High-temperature-resistant fluororubber as well as preparation method and application thereof

Abstract

The invention provides high-temperature-resistant fluororubber as well as a preparation method and application thereof, and belongs to the technical field of rubber products. The fluororubber prepared by the invention comprises the following raw materials in parts by mass: 90-110 parts of fluororubber, 1-5 parts of a vulcanizing agent, 1-5 parts of a cross-linking agent, 20-40 parts of an inorganic filler, 3-7 parts of a metal compound filler, 0.1-3 parts of a dianhydride monomer, 0.1-2 parts of a diamine monomer, 5-10 parts of N, N-dimethylformamide and 0.5-1.5 parts of an internal release agent. The invention also provides a preparation method of the fluororubber. The fluororubber material prepared by the invention not only has excellent mechanical properties, but also has excellent high-temperature mechanical stability and wide application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber product compounds, and in particular relates to a high temperature resistant fluororubber and a preparation method and application thereof. Background Art

[0002] Fluororubber refers to a synthetic polymer elastomer containing fluorine atoms on the carbon atoms of the main chain or side chain. The introduction of fluorine atoms gives the rubber excellent heat resistance, oxidation resistance, oil resistance, corrosion resistance and atmospheric aging resistance, making fluororubber widely used in aerospace, aviation, automobiles, petroleum and household appliances, and is an irreplaceable key material in the cutting-edge defense industry. With the rapid development of society, the requirements for materials in fields such as aerospace, high-speed rail ships and the semiconductor industry are becoming more and more stringent, and generally require temperature resistance to reach above 250°C, while ordinary fluororubber can usually only withstand 230°C, which can no longer meet industry requirements. Although perfluoroether rubber can withstand 250°C and above, its price is extremely expensive, which brings heavy 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, but their heat resistance is usually poor and is not enough to allow fluororubber to be used for a long time at temperatures of 250°C and 280°C. Among them, adding heat-resistant agents such as metal oxides is the most commonly used method, but this method has limited improvement in the heat resistance of fluororubber, usually only meeting 250°C, but the improvement at 280°C is very poor.

[0004] The patent application document (CN114181480A) discloses a fluororubber composition, which includes the following raw materials in parts by mass: 100 parts of fluororubber, 1 to 30 parts of polyimide, 1 to 3 parts of crosslinking agent, 1 to 6 parts of accelerator, and 0 to 3 parts of processing aid. By adding polyimide, the elastic modulus and resilience of the fluororubber composition are improved, but on the one hand, the maximum tensile strength of the fluororubber composition is only 13.9 MPa, which needs to be further improved; on the other hand, the patent application document does not study the heat resistance of the 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 250°C and above, has excellent mechanical properties and stable high-temperature mechanical properties. Summary of the invention

[0006] In view of the problems existing in the prior art, the object of the present invention is to provide a high temperature resistant fluororubber and a preparation method and use thereof.

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

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

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

[0010] The vulcanizing agent is di-2-5;

[0011] The cross-linking agent is triallyl isocyanurate;

[0012] The inorganic filler is carbon black;

[0013] The metal compound filler is zinc oxide;

[0014] The dibasic anhydride monomer is pyromellitic dianhydride, biphenyltetracarboxylic 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) reacting a dibasic anhydride monomer, a diamine monomer and a polar solvent to prepare a polyamic acid solution;

[0019] (2) kneading the polyamic acid solution and fluororubber, and heating them in a program to prepare fluororubber raw rubber;

[0020] (3) Mix the fluororubber raw rubber with other raw materials, place them aside, and then remix them to obtain a fluororubber mixed rubber;

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

[0022] Furthermore, in step (1), the polar solvent is an organic solvent; the reaction is: reacting at -5 to 10°C for 1 to 5 hours;

[0023] In step (2), the conditions for the banburying are: banburying at 10-40°C for 5-15 min; the conditions for the programmed heating are: first heating at 110-130°C for 1-3 h, then heating at 140-160°C for 1-3 h, and then heating at 160-180°C for 1-3 h.

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

[0025] In step (2), the banburying conditions are: banburying at 20-30°C for 10 min; the programmed heating conditions are: first heating at 120°C for 2 h, then heating at 150°C for 2 h, and then heating at 170°C for 2 h.

[0026] Furthermore, in step (3), the banburying conditions are: banburying at 40-80° C. for 1-10 min; the parking time is 20-30 hours;

[0027] In step (4), the vulcanization is divided into a first-stage vulcanization and a second-stage vulcanization, wherein the first-stage vulcanization is followed by standing at 10 to 40° C. for 10 to 15 hours to wait for the second-stage vulcanization;

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

[0029] The conditions of the two-stage vulcanization are: heating to 150-170° C. and maintaining for 3-5 hours; then heating to 170-190° C. and maintaining for 3-5 hours; then heating to 190-210° C. and maintaining for 3-5 hours; and finally heating to 220-240° C. and maintaining for 3-5 hours.

[0030] Furthermore, in step (3), the banburying conditions are: banburying at 60° C. for 6 min; the parking time is 24 hours;

[0031] In step (4), the vulcanization is divided into a first-stage vulcanization and a second-stage vulcanization, wherein the first-stage vulcanization is followed by standing at 20-30° C. for 12 hours to wait for the second-stage vulcanization;

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

[0033] The conditions of the two-stage vulcanization are: heating to 160° C. and maintaining for 4 hours; then heating to 180° C. and maintaining for 4 hours; then heating to 200° C. and maintaining for 4 hours; and finally heating to 230° C. and maintaining for 4 hours.

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

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

[0036] 1. The present invention proposes a new method to thermally shield the fluororubber molecular chain, which significantly improves the high temperature resistance of ordinary peroxysulfurized fluororubber at 250°C and 280°C.

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

[0038] Obviously, according to the above contents of the present invention, in accordance with common technical knowledge and customary means in the art, without departing from the above basic technical ideas of the present invention, other various forms of modification, replacement or change may be made.

[0039] The above contents of the present invention are further described in detail below through specific implementation methods in the form of examples. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above contents of the present invention belong to the scope of the present invention. DETAILED DESCRIPTION

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

[0041] In the formula of the specific embodiment of the present invention, "part" means part by weight, and 1 part is 1 g.

[0042] Unless otherwise specified, the operations in the specific embodiments of the present invention are carried out at room temperature / normal temperature, and the "room temperature / normal temperature" referred to in the present invention is 25±5°C.

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

[0044] The formula of high temperature resistant fluororubber: 100 parts of type 26 fluororubber, 3 parts of bis(25-DI), 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 meta-phenylenediamine (MPD), 8 parts of N,N-dimethylformamide (DMF), and 1 part of internal release agent (FPA-1).

[0045] (1) Preparation of polyamic acid solution

[0046] First, MPD was dissolved in DMF, and then PMDA was added and stirred until completely dissolved. The obtained solution was placed in an environment of 0-5° C. and reacted for 4 hours to obtain a polyamic acid solution.

[0047] (2) Preparation of rubber compound

[0048] The polyamic acid solution and fluororubber prepared above are put into an internal mixer and mixed at room temperature for 10 minutes, then taken out and placed on an open mixer for thinning, triangular packaged 6 times, and then placed in an oven for heating at 120℃ / 2h, 150℃ / 2h, and 170℃ / 2h in sequence, and then cooled to room temperature to obtain the pretreated fluororubber raw rubber. The obtained fluororubber raw rubber is put into an internal mixer together with the remaining raw materials of the formula, mixed at 60℃ for 6 minutes, taken out, parked for 24 hours, and re-mixed to obtain high temperature resistant fluororubber compound.

[0049] (3) One-stage vulcanization

[0050] Place the fluororubber compound in a flat vulcanizer and press at 180°C and 15MPa for 5 minutes for primary vulcanization. After the vulcanized sheet is produced, let it stand at room temperature for 12 hours to wait for the secondary vulcanization.

[0051] (4) Two-stage vulcanization

[0052] Place the film neatly in the oven, raise the temperature from room temperature to 160℃, keep it for 4 hours; then raise it to 180℃, keep it for 4 hours; then raise it to 200℃, keep it for 4 hours; finally raise it to 230℃, keep it for 4 hours. After the second stage vulcanization, the film is left at room temperature for a suitable period of time to obtain the high temperature resistant fluororubber, which is punched with a cutter to prepare for the test of high temperature mechanical properties.

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

[0054] The formula of high temperature resistant fluororubber: 100 parts of 246 type fluororubber, 3 parts of bis(25-dimethylbenzene), 4 parts of TAIC crosslinking agent, 30 parts of carbon black, 5 parts of zinc oxide, 2 parts of biphenyltetracarboxylic dianhydride (BPDA), 1 part of metaphenylenediamine (MPD), 8 parts of N,N-dimethylformamide (DMF), and 1 part of internal release agent (FPA-1).

[0055] Referring to the method of Example 1, a high temperature resistant fluororubber was prepared and punched out with a cutter to prepare for testing high temperature mechanical properties.

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

[0057] The formula of high temperature resistant fluororubber: 100 parts of 246 type fluororubber, 3 parts of double 25, 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 release agent (FPA-1).

[0058] Referring to the method of Example 1, a high temperature resistant fluororubber was prepared and punched out with a cutter to prepare for testing high temperature mechanical properties.

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

[0060] The formula of high temperature resistant fluororubber: 100 parts of type 246 fluororubber, 3 parts of double 25, 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-bis(trifluoromethyl)diaminobiphenyl (TFMB), 8 parts of N,N-dimethylformamide (DMF), and 1 part of internal release agent (FPA-1).

[0061] Referring to the method of Example 1, a high temperature resistant fluororubber was prepared and punched out with a cutter to prepare for testing high temperature mechanical properties.

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

[0063] The formula of high temperature resistant fluororubber: 100 parts of 246 type fluororubber, 3 parts of double 25, 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 release agent (FPA-1).

[0064] Referring to the method of Example 1, a high temperature resistant fluororubber was prepared and punched out with a cutter to prepare for testing high temperature mechanical properties.

[0065] The preparation of fluororubber is compared by comparative examples.

[0066] Comparative Example 1: Preparation of high temperature resistant fluororubber

[0067] The formula of high temperature resistant fluororubber: 100 parts of type 26 fluororubber, 3 parts of double 25, 4 parts of TAIC cross-linking agent, 30 parts of carbon black, 5 parts of zinc oxide, and 1 part of internal release agent (FPA-1).

[0068] Weigh 26-type fluororubber, double 25, TAIC, carbon black, zinc oxide, and internal mold release agent (FPA-1) by weight. Put the above raw materials into an internal mixer and mix them at 60°C for 6 minutes. Take them out and let them stand to obtain a high-temperature resistant fluororubber compound. Before vulcanization, the fluororubber compound needs to be parked for 24 hours and then re-mixed for use. The subsequent steps are the same as steps (3) and (4) of Example 1. Prepare the high-temperature resistant fluororubber and use a cutter to punch out sheets for testing high-temperature mechanical properties.

[0069] Comparative Example 2: Preparation of high temperature resistant fluororubber

[0070] Referring to the method of comparative example 1, the only difference is that the 26-type fluororubber in the formula of comparative example 1 is replaced with 246-type fluororubber, and the other steps and parameters are the same as those of comparative example 1. The high-temperature resistant fluororubber is prepared and punched with a cutter to prepare for testing the high-temperature mechanical properties.

[0071] The mechanical properties of the samples of 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 properties test results of high temperature resistant fluororubbers of examples and comparative examples

[0073]

[0074] Among them, Comparative Example 2 became brittle and easy to break after aging at 280° C. for 168 hours and could not be tested.

[0075] The data of Comparative Examples 1 and 2 show that the fluororubber prepared with 246 type fluororubber (280°C) has better high temperature resistance than 26 type fluororubber (250°C). The data of Examples 1 to 5 show that the fluororubbers prepared with different types of diamine monomers and dianhydride monomers have excellent tensile strength and high temperature mechanical property stability. The fluororubbers prepared in Examples 1 to 5 have better stability under high temperature conditions. Compared with Comparative Examples 1 and 2, the change in tensile strength of the fluororubbers prepared in Examples 1 to 5 before and after high temperature aging is significantly reduced, among which the change in elongation at break of Examples 1 to 3 is significantly better than that of Comparative Examples 1 and 2.

[0076] In summary, the present invention provides a high temperature resistant fluororubber and its preparation method and use. The fluororubber prepared by the present invention includes the following raw materials in parts by mass: 90-110 parts of fluororubber, 1-5 parts of vulcanizing agent, 1-5 parts of cross-linking agent, 20-40 parts of inorganic filler, 3-7 parts of metal compound filler, 0.1-3 parts of dibasic anhydride monomer, 0.1-2 parts of diamine monomer, 5-10 parts of N,N-dimethylformamide, and 0.5-1.5 parts of internal release agent. The present invention also provides a method for preparing the above fluororubber. The fluororubber material prepared by the present invention not only has excellent mechanical properties, but also has excellent high temperature mechanical stability, and has broad application prospects.

Claims

1. A high temperature resistant fluororubber, characterized in that: It is prepared from the following raw materials in parts by mass: 90-110 parts of fluororubber, 1-5 parts of vulcanizing agent, 1-5 parts of crosslinking agent, 20-40 parts of inorganic filler, 3-7 parts of metal compound filler, 0.1-3 parts of dibasic anhydride monomer, 0.1-2 parts of diamine monomer and 0.5-1.5 parts of internal release agent.

2. The high temperature resistant fluororubber according to claim 1, characterized in that: The fluororubber is prepared from the following raw materials in parts by mass: 100 parts of fluororubber, 3 parts of vulcanizing agent, 4 parts of crosslinking agent, 30 parts of inorganic filler, 5 parts of metal compound filler, 0.5-2 parts of dibasic anhydride monomer, 0.25-1 part of diamine monomer, and 1 part of internal release agent.

3. The high temperature resistant fluororubber according to claim 1, characterized in that: The fluororubber is type 26 fluororubber or type 246 fluororubber; The vulcanizing agent is di-2-5; The cross-linking agent is triallyl isocyanurate; The inorganic filler is carbon black; The metal compound filler is zinc oxide; The dibasic anhydride monomer is pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, hexafluoro dianhydride or diphenyl ether dianhydride; The diamine monomer is m-phenylenediamine, diaminodiphenyl ether, 2,2-bis(trifluoromethyl)diaminobiphenyl or diaminodiphenyl sulfone; The internal release agent is FPA-1.

4. A method for preparing the high temperature resistant fluororubber according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: (1) reacting a dibasic anhydride monomer, a diamine monomer and a polar solvent to prepare a polyamic acid solution; (2) kneading the polyamic acid solution and fluororubber, and heating them to prepare fluororubber raw rubber; (3) Mix the fluororubber raw rubber with other raw materials, place them aside, and then remix them to obtain a fluororubber mixed rubber; (4) Vulcanize the fluororubber compound to obtain high temperature resistant fluororubber.

5. The method according to claim 4, characterized in that In step (1), the polar solvent is an organic solvent; the reaction is: reacting at -5 to 10°C for 1 to 5 hours; In step (2), the conditions for the banburying are: banburying at 10-40°C for 5-15 min; the conditions for the programmed heating are: first heating at 110-130°C for 1-3 h, then heating at 140-160°C for 1-3 h, and then heating at 160-180°C for 1-3 h.

6. The method according to claim 5, characterized in that In step (1), the polar solvent is N,N-dimethylformamide; the reaction is: reacting at 0-5°C for 4 hours; In step (2), the banburying conditions are: banburying at 20-30°C for 10 min; the programmed heating conditions are: first heating at 120°C for 2 h, then heating at 150°C for 2 h, and then heating at 170°C for 2 h.

7. The method according to claim 4, characterized in that In step (3), the banburying conditions are: banburying at 40-80° C. for 1-10 min; the parking time is 20-30 hours; In step (4), the vulcanization is divided into a first-stage vulcanization and a second-stage vulcanization, wherein the first-stage vulcanization is followed by standing at 10 to 40° C. for 10 to 15 hours to wait for the second-stage vulcanization; The conditions of the first stage vulcanization are: pressing at 160-200°C and 10-20MPa for 1-10min; The conditions of the two-stage vulcanization are: heating to 150-170° C. and maintaining for 3-5 hours; then heating to 170-190° C. and maintaining for 3-5 hours; then heating to 190-210° C. and maintaining for 3-5 hours; and finally heating to 220-240° C. and maintaining for 3-5 hours.

8. The method according to claim 7, characterized in that In step (3), the banburying conditions are: banburying at 60° C. for 6 min; the parking time is 24 hours; In step (4), the vulcanization is divided into one-stage vulcanization and two-stage vulcanization, wherein the first-stage vulcanization is followed by standing at 20-30° C. for 12 hours to wait for the second-stage vulcanization; The conditions of the first stage vulcanization are: pressing at 180°C and 15MPa for 5min; The conditions of the two-stage vulcanization are: heating to 160° C. and maintaining for 4 hours; then heating to 180° C. and maintaining for 4 hours; then heating to 200° C. and maintaining for 4 hours; and finally heating to 230° C. and maintaining for 4 hours.

9. Use of the high temperature resistant fluororubber according to any one of claims 1 to 3 in the preparation of materials for aerospace, automobiles, petroleum and household appliances.

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