Weather-resistant rubber elastomer for sealing element and preparation method of weather-resistant rubber elastomer

Abstract

The invention discloses a weather-resistant rubber elastomer for a sealing element and a preparation method of the weather-resistant rubber elastomer, and belongs to the technical field of rubber elastomers, the weather-resistant rubber elastomer is obtained by internally mixing a composite flame retardant, ethylene propylene diene monomer and other raw materials through an internal mixer, and ammonium polyphosphate in the composite flame retardant can generate polyphosphoric acid when being heated and decomposed; polyphosphoric acid promotes carbonization of the rubber elastomer to form a carbon layer, generation of combustible volatile matter is reduced, meanwhile, conjugated double bonds of polyaniline are broken due to heating and cross-linked again, a stable structure reinforcing carbon layer can be formed, a large amount of water and ammonia gas can be generated when ammonium polyphosphate is decomposed, an expanded carbon layer is formed in the weather-proof rubber elastomer, and the weather-proof performance of the weather-proof rubber elastomer is improved. According to the present invention, the volume of the weather-resistant rubber elastomer is expanded so as to block the leakage of the gas inside the cell, and the good sealing property is provided during the combustion, and in addition, after the montmorillonite is intercalated by the cetyltrimethylammonium bromide and the gamma-AlOOH, the interlayer spacing is expanded, and the continuous and compact barrier can be formed at the high temperature;

Description

Technical Field

[0001] The present invention belongs to the technical field of rubber elastomers, and in particular relates to a weather-resistant rubber elastomer for sealing components and a preparation method thereof. Background Art

[0002] Seals are key components in industrial equipment, transportation, and infrastructure that isolate media from penetration and mechanical impact. Their performance directly determines the reliability of these devices in extreme environments. As global industry expands into harsh environments like high latitudes, oceans, and deserts, sealing materials must withstand increasingly complex service conditions. These include hot and humid regions and areas with high UV radiation intensity. They also need to resist acid rain corrosion and mechanical dynamic fatigue. Traditional rubber materials exhibit significant shortcomings in these extreme environments, driving the technological evolution of weather-resistant elastomers.

[0003] Chinese invention patent application CN106916384B discloses a high-temperature and aging-resistant EPDM rubber seal and its preparation method. The EPDM rubber seal comprises the following components by weight: 80-90 parts EPDM rubber, 10-20 parts saturated styrene thermoplastic elastomer, 11-17 parts activator, 3.4-5.8 parts vulcanizer, 2-4 parts accelerator, 55-70 parts filler and reinforcing agent, and 5-15 parts plasticizer. By optimizing the selection and content of the components, combined with process improvements and synergistic effects, a high-temperature and aging-resistant vulcanized rubber product is produced. It is used for sealing between the cylinder head and cylinder body of high-temperature vulcanization steam cylinders. A mixing process is used to ensure uniform dispersion of the ingredients, eliminate internal stress, and guarantee the quality of the rubber mix.

[0004] In the lithium-ion battery industry, the selection of seals requires consideration not only for their weather resistance but also for their flame retardancy. A short circuit caused by a damaged separator within a lithium-ion battery cell can cause a sudden local temperature rise. Thermal runaway can release flammable gases such as hydrogen, methane, and carbon monoxide, which can easily cause a fire. Therefore, enhancing the barrier to flammable gases is a key research focus for flame-retardant lithium-ion battery seals. Summary of the Invention

[0005] The purpose of the present invention is to provide a weather-resistant rubber elastomer for seals and a preparation method thereof. The invention is obtained by modifying a montmorillonite composite, polymerizing it with aniline, adsorbing it on the surface of ammonium polyphosphate, and then mixing it with other raw materials, thereby enhancing the flame retardant properties and isolating gas diffusion.

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

[0007] A method for preparing a weather-resistant rubber elastomer for a seal comprises the following steps:

[0008] Step 1: sodium montmorillonite is modified by hexadecyltrimethylammonium bromide to obtain modified montmorillonite, and γ-AlOOH is intercalated into the modified montmorillonite by a solvent thermal method using aluminum chloride as an aluminum source to obtain a montmorillonite composite.

[0009] Step 2: Chemically grafting an amino-containing silane coupling agent onto the surface of the montmorillonite composite to obtain amination-modified montmorillonite composite powder; utilizing electrostatic adsorption to enrich the amination-modified montmorillonite composite powder and aniline on the surface of ammonium polyphosphate; polymerizing under the action of an initiator to obtain a composite flame retardant.

[0010] Step 3: Put EPDM rubber, styrene-butadiene rubber, composite flame retardant, nano zinc oxide, stearic acid, accelerator TMTD, fumed silica, carbon nanotubes and sulfur into an internal mixer for internal mixing, demolding, and obtaining a weather-resistant rubber elastomer for sealing parts.

[0011] Furthermore, the montmorillonite composite is prepared by the following steps:

[0012] Choline chloride and urea are added to a reactor, stirred at 120-130° C. and 300-500 r / min, cooled to room temperature, and a 60 vol% ethanol aqueous solution, aluminum chloride hexahydrate, and modified montmorillonite are added. The mixture is reacted at 160-165° C. and 300-500 r / min for 5-6 hours, cooled to room temperature, filtered, washed, and dried to obtain a montmorillonite composite.

[0013] Furthermore, the usage ratio of choline chloride, urea, ethanol aqueous solution, aluminum chloride hexahydrate and modified montmorillonite is 7-12 g: 6-10 g: 600-800 mL: 12-20 g: 15-30 g.

[0014] Furthermore, the preparation process of modified montmorillonite is as follows:

[0015] Sodium montmorillonite and deionized water are added to a reactor, stirred at 80-90°C and 500-800 r / min for 30-40 min, hexadecyltrimethylammonium bromide and deionized water are mixed evenly and added to the reactor, and stirring is continued for 3-4 h. The mixture is cooled to room temperature, filtered, washed, dried, and ground to obtain modified montmorillonite.

[0016] Furthermore, the usage ratio of sodium montmorillonite, deionized water and hexadecyltrimethylammonium bromide is 20-30 g: 340-480 mL: 10-15 mL.

[0017] Furthermore, the preparation process of the amination-modified montmorillonite composite powder is as follows:

[0018] A silane coupling agent containing amino groups and a 90 vol% ethanol aqueous solution are added to a reactor, the pH value is adjusted to 5 with dilute hydrochloric acid, and hydrolysis is carried out for 1-2 hours. The montmorillonite complex and the ethanol solution are mixed evenly and added to the reactor. The mixture is reacted at 75-80° C. and 300-400 r / min for 2-3 hours. The mixture is cooled to room temperature, filtered, washed, dried, and ground to obtain amino-montmorillonite complex micropowder.

[0019] Furthermore, the usage ratio of the amino-containing silane coupling agent, the 90 vol% ethanol aqueous solution, the montmorillonite complex and the ethanol solution is 2-3 g: 100-150 mL: 10-15 g: 200-300 mL.

[0020] Furthermore, the amino group-containing silane coupling agent is any one of KH-550 and KH-792, or a mixture of the two in any mass ratio.

[0021] Furthermore, the preparation process of the composite flame retardant is as follows:

[0022] Ammonium polyphosphate, aniline, amino montmorillonite composite powder and distilled water are added into a reactor, stirred at 500-600 r / min for 10-12 minutes, ammonium persulfate as an initiator and deionized water are mixed and then dropped into the reactor, reacted at 10-15° C. and 500-800 r / min for 10-12 hours, filtered, washed, dried and ground to obtain a composite flame retardant.

[0023] Furthermore, the usage ratio of ammonium polyphosphate, aniline, amination montmorillonite composite powder, distilled water, ammonium persulfate and deionized water is 23-25 g: 13-15 g: 10-12 g: 400-450 mL: 57-60 g: 400-450 mL.

[0024] Furthermore, the mass ratio of EPDM rubber, styrene-butadiene rubber, composite flame retardant, nano zinc oxide, stearic acid, accelerator TMTD, fumed silica, carbon nanotubes and sulfur is 50-60:70-80:15-20:2-2.5:0.5-1:1-1.5:4-6:3-5:0.1-0.3.

[0025] Beneficial effects of the present invention:

[0026] 1. The weather-resistant rubber elastomer for seals of the present invention is obtained by mixing a composite flame retardant, EPDM rubber and other raw materials through a banbury kneading process. The ammonium polyphosphate in the composite flame retardant will produce polyphosphoric acid when decomposed by heat. The polyphosphoric acid promotes the carbonization of the rubber elastomer to form a carbon layer, thereby reducing the generation of combustible volatiles. At the same time, the conjugated double bonds of polyaniline are broken by heat and re-crosslinked to form a stable structure to reinforce the carbon layer. The ammonium polyphosphate will also produce a large amount of water and ammonia when decomposed, forming an expanded carbon layer inside the weather-resistant rubber elastomer, thereby making the weather-resistant rubber elastomer The volume of the battery expands, which can prevent the leakage of gas inside the battery cell and still have good sealing during combustion. In addition, after the montmorillonite is intercalated with hexadecyltrimethylammonium bromide and γ-AlOOH, the interlayer spacing is expanded, and a continuous and dense barrier is formed at high temperature to block the diffusion of combustible gases. At the same time, γ-AlOOH decomposes into aluminum oxide and water at high temperature, further inhibiting combustion. The generated aluminum oxide forms AlPO4 with polyphosphoric acid, which enhances the fire resistance of the carbon layer and can play a role in flame retardancy and isolation of combustible gases when the battery catches fire.

[0027] 2. The montmorillonite composite of the present invention is prepared by first replacing the sodium ions between the sodium-based montmorillonite layers with the quaternary ammonium cations of hexadecyltrimethylammonium bromide through ion exchange, thereby intercalating long chains into the montmorillonite layers to increase the interlayer spacing. Then, using aluminum chloride hexahydrate as an aluminum source, γ-AlOOH is intercalated into the montmorillonite layers through a solvothermal method, further increasing the interlayer spacing. The intercalation of γ-AlOOH into the montmorillonite layers disperses stress, improves tear strength, and, together with carbon nanotubes and fumed silica, enhances the wear resistance of the rubber elastomer.

[0028] 3. In the present invention, a silane coupling agent is first chemically grafted onto a montmorillonite composite, and polymerization occurs between anilines under the initiation of ammonium persulfate. During the polymerization process, the aminomontmorillonite composite is simultaneously doped into the structure of the polyaniline. Because the phosphate group in the ammonium polyphosphate carries a negative charge, the protonated amino groups in the aniline and aminomontmorillonite composite micropowder carry a positive charge. The two are enriched on the surface of the ammonium polyphosphate through electrostatic adsorption and coat the ammonium polyphosphate to form a microcapsule structure. Polyaniline is a conductive polymer. When polyaniline serves as the coating shell of the ammonium polyphosphate, it can form a conductive path in the rubber elastomer. In addition, γ-AlOOH is uniformly dispersed in the montmorillonite and coated on the outside of the ammonium polyphosphate, further increasing the conductive properties of the polymer, so that the rubber elastomer has a certain antistatic effect as a battery core seal. DETAILED DESCRIPTION

[0029] The following will be combined with specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Example 1: This example provides a weather-resistant rubber elastomer for a seal, which is prepared by the following steps:

[0031] S1: 25 g of sodium montmorillonite and 350 mL of deionized water were added to a reactor, stirred at 85 ° C and 650 r / min for 35 min, 12.5 mL of hexadecyltrimethylammonium bromide and 45 mL of deionized water were mixed and evenly added to the reactor, and stirring was continued for 3.5 h. The quaternary ammonium cations of hexadecyltrimethylammonium bromide replaced the sodium ions between the sodium montmorillonite layers through ion exchange, and the long chains were intercalated into the montmorillonite layers to increase the interlayer spacing. The mixture was cooled to room temperature, centrifuged, washed with deionized water 4 times, vacuum dried at 85 ° C for 13 h, ground, and passed through a 500 mesh sieve to obtain modified montmorillonite.

[0032] S2: Add 9 g of choline chloride and 8 g of urea to the reactor, stir at 125 ° C and 400 r / min, cool to room temperature, add 700 mL of 60 vol% ethanol aqueous solution, 16 g of aluminum chloride hexahydrate and 22 g of modified montmorillonite, react at 162 ° C and 400 r / min for 5.5 h, intercalate γ-AlOOH into the interlayer of the modified montmorillonite, cool to room temperature, centrifuge and filter, wash the precipitate with deionized water 3 times, and dry to constant weight to obtain a montmorillonite composite.

[0033] S3: 2.5 g of silane coupling agent KH-792 and 125 mL of 90 vol% ethanol aqueous solution were added to the reactor, the pH value was adjusted to 5 with dilute hydrochloric acid, and hydrolysis was carried out for 1.5 h. 12.5 g of montmorillonite complex and 250 mL of ethanol solution were mixed evenly and added to the reactor. The mixture was reacted at 77 ° C and 350 r / min for 2.5 h. The mixture was cooled to room temperature and filtered. The precipitate was washed with deionized water 4 times, dried at 85 ° C for 7 h, ground, and passed through a 500 mesh sieve to obtain amino montmorillonite complex powder.

[0034] S4: 24 g of ammonium polyphosphate, 14 g of aniline, 11 g of amination-montmorillonite composite powder and 425 mL of distilled water were added to a reactor and stirred at 550 r / min for 11 min. 58.5 g of ammonium persulfate as an initiator and 425 mL of deionized water were mixed and dropped into the reactor. The mixture was reacted at 12°C and 650 r / min for 11 h. The amino groups in the aniline and amination-montmorillonite composite powder were protonated and positively charged, and were enriched on the surface of the ammonium polyphosphate through electrostatic adsorption with the negatively charged phosphate groups on the surface of the ammonium polyphosphate. Under the action of the initiator, the aniline was polymerized to form polyaniline. At the same time, the amination-montmorillonite composite powder participated in the polymerization to form microcapsules. The precipitate was vacuum filtered, washed with deionized water 6 times, dried at 47°C for 49 h, and ground with a ball mill to obtain a composite flame retardant.

[0035] S5: 55g of EPDM rubber and 75g of styrene-butadiene rubber were put into an internal mixer for internal mixing, and then 17.5g of composite flame retardant, 2.25g of nano zinc oxide, 0.75g of stearic acid, 1.25g of accelerator TMTD, 5g of fumed silica, and 4g of carbon nanotubes were added and internal mixing was performed again to obtain a rubber mixture, which was put into an open mixer for internal mixing. After standing for 5h, 0.2g of sulfur was added and the mixture was internal mixing again to obtain a rubber compound, which was put into a mold of a vulcanizer for vulcanization at a vulcanization temperature of 160°C and a vulcanization time of 30min. After vulcanization, the mixture was cooled to room temperature and demolded to obtain a weather-resistant rubber elastomer for seals.

[0036] Example 2: This example provides a weather-resistant rubber elastomer for a seal, which is prepared by the following steps:

[0037] S1: 20 g of sodium montmorillonite and 300 mL of deionized water were added to a reactor, stirred at 80 ° C and 500 r / min for 30 min, 10 mL of hexadecyltrimethylammonium bromide and 40 mL of deionized water were mixed and evenly added to the reactor, and stirring was continued for 3 h. The quaternary ammonium cations of hexadecyltrimethylammonium bromide replaced the sodium ions between the sodium montmorillonite layers through ion exchange, and the long chains were intercalated into the montmorillonite layers to increase the interlayer spacing. The mixture was cooled to room temperature, centrifuged, washed with deionized water 3 times, vacuum dried at 80 ° C for 12 h, ground, and passed through a 500 mesh sieve to obtain modified montmorillonite.

[0038] S2: Add 7g of choline chloride and 6g of urea to the reactor, stir at 120°C and 300r / min, cool to room temperature, add 600mL of 60vol% ethanol aqueous solution, 12g of aluminum chloride hexahydrate and 15g of modified montmorillonite, react at 160°C and 300r / min for 5h, intercalate γ-AlOOH into the interlayer of the modified montmorillonite, cool to room temperature, centrifuge and filter, wash the precipitate twice with deionized water, and dry to constant weight to obtain a montmorillonite composite.

[0039] S3: 1 g of silane coupling agent KH-550, 1 g of silane coupling agent KH-792 and 100 mL of 90 vol% ethanol aqueous solution were added to the reactor, the pH value was adjusted to 5 with dilute hydrochloric acid, and hydrolyzed for 1 hour. 10 g of montmorillonite complex and 200 mL of ethanol solution were mixed evenly and added to the reactor. The mixture was reacted at 75°C and 300 r / min for 2 hours. The mixture was cooled to room temperature and filtered. The precipitate was washed 3 times with deionized water, dried at 80°C for 6 hours, ground, and passed through a 500-mesh sieve to obtain amino montmorillonite complex powder.

[0040] S4: Add 23g of ammonium polyphosphate, 13g of aniline, 10g of amino-montmorillonite composite powder and 400mL of distilled water into a reactor, stir at 500r / min for 10min, mix 57g of ammonium persulfate as an initiator and 400mL of deionized water and drop into the reactor, react at 10°C and 500r / min for 10h, vacuum filter, wash the precipitate with deionized water 5 times, dry at 45°C for 48h, and grind with a ball mill to obtain a composite flame retardant.

[0041] S5: 50g of EPDM rubber and 70g of styrene-butadiene rubber are put into an internal mixer for internal mixing, and then 15g of composite flame retardant, 2g of nano zinc oxide, 0.5g of stearic acid, 1g of accelerator TMTD, 4g of fumed silica, and 3g of carbon nanotubes are added and internal mixing is performed again to obtain a rubber mixture, which is put into an open mixer for internal mixing. After standing for 5h, 0.1g of sulfur is added and the mixture is internal mixed again to obtain a rubber compound, which is put into a mold of a vulcanizer for vulcanization at a vulcanization temperature of 160°C and a vulcanization time of 30min. After vulcanization, it is cooled to room temperature and demolded to obtain a weather-resistant rubber elastomer for seals.

[0042] Example 3: This example provides a weather-resistant rubber elastomer for a seal, which is prepared by the following steps:

[0043] S1: 30 g of sodium montmorillonite and 400 mL of deionized water were added to a reactor, stirred at 90 ° C and 800 r / min for 40 min, 15 mL of hexadecyltrimethylammonium bromide and 50 mL of deionized water were mixed and evenly added to the reactor, and stirring was continued for 4 h. The quaternary ammonium cations of hexadecyltrimethylammonium bromide replaced the sodium ions between the sodium montmorillonite layers through ion exchange, and the long chains were intercalated into the montmorillonite layers to increase the interlayer spacing. The mixture was cooled to room temperature, centrifuged, washed with deionized water 5 times, vacuum dried at 90 ° C for 14 h, ground, and passed through a 500 mesh sieve to obtain modified montmorillonite.

[0044] S2: Add 12g of choline chloride and 10g of urea to the reactor, stir at 130°C and 500r / min, cool to room temperature, add 800mL of 60vol% ethanol aqueous solution, 20g of aluminum chloride hexahydrate and 30g of modified montmorillonite, react at 165°C and 500r / min for 6h, intercalate γ-AlOOH into the interlayer of the modified montmorillonite, cool to room temperature, centrifuge and filter, wash the precipitate with deionized water 4 times, and dry to constant weight to obtain a montmorillonite composite.

[0045] S3: 3 g of silane coupling agent KH-550 and 150 mL of 90 vol% ethanol aqueous solution were added to the reactor, the pH value was adjusted to 5 with dilute hydrochloric acid, and hydrolyzed for 2 h. 15 g of montmorillonite complex and 300 mL of ethanol solution were mixed evenly and added to the reactor. The mixture was reacted at 80 ° C and 400 r / min for 3 h. The mixture was cooled to room temperature and filtered. The precipitate was washed with deionized water 5 times, dried at 90 ° C for 8 h, ground, and passed through a 500 mesh sieve to obtain amino montmorillonite complex powder.

[0046] S4: Add 25g of ammonium polyphosphate, 15g of aniline, 12g of amino-montmorillonite composite powder and 450mL of distilled water into a reactor, stir at 600r / min for 12min, mix 60g of ammonium persulfate as an initiator and 450mL of deionized water and drop into the reactor, react at 15°C and 800r / min for 12h, vacuum filter, wash the precipitate with deionized water 8 times, dry at 50°C for 50h, and grind with a ball mill to obtain a composite flame retardant.

[0047] S5: 60g of EPDM rubber and 80g of styrene-butadiene rubber were put into an internal mixer for internal mixing, and then 20g of composite flame retardant, 2.5g of nano zinc oxide, 1g of stearic acid, 1.5g of accelerator TMTD, 6g of fumed silica, and 5g of carbon nanotubes were added and internal mixing was performed again to obtain a rubber mixture, which was put into an open mixer for internal mixing. After standing for 5h, 0.3g of sulfur was added and the mixture was internal mixing again to obtain a rubber compound, which was put into a mold of a vulcanizer for vulcanization at a vulcanization temperature of 160°C and a vulcanization time of 30min. After vulcanization, the mixture was cooled to room temperature and demolded to obtain a weather-resistant rubber elastomer for seals.

[0048] Comparative Example 1: Based on Example 1, the composite flame retardant is removed in step S5, and the remaining steps remain unchanged to prepare a weather-resistant rubber elastomer for sealing components.

[0049] Comparative Example 2: Based on Example 1, the aminated montmorillonite composite powder was removed in step S4, and the remaining steps remained unchanged to prepare a weather-resistant rubber elastomer for sealing components.

[0050] Comparative Example 3: Based on Example 1, the modified montmorillonite prepared in step S1 is used instead of the montmorillonite composite in step S3, and the other steps remain unchanged to prepare a weather-resistant rubber elastomer for sealing components.

[0051] The seals prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance tests using weather-resistant rubber elastomers:

[0052] Tensile Strength: Referring to GB / T 528-2009, seals were cut from weather-resistant rubber elastomer into dumbbell-shaped specimens measuring 75 mm × 1 mm × 4 mm. The tensile speed was 500 mm / min. To ensure the accuracy of the experimental data, five samples were selected for measurement, and the arithmetic mean of these values was used as the final experimental data.

[0053] Tear Strength: Referring to GB / T 529-2008, seals were cut from weather-resistant rubber elastomer to create rectangular specimens with a thickness of 1 mm and a tensile speed of 500 mm / min. To ensure the accuracy of the test data, five samples were selected for measurement, and the arithmetic mean of these values was used as the final test data.

[0054] Shore A hardness: With reference to GB / T 531-92, the Shore A hardness of weather-resistant rubber elastomers used in seals was tested at room temperature using an XY-1 rubber hardness tester.

[0055] Limiting Oxygen Index Test: The test was conducted using the SS-1005 high-temperature fully automatic oxygen index analyzer produced by Dongguan Songshu Testing Instrument Co., Ltd. The sample length was 126mm, width was 6.5mm, thickness was 3mm, and LOI (Limiting Oxygen Index) was 0.013mm.

[0056] Smoke density test: refer to ISO5659, use NBS plastic smoke density tester produced by Testtech (Suzhou) Testing Instrument Technology Co., Ltd. to test, the test condition is flame condition, the heat flux radiated by the sample is 25kW / m 2 The sample length is 75 mm, width is 75 mm, and thickness is 3 mm. The maximum value of smoke density during the experiment is taken.

[0057] Surface resistivity test: The test was conducted using an insulation resistance tester (model: AR907+), with the test electrode inner diameter of 50 mm, outer ring inner diameter of 54 mm, chassis electrode diameter of 100 mm, test voltage of 500 V, and sample thickness of 3 mm.

[0058] The test results are shown in the following table:

[0059] Table 1 Summary of performance tests of weather-resistant rubber elastomers for seals

[0060]

[0061]

[0062] As can be seen from Table 1, the tensile strength, tear strength and Shore A hardness of the weather-resistant rubber elastomer for seals in Examples 1 to 3 are all higher than those in Comparative Examples 1 to 3. The composite flame retardant is removed in step S5 of Comparative Example 1, and the amino-containing montmorillonite composite powder is removed in step S4 of Comparative Example 2. In step S3 of Comparative Example 3, the modified montmorillonite prepared in step S1 is used to replace the montmorillonite composite. This may be because γ-AlOOH is intercalated between the montmorillonite layers, which disperses the stress and improves the mechanical properties, thereby improving the tensile strength, tear strength and hardness of the weather-resistant rubber elastomer for seals to a certain extent.

[0063] The limiting oxygen index LOI of the weather-resistant rubber elastomer for seals in Examples 1 to 3 is higher than that in Comparative Examples 1 to 3. The maximum smoke density of the weather-resistant rubber elastomer for seals in Examples 1 to 3 is lower than that in Comparative Examples 1 to 3. The composite flame retardant is removed in step S5 of Comparative Example 1, and the amino-containing montmorillonite composite powder is removed in step S4 of Comparative Example 2. The modified montmorillonite prepared in step S1 is used to replace the montmorillonite composite in step S3 of Comparative Example 3, which shows that montmorillonite, γ-AlOOH and ammonium polyphosphate can synergistically enhance the flame retardancy of the weather-resistant rubber elastomer for seals and inhibit the generation of smoke. This may be because ammonium polyphosphate will produce polyphosphoric acid when decomposed by heat, reducing the generation of combustible volatiles, and γ-AlOOH will decompose into aluminum oxide and water at high temperature. The generated aluminum oxide forms AlPO4 with polyphosphoric acid, enhancing the fire resistance of the carbon layer and synergistically blocking the diffusion of combustible gases with montmorillonite.

[0064] The surface resistivity of the weather-resistant rubber elastomer for seals in Examples 1 to 3 is lower than that in Comparative Examples 1 to 3. The composite flame retardant is removed in step S5 of Comparative Example 1, the amino-containing montmorillonite composite powder is removed in step S4 of Comparative Example 2, and the modified montmorillonite prepared in step S1 is used to replace the montmorillonite composite in step S3 of Comparative Example 3. This shows that γ-AlOOH and polyaniline synergistically enhance the antistatic effect of the weather-resistant rubber elastomer for seals. This may be because when polyaniline is used as the coating shell of ammonium polyphosphate, it can form a conductive path in the rubber elastomer, and at the same time, γ-AlOOH can further increase its conductive properties.

[0065] It should be noted that, in this document, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0066] While the embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes, modifications, substitutions, and alterations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a weather-resistant rubber elastomer for a seal, characterized in that: The steps include: Step 1: Modifying sodium montmorillonite with hexadecyltrimethylammonium bromide to obtain modified montmorillonite, and using aluminum chloride as an aluminum source, intercalating γ-AlOOH into the modified montmorillonite by a solvothermal method to obtain a montmorillonite composite; Step 2: Chemically grafting a silane coupling agent containing an amino group onto the surface of the montmorillonite composite to obtain an amination-modified montmorillonite composite powder, utilizing electrostatic adsorption to enrich the amination-modified montmorillonite composite powder and aniline on the surface of the ammonium polyphosphate, and polymerizing under the action of an initiator to obtain a composite flame retardant; Step 3: Put EPDM rubber, styrene-butadiene rubber, composite flame retardant, nano zinc oxide, stearic acid, accelerator TMTD, fumed silica, carbon nanotubes and sulfur into an internal mixer for internal mixing, demolding, and obtaining a weather-resistant rubber elastomer for sealing parts.

2. The method for preparing a weather-resistant rubber elastic body for sealing according to claim 1, characterized in that: The montmorillonite composite in step 1 is prepared by the following steps: Add choline chloride and urea into a reactor, stir at 120-130° C. and 300-500 r / min, cool to room temperature, add 60 vol% ethanol aqueous solution, aluminum chloride hexahydrate and modified montmorillonite, react at 160-165° C. and 300-500 r / min for 5-6 hours, cool to room temperature, filter, wash and dry to obtain a montmorillonite composite.

3. The method for preparing a weather-resistant rubber elastic body for sealing according to claim 2, characterized in that: The usage ratio of the choline chloride, urea, ethanol aqueous solution, aluminum chloride hexahydrate and modified montmorillonite is 7-12g:6-10g:600-800mL:12-20g:15-30g.

4. The method for preparing a weather-resistant rubber elastic body for sealing according to claim 3, characterized in that: The preparation process of the modified montmorillonite is as follows: Add sodium montmorillonite and deionized water into a reactor, stir at 80-90°C and 500-800 r / min for 30-40 min, mix cetyltrimethylammonium bromide and deionized water evenly, add into the reactor, continue stirring for 3-4 h, cool to room temperature, filter, wash, dry, and grind to obtain modified montmorillonite; The usage ratio of the sodium montmorillonite, deionized water and hexadecyltrimethylammonium bromide is 20-30 g: 340-480 mL: 10-15 mL.

5. The method for preparing a weather-resistant rubber elastic body for sealing parts according to claim 1, characterized in that: The preparation process of the amination-modified montmorillonite composite powder in step 2 is as follows: A silane coupling agent containing amino groups and a 90 vol% ethanol aqueous solution are added to a reactor, the pH value is adjusted to 5 with dilute hydrochloric acid, and hydrolysis is carried out for 1-2 hours. The montmorillonite complex and the ethanol solution are mixed evenly and then added to the reactor. The mixture is reacted at 75-80°C and 300-400 r / min for 2-3 hours. The mixture is cooled to room temperature, filtered, washed, dried, and ground to obtain amino-montmorillonite complex powder. The usage ratio of the amino-containing silane coupling agent, 90 vol% ethanol aqueous solution, montmorillonite complex and ethanol solution is 2-3 g: 100-150 mL: 10-15 g: 200-300 mL.

6. The method for preparing a weather-resistant rubber elastic body for sealing parts according to claim 5, characterized in that: The amino-containing silane coupling agent is any one of KH-550 and KH-792, or a mixture of the two in any mass ratio.

7. The method for preparing a weather-resistant rubber elastic body for sealing parts according to claim 1, characterized in that: The preparation process of the composite flame retardant in step 2 is as follows: Ammonium polyphosphate, aniline, amino montmorillonite composite powder and distilled water are added into a reactor, stirred at 500-600 r / min for 10-12 minutes, ammonium persulfate as an initiator and deionized water are mixed and then dropped into the reactor, reacted at 10-15° C. and 500-800 r / min for 10-12 hours, filtered, washed, dried and ground to obtain a composite flame retardant.

8. The method for preparing a weather-resistant rubber elastic body for sealing parts according to claim 7, characterized in that: The usage ratio of the ammonium polyphosphate, aniline, amination montmorillonite composite micropowder, distilled water, ammonium persulfate and deionized water is 23-25g:13-15g:10-12g:400-450mL:57-60g:400-450mL.

9. The method for preparing a weather-resistant rubber elastic body for sealing parts according to claim 1, characterized in that: The mass ratio of the EPDM rubber, styrene-butadiene rubber, composite flame retardant, nano zinc oxide, stearic acid, accelerator TMTD, fumed silica, carbon nanotubes and sulfur is 50-60:70-80:15-20:2-2.5:0.5-1:1-1.5:4-6:3-5:0.1-0.

3.

10. A weather-resistant rubber elastic body for sealing parts, characterized in that: The seal is prepared by the method for preparing a weather-resistant rubber elastomer for a seal according to any one of claims 1 to 9.

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