrate, and the fluororubber coating is coated on the adhesive layer. The nylon tape substrate undergoes alkali reduction treatment and infrared modification treatment. The adhesive layer comprises the following components in parts by weight: 60-80 parts of carboxylated polyamide resin, 10-20 parts of hydroxylated polyamide resin, and 5-10 parts of epoxy-modified silane coupling agent. The fluororubber coating is formed by secondary photocuring and cross-linking, and comprises the following components in parts by weight: 70-85 parts of liquid fluororubber containing photocurable functional groups, 10-20 parts of epoxy-modified liquid fluororubber, 1.5-5 parts of photoinitiator, and 5-10 parts of reactive diluent.

[0007] The inventors discovered that by using nylon tape modified by a combination of alkali reduction and infrared radiation as the substrate, combined with an adhesive layer composed of carboxylated polyamide resin, hydroxylated polyamide resin and epoxy silane coupling agent, and a fluororubber coating that has been cross-linked by secondary photocuring, the resulting fluororubber-nylon composite tape exhibits significantly better interfacial bonding strength than conventional processes. It maintains excellent adhesion stability even after long-term service in high-temperature and highly corrosive environments, and completely avoids the problems of high energy consumption and incomplete vulcanization associated with traditional hot vulcanization processes.

[0008] Analysis suggests this may be due to: alkali reduction treatment causing controlled hydrolysis of amide groups on the nylon surface, generating carboxyl and amino groups and forming a microscopically rough structure; and infrared modification further increasing the proportion of amorphous regions on the surface and improving the accessibility of polar groups. The combination of these two factors creates a high-density chemical reaction sites and a physical anchoring structure on the nylon surface, providing a dual basis for covalent bonding and mechanical locking of the adhesive layer. In the adhesive layer, carboxylated polyamides combine with carboxyl and amino groups on the nylon surface to form covalent bonds; hydroxylated polyamides construct a dense hydrogen bond network with abundant hydroxyl groups and act as a polar transition layer to reduce interfacial tension; the siloxane at one end of the epoxy silane coupling agent hydrolyzes to form silanol, which condenses with hydroxyl and carboxyl groups on the nylon and polyamide surfaces to form covalent bonds, thereby anchoring epoxy groups on the surfaces of nylon and polyamide. The epoxy groups undergo ring-opening addition with the epoxy-modified liquid fluororubber in the fluororubber layer and the residual carboxyl groups in the adhesive layer, thereby forming a strong and tough connection network with covalent bonds as the main component and hydrogen bonds as the auxiliary component inside the adhesive layer and at both interfaces. In fluororubber coatings, photocurable liquid fluororubber with functional groups undergoes rapid free radical polymerization under the action of a photoinitiator, forming a dense cross-linked framework that ensures the coating's temperature and corrosion resistance. Epoxy-modified liquid fluororubber, on the one hand, chemically bonds with the epoxy silane coupling agent and carboxyl groups in the adhesive layer, enhancing interfacial adhesion; on the other hand, it undergoes cationic polymerization or further cross-linking in the second step of secondary photocuring, forming a second cross-linked structure interpenetrating with the acrylate network. In the secondary photocuring process, the first long-wavelength ultraviolet light (nitrogen protection) achieves deep and sufficient free radical cross-linking, avoiding oxygen-induced polymerization inhibition; the second short-wavelength ultraviolet light (air environment) densifies the surface layer, activates the secondary epoxy group reaction, and releases internal stress, ensuring a uniform and complete transformation of the coating from the interface to the surface, without the localized unevenness defects of traditional vulcanization.

[0009] This application achieves a peel strength between the fluororubber coating and the nylon substrate that is far higher than conventional levels through dual modification of the nylon substrate, polarity transition and chemical bridging of the adhesive layer, interpenetrating network design of the fluororubber coating, and precise control of secondary photocuring. It also maintains long-term stability under harsh conditions such as high temperature, corrosive media and vibration and shock, while completely eliminating the inherent drawbacks of the hot vulcanization process.

[0010] In one specific implementation scheme, the treatment steps for the alkali-reduced nylon tape substrate are as follows: The nylon tape substrate is immersed in a 40-80 g / L sodium hydroxide aqueous solution for treatment, and after washing and drying, the nylon tape substrate treated with alkali reduction is obtained.

[0011] By using the above steps, the amide groups on the surface of the nylon tape substrate undergo controlled hydrolysis to generate polar groups such as carboxyl and amino groups, forming a micro-rough structure. This provides covalent bonding sites and mechanical locking interfaces for the adhesive layer, significantly improving the adhesion strength of subsequent coatings.

[0012] In one specific implementation, the processing steps of the infrared-modified nylon tape substrate are as follows: The nylon tape substrate that has undergone alkali reduction treatment is irradiated with an infrared radiation source with a wavelength of 2-4 μm to obtain the nylon tape substrate that has undergone infrared modification treatment.

[0013] By employing the above steps to treat the alkali-reduced nylon tape substrate, the surface molecular chain motion is selectively excited, the proportion of amorphous regions increases, the already generated polar groups are further exposed and their activity is improved, and at the same time, the wettability of the adhesive to the substrate is enhanced, making the bond between the adhesive layer and the nylon more uniform and firm.

[0014] In one specific implementation, the photocurable functional group in the liquid fluororubber containing photocurable functional groups is selected from one or more of acrylate groups, methacrylate groups, and acrylamide groups; more preferably, the liquid fluororubber containing photocurable functional groups is an acrylate-terminated liquid fluororubber.

[0015] The inventors discovered that acrylate, methacrylate, and acrylamide groups can all undergo rapid free radical polymerization under ultraviolet light irradiation, making them highly compatible with the photoinitiator system and secondary photocuring process used in this invention. Among them, the acrylate group exhibits the highest reactivity and fastest curing speed, forming a dense cross-linked network in a short time, thus endowing the fluororubber coating with excellent temperature resistance and corrosion resistance. The methacrylate group has a slightly slower curing speed but less volume shrinkage, making it suitable for applications requiring higher dimensional stability. The acrylamide group, due to its amide structure, can provide additional hydrogen bonding, helping to enhance the interfacial compatibility between the coating and the adhesive layer. The acrylate-terminated liquid fluororubber is further preferred because it exhibits the best overall performance in terms of curing efficiency, cross-linking density, and synergistic effect with epoxy-modified liquid fluororubber.

[0016] In one specific implementation, the epoxy silane coupling agent is KH-560.

[0017] By adopting the above technical solution, the trimethoxysilane end in the KH-560 molecule undergoes hydrolysis and condenses with the hydroxyl and carboxyl groups on the surface of nylon and polyamide to form a strong silicon-oxygen bond. The epoxy group at its end undergoes ring-opening addition with the epoxy-modified liquid fluororubber in the fluororubber layer and the residual carboxyl groups in the adhesive layer, thereby building a stable chemical bridge between the nylon substrate and the fluororubber coating, which significantly improves the interfacial bonding strength.

[0018] In one specific embodiment, the photoinitiator is selected from one or both of 2-hydroxy-2-methyl-1-phenyl-1-propanone and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide; more preferably, the photoinitiator comprises 2-hydroxy-2-methyl-1-phenyl-1-propanone and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, wherein the weight ratio of 2-hydroxy-2-methyl-1-phenyl-1-propanone to phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is 1:(0.2-1).

[0019] The inventors discovered that 2-hydroxy-2-methyl-1-phenyl-1-propanone (i.e., photoinitiator 1173) and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (i.e., photoinitiator 819) are both suitable for the free radical photocuring system in this invention, but they have different absorption wavelengths: 1173 has a main absorption peak of about 245 nm, focusing on surface curing; 819 has a main absorption peak of about 370 nm, which can penetrate deep into the coating to initiate polymerization. When 1173 is used alone, due to the limited penetration ability of short-wavelength ultraviolet light, the deep layer of the coating is prone to incomplete curing, resulting in insufficient crosslinking density of fluororubber and decreased temperature and corrosion resistance. When 819 is used alone, although deep curing is good, the surface layer is not dry and is sticky due to oxygen inhibition, affecting product use. Combining the two can achieve complementary curing of the surface and deep layers.

[0020] Further optimization of the weight ratio of the two components to 1:(0.2-1) is based on an equilibrium range determined through extensive testing. Deviations from this range may lead to the following risks: When the 1173 ratio is too high, the system is dominated by short-wavelength initiation, resulting in insufficient deep-layer light absorption. The crosslinking density decreases gradient along the thickness direction, leading to a "hard on top, soft on the bottom" structural defect within the coating. After immersion in high temperatures or corrosive media, internal stress tends to concentrate at the interface, causing blistering or localized peeling of the coating. Simultaneously, the incompletely crosslinked fluororubber molecular chains in the deep layers are highly mobile, reducing their ability to resist corrosive media. When the 819 ratio is too high, long-wavelength initiation dominates. Although deep curing is good, the surface layer lacks sufficient short-wavelength ultraviolet light excitation, and the inhibitory effect of oxygen in the air easily forms a sticky, incompletely cured layer. This not only affects the winding and feel of the composite tape but also, under the high-temperature vibration environment of the drill bit, the uncured surface layer may adhere to impurities or experience cold flow, damaging the integrity of the coating and allowing corrosive media to penetrate the interface. Therefore, by limiting the weight ratio of the two to within the range of 1:(0.2-1), an ideal coating with sufficient surface hardening, uniform deep cross-linking, and overall dense curing can be obtained, ensuring the temperature and corrosion resistance and long-term interface stability of the composite tape.

[0021] In one specific implementation, the reactive diluent is selected from one or both of trimethylolpropane triacrylate and pentaerythritol tetraacrylate.

[0022] By employing the above-mentioned technical solutions, both trimethylolpropane triacrylate and pentaerythritol tetraacrylate are multifunctional reactive diluents. They not only effectively reduce the application viscosity of fluororubber compositions and improve coating flowability, but also, due to the presence of three or four acrylate double bonds in their molecular structure, can participate in free radical polymerization reactions under ultraviolet light irradiation, forming a highly cross-linked three-dimensional network with acrylate-terminated liquid fluororubber. Compared to monofunctional or difunctional diluents, multifunctional reactive diluents significantly improve the cross-linking density and solvent resistance of fluororubber coatings, reduce molecular chain slippage at high temperatures, and thus enhance long-term temperature resistance. Furthermore, pentaerythritol tetraacrylate has higher functionality and denser cross-linking, but its brittleness is slightly increased; trimethylolpropane triacrylate, on the other hand, has better flexibility. Both can be selected or mixed as needed to balance the coating's hardness and toughness. Using these two types of reactive diluents also enhances interfacial compatibility with polar groups in the adhesive layer, preventing a decrease in interlayer adhesion due to diluent migration. Therefore, the selection of TMPTA and / or PETTA in this solution can effectively improve the crosslinking density, temperature and corrosion resistance, and bonding uniformity of the fluororubber coating with the adhesive layer while ensuring the coating's application performance.

[0023] Secondly, this application provides a method for preparing a temperature- and corrosion-resistant fluororubber-nylon composite tape, using the following technical solution: A method for preparing a temperature- and corrosion-resistant fluororubber-nylon composite tape includes the following steps: S1. The nylon tape substrate is subjected to alkali reduction treatment and infrared modification treatment in sequence to obtain a nylon tape substrate with modified surface. S2. The surface of the modified nylon tape substrate obtained in step S1 is coated with an adhesive layer composition to form an adhesive layer. S3. A fluororubber coating composition is coated on the surface of the adhesive layer obtained in step S2, and a second photocuring is performed to form a fluororubber coating, thereby obtaining the temperature-resistant and corrosion-resistant fluororubber-nylon composite tape.

[0024] The fluororubber-nylon composite tape prepared by the above steps has extremely high peel strength between the fluororubber coating and the nylon substrate. After long-term use in high temperature and strong corrosion environment, the bonding strength retention rate is excellent, and there are no defects such as incomplete vulcanization or uneven local performance that are common in traditional hot vulcanization processes.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. This application employs a combination of alkali reduction and infrared radiation to modify the nylon tape substrate, simultaneously constructing a high-density chemical reaction site and physical anchoring structure on the nylon surface. This provides a dual adhesion basis for the adhesive layer, consisting of covalent bonding and mechanical locking, thereby significantly improving the interfacial bonding strength between the fluororubber coating and the nylon substrate.

[0026] 2. This application employs an adhesive layer composed of carboxylated polyamide resin, hydroxylated polyamide resin, and epoxy silane coupling agent, combined with a synergistic combination of photocurable liquid fluororubber and epoxy-modified liquid fluororubber. Through secondary photocuring and cross-linking, an interpenetrating network structure is formed, which enables the fluororubber coating to achieve a peel strength far exceeding conventional levels between the coating and the nylon substrate, and maintains long-term stability under high temperature, strong corrosion, and vibration impact environments.

[0027] 3. This application utilizes a photoinitiator system composed of 2-hydroxy-2-methyl-1-phenylpropanone and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide. By taking advantage of the difference in their absorption wavelengths—the former mainly absorbs short wavelengths and focuses on surface curing, while the latter mainly absorbs long wavelengths and can penetrate deep into the coating to initiate polymerization—uniform crosslinking of the fluororubber coating from the surface to the depth is achieved. This effectively avoids problems such as surface stickiness, incomplete deep curing, or uneven crosslinking density gradient caused by a single photoinitiator. Thus, it completely replaces the traditional hot vulcanization process, overcomes its defects of high energy consumption, incomplete vulcanization, and uneven local performance, while reducing production costs and improving environmental friendliness. Detailed Implementation

[0028] The present application will be further described in detail below with reference to embodiments and comparative examples: Some of the raw materials used in the examples and comparative examples: Liquid fluororubber (brand name: DAI-EL G-101, purchased from Daikin brand flagship store).

[0029] Dimer acid (item number: D858224); 2-hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173, CAS: 7473-98-5); phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (photoinitiator 819, CAS: 162881-26-7); trimethylolpropane triacrylate (CAS: 15625-89-5); benzyltriethylammonium chloride (CAS: 56-37-1) were all purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0030] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available products.

[0031] Preparation Example 1 The processing steps for nylon tape substrates subjected to alkali reduction treatment are as follows: The nylon tape substrate was immersed in a 60 g / L sodium hydroxide aqueous solution, heated to 85°C for 20 minutes, removed and repeatedly washed with deionized water until the surface pH was neutral, and then placed in an 80°C oven to dry for 30 minutes to obtain the nylon tape substrate treated with alkali reduction.

[0032] Preparation Example 2 The processing steps for infrared-modified nylon tape substrate are as follows: The nylon tape substrate was laid flat in an infrared radiation device and irradiated for 10 minutes at a distance of 15 cm using an infrared radiation source with a wavelength of 3 μm. During the irradiation process, the surface temperature of the substrate was kept at 135℃. After the irradiation was completed, the substrate was allowed to cool naturally to room temperature to obtain the nylon tape substrate that had undergone infrared modification treatment.

[0033] Preparation Example 3 The continuous processing steps involving alkali reduction treatment and infrared modification treatment are as follows: The nylon tape substrate was immersed in a 60 g / L sodium hydroxide aqueous solution and heated to 85°C for 20 minutes. After removal, it was repeatedly washed with deionized water until the surface pH was neutral. Then, it was placed in an 80°C oven and dried for 30 minutes to obtain the nylon tape substrate treated with alkali reduction. The nylon tape substrate treated with alkali reduction was laid flat in an infrared radiation device and irradiated for 10 minutes at a distance of 15 cm using an infrared radiation source with a wavelength of 3 μm. During the irradiation, the surface temperature of the substrate was kept at 135°C. After the irradiation, it was naturally cooled to room temperature to obtain the nylon tape substrate treated with infrared modification.

[0034] Preparation Example 4 The preparation of carboxylated polyamide resin is as follows: 100 parts by weight of dimer acid and 20 parts by weight of hexamethylenediamine were added to a reaction vessel, along with 1 part by weight of benzoic acid. Under nitrogen protection, the mixture was heated to 170°C and stirred for 2 hours. The temperature was then increased to 230°C, and the reaction continued for 3 hours. After the reaction was complete, a vacuum was applied to -0.09 MPa and maintained for 30 minutes. The temperature was then lowered to 160°C, and 20 parts by weight of adipic acid were added. The mixture was stirred and reacted for another 2 hours. After the reaction was complete, the product was discharged hot, cooled to room temperature, and then pulverized to obtain carboxylated polyamide resin.

[0035] Preparation Example 5 The preparation of hydroxylated polyamide resin is as follows: 100 parts by weight of dimer acid, 15 parts by weight of hexamethylenediamine, and 10 parts by weight of diethanolamine were added to a reaction vessel, along with 1 part by weight of benzoic acid. Under nitrogen protection, the mixture was stirred at 170°C for 2 hours, then the temperature was increased to 210°C and the reaction continued for 3 hours. After the reaction was complete, a vacuum of -0.09 MPa was applied and maintained for 30 minutes. After the reaction was finished, the mixture was cooled to room temperature, and the product was pulverized. The product was discharged while hot, cooled to room temperature, and then pulverized again to obtain hydroxylated polyamide resin.

[0036] Preparation Example 6 The preparation of carboxyl-terminated liquid fluororubber is as follows: Under nitrogen protection, 100 parts by weight of liquid fluororubber was dissolved in 400 parts by weight of acetone, and then 3 parts by weight of samarium chloride were added. The mixture was stirred until homogeneous at room temperature. During stirring, 6 parts by weight of sodium borohydride were slowly added, and the reaction was carried out at room temperature for 6 hours. After the reaction was completed, dilute hydrochloric acid was added to quench the reaction. The product was precipitated, washed, and dried to obtain hydroxyl-terminated liquid fluororubber. The hydroxyl-terminated liquid fluororubber was dissolved in a mixed solvent of 300 parts by weight of dichloromethane and 50 parts by weight of deionized water. Under ice bath conditions, 0.5 parts by weight of 2,2,6,6-tetramethylpiperidin-1-oxy and 1.5 parts by weight of sodium bromide were added, and 100 parts by weight of sodium hypochlorite aqueous solution (available chlorine content 12%, pH 10) was added dropwise. After the addition was completed, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was completed, 20 parts by weight of sodium bisulfite were added to reduce excess sodium hypochlorite. The product was precipitated by acidification with 1 mol / L dilute hydrochloric acid to pH=2.5. The organic phase was separated and washed with deionized water until neutral. Dichloromethane was removed by vacuum distillation and the product was dried under vacuum at 60°C for 12 hours to obtain carboxyl-terminated liquid fluororubber.

[0037] Preparation Example 7 The preparation of acrylate-terminated liquid fluororubber is as follows: 100 parts by weight of the carboxyl-terminated liquid fluororubber prepared in Preparation Example 6 were added to a reaction vessel, along with 200 parts by weight of butyl acetate, and stirred until completely dissolved. Then, 20 parts by weight of glycidyl methacrylate, 1 part by weight of p-toluenesulfonic acid, and 0.2 parts by weight of hydroquinone were added, and the mixture was stirred at 90°C for 6 hours under nitrogen protection. The acid value was measured every hour during the reaction, and the reaction was stopped when the acid value dropped to less than 10% of the initial acid value. After the reaction was completed, the temperature was lowered to 50°C, and the reaction solution was washed with deionized water until neutral. After separation, the organic phase was collected, and the solvent was removed by vacuum distillation at 70°C and -0.09 MPa to obtain acrylate-terminated liquid fluororubber.

[0038] Preparation Example 8 The preparation of epoxy-modified liquid fluororubber is as follows: 100 parts by weight of the carboxyl-terminated liquid fluororubber prepared in Preparation Example 6 were added to a reaction vessel, along with 200 parts by weight of butyl acetate, and stirred until completely dissolved. Then, 15 parts by weight of epichlorohydrin, 1 part by weight of tetrabutylammonium bromide, and 0.5 parts by weight of sodium hydroxide were added. The mixture was stirred at 80°C for 5 hours under nitrogen protection. The epoxy value was measured every hour during the reaction, and the reaction was stopped when the epoxy value reached more than 90% of the theoretical value. After the reaction was completed, the temperature was lowered to 50°C, and the reaction solution was washed with deionized water until neutral. After separation, the organic phase was collected, and the solvent was removed by vacuum distillation at 70°C and -0.09 MPa to obtain epoxy-modified liquid fluororubber. Example Example

[0039] The preparation of temperature- and corrosion-resistant fluororubber-nylon composite tape includes the following steps: S1. 70 parts by weight of the carboxylated polyamide resin prepared in Preparation Example 4, 15 parts by weight of the hydroxylated polyamide resin prepared in Preparation Example 5, and 7.5 parts by weight of KH-560 are mixed to form an adhesive layer composition. S2. 77.5 parts by weight of the acrylate-terminated liquid fluororubber prepared in Preparation Example 7, 15 parts by weight of the epoxy-modified liquid fluororubber prepared in Preparation Example 8, 2 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1.2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and 7.5 parts by weight of trimethylolpropane triacrylate are mixed to form a fluororubber coating composition. S3. The adhesive layer composition prepared in S1 is coated onto the surface of the nylon tape substrate prepared in Preparation Example 3 after alkali reduction treatment and infrared modification. The wet film thickness is controlled at 15 μm, and the dry film thickness reaches 12 μm. After coating, it is placed in a 90°C oven for pre-baking for 3 minutes to allow the solvent to evaporate and initially cure, forming an adhesive layer. S4. The adhesive layer obtained in step S3 is coated with the fluororubber coating composition obtained in step S2. The wet film thickness is controlled at 165 μm, and the dry film thickness reaches 125 μm. A second light curing process is performed (first curing: under nitrogen protection, using a UV-LED light source with a wavelength of 365 nm, a light intensity of 1000 mW / cm², an irradiation distance of 10 cm, and an irradiation time of 2 minutes, to fully cross-link the deep layers of the coating with free radicals; second curing: in an air environment, using a low-pressure mercury lamp with a wavelength of 254 nm, a light intensity of 200 mW / cm², an irradiation distance of 15 cm, and an irradiation time of 5 minutes, to densify the coating surface and activate the secondary reaction of epoxy groups) to form a fluororubber coating. After curing, it is naturally cooled to room temperature, wound up, and a temperature- and corrosion-resistant fluororubber-nylon composite tape is obtained. Example

[0040] The difference between Example 2 and Example 1 is that in step S2 of Example 2, 2 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1.2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide are replaced with 3.2 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone. Example

[0041] The difference between Example 3 and Example 1 is only that in step S2 of Example 3, 2 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1.2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide are replaced with 3.2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. Example

[0042] The difference between Example 4 and Example 1 is only that in step S2 of Example 4, 2 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1.2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide are replaced with 3 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 0.2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. Example

[0043] The difference between Example 5 and Example 1 is only that in step S2 of Example 5, 2 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1.2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide are replaced with 1 part by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 2.2 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0044] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that in step S3 of Comparative Example 1, the adhesive layer composition prepared in S1 is coated on the surface of the nylon tape substrate prepared in Example 3 after alkali reduction treatment and infrared modification, instead of coating the surface of the nylon tape substrate prepared in Example 1 after alkali reduction treatment with the adhesive layer composition prepared in S1.

[0045] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that in step S3 of Comparative Example 2, the adhesive layer composition prepared in S1 is coated on the surface of the nylon tape substrate prepared in Example 3 after alkali reduction treatment and infrared modification, instead of coating the surface of the nylon tape substrate prepared in Example 2 after infrared modification.

[0046] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that in step S1 of Comparative Example 3, 70 parts by weight of the carboxylated polyamide resin prepared in Preparation Example 4 and 15 parts by weight of the hydroxylated polyamide resin prepared in Preparation Example 5 are replaced with 85 parts by weight of the carboxylated polyamide resin prepared in Preparation Example 4.

[0047] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that in step S1 of Comparative Example 4, 70 parts by weight of the carboxylated polyamide resin prepared in Preparation Example 4 and 15 parts by weight of the hydroxylated polyamide resin prepared in Preparation Example 5 are replaced with 85 parts by weight of the carboxylated polyamide resin prepared in Preparation Example 4.

[0048] The fluororubber-nylon composite tapes prepared in each embodiment and comparative example were subjected to performance tests according to the following standards: 1. Peel strength: Tested according to GB / T 2792-2014 (or ASTM D3330) using the 90° peel method, and record the maximum force value when the coating is peeled from the nylon substrate.

[0049] 2. Tensile strength and elongation at break: Tested according to GB / T 1040.3 (plastic film / strip), using standard dumbbell-shaped specimens, with a tensile rate of 50 mm / min.

[0050] The performance test data under normal conditions are summarized in Table 1: Table 1. Performance test data of fluororubber-nylon composite tapes prepared in each embodiment and comparative example.

[0051] High-temperature aging: Placed in a 200℃ forced ventilation oven for 500 hours, and then equilibrated under standard conditions (23±2℃, 50±5%RH) for 24 hours before testing peel strength, tensile strength and elongation at break.

[0052] The performance test data after high-temperature aging are summarized in Table 2: Table 2. Performance test data of fluororubber-nylon composite tapes prepared in each embodiment and comparative example after high-temperature aging.

[0053] 5. Conduct a 500-hour salt spray test according to GB / T10125, and adjust the acid and alkaline conditions by adjusting the pH. For acidic salt spray, the pH is 3.8-4.0 (usually adjusted with acetic acid); for alkaline salt spray, the pH is 10.8-11 (usually adjusted with NaOH). Then, test the peel strength, tensile strength and elongation at break.

[0054] The performance test data after the salt spray test are summarized in Table 3. Table 3. Performance test data of fluororubber-nylon composite tapes prepared in each embodiment and comparative example after salt spray testing.

[0055] Based on Examples 1-5 and Tables 1-3, it can be seen that Example 1, using a composite photoinitiator system, exhibits superior initial peel strength, peel strength retention after high-temperature aging, and salt spray corrosion resistance compared to Examples 2-5. Example 2, due to the use of a short-wavelength photoinitiator alone, resulted in incomplete deep curing of the coating, leading to a significant performance degradation after aging. Example 3, due to the use of a long-wavelength photoinitiator alone, experienced surface stickiness due to oxygen inhibition, making it prone to impurity adsorption during long-term use. Example 4 suffered from insufficient deep crosslinking density due to an excessively low proportion of long-wavelength photoinitiator. Example 5, due to an excessively low proportion of short-wavelength photoinitiator, resulted in insufficient surface densification. These results demonstrate that controlling the weight ratio of the two photoinitiators within a reasonable range can achieve uniform curing of the fluororubber coating from the surface to the depths, resulting in optimal overall performance.

[0056] Combining Example 1 and Comparative Examples 1-2, and referring to Tables 1-3, it can be seen that Example 1, which uses a combination of alkali reduction and infrared modification to treat the nylon tape substrate, exhibits significantly better interfacial bonding strength and aging resistance than Comparative Example 1 (alkali reduction treatment only) and Comparative Example 2 (infrared modification treatment only). Analysis suggests that alkali reduction treatment generates polar groups and forms a micro-rough structure on the nylon surface, providing covalent bonding sites and mechanical locking interfaces for the adhesive layer; infrared modification further increases the proportion of amorphous regions on the surface, improves the accessibility of polar groups, and enhances the wettability of the adhesive. The combined use of these two methods produces a synergistic effect, and neither modification method alone can achieve the same interfacial bonding effect.

[0057] Combining Example 1 and Comparative Examples 3-4, and referring to Tables 1-3, it can be seen that the adhesive layer of Example 1, which uses a blend of carboxylated and hydroxylated polyamide resins, exhibits significantly better interfacial bonding strength and aging resistance than Comparative Example 3 (carboxylated polyamide resin only) and Comparative Example 4 (hydroxylated polyamide resin only). Analysis suggests that the carboxylated polyamide provides the primary interfacial bonding force by forming covalent bonds with the nylon surface; while the hydroxylated polyamide, although not directly participating in strong covalent reactions, possesses abundant hydroxyl groups that can construct a dense hydrogen bond network and act as a polar transition layer, effectively reducing the interfacial tension between nylon and fluororubber. The combined use of these two materials forms a strong and resilient network characterized by "covalent bonds as the main component and hydrogen bonds as a secondary component," and neither modified polyamide alone can achieve the same synergistic reinforcing effect.

[0058] This application constructs a high-density reaction site and physical anchoring structure by combining alkali reduction and infrared modification of the nylon tape substrate. In the adhesive layer, carboxyl groups and hydroxyl polyamides are compounded and combined with an epoxy silane coupling agent to form a gradient connection network of covalent and hydrogen bonds. In the fluororubber coating, acrylate and epoxy-modified fluororubber work synergistically, and secondary photocuring with a composite photoinitiator achieves uniform coating curing and interfacial chemical anchoring. These features work together to give the fluororubber coating and nylon substrate a peel strength far exceeding conventional levels. Even after long-term use in high-temperature and highly corrosive environments, excellent bonding strength is maintained without interfacial blistering or cracking, while completely avoiding the high energy consumption and incomplete vulcanization defects of traditional hot vulcanization processes.

[0059] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A temperature- and corrosion-resistant fluororubber-nylon composite belt, characterized in that, The material includes a nylon tape substrate, an adhesive layer, and a fluororubber coating. The adhesive layer is coated on the surface of the nylon tape substrate, and the fluororubber coating is coated on the adhesive layer. The nylon tape substrate undergoes alkali reduction treatment and infrared modification treatment. The adhesive layer comprises the following components in parts by weight: 60-80 parts of carboxylated polyamide resin, 10-20 parts of hydroxylated polyamide resin, and 5-10 parts of epoxy silane coupling agent. The fluororubber coating is formed by secondary photocuring and cross-linking, and includes the following components in parts by weight: 70-85 parts of liquid fluororubber containing photocurable functional groups, 10-20 parts of epoxy-modified liquid fluororubber, 1.5-5 parts of photoinitiator, and 5-10 parts of reactive diluent.

2. The temperature-resistant and corrosion-resistant fluororubber-nylon composite tape according to claim 1, characterized in that, The processing steps for the nylon tape substrate subjected to alkali reduction treatment are as follows: The nylon tape substrate is immersed in a 40-80 g / L sodium hydroxide aqueous solution for treatment, and after washing and drying, the nylon tape substrate treated with alkali reduction is obtained.

3. The temperature- and corrosion-resistant fluororubber-nylon composite tape according to claim 2, characterized in that, The processing steps for the infrared-modified nylon tape substrate are as follows: The nylon tape substrate that has undergone alkali reduction treatment is irradiated with an infrared radiation source with a wavelength of 2-4 μm to obtain the nylon tape substrate that has undergone infrared modification treatment.

4. The temperature- and corrosion-resistant fluororubber-nylon composite tape according to claim 1, characterized in that, The photocurable functional groups in the liquid fluororubber containing photocurable functional groups are selected from one or more of acrylate groups, methacrylate groups, and acrylamide groups.

5. The temperature- and corrosion-resistant fluororubber-nylon composite tape according to claim 4, characterized in that, The liquid fluororubber containing photocurable functional groups is an acrylate-terminated liquid fluororubber.

6. The temperature- and corrosion-resistant fluororubber-nylon composite tape according to claim 1, characterized in that, The epoxy silane coupling agent is KH-560.

7. The temperature- and corrosion-resistant fluororubber-nylon composite tape according to claim 1, characterized in that, The photoinitiator is selected from one or both of 2-hydroxy-2-methyl-1-phenyl-1-propanone and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

8. The temperature- and corrosion-resistant fluororubber-nylon composite tape according to claim 7, characterized in that, The photoinitiator comprises 2-hydroxy-2-methyl-1-phenyl-1-propanone and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, wherein the weight ratio of 2-hydroxy-2-methyl-1-phenyl-1-propanone and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is 1:(0.2-1).

9. The temperature- and corrosion-resistant fluororubber-nylon composite tape according to claim 1, characterized in that, The reactive diluent is selected from one or both of trimethylolpropane triacrylate and pentaerythritol tetraacrylate.

10. A method for preparing a temperature- and corrosion-resistant fluororubber-nylon composite tape according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Carboxylated polyamide resin, hydroxylated polyamide resin and epoxy silane are coupled and mixed to form an adhesive layer composition; S2. Mix liquid fluororubber containing photocurable functional groups, epoxy-modified liquid fluororubber, photoinitiator, and reactive diluent to form a fluororubber coating composition; S3. The adhesive layer composition prepared in S1 is coated on the surface of the nylon tape substrate that has undergone alkali reduction treatment and infrared modification treatment to form an adhesive layer. S4. The adhesive layer obtained in step S3 is coated with the fluororubber coating composition obtained in step S2, and then photocured a second time to form a fluororubber coating, thus obtaining the temperature-resistant and corrosion-resistant fluororubber-nylon composite tape.

Images