High weather resistant metal powder coating and preparation method thereof

Abstract

The application relates to the field of paint, in particular to a high-weatherability metal powder paint and a preparation method thereof; the high-weatherability metal powder paint comprises the following components in parts by weight: 80-100 parts of resin, 5-9 parts of a curing agent, 30-50 parts of a filler, 1-5 parts of an additive, 10-20 parts of pigment, 1-5 parts of a silane coupling agent, 20-30 parts of nitrogen-phosphorus doped graphene, and the nitrogen-phosphorus doped graphene is adopted, so that the adhesion of the metal powder coating and the substrate and the corrosion resistance of the metal powder coating are effectively improved, and the problem of uneven metal powder in the coating process of the metal powder paint can be avoided; the nitrogen-phosphorus doped graphene is coated on the pigment through a specific preparation process, the contact of the pigment with other materials and air is reduced, and then the discoloration of the pigment caused by long-term exposure to air is reduced; the microwave heating is adopted to coat the pigment and the substrate powder in motion, and the method has the advantages of high efficiency and high quality compared with the existing thermal bonding.

Description

Technical Field

[0001] This invention relates to the field of coatings, and more particularly to a highly weather-resistant metallic powder coating and its preparation method. Background Technology

[0002] Powder coatings are coatings that exist in the form of fine powder. They do not contain organic solvents and have low VOC emissions during curing. Compared with traditional solvent-based coatings, they are environmentally friendly, efficient, and economical. With rising living standards and increased emphasis on environmental protection, they are becoming increasingly popular with consumers. In recent years, the production and variety of powder coatings have been gradually increasing, and their applications have expanded to various fields. Among them, metallic powder coatings, due to their ability to create bright and luxurious decorative effects, are widely used in the spraying of furniture, ornaments, and automobiles, both indoors and outdoors.

[0003] The preparation methods for metallic powder coatings are mainly divided into dry mixing and extrusion. Dry mixing involves mixing flake metallic pigments with powder coating particles. While simple, this method suffers from poor recyclability due to the incompatibility between the pigments and particles. Furthermore, the exposed pigments are easily corroded by atmospheric media, losing their metallic luster and ultimately affecting the decorative effect of the coating. Extrusion, on the other hand, involves treating the flake metallic pigments similarly to other pigments before extrusion and then mixing them with all other raw materials. This method results in the majority of the metallic pigments being pulverized during extrusion, significantly reducing the metallic effect of the coating. Existing metallic powder coatings often suffer from problems such as coating peeling, discoloration, cracking, and scratches after application. These problems are related not only to the preparation of the metallic powder coating but also to its composition.

[0004] Therefore, there is an urgent need for a highly weather-resistant metal powder coating and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a highly weather-resistant metal powder coating and its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention is to provide a highly weather-resistant metallic powder coating, comprising, by weight, the following components:

[0008]

[0009] Preferably, the resin includes at least one of epoxy resin, polyurethane acrylate resin, polyvinyl chloride paste resin, silicone polyester resin, phenolic resin, or amino-modified alkyd resin.

[0010] Preferably, the curing agent comprises at least one of tung oil-modified amine, triethylene glycol isocyanate, triglycidyl pyromellitic acid, dimethylhydantoin, or N-phenylmethyl-1,2-ethylenediamine.

[0011] Preferably, the filler comprises at least one of the following: silicon dioxide, titanium dioxide, manganese dioxide, zirconium dioxide, hydrotalcite, hydroxyapatite, nano boron nitride, nano molybdate, or polyaniline.

[0012] Preferably, the additives include at least one of the following: polyether polyol, modified acrylic emulsion, wax additive, cellulose acetate butyrate, or sodium carboxymethyl cellulose.

[0013] Preferably, the pigment includes at least one of aluminum silver powder, copper gold powder, zinc powder, or pearlescent powder.

[0014] Preferably, the silane coupling agent comprises at least one of γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-aminopropyltriethoxysilane.

[0015] A second aspect of the present invention is to provide a method for preparing the above-mentioned metal powder coating, comprising the steps of:

[0016] S1. Weigh appropriate amounts of resin, curing agent, filler, additives and silane coupling agent, and then perform mixing, melting, extrusion, cooling and crushing processes in sequence to obtain the base powder.

[0017] S2. Weigh an appropriate amount of nitrogen-phosphorus-doped graphene, dissolve it in an organic solvent to prepare a nitrogen-phosphorus-doped graphene dispersion; weigh an appropriate amount of pigment, grind it and place it in the nitrogen-phosphorus-doped graphene dispersion, and perform ultrasonic treatment and drying treatment in sequence to obtain graphene-coated pigment.

[0018] S3. Place the graphene-coated pigment and the substrate powder in a bonding instrument for bonding treatment to obtain the metal powder coating.

[0019] Preferably, in step S1, the melting treatment temperature is 80℃-90℃ and the time is 20min-60min; the extrusion temperature of the extrusion treatment is 90℃-95℃.

[0020] Preferably, the particle size of the base powder is 20μm-70μm.

[0021] Preferably, in step S2, the organic solvent includes at least one of: an aqueous solution of polyvinyl alcohol, an aqueous solution of polyacrylic acid, or an aqueous solution of N-methylpyrrolidone.

[0022] Preferably, in step S3, the bonding process includes: placing the graphene-coated pigment and the substrate powder in a microwave heating container, stirring at a rate of 40 rpm to 50 rpm, and heating at a rate of 4°C / min to 40°C to 50°C for 20 min to 40 min, followed by normal cooling to room temperature.

[0023] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0024] (1) The present invention uses nitrogen and phosphorus doped graphene, which can not only act as a catalyst to catalyze the components, but also effectively improve the adhesion between the metal powder coating and the substrate and the corrosion resistance of the metal powder coating, and can also avoid the problem of uneven metal powder during the coating process.

[0025] (2) The present invention uses a specific preparation process to coat the pigment with nitrogen and phosphorus doped graphene, thereby reducing the contact between the pigment and other materials and air, and thus reducing the discoloration caused by long-term exposure of the pigment to air.

[0026] (3) The present invention uses microwave heating to heat graphene-coated pigments and substrate powders in motion, which has the advantages of high efficiency and high quality compared with existing thermal bonding. Furthermore, the present invention avoids high-speed stirring of graphene-coated pigments, thus ensuring the integrity of graphene-coated pigments. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0029] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0030] Example 1

[0031] This embodiment provides a method for preparing a highly weather-resistant metallic powder coating, the steps of which include:

[0032] S1. Weigh 60 parts of epoxy resin, 22 parts of polyvinyl chloride paste resin, 6 parts of tung oil-modified amine, 30 parts of nano boron nitride, 2 parts of polyether polyol, and 2 parts of γ-aminopropyltriethoxysilane. Then, sequentially perform mixing, melting, extrusion, cooling, and crushing processes to obtain a base powder with a particle size of 20 μm.

[0033] The melting treatment temperature is 90°C and the time is 40 min; the extrusion treatment temperature is 95°C.

[0034] S2. Weigh 20 parts of nitrogen-phosphorus doped graphene and dissolve it in 90wt% polyvinyl alcohol aqueous solution to prepare nitrogen-phosphorus doped graphene dispersion; weigh 15 parts of aluminum silver powder, grind it to a particle size of 10μm and place it in the nitrogen-phosphorus doped graphene dispersion, sonicate it for 30min and then dry it to obtain graphene-coated pigment.

[0035] S3. The graphene-coated pigment and the substrate powder are placed in a bonding instrument for bonding treatment to obtain the metal powder coating; wherein,

[0036] The bonding process includes: placing the graphene-coated pigment and the substrate powder in a microwave heating container, stirring at a rate of 45 rpm, heating to 48°C at a rate of 4°C / min for bonding for 30 minutes, and then cooling to room temperature as usual.

[0037] Example 2

[0038] This embodiment provides another method for preparing a highly weather-resistant metallic powder coating, the steps of which include:

[0039] S1. Weigh 95 parts of polyurethane acrylate resin, 4 parts of triethylene glycol isocyanate, 5 parts of triglycidyl pyromellitic acid, 41 parts of silica, 3 parts of modified acrylic emulsion, 2 parts of sodium carboxymethyl cellulose, and 5 parts of γ-methacryloyloxypropyltrimethoxysilane. After sequentially mixing, melting, extruding, cooling, and crushing, a base powder with a particle size of 20 μm is obtained.

[0040] The melting treatment is performed at a temperature of 80°C for 60 minutes; the extrusion treatment is performed at a temperature of 90°C.

[0041] S2. Weigh 26 parts of nitrogen-phosphorus doped graphene and dissolve it in 90wt% polyvinyl alcohol aqueous solution to prepare nitrogen-phosphorus doped graphene dispersion; weigh 20 parts of pearl powder, grind it to a particle size of 10μm and place it in the nitrogen-phosphorus doped graphene dispersion, sonicate it for 30min and then dry it to obtain graphene-coated pigment.

[0042] S3. The graphene-coated pigment and the substrate powder are placed in a bonding instrument for bonding treatment to obtain the metal powder coating; wherein,

[0043] The bonding process includes: placing the graphene-coated pigment and the substrate powder in a microwave heating container, stirring at a rate of 50 rpm, heating to 42°C at a rate of 6°C / min for 40 min, and then cooling to room temperature as usual.

[0044] Example 3

[0045] This embodiment provides another method for preparing a highly weather-resistant metallic powder coating, the steps of which include:

[0046] S1. Weigh 60 parts of epoxy resin, 30 parts of polyurethane acrylate resin, 7 parts of tung oil-modified amine, 20 parts of zirconium dioxide, 30 parts of hydrotalcite, 3 parts of wax additive, and 1 part of γ-methacryloyloxypropyltrimethoxysilane. Then, sequentially perform mixing, melting, extrusion, cooling, and crushing treatments to obtain a base powder with a particle size of 50 μm.

[0047] The melting treatment temperature is 86°C and the time is 50 min; the extrusion treatment temperature is 82°C.

[0048] S2. Weigh 30 parts of nitrogen-phosphorus doped graphene and dissolve it in 90wt% polyacrylic acid aqueous solution to prepare nitrogen-phosphorus doped graphene dispersion; weigh 8 parts of copper gold powder and 3 parts of pearl powder, grind them and place them in the nitrogen-phosphorus doped graphene dispersion, sonicate for 40 minutes and then dry them to obtain graphene-coated pigment.

[0049] S3. The graphene-coated pigment and the substrate powder are placed in a bonding instrument for bonding treatment to obtain the metal powder coating; wherein,

[0050] The bonding process includes: placing the graphene-coated pigment and the substrate powder in a microwave heating container, stirring at a rate of 40 rpm, heating to 50°C at a rate of 4°C / min for bonding for 40 min, and then cooling to room temperature as usual.

[0051] Example 4

[0052] This embodiment provides another method for preparing a highly weather-resistant metallic powder coating, the steps of which include:

[0053] S1. Weigh 80 parts of epoxy resin, 6 parts of dimethylhydantoin, 30 parts of silica, 2 parts of cellulose acetate butyrate, and 3 parts of γ-glycidyl etheroxypropyltrimethoxysilane. Perform mixing, melting, extrusion, cooling, and crushing treatments sequentially to obtain a base powder with a particle size of 68 μm.

[0054] The melting treatment temperature is 90°C and the time is 20 min; the extrusion treatment temperature is 95°C.

[0055] S2. Weigh 30 parts of nitrogen-phosphorus doped graphene and dissolve it in 90wt% N-methylpyrrolidone aqueous solution to prepare nitrogen-phosphorus doped graphene dispersion; weigh 20 parts of zinc powder, grind it and place it in the nitrogen-phosphorus doped graphene dispersion, sonicate it for 30 minutes and then dry it to obtain graphene-coated pigment.

[0056] S3. The graphene-coated pigment and the substrate powder are placed in a bonding instrument for bonding treatment to obtain the metal powder coating; wherein,

[0057] The bonding process includes: placing the graphene-coated pigment and the substrate powder in a microwave heating chamber, stirring at a rate of 45 rpm, heating to 48°C at a rate of 6°C / min for 26 min, and then cooling to room temperature as usual.

[0058] Comparative Example 1

[0059] This comparative example provides a method for preparing a metal powder coating, the steps of which include:

[0060] Epoxy resin, triglycidyl pyromellitic acid, silica, and polyether polyol were mixed evenly and stirred at 95°C for 3 hours. Then, γ-glycidyl etheroxypropyltrimethoxysilane was added and stirred for another 10 minutes to obtain a mixture. The mixture was melt-extruded, then screened by multi-stage vibration, and aluminum silver powder was added. The mixture was stirred at 800 r / min for another 20 minutes, then the stirring speed was reduced to 200 r / min. After crushing and screening, a metallic powder coating was obtained.

[0061] Comparative Example 2

[0062] This comparative example provides another method for preparing metal powder coatings, the steps of which include:

[0063] Weigh out 45-70% polyester resin, 2-7% triglycidyl isocyanurate, 0.5-2% leveling agent, 1-5% matting agent, 0.1-1.0% degassing agent, and 15-45% filler by weight percentage. Premix, melt extrude, press, pulverize, and sieve the above materials in sequence to prepare powder coating base powder. Weigh out 1-7% pearlescent powder and heat bond it with the powder coating base powder to obtain metallic powder coating.

[0064] Detection Examples

[0065] The metal powder coatings prepared by the methods described in Examples 1-4 and Comparative Examples 1-2 were coated onto carbon steel sheets with a coating thickness of 70 μm. After standing overnight, the performance of the coating film was tested.

[0066] 1. Adhesion test

[0067] The adhesion of the paint film was tested according to standard GB 1727-1992 "General Method for Preparation of Paint Film". The test results are shown in Table 1.

[0068] 2. Impact resistance test

[0069] The impact resistance of the paint film was tested according to the standard GB / T 1732-2020 "Test Method for Impact Resistance of Paint Films", and the test results are shown in Table 1.

[0070] 3. Hardness test

[0071] The hardness of the paint film was tested according to the standard GB / T 6739-2006 "Determination of Hardness of Paint Film by Pencil Method", and the test results are shown in Table 1.

[0072] 4. Corrosion resistance test

[0073] The corrosion resistance of the paint film was tested according to the standard GB / T 23987-2009 "Artificial weathering exposure of paint and varnish coatings to fluorescent ultraviolet light and water". The test results are shown in Table 1.

[0074] 5. Aging test

[0075] The aging test of the paint film was carried out according to the standard GB / T1865-2009 "Artificial climate aging and artificial irradiation exposure to filtered xenon arc radiation for paints and varnishes". The test results are shown in Table 1.

[0076] Table 1

[0077] Adhesion / Grade Impact resistance / cm Coating hardness gloss Weight change / g Example 1 5 45 4H >90 degrees 0.002 Example 2 4 49 4H >90 degrees 0.001 Example 3 5 42 4H >90 degrees 0.002 Example 4 3 44 4H >90 degrees 0.002 Comparative Example 1 1 21 1H 75 degrees 0.011 Comparative Example 2 2 15 2H 56 degrees 0.019

[0078] As shown in Table 1, the adhesion, impact resistance, coating hardness, gloss, and aging resistance of the metal powder coating prepared by this invention after curing are significantly better than those of existing technologies. This demonstrates that the present invention, by adding nitrogen-phosphorus doped graphene and optimizing the preparation process, has obtained a metal powder coating with excellent weather resistance.

[0079] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A method for preparing a highly weather-resistant metallic powder coating, characterized in that the steps include... include: S1. Weigh appropriate amounts of resin, curing agent, filler, additives and silane coupling agent, and then perform mixing, melting, extrusion, cooling and crushing processes in sequence to obtain the base powder. S2. Weigh an appropriate amount of nitrogen-phosphorus-doped graphene, dissolve it in an organic solvent to prepare a nitrogen-phosphorus-doped graphene dispersion; weigh an appropriate amount of pigment, grind it and place it in the nitrogen-phosphorus-doped graphene dispersion, and perform ultrasonic treatment and drying treatment in sequence to obtain graphene-coated pigment. S3. Place the graphene-coated pigment and the substrate powder in a bonding instrument for bonding treatment to obtain the metal powder coating; the bonding treatment includes: placing the graphene-coated pigment and the substrate powder in a microwave heating chamber, stirring at a rate of 40 rpm-50 rpm, heating at a rate of 4℃ / min-8℃ / min to 40℃-50℃ for bonding for 20 min-40 min, and then cooling to room temperature as usual; The metal powder coating comprises, by weight, the following components: 80-100 parts of resin; 5-9 parts of curing agent; 30-50 parts of filler; 1-5 parts of auxiliary agent; 10-20 parts pigment; 1-5 parts of silane coupling agent; 20-30 parts of nitrogen-phosphorus doped graphene.

2. The preparation method according to claim 1, characterized in that, The resin includes at least one of the following: epoxy resin, polyurethane acrylate resin, polyvinyl chloride paste resin, silicone polyester resin, phenolic resin, or amino-modified alkyd resin.

3. The preparation method according to claim 1, characterized in that, The curing agent includes at least one of the following: tung oil-modified amine, triethylene glycol isocyanate, triglycidyl pyromellitic acid, dimethylhydantoin, or N-phenylmethyl-1,2-ethylenediamine.

4. The preparation method according to claim 1, characterized in that, The filler includes at least one of the following: silicon dioxide, titanium dioxide, manganese dioxide, zirconium dioxide, hydrotalcite, hydroxyapatite, nano boron nitride, nano molybdate, or polyaniline.

5. The preparation method according to claim 1, characterized in that, The additives include at least one of the following: polyether polyol, modified acrylic emulsion, wax additive, cellulose acetate butyrate, or sodium carboxymethyl cellulose.

6. The preparation method according to claim 1, characterized in that, The pigments include at least one of aluminum silver powder, copper gold powder, zinc powder, or pearlescent powder.

7. The preparation method according to claim 1, characterized in that, In step S1, the melting treatment temperature is 80℃-90℃ and the time is 20min-60min; the extrusion temperature of the extrusion treatment is 90℃-95℃.

8. The preparation method according to claim 1, characterized in that, In step S2, the organic solvent includes at least one of: an aqueous solution of polyvinyl alcohol, an aqueous solution of polyacrylic acid, or an aqueous solution of N-methylpyrrolidone.

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