An acrylate-modified alkyd self-crosslinking resin emulsion, its preparation method and application

Abstract

This application relates to the technical field of aqueous resin emulsions, and specifically discloses an acrylate-modified alkyd self-crosslinking resin emulsion, a preparation method thereof, and an application. The acrylate-modified alkyd self-crosslinking resin emulsion is mainly made from the following raw materials: an aqueous alkyd resin prepolymer, a neutralizing agent, an acrylate monomer, acrylic acid, styrene, a self-crosslinking monomer A, a self-crosslinking monomer B, an initiator, a co-initiator, and deionized water; the self-crosslinking monomer A is one or more of diacetone acrylamide, glycidyl methacrylate, and ethylene glycol methylacetoacetate methacrylate; the self-crosslinking monomer B is one or more of adipic dihydrazide, carbonic dihydrazide, oxalic dihydrazide, succinic dihydrazide, and ethylenediamine. This acrylate-modified alkyd self-crosslinking resin emulsion can form a dense paint film, and has the advantages of short paint film drying time, high hardness, and good salt spray corrosion resistance, meeting the market demand.

Description

Technical Field

[0001] The present application relates to the technical field of water-based resin emulsions, and more specifically, to an acrylate-modified alkyd self-crosslinking resin emulsion and a preparation method and application thereof. Background Art

[0002] Corrosion is a common phenomenon in nature, which poses a serious threat to people's daily life and production, especially to components in harsh environments, such as bridges, vehicles, airplanes, electric lock workshops, etc. Coating protective coatings on the surface of components and forming a paint film after drying can effectively reduce the corrosion of components.

[0003] As people's awareness of environmental protection continues to increase, protective coatings used for steel structures have also changed from oil-based to water-based. Water-based alkyd resin protective coatings are synthetic resin coatings with alkyd resin as the main film-forming substance. They have the advantages of bright and plump paint films and convenient construction. They have always been favored and widely used. When alkyd resin is used, it is first neutralized with amines to generate salts, then diluted with water, and then additives are added to obtain water-based alkyd resin protective coatings. The applicant found in actual use that the water-based alkyd resin protective coating has a slow drying speed, a soft paint film, and poor resistance to salt spray corrosion. Summary of the invention

[0004] In order to improve the drying speed, hardness and salt spray corrosion resistance of water-based anti-corrosion paint, the present application provides an acrylate-modified alkyd self-crosslinking resin emulsion and a preparation method and application thereof.

[0005] In a first aspect, the present application provides an acrylate-modified alkyd self-crosslinking resin emulsion, which adopts the following technical solution:

[0006] An acrylate-modified alkyd self-crosslinking resin emulsion is mainly prepared from the following raw materials in parts by weight: 15 parts of a waterborne alkyd resin prepolymer, 1-2 parts of a neutralizer, 18-22 parts of an acrylate monomer, 0.4-0.6 parts of acrylic acid, 10.2-14.8 parts of styrene, 0.5-1.5 parts of a self-crosslinking monomer A, 0.3-0.7 parts of a self-crosslinking monomer B, 0.1-0.3 parts of an initiator, 0.05-0.15 parts of a co-initiator, and 47-50 parts of deionized water;

[0007] The self-crosslinking monomer A is one or more of diacetone acrylamide, glycidyl methacrylate, and ethylene glycol acetoacetate;

[0008] The self-crosslinking monomer B is one or more of adipic acid dihydrazide, carbonate dihydrazide, oxalic acid dihydrazide, succinic acid dihydrazide and ethylenediamine.

[0009] The alkyd self-crosslinking resin emulsion of the present application is applied to a waterborne anticorrosive paint. The surface drying time of the waterborne anticorrosive paint is ≤10 min, the adhesion grade is ≥1 level, the pencil hardness is ≥H, and the neutral salt spray resistance time is ≥230 h. It shows the advantages of short drying time, high film hardness, and good salt spray resistance, meeting the market demand.

[0010] Styrene, acrylate monomer, and self-crosslinking monomer A are introduced into the waterborne alkyd resin prepolymer. Its molecular structure contains double bonds. Under the action of an initiator and a co-initiator, it is grafted onto the waterborne alkyd resin prepolymer. Through the synergistic effect between the waterborne alkyd resin prepolymer and polyacrylate, the pencil hardness and salt spray corrosion resistance of the alkyd self-crosslinking resin emulsion are effectively increased. In addition, the self-crosslinking monomer A also contains a crosslinking group. At this time, self-crosslinking monomer B is added. Self-crosslinking monomer B contains two crosslinking groups, and it can crosslink with the crosslinking group of self-crosslinking monomer A. At this time, stable self-crosslinking groups and oxidative crosslinking double bond groups exist in the alkyd self-crosslinking resin emulsion. During the film-forming process of the alkyd self-crosslinking resin emulsion, as the neutralizing agent and deionized water in the system volatilize, the pH value gradually decreases. Adjacent waterborne alkyd resin prepolymers can undergo oxidative crosslinking through their own double bonds. At the same time, the self-crosslinking monomer A grafted on adjacent waterborne alkyd resin prepolymers can also undergo self-crosslinking through self-crosslinking monomer B, that is, double crosslinking occurs during the film-forming process, greatly improving the denseness of the paint film. The high-density paint film can enhance the hardness and also prevent the penetration and corrosion of salts, enhancing the corrosion resistance of the alkyd self-crosslinking resin emulsion and the waterborne anticorrosive paint, and expanding the application range.

[0011] Optionally, the self-crosslinking monomer A is ethylene glycol methacrylate acetoacetate; the self-crosslinking monomer B is adipic dihydrazide.

[0012] Ethylene glycol methacrylate acetoacetate contains a diketone carbonyl group, and adipic dihydrazide contains a hydrazide group, and the two can undergo a crosslinking reaction. Moreover, ethylene glycol methacrylate acetoacetate also contains a methylene group, which has a weak acidic effect and can effectively enhance the bonding strength between raw materials and between raw materials and the substrate, enhancing the salt spray corrosion resistance of the alkyd self-crosslinking resin emulsion.

[0013] Optionally, the acrylate monomer is one or more of methyl methacrylate, butyl acrylate, and isooctyl acrylate.

[0014] Optionally, the waterborne alkyd resin prepolymer is mainly made from the following raw materials in parts by weight: 15 - 23 parts of vegetable oil fatty acid, 25 - 33 parts of acid anhydride, 15 - 23 parts of polyol, 1 - 4 parts of xylene, 15 - 30 parts of ethylene glycol monobutyl ether, and 4 - 10 parts of benzoic acid.

[0015] By adopting the above technical solution, the raw materials and their ratios of the waterborne alkyd resin are optimized, and the vegetable oil fatty acid, anhydride, and polyol are made to react to obtain a waterborne alkyd resin prepolymer. Benzoic acid is added to the raw materials. As a small molecule monobasic acid, it can adjust the functionality of the waterborne alkyd resin prepolymer, reduce the spatial shielding of free hydroxyl groups, improve the reaction activity of hydroxyl groups in grafting, accelerate the curing reaction rate, and improve the performance of the waterborne alkyd resin prepolymer.

[0016] Optionally, the vegetable oil fatty acid is one or more of soybean oleic acid, linolenic acid, dehydrated castor oil acid;

[0017] The anhydride is one or more of phthalic anhydride, trimellitic anhydride, maleic anhydride, acetic anhydride;

[0018] The polyol is one or more of ethylene glycol, propylene glycol, butylene glycol, hexanediol, neopentyl glycol, dipropylene glycol, glycerol, pentaerythritol.

[0019] By adopting the above technical solution, the vegetable oil fatty acid, anhydride, and polyol are optimized, which is convenient for the selection of vegetable oil fatty acid, anhydride, and polyol.

[0020] Optionally, the waterborne alkyd resin prepolymer is prepared by the following method: Mix the vegetable oil fatty acid, anhydride, polyol, xylene, and benzoic acid, heat up to 150 - 170 °C to start refluxing, continue to heat up to 230 - 250 °C, keep the temperature for reaction for 3 - 4 h. After detecting that the acid value is 35 ± 2, distill off xylene under reduced pressure, cool down to 140 - 160 °C, and add ethylene glycol monobutyl ether for mixing to obtain the waterborne alkyd resin prepolymer.

[0021] By adopting the above technical solution, it is convenient for the preparation of the waterborne alkyd resin prepolymer.

[0022] Furthermore, in the preparation method of the waterborne alkyd resin prepolymer, after starting refluxing, heat up to 230 - 250 °C at a rate of 5 - 15 °C / h. In an example and a comparative example, heat up to 240 °C at a rate of 10 °C / h.

[0023] Optionally, the initiator is one or more of ammonium persulfate, potassium persulfate, sodium persulfate;

[0024] The co - initiator is one or more of tert - butyl hydroperoxide, benzoyl peroxide, tert - butyl peroxybenzoate, sodium bisulfite, potassium bisulfite, sodium sulfate, vitamin C;

[0025] The neutralizer is one or more of ammonia water, N,N - dimethylethanolamine, triethylamine.

[0026] By adopting the above technical solutions, the initiator, co-initiator, and neutralizer are optimized, facilitating the selection of the initiator, co-initiator, and neutralizer.

[0027] Furthermore, the initiator is sodium persulfate, the co-initiators are tert-butyl hydroperoxide and vitamin C, the neutralizer is ammonia water, and the mass concentration of ammonia water is 25%.

[0028] In a second aspect, the present application provides a method for preparing the acrylate-modified alkyd self-crosslinking resin emulsion described above, adopting the following technical solutions:

[0029] A method for preparing the acrylate-modified alkyd self-crosslinking resin emulsion described above includes the following steps:

[0030] Mix styrene, acrylic acid, acrylate monomers, and self-crosslinking monomer A to obtain premix A for standby.

[0031] Mix the initiator and the first portion of deionized water to obtain premix B for standby.

[0032] Mix self-crosslinking monomer B and the second portion of deionized water to obtain premix C for standby.

[0033] Under continuous stirring, mix the aqueous alkyd resin prepolymer, neutralizer, and the third portion of deionized water, heat up to 80 - 90 °C, and simultaneously dropwise add premix A and premix B respectively. Premix A is added dropwise within 2 - 3 h, and premix B is added dropwise within 2 - 3 h. After the dropwise addition is completed, carry out heat preservation and stirring treatment for 0.5 - 1.5 h, add the co-initiator, continue heat preservation and stirring treatment for 0.5 - 1.5 h, cool down to 30 - 50 °C, add premix C for mixing, and add the remaining deionized water for mixing to obtain the acrylate-modified alkyd resin self-crosslinking emulsion.

[0034] First, add the neutralizer and deionized water to the aqueous alkyd resin prepolymer to form a salt, then add styrene, acrylic acid, acrylate monomers, and self-crosslinking monomer A, and carry out a grafting reaction under the action of the initiator and co-initiator. Then add self-crosslinking monomer B to obtain the acrylate-modified alkyd self-crosslinking resin emulsion, facilitating the preparation and control of the resin emulsion anticorrosive paint.

[0035] The usage amount of the first portion of deionized water is 5 - 15 wt% of the total amount of deionized water; the usage amount of the second portion of deionized water is 5 - 15 wt% of the total amount of deionized water; the usage amount of the third portion of deionized water is 50 - 70 wt% of the total amount of deionized water.

[0036] In a third aspect, the present application provides an aqueous anticorrosive paint for steel structures, adopting the following technical solutions:

[0037] An aqueous anti-corrosion paint for steel structures, the raw materials of which include an alkyd self-crosslinking resin emulsion, and the alkyd self-crosslinking resin emulsion is the acrylate-modified alkyd self-crosslinking resin emulsion described above.

[0038] Optionally, the aqueous anti-corrosion paint is mainly made of the following raw materials in parts by weight: deionized water 10 - 18 parts, acrylate-modified alkyd self-crosslinking resin emulsion 40 - 50 parts, dispersant 0.3 - 0.8 parts, defoamer 0.05 - 0.3 parts, barium sulfate 20 - 30 parts, titanium dioxide 5 - 15 parts, wetting agent 0.1 - 0.5 parts, leveling agent 0.1 - 0.5 parts, dipropylene glycol butyl ether 1 - 3 parts, dipropylene glycol methyl ether 1 - 3 parts, thickener 0.1 - 0.5 parts, preservative 0.05 - 0.3 parts, aqueous drier 0.3 - 0.8 parts.

[0039] By adopting the above technical solutions, the raw materials and the raw material ratio of the aqueous anti-corrosion paint are optimized, which is convenient for the preparation of the aqueous anti-corrosion paint.

[0040] To sum up, the present application has at least the following beneficial effects:

[0041] 1. For the acrylate-modified alkyd self-crosslinking resin emulsion of the present application, by grafting acrylate monomers and self-crosslinking monomer A on the aqueous alkyd resin prepolymer and adding self-crosslinking monomer B, stable self-crosslinking groups and oxidative crosslinking double bond groups exist in the alkyd self-crosslinking resin emulsion. During the film-forming process, the self-crosslinking groups and oxidative crosslinking double bond groups gradually crosslink, greatly enhancing the denseness of the paint film, enhancing the bonding strength between the raw materials and between the paint film and the substrate, improving the drying speed, hardness and salt spray corrosion resistance of the paint film, enhancing the anti-corrosion effect of the paint film, and meeting the market demand.

[0042] 2. When the self-crosslinking monomer A is ethylene glycol methylacetoacetate and the self-crosslinking monomer B is adipic dihydrazide, ethylene glycol methylacetoacetate contains two ketone carbonyl groups, and adipic dihydrazide contains hydrazide groups, and the two can undergo a crosslinking reaction. Moreover, ethylene glycol methylacetoacetate also contains a methylene group, which has weak acidity and can enhance the interaction between the raw materials, making the alkyd self-crosslinking resin emulsion exhibit better performance. Detailed implementation mode

[0043] To make the present application easier to understand, the following examples will be used to further illustrate the present application in detail. These examples are only illustrative and are not limited to the application scope of the present application. The raw materials or components used in the present application can be obtained through commercial channels or conventional methods without special instructions.

[0044] Preparation example

[0045] Preparation example 1

[0046] An aqueous alkyd resin prepolymer is prepared from the following raw materials: 187 g of vegetable oil fatty acid, 280 g of acid anhydride, 183 g of polyol, 25 g of xylene, 260 g of ethylene glycol monobutyl ether, and 65 g of benzoic acid.

[0047] Among them, the vegetable oil fatty acid is linolenic acid; the acid anhydride is phthalic anhydride and trimellitic anhydride, and the weight ratio of phthalic anhydride to trimellitic anhydride is 4.6:1; the polyol is pentaerythritol.

[0048] A preparation method of an aqueous alkyd resin prepolymer includes the following steps: Add vegetable oil fatty acid, acid anhydride, polyol, xylene, and benzoic acid to reactor a at a rotation speed of 300 r / min, and stir for 30 min. Heat up to 160 °C to start refluxing, and then heat up to 240 °C at a rate of 10 °C / h, and keep the temperature for reaction for 3.5 h. After testing that the acid value is 35, turn on the vacuum and distill off xylene under reduced pressure. Cool down to 150 °C, add ethylene glycol monobutyl ether, and stir for 30 min. Cool down to 60 °C and filter to obtain the aqueous alkyd resin prepolymer. At this time, the solid content of the aqueous alkyd resin prepolymer is 70 ± 1%, and the viscosity is 15000 mPa·s.

[0049] Example

[0050] Table 1 Content of each raw material of acrylate-modified alkyd self-crosslinking resin emulsion (unit: g)

[0051]

[0052]

[0053] Remarks: AAEM is ethylene glycol methylacetoacetate methacrylate; DAAM is diacetone acrylamide; GMA is glycidyl methacrylate; ADH is adipic dihydrazide; the mass concentration of ammonia water is 25%.

[0054] Example 1

[0055] An acrylate-modified alkyd self-crosslinking resin emulsion has the raw material ratio shown in Table 1, and the aqueous alkyd resin prepolymer is obtained by using Preparation Example 1.

[0056] A preparation method of an acrylate-modified alkyd self-crosslinking resin emulsion includes the following steps:

[0057] Add styrene, acrylic acid, acrylate monomer, and self-crosslinking monomer A to high-level tank a, and stir and dissolve for 30 min to obtain premix A for standby.

[0058] In the high-level tank b, an initiator and the first portion of deionized water are added, and stirred and dissolved for 30 min to obtain premix B for standby. Moreover, the usage amount of the first portion of deionized water is 30 wt% of the total amount of deionized water.

[0059] In the high-level tank c, a self-crosslinking monomer B and the second portion of deionized water are added, and stirred for 30 min to obtain premix C for standby. Moreover, the usage amount of the second portion of deionized water is 10 wt% of the total amount of deionized water.

[0060] At a rotation speed of 300 r / min, in the reaction kettle, an aqueous alkyd resin prepolymer, a neutralizing agent ammonia water, and the third portion of deionized water are added, heated to 85 °C, and stirred and dissolved for 30 min. Then, premix A and premix B are simultaneously added dropwise. Premix A is added dropwise completely within 2.5 h, and premix B is added dropwise completely within 2.5 h. After the dropwise addition is completed, keep stirring at a constant temperature for 1 h. Then, a co-initiator is added, and continue to stir at a constant temperature for 1 h. Cool down to 40 °C, then add premix C, stir for 30 min, add the remaining deionized water, stir for 30 min, and filter to obtain an acrylate-modified alkyd self-crosslinking resin emulsion. Moreover, the usage amount of the third portion of deionized water is 60 wt% of the total amount of deionized water.

[0061] Example 2

[0062] An acrylate-modified alkyd self-crosslinking resin emulsion, the difference from Example 1 is that the raw material ratio is different, and the raw material ratio is shown in Table 1.

[0063] Example 3

[0064] An acrylate-modified alkyd self-crosslinking resin emulsion, the difference from Example 1 is that the raw material ratio is different, and the raw material ratio is shown in Table 1.

[0065] Example 4

[0066] An acrylate-modified alkyd self-crosslinking resin emulsion, the difference from Example 1 is that the self-crosslinking monomer A is different, and the self-crosslinking monomer A is diacetone acrylamide, and the raw material ratio is shown in Table 1.

[0067] Example 5

[0068] An acrylate-modified alkyd self-crosslinking resin emulsion, the difference from Example 1 is that the self-crosslinking monomer A is different, and the self-crosslinking monomer A is glycidyl methacrylate, and the raw material ratio is shown in Table 1.

[0069] Example 6

[0070] An acrylate-modified alkyd self-crosslinking resin emulsion, which is different from Example 1 in that the self-crosslinking monomer A and the self-crosslinking monomer B are not added, and the raw material ratio is shown in Table 1.

[0071] Example 7

[0072] An acrylate-modified alkyd self-crosslinking resin emulsion, which is different from Example 1 in that only the waterborne alkyd resin prepolymer, the neutralizing agent and deionized water are added, and the raw material ratio is shown in Table 1.

[0073] Application Example

[0074] Application Example 1

[0075] A waterborne anticorrosive paint for steel structures, which comprises the following raw materials: 142 g of deionized water, 450 g of alkyd self-crosslinking resin emulsion, 5 g of dispersant, 1 g of defoamer, 250 g of barium sulfate, 100 g of titanium dioxide, 2 g of wetting agent, 2 g of leveling agent, 20 g of dipropylene glycol butyl ether, 20 g of dipropylene glycol methyl ether, 2 g of thickener, 1 g of preservative, 5 g of waterborne drier.

[0076] Among them, the dispersant is dispersant AKN-2280; the defoamer is defoamer TEGO Airex 902W; the wetting agent is wetting agent X-405; the leveling agent is leveling agent byk350; the thickener is thickener HY-305; the preservative is preservative LF-101; the waterborne drier is waterborne drier J2503; the alkyd self-crosslinking resin emulsion is prepared by using Example 1.

[0077] A preparation method of a waterborne anticorrosive paint for steel structures, which comprises the following steps: at a rotation speed of 500 r / min, add deionized water, alkyd self-crosslinking resin emulsion, dispersant, defoamer, wetting agent, leveling agent into a mixing tank, and stir for 10 min. Then add barium sulfate and titanium dioxide, and stir for 60 min. Then add dipropylene glycol butyl ether, dipropylene glycol methyl ether, thickener, preservative, waterborne drier, and stir for 30 min to obtain the waterborne anticorrosive paint.

[0078] Application Examples 2-7

[0079] A waterborne anticorrosive paint for steel structures, which is different from Application Example 1 in that the alkyd self-crosslinking resin emulsion in the raw materials of the waterborne anticorrosive paint is different, and the acrylate-modified alkyd self-crosslinking resin emulsions of Application Examples 2-7 are respectively prepared by using Examples 2-7.

[0080] Performance Detection

[0081] (1) The acrylate-modified alkyd self-crosslinking resin emulsions obtained in Examples 1-7 were respectively taken as samples, and the gel fraction and viscosity of the samples were tested. The test results are shown in Table 2.

[0082] Among them, according to GB / T11175-2021 "Test Method for Synthetic Resin Emulsion", the gel rate and viscosity of the sample were tested.

[0083] (2) The water-based anticorrosive paints obtained in Application Examples 1-7 were respectively taken as samples, and the samples were coated on tinplates and dried to obtain paint films. The surface drying time, adhesion grade, pencil hardness, and neutral salt spray resistance time of the paint films were tested. The test results are shown in Table 2.

[0084] Among them, the surface drying time of the paint film is tested according to GB / T1728-1989 "Determination of Drying Time of Paint Film and Putty Film".

[0085] According to GB / T1720-1989 “Determination of Adhesion of Paint Films”, the adhesion grade of the paint film is tested.

[0086] According to GB / T6739-2006 “Determination of paint film hardness by pencil method for paints and varnishes”, the pencil hardness of the paint film is tested.

[0087] According to GB / T1771-1991 "Test of neutral salt spray resistance of paints and varnishes", the neutral salt spray resistance time of the paint film is tested.

[0088] Table 2 Test results

[0089]

[0090] As can be seen from Table 2, the acrylate modified alkyd self-crosslinking resin emulsion of the present application has good viscosity. When applied to water-based anticorrosive paint, the surface drying time is 10 minutes, showing the advantage of short drying time, and the adhesion grade is 1, the pencil hardness is H to 2H, showing excellent adhesion and high hardness, and at the same time, the neutral salt spray resistance time is 230-255h, showing high salt spray corrosion resistance, meeting market demand.

[0091] Comparing Example 1 with Examples 6-7, it can be seen that if no self-crosslinking monomer is added to the acrylate-modified alkyd resin for copolymerization or no acrylate monomer is used for modification, the paint film performance is very poor, especially the paint film without acrylate monomer modification has almost no resistance, slow drying and poor water resistance. However, by adding self-crosslinking monomers AAEM, DAAM, GMA and ADH to the alkyd self-crosslinking resin emulsion, self-crosslinking occurs during the film-forming process, which increases the crosslinking density of the paint film, significantly reduces the surface drying time, increases the initial pencil hardness and neutral salt spray resistance time, which is mainly due to the double crosslinking during the film-forming process of the water-based anticorrosive paint, which greatly improves the density of the paint film and improves the performance of the paint film.

[0092] Comparing Example 1 with Examples 4-5, the properties of the paint film obtained by adding the self-crosslinking monomer DAAM or the self-crosslinking monomer GMA to the alkyd self-crosslinking resin emulsion are worse than those of the paint film obtained by adding the self-crosslinking monomer AAEM. This is mainly due to the difference in the properties of the paint film caused by the different structures of the three monomers. AAEM contains methylene, which is weakly acidic and can enhance the interaction between the raw materials, chelate metal ions, and enhance the bonding strength between the paint film and the substrate, thereby improving the hardness and salt spray corrosion resistance, so that the alkyd self-crosslinking resin emulsion exhibits better performance.

[0093] It should be noted that the embodiments described above are only used to explain the present application and do not constitute any limitation to the present application. The present application is described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present application may be modified as specified within the scope of the claims of the present application, and the present invention may be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and embodiments, it does not mean that the present application is limited to the specific examples disclosed therein. On the contrary, the present application can be extended to all other methods and applications with the same functions.

Claims

1. An acrylate-modified alkyd self-crosslinking resin emulsion, characterized in that: it is made from the following raw materials in parts by weight: 15 parts of aqueous alkyd resin prepolymer, 1 - 2 parts of neutralizer, 18 - 22 parts of (meth)acrylate monomer, 0.4 - 0.6 part of acrylic acid, 10.2 - 14.8 parts of styrene, 0.5 - 1.5 parts of self-crosslinking monomer A, 0.3 - 0.7 part of self-crosslinking monomer B, 0.1 - 0.3 part of initiator, 0.05 - 0.15 part of co-initiator, 47 - 50 parts of deionized water; the aqueous alkyd resin prepolymer is made from the following raw materials in parts by weight: 15 - 23 parts of vegetable oil fatty acid, 25 - 33 parts of acid anhydride, 15 - 23 parts of polyol, 1 - 4 parts of xylene, 15 - 30 parts of ethylene glycol monobutyl ether, 4 - 10 parts of benzoic acid; the self-crosslinking monomer A is ethylene glycol monomethacrylate acetoacetate; the self-crosslinking monomer B is adipic dihydrazide; the (meth)acrylate monomer is one or more of methyl methacrylate, butyl acrylate, isooctyl acrylate; the vegetable oil fatty acid is one or more of soybean oil fatty acid, linolenic acid, dehydrated castor oil fatty acid.

2. An acrylate-modified alkyd self-crosslinking resin emulsion according to claim 1, characterized in that: the acid anhydride is one or more of phthalic anhydride, trimellitic anhydride, maleic anhydride, acetic anhydride; the polyol is one or more of ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, dipropylene glycol, glycerol, pentaerythritol.

3. An acrylate-modified alkyd self-crosslinking resin emulsion according to claim 1, characterized in that: the aqueous alkyd resin prepolymer is prepared by the following method: mixing vegetable oil fatty acid, acid anhydride, polyol, xylene, benzoic acid, heating to 150 - 170 °C to start refluxing, continuing to heat to 230 - 250 °C, holding for reaction for 3 - 4 h, after detecting the acid value at 35 ± 2, distilling off xylene under reduced pressure, cooling to 140 - 160 °C, adding ethylene glycol monobutyl ether and mixing to obtain the aqueous alkyd resin prepolymer.

4. An acrylate-modified alkyd self-crosslinking resin emulsion according to claim 1, characterized in that: the initiator is one or more of ammonium persulfate, potassium persulfate, sodium persulfate; the co-initiator is tert-butyl hydroperoxide and vitamin C; the neutralizer is one or more of ammonia water, N,N-dimethylethanolamine, triethylamine.

5. A preparation method of an acrylate-modified alkyd self-crosslinking resin emulsion according to any one of claims 1 - 4, characterized in that: it includes the following steps: mixing styrene, acrylic acid, (meth)acrylate monomer, self-crosslinking monomer A to obtain premix A for standby; mixing the initiator and the first portion of deionized water to obtain premix B for standby; mixing the self-crosslinking monomer B and the second portion of deionized water to obtain premix C for standby; Under continuous stirring, mix the aqueous alkyd resin prepolymer, neutralizing agent, and the third portion of deionized water, heat up to 80 - 90 °C, and simultaneously dropwise add premix A and premix B respectively. Premix A is added dropwise within 2 - 3 h, and premix B is added dropwise within 2 - 3 h. After the dropwise addition is completed, carry out heat preservation and stirring treatment for 0.5 - 1.5 h, add a co-initiator, continue the heat preservation and stirring treatment for 0.5 - 1.5 h, cool down to 30 - 50 °C, add premix C and mix, add the remaining deionized water and mix to obtain an acrylate-modified alkyd resin self-crosslinking emulsion.

6. An aqueous anti-corrosion paint for steel structures Characterized in that: Its raw materials include an acrylate-modified alkyd self-crosslinking resin emulsion, and the acrylate-modified alkyd self-crosslinking resin emulsion is the acrylate-modified alkyd self-crosslinking resin emulsion described in any one of claims 1 - 4.

7. An aqueous anti-corrosion paint for steel structures according to claim 6 Characterized in that: The aqueous anti-corrosion paint is mainly made from the following raw materials in parts by weight: 10 - 18 parts of deionized water, 40 - 50 parts of acrylate-modified alkyd self-crosslinking resin emulsion, 0.3 - 0.8 part of dispersant, 0.05 - 0.3 part of defoamer, 20 - 30 parts of barium sulfate, 5 - 15 parts of titanium dioxide, 0.1 - 0.5 part of wetting agent, 0.1 - 0.5 part of leveling agent, 1 - 3 parts of dipropylene glycol butyl ether, 1 - 3 parts of dipropylene glycol methyl ether, 0.1 - 0.5 part of thickener, 0.05 - 0.3 part of preservative, 0.3 - 0.8 part of aqueous drier.

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