A fluorine-containing organic polymer and its preparation method

Abstract

The present invention relates to the technical field of fluorine-containing polymer synthesis, and particularly relates to a fluorine-containing organic polymer and a preparation method thereof. The present invention provides a fluorine-containing organic polymer having the structure shown in Formula I; in Formula I, 20 < n < 1000. The present invention uses a peroxide as an initiator to initiate a radical polymerization reaction of a fluorine-containing monomer containing an unsaturated bond and a cyclic monomer, and prepares a vinylidene fluoride copolymer containing a cyclic structure on the main chain. This copolymer has a low crystallinity, good transparency, and a high Tg. At the same time, the reaction operation of the present invention is simple and practical, and the reaction conditions are mild.

Description

Technical Field

[0001] The present invention relates to the technical field of fluoropolymer synthesis, and particularly relates to a fluorinated organic polymer and a preparation method thereof. Background Art

[0002] Polyvinylidene fluoride is a special engineering plastic, which has excellent chemical corrosion resistance, high temperature resistance, weather resistance, ultraviolet resistance, and high hardness, wear resistance, high heat distortion temperature, and good electrical insulation performance. Therefore, the research on polyvinylidene fluoride has always attracted people's attention. To broaden the application of this material in the cable field, it is necessary to further improve the flexibility of polyvinylidene fluoride. Among them, copolymerizing with a second monomer and vinylidene fluoride (VDF) is an important research direction. For example, currently, copolymers containing vinylidene fluoride (VDF), hexafluoropropylene (HFP), or chlorotrifluoroethylene (CTFE) have been proposed (WO1999 / 034372).

[0003] The above copolymerization research results have indeed improved some properties of PVDF, but the Tg of these copolymers is relatively low, and the films made have a certain degree of haze. In the field of optical applications, polymer materials need to have chemical resistance, optical transparency, and a relatively high Tg. Patent CN105669891A mentions that after replacing trifluorovinyl in the copolymer of vinylidene fluoride and trifluoromethyl vinyl with 2,3,3,3-tetrafluoropropene, these copolymers have excellent optical properties, corrosion resistance, electrical properties, and low haze. However, the Tg of these copolymers is relatively low, which affects their application scope. Patent CN1189489C uses hexafluoropropylene and vinylidene fluoride to copolymerize to reduce the crystallinity of the copolymer. When the content of hexafluoropropylene in the copolymer reaches 36% or more, the crystallinity of the copolymer is 0. It can be seen that the defect of this technology is that when the content of hexafluoropropylene in the copolymer is relatively high, the crystallinity can be significantly reduced. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a fluorinated organic polymer and a preparation method thereof, and the fluorinated organic polymer has a relatively low crystallinity and a relatively high Tg.

[0005] The present invention provides a fluorinated organic polymer having the structure shown in Formula I:

[0006]

[0007] In Formula I, 20 < n < 1000.

[0008] The present invention also provides a preparation method of a fluorinated organic polymer, comprising the following steps:

[0009] A fluorine-containing monomer having the structure shown in Formula II and a cyclic monomer having the structure shown in Formula III are subjected to a polymerization reaction under the action of an initiator to obtain a fluorine-containing organic polymer having the structure shown in Formula I;

[0010]

[0011] In Formula I, 20 < n < 1000.

[0012] Preferably, the molar ratio of the fluorine-containing monomer having the structure shown in Formula II to the cyclic monomer having the structure shown in Formula III is 0.2 - 1:0.1 - 1.

[0013] Preferably, the initiator is a peroxide;

[0014] The molar ratio of the initiator to the fluorine-containing monomer having the structure shown in Formula II is 0.001 - 0.020:0.1 - 1.

[0015] Preferably, the peroxide includes at least one of ammonium persulfate, potassium persulfate, tert-butyl peroxyneodecanoate, and diisopropyl peroxydicarbonate.

[0016] Preferably, the temperature of the polymerization reaction is -30 to 120 °C, and the time is 24 to 48 h.

[0017] Preferably, the temperature of the polymerization reaction is 60 to 100 °C.

[0018] Preferably, it includes the following steps:

[0019] Under the condition that the oxygen content is less than 20 ppm, an organic solvent, a fluorine-containing monomer having the structure shown in Formula II, a cyclic monomer having the structure shown in Formula III, and an initiator solution are mixed and then subjected to a polymerization reaction to obtain a fluorine-containing organic polymer having the structure shown in Formula I.

[0020] Preferably, the organic solvent includes at least one of ethyl acetate, butyl acetate, acetone, tetrahydrofuran, R113, and HFE-347;

[0021] The solvent in the initiator solution includes at least one of ethyl acetate, butyl acetate, acetone, tetrahydrofuran, R113, and HFE-347;

[0022] The mass concentration of the initiator solution is 4% - 6%.

[0023] Preferably, the dosage ratio of the fluorine-containing monomer having the structure shown in Formula II to the organic solvent is 0.1 - 5.0 mmol:1 mL.

[0024] The present invention provides a fluorine-containing organic polymer (vinylidene fluoride and cyclopentadiene copolymer) having the structure shown in Formula I:

[0025]

[0026] In Formula I, 20 < n < 1000.

[0027] The present invention uses a peroxide as an initiator to initiate a radical polymerization reaction of a fluorinated monomer containing an unsaturated bond and a cyclic monomer, and prepares a vinylidene fluoride copolymer containing a cyclic structure in the main chain. This copolymer has a low crystallinity, good transparency, and a high Tg. At the same time, the reaction operation of the present invention is simple and practical, and the reaction conditions are mild. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 1H NMR spectrum of the white powder obtained in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] The present invention provides a fluorinated organic polymer (vinylidene fluoride and cyclopentadiene copolymer) having the structure shown in Formula I:

[0031]

[0032] In Formula I, 20 < n < 1000.

[0033] In the present invention, in the fluorinated organic polymer, when the mass content of dicyclopentadiene reaches 27% or more, the Tg of the fluorinated organic polymer is not lower than 98 °C, the crystallinity is 0%, and the transparency is excellent.

[0034] In the fluorinated organic polymer provided by the present invention, when the mass content of dicyclopentadiene is 10% - 27%, the Tg of the fluorinated organic polymer is 51 - 98 °C, and the crystallinity is 0% - 13%. Specifically, when the mass content of dicyclopentadiene in the fluorinated organic polymer is 10%, the Tg of the fluorinated organic polymer is 51 °C, and the crystallinity is 13%. Or when the mass content of dicyclopentadiene in the fluorinated organic polymer is 15%, the Tg of the fluorinated organic polymer is 71 °C, and the crystallinity is 7%. Or when the mass content of dicyclopentadiene in the fluorinated organic polymer is 19%, the Tg of the fluorinated organic polymer is 76 °C, and the crystallinity is 5%. Or when the mass content of dicyclopentadiene in the fluorinated organic polymer is 27%, the Tg of the fluorinated organic polymer is 98 °C, and the crystallinity is 0%.

[0035] The present invention also provides a method for preparing the fluorinated organic polymer described above, comprising the following steps:

[0036] The fluorinated monomer having the structure shown in Formula II and the cyclic monomer having the structure shown in Formula III are subjected to a polymerization reaction under the action of an initiator to obtain a fluorinated organic polymer having the structure shown in Formula I;

[0037]

[0038] In Formula I, 20 < n < 1000.

[0039] In certain embodiments of the present invention, the molar ratio of the fluorinated monomer having the structure shown in Formula II to the cyclic monomer having the structure shown in Formula III is 0.2 - 1:0.1 - 1; preferably 1:1; specifically 1:1, 1:0.3 or 1:0.15.

[0040] In certain embodiments of the present invention, the initiator is a peroxide. Specifically, the peroxide includes at least one of ammonium persulfate, potassium persulfate, tert-butyl peroxyneopentanoate and diisopropyl peroxydicarbonate; preferably diisopropyl peroxydicarbonate.

[0041] The molar ratio of the initiator to the fluorinated monomer having the structure shown in Formula II is 0.001 - 0.020:0.1 - 1; specifically 0.001:0.4 or 0.001:0.2.

[0042] In certain embodiments of the present invention, the polymerization reaction is carried out under the condition that the oxygen content is less than 20 ppm. The present invention can purge the reaction vessel with nitrogen, seal the reaction vessel, and perform vacuum / nitrogen replacement on the reaction vessel until the oxygen content in the reaction vessel is less than 20 ppm.

[0043] In certain embodiments of the present invention, the polymerization reaction is carried out in an organic solvent. The organic solvent includes at least one of ethyl acetate, butyl acetate, acetone, tetrahydrofuran, R113 and HFE-347; preferably R113. The dosage ratio of the fluorinated monomer having the structure shown in Formula II to the organic solvent is 0.1 - 5.0 mmol:1 mL; preferably 0.1 - 3.0 mmol:1 mL.

[0044] In certain embodiments of the present invention, the temperature of the polymerization reaction is -30 - 120 °C, and the time is 24 - 48 h; specifically 24 h. Preferably, the temperature of the polymerization reaction is 60 - 100 °C; specifically 40 °C or 60 °C. The polymerization reaction is carried out under stirring conditions, and the polymerization reaction is carried out in a high-pressure reactor.

[0045] In certain embodiments of the present invention, the method for preparing the fluorinated organic polymer includes the following steps:

[0046] Under the condition that the oxygen content is less than 20 ppm, an organic solvent, a fluorinated monomer having the structure shown in Formula II, a cyclic monomer having the structure shown in Formula III, and an initiator solution are mixed and then subjected to a polymerization reaction to obtain a fluorinated organic polymer having the structure shown in Formula I.

[0047] In some embodiments, the mixing is stirring mixing.

[0048] The solvent in the initiator solution includes at least one of ethyl acetate, butyl acetate, acetone, tetrahydrofuran, R113, and HFE-347; preferably R113;

[0049] The mass concentration of the initiator solution is 4% - 6%; specifically 5%.

[0050] In some embodiments of the present invention, after the polymerization reaction, it further includes:

[0051] Pour the product solution after the polymerization reaction into an excessive amount of n-hexane to precipitate the product, remove the upper-layer organic solvent, and after drying, obtain a polymerization product, that is, a fluorinated organic polymer having the structure shown in Formula I.

[0052] The mass ratio of the n-hexane to the product solution is greater than 10:1; specifically 11:1.

[0053] The temperature of the n-hexane ≤ 25 °C; specifically 23 °C.

[0054] The temperature for drying is 70 - 90 °C, specifically 80 °C; the time is 10 - 14 h, specifically 12 h.

[0055] The present invention has no special restrictions on the sources of the raw materials used above, and they can be generally commercially available.

[0056] Beneficial effects:

[0057] 1) The present invention uses a peroxide as an initiator to initiate a free radical polymerization reaction of a fluorinated monomer containing an unsaturated bond and a cyclic monomer, and prepares a vinylidene fluoride copolymer containing a cyclic structure on the main chain. This copolymer has a lower crystallinity, better transparency, and a higher Tg.

[0058] 2) The reaction operation of the present invention is simple, practical, and the reaction conditions are mild;

[0059] 3) The double bond retained on the side chain of the copolymer synthesized by the present invention can be used for crosslinking.

[0060] In order to further illustrate the present invention, the following describes in detail a fluorinated organic polymer and its preparation method provided by the present invention in conjunction with embodiments, but it should not be construed as limiting the protection scope of the present invention.

[0061] In the examples, Tg and crystallinity were measured according to standard D3418, and the Tg values shown in the examples are the midpoint Tg.

[0062] Example 1

[0063] A 1 L high-pressure reactor was purged with nitrogen, sealed, and evacuated / nitrogen replaced until the oxygen content in the reactor was less than 20 ppm. Then, 0.4 L of R113, 88 g (667 mmol) of the cyclic monomer having the structure shown in Formula III, 128 g (2000 mmol) of the fluorine-containing monomer having the structure shown in Formula II, and 10 mL of an R113 solution of diisopropyl peroxydicarbonate (1.03 g, 5 mmol) were added. After reacting at 40 °C for 24 h, stirring was stopped, and the reactor was vented to atmospheric pressure. The product solution was collected and poured into an excess of n-hexane at 23 °C (the mass ratio of the n-hexane to the product solution was 11:1) to precipitate the copolymer. The upper organic solvent was removed, and the copolymer was placed in a vacuum oven and dried at 80 °C for 12 h to obtain 65 g of a white powder.

[0064] The white powder obtained was analyzed by 1H NMR spectroscopy, and the results are as Figure 1 shown. Figure 1 This is the 1H NMR spectrum of the white powder obtained in Example 1 of the present invention. Figure 1 In the polymer, 20 < n < 1000. From Figure 1 it can be seen that in the 1H NMR spectrum, the peaks at 5.5 - 6.5 ppm are the C-H of the unsaturated double bond of Polymer I, and the peaks at 1.5 - 2.0 ppm are the C-H adjacent to CF2 of Polymer I. Therefore, the obtained white powder has the structure shown in Formula I.

[0065] Calculated from the NMR data, the mass content of dicyclopentadiene in the polymer is 15%, and the mass content of 1,1-difluoroethylene is 85%. After testing, the Tg of the fluorinated organic polymer having the structure shown in Formula I is 71 °C, and the crystallinity is 7%. See Table 1 for details.

[0066] Example 2

[0067] Purge a 1L high-pressure reactor with nitrogen, seal the reactor, and replace the air in the reactor with vacuum / nitrogen until the oxygen content in the reactor is less than 20 ppm. Add 0.4L of R113, 88 g (667 mmol) of the cyclic monomer having the structure shown in Formula III, 128 g (2000 mmol) of the fluorine-containing monomer having the structure shown in Formula II, and 10 mL of an R113 solution of tert-butyl perpivalate (0.87 g, 5 mmol). After reacting at 60 °C for 24 h, stop stirring, vent to atmospheric pressure, collect the product solution, pour it into an excess of n-hexane at 23 °C (the mass ratio of the n-hexane to the product solution is 11:1) to precipitate the copolymer. Remove the upper organic solvent, place the copolymer in a vacuum oven, and dry it at 80 °C for 12 h to obtain 73 g of a white powder.

[0068] Calculated from the NMR data, in the polymer, the mass content of dicyclopentadiene is 19%, and the mass content of 1,1-difluoroethylene is 81%. After testing, the Tg of the fluorine-containing organic polymer having the structure shown in Formula I is 76 °C, and the crystallinity is 5%. See Table 1 for details.

[0069] Example 3

[0070] Purge a 1L high-pressure reactor with nitrogen, seal the reactor, and replace the air in the reactor with vacuum / nitrogen until the oxygen content in the reactor is less than 20 ppm. Add 0.4L of R113, 44 g (333 mmol) of the cyclic monomer having the structure shown in Formula III, 128 g (2000 mmol) of the fluorine-containing monomer having the structure shown in Formula II, and 10 mL of an R113 solution of tert-butyl perpivalate (0.87 g, 5 mmol). After reacting at 60 °C for 24 h, stop stirring, vent to atmospheric pressure, collect the product solution, pour it into an excess of n-hexane at 23 °C (the mass ratio of the n-hexane to the product solution is 11:1) to precipitate the copolymer. Remove the upper organic solvent, place the copolymer in a vacuum oven, and dry it at 80 °C for 12 h to obtain 81 g of a white powder.

[0071] Calculated from the NMR data, in the polymer, the mass content of dicyclopentadiene is 10%, and the mass content of 1,1-difluoroethylene is 90%. After testing, the Tg of the fluorine-containing organic polymer having the structure shown in Formula I is 51 °C, and the crystallinity is 13%. See Table 1 for details.

[0072] Example 4

[0073] Purge a 1 L high-pressure reactor with nitrogen, seal the reactor, and perform vacuum / nitrogen replacement on the reactor until the oxygen content in the reactor is less than 20 ppm. Add 0.4 L of R113, 132 g (1000 mmol) of a cyclic monomer having the structure shown in Formula III, 64 g (1000 mmol) of a fluorine-containing monomer having the structure shown in Formula II, and 10 mL of an R113 solution of tert-butyl peroxyneodecanoate (0.87 g, 5 mmol). After reacting at 60 °C for 24 h, stop stirring, vent to atmospheric pressure, collect the product solution, pour it into excessive n-hexane at 23 °C (the mass ratio of the n-hexane to the product solution is 11:1), precipitate the copolymer, remove the upper organic solvent, place the copolymer in a vacuum oven, dry it at 80 °C for 12 h, and obtain 26 g of a white powder.

[0074] Calculated according to the NMR data, in the polymer, the mass content of dicyclopentadiene is 27%, and the mass content of 1,1-difluoroethylene is 73%. After testing, the Tg of the fluorine-containing organic polymer having the structure shown in Formula I is 98 °C, and the crystallinity is 0%. See Table 1 for details.

[0075] Table 1 Monomer mass content and crystallinity in the copolymers obtained in Examples 1 to 4

[0076] Example 1,1-difluoroethylene content Dicyclopentadiene content Crystallinity 1 85％ 15％ 7％ 2 81％ 19％ 5％ 3 90％ 10％ 13％ 4 73％ 27％ 0％

[0077] Comparative Examples 1 to 3

[0078] Patent CN1189489C, titled "Low-crystallinity copolymer of 1,1-difluoroethylene and hexafluoropropylene", mentions that only when the hexafluoropropylene content in the copolymer reaches 36% or more, the crystallinity of the copolymer is 0. When the hexafluoropropylene content is 31%, the crystallinity of the copolymer is 7%. When the hexafluoropropylene content is 29%, the crystallinity of the copolymer is 10%. See Table 1 for details.

[0079] Table 1 Monomer mass content and crystallinity in the copolymers obtained in Comparative Examples 1 to 3

[0080] Comparative example 1,1-difluoroethylene content Hexafluoropropylene content Crystallinity 1 64％ 36％ 0％ 2 69％ 31％ 7％ 3 71％ 29％ 10％

[0081] Comparing Examples 1 to 4 of the present invention and Comparative Examples 1 to 3, it can be seen that when the mass content of dicyclopentadiene in the copolymer is 27%, the crystallinity of the copolymer can be reduced to 0%; while when using hexafluoropropylene and difluoroethylene to copolymerize, the crystallinity of the copolymer can only be reduced to 0% when the mass content of hexafluoropropylene reaches 36%. Therefore, dicyclopentadiene can more effectively reduce the crystallinity of difluoroethylene copolymers than hexafluoropropylene.

[0082] The experimental results show that the fluorine-containing organic polymer provided by the present invention has a low crystallinity (excellent transparency) and a high Tg.

[0083] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fluorinated organic polymer having the structure shown in Formula I: In Formula I, 20 < n < 1000; In the fluorinated organic polymer, the mass content of dicyclopentadiene is 10% - 27%.

2. A method for preparing a fluorinated organic polymer, comprising the following steps: A fluorinated monomer having the structure shown in Formula II and a cyclic monomer having the structure shown in Formula III are subjected to a polymerization reaction under the action of an initiator to obtain a fluorinated organic polymer having the structure shown in Formula I; In Formula I, 20 < n < 1000; In the fluorinated organic polymer, the mass content of dicyclopentadiene is 10% - 27%.

3. The preparation method according to claim 2, wherein The molar ratio of the fluorinated monomer having the structure shown in Formula II to the cyclic monomer having the structure shown in Formula III is 0.2 - 1:0.1 - 1.

4. The preparation method according to claim 2, characterized in that, The initiator is a peroxide; The molar ratio of the initiator to the fluorinated monomer having the structure shown in Formula II is 0.001 - 0.020:0.1 - 1.

5. The preparation method according to claim 4, wherein The peroxide includes at least one of ammonium persulfate, potassium persulfate, tert-butyl peroxyneopentanoate, and diisopropyl peroxydicarbonate.

6. The preparation method according to claim 2, characterized in that, The temperature of the polymerization reaction is -30 - 120°C, and the time is 24 - 48 h.

7. The preparation method according to claim 2, characterized in that, The temperature of the polymerization reaction is 60 - 100°C.

8. The preparation method according to claim 2, wherein Comprising the following steps: Under the condition that the oxygen content is less than 20 ppm, an organic solvent, a fluorinated monomer having the structure shown in Formula II, a cyclic monomer having the structure shown in Formula III, and an initiator solution are mixed and then subjected to a polymerization reaction to obtain a fluorinated organic polymer having the structure shown in Formula I.

9. The preparation method according to claim 8, characterized in that, The organic solvent includes at least one of ethyl acetate, butyl acetate, acetone, tetrahydrofuran, R113, and HFE-347; The solvent in the initiator solution includes at least one of ethyl acetate, butyl acetate, acetone, tetrahydrofuran, R113, and HFE-347; The mass concentration of the initiator solution is 4% - 6%.

10. The preparation method according to claim 8, wherein The dosage ratio of the fluorinated monomer having the structure shown in Formula II to the organic solvent is 0.1 - 5.0 mmol:1 mL.

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