Preparation method for high-fluorine-content low-compression-set peroxide-cured fluororubber
By using high-pressure reactor polymerization and specific additives, the problem of high compression set of high-fluorine-content peroxide-cured fluororubber was solved, achieving the preparation of high-fluorine-content, low-compression-set, and stable fluororubber suitable for industrial production.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ZHEJIANG JUSHENG FLUOROCHEM
- Filing Date
- 2025-10-16
- Publication Date
- 2026-06-25
AI Technical Summary
Existing high-fluorine-content peroxide-cured fluororubber has a high compression set, which limits its application, and its batch-to-batch stability is poor, making it difficult to meet the requirements of industrial production.
High-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber was synthesized by using a high-pressure reactor polymerization method, adding dispersants, vulcanization point monomers and initiators, and controlling reaction conditions. Triazine, phenyl sulfide and selenium complexes were used to enhance crosslinking density and chain segment rigidity, thereby improving thermal and chemical stability.
The obtained peroxide-cured fluorinated rubber has a stable fluorine content, compression set ≤20%, tensile strength of about 22MPa, elongation at break greater than 180%, and improved thermal stability, making it suitable for industrial production.
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Figure CN2025128246_25062026_PF_FP_ABST
Abstract
Description
A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber
[0001] Cross-reference to related applications
[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202411878652.5, filed on December 19, 2024, the entire contents of which are incorporated herein by reference. Technical Field
[0003] This disclosure relates to the field of fluororubber synthesis, and in particular to a method for preparing high-fluorine-content, low-compression-deflection-peroxide vulcanized fluororubber. Background Technology
[0004] High-fluorine-content peroxide (or free radical) vulcanized fluororubber is obtained by copolymerizing vinylidene fluoride (VDF), tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vulcanization point monomers (CSM, CTA), with a fluorine mass fraction of 69%–71%. In addition to the excellent high-temperature resistance and corrosion resistance characteristic of fluororubber, this type of rubber also exhibits outstanding hot tear resistance, resistance to superheated steam, and resistance to organic media. Peroxide vulcanized fluororubber products possess excellent resistance to hot air aging, methanol, fuel oil, and ozone; however, their excessively high pressure transflectance limits their application. In particular, peroxide vulcanized fluororubber with a fluorine content greater than 69% has a pressure transflectance value of 32–45%, further restricting its application.
[0005] CN202010620629 discloses a method for preparing peroxide-cured fluororubber with low compression set. However, the curing point of this peroxide-cured fluororubber is not well controlled because the addition of curing point monomers will terminate the molecular weight, resulting in a low curing point addition during the reaction process. This leads to a compression set value of about 22%, and poor batch-to-batch stability, which is not conducive to industrial production.
[0006] CN108017746A discloses a method for preparing peroxide-cured fluororubber with high fluorine content and low compression set. However, the vulcanization points of the peroxide-cured fluororubber are unevenly distributed in the chain segments. The vulcanization time is too long or under-curing occurs during processing, resulting in a compression set value of about 25%. Furthermore, the batch-to-batch stability is poor, which is not conducive to industrial production.
[0007] CN1989202A discloses a peroxide-curable fluorinated elastomer composition, which mainly improves the flowability of fluorinated elastomer compositions with shortcomings in production and improves processability. However, the number-average molecular weight of the obtained fluorinated elastomer is only 30,000 to 70,000, the crosslinking density is insufficient, the curing time is too long, resulting in a large compression set value.
[0008] In view of this, this disclosure is hereby made. Summary of the Invention
[0009] This disclosure provides a method for preparing peroxide-cured fluororubber with high fluorine content and low compression set, thereby addressing the problem of excessively high compression set in peroxide-cured fluororubber.
[0010] To achieve the aforementioned objectives, this method proposes the following solution:
[0011] A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps:
[0012] a. In a high-pressure reactor, add 30-50 parts of deoxygenated deionized water, evacuate the reactor, then add 0.025-0.045 parts of dispersant and 0.01-0.03 parts of sulfurization point monomer CTA, stir evenly, heat the reactor to 80-100℃, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 2.0-3.5MPa. Then add 0.01-0.02 parts of initiator to initiate the polymerization reaction;
[0013] b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate.
[0014] c. When the solid content of the emulsion in the reactor reaches 25-35 wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
[0015] As an optional implementation, in step a, the reactor is evacuated until the oxygen content is ≤20ppm.
[0016] As an optional implementation, the dispersant in step a is selected from a selenium-doped trimer dispersant, and the specific steps for its synthesis are as follows:
[0017] T1: Add hexafluoropropylene trimer (molecular weight 150), 2,4,6-tripropenoxy-1,3,5-triazine (molecular weight 249), CAS: 25988-85-6, and 4,4'-dimercaptodiphenyl sulfide (molecular weight 250) to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 60-70℃ for 3-7 hours under nitrogen protection;
[0018] T2: Add diallyl selenium (molecular weight 161) and react at 60-70℃ for 1-3 hours under nitrogen protection to obtain selenium-doped trimer dispersant.
[0019] As an optional implementation, the molar ratio of the hexafluoropropylene trimer: 2,4,6-tripropenoxy-1,3,5-triazine: 4,4'-dimercaptodiphenyl sulfide: tetramethylguanidine: diallyl selenium is 1-1.2: 0.003-0.03: 1.5-2.5: 0.02-0.05: 0.0005-0.005.
[0020] As an optional implementation, the sulfidation point monomer CTA in step a is an iodoalkane, including perfluorobutyl iodide, perfluoropropyl diiodide, and perfluorodiiodoethane.
[0021] As an optional implementation, the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene in step a is (35-55):(15-32.5):(20-32.5).
[0022] As an optional implementation, the initiator in step a is selected from at least one of ammonium persulfate, sodium persulfate, and potassium persulfate.
[0023] As an optional implementation, in step b, the molar ratio of the mixed monomers of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is (35-55):(15-32.5):(20-32.5).
[0024] As an optional implementation, the sulfurization point monomer CSM in step b is selected from at least one of trifluorobromoethylene, difluorobromoethylene, trifluoroiodoethylene, perfluoroiodoalkyl vinyl ether, perfluorobromoalkyl vinyl ether, and 3,3,4,4-tetrafluoro-4-bromobut-1-ene.
[0025] Reaction mechanism:
[0026] 1. Effect of triazine: The nitrogen atom in the triazine structure can form NC bonds with the carbon cations in the polymer, which can enhance the crosslinking density and improve thermal stability.
[0027] 2. The role of phenyl sulfide: The sulfur atoms in phenyl sulfide form a weak FS interaction with the fluorine atoms in the polymer, which increases the rigidity of the polymer chain and improves the heat resistance.
[0028] 3. Contribution of selenium complexes: Selenium complexes act as catalysts or co-catalysts in polymerization reactions, accelerating the reaction and further functionalizing polymers by forming chemical bonds such as SeC.
[0029] Technical effects:
[0030] 1. Improved thermal stability: The additional crosslinking points provided by triazine, the increased segment rigidity of phenyl sulfide, and the catalytic effect of selenium complexes all contribute to improving the thermal stability of the polymer.
[0031] 2. Enhanced chemical stability: These functional groups work together through different mechanisms to protect the polymer backbone from chemical erosion, enabling it to maintain the integrity of its physical and chemical properties even under extreme conditions.
[0032] 3. The peroxide-cured fluororubber prepared by the method provided in this disclosure has a stable fluorine content of 70-71%, a stable compression set of ≤20%, a tensile strength of about 22 MPa, and an elongation at break of greater than 180%. Attached Figure Description
[0033] Figure 1 shows the TGA spectrum of the peroxide-cured fluororubber prepared in Example 1;
[0034] Figure 2 shows the TGA spectrum of the peroxide-cured fluororubber prepared in Example 2;
[0035] Figure 3 shows the solid-state NMR spectrum of the peroxide-cured fluororubber prepared in Example 1. Detailed Implementation
[0036] Embodiments of this disclosure are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting it.
[0037] Example 1
[0038] A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps:
[0039] a. In a high-pressure reactor, add 3 kg of deoxygenated deionized water, evacuate the reactor, then add 0.025 kg of dispersant and 0.01 kg of sulfurization point monomer CTA, stir evenly, heat the reactor to 100°C, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 2.0 MPa. Then add 0.01 kg of initiator to initiate the polymerization reaction.
[0040] b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate.
[0041] c. When the solid content of the emulsion in the reactor reaches 25wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
[0042] In step a, the reactor is evacuated until the oxygen content is ≤20ppm.
[0043] In step a, the dispersant is selected from selenium-doped trimer dispersants, and the specific steps of their synthesis are as follows:
[0044] T1: Add hexafluoropropylene trimer (molecular weight 150), 2,4,6-tripropenoxy-1,3,5-triazine (molecular weight 249), CAS: 25988-85-6, and 4,4'-dimercaptodiphenyl sulfide (molecular weight 250) to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 60°C for 3 hours under nitrogen protection;
[0045] T2: Add diallyl selenium (molecular weight 161) and react at 60°C for 1 hour under nitrogen protection to obtain selenium-doped trimer dispersant.
[0046] The molar ratio of the hexafluoropropylene trimer: 2,4,6-tripropenoxy-1,3,5-triazine: 4,4'-dimercaptodiphenyl sulfide: tetramethylguanidine: diallyl selenium is 1:0.003:1.5:0.02:0.0005.
[0047] In step a, the sulfidation point monomer CTA is an iodoalkane selected from perfluorobutyl iodide.
[0048] In step a, the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is 35:32.5:32.5.
[0049] In step a, the initiator is selected from ammonium persulfate.
[0050] In step b, the molar ratio of the mixed monomers vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene is 35:32.5:32.5.
[0051] In step b, the sulfurization point monomer CSM is selected from trifluorobromoethylene.
[0052] Example 2
[0053] A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps:
[0054] a. In a high-pressure reactor, add 40 kg of deoxygenated deionized water, evacuate the reactor, then add 0.035 kg of dispersant and 0.02 kg of sulfurization point monomer CTA, stir evenly, heat the reactor to 90°C, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 2.5 MPa. Then add 0.01 kg of initiator to initiate the polymerization reaction.
[0055] b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate.
[0056] c. When the solid content of the emulsion in the reactor reaches 30wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
[0057] In step a, the reactor is evacuated until the oxygen content is ≤20ppm.
[0058] In step a, the dispersant is selected from selenium-doped trimer dispersants, and the specific steps of their synthesis are as follows:
[0059] T1: Add hexafluoropropylene trimer (molecular weight 150), 2,4,6-tripropenoxy-1,3,5-triazine (molecular weight 249), CAS: 25988-85-6, and 4,4'-dimercaptodiphenyl sulfide (molecular weight 250) to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 65°C for 5 hours under nitrogen protection;
[0060] T2: Add diallyl selenium (molecular weight 161) and react at 65°C for 2 hours under nitrogen protection to obtain selenium-doped trimer dispersant.
[0061] The molar ratio of the hexafluoropropylene trimer: 2,4,6-tripropenoxy-1,3,5-triazine: 4,4'-dimercaptodiphenyl sulfide: tetramethylguanidine: diallyl selenium is 1.1:0.01:2:0.02:0.001.
[0062] In step a, the sulfidation point monomer CTA is an iodoalkane selected from perfluoropropyl diiodide.
[0063] In step a, the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is 40:30:30.
[0064] In step a, the initiator is selected from sodium persulfate.
[0065] In step b, the molar ratio of the mixed monomers vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene is 40:30:30.
[0066] In step b, the sulfurization point monomer CSM is selected from difluoroethylene bromide.
[0067] Example 3
[0068] A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps:
[0069] a. In a high-pressure reactor, add 40 kg of deoxygenated deionized water, evacuate the reactor, then add 0.035 kg of dispersant and 0.02 kg of sulfurization point monomer CTA, stir evenly, heat the reactor to 90°C, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 3 MPa. Then add 0.02 kg of initiator to initiate the polymerization reaction.
[0070] b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate.
[0071] c. When the solid content of the emulsion in the reactor reaches 30wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
[0072] In step a, the reactor is evacuated until the oxygen content is ≤20ppm.
[0073] In step a, the dispersant is selected from selenium-doped trimer dispersants, and the specific steps of their synthesis are as follows:
[0074] T1: Add hexafluoropropylene trimer (molecular weight 150), 2,4,6-tripropenoxy-1,3,5-triazine (molecular weight 249), CAS: 25988-85-6, and 4,4'-dimercaptodiphenyl sulfide (molecular weight 250) to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 65°C for 5 hours under nitrogen protection;
[0075] T2: Add diallyl selenium (molecular weight 161) and react at 65°C for 2 hours under nitrogen protection to obtain selenium-doped trimer dispersant.
[0076] The molar ratio of the hexafluoropropylene trimer: 2,4,6-tripropenoxy-1,3,5-triazine: 4,4'-dimercaptodiphenyl sulfide: tetramethylguanidine: diallyl selenium is 1.1:0.02:2:0.03:0.003.
[0077] In step a, the sulfidation point monomer CTA is an iodoalkane selected from perfluoropropyl diiodide.
[0078] In step a, the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is 45:25:30.
[0079] In step a, the initiator is selected from sodium persulfate.
[0080] In step b, the molar ratio of the mixed monomers vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene is 45:25:30.
[0081] In step b, the sulfurization point monomer CSM is selected from trifluoroiodide.
[0082] Example 4
[0083] A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps:
[0084] a. In a high-pressure reactor, add 50 kg of deoxygenated deionized water, evacuate the reactor, then add 0.045 kg of dispersant and 0.03 kg of sulfurization point monomer CTA, stir evenly, heat the reactor to 100°C, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 3.5 MPa. Then add 0.02 kg of initiator to initiate the polymerization reaction.
[0085] b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate.
[0086] c. When the solid content of the emulsion in the reactor reaches 35wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
[0087] In step a, the reactor is evacuated until the oxygen content is ≤20ppm.
[0088] In step a, the dispersant is selected from selenium-doped trimer dispersants, and the specific steps of their synthesis are as follows:
[0089] T1: Add hexafluoropropylene trimer (molecular weight 150), 2,4,6-tripropenoxy-1,3,5-triazine (molecular weight 249), CAS: 25988-85-6, and 4,4'-dimercaptodiphenyl sulfide (molecular weight 250) to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 70°C for 7 hours under nitrogen protection;
[0090] T2: Add diallyl selenium (molecular weight 161) and react at 70°C for 3 hours under nitrogen protection to obtain selenium-doped trimer dispersant.
[0091] The molar ratio of the hexafluoropropylene trimer: 2,4,6-tripropenoxy-1,3,5-triazine: 4,4'-dimercaptodiphenyl sulfide: tetramethylguanidine: diallyl selenium is 1.2:0.03:2.5:0.05:0.005.
[0092] In step a, the sulfidation point monomer CTA is an iodoalkane, including perfluorodiiodoethane.
[0093] In step a, the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is 45:32.5:22.5.
[0094] In step a, the initiator is selected from potassium persulfate.
[0095] In step b, the molar ratio of the mixed monomers vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene is 45:32.5:22.5.
[0096] In step b, the sulfidation point monomer CSM is selected from perfluorobromoalkyl vinyl ethers.
[0097] Comparative Example 1
[0098] A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps:
[0099] a. In a high-pressure reactor, add 3 kg of deoxygenated deionized water, evacuate the reactor, then add 0.025 kg of dispersant and 0.01 kg of sulfurization point monomer CTA, stir evenly, heat the reactor to 100°C, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 2.0 MPa. Then add 0.01 kg of initiator to initiate the polymerization reaction.
[0100] b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate.
[0101] c. When the solid content of the emulsion in the reactor reaches 25wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
[0102] In step a, the reactor is evacuated until the oxygen content is ≤20ppm.
[0103] In step a, the dispersant is selected from selenium-doped trimer dispersants, and the specific steps of their synthesis are as follows:
[0104] T1: Add hexafluoropropylene trimer (molecular weight 150), 2,4,6-tripropenoxy-1,3,5-triazine (molecular weight 249), CAS: 25988-85-6, and 4,4'-dimercaptodiphenyl sulfide (molecular weight 250) to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 60°C for 3 hours under nitrogen protection;
[0105] T2: Add diallyl selenium (molecular weight 161) and react at 60°C for 1 hour under nitrogen protection to obtain selenium-doped trimer dispersant.
[0106] The molar ratio of hexafluoropropylene trimer: 4,4'-dimercaptodiphenyl sulfide: tetramethylguanidine: diallyl selenium is 1:1.5:0.02:0.0005.
[0107] In step a, the sulfidation point monomer CTA is an iodoalkane selected from perfluorobutyl iodide.
[0108] In step a, the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is 35:32.5:32.5.
[0109] In step a, the initiator is selected from ammonium persulfate.
[0110] In step b, the molar ratio of the mixed monomers vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene is 35:32.5:32.5.
[0111] In step b, the sulfurization point monomer CSM is selected from trifluorobromoethylene.
[0112] Comparative Example 2
[0113] A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps:
[0114] a. In a high-pressure reactor, add 3 kg of deoxygenated deionized water, evacuate the reactor, then add 0.025 kg of dispersant and 0.01 kg of sulfurization point monomer CTA, stir evenly, heat the reactor to 100°C, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 2.0 MPa. Then add 0.01 kg of initiator to initiate the polymerization reaction.
[0115] b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate.
[0116] c. When the solid content of the emulsion in the reactor reaches 25wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
[0117] In step a, the reactor is evacuated until the oxygen content is ≤20ppm.
[0118] In step a, the dispersant is selected from selenium-doped trimer dispersants, and the specific steps of their synthesis are as follows:
[0119] T1: Add hexafluoropropylene trimer (molecular weight 150), 2,4,6-tripropenoxy-1,3,5-triazine (molecular weight 249), CAS: 25988-85-6, and 4,4'-dimercaptodiphenyl sulfide (molecular weight 250) to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 60°C for 3 hours under nitrogen protection;
[0120] T2: Add diallyl selenium (molecular weight 161) and react at 60°C for 1 hour under nitrogen protection to obtain selenium-doped trimer dispersant.
[0121] The molar ratio of the hexafluoropropylene trimer: 2,4,6-tripropenoxy-1,3,5-triazine: tetramethylguanidine: diallyl selenium is 1:0.003:0.02:0.0005.
[0122] In step a, the sulfidation point monomer CTA is an iodoalkane selected from perfluorobutyl iodide.
[0123] In step a, the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is 35:32.5:32.5.
[0124] In step a, the initiator is selected from ammonium persulfate.
[0125] In step b, the molar ratio of the mixed monomers vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene is 35:32.5:32.5.
[0126] In step b, the sulfurization point monomer CSM is selected from trifluorobromoethylene.
[0127] Comparative Example 3
[0128] A method for preparing high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps:
[0129] a. In a high-pressure reactor, add 3 kg of deoxygenated deionized water, evacuate the reactor, then add 0.025 kg of dispersant and 0.01 kg of sulfurization point monomer CTA, stir evenly, heat the reactor to 100°C, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 2.0 MPa. Then add 0.01 kg of initiator to initiate the polymerization reaction.
[0130] b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate.
[0131] c. When the solid content of the emulsion in the reactor reaches 25wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
[0132] In step a, the reactor is evacuated until the oxygen content is ≤20ppm.
[0133] In step a, the dispersant is selected from selenium-doped trimer dispersants, and the specific steps of their synthesis are as follows:
[0134] T1: Add hexafluoropropylene trimer (molecular weight 150), 2,4,6-tripropenoxy-1,3,5-triazine (molecular weight 249), CAS: 25988-85-6, and 4,4'-dimercaptodiphenyl sulfide (molecular weight 250) to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 60°C for 3 hours under nitrogen protection;
[0135] T2: Add diallyl selenium (molecular weight 161) and react at 60°C for 1 hour under nitrogen protection to obtain selenium-doped trimer dispersant.
[0136] The molar ratio of the hexafluoropropylene trimer: 2,4,6-tripropenoxy-1,3,5-triazine: 4,4'-dimercaptodiphenyl sulfide: tetramethylguanidine is 1:0.003:1.5:0.02.
[0137] In step a, the sulfidation point monomer CTA is an iodoalkane selected from perfluorobutyl iodide.
[0138] In step a, the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is 35:32.5:32.5.
[0139] In step a, the initiator is selected from ammonium persulfate.
[0140] In step b, the molar ratio of the mixed monomers vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene is 35:32.5:32.5.
[0141] In step b, the sulfurization point monomer CSM is selected from trifluorobromoethylene.
[0142] Example Evaluation:
[0143] 1. Fluorine content determination
[0144] Weigh an appropriate amount of vulcanized fluororubber sample, crush it, and mix it evenly.
[0145] The oxygen bomb combustion method (oxygen bomb combustion coulometric meter) is adopted, and the specific steps are as follows:
[0146] 1) Place the rubber sample into an oxygen bomb and burn it in a high-pressure oxygen environment.
[0147] 2) The combustion products are absorbed by the absorbent.
[0148] 2. Compression deformation measurement
[0149] Prepare standard-sized rubber samples, typically cylindrical (12.5 mm in diameter and 6.3 mm in height).
[0150] The test was conducted at 70°C.
[0151] 1) Place the sample in a compression device and keep it at a compression rate of 25% for 24 hours.
[0152] 2) After the test, remove the sample from the compression device and allow it to return to room temperature for 30 minutes.
[0153] 3) Measure the height after restoration.
[0154] 3. Tensile strength determination
[0155] Prepare standard dumbbell-shaped rubber specimens with dimensions conforming to GB / T 528-2009 (ISO 37:2005) standard.
[0156] The test was conducted at room temperature.
[0157] 1) Use a universal testing machine to conduct a tensile test at a constant tensile speed (e.g., 500 mm / min).
[0158] 2) Record the maximum tensile force of the specimen.
[0159] 4. Determination of elongation at break
[0160] The same dumbbell-shaped rubber specimen as used in the tensile strength test.
[0161] The test was conducted at room temperature.
[0162] 1) Using a universal testing machine, continue stretching until the specimen breaks.
[0163] 2) Record the elongation at break of the specimen.
[0164] 5. Thermal stability test
[0165] Thermogravimetric analysis (TGA)
[0166] 1) Take an appropriate amount of vulcanized fluororubber sample and make it into a suitable size so that it can be placed in the thermogravimetric analyzer.
[0167] 2) Place the sample in the thermogravimetric analyzer, set the temperature range from room temperature to 600℃, and the heating rate is 10℃ / min. Test results:
[0168] The excellent performance of the peroxide-cured fluororubber provided in this disclosure can be comprehensively evaluated through the detailed testing methods described above.
[0169] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.
Claims
1. A method for preparing a high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber, comprising the following steps: a. In a high-pressure reactor, add 30-50 parts of deoxygenated deionized water, evacuate the reactor, then add 0.025-0.045 parts of dispersant and 0.01-0.03 parts of sulfurization point monomer CTA, stir evenly, heat the reactor to 80-100℃, and introduce a mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene to make the pressure inside the reactor 2.0-3.5MPa. Then add 0.01-0.02 parts of initiator to initiate the polymerization reaction; b. After the polymerization reaction proceeds, the pressure in the reactor is kept constant by adding mixed monomers 2 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. When the total amount of mixed monomers is added to 5%, the sulfurization point monomers CTA and CSM are added continuously at a constant flow rate. c. When the solid content of the emulsion in the reactor reaches 25-35 wt%, the polymerization reaction is terminated, unreacted monomers are recovered, the emulsion is discharged into a coagulation tank, and after coagulation and drying, peroxide vulcanized fluororubber is obtained.
2. The method for preparing high-fluorine-content, low-compression-deflection-weighted peroxide vulcanized fluororubber according to claim 1, wherein in step a, the reaction vessel is evacuated until the oxygen content is ≤20ppm.
3. The method for preparing a high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber according to claim 1 or 2, wherein the dispersant in step a is selected from a selenium-doped trimer dispersant, and the specific steps of its synthesis are as follows: T1: Add hexafluoropropylene trimer, 2,4,6-tripropenoxy-1,3,5-triazine, and 4,4'-dimercaptodiphenyl sulfide to a sealed reactor in proportion, purge with nitrogen, add tetramethylguanidine while stirring, and react at 60-70°C for 3-7 hours under nitrogen protection. T2: Add diallyl selenium and react at 60-70℃ for 1-3 hours under nitrogen protection to obtain selenium-doped trimer dispersant.
4. The method for preparing a high-fluorine-content, low-compression-deflection-peroxide vulcanized fluororubber according to claim 3, wherein the molar ratio of hexafluoropropylene trimer: 2,4,6-tripropyleneoxy-1,3,5-triazine: 4,4'-dimercaptodiphenyl sulfide: tetramethylguanidine: diallyl selenium is 1-1.2: 0.003-0.03: 1.5-2.5: 0.02-0.05: 0.0005-0.
005.
5. A method for preparing a high-fluorine-content, low-compression-deflection-weighted peroxide vulcanized fluororubber according to any one of claims 1-4, wherein the vulcanization point monomer CTA in step a is an iodoalkane, including perfluorobutyl iodide, perfluoropropyl diiodide, and perfluorodiiodoethane.
6. A method for preparing a high-fluorine-content, low-compression-deflection-weighted peroxide vulcanized fluororubber according to any one of claims 1-5, wherein the molar ratio of the mixed monomer 1 of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene in step a is (35-55):(15-32.5):(20-32.5).
7. A method for preparing a high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber according to any one of claims 1-6, wherein the initiator in step a is selected from at least one of ammonium persulfate, sodium persulfate, and potassium persulfate.
8. The method for preparing a high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber according to claim 1, wherein the molar ratio of the mixed monomers vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene in step b is (35-55):(15-32.5):(20-32.5).
9. A method for preparing a high-fluorine-content, low-compression-deflection-weight peroxide vulcanized fluororubber according to claim 1 or 8, wherein the vulcanization point monomer CSM in step b is selected from at least one of trifluorobromoethylene, difluorobromoethylene, trifluoroiodoethylene, perfluoroiodoalkyl vinyl ether, perfluorobromoalkyl vinyl ether, and 3,3,4,4-tetrafluoro-4-bromobut-1-ene.