A hydrocarbon medium resistant rubber sealing membrane and a preparation method thereof

Abstract

The application discloses a kind of hydrocarbon medium resistant rubber sealing film and preparation method thereof, belong to the technical field of rubber sealing material, the hydrocarbon medium resistant rubber sealing film includes following weight parts raw materials: nitrile rubber 100 parts, activating agent 3-8 parts, lubricant 0.5-2 parts, reinforcing filler 40-100 parts, plasticizer 15-25 parts, processing aid 0-1 part, vulcanization system 1.2-5.0 parts;The processing aid is Schiff base type hyperbranched polyglycerol ether-hydrazide, and the plasticizer is prepared after etherification and epoxidation of maleimide group castor oil.The synergistic chemical anchoring system of reactive plasticizer and hyperbranched processing aid is used to solve the problem that the existing nitrile rubber sealing material is easily extracted and seriously deteriorated in performance when serving in hydrocarbon medium for a long time.

Description

Technical Field

[0001] This invention belongs to the field of rubber sealing materials technology, specifically relating to a hydrocarbon-resistant rubber sealing film and its preparation method. Background Technology

[0002] Rubber sealing membranes are a type of functional rubber product widely used in petrochemical, oil and gas storage and transportation, and mechanical equipment industries. Their main function is to provide reliable gas-tight or liquid-tight isolation in various working media environments. In actual use, sealing membranes are in long-term contact with hydrocarbon media, including various fuels, lubricating oils, hydraulic oils, solvent oils, and petroleum-based fluids. Therefore, the material's resistance to hydrocarbon media directly affects the service life of the sealing membrane and the reliability of system operation.

[0003] Currently, nitrile rubber (NBR) is one of the most widely used rubber materials in the sealing products field, possessing good oil resistance and relatively low cost. By adjusting the acrylonitrile content in NBR, the material's oil resistance and low-temperature performance can be balanced to some extent. However, after prolonged immersion in hydrocarbon media, oil molecules and small hydrocarbon molecules penetrate into the rubber's internal molecular chains, causing swelling. Simultaneously, plasticizers and other additives in the rubber formulation are gradually extracted by the medium. The combined effect of these two diffusion processes significantly alters the rubber's mechanical properties—the material hardens, loses elasticity, and may even fail to seal. Especially in low-temperature environments, the extraction of plasticizers leads to a sharp deterioration in the rubber's cold resistance, causing it to lose its high elasticity at low temperatures and thus failing to meet the requirements for use in cold regions. Furthermore, some hydrocarbon media (such as aromatic hydrocarbon solvents) have a strong dissolving and corrosive effect on rubber materials, further accelerating the material's performance degradation.

[0004] To address the aforementioned issues, existing technologies have proposed several improvement solutions. For example, hydrogenated nitrile rubber (NBR) can be used instead of ordinary NBR. This is achieved by hydrogenating the unsaturated double bonds in the NBR molecular chain, thereby improving the material's heat resistance, ozone resistance, and resistance to various media. Other solutions involve blending NBR with other rubbers (such as chloroprene rubber and polyvinyl chloride) to attempt to combine the performance advantages of different rubber types. Furthermore, some technologies explore adding specific fillers or employing surface treatment processes to enhance resistance to various media.

[0005] However, the existing technologies still have the following shortcomings. Although hydrogenated nitrile butadiene rubber (NBR) has better resistance to media than ordinary NBR, its low-temperature performance is still limited by the main chain structure of the material itself, and it also faces the problem of decreased cold resistance after the plasticizer is extracted. Although blending modification can improve certain properties to some extent, the compatibility between different rubber components often affects the overall performance of the material, and the long-term stability of the blend system in complex hydrocarbon media environments still needs to be verified. Filler modification and surface treatment can usually only play an auxiliary role in improvement and cannot fundamentally solve the problem of interaction between the rubber matrix and hydrocarbon media. More importantly, the performance degradation mechanism of existing rubber sealing film materials during long-term contact with hydrocarbon media involves the coupled effects of multiple factors such as swelling, plasticizer extraction, and chemical aging. A single technical improvement method is often insufficient to simultaneously address these multiple aging factors. Summary of the Invention

[0006] The purpose of this invention is to provide a hydrocarbon-resistant rubber sealing film and its preparation method, so as to solve the problem of poor hydrocarbon-resistant performance of rubber sealing films.

[0007] The objective of this invention can be achieved through the following technical solutions: The first aspect of this application provides a hydrocarbon-resistant rubber sealing membrane, comprising the following raw materials in parts by weight: 100 parts of nitrile rubber, 3-8 parts of activator, 0.5-2 parts of lubricant, 40-100 parts of reinforcing filler, 15-25 parts of plasticizer, 0-1 parts of processing aid, and 1.2-5.0 parts of vulcanization system; wherein the processing aid is Schiff base type hyperbranched polyglycerol ether-hydrazide, and the plasticizer is prepared by maleimide-based castor oil after etherification and epoxidation.

[0008] In some possible implementations, the plasticizer is prepared by the following steps: Castor oil and N-(2-hydroxyethyl)maleimide were esterified with p-toluenesulfonic acid to obtain maleimide-based castor oil; Maleimide-based castor oil is etherified with n-hexadecane in the presence of anhydrous potassium carbonate and tetrabutylammonium bromide to obtain alkyl-etherified maleimide-based castor oil. Alkyl etherified maleimide castor oil undergoes an epoxidation reaction with hydrogen peroxide and acetic acid under the catalysis of a cation exchange resin to obtain a plasticizer. This invention uses epoxidized alkyl etherified maleimide castor oil as a plasticizer. The plasticizer molecule contains both epoxy and maleimide groups. The epoxy groups impart reactive activity to the plasticizer, enabling it to chemically bond with processing aids, while the maleimide groups can participate in cross-linking reactions during vulcanization or form chemical bonds with rubber molecular chains. This anchors the plasticizer molecules within the rubber network through chemical bonds, fundamentally inhibiting the diffusion and extraction of the plasticizer in hydrocarbon media. Compared to traditional plasticizers that rely solely on physical dispersion in the prior art, the extraction resistance of the plasticizer in this invention is significantly improved.

[0009] In some possible implementations, the molar ratio of castor oil to N-(2-hydroxyethyl)maleimide is 1:0.7-0.8, and the amount of p-toluenesulfonic acid is 0.4%-0.5% of the mass of castor oil. The molar ratio of hexadecane to castor oil is 1:0.9-1, the molar ratio of hexadecane to potassium carbonate is 1:1.8-2, and the amount of tetrabutylammonium bromide added is 4%-5% of the mass of maleimide-based castor oil; The molar ratio of hydrogen peroxide, acetic acid, and castor oil is 0.5-0.6:0.3-0.4:1, and the amount of cation exchange resin added is 4.5%-5% of the mass of alkyl etherified maleimide castor oil.

[0010] In some possible implementations, the processing aid is prepared through the following steps: Hyperbranched polyglycidyl ether is oxidized with sodium periodate to obtain aldehyde-modified hyperbranched polyglycidyl ether. The reaction is carried out in an ice-water bath at room temperature for 2-24 hours under light-protected conditions. After quenching with ethylene glycol, the reaction is dialyzed through a dialysis bag with a molecular weight cutoff of 1000-3000 Da and then freeze-dried. The aldehyde-modified hyperbranched polyglycidyl ether reacts with oxalic acid dihydrazide in methanol at pH 4-6 for 4-24 hours. The reaction is then dialyzed through a dialysis bag with a molecular weight cutoff of 1000-3000 Da in methanol / water to obtain Schiff base-type hyperbranched polyglycerol ether-hydrazide. This invention uses Schiff base-type hyperbranched polyglycerol ether-hydrazide as a processing aid. This hyperbranched processing aid has unique structural advantages: the hyperbranched polyether backbone provides it with good flexibility and compatibility with the rubber matrix; the numerous terminal hydrazide groups provide its multi-point chemical anchoring ability. These hydrazide groups undergo ring-opening addition reactions with the epoxy groups in the plasticizer molecules, and also undergo condensation reactions with the oxygen-containing functional groups on the surface of the carbon black filler. The multi-point anchoring effect brought about by the hyperbranched structure enables the processing aid to simultaneously and firmly chemically fix the plasticizer molecules and filler particles, effectively inhibiting the extraction of plasticizers in high-temperature hot oil environments and improving the dispersion state of fillers in the rubber matrix.

[0011] In some possible implementations, the mass ratio of hyperbranched polyglycidyl, sodium periodate, and oxalohydrazide is 10:12-15:25-35; the amount of ethylene glycol used is 1-2 times the molar amount of sodium periodate.

[0012] In some possible implementations, hyperbranched polyglycidol is prepared via the following steps: Hyperbranched polyglycidyl glycerol was obtained by ring-opening polymerization of trimethylolpropane and glycidyl glycerol under potassium methoxide catalysis, using dioxane as solvent. The reaction temperature was 70-95℃, and the reaction time was 5-6 h. The crude product was purified by acidification, acetone precipitation, and centrifugation. The concentration of potassium methoxide solution was 0.03 g / mL, and the molar ratio of trimethylolpropane to glycidyl glycerol was 3 mmol:7-10 g. Hyperbranched polyglycidyl glycerol with different molecular weights could be obtained by adjusting the ratio of trimethylolpropane to glycidyl glycerol. The average molecular weight of the hyperbranched polyglycidyl glycerol was 2500-3500 g / mol.

[0013] In some possible implementations, the vulcanization system includes peroxides, co-crosslinking agents, vulcanizing agents, and accelerators; The peroxide is dicumyl peroxide; the crosslinking agent is triallyl isocyanurate; the vulcanizing agent is sulfur; and the accelerator is N-cyclohexyl-2-benzothiazole sulfenamide.

[0014] In some possible implementations, the filler is one of carbon black, silica, diatomaceous earth, and carbon nanotubes; the lubricant is stearic acid; and the activator is zinc oxide.

[0015] The second aspect of this application provides a method for preparing a hydrocarbon-resistant rubber sealing film, comprising the following steps: Raw rubber plasticizing: Accurately weighed nitrile rubber is added to the open mill and plasticized at a roller temperature of 40-50℃ to make the raw rubber wrap around the roller and have a smooth and uniform surface. Mixing and feeding: After plasticizing, add activator and lubricant and mix well; add carbon black and plasticizer in batches (they can be added alternately to avoid powder flying); finally add processing aids and vulcanization system and mix well. During the mixing process, the filler is repeatedly cut and repeatedly rolled into 6-8 sets of bags (i.e., "triangular bags" or "rolling") to ensure that the filler is evenly dispersed in the rubber compound.

[0016] Sheeting and resting: Adjust the roller gap of the open mill to an appropriate thickness (approximately 2-3 mm), and roll the uniformly mixed rubber compound into sheets. Let the mixed rubber sheets rest at room temperature for 24 hours to relax the internal stress generated during the mixing process and promote further dispersion of fillers.

[0017] Flat vulcanization: A flat vulcanizing machine and molds are used for compression molding; the molding temperature is set to 160 ℃; the molding pressure is set to 5 MPa; the molding time is set to T90 + 2 min (2 min is used to compensate for heat loss during mold loading and venting, ensuring sufficient internal vulcanization of thick products). Determining the vulcanization time (T90 measurement): A small sample is taken from the rested film, and its positive vulcanization time T90 is measured using a rotorless vulcanizing instrument (test temperature set to 160 ℃), which is used as the benchmark for subsequent molding times.

[0018] The beneficial effects of this invention are: This invention provides a hydrocarbon-resistant rubber sealing film and its preparation method. Through a synergistic chemical anchoring system of reactive plasticizer and hyperbranched processing aid, it improves the problem of plasticizer easy extraction and severe performance degradation of existing nitrile rubber sealing materials during long-term service in hydrocarbon media.

[0019] This invention utilizes a combination of reactive plasticizers and hyperbranched processing aids. During vulcanization, the epoxy groups in the plasticizer and the hydrazide groups in the processing aid react to form covalent bonds. Simultaneously, the hydrazide groups at the ends of the processing aid chemically bond with the oxygen-containing functional groups on the filler surface. Furthermore, the maleimide groups in the plasticizer further participate in the cross-linking reaction of the rubber. The combined effect of these three factors firmly anchors the plasticizer within a three-dimensional cross-linked network, preventing extraction by hydrocarbon media.

[0020] The rubber sealing film of this invention maintains excellent dimensional stability (low volume change rate), elastic recovery ability (small compression set), and mechanical property retention (small decrease in tensile strength and elongation at break) even after long-term aging in hydrocarbon media. Simultaneously, the intrinsic flexibility provided by the hyperbranched polyether skeleton and the continuous plasticizing effect from retained plasticizers enable the sealing film to maintain sufficient flexibility under low-temperature conditions, achieving a comprehensive balance between hydrocarbon media and low-temperature resistance.

[0021] This invention, through the synergistic effect of reactive plasticizers and hyperbranched chemically anchored processing aids, systematically improves the long-term service stability of nitrile rubber sealing films in hydrocarbon media environments from the perspective of molecular structure design and network construction. It overcomes the technical defects of existing technologies, such as easy plasticizer extraction and severe deterioration of sealing performance after high-temperature aging. It provides a high-performance and highly reliable rubber sealing film material for sealing applications in petrochemical, oil and gas storage and transportation, and cold-region equipment, demonstrating significant technological advancement and broad industrial application prospects. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] The following is a detailed description of a hydrocarbon-resistant rubber sealing film and its preparation method according to an embodiment of this application.

[0024] The following is a detailed description with reference to specific examples.

[0025] Preparation Example 1 This preparation example demonstrates the preparation of a plasticizer: Esterification of castor oil with N-(2-hydroxyethyl)maleimide: Castor oil, N-(2-hydroxyethyl)maleimide, p-toluenesulfonic acid, and toluene were subjected to nitrogen protection and hydroquinone polymerization inhibitor (0.1% of the total mass of the reactants) was added. The mixture was heated to 110°C and refluxed for 4 hours. During the reaction, the generated water was continuously separated using a water separator. After the reaction was completed, the mixture was cooled to room temperature, washed with 5% sodium carbonate solution until neutral, and then washed three times with distilled water. The organic phase was dried with anhydrous sodium sulfate, and toluene was removed by vacuum distillation to obtain maleimide-based castor oil. The molar ratio of castor oil to N-(2-hydroxyethyl)maleimide was 1:0.8, and p-toluenesulfonic acid was used as a catalyst at 0.5% of the mass of castor oil. Etherification: Maleimide-based castor oil, n-hexadecane, anhydrous potassium carbonate, and tetrabutylammonium bromide were added to acetone and refluxed at 50°C for 5 hours under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, filtered to remove potassium carbonate and the generated potassium bromide salt, and the filtrate was distilled under reduced pressure using a rotary evaporator to recover acetone. The residue was dissolved in ethyl acetate and washed successively with distilled water and saturated brine, dried over anhydrous sodium sulfate, and distilled under reduced pressure to obtain alkyl-etherified maleimide-based castor oil. The molar ratio of n-hexadecane to initial castor oil was 1:1, the molar ratio of n-hexadecane to potassium carbonate was 1:2, and the amount of tetrabutylammonium bromide added was 5% of the mass of maleimide-based castor oil. Epoxidation: Alkyl etherified maleimide castor oil, acetic acid, toluene, and cation exchange resin were mixed. A 30% (w / w) hydrogen peroxide solution was added dropwise at 60°C. After the addition was complete, the reaction continued for 2 hours. After the reaction was finished, the cation exchange resin was recovered by filtration and reused. The filtrate was washed with a 5% sodium carbonate solution until neutral, then washed three times with distilled water. The organic phase was dried over anhydrous sodium sulfate and distilled under reduced pressure to obtain the plasticizer. The molar ratio of hydrogen peroxide, acetic acid, and initial castor oil was 0.6:0.4:1, and the amount of cation exchange resin added was 5% of the mass of the alkyl etherified maleimide castor oil.

[0026] Preparation Example 2 This preparation example prepares a processing aid: Trimethylolpropane was added to a potassium methoxide solution and stirred to disperse at 75°C. Then, dioxane was added, and the system temperature was maintained at 95°C. Glyceryl ether was slowly added, and the reaction continued for 6 hours. After the reaction was complete, methanol solution was added to the crude product, and the mixture was stirred until homogeneous. After acidification, stirring was continued for 30 minutes. The stirred solution was precipitated with acetone and centrifuged to obtain hyperbranched polyglyceryl ether. The concentration of potassium methoxide solution was 0.03 g / mL, and the ratio of trimethylolpropane to glyceryl ether was 3 mmol:7 g.

[0027] Hyperbranched polyglycidyl was added to water to prepare a 10% (w / w) solution. Sodium periodate was added under light-protected conditions, and the mixture was stirred for 10 hours in an ice-water bath at room temperature. After the reaction was completed, ethylene glycol was added to quench the reaction, and stirring was continued for 60 minutes. The reaction solution was then added to a dialysis bag with a molecular weight cutoff of 1000-3000 Da and dialyzed with water. Subsequently, the solution was freeze-dried to obtain aldehyde-modified hyperbranched polyglycidyl. Aldehyde-modified hyperbranched polyglycidyl ether was prepared into a 10% (w / w) solution by mixing aldehyde-modified hyperbranched polyglycidyl ether and methanol. Oxalic acid dihydrazide was added, and the pH was adjusted to 6 with acetic acid. The reaction was continued for 10 hours. After the reaction was completed, the reaction solution was added to a dialysis bag with a molecular weight cutoff of 1000-3000 Da and dialyzed with a methanol-water mixture (volume ratio 2:1) to obtain Schiff base-type hyperbranched polyglycidyl ether. The mass ratio of hyperbranched polyglycidyl ether, sodium periodate, and oxalic acid dihydrazide was 10:12:25; the amount of ethylene glycol used was 1.5 times the molar amount of sodium periodate.

[0028] Preparation Example 3 The difference between this preparation example and preparation example 2 is that: Trimethylolpropane was added to a potassium methoxide solution and stirred at 75°C to disperse the mixture. Then, dioxane was added, and the system temperature was maintained at 95°C. Glycerin was slowly added, and the reaction continued for 6 hours. After the reaction was complete, methanol solution was added to the crude product, and the mixture was stirred until homogeneous. After acidification, stirring was continued for 30 minutes. The stirred solution was precipitated with acetone and centrifuged to obtain hyperbranched polyglycerin. The ratio of trimethylolpropane to glycerin was 3 mmol:10 g, and the mass ratio of hyperbranched polyglycerin, sodium periodate, and oxalohydrazide was 10:15:35. The amount of ethylene glycol used was 1.5 times the molar amount of sodium periodate.

[0029] The remaining raw materials and preparation steps are the same as in Preparation Example 2.

[0030] Example 1 This embodiment provides a hydrocarbon-resistant rubber sealing film, comprising the following raw materials in parts by weight: 100 parts of nitrile rubber, 5 parts of activator, 1 part of lubricant, 80 parts of reinforcing filler, 20 parts of plasticizer prepared according to the method of Preparation Example 1, 0 parts of processing aid, and 4.5 parts of vulcanization system; Vulcanization system: 2 parts dicumyl peroxide, 1.5 parts triallyl isocyanurate, 0.5 parts sulfur, and 0.5 parts N-cyclohexyl-2-benzothiazole sulfenamide. The accelerator is N-cyclohexyl-2-benzothiazole sulfenamide; the lubricant is stearic acid; the activator is zinc oxide; and the filler is carbon black.

[0031] A method for preparing a hydrocarbon-resistant rubber sealing membrane includes the following steps: Raw rubber plasticizing: Accurately weighed nitrile rubber (NBR N41 raw rubber) is added to the open mill and plasticized at a roll temperature of 50°C to make the raw rubber wrap around the rolls and have a smooth and uniform surface. Mixing and feeding: After plasticizing, add activator and lubricant and mix well; add reinforcing filler and plasticizer in batches; finally add processing aid and vulcanization system and mix well; repeatedly cut the blade and repeatedly pack 8 sets of bags during the mixing process; Sheeting and Storage: Adjust the roller gap of the open mill to an appropriate thickness (approximately 2-3 mm), and roll the uniformly mixed rubber compound into sheets. Let the mixed rubber sheets stand at room temperature for 24 hours. Flat vulcanization: A flat vulcanizing machine and molds are used for compression molding; the molding temperature is set to 160 ℃; the molding pressure is set to 5 MPa; the molding time is set to T90 + 2 min (2 min is used to compensate for heat loss during mold loading and venting, ensuring sufficient internal vulcanization of thick products). Determining the vulcanization time (T90 measurement): A small sample is taken from the rested film, and its positive vulcanization time T90 is measured using a rotorless vulcanizing instrument (test temperature set to 160 ℃), which is used as the benchmark for subsequent molding times.

[0032] Example 2 The difference between this embodiment and Example 1 is that the nitrile rubber is 100 parts, the activator is 5 parts, the lubricant is 1 part, the reinforcing filler is 100 parts, the plasticizer prepared according to the method of Example 1 is 20 parts, the processing aid is 0 parts, and the vulcanization system is 4.5 parts; the remaining raw materials and preparation process are the same as in Example 1.

[0033] Example 3 The difference between this embodiment and Example 1 is that the nitrile rubber is 100 parts, the activator is 5 parts, the lubricant is 1 part, the reinforcing filler is 60 parts, the plasticizer prepared according to the method of Example 1 is 20 parts, the processing aid is 0 parts, and the vulcanization system is 4.5 parts; the remaining raw materials and preparation process are the same as in Example 1.

[0034] Example 4 The difference between this embodiment and Example 1 is that the nitrile rubber is 100 parts, the activator is 5 parts, the lubricant is 1 part, the reinforcing filler is 80 parts, the plasticizer prepared according to the method of Preparation Example 1 is 20 parts, the processing aid prepared according to the method of Preparation Example 2 is 0.8 parts, and the vulcanization system is 4.5 parts; the remaining raw materials and preparation process are the same as in Example 1.

[0035] Example 5 The difference between this embodiment and Example 1 is that the nitrile rubber is 100 parts, the activator is 5 parts, the lubricant is 1 part, the reinforcing filler is 80 parts, the plasticizer is 20 parts, the processing aid prepared according to the method of Preparation Example 3 is 0.8 parts, and the vulcanization system is 4.5 parts; the remaining raw materials and preparation process are the same as in Example 1.

[0036] Example 6 The difference between this embodiment and Example 1 is that the nitrile rubber is 100 parts, the activator is 5 parts, the lubricant is 1 part, the reinforcing filler is 80 parts, the plasticizer is 20 parts, the processing aid prepared according to the method of Preparation Example 2 is 1 part, and the vulcanization system is 4.5 parts; the remaining raw materials and preparation process are the same as in Example 1.

[0037] Example 7 The difference between this embodiment and Example 1 is that the nitrile rubber is 100 parts, the activator is 5 parts, the lubricant is 1 part, the reinforcing filler is 80 parts, the plasticizer is 25 parts, the processing aid prepared according to the method of Preparation Example 3 is 0.8 parts, and the vulcanization system is 4.5 parts; the remaining raw materials and preparation process are the same as in Example 1.

[0038] Example 8 The difference between this embodiment and Example 1 is that the nitrile rubber is 100 parts, the activator is 5 parts, the lubricant is 1 part, the reinforcing filler is 80 parts, the plasticizer is 15 parts, the processing aid prepared according to the method of Preparation Example 3 is 0.8 parts, and the vulcanization system is 4.5 parts; the remaining raw materials and preparation process are the same as in Example 1.

[0039] Comparative Example 1 Compared with Example 1, the plasticizer in this comparative example is replaced with commercially available plasticizer TP-95, while the other raw materials and preparation process remain the same as in Example 1.

[0040] Comparative Example 2 Compared with Example 5, the plasticizer in this comparative example is replaced with commercially available plasticizer TP-95, while the other raw materials and preparation process remain the same as in Example 5.

[0041] Comparative Example 3 Compared with Example 5, this comparative example replaces the processing aid with hyperbranched polyglycidol in Preparation Example 3, while the other raw materials and preparation process remain the same as in Example 5.

[0042] Test example: Oil resistance: The sample of No. 3 fuel (RP-3 is a hydrocarbon mixture) was aged (aged at 150℃ for 24 hours and then taken out) and placed in an explosion-proof container filled with oil. After conditioning at room temperature for 24 hours, the performance was tested.

[0043] (1) Test of volume change rate: According to GB / T1690-2010, type II sample (25mm×25mm) was used to test the mass in air and water before and after aging. The volume change rate of NBR vulcanizate after immersion in oil was tested according to the water displacement method.

[0044] (2) Test of compression set performance: In accordance with GB / T7759.1-2015, the compression set of NBR vulcanizate after hot oil aging was tested using type A specimens (diameter 29 mm, height 12.5 mm) under a compression rate of 25%.

[0045] Tensile property test: Using an electronic tensile testing machine and a dumbbell-shaped specimen, the stress-strain curve of the vulcanizate was tested according to GB / T528-2009 at a test speed of 500 mm / min.

[0046] Brittleness temperature: According to GB / T15256-2014, the brittleness temperature is determined by immersing the sample in alcohol for 5 minutes and then impacting it using the multiple sample method (5 samples). The lowest temperature at which no cracks appear is taken as the brittleness temperature.

[0047] Performance tests were conducted on Examples 1-8 and Comparative Examples 1-3, and the results are shown in Table 1: Table 1

[0048] As shown in Table 1, this invention achieves improved performance of nitrile rubber sealing films under high-temperature hot oil aging conditions through the synergistic chemical anchoring effect of reactive epoxidized castor oil-based plasticizer and hydrazide-functionalized hyperbranched polyglycerol ether processing aid. The introduction of the hyperbranched polyglycerol ether-hydrazide processing aid in Examples 1-3 and Examples 4-8 upgrades the original physically dispersed plasticizing system into a three-dimensional anchored network system characterized by chemical bonding. This fundamental structural difference results in Examples 4-8 exhibiting systematic superiority over Examples 1-3 in terms of heat-resistant oil aging performance, elasticity retention, and mechanical property stability.

[0049] According to the comparison between Example 1 and Comparative Example 1, and Example 5 and Comparative Example 2, the reactive plasticizer containing maleimide groups and epoxy groups prepared in this invention can react with the rubber matrix or form strong intermolecular interactions through the active groups in its structure during hot oil aging, thereby effectively resisting the extraction and erosion of hydrocarbon media. Its hot oil aging resistance and elasticity retention are significantly better than those of traditional commercially available plasticizers.

[0050] A comparison of Example 5 and Comparative Example 3 shows that the functionalized hyperbranched polyglycidyl can only improve the compatibility between components to a certain extent through physical compatibilization. However, its molecular chain ends lack chemically bondable hydrazide groups, making it unable to form covalent bonds with the epoxy groups in the plasticizer molecule and the oxygen-containing functional groups on the filler surface. Therefore, its anchoring effect on the plasticizer is extremely limited. In contrast, the hyperbranched processing aid prepared in Example 3, which introduces a Schiff base structure through aldehyde and hydrazide functionalization, can form multi-point chemical anchoring with the plasticizer and filler through the terminal hydrazide / Schiff base groups, thereby effectively inhibiting the extraction of plasticizer and maintaining the structural integrity of the material during hot oil aging.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rubber sealing membrane resistant to hydrocarbon media, characterized in that, The raw materials include the following parts by weight: 100 parts of nitrile rubber, 3-8 parts of activator, 0.5-2 parts of lubricant, 40-100 parts of reinforcing filler, 15-25 parts of plasticizer, 0-1 parts of processing aid, and 1.2-5.0 parts of vulcanization system; wherein the processing aid is Schiff base type hyperbranched polyglycerol ether-hydrazide, and the plasticizer is maleimide-based castor oil prepared by etherification and epoxidation.

2. The hydrocarbon-resistant rubber sealing membrane according to claim 1, characterized in that, The plasticizer is prepared by the following steps: Castor oil and N-(2-hydroxyethyl)maleimide were esterified with p-toluenesulfonic acid to obtain maleimide-based castor oil; Maleimide-based castor oil was etherified with n-hexadecane in the presence of anhydrous potassium carbonate and tetrabutylammonium bromide to obtain alkyl-etherified maleimide-based castor oil. Alkyl etherified maleimide castor oil undergoes an epoxidation reaction with hydrogen peroxide and acetic acid under the catalysis of a cation exchange resin to obtain a plasticizer.

3. The hydrocarbon-resistant rubber sealing membrane according to claim 2, characterized in that, The molar ratio of castor oil to N-(2-hydroxyethyl)maleimide is 1:0.7-0.8, and the amount of p-toluenesulfonic acid used is 0.4%-0.5% of the mass of castor oil. The molar ratio of hexadecane to castor oil is 1:0.9-1, the molar ratio of hexadecane to potassium carbonate is 1:1.8-2, and the amount of tetrabutylammonium bromide added is 4%-5% of the mass of maleimide-based castor oil; The molar ratio of hydrogen peroxide, acetic acid, and castor oil is 0.5-0.6:0.3-0.4:1, and the amount of cation exchange resin added is 4.5%-5% of the mass of alkyl etherified maleimide castor oil.

4. The hydrocarbon-resistant rubber sealing membrane according to claim 1, characterized in that, The processing aid is prepared through the following steps: Hyperbranched polyglycidyl ether was oxidized with sodium periodate to obtain aldehyde-modified hyperbranched polyglycidyl ether. The reaction was carried out in an ice-water bath at room temperature for 2-24 hours under light-protected conditions. After quenching with ethylene glycol, the reaction was dialyzed through a dialysis bag with a molecular weight cutoff of 1000-3000 Da and then freeze-dried. The aldehyde-modified hyperbranched polyglycidyl ether was reacted with oxalic acid dihydrazide in methanol with the pH adjusted to 4-6 by acetic acid for 4-24 hours. The reaction was then dialyzed through a dialysis bag with a molecular weight cutoff of 1000-3000 Da in methanol / water to obtain Schiff base type hyperbranched polyglycerol ether-hydrazide.

5. The hydrocarbon-resistant rubber sealing membrane according to claim 4, characterized in that, The mass ratio of hyperbranched polyglycidyl glycerol, sodium periodate, and oxalohydrazide is 10:12-15:25-35; the amount of ethylene glycol used is 1-2 times the molar amount of sodium periodate.

6. The hydrocarbon-resistant rubber sealing membrane according to claim 1, characterized in that, The hyperbranched polyglycidol is prepared by the following steps: Trimethylolpropane was reacted with glycidyl ether via ring-opening polymerization under potassium methoxide catalysis to obtain hyperbranched polyglycidyl ether. Dioxane was used as solvent. The reaction temperature was 70-95℃ and the reaction time was 5-6h. The crude product was purified by acidification, acetone precipitation and centrifugation. The concentration of potassium methoxide solution was 0.03 g / mL, and the ratio of trimethylolpropane to glycidol was 3 mmol: 7-10 g.

7. The hydrocarbon-resistant rubber sealing membrane according to claim 1, characterized in that, The vulcanization system includes peroxide, crosslinking agent, vulcanizing agent and accelerator.

8. The hydrocarbon-resistant rubber sealing membrane according to claim 7, characterized in that, The peroxide is dicumyl peroxide; the crosslinking agent is triallyl isocyanurate; the vulcanizing agent is sulfur; and the accelerator is N-cyclohexyl-2-benzothiazole sulfenamide.

9. The hydrocarbon-resistant rubber sealing membrane according to claim 1, characterized in that, The filler is one of carbon black, silica, diatomaceous earth, and carbon nanotubes; the lubricant is stearic acid; and the activator is zinc oxide.

10. A method for preparing a hydrocarbon-resistant rubber sealing membrane for use in preparing the hydrocarbon-resistant rubber sealing membrane according to any one of claims 1-9, characterized in that, The steps include the following: Raw rubber plasticizing: Accurately weighed nitrile rubber is added to the open mill and plasticized at a roller temperature of 40-50℃ to make the raw rubber wrap around the roller and have a smooth and uniform surface. Mixing and feeding: After plasticizing, add activator and lubricant and mix well; add carbon black and plasticizer in batches; finally add processing aids and vulcanization system and mix well. During the mixing process, the mixture is repeatedly cut with a knife and repeatedly bagged 6 to 8 times; Sheeting and storage: Adjust the roller gap of the open mill to roll out the evenly mixed rubber compound into sheets; Flat vulcanization: Flat vulcanizing machine and mold are used for molding; the molding temperature is set to 155-160℃; the molding pressure is set to 4.5-5MPa; the molding time is set to T90+2 min.

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