Anti-ultraviolet finishing varnish for building external wall and preparation method thereof

Abstract

The invention relates to an anti-ultraviolet finishing varnish for a building outer wall. The anti-ultraviolet finishing varnish for the building outer wall comprises a fluorocarbon emulsion, an acrylic emulsion, an anti-ultraviolet auxiliary agent, an organic amine auxiliary agent, an auxiliary agent and water, the fluorocarbon emulsion, the acrylic emulsion and the anti-ultraviolet additive are compounded, and the anti-ultraviolet additive is formed by respectively introducing a triazine ultraviolet light absorbing group and a hindered amine group on nano titanium dioxide. The problem of poor utilization efficiency caused by different action positions of the hindered amine light stabilizer and the ultraviolet absorbent can be effectively solved, and migration and loss of the hindered amine light stabilizer and the ultraviolet absorbent in a paint film are avoided; besides, the nano titanium dioxide grafted with the triazine ultraviolet light absorbing group and the hindered amine group can reduce the hydroxyl density on the surface of the nano titanium dioxide and avoid agglomeration of the nano titanium dioxide, so that the compatibility and dispersity of the nano titanium dioxide in the components are improved, the rigidity of the varnish is improved, and the service life of the varnish is prolonged. And the scrubbing resistance of the paint film is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of construction, in particular to an anti-ultraviolet finish varnish for building exterior walls and a preparation method thereof. Background Art

[0002] Ultraviolet rays are a type of electromagnetic radiation with a shorter wavelength than visible light. They can be further divided into three main types based on wavelength: Ultraviolet A (UVA), Ultraviolet B (UVB) and Ultraviolet C (UVC). The shorter the wavelength, the higher the energy. UVA has the longest wavelength, UVB has the second longest wavelength, and UVC has the shortest wavelength. However, the atmosphere has a high absorption effect on it and has little impact on the surface. Ultraviolet rays come from many sources, and the photochemical aging of varnish mainly comes from solar radiation.

[0003] Protection against ultraviolet light is related to environmental safety, resource conservation and human health. In order to improve the level of protection against ultraviolet light, anti-ultraviolet coatings have been widely used in the fields of architectural glass and automotive glass. However, the requirements for anti-aging performance of building exterior walls, which are also facing severe aging environments, seem to have been ignored for a long time. Light aging of exterior walls will not only cause the varnish to powder, crack and fall off, but also reduce the stain resistance, causing the exterior wall's aesthetics to deteriorate or even become irreparable.

[0004] Functional anti-UV topcoat can be used to enhance the anti-aging performance of building exterior walls. However, due to the complexity of topcoat ingredients and considering possible antagonistic effects, strict requirements are imposed on the screening and addition of anti-aging additives. Moreover, due to the diversity of topcoats such as flat coating and thick paste, the addition of anti-UV additives is inconvenient, complicated and inefficient.

[0005] By enriching the functionality of the topcoat varnish, developing a topcoat with aging resistance can not only shield UV light, but also facilitate construction. It is more efficient and broad-spectrum than developing UV-resistant topcoat, and has excellent convenience and applicability. There are many benefits to developing functional building exterior wall covers, such as: (1) Improving building performance: Functional exterior wall covers can improve building performance, such as insulation, waterproofing, and sound insulation. These functions can improve the comfort and sustainability of buildings, reduce energy consumption, and reduce environmental impact; (2) Enhancing the appearance of buildings: Functional exterior wall covers can add unique features and styles to buildings; (3) Improving indoor environmental quality: Some functional exterior wall covers can help improve indoor air quality, such as dust prevention, antibacterial, and air purification; (4) Extending the life of buildings: Functional exterior wall covers can provide an additional layer of protection to prevent buildings from being damaged by the external environment and extend the service life of buildings.

[0006] Most of the current building exterior wall coverings focus on monotonous basic functional properties: that is, simply providing the paint film properties required for a certain covering, and not paying attention to additional functional properties. For the exterior wall varnish system with broad market prospects, overly monotonous performance will undoubtedly greatly affect the efficiency of resource utilization, indirectly increase production and use costs, and is very unfavorable to the development of the covering and the overall exterior wall varnish system. To achieve a breakthrough, the covering varnish system must be given advanced functional properties.

[0007] Since the functional anti-ultraviolet coating is mainly determined by two factors, namely, film-forming materials and anti-ultraviolet additives, the product development is also carried out from these two aspects in turn:

[0008] (I) Based on the film-forming material, i.e., the resin emulsion level: In the prior art, due to the high requirements of the functional coating on the film-forming material, the current use of a single emulsion has a single function and a limited scope of application. There are two solutions to the current dilemma. One is the targeted improvement of the emulsion synthesis stage, but this method has a "blind box effect", that is, there is a large gap between the performance of the actual synthetic emulsion and the expected performance; the second is to improve the compounding of the emulsion in order to achieve the effect of combining the advantages of two or more emulsions, but the current stage of compounding is inefficient and cannot be self-consistent. In essence, it lacks theoretical explanation assistance at the micro-nano level.

[0009] (II) Based on the anti-ultraviolet additive level: Although the functionality of the building exterior wall covering needs to be developed, we can get a glimpse of the situation from the functional anti-ultraviolet glass exterior wall and automobile coatings. The current development of anti-ultraviolet coatings tends to use hindered amine light stabilizers alone or ultraviolet light absorbers alone, but the effects are not ideal. A few companies have adopted a compounding strategy. One is to compound hindered amine light stabilizers with ultraviolet light absorbers, and the other is to compound organic anti-ultraviolet additives with inorganic anti-ultraviolet additives. This strategy has significantly improved the effect compared with the traditional single-combination, but there are still disadvantages: the anti-ultraviolet compound products of anti-ultraviolet additive manufacturers have limited application scenarios. With the iteration and upgrading of coating products, the original compound products are facing elimination, and the original compound products cannot be split and used, resulting in a huge waste of raw materials; coating companies have low efficiency in independent compounding, prolonged R&D cycle, and blind compounding.

[0010] The above two situations are simple physical compounding, and there are several disadvantages, such as Figure 1As shown in the figure, (1) poor dispersibility greatly affects the actual weathering effect; (2) although the dispersibility can be improved to make the hindered amine light stabilizer and the ultraviolet light absorber evenly distributed in the varnish, the hindered amine light stabilizer mainly works on the surface of the varnish, while the ultraviolet light absorber mainly works inside the varnish, which means that the role of the ultraviolet light absorber dispersed on the surface of the varnish and the hindered amine light stabilizer dispersed inside the varnish is greatly limited; (3) as time goes by, small molecule organic anti-ultraviolet additives will gradually migrate and lose, which greatly affects the weathering resistance of the paint film.

[0011] In summary, it is urgent to design an anti-ultraviolet finish varnish for building exterior walls to solve the problems existing in the prior art. Summary of the invention

[0012] Based on this, the present invention provides an anti-ultraviolet topcoat varnish for building exterior walls to overcome the shortcomings of the prior art. The technical solution greatly improves the dispersibility of anti-ultraviolet additives, effectively solves the utilization efficiency of hindered amine light stabilizers and ultraviolet absorbers, and effectively avoids the loss of small molecule additives in the paint film.

[0013] An object of the present invention is to provide an anti-ultraviolet finish varnish for building exterior walls, wherein the anti-ultraviolet finish varnish for building exterior walls comprises the following components in parts by weight:

[0014]

[0015]

[0016] Wherein, the anti-ultraviolet auxiliary agent is nano titanium dioxide grafted with hindered amine groups and triazine groups.

[0017] Furthermore, the nano titanium dioxide is rutile nano titanium dioxide.

[0018] Furthermore, the acrylic emulsion is selected from one or more of hydroxypropyl emulsion, styrene-acrylic emulsion and pure acrylic emulsion.

[0019] Specifically, the present invention combines the advantages of acrylic emulsion and fluorocarbon emulsion and optimizes their disadvantages by compounding them, and can achieve the regulation of the gloss of the paint film from matte, semi-gloss, to high gloss, and the compounding process is simple and highly operable.

[0020] Furthermore, the organic amine auxiliary agent is selected from one or more of 2-amino-2-methyl-1-propanol and diethanolamine.

[0021] Furthermore, the auxiliary agent is selected from one or more of a thickener, a defoamer, a preservative, a wetting agent, an antifreeze agent, and a film-forming auxiliary agent.

[0022] Furthermore, the thickener is an alkali swelling thickener.

[0023] Preferably, the thickener is selected from one or more of Dow's TT935, Wanhua Chemical's A-401, and Puwei Chemical's RS-315.

[0024] Furthermore, the defoaming agent is selected from one or more of polyether-modified dimethylsiloxane, polysiloxane and ethylene glycol siloxane.

[0025] Furthermore, the preservative is selected from one or more of 2-methyl-4-isothiazoline-3-one and 1,2-benzisothiazolin-3-one (BIT).

[0026] Furthermore, the wetting agent is selected from one or more of silicone oil wetting agents, nonionic surfactants, cationic surfactants, hydrophobic solvents, polymer wetting agents, and fluorocarbon wetting agents.

[0027] Furthermore, the antifreeze agent is selected from one or more of propylene glycol and ethylene glycol butyl ether.

[0028] Furthermore, the film-forming aid is selected from one or more of alcohol ester dodecaned, propylene glycol butyl ether, dipropylene glycol methyl ether and benzyl alcohol.

[0029] like Figure 2 As shown in the figure, fluorocarbon emulsion is an excellent film-forming material, but it has the following disadvantages: (1) Fluorocarbon emulsion is subject to strong hydrogen bonds between fluorine atoms, has strong cohesive force, and the flexibility of the paint film is usually poor; (2) The presence of too many fluorine atoms on the surface makes the paint film not resistant to oil stains despite its low surface energy. In other words, it cannot be easily washed off with water; (3) High-gloss fluorocarbon emulsions are difficult to apply and do not conform to modern aesthetics.

[0030] The compounding of fluorocarbon emulsion and acrylic emulsion has the following advantages: (1) The introduction of acrylic emulsion can dilute the strong fluorine-fluorine hydrogen bond in the fluorocarbon emulsion, and at the same time introduce relatively weak fluorine-hydroxyl weak hydrogen bonds, which can reduce the cohesion of the varnish to a certain extent without losing the density of the paint film, thereby improving the flexibility; (2) By adjusting the ratio of fluorine atoms to hydroxyl groups on the surface of the paint film, the surface energy of the paint film can be changed, and its stain resistance can be improved. When the static water contact angle of the paint film is adjusted to close to 90°, it has good resistance to both water-based stains and oily stains, and the stain resistance is greatly improved; (3) By introducing matte acrylic resin and setting the gradient and highlight fluorocarbon emulsion compounding ratio, the gloss of the paint film can be adjusted in a targeted manner.

[0031] like Figure 3As shown, we selected nano-TiO2 for water-based coatings and used a high-pressure reactor to graft triazine groups and hindered amine groups onto nano-TiO2 under acid catalysis. Although the triazine groups and hindered amine groups were grafted, their compatibility with the water environment was not significantly affected. The surface-modified nano-TiO2 had good dispersibility, which maximized the role of the hindered amine groups and triazine groups. The introduction of nano-titanium dioxide further improved the rigidity of the varnish, greatly improving the scrub resistance of the paint film.

[0032] The present invention also provides a method for preparing the anti-ultraviolet finish varnish for building exterior walls, comprising the following steps:

[0033] S1. The activated nano-titanium dioxide is mixed with a solvent, a hydroxyl-containing hindered amine compound, and an acid, and reacted, and then a hydroxyl-containing triazine group compound is added, and the reaction is continued, and the anti-ultraviolet additive is obtained after centrifugation, washing, and drying;

[0034] S2. Add an auxiliary agent into water, add an organic amine auxiliary agent to adjust the pH, and then add the remaining ingredients to obtain the anti-ultraviolet topcoat varnish for the building exterior wall.

[0035] Furthermore, in step S1, the activation method of the nano titanium dioxide is drying at 180-230° C. for 10-14 hours.

[0036] Furthermore, in step S1, the acid is selected from one or more of sulfuric acid and hydrochloric acid.

[0037] Furthermore, in step S1, the reaction temperature is 125-185°C.

[0038] Furthermore, in step S1, the reaction pressure is 200-500 kPa.

[0039] The present invention has the following beneficial effects:

[0040] 1. The present invention adopts a fluorocarbon emulsion, an acrylic emulsion and an anti-ultraviolet additive, wherein the anti-ultraviolet additive is a modified nano titanium dioxide introduced with a triazine ultraviolet light absorbing group and a hindered amine group, which can effectively solve the problem of poor utilization efficiency of hindered amine light stabilizers and ultraviolet absorbers due to different action positions, and avoids the migration and loss of the two in the paint film; in addition, since the modified nano titanium dioxide can reduce the surface hydroxyl density of the nano titanium dioxide and avoid the agglomeration of the nano titanium dioxide, the compatibility and dispersibility of the nano titanium dioxide in the varnish composition are improved, the rigidity of the varnish is further improved, and the scrub resistance of the paint film is greatly improved.

[0041] 2. The present invention achieves gloss adjustment and has excellent stain resistance by compounding fluorocarbon emulsion and acrylic emulsion. Acrylic emulsion can dilute the strength of fluorine-fluorine strong hydrogen bonds in fluorocarbon emulsion and introduce relatively weak fluorine-hydroxyl weak hydrogen bonds. Without losing the density of the paint film, the cohesion of the varnish is reduced, thereby improving the flexibility. The stain resistance of the paint film is also improved by adjusting the surface energy of the paint film. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of the problem of the existence of anti-ultraviolet additives in varnishes of the prior art;

[0043] Figure 2 It is a schematic diagram of the principle of compounding fluorocarbon emulsion and acrylic emulsion in the present invention;

[0044] Figure 3 The schematic diagram of the reaction of modified nano-titanium dioxide in Examples 1-3;

[0045] Figure 4 The results of the varnishes of Examples 1-3 and Comparative Examples 1-3 after 6000h UVA rapid aging are shown in FIG. DETAILED DESCRIPTION

[0046] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0047] The words "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0048] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers expressing, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on the desired properties to be obtained by the present invention.

[0049] It should be noted that, in the specific implementation process, the granulation device mentioned adopts a relatively mature device currently available on the market.

[0050] 4-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenol, analytical grade reagent, CAS No. 61414-16-2.

[0051] (2,2,6,6-Tetramethylpiperidin-4-yl)-methanol, analytical grade reagent, CAS No. 61171-35-5.

[0052] Fluorocarbon emulsion, brand name DF-01L.

[0053] Acrylic emulsion, Wanhua Chemical, Archso18087.

[0054] Organic amine auxiliary, 2-amino-2-methyl-1-propanol.

[0055] Thickener, TT615.

[0056] Defoamer, A-10.

[0057] Preservative, ROCIMA631.

[0058] Wetting agent, PY199.

[0059] Antifreeze, propylene glycol.

[0060] Film-forming aid, alcohol ester twelve.

[0061] Example 1

[0062] An anti-ultraviolet finishing varnish for building exterior walls, comprising the following components in parts by mass:

[0063]

[0064]

[0065] The preparation method of the above-mentioned anti-ultraviolet finish varnish for building exterior walls comprises the following steps:

[0066] S1. Dry 100 parts of nano titanium dioxide at 200° C. for 12 h, grind to 250 nm, mix with 200 parts of dimethyl sulfoxide, 0.5 parts of 10 wt% sulfuric acid solution, and 1 part of (2,2,6,6-tetramethylpiperidin-4-yl)-methanol in a high-pressure reactor, react for 24 h at a reaction temperature of 150° C. and a reaction pressure of 300 kPa, add 1 part of 4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenol, continue to react for 24 h, centrifuge and wash with deionized water, and dry at 120° C. for 12 h to obtain an anti-ultraviolet additive;

[0067] S2. Add a wetting agent, a film-forming aid, an antifreeze agent, and a defoaming agent to 1 / 3 of deionized water according to the above-mentioned mass fractions, disperse evenly, add an organic amine aid to adjust the pH to 7-8 while stirring, disperse for 3 minutes, then add a fluorocarbon emulsion and an acrylic emulsion, disperse for 3 minutes, add a thickener, disperse for 5 minutes, then add the remaining ingredients, stir for 10 minutes, and obtain the anti-ultraviolet topcoat varnish for the building exterior wall.

[0068] Example 2

[0069] An anti-ultraviolet finishing varnish for building exterior walls, comprising the following components in parts by mass:

[0070]

[0071] The preparation method of the above-mentioned anti-ultraviolet finish varnish for building exterior walls comprises the following steps:

[0072] S1. 100 parts of nano titanium dioxide are dried at 200° C. for 12 h, ground to a particle size of 300 nm, mixed with 200 parts of dimethyl sulfoxide, 0.5 parts of a 10 wt% sulfuric acid solution, and 1 part of (2,2,6,6-tetramethylpiperidin-4-yl)-methanol in a high-pressure reactor, reacted at a reaction temperature of 175° C. and a reaction pressure of 400 kPa for 24 h, added with 1 part of 4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenol, continued to react for 24 h, centrifuged and washed with deionized water, and dried at 120° C. for 12 h to obtain an anti-ultraviolet additive;

[0073] S2. Add a wetting agent, a film-forming aid, an antifreeze agent, and a defoaming agent to 1 / 3 of deionized water according to the above-mentioned mass fractions, disperse evenly, add an organic amine aid to adjust the pH to 7-8 while stirring, disperse for 3 minutes, then add a fluorocarbon emulsion and an acrylic emulsion, disperse for 3 minutes, add a thickener, disperse for 5 minutes, then add the remaining ingredients, stir for 10 minutes, and obtain the anti-ultraviolet topcoat varnish for the building exterior wall.

[0074] Example 3

[0075] An anti-ultraviolet finishing varnish for building exterior walls, comprising the following components in parts by mass:

[0076]

[0077] The preparation method of the above-mentioned anti-ultraviolet finish varnish for building exterior walls comprises the following steps:

[0078] S1. Dry 100 parts of nano titanium dioxide at 200° C. for 12 h, grind to a particle size of 450 nm, mix with 200 parts of dimethyl sulfoxide, 0.5 parts of a 10 wt% sulfuric acid solution, and 1 part of (2,2,6,6-tetramethylpiperidin-4-yl)-methanol in a high-pressure reactor, react for 24 h at a reaction temperature of 185° C. and a reaction pressure of 500 kPa, add 1 part of 4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenol, continue to react for 24 h, centrifuge and wash with deionized water, and dry at 120° C. for 12 h to obtain an anti-ultraviolet additive;

[0079] S2. Add a wetting agent, a film-forming aid, an antifreeze agent, and a defoaming agent to 1 / 3 of deionized water according to the above-mentioned mass fractions, disperse evenly, add an organic amine aid to adjust the pH to 7-8 while stirring, disperse for 3 minutes, then add a fluorocarbon emulsion and an acrylic emulsion, disperse for 3 minutes, add a thickener, disperse for 5 minutes, then add the remaining ingredients, stir for 10 minutes, and obtain the anti-ultraviolet topcoat varnish for the building exterior wall.

[0080] Comparative Example 1

[0081] The difference between Comparative Example 1 and Example 1 is that the anti-ultraviolet additive is replaced by unmodified nano titanium dioxide, and the other components and preparation method are the same as those of Example 1.

[0082] Comparative Example 2

[0083] The difference between Comparative Example 2 and Example 1 is that the anti-ultraviolet additive is replaced by a 1:1 physically mixed hindered amine light stabilizer UV-770 and an ultraviolet absorber UV-531.

[0084] Comparative Example 3

[0085] The difference between Comparative Example 3 and Example 1 is that in step S1, the mass of (2,2,6,6-tetramethylpiperidin-4-yl)-methanol is replaced by 4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenol, and the other components and preparation methods are the same.

[0086] Comparative Example 4

[0087] An existing product of an anti-ultraviolet varnish is available with the brand name F55-7.

[0088] Test Example 1

[0089] The varnishes prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests.

[0090] Test method:

[0091] Gloss: Tested according to GB / T 9754-2007.

[0092] Stain resistance: tested according to HG / T 5065-2016.

[0093] Washability: Tested according to HG / T 5065-2016.

[0094] Ultraviolet (UVA) rapid aging: tested according to GB / T 23987-2009.

[0095] Construction performance: Tested according to HG / T 5065-2016.

[0096] The test results are shown in Table 1 below.

[0097] Table 1 Performance test results of varnishes of Examples 1-3 and Comparative Examples 1-4

[0098]

[0099]

[0100] Figure 4 The results of the varnishes of Examples 1-3 and Comparative Examples 1-3 after 6000h UVA rapid aging are shown in FIG.

[0101] From the above table and Figure 4 It can be seen from the test results that the anti-ultraviolet topcoat varnish for building exterior walls provided by Examples 1-3 of the present invention has obvious performance advantages over Comparative Examples 1-4 in terms of gloss, stain resistance, washability, ultraviolet (UVA) rapid aging, and construction performance.

[0102] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0103] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An anti-ultraviolet finish varnish for building exterior walls, characterized in that: The anti-ultraviolet finish varnish for building exterior walls comprises the following components in parts by mass: Wherein, the anti-ultraviolet auxiliary agent is nano titanium dioxide grafted with hindered amine groups and triazine groups.

2. The anti-ultraviolet finish varnish for building exterior walls according to claim 1, characterized in that: The acrylic emulsion is selected from one or more of hydroxypropyl emulsion, styrene-acrylic emulsion and pure acrylic emulsion.

3. The anti-ultraviolet finish varnish for building exterior walls according to claim 1, characterized in that: The organic amine auxiliary agent is selected from one or more of 2-amino-2-methyl-1-propanol and diethanolamine.

4. The anti-ultraviolet finish varnish for building exterior walls according to claim 1, characterized in that: The auxiliary agent is selected from one or more of a thickener, a defoamer, a preservative, a wetting agent, an antifreeze agent, and a film-forming auxiliary agent.

5. The method for preparing the anti-ultraviolet finish varnish for building exterior walls according to any one of claims 1 to 4, characterized in that: The steps include: S1. The activated nano-titanium dioxide is mixed with a solvent, a hydroxyl-containing hindered amine compound, and an acid, and reacted, and then a hydroxyl-containing triazine group compound is added, and the reaction is continued, and the anti-ultraviolet additive is obtained after centrifugation, washing, and drying; S2. Add an auxiliary agent into water, add an organic amine auxiliary agent to adjust the pH, and then add the remaining ingredients to obtain the anti-ultraviolet topcoat varnish for the building exterior wall.

6. The method for preparing the anti-ultraviolet finish varnish for building exterior walls according to claim 5, characterized in that: In step S1, the activation method of the nano titanium dioxide is drying at 180-230° C. for 10-14 hours.

7. The method for preparing the anti-ultraviolet finish varnish for building exterior walls according to claim 5, characterized in that: In step S1, the acid is selected from one or more of sulfuric acid and hydrochloric acid.

8. The method for preparing the anti-ultraviolet finish varnish for building exterior walls according to claim 5, characterized in that: In step S1, the reaction temperature is 125-185°C.

9. The method for preparing the anti-ultraviolet finish varnish for building exterior walls according to claim 5, characterized in that: In step S1, the reaction pressure is 200-500 kPa.

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