Building coating with photocatalytic degradation effect as well as preparation method and application thereof

Abstract

According to the building coating with the photocatalytic degradation effect and the preparation method of the building coating, by means of maleic anhydride grafting and introduction of an ultraviolet absorbent and an antioxidant, the weather resistance, oxidation resistance and adhesive force of modified acrylic resin can be remarkably improved, degradation of the coating caused by ultraviolet rays or oxidation is delayed, and the photocatalytic degradation effect is good. The photocatalytic coating prepared by the preparation method disclosed by the invention has the advantages of high mechanical strength, excellent compatibility with other components in a coating system and flexibility and mechanical strength, so that a coating is not easy to crack or peel off, the service life of the coating is prolonged, and the photocatalytic effect is further ensured. A specific photocatalyst is prepared, the effect of porous shell powder is provided, and doping of zinc oxide is combined, so that the photocatalytic effect can be remarkably improved, organic pollutants in air can be efficiently degraded, and the environment quality is improved. Meanwhile, the porous shell powder has a high specific surface area and a pore structure, so that the adsorption capacity of the photocatalyst on pollutants can be enhanced, active sites are provided, and the photocatalytic service life is prolonged.

Description

Technical Field

[0001] The present invention relates to a method for preparing a coating, and in particular to a building coating with a photocatalytic degradation effect, a preparation method thereof, and an application thereof. Background Art

[0002] The economic and social activities of a high-density population will inevitably bring about a large amount of fine particulate matter (such as PM2.5). Once the emission exceeds the circulation capacity of the atmosphere, it is easy to cause large-scale environmental pollution due to the influence of calm weather. The existing technology uses environmental photocatalytic methods to assist in environmental governance, and uses photocatalytic coatings to degrade gaseous pollutants (VOCs, NOx, SO2, etc.) and O3 to achieve the purpose of inhibiting the formation of secondary aerosols. The degradation of gaseous pollutants will effectively inhibit the formation of SOA and SIA, reducing environmental pollution. If the surface of a building is used as a carrier to load a photocatalytic functional coating, it will be possible to fully utilize the existing building surface to control environmental air pollution, which is of great significance. For example, the Chinese patent application number 201710788580.9 discloses an automatic adsorption haze paint. By adding a surfactant to modify the existing paint, the surface energy of the paint is increased, thereby adsorbing haze. For example, Chinese patent application number CN201610741103.2 discloses a photocatalytic anti-smog sand-wall negative ion coating, comprising the following raw materials by weight: 15-60 parts of an anti-smog base material, 10-70 parts of a granular aggregate, and 10-30 parts of a binder. The anti-smog base material can eliminate smoke, oil, and sand dust in smog and increase negative ions in the air. However, the resulting coating is generally poor in quality, resulting in poor photocatalytic performance. Summary of the Invention

[0003] Based on this, in order to solve one of the above problems, the present invention provides a building coating with photocatalytic degradation effect and its preparation method and application. The specific technical solution is as follows:

[0004] A building coating with photocatalytic degradation effect, comprising the following raw materials in parts by weight:

[0005] 40 to 60 parts of modified acrylic resin, 10 to 15 parts of epoxy resin, 1 to 15 parts of photocatalyst, 0.5 to 1.3 parts of leveling agent, 0.8 to 1.7 parts of dispersant, 3 to 5 parts of curing agent, 1 to 3 parts of brightener, 0.7 to 2 parts of benzoin and 1 to 7 parts of polytetrafluoroethylene wax.

[0006] Furthermore, the preparation method of the modified acrylic resin is:

[0007] Acrylic resin is added to xylene, stirred at 60°C to 70°C for 10min to 30min, then an antioxidant and maleic anhydride are added, the temperature is raised to 80°C to 90°C under a nitrogen atmosphere, the reaction is carried out for 3h to 5h, and then an ultraviolet absorber is added and high-speed shear emulsification is performed to obtain a modified acrylic resin.

[0008] Furthermore, the weight ratio of the acrylic resin to xylene is (10-15):100.

[0009] Furthermore, the added amount of the antioxidant accounts for 1% to 8% of the mass of the acrylic resin; the added amount of the maleic anhydride accounts for 5% to 10% of the mass of the acrylic resin; and the added amount of the anti-ultraviolet absorber accounts for 1% to 3% of the mass of the acrylic resin.

[0010] Furthermore, the antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant.

[0011] Furthermore, the ultraviolet absorber is only one of salicylate ultraviolet absorbers, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, substituted acrylonitrile ultraviolet absorbers, triazine ultraviolet absorbers, and hindered amine ultraviolet absorbers.

[0012] Furthermore, the preparation method of the photocatalyst is:

[0013] Tetrabutyl titanate and terephthalic acid are added to a solvent, and stirred at 120° C. to 150° C. and 100 r / min to 500 r / min for 8 h to 10 h to obtain a precursor;

[0014] The porous shell powder is placed in an argon atmosphere, heated to 500°C to 600°C at a rate of 10°C / min to 15°C / min, kept warm for 1h to 3h, then cooled to room temperature at a rate of 5°C / min to 8°C / min, crushed, added to the precursor, and stirred at a speed of 100r / min to 500r / min for 1h to 5h, then zinc oxide is added, stirred at 100°C to 120°C for 5h to 8h, cooled to room temperature, centrifuged and dried to obtain a photocatalyst.

[0015] Furthermore, the solvent is a mixture of methanol and dimethylformamide, and the volume ratio of methanol to dimethylformamide is (20-30): (70-80).

[0016] In addition, the present invention also provides a method for preparing a building coating with a photocatalytic degradation effect, the preparation method comprising the following steps:

[0017] Add modified acrylic resin, epoxy resin, photocatalyst, leveling agent, dispersant, curing agent, brightener, benzoin and polytetrafluoroethylene wax into a mixer, and stir at a speed of 800 r / min to 1200 r / min for 5 min to 10 min to obtain a mixture;

[0018] The mixture is added to a twin-screw extruder for melt extrusion, rapidly cooled into thin sheets by a cooling roller, crushed into sheets of 1 mm to 3 mm, and then ground with an ACM mill to a D50 of 15 μm to 50 μm, and sieved to obtain a building coating with photocatalytic degradation effect.

[0019] The present invention also provides an application of a building paint with a photocatalytic degradation effect, wherein the application is an application of the building paint with a photocatalytic degradation effect in a photocatalytic degradation coating on a building surface.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention significantly improves the weather resistance, oxidation resistance and adhesion of the modified acrylic resin by grafting maleic anhydride and introducing a UV absorber and an antioxidant, delays the degradation of the coating due to ultraviolet rays or oxidation, and has excellent compatibility with other components in the coating system. It takes into account flexibility and mechanical strength, making the coating less likely to crack or peel, helping to extend the service life of the coating and further helping to ensure the photocatalytic effect.

[0022] 2. The present invention, by preparing a specific photocatalyst, provides porous shell powder, and combined with zinc oxide doping, can significantly enhance the photocatalytic effect, efficiently degrade organic pollutants in the air, and improve environmental quality. At the same time, the porous shell powder has a high specific surface area and pore structure, which can enhance the photocatalyst's adsorption capacity for pollutants, provide active sites, and extend the photocatalytic life. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] In one embodiment of the present invention, a building coating with photocatalytic degradation effect comprises the following raw materials in parts by weight:

[0026] 40 to 60 parts of modified acrylic resin, 10 to 15 parts of epoxy resin, 1 to 15 parts of photocatalyst, 0.5 to 1.3 parts of leveling agent, 0.8 to 1.7 parts of dispersant, 3 to 5 parts of curing agent, 1 to 3 parts of brightener, 0.7 to 2 parts of benzoin and 1 to 7 parts of polytetrafluoroethylene wax.

[0027] In one embodiment, the preparation method of the modified acrylic resin is:

[0028] Acrylic resin is added to xylene, stirred at 60°C to 70°C for 10min to 30min, then an antioxidant and maleic anhydride are added, the temperature is raised to 80°C to 90°C under a nitrogen atmosphere, the reaction is carried out for 3h to 5h, and then an ultraviolet absorber is added and high-speed shear emulsification is performed to obtain a modified acrylic resin.

[0029] In one embodiment, the weight ratio of the acrylic resin to xylene is (10-15):100.

[0030] In one embodiment, the added amount of the antioxidant accounts for 1% to 8% of the mass of the acrylic resin; the added amount of the maleic anhydride accounts for 5% to 10% of the mass of the acrylic resin; and the added amount of the anti-ultraviolet absorber accounts for 1% to 3% of the mass of the acrylic resin.

[0031] In one embodiment, the antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant.

[0032] In one embodiment, the ultraviolet absorber is only one of a salicylate ultraviolet absorber, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a substituted acrylonitrile ultraviolet absorber, a triazine ultraviolet absorber, and a hindered amine ultraviolet absorber.

[0033] In one embodiment, the preparation method of the photocatalyst is:

[0034] Tetrabutyl titanate and terephthalic acid are added to a solvent, and stirred at 120° C. to 150° C. and 100 r / min to 500 r / min for 8 h to 10 h to obtain a precursor;

[0035] The porous shell powder is placed in an argon atmosphere, heated to 500°C to 600°C at a rate of 10°C / min to 15°C / min, kept warm for 1h to 3h, then cooled to room temperature at a rate of 5°C / min to 8°C / min, crushed, added to the precursor, and stirred at a speed of 100r / min to 500r / min for 1h to 5h, then zinc oxide is added, stirred at 100°C to 120°C for 5h to 8h, cooled to room temperature, centrifuged and dried to obtain a photocatalyst.

[0036] In one embodiment, the solvent is a mixture of methanol and dimethylformamide, and the volume ratio of methanol to dimethylformamide is (20-30): (70-80).

[0037] In one embodiment, the weight ratio of tetrabutyl titanate, terephthalic acid, solvent, porous shell powder and zinc oxide is (15-20): (20-30): 100: (7-15): (1-7).

[0038] In one embodiment, the leveling agent is an acrylate leveling agent.

[0039] In one embodiment, the dispersant is sodium hexametaphosphate.

[0040] In one embodiment, the curing agent is the isocyanate curing agent.

[0041] In one embodiment, the brightener is at least one of pentaerythritol and microcrystalline wax.

[0042] In addition, the present invention also provides a method for preparing a building coating with a photocatalytic degradation effect, the preparation method comprising the following steps:

[0043] Add modified acrylic resin, epoxy resin, photocatalyst, leveling agent, dispersant, curing agent, brightener, benzoin and polytetrafluoroethylene wax into a mixer, and stir at a speed of 800 r / min to 1200 r / min for 5 min to 10 min to obtain a mixture;

[0044] The mixture is added to a twin-screw extruder for melt extrusion, rapidly cooled into thin sheets by a cooling roller, crushed into sheets of 1 mm to 3 mm, and then ground with an ACM mill to a D50 of 15 μm to 50 μm, and sieved to obtain a building coating with photocatalytic degradation effect.

[0045] In one embodiment, the process parameters of the melt extrusion are: the temperature of the feeding zone is 80°C to 90°C, the temperature of the melting zone is 100°C to 110°C, and the temperature of the homogenizing zone is 110°C to 120°C.

[0046] The present invention also provides an application of a building paint with a photocatalytic degradation effect, wherein the application is an application of the building paint with a photocatalytic degradation effect in a photocatalytic degradation coating on a building surface.

[0047] The architectural coating prepared by the above scheme has excellent adhesion, mechanical properties and photocatalytic effect.

[0048] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0049] Example 1:

[0050] A method for preparing a building coating with a photocatalytic degradation effect, the method comprising the following steps:

[0051] 12 parts of acrylic resin were added to 100 parts of xylene by weight, and the mixture was stirred at 70° C. for 20 minutes. Then, 7% of a hindered phenol antioxidant and 8% of maleic anhydride were added, and the mixture was heated to 90° C. under a nitrogen atmosphere and reacted for 4 hours. Then, 2% of a benzotriazole ultraviolet absorber was added, and high-speed shear emulsification was performed to obtain a modified acrylic resin.

[0052] By weight, 18 parts of tetrabutyl titanate and 25 parts of terephthalic acid were added to 100 parts of a solvent (methanol and dimethylformamide in a volume ratio of 30:70), and stirred at 120°C and 300r / min for 10 hours to obtain a precursor; 13 parts of porous shell powder were placed in an argon atmosphere, heated to 500°C at a rate of 10°C / min, kept warm for 3 hours, and then cooled to room temperature at a rate of 5°C / min. After crushing, the porous shell powder was added to the precursor and stirred at a speed of 300r / min for 4 hours, and then 6 parts of zinc oxide were added. The mixture was stirred at 120°C for 8 hours, cooled to room temperature, centrifuged and dried to obtain a photocatalyst;

[0053] In parts by weight, 50 parts of modified acrylic resin, 15 parts of epoxy resin, 13 parts of photocatalyst, 1.0 part of acrylate leveling agent, 1.3 parts of sodium hexametaphosphate, 4 parts of isocyanate curing agent, 3 parts of microcrystalline wax, 1 part of benzoin and 5 parts of polytetrafluoroethylene wax were added to a mixer and stirred at a speed of 1200 r / min for 10 minutes to obtain a mixture;

[0054] The mixture is added to a twin-screw extruder for melt extrusion, and the process parameters of the melt extrusion are: the temperature of the feeding zone is 85° C., the temperature of the melting zone is 110° C., and the temperature of the homogenizing zone is 120° C. The mixture is rapidly cooled into thin sheets by a cooling roller, and then crushed into 3 mm slices, and then ground into D50 = 45 μm by an ACM mill, and sieved to obtain a building coating with photocatalytic degradation effect.

[0055] Example 2:

[0056] A method for preparing a building coating with a photocatalytic degradation effect, the method comprising the following steps:

[0057] 14 parts of acrylic resin were added to 100 parts of xylene by weight, and the mixture was stirred at 70° C. for 20 minutes. Then, 8% of a hindered phenol antioxidant and 8% of maleic anhydride were added, and the mixture was heated to 90° C. under a nitrogen atmosphere and reacted for 5 hours. Then, 1% of a benzotriazole ultraviolet absorber was added, and high-speed shear emulsification was performed to obtain a modified acrylic resin.

[0058] According to the weight ratio, 19 parts of tetrabutyl titanate and 27 parts of terephthalic acid are added to 100 parts of a solvent (methanol and dimethylformamide in a volume ratio of 30:70), and stirred at 120°C and 300r / min for 10 hours to obtain a precursor; 13 parts of porous shell powder are placed in an argon atmosphere, heated to 600°C at a rate of 10°C / min, kept warm for 3 hours, and then cooled to room temperature at a rate of 8°C / min. After crushing, the porous shell powder is added to the precursor and stirred at a speed of 500r / min for 5 hours, and then 7 parts of zinc oxide are added, stirred at 120°C for 7 hours, cooled to room temperature, centrifuged and dried to obtain a photocatalyst;

[0059] In parts by weight, 50 parts of modified acrylic resin, 12 parts of epoxy resin, 15 parts of photocatalyst, 0.9 parts of acrylate leveling agent, 1.1 parts of sodium hexametaphosphate, 5 parts of isocyanate curing agent, 3 parts of microcrystalline wax, 1 part of benzoin and 5 parts of polytetrafluoroethylene wax were added to a mixer and stirred at a speed of 1200 r / min for 10 minutes to obtain a mixture;

[0060] The mixture is added to a twin-screw extruder for melt extrusion, and the process parameters of the melt extrusion are: the temperature of the feeding zone is 85° C., the temperature of the melting zone is 110° C., and the temperature of the homogenizing zone is 120° C. The mixture is rapidly cooled into thin sheets by a cooling roller, and then crushed into 3 mm slices, and then ground into D50 = 45 μm by an ACM mill, and sieved to obtain a building coating with photocatalytic degradation effect.

[0061] Example 3:

[0062] A method for preparing a building coating with a photocatalytic degradation effect, the method comprising the following steps:

[0063] 15 parts of acrylic resin were added to 100 parts of xylene by weight, and the mixture was stirred at 65° C. for 20 minutes. Then, 5% of a hindered phenol antioxidant and 6% of maleic anhydride were added, and the mixture was heated to 85° C. under a nitrogen atmosphere and reacted for 4 hours. Then, 3% of a benzotriazole ultraviolet absorber was added, and high-speed shear emulsification was performed to obtain a modified acrylic resin.

[0064] By weight, 18 parts of tetrabutyl titanate and 27 parts of terephthalic acid were added to 100 parts of a solvent (methanol and dimethylformamide in a volume ratio of 30:70), and stirred at 120°C and 300r / min for 10 hours to obtain a precursor; 12 parts of porous shell powder were placed in an argon atmosphere, heated to 550°C at a rate of 10°C / min, kept warm for 2 hours, and then cooled to room temperature at a rate of 6°C / min. After crushing, the porous shell powder was added to the precursor and stirred at a speed of 200r / min for 3 hours, and then 5 parts of zinc oxide were added. The mixture was stirred at 120°C for 6 hours, cooled to room temperature, centrifuged and dried to obtain a photocatalyst;

[0065] In parts by weight, 50 parts of modified acrylic resin, 10 parts of epoxy resin, 10 parts of photocatalyst, 0.8 parts of acrylate leveling agent, 1.2 parts of sodium hexametaphosphate, 4 parts of isocyanate curing agent, 3 parts of microcrystalline wax, 1 part of benzoin and 3 parts of polytetrafluoroethylene wax were added to a mixer and stirred at a speed of 1000 r / min for 10 minutes to obtain a mixture;

[0066] The mixture is added to a twin-screw extruder for melt extrusion, and the process parameters of the melt extrusion are: the temperature of the feeding zone is 85° C., the temperature of the melting zone is 110° C., and the temperature of the homogenizing zone is 120° C. The mixture is rapidly cooled into thin sheets by a cooling roller, and then crushed into 3 mm slices, and then ground into D50 = 45 μm by an ACM mill, and sieved to obtain a building coating with photocatalytic degradation effect.

[0067] Comparative Example 1:

[0068] Compared with Example 3, conventional acrylic resin was used in place of modified acrylic resin in Comparative Example 1, and the rest was the same as in Example 3.

[0069] Comparative Example 2:

[0070] Compared with Example 3, no antioxidant was added to the modified acrylic resin in Comparative Example 2, and the other conditions were the same as those in Example 3.

[0071] Comparative Example 3:

[0072] Compared with Example 3, maleic anhydride was not added to the modified acrylic resin in Comparative Example 3, and the rest was the same as in Example 3.

[0073] Comparative Example 4:

[0074] Compared with Example 3, no ultraviolet absorber was added to the modified acrylic resin in Comparative Example 4, and the other conditions were the same as those in Example 3.

[0075] Comparative Example 5:

[0076] Compared with Example 3, the photocatalyst in Comparative Example 5 does not contain porous shell powder, and the rest is the same as Example 3.

[0077] Comparative Example 6:

[0078] Compared with Example 3, zinc oxide was not added to the photocatalyst in Comparative Example 6, and the other components were the same as those in Example 3.

[0079] Comparative Example 7:

[0080] Compared with Example 3, no photocatalyst was added in Comparative Example 7, and the rest was the same as Example 3.

[0081] The architectural coating samples prepared in Examples 1-3 and the comparative architectural coating samples prepared in Comparative Examples 1-7 were coated onto 150 mm × 100 mm × 5 mm asbestos cement boards to a thickness of 0.2 μm. After drying, the coating properties were tested. The results are shown in Table 1 below.

[0082] Table 1: Performance test results

[0083]

[0084] Analysis of the data in Table 1 demonstrates that the present invention, by modifying an acrylic resin to obtain a modified acrylic resin, grafting it with maleic anhydride, and then introducing an antioxidant and a UV absorber, increases active sites while ensuring good compatibility of the modified acrylic resin, reduces the migration of the antioxidant and UV absorber, and thus imparts superior weather resistance and adhesion, thereby positively impacting photocatalysis. Furthermore, the photocatalyst prepared by the present invention exhibits a synergistic effect, resulting in a significant photocatalytic effect and excellent adsorption of PM2.5, achieving a certain haze reduction effect.

[0085] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0086] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A building coating with photocatalytic degradation effect, characterized in that: The architectural coating comprises the following raw materials in parts by weight: 40 to 60 parts of modified acrylic resin, 10 to 15 parts of epoxy resin, 1 to 15 parts of photocatalyst, 0.5 to 1.3 parts of leveling agent, 0.8 to 1.7 parts of dispersant, 3 to 5 parts of curing agent, 1 to 3 parts of brightener, 0.7 to 2 parts of benzoin and 1 to 7 parts of polytetrafluoroethylene wax.

2. The architectural coating according to claim 1, characterized in that The preparation method of the modified acrylic resin is: Acrylic resin is added to xylene, stirred at 60°C to 70°C for 10min to 30min, then an antioxidant and maleic anhydride are added, the temperature is raised to 80°C to 90°C under a nitrogen atmosphere, the reaction is carried out for 3h to 5h, and then an ultraviolet absorber is added and high-speed shear emulsification is performed to obtain a modified acrylic resin.

3. The architectural coating according to claim 2, characterized in that The weight ratio of the acrylic resin to xylene is (10-15):

100.

4. The architectural coating according to claim 2, characterized in that The added amount of the antioxidant accounts for 1% to 8% of the mass of the acrylic resin; the added amount of the maleic anhydride accounts for 5% to 10% of the mass of the acrylic resin; and the added amount of the anti-ultraviolet absorber accounts for 1% to 3% of the mass of the acrylic resin.

5. The architectural coating according to claim 4, characterized in that The antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant.

6. The architectural coating according to claim 4, characterized in that The ultraviolet absorber is one of salicylate ultraviolet absorbers, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, substituted acrylonitrile ultraviolet absorbers, triazine ultraviolet absorbers, and hindered amine ultraviolet absorbers.

7. The architectural coating according to claim 1, characterized in that The preparation method of the photocatalyst is: Tetrabutyl titanate and terephthalic acid are added to a solvent, and stirred at 120° C. to 150° C. and 100 r / min to 500 r / min for 8 h to 10 h to obtain a precursor; The porous shell powder is placed in an argon atmosphere, heated to 500°C to 600°C at a rate of 10°C / min to 15°C / min, kept warm for 1h to 3h, then cooled to room temperature at a rate of 5°C / min to 8°C / min, crushed, added to the precursor, and stirred at a speed of 100r / min to 500r / min for 1h to 5h, then zinc oxide is added, stirred at 100°C to 120°C for 5h to 8h, cooled to room temperature, centrifuged and dried to obtain a photocatalyst.

8. The architectural coating according to claim 7, characterized in that The solvent is a mixture of methanol and dimethylformamide, and the volume ratio of the methanol to the dimethylformamide is (20-30): (70-80).

9. A method for preparing a building coating with photocatalytic degradation effect, characterized in that: The preparation method is used to prepare the architectural coating with photocatalytic degradation effect as claimed in any one of claims 1 to 8, and the preparation method comprises the following steps: Add modified acrylic resin, epoxy resin, photocatalyst, leveling agent, dispersant, curing agent, brightener, benzoin and polytetrafluoroethylene wax into a mixer, and stir at a speed of 800 r / min to 1200 r / min for 5 min to 10 min to obtain a mixture; The mixture is added to a twin-screw extruder for melt extrusion, rapidly cooled into thin sheets by a cooling roller, crushed into sheets of 1 mm to 3 mm, and then ground with an ACM mill to a D50 of 15 μm to 50 μm, and sieved to obtain a building coating with photocatalytic degradation effect.

10. Use of a building paint with a photocatalytic degradation effect, wherein the use is use of the building paint with a photocatalytic degradation effect according to any one of claims 1 to 8 in a photocatalytic degradation coating on a building surface.

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