PERFLUOROETHER FLUORORUBBER AND PREPARATION METHOD THEREFOR AND USE THEREOF

Abstract

The present invention provides a perfluoroether fluororubber and a preparation method therefor and use thereof. The perfluoroether fluororubber is prepared by a stepwise polymerization method, wherein polymerization monomers in each step of polymerization comprise tetrafluoroethylene and a perfluoroalkyl vinyl ether. The preparation method for the perfluoroether fluororubber provided in the present invention can shorten polymerization time and improve production efficiency, and the finally obtained perfluoroether fluororubber is good in processability, high in strength, low in hardness and compression deformation and good in medium resistance.

Claims

1. A preparation method for a perfluoroether fluororubber, wherein the perfluoroether fluororubber is prepared by a stepwise polymerization method; wherein, the polymerization monomers in each step of polymerization comprise tetrafluoroethylene and a perfluoroalkyl vinyl ether.

2. The preparation method according to claim 1, wherein the polymerization monomers in each step of polymerization further comprise a vulcanization point monomer, preferably the vulcanization point monomer is a perfluoroiodoolefin; preferably, the stepwise polymerization method is a three-step polymerization method, comprising: (1) subjecting pre-polymerization monomers composed of a vulcanization point monomer, tetrafluoroethylene and a perfluoroalkyl vinyl ether to a pre-polymerization reaction; (2) further adding mid-polymerization monomers composed of a vulcanization point monomer, tetrafluoroethylene and a perfluoroalkyl vinyl ether for a mid-polymerization reaction; and (3) further adding post-polymerization monomers composed of a vulcanization point monomer, tetrafluoroethylene and a perfluoroalkyl vinyl ether for a post-polymerization reaction, and collecting the reaction product.

3. The preparation method according to claim 2, wherein the molar ratio of the vulcanization point monomer, tetrafluoroethylene and the perfluoroalkyl vinyl ether in the pre-polymerization monomers is (1-3):(60-70):(30-40); the molar ratio of the vulcanization point monomer, tetrafluoroethylene and the perfluoroalkyl vinyl ether in the mid-polymerization monomers is (0.1-1):(35-55):(40-65); the molar ratio of the vulcanization point monomer, tetrafluoroethylene and the perfluoroalkyl vinyl ether in the post-polymerization monomers is (1-3):(60-70):(30-40); based on 100% of the total mole number of the pre-polymerization monomers, the content of the vulcanization point monomer is 1-3%, the content of tetrafluoroethylene is 60-70%, and the content of the perfluoroalkyl vinyl ether is 30-40%; based on 100% of the total mole number of the mid-polymerization monomers, the content of the vulcanization point monomer is 0.1-1%, the content of tetrafluoroethylene is 35-55%, and the content of the perfluoroalkyl vinyl ether is 40-65%; and based on 100% of the total mole number of the post-polymerization monomers, the content of the vulcanization point monomer is 1-3%, the content of tetrafluoroethylene is 60-70%, and the content of the perfluoroalkyl vinyl ether is 30-40%.

4. The preparation method according to claim 3, wherein the mass ratio of the pre-polymerization monomers, the mid-polymerization monomers and the post-polymerization monomers is (20-35):(30-60):(20-35); preferably, the pre-polymerization monomers account for 20-35% of the total mass of the polymerization monomers, the mid-polymerization monomers account for 30-60% of the total mass of the polymerization monomers, and the post-polymerization monomers account for 20-35% of the total mass of the polymerization monomers.

5. The preparation method according to claim 4, wherein the mass of the post-polymerization monomers is the same as that of the pre-polymerization monomers; preferably, the proportion of each component in the post-polymerization monomers is the same as that in the pre-polymerization monomers.

6. The preparation method according to claim 2, wherein the total polymerization time of the stepwise polymerization method is 2-4 h; and/or the polymerization pressures of the pre-polymerization reaction and the post-polymerization reaction are each independently selected from the range of 2.8-3.5 MPa, the polymerization pressure of the mid-polymerization reaction is 1.6-2.5 MPa; and/or the reaction temperatures of the pre-polymerization reaction, the mid-polymerization reaction and the post-polymerization reaction are each independently selected from the range of 60-95° C.; and/or before adding the mid-polymerization monomers, unreacted pre-polymerization monomers are recovered, preferably before adding the post-polymerization monomers, unreacted mid-polymerization monomers are recovered; and/or the preparation method further comprises recovery of unreacted post-polymerization monomers in the reaction product obtained in step (3), and an emulsion containing the perfluoroether fluororubber being obtained.

7. The preparation method according to claim 2, wherein the stepwise polymerization method uses water as a dispersion medium; and/or the system of the pre-polymerization reaction further comprises an initiator, preferably the initiator is any one or a combination of at least two of ammonium persulfate, potassium persulfate or potassium permanganate, preferably, based on 100 parts by weight of the aqueous medium, the dosage of the initiator is 0.0001-8 parts by weight; and/or the system of the pre-polymerization reaction further comprises a perfluorooctanoate as an emulsifier, preferably, based on 100 parts by weight of the aqueous medium, the dosage of the emulsifier is 0.01-5 parts by weight; and/or the system of the pre-polymerization reaction further comprises a chain transfer agent, preferably the chain transfer agent is any one or a combination of at least two of 1,2-diiodoperfluoroethane, 1,3-diiodoperfluoropropane or 1,4-diiodoperfluorobutane, preferably, based on the total mass of the polymerization monomers, the dosage of the chain transfer agent is 0.01-5%.

8. The preparation method according to claim 2, wherein the preparation method comprises the following steps: (1) adding deionized water to a reactor, vacuumizing to an oxygen content of ≤30 ppm, then adding an emulsifier, and heating to 60-95° C.; (2) adding the pre-polymerization monomers, increasing the pressure of the reactor to 2.8-3.5 MPa, then adding an initiator and a chain transfer agent to carry out the pre-polymerization reaction; when the added amount of the pre-polymerization monomers being 20-35% of the total mass of the polymerization monomers, recovering unreacted monomers; (3) adding the mid-polymerization monomers, then reducing the pressure to 1.6-2.5 MPa to carry out the mid-polymerization reaction, when the added amount of the mid-polymerization monomers is 30-85% of the total mass of the polymerization monomers, recovering unreacted monomers; (4) adding the post-polymerization monomers, then increasing the pressure to 2.8-3.5 MPa to carry out the post-polymerization reaction; when the added amount of the post-polymerization monomers being 20-35% of the total mass of the polymerization monomers, recovering unreacted monomers, and an emulsion containing the perfluoroether fluororubber being obtained; and (5) the emulsion being agglomerated, washed and dried to provide the perfluoroether fluororubber.

9. A perfluoroether fluororubber prepared by the preparation method according to claim 1.

10. Use of the perfluoroether fluororubber according to claim 9 in petrochemical materials, automotive industrial materials, semiconductor materials, aerospace materials or device materials.

Description

BEST MODE

[0058] The technical solutions of the present invention are further explained by the following specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as a specific limitation of the present invention.

Example 1

[0059] A preparation method of perfluoroether fluororubber compreses steps of: [0060] (1) adding 30 L of deionized water to a 50 L reactor, vacuumizing to an oxygen content of ≤30 ppm, adding 35 g of ammonium perfluorooctanoate, and heating the contents in the reactor to 85° C.; [0061] (2) feeding pre-polymerization monomers composed of I(CF.sub.2).sub.2OCF═CF.sub.2, TFE and perfluoromethyl vinyl ether with a molar ratio of 1:60:39, increasing the pressure of the reactor to 3.0 MPa, adding 15 g of potassium persulfate and 25 g of 1,2-diiodoperfluoroethane to carry out the pre-polymerization reaction; when the added amount of the pre-polymerization monomers was 2.5 kg, recovering the unreacted monomers; [0062] (3) introducing mid-polymerization monomers composed of I(CF.sub.2).sub.2OCF═CF.sub.2, TFE and perfluoromethyl vinyl ether with a molar ratio of 0.1:35:64.9 into the reactor, adjusting the polymerization pressure to 2.0 MPa to carry out the mid-polymerization reaction; when the added amount of the mid-polymerization monomers was 3.3 kg, recovering the unreacted monomers; [0063] (4) further introducing post-polymerization monomers composed of I(CF.sub.2).sub.2OCF CF.sub.2, TFE and perfluoromethyl vinyl ether with a molar ratio of 1:60:39 into the reactor, increasing the pressure of the reactor to 3.0 MPa; when the added amount of the post-polymerization monomers was 2.5 kg, ending the reaction and recovering the unreacted monomers; an emulsion containing the perfluoroether fluororubber being obtained; and [0064] (5) the emulsion being mechanically agglomerated, washed, and vacuum dried at 100° C. to provide about 7.5 kg of the perfluoroether fluororubber product.

Example 2

[0065] A preparation method of perfluoroether fluororubber compreses steps of: [0066] (1) adding 30 L of deionized water to a 50 L reactor, vacuumizing to an oxygen content of ≤30 ppm, adding 50 g of ammonium perfluorooctanoate, and heating the contents in the reactor to 90° C.; [0067] (2) feeding pre-polymerization monomers composed of I(CF.sub.2).sub.2OCF═CF.sub.2, tetrafluoroethylene and perfluoropropyl vinyl ether with a molar ratio of 3:67:30, increasing the pressure of the reactor to 3.5 MPa, adding 40 g of potassium persulfate and 50 g of 1,4-diiodoperfluorobutane to carry out the pre-polymerization reaction; when the added amount of the pre-polymerization monomers was 3.5 kg, recovering the unreacted monomers; [0068] (3) introducing mid-polymerization monomers composed of I(CF.sub.2).sub.2OCF═CF.sub.2, TFE and perfluoropropyl vinyl ether with a molar ratio of 1:55:44 into the reactor, adjusting the polymerization pressure to 2.5 MPa to carry out the mid-polymerization reaction; when the added amount of the mid-polymerization monomers was 3.0 kg, recovering the unreacted monomers; [0069] (4) further introducing post-polymerization monomers composed of I(CF.sub.2).sub.2OCF CF.sub.2, TFE and perfluoropropyl vinyl ether with a molar ratio of 3:67:30 into the reactor, increasing the pressure of the reactor to 3.5 MPa; when the added amount of the post-polymerization monomers was 3.5 kg, ending the reaction and recovering the unreacted monomers; an emulsion containing the perfluoroether fluororubber being obtained; and [0070] (5) the emulsion being mechanically agglomerated, washed, and vacuum dried at 100° C. to provide the perfluoroether fluororubber product.

Example 3

[0071] Compared with Example 1, the difference of this comparative Example lies in that, the pressure of mid-polymerization reaction in step (3) was 3.0 MPa.

Example 4

[0072] Compared with Example 1, the difference of this comparative Example lies in that, the pressures of the pre-polymerization reaction in step (2) and the post-polymerization reaction in step (4) were both 2.0 MPa.

Example 5

[0073] Compared with Example 1, the difference of this comparative Example lies in that, the molar ratio of I(CF.sub.2).sub.2OCF═CF.sub.2, TFE and perfluoromethyl vinyl ether introduced in step (3) was 0.1:50:49.9.

Comparative Example 1

[0074] A preparation method of perfluoroether fluororubber compreses steps of: [0075] (1) adding 30 L of deionized water to a 50 L reactor, vacuumizing to an oxygen content of ≤30 ppm, adding 35 g of ammonium perfluorooctanoate, and heating the contents in the reactor to 85° C.; [0076] (2) feeding I(CF.sub.2).sub.2OCF═CF.sub.2, TFE and perfluoromethyl vinyl ether with a molar ratio of 1:45:55 and the total addition amount of the polymerization monomers being 8.3 kg, increasing the pressure of the reactor to 3.0 MPa, adding 15 g of potassium persulfate and 25 g of 1,2-diiodoperfluoroethane to carry out the polymerization reaction; when the solid content was about 21%, recovering the unreacted monomers and an emulsion containing the perfluoroether fluororubber being obtained; and [0077] (5) the emulsion being mechanically agglomerated, washed, and vacuum dried at 100° C. to provide about 8.0 kg of the perfluoroether fluororubber product.

[0078] Performance Test

[0079] The raw rubbers (perfluoroether fluororubber product) prepared by Example 1 and Comparative Example 1 were vulcanized, and the vulcanization formula is shown in Table 1:

TABLE-US-00001 TABLE 1 Component or procedure Parameter Raw rubber 100 parts 2,5-dimethyl-2,5- 4 parts di(tert-butylperoxy)hexane, 75% TAIC 3 parts N990 20 parts First-stage vulcanization 170° C. × 10 min Second-stage vulcanization 232° C. × 4 h   

[0080] The performance test of raw rubbers and vulcanized samples was conducted to measure the Mooney viscosity, fluorine content, mechanical properties (tensile strength and elongation at break), hardness and compression deformation. The test results are shown in Table 2:

TABLE-US-00002 TABLE 2 Com- Elon- pression F Tensile gation Hard- defor- Mooney content/ strength/ at ness/ mation/ Sample viscosity % MPa break/% Ha % Example 1 55 72 28.5 180 78 25 Example 2 62 72.1 29.2 180 77 26 Example 3 75 72.0 32.0  80 88 45 Example 4 22 70.5 16.3  90 82 38 Example 5 42 70.1 14.8 110 85 39 Comparative 78 72.1 26.5 110 92 37 Example 1

[0081] It can be seen from the Examples and performance tests that the perfluoroether fluororubber prepared by the preparation method according to the present invention has good tensile strength and elongation at break, while the hardness and compression deformation are low, and the processability is good.

[0082] From the comparison of Example 1 with Examples 2-4, it can be seen that the pressures used in the stepwise polymerization reaction according to the present invention need to be within the limited ranges of the present invention to provide a product with excellent tensile strength while its hardness and compression deformation are low, and the medium resistance and processability are better. From the comparison of Example 1 with Example 5, it can be seen that the feedstock ratio in the mid-term polymerization reaction needs to be within the limited range of the present invention. From the comparison of Example 1 with Comparative Example 1, it can be seen that the perfluoroether fluororubber obtained by stepwise polymerization method has lower hardness and compression deformation, and has better vulcanization performance and better processability.

[0083] The applicant declares that the present invention illustrates the perfluoroether fluororubber, the preparation method therefor and use thereof according to the present invention by the above embodiments, but the present invention is not limited to the above detailed methods, that is, it does not mean that the present invention must rely on the above detailed methods to be implemented. Those skilled in the art should understand that any modification of the present invention, equivalent substitution of each and any raw material of the product of the present invention, addition of auxiliary ingredient, selection of a specific method, etc., all fall within the scope of protection and disclosure of the present invention.