A fluorine-containing resin, a method for producing the same, and use thereof

Abstract

The application discloses a fluorine-containing resin, which comprises 58-78 wt% of a first copolymer formed by vinylidene fluoride-trifluoroethylene-a third fluorine-containing monomer in a linear molecular structure; 20-40 wt% of a second copolymer formed by vinylidene fluoride-trifluoroethylene-a third fluorine-containing monomer in a branched molecular structure; and 0.5-5 wt% of a third copolymer formed by vinylidene fluoride-trifluoroethylene-a polar monomer in a branched molecular structure. The fluorine-containing resin has a unique molecular weight distribution, a branched structure and a polar structure unit, and a fluorine-containing resin mixture prepared by blending the fluorine-containing resin with inorganic particles has the inorganic particles uniformly dispersed in the fluorine-containing resin and not agglomerated.

Description

Technical Field

[0001] This invention relates to the field of polymers, and more specifically to fluorinated resins, their preparation methods, and applications. Background Technology

[0002] Vinylidene fluoride-trifluoroethylene copolymer resin and its derivatives (hereinafter referred to as F23 resin) are electroactive fluorinated resins. Due to their excellent dielectric, ferroelectric, piezoelectric and electrochemical properties, they are widely used in microelectronic devices, sensors, loudspeakers, capacitors and refrigeration.

[0003] To further improve the performance of F23 resin, inorganic particles are often added to prepare fluorinated composite materials. However, inorganic particles have poor compatibility with F23 resin and are not easily dispersed uniformly. To solve the problem of uneven dispersion of inorganic particles, patent CN109593218A discloses the use of strong acids, strong oxidants, organosilicon coupling agents, dopamine and its derivatives to modify the surface of inorganic particles, and patent CN100338149A discloses the use of isocyanates to modify the surface of inorganic particles, thereby improving the uniformity of distribution, compatibility or interfacial properties of inorganic particles and resin.

[0004] However, modifying inorganic particles alone cannot achieve the best results. Improving F23 resin to obtain a resin structure that is easier to combine with inorganic particles is another direction, but there are currently no relevant research reports. Summary of the Invention

[0005] To address the aforementioned problems, the present invention provides a fluorinated resin having a unique molecular weight distribution, branched structure, and polar monomer structural units. A mixture prepared by blending the fluorinated resin with inorganic particles is provided, wherein the inorganic particles are uniformly dispersed in the fluorinated resin without agglomeration.

[0006] This invention is achieved through the following technical solution:

[0007] A fluorinated resin, the fluorinated resin comprising:

[0008] A first copolymer consisting of 58–78 wt% of vinylidene fluoride, trifluoroethylene, and a third fluorinated monomer with a linear molecular structure;

[0009] 20–40 wt% of a second copolymer formed from branched molecular structure of vinylidene fluoride, trifluoroethylene, and a third fluorinated monomer;

[0010] 0.5–5 wt% of a third copolymer formed from branched molecular structure vinylidene fluoride, trifluoroethylene, and polar monomers.

[0011] Furthermore, the first copolymer has a long branching point content of <0.03 per 1000 carbon atoms and a weight-average molecular weight of >300,000 Daltons; the second copolymer has a long branching point content of >0.1 per 1000 carbon atoms and a weight-average molecular weight of >300,000 Daltons; and the third copolymer has a long branching point content of >0.1 per 1000 carbon atoms and a weight-average molecular weight of <100,000 Daltons.

[0012] The polar monomer structural unit content in the fluorinated resin of the present invention accounts for >0.01 wt% of the total amount of the fluorinated resin.

[0013] The third fluorinated monomer of the present invention is selected from at least one of monofluorochloroethylene, difluorochloroethylene, trifluorochloroethylene, hexafluoropropylene, or vinyl fluoride; preferably, the third fluorinated monomer is selected from at least one of monofluorochloroethylene, difluorochloroethylene, or trifluorochloroethylene.

[0014] The polar monomers described in this invention are selected from at least one of acrylic acid, acrylate, methacrylic acid, methacrylate, maleic acid, maleate, citrate, or citrate; preferably, the polar monomers are selected from at least one of acrylic acid or acrylate.

[0015] The third copolymer of vinylidene fluoride-trifluoroethylene-polar monomer with a branched molecular structure has strong interaction between the polar monomer structural units and inorganic particles, and the molecular chains are wrapped around the surface of the inorganic particles, achieving good interfacial compatibility between the inorganic particles and the polymer. The second copolymer of vinylidene fluoride-trifluoroethylene-third fluorinated monomer with a branched molecular structure better connects the third copolymer in the region through the branched chain structure. The second copolymer and the third copolymer are completely compatible due to their consistent main chain structure. The first copolymer of vinylidene fluoride-trifluoroethylene-third fluorinated monomer with a linear molecular structure serves as the backbone, and its long straight chains effectively connect the second copolymer in different regions. The first copolymer and the third copolymer are completely compatible due to their consistent main chain structure. Through the synergistic effect of the three copolymer components, the uniformity of distribution, compatibility, or interfacial properties of inorganic particles in fluorinated resin are improved.

[0016] The present invention also provides a method for preparing a fluorinated resin, the method comprising the following steps:

[0017] (1) Add deionized water, dispersant, and polymerizer to the reactor, and evacuate the reactor until the internal pressure is <0.01 Bar;

[0018] (2) A first mixture comprising 58-83 wt% vinylidene fluoride, 15-40 wt% trifluoroethylene and 0.1-3 wt% third fluorinated monomer is added to a reactor, an initiator is added to carry out a polymerization reaction, the polymerization pressure is 45-80 bar, the polymerization temperature is 35-50 °C, and a second mixture comprising 30-75 wt% vinylidene fluoride, 15-40 wt% trifluoroethylene and 2-30 wt% third fluorinated monomer is added to the reactor, and a first copolymer is obtained by polymerization reaction;

[0019] (3) The reactor is heated to 65-85°C, and a third mixture including 35-70 wt% vinylidene fluoride, 20-40 wt% trifluoroethylene and 5-35 wt% third fluorinated monomer is added to the reactor and a second copolymer is obtained through polymerization reaction.

[0020] (4) Add polar monomers to the reactor and polymerize to obtain a third copolymer. After the polymerization reaction is completed, wash, dehydrate and dry to obtain a fluorinated resin.

[0021] Further, the first mixture comprises 64-79 wt% vinylidene fluoride, 20-35 wt% trifluoroethylene, and 0.3-1.5 wt% of a third fluorinated monomer; the second mixture comprises 43-68 wt% vinylidene fluoride, 17-37 wt% trifluoroethylene, and 4-20 wt% of a third fluorinated monomer; and the third mixture comprises 40-65 wt% vinylidene fluoride, 20-35 wt% trifluoroethylene, and 10-25 wt% of a third fluorinated monomer.

[0022] The third fluorinated monomer of the present invention is selected from at least one of monofluorochloroethylene, difluorochloroethylene, trifluorochloroethylene, hexafluoropropylene, or vinyl fluoride; preferably, the third fluorinated monomer is selected from at least one of monofluorochloroethylene, difluorochloroethylene, or trifluorochloroethylene.

[0023] The polar monomers described in this invention are selected from at least one of acrylic acid, acrylate, methacrylic acid, methacrylate, maleic acid, maleate, citrate, or citrate; preferably, the polar monomers are selected from at least one of acrylic acid or acrylate.

[0024] The dispersant of the present invention is selected from at least one of methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, or maleic acid modified polyethylene; preferably, it is selected from at least one of methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, or carboxymethylcellulose.

[0025] The polymerization telomer described in this invention is selected from at least one of alcohols, ketones, esters, halogenated hydrocarbons, or aliphatic alkanes; preferably, the polymerization telomer is selected from at least one of methanol, isopropanol, acetone, ethyl acetate, diethyl carbonate, dimethyl carbonate, dichloromethane, or n-hexane.

[0026] The initiator of the present invention is selected from at least one of di-n-propyl peroxide, diisopropyl peroxide, diisobutyl peroxide, 2-ethylhexyl peroxide, di-tert-butyl peroxide, tert-butyl peroxide, or lauroyl peroxide; preferably, it is selected from at least one of di-n-propyl peroxide, diisopropyl peroxide, di-tert-butyl peroxide, or tert-butyl peroxide.

[0027] In step (2) of this invention, the polymerization temperature is 35-50℃, and the resulting polymer has a basically linear molecular chain with an average content of long branching points <0.03 per 1000 carbon atoms. When the polymerization temperature is <35℃, the reaction rate will slow down, especially when the concentration of the third fluorinated monomer in the reactor is high or when a polymer with a high content of the third fluorinated monomer needs to be prepared, the slowdown in reaction rate will be more significant. When the polymerization temperature is >50℃, the content of long branching points in the product will increase. The concentrations of initiator and telomer are low, and the weight-average molecular weight of the resulting polymer is >300,000 Daltons. By adding a suitable proportion of the second mixture, the concentrations of vinylidene fluoride, trifluoroethylene, and the third fluorinated monomer in the reactor are kept basically constant. Thus, a first copolymer formed by vinylidene fluoride-trifluoroethylene-third fluorinated monomer with a linear molecular structure is prepared, with a long branching point content <0.03 per 1000 carbon atoms and a weight-average molecular weight >300,000 Daltons.

[0028] In step (3) of this invention, the polymerization temperature is 65-85℃, resulting in a polymer molecular chain structure containing a large number of long branches. The polymer exhibits a branched molecular structure, with an average content of long branching points > 0.1 per 1000 carbon atoms. When the polymerization temperature is < 65℃, the average content of long branching points will be < 0.1 per 1000 carbon atoms, and the degree of branching of the molecular chain will not meet the requirements. When the polymerization temperature is > 85℃, it is not conducive to controlling the concentration of the three monomers, the uniformity of polymer composition decreases, and the long branches... The average content of branching points is >1 per 1000 carbon atoms; the concentrations of initiator and telomer are low, and the weight-average molecular weight of the obtained polymer is >300,000 Daltons; by adding a suitable proportion of the third mixture, the concentrations of vinylidene fluoride, trifluoroethylene, and the third fluorinated monomer in the reactor are kept basically constant; thereby, a second copolymer of vinylidene fluoride-trifluoroethylene-the third fluorinated monomer with a branched molecular structure and high molecular weight is prepared, with the content of long-chain branching points >0.1 per 1000 carbon atoms and the weight-average molecular weight >300,000 Daltons.

[0029] In step (4) of this invention, a polar monomer is added to prepare a third copolymer of low molecular weight vinylidene fluoride-trifluoroethylene-polar monomer with a branched molecular structure. Under these polymerization conditions, when the third fluorinated monomer is not added, the concentration of the third fluorinated monomer in the reactor will decrease to 1 / 10 of its original concentration within 10 minutes. The third copolymer obtained in this step is mainly composed of structural units of vinylidene fluoride, trifluoroethylene, and polar monomer. By increasing the concentration of initiator and telomerizing agent, the weight-average molecular weight of the polymer synthesized in this step is <100,000 Daltons.

[0030] Furthermore, the preparation method of the fluorinated resin employs suspension polymerization, comprising the following steps:

[0031] (1) Add 2000-4000 parts by weight of deionized water, 0.1-5 parts by weight of dispersant, and 1-5 parts by weight of polymerizer to the reactor, and evacuate the reactor until the internal pressure is <0.01 Bar;

[0032] (2) 300–900 parts by weight of a first mixture comprising 58–83 wt% vinylidene fluoride, 15–40 wt% trifluoroethylene, and 0.1–3 wt% a third fluorinated monomer are added to a reactor; 0.5–10 parts by weight of an initiator are added to the reactor to begin the polymerization reaction; 400–700 parts by weight of a second mixture comprising 30–75 wt% vinylidene fluoride, 15–40 wt% trifluoroethylene, and 2–30 wt% a third fluorinated monomer are added to the reactor; the polymerization pressure is 45–80 bar, and the polymerization temperature is 35–50 °C; the first copolymer is obtained through the polymerization reaction.

[0033] (3) The reactor is heated to 65-85°C, and 100-300 parts by weight of a third mixture including 35-70 wt% vinylidene fluoride, 20-40 wt% trifluoroethylene and 5-35 wt% of a third fluorinated monomer are added to the reactor and a second copolymer is obtained by polymerization reaction.

[0034] (5) Add 2-10 parts by mass of initiator, 10-30 parts by mass of polymerization tuner and 5-50 parts by mass of polar monomer to the reactor. The polymerization reaction is carried out for 20-40 minutes to obtain the third copolymer. After the polymerization reaction is completed, wash, dehydrate and dry to obtain fluorinated resin.

[0035] The present invention also provides a fluorinated resin mixture, which is prepared by blending 50 to 99 parts by mass of fluorinated resin and 1 to 50 parts by mass of inorganic particles.

[0036] The inorganic particles described in this invention are selected from at least one of lead zirconate titanate, barium titanate, barium strontium titanate, montmorillonite, or boron nitride, and the size of the inorganic particles is 5 to 10,000 nm; preferably, the size of the inorganic particles is 5 to 1,000 nm.

[0037] Furthermore, the inorganic particles may be left untreated or modified before use; preferably, the inorganic particles are modified by strong acid, strong oxidant, organosilicon coupling agent, and dopamine before use.

[0038] The fluorinated resin and inorganic particles described in this invention are prepared by solution blending or melt blending.

[0039] The present invention also provides an application of a fluorinated resin mixture, wherein the fluorinated resin mixture is used as an electroactive material in sensors, loudspeakers, capacitors, and refrigerators.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows: when the fluorinated resin of the present invention is blended with inorganic particles to prepare a mixture, the inorganic particles can be uniformly dispersed in the fluorinated resin without agglomeration, thereby improving the distribution uniformity, compatibility or interfacial properties of the inorganic particles and the fluorinated resin. Attached Figure Description

[0041] Figure 1 X-ray energy dispersive spectroscopy (EDS) scan of the F element distribution in the fluorinated resin mixture prepared in Example 1;

[0042] Figure 2 X-ray energy dispersive spectroscopy (EDS) scan of the F element distribution in the fluorinated resin mixture prepared in Comparative Example 1.

[0043] Figure 3 This is a schematic diagram of the fluorinated resin and inorganic particle mixture described in this invention, wherein a represents a first copolymer of vinylidene fluoride-trifluoroethylene-a third fluorinated monomer with a linear molecular structure; b represents a second copolymer of vinylidene fluoride-trifluoroethylene-a third fluorinated monomer with a branched molecular structure; c represents a third copolymer of vinylidene fluoride-trifluoroethylene-a polar monomer with a branched molecular structure; and d represents inorganic particles. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements, and equivalents that may be included within the scope of the claims.

[0045] The resin performance testing methods of the embodiments and comparative examples of the present invention are as follows:

[0046] Weight-average molecular weight: Tested using a PL-50 room-temperature GPC with chromatographically pure DMF as the mobile phase and a standard curve prepared using polystyrene standard samples.

[0047] Long-chain branching point content: using 19The content of long-chain branching points in the resin was analyzed by 1F-NMR using a Bruker AVANCE III HD 600MHz spectrometer with deuterated DMF as the solvent. The NMR peak at -100 ppm in the 1F spectrum corresponds to the F structure connected to the long-chain branching point. Therefore, the number of carbon atoms in the long-chain branching point can be calculated from the peak area at -100 ppm in the 1F spectrum, and the total number of carbon atoms can be calculated from the peak areas of all peaks. The ratio of these ratios represents the content of long-chain branching points.

[0048] Polar monomer structural unit content: (using...) 19 The content of polar monomer structural units in the resin was analyzed by 1F-NMR using a Bruker AVANCE III HD 600MHz spectrometer with deuterated DMF as the solvent. The NMR peak at -98 ppm in the 1F-NMR spectrum corresponds to the F-type structure on the VDF repeating unit connected to the polar monomer. Therefore, the number of VDF repeating units connected to the polar monomer can be calculated by the peak area at -98 ppm in the 1F-NMR spectrum, thus inferring the number of repeating units of the polar monomer. The total number of repeating units can then be calculated by the peak areas of all peaks, and the ratio of these ratios represents the content of polar monomer structural units.

[0049] Uniformity of inorganic particle distribution in fluorinated resin: The uniformity of distribution of different materials was observed by scanning the composition distribution of different elements with an X-ray energy dispersive spectrometer. The distribution of fluorinated resin was obtained by collecting F element data from the energy dispersive spectrometer.

[0050] Example 1

[0051] Fluoropolymer resins are prepared using a suspension polymerization process.

[0052] (1) Add water and additives: Inject 3000 parts by weight of deionized water, 1 part by weight of carboxymethyl cellulose and 3 parts by weight of isopropanol into the reactor, and perform vacuum replacement on the reactor to make the pressure inside the reactor <0.01 Bar;

[0053] (2) Add the first mixture: inject 490 parts by mass of vinylidene fluoride, 200 parts by mass of trifluoroethylene, and 10 parts by mass of monochlorofluoroethylene into the reactor;

[0054] (3) First stage polymerization: 2 parts by mass of di-n-propyl peroxide dicarbonate were injected into the reactor to start the first stage polymerization reaction. During the reaction, 500 parts by mass of the second mixture were continuously introduced. The second mixture consisted of 320 parts by mass of vinylidene fluoride, 130 parts by mass of trifluoroethylene, and 50 parts by mass of monochlorofluoroethylene. The polymerization pressure was maintained at 58 bar and the polymerization temperature was 45°C.

[0055] (4) Second stage polymerization: The polymerization temperature is raised to 75°C and kept constant. 200 parts by mass of the third mixture are introduced. The third mixture consists of 100 parts by mass of vinylidene fluoride, 65 parts by mass of trifluoroethylene, and 35 parts by mass of monochlorofluoroethylene. The polymerization pressure is maintained at 63 bar.

[0056] (5) Third stage polymerization: inject 5 parts by mass of di-n-propyl peroxide, 20 parts by mass of isopropanol and 30 parts by mass of acrylic acid into the reactor, maintain the polymerization temperature at 80°C and react for 40 minutes.

[0057] (6) Post-treatment: The polymerization product is washed, dehydrated and dried in sequence to obtain fluorinated resin.

[0058] Fluorine-containing resin mixtures were prepared by melt blending:

[0059] 50 parts by weight of the prepared fluorinated resin and 50 parts by weight of lead zirconate titanate were thoroughly pulverized and mixed in a pulverizer, and then melt-blended using an internal mixer to obtain a fluorinated resin mixture.

[0060] Example 2

[0061] Example 1 was repeated, except that the polymerization temperature of the first stage polymerization was 50°C, the polymerization temperature of the second stage polymerization was 85°C, and the polymerization temperature of the third stage polymerization was 85°C, while all other operations remained unchanged, to obtain a fluorinated resin mixture.

[0062] Example 3

[0063] Example 1 was repeated, except that: the first mixture consisted of 310 parts by mass of vinylidene fluoride, 175 parts by mass of trifluoroethylene, and 15 parts by mass of monofluorochloroethylene; the second mixture consisted of 400 parts by mass of vinylidene fluoride, 200 parts by mass of trifluoroethylene, and 100 parts by mass of monofluorochloroethylene; and the third mixture consisted of 50 parts by mass of vinylidene fluoride, 30 parts by mass of trifluoroethylene, and 20 parts by mass of monofluorochloroethylene. All other operations remained unchanged, resulting in a fluorinated resin mixture.

[0064] Example 4

[0065] Repeat Example 1, except that monochlorofluoroethylene is replaced with dichlorofluoroethylene, while all other operations remain unchanged, to obtain a fluorinated resin mixture.

[0066] Example 5

[0067] Repeat Example 1, except that monofluorochloroethylene is replaced with trifluorochloroethylene, while all other operations remain unchanged, to obtain a fluorinated resin mixture.

[0068] Comparative Example 1

[0069] The conditions for preparing the first copolymer in Example 1 were simulated.

[0070] (1) Add water and additives: Inject 3000 parts by weight of deionized water, 1 part by weight of carboxymethyl cellulose and 3 parts by weight of isopropanol into the reactor, and perform vacuum replacement on the reactor to make the pressure inside the reactor <0.01 Bar;

[0071] (2) Add the first mixture: inject 490 parts by mass of vinylidene fluoride, 200 parts by mass of trifluoroethylene, and 10 parts by mass of monochlorofluoroethylene into the reactor;

[0072] (3) Polymerization: 2 parts by mass of di-n-propyl peroxide dicarbonate were injected into the reactor to start the polymerization reaction. During the reaction, 700 parts by mass of the second mixture were continuously introduced. The second mixture consisted of 450 parts by mass of vinylidene fluoride, 180 parts by mass of trifluoroethylene, and 70 parts by mass of monochlorofluoroethylene. The polymerization pressure was maintained at 58 bar and the polymerization temperature was 45°C.

[0073] (4) Post-processing: After polymerization, the polymerization product is washed, dehydrated and dried in sequence to obtain fluorinated resin.

[0074] 50 parts by mass of the fluorinated resin prepared in the above steps and 50 parts by mass of lead zirconate titanate were thoroughly pulverized and mixed in a pulverizer, and then melt-blended using an internal mixer to obtain a fluorinated resin mixture.

[0075] Comparative Example 2

[0076] The conditions for preparing the second copolymer in Example 1 were simulated.

[0077] (1) Add water and additives: Inject 3000 parts by weight of deionized water, 1 part by weight of carboxymethyl cellulose and 3 parts by weight of isopropanol into the reactor, and perform vacuum replacement on the reactor to make the pressure inside the reactor <0.01 Bar;

[0078] (2) Add the first mixture: inject 490 parts by mass of vinylidene fluoride, 200 parts by mass of trifluoroethylene, and 10 parts by mass of monochlorofluoroethylene into the reactor;

[0079] (3) Polymerization: 2 parts by mass of di-n-propyl peroxide dicarbonate were injected into the reactor to start the polymerization reaction. During the reaction, 200 parts by mass of a third mixture were introduced. The third mixture consisted of 100 parts by mass of vinylidene fluoride, 65 parts by mass of trifluoroethylene, and 35 parts by mass of monochlorofluoroethylene. The polymerization pressure was maintained at 63 bar and the polymerization temperature was maintained at 75°C.

[0080] (4) Post-treatment: The polymerization product is washed, dehydrated and dried in sequence to obtain fluorinated resin.

[0081] 50 parts by mass of the fluorinated resin prepared in the above steps and 50 parts by mass of lead zirconate titanate were thoroughly pulverized and mixed in a pulverizer, and then melt-blended using an internal mixer to obtain a fluorinated resin mixture.

[0082] Comparative Example 3

[0083] The conditions for preparing the third copolymer in Example 1 were simulated.

[0084] (1) Add water and additives: Inject 3000 parts by weight of deionized water, 1 part by weight of carboxymethyl cellulose and 23 parts by weight of isopropanol into the reactor, and perform vacuum replacement on the reactor to make the pressure inside the reactor <0.01 Bar;

[0085] (2) Add the first mixture: inject 490 parts by mass of vinylidene fluoride, 200 parts by mass of trifluoroethylene, and 10 parts by mass of monochlorofluoroethylene into the reactor;

[0086] (3) Polymerization: 7 parts by mass of di-n-propyl peroxide and 30 parts by mass of acrylic acid are injected into the reactor to start the polymerization reaction. The polymerization temperature is maintained at 80°C and the reaction is carried out for 40 minutes. The polymer product is then discharged.

[0087] (4) Post-treatment: The polymerization product is washed, dehydrated and dried in sequence to obtain fluorinated resin.

[0088] 50 parts by mass of the fluorinated resin prepared in the above steps and 50 parts by mass of lead zirconate titanate were thoroughly pulverized and mixed in a pulverizer, and then melt-blended using an internal mixer to obtain a fluorinated resin mixture.

[0089] Test Example 1

[0090] The weight-average molecular weight and weight-average molecular weight <10 of the fluorinated resins prepared in Examples 1-5 and Comparative Examples 1-3 were tested. 5 The component content, long branching point content, polar monomer chain segment content, and the distribution uniformity of inorganic particles in the fluorinated resin mixture are detailed in Table 1.

[0091] Table 1. Performance data of the fluoropolymers prepared in the examples and comparative examples.

[0092]

[0093] By comparing Example 1 with Comparative Examples 1-3, it can be found that the three polymerization stages of Example 1 respectively generated a first copolymer of high molecular weight vinylidene fluoride-trifluoroethylene-monochlorofluoroethylene with a linear structure, a second copolymer of high molecular weight vinylidene fluoride-trifluoroethylene-monochlorofluoroethylene with a branched structure, and a third copolymer of low molecular weight vinylidene fluoride-trifluoroethylene-acrylic acid with a branched structure. When these three types of copolymers were mixed with inorganic particles alone, the uniformity of inorganic particle distribution was poor. When the fluorinated resin prepared in Example 1 was blended with inorganic particles, the uniformity of inorganic particle distribution was significantly improved.

Claims

1. A fluorine-containing resin characterized by comprising: The fluorine-containing resin comprises: 58-78 wt% of a first copolymer of vinylidene fluoride-trifluoroethylene-a third fluorine-containing monomer in linear molecular structure; 20-40 wt% of a second copolymer of vinylidene fluoride-trifluoroethylene-a third fluorine-containing monomer in branched molecular structure; and The weight average molecular weight of the first copolymer is greater than 300,000 Dalton; The content of long-chain branched points of the second copolymer is greater than 0.1 per 1000 carbon atoms, and the weight average molecular weight is greater than 300,000 Dalton; The content of long-chain branched points of the third copolymer is greater than 0.1 per 1000 carbon atoms, and the weight average molecular weight is less than 1,000,000 Dalton.

2. The fluorine-containing resin according to claim 1, wherein: The content of long-chain branched points of the first copolymer is less than 0.03 per 1000 carbon atoms.

3. The fluororesin according to claim 1 or 2, characterized by: The content of the polar monomer structural unit is greater than 0.01 wt% of the total amount of the fluorine-containing resin.

4. The fluororesin according to claim 1, characterized by: The third fluorine-containing monomer is selected from at least one of monofluoromonochloroethylene, difluoromonochloroethylene, trifluoromonochloroethylene, hexafluoropropylene, or fluorovinyl; and the polar monomer is selected from at least one of acrylic acid, acrylate, methacrylic acid, methacrylate, maleic acid, maleate, citraconic acid, or citraconate.

5. The fluororesin according to claim 4, characterized by: The third fluorine-containing monomer is selected from at least one of monofluoromonochloroethylene, difluoromonochloroethylene, or trifluoromonochloroethylene; and the polar monomer is selected from at least one of acrylic acid or acrylate.

6. A process for producing the fluororesin as claimed in any one of claims 1 to 5, characterized by: The preparation method comprises the following steps: (1) adding deionized water, dispersant, and telomerizer into a reactor, and evacuating the reactor to an internal pressure of less than 0.01 Bar; (2) adding a first mixture comprising 58-83 wt% of vinylidene fluoride, 15-40 wt% of trifluoroethylene, and 0.1-3 wt% of a third fluorine-containing monomer into the reactor, adding an initiator to perform a polymerization reaction, the polymerization pressure is 45-80 bar, the polymerization temperature is 35-50°C, and a second mixture comprising 30-75 wt% of vinylidene fluoride, 15-40 wt% of trifluoroethylene, and 2-30 wt% of the third fluorine-containing monomer is added to the reactor, and a first copolymer is obtained through the polymerization reaction; (3) heating the reactor to 65-85°C, adding a third mixture comprising 35-70 wt% of vinylidene fluoride, 20-40 wt% of trifluoroethylene, and 5-35 wt% of the third fluorine-containing monomer into the reactor, and obtaining a second copolymer through a polymerization reaction; (4) adding a polar monomer into the reactor, obtaining a third copolymer through a polymerization reaction, and after the polymerization reaction is completed, washing, dewatering, and drying to obtain the fluorine-containing resin.

7. The process for producing a fluororesin according to claim 6, characterized by: The first mixture comprises 64-79 wt% of vinylidene fluoride, 20-35 wt% of trifluoroethylene and 0.3-1.5 wt% of the third fluorine-containing monomer; the second mixture comprises 43-68 wt% of vinylidene fluoride, 17-37 wt% of trifluoroethylene and 4-20 wt% of the third fluorine-containing monomer; the third mixture comprises 40-65 wt% of vinylidene fluoride, 20-35 wt% of trifluoroethylene and 10-25 wt% of the third fluorine-containing monomer.

8. The process for producing a fluororesin according to claim 6 or 7, characterized by: The third fluorine-containing monomer is selected from at least one of monofluoromonochloroethylene, difluoromonochloroethylene, trifluoromonochloroethylene, hexafluoropropylene or fluoroethylene; the polar monomer is selected from at least one of acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, maleic acid, maleic ester, citraconic acid or citraconic ester.

9. The process for producing a fluororesin according to claim 6, characterized by: The dispersant is selected from at least one of methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose or maleic acid modified polyethylene.

10. The process for producing a fluororesin according to claim 6, characterized by: The telogen is selected from at least one of methanol, isopropyl alcohol, acetone, ethyl acetate, diethyl carbonate, dimethyl carbonate, dichloromethane or n-hexane.

11. The process for producing a fluororesin according to claim 6, characterized by: The initiator is selected from at least one of di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, diisobutyl peroxydicarbonate, (2-ethylhexyl) peroxydicarbonate, di-t-butyl peroxydicarbonate, t-butyl peroxybenzoate or lauroyl peroxide.

12. A fluorine-containing resin mixture characterized by: The fluorine-containing resin mixture is prepared by blending 50-99 parts by mass of the fluorine-containing resin according to any one of claims 1-5 and 1-50 parts by mass of inorganic particles.

13. The fluororesin mixture according to claim 12, characterized by: The inorganic particles are selected from at least one of lead zirconate titanate, barium titanate, barium strontium titanate, montmorillonite or boron nitride.

14. The fluororesin mixture according to claim 12, characterized by: The fluorine-containing resin mixture is prepared by solution blending or melt blending of the fluorine-containing resin and inorganic particles.

15. Use of a fluororesin mixture according to any one of claims 12 to 14, characterized in that: The fluorine-containing resin mixture is applied as an electroactive material to sensors, loudspeakers, capacitors, refrigerators.

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