Uvioresistant finishing varnish for building facades and process for its preparation

Abstract

The application relates to a kind of anti-UV finishing varnish for building outer wall, the anti-UV finishing varnish for building outer wall includes fluorocarbon emulsion, acrylic emulsion, anti-UV auxiliary agent, organic amine auxiliary agent, auxiliary agent, water;In the application, fluorocarbon emulsion, acrylic emulsion and anti-UV auxiliary agent are compounded, the anti-UV auxiliary agent is respectively introduced triazine ultraviolet light absorbing group and hindered amine group on nano-titanium dioxide.The application can effectively solve the problem of poor utilization efficiency caused by different action positions of hindered amine light stabilizer and ultraviolet absorber, and avoids the migration and loss of the two in the paint film;In addition, nano-titanium dioxide grafted with triazine ultraviolet light absorbing group and hindered amine group can reduce the hydroxyl group density on the surface of nano-titanium dioxide, avoid the agglomeration of nano-titanium dioxide, thereby improve the compatibility and dispersibility of nano-titanium dioxide in the component, and improve the rigidity of the varnish, greatly improve the scrub resistance of the paint film.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building technology, in particular to an anti-ultraviolet finishing varnish for building outer walls and a preparation method thereof. BACKGROUND

[0002] Ultraviolet light is a kind of electromagnetic radiation with shorter wavelength than visible light. According to the wavelength, it can be divided into three main types: ultraviolet A band (UVA), ultraviolet B band (UVB) and ultraviolet C band (UVC). The shorter the wavelength, the higher the energy. Among them, UVA has the longest wavelength, UVB has the second longest wavelength, and UVC has the shortest wavelength, but the atmosphere has a high absorption effect on it, and has less impact on the ground. Ultraviolet light has many sources, and the photochemical aging of varnish is mainly caused by solar radiation.

[0003] Protection against ultraviolet light is related to environmental safety, resource conservation and human health. In order to improve the protection level of ultraviolet light, at present, anti-ultraviolet coatings have been widely used in the fields of building glass and automobile glass, but the requirement for anti-aging performance of building outer walls, which also faces severe aging environment, has long been overlooked by people. The photoaging of outer wall not only causes the varnish to powder, crack and fall off, but also causes the stain resistance to decrease, resulting in the deterioration of the appearance of the outer wall and even irreparable damage.

[0004] Enhancing the anti-aging performance of building outer walls can use functional anti-ultraviolet finish, but due to the complexity of the finish composition, considering the possible antagonistic effect, the selection and addition of anti-aging additives have strict requirements, and due to the diversity of the finish such as flat coating and thick paste, the addition of anti-ultraviolet additives is inconvenient, complex and inefficient.

[0005] By enriching the functionality of the finishing varnish, developing a finishing varnish with anti-aging performance not only has the effect of shielding ultraviolet light, but also is convenient to construct, and is more efficient and broad-spectrum than developing anti-ultraviolet finish, and has excellent convenience and applicability. Developing functional building outer wall finishing has many benefits, such as: (1) improving building performance: functional outer wall finishing can improve the performance of buildings, such as thermal insulation, waterproofing, sound insulation, etc. These functions can improve the comfort and sustainability of buildings, reduce energy consumption, and reduce the impact on the environment; (2) enhancing the appearance of buildings: functional outer wall finishing can add unique features and styles to buildings; (3) improving indoor environmental quality: some functional outer wall finishing can help improve indoor air quality, such as dustproof, antibacterial, air purification, etc.; (4) prolonging the service life of buildings: functional outer wall finishing can provide an additional protective layer to prevent buildings from being damaged by external environment, prolonging the service life of buildings.

[0006] Current building exterior wall finishes are largely focused on basic, monotonous functional properties: simply providing the paint film properties necessary for a given finish, while neglecting additional functional attributes. For exterior wall clearcoat systems, which hold great market potential, overly monotonous performance undoubtedly significantly impacts resource utilization, indirectly increasing production and operating costs, negatively impacting the development of both the finish and the overall exterior wall clearcoat system. To achieve a breakthrough, the finish clearcoat system must be endowed with advanced functional attributes.

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

[0008] (1) Based on the film-forming material, i.e., the resin emulsion level: In the existing technology, due to the high requirements of the functional cover for the film-forming material, the use of a single emulsion at this stage 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 compounding is inefficient and cannot be self-consistent. In essence, it lacks theoretical explanation assistance at the micro-nano level.

[0009] (2) Based on the level of anti-UV additives: Although the functionality of building exterior wall coverings needs to be developed, we can get a glimpse of the situation from functional anti-UV glass exterior walls and automotive coatings. The current development of anti-UV coatings tends to use hindered amine light stabilizers alone or ultraviolet 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 absorbers, and the other is to compound organic anti-UV additives with inorganic anti-UV additives. This strategy has significantly improved the effect compared to the traditional single-combination, but there are still disadvantages: the anti-UV compound products of anti-UV additive manufacturers are limited in application scenarios. With the iterative upgrade 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; the coating companies' independent compounding has the disadvantages of low efficiency, extended R&D cycle, and blind compounding.

[0010] The above two cases are simple physical compounding, and there are several disadvantages, such as Figure 1As shown in the figure, (1) the dispersibility is poor, which greatly affects the actual weather resistance 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 effects of the ultraviolet light absorber dispersed on the surface of the varnish and the hindered amine light stabilizer dispersed inside the varnish are greatly limited; (3) as time goes by, the small molecule organic anti-ultraviolet additives will gradually migrate and lose, which greatly affects the weather resistance of the paint film.

[0011] In summary, there is an urgent need 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-UV topcoat varnish for building exterior walls to overcome the shortcomings of existing technologies. This technical solution significantly improves the dispersibility of anti-UV additives, effectively improves the utilization efficiency of hindered amine light stabilizers and UV 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 mass:

[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, which can achieve the regulation of the paint film gloss 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 defoaming agent, 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 lauryl, 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 paint film flexibility 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 emulsion is difficult to apply and does 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 bond, 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 and 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 in the figure, 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 onto the nano-TiO2, its 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 the reaction is then performed. A hydroxyl-containing triazine group compound is added, and the reaction is continued. The reaction is centrifuged, washed, and dried to obtain an anti-UV additive.

[0034] S2. Add an additive to water, add an organic amine additive 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 compound of fluorocarbon emulsion, acrylic emulsion and anti-UV auxiliary agent. The anti-UV auxiliary agent is a modified nano titanium dioxide introduced with triazine ultraviolet light absorbing groups and hindered amine groups, which can effectively solve the problem of poor utilization efficiency of hindered amine light stabilizers and ultraviolet absorbers due to different action positions, and avoid 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 nano titanium dioxide, the agglomeration of nano titanium dioxide is avoided, thereby improving the compatibility and dispersibility of nano titanium dioxide in the varnish composition, further improving the rigidity of the varnish, and greatly improving the scrub resistance of the paint film.

[0041] 2. The present application realizes the adjustment of gloss by using fluorocarbon emulsion and acrylic emulsion compounding, and has excellent stain resistance, the acrylic emulsion can dilute the strength of fluorine-fluorine strong hydrogen bond in the fluorocarbon emulsion, while introducing relatively weak fluorine-hydroxyl weak hydrogen bond, reducing the cohesive force of varnish without losing the compactness of paint film, thereby improving flexibility; also by adjusting the surface energy of the paint film, the stain resistance is improved. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 Schematic diagram of the existing problems of the anti-ultraviolet additive in the varnish of the prior art;

[0043] Figure 2 Schematic diagram of the principle of compounding fluorocarbon emulsion and acrylic emulsion in the present application;

[0044] Figure 3 Reaction principle diagram of modified nano titanium dioxide in examples 1-3;

[0045] Figure 4 Result diagram of varnish in examples 1-3 and comparative examples 1-3 after 6000h UVA rapid aging. DETAILED DESCRIPTION

[0046] In order to more clearly illustrate the technical solutions of the present application, the following examples are listed. The raw materials, reactions and post-treatment means appearing in the examples are all common raw materials on the market and technical means familiar to those skilled in the art, unless otherwise stated.

[0047] The words "preferred", "preferably", "more preferred" and the like in the present application refer to the embodiments of the present application which can provide certain beneficial effects in certain cases. However, other embodiments can also be preferred in the same or other cases. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not usable, nor is it intended to exclude other embodiments from the scope of the present application.

[0048] It should be understood that, except in any operating examples, or otherwise indicated, all numbers appearing in the specification and claims, such as those expressing amounts of ingredients, are to be understood as approximations based on the desired properties sought to be obtained by the application. Therefore, unless otherwise indicated, numerical parameters in the specification and the attached claims are approximations that vary in different instances based on the desired properties sought to be obtained by the application.

[0049] It should be noted that in the specific implementation process, the mentioned granulating device adopts the existing mature device on the market.

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

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

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

[0053] Acrylic emulsion, Wanhua Chemical, Archso18087.

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

[0055] Thickener, TT615.

[0056] Defoaming agent, A-10.

[0057] Preservative, ROCIMA631.

[0058] Wetting agent, PY199.

[0059] Antifreeze, propylene glycol.

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

[0061] Example 1

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

[0063]

[0064]

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

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

[0067] S2. According to the above mass fraction, the wetting agent, the film forming aid, the antifreezing agent, the defoaming agent are added into 1 / 3 of the deionized water, uniformly dispersed, the organic amine aid is added under stirring to adjust the pH to 7-8, dispersed for 3 min, the fluorocarbon emulsion, the acrylic emulsion are added, dispersed for 3 min, the thickening agent is added, dispersed for 5 min, the remaining ingredients are added, stirred for 10 min, to obtain the anti-ultraviolet finishing varnish for building exterior wall.

[0068] Example 2

[0069] An anti-ultraviolet finishing varnish for building exterior wall comprises the following components in mass fraction:

[0070]

[0071] The preparation method of the anti-ultraviolet finishing varnish for building exterior wall comprises the following steps:

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

[0073] S2. According to the above mass fraction, the wetting agent, the film forming aid, the antifreezing agent, the defoaming agent are added into 1 / 3 of the deionized water, uniformly dispersed, the organic amine aid is added under stirring to adjust the pH to 7-8, dispersed for 3 min, the fluorocarbon emulsion, the acrylic emulsion are added, dispersed for 3 min, the thickening agent is added, dispersed for 5 min, the remaining ingredients are added, stirred for 10 min, to obtain the anti-ultraviolet finishing varnish for building exterior wall.

[0074] Example 3

[0075] An anti-ultraviolet finishing varnish for building exterior wall comprises the following components in mass fraction:

[0076]

[0077] The preparation method of the anti-ultraviolet finishing varnish for building exterior wall comprises the following steps:

[0078] S1. 100 parts of nano-titanium dioxide were dried at 200 ° C for 12 hours, ground to a particle size of 450 nm, and 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 an autoclave. The mixture was reacted at a reaction temperature of 185 ° C and a reaction pressure of 500 kPa for 24 hours. 1 part of 4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenol was added and the reaction was continued for 24 hours. The mixture was centrifuged and washed with deionized water and dried at 120 ° C for 12 hours to obtain an anti-UV 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 them evenly, add an organic amine additive while stirring to adjust the pH to 7-8, 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, and stir for 10 minutes to obtain the anti-UV 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 and other qualities are replaced by unmodified nano titanium dioxide, and the other ingredients and preparation methods 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-UV auxiliary agent is replaced by a 1:1 physical mixture of hindered amine light stabilizer UV-770 and 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 UV resistant varnish is brand 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.

[0101] From the above table and Figure 4 It can be seen from the test results that the anti-UV 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, wash resistance, rapid aging of ultraviolet (UVA), 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 invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0103] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method 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 can also be appropriately combined to form other implementation methods 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: 40-45 parts of fluorocarbon emulsion 55-60 parts of acrylic emulsion 0.6-0.8 parts of anti-ultraviolet additive 0.05-0.15 parts of organic amine additives 0.1-10 parts of additives 40-45 parts water; 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 defoaming agent, 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 the reaction is then performed. A hydroxyl-containing triazine group compound is added, and the reaction is continued. The reaction is centrifuged, washed, and dried to obtain an anti-UV additive. S2. Add the additive to water, add an organic amine additive to adjust the pH, and then add the remaining components 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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