High temperature resistant water vapor crosslinking agent, perfluoroether elastomer composition and preparation method

Abstract

The present invention relates to a high temperature water vapor resistant crosslinking agent, a perfluoroether elastomer composition and a preparation method. The preparation method of the high temperature water vapor resistant crosslinking agent comprises the following steps: S1, preparing a halogenated trifluoroethylene benzene Grignard reagent tetrahydrofuran solution, and reacting it with a halogenated perfluoroalkyl compound to synthesize a mixture containing the high temperature water vapor resistant crosslinking agent; S2, separating and purifying the mixture containing the high temperature water vapor resistant crosslinking agent to obtain the high temperature water vapor resistant crosslinking agent. The high temperature water vapor resistant crosslinking agent synthesized by the present invention is used to prepare a perfluoroether elastomer composition resistant to high temperature water vapor, and its high temperature water vapor resistance performance is significantly improved.

Description

Technical Field

[0001] The invention relates to a high-temperature resistant water vapor crosslinking agent, a perfluoroether elastomer composition and a preparation method, and is applied to the field of perfluoroether elastomers. Background Art

[0002] As semiconductor process technology improves, the environmental requirements for process reaction chambers are getting higher and higher. Rubber products, as important sealing components in semiconductor process reaction chambers, are often used to prevent high-pressure steam (or steam; hereinafter referred to as steam) from leaking from the pipeline system or the equipment it flows through.

[0003] In this case, the perfluoroether elastomer composition sealing material prepared from tetrafluoroethylene (TFE) and perfluoroalkyl vinyl ether (PAVE) is not enough to resist high-temperature steam. For example, the perfluoroether elastomer composition using the triazine vulcanization system is resistant to high temperatures up to 320°C, but is not resistant to water vapor, and its upper limit of water vapor resistance is 100°C; the perfluoroether elastomer composition using the peroxide vulcanization system can withstand 200°C water vapor, but the high temperature resistance can only reach 200°C; the perfluoroether elastomer composition using the fluorinated diene peroxide cross-linking system can simultaneously increase the temperature to 280°C, but does not meet the requirement of 300°C water vapor resistance.

[0004] Patent CN105452361B discloses a method for preparing a novel cross-linking agent, which has water vapor resistance at a temperature greater than 300°C. However, the preparation of the vulcanizing agent monomer adopts a replacement reaction method, which results in expensive raw materials and low recovery rate.

[0005] Based on this, the present invention proposes a new high temperature resistant water vapor crosslinking agent, a perfluoroether elastomer composition and a preparation method. Summary of the invention

[0006] The purpose of the present invention is to provide a high temperature water vapor resistant crosslinking agent, a perfluoroether elastomer composition and a preparation method to solve the problems existing in the above-mentioned prior art. The present invention provides a method for synthesizing a high temperature water vapor resistant crosslinking agent from fluorine-containing raw materials and various halogenated perfluoroalkyl compounds, and is applied to the preparation of a high temperature water vapor resistant perfluoroether elastomer composition.

[0007] In order to solve the above problems, the first aspect of the present invention provides a method for preparing a high temperature resistant water vapor crosslinking agent, comprising the following steps:

[0008] S1. preparing a tetrahydrofuran solution of a halogenated trifluoroethylene benzene Grignard reagent under nitrogen protection, and reacting the solution with a halogenated perfluoroalkyl compound to synthesize a mixture solution containing a high temperature resistant water vapor cross-linking agent;

[0009] S1-1, under nitrogen protection, reacting 2-2.1 equivalents of 1-bromo-4-(1,2,2-trifluorovinyl)benzene with magnesium in anhydrous tetrahydrofuran solution to prepare a Grignard reagent;

[0010] S1-2, dissolving 1 equivalent of 1,6-diiodoperfluorohexane in anhydrous tetrahydrofuran solution under nitrogen protection, heating under reflux and stirring, slowly adding the Grignard reagent, and reacting to obtain a mixture solution containing a high temperature vapor resistant crosslinking agent;

[0011] S2, separating and purifying the mixture solution containing the high temperature steam resistant cross-linking agent to obtain the high temperature steam resistant cross-linking agent;

[0012] S2-1. Add saturated ammonium chloride to quench the reaction, extract with ethyl acetate, wash with saturated brine, dry and filter, and concentrate the crude product by rotary evaporation.

[0013] In one embodiment, in step S2, the purification method includes any one of extraction, ion exchange, adsorption, and distillation, or a combination thereof.

[0014] The second aspect of the present invention provides a high temperature water vapor resistant cross-linking agent, which is prepared by the above-mentioned preparation method of the high temperature water vapor resistant cross-linking agent, and the chemical formula of the high temperature water vapor resistant cross-linking agent is:

[0015] CF2=CF-Ph-(CF2) n -Ph-CF=CF2

[0016] In the formula, Ph is the abbreviation of phenyl, and n is an integer greater than 2.

[0017] The third aspect of the present invention provides a method for preparing a high temperature water vapor resistant perfluoroether elastomer composition, comprising the following steps:

[0018] Step 1, preparing a perfluoroether elastomer;

[0019] Step 1-1, polymerizing 43-62 parts by mass of tetrafluoroethylene (TFE), 57-38 parts by mass of perfluoroalkyl vinyl ether (total 100 parts by mass), 0.5-2 parts by mass of non-conjugated fluorodiene vulcanization point monomer, 0.1-2 parts by mass of chain transfer agent, and 0.3-0.5 parts by mass of peroxy initiator to obtain a perfluoroether elastomer emulsion, and coagulating, washing, and drying to obtain a perfluoroether elastomer; wherein the fluorodiene is added in batches by a metering pump at the beginning and end of the reaction;

[0020] Step 2, preparing a perfluoroether elastomer composition, wherein the perfluoroether elastomer composition contains the above-mentioned high temperature resistant water vapor crosslinking agent;

[0021] Step 2-1, mixing 100 parts by mass of the perfluoroether elastomer described in step 1-1, 0.5-2 parts by mass of a high temperature steam resistant crosslinking agent, 0.5-2 parts by mass of a peroxide vulcanizing agent, and 1-50 parts by mass of a filler to obtain a crosslinked perfluoroether elastomer compound;

[0022] Step 2-2, the perfluoroether elastomer rubber compound is subjected to primary vulcanization molding at a temperature of 150-180° C., a pressure of 8-10 MPa, and a time of 10-20 min;

[0023] Step 2-3, using a combination of radiation vulcanization and high temperature vulcanization to secondary vulcanize the molded product to obtain a perfluoroether elastomer composition; wherein the radiation vulcanization dose is 100-200 kGy, the high temperature vulcanization temperature is 240-280°C, and the time is 1-4 hr.

[0024] In one embodiment, in step 1-1, the perfluoroalkyl vinyl ether includes any one of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, and perfluoropropyl vinyl ether.

[0025] In one embodiment, in step 1-1, the non-conjugated fluorodiene curing site monomer structure is CH2=CH-(CF2)n-CH=CH2 (n is an integer greater than or equal to 2).

[0026] In one embodiment, in step 1-1, the chain transfer agent includes any one of methanol, methyl formate, tert-butyl acetate, methylene iodide, perfluoroalkyl iodide and 1,4-diiodoperfluoro-butane; and the peroxy initiator is potassium persulfate or ammonium persulfate.

[0027] In one embodiment, in step 2-1, the peroxy curing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane or 1,3-bis(tert-butylperoxide isopropyl)benzene.

[0028] In one embodiment, in step 2-1, the filler includes any one of carbon black, carbon nanotubes, graphene, silicon dioxide, titanium dioxide, semi-crystalline fluoropolymer, and perfluoropolymer, or a combination thereof.

[0029] The fourth aspect of the present invention provides a high temperature water vapor resistant perfluoroether elastomer composition, which is prepared by the above-mentioned preparation method of the high temperature water vapor resistant perfluoroether elastomer composition.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] 1. The perfluoroether elastomer prepared by the high temperature steam resistant crosslinking agent of the present invention has a unique crosslinking structure, which not only has less side reactions between the crosslinking agents, but also has good dispersibility in the perfluoroether elastomer, so that the perfluoroether elastomer has excellent heat resistance and high temperature steam resistance.

[0032] 2. The high-temperature water vapor resistant perfluoroether elastomer composition prepared by the present invention using perfluoroether elastomer has excellent resistance to high-temperature water vapor and has the performance of water vapor resistance at a temperature higher than 300°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flowchart of a method for preparing a high temperature resistant water vapor cross-linking agent in an embodiment of the present invention;

[0034] Figure 2 It is a flowchart of a method for preparing a high temperature steam resistant perfluoroether elastomer composition in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0036] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0037] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0038] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0039] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0040] like Figure 1 As shown, this embodiment provides a method for preparing a high temperature resistant water vapor cross-linking agent, comprising the following steps:

[0041] S1. preparing a tetrahydrofuran solution of a halogenated trifluoroethylene benzene Grignard reagent under nitrogen protection, and reacting the solution with a halogenated perfluoroalkyl compound to synthesize a mixture solution containing a high temperature resistant water vapor cross-linking agent;

[0042] Wherein, the halogenated trifluoroethylene benzene is:

[0043] CF2=CF-Ph-X (a)

[0044] Where -Ph is a benzene ring, -X is a halogen element I, Br;

[0045] Halogenated perfluoroalkyl compounds are:

[0046] X-(CF2) n -X(b)

[0047] Wherein n is an integer greater than 2;

[0048] S1-1, under nitrogen protection, reacting 2-2.1 equivalents of 1-bromo-4-(1,2,2-trifluorovinyl)benzene with magnesium in anhydrous tetrahydrofuran solution to prepare a Grignard reagent;

[0049] S1-2, dissolving 1 equivalent of 1,6-diiodoperfluorohexane in anhydrous tetrahydrofuran solution under nitrogen protection, heating under reflux and stirring, slowly adding the Grignard reagent, and reacting to obtain a mixture solution containing a high temperature vapor resistant crosslinking agent;

[0050] S2, separating and purifying the mixture solution containing the high temperature steam resistant cross-linking agent to obtain the high temperature steam resistant cross-linking agent;

[0051] S2-1. Add saturated ammonium chloride to quench the reaction, extract with ethyl acetate, wash with saturated brine, dry and filter, and concentrate the crude product by rotary evaporation.

[0052] In one embodiment, in step S2, the purification method includes any one of extraction, ion exchange, adsorption, and distillation, or a combination thereof.

[0053] The embodiment provides a high temperature water vapor resistant crosslinking agent of formula C:

[0054] CF2=CF-Ph-(CF2) n -Ph-CF=CF2(C)

[0055] In the formula, n is an integer greater than 2.

[0056] The embodiment provides a high temperature steam resistant cross-linking agent, which is prepared by the above-mentioned preparation method of the high temperature steam resistant cross-linking agent.

[0057] like Figure 2 As shown, the embodiment provides a method for preparing a high temperature water vapor resistant perfluoroether elastomer composition, comprising the following steps:

[0058] Step 1, preparing a perfluoroether elastomer;

[0059] Step 1-1, 43-62 parts by mass of tetrafluoroethylene (TFE), 57-38 parts by mass of perfluoroalkyl vinyl ether (total 100 parts by mass), 0.5-2 parts by mass of non-conjugated fluorodiene vulcanization point monomer, 0.1-2 parts by mass of chain transfer agent, and 0.3-0.5 parts by mass of peroxy initiator are polymerized to obtain a perfluoroether elastomer emulsion, and then treated and dried to obtain a perfluoroether elastomer; wherein the fluorodiene is added in batches by a metering pump at the beginning and end of the reaction;

[0060] Step 2, preparing a perfluoroether elastomer composition, wherein the perfluoroether elastomer composition contains a high temperature resistant water vapor crosslinking agent;

[0061] Step 2-1, mixing 100 parts by mass of the perfluoroether elastomer described in step 1-1, 0.5-2 parts by mass of a high temperature steam resistant crosslinking agent, 0.5-2 parts by mass of a peroxide vulcanizing agent, and 1-50 parts by mass of a filler to obtain a crosslinked perfluoroether elastomer compound;

[0062] Step 2-2, the perfluoroether elastomer rubber compound is subjected to primary vulcanization molding at a temperature of 150-180° C., a pressure of 8-10 MPa, and a time of 10-20 min;

[0063] Step 2-3, using a combination of radiation vulcanization and high temperature vulcanization to secondary vulcanize the molded product to obtain a perfluoroether elastomer composition; wherein the radiation vulcanization dose is 100-200 kGy, the high temperature vulcanization is 240-280°C, and the time is 1-4 hr.

[0064] In one embodiment, the perfluoroether elastomer is obtained by emulsion polymerization, and the perfluoroether elastomer emulsion obtained by polymerization is flocculated, washed, and dried to obtain the perfluoroether elastomer.

[0065] In one embodiment, the perfluoroalkyl vinyl ether (PAVE) includes any one of perfluoromethyl vinyl ether (PMVE), perfluoroethyl vinyl ether (PEVE), and perfluoropropyl vinyl ether (PPVE).

[0066] In one embodiment, the non-conjugated fluorodiene curing site monomer structure is CH2=CH-(CF2)n-CH=CH2 (n is an integer greater than or equal to 2).

[0067] In one embodiment, the peroxy curing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane (hereinafter referred to as bis(2,5)), or 1,3-bis(tert-butylperoxide isopropyl)benzene.

[0068] In one embodiment, the peroxy initiator is potassium persulfate or ammonium persulfate.

[0069] In one embodiment, the chain transfer agent includes any one of methanol, methyl formate, tert-butyl acetate, methylene iodide, perfluoroalkyl iodide and 1,4-diiodoperfluoro-butane.

[0070] In one embodiment, the filler includes any one of carbon black, carbon nanotubes, graphene, silicon dioxide, titanium dioxide, semi-crystalline fluoropolymer, and perfluoropolymer, or a combination thereof.

[0071] Example 1

[0072] 1. Synthesis of 1-bromo-4-(1,2,2-trifluorovinyl)benzene

[0073] 4-Bromophenylboric acid (201g), tetrakis(triphenyl)phosphine palladium (11.5g), potassium phosphate (636g) were added to a reactor with an external condensation reflux jacket and a feed tube, and after adding 2000mL toluene solvent and an appropriate amount of water, a dry ice reflux device was connected to the reactor, and the air of the system was replaced by nitrogen N2. 5 times the equivalent of trifluorochloroethylene of 4-bromophenylboric acid was charged into the reactor, and then the reactor temperature was raised to above 95°C after opening the external condensation water. The reflux valve was opened under dry ice acetone bath conditions, trifluorochloroethylene was added, and dry ice was refluxed for 6 hours, and then a colorless liquid was obtained after passing through a column with normal hexane, with a yield of 80%.

[0074] 2. Synthesis of crosslinking agent CF2=CF-Ph-(CF2)6-Ph-CF=CF2

[0075] CF2=CF-Ph-MgX Grignard reagent synthesis

[0076] A 5L double-necked reactor equipped with a dry ice condenser is continuously introduced with nitrogen N2 to replace the air in the system, and 2L of dehydrated tetrahydrofuran (THF) solution (water content is less than 10ppm) is added. The tail gas is oil-sealed or a thin film is used to maintain a trace amount of N2 bubbling to prevent oxygen penetration. At room temperature, 200g of the 1-bromo-4-(1,2,2-trifluorovinyl)benzene (molecular weight 237.01) is reacted with a magnesium strip in an anhydrous tetrahydrofuran solution to prepare a Grignard reagent CF2=CF-Ph-MgX (molecular weight 261.32); set aside;

[0077] A 5L double-necked reactor equipped with a dry ice condenser was continuously introduced with nitrogen N2 to replace the air in the system, and 2L of anhydrous tetrahydrofuran solution (water content less than 10ppm) was added. The tail gas was oil-sealed or a thin film was used to maintain a trace amount of N2 bubbling to prevent oxygen penetration. 192.68g of 1,6-diiodoperfluorohexane (molecular weight 553.85) was dissolved in anhydrous tetrahydrofuran solution, heated under reflux and stirred, and the Grignard reagent was slowly added to react to obtain a mixture solution containing a high temperature resistant water vapor crosslinking agent, and the reaction was carried out for 16h;

[0078] After the reaction was completed, saturated ammonium chloride was added to quench the reaction, extracted with ethyl acetate, washed with saturated brine, dried and filtered, and the crude product was concentrated by rotary evaporation.

[0079] The concentrated crude product is dissolved in pentane, hexane or diethyl ether, and the target compound is extracted by decantation. The extract is concentrated and separated by a chromatographic column filled with silica gel using hexane as an eluent to obtain a high temperature resistant water vapor crosslinking agent (C).

[0080] 3. Emulsion polymerization of perfluoroether elastomer containing non-conjugated fluorodiolefin vulcanization point monomer

[0081] The perfluoroether elastomer contains 56.5 parts by mass of tetrafluoroethylene (TFE), 43.5 parts by mass of perfluoromethyl vinyl ether (PMVE) in a total of 100 parts by mass, 0.8 parts by mass of non-conjugated fluorodiolefin vulcanization point monomer, 0.5 parts by mass of chain transfer agent 1,4-diiodoperfluoro-butane, and 0.4 parts by mass of ammonium persulfate. The perfluoroether elastomer emulsion is obtained by polymerization, and then flocculated, washed, and dried to obtain the perfluoroether elastomer.

[0082] The non-conjugated fluorodiolefin vulcanization site monomer is added in batches by a metering pump during the beginning and end of the reaction, 1 / 10 is added each time, for a total of 10 times.

[0083] The main chain of perfluoroether elastomer does not contain double bonds or carbon-hydrogen CH bonds, and it is difficult to form a grid structure between the main chains of perfluoroether elastomer using ordinary cross-linking methods involving peroxides. Therefore, it is necessary to introduce curing sites - monomers containing reactive sites (such as nitrile groups, iodides and bromides) into perfluoroether elastomers. The heat resistance and high-temperature steam resistance of perfluoroether elastomers are determined by the cross-linking structure generated by the reaction of curing sites and additives.

[0084] 4. Preparation of high temperature water vapor resistant perfluoroether elastomer composition

[0085] Relative to 1000g of the perfluoroether elastomer, 5g of high temperature steam resistant crosslinking agent (C), 10g of peroxide vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butyl peroxide)hexane, and 150g of Cabot N990 carbon black were added and mixed to obtain a crosslinked perfluoroether elastomer compound.

[0086] After a vulcanization molding process at 170°C, 8 MPa, and heating for 15 minutes, an O-ring (type 214) with a wire diameter of 3.53 mm and an inner diameter of 24.99 mm was produced.

[0087] Secondary vulcanization is a combination of radiation vulcanization and high temperature vulcanization. First, radiation vulcanization is performed with a radiation dose of 150 kGy, and then high temperature vulcanization is performed in air at 260°C for 4 hours.

[0088] 5. Performance Testing

[0089] The 214-type O-ring made of the perfluoroether elastomer composition was evaluated as follows:

[0090] 1) Heat resistance

[0091] The mass loss rate of the 214 type O-ring was measured before and after being exposed to an atmosphere at 300°C for 70 hours, and the changes in appearance were recorded at the same time.

[0092]

[0093] 2) Mass swelling change rate

[0094] The method is shown in Senhuan Enterprise Standard Q / SMS 006-2024 Test Method for Swelling of Perfluoro Seals by Fluorinated Liquids for Electronics. Determine the mass change rate of the 214-type O-ring before and after immersion in perfluoroalkyl fluorinated liquid (Fluorinert FC-3283) at room temperature (21-25°C) for 70 hours:

[0095]

[0096] 3) Steam resistance test (300°C)

[0097] The method is shown in Senhuan Enterprise Standard Q / SMS 005-2024 Test Method for Water Vapor Corrosion Resistance of Perfluoroether Elastomer Seals for Semiconductor Equipment. Expose the 214 type O-ring to saturated water vapor at 300°C for 24 hours, and measure the mass change rate before and after the test:

[0098]

[0099] 4) Resistance to plasma etching

[0100] For the plasma etching resistance method, please refer to Senhuan Enterprise Standard Q / SMS 001-2024 Plasma Etching Resistance Test Method for Perfluoroether Rubber Seals.

[0101] Experimental conditions: The ICP test conditions are radio frequency 13.56 MHz, flow rate 50 standard cubic centimeters per minute (sccm), pressure 500 mTorr (mt), power 800 W, gas is O2, and the balance gas is N2.

[0102] 5) Compression set (300°C) and mechanical properties.

[0103] The triazine ring crosslinked structure has good heat resistance, but its upper limit to steam temperature is not more than 100°C. On the other hand, the fluorinated diene crosslinked structure has both high heat resistance and steam resistance, but its upper limit to the use temperature is 280°C.

[0104] In order to develop a perfluoroether elastomer sealing material that is resistant to steam at temperatures above 300°C, a new cross-linking structure is required. This cross-linking structure must have excellent resistance to high-temperature steam so that the cross-linking agent and the perfluoroether elastomer can cross-link efficiently. In addition, it is also necessary to consider that the cross-linking agent has few side reactions, good dispersibility in the perfluoroether elastomer, and can undergo an effective cross-linking reaction.

[0105] The present invention uses non-conjugated fluorodiolefin vulcanization point monomers and adds a synthetic high-temperature resistant water vapor crosslinking agent (C) during mixing to prepare a perfluoroether elastomer composition product that has both high heat resistance and steam resistance, and its upper limit of use temperature can reach 300°C.

[0106] The test results are summarized in Table 1.

[0107] Example 2

[0108] Steps 1-3, Example 2 are the same as Example 1.

[0109] Step 4, preparing a perfluoroether elastomer composition

[0110] To 1000 g of the perfluoroether elastomer, 10 g of a high temperature steam resistant crosslinking agent (C), 10 g of a peroxide vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, and 150 g of Cabot N990 carbon black were added and kneaded to obtain a crosslinked perfluoroether elastomer.

[0111] Step 5 is the same as Step 5 of Example 1.

[0112] Example 3

[0113] Steps 1-3, Example 3 are the same as Example 1.

[0114] Step 4, preparing a perfluoroether elastomer composition

[0115] To 1000 g of the perfluoroether elastomer, 15 g of a high temperature steam resistant crosslinking agent (C), 10 g of a peroxide vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, and 150 g of Cabot N990 carbon black were added and kneaded to obtain a crosslinked perfluoroether elastomer.

[0116] Step 5 is the same as Step 5 of Example 1.

[0117] Example 4

[0118] Steps 1-2, Example 5 are the same as Example 1.

[0119] Step 3. Emulsion polymerization of perfluoroether elastomer containing non-conjugated fluorodiolefin cure site monomer

[0120] The perfluoroether elastomer contains 56.5 parts by mass of tetrafluoroethylene (TFE), 43.5 parts by mass of perfluoromethyl vinyl ether (PMVE) (totaling 100 parts by mass), 1.5 parts by mass of non-conjugated fluorodiolefin vulcanization point monomer, 0.5 parts by mass of chain transfer agent 1,4-diiodoperfluoro-butane, and 0.4 parts by mass of ammonium persulfate. The perfluoroether elastomer emulsion is obtained by polymerization, and then flocculated, washed, and dried to obtain the perfluoroether elastomer.

[0121] Step 4: With respect to 1000 g of the perfluoroether elastomer of Example 1, add 5 g of a high temperature steam resistant crosslinking agent (C), 10 g of a peroxide vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butyl peroxide)hexane, and 150 g of Capote N990 carbon black, and mix and knead to obtain a crosslinked perfluoroether elastomer compound.

[0122] Step 5 is the same as Example 5 of Example 1.

[0123] Example 5

[0124] Steps 1-3, Example 5 are the same as Example 4.

[0125] Step 4, preparing a perfluoroether elastomer composition

[0126] To 1000 g of the perfluoroether elastomer, 10 g of a high temperature steam resistant crosslinking agent (C), 10 g of a peroxide vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, and 150 g of Cabot N990 carbon black were added and kneaded to obtain a crosslinked perfluoroether elastomer.

[0127] Step 5 is the same as Step 5 of Example 1.

[0128] Example 6

[0129] Steps 1-3, Example 6 are the same as Example 4.

[0130] 4. Preparation of perfluoroether elastomer composition

[0131] To 1000 g of the perfluoroether elastomer, 15 g of a high temperature steam resistant crosslinking agent (C), 10 g of a peroxide vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, and 150 g of Cabot N990 carbon black were added and kneaded to obtain a crosslinked perfluoroether elastomer.

[0132] Step 5 is the same as Step 5 of Example 1.

[0133] Comparative Example 1

[0134] Steps 1-3, Comparative Example 1 are the same as Example 1.

[0135] 4. Preparation of perfluoroether elastomer composition

[0136] 20 g of a peroxide curing agent 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane and 150 g of Cabot N990 carbon black were added to 1000 g of the perfluoroether elastomer, and the mixture was kneaded to obtain a cross-linked perfluoroether elastomer.

[0137] Step 5 is the same as Step 5 of Example 1.

[0138] Comparative Example 2

[0139] Steps 1-3, Comparative Example 2 are the same as Example 4.

[0140] 4. Preparation of perfluoroether elastomer composition

[0141] 20 g of a peroxide curing agent 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane and 150 g of Cabot N990 carbon black were added to 1000 g of the perfluoroether elastomer, and the mixture was kneaded to obtain a cross-linked perfluoroether elastomer.

[0142] Step 5 is the same as Step 5 of Example 1.

[0143] Table 1 Main properties of Examples 1-6 and Comparative Examples 1-2

[0144]

[0145] Regarding the evaluation of the appearance, a case where no change was observed was recorded as “no change”, and a case where dissolution was observed but the shape did not change was recorded as “slightly dissolved”.

[0146] As can be seen from Table 1, Examples 1-6 show a significant improvement in water vapor resistance. Compared with Comparative Examples 1-2, the water vapor resistance change rate calculated by equation (3) is reduced from 7.1-7.3% to 3.1-4.3%.

[0147] Among them, the number of parts by mass of the cross-linking agent resistant to high temperature water vapor is related to the water vapor resistance and tensile strength. The more parts by mass of the cross-linking agent resistant to high temperature water vapor, the smaller the mass reduction rate, mass swelling rate and steam resistance change rate of the perfluoroether elastomer composition, and the greater the tensile strength.

[0148] The non-conjugated fluorodiolefin vulcanization point monomers in Examples 1-3 are all 0.8 parts by mass, and the non-conjugated fluorodiolefin vulcanization point monomers in Examples 4-6 are all 1.5 parts by mass. As the amount of high temperature water vapor resistant cross-linking agent increases, the mass loss rate and the water vapor resistance change rate decrease, and the tensile strength value increases.

[0149] It can also be seen from Table 1 that the amount of non-conjugated fluorodiolefin vulcanization point monomer used is related to the mass loss rate, water vapor resistance change rate and tensile strength value. The mass loss rate and water vapor resistance change rate of a large amount of non-conjugated fluorodiolefin vulcanization point monomer are smaller than those of a small amount, while the tensile strength value becomes larger. This indicates that the amount of non-conjugated fluorodiolefin vulcanization point monomer and high temperature water vapor resistant crosslinking agent (C) is closely related to the mass reduction rate, mass swelling rate and steam resistance change rate of the perfluoroether elastomer composition.

[0150] Among them, the best performance is Example 6, in which the values ​​of the non-conjugated fluorodiolefin vulcanization point monomer and the high temperature water vapor resistant crosslinking agent (C) are the largest.

[0151] Comparative Examples 1 and 2 did not use a high temperature water vapor resistant crosslinking agent, and the appearance evaluation was "a little dissolved", indicating that they did not have the performance of 300°C water vapor resistance. The appearance evaluation of Examples 1 to 6 was "no change", and they had the performance of 300°C water vapor resistance, indicating that the perfluoroether elastomer and the high temperature water vapor resistant crosslinking agent (C) produced efficient crosslinking, so that the perfluoroether elastomer composition product had the performance of 300°C water vapor resistance.

[0152] Compared with Example 1 and Example 4, the mass loss rate and water vapor resistance change rate of Comparative Examples 1 and Comparative Examples 2 are greater than those in Example 1 and Example 4, while the tensile strength value is smaller than that in Example 1 and Example 4, which is also related to the fact that no high temperature resistant water vapor cross-linking agent is used.

[0153] In Comparative Examples 1 and 2, the mass loss rate and the water vapor resistance change rate of the non-conjugated fluorodiolefin vulcanization point monomer with a large dosage are smaller than those with a small dosage, while the tensile strength value becomes larger, which also illustrates the effect of the dosage of the non-conjugated fluorodiolefin vulcanization point monomer.

[0154] The above data can illustrate that in this embodiment, based on the use of non-conjugated fluorodiolefin vulcanization point monomers, a synthetic high-temperature steam-resistant crosslinking agent (C) is added during mixing. The efficient crosslinking structure of the crosslinking agent and the perfluoroether elastomer has excellent resistance to high-temperature steam. The finally obtained perfluoroether elastomer composition product has both high heat resistance and steam resistance, and its upper limit of use temperature is 300°C.

[0155] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for preparing a high temperature steam resistant crosslinking agent, characterized in that: The following steps are involved: S1, preparing a tetrahydrofuran solution of a halogenated trifluoroethylene benzene Grignard reagent, and reacting the solution with a halogenated perfluoroalkyl compound to synthesize a mixture solution containing a high temperature resistant water vapor cross-linking agent; S2. Separating and purifying the mixture solution containing the high temperature resistant water vapor cross-linking agent to obtain the high temperature resistant water vapor cross-linking agent.

2. The method for preparing a high temperature resistant water vapor crosslinking agent according to claim 1, characterized in that: S1 also includes: S1-1, under nitrogen protection, reacting 2-2.1 equivalents of 1-bromo-4-(1,2,2-trifluorovinyl)benzene with magnesium in anhydrous tetrahydrofuran solution to prepare a Grignard reagent; S1-2. Dissolve 1 equivalent of 1,6-diiodoperfluorohexane in anhydrous tetrahydrofuran solution under nitrogen protection, heat under reflux and stir, slowly add the Grignard reagent, and react to obtain a mixture solution containing a high temperature resistant water vapor cross-linking agent.

3. A high temperature steam resistant crosslinking agent, characterized in that: The high temperature resistant water vapor crosslinking agent is prepared by the preparation method of claim 1 or 2, wherein the chemical formula of the high temperature resistant water vapor crosslinking agent is: CF2=CF-Ph-(CF2) n -Ph-CF=CF2 Wherein Ph is the abbreviation of phenyl; n is an integer greater than 2.

4. A method for preparing a high temperature water vapor resistant perfluoroether elastomer composition, characterized in that: The following steps are involved: Step 1, preparing a perfluoroether elastomer; Step 1-1, polymerizing 43-62 parts by mass of tetrafluoroethylene (TFE), 57-38 parts by mass of perfluoroalkyl vinyl ether (total 100 parts by mass), 0.5-2 parts by mass of non-conjugated fluorodiene vulcanization point monomer, 0.1-2 parts by mass of chain transfer agent, and 0.3-0.6 parts by mass of peroxy initiator to obtain a perfluoroether elastomer emulsion, and coagulating, washing, and drying to obtain a perfluoroether elastomer; wherein the fluorodiene is added in batches by a metering pump at the beginning and end of the reaction; Step 2, preparing a perfluoroether elastomer composition, wherein the perfluoroether elastomer composition contains the high temperature steam resistant crosslinking agent as claimed in claim 3; Step 2-1, mixing 100 parts by mass of the perfluoroether elastomer described in step 1-1, 0.5-2 parts by mass of a high temperature steam resistant crosslinking agent, 0.5-2 parts by mass of a peroxide vulcanizing agent, and 1-50 parts by mass of a filler to obtain a crosslinked perfluoroether elastomer compound; Step 2-2, the perfluoroether elastomer rubber compound is subjected to primary vulcanization molding at a temperature of 150-180° C., a pressure of 8-10 MPa, and a time of 10-20 min; Step 2-3, using a combination of radiation vulcanization and high temperature vulcanization to secondary vulcanize the molded product to obtain a perfluoroether elastomer composition; wherein the radiation vulcanization dose is 100-200 kGy, the high temperature vulcanization temperature is 240-280°C, and the time is 1-4 hr.

5. The method for preparing the high temperature water vapor resistant perfluoroether elastomer composition according to claim 4, characterized in that: In step 1-1, the perfluoroalkyl vinyl ether includes any one of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether and perfluoropropyl vinyl ether.

6. The method for preparing the high temperature water vapor resistant perfluoroether elastomer composition according to claim 4, characterized in that: In step 1-1, the non-conjugated fluorodiolefin curing site monomer structure is CH2=CH-(CF2)n-CH=CH2 n is an integer greater than or equal to 2.

7. The method for preparing the high temperature water vapor resistant perfluoroether elastomer composition according to claim 4, characterized in that: In step 1-1, the chain transfer agent includes any one of methanol, methyl formate, tert-butyl acetate, methylene iodide, perfluoroalkyl iodide and 1,4-diiodoperfluoro-butane; and the peroxy initiator is potassium persulfate or ammonium persulfate.

8. The method for preparing the high temperature water vapor resistant perfluoroether elastomer composition according to claim 4, characterized in that: In step 2-1, the peroxide vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane or 1,3-bis(tert-butylperoxide isopropyl)benzene.

9. The method for preparing the high temperature water vapor resistant perfluoroether elastomer composition according to claim 4, characterized in that: In step 2-1, the filler includes any one of carbon black, carbon nanotubes, graphene, silicon dioxide, titanium dioxide, semi-crystalline fluoropolymer, and perfluoropolymer, or a combination thereof.

10. A high temperature water vapor resistant perfluoroether elastomer composition, characterized in that: The composition is prepared by the method for preparing the high temperature steam resistant perfluoroether elastomer composition according to any one of claims 4 to 9.

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