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

Abstract

The invention belongs to the technical field of polymer synthesis, and discloses a soap-free polymerization preparation method of a high-solid-content environment-friendly fluorocarbon resin emulsion for coating, which comprises the following steps: in the presence of an initiator, mixing and dispersing fluorine-containing olefin, other vinyl ether monomers, polyoxyethylene ether and water, and then carrying out polymerization reaction to obtain the high-solid-content environment-friendly fluorocarbon resin emulsion. The high-solid-content environment-friendly fluorocarbon resin emulsion for coating is prepared; the solid content of the high-solid-content environment-friendly fluorocarbon resin emulsion is 50 wt% or above; the polyoxyethylene ether is a polyoxyethylene ether reaction type macromonomer with double bonds and a super-long EO chain, and the EO number is greater than or equal to 20. By introducing the polyoxyethylene ether macromonomer with double bonds and an ultra-long EO (greater than or equal to 20) chain, the stability of an emulsion polymerization system is ensured, and meanwhile, the polyoxyethylene ether macromonomer participates in the reaction as a reaction monomer, so that the problems of poor optical property, electrical property and water resistance caused by the fact that an emulsifier floats on the surface of a polymer in the application process are solved.

Description

Technical Field

[0001] The 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 made by copolymerizing various fluorine-containing monomers with some fluorine-free monomers. From the microscopic structure point of view, the fluorine atoms in FEVE form an almost complete cylindrical shell in the form of a spiral, and tightly surround the main chain. The FC bond with strong bond energy wraps the CC bond with weaker bond energy, making the polymer not easily destroyed by external factors. Therefore, FEVE has various advantages such as excellent weather resistance, chemical stability, and mechanical strength.

[0003] At present, the main methods for preparing FEVE fluorocarbon resins are solution polymerization and emulsion polymerization. FEVE fluorocarbon resins prepared by solution polymerization contain a large amount of organic solvents, which will cause environmental pollution and damage human health when discharged into the air. Based on environmental protection considerations, water-based fluorocarbon resins have received more and more attention, but the method for preparing water-based fluorocarbon resins is generally emulsion polymerization.

[0004] High solid content emulsion has the advantages of high production efficiency, short film-forming time, and low storage and transportation costs. However, in most cases, the solid content of industrial emulsion is less than 50wt%. If it exceeds this limit, the viscosity of the emulsion will increase sharply, the self-acceleration in the reaction will be more intense, the latex particles will easily agglomerate, and a large amount of coagulants will appear, resulting in reaction failure and difficulty in preparing a stable polymer emulsion.

[0005] Emulsion polymerization uses water as a 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 latex particles, but the presence of emulsifiers can have adverse effects on the optical properties, electrical properties, water resistance, etc. of the polymer, and also increase the cost of post-processing, causing pollution to the environment, especially the fluorinated emulsifiers used in the preparation of water-based fluorocarbon resins, such as the banned PFOA and alkylphenol emulsifiers, although they have very high stability, once entering the natural environment, they will exist in soil and water bodies for a long time, are extremely difficult to degrade, and even migrate over long distances with atmospheric circulation, causing global pollution. For example, in patent CN112679647B, a high solid content emulsion is prepared by increasing the emulsion particle size and widening the particle size distribution through a mini-emulsion polymerization method, but the banned fluorinated surfactant is used in its polymerization process, and the large particle size obtained by its polymerization will be more easily agglomerated, which will also reduce the emulsion stability.

[0006] In order to solve the above problems caused by the addition of emulsifiers, the prior art began to look for new preparation methods. For example, the soap-free emulsion polymerization method refers to an emulsion polymerization process in which no emulsifier is added at all or only a trace amount of emulsifier (whose concentration is less than the critical micelle concentration CMC) is added during the reaction. However, the soap-free emulsion polymerization method of the prior art is more used in the field of non-fluorine-containing polymers. When applied to the field of fluorine-containing polymers, since the solubility of fluorine-containing monomers in water is very low, most of them require the addition of fluorine-containing emulsifiers during polymerization to capture the fluorine-containing monomers and carry out polymerization reactions, and the presence of emulsifiers will affect the properties of the polymer.

[0007] Patent CN106519155B discloses a method for preparing a high-solid content soap-free polymer emulsion based on a semi-continuous feeding method. The preparation method adopts the polymerization-induced self-assembly (PISA) technology. The specific preparation process is: firstly, a water-soluble monomer, such as polyethylene glycol monomethyl ether methacrylate, is dissolved in water, and then polymerized into a macromolecular RAFT agent under the control of a RAFT agent, and 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 that the monomer is water-soluble, and the prepared soap-free polymer emulsion is an amphiphilic block copolymer and a non-fluorinated polymer at the same time, and its polymer molecular weight is low, and the polymerization process in the preparation process is cumbersome and requires two-step polymerization.

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

[0010] To achieve the above object, 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, wherein fluorine-containing olefins, other vinyl ether monomers, polyoxyethylene ether and water are mixed and dispersed under the condition of an initiator, and then a polymerization reaction is carried out to prepare the high-solid-content environmentally friendly fluorocarbon resin emulsion for coating;

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

[0013] Polyoxyethylene ether is a polyoxyethylene ether reactive macromonomer with double bonds and super long EO chains (-CH2CH2O-), and the EO number is ≥20.

[0014] According to the soap-free polymerization method for preparing 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 50-60wt%.

[0015] The soap-free polymerization method for preparing a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating as described above, wherein the fluorinated olefin is a compound having a structure shown in Formula I;

[0016] Formula I;

[0017] 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;

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

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

[0020] Formula II;

[0021] In Formula II, R 5 is selected from hydroxy-C1~C16 alkyl (i.e., an alkyl group with 1 to 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 Each is 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 a 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 Each is independently selected from hydrogen, fluorine, chlorine, bromine, iodine, C1~C12 alkyl, C1~C12 haloalkyl, C2~C12 alkenyl and C2~C12 haloalkenyl;

[0025] Polyoxyethylene 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; n≥20.

[0028] A soap-free polymerization method for preparing a high-solid-content environmentally friendly fluorocarbon resin emulsion for coating as described above, wherein 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] In 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 fluorinated olefins, other vinyl ether monomers and polyoxyethylene ether, the content of fluorinated olefins is 40-60 mol%, and the content of polyoxyethylene 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] According to the soap-free polymerization preparation method of the high solid content environmentally friendly fluorocarbon resin emulsion for coating, 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] A soap-free polymerization preparation method for a high solid content environmentally friendly fluorocarbon resin emulsion for coating as described in any of the above items, the specific preparation steps are as follows:

[0034] (1) Add other vinyl ether monomers, polyoxyethylene ether and water into the reactor at one time, evacuate the reactor and replace with nitrogen until the oxygen content in the reactor is less than 50 ppm;

[0035] (2) Add fluorinated olefins to the reactor of step (1), raise the temperature to 40-70°C, and then start adding initiators to carry out polymerization reaction. The initiators are added continuously within 4 hours. After the addition is completed, the reaction is continued for 1 hour to terminate the polymerization reaction;

[0036] (3) The reaction product of step (2) is transferred to a rotary evaporator for concentration treatment so that the solid content of the material is greater than 50 wt %, thereby 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 ether macromonomer having a double bond and an ultra-long EO (≥20) chain, it has the function of an emulsifier. In the current context where PFAS is explicitly banned, it 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 the application process, resulting in poor optical properties, electrical properties, and water resistance. Specifically, during emulsion polymerization, the polyoxyethylene ether macromonomer used in the present invention has a large EO number, and the EO chain in the polyoxyethylene ether macromonomer is wrapped around the latex particles (i.e., the particle shape of the high molecular polymer dispersed in the water phase during the reaction process), forming a large steric hindrance, making it difficult for the latex particles to agglomerate, and the latex particles are more stable, playing the role of a surfactant; and the large EO number and strong hydrophilicity are conducive to enhancing the dispersibility of the latex particles in the water phase. In addition, for the fluorine-containing resin FEVE, its fluorine-containing monomers such as trifluorochloroethylene are insoluble in water but soluble in ether. The addition of polyoxyethylene ether with water-soluble ultra-long EO (≥20) chains can also increase the solubility of the fluorine-containing monomers in the aqueous phase, making soap-free polymerization possible.

[0039] The present invention technically breaks through the limitations of traditional polymerized coatings, is not only environmentally friendly but also can give fluorine-containing resins better properties, such as excellent water resistance, fine particle size and good stability, thereby reducing production costs and expanding the scope of product use.

[0040] Beneficial effects:

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

[0042] (2) The preparation method of the present invention is not only environmentally friendly, but also can give the fluorine-containing resin better properties, while reducing production costs and expanding the scope of product use. BRIEF DESCRIPTION OF THE DRAWINGS

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

[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 are not intended 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 fall within the scope limited by the appended claims of the application equally.

[0045] The testing methods of the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0046] Water resistance: referring to Method A (immersion test method) of GB / T 1733-1993, the water resistance test of the high solid content environmentally friendly fluorocarbon resin emulsion for coating prepared in each embodiment and comparative example is carried out, specifically: adding distilled water into a glass water tank, adjusting the water temperature to 25°C and maintaining the temperature during the whole test process, then coating the high solid content environmentally friendly fluorocarbon resin emulsion on three test panels respectively, and placing them into a glass water tank so that 2 / 3 of the length of each test panel is immersed in water for 168h, after the immersion is completed, taking them out and drying them with filter paper, then checking and recording whether the three test panels have blistering, cracking, peeling, powdering, obvious discoloration, obvious gloss loss and other coating pathological phenomena, if at least two panels do not show any pathological phenomena, it is judged 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 embodiment and comparative example was tested using a rotary evaporation viscometer (BGD 152 / 1S) at a temperature of 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: , R is a straight-chain alkyl group, the EO number is 40, and the number average molecular weight is 1876) and water are added to the reactor at one time, and the reactor is evacuated and replaced with nitrogen until the oxygen content in the reactor is 35ppm; wherein the water content is 50wt% of the total amount added in this step;

[0051] (2) adding chlorotrifluoroethylene to the reactor of step (1), heating to 50° C. and then adding an initiator (a redox system of potassium persulfate and sodium sulfite, wherein the mass ratio of potassium persulfate to sodium sulfite is 5:2) to carry out a polymerization reaction, adding the initiator continuously within 4 hours, and continuing the reaction for 1 hour after the addition to terminate the polymerization reaction, and finally concentrating the reaction material to obtain a high solid content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50wt%;

[0052] In the process of steps (1) and (2), based on the total molar amount of hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene 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 ether is 1 mol%, and the content of initiator is 1 wt%.

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

[0054] like Figure 1 As shown in Figure 2, C-Cl and CF are at 842 cm -1 and 957 cm -1 The FCF bond has a stretching vibration at 1343 cm -1 Asymmetric stretching vibration occurs at 1105 cm -1 The peak of CH2 appears at 2860cm -1 , cyclohexane at 1452 cm -1 There is a bending vibration peak at 1600cm -1 No strong absorption peak of C=C double bond was found. Therefore, FT-IR spectrum showed that polyoxyethylene ether participated in the reaction and was successfully polymerized in the polymer.

[0055] After 50 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was placed at 25°C for 6 months, the emulsion did not show stratification. At the same time, 1 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was centrifuged at a speed of 10000r / 30min for 30min in a centrifuge, and the emulsion did not show stratification. The high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was tested for water resistance, and the result was normal.

[0056] Comparative Example 1

[0057] A soap-free polymerization method for preparing a high-solid content environmentally friendly fluorocarbon resin emulsion for coating is basically the same as Example 1, except that the EO number of the EO chain of the polyoxyethylene 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 61mPa·s, the hydroxyl value is 41mgKOH / g, the fluorine content is 19.5wt%, and the average particle size is 216nm; 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 50 ml of high-solid-content environmentally friendly fluorocarbon resin emulsion for coating was placed at 25°C for 6 months, the emulsion showed stratification. At the same time, after 1 ml of high-solid-content environmentally friendly fluorocarbon resin emulsion for coating was centrifuged at a speed of 10000r / 30min for 30min, the emulsion showed stratification.

[0060] By comparing Comparative Example 1 with Example 1, it can be seen that the high-solid content environmentally friendly fluorocarbon resin emulsion for coating prepared in Comparative Example 1 has poor stability. This is because the EO number of the EO chain of the polyoxyethylene ether used in Comparative Example 1 is too small. When the EO chain in the polyoxyethylene ether macromonomer is wrapped around the latex particles, the formed steric hindrance is small, which will make the emulsion stable, and the latex particles are more likely to agglomerate, resulting in a large amount of coagulants during the reaction polymerization process, which ultimately leads to poor film-forming properties 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) Hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene ether (chemical formula: , R is a straight-chain alkyl group, the EO number is 40, and the number average molecular weight is 1876) and water are added to the reactor at one time, and the reactor is evacuated and replaced with nitrogen until the oxygen content in the reactor is 35ppm; wherein the water content is 50wt% of the total amount added in this step;

[0064] (2) adding chlorotrifluoroethylene to the reactor of step (1), heating to 50° C. and then adding an initiator (a redox system of potassium persulfate and sodium sulfite, wherein the mass ratio of potassium persulfate to sodium sulfite is 5:2) to carry out a polymerization reaction, adding the initiator continuously within 4 hours, and continuing the reaction for 1 hour after the addition to terminate the polymerization reaction, and finally concentrating the reaction material to obtain a high solid content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50wt%;

[0065] In the process of steps (1) and (2), based on the total molar amount of hydroxybutyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene 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 ether is 4 mol%, and the content of initiator is 1 wt%.

[0066] The final high solid content environmentally friendly fluorocarbon resin emulsion for coating has a viscosity of 50mPa·s, a hydroxyl value of 42mgKOH / g, a fluorine content of 19.7wt%, and an average particle size of 72nm; the number average molecular weight Mn of the polymer in the high solid content environmentally friendly fluorocarbon resin emulsion for coating is 68253;

[0067] After 50 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was placed at 25°C for 6 months, the emulsion did not show stratification. At the same time, 1 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was centrifuged at a speed of 10000r / 30min for 30min in a centrifuge, and the emulsion did not show stratification. The high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was tested for water resistance, 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 monovinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene ether (chemical formula: , R is a straight-chain alkyl group, the EO number is 40, and the number average molecular weight is 1876) and water are added to the reactor at one time, and the reactor is evacuated and replaced with nitrogen until the oxygen content in the reactor is 35ppm; wherein the water content is 50wt% of the total amount added in this step;

[0071] (2) adding chlorotrifluoroethylene to the reactor of step (1), heating to 50° C. and then adding an initiator (a redox system of potassium persulfate and sodium sulfite, wherein the mass ratio of potassium persulfate to sodium sulfite is 5:2) to carry out a polymerization reaction, adding the initiator continuously within 4 hours, and continuing the reaction for 1 hour after the addition to terminate the polymerization reaction, and finally concentrating the reaction material to obtain a high solid content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50wt%;

[0072] In the process of steps (1) and (2), based on the total molar amount of cyclohexyl-1,4-dimethanol monovinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, polyoxyethylene ether and chlorotrifluoroethylene, the content of chlorotrifluoroethylene is 50 mol%, the content of cyclohexyl-1,4-dimethanol monovinyl 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 initiator is 1 wt%.

[0073] The final high solid content environmentally friendly fluorocarbon resin emulsion for coating has a viscosity of 50mPa·s, a hydroxyl value of 41mgKOH / g, a fluorine content of 18.5wt%, and an average particle size of 84nm; 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, the emulsion did not show stratification. At the same time, 1 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was centrifuged at a speed of 10000r / 30min for 30min in a centrifuge, and the emulsion did not show stratification. The high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was tested for water resistance, 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: , R is a straight-chain alkyl group, the EO number is 40, and the number average molecular weight is 1876) and water are added to the reactor at one time, and the reactor is evacuated and replaced with nitrogen until the oxygen content in the reactor is 35ppm; wherein the water content is 50wt% of the total amount added in this step;

[0078] (2) adding chlorotrifluoroethylene to the reactor of step (1), heating to 50° C. and then adding an initiator (a redox system of potassium persulfate and sodium sulfite, wherein the mass ratio of potassium persulfate to sodium sulfite is 5:2) to carry out a polymerization reaction, adding the initiator continuously within 4 hours, and continuing the reaction for 1 hour after the addition to terminate the polymerization reaction, and finally concentrating the reaction material to obtain a high solid content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50wt%;

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

[0080] The final high solid content environmentally friendly fluorocarbon resin emulsion for coating has a viscosity of 50 mPa·s, a hydroxyl value of 42 mgKOH / g, a fluorine content of 19.1 wt%, and an average particle size of 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 50 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was placed at 25°C for 6 months, the emulsion did not show stratification. At the same time, 1 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was centrifuged at a speed of 10000r / 30min for 30min in a centrifuge, and the emulsion did not show stratification. The high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was tested for water resistance, 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 ether (chemical formula: , R is a straight-chain alkyl group, the EO number is 60, and the number average molecular weight is 2756) and water are added to the reactor at one time, and vacuum is evacuated and replaced with nitrogen until the oxygen content in the reactor is 35ppm; wherein the water content is 50wt% of the total amount added in this step;

[0085] (2) adding chlorotrifluoroethylene to the reactor of step (1), heating to 50° C. and then adding an initiator (a redox system of potassium persulfate and sodium sulfite, wherein the mass ratio of potassium persulfate to sodium sulfite is 5:2) to carry out a polymerization reaction, adding the initiator continuously within 4 hours, and continuing the reaction for 1 hour after the addition to terminate the polymerization reaction, and finally concentrating the reaction material to obtain a high solid content environmentally friendly fluorocarbon resin emulsion for coating with a solid content of 50wt%;

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

[0087] The final high solid content environmentally friendly fluorocarbon resin emulsion for coating has a viscosity of 50mPa·s, a hydroxyl value of 41mgKOH / g, a fluorine content of 19wt%, and an average particle size of 89nm; 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 50 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was placed at 25°C for 6 months, the emulsion did not show stratification. At the same time, 1 ml of the high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was centrifuged at a speed of 10000r / 30min for 30min in a centrifuge, and the emulsion did not show stratification. The high-solid content, environmentally friendly fluorocarbon resin emulsion for coating was tested for water resistance, 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 high solid content environmentally friendly fluorocarbon resin emulsion is more than 50wt%; Polyoxyethylene ether is a polyoxyethylene ether reactive macromonomer having double bonds and super-long EO chains, and the EO number is ≥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 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 a compound having a structure shown in Formula I; 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; 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; 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; Formula IV; In formula IV, R is selected from C1~C24 straight chain alkyl; n≥20.

4. The method for preparing a high solid content environmentally friendly fluorocarbon resin emulsion for coating by soap-free polymerization according to claim 3, 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.

5. The method for preparing a high solid content environmentally friendly fluorocarbon resin emulsion for coating by soap-free polymerization according to claim 4, characterized in that: Based on the total molar amount of fluorinated olefins, other vinyl ether monomers and polyoxyethylene ether, the content of fluorinated olefins is 40-60 mol%, and the content of polyoxyethylene ether is 0.1-5 mol%.

6. The method for preparing a high solid content environmentally friendly fluorocarbon resin emulsion for coating by soap-free polymerization according to claim 5, 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 30000-100000.

7. The method for preparing a high solid content environmentally friendly fluorocarbon resin emulsion for coating by soap-free polymerization according to any one of claims 1 to 6, characterized in that: The specific preparation steps are as follows: (1) Add other vinyl ether monomers, polyoxyethylene ether and water into the reactor at one time, evacuate the reactor and replace with nitrogen until the oxygen content in the reactor is less than 50 ppm; (2) Add fluorinated olefins to the reactor of step (1), raise the temperature to 40-70°C, and then start adding initiators to carry out polymerization reaction. The initiators are added continuously 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.

Images