High temperature resistant fluorine rubber, its preparation method and use

Abstract

This invention provides a high-temperature resistant fluororubber, its preparation method, and its applications, belonging to the technical field of rubber product compounds. The fluororubber prepared by this invention comprises the following raw materials in parts by weight: 90-110 parts fluororubber, 1-5 parts vulcanizing agent, 1-5 parts crosslinking agent, 20-40 parts inorganic filler, 3-7 parts metal compound filler, 0.1-3 parts dianhydride monomer, 0.1-2 parts diamine monomer, 5-10 parts N,N-dimethylformamide, and 0.5-1.5 parts internal release agent. This invention also provides a method for preparing the above-mentioned fluororubber. The fluororubber material prepared by this invention not only possesses excellent mechanical properties but also excellent high-temperature mechanical stability, showing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of rubber product compound technology, specifically relating to a high-temperature resistant fluororubber, its preparation method, and its uses. Background Technology

[0002] Fluororubber is a synthetic polymer elastomer containing fluorine atoms on the carbon atoms of its main chain or side chains. The introduction of fluorine atoms endows the rubber with excellent heat resistance, oxidation resistance, oil resistance, corrosion resistance, and atmospheric aging resistance, making it widely used in aerospace, aviation, automotive, petroleum, and household appliances. It is an irreplaceable key material in advanced defense industries. With rapid societal development, the requirements for materials in aerospace, high-speed rail, shipbuilding, and semiconductor industries are becoming increasingly stringent, generally requiring temperature resistance above 250°C. Ordinary fluororubber typically only withstands 230°C, which no longer meets industry requirements. Although perfluoroether rubber can withstand 250°C and above, its extremely high price results in significant costs.

[0003] Existing technical solutions (CN116462925A, CN113372668A, CN112898706A, CN110054854A, CN104045948A) improve the heat resistance of fluororubber by adding heat-resistant agents such as metal oxides, tetrafluoroethylene powder, and silane coupling agents. However, their heat resistance is generally poor and insufficient for long-term use at 250℃ and 280℃. Among these methods, adding heat-resistant agents such as metal oxides is the most common, but this method has limited improvement on the heat resistance of fluororubber, usually only meeting the requirements up to 250℃, and offering very little improvement at 280℃.

[0004] Patent application (CN114181480A) discloses a fluororubber composition comprising the following raw materials in parts by weight: 100 parts fluororubber, 1-30 parts polyimide, 1-3 parts crosslinking agent, 1-6 parts accelerator, and 0-3 parts processing aid. The addition of polyimide improves the elastic modulus and resilience of this fluororubber composition. However, on the one hand, the maximum tensile strength of this fluororubber composition is only 13.9 MPa, which needs further improvement; on the other hand, this patent application does not investigate the heat resistance of its fluororubber composition, nor does it teach how to improve the heat resistance of fluororubber.

[0005] Therefore, it is of great significance to develop a fluororubber that can withstand temperatures of 250°C and above, has excellent mechanical properties, and exhibits stable high-temperature mechanical properties. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a high-temperature resistant fluororubber, its preparation method and its uses.

[0007] This invention provides a high-temperature resistant fluororubber, which is prepared from the following raw materials in parts by weight: 90-110 parts fluororubber, 1-5 parts vulcanizing agent, 1-5 parts crosslinking agent, 20-40 parts inorganic filler, 3-7 parts metal compound filler, 0.1-3 parts dianhydride monomer, 0.1-2 parts diamine monomer, and 0.5-1.5 parts internal release agent.

[0008] Furthermore, the fluororubber is prepared from the following raw materials in parts by weight: 100 parts fluororubber, 3 parts vulcanizing agent, 4 parts crosslinking agent, 30 parts inorganic filler, 5 parts metal compound filler, 0.5-2 parts dianhydride monomer, 0.25-1 part diamine monomer, and 1 part internal release agent.

[0009] Furthermore, the fluororubber is type 26 fluororubber or type 246 fluororubber;

[0010] The vulcanizing agent is bis(2,5);

[0011] The crosslinking agent is triallyl isocyanurate;

[0012] The inorganic filler is carbon black;

[0013] The metal compound filler is zinc oxide;

[0014] The dihydric anhydride monomer is pyromellitic dianhydride, biphenyl dianhydride, hexafluoro dianhydride or diphenyl ether dianhydride.

[0015] The diamine monomer is m-phenylenediamine, diaminodiphenyl ether, 2,2-bis(trifluoromethyl)diaminobiphenyl or diaminodiphenyl sulfone;

[0016] The internal release agent is FPA-1.

[0017] The present invention also provides a method for preparing the above-mentioned high-temperature resistant fluororubber, the method comprising the following steps:

[0018] (1) Prepare a polyamic acid solution by reacting a dihydric anhydride monomer, a diamine monomer, and a polar solvent;

[0019] (2) Mix polyamic acid solution with fluororubber and heat in a programmed manner to prepare fluororubber raw rubber;

[0020] (3) Mix the raw fluororubber with the remaining raw materials, let it stand, and then re-mix it to obtain the fluororubber compound.

[0021] (4) Vulcanize the fluororubber compound to obtain high-temperature resistant fluororubber.

[0022] Further, in step (1), the polar solvent is an organic solvent; the reaction is carried out at -5 to 10°C for 1 to 5 hours.

[0023] In step (2), the conditions for internal mixing are: internal mixing at 10-40℃ for 5-15 minutes; the conditions for programmed heating are: first heating at 110-130℃ for 1-3 hours, then heating at 140-160℃ for 1-3 hours, and then heating at 160-180℃ for 1-3 hours.

[0024] Further, in step (1), the polar solvent is N,N-dimethylformamide; the reaction is carried out at 0-5°C for 4 hours;

[0025] In step (2), the conditions for internal mixing are: internal mixing at 20-30℃ for 10 minutes; the conditions for programmed heating are: first heating at 120℃ for 2 hours, then heating at 150℃ for 2 hours, and then heating at 170℃ for 2 hours.

[0026] Furthermore, in step (3), the conditions for intensive mixing are: intensive mixing at 40-80°C for 1-10 minutes; and the resting time is 20-30 hours.

[0027] In step (4), the vulcanization is divided into a first-stage vulcanization and a second-stage vulcanization. After the first-stage vulcanization, the sheet is left to stand at 10-40°C for 10-15 hours to prepare for the second-stage vulcanization.

[0028] The conditions for the first stage of vulcanization are: pressing at 160-200℃ and 10-20MPa for 1-10 minutes;

[0029] The conditions for the two-stage vulcanization are as follows: raise the temperature to 150-170℃ and hold for 3-5 hours; raise the temperature to 170-190℃ and hold for 3-5 hours; raise the temperature to 190-210℃ and hold for 3-5 hours; and finally raise the temperature to 220-240℃ and hold for 3-5 hours.

[0030] Furthermore, in step (3), the conditions for intensive mixing are: intensive mixing at 60°C for 6 minutes; and the resting time is 24 hours.

[0031] In step (4), the vulcanization is divided into a first-stage vulcanization and a second-stage vulcanization. After the first-stage vulcanization, the sheet is left to stand at 20-30°C for 12 hours to prepare for the second-stage vulcanization.

[0032] The conditions for the first stage of vulcanization are: pressing at 180℃ and 15MPa for 5 minutes;

[0033] The conditions for the two-stage vulcanization are as follows: raise the temperature to 160°C and hold for 4 hours; raise it to 180°C and hold for 4 hours; raise it to 200°C and hold for 4 hours; and finally raise it to 230°C and hold for 4 hours.

[0034] The present invention also provides the use of the above-mentioned high-temperature resistant fluororubber in the preparation of materials for aerospace, automotive, petroleum and household appliances.

[0035] The present invention has achieved the following beneficial effects:

[0036] 1. This invention proposes a novel method for thermally shielding the molecular chains of fluororubber, which significantly improves the high-temperature resistance of ordinary peroxy-cured fluororubber at 250℃ and 280℃.

[0037] 2. Compared with the fluororubber composition disclosed in patent document (CN114181480A), the fluororubber prepared by this invention has a higher tensile strength, reaching 16.01–18.75 MPa; while the highest tensile strength of the fluororubber composition in patent document (CN114181480A) is only 13.9 MPa. The fluororubber material prepared by this invention has excellent mechanical properties and improves the stability of the high-temperature mechanical properties of fluororubber.

[0038] 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.

[0039] 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 embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Detailed Implementation

[0040] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0041] In the formulation of the specific embodiments of the present invention, "part" refers to parts by weight, and 1 part is 1g.

[0042] Unless otherwise specified, the operation of the specific embodiments of the present invention is carried out at room temperature / normal temperature, which means 25±5℃ in the present invention.

[0043] Example 1: Preparation of high-temperature resistant fluororubber

[0044] The formulation of high-temperature resistant fluororubber is as follows: 100 parts of type 26 fluororubber, 3 parts of bis(2,5)-diphenyl ether, 4 parts of triallyl isocyanurate (TAIC) crosslinking agent, 30 parts of carbon black, 5 parts of zinc oxide, 0.5 parts of pyromellitic dianhydride (PMDA), 0.25 parts of m-phenylenediamine (MPD), 8 parts of N,N-dimethylformamide (DMF), and 1 part of internal mold release agent (FPA-1).

[0045] (1) Preparation of polyamic acid solution

[0046] First, MPD is dissolved in DMF, then PMDA is added and stirred until completely dissolved. The resulting solution is then reacted at 0-5℃ for 4 hours to obtain a polyamic acid solution.

[0047] (2) Preparation of compound rubber

[0048] The prepared polyamic acid solution and fluororubber were added to a mixer and mixed at room temperature for 10 minutes. The mixture was then removed and passed through a two-roll mill, forming a triangular sheet six times. After sheeting, the sheet was placed in an oven and heated sequentially at 120℃ / 2h, 150℃ / 2h, and 170℃ / 2h. It was then cooled to room temperature to obtain the pretreated fluororubber raw rubber. The obtained fluororubber raw rubber was then added to a mixer along with the remaining ingredients in the formulation and mixed at 60℃ for 6 minutes. The mixture was then removed, allowed to stand for 24 hours, and then re-mixed to obtain a high-temperature resistant fluororubber compound.

[0049] (3) First stage of sulfidation

[0050] The fluororubber compound was placed in a flat vulcanizing machine and pressed at 180℃ and 15MPa for 5 minutes for the first stage of vulcanization. After the vulcanized sheets were produced, they were allowed to stand at room temperature for 12 hours to prepare for the second stage of vulcanization.

[0051] (4) Two-stage vulcanization

[0052] The film sheets were neatly arranged in an oven and heated from room temperature to 160°C, held for 4 hours; then heated to 180°C, held for 4 hours; then heated to 200°C, held for 4 hours; and finally heated to 230°C, held for 4 hours. After the two-stage vulcanization, the sheets were left to stand at room temperature for an appropriate time to obtain high-temperature resistant fluororubber. The sheets were then punched with a cutter to prepare for testing of high-temperature mechanical properties.

[0053] Example 2: Preparation of high-temperature resistant fluororubber

[0054] The formulation of high-temperature resistant fluororubber is as follows: 100 parts of type 246 fluororubber, 3 parts of bis(2,5)-diphenyl ether, 4 parts of TAIC crosslinking agent, 30 parts of carbon black, 5 parts of zinc oxide, 2 parts of biphenyl dianhydride (BPDA), 1 part of m-phenylenediamine (MPD), 8 parts of N,N-dimethylformamide (DMF), and 1 part of internal mold release agent (FPA-1).

[0055] Following the method in Example 1, a high-temperature resistant fluororubber was prepared and punched into sheets using a cutting tool in preparation for testing its high-temperature mechanical properties.

[0056] Example 3: Preparation of high-temperature resistant fluororubber

[0057] The formulation of high-temperature resistant fluororubber is as follows: 100 parts of type 246 fluororubber, 3 parts of bis(2,5)-diphenyl ether, 4 parts of TAIC crosslinking agent, 30 parts of carbon black, 5 parts of zinc oxide, 2 parts of pyromellitic dianhydride (PMDA), 1 part of diaminodiphenyl ether (OPD), 8 parts of N,N-dimethylformamide (DMF), and 1 part of internal mold release agent (FPA-1).

[0058] Following the method in Example 1, a high-temperature resistant fluororubber was prepared and punched into sheets using a cutting tool in preparation for testing its high-temperature mechanical properties.

[0059] Example 4: Preparation of high-temperature resistant fluororubber

[0060] The formulation of high-temperature resistant fluororubber is as follows: 100 parts of type 246 fluororubber, 3 parts of bis(2,5)-diphenyl ether, 4 parts of TAIC crosslinking agent, 30 parts of carbon black, 5 parts of zinc oxide, 1 part of hexafluorodianhydride (6FDA), 1 part of 2,2-di(trifluoromethyl)diaminobiphenyl (TFMB), 8 parts of N,N-dimethylformamide (DMF), and 1 part of internal mold release agent (FPA-1).

[0061] Following the method in Example 1, a high-temperature resistant fluororubber was prepared and punched into sheets using a cutting tool in preparation for testing its high-temperature mechanical properties.

[0062] Example 5: Preparation of high-temperature resistant fluororubber

[0063] The formulation of high-temperature resistant fluororubber is as follows: 100 parts of type 246 fluororubber, 3 parts of bis(2,5)-diphenyl ether dianhydride (OPDA), 4 parts of TAIC crosslinking agent, 30 parts of carbon black, 5 parts of zinc oxide, 2 parts of diphenyl ether dianhydride (OPDA), 1 part of diaminodiphenyl sulfone (PPDA), 8 parts of N,N-dimethylformamide (DMF), and 1 part of internal mold release agent (FPA-1).

[0064] Following the method in Example 1, a high-temperature resistant fluororubber was prepared and punched into sheets using a cutting tool in preparation for testing its high-temperature mechanical properties.

[0065] The preparation of fluororubber is compared below using comparative proportions.

[0066] Comparative Example 1: Preparation of High-Temperature Resistant Fluororubber

[0067] The formulation of high-temperature resistant fluororubber is as follows: 100 parts of type 26 fluororubber, 3 parts of bis(2,5)5, ​​4 parts of TAIC crosslinking agent, 30 parts of carbon black, 5 parts of zinc oxide, and 1 part of internal release agent (FPA-1).

[0068] Weigh out the following ingredients by weight: type 26 fluororubber, bis(2,5), TAIC, carbon black, zinc oxide, and internal release agent (FPA-1). Add all the above ingredients to a mixer and mix at 60°C for 6 minutes. Remove and allow to stand to obtain a high-temperature resistant fluororubber compound. Before vulcanization, the fluororubber compound needs to be left to stand for 24 hours before reprocessing. Subsequent steps are the same as in steps (3) and (4) of Example 1. The high-temperature resistant fluororubber is then sheeted using a cutting tool for testing its high-temperature mechanical properties.

[0069] Comparative Example 2: Preparation of High-Temperature Resistant Fluororubber

[0070] Following the method of Comparative Example 1, the only difference was that type 26 fluororubber in the formulation of Comparative Example 1 was replaced with type 246 fluororubber; all other steps and parameters were the same as in Comparative Example 1. High-temperature resistant fluororubber was prepared and sheeted using a cutting tool for testing its high-temperature mechanical properties.

[0071] The mechanical properties of the samples from the above examples and comparative examples were tested according to GB / T 528-2009 standard. The results are shown in Table 1.

[0072] Table 1. Mechanical property test results of high-temperature resistant fluororubber in the examples and comparative examples

[0073]

[0074] Among them, Comparative Example 2 became brittle and easily broken after aging at 280℃ for 168 hours and could not be tested.

[0075] Data from Comparative Examples 1 and 2 show that the fluororubber prepared from type 246 fluororubber (280℃) exhibits better high-temperature resistance than type 26 fluororubber (250℃). Data from Examples 1-5 show that fluororubbers prepared from different types of diamine monomers and dianhydride monomers all possess excellent tensile strength and high-temperature mechanical property stability. The fluororubbers prepared in Examples 1-5 show better stability under high-temperature conditions. Compared to Comparative Examples 1 and 2, the tensile strength changes of the fluororubbers prepared in Examples 1-5 before and after high-temperature aging are significantly reduced. Specifically, the changes in elongation at break in Examples 1-3 are significantly better than those in Comparative Examples 1 and 2.

[0076] In summary, this invention provides a high-temperature resistant fluororubber, its preparation method, and its applications. The fluororubber prepared by this invention comprises the following raw materials in parts by weight: 90-110 parts fluororubber, 1-5 parts vulcanizing agent, 1-5 parts crosslinking agent, 20-40 parts inorganic filler, 3-7 parts metal compound filler, 0.1-3 parts dianhydride monomer, 0.1-2 parts diamine monomer, 5-10 parts N,N-dimethylformamide, and 0.5-1.5 parts internal release agent. This invention also provides a method for preparing the above-mentioned fluororubber. The fluororubber material prepared by this invention not only possesses excellent mechanical properties but also excellent high-temperature mechanical stability, and has broad application prospects.

Claims

1. A high-temperature resistant fluororubber, characterized in that, It is made from the following raw materials in parts by weight: 100 parts of type 246 fluororubber, 3 parts of bis(2,5)5, ​​4 parts of triallyl isocyanurate, 30 parts of carbon black, 5 parts of zinc oxide, 2 parts of dianhydride monomer, 1 part of diamine monomer, and 1 part of FPA-1. The dihydric anhydride monomer is pyromellitic dianhydride; The diamine monomer is diaminodiphenyl ether.

2. A high-temperature resistant fluororubber, characterized in that, It is made from the following raw materials in parts by weight: 100 parts of type 246 fluororubber, 3 parts of bis(2,5)5, ​​4 parts of triallyl isocyanurate, 30 parts of carbon black, 5 parts of zinc oxide, 2 parts of dianhydride monomer, 1 part of diamine monomer, and 1 part of FPA-1. The dihydric anhydride monomer is biphenyl ether dianhydride; The diamine monomer is diaminodiphenyl ether.

3. A method for preparing the high-temperature resistant fluororubber according to claim 1 or 2, characterized in that, The method includes the following steps: (1) Prepare a polyamic acid solution by reacting a dihydric anhydride monomer, a diamine monomer, and a polar solvent; (2) The polyamic acid solution is mixed with fluororubber and heated in a controlled manner to prepare fluororubber raw rubber; (3) Mix the raw fluororubber with the remaining raw materials, let it stand, and then re-mix it to obtain the fluororubber compound. (4) Vulcanize the fluororubber compound to obtain high-temperature resistant fluororubber.

4. The method according to claim 3, characterized in that, In step (1), the polar solvent is an organic solvent; the reaction is carried out at -5~10℃ for 1~5 hours. In step (2), the conditions for internal mixing are: internal mixing at 10~40℃ for 5~15 minutes; the conditions for programmed heating are: first heating at 110~130℃ for 1~3 hours, then heating at 140~160℃ for 1~3 hours, and then heating at 160~180℃ for 1~3 hours.

5. The method according to claim 4, characterized in that, In step (1), the polar solvent is N,N-dimethylformamide; the reaction is carried out at 0~5℃ for 4 hours. In step (2), the conditions for internal mixing are: internal mixing at 20~30℃ for 10 minutes; the conditions for programmed heating are: first heating at 120℃ for 2 hours, then heating at 150℃ for 2 hours, and then heating at 170℃ for 2 hours.

6. The method according to claim 5, characterized in that, In step (3), the conditions for intensive mixing are: intensive mixing at 40~80℃ for 1~10 minutes; the resting time is 20~30 hours; In step (4), the vulcanization is divided into a first-stage vulcanization and a second-stage vulcanization. After the first-stage vulcanization, the sheet is left to stand at 10~40℃ for 10~15h in preparation for the second-stage vulcanization. The conditions for the first stage of vulcanization are: pressing at 160~200℃ and 10~20MPa for 1~10min; The conditions for the two-stage vulcanization are as follows: raise the temperature to 150~170℃ and hold for 3~5 hours; raise the temperature to 170~190℃ and hold for 3~5 hours; raise the temperature to 190~210℃ and hold for 3~5 hours; and finally raise the temperature to 220~240℃ and hold for 3~5 hours.

7. The method according to claim 6, characterized in that, In step (3), the conditions for intensive mixing are: intensive mixing at 60°C for 6 minutes; and the resting time is 24 hours. In step (4), the vulcanization is divided into a first-stage vulcanization and a second-stage vulcanization. After the first-stage vulcanization, the sheet is left to stand at 20~30℃ for 12 hours to prepare for the second-stage vulcanization. The conditions for the first stage of vulcanization are: pressing at 180℃ and 15MPa for 5 minutes; The conditions for the two-stage vulcanization are as follows: raise the temperature to 160°C and hold for 4 hours; raise it to 180°C and hold for 4 hours; raise it to 200°C and hold for 4 hours; and finally raise it to 230°C and hold for 4 hours.

8. Use of the high-temperature resistant fluororubber as described in claim 1 or 2 in the preparation of materials for aerospace, automotive, petroleum and household appliances.

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