Fluororubber prepared using a fluorine-free surface activation and a method for preparing the same

Abstract

The application belongs to the technical field of fluororubber materials, and particularly relates to fluororubber prepared by using fluorine-free surface active agent and a preparation method thereof. The method for preparing fluororubber by using fluorine-free surface active agent comprises the following steps: adding fluorine-free surface active agent, molecular weight regulator, mixed monomer, initiator and water into a reaction kettle to perform copolymerization; adding mixed monomer and molecular weight regulator into the reaction kettle to continue the copolymerization, so as to obtain fluororubber raw rubber; mixing the fluororubber raw rubber and vulcanizing agent to perform vulcanization treatment, so as to obtain the fluororubber; the mixed monomer comprises vinylidene fluoride, perfluoropropylene and tetrafluoroethylene with a molar ratio of 35-55:20-33:20-32. In the preparation process of the fluororubber, the fluorine-free surface active agent is used to replace the fluorine-containing surface active agent, so that the problem of fluororubber PFAS exceeding the standard is solved, the content of 470 PFAS indicators in the obtained fluororubber product does not exceed the standard (≤250 ppb), the international strict regulations such as EU REACH, POPs and PPWR are met, and the fluororubber can smoothly enter the overseas market.

Description

Technical Field

[0001] This application belongs to the field of fluororubber materials technology, specifically relating to a fluororubber prepared using fluorine-free surfactants and its preparation method. Background Technology

[0002] Fluororubber, with its excellent comprehensive properties, is widely used in automobiles, aerospace, new energy lithium batteries, smart wearables, and high-end sealing fields. However, international regulations on perfluorinated and polyfluoroalkyl substances (PFAS) are becoming increasingly stringent. The EU's REACH regulation and POPs regulation have successively introduced PFAS limit standards, and many stringent PFAS content limits will be officially implemented from 2026. The global fluororubber industry's upgrade towards fluorine-free surfactants has become an inevitable trend, and the research and development and production of fluorine-free surfactant fluororubber has become the core development direction of the industry.

[0003] Traditional fluororubber production mainly uses fluorinated surfactants, which fall under the category of PFAS. This can easily lead to excessive PFAS levels in the products, failing to meet international regulatory requirements. If fluorinated surfactants are directly replaced, problems such as decreased product performance, poor production process stability, and cross-contamination of the system can still result in excessive PFAS levels. Furthermore, existing fluorinated surfactant-free fluororubber preparation processes suffer from immature formulations and mismatched post-processing parameters.

[0004] Therefore, there is an urgent need to develop a method for preparing fluororubber without fluorine surfactants. This method should completely replace fluorine-containing surfactants, ensuring that the core properties of the product, such as tensile strength, elongation at break, hardness, and compression set, are comparable to or better than those of traditional products. At the same time, it should solve the problem of cross-contamination in the production system, achieving undetectable levels of all 671 PFAS test indicators. Furthermore, it should be compatible with existing industrial production lines, enabling stable and continuous production, and controlling production costs to be on par with traditional products. Summary of the Invention

[0005] This application provides a fluororubber prepared using fluorine-free surfactants and its preparation method, aiming to solve the problems of excessive PFAS in traditional fluorine-containing surfactant fluororubber products, which cannot meet international regulatory requirements; and the poor stability and decreased core properties (tensile strength and elongation at break) of existing fluororubber prepared using fluorine-free surfactants.

[0006] The first aspect of this application provides a method for preparing fluororubber using fluorine-free surfactants, comprising the following steps: (1) Add non-fluorinated surfactant, molecular weight regulator, mixed monomers, initiator and water to the reactor to carry out copolymerization reaction; (2) Add mixed monomers and molecular weight regulators to the reactor and continue the copolymerization reaction to obtain fluororubber raw rubber; (3) The fluororubber raw rubber and the vulcanizing agent are mixed and vulcanized to obtain the fluororubber; The mixed monomers include vinylidene fluoride, perfluoropropylene, and tetrafluoroethylene in a molar ratio of 35-55:20-33:20-32.

[0007] According to some embodiments of the preparation method described in this application, in step (1), the fluorine-free surfactant has the structural formula C8H. 17 -C6H4-O-(CH2CH2O)nH, where n takes the value 7≤n≤30.

[0008] According to some embodiments of the preparation method described in this application, the fluorine-free surfactant has the structural formula C8H. 17 -C6H4-O-(CH2CH2O)nH, where n takes the value 4≤n≤13.

[0009] According to some embodiments of the preparation method described in this application, the fluorine-free surfactant includes one or more of octylphenol polyoxyethylene ether OP-7, octylphenol polyoxyethylene ether OP-9, octylphenol polyoxyethylene ether OP-10, and octylphenol polyoxyethylene ether OP-13.

[0010] According to some embodiments of the preparation method described in this application, the molecular weight regulator includes alkane molecular weight regulators and / or ester molecular weight regulators.

[0011] According to some embodiments of the preparation method described in this application, the initiator includes one or more of potassium persulfate, tert-butyl hydroperoxide, tert-butyl peroxide, peracetic acid, and potassium perchlorate.

[0012] According to some embodiments of the preparation method described in this application, the vulcanizing agent includes 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triallyl isocyanurate, and semi-reinforcing carbon black.

[0013] According to some embodiments of the preparation method described in this application, the alkane molecular weight regulator includes one or more of n-pentane, isopentane, n-hexane, cyclohexane, n-heptane, n-octane, isoheptane, and isooctane.

[0014] According to some embodiments of the preparation method described in this application, the ester molecular weight regulator includes one or more of isooctyl mercaptoacetate, isooctyl 3-mercaptopropionate, ethyl mercaptoacetate, butyl acetate, and dibutyl phthalate.

[0015] According to some embodiments of the preparation method described in this application, in step (1), the mass ratio of the fluorine-free surfactant, molecular weight regulator, mixed monomer, initiator and water is (10-50):(0-10):(230-280):(0.2-2):(2400-3000).

[0016] According to some embodiments of the preparation method described in this application, in step (1), the temperature of the copolymerization reaction is 50-95℃, the pressure is 1.0-3.0MPa, and the time is 100-200min.

[0017] According to some embodiments of the preparation method described in this application, in step (2), the amount of mixed monomers added is 3-5 times the amount of mixed monomers added in step (1).

[0018] According to some embodiments of the preparation method described in this application, the mass ratio of the mixed monomer and the molecular weight regulator added in step (2) is 100:(0.1-1).

[0019] According to some embodiments of the preparation method described in this application, in step (2), the temperature of the copolymerization reaction is 50-95℃, the pressure is 1.0-3.0MPa, and the time is 2-4h.

[0020] According to some embodiments of the preparation method described in this application, in step (3), the mass ratio of the fluororubber raw rubber to the vulcanizing agent is 100:(38-46).

[0021] According to some embodiments of the preparation method described in this application, the mass ratio of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triallyl isocyanurate, and semi-reinforcing carbon black in the vulcanizing agent is 2.5-3.0:6.0-8.0:30-35.

[0022] According to some embodiments of the preparation method described in this application, the vulcanization treatment is carried out at a temperature of 190-230°C for 8-16 hours.

[0023] According to some embodiments of the preparation method described in this application, the copolymerization product of step (1) is subjected to electrolyte coagulation treatment, then washed and dried to obtain fluororubber raw rubber.

[0024] According to some embodiments of the preparation method described in this application, the washing includes washing with deionized water.

[0025] According to some embodiments of the preparation method described in this application, preferably, the drying temperature is 120-150°C and the time is 8-10 hours.

[0026] The second aspect of this application provides a fluororubber prepared by the method described in the first aspect of this application.

[0027] The beneficial effects of this application include: the use of fluorine-free surfactants to replace fluorine-containing surfactants in the preparation process of fluororubber in this application solves the problem of excessive PFAS in fluororubber. The 470 PFAS content indicators in the obtained fluororubber product do not exceed the standard (≤250ppb), meet the stringent international regulations such as EU REACH, POPs, and PPWR, and can be successfully entered into overseas markets.

[0028] The fluororubber described in this application has good product performance, with tensile strength ≥20MPa, elongation at break ≥150%, compression set ≤20%, and hardness (Shore A) 60-80. All properties meet and exceed industry quality control standards. Detailed Implementation

[0029] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0031] This application provides a method for preparing fluororubber using fluorine-free surfactants, including the following steps: (1) Add non-fluorinated surfactant, molecular weight regulator, mixed monomers, initiator and water to the reactor to carry out copolymerization reaction; (2) Add mixed monomers and molecular weight regulators to the reactor and continue the copolymerization reaction to obtain fluororubber raw rubber; (3) The fluororubber raw rubber and the vulcanizing agent are mixed and vulcanized to obtain the fluororubber; The mixed monomers include vinylidene fluoride, perfluoropropylene, and tetrafluoroethylene in a molar ratio of 35-55:20-33:20-32.

[0032] The surfactant used in the fluororubber described in this application is a fluorine-free surfactant (hydrocarbon surfactant). The hydrophobic end of this type of surfactant is an octylphenol group (C8 alkyl chain), which has good compatibility with the fluororubber matrix (bromine / iodine type FKM); the hydrophilic end is a polyoxyethylene ether segment, which can combine with the hydroxyl and polar groups on the surface of powder fillers (such as N990 carbon black), metal oxides (highly active MgO) and vulcanizing auxiliaries (BIPB, TAIC) through hydrogen bonds to form a stable adsorption-dispersion layer.

[0033] In some embodiments of this application, in step (1), the fluorine-free surfactant has the structural formula C8H. 17 -C6H4-O-(CH2CH2O)nH, where n takes the value 7≤n≤30.

[0034] In some embodiments of this application, the fluorine-free surfactant has the structural formula C8H. 17 -C6H4-O-(CH2CH2O)nH, where n takes the value 4≤n≤13.

[0035] In some embodiments of this application, the fluorine-free surfactant includes one or more of octylphenol polyoxyethylene ether OP-7, octylphenol polyoxyethylene ether OP-9, octylphenol polyoxyethylene ether OP-10, and octylphenol polyoxyethylene ether OP-13.

[0036] In some embodiments of this application, the molecular weight regulator includes alkane molecular weight regulators and / or ester molecular weight regulators.

[0037] In some embodiments of this application, the initiator includes one or more of potassium persulfate, tert-butyl hydroperoxide, tert-butyl peroxide, peracetic acid, and potassium perchlorate.

[0038] In some embodiments of this application, the vulcanizing agent includes 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triallyl isocyanurate, and semi-reinforcing carbon black.

[0039] In some embodiments of this application, the alkane molecular weight regulator includes one or more of n-pentane, isopentane, n-hexane, cyclohexane, n-heptane, n-octane, isoheptane, and isooctane.

[0040] In some embodiments of this application, the ester molecular weight regulator includes one or more of isooctyl mercaptoacetate, isooctyl 3-mercaptopropionate, ethyl mercaptoacetate, butyl acetate, and dibutyl phthalate.

[0041] In some embodiments of this application, in step (1), the mass ratio of the fluorine-free surfactant, molecular weight regulator, mixed monomer, initiator and water is (10-50):(0-10):(230-280):(0.2-2):(2400-3000).

[0042] In some embodiments of this application, in step (1), the temperature of the copolymerization reaction is 50-95°C, such as 50°C, 55°C, 60°C, 70°C, 80°C, 90°C, 95°C, etc., the pressure is 1.0-3.0 MPa, such as 1.0 MPa, 1.5 MPa, 2.0 MPa, 2.6 MPa, 3.0 MPa, etc., and the time is 100-200 min, such as 100 min, 120 min, 150 min, 200 min, etc.

[0043] In some embodiments of this application, in step (2), the amount of mixed monomer added is 3-5 times that of the amount of mixed monomer added in step (1), for example, 3 times, 3.5 times, 4 times, 4.3 times, 5 times, etc.

[0044] In some embodiments of this application, the mass ratio of the mixed monomer and the molecular weight regulator added in step (2) is 100:(0.1-1); for example, 100:0.1, 100:0.2, 100:0.5, 100:0.8, 100:1, etc.

[0045] In some embodiments of this application, in step (2), the temperature of the copolymerization reaction is 50-95°C, such as 50°C, 55°C, 60°C, 70°C, 80°C, 90°C, 95°C, etc., the pressure is 1.0-3.0 MPa, and the time is 2-4 h, such as 2 h, 2.5 h, 3 h, 4 h, etc.

[0046] In some embodiments of this application, in step (3), the mass ratio of the fluororubber raw rubber to the vulcanizing agent is 100:(38-46); for example, 100:38, 100:40, 100:43, 100:45, 100:46, etc.

[0047] In some embodiments of this application, the mass ratio of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triallyl isocyanurate, and semi-reinforcing carbon black in the vulcanizing agent is 2.5-3.0: 6.0-8.0: 30-35; In some embodiments of this application, the temperature of the vulcanization treatment is 190-230℃, such as 190℃, 200℃, 210℃, 230℃, etc., and the time is 8-16h, such as 8h, 9h, 10h, 12h, 16h, etc.

[0048] In some embodiments of this application, the copolymerization product of step (1) is subjected to electrolyte coagulation treatment, then washed and dried to obtain fluororubber raw rubber.

[0049] In some embodiments of this application, the washing includes washing with deionized water; In some embodiments of this application, the drying temperature is 120-150°C, such as 120°C, 130°C, 140°C, 150°C, etc., and the time is 8-10h, such as 8h, 8.5h, 9h, 10h, etc.

[0050] This application also provides a fluororubber prepared by the method described in the first aspect of this application. The fluororubber product described in this application has 470 PFAS content indicators that do not exceed the standard (≤250ppb), meeting the stringent international regulations such as EU REACH, POPs, and PPWR, and can smoothly enter overseas markets; it has good product performance, with tensile strength ≥20MPa, elongation at break ≥150%, compression set ≤20%, and hardness (Shore A) 60-80. All properties meet and exceed industry quality control standards.

[0051] The technical solution of this application will be further described below with reference to specific embodiments.

[0052] Example 1 A fluororubber prepared using a fluorine-free surfactant includes the following steps: Measure 2500 parts by weight of high-purity deionized water into a sealed polymerization reactor, start the stirring device, and adjust the stirring speed to 100 rpm; then add 10 parts by weight of octylphenol polyoxyethylene ether OP-10 (C8H). 17 -C6H4-O-(CH2CH2O) 10 The polymerization reactor system was heated to 75°C with 10 parts of isoheptane (a molecular weight regulator); then, a mixture of VDF, HFP, and TFE monomers (monomer molar ratio of VDF:HFP:TFE = 50:30:20) was introduced into the reactor until the pressure inside the reactor reached 1.6 MPa (the amount of mixed monomers introduced was 250 parts); then, 0.2 parts of potassium persulfate initiator was added to the system to initiate the copolymerization reaction, and the reaction was maintained at this temperature for 2 hours. During copolymerization, a mixture of VDF, HFP, and TFE monomers (monomer molar ratio of VDF:HFP:TFE = 45:28:27) was continuously added to the polymerization reactor to maintain a stable pressure of 1.6 MPa, while controlling the reaction temperature at 75°C. During copolymerization, isoheptane, a molecular weight regulator, was continuously added to the polymerization reactor, with the amount of regulator added being 0.5 wt% of the total added mixed monomers. The total amount of mixed monomers to be added reached 8 wt%. When the content of the copolymerization reaction was 00 parts, the copolymerization reaction was terminated (the reaction time was 2 hours at this time), and a fluororubber emulsion was obtained. The emulsion was subjected to electrolyte coagulation treatment, washed and purified with deionized water, and then dried at 140°C for 8 hours to obtain fluororubber raw rubber. The fluororubber raw rubber was mixed with 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triallyl isocyanurate, and semi-reinforcing carbon black at a mass ratio of 100:2.5:7:30 and kneaded at 200°C for 8 hours to obtain fluororubber.

[0053] Example 2 The only difference between the fluororubber prepared using fluorine-free surfactants in Example 2 and Example 1 is that the fluororubber prepared in Example 2 uses C8H... 17 -C6H4-O-(CH2CH2O)3-H replaces C8H 17 -C6H4-O-(CH2CH2O) 10 -H.

[0054] Example 3 The only difference between the fluororubber prepared using fluorine-free surfactants in Example 3 and that in Example 1 is that the fluororubber prepared in Example 3 uses C8H... 17 -C6H4-O-(CH2CH2O)9-H replaces C8H 17 -C6H4-O-(CH2CH2O) 10 -H.

[0055] Example 4 The only difference between the fluororubber prepared using fluorine-free surfactants in Example 4 and that in Example 1 is that the fluororubber prepared in Example 4 uses C8H... 17 -C6H4-O-(CH2CH2O) 12 -H replaces C8H 17 -C6H4-O-(CH2CH2O) 10 -H.

[0056] Example 5 The only difference between the fluororubber prepared using fluorine-free surfactants in Example 5 and that in Example 1 is that the fluororubber prepared in Example 5 uses C8H... 17 -C6H4-O-(CH2CH2O)15 -H replaces C8H 17 -C6H4-O-(CH2CH2O) 10 -H.

[0057] Comparative Example 1 The only difference between the fluororubber described in Comparative Example 1 and that in Example 1 is that the fluororubber described in Comparative Example 1 uses the traditional fluorinated surfactant CF3-(CF2)6-COOH instead of C8H in its preparation process. 17 -C6H4-O-(CH2CH2O) 10 -H.

[0058] The performance of the fluororubber described in Examples 1-5 and Comparative Example 1 of this application was studied, and the results are shown in Table 1.

[0059] Table 1

[0060] Table 1 shows that the key performance indicators of fluororubber prepared using hydrocarbon surfactants, such as tensile strength, elongation at break, Shore A hardness, and compression set, are consistent with those of products prepared using traditional processes. All performance parameters of the product consistently meet the standards: tensile strength not less than 20 MPa, elongation at break not less than 150%, compression set controlled within 20%, and Shore A hardness in the range of 60-80. Simultaneously, this method effectively solves the problem of cross-contamination in the production process; testing showed that none of the 671 perfluorinated and polyfluoroalkyl substances (PFAS) were detected. Furthermore, when C8H... 17 When the n value of -C6H4-O-(CH2CH2O)nH is between 9 and 12, the product exhibits better mechanical properties. Overall, hydrocarbon surfactants can completely replace the original raw materials in the production of fluororubber.

[0061] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for preparing fluororubber using fluorine-free surfactants, characterized in that, Includes the following steps: (1) Add non-fluorinated surfactant, molecular weight regulator, mixed monomers, initiator and water to the reactor to carry out copolymerization reaction; (2) Add mixed monomers and molecular weight regulators to the reactor and continue the copolymerization reaction to obtain fluororubber raw rubber; (3) The fluororubber raw rubber and the vulcanizing agent are mixed and vulcanized to obtain the fluororubber; The mixed monomers include vinylidene fluoride, perfluoropropylene, and tetrafluoroethylene in a molar ratio of 35-55:20-33:20-32.

2. The method for preparing fluororubber using fluorine-free surfactants according to claim 1, characterized in that, In step (1), the fluorine-free surfactant has the structural formula C8H. 17 -C6H4-O-(CH2CH2O)nH, where n takes the value 7≤n≤30.

3. The method for preparing fluororubber using fluorine-free surfactants according to claim 1, characterized in that, The fluorine-free surfactant has the structural formula C8H. 17 -C6H4-O-(CH2CH2O)nH, where the value of n is 4≤n≤13; Preferably, the fluorine-free surfactant includes one or more of octylphenol polyoxyethylene ether OP-7, octylphenol polyoxyethylene ether OP-9, octylphenol polyoxyethylene ether OP-10, and octylphenol polyoxyethylene ether OP-13.

4. The method for preparing fluororubber using fluorine-free surfactants according to claim 1, characterized in that, The molecular weight regulator includes alkane molecular weight regulators and / or ester molecular weight regulators; And / or, the initiator includes one or more of potassium persulfate, tert-butyl hydroperoxide, tert-butyl peroxide, peracetic acid, and potassium perchlorate; And / or, the vulcanizing agent includes 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triallyl isocyanurate, and semi-reinforcing carbon black.

5. The method for preparing fluororubber using fluorine-free surfactants according to claim 4, characterized in that, The alkane molecular weight regulators include one or more of the following: n-pentane, isopentane, n-hexane, cyclohexane, n-heptane, n-octane, isoheptane, and isooctane. And / or, the ester molecular weight regulator includes one or more of isooctyl mercaptoacetate, isooctyl 3-mercaptopropionate, ethyl mercaptoacetate, butyl acetate, and dibutyl phthalate.

6. The method for preparing fluororubber using fluorine-free surfactants according to claim 1, characterized in that, In step (1), the mass ratio of the fluorine-free surfactant, molecular weight regulator, mixed monomer, initiator and water is (10-50):(0-10):(230-280):(0.2-2):(2400-3000). And / or, in step (1), the temperature of the copolymerization reaction is 50-95℃, the pressure is 1.0-3.0MPa, and the time is 100-200min.

7. The method for preparing fluororubber using fluorine-free surfactants according to claim 1, characterized in that, In step (2), the amount of mixed monomers added is 3-5 times that in step (1); And / or, the mass ratio of the mixed monomers and molecular weight regulators added in step (2) is 100:(0.1-1); And / or, in step (2), the temperature of the copolymerization reaction is 50-95℃, the pressure is 1.0-3.0MPa, and the time is 2-4h.

8. The method for preparing fluororubber using fluorine-free surfactants according to claim 1, characterized in that, In step (3), the mass ratio of the fluororubber raw rubber to the vulcanizing agent is 100:(38-46). Preferably, the mass ratio of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triallyl isocyanurate, and semi-reinforcing carbon black in the vulcanizing agent is 2.5-3.0: 6.0-8.0: 30-35; And / or, the vulcanization treatment is carried out at a temperature of 190-230°C for a time of 8-16 hours.

9. The method for preparing fluororubber using fluorine-free surfactants according to claim 1, characterized in that, It also includes treating the copolymerization product of step (1) with electrolyte coagulation, then washing and drying to obtain fluororubber raw rubber; Preferably, the washing includes washing with deionized water; Preferably, the drying temperature is 120-150℃ and the time is 8-10h.

10. A fluororubber, characterized in that, It is prepared by the method described in any one of claims 1-9.

Images