Environment-friendly thermosetting powder coating and preparation method thereof

Abstract

The invention discloses an environment-friendly thermosetting powder coating and a preparation method thereof. The preparation method comprises the following steps: mixing epoxy resin with a solvent formed by mixing n-butyl alcohol and ethylene glycol monobutyl ether to prepare a dispersion liquid 1; the preparation method comprises the following steps: reacting nano zirconium oxide particles and a surfactant with tetraethoxysilane to prepare ZrO2 / SiO2 particles; the ZrO2 / SiO2 particles and a modifier are subjected to a reaction, and surface modified ZrO2 / SiO2 particles are obtained; adding the surface-modified ZrO2 / SiO2 particles into a polymeric monomer, then adding an initiator, and uniformly stirring to obtain a dispersion system 2; carrying out condensation polymerization on the dispersion system 1 and the dispersion system 2 to prepare epoxy acrylic copolymer powder containing surface modified ZrO2 / SiO2 particles; the preparation method comprises the following steps: uniformly mixing the epoxy acrylic copolymer powder containing the surface-modified ZrO2 / SiO2 particles with a pigment, an accelerant, a flame retardant, an auxiliary agent and a filler, feeding the mixture into an extruder, carrying out melt extrusion, crushing and sieving. The preparation method of the environment-friendly thermosetting powder coating has the advantages of being simple in process, mild in condition, energy-saving, environment-friendly and the like.

Description

Technical Field

[0001] The invention belongs to the field of thermosetting powder coatings, and in particular relates to an environmentally friendly thermosetting powder coating and a preparation method thereof. Background Art

[0002] Powder coating is a kind of coating that does not contain organic solvents and exists in the form of fine powder. It is not only popular in the market with its excellent performance, basically no pollution to the environment, simple use method and low price, but also gradually becomes one of the new directions of the development of the green coating industry (Shi Ligong. Can powder coating emerge as a new force in the future environmentally friendly coating market [J]. Coatings Industry, 2018, 48(5):80-87.). Powder coatings can be divided into two categories according to the characteristics of their film-forming substances: thermosetting and thermoplastic powder coatings; among them, thermoplastic powder coatings have significant disadvantages such as poor crushing performance of its resin, large molecular weight and high softening point, which limits its application range. In contrast, thermosetting powder coatings currently occupy a dominant position in the market (He Mingjun, Hu Xiaoyong, Ke Yong, et al. Research progress of thermosetting powder coatings [J]. Synthetic Resins and Plastics, 2016, 33(4):93-97.). Specifically, thermosetting powder coating is a high-performance coating that not only inherits the high efficiency and environmental protection characteristics of traditional powder coatings, but also provides excellent properties such as heat resistance, corrosion resistance and high temperature resistance, making it an ideal choice for high-temperature equipment. However, the high-temperature resistance of traditional powder coatings commonly used on the market is usually not ideal. Excessive temperatures during construction may affect the performance of certain workpieces or even damage them. In addition, compared with liquid coatings, powder coatings are still limited in the diversity of colors and appearance effects. Therefore, it is very necessary to develop environmentally friendly thermosetting powder coatings with better performance. Summary of the invention

[0003] The object of the present invention is to provide an environmentally friendly thermosetting powder coating and a preparation method thereof.

[0004] In order to achieve the above object, the solution of the present invention is:

[0005] A method for preparing an environmentally friendly thermosetting powder coating, characterized in that it comprises the following steps:

[0006] (1) mixing an epoxy resin with a solvent prepared by mixing n-butanol and ethylene glycol monobutyl ether, and then preparing a dispersion 1 by stirring and heating;

[0007] (2) adding nano zirconium oxide particles and a surfactant to ethanol and stirring evenly, adding an ammonia solution to adjust the pH value of the system, then adding ethyl orthosilicate, subjecting the obtained mixture to a microwave reaction, filtering and washing the obtained solid to prepare ZrO2 / SiO2 particles;

[0008] (3) adding the ZrO2 / SiO2 particles prepared in step (2) and the modifier into toluene for reflux reaction, and after the reaction is completed, washing the obtained solid with toluene to prepare surface-modified ZrO2 / SiO2 particles;

[0009] (4) adding the surface-modified ZrO2 / SiO2 particles obtained in step (3) to the polymerization monomer, and then adding an initiator and stirring evenly to obtain a dispersion 2;

[0010] (5) continuing to heat the dispersion 1 prepared in step (1) to a higher temperature, and then slowly dropping the dispersion 2 prepared in step (4), and continuing to maintain a constant temperature reaction until the polycondensation reaction is completed; after the system cools to room temperature, extracting the reaction product with toluene, and distilling the extract to remove the solvent to obtain an epoxy acrylic copolymer powder containing surface-modified ZrO2 / SiO2 particles;

[0011] (6) The epoxy acrylic copolymer powder containing surface-modified ZrO2 / SiO2 particles obtained in step (5) is mixed evenly with a pigment, a accelerator, a flame retardant, an additive and a filler, and then fed into an extruder for melt extrusion. After extrusion cooling, the mixture is crushed and sieved to obtain the environmentally friendly thermosetting powder coating.

[0012] Preferably, the heating temperature in step (1) is 80-100°C.

[0013] Preferably, the particle size of the nano zirconium oxide particles in step (2) is in the range of 100-200 nm.

[0014] Preferably, the surfactant described in step (2) is selected from one of fatty alcohol polyoxyethylene ether, Tween 80 or dodecyltrimethylammonium chloride.

[0015] Preferably, the modifier described in step (3) is one of methacryloxypropyltrimethoxysilane, isopropyl tri(dioctylpyrophosphate) titanate, stearic acid, lauric acid or oleic acid.

[0016] Preferably, the polymerizable monomer in step (4) is one of acrylic acid, methacrylic acid, hydroxypropyl acrylate, methyl methacrylate or butyl acrylate.

[0017] Preferably, the initiator in step (4) is one of benzoyl peroxide, benzophenone peroxide or tert-butyl hydroperoxide.

[0018] Preferably, the isothermal reaction temperature in step (5) is between 90 and 120°C.

[0019] The environmentally friendly thermosetting powder coating prepared by the above-mentioned preparation method of environmentally friendly thermosetting powder coating is characterized in that the mass ratio of the surface modified ZrO2 / SiO2 particles is 1.0-2.5%.

[0020] The aforementioned environmentally friendly thermosetting powder coating is used in the corrosion protection of metal materials.

[0021] The specific principle of the preparation method of the environmentally friendly thermosetting powder coating provided by the present invention is as follows:

[0022] The preparation method of the environmentally friendly thermosetting powder coating provided by the present invention is to prepare ZrO2 / SiO2 composite particles by a sol-gel method under alkaline conditions with nano zirconium oxide particles, surfactants and tetraethyl orthosilicate, and then use methacryloxypropyl trimethoxysilane or isopropyl tri(dioctyl pyrophosphate acyloxy) titanate to modify the ZrO2 / SiO2 composite particles to obtain surface-modified ZrO2 / SiO2 particles. Next, the surface-modified ZrO2 / SiO2 particles are dispersed in polymerizable monomers and undergo graft copolymerization with epoxy resin to obtain epoxy acrylic copolymer powder containing surface-modified ZrO2 / SiO2 particles. Finally, the epoxy acrylic copolymer powder containing surface-modified ZrO2 / SiO2 particles is mixed evenly with pigment, accelerator, flame retardant, auxiliary agent and filler, and then sent into an extruder for melt extrusion, and the mixture is crushed and sieved after extrusion cooling to obtain the environmentally friendly thermosetting powder coating. Among them, the addition of surface-modified ZrO2 / SiO2 particles can improve the mechanical properties and high temperature resistance of the prepared powder coating; while the use of epoxy acrylic graft copolymer effectively improves the acid resistance and alkali resistance of the prepared powder coating.

[0023] Compared with the existing thermosetting powder coating and preparation method thereof, the gain effects of the present invention are as follows:

[0024] 1. The environmentally friendly thermosetting powder coating provided by the present invention has no solvent addition and extremely low VOC (volatile organic compound) emissions. It is an environmentally friendly coating with the advantages of being green and environmentally friendly.

[0025] 2. The preparation method of the environmentally friendly thermosetting powder coating provided by the present invention also has the advantages of simple process, mild conditions, good repeatability and being conducive to industrial promotion, etc. It provides a new method for preparing environmentally friendly thermosetting powder coatings and opens up new ideas.

[0026] 3. The coating made of the environmentally friendly thermosetting powder coating provided by the present invention on the metal surface not only has high mechanical properties, but also has good high temperature resistance, acid resistance and alkali resistance. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the embodiments. It should also be understood that the following embodiments are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. The specific quality, reaction time and temperature, process parameters, etc. in the examples are only examples within the appropriate ranges. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present invention all belong to the scope of protection of the present invention.

[0028] Unless otherwise specified, all reagents used in the examples of the present invention are commercial reagents and were not further purified before use.

[0029] Embodiment 1:

[0030] The preparation steps of environmentally friendly thermosetting powder coating are as follows:

[0031] (1) Under nitrogen protection, 10 g of epoxy resin E-12 was dissolved in a mixed solvent consisting of 10 mL of ethylene glycol monobutyl ether and 25 mL of n-butanol and stirred and heated to 90° C. to prepare dispersion 1;

[0032] (2) Add 5 g of nano zirconium oxide particles (particle size 100-200 nm) and 0.1 g of fatty alcohol polyoxyethylene ether to 750 ml of ethanol, stir evenly, add 5% mass concentration of aqueous ammonia solution to adjust the pH value of the system to 10, then add 5.25 g of tetraethyl orthosilicate, place the resulting mixture in a microwave reaction tank for microwave reaction at a microwave power of 350 W and a temperature of 80°C for 1.5 h. After filtering, wash the resulting solid three times with 75 ml of anhydrous ethanol and 75 ml of deionized water, and dry the resulting solid at 110°C for 2.5 h to prepare ZrO2 / SiO2 particles.

[0033] (3) adding the ZrO2 / SiO2 particles prepared in step (2) and the modifier to toluene for reflux reaction, and washing the obtained solid with toluene after the reaction to prepare surface-modified ZrO2 / SiO2 particles; adding 1.5 g of the ZrO2 / SiO2 particles prepared in step (1) and 2.5 g of methacryloxypropyltrimethoxysilane to 750 ml of toluene for reflux reaction for 6.5 hours, and washing the obtained solid with 75 ml of toluene three times after the reaction, and drying to prepare methacryloxypropyltrimethoxysilane-modified ZrO2 / SiO2 particles, and the obtained particles are recorded as SC-ZrO2 / SiO2 particles;

[0034] (4) Under nitrogen protection, 1.5 g of the SC-ZrO2 / SiO2 particles prepared in step (3) were added to 10 g of acrylic acid monomer, and then 1 g of benzoyl peroxide was added and stirred to obtain dispersion 2;

[0035] (5) Under nitrogen protection, the dispersion system 1 prepared in step (1) is further heated to 115° C., and then the dispersion system 2 prepared in step (4) is slowly added dropwise. After the addition is completed, the temperature is maintained at 115° C. for about 4 hours until the polycondensation reaction is completed; after the system cools to room temperature, the reaction product is extracted three times with 150 mL of toluene, and the extracts are combined and the solvent is removed by reduced pressure distillation to obtain an epoxy acrylic copolymer powder containing SC-ZrO2 / SiO2 particles;

[0036] (6) 8 g of the epoxy acrylic copolymer powder containing SC-ZrO2 / SiO2 particles obtained in step (5) was mixed evenly with 0.2 g of titanium dioxide, 0.05 g of 2-methylimidazole, 0.25 g of tricresyl phosphate, 0.2 g of hydroxyalkylamide and 1.3 g of a mixed filler composed of wollastonite and zinc stearate in a mass ratio of 1:1, and then sent into a micro extruder for melt extrusion. The temperature of the extruder was set to: 90-95°C in zone I, 95-100°C in zone II, 100-105°C in zone III, and 100-105°C in zone IV; the speed was set to: 950-1000 r / min. After extrusion and cooling, the obtained solid was crushed and sieved again with 200 mesh to obtain the environmentally friendly thermosetting powder coating. The obtained powder coating was recorded as SC-ZrO2 / SiO2-nHA-E-12-1.

[0037] The prepared environmentally friendly thermosetting powder coating is loaded into an electrostatic spray gun and evenly sprayed on the surface of the metal sheet substrate. After spraying, the metal sheet is quickly placed in an oven for heating and curing. After the fully cured metal sheet is taken out, it is placed in a ventilated and dry place indoors and naturally cooled to room temperature before various performance tests can be performed. Among them, the metal sheet used is a tinplate sheet, and the preparation steps are: the tinplate sheet is cut into a test plate with a size of 50mm×120mm×0.3mm, and the test plate is cleaned according to the provisions of the test plate in GB9271-1988.

[0038] The impact resistance, adhesion, high temperature resistance, water resistance and acid and alkali corrosion resistance of SC-ZrO2 / SiO2-nHA-E-12-1 coating were measured according to the corresponding standards, as follows: the impact resistance was measured according to the national standard GB / T1732-1993 "Determination of impact resistance of paint film", the adhesion (cross-cut method) was measured according to ISO2409-2007 "cross-cut test for paints and varnishes", the boiling water resistance test was measured according to GB / T1733-1993 "Determination of water resistance of paint films", the acid and alkali resistance test was measured according to GB / T 9274-1988 "Determination of liquid medium resistance of paints and varnishes", and the high temperature resistance test was measured by placing the metal substrate sprayed with powder coating into a muffle furnace and baking at different temperatures and observing the appearance changes. The results are shown in Table 1.

[0039] Embodiment 2:

[0040] The preparation of the environmentally friendly thermosetting powder coating refers to Example 1, except that the methacryloxypropyltrimethoxysilane in step (3) is replaced with isopropyl tri(dioctylpyrophosphate) titanate, and the remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as iDTC-ZrO2 / SiO2-nHA-E-12-2.

[0041] The preparation and performance characterization of the iDTC-ZrO2 / SiO2-nHA-E-12-2 coating are the same as those in Example 1; the results are shown in Table 1.

[0042] Embodiment 3:

[0043] The preparation of the environmentally friendly thermosetting powder coating refers to Example 1, except that the methacryloxypropyltrimethoxysilane in step (3) is replaced with stearic acid. The remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as SA-ZrO2 / SiO2-nHA-E-12-3.

[0044] The preparation and performance characterization of SA-ZrO2 / SiO2-nHA-E-12-3 coating are the same as those in Example 1; the results are shown in Table 1.

[0045] Embodiment 4:

[0046] The preparation of the environmentally friendly thermosetting powder coating is referred to Example 1, except that the acrylic acid monomer in step (4) is replaced with methacrylic acid. The remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as SC-ZrO2 / SiO2-nMHA-E-12-4.

[0047] The preparation and performance characterization of the SC-ZrO2 / SiO2-nMHA-E-12-4 coating are the same as those in Example 1; the results are shown in Table 1.

[0048] Embodiment 5:

[0049] The preparation of the environmentally friendly thermosetting powder coating is referred to Example 1, except that the acrylic monomer in step (4) is replaced with hydroxypropyl acrylate. The remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as SC-ZrO2 / SiO2-HPA-E-12-5.

[0050] The preparation and performance characterization of the SC-ZrO2 / SiO2-HPA-E-12-5 coating are the same as those in Example 1; the results are shown in Table 1.

[0051] Embodiment 6:

[0052] The preparation of the environmentally friendly thermosetting powder coating is referred to Example 1, except that the acrylic monomer in step (4) is replaced with methyl methacrylate. The remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as SC-ZrO2 / SiO2-MMA-E-12-6.

[0053] The preparation and performance characterization of the SC-ZrO2 / SiO2-MMA-E-12-6 coating are the same as those in Example 1; the results are shown in Table 1.

[0054] Embodiment 7:

[0055] The preparation of the environmentally friendly thermosetting powder coating is referred to Example 1, except that the acrylic monomer in step (4) is replaced with butyl acrylate. The remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as SC-ZrO2 / SiO2-BA-E-12-7.

[0056] The preparation and performance characterization of the SC-ZrO2 / SiO2-BA-E-12-7 coating are the same as those in Example 1; the results are shown in Table 1.

[0057] Embodiment 8:

[0058] The preparation of the environmentally friendly thermosetting powder coating refers to Example 1, except that the mass ratio of filler wollastonite to zinc stearate in step (6) is changed from 1:1 to 1:2. The remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as SC-ZrO2 / SiO2-nHA-E-12-8.

[0059] The preparation and performance characterization of the SC-ZrO2 / SiO2-nHA-E-12-8 coating are the same as those in Example 1; the results are shown in Table 1.

[0060] Embodiment 9:

[0061] The preparation of the environmentally friendly thermosetting powder coating refers to Example 1, except that the mass ratio of filler wollastonite to zinc stearate in step (6) is changed from 1:1 to 3:2. The remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as SC-ZrO2 / SiO2-nHA-E-12-9.

[0062] The preparation and performance characterization of the SC-ZrO2 / SiO2-nHA-E-12-9 coating are the same as those in Example 1; the results are shown in Table 1.

[0063] Embodiment 10:

[0064] The preparation of the environmentally friendly thermosetting powder coating refers to Example 1, except that the mass ratio of filler wollastonite to zinc stearate in step (6) is changed from 1:1 to 2:1, and the remaining steps are the same as Example 1. The obtained environmentally friendly thermosetting powder coating is recorded as SC-ZrO2 / SiO2-nHA-E-12-10.

[0065] The preparation and performance characterization of the SC-ZrO2 / SiO2-nHA-E-12-10 coating are the same as those in Example 1; the results are shown in Table 1.

[0066] Embodiment 11:

[0067] The preparation of the environmentally friendly thermosetting powder coating is based on Example 1, except that the methacryloxypropyltrimethoxysilane in step (3) is replaced with isopropyl tri(dioctylpyrophosphate) titanate, the acrylic monomer in step (4) is replaced with methyl methacrylate, and the mass ratio of filler wollastonite to zinc stearate in step (6) is changed from 1:1 to 3:2. The remaining steps are the same as in Example 1, and the obtained environmentally friendly thermosetting powder coating is recorded as iDTC-ZrO2 / SiO2-MMA-E-12-11.

[0068] The preparation and performance characterization of the iDTC-ZrO2 / SiO2-MMA-E-12-11 coating are the same as those in Example 1; the results are shown in Table 1.

[0069] Table 1 Performance characteristics of environmentally friendly thermosetting powder coatings

[0070] Impact resistance Adhesion Boiling resistance High temperature resistance Acid resistance Alkali resistance Example 1 No cracks Level 1 8h 80℃ 144h 144h Example 2 No cracks Level 0 8h 80℃ 144h 144h Example 3 No cracks Level 2 8h 80℃ 144h 144h Example 4 No cracks Level 1 8h 80℃ 144h 144h Example 5 No cracks Level 1 10h 80℃ 168h 168h Example 6 No cracks Level 1 12h 100℃ 192h 192h Example 7 No cracks Level 2 12h 100℃ 168h 168h Example 8 No cracks Level 2 12h 110℃ 192h 192h Example 9 No cracks Level 1 12h 110℃ 216h 216h Example 10 No cracks Level 2 12h 110℃ 192h 192h Embodiment 11 No cracks Level 0 14h 120℃ 240h 240h Comparative Example 1 There are cracks Level 4 2h 60℃ 48h 48h Comparative Example 2 There are cracks Level 3 4h 60℃ 48h 48h

[0071] Note: The impact strength selected for the impact resistance test is 50kg·cm. The time for water boiling resistance, high temperature resistance, acid resistance and alkali resistance refers to the time when the coating has no blistering, no falling off and no discoloration under the test conditions.

[0072] It can be seen from Table 1 that the impact resistance and adhesion of the prepared environmentally friendly thermosetting powder coating can be greatly improved by adding surface-modified ZrO2 / SiO2 particulate materials, while the acid resistance and alkali resistance of the prepared powder coating can be effectively improved by using acrylic acid and its derivatives to graft copolymerize with epoxy resin to form a copolymer; in addition, the mass ratio of filler wollastonite to zinc stearate in the prepared powder coating also affects the coating performance.

[0073] Comparative Example 1:

[0074] The preparation steps of environmentally friendly thermosetting powder coating are as follows:

[0075] (1) Add 2.5 g of nano zirconium oxide particles (particle size 100-200 nm) and 0.05 g of fatty alcohol polyoxyethylene ether to 500 ml of ethanol, stir evenly, add 5% aqueous ammonia solution to adjust the pH value of the system to 10, then add 2.6 g of ethyl orthosilicate, heat the mixture at 100°C for 12 h, filter, wash the solid three times with 50 ml of anhydrous ethanol and 50 ml of deionized water, and dry the solid at 110°C for 2.5 h to prepare ZrO2 / SiO2 particles.

[0076] (2) 0.3 g of the ZrO2 / SiO2 particles prepared in step (1), 8.7 g of epoxy resin E-12, 0.2 g of titanium dioxide, 0.05 g of 2-methylimidazole, 0.25 g of tricresyl phosphate, 0.2 g of hydroxyalkylamide and 0.3 g of a mixed filler consisting of wollastonite and zinc stearate in a mass ratio of 1:1 were mixed uniformly and sent into a micro extruder for melt extrusion. The temperature of the extruder was set to: 90-95°C in zone I, 95-100°C in zone II, 100-105°C in zone III, and 100-105°C in zone IV; the speed was set to: 950-1000 r / min. After extrusion and cooling, the obtained solid was crushed again and sieved through 200 mesh to obtain the environmentally friendly thermosetting powder coating. The obtained powder coating was recorded as ZrO2 / SiO2-E-12-12.

[0077] The preparation and performance characterization of the ZrO2 / SiO2-E-12-12 coating are the same as those in Example 1; the results are shown in Table 1.

[0078] Comparative Example 2:

[0079] The preparation steps of environmentally friendly thermosetting powder coating are as follows:

[0080] (1) The preparation of ZrO2 / SiO2 particles is the same as step (2) in the example;

[0081] (2) Preparation of SC-ZrO2 / SiO2 particles is the same as step (3) in the example;

[0082] (3) Preparation of Powder Coating Referring to step (2) in Comparative Example 1, the obtained powder coating was recorded as SC-ZrO2 / SiO2-E-12-13.

[0083] The preparation and performance characterization of the SC-ZrO2 / SiO2-E-12-13 coating are the same as those in Example 1; the results are shown in Table 1.

Claims

1. A method for preparing an environmentally friendly thermosetting powder coating, characterized in that: The steps include: (1) mixing an epoxy resin with a solvent prepared by mixing n-butanol and ethylene glycol monobutyl ether, and then preparing a dispersion 1 by stirring and heating; (2) adding nano zirconium oxide particles and a surfactant to ethanol and stirring evenly, then adding an ammonia solution to adjust the pH value of the system, then adding ethyl orthosilicate, heating the resulting mixture for reaction, filtering and washing the resulting solid to prepare ZrO2 / SiO2 particles; (3) adding the ZrO2 / SiO2 particles prepared in step (2) and the modifier into toluene for reflux reaction, and after the reaction is completed, washing the obtained solid with toluene to prepare surface-modified ZrO2 / SiO2 particles; (4) adding the surface-modified ZrO2 / SiO2 particles obtained in step (3) to the polymerization monomer, and then adding an initiator and stirring evenly to obtain a dispersion 2; (5) continuing to heat the dispersion 1 prepared in step (1) to a higher temperature, and then slowly dropping the dispersion 2 prepared in step (4), and continuing to maintain a constant temperature reaction until the polycondensation reaction is completed; after the system cools to room temperature, extracting the reaction product with toluene, and distilling the extract to remove the solvent to obtain an epoxy acrylic copolymer powder containing surface-modified ZrO2 / SiO2 particles; (6) The epoxy acrylic copolymer powder containing surface-modified ZrO2 / SiO2 particles obtained in step (5) is mixed evenly with a pigment, a accelerator, a flame retardant, an additive and a filler, and then fed into an extruder for melt extrusion. After extrusion cooling, the mixture is crushed and sieved to obtain the environmentally friendly thermosetting powder coating.

2. The method for preparing an environmentally friendly thermosetting powder coating according to claim 1, characterized in that: The heating temperature in step (1) is 80-100°C.

3. The method for preparing an environmentally friendly thermosetting powder coating according to claim 1, characterized in that: The particle size of the nano zirconium oxide particles described in step (2) is in the range of 100-200 nm.

4. The method for preparing an environmentally friendly thermosetting powder coating according to claim 1, characterized in that: The surfactant described in step (2) is selected from one of fatty alcohol polyoxyethylene ether, Tween 80 or dodecyltrimethylammonium chloride.

5. The method for preparing an environmentally friendly thermosetting powder coating according to claim 1, characterized in that: The modifier described in step (3) is one of methacryloxypropyltrimethoxysilane, isopropyl tri(dioctylpyrophosphate) titanate, stearic acid, lauric acid or oleic acid.

6. The method for preparing an environmentally friendly thermosetting powder coating according to claim 1, characterized in that: The initiator described in step (4) is one of benzoyl peroxide, benzophenone peroxide or tert-butyl hydroperoxide.

7. The method for preparing an environmentally friendly thermosetting powder coating according to claim 1, characterized in that: The polymerizable monomer in step (4) is one of acrylic acid, methacrylic acid, hydroxypropyl acrylate, methyl methacrylate or butyl acrylate.

8. The method for preparing the epoxy resin composite material according to claim 1, characterized in that: The isothermal reaction temperature in step (5) is 90-120°C.

9. An environmentally friendly thermosetting powder coating prepared by the method for preparing an environmentally friendly thermosetting powder coating as claimed in any one of claims 1 to 8, characterized in that: The mass ratio of the surface modified ZrO2 / SiO2 particles is 1.0-2.5%.

10. Use of the epoxy resin composite material obtained by the preparation method of the epoxy resin composite material according to any one of claims 1 to 8 or the environmentally friendly thermosetting powder coating according to claim 9 in the corrosion protection of metal materials.