A gasoline-resistant rubber magnetic strip and its preparation method

Abstract

This application relates to the field of rubber magnetic strip processing technology, and more specifically, to a gasoline-resistant rubber magnetic strip and its preparation method, which is prepared from the following raw materials in parts by weight: 85-92 parts magnetic powder, 4-8 parts nitrile rubber, 0.5-1 part dispersant, 0.1-0.5 parts coupling agent, 0.15-0.5 parts anti-aging agent, 0.2-0.5 parts zinc oxide, 0.1-0.2 parts di-tert-butyl peroxide, 0.2-0.5 parts triallyl isocyanurate, and 0 parts toughening agent. 0.15-0.6 parts, oil-resistant plasticizer 0.5-1 parts, wherein the oil-resistant plasticizer is composed of paraffin oil, adipic acid-based polyester and sebacic acid-based polyester. The above formula effectively solves the problems of swelling and interface debonding of existing nitrile rubber-based magnetic strips in gasoline environment. It can still maintain good chemical stability in oily environment for a long time, and the volume expansion rate is significantly reduced. It can avoid fan speed instability, start-stop failure or jamming, etc., and also has good flexibility and impact resistance.

Description

Technical Field

[0001] This application relates to the field of rubber magnetic strip processing technology, and more specifically, to a gasoline-resistant rubber magnetic strip and its preparation method. Background Technology

[0002] Rubber magnetic strips (also known as flexible bonded magnets) are made by combining ferrite magnetic powder with rubber or thermoplastic elastomers. They possess characteristics such as flexibility, ease of processing and molding, impact resistance, and noise reduction, making them a mainstream material choice for permanent magnet rotors in automotive micro fans. Currently, most rubber magnetic strips used in automotive fans are made by calendering anisotropic strontium ferrite powder with nitrile rubber. This type of flexible bonded magnet offers advantages such as low continuous production costs, good flexibility, high dimensional accuracy, and ease of automated assembly. Furthermore, it exhibits good temperature and humidity resistance under typical automotive conditions, and its magnetic performance fluctuations can be controlled within a small range, meeting the general heat dissipation requirements of vehicles.

[0003] However, when miniature fans are installed in engine compartments, around fuel supply systems, or in areas where fuel leaks may occur, the rubber magnetic strips will inevitably come into contact with gasoline vapor or liquid gasoline. Prolonged contact degrades their chemical stability. More seriously, aromatics, olefins, and peroxides in gasoline can penetrate into the gaps between rubber molecular chains, disrupting the cross-linked network structure of the nitrile rubber substrate and causing a significant swelling effect. This swelling not only leads to a 15%-30% volume expansion of the magnetic strip but also causes debonding between the ferrite magnetic powder and the rubber substrate, resulting in a decrease in magnetic performance exceeding 20%. Ultimately, this can cause serious malfunctions such as fan speed instability, start-stop failure, or even jamming.

[0004] To address the aforementioned issues, existing technologies primarily mitigate them through external protection methods, such as adding metal protective covers, applying oil-resistant coatings, or using sealant potting. However, these solutions have significant drawbacks: protective covers increase the size and weight of the fan; coatings are prone to peeling off over long-term use, resulting in poor protective durability; and potting processes lead to increased costs and loss of maintainability. Some manufacturers have attempted to replace nitrile rubber with CPE substrates, but its gasoline resistance is only slightly better, still considered "poor," and its magnetic properties fluctuate more significantly. Research has also explored all-plastic bonded magnets, but their poor flexibility and insufficient impact resistance result in an assembly breakage rate as high as 3%-5%, making them unsuitable for the vibration environment of automobiles. Summary of the Invention

[0005] To address the problem of poor oil resistance in nitrile rubber magnetic strips, this application provides a gasoline-resistant rubber magnetic strip and its preparation method.

[0006] In a first aspect, this application provides a gasoline-resistant rubber magnetic strip, employing the following technical solution: A gasoline-resistant rubber magnetic strip is prepared from the following raw materials in parts by weight: 85-92 parts of magnetic powder 4-8 parts of nitrile rubber Dispersant 0.5-1 part 0.1-0.5 parts of coupling agent Anti-aging agent 0.15-0.5 parts 0.2-0.5 parts zinc oxide 0.1-0.2 parts of bis-tert-butyl peroxide 0.2-0.5 parts of triallyl isocyanurate Toughening agent 0.15-0.6 parts Oil-resistant plasticizer 0.5-1 part The oil-resistant plasticizer is composed of paraffin oil, adipic acid-based polyester, and sebacic acid-based polyester.

[0007] By adopting the above technical solution, the problems of swelling and interface debonding of existing nitrile rubber-based magnetic strips in gasoline environments are effectively solved. It maintains good chemical stability even after long-term use in oily environments, with a significantly reduced volume expansion rate, thus preventing fan malfunctions such as speed instability, start-stop failure, or jamming. It also possesses good flexibility and impact resistance.

[0008] Magnetic powder, as the core functional component, provides basic magnetic properties, while nitrile rubber imparts flexibility and processing capability to the magnetic strip. The two are uniformly mixed under the action of a dispersant, preventing magnetic powder agglomeration. A coupling agent strengthens the interfacial bonding between the magnetic powder and the rubber substrate, inhibiting interfacial debonding caused by gasoline. Di-tert-butyl peroxide and triallyl isocyanurate synergistically construct a dense and stable rubber cross-linking network, enhancing the substrate's resistance to swelling and resisting the damage to molecular chains caused by aromatics and olefins in gasoline. Paraffin oil has excellent compatibility with the nitrile rubber substrate, rapidly improving the flowability of mixing and calendering while maintaining the original flexibility of the magnetic strip, preventing brittleness after processing. Its chemical stability also provides basic protection against the penetration of small gasoline molecules. Adipic acid-based polyester molecules have good compatibility with the nitrile rubber cross-linking network, low migration, and are less prone to precipitation during long-term use, ensuring continuous oil resistance while also maintaining temperature resistance in typical automotive environments. Sebacic acid-based polyesters offer superior low-temperature flexibility and impact resistance, making them suitable for automotive vibration and alternating high and low temperature environments. It has lower migration than adipic acid-based polyesters, stronger long-term oil resistance, and can further enhance the barrier effect against gasoline components, reduce the risk of interface debonding between magnetic powder and rubber substrate. The combined use of the three can improve processing fluidity and specifically block the penetration of gasoline components, further enhancing gasoline resistance. Anti-aging agents slow down the aging and degradation of the magnetic strip in the automotive environment, zinc oxide optimizes the efficiency of the cross-linking reaction, and toughening agents ensure the impact resistance and assembly reliability of the magnetic strip in the vibration environment of automobiles. With the synergistic effect of the components, the magnetic strip improves gasoline resistance while taking into account impact resistance, flexibility and stability in use.

[0009] Preferably, the weight ratio of the paraffin oil, the adipic acid-based polyester, and the sebacic acid-based polyester is (1-2):(2-3):5.

[0010] By adopting the above technical solution and optimizing the dosage of the three components, the appropriate amount of paraffin oil ensures good compatibility with nitrile rubber substrate and the fluidity of magnetic strip processing, which helps to maintain thin-wall molding and flexibility. The adipic acid-based polyester with a moderate proportion enhances the resistance to gasoline swelling and resists the damage of aromatic hydrocarbons and olefins to the rubber crosslinking network. Furthermore, the sebacic acid-based polyester with the highest proportion improves the long-term oil resistance stability of the magnetic strip under automotive vibration and high and low temperature alternating environments, effectively reducing the risk of plasticizer migration and precipitation. Ultimately, the volume expansion rate of the rubber magnetic strip after immersion in gasoline medium is significantly reduced.

[0011] Preferably, the magnetic powder is a modified magnetic powder, prepared by the following method: 1) Mix 7-10 parts of organic bentonite and 35-40 parts of anhydrous ethanol by weight, and disperse by ultrasonication to obtain a suspension; 2) According to the weight, mix 3-5 parts of hydroxyethyl methacrylate with 8-10 parts of anhydrous ethanol, add the mixture to the suspension, stir at 55-60℃ for 1-2 hours, then add 100 parts of magnetic powder, heat to 70-75℃ for 20-30 minutes, and dry to obtain modified magnetic powder.

[0012] By adopting the above technical solution, the modified magnetic powder obtained by synergistic modification of organic bentonite and hydroxyethyl methacrylate can form a composite modified layer with both compatibility and barrier properties on the surface of the magnetic powder. This greatly improves the interfacial bonding force between the magnetic powder and the nitrile rubber substrate, effectively suppressing the problem of magnetic powder-rubber interface debonding caused by gasoline medium penetration. At the same time, the modified layer can reduce the interaction between the active sites on the surface of the magnetic powder and gasoline components, reducing the attenuation of the magnetic properties of the magnetic powder. Combined with the synergistic effect of compounded oil-resistant plasticizers, the decrease in magnetic properties of the rubber magnetic strip after immersion in gasoline environment is further reduced, and the volume expansion rate is suppressed. In addition, the modification process does not destroy the original magnetic properties of the magnetic powder, and the modified layer can improve the dispersion uniformity of the magnetic powder in the rubber matrix, ensuring the dimensional accuracy and flexibility of the magnetic strip during processing and molding. This allows the magnetic strip to maintain its thin-wall molding capability and automated assembly adaptability while further enhancing its gasoline resistance stability and reliability, making it more suitable for use in harsh gasoline contact scenarios such as engine compartments and fuel supply system peripheries.

[0013] Preferably, the toughening agent is composed of terpene resin and phenolic resin in a weight ratio of (1-5):1.

[0014] By adopting the above technical solutions and optimizing the type and amount of toughening agent, a good synergy can be formed with the nitrile rubber substrate and modified magnetic powder. The higher proportion of terpene resin enhances the flexibility and impact toughness of the magnetic strip, effectively reducing the risk of assembly breakage under automotive vibration environment and solving the problem of insufficient impact resistance of all-plastic bonded magnets. Furthermore, the phenolic resin enhances the structural stability of the rubber cross-linking network, which helps to improve the magnetic strip's resistance to gasoline swelling and avoids sacrificing oil resistance during the toughening process.

[0015] Preferably, the nitrile rubber is pretreated by the following method: By weight, 10-15 parts of nitrile rubber are mixed with 0.3-0.5 parts of methyl methacrylate, 0.5-1 parts of hydroxyl-terminated polydimethylsiloxane and 0.01-0.03 parts of initiator to obtain pretreated nitrile rubber.

[0016] By adopting the above technical solutions, nitrile rubber substrates can be modified to optimize their gasoline resistance and interfacial compatibility. Methyl methacrylate can introduce oil-resistant groups, forming a denser and more stable cross-linked structure with the nitrile rubber molecular chains, enhancing resistance to harmful components such as aromatics and olefins in gasoline, and further inhibiting magnetic strip swelling. Hydroxyl-terminated polydimethylsiloxane can improve the flexibility and surface activity of the rubber, and, together with the composite modification layer on the surface of the modified magnetic powder, significantly strengthens the interfacial bonding force between the magnetic powder and the rubber substrate, reducing the risk of interfacial debonding caused by gasoline penetration. The initiator ensures the full reaction of the two modifiers with the nitrile rubber, ensuring uniform and stable modification effects. The pretreated nitrile rubber still maintains good processing fluidity and flexibility, and can form a highly efficient synergy with the compounded oil-resistant plasticizer, compounded toughening agent, and other components, further reducing the volume expansion rate and magnetic performance attenuation of the rubber magnetic strip in gasoline contact scenarios, greatly improving structural toughness and reliability, and fully meeting the long-term use requirements of harsh automotive environments such as engine compartments.

[0017] Preferably, the acrylonitrile content in the nitrile rubber is 35-50%, and the Mooney viscosity is 40-70.

[0018] By adopting the above technical solutions and optimizing the parameters of nitrile rubber, the molecular chain polarity and oil-resistant group density can be further strengthened, significantly improving its resistance to aromatics and olefins in gasoline, and further inhibiting magnetic strip swelling and interfacial debonding. Simultaneously, it ensures the smoothness of magnetic strip mixing, calendering, and thin-wall molding (0.3mm and above) to meet the needs of automated assembly, while maintaining good flexibility and impact resistance, suitable for the automotive vibration environment. This parameter combination allows the rubber magnetic strip to maintain excellent gasoline resistance, flexibility, and impact resistance.

[0019] Preferably, the hydroxyl-terminated polydimethylsiloxane has a viscosity of 5000-10000 mPa·s at 25°C and a molecular weight of 20000-110000.

[0020] By adopting the above technical solution, the moderate viscosity ensures that it is evenly dispersed with nitrile rubber and methyl methacrylate, avoiding agglomeration or migration; the long molecular chain structure can enhance the flexibility of the rubber matrix and the toughness of the cross-linking network, while strengthening the interfacial interaction with the modified magnetic powder surface modification layer, further inhibiting the de-adhesion caused by gasoline penetration.

[0021] Preferably, the anti-aging agent is composed of anti-aging agent RD and anti-aging agent 4010 in a weight ratio of (3-5):1.

[0022] By adopting the above technical solution, a synergistic effect in anti-aging is achieved. Antioxidant RD resists thermo-oxidative aging, is suitable for the high-temperature environment of the vehicle, and inhibits the thermal degradation of rubber molecular chains; Antioxidant 4010 focuses on resisting ozone and fatigue aging, and copes with vehicle vibration and outdoor ozone corrosion. The two work together to resist the aging and corrosion of the magnetic strip in the harsh environment of the vehicle, avoid the decline of oil resistance, magnetic powder shedding or structural embrittlement, and ensure the structural stability and gasoline resistance of the magnetic strip during long-term use.

[0023] Secondly, this application provides a method for preparing a gasoline-resistant rubber magnetic strip, which adopts the following technical solution: A method for preparing a gasoline-resistant rubber magnetic strip includes the following preparation steps: S1. Stir and mix the magnetic powder and coupling agent to obtain a mixture; S2. Pass the nitrile rubber through a two-roll mill 5-7 times, then mix it with dispersant, anti-aging agent, zinc oxide, toughening agent, oil-resistant plasticizer and other mixtures. After the rubber compound cools to below 50°C, add bis-tert-butyl peroxide and triallyl isocyanurate, then pass it through a two-roll mill 6-8 times and make triangular wraps 3-5 times to obtain the compound. S3. The compounded rubber is calendered into sheets of the required thickness, vulcanized, and magnetized to obtain gasoline-resistant rubber magnetic strips.

[0024] By adopting the above technical solution, S1 first premixes the magnetic powder with the coupling agent to enhance the interfacial compatibility of the magnetic powder in advance; S2 uses a two-roll mill for thin-passing, internal mixing, and triangular packaging to ensure that the nitrile rubber and components such as dispersants, anti-aging agents, toughening agents, and oil-resistant plasticizers are uniformly dispersed. After cooling, a crosslinking agent is added to prevent premature reaction and ensure processing stability; S3 involves calendering, vulcanization, curing, and magnetization to form a dense crosslinked network in the rubber, with uniform distribution of magnetic powder. The entire process balances processing smoothness and product performance, ensuring both the thin-wall forming capability and dimensional accuracy of the magnetic strip, while also enhancing gasoline resistance, magnetic performance stability, and aging resistance. It is suitable for automated production, allowing the product to be used reliably in the harsh automotive environment for extended periods.

[0025] Preferably, the mixing temperature in step S2 is 100-110℃; In step S3, the vulcanization temperature is 160-180℃, the pressure is 10-15MPa, and the time is 10-20 minutes.

[0026] By adopting the above technical solution, the mixing temperature of 100-110℃ in S2 can promote the full integration and dispersion of nitrile rubber with components such as dispersants, toughening agents, oil-resistant plasticizers, and modified magnetic powder, while avoiding premature triggering of cross-linking reactions and ensuring smooth processing. The vulcanization conditions of 160-180℃, 10-15MPa, and 10-20 minutes in S3 can promote the efficient cross-linking of di-tert-butyl peroxide and triallyl isocyanurate, forming a dense and stable rubber network structure. The synergistic effect of the entire set of parameters and formulation ensures uniform distribution of magnetic powder and strong interfacial bonding, while also enhancing the magnetic strip's resistance to gasoline swelling and structural toughness, allowing the product to maintain excellent aging resistance in the harsh automotive environment and significantly extending its service life.

[0027] In summary, this application has the following beneficial effects: 1. In this application, magnetic powder and nitrile rubber are uniformly compounded under the action of a dispersant, ensuring basic magnetic properties and flexibility; a coupling agent strengthens the interfacial bonding force between the magnetic powder and rubber, inhibiting interfacial debonding caused by the gasoline environment; bis-tert-butyl peroxide and triallyl isocyanurate construct a dense cross-linked network, improving anti-swelling ability, resisting the attack of aromatics and olefins, significantly reducing the volume expansion rate, and avoiding fan speed instability, start-stop failure, or jamming. The oil-resistant plasticizer is a ternary compound of paraffin oil, adipic acid-based polyester, and sebacic acid-based polyester: paraffin oil improves processing fluidity and maintains flexibility; adipic acid-based polyester has strong compatibility with the cross-linked network and low migration, ensuring long-term oil resistance stability; sebacic acid-based polyester has better low-temperature flexibility and strengthens the barrier against gasoline components. With the addition of antioxidants to slow down environmental aging, zinc oxide to optimize cross-linking efficiency, and toughening agents to improve impact resistance and assembly reliability, this magnetic strip combines chemical stability, mechanical toughness, and dimensional stability under alternating high and low temperatures and vibration conditions in vehicles. It achieves a balance between oil resistance, impact resistance, and service life, making it suitable for reliable operation in long-term oil immersion environments. Detailed Implementation

[0028] The paraffin oil was purchased from Karamay Petrochemical, and its model number is KN4010.

[0029] The adipic acid-based polyester is ADK C-8 from Adico.

[0030] The sebacic acid-based polyester is Hallstar's Paraplex G-25.

[0031] The terpene resin was purchased from Guangdong Kemao Forestry Chemical Co., Ltd., model number KE-100.

[0032] The phenolic resin was purchased from Shengquan Group, model SQPF-506.

[0033] Example 1 A gasoline-resistant rubber magnetic strip is prepared by the following method: S1. Mix 850g of magnetic powder (ferrite magnetic powder) and 1g of coupling agent (γ-aminopropyltriethoxysilane) to obtain a mixture; S2. Pass 40g of nitrile rubber through a two-roll mill 5 times, then mix it with 5g of dispersant (sodium stearate), 1.5g of anti-aging agent, 2g of zinc oxide, 1.5g of toughening agent, 5g of oil-resistant plasticizer and other mixtures in an intensive mixing process at 100℃. After the rubber compound cools to below 50℃, add 1g of di-tert-butyl peroxide and 2g of triallyl isocyanurate, pass it through a two-roll mill 6 times, and then form a triangular bundle 3 times to obtain the compound. The oil-resistant plasticizer is composed of paraffin oil, adipic acid-based polyester and sebacic acid-based polyester in a weight ratio of 1:2:5; The toughening agent is composed of terpene resin and phenolic resin in a weight ratio of 1:1; The anti-aging agent is composed of anti-aging agent RD and anti-aging agent 4010 in a weight ratio of 3:1; The acrylonitrile content in nitrile rubber is 35%, and the Mooney viscosity is 40. S3. The compounded rubber is calendered into sheets of the required thickness, vulcanized at a temperature of 160℃, a pressure of 10MPa, and a time of 10 minutes, and then magnetized to obtain gasoline-resistant rubber magnetic strips.

[0034] The difference between Examples 2-3 and Example 1 lies in the types, amounts, and parameters of raw materials used to prepare the gasoline-resistant rubber magnetic strips. Specific differences are shown in Table 1. Table 1. Types, amounts, and parameters of raw materials for preparing gasoline-resistant rubber magnetic strips.

[0035] Example 4 A gasoline-resistant rubber magnetic strip, the difference between this embodiment and Embodiment 1 is that the magnetic powder is a modified magnetic powder, prepared by the following method: 1) Mix 70g of organic bentonite and 350g of anhydrous ethanol, and disperse by ultrasonication to obtain a suspension; 2) Mix 3-0g of hydroxyethyl methacrylate with 80g of anhydrous ethanol, add the mixture to the suspension, stir at 55℃ for 1h, then add 1000g of magnetic powder, heat to 70℃ and stir for 20min, dry to obtain modified magnetic powder.

[0036] Example 5 A gasoline-resistant rubber magnetic strip, the difference between this embodiment and Embodiment 1 is that the magnetic powder is a modified magnetic powder, prepared by the following method: 1) Mix 100g of organic bentonite and 400g of anhydrous ethanol, and disperse by ultrasonication to obtain a suspension; 2) Mix 50g of hydroxyethyl methacrylate with 100g of anhydrous ethanol, add the mixture to the suspension, stir at 60℃ for 2h, then add 1000g of magnetic powder, heat to 75℃ and stir for 30min, and recover the ethanol by vacuum distillation to obtain the modified magnetic powder.

[0037] Example 6 A gasoline-resistant rubber magnetic strip, the difference between this embodiment and embodiment 1 is that 1000g of nitrile rubber is mixed with 10g of methyl methacrylate, 50g of hydroxyl-terminated polydimethylsiloxane and 1g of initiator (diisopropylbenzene peroxide) to obtain pretreated nitrile rubber.

[0038] The viscosity of hydroxyl-terminated polydimethylsiloxane at 25°C is 5000 mPa·s, and its molecular weight is 20000.

[0039] Example 7 A gasoline-resistant rubber magnetic strip, the difference between this embodiment and embodiment 4 is that 1500g of nitrile rubber is mixed with 20g of methyl methacrylate, 100g of hydroxyl-terminated polydimethylsiloxane and 3g of initiator (diisopropylbenzene peroxide) to obtain pretreated nitrile rubber.

[0040] The viscosity of hydroxyl-terminated polydimethylsiloxane at 25°C is 10,000 mPa·s, and its molecular weight is 110,000.

[0041] Example 8 A gasoline-resistant rubber magnetic strip, the difference between this embodiment and Embodiment 1 is that the weight ratio of paraffin oil, the adipic acid-based polyester and the sebacic acid-based polyester is 5:2:1.

[0042] Example 9 A gasoline-resistant rubber magnetic strip, the difference between this embodiment and Embodiment 1 is that the toughening agent is a terpene resin.

[0043] Comparative Example Comparative Example 1 A gasoline-resistant rubber magnetic strip, the difference between this comparative example and Example 1 is that the oil-resistant plasticizer is paraffin oil.

[0044] Comparative Example 2 A gasoline-resistant rubber magnetic strip, the difference between this comparative example and Example 1 is that the oil-resistant plasticizer is composed of paraffin oil and adipic acid-based polyester in a weight ratio of 1:2.

[0045] Comparative Example 3 A gasoline-resistant rubber magnetic strip, which differs from Example 1 in that no oil-resistant plasticizer is added.

[0046] Comparative Example 4 A gasoline-resistant rubber magnetic strip, the difference between this comparative example and Example 1 is that triallyl isocyanurate is replaced with benzoyl peroxide.

[0047] Comparative Example 5 A gasoline-resistant rubber magnetic strip, which differs from Example 1 in that it does not contain bis-tert-butyl peroxide.

[0048] Comparative Example 6 A gasoline-resistant rubber magnetic strip, the difference between this comparative example and Example 1 is that the amount of toughening agent used is 7g.

[0049] Detection methods / test methods Gasoline resistance test: The gasoline-resistant rubber magnetic strips prepared in Examples 1-9 and Comparative Examples 1-6 were placed in a mixture of 30% benzene and 70% gasoline and subjected to a temperature of 23℃±2℃*200h, and the volume expansion rate was then tested. Volume expansion rate: Refer to GB / T 7759 / Volume Expansion Method.

[0050] Interfacial bonding strength: After bending the gasoline-resistant rubber magnetic strips prepared in Examples 1-9 and Comparative Examples 1-6 180° 100 times, observe the magnetic powder shedding. If there is no shedding, perform gasoline resistance performance testing and bend the strips again to observe the magnetic powder shedding.

[0051] Flexibility: The elongation rate was tested according to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber" using dumbbell-shaped specimens at 500 mm / min ± 50 mm / min.

[0052] Impact resistance: Tear strength was tested according to GB / T 529, ensuring an assembly breakage rate of <0.5%. Experimental data are shown in Table 2. Table 2. Experimental data of Examples 1-9 and Comparative Examples 1-6

[0053] As can be seen from the experimental data in the table, the formulation in this application achieves a comprehensive improvement in oil resistance, interfacial bonding strength and mechanical strength, and solves the problems of gasoline swelling and de-adhesion of traditional magnetic strips.

[0054] Comparing Example 1 with Comparative Examples 1-3, it is shown that the oil-resistant plasticizer composed of paraffin oil, adipic acid-based polyester and sebacic acid-based polyester effectively prevents gasoline penetration, maintains the stability of the cross-linked network, and effectively ensures the flexibility and mechanical strength of the magnetic strip while inhibiting swelling and interfacial debonding.

[0055] Compared with Comparative Examples 4-6, the crosslinking system constructed by synergistic use of bis-tert-butyl peroxide and triallyl isocyanurate, by only increasing the amount of toughening agent, can more effectively control the volume expansion rate at a lower level, while maintaining excellent tensile strength and tear strength. Although excessive toughening agent can improve interfacial bonding, it leads to an increase in expansion rate and a decrease in mechanical properties. This illustrates the key role of balancing the crosslinking system and the amount of toughening agent in achieving optimal overall oil resistance, mechanical strength and processing performance.

[0056] Comparing Example 1 with Examples 4-5, it is evident that the synergistic modification of magnetic powder with organic bentonite and hydroxyethyl methacrylate further reduces the volume expansion rate. The interfacial bonding force after the oil resistance test is improved from "slight detachment" to "no detachment". At the same time, the tensile strength and tear strength are improved, which fully verifies that the composite barrier layer formed on the surface of the modified magnetic powder can effectively inhibit gasoline penetration and strengthen the bonding between the magnetic powder and rubber. Thus, while maintaining excellent mechanical properties, it enhances the long-term oil resistance stability and structural integrity of the magnetic strip.

[0057] Comparing Examples 1 with Examples 6-7, it is evident that the volume expansion rate of nitrile rubber is reduced after pretreatment with methyl methacrylate and hydroxyl-terminated polydimethylsiloxane. In Example 7, due to the synergistic effect of the modified magnetic powder and the pretreated rubber, the tensile strength and tear strength are improved, and there is no interface detachment before and after the oil resistance test. This fully verifies that the pretreatment can introduce oil-resistant groups into the rubber molecular chain and enhance interfacial activity, forming a stronger bond with the magnetic powder modified layer. Thus, better gasoline swelling resistance, mechanical strength and long-term structural stability are achieved with a lower amount of plasticizer.

[0058] Comparing Example 1 with Examples 8-9 demonstrates the key role of the 1:2:5 ratio dominated by sebacic acid polyester and the terpene resin / phenolic resin compound system in synergistically inhibiting gasoline swelling, maintaining high tensile strength and mechanical strength, thus achieving an optimal balance between oil resistance, flexibility and processing performance.

[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 gasoline resistant rubber magnetic stripe, characterized by, It is prepared from the following raw materials in parts by weight: 85-92 parts of magnetic powder 4-8 parts of nitrile rubber Dispersant 0.5-1 part 0.1-0.5 parts of coupling agent Anti-aging agent 0.15-0.5 parts 0.2-0.5 parts zinc oxide 0.1-0.2 parts of bis-tert-butyl peroxide 0.2-0.5 parts of triallyl isocyanurate Toughening agent 0.15-0.6 parts Oil-resistant plasticizer 0.5-1 part The oil-resistant plasticizer is composed of paraffin oil, adipic acid-based polyester, and sebacic acid-based polyester.

2. The gasoline resistant rubber magnetic stripe of claim 1, wherein: The weight ratio of the paraffin oil, the adipic acid-based polyester, and the sebacic acid-based polyester is (1-2):(2-3):

5.

3. The gasoline-resistant rubber magnetic strip according to claim 1, characterized in that: The magnetic powder is a modified magnetic powder, prepared by the following method: 1) Mix 7-10 parts of organic bentonite and 35-40 parts of anhydrous ethanol by weight, and disperse by ultrasonication to obtain a suspension; 2) According to the weight, mix 3-5 parts of hydroxyethyl methacrylate with 8-10 parts of anhydrous ethanol, add the mixture to the suspension, stir at 55-60℃ for 1-2 hours, then add 100 parts of magnetic powder, heat to 70-75℃ and stir for 20-30 minutes, and dry to obtain modified magnetic powder.

4. The gasoline-resistant rubber magnetic strip according to claim 1, characterized in that: The toughening agent is composed of terpene resin and phenolic resin in a weight ratio of (1-5):

1.

5. The gasoline-resistant rubber magnetic strip according to claim 1, characterized in that, The nitrile rubber is pretreated by the following method: By weight, 10-15 parts of nitrile rubber are mixed with 0.3-0.5 parts of methyl methacrylate, 0.5-1 parts of hydroxyl-terminated polydimethylsiloxane and 0.01-0.03 parts of initiator to obtain pretreated nitrile rubber.

6. The gasoline-resistant rubber magnetic strip according to claim 5, characterized in that: The acrylonitrile content in the nitrile rubber is 35-50%, and the Mooney viscosity is 40-70.

7. The gasoline-resistant rubber magnetic strip according to claim 5, characterized in that: The hydroxyl-terminated polydimethylsiloxane has a viscosity of 5000-10000 mPa·s at 25°C and a molecular weight of 20000-110000.

8. The gasoline-resistant rubber magnetic strip according to claim 1, characterized in that: The anti-aging agent is composed of anti-aging agent RD and anti-aging agent 4010 in a weight ratio of (3-5):

1.

9. A method for preparing a gasoline-resistant rubber magnetic strip as described in any one of claims 1-8, characterized in that, The preparation steps include the following: S1. Stir and mix the magnetic powder and coupling agent to obtain a mixture; S2. Pass the nitrile rubber through a two-roll mill 5-7 times, then mix it with dispersant, anti-aging agent, zinc oxide toughening agent, oil-resistant plasticizer and other mixtures. After the rubber compound cools to below 50°C, add bis-tert-butyl peroxide and triallyl isocyanurate, then pass it through a two-roll mill 6-8 times and make triangular wraps 3-5 times to obtain the compound. S3. The compounded rubber is calendered into sheets of the required thickness, vulcanized, and magnetized to obtain gasoline-resistant rubber magnetic strips.

10. The method for preparing the gasoline-resistant rubber magnetic strip according to claim 9, characterized in that: The mixing temperature in step S2 is 100-110℃; In step S3, the vulcanization temperature is 160-180℃, the pressure is 10-15MPa, and the time is 10-20 minutes.

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