Polyurethane paint with good weather resistance and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a preparation method of polyurethane paint with good weather fastness, which comprises the following raw materials in parts by weight: 40-60 parts of main resin, 5-15 parts of first powder, 3-10 parts of second powder, 10-20 parts of solvent and 1-3 parts of additive. In the preparation method, the first powder is subjected to carbonization and silane treatment, active groups formed on the surface of the first powder can be chemically crosslinked with main resin to form a molecular bridge to tightly connect inorganic particles with organic resin, and a firm interface bonding layer is formed, just like a plurality of small hooks are added between polyurethane paint and a steel plate to enable the polyurethane paint and the steel plate to be tightly connected; the binding force between the polyurethane paint and a base material can be enhanced, so that the polyurethane paint can be firmly attached in different temperature environments, and the weather resistance of the paint is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly to a polyurethane paint with good weather resistance and a preparation method thereof. Background Art

[0002] Polyurethane paint is a coating with polyurethane resin as the main film-forming substance, usually formed by cross-linking and curing a proportionate mixture of isocyanate components and polyol components. Its paint film is tough, wear-resistant, chemically corrosion-resistant, has strong adhesion and full luster, and has excellent weather resistance and mechanical properties, and can adapt to different substrates by adjusting the formula.

[0003] When existing polyurethane paints are combined with substrates, due to the lack of effective chemical connection between inorganic particles and organic resins, the interfacial bonding force is insufficient. Under the influence of environmental factors such as temperature changes, the paint film is prone to problems such as peeling and falling off, seriously affecting its weather resistance.

[0004] Based on this, the present invention provides a polyurethane paint with good weather resistance and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a polyurethane paint with good weather resistance and a preparation method thereof to solve the problems raised in the background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A preparation method of a polyurethane paint with good weather resistance, comprising the following raw materials in parts by weight: 40 - 60 parts of main resin, 5 - 15 parts of first powder, 3 - 10 parts of second powder, 10 - 20 parts of solvent, and 1 - 3 parts of additive.

[0007] Preferably, the preparation method of the polyurethane paint with good weather resistance comprises the following steps: S1: Put the first powder, second powder, additive and solvent into a disperser, set the rotation speed at 2000 - 3000 r / min, and continuously stir for 30 - 50 min to obtain a mixed slurry; S2: Put the main resin into a reaction kettle, then add ethyl acetate accounting for 30 - 60% of the mass of the main resin, set the temperature at 60 - 70 °C, the rotation speed at 200 - 300 r / min, and continuously stir for 1 h; S3: Add the mixed slurry into the reaction kettle in S2, set the rotation speed at 800 - 900 r / min, and continue to stir for 2 - 3 h to obtain a paint; S4: Transfer the paint to a ripening tank, set the temperature at 40 - 50 °C, let it stand for 24 h, and then pass it through a filter with a pore size of 10 - 15 μm, and take the filtrate, which is the polyurethane paint with good weather resistance.

[0008] Preferably, the preparation method of the first powder comprises the following steps: Step 1: Select plant waste as raw material, crush and grind it to 0.5 - 1.5 mm to obtain crushed material; Step 2: Put the crushed material into a carbonization furnace, heat it up to 500 - 800 °C at a heating rate of 10 °C / min under nitrogen protection, keep it for 2 - 4 h, then take it out and let it cool naturally at room temperature to obtain carbonized material; Step 3: Add the carbonized material to a ball mill, set the rotation speed at 400 - 500 r / min, grind for 4 - 5 h, and then pass through a sieve to obtain primary first powder with a particle size of 50 - 200 nm; Step 4: Add the primary first powder to a blender, then add silane coupling agent KH - 550 accounting for 2 - 3% of the mass of the primary first powder, set the rotation speed at 200 - 300 r / min, temperature at 60 - 70 °C, continuously stir for 1 - 2 h, then transfer it to a drying oven and dry it at 80 - 90 °C for 2 - 3 h, and then grind to obtain the first powder.

[0009] Preferably, the preparation method of the second powder includes the following steps: Step 1: Pass industrial flue gas into a spray tower, spray the industrial flue gas with a 10% sodium hydroxide solution by mass fraction to obtain a mixed solution, then filter the mixed solution and take the precipitate; Step 2: Mix the precipitate with 5% dilute hydrochloric acid by mass fraction according to a solid - liquid ratio of 1:(5 - 7), then add it to a reaction kettle, set the rotation speed at 150 - 200 r / min, continuously stir for 30 - 50 min, then transfer it to a centrifuge, set the rotation speed at 3000 - 4000 r / min, and continuously separate for 30 - 50 min to obtain a solid separation; Step 3: Transfer the solid separation to a drying oven and dry it at 100 - 120 °C for 3 - 4 h to obtain primary functional powder; Step 4: Transfer the primary functional powder to a calcination furnace, heat it at a heating rate of 10 - 15 °C / min to 500 - 600 °C, calcine for 2 - 3 h, and then cool it at room temperature to obtain the second powder.

[0010] Preferably, the main resin is composed of isocyanate and polyol, and the mass ratio of isocyanate to polyol is 1:1.

[0011] Preferably, the preparation method of the main resin includes the following steps: Add isocyanate and polyol to a reaction kettle, and continuously stir at 200 - 300 r / min and 60 - 70 °C for 1 - 3 h to obtain the main resin.

[0012] Preferably, the solvent can be selected from at least one of butyl acetate and propylene glycol methyl ether acetate, and the additive is made by mixing a leveling agent, a dispersant and an ultraviolet absorber according to a mass ratio of 1:1:1.

[0013] Preferably, the leveling agent can be at least one of isophorone and diacetone alcohol, the dispersant can be at least one of polyacrylamide and methyl amyl alcohol, and the ultraviolet absorber can be at least one of UV-531 and UV-327.

[0014] Preferably, the plant waste can be any one of coffee grounds, rice husks and straw.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this preparation method, the first powder is treated by carbonization and silanization, and the active groups formed on its surface can chemically crosslink with the main resin, forming a "molecular bridge" to tightly connect the inorganic particles and the organic resin, forming a firm interfacial bonding layer. It's like adding many "small hooks" between the polyurethane paint and the steel plate to make them tightly connected, which can enhance the bonding force between the polyurethane paint and the substrate, enable the polyurethane paint to firmly adhere under different temperature environments, and improve the weather resistance of the paint.

[0016] 2. In this preparation method, the second powder is treated by industrial flue gas treatment and calcination to form components with a dense crystal structure. These rigid particles are evenly distributed in the paint film to form a "skeleton support" to maintain the spatial structure of the paint film. When the resin matrix absorbs water and swells in a humid and hot environment, the rigid structure of the second powder can effectively resist deformation, keep the hardness of the paint film stable, and resist the influence brought by the humid and hot environment, enabling the polyurethane paint to maintain good performance in humid and high-temperature places.

[0017] 3. In this preparation method, the first powder and the second powder have a synergistic effect. The porous structure of the first powder increases the pigment dispersion area and reduces the light absorption concentration point. The crystal structure of the second powder has a scattering and reflection effect on ultraviolet rays, improving the ability of the polyurethane paint to resist ultraviolet rays and maintaining the stability and weather resistance of the polyurethane paint. Specific embodiments

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] Example 1, this example provides a preparation method of a polyurethane paint with good weather resistance, including the following raw materials in parts by weight: 40 parts of main resin, 5 parts of first powder, 3 parts of second powder, 10 parts of solvent, and 1 part of additive.

[0020] Among them, the preparation method of the polyurethane paint with good weather resistance includes the following steps: S1: Put the first powder material, the second powder material, the additive and the solvent into a disperser, set the rotation speed at 2000 r / min, and continuously stir for 30 min to obtain a mixed slurry. S2: Add the main resin into a reaction kettle, then add ethyl acetate accounting for 30% of the mass of the main resin, set the temperature at 60 °C, the rotation speed at 200 r / min, and continuously stir for 1 h. S3: Add the mixed slurry into the reaction kettle of S2, set the rotation speed at 800 r / min, and continue to stir for 2 h to obtain a paint material. S4: Transfer the paint material to a ripening tank, set the temperature at 40 °C, let it stand for 24 h, then pass it through a filter with a pore size of 10 μm, and take the filtrate, which is the polyurethane paint with good weather resistance.

[0021] Among them, the preparation method of the first powder material includes the following steps: Step 1: Select plant waste as the raw material, crush and break it to 0.5 mm to obtain a crushed material. Step 2: Put the crushed material into a carbonization furnace, heat it to 500 °C at a heating rate of 10 °C / min under nitrogen protection, keep it for 2 h, then take it out and let it cool naturally at room temperature to obtain a carbonized material. Step 3: Add the carbonized material into a ball mill, set the rotation speed at 400 r / min, grind for 4 h, and then sieve to obtain a primary first powder material with a particle size of 50 nm. Step 4: Add the primary first powder material into a mixer, then add silane coupling agent KH-550 accounting for 2% of the mass of the primary first powder material, set the rotation speed at 200 r / min, the temperature at 60 °C, continuously stir for 1 h, then transfer it to a drying oven and dry it at 80 °C for 2 h, and then grind to obtain the first powder material.

[0022] Among them, the preparation method of the second powder material includes the following steps: Step 1: Pass industrial flue gas into a spray tower, spray the industrial flue gas with a 10% sodium hydroxide solution by mass fraction to obtain a mixed solution, then filter the mixed solution and take the precipitate. Step 2: Mix the precipitate with dilute hydrochloric acid with a mass fraction of 5% at a solid-liquid ratio of 1:5, then add it into a reaction kettle, set the rotation speed at 150 r / min, continuously stir for 30 min, then transfer it to a centrifuge, set the rotation speed at 3000 r / min, and continuously separate for 30 min to obtain a solid separation. Step 3: Transfer the solid separation to a drying oven and dry it at 100 °C for 3 h to obtain a primary functional powder. Step 4: Transfer the primary functional powder to a calcination furnace, heat it to 500 °C at a heating rate of 10 °C / min, calcine for 2 h, and then cool it at room temperature to obtain the second powder material.

[0023] Among them, the main resin is composed of isocyanate and polyol, and the mass ratio of isocyanate to polyol is 1:1.

[0024] Among them, the preparation method of the main resin includes the following steps: Add isocyanate and polyol into a reaction kettle, and continuously stir at 200 r / min and 60 °C for 1 h to obtain the main resin.

[0025] Among them, butyl acetate is selected as the solvent, and the additive is made by mixing a leveling agent, a dispersant and an ultraviolet absorber in a mass ratio of 1:1:1.

[0026] Among them, isophorone is selected as the leveling agent, polyacrylamide is selected as the dispersant, and UV-531 is selected as the ultraviolet absorber.

[0027] Among them, coffee grounds are selected as the plant waste.

[0028] Example 2, a preparation method of a polyurethane paint with good weather resistance, includes the following raw materials in parts by weight: 60 parts of main resin, 15 parts of the first powder, 10 parts of the second powder, 20 parts of solvent, and 3 parts of additive.

[0029] Among them, the preparation method of the polyurethane paint with good weather resistance includes the following steps: S1: Put the first powder, the second powder, the additive and the solvent into a disperser, set the rotation speed at 3000 r / min, and continuously stir for 50 min to obtain a mixed slurry; S2: Add the main resin into a reaction kettle, and then add ethyl acetate accounting for 60% of the mass of the main resin, set the temperature at 70 °C, the rotation speed at 300 r / min, and continuously stir for 1 h; S3: Add the mixed slurry into the reaction kettle in S2, set the rotation speed at 900 r / min, and continue to stir for 3 h to obtain a paint; S4: Transfer the paint to a curing tank, set the temperature at 50 °C, let it stand for 24 h, and then pass through a filter with a pore size of 15 μm, and take the filtrate, which is the polyurethane paint with good weather resistance.

[0030] Among them, the preparation method of the first powder includes the following steps: Step 1: Select plant waste as the raw material, crush and break it to 1.5 mm to obtain a crushed material; Step 2: Put the crushed material into a carbonization furnace, heat it up to 800 °C at a heating rate of 10 °C / min under nitrogen protection, keep it for 4 h, and then take it out and let it cool naturally at room temperature to obtain a carbonized material; Step 3: Add the carbonized material into a ball mill, set the rotation speed at 500 r / min, grind for 5 h, and then pass through a sieve to obtain a primary first powder with a particle size of 200 nm; Step 4: Add the primary first powder into a blender, and then add silane coupling agent KH-550 accounting for 3% of the mass of the primary first powder. Set the rotation speed at 300 r / min and the temperature at 70 °C, and continuously stir for 2 h. Then transfer it to a drying oven and dry it at 90 °C for 3 h, and then grind it to obtain the first powder.

[0031] Among them, the preparation method of the second powder includes the following steps: Step 1: Pass the industrial flue gas into a spray tower, spray the industrial flue gas with a 10% sodium hydroxide solution by mass fraction to obtain a mixed solution, and then filter the mixed solution to obtain the precipitate. Step 2: Mix the precipitate with dilute hydrochloric acid with a mass fraction of 5% according to a solid-liquid ratio of 1:7, then add it to a reaction kettle, set the rotation speed at 200 r / min, continuously stir for 50 min, and then transfer it to a centrifuge, set the rotation speed at 4000 r / min, and continuously separate for 50 min to obtain a solid separation. Step 3: Transfer the solid separation to a drying oven and dry it at 120 °C for 4 h to obtain the primary functional powder. Step 4: Transfer the primary functional powder to a calcination furnace, heat it to 600 °C at a heating rate of 15 °C / min, calcine for 3 h, and then cool it to room temperature to obtain the second powder.

[0032] Among them, the main resin is composed of isocyanate and polyol, and the mass ratio of isocyanate to polyol is 1:1.

[0033] Among them, the preparation method of the main resin includes the following steps: Add isocyanate and polyol to a reaction kettle, and continuously stir at 300 r / min and 70 °C for 3 h to obtain the main resin.

[0034] Among them, the solvent can be selected as propylene glycol methyl ether acetate, and the additive is made by mixing a leveling agent, a dispersant, and an ultraviolet absorber according to a mass ratio of 1:1:1.

[0035] Among them, the leveling agent is selected as diacetone alcohol, the dispersant is selected as methyl amyl alcohol, and the ultraviolet absorber is selected as UV-327.

[0036] Among them, the plant waste is selected as straw.

[0037] Example 3, a preparation method of a polyurethane paint with good weather resistance, includes the following raw materials in parts by weight: 50 parts of main resin, 10 parts of the first powder, 7 parts of the second powder, 15 parts of solvent, and 2 parts of additive.

[0038] Among them, the preparation method of the polyurethane paint with good weather resistance includes the following steps: S1: Put the first powder, the second powder, the additive, and the solvent into a disperser, set the rotation speed at 2500 r / min, and continuously stir for 40 min to obtain a mixed slurry. S2: Add the main resin into the reaction kettle, then add ethyl acetate accounting for 45% of the mass of the main resin, set the temperature at 65°C, the rotation speed at 250 r / min, and continuously stir for 1 h; S3: Add the mixed slurry into the reaction kettle in S2, set the rotation speed at 850 r / min, and continue to stir for 2.5 h to obtain the paint; S4: Transfer the paint to the aging tank, set the temperature at 45°C, let it stand for 24 h, then pass it through a filter with a pore size of 12 μm, and take the filtrate, which is the polyurethane paint with good weather resistance.

[0039] Among them, the preparation method of the first powder includes the following steps: Step 1: Select plant waste as the raw material, crush and break it to 1 mm to obtain the crushed material; Step 2: Put the crushed material into the carbonization furnace, heat it up to 650°C at a heating rate of 10°C / min under nitrogen protection, keep it for 3 h, then take it out and let it cool naturally at room temperature to obtain the carbonized material; Step 3: Add the carbonized material into the ball mill, set the rotation speed at 450 r / min, grind for 4.5 h, and then screen to obtain the primary first powder with a particle size of 100 nm; Step 4: Add the primary first powder into the blender, then add silane coupling agent KH-550 accounting for 2.5% of the mass of the primary first powder, set the rotation speed at 250 r / min, the temperature at 65°C, continuously stir for 1.5 h, then transfer it to the drying oven and dry it at 85°C for 2.5 h, and then grind to obtain the first powder.

[0040] Among them, the preparation method of the second powder includes the following steps: Step 1: Pass the industrial flue gas into the spray tower, spray the industrial flue gas with a 10% sodium hydroxide solution by mass fraction to obtain a mixed solution, and then filter the mixed solution to take the precipitate; Step 2: Mix the precipitate with dilute hydrochloric acid with a mass fraction of 5% at a solid-liquid ratio of 1:6, then add it into the reaction kettle, set the rotation speed at 180 r / min, continuously stir for 40 min, then transfer it to the centrifuge, set the rotation speed at 3500 r / min, and continuously separate for 40 min to obtain the solid separation; Step 3: Transfer the solid separation to the drying oven and dry it at 110°C for 3.5 h to obtain the primary functional powder; Step 4: Transfer the primary functional powder to the calcination furnace, heat it up to 550°C at a heating rate of 12°C / min, calcine for 2.5 h, and then cool it at room temperature to obtain the second powder.

[0041] Among them, the main resin is composed of isocyanate and polyol, and the mass ratio of isocyanate to polyol is 1:1.

[0042] Among them, the preparation method of the main resin includes the following steps: adding isocyanate and polyol into a reaction kettle, and continuously stirring for 2 h at 250 r / min and 65 °C to obtain the main resin.

[0043] Among them, butyl acetate is selected as the solvent, and the additive is made by mixing a leveling agent, a dispersant, and an ultraviolet absorber in a mass ratio of 1:1:1.

[0044] Among them, isophorone is selected as the leveling agent, methyl pentanol is selected as the dispersant, and UV-327 is selected as the ultraviolet absorber.

[0045] Among them, rice husk is selected as the plant waste.

[0046] Comparative Example 1: The difference between this comparative example and Examples 1-3 is that: in the process of preparing the polyurethane paint with good weather resistance in this comparative example, the first powder material is not added.

[0047] Comparative Example 2: The difference between this comparative example and Examples 1-3 is that: in the process of preparing the polyurethane paint with good weather resistance in this comparative example, the second powder material is not added.

[0048] Comparative Example 3: The difference between this comparative example and Examples 1-3 is that: in the process of preparing the polyurethane paint with good weather resistance in this comparative example, traditional calcium carbonate filler is used to replace the first powder material and the second powder material.

[0049] After preparing the polyurethane paint according to the preparation methods of Examples 1-3 and Comparative Examples 1-3, apply it on a standard steel plate to form a paint sample, and conduct performance tests on it; Ultraviolet aging test: Place the paint sample in an ultraviolet aging chamber, irradiate it at a wavelength of 280-400 nm and an intensity of 50 W / ㎡ for 7-10 days, and observe the degree of color change of the paint sample after the test and record the results in the following table. The results are divided into 1-10, where 1 is the best and 10 is the worst; Damp heat aging test: Place the paint sample in an environment of 50 °C and 95% humidity for 72 hours, then draw on the surface of the paint sample with a pencil, and judge the change in the hardness of the paint sample by the pencil hardness that can leave scratches and record the pencil hardness in the following table; Cold and hot cycle adhesion test: Cycle the paint sample 10 times between -20 °C and 60 °C, with each cycle lasting 2 hours. Then, use the cross-cut method to detect the adhesion degree between the paint sample and the steel plate, and record the results in the following table;

[0050] It can be seen from the comparison of the data in the table that the adhesion of Comparative Example 1 reached level 4 after thermal cycling, while Examples 1-3 remained stable at level 1. This is because after the first powder was carbonized and treated with silane, reactive groups formed on its surface can chemically crosslink with the main resin. Just like a "molecular bridge", it tightly connects the inorganic particles and the organic resin, forming a firm interfacial bonding layer. It's like adding many "small hooks" between the paint sample and the steel plate, making them stick together tightly, which can enhance the bonding force between the paint sample and the substrate, enabling the paint to adhere firmly under different temperature environments and improving the weather resistance of the paint. Without the first powder, the connection between the paint sample and the steel plate becomes very fragile, and the forces generated by thermal cycling are easily able to separate them. It can be seen from the comparison of the data in the table that after exposure to a damp and hot environment, the hardness of Comparative Example 2 was 3B, while Examples 1-3 remained at 4H. This is because the second powder was treated with industrial flue gas and calcined to form components with a dense crystal structure. These rigid particles are evenly distributed in the paint film, acting like a "skeleton support" to maintain the spatial structure of the paint film. When the resin matrix absorbs water and swells due to the damp and hot environment, the rigid structure of the second powder can effectively resist deformation, keeping the hardness of the paint film stable and resisting the influence of the damp and hot environment, enabling the paint to maintain good performance in humid and high-temperature places. Without the second powder, the resin matrix lacks support, the molecular chain spacing increases after absorbing water, the flexibility decreases, and the hardness is significantly reduced, resulting in the paint sample being easily softened and deformed in the damp and hot environment.

[0051] It can be seen from the comparison of the data in the table that after ultraviolet irradiation, the color difference of Comparative Example 3 reached 8, while Examples 1-3 remained at 1-1.5. This is because the surface of traditional calcium carbonate filler is smooth and lacks light protection function, unable to effectively disperse or absorb ultraviolet energy, resulting in the light energy directly acting on the resin molecular chain and triggering an oxidative cleavage reaction. However, the first powder and the second powder have a synergistic effect. The porous structure of the first powder increases the pigment dispersion area and reduces the light absorption concentration points. The crystal structure of the second powder has a scattering and reflection effect on ultraviolet rays. At the same time, the surface energy after silane treatment can form a "capture-dissipation" system with the ultraviolet absorber, converting light energy into harmless heat energy, improving the ability of the paint sample to resist ultraviolet rays, maintaining the color stability of the paint, and enhancing the weather resistance of the paint.

[0052] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0053] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A preparation method of a polyurethane paint with good weather resistance, characterized in that, It includes the following raw materials in parts by weight: 40 - 60 parts of main resin, 5 - 15 parts of first powder, 3 - 10 parts of second powder, 10 - 20 parts of solvent, and 1 - 3 parts of additive.

2. The preparation method of the polyurethane paint with good weather resistance according to claim 1, characterized in that, The preparation method of the polyurethane paint with good weather resistance includes the following steps: S1: Put the first powder, second powder, additive and solvent into a disperser, set the rotation speed at 2000 - 3000 r / min, and continuously stir for 30 - 50 min to obtain a mixed slurry; S2: Add the main resin into a reaction kettle, then add ethyl acetate accounting for 30 - 60% of the mass of the main resin, set the temperature at 60 - 70 °C, the rotation speed at 200 - 300 r / min, and continuously stir for 1 h; S3: Add the mixed slurry into the reaction kettle in S2, set the rotation speed at 800 - 900 r / min, and continue to stir for 2 - 3 h to obtain paint; S4: Transfer the paint to a curing tank, set the temperature at 40 - 50 °C, let it stand for 24 h, and then pass it through a filter with a pore size of 10 - 15 μm, and take the filtrate, which is the polyurethane paint with good weather resistance.

3. The preparation method of the polyurethane paint with good weather resistance according to claim 1, characterized in that, The preparation method of the first powder includes the following steps: Step 1: Select plant waste as the raw material, crush and break it to 0.5 - 1.5 mm to obtain a crushed material; Step 2: Put the crushed material into a carbonization furnace, heat it up to 500 - 800 °C at a heating rate of 10 °C / min under nitrogen protection, keep it for 2 - 4 h, then take it out and let it cool naturally at room temperature to obtain a carbonized material; Step 3: Add the carbonized material into a ball mill, set the rotation speed at 400 - 500 r / min, grind for 4 - 5 h, and then sieve to obtain a primary first powder with a particle size of 50 - 200 nm; Step 4: Add the primary first powder into a mixer, then add 2 - 3% of silane coupling agent KH - 550 based on the mass of the primary first powder, set the rotation speed at 200 - 300 r / min, the temperature at 60 - 70 °C, continuously stir for 1 - 2 h, then transfer it to a drying oven and dry it at 80 - 90 °C for 2 - 3 h, and then grind to obtain the first powder.

4. The preparation method of the polyurethane paint with good weather resistance according to claim 1, characterized in that, The preparation method of the second powder includes the following steps: Step 1: Pass industrial flue gas into a spray tower, spray the industrial flue gas with a 10% sodium hydroxide solution by mass fraction to obtain a mixed solution, and then filter the mixed solution to take the precipitate; Step 2: Mix the precipitate with 5% dilute hydrochloric acid by mass fraction according to a solid - liquid ratio of 1:(5 - 7), then add it into a reaction kettle, set the rotation speed at 150 - 200 r / min, continuously stir for 30 - 50 min, and then transfer it to a centrifuge, set the rotation speed at 3000 - 4000 r / min, and continuously separate for 30 - 50 min to obtain a solid separation; Step 3: Transfer the solid separation to a drying oven and dry it at 100 - 120 °C for 3 - 4 h to obtain a primary functional powder; Step 4: Transfer the primary functional powder to a calcination furnace, heat it at a heating rate of 10 - 15 °C / min to 500 - 600 °C, calcine for 2 - 3 h, and then cool it at room temperature to obtain the second powder.

5. The preparation method of the polyurethane paint with good weather resistance according to claim 1, characterized in that, The main resin is composed of isocyanate and polyol, and the mass ratio of isocyanate to polyol is 1:

1.

6. The preparation method of the polyurethane paint with good weather resistance according to claim 1, characterized in that, The method for preparing the main resin comprises the following steps: adding isocyanate and polyol into a reaction kettle, and continuously stirring at 200-300 r / min and 60-70 °C for 1-3 h to obtain the main resin.

7. The preparation method of the polyurethane paint with good weather resistance according to claim 1, characterized in that, The solvent can be selected from at least one of butyl acetate and propylene glycol methyl ether acetate, and the additive is made by mixing a leveling agent, a dispersant and an ultraviolet absorber in a mass ratio of 1:1:

1.

8. The preparation method of the polyurethane paint with good weather resistance according to claim 7, characterized in that, The leveling agent can be selected from at least one of isophorone and diacetone alcohol, the dispersant can be selected from at least one of polyacrylamide and methyl amyl alcohol, and the ultraviolet absorber can be selected from at least one of UV-531 and UV-327.

9. The preparation method of the polyurethane paint with good weather resistance according to claim 3, characterized in that, The plant waste can be selected from any one of coffee grounds, rice husks and straws.

10. A polyurethane paint with good weather resistance, characterized in that, It is prepared by the method for preparing the polyurethane paint with good weather resistance according to any one of claims 1 to 9.

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