High-weather-resistance polyurethane paint

Abstract

The invention relates to high-weather-resistance polyurethane paint, and belongs to the technical field of environment-friendly paint. The high-weather-resistance polyurethane paint is prepared by taking super-weather-resistance polyester resin, pigment, nano silicon dioxide, high-toughness polyester resin, blocked isocyanate, an auxiliary agent, a composite functional agent and an environment-friendly solvent as raw materials. Compared with the prior art, the high-weather-resistance polyurethane paint is lower in cost, environmentally friendly and higher in preparation efficiency, nano silicon dioxide used in the preparation method can effectively improve the smoothness of a formed paint film, the prepared paint surface is attractive and smooth, and the high-weather-resistance polyurethane paint is high in weather resistance and good in weather resistance. The polyurethane primer provided by the invention has good ultraviolet resistance and oxidation resistance, good weather resistance and flame retardant property, and the flame retardant time is far away from that of other primers sold in supermarkets.

Description

Technical Field

[0001] The invention belongs to the technical field of environmentally friendly coatings, and in particular relates to a highly weather-resistant polyurethane paint. Background Art

[0002] In the existing fluorocarbon printed thick plate coil production process, a four-stage coating and baking curing process is mostly used, including polyurethane primer, PVDF fluorocarbon paint, overprinting and final PVDF fluorocarbon varnish. This process is not only costly, but also has great limitations in terms of environmental protection, resource utilization efficiency and production efficiency. Among them, the performance of polyurethane primer as the basis of the coating system has a decisive influence on the weather resistance, processing performance and appearance of the final product. However, due to its high material cost and strict construction process requirements, PVDF fluorocarbon paint leads to high overall process costs.

[0003] In addition, due to its organic structure, traditional polyurethane primers are easily affected by oxidation and aging and degeneration due to ultraviolet light, resulting in color changes that affect the appearance. In the prior art, ultraviolet absorbers and antioxidants are often added thereto. However, the small molecular structure of such additives themselves is easy to fall off after long-term use, and excessive additives will affect the performance of the primer itself. Summary of the invention

[0004] The object of the present invention is to provide a highly weather-resistant polyurethane paint to solve the problems mentioned in the above background technology.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A highly weather-resistant polyurethane paint, comprising the following raw materials in parts by weight: 40-45 parts of super-weather-resistant polyester resin, 8-20 parts of pigment, 2-3 parts of nano-silicon dioxide, 10-12 parts of high-toughness polyester resin, 8-10 parts of blocked isocyanate, 2-3 parts of additives, 2-3 parts of composite functional agents, and 15-20 parts of environmentally friendly solvents; A highly weather-resistant polyurethane paint, the preparation method of which comprises the following steps: Step 1: Weigh each raw material by mass and divide the environmentally friendly solvent into three equal parts; Step 2: Grind the pigment to a particle size of less than 10 μm, dissolve it in two portions of an environmentally friendly solvent, add super weather-resistant polyester resin, high-toughness polyester resin, and additives to the environmentally friendly solvent, and stir thoroughly to obtain liquid A; Step 3: dissolve the composite functional agent in an environmentally friendly solvent, add nano-silicon dioxide and blocked isocyanate to the environmentally friendly solvent, and stir thoroughly to obtain liquid B; Step 4: Add liquid B to liquid A, mix evenly and adjust the color to produce a highly weather-resistant polyurethane paint.

[0006] Furthermore, in the second step, the stirring speed condition is 1000-1200 r / min, and the stirring speed condition is 40-60 min.

[0007] Furthermore, in the third step, the stirring speed condition is 1500-1800 r / min, and the stirring speed condition is 30-40 min.

[0008] Furthermore, the super weather-resistant polyester resin is polycaprolactone diol.

[0009] Furthermore, the pigment is one of a ceramic pigment and a metal pigment, and when the pigment used is a metal pigment, grinding is not required during preparation.

[0010] Furthermore, the high-toughness polyester resin is an alkyd resin with an oil content of less than 50%.

[0011] Furthermore, the blocked isocyanate is isophorone diisocyanate.

[0012] Furthermore, the auxiliary agent is pentaerythritol.

[0013] Furthermore, the environmentally friendly solvent is one of propylene glycol methyl ether acetate and nylon acid methyl ester.

[0014] Furthermore, the composite functional agent is prepared by the following steps: Step 1: Mix 3,5-di-tert-butyl-4-hydroxybenzoic acid, thionyl chloride and chloroform in a three-necked flask, install a condenser and a thermometer, start magnetic stirring, and react at a temperature of 60-80°C for 3-4h. After the reaction is completed, rotary evaporation is performed to obtain intermediate 1; Step 2: Mix pyrogallol, phosphorus oxychloride, aluminum chloride and N-methylpyrrolidone in a three-necked flask, install a condenser and a thermometer, start magnetic stirring, and react at a temperature of 70-90°C for 6-8h. After the reaction is completed, rotary evaporation is performed to obtain intermediate 2; Step 3: Mix intermediate 1, intermediate 2 and tetrahydrofuran in a stainless steel reactor, install a condenser and a thermometer, turn on magnetic stirring, react at 60°C for 3h, then add aluminum chloride to the stainless steel reactor, and react at 140-160°C for 6-8h. After the reaction, add deionized water to the stainless steel reactor for washing, separate the organic layer of the obtained product with a separatory funnel, and rotary evaporate to obtain intermediate 3; Step 4: Mix the intermediate 3, aminopropyltriethoxysilane, triethylamine and N-methylpyrrolidone in a three-necked flask, install a condenser and a thermometer, start magnetic stirring, and react at a temperature of 110-120°C for 10-12h. After the reaction is completed, rotary evaporate to obtain the composite functional agent.

[0015] Furthermore, the amount ratio of 3,5-di-tert-butyl-4-hydroxybenzoic acid, thionyl chloride and chloroform used in step 1 is 0.1 mol: 0.08-0.1 mol: 40-60 mL.

[0016] Furthermore, the dosage ratio of pyrogallol, phosphorus oxychloride, aluminum chloride and N-methylpyrrolidone used in step 2 is 0.1 mol: 0.1 mol: 3-4 g: 30-40 mL.

[0017] Furthermore, the usage ratio of intermediate 1, intermediate 2, tetrahydrofuran and aluminum chloride used in step 3 is: 0.08 mol: 0.08 mol: 60-80 mL: 16-24 g.

[0018] Furthermore, the usage ratio of intermediate 3, aminopropyltriethoxysilane, triethylamine and N-methylpyrrolidone used in step 4 is 0.05 mol: 0.05-0.06 mol: 0.06-0.08 mol: 60-80 mL.

[0019] Beneficial effects of the present invention: 1) The present invention uses super weather-resistant polyester resin, pigment, nano silicon dioxide, high-toughness polyester resin, blocked isocyanate, additives, composite functional agent and environmentally friendly solvent as raw materials to prepare a high weather-resistant polyurethane paint; the present invention grinds and crushes the pigment, dissolves it with super weather-resistant polyester resin, high-toughness polyester resin and additives in an environmentally friendly solvent, and then fully stirs and disperses it to obtain liquid A; then the composite functional agent, nano silicon dioxide and blocked isocyanate are dissolved in an environmentally friendly solvent, and then fully stirs and disperses it to obtain liquid B; finally, liquid B is added to liquid A to adjust the color to obtain a high weather-resistant polyurethane paint. Compared with the prior art, the high weather-resistant polyurethane paint of the present invention has lower cost, is environmentally friendly and has higher preparation efficiency. The nano silicon dioxide added to the polyurethane paint of the present invention in its preparation process can effectively improve the smoothness of the paint film after forming, and the obtained paint surface is beautiful and smooth.

[0020] 2) The present invention uses 3,5-di-tert-butyl-4-hydroxybenzoic acid as a raw material, uses thionyl chloride to chlorinate the carboxyl group of 3,5-di-tert-butyl-4-hydroxybenzoic acid to obtain intermediate 1, uses tert-butylphenol and phosphorus oxychloride as raw materials, and performs an esterification reaction under the condition of aluminum chloride as a catalyst to obtain intermediate 2, then the acyl chloride group of intermediate 1 and the phenolic hydroxyl group of intermediate 2 undergo an esterification reaction, and then undergoes a Fries rearrangement under the condition of aluminum chloride as a catalyst to obtain intermediate 3, and finally the phosphorus oxychloride group of intermediate 3 undergoes a nucleophilic substitution reaction with the amino group of aminopropyltriethoxysilane to obtain a composite functional agent; the composite functional agent of the present invention has a benzophenone structure, and the benzophenone structure has a hydroxyl group at the ortho position, which can form a hydrogen bond in the molecule, and this structure absorbs the energy of ultraviolet light when exposed to ultraviolet light to break the hydrogen bond The composite functional agent can absorb ultraviolet light in the form of heat energy, and can re-form hydrogen bonds under normal conditions to absorb ultraviolet light again, and has a long-term effective absorption effect on ultraviolet light; in addition, the composite functional agent also has a hindered phenol-based structure, which has good antioxidant properties and is not easy to oxidize and denature, and the phosphate structure of the composite functional agent can react at high temperatures to form a protective layer to isolate direct contact between oxygen and the substrate, and has good flame retardancy. Therefore, the composite functional agent of the present invention has ultraviolet absorption and antioxidant effects, and is flame retardant. In addition, the organic silicon structure in the composite functional agent can also give the composite functional agent good inorganic affinity, thereby improving the degree of bonding of the composite functional agent on nano-silicon dioxide, making the components not easy to fall off, and can be effective for a long time.

[0021] 3) The highly weather-resistant polyurethane paint of the present invention has high preparation efficiency, a simple preparation method, is environmentally friendly, has flame retardancy, and has excellent antioxidant and UV resistance, so it has good weather resistance and long-term stable performance. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0023] Example 1 A highly weather-resistant polyurethane paint, comprising the following raw materials in parts by weight: 40 parts of polycaprolactone diol, 8 parts of metallic pigment, 2 parts of nano-silicon dioxide, 10 parts of alkyd resin, 8 parts of isophorone diisocyanate, 2 parts of pentaerythritol, 2 parts of composite functional agent, and 15 parts of propylene glycol methyl ether acetate; The preparation method of the highly weather-resistant polyurethane paint comprises the following steps: Step 1: weigh each raw material according to the mass fraction, and divide propylene glycol methyl ether acetate into three equal parts; Step 2: dissolving the metallic pigment with two portions of propylene glycol methyl ether acetate, adding polycaprolactone diol, alkyd resin, and pentaerythritol to the propylene glycol methyl ether acetate, and stirring at a speed of 1000 r / min for 40 minutes to obtain liquid A; Step 3: dissolving the composite functional agent with one portion of propylene glycol methyl ether acetate, adding nano-silicon dioxide and isophorone diisocyanate to the propylene glycol methyl ether acetate, and stirring at a speed of 1500 r / min for 30 min to obtain liquid B; Step 4: Add liquid B to liquid A, mix evenly and adjust the color to produce a highly weather-resistant polyurethane paint.

[0024] The oil content of the alkyd resin used in this embodiment is less than 50%.

[0025] Among them, the composite functional agent in this embodiment is prepared by the following steps: Step 1: 0.1 mol 3,5-di-tert-butyl-4-hydroxybenzoic acid, 0.08 mol thionyl chloride and 40 mL chloroform were mixed in a container, stirred evenly, and reacted at 60°C for 3 h. After the reaction was completed, the intermediate 1 was obtained by rotary evaporation; Step 2: 0.1 mol of pyrogallol, 0.1 mol of phosphorus oxychloride, 3 g of aluminum chloride, and 30 mL of N-methylpyrrolidone were mixed in a container, stirred evenly, and reacted at 70°C for 6 h. After the reaction was completed, the intermediate 2 was obtained by rotary evaporation; Step 3: 0.08 mol of intermediate 1, 0.08 mol of intermediate 2 and 60 mL of tetrahydrofuran were mixed in a container, stirred evenly, reacted at 60°C for 3 h, then 16 g of aluminum chloride was added to the container, and reacted at 140°C for 6 h. After the reaction, deionized water was added to the container for washing, and the organic layer of the obtained product was separated by a separatory funnel, and then rotary evaporated to obtain intermediate 3; Step 4: Mix 0.05 mol of intermediate 3, 0.05 mol of aminopropyltriethoxysilane, 0.06 mol of triethylamine and 60 mL of N-methylpyrrolidone in a container, stir evenly, and react at 110° C. for 10 h. After the reaction, rotary evaporate to obtain a composite functional agent.

[0026] Example 2 A highly weather-resistant polyurethane paint comprises the following raw materials in parts by weight: 45 parts of polycaprolactone diol, 8 parts of ceramic pigment, 3 parts of nano-silicon dioxide, 10 parts of alkyd resin, 10 parts of isophorone diisocyanate, 2 parts of pentaerythritol, 3 parts of composite functional agent, and 15 parts of methyl nylonate; The preparation method of the highly weather-resistant polyurethane paint comprises the following steps: Step 1: weigh each raw material according to the mass fraction, and divide nylon acid methyl ester into three equal parts; Step 2: grind the ceramic pigment to a particle size of less than 10 μm, dissolve it in two portions of methyl nylonate, add polycaprolactone diol, alkyd resin, and pentaerythritol to the methyl nylonate, and stir at a speed of 1100 r / min for 50 min to obtain liquid A; Step 3: dissolving the composite functional agent with one portion of nylon acid methyl ester, adding nano-silicon dioxide and isophorone diisocyanate to the nylon acid methyl ester, and stirring at 1650 r / min for 35 min to obtain liquid B; Step 4: Add liquid B to liquid A, mix evenly and adjust the color to produce a highly weather-resistant polyurethane paint.

[0027] The oil content of the alkyd resin used in this embodiment is less than 50%.

[0028] The composite functional agent in this embodiment is prepared by the following steps: Step 1: 0.1 mol 3,5-di-tert-butyl-4-hydroxybenzoic acid, 0.09 mol thionyl chloride and 50 mL chloroform were mixed in a container, stirred evenly, and reacted at 70°C for 3.5 h. After the reaction was completed, the intermediate 1 was obtained by rotary evaporation; Step 2: 0.1 mol of pyrogallol, 0.1 mol of phosphorus oxychloride, 3.5 g of aluminum chloride, and 35 mL of N-methylpyrrolidone were mixed in a container, stirred evenly, and reacted at 80°C for 7 h. After the reaction was completed, the intermediate 2 was obtained by rotary evaporation; Step 3: 0.08 mol of intermediate 1, 0.08 mol of intermediate 2 and 70 mL of tetrahydrofuran were mixed in a container, stirred evenly, reacted at 60°C for 3 h, then 20 g of aluminum chloride was added to the container, and reacted at 150°C for 7 h. After the reaction, deionized water was added to the container for washing, and the organic layer of the obtained product was separated by a separatory funnel, and then rotary evaporated to obtain intermediate 3; Step 4: Mix 0.05 mol of intermediate 3, 0.055 mol of aminopropyltriethoxysilane, 0.07 mol of triethylamine and 70 mL of N-methylpyrrolidone in a container, stir evenly, and react at 115° C. for 11 hours. After the reaction is completed, rotary evaporation is performed to obtain a composite functional agent.

[0029] Example 3 A highly weather-resistant polyurethane paint, comprising the following raw materials in parts by weight: 40 parts of polycaprolactone diol, 20 parts of ceramic pigment, 2 parts of nano-silicon dioxide, 12 parts of alkyd resin, 8 parts of isophorone diisocyanate, 3 parts of pentaerythritol, 2 parts of composite functional agent, and 20 parts of propylene glycol methyl ether acetate; The preparation method of the highly weather-resistant polyurethane paint comprises the following steps: Step 1: weigh each raw material according to the mass fraction, and divide propylene glycol methyl ether acetate into three equal parts; Step 2: grind the ceramic pigment to a particle size of less than 10 μm, dissolve it in two portions of propylene glycol methyl ether acetate, add polycaprolactone diol, alkyd resin, and pentaerythritol to the propylene glycol methyl ether acetate, and stir at a speed of 1200 r / min for 60 min to obtain liquid A; Step 3: dissolving the composite functional agent with one portion of propylene glycol methyl ether acetate, adding nano-silicon dioxide and isophorone diisocyanate to the propylene glycol methyl ether acetate, and stirring at a speed of 1800 r / min for 40 min to obtain liquid B; Step 4: Add liquid B to liquid A, mix evenly and adjust the color to produce a highly weather-resistant polyurethane paint.

[0030] The oil content of the alkyd resin used in this embodiment is less than 50%.

[0031] The composite functional agent in this embodiment is prepared by the following steps: Step 1: 0.1 mol 3,5-di-tert-butyl-4-hydroxybenzoic acid, 0.1 mol thionyl chloride and 60 mL chloroform were mixed in a container, stirred evenly, and reacted at 80°C for 4 h. After the reaction was completed, the intermediate 1 was obtained by rotary evaporation; Step 2: 0.1 mol of pyrogallol, 0.1 mol of phosphorus oxychloride, 4 g of aluminum chloride, and 40 mL of N-methylpyrrolidone were mixed in a container, stirred evenly, and reacted at 90° C. for 8 h. After the reaction was completed, the intermediate 2 was obtained by rotary evaporation; Step 3: 0.08 mol of intermediate 1, 0.08 mol of intermediate 2 and 80 mL of tetrahydrofuran were mixed in a container, stirred evenly, and reacted at 60°C for 3 h. Then, 24 g of aluminum chloride was added to the container, and reacted at 160°C for 8 h. After the reaction, deionized water was added to the container for washing. The organic layer of the obtained product was separated by a separatory funnel, and then rotary evaporated to obtain intermediate 3. Step 4: 0.05 mol of intermediate 3, 0.06 mol of aminopropyltriethoxysilane, 0.08 mol of triethylamine and 80 mL of N-methylpyrrolidone were mixed in a container, stirred evenly, and reacted at 120° C. for 12 h. After the reaction was completed, a composite functional agent was obtained by rotary evaporation.

[0032] Experimental Example 1 The composite functional agent obtained in Examples 1-3 was coated on a wooden board, and a wooden board not coated with any substance was used as a blank control. Four wooden boards were placed in a test box and subjected to an ultraviolet aging test at a temperature of 60°C and 4 hours of ultraviolet light irradiation, wherein the test wavelength of the ultraviolet light was QUVB (320-400nm) and the intensity was 0.81W / m 2 The yellowing value standard is tested according to the national standard GB11186.3-89. The test results are shown in Table 1: Table 1 project Yellowing value Example 1 1.62 Example 2 1.39 Example 3 1.77 Blank control 34.09 It can be seen from Table 1 that the change in the yellowness value of the wood board coated with the composite functional agent of the present invention is significantly smaller than that of the blank control group, indicating that the composite functional agent of the present invention has a good absorption effect on ultraviolet light and has a long-lasting effect and will not degrade even under long-term high-intensity ultraviolet light irradiation conditions.

[0033] Comparative Example 1 This comparative example is a polyurethane primer sold by Jinuo Shengcheng Paint Co., Ltd.

[0034] The high weather-resistant polyurethane paint obtained in Examples 1-3 and the polyurethane primer in Comparative Example 1 were subjected to adhesion test according to QB / T2412-98, abrasion resistance test according to GB / T1768-2006, and flame retardancy test according to national standard GB / 12441-2005, respectively. The test results are shown in Table 2: Table 2 project Adhesion grade Wear resistance test Flame retardant time / min Example 1 Level 1 44 times 15min Example 2 Level 1 48 times 18min Example 3 Level 1 43 times 14min Comparative Example 1 Level 2 24 times <3min It can be seen from Table 2 that the high weather-resistant polyurethane paint of the present invention is far superior to the commercially available polyurethane primer in terms of adhesion grade and wear resistance test type mechanical property tests, and the addition of the composite functional agent of the present invention has a longer flame retardant time, good UV resistance and antioxidant properties, and good weather resistance.

[0035] A highly weather-resistant polyurethane paint provided by the present invention is introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combination method. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention can be used in combination with each other in any way. The reason why these combinations are not exhaustively described in this specification is only for the consideration of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A highly weather-resistant polyurethane paint, characterized in that: Contains the following raw materials in parts by mass: 40-45 parts of super weather-resistant polyester resin, 8-20 parts of pigment, 2-3 parts of nano-silicon dioxide, 10-12 parts of high-toughness polyester resin, 8-10 parts of blocked isocyanate, 2-3 parts of additives, 2-3 parts of composite functional agents, and 15-20 parts of environmentally friendly solvents; Wherein, the composite functional agent is prepared by the following steps: Step 1: Mix 3,5-di-tert-butyl-4-hydroxybenzoic acid, thionyl chloride and chloroform in a container, stir evenly, and react at 60-80° C. for 3-4 hours to obtain intermediate 1; Step 2: Mix pyrogallol, phosphorus oxychloride, aluminum chloride and N-methylpyrrolidone in a container, stir evenly, and react at 70-90° C. for 6-8 hours to obtain intermediate 2; Step 3: Intermediate 1, intermediate 2 and tetrahydrofuran are mixed in a container, stirred evenly, reacted at 60° C. for 3 h, then aluminum chloride is added to the container, and reacted at 140-160° C. for 6-8 h to obtain intermediate 3; Step 4: Mix the intermediate 3, aminopropyltriethoxysilane, triethylamine and N-methylpyrrolidone in a container, stir evenly, and react at a temperature of 110-120° C. for 10-12 hours to obtain the composite functional agent.

2. A highly weather-resistant polyurethane paint according to claim 1, characterized in that: The amount ratio of 3,5-di-tert-butyl-4-hydroxybenzoic acid, thionyl chloride and chloroform used in step 1 is 0.1 mol: 0.08-0.1 mol: 40-60 mL.

3. A highly weather-resistant polyurethane paint according to claim 1, characterized in that: The amount ratio of pyrogallol, phosphorus oxychloride, aluminum chloride and N-methylpyrrolidone used in step 2 is 0.1 mol: 0.1 mol: 3-4 g: 30-40 mL.

4. A highly weather-resistant polyurethane paint according to claim 1, characterized in that: The usage ratio of intermediate 1, intermediate 2, tetrahydrofuran and aluminum chloride used in step 3 is: 0.08mol: 0.08mol: 60-80mL: 16-24g.

5. A highly weather-resistant polyurethane paint according to claim 1, characterized in that: The amount ratio of intermediate 3, aminopropyltriethoxysilane, triethylamine and N-methylpyrrolidone used in step 4 is 0.05 mol: 0.05-0.06 mol: 0.06-0.08 mol: 60-80 mL.

6. A highly weather-resistant polyurethane paint according to any one of claims 1 to 5, characterized in that: The preparation method of highly weather-resistant polyurethane paint comprises the following steps: Step 1: Weigh each raw material by mass and divide the environmentally friendly solvent into three equal parts; Step 2: Grind the pigment to a particle size of less than 10 μm, dissolve it in two portions of an environmentally friendly solvent, add super weather-resistant polyester resin, high-toughness polyester resin, and additives to the environmentally friendly solvent, and stir thoroughly to obtain liquid A; Step 3: Dissolve the composite functional agent with an environmentally friendly solvent, add nano-silicon dioxide and blocked isocyanate to the environmentally friendly solvent, and stir thoroughly to obtain liquid B; Step 4: Add liquid B to liquid A, mix evenly and adjust the color to produce a highly weather-resistant polyurethane paint.

7. A highly weather-resistant polyurethane paint according to claim 6, characterized in that: The super weather-resistant polyester resin is polycaprolactone diol, the high-toughness polyester resin is an alkyd resin with an oil content of less than 50%, the blocked isocyanate is isophorone diisocyanate, the auxiliary agent is pentaerythritol, and the environmentally friendly solvent is one of propylene glycol methyl ether acetate and nylon acid methyl ester.

8. A highly weather-resistant polyurethane paint according to claim 6, characterized in that: The pigment is one of a ceramic pigment and a metal pigment, and when the used pigment is a metal pigment, grinding is not required during preparation.

9. A highly weather-resistant polyurethane paint according to claim 6, characterized in that: In the second step, the stirring speed condition is 1000-1200r / min, and the stirring speed condition is 40-60min.

10. A highly weather-resistant polyurethane paint according to claim 6, characterized in that: In the third step, the stirring speed condition is 1500-1800r / min, and the stirring speed condition is 30-40min.