A method for synthesizing perfluoroether rubber with a wide temperature range

Abstract

The present invention relates to the technical field of polymer synthesis, and discloses a method for synthesizing a wide-temperature range perfluoroether rubber. The present invention effectively enhances the flexibility and stability of the rubber molecular chain by regulating the mass ratio of tetrafluoroethylene to perfluoromethoxyethyl vinyl ether and adding an appropriate amount of modified monomer perfluoromethyl vinyl ether. At the same time, the cross-linking structure of the rubber is optimized by using a chain transfer agent coupled with fluoroethanol and perfluoropropaneoxysilane, as well as a specific vulcanization point monomer, so that it can maintain good mechanical properties and chemical resistance in both high and low temperature environments; the prepared perfluoroether rubber has excellent tensile strength, elongation and hardness, and a wide temperature range, and can work stably under extreme temperature conditions. In addition, the rubber also exhibits excellent resistance to heat air aging, meeting the needs of a wider range of application scenarios.

Description

Technical Field

[0001] The invention relates to the technical field of polymer synthesis, in particular to a method for synthesizing perfluoroether rubber with a wide temperature range. Background Art

[0002] Perfluoroether rubber is a special rubber material with excellent chemical resistance, high and low temperature resistance and high mechanical strength. It is widely used in aerospace, automotive, petrochemical and nuclear industries. However, traditional perfluoroether rubber synthesis methods often face the problem of temperature range limitations, that is, under extreme high and low temperature environments, its performance will drop significantly and cannot meet the needs of specific application scenarios.

[0003] Specifically, the traditional synthesis of perfluoroether rubber mainly relies on the polymerization reaction of monomers such as tetrafluoroethylene (TFE) and perfluoromethoxyethyl vinyl ether (PFMOEVE). These monomers can form perfluoroether rubber with excellent performance through a specific polymerization process, but the stability and mobility of its molecular chain will be seriously affected in high or low temperature environments, resulting in a decrease in the elasticity, strength and chemical resistance of the rubber. Therefore, a method for synthesizing perfluoroether rubber with a wide temperature range is proposed. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for synthesizing perfluoroether rubber with a wide temperature range to solve the background technical problems.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for synthesizing a wide temperature range perfluoroether rubber, comprising the following steps:

[0006] Tetrafluoroethylene and perfluoromethoxyethyl vinyl ether are selected as main monomers in a mass ratio of (20-40): (60-80), and a modified monomer perfluoromethyl vinyl ether is added to the main monomers in an amount of 5-10% of the total mass of the monomers;

[0007] A preparation prepared by coupling fluoroethanol and perfluoropropoxysilane in a molar ratio of 1:1 is selected as a chain transfer agent;

[0008] One or more of perfluoro-4-bromo-1-butene, perfluoroethyl bromide vinyl ether, perfluoroethyl iodide vinyl ether, perfluoro-4-iodo-1-butene, trifluoroethylene iodide or trifluoroethylene bromide are selected as the vulcanization site monomers;

[0009] The tetrafluoroethylene, perfluoromethoxyethyl vinyl ether, modified monomer perfluoromethyl vinyl ether, chain transfer agent and vulcanization point monomer are polymerized through polymerization reaction to obtain a preliminary perfluoroether rubber;

[0010] The vulcanization point monomers in the preliminary perfluoroether rubber are treated as crosslinking points to obtain the perfluoroether rubber.

[0011] Preferably, the polymerization reaction specifically comprises the following steps:

[0012] Adding deionized water, pH buffer and emulsifier into a polymerization reactor;

[0013] Add the tetrafluoroethylene, perfluoromethoxyethyl vinyl ether, modified monomer perfluoromethyl vinyl ether, chain transfer agent and vulcanization site monomer into a reaction kettle, and adjust the pressure in the reaction kettle to 1-3 MPa;

[0014] Heat the reactor to 80-110°C, add initiator, and initiate polymerization;

[0015] During the reaction, the pressure in the reactor was maintained stable by continuously replenishing tetrafluoroethylene;

[0016] After the polymerization reaction has been carried out for a predetermined time, the polymerization product is taken out from the reactor, condensed, and then washed and dried to obtain a preliminary perfluoroether rubber.

[0017] Preferably, the vulcanization treatment is specifically performed by using a dual 25+TAIC vulcanization system to vulcanize the obtained preliminary perfluoroether rubber, the vulcanization temperature is 180-220° C., and the vulcanization time is 10-30 minutes to obtain the perfluoroether rubber.

[0018] Preferably, the method further comprises subjecting the obtained perfluoroether rubber to surface modification treatment using non-thermal equilibrium plasma technology in an oxygen or nitrogen atmosphere to introduce polar functional groups.

[0019] Preferably, the amount of the vulcanization point monomer added is controlled within the range of 0.5-3% of the total mass of tetrafluoroethylene and perfluoromethoxyethyl vinyl ether to ensure that the rubber material has suitable crosslinking density and mechanical properties.

[0020] Preferably, the amount of the chain transfer agent added is controlled within the range of 0.1-1% of the total mass of the obtained perfluoroether rubber to achieve regulation of the molecular weight.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention effectively enhances the flexibility and stability of the rubber molecular chain by adjusting the mass ratio of tetrafluoroethylene to perfluoromethoxyethyl vinyl ether and adding an appropriate amount of modified monomer perfluoromethyl vinyl ether. At the same time, the cross-linking structure of the rubber is optimized by using a chain transfer agent coupled with fluoroethanol and perfluoropropaneoxysilane, as well as a specific vulcanization point monomer, so that it can maintain good mechanical properties and chemical resistance in both high and low temperature environments; the prepared perfluoroether rubber has excellent tensile strength, elongation and hardness, and a wide temperature range, and can work stably under extreme temperature conditions. In addition, the rubber also exhibits excellent resistance to hot air aging, meeting the needs of a wider range of application scenarios.

[0023] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a flow chart of the synthesis method of the wide temperature range perfluoroether rubber. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this technical field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment describes in detail a method for synthesizing a wide temperature range perfluoroether rubber.

[0028] Main monomer selection and mass ratio:

[0029] Tetrafluoroethylene (TFE) and perfluoromethoxyethyl vinyl ether (PFMVE) were selected as main monomers, with a mass ratio of 20:80. A modified monomer perfluoromethyl vinyl ether (PMVE) accounting for 8% of the total weight of the monomers was added to the main monomers.

[0030] Chain transfer agent selection:

[0031] A preparation prepared by coupling fluoroethanol and perfluoropropoxysilane in a molar ratio of 1:1 was selected as a chain transfer agent, and the added amount was controlled to be 0.5% of the total mass of the obtained perfluoroether rubber.

[0032] Vulcanization point monomer selection:

[0033] Perfluoro-4-bromo-1-butene was selected as the vulcanization point monomer, and the added amount was controlled to be 1.5% of the total mass of tetrafluoroethylene and perfluoromethoxyethyl vinyl ether.

[0034] Synthesis steps:

[0035] In a 5 L stainless steel reactor with a stirrer, 3 L of deionized water, 2 g of a pH buffer (dipotassium hydrogen phosphate) and 2 g of an emulsifier (perfluoropolyether peroxide) were added.

[0036] The reactor was vacuumed, and then 800 g of PFMVE and 160 g of TFE (total mass was 960 g, meeting the mass ratio requirement) and 80 g of PMVE (accounting for 8% of the total mass of the monomers) were added into the reactor using a metering pump.

[0037] Add chain transfer agent, raise the temperature to 95°C, and continue to add TFE monomer to raise the pressure to 2MPa.

[0038] The vulcanization point monomer is introduced by a metering pump, and azobisisobutyronitrile is added as an initiator in a 12% (wt) aqueous solution to initiate the polymerization reaction.

[0039] After the polymerization reaction started, TFE monomer was added to the reactor every time the reactor pressure dropped by 0.01 MPa to maintain the pressure in the reactor at 2 MPa.

[0040] When TFE is continuously fed to a predetermined value, the reaction is stopped to obtain a perfluoroether rubber latex.

[0041] The perfluoroether rubber latex is condensed by an aqueous solution of aluminum sulfate to form solid particles. The condensed rubber particles are then washed with ethanol to remove impurities and unreacted monomers attached to the surface. The particles are then dried in a vacuum drying oven at 90°C and -0.08MPa for 16 hours to obtain a raw rubber product.

[0042] The raw rubber is vulcanized using a double 25+TAIC vulcanization system at a vulcanization temperature of 200°C and a vulcanization time of 20 minutes.

[0043] The vulcanized rubber was surface modified by introducing polar functional groups in a nitrogen atmosphere using non-thermal equilibrium plasma technology.

[0044] Example 2

[0045] This embodiment is similar to Embodiment 1, but the mass ratio of the main monomers is 30:70, the vulcanization point monomer is selected as perfluoro-4-iodo-1-butene, the addition amount of the chain transfer agent is controlled to 0.5% of the total mass of the obtained perfluoroether rubber, and the other steps and conditions are the same as in Embodiment 1.

[0046] Example 3

[0047] This embodiment is similar to Embodiment 1, but the mass ratio of the main monomers is 40:60, the pressure during the polymerization reaction is maintained at 2.5 MPa, the vulcanization point monomer is selected as trifluoroethylene iodide, the amount of chain transfer agent added is controlled to be 1% of the total mass of the obtained perfluoroether rubber, and after the vulcanization treatment, the rubber is subjected to non-thermal equilibrium plasma surface modification treatment in an oxygen atmosphere, and the other steps and conditions are the same as in Embodiment 1.

[0048] Example 4

[0049] In this embodiment, based on the embodiment 3, the addition amount of the modified monomer PMVE is increased to 10% of the total weight of the monomers, and the other steps and conditions are the same as those in the embodiment 3.

[0050] Example 5

[0051] In this embodiment, based on Example 4, the mass ratio of the comonomers is adjusted, that is, the mass ratio of TFE, PFMVE and PMVE is 35:55:10, and perfluoroethyl bromide vinyl ether is selected as the vulcanization point monomer, and a non-thermal equilibrium plasma surface modification treatment is carried out under a nitrogen atmosphere. The other steps and conditions are the same as those in Example 4.

[0052] Comparative Example 1

[0053] This comparative example is similar to Example 1, but the mass ratio of the main monomers is 10:90, and the modified monomer PMVE and the vulcanization site monomer are not added. The amount of chain transfer agent added is the same as that in Example 1, and the other steps and conditions are the same as those in Example 1.

[0054] Comparative Example 2

[0055] This comparative example is similar to Example 1, but the pressure during the polymerization reaction is maintained at 0.5 MPa, which is much lower than the pressure in Example 1. Other steps and conditions are the same as in Example 1.

[0056] Comparative Example 3

[0057] This comparative example selected a different emulsifier (such as sodium lauryl sulfate) and omitted the addition of a chain transfer agent. Other steps and conditions were the same as those in Example 1.

[0058] Comparative Example 4

[0059] This comparative example is similar to Example 3, but the sulfurization step is omitted. Other steps and conditions are the same as those in Example 3.

[0060] The rubber products prepared in the above-mentioned Examples 1 to 5 and Comparative Examples 1 to 4 were tested, wherein the tensile strength and elongation were tested according to the ASTM D638 test standard, the hardness was tested according to the ASTM D2240 test standard, the glass transition temperature was tested according to the ASTM E1356 test standard, and the strength retention rate after hot air aging was tested according to the ASTM D573 test standard. The specific test results are shown in Table 1 below;

[0061] Table 1

[0062]

[0063]

[0064] From the comparison of the test results of the above embodiments and comparative examples, it can be seen that the method for synthesizing a wide-temperature range perfluoroether rubber proposed in the present invention can prepare a perfluoroether rubber with excellent performance and meet the needs of more application scenarios.

Claims

1. A method for synthesizing a wide temperature range perfluoroether rubber, characterized in that: The following steps are involved: Tetrafluoroethylene and perfluoromethoxyethyl vinyl ether are selected as main monomers in a mass ratio of (20-40): (60-80), and a modified monomer perfluoromethyl vinyl ether is added to the main monomers in an amount of 5-10% of the total mass of the monomers; A preparation prepared by coupling fluoroethanol and perfluoropropoxysilane in a molar ratio of 1:1 is selected as a chain transfer agent; One or more of perfluoro-4-bromo-1-butene, perfluoroethyl bromide vinyl ether, perfluoroethyl iodide vinyl ether, perfluoro-4-iodo-1-butene, trifluoroethylene iodide or trifluoroethylene bromide are selected as the vulcanization site monomers; The tetrafluoroethylene, perfluoromethoxyethyl vinyl ether, modified monomer perfluoromethyl vinyl ether, chain transfer agent and vulcanization point monomer are polymerized through polymerization reaction to obtain a preliminary perfluoroether rubber; The vulcanization point monomers in the preliminary perfluoroether rubber are treated as crosslinking points to obtain the perfluoroether rubber.

2. The method for synthesizing a wide temperature range perfluoroether rubber according to claim 1, characterized in that: The polymerization reaction specifically comprises the following steps: Adding deionized water, pH buffer and emulsifier into a polymerization reactor; Add the tetrafluoroethylene, perfluoromethoxyethyl vinyl ether, modified monomer perfluoromethyl vinyl ether, chain transfer agent and vulcanization site monomer into a reaction kettle, and adjust the pressure in the reaction kettle to 1-3 MPa; Heat the reactor to 80-110°C, add initiator, and initiate polymerization; During the reaction, the pressure in the reactor was maintained stable by continuously replenishing tetrafluoroethylene; After the polymerization reaction has been carried out for a predetermined time, the polymerization product is taken out from the reactor, condensed, and then washed and dried to obtain a preliminary perfluoroether rubber.

3. The method for synthesizing a wide temperature range perfluoroether rubber according to claim 2, characterized in that: The vulcanization treatment is specifically carried out by using a double 25+TAIC vulcanization system to vulcanize the obtained preliminary perfluoroether rubber, the vulcanization temperature is 180-220° C., and the vulcanization time is 10-30 minutes to obtain the perfluoroether rubber.

4. The method for synthesizing a wide temperature range perfluoroether rubber according to claim 3, characterized in that: The method also includes the step of performing surface modification treatment on the obtained perfluoroether rubber in an oxygen or nitrogen atmosphere by using a non-thermal equilibrium plasma technology to introduce polar functional groups.

5. The method for synthesizing a wide temperature range perfluoroether rubber according to claim 1, characterized in that: The added amount of the vulcanization point monomer is controlled within the range of 0.5-3% of the total mass of tetrafluoroethylene and perfluoromethoxyethyl vinyl ether to ensure that the rubber material has suitable crosslinking density and mechanical properties.

6. The method for synthesizing a wide temperature range perfluoroether rubber according to claim 1, characterized in that: The added amount of the chain transfer agent is controlled within the range of 0.1-1% of the total mass of the obtained perfluoroether rubber to achieve molecular weight regulation.

Images