Green low-temperature-resistant fluororubber, preparation method and use thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 四川道弘新材料股份有限公司
- Filing Date
- 2025-01-09
- Publication Date
- 2026-06-30
AI Technical Summary
Existing fluororubbers have a high brittle temperature at low temperatures, which cannot meet the requirements of certain low-temperature working environments. Furthermore, traditional emulsifiers such as perfluorooctanoic acid and its derivatives are harmful to the environment and cannot meet green and environmentally friendly requirements.
A fluorine-free surfactant was prepared using acid anhydride compounds, fatty alcohol polyoxyethylene ethers, bisulfite and alkaline catalysts, which was then used to prepare fluororubber raw rubber. Low-temperature resistant fluororubber was prepared by batch free radical emulsion polymerization.
The prepared fluororubber exhibits excellent cold resistance at low temperatures, while avoiding the environmental pollution caused by traditional emulsifiers, and possesses good mechanical properties and application prospects.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical production technology, specifically relating to a green low-temperature resistant fluororubber, its preparation method, and its uses. Background Technology
[0002] Type 246 fluororubber is a ternary polymer elastomer copolymerized from vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene in a specific ratio under the action of an emulsifier. Due to its excellent chemical resistance, heat resistance, and physical and mechanical properties, Type 246 fluororubber is widely used in sealing rings, gaskets, oil seals, and other fields. However, the low-temperature resistance of fluororubber typically decreases with increasing fluorine content. The brittle temperature of Type 246 fluororubber is approximately -20°C, which cannot meet the requirements of certain low-temperature working environments. Therefore, the research and development of low-temperature resistant fluororubber has become a hot topic both domestically and internationally.
[0003] As an emulsifier in the production of type 246 fluororubber, perfluorooctanoic acid (PFOA) and its derivatives primarily function to uniformly disperse the primary particles of fluororubber, ensuring the stability of the fluororubber emulsion. They are essential additives for the industrial production of type 246 fluororubber. However, scientists have discovered that PFOA and its derivatives are difficult to degrade in the environment, exhibiting environmental accumulation and negatively impacting the growth and development of organisms. Therefore, the use of these substances in fluoropolymer production is gradually being restricted, making the development of green PFOA alternatives an urgent task for fluoropolymer companies. To reduce PFOA usage, domestic fluororubber manufacturers are researching and developing alternatives, but the application of these substances has not yet been completely eliminated. Existing surfactants use surfactants containing short-chain carbon-fluorine bonds to replace PFOA surfactants, but these surfactants cannot completely avoid environmental hazards, still exhibiting persistent bioaccumulation and long-distance migration, causing serious negative impacts on human health and the environment. Simultaneously, non-fluorinated surfactants may undergo chain transfer during polymerization, leading to a decrease in the molecular weight of the polymer and thus unstable product performance.
[0004] Juhua Group's patent application CN115093500A (application number: 202210802613.1) uses a novel fluorinated surfactant to partially replace PFOA. However, this method uses surfactants with high toxicity, which cannot fully meet environmental friendliness requirements. Surfactants mentioned in US patent documents US5789508, US4025709, US5688884, and US5763552, due to their molecular structure, can affect the product quality of the polymer during the polymerization reaction.
[0005] Therefore, the development of green, low-temperature resistant fluororubber that can be industrially produced is of great research significance. Summary of the Invention
[0006] In order to solve the above-mentioned problems in the prior art, the purpose of this invention is to provide a green low-temperature resistant fluororubber, its preparation method and uses.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] This invention provides a fluorine-free surfactant, which is a product prepared from acid anhydride compounds, fatty alcohol polyoxyethylene ethers, bisulfites and alkaline catalysts.
[0009] Further, the acid anhydride compound is citrate anhydride, 2,3-dimethylmaleic anhydride, 2,3-dichloromaleic anhydride, maleic anhydride, bromomaleic anhydride, or 2,3-dichloromaleic anhydride; the fatty alcohol polyoxyethylene ether is fatty alcohol polyoxyethylene ether AEO-3, fatty alcohol polyoxyethylene ether AEO-7, or fatty alcohol polyoxyethylene ether AEO-9; the bisulfite is sodium bisulfite; the alkaline catalyst is triethylamine; the mass ratio of the acid anhydride compound, fatty alcohol polyoxyethylene ether, bisulfite, and alkaline catalyst is 1:0.5–3:0.5–3:0.1–1; preferably, the mass ratio of the acid anhydride compound, fatty alcohol polyoxyethylene ether, bisulfite, and alkaline catalyst is 1:1.75:1.75:0.3.
[0010] The present invention also provides a method for preparing the above-mentioned fluorine-free surfactant, wherein the method comprises reacting an acid anhydride compound, a fatty alcohol polyoxyethylene ether, and a bisulfite in the presence of an alkaline catalyst.
[0011] Further, the solvent for the reaction is dichloromethane; the reaction conditions are under nitrogen protection; the mass ratio of the solvent to the acid anhydride compound is 1:0.01-0.5; the reaction temperature is 50-80℃; the reaction time is 4-12h; preferably, the mass ratio of the solvent to the acid anhydride compound is 1:0.02; the reaction temperature is 65℃; and the reaction time is 8h.
[0012] The present invention also provides a fluororubber raw rubber, which is a product prepared from the above-mentioned fluorine-free surfactant, fluorinated olefin gaseous monomer, initiator and chain transfer agent as raw materials.
[0013] Further, the fluorinated olefin gaseous monomer is one or a mixture of two or more of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene; the initiator is one or a mixture of two or more of sodium sulfite, sodium phosphate, and ammonium persulfate; the chain transfer agent is an alcohol compound; the mass ratio of the fluorine-free surfactant, the fluorinated olefin gaseous monomer, the initiator, and the chain transfer agent is 1:10-100:0.1-1:0.1-1; preferably, the fluorinated olefin gaseous monomer is a mixture of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene; preferably, the molar ratio of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene in the mixture is 35:45:20; the mass ratio of the fluorine-free surfactant, the fluorinated olefin gaseous monomer, the initiator, and the chain transfer agent is 1:33.33:0.36:0.22.
[0014] The present invention also provides a method for preparing the above-mentioned fluororubber raw rubber, the method comprising the following steps: preparing an aqueous solution of the above-mentioned fluorine-free surfactant, adding it to a reaction vessel, first replacing the air in the reaction vessel with an inert gas, then introducing a fluorinated olefin gaseous monomer, adding an initiator, and carrying out the first step reaction; adding a chain transfer agent, and carrying out the second step reaction to obtain fluororubber raw rubber.
[0015] Further, the pH of the aqueous solution of the fluorine-free surfactant is 3–6.9; the inert gas is nitrogen; the temperature of the first and second steps is 60–100°C; the time of the first step reaction is 0.5–3 h; the time of the second step reaction is 2–8 h; the pressure of the first and second steps is 2–6 MPa; preferably, the pH of the aqueous solution of the fluorine-free surfactant is 5; the temperature of the first and second steps is 75–85°C; the time of the first step reaction is 1.5 h; the time of the second step reaction is 4 h; and the pressure of the first and second steps is 4 MPa.
[0016] The present invention also provides a low-temperature resistant fluororubber, which is a product prepared from the above-mentioned fluororubber raw rubber, vulcanizing agent, accelerator, processing aid and filler as raw materials.
[0017] Further, the vulcanizing agent is triallyl isocyanurate; the accelerator is 2,5-di-tert-butylperoxide-2,5-dimethylethane; the processing aid is an acid scavenger, preferably zinc oxide; the filler is carbon black; the mass ratio of the fluororubber raw rubber, vulcanizing agent, accelerator, processing aid and filler is 70-120:1-10:1-10:5-20:5-20; preferably, the mass ratio of the fluororubber raw rubber, vulcanizing agent, accelerator, processing aid and filler is 95:4:4:9:12.
[0018] This invention also provides the application of the above-mentioned low-temperature resistant fluororubber in low-temperature resistant sealing rings, low-temperature resistant gaskets, and low-temperature resistant oil seal materials.
[0019] The present invention has achieved the following beneficial effects:
[0020] This invention provides a method for preparing green, low-temperature resistant fluororubber raw material. A novel fluorine-free surfactant is used to replace PFOA. The mechanical properties of the 246-type fluororubber prepared by this method are comparable to those of 246-type fluororubber produced using PFOA, while significantly enhancing the low-temperature resistance of the fluororubber. This invention avoids the use of PFOA, which is beneficial for the industrial production of green, low-temperature resistant fluororubber and has promising application prospects.
[0021] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.
[0022] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Detailed Implementation
[0023] The reagents and equipment used in the specific embodiments of this invention are all known products and were obtained by purchasing commercially available products.
[0024] Unless otherwise specified, the parts of raw materials in the specific embodiments of the present invention are parts by mass.
[0025] In this invention, the room temperature is 25±5℃.
[0026] Example 1: Fluorine-free surfactant I and its preparation method
[0027] 20 parts of citrate anhydride compound, 35 parts of fatty alcohol polyoxyethylene ether AEO-9, 35 parts of sodium bisulfite, and 1000 parts of dichloromethane were added to a reactor. Nitrogen gas was introduced, and the temperature was controlled at 65°C under stirring. 6 parts of triethylamine were then added dropwise. After reacting for 8 hours, the dichloromethane was removed by vacuum distillation to obtain the crude product. The crude product was then washed with diethyl ether to obtain fluorine-free surfactant I.
[0028] Example 2: Fluorine-free surfactant II and its preparation method
[0029] The method of Example 1 was followed, except that the citrate anhydride compound in Example 1 was replaced with 2,3-dimethylmaleic anhydride compound to obtain fluorine-free surfactant II.
[0030] Example 3: Fluorine-free surfactant III and its preparation method
[0031] The method of Example 1 was followed, except that the citrate anhydride compound in Example 1 was replaced with 2,3-dichloromaleic anhydride compound to obtain fluorine-free surfactant III.
[0032] Example 4: Fluorine-free surfactant IV and its preparation method
[0033] The method of Example 1 is used, except that the citrate anhydride compound in Example 1 is replaced with maleic anhydride compound to obtain fluorine-free surfactant IV.
[0034] Example 5 Fluororubber Raw Rubber I and its Preparation Method
[0035] Fluororubber was prepared by batch free radical emulsion polymerization in a 50L high-pressure reactor.
[0036] Add 30L of deionized water and a 50g / L aqueous solution of non-fluorinated surfactant I containing 450g of non-fluorinated surfactant I, along with 80g of disodium hydrogen phosphate as a pH adjuster to adjust the pH to 5. First, replace the air in the vapor space of the reactor with nitrogen, then replace it with a mixture of monomers (vinylidene fluoride:tetrafluoroethylene:hexafluoropropylene = 35:45:20, mol%) to reduce the oxygen content to less than 20ppm. Heat the reactor to 85℃. Continue adding the mixture of monomers to the reactor using a diaphragm compressor to increase the pressure to 4.0MPa. Start stirring to thoroughly mix the monomers in the reactor, then add 160g of an initiator aqueous solution (50g / L, potassium persulfate as the initiator) to begin the reaction. During the reaction, continuously add the mixture of monomers (vinylidene fluoride:tetrafluoroethylene:hexafluoropropylene = 60:25:15, mol%) to maintain the reactor pressure at 4.0MPa and the temperature at 75℃. After reacting for 1.5 hours, add 100g of methanol as a chain transfer agent. The reaction continues until the predetermined amount of mixed monomers is 15 kg. After 4 hours of reaction (starting from the addition of the initiator), the reaction is stopped to obtain fluororubber raw rubber I.
[0037] Example 6 Fluororubber Raw Rubber II and its Preparation Method
[0038] The method of Example 5 is used, except that the aqueous solution of non-fluorinated surfactant I in Example 5 is replaced with an aqueous solution of non-fluorinated surfactant II to obtain fluororubber raw rubber II.
[0039] Example 7 Fluororubber raw rubber III and its preparation method
[0040] The method of Example 5 is used, except that the aqueous solution of non-fluorinated surfactant I in Example 5 is replaced with an aqueous solution of non-fluorinated surfactant III to obtain fluororubber raw rubber III.
[0041] Example 8 Fluororubber Raw Rubber IV and its Preparation Method
[0042] The method of Example 5 is used, except that the aqueous solution of non-fluorinated surfactant I in Example 5 is replaced with an aqueous solution of non-fluorinated surfactant IV to obtain fluororubber raw rubber IV.
[0043] Example 9 Low-temperature resistant fluororubber I and its preparation method
[0044] Weigh out 95 parts of fluororubber raw rubber I, 4 parts of vulcanizing agent triallyl isocyanurate TAIC, 4 parts of accelerator 2,5-di-tert-butylperoxide-2,5-dimethylethane, 9 parts of acid scavenger zinc oxide, and 12 parts of filler carbon black MT. Then, at room temperature, perform thin-pass plasticizing three times on a two-roll mill.
[0045] Then, accelerators, acid scavengers, and fillers are added, followed by vulcanizing agents for mixing. The mixing process involves five thin-pass plasticizing cycles on a two-roll mill at room temperature.
[0046] After aging for 16 hours, the material is re-rolled and sheeted to obtain low-temperature resistant fluororubber I. The re-rolling process involves three thin-pass plasticizing cycles on a two-roll mill at room temperature.
[0047] Example 10 Low-temperature resistant fluororubber II and its preparation method
[0048] The method of Example 9 is used, except that the fluororubber raw rubber I in Example 9 is replaced with fluororubber raw rubber II to obtain low-temperature resistant fluororubber II.
[0049] Example 11 Low-temperature resistant fluororubber III and its preparation method
[0050] The method of Example 9 is used, except that the fluororubber raw rubber I in Example 9 is replaced with fluororubber raw rubber III to obtain low-temperature resistant fluororubber III.
[0051] Example 12 Low-temperature resistant fluororubber IV and its preparation method
[0052] The method of Example 9 is used, except that the fluororubber raw rubber I in Example 9 is replaced with fluororubber raw rubber IV to obtain low-temperature resistant fluororubber IV.
[0053] The following experimental examples demonstrate the beneficial effects of the present invention.
[0054] Experiment Example 1: Mechanical Property Testing of Low-Temperature Resistant Fluororubber
[0055] Mechanical performance testing standard: GB / T 528-2009.
[0056] The mechanical properties of fluororubbers I-IV prepared in Examples 9-12 were analyzed using a universal testing machine, and the results are shown in Table 1.
[0057] Table 1 Mechanical properties of fluororubbers I-IV of the present invention
[0058] Hardness / HA Tensile strength / MPa Elongation at break / % Fluororubber I 74 15.8 253 Fluororubber II 72 15.4 245 Fluororubber III 73 16.3 239 Fluororubber IV 72 14.7 235
[0059] As shown in Table 1, the fluororubber of the present invention has good comprehensive mechanical properties, especially the Shore A hardness of fluororubber I is 74HA and the elongation at break is 253%.
[0060] Experiment Example 2: Low-temperature resistance test of fluororubber
[0061] Determination of compressive cold resistance coefficient: HG / T 3866-2008.
[0062] The low-temperature resistance of fluororubbers I-IV prepared in Examples 9-12 was tested at temperatures of -30℃, -35℃, and -40℃, respectively. The results are shown in Table 2.
[0063] Test parameters: The temperature was maintained at low temperature for 5 minutes, the pressure was removed within 10 seconds, and the data was read after 3 minutes of recovery. The formula for calculating the cold-resistant compressibility coefficient k is as follows:
[0064]
[0065] h0 is the original height, h1 is the compressed height, and h2 is the restored height.
[0066] Table 2. Cold-resistant compression coefficients of fluororubbers I-IV of this invention.
[0067]
[0068] As shown in Table 2, the low-temperature compression coefficient of fluororubber I is still 0.37 at -35℃, indicating that it still has good recovery ability at -35℃. Compared with other groups of fluororubber, fluororubber I has better low-temperature resistance.
[0069] In summary, this invention provides a method for preparing green, low-temperature resistant fluororubber raw material. It uses a novel fluorine-free surfactant to replace PFOA. The mechanical properties of the 246-type fluororubber prepared by this method are comparable to those of 246-type fluororubber produced using PFOA, while significantly enhancing the low-temperature resistance of the fluororubber. This invention avoids the use of PFOA, which is beneficial for the industrial production of green, low-temperature resistant fluororubber and has promising application prospects.
Claims
1. A low-temperature resistant fluororubber, characterized in that, The low-temperature resistant fluororubber is prepared from fluororubber raw rubber, vulcanizing agent, accelerator, processing aid and filler as raw materials; the fluororubber raw rubber is prepared from non-fluorinated surfactant and fluorinated substituted olefin gaseous monomer, initiator and chain transfer agent as raw materials; the mass ratio of non-fluorinated surfactant, fluorinated substituted olefin gaseous monomer, initiator and chain transfer agent is 1:(10~100):(0.1~1):(0.1~1); The fluorine-free surfactant is prepared from citrate anhydride, fatty alcohol polyoxyethylene ether, bisulfite and alkaline catalyst as raw materials; the mass ratio of citrate anhydride, fatty alcohol polyoxyethylene ether, bisulfite and alkaline catalyst is 1:(0.5~3):(0.5~3):(0.1~1).
2. The low-temperature resistant fluororubber according to claim 1, characterized in that, The bisulfite is sodium bisulfite, and the alkaline catalyst is triethylamine; the mass ratio of citralic anhydride, fatty alcohol polyoxyethylene ether, bisulfite, and alkaline catalyst is 1:1.75:1.75:0.
3.
3. The low-temperature resistant fluororubber according to claim 1, characterized in that, The fluorinated olefin gaseous monomer is one or a mixture of two or more of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene; the initiator is one or a mixture of two or more of sodium sulfite, sodium phosphate, and ammonium persulfate; and the chain transfer agent is an alcohol compound.
4. The low-temperature resistant fluororubber according to claim 3, characterized in that, The fluorinated olefin gaseous monomer is a mixture of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene; the mass ratio of the fluorine-free surfactant, the fluorinated olefin gaseous monomer, the initiator and the chain transfer agent is 1:33.33:0.36:0.
22.
5. The low-temperature resistant fluororubber according to claim 1, characterized in that, The vulcanizing agent is triallyl isocyanurate, the accelerator is 2,5-di-tert-butylperoxide-2,5-dimethylethane, the processing aid is zinc oxide, and the filler is carbon black; the mass ratio of the fluororubber raw rubber, vulcanizing agent, accelerator, processing aid and filler is (70~120):(1~10):(1~10):(5~20):(5~20).
6. The low-temperature resistant fluororubber according to claim 5, characterized in that, The mass ratio of the fluororubber raw rubber, vulcanizing agent, accelerator, processing aid and filler is 95:4:4:9:
12.
7. The application of the low-temperature resistant fluororubber according to any one of claims 1 to 6 in low-temperature resistant sealing rings, low-temperature resistant gaskets, and low-temperature resistant oil seal materials.