Epoxy powder coating with high wear resistance and salt spray resistance and preparation method thereof

Abstract

The invention belongs to the technical field of powder coatings, and particularly relates to a high-wear-resistance and salt-fog-resistance epoxy powder coating and a preparation method thereof. The epoxy powder coating with high wear resistance and salt spray resistance is prepared from the following raw materials in parts by weight: 40 to 60 parts of modified epoxy resin, 15 to 30 parts of carboxyl-terminated polyester resin, 10 to 25 parts of fluorosilane modified composite filler, 10 to 25 parts of curing agent, 0.5 to 1 part of benzoin, 0 to 20 parts of pigment and 0.3 to 2 parts of other auxiliaries. The invention provides a high-wear-resistance and salt-fog-resistance epoxy powder coating and a preparation method thereof, which are used for solving the technical problems of poor hardness, weather resistance and salt fog resistance of the epoxy powder coating in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of powder coatings, and in particular relates to a highly wear-resistant and salt-spray-resistant epoxy powder coating and a preparation method thereof. Background Art

[0002] Powder coatings are mainly solid powders mixed with resins, curing agents, pigments, fillers, additives, etc., which are applied to the surface of the object by electrostatic spraying, and then baked to make it melt and level, and solidify into a film. Because it does not contain any organic solvents, is pollution-free, has high utilization rate, low energy consumption, and simple process, it has become a "4E type" (high production efficiency, excellent coating performance, ecological and environmental protection, and economic) coating recognized by everyone, and is widely used in construction, steel, automobiles, home appliances and other fields.

[0003] According to the different types of resins, powder coatings can be divided into two categories: one is thermoplastic powder coatings prepared from thermoplastic resins, and the other is thermosetting powder coatings prepared from thermosetting resins. At present, the thermosetting powder coatings that are studied more are mainly epoxy resin powder coatings, polyester powder coatings, polyurethane powder coatings, acrylic powder coatings, etc. Traditional epoxy resin powder coatings have poor weather resistance and salt spray resistance, which limits their application in outdoor environments.

[0004] Therefore, it is necessary to develop an epoxy powder coating with high wear resistance, excellent weather resistance and salt spray resistance. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a highly wear-resistant and salt-spray-resistant epoxy powder coating and a preparation method thereof, so as to solve the technical problems of poor hardness, weather resistance and salt-spray resistance of the epoxy powder coating in the prior art.

[0006] The technical solution adopted by the present invention to solve the above problems is as follows:

[0007] A highly wear-resistant and salt-spray-resistant epoxy powder coating comprises the following raw materials in parts by weight: 40 to 60 parts of modified epoxy resin, 15 to 30 parts of terminal carboxyl polyester resin, 10 to 25 parts of fluorosilane-modified composite filler, 10 to 25 parts of curing agent, 0.5 to 1 part of benzoin, 0 to 20 parts of pigment and 0.3 to 2 parts of other additives.

[0008] Furthermore, the preparation method of the modified epoxy resin includes: adding bisphenol A epoxy resin and polyvinyl pyrrolidone, stirring and mixing and heating to 100-110° C.; adding epoxy phosphate, heating to 120-140° C., reacting for 3-8 hours, and cooling to obtain the modified epoxy resin.

[0009] Furthermore, the weight ratio of the bisphenol A epoxy resin, the epoxy phosphate and the polyvinyl pyrrolidone is (20-35):3:(3-7).

[0010] Furthermore, the acid value of the carboxyl-terminated polyester resin is 25 mgKOH / g to 50 mgKOH / g.

[0011] Furthermore, the fluorosilane modified composite filler includes the following raw materials in parts by weight: 25-45 parts of nano silicon nitride, 3-10 parts of nano gadolinium oxide, 3-20 parts of nano talc, 36-55 parts of fluorine-containing silane coupling agent, 12-22 parts of tetrapropyl orthosilicate, and 18-35 parts of sodium dibutylnaphthalene sulfonate.

[0012] Furthermore, the preparation method of the fluorosilane modified composite filler comprises the following steps:

[0013] S1. The nano-silicon nitride, nano-gadolinium oxide and nano-talc are mixed uniformly to obtain a mixture, and then the mixture is added to water and ultrasonically dispersed for 5 to 15 minutes to obtain a dispersion;

[0014] S2. Add a fluorinated silane coupling agent to the dispersion and stir at 70 to 100° C. for 20 to 40 minutes;

[0015] S3. Then add tetrapropyl orthosilicate and sodium dibutylnaphthalene sulfonate, stir and react at 120-150° C. for 20-40 min, then let stand for 4-8 h, and obtain the fluorosilane-modified composite filler after filtering, washing and drying.

[0016] Furthermore, the curing agent is at least one of toluene diisocyanate, hexyl diisocyanate, and hexamethylene diisocyanate.

[0017] Furthermore, the other additives include one or more of a stabilizer, a defoamer and a leveling agent.

[0018] The present invention also provides a method for preparing the highly wear-resistant and salt-spray-resistant epoxy powder coating as described above, comprising the following steps: uniformly mixing modified epoxy resin, carboxyl-terminated polyester resin, fluorosilane-modified composite filler, curing agent, benzoin, pigment and other additives according to the weight proportion of the formula, melt-extruding, cooling, crushing and sieving to obtain the highly wear-resistant and salt-spray-resistant epoxy powder coating.

[0019] Furthermore, the melt extrusion method is: in a twin-screw extruder, the temperature of zone I is controlled at 90-100° C. and the temperature of zone II is controlled at 110-120° C. for melt extrusion.

[0020] The present invention has the following beneficial effects:

[0021] (1) Bisphenol A epoxy resin has good mechanical strength and toughness; the added epoxy phosphate helps to improve the bonding force between the paint film and the substrate; in the process of preparing the modified epoxy resin, the present invention combines bisphenol A epoxy resin with epoxy phosphate and polyvinyl pyrrolidone to achieve synergistic effects, thereby improving the solubility and processing properties of the resin; the method for preparing the modified epoxy resin helps to improve the thermal stability of the resin, helps to form a coating with strong corrosion resistance, can effectively block the corrosion of the substrate by external substances, and make the coating have better salt spray resistance; the modified epoxy resin provided by the present invention is combined with a terminal carboxyl polyester resin with a lower acid value, which is beneficial to improving the density of the paint film, so that the paint film has better chemical corrosion resistance and is suitable for a wider range of industrial applications.

[0022] (2) The nano yttrium oxide added in the preparation of the fluorosilane modified composite filler of the present invention helps the coating resist thermal oxidation in a high temperature environment, but the nano yttrium oxide has the defects of poor strength and density; the present invention combines nano yttrium oxide with nano silicon nitride and nano talc, and the three synergistically enhance the effect, strengthen the coating network crosslinking, and help improve the coating strength; at the same time, the present invention uses a fluorine-containing silane coupling agent to coat and modify the three nano fillers, and then adds tetrapropyl orthosilicate and sodium dibutylnaphthalene sulfonate, which improves the dispersibility of the system and the compatibility with the resin, has good bonding, can effectively prevent the penetration of corrosive media, significantly improves the corrosion resistance of the coating, and reduces cracking. The fluorosilane modified composite filler prepared by the present invention is uniform in size, good in dispersibility, and has no agglomeration phenomenon. It can be used in powder coatings to make it have stronger weather resistance, chemical stability, corrosion resistance and hardness.

[0023] (3) The present invention uses modified epoxy resin as the main resin raw material for preparing epoxy powder coatings, and matches it with fluorosilane modified composite fillers, so that the prepared epoxy powder coatings have very excellent wear resistance, weather resistance, salt spray resistance and corrosion resistance, thereby solving the technical problems of poor hardness, weather resistance and salt spray resistance of epoxy powder coatings in the prior art. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and are not limitations of the present invention. 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.

[0025] Unless otherwise specified, the test materials, reagents, methods and equipment used in the following examples are conventional test materials, reagents, methods and equipment in the technical field; unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources. The quantitative tests in the following examples were all repeated three times, and the data are the average or average ± standard deviation of the three repeated experiments.

[0026] Example 1

[0027] A. Preparation of modified epoxy resin: The preparation method of the modified epoxy resin specifically includes the following steps: adding 60 parts by weight of bisphenol A epoxy resin and 9 parts by weight of polyvinyl pyrrolidone, stirring and mixing, and heating to 110°C; adding 9 parts by weight of epoxy phosphate, heating to 130°C, reacting for 5 hours, and cooling to obtain the modified epoxy resin. The weight ratio of the bisphenol A epoxy resin, the epoxy phosphate and the polyvinyl pyrrolidone is 20:3:3.

[0028] B. Preparation of fluorosilane modified composite filler: The fluorosilane modified composite filler includes the following raw materials by weight: 25 parts of nano silicon nitride, 10 parts of nano gadolinium oxide, 16 parts of nano talc, 52 parts of fluorine-containing silane coupling agent, 13 parts of tetrapropyl orthosilicate, and 28 parts of sodium dibutylnaphthalene sulfonate. The preparation method of the fluorosilane modified composite filler specifically includes the following steps:

[0029] S1. The nano-silicon nitride, nano-gadolinium oxide and nano-talc are mixed to obtain a mixture, and then the mixture is added to water and ultrasonically dispersed for 10 minutes to obtain a dispersion;

[0030] S2. Add fluorinated silane coupling agent to the dispersion and stir at 85°C for 30 min;

[0031] S3. Then add tetrapropyl orthosilicate and sodium dibutylnaphthalene sulfonate, stir and react at 130° C. for 30 minutes, then let stand for 6 hours, and obtain a fluorosilane-modified composite filler after filtering, washing and drying.

[0032] C. Preparation of a highly wear-resistant and salt-spray-resistant epoxy powder coating: including the following raw materials by weight: 42 parts of modified epoxy resin, 28 parts of terminal carboxyl polyester resin, 23 parts of fluorosilane modified composite filler, 20 parts of toluene diisocyanate, 0.8 parts of benzoin, 5 parts of pigment, 0.8 parts of leveling agent, and 1 part of stabilizer. The preparation method of the highly wear-resistant and salt-spray-resistant epoxy powder coating comprises the following steps: uniformly mixing the above raw materials according to the weight of the formula, controlling the temperature of the twin-screw extruder zone I to 90-100°C and the temperature of the zone II to 110-120°C in a twin-screw extruder for melt extrusion, cooling, crushing, and sieving to obtain a highly wear-resistant and salt-spray-resistant epoxy powder coating.

[0033] Example 2

[0034] A. Preparation of modified epoxy resin: The preparation method of the modified epoxy resin specifically includes the following steps: adding 75 parts by weight of bisphenol A epoxy resin and 9 parts by weight of polyvinyl pyrrolidone, stirring and mixing, and heating to 110°C; adding 21 parts by weight of epoxy phosphate, heating to 130°C, reacting for 5 hours, and cooling to obtain the modified epoxy resin. The weight ratio of the bisphenol A epoxy resin, the epoxy phosphate and the polyvinyl pyrrolidone is 25:3:7.

[0035] B. Preparation of fluorosilane modified composite filler: The fluorosilane modified composite filler includes the following raw materials by weight: 32 parts of nano silicon nitride, 6 parts of nano gadolinium oxide, 5 parts of nano talc, 40 parts of fluorine-containing silane coupling agent, 15 parts of tetrapropyl orthosilicate, and 33 parts of sodium dibutylnaphthalene sulfonate. The preparation method of the fluorosilane modified composite filler specifically includes the following steps:

[0036] S1. The nano-silicon nitride, nano-gadolinium oxide and nano-talc are mixed to obtain a mixture, and then the mixture is added to water and ultrasonically dispersed for 10 minutes to obtain a dispersion;

[0037] S2. Add fluorinated silane coupling agent to the dispersion and stir at 85°C for 30 min;

[0038] S3. Then add tetrapropyl orthosilicate and sodium dibutylnaphthalene sulfonate, stir and react at 130° C. for 30 minutes, then let stand for 6 hours, and obtain a fluorosilane-modified composite filler after filtering, washing and drying.

[0039] C. Preparation of highly wear-resistant and salt-spray-resistant epoxy powder coating: including the following raw materials in parts by weight: 50 parts of modified epoxy resin, 25 parts of terminal carboxyl polyester resin, 14 parts of fluorosilane-modified composite filler, 20 parts of hexyl diisocyanate, 0.8 parts of benzoin, 5 parts of pigment, 0.8 parts of leveling agent, and 1 part of stabilizer. The preparation method of the highly wear-resistant and salt-spray-resistant epoxy powder coating comprises the following steps: uniformly mixing the above raw materials according to the weight of the formula, controlling the temperature of the twin-screw extruder zone I to 90-100°C and the temperature of the twin-screw extruder zone II to 110-120°C for melt extrusion, cooling, crushing, and sieving to obtain a highly wear-resistant and salt-spray-resistant epoxy powder coating.

[0040] Example 3

[0041] A. Preparation of modified epoxy resin: The preparation method of the modified epoxy resin specifically includes the following steps: adding 90 parts by weight of bisphenol A epoxy resin and 9 parts by weight of polyvinyl pyrrolidone, stirring and mixing, and heating to 110°C; adding 9 parts by weight of epoxy phosphate, heating to 130°C, reacting for 5 hours, and cooling to obtain the modified epoxy resin. The weight ratio of the bisphenol A epoxy resin, the epoxy phosphate and the polyvinyl pyrrolidone is 30:3:3.

[0042] B. Preparation of fluorosilane modified composite filler: The fluorosilane modified composite filler includes the following raw materials by weight: 41 parts of nano silicon nitride, 8 parts of nano gadolinium oxide, 9 parts of nano talc, 46 parts of fluorine-containing silane coupling agent, 18 parts of tetrapropyl orthosilicate, and 23 parts of sodium dibutylnaphthalene sulfonate. The preparation method of the fluorosilane modified composite filler specifically includes the following steps:

[0043] S1. The nano-silicon nitride, nano-gadolinium oxide and nano-talc are mixed to obtain a mixture, and then the mixture is added to water and ultrasonically dispersed for 10 minutes to obtain a dispersion;

[0044] S2. Add fluorinated silane coupling agent to the dispersion and stir at 85°C for 30 min;

[0045] S3. Then add tetrapropyl orthosilicate and sodium dibutylnaphthalene sulfonate, stir and react at 130° C. for 30 minutes, then let stand for 6 hours, and obtain a fluorosilane-modified composite filler after filtering, washing and drying.

[0046] C. Preparation of highly wear-resistant and salt-spray-resistant epoxy powder coating: including the following raw materials in parts by weight: 53 parts of modified epoxy resin, 22 parts of terminal carboxyl polyester resin, 18 parts of fluorosilane-modified composite filler, 20 parts of hexamethylene diisocyanate, 0.8 parts of benzoin, 5 parts of pigment, 0.8 parts of leveling agent, and 1 part of stabilizer. The preparation method of the highly wear-resistant and salt-spray-resistant epoxy powder coating comprises the following steps: uniformly mixing the above raw materials according to the weight of the formula, controlling the temperature of the twin-screw extruder zone I to 90-100°C and the temperature of the twin-screw extruder zone II to 110-120°C for melt extrusion, cooling, crushing, and sieving to obtain a highly wear-resistant and salt-spray-resistant epoxy powder coating.

[0047] Example 4

[0048] A. Preparation of modified epoxy resin: The preparation method of the modified epoxy resin specifically includes the following steps: adding 99 parts by weight of bisphenol A epoxy resin and 9 parts by weight of polyvinyl pyrrolidone, stirring and mixing, and heating to 110°C; adding 15 parts by weight of epoxy phosphate, heating to 130°C, reacting for 5 hours, and cooling to obtain the modified epoxy resin. The weight ratio of the bisphenol A epoxy resin, the epoxy phosphate and the polyvinyl pyrrolidone is 33:3:5.

[0049] B. Preparation of fluorosilane modified composite filler: The fluorosilane modified composite filler includes the following raw materials by weight: 45 parts of nano silicon nitride, 4 parts of nano gadolinium oxide, 20 parts of nano talc, 36 parts of fluorine-containing silane coupling agent, 21 parts of tetrapropyl orthosilicate, and 20 parts of sodium dibutylnaphthalene sulfonate. The preparation method of the fluorosilane modified composite filler specifically includes the following steps:

[0050] S1. The nano-silicon nitride, nano-gadolinium oxide and nano-talc are mixed to obtain a mixture, and then the mixture is added to water and ultrasonically dispersed for 10 minutes to obtain a dispersion;

[0051] S2. Add fluorinated silane coupling agent to the dispersion and stir at 85°C for 30 min;

[0052] S3. Then add tetrapropyl orthosilicate and sodium dibutylnaphthalene sulfonate, stir and react at 130° C. for 30 minutes, then let stand for 6 hours, and obtain a fluorosilane-modified composite filler after filtering, washing and drying.

[0053] C. Preparation of highly wear-resistant and salt-spray-resistant epoxy powder coating: including the following raw materials in parts by weight: 60 parts of modified epoxy resin, 17 parts of terminal carboxyl polyester resin, 12 parts of fluorosilane-modified composite filler, 20 parts of toluene diisocyanate, 0.8 parts of benzoin, 5 parts of pigment, 0.8 parts of leveling agent, and 1 part of stabilizer. The preparation method of the highly wear-resistant and salt-spray-resistant epoxy powder coating comprises the following steps: uniformly mixing the above raw materials according to the weight of the formula, controlling the temperature of the twin-screw extruder zone I to 90-100°C and the temperature of the twin-screw extruder zone II to 110-120°C for melt extrusion, cooling, crushing, and sieving to obtain a highly wear-resistant and salt-spray-resistant epoxy powder coating.

[0054] Comparative Example 1

[0055] An epoxy powder coating is disclosed, which differs from Example 1 in that in this comparative example, an equal amount of modified epoxy resin is replaced by bisphenol A epoxy resin, and other preparation steps and parameters remain unchanged.

[0056] Comparative Example 2

[0057] An epoxy powder coating is different from Example 1 in that: in the process of preparing the modified epoxy resin, no epoxy phosphate is added in this comparative example, and the bisphenol A epoxy resin is 69 parts by weight, and the other preparation steps and parameters remain unchanged.

[0058] Comparative Example 3

[0059] An epoxy powder coating is different from Example 1 in that: in the process of preparing the fluorosilane-modified composite filler, nano silicon nitride is not added in this comparative example, and the other preparation steps and parameters remain unchanged.

[0060] Comparative Example 4

[0061] An epoxy powder coating is different from Example 1 in that: in the process of preparing the fluorosilane-modified composite filler, nano-gadolinium oxide is not added in this comparative example, and the other preparation steps and parameters remain unchanged.

[0062] Comparative Example 5

[0063] An epoxy powder coating is different from Example 1 in that: in this comparative example, nano talc is not added during the preparation of the fluorosilane-modified composite filler, and the other preparation steps and parameters remain unchanged.

[0064] Comparative Example 6

[0065] An epoxy powder coating is different from Example 1 in that: in the process of preparing the fluorosilane-modified composite filler, no fluorine-containing silane coupling agent is added in this comparative example, and the other preparation steps and parameters remain unchanged.

[0066] Comparative Example 7

[0067] An epoxy powder coating is different from Example 1 in that: in this comparative example, tetrapropyl orthosilicate is not added during the preparation of the fluorosilane-modified composite filler, and the other preparation steps and parameters remain unchanged.

[0068] Comparative Example 8

[0069] An epoxy powder coating is different from Example 1 in that: in the process of preparing the fluorosilane-modified composite filler, sodium dibutylnaphthalene sulfonate is not added in this comparative example, and the other preparation steps and parameters remain unchanged.

[0070] The epoxy powder coatings prepared in Examples 1 to 4 and Comparative Examples 1 to 8 were sprayed on test plates of the same type, with a spray coating thickness of about 80 μm. The coatings were cured at 200° C. for 15 min to obtain cured coatings. The coatings were tested for performance. The test reference standards are as follows:

[0071] 1. Abrasion resistance test: Tested in accordance with GB / T 23988-2009 "Determination of abrasion resistance of coatings - falling sand method";

[0072] 2. Impact resistance test: Tested in accordance with GB / T 1732-2020 "Determination of impact resistance of paint film";

[0073] 3. Hardness test: Test in accordance with GB / T 6739-2006 "Paints and varnishes: Determination of film hardness by pencil method";

[0074] 4. Salt spray resistance test: Tested in accordance with GB / T 1771-2007 "Paints and varnishes: Determination of resistance to neutral salt spray";

[0075] 5. Weather resistance test: Determine by UV lamp method in accordance with GB / T 23987-2009 “Artificial weathering of paint and varnish coatings - Exposure to fluorescent UV and water”.

[0076] The test results of Examples 1 to 4 and Comparative Examples 1 to 8 are shown in Table 1.

[0077] Table 1:

[0078] test Wear resistance Impact resistance hardness Salt spray resistant Weather resistance Example 1 5.6L / μm 63.2cm 4H 3200h UVB-313, 510h Example 2 5.3L / μm 62.6cm 4H 2900h UVB-313, 470h Example 3 5.4L / μm 63.0cm 4H 3100h UVB-313, 490h Example 4 5.4L / μm 62.9cm 4H 3100h UVB-313, 450h Comparative Example 1 3.4L / μm 53.1cm 3H 2300h UVB-313, 390h Comparative Example 2 2.8L / μm 54.4cm 2H 2200h UVB-313, 360h Comparative Example 3 3.1L / μm 50.3cm 3H 2500h UVB-313, 390h Comparative Example 4 3.0L / μm 49.9cm 2H 2200h UVB-313, 370h Comparative Example 5 2.9L / μm 53.2cm 2H 2300h UVB-313, 350h Comparative Example 6 2.5L / μm 49.5cm 1H 2100h UVB-313, 330h Comparative Example 7 2.9L / μm 55.0cm 2H 2400h UVB-313, 350h Comparative Example 8 2.8L / μm 54.8cm 2H 2300h UVB-313, 360h

[0079] From the above performance test results, it can be seen that compared with the powder coatings of comparative examples 1 to 8, the powder coatings of embodiments 1 to 4 of the present invention have better wear resistance, impact resistance, hardness, salt spray corrosion resistance and weather resistance.

[0080] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0081] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0082] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A highly wear-resistant and salt-spray-resistant epoxy powder coating, characterized in that: The invention comprises the following raw materials in parts by weight: 40-60 parts of modified epoxy resin, 15-30 parts of terminal carboxyl polyester resin, 10-25 parts of fluorosilane modified composite filler, 10-25 parts of curing agent, 0.5-1 part of benzoin, 0-20 parts of pigment and 0.3-2 parts of other auxiliary agents.

2. The highly wear-resistant and salt-spray-resistant epoxy powder coating according to claim 1, characterized in that: The preparation method of the modified epoxy resin comprises: adding bisphenol A epoxy resin and polyvinyl pyrrolidone, stirring and mixing, and heating to 100-110° C.; adding epoxy phosphate, heating to 120-140° C., reacting for 3-8 hours, and cooling to obtain the modified epoxy resin.

3. The highly wear-resistant and salt-spray-resistant epoxy powder coating according to claim 2, characterized in that: The weight ratio of the bisphenol A epoxy resin, the epoxy phosphate and the polyvinyl pyrrolidone is (20-35):3:(3-7).

4. The highly wear-resistant and salt-spray-resistant epoxy powder coating according to claim 1, characterized in that: The acid value of the carboxyl-terminated polyester resin is 25 mgKOH / g to 50 mgKOH / g.

5. The highly wear-resistant and salt-spray-resistant epoxy powder coating according to claim 1, characterized in that: The fluorosilane modified composite filler comprises the following raw materials in parts by weight: 25-45 parts of nano silicon nitride, 3-10 parts of nano gadolinium oxide, 3-20 parts of nano talc, 36-55 parts of fluorine-containing silane coupling agent, 12-22 parts of tetrapropyl orthosilicate, and 18-35 parts of sodium dibutylnaphthalene sulfonate.

6. The highly wear-resistant and salt-spray-resistant epoxy powder coating according to claim 5, characterized in that: The preparation method of the fluorosilane modified composite filler comprises the following steps: S1. The nano-silicon nitride, nano-gadolinium oxide and nano-talc are mixed uniformly to obtain a mixture, and then the mixture is added to water and ultrasonically dispersed for 5 to 15 minutes to obtain a dispersion; S2. Add a fluorinated silane coupling agent to the dispersion and stir at 70 to 100° C. for 20 to 40 minutes; S3. Then add tetrapropyl orthosilicate and sodium dibutylnaphthalene sulfonate, stir and react at 120-150° C. for 20-40 min, then let stand for 4-8 h, and obtain the fluorosilane-modified composite filler after filtering, washing and drying.

7. The highly wear-resistant and salt-spray-resistant epoxy powder coating according to claim 1, characterized in that: The curing agent is at least one of toluene diisocyanate, hexyl diisocyanate and hexamethylene diisocyanate.

8. The highly wear-resistant and salt-spray-resistant epoxy powder coating according to claim 1, characterized in that: The other auxiliary agents include one or more of stabilizers, defoamers and leveling agents.

9. A method for preparing the highly wear-resistant and salt-spray-resistant epoxy powder coating according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: uniformly mixing modified epoxy resin, carboxyl-terminated polyester resin, fluorosilane-modified composite filler, curing agent, benzoin, pigment and other additives according to the weight proportion of the formula, and performing melt extrusion, cooling, crushing and sieving to obtain a highly wear-resistant and salt-spray-resistant epoxy powder coating.

10. The method for preparing the highly wear-resistant and salt-spray-resistant epoxy powder coating according to claim 9, characterized in that: The melt extrusion method comprises: controlling the temperature of zone I of the twin-screw extruder to 90-100° C. and the temperature of zone II to 110-120° C. for melt extrusion.