High-strength fluororubber and preparation method thereof

Abstract

The invention relates to the field of rubber, in particular to high-strength fluororubber and a preparation method thereof. The fluororubber comprises the following components in parts by weight: 100 parts of raw fluororubber, 20-30 parts of a reinforcing agent, 10-20 parts of a filling agent, 7-16 parts of an acid acceptor, 0.1-0.5 part of a coupling agent, 0.1-1 part of a release agent, 2-5 parts of a vulcanizing agent and 1.2-2 parts of a vulcanization accelerator. The fluororubber material prepared by the invention not only has the advantages of high temperature resistance, oil resistance and corrosion resistance, but also has excellent strength and toughness, is suitable for being used as a material for sealing washers and liners of chemical equipment, can be kept stable in various chemical and solvent environments, and ensures long-term normal operation of the equipment.

Description

Technical Field

[0001] The present invention relates to the field of rubber, and particularly to a high-strength fluororubber and a preparation method thereof. Background Art

[0002] As the depth of oil and gas drilling and production gradually increases, the composition of oil and gas and the pressure conditions become more complex. Therefore, higher requirements are put forward for the rubber sealing material technology of the equipment related to oil and gas drilling, transmission, and processing. Under the working conditions of high temperature, high pressure, and strong corrosion, in addition to tolerating complex media, rubber materials are also required to have high hardness, high tensile strength, high resistance to shear deformation, explosion-proof or resistance to rapid gas pressure loss, and resistance to extrusion deformation of rubber materials.

[0003] During the transportation of oil and gas pipelines, valves are very important components. In the non-metallic sealing field of valves, non-metallic materials generally refer to plastics, rubbers, and flexible graphite, etc. Due to its excellent elasticity, obvious compensation tolerance effect, and low requirement for the machining accuracy of metal parts, rubber materials are widely designed and used in valve seals. However, the existing rubber materials have unsatisfactory sealing effects under high temperature and high pressure, especially when the pressure is above 15 MPa and the temperature is above 200 °C. This is mainly due to poor wear resistance, low hardness, low strength, large anti-extrusion deformation, easy failure under high-pressure shear, and at the same time, rubber seals are prone to rapid gas pressure release failure in high-temperature and high-pressure liquid or gas environments.

[0004] Fluororubber (FKM) refers to a synthetic polymer elastomer in which fluorine atoms are connected to the carbon atoms of the main chain or side chain. This polymer material has characteristics such as heat resistance, oil resistance, solvent resistance, corrosion resistance, and resistance to strong oxidants, and has good physical and mechanical properties. It is widely used in the fields of aerospace, aviation, weapons, automobiles, petrochemicals, etc. With the development of science and technology, higher requirements are put forward for the comprehensive performance of fluororubber. Due to the high viscosity characteristics of fluororubber itself, it is difficult to achieve uniform mixing with small-particle inorganic fillers. At present, most of the commercially available products use thermally cracked carbon black (such as N990) with large particle size for reinforcement. Although the particle size is large (average 280 nm), local agglomeration may still occur due to low structure, and the carbon black obtained by the thermal cracking method will significantly increase the hardness and stress of the vulcanizate, resulting in a decrease in the tensile strength and tear strength of the material and affecting the dynamic sealing performance. Therefore, although the existing fluororubber materials have the advantages of high temperature resistance and corrosion resistance, their low strength restricts their application in more fields. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a high-strength fluororubber and a preparation method thereof.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] In a first aspect, the present invention provides a high-strength fluororubber comprising the following components, calculated in parts by weight:

[0008] 100 parts of fluororubber raw rubber, 20-30 parts of reinforcing agent, 10-20 parts of filler, 7-16 parts of acid absorber, 0.1-0.5 parts of coupling agent, 0.1-1 parts of release agent, 2-5 parts of vulcanizing agent and 1.2-2 parts of vulcanization accelerator.

[0009] Preferably, the brand of the fluororubber raw rubber is at least one of FE2461, FE2462, FE2463, FE2601, and FE2603.

[0010] Preferably, the filler is at least one of white carbon black, calcium carbonate, barium sulfate, calcium oxide, and carbon fiber.

[0011] Preferably, the acid scavenger is a mixture of calcium hydroxide and magnesium oxide, and the mass ratio of calcium hydroxide to magnesium oxide is 3-6:5-10.

[0012] Preferably, the reinforcing agent is modified carbon black N990, and the preparation process is: first, carbon black N990 is subjected to amination treatment to obtain amino carbon black N990; then 5-hydroxymethylfurfural is subjected to amine-aldehyde condensation reaction to obtain Schiff base functionalized carbon black N990; finally, it is subjected to esterification reaction with terminal carboxyl fluororubber to obtain modified carbon black N990.

[0013] Preferably, the coupling agent is silane coupling agent A-151 or silane coupling agent A-171.

[0014] Preferably, the release agent is carnauba wax, paraffin wax or polyethylene wax.

[0015] Preferably, the vulcanizing agent is bisphenol AF; and the vulcanization accelerator is benzyltriphenylphosphine chloride.

[0016] Preferably, the preparation method of the modified N990 carbon black comprises:

[0017] S1. Carbon black N990 is placed in an ethanol aqueous solution, and then an aminosilane coupling agent is added. After sufficient dispersion, the mixture is refluxed in a water bath for 2-8 hours, and then centrifuged and dried to obtain amino carbon black N990.

[0018] S2. Dissolve 5-hydroxymethylfurfural (5-HMF) in anhydrous ethanol, add amino carbon black N990, add catalyst dropwise, heat to 70-80°C and reflux for 10-20 hours. After the reaction, remove the solvent under reduced pressure, wash with water 3-5 times and dry to obtain Schiff base functionalized carbon black N990;

[0019] S3. Dissolve the carboxyl-terminated fluororubber (CTLF) in tetrahydrofuran, and then slowly add the Schiff base-functionalized carbon black N990 with stirring. After all is added, disperse it fully until uniform. Add p-toluenesulfonic acid as a catalyst, and under the protection of nitrogen, heat it to 110 - 150 °C, keep stirring for 8 - 16 h. After the reaction is completed, cool it to room temperature, remove the solvent under reduced pressure, wash it with saturated sodium carbonate solution until neutral, then wash it with water 3 - 5 times and dry it to obtain the modified N990 carbon black.

[0020] Preferably, in the step S1, the carbon black N990 is obtained by the thermal cracking method, with a particle size range of 200 - 500 nm and an average particle size of 280 nm.

[0021] Preferably, in the step S1, the mass fraction of the aqueous solution of ethanol is 40% - 80%.

[0022] Preferably, in the step S1, the amino-silane coupling agent is at least one of KH-550, KH-602, and KH-792.

[0023] Preferably, in the step S1, the mass-to-volume ratio of the carbon black N990, the amino-silane coupling agent, and the aqueous solution of ethanol is 1 g : (0.12 - 0.38) g : (10 - 20) mL.

[0024] Preferably, in the step S2, the mass-to-volume ratio of the amino-functionalized carbon black N990, 5-hydroxymethylfurfural, and absolute ethanol is 1 g : (0.26 - 0.52) g : (10 - 20) mL.

[0025] Preferably, in the step S2, the catalyst is glacial acetic acid, and the addition amount of glacial acetic acid is 1% - 5% of the mass of 5-hydroxymethylfurfural.

[0026] Preferably, in the step S3, the number-average molecular weight of the carboxyl-terminated fluororubber is 2300 - 2520, and the carboxyl content is 2.1% - 2.5%.

[0027] Preferably, in the step S3, the mass-to-volume ratio of the Schiff base-functionalized carbon black N990, the carboxyl-terminated fluororubber, and tetrahydrofuran is 1 g : (1.8 - 3.6) g : (12 - 24) mL.

[0028] Preferably, in the step S3, the catalyst is p-toluenesulfonic acid, and the addition amount is 1.3% - 4.6% of the mass of the carboxyl-terminated fluororubber.

[0029] In the second aspect, the present invention provides a preparation method of a high-strength fluororubber, comprising the following steps:

[0030] (1) First, the fluororubber raw rubber is plasticized in an open mill, the distance between two adjacent roller surfaces is controlled to be 0.3-0.5 mm, the plasticizing temperature is 40-60° C., and the plasticizing time is 10-40 min to obtain the plasticized fluororubber;

[0031] (2) adding the plasticized fluororubber, acid absorber, release agent, coupling agent, reinforcing agent, and filler into an internal mixer, and mixing them thoroughly at a mixing temperature of 55-65° C. for 4-8 minutes, then adding a vulcanizing agent and a vulcanization accelerator, and mixing them again at a mixing temperature of 90-110° C. for 3-5 minutes to obtain the mixed fluororubber;

[0032] (3) The mixed fluororubber is placed in a mold and pressurized at a temperature of 165-170°C, a pressure of 15-20 MPa, and a time of 10-15 minutes. After demolding, it is treated in an oven at 200-220°C for 12-24 hours to obtain high-strength fluororubber.

[0033] The beneficial effects of the present invention are:

[0034] 1. The present invention prepares a fluororubber material, which not only has the advantages of high temperature resistance, oil resistance, and corrosion resistance, but also has excellent strength and toughness. It is suitable for use as a material for sealing gaskets and linings of chemical equipment. It can remain stable in various chemical and solvent environments, ensuring the long-term normal operation of the equipment.

[0035] 2. In the fluororubber material prepared by the present invention, a filler and a reinforcing agent are used in combination, wherein the reinforcing agent is modified carbon black N990. Compared with traditional carbon black N990, the modified carbon black N990 of the present invention has better compatibility with fluororubber, and on the basis of maintaining high temperature resistance and corrosion resistance, it has a significant improvement in the tensile strength and tear strength of fluororubber.

[0036] 3. The preparation process of modified carbon black N990 is to first treat carbon black N990 with an aminosilane coupling agent to obtain amino carbon black N990; then combine it with 5-hydroxymethylfurfural through an amine-aldehyde condensation reaction to obtain functionalized carbon black N990 containing Schiff base; finally, esterify it with terminal carboxyl fluororubber to finally prepare carbon black N990 material coated with Schiff base functional group and fluororubber, that is, modified carbon black N990.

[0037] 4. After adding modified N990 carbon black as a reinforcing agent in the present invention, not only dust pollution is reduced, but also the mixing time is shortened by 30%-50% (the traditional mixing time is 10-20 minutes) during subsequent mixing, thereby accelerating the production efficiency of industrial fluororubber. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0039] Figure 1 1 is a SEM schematic diagram (5 μm) of the fluororubber material prepared in Example 1 of the present invention;

[0040] Figure 2 This is a SEM schematic diagram (200 μm) of the fluororubber material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the presence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be regarded as the scope of the present invention.

[0042] In order to better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0043] The present invention will be further described below with reference to the following examples.

[0044] Example 1

[0045] A high-strength fluororubber material, calculated by weight, comprising the following components:

[0046] 100 parts of fluororubber raw rubber, 25 parts of reinforcing agent, 15 parts of filler, 12 parts of acid absorber, 0.3 parts of coupling agent, 0.6 parts of release agent, 3 parts of vulcanizing agent and 1.8 parts of vulcanization accelerator.

[0047] Among them, the brand of the fluororubber raw rubber is FE2463; the filler is 5μm calcium carbonate; the acid absorber is a mixture of calcium hydroxide and magnesium oxide, and the mass ratio of calcium hydroxide to magnesium oxide is 4:9; the coupling agent is silane coupling agent A-151; the release agent is carnauba wax; the vulcanizing agent is bisphenol AF; and the vulcanization accelerator is benzyltriphenylphosphine chloride.

[0048] Wherein, the reinforcing agent is modified N990 carbon black, and the preparation method includes:

[0049] S1. Take 1g of carbon black N990 (average particle size of 280nm) obtained by thermal cracking and place it in 15mL of 60% ethanol aqueous solution, then add 0.26g of aminosilane coupling agent KH-550. After fully dispersed, reflux in a water bath for 6h, then centrifuge and dry to obtain amino carbon black N990;

[0050] S2. Dissolve 0.39 g of 5-hydroxymethylfurfural (5-HMF) in 15 mL of anhydrous ethanol, add 1 g of amino-functionalized carbon black N990, add dropwise glacial acetic acid (3% by weight of 5-hydroxymethylfurfural), heat to 75° C. and reflux for 15 h. After the reaction, remove the solvent under reduced pressure, wash with water 4 times, and dry to obtain Schiff base functionalized carbon black N990;

[0051] S3. Dissolve 2.7 g of carboxyl-terminated fluororubber (CTLF, Mn=2460, carboxyl groups account for 2.3%) in 18 mL of tetrahydrofuran, then slowly add 1 g of Schiff base functionalized carbon black N990 while stirring. After all the addition, fully disperse it until it is uniform. Add 2.7% of the mass of carboxyl-terminated fluororubber toluenesulfonic acid as a catalyst. Under the protection of nitrogen, heat to 130 ° C, keep stirring for 12 hours, cool to room temperature after the reaction is completed, remove the solvent under reduced pressure, wash with saturated sodium carbonate solution until neutral, wash with water 4 times and dry, and crush to obtain modified N990 carbon black.

[0052] The preparation method of the high-strength fluororubber comprises the following steps:

[0053] (1) First, the fluororubber raw rubber was plasticized in an open mill, with the distance between two adjacent roller surfaces controlled to be 0.5 mm, the plasticizing temperature to be 50° C., and the plasticizing time to be 25 min, to obtain the plasticized fluororubber;

[0054] (2) adding the plasticized fluororubber, acid absorber, release agent, coupling agent, reinforcing agent, and filler into an internal mixer and mixing them thoroughly at a mixing temperature of 60° C. for 6 minutes, then adding a vulcanizing agent and a vulcanization accelerator and mixing them again at a mixing temperature of 100° C. for 4 minutes to obtain the mixed fluororubber;

[0055] (3) The mixed fluororubber is placed in a mold and pressurized at a temperature of 170°C, a pressure of 18 MPa, and a time of 12 minutes. After demolding, it is treated in an oven at 210°C for 18 hours to obtain high-strength fluororubber.

[0056] Example 2

[0057] A high-strength fluororubber material, calculated by weight, comprising the following components:

[0058] 100 parts of fluororubber raw rubber, 22 parts of reinforcing agent, 13 parts of filler, 12 parts of acid absorber, 0.4 parts of coupling agent, 0.7 parts of release agent, 4 parts of vulcanizing agent and 1.7 parts of vulcanization accelerator.

[0059] The fluororubber raw rubber is FE2461; the filler is barium sulfate; the acid absorber is a mixture of calcium hydroxide and magnesium oxide, with a mass ratio of calcium hydroxide to magnesium oxide of 3:5; the coupling agent is silane coupling agent A-171; the release agent is paraffin; the vulcanizing agent is bisphenol AF; and the vulcanization accelerator is benzyltriphenylphosphine chloride.

[0060] Wherein, the reinforcing agent is modified N990 carbon black, and the preparation method includes:

[0061] S1. Take 1g of carbon black N990 (average particle size of 280nm) obtained by thermal cracking and place it in 12mL of 50% ethanol aqueous solution, then add 0.17g of aminosilane coupling agent. After fully dispersed, reflux in a water bath for 3h, then centrifuge and dry to obtain amino carbon black N990;

[0062] S2. Dissolve (0.26-0.52) g of 5-hydroxymethylfurfural (5-HMF) in (10-20) mL of anhydrous ethanol, add 1 g of amino carbon black N990, add dropwise glacial acetic acid (2% by weight of 5-hydroxymethylfurfural), heat to 75° C. and reflux for 15 h. After the reaction, remove the solvent under reduced pressure, wash with water three times, and dry to obtain Schiff base functionalized carbon black N990;

[0063] S3. Dissolve 2.2 g of carboxyl-terminated fluororubber (CTLF, Mn=2460, carboxyl groups account for 2.3%) in 20 mL of tetrahydrofuran, then slowly add 1 g of Schiff base functionalized carbon black N990 while stirring. After all the addition, fully disperse it until it is uniform. Add 3.1% of the mass of carboxyl-terminated fluororubber p-toluenesulfonic acid as a catalyst. Under the protection of nitrogen, heat to 120 ° C, keep stirring for 10 hours, cool to room temperature after the reaction is completed, remove the solvent under reduced pressure, wash with saturated sodium carbonate solution until neutral, wash with water 3 times and dry, and crush to obtain modified N990 carbon black.

[0064] The preparation method of the high-strength fluororubber comprises the following steps:

[0065] (1) First, the fluororubber raw rubber was plasticized in an open mill, with the distance between two adjacent roller surfaces controlled to be 0.5 mm, the plasticizing temperature to be 50° C., and the plasticizing time to be 25 min, to obtain the plasticized fluororubber;

[0066] (2) adding the plasticized fluororubber, acid absorber, release agent, coupling agent, reinforcing agent, and filler into an internal mixer and mixing them thoroughly at a mixing temperature of 60° C. for 6 minutes, then adding a vulcanizing agent and a vulcanization accelerator and mixing them again at a mixing temperature of 100° C. for 4 minutes to obtain the mixed fluororubber;

[0067] (3) The mixed fluororubber is placed in a mold and pressurized at a temperature of 170°C, a pressure of 18 MPa, and a time of 12 minutes. After demolding, it is treated in an oven at 210°C for 18 hours to obtain high-strength fluororubber.

[0068] Example 3

[0069] A high-strength fluororubber material, calculated by weight, comprising the following components:

[0070] 100 parts of fluororubber raw rubber, 20 parts of reinforcing agent, 10 parts of filler, 7 parts of acid absorber, 0.1 parts of coupling agent, 0.1 parts of release agent, 2 parts of vulcanizing agent and 1.2 parts of vulcanization accelerator.

[0071] The fluororubber raw rubber is FE2462; the filler is white carbon black; the acid scavenger is a mixture of calcium hydroxide and magnesium oxide, with a mass ratio of 6:10; the coupling agent is silane coupling agent A-151; the release agent is polyethylene wax; the vulcanizing agent is bisphenol AF; and the vulcanization accelerator is benzyltriphenylphosphine chloride.

[0072] Wherein, the reinforcing agent is modified N990 carbon black, and the preparation method includes:

[0073] S1. Take 1g of carbon black N990 (average particle size of 280nm) obtained by thermal cracking and place it in (10-20)mL of 40% ethanol aqueous solution, then add 0.12g of aminosilane coupling agent. After fully dispersed, reflux in a water bath for 2h, then centrifuge and dry to obtain amino carbon black N990;

[0074] S2. Dissolve 0.26 g of 5-hydroxymethylfurfural (5-HMF) in 10 mL of anhydrous ethanol, add 1 g of amino-functionalized carbon black N990, add dropwise glacial acetic acid (1% by weight of 5-hydroxymethylfurfural), heat to 70° C. and reflux for 10 h. After the reaction, remove the solvent under reduced pressure, wash with water three times, and dry to obtain Schiff base functionalized carbon black N990;

[0075] S3. Dissolve 1.8 g of carboxyl-terminated fluororubber (CTLF, Mn=2460, carboxyl groups account for 2.3%) in 12 mL of tetrahydrofuran, then slowly add 1 g of Schiff base functionalized carbon black N990 while stirring. After all the addition, fully disperse it until it is uniform. Add 1.3% of the mass of carboxyl-terminated fluororubber toluenesulfonic acid as a catalyst. Under the protection of nitrogen, heat to 110°C, keep stirring for 16 hours, cool to room temperature after the reaction is completed, remove the solvent under reduced pressure, wash with saturated sodium carbonate solution until neutral, wash with water 3 times and dry, and crush to obtain modified N990 carbon black.

[0076] The preparation method of the high-strength fluororubber comprises the following steps:

[0077] (1) First, the fluororubber raw rubber was plasticized in an open mill, the distance between two adjacent roller surfaces was controlled to be 0.5 mm, the plasticizing temperature was 40° C., and the plasticizing time was 40 min to obtain the plasticized fluororubber;

[0078] (2) adding the plasticized fluororubber, acid absorber, release agent, coupling agent, reinforcing agent, and filler into an internal mixer and mixing them thoroughly at a mixing temperature of 55° C. for 8 minutes, then adding a vulcanizing agent and a vulcanization accelerator and mixing them again at a mixing temperature of 90° C. for 5 minutes to obtain the mixed fluororubber;

[0079] (3) The mixed fluororubber is placed in a mold and pressurized at a temperature of 165°C, a pressure of 15 MPa, and a time of 15 minutes. After demolding, it is treated in an oven at 200°C for 24 hours to obtain high-strength fluororubber.

[0080] Example 4

[0081] A high-strength fluororubber material, calculated by weight, comprising the following components:

[0082] 100 parts of fluororubber raw rubber, 30 parts of reinforcing agent, 20 parts of filler, 16 parts of acid absorber, 0.5 parts of coupling agent, 1 part of release agent, 5 parts of vulcanizing agent and 2 parts of vulcanization accelerator.

[0083] The fluororubber raw rubber is FE2603; the filler is carbon fiber; the acid absorber is a mixture of calcium hydroxide and magnesium oxide, with a mass ratio of 3:5; the coupling agent is silane coupling agent A-151; the release agent is carnauba wax; the vulcanizing agent is bisphenol AF; and the vulcanization accelerator is benzyltriphenylphosphine chloride.

[0084] Wherein, the reinforcing agent is modified N990 carbon black, and the preparation method includes:

[0085] S1. Take 1g of carbon black N990 (average particle size of 280nm) obtained by thermal cracking and place it in 20mL of 80% ethanol aqueous solution, then add 0.38g of aminosilane coupling agent. After fully dispersed, reflux in a water bath for 8h, then centrifuge and dry to obtain amino carbon black N990;

[0086] S2. Dissolve 0.52 g of 5-hydroxymethylfurfural (5-HMF) in 20 mL of anhydrous ethanol, add 1 g of amino-functionalized carbon black N990, add dropwise glacial acetic acid (5% by weight of 5-hydroxymethylfurfural), heat to 80° C. and reflux for 20 h. After the reaction, remove the solvent under reduced pressure, wash with water 5 times, and dry to obtain Schiff base functionalized carbon black N990;

[0087] S3. Dissolve 3.6 g of carboxyl-terminated fluororubber (CTLF, Mn=2460, carboxyl groups account for 2.3%) in 24 mL of tetrahydrofuran, then slowly add 1 g of Schiff base functionalized carbon black N990 while stirring. After all the addition, fully disperse it until it is uniform. Add 4.6% of the mass of carboxyl-terminated fluororubber p-toluenesulfonic acid as a catalyst. Under the protection of nitrogen, heat to 150 ° C, keep stirring for 8 hours, cool to room temperature after the reaction is completed, remove the solvent under reduced pressure, wash with saturated sodium carbonate solution until neutral, wash with water 5 times and dry, and crush to obtain modified N990 carbon black.

[0088] The preparation method of the high-strength fluororubber comprises the following steps:

[0089] (1) First, the fluororubber raw rubber was plasticized in an open mill, the distance between two adjacent roller surfaces was controlled to be 0.5 mm, the plasticizing temperature was 60°C, and the plasticizing time was 10 min to obtain the plasticized fluororubber;

[0090] (2) adding the plasticized fluororubber, acid absorber, release agent, coupling agent, reinforcing agent, and filler into an internal mixer and mixing them thoroughly at a mixing temperature of 65° C. for 4 minutes, then adding a vulcanizing agent and a vulcanization accelerator and mixing them again at a mixing temperature of 110° C. for 3 minutes to obtain the mixed fluororubber;

[0091] (3) The mixed fluororubber is placed in a mold and pressurized at a temperature of 170°C, a pressure of 20 MPa, and a time of 10 minutes. After demolding, it is treated in an oven at 220°C for 12 hours to obtain high-strength fluororubber.

[0092] Comparative Example 1

[0093] A fluororubber material, calculated by weight, comprising the following components:

[0094] 100 parts of fluororubber raw rubber, 25 parts of reinforcing agent, 15 parts of filler, 12 parts of acid absorber, 0.3 parts of coupling agent, 0.6 parts of release agent, 3 parts of vulcanizing agent and 1.8 parts of vulcanization accelerator.

[0095] The only difference between this comparative example and Example 1 is that the filler is replaced by N990 carbon black (average particle size of 280 nm).

[0096] Comparative Example 2

[0097] A fluororubber material, calculated by weight, comprising the following components:

[0098] 100 parts of fluororubber raw rubber, 25 parts of reinforcing agent, 15 parts of filler, 12 parts of acid absorber, 0.3 parts of coupling agent, 0.6 parts of release agent, 3 parts of vulcanizing agent and 1.8 parts of vulcanization accelerator.

[0099] The only difference between this comparative example and Example 1 is that the filler is replaced by Schiff base functionalized carbon black N990 (prepared in the same manner as step S2 of Example 1).

[0100] Comparative Example 3

[0101] A fluororubber material, calculated by weight, comprising the following components:

[0102] 100 parts of fluororubber raw rubber, 25 parts of reinforcing agent, 15 parts of filler, 12 parts of acid absorber, 0.3 parts of coupling agent, 0.6 parts of release agent, 3 parts of vulcanizing agent and 1.8 parts of vulcanization accelerator.

[0103] The only difference between this comparative example and Example 1 is that the filler is replaced by a mixture of N990 carbon black (average particle size of 280 nm) and carboxyl-terminated fluororubber (CTLF, Mn=2460, carboxyl group proportion of 2.3%), and the mass ratio of N990 carbon black to carboxyl-terminated fluororubber is 1:2.7.

[0104] Experimental example

[0105] In order to more clearly describe the content of the present invention, for the optimal Example 1 of the present invention, Comparative Examples 1-3 are set as control examples, and multiple properties of the fluororubber materials prepared in Example 1 and Comparative Examples 1-3 are detected. Among them, the tensile strength detection refers to the standard ASTM D412, the tear strength detection refers to the standard ASTM D624, the hardness detection refers to the standard ASTM D2240, the high-temperature resistance detection refers to the standard ASTM D573 (performance retention rate after aging at 275°C for 24 hours), the oil resistance detection refers to the standard ASTM D471 (Great Wall thickened hydraulic oil No. 40, 100°C × 168h, volume measurement and calculation before and after impregnation), and the acid and alkali resistance detection refers to the standard ISO 1817 (alkali solution: 10wt% sodium hydroxide solution; acid solution: 10wt% sulfuric acid solution; 23°C × 72h, weigh the mass change before and after the test after the test is completed).

[0106] The test results are shown in Table 1 as follows:

[0107] Table 1 Performance test results of different fluororubber materials

[0108]

[0109] It can be seen from the results in Table 1 that compared with Comparative Example 1, the fluororubber material prepared in Example 1 of the present invention can exhibit more excellent tensile strength and tear strength on the basis of maintaining excellent oil resistance and corrosion resistance, and at the same time, there is also a certain improvement in high-temperature resistance. In summary, it shows that the fluororubber material prepared in Example 1 of the present invention not only has the advantages of high temperature resistance, oil resistance and corrosion resistance, but also has excellent strength and toughness, is suitable for use as a sealing material for various equipment, and has a very broad application prospect.

[0110] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-strength fluororubber, characterized in that, Calculated by weight, it includes the following ingredients: 100 parts of fluororubber raw rubber, 20-30 parts of reinforcing agent, 10-20 parts of filler, 7-16 parts of acid absorber, 0.1-0.5 parts of coupling agent, 0.1-1 parts of release agent, 2-5 parts of vulcanizing agent and 1.2-2 parts of vulcanization accelerator; The reinforcing agent is modified carbon black N990, and the preparation process is as follows: first, carbon black N990 is subjected to an amination treatment to obtain aminated carbon black N990; then, an amine-aldehyde condensation reaction is carried out with 5-hydroxymethylfurfural to obtain Schiff base functionalized carbon black N990; and finally, an esterification reaction is carried out with terminal carboxyl fluororubber to obtain modified carbon black N990.

2. The high-strength fluororubber according to claim 1, characterized in that, The filler is at least one of white carbon black, calcium carbonate, barium sulfate, calcium oxide, and carbon fiber.

3. A high-strength fluororubber according to claim 1, wherein, The acid scavenger is a mixture of calcium hydroxide and magnesium oxide, and the mass ratio of calcium hydroxide to magnesium oxide is 3-6:5-10.

4. A high-strength fluororubber according to claim 1, characterized in that The coupling agent is silane coupling agent A-151 or silane coupling agent A-171; the release agent is carnauba wax, paraffin wax or polyethylene wax.

5. A high-strength fluororubber according to claim 1, wherein, The vulcanizing agent is bisphenol AF; the vulcanization accelerator is benzyltriphenylphosphine chloride.

6. A high-strength fluororubber according to claim 1, wherein, The preparation method of the modified N990 carbon black comprises: S1. Carbon black N990 is placed in an ethanol aqueous solution, and then an aminosilane coupling agent is added. After sufficient dispersion, the mixture is refluxed in a water bath for 2-8 hours, and then centrifuged and dried to obtain amino carbon black N990. S2. Dissolve 5-hydroxymethylfurfural in anhydrous ethanol, add amino carbon black N990, add catalyst dropwise, heat to 70-80°C and reflux for 10-20 hours. After the reaction, reduce pressure, wash and dry to obtain Schiff base functionalized carbon black N990. S3. Dissolve the carboxyl-terminated fluororubber in tetrahydrofuran, then slowly add the Schiff base functionalized carbon black N990 while stirring. After all the addition, fully disperse it until it is uniform. Add the catalyst, and under the protection of nitrogen, heat it to 110-150°C, keep it warm and stir for 8-16 hours. After the reaction is completed, remove impurities to obtain modified N990 carbon black.

7. A high-strength fluororubber according to claim 1, characterized in that, In the S1, the mass volume ratio of carbon black N990, aminosilane coupling agent and ethanol aqueous solution is 1g:(0.12-0.38)g:(10-20)mL.

8. A high-strength fluororubber according to claim 1, characterized in that, In S2, the mass volume ratio of amination carbon black N990, 5-hydroxymethylfurfural and anhydrous ethanol is 1 g: (0.26-0.52) g: (10-20) mL.

9. A high-strength fluororubber according to claim 1, characterized in that In S3, the mass volume ratio of Schiff base functionalized carbon black N990, carboxyl-terminated fluororubber and tetrahydrofuran is 1 g:(1.8-3.6) g:(12-24) mL; the catalyst is p-toluenesulfonic acid, and the added amount is 1.3%-4.6% of the mass of the carboxyl-terminated fluororubber.

10. A method for preparing the high-strength fluororubber according to claim 1, characterized in that, The following steps are involved: (1) First, the fluororubber raw rubber is plasticized in an open mill to obtain the plasticized fluororubber; (2) adding the plasticized fluororubber, acid absorber, release agent, coupling agent, reinforcing agent, and filler into an internal mixer, mixing them thoroughly, then adding a vulcanizing agent and a vulcanization accelerator, and mixing them again to obtain the mixed fluororubber; (3) Place the kneaded fluororubber in a mold for pressure molding, and after demolding, further process it in an oven to obtain high-strength fluororubber.

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