Nanometer modified epoxy powder coating and preparation method thereof

Abstract

The application relates to the technical field of epoxy powder coating, and discloses a nano-modified epoxy powder coating and a preparation method, specifically two new phenyl silane coupling agents containing imidazole derivatives are synthesized, the phenyl silane coupling agents are used for surface modification of nano-filler (the nano-filler is compounded by nano-SiO2 with corrosion-resistant function and rutile-type nano-TiO2 with excellent ultraviolet shielding effect), a curing-promoting nano-filler with low-temperature curing function is prepared, the filler is premixed with an epoxy resin, a curing agent, pigments, fillers and additives, melt-extruded, cooled, broken, ground and sieved to prepare the nano-modified epoxy powder coating. The nano-modified epoxy powder coating prepared by the application can be rapidly cured below 160 DEG C, and the coating obtained through curing exhibits excellent corrosion resistance and weather resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of epoxy powder coating, in particular to a nano-modified epoxy powder coating and a preparation method thereof. BACKGROUND

[0002] The epoxy powder coating is a solid powder coating composed of epoxy resin, curing agent, pigment, filler and additive, which is prepared by pre-mixing, melt extrusion, cooling, crushing, grinding and sieving. The coating is uniformly attached to the surface of metal (such as low carbon steel) by electrostatic spraying or fluidized bed dipping, and is cured to form a hard and durable coating under heating, thereby protecting the metal from corrosion.

[0003] Since the molecular structure of epoxy resin contains aromatic ether bonds which are easily degraded by ultraviolet light, oxidation and molecular chain rupture will occur under the irradiation of outdoor sunlight (especially UV ultraviolet light). In addition, the epoxy system (such as dicyandiamide curing) usually needs to be cured at a high temperature of 180-200℃ for 10-15 minutes, which not only consumes high energy but also limits its application on heat-sensitive substrates (such as some plastics, pre-assembled parts, electronic components). Therefore, the epoxy powder coating has inherent defects of poor weather resistance and high curing temperature.

[0004] In addition, after the epoxy resin is cured, defects such as pores and cracks are easily generated in the coating, so that corrosive media such as water and oxygen can penetrate into the epoxy resin through these small pores, thereby destroying the corrosion resistance of the coating and accelerating the corrosion of the metal.

[0005] It has been found that the epoxy powder coating prepared by using 3-glycidoxypropyltrimethoxysilane modified silica nanoparticles as filler exhibits excellent corrosion resistance. Nano-titanium dioxide has excellent ultraviolet shielding effect, which can help to improve the ultraviolet resistance of the powder coating. The addition of imidazole type accelerator can reduce the curing temperature of the dicyandiamide system and shorten the curing time.

[0006] Based on this, the present application proposes to use imidazole type curing accelerator in combination with nano-filler, so as to simultaneously achieve the technical goals of low-temperature rapid curing, improving the corrosion resistance and weather resistance of the coating. SUMMARY

[0007] The present application synthesizes a phenyl silane coupling agent containing imidazole derivative, which is modified on the surface of nano-filler to prepare a curing-promoting nano-filler. The filler, together with epoxy resin, curing agent, pigment, filler and additive, is pre-mixed, melt-extruded, cooled, crushed, ground and sieved to prepare a nano-modified epoxy powder coating. The coating can simultaneously achieve the technical goals of low-temperature rapid curing, improving the corrosion resistance and weather resistance of the coating.

[0008] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0009] A nano-modified epoxy powder coating, comprising the following raw materials in parts by weight: 90-110 parts of epoxy resin, 3-5 parts of curing-promoting nano-filler, 2-3 parts of barium sulfate, 2-4 parts of curing agent, 1-2 parts of leveling agent, 30-40 parts of pigment, 0.4-0.6 parts of defoaming agent, 0.5-1.5 parts of polyethylene wax powder;

[0010] The curing-promoting nano-filler is prepared by compounding curing-promoting nano-SiO2 and curing-promoting nano-TiO2 in a mass ratio of 2:1.

[0011] The curing-promoting nano-SiO2 is prepared by surface modification of nano-SiO2 rich in hydroxyl functional groups with a phenyl silane coupling agent containing imidazole derivatives.

[0012] The curing-promoting nano-TiO2 is prepared by surface modification of rutile-type nano-TiO2 rich in hydroxyl functional groups with a phenyl silane coupling agent containing imidazole derivatives.

[0013] The phenyl silane coupling agent containing imidazole derivatives is phenyl silane coupling agent I or / and phenyl silane coupling agent II.

[0014] Preferably, the amount of phenyl silane coupling agent in the curing-promoting nano-SiO2 is 5wt%-15wt% of the amount of nano-SiO2.

[0015] The amount of phenyl silane coupling agent in the curing-promoting nano-TiO2 is 5wt%-15wt% of the amount of nano-TiO2.

[0016] Preferably, the particle size of the nano-SiO2 is 30-100nm.

[0017] Preferably, the particle size of the nano-TiO2 is 30-100nm.

[0018] Preferably, the model of the epoxy resin is E-12, the curing agent is dicyandiamide, the model of the leveling agent is BYK-360P, the pigment is titanium white, and the defoaming agent is benzoin.

[0019] Preferably, the curing temperature of the epoxy powder coating is 140-160℃.

[0020] A preparation method of a nano-modified epoxy powder coating, comprising the following steps: according to the formula of the nano-modified epoxy powder coating, ingredients are prepared, the raw materials are mixed uniformly, and then the nano-modified epoxy powder coating is prepared through the processes of melting extrusion, cooling crushing and grinding screening.

[0021] The feeding temperature in the melt extrusion process is set to 70-80 DEG C, and the melt section and discharging temperature is set to 90-110 DEG C.

[0022] Preferably, the preparation method of the phenyl silane coupling agent I is as follows:

[0023] Based on the ring-opening reaction mechanism of secondary amine-epoxy groups, 1 mol equivalent of 2-ethyl-4-methyl imidazole and 1 mol equivalent of allyl glycidyl ether are used as raw materials to prepare intermediate 1-1.

[0024] Based on the silicon-hydrogen addition reaction mechanism, 1 mol equivalent of intermediate 1-1 and 1 mol equivalent of 1,1,5,5-tetramethyl-3,3-diphenyl trisiloxane are reacted to prepare intermediate 1-2.

[0025] Based on the silicon-hydrogen addition reaction mechanism, 1 mol equivalent of intermediate 1-2 and 1 mol equivalent of allyl triethoxysilane are reacted to prepare the phenyl silane coupling agent I.

[0026] Preferably, the preparation method of the phenyl silane coupling agent II is as follows:

[0027] Based on the silicon-hydrogen addition reaction mechanism, 1 mol equivalent of intermediate 1-1 and 1 mol equivalent of 3,13-dihydrogen octaphenyl double-clam half-silicon oxide are reacted to prepare intermediate 2-1.

[0028] The silicon-hydrogen bond of 1 mol equivalent of intermediate 2-1 is reacted with the alkyl functional group of 1 mol equivalent of allyl triethoxysilane to prepare the phenyl silane coupling agent II.

[0029] Preferably, the nano-modified type epoxy powder coating is uniformly attached to the surface of solar photovoltaic supports, outdoor lamps and outdoor plastic furniture or equipment by electrostatic spraying or fluidized bed dipping, and a hard and durable coating is formed at a temperature of 140-160 DEG C.

[0030] The present application has the following advantages:

[0031] Based on the molecular design mechanism, two new phenyl silane coupling agents containing imidazole derivatives are synthesized, the phenyl silane coupling agent is used as the surface modification of the nano-filler (the nano-filler is composed of nano-SiO2 with corrosion-resistant function and rutile nano-TiO2 with excellent ultraviolet shielding effect), a curing-promoting type nano-filler with low-temperature curing function is prepared, and the hydroxyl groups and benzene ring structures contained on the surface of the filler can improve the compatibility of the nano-filler and the epoxy resin.

[0032] The curing-promoting type nano-filler is used as the functional modified filler of the epoxy powder coating to prepare the nano-modified type epoxy powder coating.

[0033] The experimental results prove that the nano modified epoxy powder coating prepared by the application can be rapidly cured below 160 DEG C, and the coating obtained by curing exhibits superior corrosion resistance and weather resistance. DETAILED DESCRIPTION Example One

[0034] The synthetic process of the phenyl silane coupling agent I is as follows:

[0035] Step one: through the ring opening reaction of 1 mole equivalent of the secondary amine function of 2-ethyl-4-methyl imidazole and 1 mole equivalent of the epoxy group of allyl glycidyl ether, an intermediate 1-1 is generated;

[0036] Step two: through the reaction of 1 mole equivalent of the alkenyl function of the intermediate 1-1 and 1 mole equivalent of the silicon-hydrogen bond of 1,1,5,5-tetramethyl-3,3-diphenyl trisiloxane, an intermediate 1-2 is generated;

[0037] Step three: through the reaction of 1 mole equivalent of the silicon-hydrogen bond of the intermediate 1-2 and 1 mole equivalent of the alkenyl function of allyl triethoxysilane, the phenyl silane coupling agent I is generated;

[0038] The experimental steps of the phenyl silane coupling agent I are as follows:

[0039] Step one: 2.21g of 2-ethyl-4-methyl imidazole is added into a reaction container, 30mL of dimethylbenzene is added, after the addition, the temperature is increased to 120 DEG C, after stirring to dissolve, 2.3g of allyl glycidyl ether is added, the reaction is continuously carried out at 120 DEG C for 2h, it is reduced to room temperature, the solvent is removed by reduced pressure distillation, and vacuum drying is carried out at 60 DEG C for 10h, so as to prepare the intermediate 1-1;

[0040] Step two: 2.25g of the intermediate 1-1, 3.34g of 1,1,5,5-tetramethyl-3,3-diphenyl trisiloxane and 40mL of N,N-dimethylformamide are added into a 250mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet pipe, nitrogen is introduced, heating and stirring are carried out, the temperature is increased to 70 DEG C, 1mL of chloroplatinic acid isopropanol solution (0.02g / mL) is added dropwise, after the dropwise addition is completed, the reaction is carried out at 90 DEG C for 5h, after the reaction is completed, the solvent is removed by reduced pressure distillation, washing is carried out, and vacuum drying is carried out, so as to prepare the intermediate 1-2;

[0041] Step three: under the protection of nitrogen, 5.57g of the intermediate 1-2 and 2.05g of allyl triethoxysilane are added into 50mL of N,N-dimethylformamide, mechanical stirring is uniformly carried out, the temperature is increased to 70 DEG C, 2mL of chloroplatinic acid isopropanol solution (0.02g / mL) is added dropwise, after the dropwise addition is completed, the temperature is increased to 90 DEG C, and the reaction is carried out for 5h, the solvent is removed by reduced pressure distillation, and vacuum drying is carried out at 60 DEG C until the weight is constant, so as to prepare the phenyl silane coupling agent I.

[0042] The chemical structural formula of the phenyl silane coupling agent I is as follows:

[0043] ;

[0044] The nuclear magnetic resonance hydrogen spectrum of the phenyl silane coupling agent I is characterized as follows:

[0045] 1 H NMR (DMSO-d6, 400 MHz) δ: 0.08 (s, 12H), 0.68-0.88 (m, 6H), 1.17-1.19 (t, 9H), 1.26-1.29 (t, 3H), 1.37-1.45 (m, 2H), 1.52-1.59 (m, 2H), 2.29 (s, 3H), 2.74-2.78 (m, 2H), 3.34-3.41 (m, 2H), 3.45-3.54 (m, 2H), 3.77-3.82 (m, 6H), 3.88-3.98 (m, 2H), 4.05-4.06 (d, 1H), 4.11-4.17 (m, 1H), 6.83 (s, 1H), 7.23-7.26 (t, 4H), 7.34-7.37 (t, 2H), 7.46-7.47 (d, 4H). Example Two:

[0046] The phenyl silane coupling agent II is synthesized, and the synthesis process is as follows:

[0047] Step 1: through the reaction of 1 mole equivalent of the alkenyl functional group of the intermediate 1-1 and 1 mole equivalent of the silicon-hydrogen bond of 3,13-dihydrooctaphenyl disquisilase (DDSQ-H), the intermediate 2-1 is generated;

[0048] Step 2: through the reaction of 1 mole equivalent of the silicon-hydrogen bond of the intermediate 2-1 and 1 mole equivalent of the alkenyl functional group of allyl triethoxysilane, the phenyl silane coupling agent II is generated;

[0049] The experimental steps of the phenyl silane coupling agent II are as follows:

[0050] Step 1: 100 mL of isopropyl alcohol, 2.84 g of deionized water and 2.85 g of sodium hydroxide are added to a 250 mL three-necked flask protected by nitrogen, and after being fully stirred and uniformly mixed, 21.24 g of phenyl trimethoxysilane is continuously added, and the reaction is carried out at 80°C under reflux for 4 h, and then cooled to room temperature, and the reaction is continued for 15 h, after the reaction is completed, white solid is obtained by rotary evaporation, and dried in a vacuum oven at 40°C for 6 h to obtain sodium octaphenylcyclotetrasiloxane tetrasilanol;

[0051] Under nitrogen protection, 11.24 g of sodium octaphenylcyclotetrasiloxane silanol and 2.94 mL of triethylamine were added to 100 mL of anhydrous tetrahydrofuran, and stirring was performed under ice bath, and a 10 mL tetrahydrofuran solution containing 3.42 g of methyldichlorosilane was added dropwise, and after reaction at 0°C for 4 h, the reaction was continued at room temperature for 20 h, and after the reaction was completed, the solvent was removed by rotary evaporation, washed, and dried at 60°C under vacuum for 7 h to obtain 3,13-dihydrooctaphenylbiscassie siloxane (DDSQ-H);

[0052] Step two: 5.77 g of 3,13-dihydrooctaphenylbiscassie siloxane, 1.12 g of intermediate 1-1, and 50 mL of toluene were added to a 100 mL two-neck flask under nitrogen protection, and 1 mL of chloroplatinic acid isopropyl alcohol solution (0.02 g / mL) was added dropwise under stirring, and the reaction was performed at 80°C for 24 h, and after the reaction was completed, the solvent was removed by rotary evaporation to obtain intermediate 2-1;

[0053] Step three: 6.9 g of intermediate 2-1 and 1.1 g of allyl triethoxysilane were added to 50 mL of toluene, and mechanical stirring was performed until uniform, 1 mL of chloroplatinic acid isopropyl alcohol solution (0.02 g / mL) was added dropwise, the temperature of the system was increased to 80°C, and the reaction was performed for 24 h, the solvent was removed by rotary evaporation, washed, and dried at 60°C under vacuum for 8 h to obtain phenyl silane coupling agent II;

[0054] The chemical structural formula of phenyl silane coupling agent II is:

[0055] ;

[0056] wherein R is a phenyl group, and the chemical structure is ;

[0057] The nuclear magnetic resonance hydrogen spectrum of phenyl silane coupling agent II is characterized as:

[0058] 1H NMR (DMSO-d6, 400 MHz) δ: 0.11 (s, 6H), 0.70-0.82 (m, 2H), 0.90-0.94 (t, 2H), 1.01-1.16 (m, 2H), 1.23-1.26 (t, 9H), 1.36-1.39 (t, 3H), 1.48-1.56 (m, 2H), 1.60-1.69 (m, 2H), 2.29 (s, 3H), 2.74-2.78 (m, 2H), 3.40-3.43 (t, 2H), 3.48-3.57 (m, 2H), 3.77-3.82 (m, 6H), 3.90-4.00 (m, 2H), 4.08-4.09 (d, 1H), 4.14-4.20 (m, 1H), 6.83 (s, 1H), 7.27-7.34 (m, 24H), 7.50-7.55 (m, 16H). Example 3

[0059] (1) The curing-promoting nano-SiO2 is prepared by surface modification of nano-SiO2 (average particle size 50 nm) with a phenylsilane coupling agent to enrich the surface with hydroxyl functional groups;

[0060] The curing-promoting nano-SiO2 specifically includes curing-promoting nano-SiO2 (I), curing-promoting nano-SiO2 (II), and curing-promoting nano-SiO2 (I+II);

[0061] The method for preparing the curing-promoting nano-SiO2 (I) comprises the following steps: 10 g of nano-SiO2 (average particle size 50 nm) is added to 100 mL of an ethanol solution (ethanol:water = 19:1, mass ratio), mechanically stirred until uniform, 1.2 g of phenylsilane coupling agent I is added, the temperature of the system is raised to 110°C, and the system is refluxed and condensed for 3 h, after which it is cooled to room temperature, filtered, washed, and vacuum dried at 50°C for 8 h to obtain the curing-promoting nano-SiO2 (I);

[0062] The method for preparing the curing-promoting nano-SiO2 (II) differs from the method for preparing the curing-promoting nano-SiO2 (I) only in that 1.2 g of phenylsilane coupling agent II is used instead of 1.2 g of phenylsilane coupling agent I;

[0063] The method for preparing the curing-promoting nano-SiO2 (I+II) differs from the method for preparing the curing-promoting nano-SiO2 (I) only in that 0.6 g of phenylsilane coupling agent I and 0.6 g of phenylsilane coupling agent II are used instead of 1.2 g of phenylsilane coupling agent I;

[0064] (2) The curing-promoting nano-TiO2 is prepared by surface modification of the rutile nano-TiO2 (average particle size 50 nm) with phenyl silane coupling agent, which is rich in hydroxyl functional groups on the surface;

[0065] The curing-promoting nano-TiO2 specifically includes curing-promoting nano-TiO2 (I), curing-promoting nano-TiO2 (II) and curing-promoting nano-TiO2 (I+II);

[0066] The method for preparing the curing-promoting nano-TiO2 (I) comprises the following steps: 10 g of rutile nano-TiO2 (average particle size 50 nm) is added into 100 mL of ethanol solution (ethanol: water = 19:1, mass ratio), mechanically stirred uniformly, 1.2 g of phenyl silane coupling agent I is added, the temperature of the system is raised to 110°C, and the condensation reflux reaction is carried out for 3 h, then the system is cooled to room temperature, filtered, washed and vacuum dried at 50°C for 8 h, thereby obtaining the curing-promoting nano-TiO2 (I);

[0067] The method for preparing the curing-promoting nano-TiO2 (II) is different from the method for preparing the curing-promoting nano-TiO2 (I) only in that 1.2 g of phenyl silane coupling agent II is used to replace 1.2 g of phenyl silane coupling agent I;

[0068] The method for preparing the curing-promoting nano-TiO2 (I+II) is different from the method for preparing the curing-promoting nano-TiO2 (I) only in that 0.6 g of phenyl silane coupling agent I and 0.6 g of phenyl silane coupling agent II are used to replace 1.2 g of phenyl silane coupling agent I;

[0069] (3) The curing-promoting nano-sized filler is prepared by compounding the curing-promoting nano-SiO2 and the curing-promoting nano-TiO2 according to a mass ratio of 2:1, and the compounded filler includes curing-promoting nano-sized filler (I), curing-promoting nano-sized filler (II) and curing-promoting nano-sized filler (I+II), and the specific formula is shown in Table 1.

[0070] Table 1 Formula of the curing-promoting nano-sized filler

[0071] Example Four:

[0072] (1) The nano-modified epoxy powder coating I is prepared from the following raw materials:

[0073] E-12 bisphenol A type epoxy resin (model 604), 100 parts by weight;

[0074] Curing-promoting nano-filler (I), 4 parts by weight;

[0075] Barium sulfate, 2.5 parts by weight;

[0076] Dicyandiamide curing agent, 3 parts by weight;

[0077] Leveling agent (model BYK-360P), 1.5 parts by weight;

[0078] Titanium white, 35 parts by weight;

[0079] Gum benzoin, 0.5 parts by weight;

[0080] Polyethylene wax powder, 1 part by weight;

[0081] The preparation method of the nano-modified epoxy powder coating I comprises the following steps:

[0082] According to the formula of the nano-modified epoxy powder coating I, E-12 bisphenol A type epoxy resin, dicyandiamide curing agent, leveling agent, titanium white, gum benzoin and polyethylene wax powder are mixed, and then the curing-promoting nano-filler I is added. After being fully mixed, the mixture is put into a double-screw extruder. The feeding temperature is set to 75℃, and the melting section and the discharging temperature are set to 100℃. High-temperature melting extrusion is performed. After extrusion, the material is crushed into powder by a grinding machine, and then sieved through a 160-mesh fine sieve to obtain the nano-modified epoxy powder coating I.

[0083] (2) The nano-modified epoxy powder coating II is prepared, which is only different from the nano-modified epoxy powder coating I in that the curing-promoting nano-filler (I) is replaced by the curing-promoting nano-filler (II).

[0084] (3) The nano-modified epoxy powder coating III is prepared, which is only different from the nano-modified epoxy powder coating I in that the curing-promoting nano-filler (I) is replaced by the curing-promoting nano-filler (I+II).

[0085] Performance test:

[0086] I. Gelation time: According to the standard of GB / T 16995-1997 "Determination of gelation time of thermosetting powder coating at a given temperature", 0.25 mL of the nano-modified epoxy powder coating is placed on a test plate preheated to 140℃ or 160℃. When the powder on the test plate just melts, the timing starts. At this time, a needle with low heat capacity is used to stir a small circle on the melted powder every 2-3 seconds. When the silk formed by lifting the powder up about 1 cm breaks or cannot be lifted out of the melted powder, the timing stops. The time recorded at this time is the gelation time of the powder coating.

[0087] II. The tinplate sheet with a size of 120mm*50mm is polished by dry grinding with No.600 sandpaper, and after ensuring that the original surface layer is completely removed, the surface residual substances are wiped clean with acetone and dried for standby;

[0088] The nano-modified epoxy powder coating prepared in the application is uniformly sprayed on the treated tinplate sheet using an electrostatic spraying device, and a coating sample with a thickness of 100μm is prepared after curing at 160℃ for 20min;

[0089] (1) Impact resistance: According to the standard GB / T 1732-2020 "Paint film impact resistance test method", the positive impact height and the reverse impact height of the coating sample are tested;

[0090] (2) UV resistance test: the coating sample is placed in a UV aging oven for aging treatment, the temperature is 50℃, 8 UV-B irradiation, the irradiation light intensity is 0.68W / m 2 , the sample is taken out after irradiation for 48h and 144h respectively, and the gloss of the coating sample is measured using a gloss meter;

[0091] (3) Corrosion resistance test: according to the standard HG / T 2006-2022 "Thermosetting and thermoplastic powder coatings", the alkali resistance, acid resistance and salt spray resistance of the coating sample are tested;

[0092] The above test results are shown in Table 2 below;

[0093] Table 2 Performance test results of nano-modified epoxy powder coating

[0094]

[0095] The difference between the comparative example and the nano-modified epoxy powder coating I is only that no curing-promoting nano filler (I) is added;

[0096] From the test results, it can be seen that the nano-modified epoxy powder coating prepared in the application can realize low-temperature rapid curing, and the coating obtained after curing has achieved significant improvement in corrosion resistance and UV resistance.

Claims

1. A nano-modified epoxy powder coating, characterized in that, The raw materials include the following weight parts: 90-110 parts of epoxy resin, 3-5 parts of curing-promoting nano-filler, 2-3 parts of barium sulfate, 2-4 parts of curing agent, 1-2 parts of leveling agent, 30-40 parts of pigment, 0.4-0.6 parts of defoaming agent, and 0.5-1.5 parts of polyethylene wax powder; The curing-promoting nano-filler is prepared by compounding curing-promoting nano-SiO2 and curing-promoting nano-TiO2 at a mass ratio of 2:1; The curing-promoting nano-SiO2 is prepared by surface modification of nano-SiO2 rich in hydroxyl functional groups with phenyl silane coupling agent containing imidazole derivatives; The curing-promoting nano-TiO2 is prepared by surface modification of rutile-type nano-TiO2 rich in hydroxyl functional groups with phenyl silane coupling agent containing imidazole derivatives; The phenyl silane coupling agent containing imidazole derivatives is phenyl silane coupling agent I or / and phenyl silane coupling agent II; The chemical structural formula of the phenyl silane coupling agent I is as follows: ； The chemical structural formula of the phenyl silane coupling agent II is as follows: ； wherein R is a phenyl group having the chemical structure .

2. The nano-modified epoxy powder coating according to claim 1, characterized in that, The amount of the phenyl silane coupling agent in the curing-promoting nano-SiO2 is 5wt%-15wt% of the amount of nano-silica; The amount of the phenyl silane coupling agent in the curing-promoting nano-TiO2 is 5wt%-15wt% of the amount of nano-titania.

3. The nano-modified epoxy powder coating according to claim 2, characterized in that, The particle size of the nano-silica is 30-100nm.

4. The nano-modified epoxy powder coating according to claim 2, characterized in that, The particle size of the nano-titania is 30-100nm.

5. The nano-modified epoxy powder coating according to claim 1, characterized in that, The model of the epoxy resin is E-12, the curing agent is dicyandiamide, the model of the leveling agent is BYK-360P, the pigment is titanium white, and the defoaming agent is benzoin.

6. The nano-modified epoxy powder coating according to claim 1, characterized in that, The curing temperature of the epoxy powder coating is 140-160℃.

7. The method for preparing a nano-modified epoxy powder coating according to claim 1, characterized in that, The method comprises the following steps: According to the formula of the nano-modified epoxy powder coating, the raw materials are mixed uniformly, and then the nano-modified epoxy powder coating is prepared through the processes of melting extrusion, cooling crushing and grinding screening; The feeding temperature in the process of melting extrusion is set to 70-80℃, and the melting section and the discharging temperature are set to 90-110℃.

8. The method for preparing a nano-modified epoxy powder coating according to claim 7, characterized in that, The preparation method of the phenyl silane coupling agent I is as follows: Based on the ring-opening reaction mechanism of secondary amine-epoxy groups, 1 mole equivalent of 2-ethyl-4-methyl imidazole and 1 mole equivalent of allyl glycidyl ether are used as raw materials to prepare intermediate 1-1; Based on the silicon-hydrogen addition reaction mechanism, 1 mole equivalent of intermediate 1-1 reacts with 1 mole equivalent of 1,1,5,5-tetramethyl-3,3-diphenyl trisiloxane to prepare intermediate 1-2; Based on the silicon-hydrogen addition reaction mechanism, 1 mole equivalent of intermediate 1-2 reacts with 1 mole equivalent of allyl triethoxysilane to prepare the phenyl silane coupling agent I.

9. The method for preparing a nano-modified epoxy powder coating according to claim 7, characterized in that, The preparation method of the phenyl silane coupling agent II is as follows: Based on the silicon-hydrogen addition reaction mechanism, 1 mole equivalent of intermediate 1-1 reacts with 1 mole equivalent of 3,13-dihydrooctaphenyl bis-clam plate silsesquioxane to prepare intermediate 2-1; The phenylsilane coupling agent II is prepared by reacting 1 mole equivalent of the silicon-hydrogen bond of intermediate 2-1 with 1 mole equivalent of the alkenyl functional group of allyltriethoxysilane.

10. The nano-modified epoxy powder coating according to claim 1, characterized in that, The nano-modified epoxy powder coating is cured at a temperature of 140-160 DEG C to form a hard and durable coating by electrostatic spraying or fluidized bed dip coating.

Images