Sealing material resistant to NMP (N-Methyl Pyrrolidone) strong polar solvent

Abstract

Belonging to the technical field of sealing materials, the invention discloses an NMP strong polar solvent resistant sealing material, which comprises the following raw materials by weight: 100 parts of ethylene propylene diene monomer, 3-7 parts of modified montmorillonite, 30-40 parts of white carbon black, 5 parts of zinc oxide, 1 part of stearic acid, 1-3 parts of a surfactant, 2-4 parts of peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, and 5 parts of paraffin oil. The modified montmorillonite is thiourea alkyl imidazoline quaternary ammonium salt modified montmorillonite; according to the invention, the ethylene propylene diene monomer is used as a main material, the white carbon black and the modified montmorillonite are used as reinforcing fillers, and the surfactant is introduced as an auxiliary agent, so that the internal network structure of the rubber is perfected and optimized under the mutual synergistic effect of the raw materials; the final sealing material has good mechanical properties, NMP strong polar solvent corrosion resistance and good aging resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of sealing materials, and in particular relates to a sealing material resistant to NMP strong polar solvent. Background Art

[0002] NMP is the abbreviation of N-methylpyrrolidone, which is a highly polar aprotic solvent with the advantages of high boiling point, strong polarity, low viscosity, strong dissolving power, non-corrosiveness, low toxicity, good chemical and thermal stability, and complete miscibility with water. It is mainly used in coatings, lithium batteries, plastics, chemical production agents, agricultural chemicals, cleaning, cleaning and degreasing, polymer solvents and polymerization reaction solvents.

[0003] With the development of new energy vehicles, lithium-ion batteries are currently the most ideal secondary battery. As one of the key raw materials in lithium-ion battery manufacturing, NMP directly impacts the quality of lithium-ion battery slurry coating and environmental protection requirements. According to industry research data, while the proportion of NMP in the value of lithium-ion batteries varies depending on model and specification, overall, NMP accounts for approximately 3%-6% of the manufacturing cost of lithium-ion batteries. The market size and demand for NMP are also growing alongside the growth of lithium-ion batteries, particularly energy storage batteries and power batteries.

[0004] NMP is a highly polar solvent that is volatile at room temperature or under stirring and heating conditions. Therefore, to minimize solvent loss and environmental pollution, NMP must be incorporated into sealing materials during transportation and use. Existing sealing material preparation processes typically use a blend of modified EPDM (ethylene propylene diene monomer) raw materials to create a rubber material, which is then molded through high-temperature, high-pressure in-mold molding. While products produced with this formulation exhibit sufficient tensile strength and low compression set, their tolerance to long-term exposure to NMP solutions is limited. Especially in high-temperature environments, the performance of the sealing ring deteriorates further, shortening its service life and failing to meet customer requirements for the full lifecycle of the sealing ring. Summary of the Invention

[0005] The present invention aims to provide a sealing material resistant to NMP, a highly polar solvent, to solve the problem that existing sealing materials have poor tolerance to NMP.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A sealing material resistant to NMP strong polar solvent, comprising the following raw materials in parts by weight:

[0008] 100 parts of EPDM rubber, 3-7 parts of modified montmorillonite, 30-40 parts of white carbon black, 5 parts of zinc oxide, 1 part of stearic acid, 1-3 parts of surfactant, 2-4 parts of diisopropyl peroxide, 1 part of triallyl isocyanurate, and 5 parts of paraffin oil.

[0009] The modified montmorillonite is thiourea-alkyl imidazoline quaternary ammonium salt modified montmorillonite.

[0010] The surfactant is a surfactant carrying a borate structure.

[0011] As a preferred technical solution of the present invention, the modified montmorillonite is prepared by the following steps:

[0012] Sodium montmorillonite is added to deionized water, stirred at room temperature for 10-30 minutes, aged for 24 hours, then heated to 60-80°C, and an aqueous solution of thiourea alkyl imidazoline quaternary ammonium salt is added dropwise. After the addition is complete, the mixture is stirred for 3-5 hours at this temperature, centrifuged, and the precipitate is washed with deionized water and dried to obtain modified montmorillonite.

[0013] As a preferred technical solution of the present invention, the mass ratio of sodium montmorillonite and thiourea-based alkyl imidazoline quaternary ammonium salt is 10:3.3-6.6. The sodium montmorillonite is treated with thiourea-based alkyl imidazoline quaternary ammonium salt, and the hydrophilic end of the thiourea-based alkyl imidazoline quaternary ammonium salt enters the montmorillonite interlayer, increasing the interlayer spacing and improving the contact area between the montmorillonite and the rubber matrix. The hydrophobic long chain is compatible with the rubber molecular chain, enhancing the interfacial adhesion between the montmorillonite and the rubber matrix, thereby increasing the ability of the composite material to resist stress during fracture and improving the mechanical properties of the sealing material. In addition, since the montmorillonite lamellar structure has good barrier properties, it is beneficial to improve the solvent resistance and gas barrier properties of the composite material, and the thiourea group carried by the thiourea-based alkyl imidazoline quaternary ammonium salt can effectively decompose hydrogen peroxide, inhibit the oxidative aging reaction of the rubber, and effectively improve the aging resistance of the composite material.

[0014] As a preferred technical solution of the present invention, the thiourea-alkyl imidazoline quaternary ammonium salt is prepared by the following steps:

[0015] Add organic carboxylic acid, diethylenetriamine and xylene into a flask, stir and react at 140-160°C for 2 hours, then heat to 190-210°C for 2 hours, cool to 90-110°C, slowly add benzyl chloride dropwise, keep warm and react for 3 hours, then add thiourea, stir and react for 2-3 hours. After the reaction, remove xylene by vacuum distillation to obtain thiourea alkyl imidazoline quaternary ammonium salt.

[0016] As a preferred technical solution of the present invention, the usage ratio of organic carboxylic acid, diethylenetriamine, benzyl chloride and thiourea is 0.1 mol: 0.12 mol: 0.1 mol: 7.6-8.8 g. The organic carboxylic acid and diethylenetriamine are used as raw materials, and a cyclization reaction, a quaternization reaction and then a reaction with thiourea are performed to obtain a thiourea-based alkyl imidazoline quaternary ammonium salt.

[0017] As a preferred technical solution of the present invention, the organic carboxylic acid is a saturated carboxylic acid and / or an unsaturated carboxylic acid, preferably an unsaturated carboxylic acid. The thiourea-based alkyl imidazoline quaternary ammonium salt prepared with the unsaturated carboxylic acid contains an unsaturated double bond. Under the action of diisopropyl peroxide, it can react with the double bonds on the rubber molecular chain, which is conducive to the formation of a cross-linked network and optimizes the mechanical properties of the sealing material.

[0018] As a preferred technical solution of the present invention, the saturated carboxylic acid is at least one of capric acid, valeric acid, palmitic acid and stearic acid.

[0019] As a preferred technical solution of the present invention, the unsaturated carboxylic acid is at least one of oleic acid, linoleic acid and arachidonic acid.

[0020] As a preferred technical solution of the present invention, the surfactant is prepared by the following steps:

[0021] Add boric acid, diethanolamine and toluene to a flask, heat to reflux and react for 8-10 hours, then remove toluene by distillation under reduced pressure, add anhydrous ethanol, long-chain halogenated olefins and anhydrous sodium carbonate to the distillation product, stir evenly, stir at 70-75°C and react for 8-10 hours, then remove anhydrous ethanol by rotary evaporation to obtain a surfactant.

[0022] As a preferred technical solution of the present invention, the usage ratio of boric acid, diethanolamine, toluene, anhydrous ethanol, long-chain halogenated olefin and anhydrous sodium carbonate is 0.05 mol: 0.1-0.12 mol: 100-150 mL: 100-200 mL: 0.1 mol: 10.5-11.0 g. First, boric acid and diethanolamine are subjected to an esterification reaction to obtain diethanolamine borate, and then the long-chain halogenated olefin is used as a quaternization agent to obtain a surfactant carrying a borate structure.

[0023] As a preferred technical solution of the present invention, the long-chain halogenated olefin is 9-bromo-1-nonene and / or 11-bromo-1-undecene.

[0024] The preparation method of the above-mentioned sealing material resistant to NMP highly polar solvent comprises the following steps:

[0025] According to the raw material ratio, EPDM rubber is added to an internal mixer and plasticized for 3-5 minutes. Modified montmorillonite is added and plasticized at 100-110°C for 8-10 minutes. Then, white carbon black, stearic acid, surfactant, zinc oxide, triallyl isocyanurate and paraffin oil are added in sequence and plasticized at 100-110°C for 8-10 minutes. Then, plasticized at 115-125°C for 8-10 minutes, cooled to 50-60°C, diisopropyl peroxide is added, and vulcanized at 130-150°C and 10-15MPa for 60-75 minutes to obtain a sealing material resistant to the strong polar solvent NMP.

[0026] As a preferred technical solution of the present invention, during the plasticating process, the rotation speed of the internal mixer is 40-50 r / min.

[0027] Beneficial effects of the present invention:

[0028] 1. The present invention provides a sealing material resistant to NMP, a highly polar solvent. The sealing material uses EPDM rubber as a main material, white carbon black and modified montmorillonite as reinforcing fillers, and a surfactant as an auxiliary agent. Under the synergistic effect of the raw materials, the internal network structure of the rubber is improved and optimized, so that the final sealing material has good mechanical properties and resistance to corrosion by NMP, a highly polar solvent, and good aging resistance.

[0029] 2. The present invention utilizes thiourea-based alkyl imidazoline quaternary ammonium salt to treat sodium montmorillonite. The hydrophilic end of the thiourea-based alkyl imidazoline quaternary ammonium salt enters the montmorillonite interlayer, increases the interlayer spacing, and improves the contact area between the montmorillonite and the rubber matrix. The hydrophobic long chain is compatible with the rubber molecular chain, thereby enhancing the interfacial adhesion between the montmorillonite and the rubber matrix, thereby increasing the ability of the composite material to resist stress during fracture and improving the mechanical properties of the sealing material. In addition, since the montmorillonite lamellar structure has good barrier properties, it is beneficial to improve the solvent resistance and gas barrier properties of the composite material. The thiourea group carried by the thiourea-based alkyl imidazoline quaternary ammonium salt can effectively decompose hydroperoxides, inhibit the oxidative aging reaction of the rubber, and effectively improve the aging resistance of the sealing material.

[0030] 3. The surfactant in the present invention is a surfactant carrying a borate structure. The positively charged nitrogen and negatively charged bromide ions on the surfactant molecular chain interact with the silanol group on the surface of silica, which can weaken the interaction between silica and silica, and is beneficial to the uniform dispersion of silica in the rubber material, so that silica can fully exert its reinforcing effect; the unsaturated double bonds carried by the surfactant can react with the double bonds on the rubber molecular chain under the action of diisopropylbenzene peroxide, which is beneficial to the formation of a cross-linked network and optimizes the mechanical properties of the sealing material. In addition, the borate structure carried by the surfactant is a dynamic covalent bond. When the rubber material is subjected to external force, the borate bond can break, allowing the rubber molecular chain to slide relatively, thereby absorbing and dissipating the external force energy and reducing the stress concentration inside the rubber; when the external force is removed, the borate bond can be reformed, allowing the rubber material to return to its original shape or state, thereby improving the elasticity and compression deformation resistance of the rubber. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0032] The terms used in the examples of this application are for the purpose of describing specific implementation rules only and are not intended to limit this application. The singular forms "a", "an", "the" and "the" used in the implementation rules of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0033] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution. Some or all steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0034] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass described in the examples of this application may be a mass unit known in the chemical industry, such as μg, mg, g, kg, etc.

[0035] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0037] The technical solution of the present application is illustrated below through specific embodiments and comparative examples.

[0038] Preparation Example 1

[0039] This preparation example provides a modified montmorillonite, and the preparation steps are as follows:

[0040] 10 g of sodium montmorillonite was added to 100 mL of deionized water, stirred at room temperature for 10 min, aged for 24 h, then heated to 60 ° C, and a mixed solution consisting of 3.3 g of thiourea alkyl imidazoline quaternary ammonium salt and 20 mL of deionized water was added dropwise. After the addition was completed, the mixture was kept warm and stirred for 3 h, centrifuged, and the precipitate was washed with deionized water and dried to obtain modified montmorillonite.

[0041] The thiourea-based alkyl imidazoline quaternary ammonium salt is prepared by the following steps:

[0042] 0.1 mol capric acid, 0.12 mol diethylenetriamine and 300 mL xylene were added to a flask, stirred and reacted at 140°C for 2 h, then heated to 190°C for 2 h, cooled to 90°C, 0.1 mol benzyl chloride was slowly added dropwise, kept warm and reacted for 3 h, then 7.6 g thiourea was added, stirred and reacted for 2 h, and after the reaction was completed, xylene was removed by vacuum distillation to obtain thiourea alkyl imidazoline quaternary ammonium salt.

[0043] Preparation Example 2

[0044] This preparation example provides a modified montmorillonite, and the preparation steps are as follows:

[0045] 10 g of sodium montmorillonite was added to 150 mL of deionized water, stirred at room temperature for 20 min, aged for 24 h, then heated to 70 ° C, and a mixed solution consisting of 4.8 g of thiourea alkyl imidazoline quaternary ammonium salt and 20 mL of deionized water was added dropwise. After the addition was completed, the mixture was kept warm and stirred for 4 h, centrifuged, and the precipitate was washed with deionized water and dried to obtain modified montmorillonite.

[0046] The thiourea alkyl imidazoline quaternary ammonium salt is prepared by the following steps:

[0047] 0.1 mol of capric acid, 0.12 mol of diethylenetriamine and 400 mL of xylene were added to a flask, stirred and reacted at 150°C for 2 h, then heated to 200°C and reacted for 2 h, cooled to 100°C, 0.1 mol of benzyl chloride was slowly added dropwise, and the temperature was kept warm for 3 h. Then 8.0 g of thiourea was added and stirred and reacted for 2.5 h. After the reaction was completed, xylene was removed by vacuum distillation to obtain a thiourea alkyl imidazoline quaternary ammonium salt.

[0048] Preparation Example 3

[0049] This preparation example provides a modified montmorillonite, and the preparation steps are as follows:

[0050] 10 g of sodium montmorillonite was added to 200 mL of deionized water, stirred at room temperature for 30 min, aged for 24 h, then heated to 80 ° C, and a mixed solution consisting of 6.6 g of thiourea alkyl imidazoline quaternary ammonium salt and 20 mL of deionized water was added dropwise. After the addition was completed, the mixture was stirred for 5 h at room temperature and centrifuged. The precipitate was washed with deionized water and dried to obtain modified montmorillonite.

[0051] The thiourea-based alkyl imidazoline quaternary ammonium salt is prepared by the following steps:

[0052] 0.1 mol of capric acid, 0.12 mol of diethylenetriamine and 500 mL of xylene were added to a flask, stirred and reacted at 160°C for 2 h, then heated to 210°C for 2 h, cooled to 110°C, 0.1 mol of benzyl chloride was slowly added dropwise, kept warm and reacted for 3 h, then 8.8 g of thiourea was added, stirred and reacted for 3 h, and after the reaction was completed, xylene was removed by vacuum distillation to obtain thiourea alkyl imidazoline quaternary ammonium salt.

[0053] Preparation Example 4

[0054] A modified montmorillonite, compared with Preparation Example 1, the only difference is that capric acid is replaced by an equal molar amount of oleic acid.

[0055] Comparative Example 1

[0056] A modified montmorillonite, compared with Preparation Example 1, differs only in that the thiourea-alkyl imidazoline quaternary ammonium salt is replaced by an equal mass of hexadecyltrimethylammonium bromide.

[0057] Example 1

[0058] A sealing material resistant to NMP strong polar solvent, comprising the following raw materials in parts by weight:

[0059] 100 parts of EPDM rubber, 3 parts of modified montmorillonite of Preparation Example 1, 30 parts of white carbon black, 5 parts of zinc oxide, 1 part of stearic acid, 1 part of surfactant, 2 parts of diisopropyl peroxide, 1 part of triallyl isocyanurate, and 5 parts of paraffin oil.

[0060] The surfactant is prepared by the following steps:

[0061] Add 0.05 mol of boric acid, 0.1 mol of diethanolamine and 100 mL of toluene to a flask, heat to reflux and react for 8 hours, then remove the toluene by distillation under reduced pressure, add 100 mL of anhydrous ethanol, 0.1 mol of 9-bromo-1-nonene and 10.5 g of anhydrous sodium carbonate to the distillation product, stir evenly, stir at 70°C for 8 hours, then remove the anhydrous ethanol by rotary evaporation to obtain a surfactant.

[0062] The preparation method of the above-mentioned sealing material resistant to NMP highly polar solvent comprises the following steps:

[0063] According to the raw material ratio, EPDM rubber was added to an internal mixer and plasticized for 3 minutes at a speed of 40 r / min. Modified montmorillonite was added and plasticized for 8 minutes at 100°C. Then, white carbon black, stearic acid, surfactant, zinc oxide, triallyl isocyanurate and paraffin oil were added in sequence and plasticized for 8 minutes at 100°C, then plasticized for 10 minutes at 115°C, cooled to 50°C, and diisopropyl peroxide was added. The mixture was vulcanized at 130°C and 10 MPa for 60 minutes to obtain a sealing material resistant to the strong polar solvent NMP.

[0064] Example 2

[0065] A sealing material resistant to NMP strong polar solvent, comprising the following raw materials in parts by weight:

[0066] 100 parts of EPDM rubber, 5 parts of modified montmorillonite of Preparation Example 1, 35 parts of white carbon black, 5 parts of zinc oxide, 1 part of stearic acid, 2 parts of surfactant, 3 parts of diisopropyl peroxide, 1 part of triallyl isocyanurate, and 5 parts of paraffin oil.

[0067] The surfactant is prepared by the following steps:

[0068] 0.05 mol of boric acid, 0.11 mol of diethanolamine and 130 mL of toluene were added to a flask, and the temperature was raised to reflux for reaction for 9 hours. The toluene was then removed by distillation under reduced pressure. 150 mL of anhydrous ethanol, 0.1 mol of 9-bromo-1-nonene and 10.5 g of anhydrous sodium carbonate were added to the distillation product, and the mixture was stirred evenly. The mixture was stirred at 75° C. for reaction for 9 hours, and the anhydrous ethanol was then removed by rotary evaporation to obtain a surfactant.

[0069] The preparation method of the above-mentioned sealing material resistant to NMP highly polar solvent comprises the following steps:

[0070] According to the raw material ratio, EPDM rubber was added to an internal mixer and plasticized for 4 minutes at a speed of 45 r / min. Modified montmorillonite was added and plasticized at 105°C for 9 minutes. Then, white carbon black, stearic acid, surfactant, zinc oxide, triallyl isocyanurate and paraffin oil were added in sequence and plasticized at 105°C for 9 minutes, then plasticized at 120°C for 9 minutes, cooled to 55°C, diisopropyl peroxide was added, and vulcanized at 140°C and 12 MPa for 75 minutes to obtain a sealing material resistant to the strong polar solvent NMP.

[0071] Example 3

[0072] A sealing material resistant to NMP strong polar solvent, comprising the following raw materials in parts by weight:

[0073] 100 parts of EPDM rubber, 7 parts of modified montmorillonite of Preparation Example 1, 40 parts of white carbon black, 5 parts of zinc oxide, 1 part of stearic acid, 3 parts of surfactant, 4 parts of diisopropyl peroxide, 1 part of triallyl isocyanurate, and 5 parts of paraffin oil.

[0074] The surfactant is prepared by the following steps:

[0075] 0.05 mol of boric acid, 0.12 mol of diethanolamine and 150 mL of toluene were added to a flask, and the temperature was raised to reflux for reaction for 10 h. The toluene was then removed by distillation under reduced pressure. 200 mL of anhydrous ethanol, 0.1 mol of 9-bromo-1-nonene and 11.0 g of anhydrous sodium carbonate were added to the distillation product, and the mixture was stirred evenly. The mixture was stirred at 75 ° C for reaction for 10 h, and the anhydrous ethanol was then removed by rotary evaporation to obtain a surfactant.

[0076] The preparation method of the above-mentioned sealing material resistant to NMP highly polar solvent comprises the following steps:

[0077] According to the raw material ratio, EPDM rubber was added to an internal mixer and plasticized for 5 minutes at a speed of 50 r / min. Modified montmorillonite was added and plasticized for 10 minutes at 110°C. Then, white carbon black, stearic acid, surfactant, zinc oxide, triallyl isocyanurate and paraffin oil were added in sequence and plasticized for 10 minutes at 110°C, then plasticized for 10 minutes at 125°C, cooled to 60°C, diisopropyl peroxide was added, and vulcanized at 150°C and 15 MPa for 60 minutes to obtain a sealing material resistant to the strong polar solvent NMP.

[0078] Example 4

[0079] A sealing material resistant to the highly polar solvent NMP is disclosed. Compared with Example 1, the only difference is that the modified montmorillonite in Example 1 is replaced by an equal weight portion of the product obtained in Preparation Example 2.

[0080] Example 5

[0081] A sealing material resistant to the highly polar solvent NMP is disclosed. Compared with Example 1, the only difference is that the modified montmorillonite in Example 1 is replaced by an equal weight portion of the product obtained in Preparation Example 3.

[0082] Example 6

[0083] A sealing material resistant to the highly polar solvent NMP is disclosed. Compared with Example 1, the only difference is that the modified montmorillonite in Example 1 is replaced by an equal weight portion of the product obtained in Preparation Example 4.

[0084] Example 7

[0085] A sealing material resistant to the highly polar solvent NMP is disclosed. Compared with Example 1, the only difference is that 9-bromo-1-nonene in Example 1 is replaced by an equal molar amount of 11-bromo-1-undecene.

[0086] Example 8

[0087] A sealing material resistant to the highly polar solvent NMP is disclosed. Compared with Example 2, the only difference is that the modified montmorillonite in Example 2 is replaced by an equal weight portion of the product obtained in Preparation Example 4.

[0088] Comparative Example 1

[0089] A sealing material resistant to the highly polar solvent NMP is disclosed. Compared with Example 1, the only difference is that the modified montmorillonite in Example 1 is replaced by an equal weight portion of the product obtained in Control Example 1.

[0090] Comparative Example 2

[0091] A sealing material resistant to the highly polar solvent NMP is disclosed. Compared with Example 1, the only difference is that 9-bromo-1-nonene in Example 1 is replaced by an equal molar amount of 1-bromo-hexadecane.

[0092] Comparative Example 3

[0093] A sealing material resistant to a strong polar solvent such as NMP is disclosed. Compared with Example 1, the only difference is that the surfactant in Example 1 is replaced with methacryloyloxypropyltrimethoxysilane of equal mass.

[0094] Comparative Example 4

[0095] A sealing material resistant to the highly polar solvent NMP is disclosed. Compared with Example 1, the only difference is that the surfactant in Example 1 is removed.

[0096] The sealing materials obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were subjected to performance tests, and the test process was as follows:

[0097] (1) Tensile strength was measured in accordance with GB / T528-2009 “Vulcanized rubber or thermoplastic rubber — Determination of tensile stress-strain properties” at a tensile speed of 500 mm / min.

[0098] (2) Heat-oxidative aging resistance: The test is carried out in accordance with GB / T3512-2014 “Hot air accelerated aging and heat resistance test for vulcanized rubber or thermoplastic rubber”, at 200°C for 72 hours.

[0099] (3) The sealing materials prepared in each group were immersed in NMP (N-methylpyrrolidone) for 48 hours and the tensile strength was tested again. The smaller the change in tensile strength, the higher the tolerance to NMP.

[0100] (4) Compression set was carried out in accordance with GB / T7759.1-2015 “Determination of compression set of vulcanized rubber or thermoplastic rubber”, with the test conditions being 125°C for 72 h.

[0101] The test results are shown in Table 1:

[0102] Table 1

[0103]

[0104]

[0105] It can be seen from the data recorded in Table 1 that the sealing materials obtained in Examples 1 to 3 have good tensile strength, aging resistance, NMP resistance and low compression set, among which Example 2 has the best performance. It can be seen from the test results in Examples 1 and 6, and Examples 2 and 8 that the modified montmorillonite prepared using unsaturated carboxylic acid as raw material is more conducive to obtaining high-performance sealing materials. It can be seen from the test results in Examples 1, 4 and 5 that the sealing materials obtained with the modified montmorillonite prepared in Preparation Example 1, Preparation Example 2 and Preparation Example 3 have similar performance. It can be seen from the test results in Examples 1 and 7 that, compared with 9-bromo-1-nonene, the surfactant prepared using 11-bromo-1-undecene as raw material is more conducive to obtaining high-performance sealing materials.

[0106] It can be seen from the test results in Example 1 and Comparative Example 1 that, compared with the montmorillonite modified with hexadecyltrimethylammonium bromide, the sealing material obtained by the modified montmorillonite provided by the present invention has significantly improved aging resistance and NMP resistance.

[0107] It can be seen from the test results of Example 1 and Comparative Examples 2, 3 and 4 that the surfactant provided by the present invention is more conducive to obtaining a sealing material with good mechanical properties, aging resistance and NMP resistance.

[0108] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0109] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A sealing material resistant to NMP strong polar solvent, characterized in that, Calculated by weight, it includes the following raw materials: 100 parts of EPDM rubber, 3-7 parts of modified montmorillonite, 30-40 parts of white carbon black, 5 parts of zinc oxide, 1 part of stearic acid, 1-3 parts of surfactant, 2-4 parts of diisopropyl peroxide, 1 part of triallyl isocyanurate, and 5 parts of paraffin oil; The modified montmorillonite is thiourea-alkyl imidazoline quaternary ammonium salt modified montmorillonite; The surfactant is a surfactant carrying a borate structure.

2. A sealing material resistant to NMP strong polar solvent according to claim 1, characterized in that, The modified montmorillonite is prepared by the following steps: Sodium montmorillonite is added to deionized water, stirred at room temperature for 10-30 minutes, aged for 24 hours, heated to 60-80°C, and an aqueous solution of thiourea alkyl imidazoline quaternary ammonium salt is added dropwise. After the addition is complete, the mixture is stirred at this temperature for 3-5 hours, centrifuged, and the precipitate is washed with deionized water and dried to obtain modified montmorillonite.

3. A sealing material resistant to NMP strong polar solvent according to claim 2, characterized in that, The mass ratio of sodium montmorillonite to thiourea alkyl imidazoline quaternary ammonium salt is 10:3.3-6.

6.

4. A sealing material resistant to NMP strong polar solvent according to claim 2, characterized in that, The thiourea-based alkyl imidazoline quaternary ammonium salt is prepared by the following steps: Add organic carboxylic acid, diethylenetriamine and xylene into a flask, stir and react at 140-160°C for 2 hours, then heat to 190-210°C for 2 hours, cool to 90-110°C, slowly add benzyl chloride dropwise, keep warm and react for 3 hours, then add thiourea, stir and react for 2-3 hours. After the reaction, remove xylene by vacuum distillation to obtain thiourea alkyl imidazoline quaternary ammonium salt.

5. A sealing material resistant to NMP strong polar solvent according to claim 4, characterized in that, The usage ratio of organic carboxylic acid, diethylenetriamine, benzyl chloride and thiourea is 0.1 mol: 0.12 mol: 0.1 mol: 7.6-8.8 g.

6. A sealing material resistant to NMP strong polar solvent according to claim 4, characterized in that, The organic carboxylic acid is a saturated carboxylic acid and / or an unsaturated carboxylic acid, the saturated carboxylic acid is at least one of capric acid, valeric acid, palmitic acid and stearic acid, and the unsaturated carboxylic acid is at least one of oleic acid, linoleic acid and arachidonic acid.

7. A sealing material resistant to NMP strong polar solvent according to claim 1, characterized in that, The surfactant is prepared by the following steps: Add boric acid, diethanolamine and toluene to a flask, heat to reflux and react for 8-10 hours, then remove toluene by distillation under reduced pressure, add anhydrous ethanol, long-chain halogenated olefins and anhydrous sodium carbonate to the distillation product, stir evenly, stir at 70-75°C and react for 8-10 hours, then remove anhydrous ethanol by rotary evaporation to obtain a surfactant.

8. A sealing material resistant to NMP strong polar solvent according to claim 7, characterized in that, The usage ratio of boric acid, diethanolamine, toluene, anhydrous ethanol, long-chain halogenated olefin and anhydrous sodium carbonate is 0.05 mol: 0.1-0.12 mol: 100-150 mL: 100-200 mL: 0.1 mol: 10.5-11.0 g.

9. A sealing material resistant to NMP strong polar solvent according to claim 7, characterized in that, The long-chain halogenated olefin is 9-bromo-1-nonene and / or 11-bromo-1-undecene.

10. A sealing material resistant to NMP strong polar solvent according to claim 1, characterized in that, The preparation method of the sealing material resistant to NMP strong polar solvent comprises the following steps: According to the raw material ratio, EPDM rubber is added to an internal mixer and plasticized for 3-5 minutes. Modified montmorillonite is added and plasticized at 100-110°C for 8-10 minutes. Then, white carbon black, stearic acid, surfactant, zinc oxide, triallyl isocyanurate and paraffin oil are added in sequence and plasticized at 100-110°C for 8-10 minutes. Then, plasticized at 115-125°C for 8-10 minutes, cooled to 50-60°C, diisopropyl peroxide is added, and vulcanized at 130-150°C and 10-15MPa for 60-75 minutes to obtain a sealing material resistant to the strong polar solvent NMP.

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