A modified fluororubber sealing ring and its preparation method

Abstract

This application relates to the technical field of sealing ring materials, and specifically discloses a modified fluororubber sealing ring and a preparation method thereof. The sealing ring comprises raw material fluororubber, aramid pulp, resin composition, dicumyl peroxide, reinforcing agent and stabilizer. The preparation method of the sealing ring includes: initially mixing the aramid pulp and the reinforcing agent and then jointly putting them into a mixer with the fluororubber for plasticizing; putting the resin composition into the mixer, discharging the mixture after mixing and then thinning and cooling it on an open mill; putting the cooled rubber material into the open mill, adding dicumyl peroxide and the stabilizer, mixing and then cooling; cutting the material obtained by mixing on the open mill and then putting it into a vulcanizer for vulcanization and shaping to obtain the product. The raw materials selected in this application are simple, safe, environmentally friendly, and the preparation process is green and environmentally friendly. The obtained modified fluororubber sealing ring further improves the mechanical strength and hardness while maintaining the excellent performance of the traditional fluororubber sealing ring, and reduces the production cost.

Description

Technical Field

[0001] The present application relates to the technical field of sealing ring materials, and more specifically, to a modified fluororubber sealing ring and a preparation method thereof. Background Art

[0002] Fluororubber refers to a high molecular polymer containing fluorine atoms on the main chain and side chain carbon atoms. The rubber molecule contains fluorine atoms. The C-F property formed by fluorine atoms and carbon atoms is very high. At the same time, fluorine atoms have a great adsorption effect, which enhances the performance of the C-C bond in the fluorocarbon molecular chain, and it increases with the improvement of its fluorination degree. Fluorine atoms can shield the C-C main chain well, thus ensuring the chemical inertness of the C-C bond. Therefore, fluororubber has excellent heat resistance, oxidation resistance, oil resistance, corrosion resistance and atmospheric aging resistance, and is widely used as a sealing material in the fields of national defense, military industry, aerospace, aviation, automobiles, petroleum and household appliances, etc.

[0003] The most prominent feature of the fluororubber sealing ring is its excellent high temperature resistance, with a maximum temperature resistance of 300°C and it can work for a long time in the working condition environment of 200 - 260°C. The fluororubber sealing ring also has excellent chemical stability, and its stability to organic liquids such as fuel oil, hydraulic oil, lubricating oil, various dilute and concentrated nitric acids, sulfuric acids, hydrochloric acids and strong oxidants such as high-concentration hydrogen peroxide is better than that of other rubbers. In addition, the fluororubber sealing ring also has relatively excellent aging resistance, ozone resistance and mechanical properties. With the continuous improvement of China's industrial manufacturing level, the consumption of fluororubber sealing rings has also increased rapidly. Although the fluororubber sealing ring has excellent use performance, it still has the defect of poor processing performance.

[0004] In related technologies, the conventional fluororubber sealing ring is prepared by heating and soft-cutting fluororubber, adding the solvent acetone to dilute the fluororubber block and stirring it into a rubber paste, and then coating the liquid fluororubber paste on the cloth. The above preparation method of the fluororubber sealing ring has the problems that the fluororubber rubber paste is prone to gelation, resulting in waste of raw materials and increased production costs; polluting gases are easily dissipated during the coating process, causing environmental pollution and harm to the human body, which does not conform to the development trend of green environmental protection; and the adhesion between the fluororubber and the cloth is poor, resulting in poor product strength and restricting its application fields. Based on the above statements, the present application provides a modified fluororubber sealing ring and a preparation method thereof. Summary of the Invention

[0005] In order to solve the problems of high processing cost, poor product strength and easy pollution during processing of the current fluororubber sealing ring, the present application provides a modified fluororubber sealing ring and a preparation method thereof.

[0006] In the first aspect, the present application provides a modified fluororubber sealing ring, adopting the following technical solution:

[0007] A modified fluororubber sealing ring, comprising the following raw materials in parts by weight: 60 - 80 parts of fluororubber, 30 - 40 parts of aramid pulp, and 3 - 8 parts of resin composition.

[0008] Preferably, the modified fluororubber sealing ring comprises the following raw materials in parts by weight: 65 - 75 parts of fluororubber, 32 - 38 parts of aramid pulp, and 4 - 7 parts of resin composition.

[0009] Preferably, the modified fluororubber sealing ring comprises the following raw materials in parts by weight: 70 parts of fluororubber, 35 parts of aramid pulp, and 5 parts of resin composition.

[0010] By adopting the above technical scheme, this application selects fluororubber, aramid pulp, and resin composition as raw materials. The raw material selection is simple, safe, environmentally friendly, and the preparation process is green and environmentally friendly; by controlling the formula ratio and using aramid pulp to reinforce fluororubber, the obtained modified fluororubber sealing ring further improves the mechanical strength and hardness while maintaining the excellent performance of the traditional fluororubber sealing ring, and reduces the production cost.

[0011] Preferably, the fluororubber includes perfluoroether rubber and tetrapropylfluororubber; the mass ratio of the perfluoroether rubber to the tetrapropylfluororubber is 2 - 3:1.

[0012] By adopting the above technical scheme, using the compound of perfluoroether rubber and tetrapropylfluororubber as the main material reduces the regularity of the main material, improves the compatibility of the main material with other components, and by controlling the dosage ratio of the two, the mechanical strength of the modified fluororubber sealing ring can be further improved and the compression set rate can be reduced.

[0013] Preferably, the aramid pulp comprises the following raw materials in weight percentage: 20 - 40% of aramid short fibers, 2 - 4% of lithium diisopropylamide, 5 - 8% of liquid paraffin, 1 - 3% of vinyltrimethoxysilane, 1 - 3% of methyltriethylammonium chloride, and the balance is ethyl acetate.

[0014] Preferably, the aramid pulp is prepared by the following method:

[0015] Perform the first grinding treatment on the aramid short fibers with liquid paraffin, and then perform the second grinding treatment with lithium diisopropylamide to obtain a grinding mixture;

[0016] After stirring and dispersing the grinding mixture with ethyl acetate, add vinyltrimethoxysilane and methyltriethylammonium chloride for ultrasonic treatment, and after ultrasonic treatment, age, beat, filter, and dry to obtain the required aramid pulp.

[0017] Preferably, the pressure for the two grindings is 13 - 15 kPa, the grinding speed is 42 - 48 r / min, the first grinding time is 10 - 20 min, and the second grinding time is 8 - 15 min.

[0018] Preferably, the ultrasonic power is 70 - 80 W, the ultrasonic time is 8 - 10 min, and the aging time is 1 - 5 h.

[0019] Preferably, the average length of the aramid short fibers is 2 - 3 mm, and the average length of the aramid pulp is 0.15 - 0.2 mm.

[0020] By adopting the above technical solutions, first, the aramid short fibers are pretreated with liquid paraffin, and then lithiated diisopropylamine is added for etching modification, which can effectively destroy the highly crystalline surface of the aramid short fibers, improve the surface roughness while avoiding damaging the deep - seated main structure of the aramid short fibers; after the grinding mixture is stirred and dispersed with ethyl acetate, vinyltrimethoxysilane and methyltriethylammonium chloride are added for treatment, which can further improve the surface roughness of the aramid short fibers, increase their surface free energy, and the obtained aramid pulp has a large effective contact area and strong interfacial bonding ability, and can be filled in a large amount and uniformly dispersed in the formulation system, thus achieving a significant strengthening effect.

[0021] Preferably, the resin composition includes dicyclopentadiene phenol - type epoxy resin and novolac epoxy resin, and the mass ratio of the dicyclopentadiene phenol - type epoxy resin to the novolac epoxy resin is 0.3 - 0.5:1.

[0022] Preferably, the epoxy equivalent of the dicyclopentadiene phenol - type epoxy resin is 270 - 290 g / eq, and the epoxy equivalent of the novolac epoxy resin is 172 - 179 g / eq.

[0023] By adopting the above technical solutions, using a blend of dicyclopentadiene phenol - type epoxy resin and novolac epoxy resin as the resin composition can effectively improve the compatibility and bonding strength of each component in the formulation. By controlling the epoxy equivalent of the selected resin composition, the mechanical strength and cross - linking density of the fluororubber seal ring can be further improved.

[0024] Preferably, the raw materials further include 0.1 - 0.3 parts of dicumyl peroxide, 1 - 2 parts of reinforcing agent, and 4 - 8 parts of stabilizer.

[0025] Preferably, the raw materials further include 0.2 parts of dicumyl peroxide, 1.5 parts of reinforcing agent, and 6 parts of stabilizer.

[0026] Preferably, the reinforcing agent is nano - graphene; the nano - graphene includes nano - graphene with a particle size of 1 - 30 nm and nano - graphene with a particle size of 400 - 500 nm; the mass ratio of the nano - graphene with a particle size of 1 - 30 nm to the nano - graphene with a particle size of 400 - 500 nm is 3:1.

[0027] By adopting the above technical solution, the addition of a small amount of nano-graphene can form active adsorption centers, enhance the bonding force between fluororubber, aramid pulp and other components, and thus greatly improve the mechanical properties and sealing performance of the sealing ring, effectively prevent corrosive media from passing through, and further improve the heat resistance, aging resistance and chemical corrosion resistance of the sealing ring; by controlling the selected particle size of nano-graphene, better doping of nano-graphene in aramid pulp can be achieved, improving the dispersion uniformity of aramid pulp itself, avoiding entanglement and agglomeration of aramid pulp, thereby improving the processability of the sealing ring, further enhancing the mechanical strength of the obtained sealing ring and reducing the processing cost.

[0028] Preferably, the stabilizer comprises zinc oxide, zinc stearate and polyethylene wax in a mass ratio of 0.3-0.5:0.2-0.4:1.

[0029] By adopting the above technical solution, controlling the mass ratio within the above range, and using the compound of zinc oxide, zinc stearate and polyethylene wax as the stabilizer, the three work synergistically to significantly improve the fluidity and processability of the rubber compound, avoid the gelling phenomenon, and the obtained fluororubber sealing ring has high production efficiency, low production cost, high product qualification rate and good product quality.

[0030] In a second aspect, the present application provides a preparation method of a modified fluororubber sealing ring, adopting the following technical solution: A preparation method of a modified fluororubber sealing ring includes the following preparation steps:

[0031] S1. Weigh raw materials of fluororubber, aramid pulp, resin composition, dicumyl peroxide, reinforcing agent and stabilizer for standby according to parts by weight;

[0032] S2. Initially mix the aramid pulp and the reinforcing agent, and then jointly put them into a mixer with the fluororubber for plasticizing;

[0033] S3. Put the resin composition into the mixer in step S2, mix and discharge the rubber to a two-roll mill for thin passing and cooling;

[0034] S4. Put the cooled rubber compound in step S3 into a two-roll mill, add dicumyl peroxide and the stabilizer, open mill and then cool;

[0035] S5. Cut the material obtained by open milling in step S4 and put it into a vulcanizer for vulcanization and shaping to obtain the required modified fluororubber sealing ring.

[0036] By adopting the above technical solution, in the present application, aramid pulp and a reinforcing agent are first premixed and then kneaded with fluororubber, and then a resin composition is added for kneading, which can ensure that each component is fully mixed and evenly dispersed. By adding dicumyl peroxide and a stabilizer for open milling together, the obtained rubber compound has good fluidity, good processing performance, and high vulcanization rate. The modified fluororubber sealing ring product obtained by vulcanization molding has stable performance; the preparation method of the present application is simple in operation, high in production efficiency, low in production and processing cost, and the preparation process will not cause great pollution to the environment. The obtained modified fluororubber sealing ring has excellent sealing performance, high temperature resistance, high pressure resistance, and chemical corrosion resistance, with high hardness and low compression set rate, and has good applicability and long service life in actual use.

[0037] In summary, the present application has the following beneficial effects:

[0038] In the present application, fluororubber, aramid pulp, and a resin composition are selected as raw materials. The selection of raw materials is simple, safe, and environmentally friendly. By controlling the formulation ratio, a modified fluororubber sealing ring is obtained by reinforcing fluororubber with aramid pulp. By adding a small amount of nano-graphene to the formulation, active adsorption centers can be formed, enhancing the bonding force between fluororubber, aramid pulp, and other components, thereby greatly improving the mechanical properties and sealing performance of the sealing ring, effectively preventing corrosive media from passing through, and further improving the heat resistance, aging resistance, and chemical corrosion resistance of the sealing ring; by controlling the selected particle size of nano-graphene, better doping of nano-graphene in aramid pulp can be achieved, improving the dispersion uniformity of aramid pulp itself, avoiding entanglement of aramid pulp into clusters, thereby improving the processability of the sealing ring, further enhancing the mechanical strength of the prepared sealing ring, and reducing the processing cost.

[0039] By adopting the above technical solution, in the present application, aramid pulp and a reinforcing agent are first premixed and then kneaded with fluororubber, and then a resin composition is added for kneading, which can ensure that each component is fully mixed and evenly dispersed. By adding dicumyl peroxide and a stabilizer for open milling together, the obtained rubber compound has good fluidity, good processing performance, and high vulcanization rate. The modified fluororubber sealing ring product obtained by vulcanization molding has stable performance; the preparation method of the present application is simple in operation, high in production efficiency, low in production and processing cost, and the preparation process will not cause great pollution to the environment. The obtained modified fluororubber sealing ring has excellent sealing performance, high temperature resistance, high pressure resistance, and chemical corrosion resistance, with high hardness and low compression set rate, and has good applicability and long service life in actual use. Specific Embodiments

[0040] The following further elaborates on the present application with reference to examples.

[0041] Preparation Examples 1 - 3 provide aramid pulp and its preparation method.

[0042] Preparation Example 1

[0043] The aramid pulp includes raw materials in the following weight percentages: 20% of aramid short fibers, 2% of lithium diisopropylamide, 5% of liquid paraffin, 1% of vinyltrimethoxysilane, 1% of methyltriethylammonium chloride, and the balance is ethyl acetate.

[0044] The aramid pulp is prepared by the following method:

[0045] The aramid short fibers with an average length of 2 mm are added with liquid paraffin for the first grinding treatment, and then lithium diisopropylamide is added for the second grinding treatment. The pressure for both grindings is controlled at 13 kPa, the grinding rotation speed is 42 r / min, the first grinding time is 20 min, and the second grinding time is 15 min. After grinding, a grinding mixture is obtained.

[0046] After the grinding mixture is stirred and dispersed with ethyl acetate, vinyltrimethoxysilane and methyltriethylammonium chloride are added for ultrasonic treatment. The ultrasonic power is controlled at 70 W, the ultrasonic time is 10 min, and after ultrasonic treatment, it is aged for 5 h, beaten, filtered, and dried to obtain aramid pulp with an average length of 0.15 mm.

[0047] Preparation Example 2

[0048] The aramid pulp includes raw materials in the following weight percentages: 30% of aramid short fibers, 3% of lithium diisopropylamide, 6.5% of liquid paraffin, 2% of vinyltrimethoxysilane, 2% of methyltriethylammonium chloride, and the balance is ethyl acetate.

[0049] The aramid pulp is prepared by the following method:

[0050] The aramid short fibers with an average length of 2.5 mm are added with liquid paraffin for the first grinding treatment, and then lithium diisopropylamide is added for the second grinding treatment. The pressure for both grindings is controlled at 14 kPa, the grinding rotation speed is 45 r / min, the first grinding time is 15 min, and the second grinding time is 12 min. After grinding, a grinding mixture is obtained.

[0051] After the grinding mixture is stirred and dispersed with ethyl acetate, vinyltrimethoxysilane and methyltriethylammonium chloride are added for ultrasonic treatment. The ultrasonic power is controlled at 75 W, the ultrasonic time is 9 min, and after ultrasonic treatment, it is aged for 3 h, beaten, filtered, and dried to obtain aramid pulp with an average length of 0.18 mm.

[0052] Preparation Example 3

[0053] The aramid pulp includes raw materials in the following weight percentages: 40% of aramid short fibers, 4% of lithium diisopropylamide, 8% of liquid paraffin, 3% of vinyltrimethoxysilane, 3% of methyltriethylammonium chloride, and the balance is ethyl acetate.

[0054] The aramid pulp is prepared by the following method:

[0055] The aramid short fibers with an average length of 3 mm are ground for the first time with liquid paraffin, and then ground for the second time with lithium diisopropylamide. The pressure for the two grinding processes is controlled at 15 kPa, the grinding speed is 48 r / min, the first grinding time is 10 min, and the second grinding time is 8 min. After grinding, a grinding mixture is obtained.

[0056] After the grinding mixture is stirred and dispersed with ethyl acetate, vinyltrimethoxysilane and methyltriethylammonium chloride are added for ultrasonic treatment. The ultrasonic power is controlled at 80 W, the ultrasonic time is 8 min, and after ultrasonic treatment, it is aged for 1 h, then beaten, filtered, and dried to obtain aramid pulp with an average length of 0.2 mm.

[0057] Comparative Preparation Example 1

[0058] The aramid pulp comprises the following raw materials by weight percentage: 20% of aramid short fibers, 2% of lithium diisopropylamide, 5% of liquid paraffin, 1% of vinyltrimethoxysilane, 1% of methyltriethylammonium chloride, and the balance is ethyl acetate.

[0059] The aramid pulp is prepared by the following method:

[0060] The aramid short fibers with an average length of 2 mm are ground for the first time with lithium diisopropylamide, and then ground for the second time with liquid paraffin. The pressure for the two grinding processes is controlled at 13 kPa, the grinding speed is 42 r / min, the first grinding time is 20 min, and the second grinding time is 15 min. After grinding, a grinding mixture is obtained.

[0061] After the grinding mixture is stirred and dispersed with ethyl acetate, vinyltrimethoxysilane and methyltriethylammonium chloride are added for ultrasonic treatment. The ultrasonic power is controlled at 70 W, the ultrasonic time is 10 min, and after ultrasonic treatment, it is aged for 5 h, then beaten, filtered, and dried to obtain aramid pulp with an average length of 0.15 mm.

[0062] Comparative Preparation Example 2

[0063] The aramid pulp comprises the following raw materials by weight percentage: 20% of aramid short fibers, 2% of lithium diisopropylamide, 5% of liquid paraffin, 2% of vinyltrimethoxysilane, and the balance is ethyl acetate.

[0064] The aramid pulp is prepared by the following method:

[0065] The aramid short fibers with an average length of 2 mm are ground for the first time with lithium diisopropylamide, and then ground for the second time with liquid paraffin. The pressure for both grindings is controlled at 13 kPa, the grinding rotation speed is 42 r / min, the first grinding time is 20 min, and the second grinding time is 15 min. After grinding, a ground mixture is obtained.

[0066] After the ground mixture is stirred and dispersed with ethyl acetate, vinyltrimethoxysilane is added for ultrasonic treatment. The ultrasonic power is controlled at 70 W, the ultrasonic time is 10 min, and after ultrasonic treatment, it is aged for 5 h, then beaten, filtered, and dried to obtain aramid pulp with an average length of 0.15 mm.

[0067] Examples 1-13 provide a modified fluororubber sealing ring and its preparation method. Hereinafter, Example 1 will be taken as an example for illustration.

[0068] Example 1

[0069] A modified fluororubber sealing ring, comprising raw materials: 60 Kg of fluororubber, 30 Kg of aramid pulp, 3 Kg of resin composition, 0.1 Kg of dicumyl peroxide, 1 Kg of reinforcing agent, and 4 Kg of stabilizer;

[0070] Among them, the fluororubber includes perfluoroether rubber and tetrapropyl fluororubber, and the mass ratio of perfluoroether rubber to tetrapropyl fluororubber is 2:1; the aramid pulp is prepared from Preparation Example 1;

[0071] The resin composition includes dicyclopentadiene phenol type epoxy resin and phenolic epoxy resin, and the mass ratio of dicyclopentadiene phenol type epoxy resin to phenolic epoxy resin is 0.3:1, and the epoxy equivalent of dicyclopentadiene phenol type epoxy resin is 270-290 g / eq, and the epoxy equivalent of phenolic epoxy resin is 172-179 g / eq;

[0072] The reinforcing agent includes nano-graphene with a particle size of 1-30 nm and nano-graphene with a particle size of 400-500 nm, and the mass ratio of nano-graphene with a particle size of 1-30 nm to nano-graphene with a particle size of 400-500 nm is 3:1;

[0073] The stabilizer includes zinc oxide, zinc stearate, and polyethylene wax with a mass ratio of 0.3:0.2:1.

[0074] A preparation method of a modified fluororubber sealing ring, comprising the following preparation steps:

[0075] S1. By weight, weigh the raw materials fluororubber, aramid pulp, resin composition, dicumyl peroxide, reinforcing agent, and stabilizer for standby;

[0076] S2. First, aramid pulp and the reinforcing agent are magnetically stirred at a rotation speed of 450 r / min for 25 min for preliminary mixing, and then put into an internal mixer together with fluororubber for plasticizing for 4 min. The plasticizing temperature is 90 °C, and the rotor speed is 45 r / min;

[0077] S3. Put the resin composition into the internal mixer in step S2, knead for 20 min, control the temperature during the kneading process at 110 °C, turn the rubber 4 times during the kneading process, and after completion, discharge the rubber to a two-roll mill for thin-pass cooling to 50 °C;

[0078] S4. Preheat the two-roll mill to 75 °C, put the cooled rubber compound in step S3 into the two-roll mill, add dicumyl peroxide and the stabilizer, and open mill for 14 min under the condition of a rotation speed of 30 r / min. After the open milling is completed, cool to room temperature;

[0079] S5. Cut the material obtained by open milling in step S4 and put it into a vulcanizer. Control the mold temperature at 155 °C and the vulcanization time at 18 min. After vulcanization and shaping through the vulcanizer mold, the required modified fluororubber sealing ring is obtained.

[0080] Examples 2-5 are the same as Example 1, except that the masses of the raw materials for preparing the modified fluororubber sealing ring are different, as shown in Table 1 specifically.

[0081] Table 1: Masses of the raw materials for preparing the modified fluororubber sealing ring in Examples 1-5

[0082]

[0083] Example 6

[0084] Example 6 is the same as Example 3, except that the mass ratio of perfluoroether rubber to tetrapropyl fluororubber is 2.5:1.

[0085] Example 7

[0086] Example 7 is the same as Example 3, except that the mass ratio of perfluoroether rubber to tetrapropyl fluororubber is 3:1.

[0087] Example 8

[0088] Example 8 is the same as Example 3, except that the aramid pulp is prepared from Preparation Example 2.

[0089] Example 9

[0090] Example 9 is the same as Example 3, except that the aramid pulp is prepared from Preparation Example 3.

[0091] Example 10

[0092] Example 10 is the same as Example 3, except that the mass ratio of dicyclopentadiene phenol type epoxy resin to novolac epoxy resin is 0.4:1.

[0093] Example 11

[0094] Example 11 is the same as Example 3, except that the mass ratio of dicyclopentadiene phenol type epoxy resin to novolac epoxy resin is 0.5:1.

[0095] Example 12

[0096] Example 12 is the same as Example 3, except that the stabilizer includes zinc oxide, zinc stearate and polyethylene wax with a mass ratio of 0.4:0.3:1.

[0097] Example 13

[0098] Example 13 is the same as Example 3, except that the stabilizer includes zinc oxide, zinc stearate and polyethylene wax with a mass ratio of 0.5:0.4:1.

[0099] To verify the performance of the modified fluororubber sealing rings prepared in Examples 1-13 of the present application, the applicant set Comparative Examples 1-12 as follows:

[0100] Comparative Example 1

[0101] Comparative Example 1 is the same as Example 1, except that the fluororubber only selects perfluoroether rubber.

[0102] Comparative Example 2

[0103] Comparative Example 2 is the same as Example 1, except that the fluororubber only selects tetrapropyl fluororubber.

[0104] Comparative Example 3

[0105] Comparative Example 3 is the same as Example 1, except that the aramid pulp is prepared from Comparative Preparation Example 1.

[0106] Comparative Example 4

[0107] Comparative Example 4 is the same as Example 1, except that the aramid pulp is prepared from Comparative Preparation Example 2.

[0108] Comparative Example 5

[0109] Comparative Example 5 is the same as Example 1, except that the aramid pulp selects commercially available aramid pulp (DuPont 1F1710).

[0110] Comparative Example 6

[0111] Comparative Example 6 is the same as Example 1, except that the resin composition only selects dicyclopentadiene phenol type epoxy resin.

[0112] Comparative Example 7

[0113] Comparative Example 7 is the same as Example 1, except that the resin composition only uses phenolic epoxy resin.

[0114] Comparative Example 8

[0115] Comparative Example 8 is the same as Example 1, except that the reinforcing agent only uses nano-graphene with a particle size of 400 - 500 nm.

[0116] Comparative Example 9

[0117] Comparative Example 9 is the same as Example 1, except that the reinforcing agent only uses nano-graphene with a particle size of 1 - 30 nm.

[0118] Comparative Example 10

[0119] Comparative Example 10 is the same as Example 1, except that the stabilizer includes zinc oxide and polyethylene wax with a mass ratio of 0.3:1.

[0120] Comparative Example 11

[0121] Comparative Example 11 is the same as Example 1, except that the stabilizer includes zinc stearate and polyethylene wax with a mass ratio of 0.2:1.

[0122] Comparative Example 12

[0123] Comparative Example 12 is the same as Example 1, except that the stabilizer is polyethylene wax.

[0124] Performance Test

[0125] Referring to standards ASTM D2240 and ASTM D1414, the hardness and permanent compression set rate of the modified fluororubber seals prepared in Examples 1 - 13 and Comparative Examples 1 - 12 of this application were tested, and the results shown in Table 2 below were obtained:

[0126] Table 2: Performance Test Results of Seal Ring Samples

[0127]

[0128]

[0129] It can be seen from the data shown in Table 2 above that the modified fluororubber seals prepared in the examples of this application have good mechanical properties, high hardness, low compression set rate, good applicability, and long service life.

[0130] Comparing Comparative Example 1 with Comparative Examples 1-2 shows that: using a blend of perfluoroether rubber and tetrapropylfluororubber as the main material and controlling the mass ratio of perfluoroether rubber to tetrapropylfluororubber to be 2-3:1 can further increase the hardness of the modified fluororubber seal ring and reduce the compression set rate compared to using only perfluoroether rubber or tetrapropylfluororubber alone.

[0131] Comparing Example 1 with Comparative Example 3 shows that: during the preparation of aramid pulp, using liquid paraffin to pretreat the aramid short fibers and then subjecting them to etching modification with lithium diisopropylamide can effectively destroy the highly crystalline surface of the aramid short fibers, improve the surface roughness while avoiding damaging the deep main structure of the aramid short fibers, thereby increasing the hardness and heat resistance of the modified fluororubber seal ring and reducing the compression set rate.

[0132] Comparing Example 1 with Comparative Example 4 shows that: treating with vinyltrimethoxysilane and methyltriethylammonium chloride can further improve the surface roughness of the aramid short fibers, increase their surface free energy, and further increase the hardness and heat resistance of the modified fluororubber seal ring and reduce the compression set rate.

[0133] Comparing Example 1 with Comparative Example 5 shows that: the aramid pulp prepared in this application has a high addition amount, can be effectively filled and uniformly dispersed in the formulation system, thereby increasing the hardness and heat resistance of the modified fluororubber seal ring, reducing the compression set rate, and reducing the production and processing costs; the applicant learned through experiments that the maximum addition amount of commercially available aramid pulp in the formulation system of this application can reach 18 Kg. Continuing to add will cause difficulties in feeding during mixing, poor processability, and the comprehensive performance of the finally obtained modified fluororubber seal ring will instead decline.

[0134] Comparing Example 1 with Comparative Examples 6-7 shows that: the resin composition is selected as a blend of dicyclopentadiene phenol type epoxy resin and phenolic epoxy resin, and controlling the mass ratio of dicyclopentadiene phenol type epoxy resin to phenolic epoxy resin to be 0.3-0.5:1 can further increase the hardness of the modified fluororubber seal ring and reduce the compression set rate compared to using only dicyclopentadiene phenol type epoxy resin or phenolic epoxy resin alone.

[0135] Comparing Example 1 with Comparative Examples 8-9 shows that: by controlling the selected particle size of nano-graphene, better doping of nano-graphene in the aramid pulp can be achieved, improving the dispersion uniformity of the aramid pulp itself and avoiding the aramid pulp from entangling into clusters, thereby increasing the hardness of the modified fluororubber seal ring and reducing the compression set rate.

[0136] Comparing Example 1 with Comparative Examples 10-12 shows that: using a blend of zinc oxide, zinc stearate, and polyethylene wax as stabilizers, the three can play a synergistic effect, further increasing the hardness of the modified fluororubber seal ring and reducing the compression set rate.

[0137] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A modified fluororubber sealing ring, characterized in that, It comprises the following raw materials in parts by weight: 60 - 80 parts of fluororubber, 30 - 40 parts of aramid pulp, 3 - 8 parts of resin composition, 0.1 - 0.3 part of dicumyl peroxide, 1 - 2 parts of reinforcing agent, and 4 - 8 parts of stabilizer; The fluororubber includes perfluoroether rubber and tetrapropyl fluororubber; the mass ratio of the perfluoroether rubber to the tetrapropyl fluororubber is 2 - 3:1; the aramid pulp is prepared by the following method: Short - cut aramid fibers are added with liquid paraffin for the first grinding treatment, and then added with lithium diisopropylamide for the second grinding treatment to obtain a grinding mixture; The grinding mixture is added with ethyl acetate and stirred for dispersion, then added with vinyltrimethoxysilane and methyltriethylammonium chloride for ultrasonic treatment. After ultrasonic treatment, it is aged, beaten into pulp, filtered by suction, and dried to obtain the required aramid pulp; The resin composition includes dicyclopentadiene phenol - type epoxy resin and phenolic epoxy resin, and the mass ratio of the dicyclopentadiene phenol - type epoxy resin to the phenolic epoxy resin is 0.3 - 0.5:1; The reinforcing agent is nano - graphene; the nano - graphene includes nano - graphene with a particle size of 1 - 30 nm and nano - graphene with a particle size of 400 - 500 nm; the mass ratio of the nano - graphene with a particle size of 1 - 30 nm to the nano - graphene with a particle size of 400 - 500 nm is 3:1; The stabilizer includes zinc oxide, zinc stearate, and polyethylene wax with a mass ratio of 0.3 - 0.5:0.2 - 0.4:

1.

2. The modified fluororubber sealing ring according to claim 1, characterized in that, The aramid pulp includes the following raw materials in weight percentages: 20 - 40% of short - cut aramid fibers, 2 - 4% of lithium diisopropylamide, 5 - 8% of liquid paraffin, 1 - 3% of vinyltrimethoxysilane, 1 - 3% of methyltriethylammonium chloride, and the balance is ethyl acetate.

3. The modified fluororubber sealing ring according to claim 1, characterized in that, The epoxy equivalent of the dicyclopentadiene phenol - type epoxy resin is 270 - 290 g / eq, and the epoxy equivalent of the phenolic epoxy resin is 172 - 179 g / eq.

4. A preparation method of the modified fluororubber sealing ring according to any one of claims 1-3, characterized in that, It includes the following preparation steps: S1. Weigh the raw materials of fluororubber, aramid pulp, resin composition, dicumyl peroxide, reinforcing agent, and stabilizer in parts by weight for standby; S2. The aramid pulp and the reinforcing agent are initially mixed and then jointly put into a mixer for plasticizing with the fluororubber; S3. The resin composition is put into the mixer in step S2, and after mixing, the discharged rubber is passed through a two - roll mill for thin - passing and cooling; S4. The cooled rubber compound in step S3 is put into a two - roll mill, added with dicumyl peroxide and stabilizer, and then cooled after mixing; S5. The material obtained by mixing in step S4 is cut and then put into a vulcanizer for vulcanization and shaping to obtain the required modified fluororubber sealing ring.

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