Preparation method and application of low-temperature-resistant high-purity perfluoroether rubber

Abstract

The invention discloses a preparation method and application of low-temperature-resistant high-purity perfluoroether rubber, and relates to the technical field of perfluoroether rubber. The preparation method comprises the following specific steps: adding high-purity water, a microemulsion, a monomer A and a monomer B into a polymerization kettle, starting stirring, heating the polymerization kettle, introducing PMVE, a first mixed gas of PMVE and TFE, a chain transfer agent, a vulcanization point monomer and an initiator, introducing a second mixed gas of PMVE and TFE during a reaction period, releasing pressure of the polymerization kettle after a copolymerization reaction is terminated, and discharging to obtain a finished product. And condensing, washing and drying the obtained elastomer emulsion to obtain the perfluoroether rubber, and mixing to finally obtain the vulcanized perfluoroether rubber. The perfluoromethyl vinyl ether-tetrafluoroethylene copolymer prepared by the invention has excellent mechanical properties, low temperature resistance and sulfur change performance.

Description

Technical Field

[0001] The present invention relates to the technical field of fluoroether rubber, in particular to a preparation method and application of low-temperature resistant high-purity perfluoroether rubber. Background Art

[0002] Perfluoroether rubber is widely used in chemical reaction device seals in various factories, chemical pipeline linings and accessories, seals in the semiconductor industry, and special parts in the automotive industry, petrochemical industry and aerospace industry.

[0003] Patent document CN105218985 discloses a method for improving the corrosion resistance of fluororubber, particularly its resistance to hydrofluoric acid. The method involves adding a certain amount of perfluoroether rubber to fluororubber. While this method improves the corrosion resistance of the fluororubber, the blended materials significantly reduce the perfluoroether rubber's excellent resistance to media. The patent does not examine the perfluoroether rubber's low-temperature resistance.

[0004] Patent document CN110903428 A discloses a low-temperature resistant fluoroether rubber, its preparation method, and application. The rubber is obtained by emulsion polymerization at a certain temperature and pressure using one or more comonomers of vinylidene fluoride / tetrafluoroethylene / perfluoropropylene, a low-temperature comonomer perfluoroalkyl vinyl ether, a vulcanization point monomer iodinated perfluoroolefin, and a chain transfer agent iodinated alkane. However, the resulting rubber product has a permanent compression set (O-ring, 200°C, 70h) of more than 20%, a glass transition temperature of -22 to -37°C, and a tensile strength of approximately 18 MPa to 25 MPa.

[0005] Patent document CN104530292A discloses a method for preparing a low-temperature resistant perfluoroether rubber. The method comprises mixing an emulsifier, a fluoroether oil, and water in a certain proportion and heating the mixture to form a microemulsion. Then, comonomer A, comonomer B, tetrafluoroethylene, perfluoromethyl vinyl ether, a pH regulator, and an initiator are added for reaction. The perfluoroether rubber prepared by the method of the present invention is easy to process, has a glass transition temperature of -29 to -36°C, a tensile strength of about 18 to 23 MPa, and an elongation at break of 220 to 250. However, if the copolymerization temperature of the invention is lower than 70°C, the polymerization rate is too slow and is not suitable for industrial production. If the temperature is higher than 120°C, the fluoroelastomer polymer emulsion becomes viscous and blocks the pipeline, making it difficult to maintain the stability of the emulsion during the reaction, and the experimental repeatability is poor.

[0006] In the existing PMVE-TFE process, although the perfluoroether rubber obtained has a certain low-temperature resistance, the low purity of the product makes it difficult to be applied to cutting-edge products such as electronic chips. There is an urgent need to find a method for synthesizing low-temperature resistant high-purity perfluoroether rubber in a microemulsion system. Although methods for synthesizing low-temperature fluoroether rubber in a microemulsion system have been reported, the preparation of the microemulsion in the reported methods is greatly affected by temperature. The microemulsion needs to be heated before the reaction, and the microemulsion system is unstable and easily delaminated. In addition, the purity of the product produced is not high and does not meet the requirements of cutting-edge products such as electronics. Summary of the Invention

[0007] The present invention provides a method for preparing and applying a low-temperature-resistant, high-purity perfluoroether rubber. The rubber is obtained by initiating a polymerization reaction under microemulsion conditions using comonomers A and B as comonomers, tetrafluoroethylene and perfluoroalkyl vinyl ether as reactive monomers, iodinated fluoroolefins as vulcanization site monomers, and iodinated alkanes as chain transfer agents.

[0008] The specific plan is as follows:

[0009] A preparation method and application of low-temperature resistant high-purity perfluoroether rubber, the operating steps of which are as follows:

[0010] S1: Add 300-400 parts of high-purity water to a polymerization kettle in parts by weight, start stirring and add 0.5-2 parts of microemulsion, add 0.25-0.45 parts of comonomers A and B to the above microemulsion, stir at a speed of 30-120 rpm, heat the polymerization kettle while introducing PMVE to a temperature of 80-120°C and a pressure of 1.5-1.8 MPa, then introduce a first mixed gas of PMVE and TFE to a pressure of 3.0-5.0 MPa in the polymerization kettle, add 0.05-0.2 parts of chain transfer agent, 0.02-0.1 parts of vulcanization site monomer, and 0.01-0.1 parts of initiator to initiate copolymerization;

[0011] S2: After the polymerization reaction starts, a second mixed gas of PMVE and TFE is introduced, and the pressure of the polymerization kettle is maintained at 3.0-5.0 MPa and the temperature is 80-120°C. When the consumption of the second mixed monomer reaches 30-50 parts, the copolymerization reaction is terminated, the polymerization kettle is depressurized and the material is discharged. The obtained elastomer emulsion is coagulated, washed, and dried to obtain perfluoroether rubber;

[0012] S3: Prepare the following mixing components: (1) 10-12 parts of raw rubber; (2) 0.15-0.18 parts of triallylsilsesquioxane modified curing agent; (3) 0.3-0.5 parts of 2,5-di-tert-butylperoxy-2,5-dimethylethane curing aid; (4) 1.5-2 parts of filler material MT carbon black N9900; (5) 0.5-0.8 parts of processing aid octadecanoic acid, add the above components into an internal mixer and mix, place at room temperature for 20 hours, and then return to the open mixer to finally obtain perfluoroether rubber vulcanizate.

[0013] The mass ratio of the microemulsion is emulsifier:polyether oil:water=10:1~1:10~1:10.

[0014] The emulsifier is selected from potassium perfluoropolyether carboxylate, magnesium perfluoropolyether carboxylate, sodium perfluoropolyether carboxylate, and ammonium perfluoropolyether carboxylate; the polyether oil is selected from PFPE, and its structural formula is (—CF2—O—CF2—)n.

[0015] The comonomer A is selected from CF3CF2CF2CF2O(CF(CF3)CF2O)nCF=CF2, n=0-6, preferably n=1-3; the comonomer B is selected from CF3CF2O(CF3CF2O)mCF=CF2, m=0-5, preferably m=1-3.

[0016] The chain transfer agent is selected from one of iodinated alkanes, alkane compounds, alcohols, fats, and organic halides, including one or more combinations of 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane, 1,3-diiodine-2-chloroperfluoropropane, 1,5-diiodine-2,4-dichloroperfluoropentane, 1,3-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, perfluoroisopropyl iodide, perfluoro-n-butyl iodide, trifluoromethyl iodide, methyl iodide, isopentane, methanol, isopropanol, ethyl acetate, diethyl malonate, CCl4, CBrCl3, CF2BrCFBrCF3 and CF2I2.

[0017] The vulcanization site monomer is selected from chlorinated olefins, including one or a combination of trifluoroethylene bromide, 4-bromoperfluoro-1-butene, 1-bromo-2,2-difluoroethylene, 4-bromo-3,3,4,4-tetrafluoro-1-butene, perfluoroalkyl bromide, 4-bromo-1,1,2-trifluoro-1-butene, and 4-bromo-1,1,3,3,4,4-hexafluoro-1-butene.

[0018] The initiator is selected from one or a combination of diisopropyl peroxydicarbonate, benzoyl peroxide, cumene peroxide, tert-butyl hydroperoxide, potassium persulfate, and ammonium persulfate.

[0019] The molar ratio of PMVE to TFE in the first mixture is 1:1.0-2.0; the molar ratio of PMVE to TFE in the second mixture is 1:1.5-2.0; and the purity of the PMVE and TFE monomers is not less than 99.99%.

[0020] The triallylsilsesquioxane-modified curing agent reacts via a condensation reaction between an isocyanurate and a hydroxyl group. During this process, the carbon-nitrogen double bond (C=N) in TAIC reacts with the hydroxyl group (-OH) of the 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex. Through a nucleophilic addition mechanism, the oxygen atom on the hydroxyl group attacks the carbon atom on the TAIC ring, opening the ring to form an intermediate, which then deprotonates and closes the ring to form a stable urea ketone structure.

[0021] Role of silsesquioxane: Trisilanolphenyl-cage polysilsesquioxane may act as a template or scaffold in this process. Its porous structure and high specific surface area provide a good reaction interface between TAIC and the complex, and promote the reaction through physical adsorption or chemical bonding.

[0022] The preparation method of triallylsilsesquioxane modified vulcanizing agent is as follows:

[0023] In a sealed stirred reactor, 25-50 parts of triallyl isocyanurate (TAIC, CAS: 1025-16-2), 0.5-2.5 parts of 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex, 0.01-0.1 parts of trisilanolphenyl-cage polysilsesquioxane (CAS: 444315-26-8), 1-3 parts of stannous octoate, and 200-300 parts of toluene are added by weight; the mixture is stirred at 60-70° C. for 120-180 minutes, and the toluene is removed by distillation to obtain a triallyl silsesquioxane-modified vulcanizing agent.

[0024] The preparation method of the DL-4-hydroxy-2-ketoglutaric acid / zirconium / lanthanum complex comprises the following steps: adding 16-32 parts of 4,4'-dihydroxy-2,2'-bipyridine, 7-14 parts of zirconium nitrate, 16-32 parts of lanthanum nitrate, and 200-300 parts of water, stirring at 40-50° C. for 100-150 minutes, and removing the water by distillation to obtain the 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex.

[0025] The technical effects of this method are as follows:

[0026] 1. Improvement of physical properties: The introduction of 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex and silsesquioxane improves the vulcanization efficiency of fluororubber because these two compounds provide more crosslinking points, increasing the crosslinking density during the vulcanization process, thereby improving the hardness and tear strength of the material.

[0027] 2. Improved heat resistance: TAIC itself has good thermal stability, and the cross-linked structure formed during the vulcanization process can further enhance the material's heat resistance. Furthermore, the silicon-oxygen-silicon bond of silsesquioxane also has good thermal stability, and its addition helps enhance the overall material's heat resistance.

[0028] 3. Enhanced chemical stability: The urea ketone structure formed by the above-mentioned chemical reaction is relatively stable and is not easy to undergo reverse reaction or decomposition under changes in the external environment, thereby enhancing the chemical stability of the material.

[0029] 4. The perfluoromethyl vinyl ether-tetrafluoroethylene copolymer prepared by the present invention has excellent mechanical properties, with a tensile strength of ≥26 MPa and an elongation at break of ≥250%; and excellent low-temperature resistance, reaching a minimum of -50°C.

[0030] 5. The solvent water used in the present invention can be recycled and reused, which reduces production costs and is environmentally friendly. DETAILED DESCRIPTION

[0031] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. The detection methods of the following examples are as follows:

[0032] (1) Glass transition temperature: DSC, take the median value.

[0033] (2) Vulcanized product TR-10: GB / T7758-2002.

[0034] (3) Low temperature brittleness temperature: GB / T15256-1994.

[0035] (4)Tensile strength: GB / T528-2008.

[0036] (5) Permanent compression set (O-ring, 200°C, 70h): GB / T7759.0-2015.

[0037] (6) Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 1: Shore durometer method.

[0038] Example 1

[0039] A method for preparing fluoroether rubber comprises the following steps:

[0040] S1: 30 kg of high-purity water was added to a 50 L stainless steel polymerization kettle and stirring was started at 60 rpm. 4 kg of pure PMVE and 900 g of emulsifier (a mixture of potassium perfluoropolyether carboxylate: polyether oil: water = 10:1:1) were introduced into the polymerization kettle. A (2000 g) of CF3CF2CF2CF2O (CF(CF3)CF2O)CF=CF2 and B (1500 g) of CF3CF2O (CF3CF2O)CF=CF2) were added to the above microemulsion. The temperature was raised to 80° C. until the pressure of the polymerization kettle was about 1.8 MPa. Then, PMVE and tetrafluoroethylene were first mixed to a pressure of 3.0 MPa in the polymerization kettle. 30 g of chain transfer agent 1,2-diiodoethane, 50 g of vulcanization site monomer 1-iodo-2,2-difluoroethylene, and 6 g of initiator potassium persulfate were added to initiate copolymerization.

[0041] S2: After the polymerization reaction begins, a second mixed gas of PMVE and TFE is introduced. The molar ratio of PMVE to TFE in the second mixture is 0.5:1. The pressure in the polymerization reactor is maintained at 3.0 MPa. When the consumption of the second mixed monomer reaches 20 kg, the copolymerization reaction is terminated, and the polymerization reactor is depressurized and discharged to obtain an elastomer emulsion. A magnesium chloride solution is added to the elastomer emulsion for coagulation and washing. The elastomer is then dried in a vacuum drying oven at 120°C for 4 hours to obtain a low-temperature resistant perfluoroether rubber elastomer product.

[0042] S3: Prepare the following mixing components: (1) 10 kg of raw rubber; (2) 0.15 kg of triallylsilsesquioxane-modified curing agent; (3) 0.3 kg of 2,5-di-tert-butylperoxy-2,5-dimethylethane curing aid; (4) 1.5 kg of MT carbon black N9900 filler; (5) 0.5 kg of octadecanoic acid processing aid. Add the above components to an internal mixer and mix them. After standing at room temperature for 20 hours, remix them on an open mixer to finally produce a perfluoroether rubber vulcanizate.

[0043] The preparation method of triallylsilsesquioxane modified vulcanizing agent is as follows:

[0044] In a sealed stirred reactor, 25 kg of triallyl isocyanurate (TAIC, CAS: 1025-16-2), 0.5 kg of 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex, 0.01 kg of trisilanolphenyl-cage polysilsesquioxane (CAS: 444315-26-8), 1 kg of stannous octoate, and 200 kg of toluene were added. The mixture was stirred at 60° C. for 120 minutes, and the toluene was removed by distillation to obtain a triallyl silsesquioxane-modified vulcanizing agent.

[0045] The preparation method of the DL-4-hydroxy-2-ketoglutaric acid / zirconium / lanthanum complex comprises the following steps: 16 kg of 4,4'-dihydroxy-2,2'-bipyridine, 7 kg of zirconium nitrate, 16 kg of lanthanum nitrate, and 200 kg of water are stirred at 40° C. for 100 minutes, and the water is removed by distillation to obtain the 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex.

[0046] Table 1 Performance test of perfluoroether rubber

[0047]

[0048]

[0049] Example 2

[0050] A method for preparing perfluoroether rubber comprises the following steps:

[0051] S1: 30 kg of high-purity water was added to a 50 L stainless steel polymerization kettle and stirring was started at 80 rpm. 4 kg of pure PMVE and 300 g of emulsifier (a mixture of magnesium perfluoropolyether carboxylate: polyether oil: water = 1:10:1) were introduced into the polymerization kettle. A (2000 g) of CF3CF2CF2CF2O (CF(CF3)CF2O)CF=CF2 and B (1500 g) of CF3CF2O (CF3CF2O)CF=CF2) were added to the above microemulsion. The temperature was raised to 90° C. until the polymerization kettle pressure was about 2.0 MPa. Then, PMVE and tetrafluoroethylene were first mixed to a polymerization kettle pressure of 4.0 MPa. 30 g of chain transfer agent 1,2-diiodoethane, 50 g of vulcanization site monomer 1-iodo-2,2-difluoroethylene, and 6 g of initiator potassium persulfate were added to initiate copolymerization.

[0052] S2: After the polymerization reaction starts, a second mixed gas of PMVE and TFE is introduced. The molar ratio of PMVE and TFE in the second mixture is 0.5:1. The pressure of the polymerization kettle is maintained at 4.0 MPa. When the consumption of the second mixed monomer reaches 20 kg, the copolymerization reaction is terminated, the polymerization kettle is depressurized and the material is discharged. The obtained elastomer emulsion is condensed, washed and dried to obtain perfluoroether rubber.

[0053] S3: Prepare the following mixing components: (1) 10 kg of raw rubber; (2) 0.15 kg of triallylsilsesquioxane-modified curing agent; (3) 0.3 kg of 2,5-di-tert-butylperoxy-2,5-dimethylethane curing aid; (4) 1.5 kg of MT carbon black N9900 filler; (5) 0.5 kg of octadecanoic acid processing aid. Add the above components to an internal mixer and mix them. After standing at room temperature for 20 hours, remix them on an open mixer to finally produce a perfluoroether rubber vulcanizate.

[0054] The preparation method of triallylsilsesquioxane modified vulcanizing agent is as follows:

[0055] In a sealed stirred reactor, 35 kg of triallyl isocyanurate (TAIC, CAS: 1025-16-2), 1 kg of 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex, 0.045 kg of trisilanolphenyl-cage polysilsesquioxane (CAS: 444315-26-8), 2 kg of stannous octoate, and 250 kg of toluene were added. The mixture was stirred at 65° C. for 140 minutes, and the toluene was removed by distillation to obtain a triallyl silsesquioxane-modified vulcanizing agent.

[0056] The preparation method of the DL-4-hydroxy-2-ketoglutaric acid / zirconium / lanthanum complex comprises the following steps: 24 kg of 4,4'-dihydroxy-2,2'-bipyridine, 9 kg of zirconium nitrate, 24 kg of lanthanum nitrate, and 250 kg of water are stirred at 45° C. for 125 minutes, and the water is removed by distillation to obtain the 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex.

[0057] Table 2 Performance test of perfluoroether rubber

[0058]

[0059] Example 3

[0060] A method for preparing perfluoroether rubber comprises the following steps:

[0061] S1: 30 kg of high-purity water was added to a 50 L stainless steel polymerization kettle and stirring was started at 100 rpm. 4 kg of pure PMVE and 300 g of emulsifier (a mixture of sodium perfluoropolyether carboxylate: polyether oil: water = 1:1:10) were introduced into the polymerization kettle. A (2000 g) of CF3CF2CF2CF2O (CF(CF3)CF2O)CF=CF2 and B (1500 g) of CF3CF2O (CF3CF2O)CF=CF2) were added to the above microemulsion. The temperature was raised by 100 ° C to a polymerization kettle pressure of about 1.5 MPa. Then, PMVE and tetrafluoroethylene were first mixed until the polymerization kettle pressure reached 3.5 MPa. 30 g of chain transfer agent 1,2-diiodoethane, 50 g of vulcanization site monomer 1-iodo-2,2-difluoroethylene, and 6 g of initiator potassium persulfate were added to initiate copolymerization.

[0062] S2: After the polymerization reaction starts, a second mixed gas of PMVE and TFE is introduced. The molar ratio of PPVE and TFE in the second mixture is 0.5:1. The pressure of the polymerization kettle is maintained at 3.5 MPa. When the consumption of the second mixed monomer reaches 20 kg, the copolymerization reaction is terminated, the polymerization kettle is depressurized and the material is discharged. The obtained elastomer emulsion is condensed, washed and dried to obtain perfluoroether rubber.

[0063] S3: Prepare the following mixing components: (1) 10 kg of raw rubber; (2) 0.15 kg of triallylsilsesquioxane-modified curing agent; (3) 0.3 kg of 2,5-di-tert-butylperoxy-2,5-dimethylethane curing aid; (4) 1.5 kg of MT carbon black N9900 filler; (5) 0.5 kg of octadecanoic acid processing aid. Add the above components to an internal mixer and mix them. After standing at room temperature for 20 hours, remix them on an open mixer to finally produce a perfluoroether rubber vulcanizate.

[0064] The preparation method of triallylsilsesquioxane modified vulcanizing agent is as follows:

[0065] In a sealed stirred reactor, 40 kg of triallyl isocyanurate (TAIC, CAS: 1025-16-2), 2 kg of 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex, 0.08 kg of trisilanolphenyl-cage polysilsesquioxane (CAS: 444315-26-8), 2 kg of stannous octoate, and 250 kg of toluene were added, and the mixture was stirred at 65° C. for 160 minutes. The toluene was removed by distillation to obtain a triallyl silsesquioxane-modified vulcanizing agent;

[0066] The preparation method of the DL-4-hydroxy-2-ketoglutaric acid / zirconium / lanthanum complex comprises the following steps: 28 kg of 4,4'-dihydroxy-2,2'-bipyridine, 12 kg of zirconium nitrate, 28 kg of lanthanum nitrate, and 250 kg of water are stirred at 45° C. for 125 minutes, and the water is removed by distillation to obtain the 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex.

[0067] Table 3 Performance test of perfluoroether rubber

[0068]

[0069]

[0070] Example 4

[0071] A method for preparing perfluoroether rubber comprises the following steps:

[0072] S1: 30 kg of high-purity water was added to a 50 L stainless steel polymerization kettle and stirring was started at 120 rpm. 4.5 kg of pure PMVE and 300 g of emulsifier (a mixture of perfluoropolyether carboxylic acid ammonium: polyether oil: water = 10:5:5) were introduced into the polymerization kettle. A (2000 g) of CF3CF2CF2CF2O (CF(CF3)CF2O)CF=CF2 and B (1500 g) of CF3CF2O (CF3CF2O)CF=CF2) were added to the above microemulsion. The temperature was raised to 70° C. until the polymerization kettle pressure was about 1.5 MPa. Then, PMVE and tetrafluoroethylene were first mixed to a polymerization kettle pressure of 3.5 MPa. 30 g of chain transfer agent 1,2-diiodoethane, 50 g of vulcanization site monomer 1-iodo-2,2-difluoroethylene, and 6 g of initiator potassium persulfate were added to initiate the copolymerization reaction.

[0073] S2: After the polymerization reaction starts, a second mixed gas of PMVE and TFE is introduced. The molar ratio of PMVE and TFE in the second mixture is 0.5:1. The pressure of the polymerization kettle is maintained at 3.5 MPa. When the consumption of the second mixed monomer reaches 20 kg, the copolymerization reaction is terminated, the polymerization kettle is depressurized and the material is discharged. The obtained elastomer emulsion is condensed, washed and dried to obtain perfluoroether rubber.

[0074] S3: Prepare the following mixing components: (1) 10 kg of raw rubber; (2) 0.15 kg of triallylsilsesquioxane-modified curing agent; (3) 0.3 kg of 2,5-di-tert-butylperoxy-2,5-dimethylethane curing aid; (4) 1.5 kg of MT carbon black N9900 filler; (5) 0.5 kg of octadecanoic acid processing aid. Add the above components to an internal mixer and mix them. After standing at room temperature for 20 hours, remix them on an open mixer to finally produce a perfluoroether rubber vulcanizate.

[0075] The preparation method of triallylsilsesquioxane modified vulcanizing agent is as follows:

[0076] In a sealed stirred reactor, 50 kg of triallyl isocyanurate (TAIC, CAS: 1025-16-2), 2.5 kg of 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex, 0.1 kg of trisilanolphenyl-cage polysilsesquioxane (CAS: 444315-26-8), 3 kg of stannous octoate, and 300 kg of toluene were added. The mixture was stirred at 70° C. for 180 minutes, and the toluene was removed by distillation to obtain a triallyl silsesquioxane-modified vulcanizing agent.

[0077] The preparation method of the DL-4-hydroxy-2-ketoglutaric acid / zirconium / lanthanum complex comprises the following steps: 32 kg of 4,4'-dihydroxy-2,2'-bipyridine, 14 kg of zirconium nitrate, 32 kg of lanthanum nitrate, and 300 kg of water are stirred at 50° C. for 150 minutes, and the water is removed by distillation to obtain the 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex.

[0078] Table 4 Performance test of perfluoroether rubber

[0079]

[0080] Comparative Example 1

[0081] A method for preparing fluoroether rubber comprises the following steps:

[0082] S1: 30 kg of high-purity water was added to a 50 L stainless steel polymerization kettle and stirring was started at 60 rpm. 4 kg of pure PMVE and 900 g of emulsifier (a mixture of potassium perfluoropolyether carboxylate: polyether oil: water = 10:1:1) were introduced into the polymerization kettle. A (2000 g) of CF3CF2CF2CF2O (CF(CF3)CF2O)CF=CF2 and B (1500 g) of CF3CF2O (CF3CF2O)CF=CF2) were added to the above microemulsion. The temperature was raised to 80° C. until the pressure of the polymerization kettle was about 1.8 MPa. Then, PMVE and tetrafluoroethylene were first mixed to a pressure of 3.0 MPa in the polymerization kettle. 30 g of chain transfer agent 1,2-diiodoethane, 50 g of vulcanization site monomer 1-iodo-2,2-difluoroethylene, and 6 g of initiator potassium persulfate were added to initiate copolymerization.

[0083] S2: After the polymerization reaction begins, a second mixed gas of PMVE and TFE is introduced. The molar ratio of PMVE to TFE in the second mixture is 0.5:1. The pressure in the polymerization reactor is maintained at 3.0 MPa. When the consumption of the second mixed monomer reaches 20 kg, the copolymerization reaction is terminated, and the polymerization reactor is depressurized and discharged to obtain an elastomer emulsion. A magnesium chloride solution is added to the elastomer emulsion for coagulation and washing. The elastomer is then dried in a vacuum drying oven at 120°C for 4 hours to obtain a low-temperature resistant perfluoroether rubber elastomer product.

[0084] S3: Prepare the following mixing components: (1) 10 kg of raw rubber; (2) 0.15 kg of triallyl isocyanurate (vulcanizing agent); (3) 0.3 kg of 2,5-di-tert-butylperoxy-2,5-dimethylethane (vulcanizing aid); (4) 1.5 kg of MT carbon black N9900 (filler); and (5) 0.5 kg of octadecanoic acid (processing aid). The above components were added to an internal mixer and mixed. After standing at room temperature for 20 hours, the mixture was returned to an open mixer to obtain a perfluoroether rubber vulcanizate.

[0085] Table 5 Performance test of perfluoroether rubber

[0086]

[0087]

[0088] Comparative Example 2

[0089] A method for preparing fluoroether rubber comprises the following steps:

[0090] S1: 30 kg of high-purity water was added to a 50 L stainless steel polymerization kettle and stirring was started at 60 rpm. 4 kg of pure PMVE and 900 g of emulsifier (a mixture of potassium perfluoropolyether carboxylate: polyether oil: water = 10:1:1) were introduced into the polymerization kettle. A (2000 g) of CF3CF2CF2CF2O (CF(CF3)CF2O)CF=CF2 and B (1500 g) of CF3CF2O (CF3CF2O)CF=CF2) were added to the above microemulsion. The temperature was raised to 80° C. until the pressure of the polymerization kettle was about 1.8 MPa. Then, PMVE and tetrafluoroethylene were first mixed to a pressure of 3.0 MPa in the polymerization kettle. 30 g of chain transfer agent 1,2-diiodoethane, 50 g of vulcanization site monomer 1-iodo-2,2-difluoroethylene, and 6 g of initiator potassium persulfate were added to initiate copolymerization.

[0091] S2: After the polymerization reaction begins, a second mixed gas of PMVE and TFE is introduced. The molar ratio of PMVE to TFE in the second mixture is 0.5:1. The pressure in the polymerization reactor is maintained at 3.0 MPa. When the consumption of the second mixed monomer reaches 20 kg, the copolymerization reaction is terminated, and the polymerization reactor is depressurized and discharged to obtain an elastomer emulsion. A magnesium chloride solution is added to the elastomer emulsion for coagulation and washing. The elastomer is then dried in a vacuum drying oven at 120°C for 4 hours to obtain a low-temperature resistant perfluoroether rubber elastomer product.

[0092] S3: Prepare the following mixing components: (1) 10 kg of raw rubber; (2) 0.15 kg of triallylsilsesquioxane-modified curing agent; (3) 0.3 kg of 2,5-di-tert-butylperoxy-2,5-dimethylethane curing aid; (4) 1.5 kg of MT carbon black N9900 filler; (5) 0.5 kg of octadecanoic acid processing aid. Add the above components to an internal mixer and mix them. After standing at room temperature for 20 hours, remix them on an open mixer to finally produce a perfluoroether rubber vulcanizate.

[0093] The preparation method of triallylsilsesquioxane modified vulcanizing agent is as follows:

[0094] In a sealed stirred reactor, 25 kg of triallyl isocyanurate (TAIC, CAS: 1025-16-2), 0.01 kg of trisilanolphenyl-cage polysilsesquioxane (CAS: 444315-26-8), 1 kg of stannous octoate, and 200 kg of toluene were added, and the mixture was stirred at 60° C. for 120 minutes. The toluene was removed by distillation to obtain a triallyl silsesquioxane-modified vulcanizing agent;

[0095] Table 6 Performance test of perfluoroether rubber

[0096]

[0097] It can be seen from the above specific embodiments that the low-temperature resistant perfluoroether rubber prepared by this method has excellent mechanical properties, low-temperature resistance and sulfur transformation properties.

[0098] The applicant declares that the above-described embodiments are used to further illustrate the present invention, but the present invention is not limited to these embodiments. This does not mean that the present invention must rely on these embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for raw materials in the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A preparation method and application of low-temperature resistant high-purity perfluoroether rubber, the operating steps are as follows: S1: Add 300-400 parts of high-purity water to a polymerization kettle in parts by weight, start stirring and add 0.5-2 parts of microemulsion, add 0.25-0.45 parts of comonomers A and B to the above microemulsion, stir at a speed of 30-120 rpm, heat the polymerization kettle while introducing PMVE to a temperature of 80-120°C and a pressure of 1.5-1.8 MPa, then introduce a first mixed gas of PMVE and TFE to a pressure of 3.0-5.0 MPa in the polymerization kettle, add 0.05-0.2 parts of chain transfer agent, 0.02-0.1 parts of vulcanization site monomer, and 0.01-0.1 parts of initiator to initiate copolymerization; S2: After the polymerization reaction starts, a second mixed gas of PMVE and TFE is introduced, and the pressure of the polymerization kettle is maintained at 3.0-5.0 MPa and the temperature is 80-120°C. When the consumption of the second mixed monomer reaches 30-50 parts, the copolymerization reaction is terminated, the polymerization kettle is depressurized and the material is discharged. The obtained elastomer emulsion is coagulated, washed, and dried to obtain perfluoroether rubber; S3: Prepare the following mixing components: (1) 10-12 parts of raw rubber; (2) 0.15-0.18 parts of triallylsilsesquioxane modified curing agent; (3) 0.3-0.5 parts of 2,5-di-tert-butylperoxy-2,5-dimethylethane curing aid; (4) 1.5-2 parts of filler material MT carbon black N9900; (5) 0.5-0.8 parts of processing aid octadecanoic acid, add the above components into an internal mixer and mix, place at room temperature for 20 hours, and then return to the open mixer to finally obtain perfluoroether rubber vulcanizate.

2. The preparation method and application of a low-temperature resistant high-purity perfluoroether rubber according to claim 1, characterized in that: The mass ratio of the microemulsion is emulsifier:polyether oil:water=10:1~1:10~1:

10.

3. The preparation method and application of a low-temperature resistant high-purity perfluoroether rubber according to claim 2, characterized in that: The emulsifier is selected from potassium perfluoropolyether carboxylate, magnesium perfluoropolyether carboxylate, sodium perfluoropolyether carboxylate, and ammonium perfluoropolyether carboxylate; the polyether oil is selected from PFPE, and its structural formula is (—CF2—O—CF2—)n.

4. The preparation method and application of a low-temperature resistant high-purity perfluoroether rubber according to claim 1, characterized in that: The comonomer A is selected from CF3CF2CF2CF2O(CF(CF3)CF2O)nCF=CF2, n=0-6, preferably n=1-3; the comonomer B is selected from CF3CF2O(CF3CF2O)mCF=CF2, m=0-5, preferably m=1-3.

5. The preparation method and application of a low-temperature resistant high-purity perfluoroether rubber according to claim 1, characterized in that: The chain transfer agent is selected from one of iodinated alkanes, alkane compounds, alcohols, fats, and organic halides, including one or more combinations of 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane, 1,3-diiodine-2-chloroperfluoropropane, 1,5-diiodine-2,4-dichloroperfluoropentane, 1,3-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, perfluoroisopropyl iodide, perfluoro-n-butyl iodide, trifluoromethyl iodide, methyl iodide, isopentane, methanol, isopropanol, ethyl acetate, diethyl malonate, CCl4, CBrCl3, CF2BrCFBrCF3 and CF2I2.

6. The preparation method and application of a low-temperature resistant high-purity perfluoroether rubber according to claim 1, characterized in that: The vulcanization site monomer is selected from chlorinated olefins, including one or a combination of trifluoroethylene bromide, 4-bromoperfluoro-1-butene, 1-bromo-2,2-difluoroethylene, 4-bromo-3,3,4,4-tetrafluoro-1-butene, perfluoroalkyl bromide, 4-bromo-1,1,2-trifluoro-1-butene, and 4-bromo-1,1,3,3,4,4-hexafluoro-1-butene.

7. The preparation method and application of a low-temperature resistant high-purity perfluoroether rubber according to claim 1, characterized in that: The initiator is selected from one or a combination of diisopropyl peroxydicarbonate, benzoyl peroxide, cumene peroxide, tert-butyl hydroperoxide, potassium persulfate, and ammonium persulfate.

8. The preparation method and application of a low-temperature resistant high-purity perfluoroether rubber according to claim 1, characterized in that: The molar ratio of PMVE to TFE in the first mixture is 1:1.0-2.0; the molar ratio of PMVE to TFE in the second mixture is 1:1.5-2.0; and the purity of the PMVE and TFE monomers is not less than 99.99%.

9. The preparation method and application of a low-temperature resistant high-purity perfluoroether rubber according to claim 1, characterized in that: The preparation method of the triallylsilsesquioxane modified vulcanizing agent is: In a sealed stirred reactor, 25-50 parts of triallyl isocyanurate (TAIC), 0.5-2.5 parts of 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex, 0.01-0.1 parts of trisilanolphenyl-cage polysilsesquioxane, 1-3 parts of stannous octoate, and 200-300 parts of toluene are added by weight; the mixture is stirred at 60-70°C for 120-180 minutes, and the toluene is removed by distillation to obtain a triallyl silsesquioxane-modified vulcanizing agent.

10. The preparation method and application of low-temperature resistant high-purity perfluoroether rubber according to claim 1, characterized in that: The preparation method of the DL-4-hydroxy-2-ketoglutaric acid / zirconium / lanthanum complex comprises the following steps: adding 16-32 parts of 4,4'-dihydroxy-2,2'-bipyridine, 7-14 parts of zirconium nitrate, 16-32 parts of lanthanum nitrate, and 200-300 parts of water, stirring at 40-50° C. for 100-150 minutes, and removing the water by distillation to obtain the 4,4'-dihydroxy-2,2'-bipyridine / zirconium / lanthanum complex.

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