Vinyl epoxy siloxane modified acrylic resin and preparation method therefor, and weather-resistant topcoat and preparation method therefor

Abstract

The present invention belongs to the technical field of coatings, and in particular discloses a vinyl epoxy siloxane modified acrylic resin and a preparation method therefor. The vinyl epoxy siloxane modified acrylic resin is a vinyl epoxy polysiloxane graft-modified acrylic resin synthesized by using styrene, an acrylate monomer with a specific composition, vinyltriisopropoxysilane, etc., as comonomers, producing a copolymer therefrom under the action of an initiator, and then grafting epoxy siloxane thereto by means of a chemical synthesis modification method. By means of a copolymerization reaction and grafting modification, the molecular chains of the resin are endowed with a relatively large number of silane branches and an appropriate amount of epoxy groups and silane groups, which are uniformly distributed, thereby increasing the glass transition temperature of the resin. Also disclosed in the present invention are a weather-resistant topcoat based on the vinyl epoxy siloxane modified acrylic resin, and a preparation method therefor. The relatively high glass transition temperature of the vinyl epoxy siloxane modified acrylic resin ensures that the weather-resistant topcoat has good self-drying performance and medium resistance.

Description

Vinyl epoxy siloxane modified acrylic resin and preparation method thereof, weather-resistant topcoat and preparation method thereof TECHNICAL FIELD

[0001] The present application belongs to the technical field of coatings, and particularly relates to a vinyl epoxy siloxane modified acrylic resin and a preparation method thereof, and a weather-resistant topcoat having the vinyl epoxy siloxane modified acrylic resin and a preparation method thereof. BACKGROUND

[0002] At present, alkyd resin and acrylic resin are commonly used in outdoor weather-resistant coatings, and the weather resistance thereof is generally maintained for about 2-3 years. The main chain of organosiloxane resin is Si-O-Si, and the bond energy of Si=O (450 kJ / mol) is greater than the bond energy of C-C (345 kJ / mol) and the bond energy of C-O (351 kJ / mol) of ordinary organic polymers. Therefore, the organosiloxane resin has excellent heat resistance and ultraviolet light aging resistance. However, the cost of pure organosiloxane resin is high, and therefore, alkyd resin and acrylic resin are often used to modify the organosiloxane resin. The organosiloxane and the acrylic resin have good miscibility, and therefore, the organosiloxane containing active groups (such as -OH) is often used to condense and modify the acrylic resin containing active groups (such as -OH and -COOH), or the organosiloxane containing unsaturated bonds is used to free-radical polymerize and modify the acrylic acid and ester monomers, so as to comprehensively utilize the weather resistance, decorative property and low cost advantage of the two.

[0003] The commonly used siloxane modified acrylic resin coating on the market has an actual service life of 5-8 years, and the paint film will be corroded and damaged. In addition, the conventional siloxane modified acrylic resin modified by the above method is generally a two-component coating during paint preparation, and the construction is relatively complicated, the adhesion of the paint film is general, and the chemical resistance and salt spray resistance are poor. At present, the labor cost is high, and frequent coating construction and maintenance can easily cause environmental pollution and safety and environmental protection problems. The epoxy siloxane is used to chemically modify the acrylic resin, the epoxy group can react with the carboxyl group in the side chain of the acrylic resin, and the acrylic resin can be used to prepare a moisture curing one-component coating. The one-component coating has excellent weather resistance, decorative property and low cost advantage, and also has the characteristics of high hardness, good adhesion and chemical resistance. Therefore, the one-component epoxy polysiloxane modified acrylic resin coating with simple construction process, long service life, excellent acid resistance, alkali resistance and water resistance is more popular.

[0004] However, the single-component epoxy polysiloxane modified acrylic resin in the current research has many disadvantages. For example, a water-soluble silicone modified acrylic resin uses various olefin monomers to react, and by means of an epoxy-siloxane chain with large steric hindrance, the epoxy group is bonded to the ethylene urea structure on the polyacrylate branched chain to improve the use amount and modification effect of the silicone, and the water dispersion has good stability. However, when the water-soluble silicone modified acrylic resin is used to form a thermosetting coating, it still needs to be mixed with an amino resin and high-temperature baking is needed to realize the curing of the paint film, and it cannot be self-dried. For another example, a photocurable composite coating printing color paste composition adds an epoxy-terminated siloxane in the color paste component to realize excellent chemical stability, weather resistance, oxidation resistance, non-yellowing, and good flexibility, but it needs to be irradiated by ultraviolet light to realize UV crosslinking and curing. In summary, the current technology of epoxy polysiloxane modified acrylic resin generally has problems such as complicated construction, high construction cost, etc.

[0005] Therefore, it is urgent to continuously improve the epoxy polysiloxane modified acrylic resin to truly promote the development of outdoor weather-resistant coatings.

[0006] SUMMARY

[0007] In order to solve the problems of the paint formed by the epoxy polysiloxane modified acrylic resin in the prior art, such as self-drying, complicated construction, and high construction cost, the present application continues to improve the technology of epoxy polysiloxane modified acrylic resin, and obtains a new vinyl epoxy siloxane modified acrylic resin. Through the selection of specific components and the reaction therebetween, the resin material has a higher glass transition temperature, thereby improving the self-drying property and medium resistance of the paint.

[0008] The specific technical solutions adopted by the present application are as follows:

[0009] A vinyl epoxy siloxane modified acrylic resin is prepared from the following raw materials in mass fraction:

[0010] and is obtained through copolymerization of styrene, acrylic ester monomers, and vinyl triisopropoxy silane, and further graft modification of epoxy siloxane.

[0011] In some preferred embodiments, the above-mentioned vinyl epoxy siloxane modified acrylic resin has the following raw materials in mass fraction:

[0012] In the above-mentioned vinyl epoxy siloxane modified acrylic resin, the acrylic ester monomers are a mixture of methyl methacrylate, butyl acrylate, and acrylic acid in a mass ratio of 22-30:8.2-14.2:0.8.

[0013] wherein the epoxy siloxane is a mixture of β-(3,4-epoxycyclohexyl)ethyl triethoxysilane and γ-glycidoxypropyl trimethoxysilane in a mass ratio of 3.75-5.15:0.25-0.55.

[0014] Further, the initiator is di-tert-butyl peroxide and / or dicumyl peroxide.

[0015] Further, the catalyst is triethylamine and / or triethanolamine.

[0016] Generally, the reaction solvent is xylene, toluene, butyl acetate, etc., which are conventional solvents that can be generally applied to the synthesis of epoxy siloxane-modified acrylic resins, and are not specifically limited herein.

[0017] The above-described vinyl epoxy siloxane-modified acrylic resin can be prepared by the following method:

[0018] In step S1, after the partial solvent is subjected to dehydration treatment, styrene, an acrylate monomer, vinyl triisopropoxysilane, and partial initiator are mixed uniformly at 120-130°C and reacted for 4-4.5 hours to obtain a copolymer.

[0019] In step S2, the remaining initiator is dissolved in the remaining solvent to form an initiator mixture, and the initiator mixture, epoxy siloxane, and catalyst are added to the copolymer, and the reaction is maintained until the acid value of the reaction system is less than 5 mg KOH / g, and the reaction is stopped to obtain a vinyl epoxy siloxane-modified acrylic resin.

[0020] Generally, in step S1, at least 80 wt% of the solvent is subjected to dehydration treatment in consideration of the water content of the solvent, which affects the subsequent reaction.

[0021] The present application also provides the use of the above-described vinyl epoxy siloxane-modified acrylic resin in paint preparation, and provides a weather-resistant topcoat, which comprises the following components in uniform mixture in mass fraction:

[0022] Further, the pigment is at least one selected from titanium dioxide, barium sulfate, chrome yellow, aluminum powder, and zinc oxide.

[0023] Further, the auxiliary agent can be at least one selected from a dispersant (for pigment wetting), a leveling agent, a UV stabilizer, and a UV absorber.

[0024] Further, the mixed solvent is xylene, toluene, butyl acetate, etc., which are conventional solvents that can be generally applied to the synthesis of weather-resistant topcoats, and are not specifically limited herein.

[0025] The pigments, the additives and the mixed solvents are selected by referring to the general components and properties of weather-resistant paint by those skilled in the art, and are not specifically limited here.

[0026] The weather-resistant topcoat can be prepared by the following method:

[0027] The vinyl epoxy siloxane modified acrylic resin, the pigments and the additives are uniformly mixed in the mixed solvents, dispersed, and ground to a fineness of 20 μm or less, and filtered to obtain the weather-resistant topcoat.

[0028] The vinyl epoxy siloxane modified acrylic resin provided by the present application is copolymerized with styrene, a specific proportion of acrylate monomers, and vinyl triisopropoxy silane as a copolymerization monomer, each of which contains an active functional group -C=C-. The copolymer is generated under the action of an initiator. The special monomer vinyl triisopropoxy silane is uniformly distributed in the molecular chain and provides more silane branched chains for the molecular backbone. Then, the epoxy siloxane is grafted under the condition of a catalyst by means of a modifier with a specific proportion, and the vinyl epoxy siloxane grafted modified acrylic resin is synthesized by a chemical synthesis modification method. The copolymerization reaction and the graft modification endow the resin molecular chain with more uniformly distributed silane branched chains, appropriate epoxy groups and silane groups, thereby improving the glass transition temperature of the resin and the self-drying property and the medium resistance of the paint prepared therefrom.

[0029] Based on this, the vinyl epoxy siloxane modified acrylic resin can be used as a base material, combined with pigments, fillers, additives and mixed solvents, and prepared into paint through processes such as dispersion and grinding. Based on the high glass transition temperature of the vinyl epoxy siloxane modified acrylic resin, the paint prepared therefrom also has strong self-drying property and medium resistance.

[0030] The vinyl epoxy siloxane modified acrylic resin has a cost advantage over pure organic siloxane resin, and compared with conventional siloxane modified acrylic resin, it can be used to prepare moisture-curing one-component paint, and the construction process is simple. The vinyl epoxy siloxane modified acrylic resin not only has excellent weather resistance, decorative properties and low cost advantage, but also has high hardness, good adhesion, excellent acid resistance, alkali resistance and water resistance. DETAILED DESCRIPTION

[0031] The raw material components and the preparation method of the vinyl epoxysiloxane-modified acrylic resin provided by the present application, and the composition and the preparation method of the weather-resistant topcoat based thereon will be described below through specific examples, but those skilled in the art will understand that the following examples are only specific examples of the vinyl epoxysiloxane-modified acrylic resin and the weather-resistant topcoat of the present application, and are not used to limit the entirety thereof. On the contrary, these examples are provided to explain the principles of the present application and its practical applications, so as to enable other skilled persons in the art to understand various embodiments of the present application and various modifications suitable for specific intended applications.

[0032] Table 1 below shows the raw material components of each of the vinyl epoxysiloxane-modified acrylic resins provided by Examples 1-11.

[0033] The preparation method of each of the vinyl epoxysiloxane-modified acrylic resins provided by Examples 1-11 is as follows:

[0034] First, nitrogen is introduced into the reaction bottle for about 10 minutes to exclude air; 90% of the reaction solvent is put into the reaction bottle, and the temperature is raised to 130-135°C to reflux and dehydrate until there is no water bead in the water separator, and then the temperature is lowered to 120-130°C and kept constant.

[0035] Then, the styrene, the acrylic monomer, the vinyl triisopropoxysilane and 90% of the initiator are mixed uniformly, and the above mixture is slowly and uniformly added at a temperature of 120-130°C, and the addition is completed in 2-2.5 hours, and the reaction is maintained at this temperature for 2 hours.

[0036] Finally, the remaining reaction solvent and initiator are mixed uniformly and slowly and uniformly added to the reaction bottle at a temperature of 120-130°C, and the addition is completed, and the reaction is maintained for another 2 hours; then the epoxy siloxane and the catalyst are added to the reaction bottle at this temperature, and the reaction is maintained until the acid value of the system is less than 5 mg KOH / g, and the vinyl epoxysiloxane-modified acrylic resin is obtained.

[0037] At the same time, in order to verify the necessity of the raw material components of the above examples, a number of comparative experiments were carried out. The raw material components of each of the comparative modified acrylic resins provided by Comparative Examples 1-11 are also listed in the table.

[0038] Table 1 Raw material components (mass parts) of each of the modified acrylic resins provided by Examples 1-11 and Comparative Examples 1-11

[0039] *: In Comparative Example 4, 20 mass parts of glycidyl acrylate are also included as the acrylic monomer.

[0040] The performance parameters of each modified acrylic resin provided by the above examples and comparative examples are shown in Table 2.

[0041] It should be noted that in each comparative example, the degree of acid value maximization of the final system is reduced, which is considered to be the end of the reaction, and may not be reduced to less than 5 mg KOH / g due to changes in substances or amounts.

[0042] Table 2 Performance parameters of each modified acrylic resin provided by Examples 1-11 and Comparative Examples 1-11

[0043] In combination with Table 1 and Table 2, it can be seen that, compared with Examples 1 and 2, Comparative Examples 1 and 2 are respectively grafted and modified with γ-glycidoxypropyltrimethoxysilane (the total number of epoxy groups is consistent with β-(3, 4-epoxycyclohexyl) ethyl triethoxysilane and γ-glycidoxypropyltrimethoxysilane in Example 1) and β-(3, 4-epoxycyclohexyl) ethyl triethoxysilane as epoxy siloxane (the total number of epoxy groups is consistent with β-(3, 4-epoxycyclohexyl) ethyl triethoxysilane and γ-glycidoxypropyltrimethoxysilane in Example 2), and the grafting rates are lower, resulting in insufficient participation of -COOH in the reaction and high resin acid value. That is, even if the same number of epoxy groups is maintained, the use of β-(3, 4-epoxycyclohexyl) ethyl triethoxysilane and γ-glycidoxypropyltrimethoxysilane as epoxy siloxane can bring higher grafting rate than the use of any single component, thereby obtaining the target product.

[0044] Compared with Example 1, Comparative Example 3 uses an equal amount of hydroxyethyl methacrylate instead of methyl methacrylate, and it can be seen that hydroxyethyl methacrylate contains active functional group -OH, which will cause the prepared paint film to be unable to dry, and a curing agent and a crosslinking agent capable of reacting with -OH need to be added to form an effective coating film.

[0045] Compared with Example 1, Comparative Example 4 increases glycidyl acrylate as an acrylic ester monomer (i.e., including methyl methacrylate, butyl acrylate, acrylic acid, and glycidyl acrylate), and replaces the epoxy siloxane with an epoxy-terminated silane (a straight-chain polysiloxane with epoxy groups at both ends of the molecular chain, and the molecular weight is 2000). Glycidyl acrylate participates in the double bond -C=C- polymerization reaction in the reaction stage, and the epoxy group reacts with -COOH in acrylic acid, resulting in a resin with a low acid value, and a cross-linked polymer is formed, the resin has a large molecular weight, a high viscosity, and a high T g g, which will result in a brittle paint film.

[0046] Comparative Example 5 uses 3-methacryloxypropyltrimethoxysilane (a conventional organosilane or organosiloxane) instead of the epoxy siloxane of Example 1, which does not contain active groups capable of reacting with -COOH and cannot be effectively grafted and modified, ultimately resulting in a resin with a high acid value and a large number of residual polar groups in the molecular chain, which can result in poor dryness and poor medium resistance of the paint film.

[0047] Comparative Examples 6 and 7 use 3-aminopropyltriethoxysilane instead of the epoxy siloxane of Example 1, which does not contain a double bond group -C=C- and cannot undergo addition polymerization with styrene and acrylate monomers, thus resulting in uneven distribution of silane groups on the main chain of the acrylic double bond, ultimately resulting in a resin with a high acid value.

[0048] Comparative Examples 8 and 9 use a small amount and a large amount of vinyl triisopropyl silane, respectively, instead of the epoxy siloxane of Example 1. Comparative Example 8 generates a molecular main chain containing a small amount of vinyl triisopropyl silane, resulting in a resin with low viscosity; and Comparative Example 9 generates a molecular main chain containing a large amount of vinyl triisopropyl silane, resulting in a resin with a low T g g, high viscosity, and poor dryness.

[0049] Comparative Example 10 uses a small amount of epoxy silane instead of the epoxy siloxane of Example 1, which results in a small amount of -COOH reacting with it and cannot be effectively grafted and modified, ultimately resulting in a resin with a high acid value, poor dryness, and poor medium resistance of the paint film.

[0050] Comparative Example 11 uses a large amount of epoxy silane instead of the epoxy siloxane of Example 1, which results in crosslinking with -COOH, a resin with high viscosity, a small amount of residual polar groups -COOH, a brittle paint film, and poor adhesion.

[0051] The vinyl epoxy siloxane modified acrylic resin provided by each of the above embodiments can be applied to paint and can obtain a self-drying weatherable topcoat due to its high glass transition temperature.

[0052] The following application examples 1-11 provide weatherable topcoats based on the vinyl epoxy siloxane modified acrylic resin provided by the above embodiments, and the compositions are shown in Table 3.

[0053] At the same time, in order to illustrate the effect of the vinyl epoxy siloxane modified acrylic resin on the performance of the weatherable topcoat, the comparative modified acrylic resins provided by Comparative Examples 1-11 are also prepared into comparative topcoats using the same method, and the compositions of Comparative Examples 1-11 are also listed in Table 3 below.

[0054] Each of the topcoats provided by application examples 1-11 and application comparative examples 1-11 is prepared using the following method:

[0055] The modified acrylic resin from the corresponding example or comparative example was uniformly mixed and dispersed in the mixed solvent with pigments, auxiliaries, ground to a fineness of less than 20 μm, and filtered to obtain the topcoat.

[0056] Table 3 Composition (parts by mass) of each topcoat provided by application examples 1-11 and application comparative examples 1-11

[0057] The topcoats in each of the above application examples and application comparative examples were sprayed or brushed onto a board, and after 7 days of room temperature curing, performance testing was performed. The performances are shown in Tables 4 and 5, respectively.

[0058] Table 4 Performance of each topcoat provided by application examples 1-11

[0059] Table 5 Performance of each topcoat provided by application comparative examples 1-11

[0060] By comparing the performances of each topcoat in Tables 4 and 5, it can be seen that the vinyl-epoxy-siloxane modified acrylic resin provided by each example uses styrene, acrylic ester monomers of a specific ratio, and vinyl triisopropoxy silane as comonomers, each of which contains active functional groups -C=C-. The copolymer is generated under the action of di-t-butyl peroxide initiator. The special monomer vinyl triisopropoxy silane can be uniformly distributed in the molecular chain and provide more silane-containing branched chains for the molecular backbone. The epoxy-siloxane of a specific ratio is a modifier, which is synthesized by a chemical modification method under the condition of a catalyst to synthesize the vinyl-epoxy-siloxane grafted modified acrylic resin. Through copolymerization and graft modification, the resin molecular chain is endowed with more uniformly distributed silane branched chains, appropriate epoxy groups, and silane groups, thereby improving the glass transition temperature of the resin.

[0061] Application examples 1-11 use the above vinyl-epoxy-siloxane grafted modified acrylic resin as a base material, which is combined with pigments, fillers, solvents, and auxiliaries through dispersion, grinding, and other processes to prepare paint, and is used to prepare moisture-cured one-component coatings, which have excellent weather resistance, high hardness, good adhesion, excellent acid resistance, alkali resistance, and water resistance, and other characteristics.

[0062] Application comparative examples 1-2 use the comparative modified acrylic resins prepared in comparative examples 1-2 as base materials. Both of these two types of comparative modified acrylic resins have low grafting rates and high acid values, which result in insufficient participation of -COOH in the reaction. Therefore, the paint films prepared using the comparative modified acrylic resins in application comparative examples 1-2 have decreased adhesion, acid resistance, alkali resistance, salt mist resistance, artificial accelerated aging resistance, and water resistance.

[0063] Application Comparative Example 3 uses the comparative modified acrylic resin prepared in Application Comparative Example 3 as a base material. The comparative modified acrylic resin is synthesized using hydroxyethyl methacrylate and other monomers, and the resin molecular chain contains a hydroxyl active functional group. The paint film prepared therefrom cannot be surface dried and air dried at room temperature, and cannot form an effective paint film coating. It needs to be combined with additional additives such as curing agents and crosslinking agents that can react with the hydroxyl group to be able to be applied.

[0064] Application Comparative Example 4 uses the comparative modified acrylic resin prepared in Application Comparative Example 4 as a base material. The comparative modified acrylic resin is synthesized and modified using glycidyl acrylate and an epoxy-silane. The epoxy and silane groups cannot be uniformly distributed in the resin molecular chain. Glycidyl acrylate participates in the double bond-C=C- polymerization reaction in the reaction stage, and the epoxy group reacts with the-COOH in the acrylic acid to form a crosslinked polymer. The paint film prepared therefrom is brittle, and has poor impact resistance, adhesion, and other properties.

[0065] Application Comparative Example 5 uses the comparative modified acrylic resin prepared in Application Comparative Example 5 as a base material. The comparative modified acrylic resin is modified using 3-methacryloyloxypropyl trimethoxysilane. First, it does not contain an active functional group-C=C- to participate in the copolymerization of monomers, and the silane group cannot be uniformly distributed in the resin molecular chain. Second, it does not contain an active group to react with-COOH, and cannot be effectively grafted and modified. Third, the acid value of the comparative modified acrylic resin obtained is high, and-COOH is a polar hydrophilic group. The paint film prepared therefrom has poor acid resistance, alkali resistance, salt spray resistance, artificial accelerated aging resistance, water resistance, and other properties.

[0066] Application Comparative Examples 6-7 use the comparative modified acrylic resins prepared in Application Comparative Examples 6-7 as base materials. The silane monomer used in Application Comparative Examples 6-7 is 3-aminopropyl triethoxysilane, which does not contain a double bond group-C=C-, and cannot undergo addition polymerization with styrene and acrylate monomers, resulting in the silane group not being uniformly distributed on the acrylic double bond backbone. As a result, the paint film prepared in Application Comparative Examples 6-7 has decreased acid resistance, alkali resistance, salt spray resistance, artificial accelerated aging resistance, water resistance, and other properties.

[0067] Application Comparative Example 8 and Application Comparative Example 9 use the comparative modified acrylic resins prepared in Application Comparative Example 8 and Application Comparative Example 9 as base materials. Application Comparative Example 8 and Application Comparative Example 9 use less and more vinyl triisopropoxysilane, respectively. Application Comparative Example 8 generates a molecular backbone containing less vinyl triisopropoxysilane, and the resin has low viscosity. The paint film prepared therefrom has poor salt spray resistance and artificial accelerated aging resistance. Application Comparative Example 9 generates a molecular backbone containing more vinyl triisopropoxysilane, and the resin has low T g g, and high viscosity. The paint film prepared therefrom has poor dryness and wear resistance.

[0068] Application Comparative Example 10 uses the comparative modified acrylic resin prepared in Comparative Example 10 as the base material. The resin prepared in Comparative Example 10 contains a small proportion of epoxy silane, and the -COOH reacts less, which cannot effectively graft modification, eventually leading to the acid value of the obtained resin being too high, resulting in poor acid, alkali, water and other medium resistance of the paint film.

[0069] Application Comparative Example 11 uses the comparative modified acrylic resin prepared in Comparative Example 11 as the base material. The resin prepared in Comparative Example 11 contains a large proportion of epoxy silane, which crosslinks with -COOH, and the resin viscosity is too high, and the residual amount of polar group -COOH is small, the paint film is brittle, resulting in poor impact resistance and adhesion.

[0070] It should be noted that although in the above application examples 1-11, the auxiliary agents are all mixtures of three or four of dispersants, leveling agents, UV stabilizers and UV absorbers, but those skilled in the art will understand that these several components in the topcoat all belong to conventional components, and those skilled in the art can select to add any one or at least two combinations of them according to the specific actual needs.

[0071] Although the present application has been shown and described with reference to certain embodiments thereof, it is understood that various changes in form and detail can be made therein without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.

Claims

1. A vinyl epoxide siloxane modified acrylic resin characterized by, By using the following raw materials by mass parts: and further grafted with the epoxy siloxane to obtain; The acrylic monomer is a mixture of methyl methacrylate, butyl acrylate and acrylic acid in a mass ratio of 22-30:8.2-14.2:0.8; and the epoxy siloxane is a mixture of β-(3,4-epoxycyclohexyl) ethyl triethoxysilane and γ-glycidyl ether propyl trimethoxysilane in a mass ratio of 3.75-5.15:0.25-0.

55.

2. The vinyl epoxysiloxane modified acrylic resin according to claim 1, characterized in that, The vinyl epoxide siloxane modified acrylic resin has the following raw materials by mass fraction:

3. The vinyl epoxysiloxane modified acrylic resin according to claim 1 or 2, characterized in that, The initiator is di-t-butyl peroxide and / or diisopropylbenzene peroxide.

4. The vinyl epoxysiloxane modified acrylic resin according to claim 1 or 2, characterized in that, The catalyst is triethylamine and / or triethanolamine.

5. The vinyl epoxysiloxane modified acrylic resin according to claim 1 or 2, characterized in that, The reaction solvent is at least one selected from dimethylbenzene, toluene and butyl acetate.

6. The method for preparing a vinyl epoxysiloxane modified acrylic resin according to any one of claims 1 to 5, characterized by, The method comprises the steps of: S1, after the partial solvent is treated by dehydration, the styrene, the acrylic monomer, the vinyl triisopropoxy silane and the partial initiator are mixed uniformly at 120-130 DEG C and reacted for 4-4.5 hours to obtain a copolymer; S2, the residual initiator is dissolved in the residual solvent to form an initiator mixture, the initiator mixture, the epoxy siloxane and the catalyst are added to the copolymer, and the reaction is carried out until the acid value of the reaction system is less than 5 mg KOH / g, the reaction is stopped, and the vinyl epoxy siloxane modified acrylic resin is obtained.

7. The production method according to claim 6, wherein In the step S1, at least 80 wt% of the solvent is treated by dehydration.

8. A weatherable topcoat characterized by, The following components are mixed homogeneously in parts by mass: The acrylic resin is the vinyl epoxy siloxane modified acrylic resin according to any one of claims 1-5.

9. The weatherable topcoat of claim 8, wherein, The pigment is at least one selected from titanium white, barium sulfate, chrome yellow, aluminum powder and zinc oxide; the auxiliary agent is at least one selected from a dispersing agent, a leveling agent, a UV stabilizer and a UV absorber; and the mixed solvent is at least one selected from dimethylbenzene, toluene and butyl acetate.

10. The method for preparing a weatherable topcoat according to claim 8 or 9, characterized in that, The method comprises the steps of: uniformly mixing the vinyl epoxy siloxane modified acrylic resin, the pigment and the auxiliary agent in the mixed solvent, dispersing and grinding to a fineness of 20 μm or less, and filtering to obtain the product. The method comprises the steps of: uniformly mixing the vinyl epoxy siloxane modified acrylic resin, the pigment and the auxiliary agent in the mixed solvent, dispersing and grinding to a fineness of 20 μm or less, and filtering to obtain the product.

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