Heat-resistant polymer microsphere as well as preparation method and application thereof

Abstract

The invention relates to a heat-resistant polymer microsphere as well as a preparation method and application thereof, and belongs to the technical field of polymer microspheres, and the preparation method comprises the following steps: adding a monomer and an initiator into a dispersant solution, fully stirring in an inert atmosphere, reacting at a first reaction temperature, continuously reacting at a second reaction temperature, and after the reaction is finished, centrifuging, washing and drying to obtain the heat-resistant polymer microsphere. The heat-resistant polymer microspheres are obtained; wherein the monomer is an organic compound containing a carbon-carbon double bond; the initiator is a free radical initiator; the dispersing agent is a water-soluble polymer; the first reaction temperature is lower than the second reaction temperature. Compared with the prior art, the size range of the microspheres prepared by the method covers 200nm-1mu m, the particle size is controllable, and the uniformity is good; the thermal stability is excellent, and the thermal decomposition temperature reaches up to 300 DEG C or above.

Description

Technical Field

[0001] The invention relates to the technical field of polymer microspheres, and in particular to heat-resistant polymer microspheres and a preparation method and application thereof. Background Art

[0002] Polymer microspheres refer to tiny particles made of polymer materials with diameters ranging from nanometers to millimeters. They have a large specific surface area and good drug loading capacity, and are therefore widely used in the fields of biomedicine, membrane coating materials, etc. Up to now, polymer microspheres are mainly prepared by emulsion polymerization, dispersion polymerization, precipitation polymerization, etc. Emulsion polymerization is usually suitable for preparing microspheres with a size of less than 200nm, while dispersion polymerization and precipitation polymerization are usually suitable for preparing microspheres with a size of more than 1μm. It is still a big challenge to prepare microspheres with a size between 200nm and 1μm by dispersion polymerization.

[0003] At present, many application scenarios have high requirements for the size distribution and thermal stability of polymer microspheres. For example, in the field of battery separator coating materials, the smaller particle size (below 500nm) and narrow particle size distribution of the microspheres are very important for their uniform coating on the surface of the separator. In addition, the operating conditions of the battery also place high demands on the thermal stability of the microspheres. The thermal decomposition temperature must be at least 180°C. Usually, the thermal stability can be enhanced by adding inorganic components, but the cost is relatively high at present. Summary of the invention

[0004] In order to overcome the defect that only microspheres larger than 1 μm can be obtained by dispersion polymerization, the present invention provides heat-resistant polymer microspheres and a preparation method and application thereof. The size of the microspheres obtained by the preparation method of the present invention is 200 nm-1 μm.

[0005] The present invention provides a strategy for preparing heat-resistant polymer microspheres with a size of 200nm-1μm by using a dispersion polymerization method, which expands the lower limit of the size of microspheres prepared by dispersion polymerization. The present invention can reduce the size of the prepared microspheres to 200nm-1μm by selecting a suitable dispersant and adjusting the polarity of the dispersion medium (such as selecting different combinations of alcohols and water, and adjusting the mass ratio of alcohol and water), and the particle size is controllable and uniform; by introducing a heat-resistant monomer and increasing the crosslinking degree inside the microspheres, the thermal stability of the polymer microspheres is effectively enhanced, and the thermal decomposition temperature can reach above 300°C. Specifically, in dispersion polymerization, by adjusting the alcohol-water ratio in the solvent, the particle size of the microspheres can be flexibly controlled: the alcohol-water ratio mainly affects the dissolution ability of the dispersion medium for the polymer, thereby affecting the time for the polymer to precipitate and nucleate, resulting in a change in the number of nucleation points, and then affecting the size of the prepared microspheres. Increasing the amount of dispersant will provide more nucleation sites and enhance the stability of the particles, so that the monomers are dispersed to grow on a large number of microspheres, while inhibiting coagulation, thereby generating smaller and evenly distributed microspheres. That is to say, the core of the present invention is to achieve particle size control through comprehensive regulation of nucleation density, stability and growth rate.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One of the purposes of the present invention is a method for preparing heat-resistant polymer microspheres, comprising:

[0008] The monomer and the initiator are added to the dispersant solution, stirred sufficiently in an inert atmosphere and reacted at a first reaction temperature, and then continued to react at a second reaction temperature. After the reaction is completed, centrifugation, washing, and drying are performed to obtain heat-resistant polymer microspheres;

[0009] Wherein, the monomer is an organic compound containing a carbon-carbon double bond;

[0010] The initiator is a free radical initiator;

[0011] The dispersant is a water-soluble polymer;

[0012] The first reaction temperature is lower than the second reaction temperature, so as to increase the reaction rate at the end and the monomer conversion rate;

[0013] Reacting in an inert atmosphere eliminates free radical quenching by oxygen.

[0014] Further, the monomer is selected from one or more of styrene, divinylbenzene, vinyl acetate, chloromethylstyrene, acrylamide, 2-methyl-5-vinylpyridine, sodium p-vinylbenzenesulfonate, N-vinylformamide, N-vinylpyrrolidone, aniline, acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dodecyl acrylate, glycidyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, allyl glycidyl ether, adipic dihydrazide, carbonate dihydrazide, oxalic acid dihydrazide, succinic acid dihydrazide, N-aminoacrylamide, methylenebisacrylamide, itaconic acid, maleic acid, maleic anhydride or fumaric acid.

[0015] Preferably, the monomer is selected from one or more of styrene, acrylonitrile, methyl methacrylate and divinylbenzene.

[0016] Furthermore, the initiator is selected from one or more of ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, benzoyl peroxide, azobisisobutyronitrile or cumene hydroperoxide.

[0017] Preferably, the initiator is potassium persulfate.

[0018] Furthermore, the dispersant is selected from one or more of polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG), hydroxypropyl cellulose (HPC), polyvinyl alcohol (PVA), and polyacrylic acid (PAA).

[0019] Preferably, the dispersant is PVA (200k).

[0020] Furthermore, the dispersant solution is obtained by dissolving a dispersant in a mixed solvent consisting of water and an alcohol solvent, and the mass ratio of the dispersant to the mixed solvent is 1:1000-10:1.

[0021] Furthermore, the alcohol solvent is selected from any one or more of methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, tert-butanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol and glycerol.

[0022] Preferably, the alcohol solvent is ethanol.

[0023] Furthermore, the mass ratio of water to alcohol solvent is 500:1-1:500.

[0024] Furthermore, the first reaction temperature is 60-80°C; the second reaction temperature is 70-90°C.

[0025] The second object of the present invention is to provide a heat-resistant polymer microsphere, which is prepared by the preparation method as described above. The size of the heat-resistant polymer microsphere is 200nm-1μm, and the thermal decomposition temperature of the microsphere is 300-420℃.

[0026] The third object of the present invention is to use the heat-resistant polymer microspheres as described above as a coating material in a lithium-ion battery separator.

[0027] Compared with the prior art, the present invention reduces the size of the prepared microspheres to 200nm-1μm by selecting a suitable dispersant and adjusting the polarity of the dispersion medium, such as selecting different combinations of alcohols and water and adjusting the mass ratio of alcohol and water. The particle size is controllable and the uniformity is good. By introducing heat-resistant monomers and increasing the cross-linking degree inside the microspheres, the thermal stability of the polymer microspheres is effectively enhanced, and the thermal decomposition temperature can reach above 300°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A This is a scanning electron microscope photo of the microspheres prepared in Example 1;

[0029] Figure 1B This is a scanning electron microscope photo of the microspheres prepared in Example 2;

[0030] Figure 1C This is a scanning electron microscope photo of the microspheres prepared in Example 3;

[0031] Figure 1D This is a scanning electron microscope photo of the microspheres prepared in Example 6;

[0032] Figure 2A This is a scanning electron microscope photo of the microspheres prepared in Example 7;

[0033] Figure 2B This is a scanning electron microscope photo of the microspheres prepared in Example 8;

[0034] Figure 2C This is a scanning electron microscope photo of the microspheres prepared in Comparative Example 1;

[0035] Figure 3A Thermogravimetric (TGA) curve of the microspheres prepared in Example 1;

[0036] Figure 3B Thermogravimetric (TGA) curve of the microspheres prepared in Example 5;

[0037] Figure 3C This is the thermogravimetric (TGA) curve of the microspheres prepared in Example 6. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0039] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. If no specific conditions are specified, the conventional conditions or the conditions recommended by the manufacturer shall be followed. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0040] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0041] Polymer microspheres refer to tiny particles made of polymer materials with diameters ranging from nanometers to millimeters. They have a large specific surface area and good drug loading capacity, and are therefore widely used in the fields of biomedicine, membrane coating materials, etc. Up to now, polymer microspheres are mainly prepared by emulsion polymerization, dispersion polymerization, precipitation polymerization, etc. Emulsion polymerization is usually suitable for preparing microspheres with a size below 200nm, while dispersion polymerization and precipitation polymerization are usually suitable for preparing microspheres above 1μm. It is still a big challenge to prepare microspheres with a size between 200nm and 1μm by dispersion polymerization.

[0042] In order to overcome the defect that only microspheres with a size of 1 μm or more can be obtained by dispersion polymerization, the present invention provides a method for preparing heat-resistant polymer microspheres with a size of 200 nm-1 μm by dispersion polymerization, comprising:

[0043] The monomer and the initiator are added to the dispersant solution, stirred sufficiently, reacted at a first reaction temperature in an inert atmosphere, and then continued to react at a second reaction temperature. After the reaction is completed, centrifuged, washed, and dried to obtain heat-resistant polymer microspheres;

[0044] Wherein, the monomer is an organic compound containing a carbon-carbon double bond;

[0045] The initiator is a free radical initiator;

[0046] The dispersant is a water-soluble polymer;

[0047] The first reaction temperature is lower than the second reaction temperature, so as to increase the reaction rate at the end and the monomer conversion rate;

[0048] Reacting in an inert atmosphere eliminates free radical quenching by oxygen.

[0049] In some embodiments of the present invention, the monomer is selected from styrene, divinylbenzene, vinyl acetate, chloromethylstyrene, acrylamide, 2-methyl-5-vinylpyridine, sodium p-vinylbenzenesulfonate, N-vinylformamide, N-vinylpyrrolidone, aniline, acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dodecyl acrylate, glycidyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, allyl glycidyl ether, adipic dihydrazide, carbonate dihydrazide, oxalic acid dihydrazide, succinic acid dihydrazide, N-aminoacrylamide, methylenebisacrylamide, itaconic acid, maleic acid, maleic anhydride or fumaric acid.

[0050] Preferably, the monomer is selected from one or more of styrene, acrylonitrile, methyl methacrylate and divinylbenzene.

[0051] In some embodiments of the present invention, the initiator is selected from one or more of ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, benzoyl peroxide, azobisisobutyronitrile or cumene hydroperoxide.

[0052] Preferably, the initiator is potassium persulfate.

[0053] In some embodiments of the present invention, the dispersant is selected from one or more of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), hydroxypropylcellulose (HPC), polyvinyl alcohol (PVA), and polyacrylic acid (PAA).

[0054] Preferably, the dispersant is PVA (200k).

[0055] In some embodiments of the present invention, the dispersant solution is obtained by dissolving a dispersant in a mixed solvent consisting of water and an alcohol solvent, and the mass ratio of the dispersant to the mixed solvent is 1:1000-10:1.

[0056] In some embodiments of the present invention, the alcohol solvent is selected from any one or more of methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, tert-butanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol and glycerol.

[0057] Preferably, the alcohol solvent is ethanol.

[0058] In some embodiments of the present invention, the mass ratio of water to alcohol solvent is 500:1-1:500.

[0059] In some embodiments of the present invention, the first reaction temperature is 60-80°C; the second reaction temperature is 70-90°C.

[0060] Example 1

[0061] This embodiment provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0062]

[0063]

[0064] 1. Dispersant dissolution: PVA (200k), ethanol and water were weighed according to the above table, and mechanically stirred for 2 hours to fully dissolve the PVA; styrene and acrylonitrile were weighed according to the above table and mixed evenly to obtain a mixed monomer; initiator was weighed according to the above table.

[0065] 2. Feeding: Add the dissolved PVA alcohol-water mixture into the reactor (250 mL), start stirring at a rate of 170 rpm. After nitrogen is introduced for 0.5 h, add the mixed monomer and initiator, continue to introduce nitrogen for 0.5 h, and then mechanically stir for 0.5 h.

[0066] 3. Polymerization reaction: Raise the temperature to 70°C to initiate the polymerization reaction and continue mechanical stirring for 12 hours.

[0067] 4. Heating: 12 hours after the start of polymerization, raise the temperature to 80°C.

[0068] 5. Discharging: 16 hours after the start of polymerization, stop heating and cool naturally to room temperature. Discharging, centrifuging with ethanol, washing and drying, nano-scale heat-resistant polymer microspheres are obtained. The average size of the microspheres is about 300nm. Figure 1A The microspheres have excellent thermal stability, such as Figure 3AAs shown, the thermal decomposition temperature is 373°C (using a PE thermogravimetric analyzer, nitrogen atmosphere, flow rate 40 mL / min, from 50°C to 800°C, heating rate 10°C / min, the temperature at which the weight loss is 3% in the curve is taken as the thermal decomposition temperature T 3 ). This indicates that the introduction of ethanol into the solvent is helpful in preparing uniform polymer microspheres.

[0069] Example 2

[0070] This embodiment provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0071]

[0072]

[0073] 1. Dispersant dissolution: PVA (200k), ethanol and water were weighed according to the above table, and mechanically stirred for 2 hours to fully dissolve the PVA; styrene and acrylonitrile were weighed according to the above table and mixed evenly to obtain a mixed monomer; initiator was weighed according to the above table.

[0074] 2. Feeding: Add the dissolved PVA alcohol-water mixture into the reactor (250 mL), start stirring at a rate of 170 rpm. After nitrogen is introduced for 0.5 h, add the mixed monomer and initiator, continue to introduce nitrogen for 0.5 h, and then mechanically stir for 0.5 h.

[0075] 3. Polymerization reaction: Raise the temperature to 70°C to initiate the polymerization reaction and continue mechanical stirring for 12 hours.

[0076] 4. Heating: 12 hours after the start of polymerization, raise the temperature to 80°C.

[0077] 5. Discharging: 16 hours after the start of polymerization, stop heating and cool naturally to room temperature. Discharging, centrifuging with ethanol, washing and drying, nano-scale heat-resistant polymer microspheres are obtained. The average size of the microspheres is about 250nm. Figure 1B .

[0078] Example 3

[0079] This embodiment provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0080]

[0081]

[0082] 1. Dispersant dissolution: PVA (200k), ethanol and water were weighed according to the above table, and mechanically stirred for 2 hours to fully dissolve the PVA; styrene and acrylonitrile were weighed according to the above table and mixed evenly to obtain a mixed monomer; initiator was weighed according to the above table.

[0083] 2. Feeding: Add the dissolved PVA alcohol-water mixture into the reactor (250 mL), start stirring at a rate of 170 rpm. After nitrogen is introduced for 0.5 h, add the mixed monomer and initiator, continue to introduce nitrogen for 0.5 h, and then mechanically stir for 0.5 h.

[0084] 3. Polymerization reaction: Raise the temperature to 70°C to initiate the polymerization reaction and continue mechanical stirring for 12 hours.

[0085] 4. Heating: 12 hours after the start of polymerization, raise the temperature to 80°C.

[0086] 5. Discharging: 16 hours after the start of polymerization, stop heating and cool naturally to room temperature. Discharging, centrifuging with ethanol, washing and drying, nano-scale heat-resistant polymer microspheres are obtained. The average size of the microspheres is about 150nm. Figure 1C It is not difficult to see from Examples 1, 2, and 3 that as the proportion of ethanol in the solvent decreases, the size of the polymer microspheres gradually decreases, and the uniformity improves.

[0087] Example 4

[0088] This embodiment provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0089]

[0090]

[0091] 1. Dispersant dissolution: PVA (200k), ethanol and water were weighed according to the above table, and mechanically stirred for 2 hours to fully dissolve the PVA; styrene, acrylonitrile and methyl methacrylate were weighed according to the above table and mixed evenly to obtain a mixed monomer; the initiator was weighed according to the above table.

[0092] 2. Feeding: Add the dissolved PVA alcohol-water mixture into the reactor (250 mL), start stirring at a rate of 170 rpm. After nitrogen is introduced for 0.5 h, add the mixed monomer and initiator, continue to introduce nitrogen for 0.5 h, and then mechanically stir for 0.5 h.

[0093] 3. Polymerization reaction: Raise the temperature to 70°C to initiate the polymerization reaction and continue mechanical stirring for 12 hours.

[0094] 4. Heating: 12 hours after the start of polymerization, raise the temperature to 80°C.

[0095] 5. Discharging: 16 hours after the start of polymerization, stop heating and cool naturally to room temperature. Discharging, centrifuging with ethanol, washing and drying to obtain nano-scale heat-resistant polymer microspheres, the average size of which is about 420nm.

[0096] Example 5

[0097] This embodiment provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0098]

[0099]

[0100] 1. Dispersant dissolution: PVA (200k), ethanol and water were weighed according to the above table, and mechanically stirred for 2 hours to fully dissolve the PVA; styrene, acrylonitrile and divinylbenzene were weighed according to the above table and mixed evenly to obtain a mixed monomer; initiator was weighed according to the above table.

[0101] 2. Feeding: Add the dissolved PVA alcohol-water mixture into the reactor (250 mL), start stirring at a rate of 170 rpm. After nitrogen is introduced for 0.5 h, add the mixed monomer and initiator, continue to introduce nitrogen for 0.5 h, and then mechanically stir for 0.5 h.

[0102] 3. Polymerization reaction: Raise the temperature to 70°C to initiate the polymerization reaction and continue mechanical stirring for 12 hours.

[0103] 4. Heating: 12 hours after the start of polymerization, raise the temperature to 80°C.

[0104] 5. Discharging: 16 hours after the start of polymerization, stop heating and cool naturally to room temperature. Discharging, centrifuging with ethanol, washing and drying, nano-scale heat-resistant polymer microspheres are obtained. The average size of the microspheres is about 330nm. After the introduction of cross-linking monomer divinylbenzene, the degree of cross-linking inside the microspheres can be further increased, thereby enhancing their thermal stability. Figure 3B As shown, the thermal decomposition temperature of the microspheres was further increased to 385°C (using a PE thermogravimetric analyzer, nitrogen atmosphere, flow rate 40 mL / min, from 50°C to 800°C, heating rate 10°C / min, taking the temperature of 3% weight loss in the curve as the thermal decomposition temperature T 3 ).

[0105] Example 6

[0106] This embodiment provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0107]

[0108]

[0109] This example is based on Example 1, which is enlarged to 100 times the scale. The preparation method is the same as that of Example 1, and the average size of the obtained microspheres is about 300nm. Figure 1D , thermal decomposition temperature 378 ° C (using PE thermogravimetric analyzer, nitrogen atmosphere, flow rate 40mL / min, from 50 ° C to 800 ° C, heating rate 10 ° C / min, take the temperature of 3% weight loss in the curve as the thermal decomposition temperature T 3 ),See Figure 3C This indicates that the amplification effect of this reaction is small, which is conducive to subsequent amplification production.

[0110] Example 7

[0111] This embodiment provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0112]

[0113] The preparation process of this embodiment is basically the same as that of embodiment 1, except that the amount of dispersant used in this embodiment is less, 0.1 g. It can be seen that after reducing the amount of dispersant, the size of the microspheres increases significantly from 300 nm to 350 nm. Figure 2A .

[0114] Example 8

[0115] This embodiment provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0116]

[0117] 1. Dispersant dissolution: PVA (200k), ethanol and water were weighed according to the above table, and mechanically stirred for 2 hours to fully dissolve the PVA; styrene and methyl methacrylate were weighed according to the above table and mixed evenly to obtain a mixed monomer; the initiator was weighed according to the above table.

[0118] 2. Feeding: Add the dissolved PVA alcohol-water mixture into the reactor (250 mL), start stirring at a rate of 170 rpm. After nitrogen is introduced for 0.5 h, add the mixed monomer and initiator, continue to introduce nitrogen for 0.5 h, and then mechanically stir for 0.5 h.

[0119] 3. Polymerization reaction: Raise the temperature to 70°C to initiate the polymerization reaction and continue mechanical stirring for 12 hours.

[0120] 4. Heating: 12 hours after the start of polymerization, raise the temperature to 80°C.

[0121] 5. Discharging: 16 hours after the start of polymerization, stop heating and cool naturally to room temperature. Discharging, centrifuging with ethanol, washing and drying, nano-scale heat-resistant polymer microspheres are obtained. The average size of the microspheres is about 640nm. Figure 2B Compared with Example 7, the size of the microspheres was further increased after the second monomer was replaced by methyl methacrylate from acrylonitrile.

[0122] Comparative Example 1

[0123] This comparative example provides a method for preparing heat-resistant polymer microspheres. The raw materials and their proportions are shown in the following table:

[0124]

[0125] 1. Dispersant dissolution: PVA (200k) and water were weighed according to the above table, and mechanically stirred for 2 hours to fully dissolve the PVA; styrene and acrylonitrile were weighed according to the above table and mixed evenly to obtain a mixed monomer; initiator was weighed according to the above table.

[0126] 2. Feeding: Add the dissolved PVA alcohol-water mixture into the reactor (250 mL), start stirring at a rate of 170 rpm. After nitrogen is introduced for 0.5 h, add the mixed monomer and initiator, continue to introduce nitrogen for 0.5 h, and then mechanically stir for 0.5 h.

[0127] 3. Polymerization reaction: Raise the temperature to 70°C to initiate the polymerization reaction and continue mechanical stirring for 12 hours.

[0128] 4. Heating: 12 hours after the start of polymerization, raise the temperature to 80°C.

[0129] 5. Discharging: 16 hours after the start of polymerization, stop heating and cool naturally to room temperature. Discharging, centrifuging with ethanol, washing and drying, nano-scale heat-resistant polymer microspheres are obtained. The size uniformity of the microspheres is poor, with a wide distribution in the range of 50nm-2μm. Figure 2C This indicates that uniform polymer microspheres cannot be prepared without the presence of ethanol in the solvent.

[0130] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing heat-resistant polymer microspheres, characterized in that: include: The monomer and the initiator are added to the dispersant solution, stirred sufficiently in an inert atmosphere and reacted at a first reaction temperature, and then continued to react at a second reaction temperature. After the reaction is completed, centrifugation, washing, and drying are performed to obtain heat-resistant polymer microspheres; Wherein, the monomer is an organic compound containing a carbon-carbon double bond; The initiator is a free radical initiator; The dispersant is a water-soluble polymer; The first reaction temperature is lower than the second reaction temperature.

2. The method for preparing heat-resistant polymer microspheres according to claim 1, characterized in that: The monomer is selected from one or more of styrene, divinylbenzene, vinyl acetate, chloromethylstyrene, acrylamide, 2-methyl-5-vinylpyridine, sodium p-vinylbenzenesulfonate, N-vinylformamide, N-vinylpyrrolidone, aniline, acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dodecyl acrylate, glycidyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, allyl glycidyl ether, adipic dihydrazide, carbonate dihydrazide, oxalic acid dihydrazide, succinic acid dihydrazide, N-aminoacrylamide, methylenebisacrylamide, itaconic acid, maleic acid, maleic anhydride or fumaric acid.

3. The method for preparing heat-resistant polymer microspheres according to claim 1, characterized in that: The initiator is selected from one or more of ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, benzoyl peroxide, azobisisobutyronitrile or cumene hydroperoxide.

4. The method for preparing heat-resistant polymer microspheres according to claim 1, characterized in that: The dispersant is selected from one or more of polyvinyl pyrrolidone, polyethylene glycol, hydroxypropyl cellulose, polyvinyl alcohol, and polyacrylic acid.

5. The method for preparing heat-resistant polymer microspheres according to claim 1, characterized in that: The dispersant solution is obtained by dissolving a dispersant in a mixed solvent consisting of water and an alcohol solvent, and the mass ratio of the dispersant to the mixed solvent is 1:1000-10:

1.

6. The method for preparing heat-resistant polymer microspheres according to claim 5, characterized in that: The alcohol solvent is selected from any one or more of methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, tert-butanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol and glycerol.

7. The method for preparing heat-resistant polymer microspheres according to claim 5, characterized in that: The mass ratio of the water to the alcohol solvent is 500:1-1:

500.

8. The method for preparing heat-resistant polymer microspheres according to claim 1, characterized in that: The first reaction temperature is 60-80°C; the second reaction temperature is 70-90°C.

9. A heat-resistant polymer microsphere, characterized in that: It is prepared by the preparation method as claimed in claims 1-8, the size of the heat-resistant polymer microspheres is 200nm-1μm, and the thermal decomposition temperature of the microspheres is 300-420°C.

10. Use of the heat-resistant polymer microspheres as claimed in claim 9 as a coating material in a lithium-ion battery separator.

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