Soap-free polymerization preparation method of high solid content environmentally friendly fluorocarbon resin emulsion for coating

Abstract

The present invention belongs to the technical field of polymer synthesis, and discloses a soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating. The preparation method is as follows: under the condition of an initiator, a fluorinated olefin, other vinyl ether monomers, a polyoxyethylene ether, and water are mixed and dispersed, and then a polymerization reaction is carried out to obtain a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating; the solid content of the high-solid-content environmentally friendly fluorocarbon resin emulsion is above 50 wt%; the polyoxyethylene ether is a polyoxyethylene ether reactive macromonomer with a double bond and an ultra-long EO chain, and the EO number is ≥20. By introducing a polyoxyethylene ether macromonomer with a double bond and an ultra-long EO (≥20) chain, the present invention not only ensures the stability of the emulsion polymerization system, but also participates in the reaction as a reactive monomer, solving the problem that the emulsifier will float to the surface of the polymer during application, resulting in poor optical properties, electrical properties, and water resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer synthesis, and relates to a soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating. Background Art

[0002] Fluorocarbon resin (FEVE) is a polymer with fluorine atoms on the main chain or side chain, which is copolymerized from various fluorine-containing monomers and some non-fluorine-containing monomers. From a microscopic structure perspective, the fluorine atoms in FEVE form an almost complete cylindrical shell in a helical form and tightly surround the main chain. The F-C bond with strong bond energy wraps the C-C bond with weaker bond energy, making the polymer not easily damaged by external factors. Therefore, FEVE has various advantages such as excellent weather resistance, chemical stability, and mechanical strength.

[0003] Currently, the main methods for preparing FEVE fluorocarbon resin are solution polymerization and emulsion polymerization. The FEVE fluorocarbon resin prepared by solution polymerization contains a large amount of organic solvents. The emission of these organic solvents into the air will cause environmental pollution and also damage human health. Considering environmental protection, currently, waterborne fluorocarbon resins have received more and more attention. However, the general method for preparing waterborne fluorocarbon resins is emulsion polymerization.

[0004] High-solid-content emulsions have advantages such as high production efficiency, short film-forming time, and low storage and transportation costs. However, in most cases, the solid content of industrial emulsions is lower than 50 wt%. Exceeding this limit, the viscosity of the emulsion will increase sharply, the self-acceleration in the reaction will be more intense, the latex particles are prone to agglomeration, and a large amount of coagulum will appear, resulting in the failure of the reaction and making it difficult to prepare a stable polymer emulsion.

[0005] Emulsion polymerization uses water as the dispersion medium and has advantages such as fast polymerization rate, low system viscosity, and the ability to prepare high-molecular-weight polymers. However, in traditional emulsion polymerization, emulsifiers are often added to stabilize the latex particles. However, the presence of emulsifiers will have adverse effects on the optical properties, electrical properties, water resistance, etc. of the polymer, and at the same time, it also increases the cost of post-treatment and causes environmental pollution. Especially for the fluorine-containing emulsifiers used in the preparation of waterborne fluorocarbon resins, such as the already banned PFOA and alkylphenol emulsifiers, although they have high stability, once they enter the natural environment, they will exist in the soil and water bodies for a long time, are extremely difficult to degrade, and even migrate over long distances with the atmospheric circulation, causing global pollution. For example, in patent CN112679647B, a high-solid-content emulsion was prepared by a miniemulsion polymerization method that increases the emulsion particle size and broadens the particle size distribution. However, a banned fluorine-containing surfactant was used in its polymerization process, and the large particle size obtained by its polymerization is more likely to agglomerate, which will also reduce the emulsion stability.

[0006] To solve the above problems caused by the addition of emulsifiers, the existing technology has started to search for new preparation methods. For example, the soap-free emulsion polymerization method refers to the emulsion polymerization process in which no emulsifier is added at all or only a trace amount of emulsifier (its concentration is less than the critical micelle concentration CMC) is added during the reaction. However, the existing soap-free emulsion polymerization methods are more applied in the field of non-fluorinated polymers. When applied to the field of fluorinated polymers, due to the very low solubility of fluorinated monomers in water, most of them need to be captured by adding fluorinated emulsifiers during polymerization to carry out the polymerization reaction, and the presence of emulsifiers will affect the performance of the polymer.

[0007] Patent CN106519155B discloses a method for preparing a soap-free polymer emulsion with high solid content based on the semi-continuous feeding method. The preparation method uses Polymerization-Induced Self-Assembly (PISA) technology. The specific preparation process is as follows: First, water-soluble monomers, such as polyethylene glycol monomethyl ether methacrylate, are dissolved in water, and then polymerized into macromolecular RAFT reagents under the regulation of RAFT reagents. Then, the second monomer, methyl methacrylate, is slowly and uniformly added to the system in a semi-continuous feeding manner, and finally an amphiphilic block copolymer is prepared. However, this method requires the monomers to have water solubility, and the prepared soap-free polymer emulsion is an amphiphilic block copolymer and a non-fluorinated polymer at the same time. Its polymer molecular weight is low, and the polymerization process is cumbersome during the preparation process, requiring two-step polymerization.

[0008] Therefore, it is of great significance to study a soap-free polymerization preparation method for a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating to solve the above problems. Summary of the Invention

[0009] The purpose of the present invention is to solve the problems existing in the prior art and provide a soap-free polymerization preparation method for a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating.

[0010] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0011] A soap-free polymerization preparation method for a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating. Under the condition of an initiator, fluorinated olefins, other vinyl ether monomers, polyoxyethylene ether, and water are mixed and dispersed and then subjected to a polymerization reaction to obtain a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating;

[0012] The solid content of the high-solid-content environmentally friendly fluorocarbon resin emulsion is 50wt% or more;

[0013] The polyoxyethylene ether is a polyoxyethylene ether reactive macromonomer with a double bond and an ultra-long EO chain (-CH 2 CH 2 O-), and the EO number ≥ 20.

[0014] A soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating as described above, and the solid content of the high-solid-content environmentally friendly fluorocarbon resin emulsion is 50-60 wt%.

[0015] A soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating as described above, and the fluoroolefin is a compound having the structure shown in Formula I;

[0016] Formula I;

[0017] In Formula I, R 1 , R 2 , R 3 and R 4 are each independently selected from fluorine, chlorine, bromine, iodine, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl and C2-C12 haloalkenyl, and at least one fluorine atom is contained in Formula I;

[0018] The other vinyl ether monomers are the second monomer and the third monomer;

[0019] The second monomer is a compound having the structure shown in Formula II;

[0020] Formula II;

[0021] In Formula II, R 5 is selected from hydroxy-C1-C16 alkyl (i.e., alkyl with 1-16 carbon atoms containing a hydroxyl group), hydroxy-C3-C16 cycloalkyl, hydroxy-C6-C16 aryl, hydroxy-C6-C16 aralkyl, R 6 , R 7 and R 8 are each independently selected from hydrogen, fluorine, chlorine, bromine, iodine, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl and C2-C12 haloalkenyl;

[0022] The third monomer is a compound having the structure shown in Formula III;

[0023] Formula III;

[0024] In Formula III, R 9 is selected from C1-C24 alkyl, C3-C24 cycloalkyl, C6-C24 aryl and C6-C24 aralkyl; R 10 , R 11 and R 12 are each independently selected from hydrogen, fluorine, chlorine, bromine, iodine, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl and C2-C12 haloalkenyl;

[0025] The polyoxyethylene-based ether is a compound having the structure shown in Formula IV:

[0026] Formula IV;

[0027] In Formula IV, R is selected from C1-C24 straight-chain alkyl groups; n ≥ 20.

[0028] For the soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating as described above, the fluorinated olefin is tetrafluoroethylene or chlorotrifluoroethylene;

[0029] The second monomer is hydroxymethyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, hydroxypentyl vinyl ether, hydroxyhexyl vinyl ether, hydroxydecyl vinyl ether, hydroxydodecyl vinyl ether, hydroxyhexadecyl vinyl ether, hydroxycyclopropyl vinyl ether, hydroxycyclobutyl vinyl ether, hydroxycyclopentyl vinyl ether or hydroxycyclohexyl vinyl ether;

[0030] The third monomer is one or more of ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, heptyl vinyl ether, octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, hexadecyl vinyl ether, octadecyl vinyl ether, cyclobutyl vinyl ether, cyclopentyl vinyl ether and cyclohexyl vinyl ether.

[0031] For the soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating as described above, based on the total molar amount of the fluorinated olefin, other vinyl ether monomers and the polyoxyethylene-based ether, the content of the fluorinated olefin is 40-60 mol%, and the content of the polyoxyethylene-based ether is 0.1-5 mol%. Specifically, when the other vinyl ether monomers are the second monomer and the third monomer, the content of the second monomer is 3-30 mol%, and the content of the third monomer is 10-50 mol%.

[0032] For the soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating as described above, the number-average molecular weight Mn of the polymer in the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 30,000-100,000, and the optimal number-average molecular weight is 50,000-70,000.

[0033] For the soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating as described in any one of the above, the specific preparation steps are as follows:

[0034] (1) Add other vinyl ether monomers, polyoxyethylene-based ether and water into the reaction kettle at one time, evacuate to vacuum and perform nitrogen replacement until the oxygen content in the reaction kettle is lower than 50 ppm;

[0035] (2) Add fluorinated olefins to the reactor in step (1). After heating to 40 - 70 °C, start adding the initiator for polymerization reaction. The initiator is continuously added within 4 h. After adding, continue the reaction for 1 h to end the polymerization reaction.

[0036] (3) Transfer the reaction product of step (2) to a rotary evaporator for concentration treatment to make the solid content of the material above 50 wt%, obtaining a high solid content environmentally friendly fluorocarbon resin emulsion for coating.

[0037] Principle of the invention:

[0038] In the present invention, by adding a polyoxyethylene-based macromonomer with a double bond and an ultra-long EO (≥20) chain, which has the function of an emulsifier. Under the background that PFAS is clearly prohibited at present, it not only ensures the stability of the emulsion polymerization system, but also participates in the reaction as a reaction monomer, solving the problem that the emulsifier will float to the surface of the polymer during application, resulting in poor optical properties, electrical properties, and water resistance. Specifically, during emulsion polymerization, the polyoxyethylene-based macromonomer used in the present invention has a large EO number. The EO chain in the polyoxyethylene-based macromonomer wraps around the latex particles (i.e., the particles in which the polymer is dispersed in the aqueous phase during the reaction process), forming a large steric hindrance, making the latex particles not easily agglomerate and the emulsion particles more stable, playing the role of a surfactant; and with a large EO number, it has strong hydrophilicity, which is beneficial to enhancing the dispersion of the latex particles in the aqueous phase. In addition, for the fluororesin FEVE, its fluorinated monomer such as chlorotrifluoroethylene is insoluble in water and soluble in ether. The addition of a polyoxyethylene-based ether with a water-soluble ultra-long EO (≥20) chain can also increase the solubility of the fluorinated monomer in the aqueous phase, making soap-free polymerization possible.

[0039] The present invention technically breaks through the limitations of traditional polymerization for preparing coatings, which is not only ecological and environmentally friendly but also can endow the fluororesin with better properties: such as excellent water resistance, fine particle size and good stability, etc., reducing the production cost and expanding the scope of product use.

[0040] Beneficial effects:

[0041] (1) By introducing a polyoxyethylene-based macromonomer with an ultra-long EO (≥20) chain, the present invention not only ensures the stability of the emulsion polymerization system, but also participates in the reaction as a reaction monomer, solving the problem that the emulsifier will float to the surface of the polymer during application, resulting in poor optical properties, electrical properties, and water resistance.

[0042] (2) The preparation method of the present invention is not only ecological and environmentally friendly, but also can endow the fluororesin with better properties, while reducing the production cost and expanding the scope of product use. Description of the drawings

[0043] Figure 1 FT-IR spectrum of the high solid content environmentally friendly fluorocarbon resin emulsion for coating prepared in Example 1. Specific embodiments

[0044] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0045] The test methods for relevant performance indicators in the following examples and comparative examples are as follows:

[0046] Water resistance: Referring to Method A (immersion test method) in GB / T 1733-1993, the water resistance of the high solid content environmentally friendly fluorocarbon resin emulsion for coating prepared in each example and comparative example was tested. Specifically: Distilled water was added to a glass water tank, the water temperature was adjusted to 25 °C and maintained at this temperature throughout the test process. Then, the high solid content environmentally friendly fluorocarbon resin emulsion was respectively coated on three test panels and placed in the glass water tank so that 2 / 3 of the length of each test panel was immersed in water for 168 h. After the immersion was completed, the test panels were taken out and blotted dry with filter paper. Subsequently, it was checked and recorded whether there were coating film pathological phenomena such as blistering, cracking, peeling, powdering, obvious color change, and obvious loss of gloss on the 3 test panels. If at least 2 test panels did not show pathological phenomena, it was determined to be normal (i.e., qualified).

[0047] Viscosity: The viscosity of the high solid content environmentally friendly fluorocarbon resin emulsion for coating prepared in each example and comparative example was tested using a rotary evaporation viscometer (BGD 152 / 1S), and the test temperature condition was 25 °C.

[0048] Example 1

[0049] A soap-free polymerization preparation method of a high solid content environmentally friendly fluorocarbon resin emulsion for coating, the steps are as follows:

[0050] (1) Hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene ether (chemical formula is , R is a straight-chain alkyl group, the number of EO is 40, and the number average molecular weight is 1876) and water were added to the reaction kettle at one time, evacuated and replaced with nitrogen until the oxygen content in the reaction kettle was 35 ppm; among them, the content of water was 50 wt% of the total addition amount in this step;

[0051] (2) Add chlorotrifluoroethylene to the reactor in step (1). After heating to 50 °C, start adding an initiator (a redox system of potassium persulfate and sodium sulfite, where the mass ratio of potassium persulfate to sodium sulfite is 5:2) for polymerization reaction. Continuously add the initiator within 4 h, and continue the reaction for 1 h after adding to end the polymerization reaction. Finally, concentrate the reaction material to obtain a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50 wt%.

[0052] During the processes of steps (1) and (2), based on the total molar amount of hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene vinyl ether and chlorotrifluoroethylene, the content of chlorotrifluoroethylene is 50 mol%, the content of hydroxybutyl vinyl ether is 11 mol%, the content of ethyl vinyl ether is 20 mol%, the content of cyclohexyl vinyl ether is 18 mol%, the content of polyoxyethylene vinyl ether is 1 mol%, and the content of the initiator is 1 wt%.

[0053] The finally prepared high-solid-content environmentally friendly fluorocarbon resin emulsion for coating has a viscosity of 50 mPa·s, a hydroxyl value of 45 mgKOH / g, a fluorine content of 19.9 wt%, and an average particle size of 81 nm; the number-average molecular weight Mn of the polymer in the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 69541.

[0054] As Figure 1 shown, C-Cl and C-F show stretching vibrations at 842 cm -1 and 957 cm -1 respectively, the F-C-F bond shows an asymmetric stretching vibration at 1343 cm -1 , the C-O-C bond shows a peak at 1105 cm -1 , the characteristic peak of CH 2 appears at 2860 cm -1 , cyclohexane has a bending vibration peak at 1452 cm -1 , and no strong absorption peak of C=C double bond is found at 1600 cm -1 . Therefore, the FT-IR spectrum shows that polyoxyethylene vinyl ether participates in the reaction and is successfully polymerized into the polymer.

[0055] After placing 50 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating at 25 °C for 6 months, the emulsion does not show a layering phenomenon. At the same time, take 1 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating and centrifuge it at a speed of 10000 r / 30 min for 30 min, and the emulsion does not show a layering; conduct a water resistance test on the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating, and the result is normal.

[0056] Comparative Example 1

[0057] A soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating, which is basically the same as Example 1, except that: the EO number of the EO chain of the polyoxyethylene-based ether used in step (1) is 10.

[0058] The viscosity of the finally prepared high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 61 mPa·s, the hydroxyl value is 41 mgKOH / g, the fluorine content is 19.5 wt%, and the average particle size is 216 nm; the number-average molecular weight Mn of the polymer in the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 56159;

[0059] After placing 50 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating at 25 °C for 6 months, the emulsion shows a layering phenomenon. At the same time, 1 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is taken and centrifuged at a speed of 10000 r / 30 min for 30 min, and the emulsion shows a layering phenomenon.

[0060] Comparing Comparative Example 1 with Example 1, it can be seen that the stability of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating prepared in Comparative Example 1 is poor. This is because the EO number of the EO chain of the polyoxyethylene-based ether used in Comparative Example 1 is too small. When the EO chain in the polyoxyethylene-based ether macromonomer wraps around the latex particles, the formed steric hindrance is small, which will result in poor stability of the emulsion, and the latex particles are more likely to agglomerate, resulting in a large amount of coagulum during the reaction polymerization process, and ultimately leading to poor film-forming property of the emulsion.

[0061] Example 2

[0062] A soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating, the steps are as follows:

[0063] (1) Add hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene-based ether (chemical formula is , R is a straight-chain alkyl group, the EO number is 40, and the number-average molecular weight is 1876) and water into the reaction kettle at one time, evacuate and carry out nitrogen replacement until the oxygen content in the reaction kettle is 35 ppm; among them, the content of water is 50 wt% of the total addition amount of this step;

[0064] (2) Add chlorotrifluoroethylene to the reaction kettle in step (1), heat up to 50 °C, and then start to add the initiator (redox system of potassium persulfate and sodium sulfite, where the mass ratio of potassium persulfate to sodium sulfite is 5:2) for polymerization reaction. The initiator is continuously added within 4 h, and after adding, continue to react for 1 h to end the polymerization reaction. Finally, concentrate the reaction material to obtain a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50 wt%;

[0065] During the processes of steps (1) and (2), based on the total molar amount of hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene vinyl ether and chlorotrifluoroethylene, the content of chlorotrifluoroethylene is 50 mol%, the content of hydroxybutyl vinyl ether is 11 mol%, the content of ethyl vinyl ether is 17 mol%, the content of cyclohexyl vinyl ether is 18 mol%, the content of polyoxyethylene vinyl ether is 4 mol%, and the content of the initiator is 1 wt%.

[0066] The viscosity of the finally prepared high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 50 mPa·s, the hydroxyl value is 42 mgKOH / g, the fluorine content is 19.7 wt%, and the average particle size is 72 nm; the number-average molecular weight Mn of the polymer in the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 68,253;

[0067] After placing 50 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating at 25°C for 6 months, the emulsion did not show any layering phenomenon. At the same time, 1 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating was taken and centrifuged at a speed of 10,000 r / 30 min for 30 min in a centrifuge, and the emulsion did not show any layering; the water resistance test was carried out on the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating, and the result was normal.

[0068] Example 3

[0069] A soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating, the steps are as follows:

[0070] (1) Cyclohexyl-1,4-dimethanol mono vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene vinyl ether (chemical formula is , R is a straight-chain alkyl group, the number of EO is 40, and the number-average molecular weight is 1876) and water are added to the reaction kettle at one time, evacuated and replaced with nitrogen until the oxygen content in the reaction kettle is 35 ppm; among them, the content of water is 50 wt% of the total addition amount of this step;

[0071] (2) Chlorotrifluoroethylene is added to the reaction kettle in step (1), and after heating to 50°C, an initiator (a redox system of potassium persulfate and sodium sulfite, where the mass ratio of potassium persulfate to sodium sulfite is 5:2) is added to start the polymerization reaction. The initiator is continuously added within 4 h, and after adding, the reaction continues for 1 h to end the polymerization reaction. Finally, the reaction material is concentrated to obtain a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50 wt%;

[0072] During the processes of steps (1) and (2), based on the total molar amount of cyclohexane-1,4-dimethanol mono vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene ether and chlorotrifluoroethylene, the content of chlorotrifluoroethylene is 50 mol%, the content of cyclohexane-1,4-dimethanol mono vinyl ether is 11 mol%, the content of ethyl vinyl ether is 19 mol%, the content of cyclohexyl vinyl ether is 18 mol%, the content of polyoxyethylene ether is 2 mol%, and the content of the initiator is 1 wt%.

[0073] The viscosity of the finally prepared high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 50 mPa·s, the hydroxyl value is 41 mgKOH / g, the fluorine content is 18.5 wt%, and the average particle size is 84 nm; the number-average molecular weight Mn of the polymer in the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 71969;

[0074] After 50 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating was placed at 25°C for 6 months, no delamination occurred in the emulsion. At the same time, 1 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating was taken and centrifuged at a speed of 10000 r / 30 min for 30 min in a centrifuge, and no delamination occurred in the emulsion; the water resistance test of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating was carried out, and the result was normal.

[0075] Example 4

[0076] A soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating, the steps are as follows:

[0077] (1) Hydroxybutyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene ether (chemical formula is , R is a straight-chain alkyl group, the number of EO is 40, and the number-average molecular weight is 1876) and water are added to the reaction kettle at one time, evacuated and purged with nitrogen until the oxygen content in the reaction kettle is 35 ppm; among them, the content of water is 50 wt% of the total addition amount of this step;

[0078] (2) Chlorotrifluoroethylene is added to the reaction kettle in step (1), and the temperature is raised to 50°C, and then the initiator (redox system of potassium persulfate and sodium sulfite, where the mass ratio of potassium persulfate to sodium sulfite is 5:2) is added to carry out the polymerization reaction. The initiator is continuously added within 4 h, and after adding, the reaction continues for 1 h to end the polymerization reaction. Finally, the reaction material is concentrated to obtain a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50 wt%.

[0079] In the processes of steps (1) and (2), based on the total molar amount of hydroxybutyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene vinyl ether and chlorotrifluoroethylene, the content of chlorotrifluoroethylene is 50 mol%, the content of hydroxybutyl vinyl ether is 11 mol%, the content of butyl vinyl ether is 19 mol%, the content of cyclohexyl vinyl ether is 18 mol%, the content of polyoxyethylene vinyl ether is 2 mol%, and the content of the initiator is 1 wt%.

[0080] The viscosity of the finally prepared high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 50 mPa·s, the hydroxyl value is 42 mgKOH / g, the fluorine content is 19.1 wt%, and the average particle size is 84 nm; the number-average molecular weight Mn of the polymer in the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating is 70298;

[0081] After placing 50 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating at 25°C for 6 months, no layering phenomenon occurred in the emulsion. At the same time, 1 ml of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating was taken and centrifuged at a speed of 10000 r / 30 min for 30 min in a centrifuge, and no layering occurred in the emulsion; the water resistance test of the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating was carried out, and the result was normal.

[0082] Example 5

[0083] A soap-free polymerization preparation method of a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating, the steps are as follows:

[0084] (1) Hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene vinyl ether (chemical formula is , R is a straight-chain alkyl group, the number of EO is 60, and the number-average molecular weight is 2756) and water are added to the reaction kettle at one time, evacuated and replaced with nitrogen until the oxygen content in the reaction kettle is 35 ppm; among them, the content of water is 50 wt% of the total addition amount of this step;

[0085] (2) Chlorotrifluoroethylene is added to the reaction kettle in step (1), and after heating to 50°C, an initiator (redox system of potassium persulfate and sodium sulfite, where the mass ratio of potassium persulfate to sodium sulfite is 5:2) is added to carry out the polymerization reaction. The initiator is continuously added within 4 h, and after adding, the reaction continues for 1 h to end the polymerization reaction. Finally, the reaction material is concentrated to obtain a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50 wt%;

[0086] In the processes of steps (1) and (2), based on the total molar amount of hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene vinyl ether and chlorotrifluoroethylene, the content of chlorotrifluoroethylene is 50 mol%, the content of hydroxybutyl vinyl ether is 11 mol%, the content of ethyl vinyl ether is 9 mol%, the content of cyclohexyl vinyl ether is 28 mol%, the content of polyoxyethylene vinyl ether is 2 mol%, and the content of the initiator is 1 wt%.

[0087] The viscosity of the finally prepared high-solid content environmentally friendly fluorocarbon resin emulsion for coating is 50 mPa·s, the hydroxyl value is 41 mgKOH / g, the fluorine content is 19 wt%, the average particle size is 89 nm; the number-average molecular weight Mn of the polymer in the high-solid content environmentally friendly fluorocarbon resin emulsion for coating is 83077;

[0088] After placing 50 ml of the high-solid content environmentally friendly fluorocarbon resin emulsion for coating at 25°C for 6 months, no delamination occurred in the emulsion. At the same time, 1 ml of the high-solid content environmentally friendly fluorocarbon resin emulsion for coating was taken and centrifuged at a speed of 10000 r / 30 min for 30 min in a centrifuge, and no delamination occurred in the emulsion; the water resistance of the high-solid content environmentally friendly fluorocarbon resin emulsion for coating was tested, and the result was normal.

Claims

1. A method for preparing a high solid content environmentally friendly fluorocarbon resin emulsion for coating by soap-free polymerization, characterized in that: Under the condition of an initiator, fluorine-containing olefins, other vinyl ether monomers, polyoxyethylene ether and water are mixed and dispersed, and then polymerized to obtain a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating; The solid content of the high solid content environmentally friendly fluorocarbon resin emulsion is more than 50wt%; Polyoxyethylene ether is a polyoxyethylene ether reactive macromonomer with double bonds and ultra-long EO chains, and the EO number is ≥20; Based on the total molar amount of fluorinated olefin, other vinyl ether monomers and polyoxyethylene ether, the content of fluorinated olefin is 40-60 mol%, and the content of polyoxyethylene ether is 0.1-5 mol%; The fluorinated olefin is a compound having a structure shown in Formula I; In Formula I, R 1 , R 2 , R 3 and R 4 Each is independently selected from fluorine, chlorine, bromine, iodine, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl and C2-C12 haloalkenyl, and Formula I contains at least one fluorine atom; The other vinyl ether monomers are the second monomer and the third monomer; The second monomer is a compound having a structure shown in Formula II; In Formula II, R 5 is selected from hydroxy-C1-C16 alkyl, hydroxy-C3-C16 cycloalkyl, hydroxy-C6-C16 aryl, hydroxy-C6-C16 aralkyl, R 6 , R 7 and R 8 Each is independently selected from hydrogen, fluorine, chlorine, bromine, iodine, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl and C2-C12 haloalkenyl; The third monomer is a compound having a structure shown in Formula III; In Formula III, R 9 is selected from C1-C24 alkyl, C3-C24 cycloalkyl, C6-C24 aryl and C6-C24 aralkyl; R 10 , R 11 and R 12 Each is independently selected from hydrogen, fluorine, chlorine, bromine, iodine, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl and C2-C12 haloalkenyl; Polyoxyethylene ether is a compound having a structure shown in Formula IV; In formula IV, R is selected from C1-C24 straight chain alkylene; n≥20.

2. The method for preparing a high solid content environmentally friendly fluorocarbon resin emulsion for coating by soap-free polymerization according to claim 1, characterized in that: The solid content of the high-solid-content environmentally friendly fluorocarbon resin emulsion is 50-60wt%.

3. The soap-free polymerization preparation method of a high solid content environmentally friendly fluorocarbon resin emulsion for coating according to claim 1, characterized in that: The fluorinated olefin is tetrafluoroethylene or chlorotrifluoroethylene; The second monomer is hydroxymethyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, hydroxypentyl vinyl ether, hydroxyhexyl vinyl ether, hydroxydecyl vinyl ether, hydroxydodecyl vinyl ether, hydroxyhexadecyl vinyl ether, hydroxycyclopropyl vinyl ether, hydroxycyclobutyl vinyl ether, hydroxycyclopentyl vinyl ether or hydroxycyclohexyl vinyl ether; The third monomer is one or more of ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, heptyl vinyl ether, octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, hexadecyl vinyl ether, octadecyl vinyl ether, cyclobutyl vinyl ether, cyclopentyl vinyl ether and cyclohexyl vinyl ether.

4. The soap-free polymerization method for preparing a high solid content environmentally friendly fluorocarbon resin emulsion for coating according to claim 1, characterized in that: The number average molecular weight Mn of the polymer in the high solid content environmentally friendly fluorocarbon resin emulsion for coating is 30,000-100,000.

5. The soap-free polymerization preparation method of a high solid content environmentally friendly fluorocarbon resin emulsion for coating according to any one of claims 1 to 4, characterized in that: The specific preparation steps are as follows: (1) adding other vinyl ether monomers, polyoxyethylene ether and water into a reaction kettle at once, evacuating the kettle and replacing the air with nitrogen until the oxygen content in the reaction kettle is less than 50 ppm; (2) adding fluorinated olefins to the reaction kettle of step (1), heating to 40-70° C. and then adding initiators to carry out polymerization reaction. The initiators are continuously added within 4 hours. After the addition is completed, the reaction is continued for 1 hour to terminate the polymerization reaction; (3) The reaction product of step (2) is transferred to a rotary evaporator for concentration to obtain an environmentally friendly fluorocarbon resin emulsion with a high solid content for coating.

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