A composite modified alkyd dispersion, its preparation method and application

Abstract

The present invention relates to a composite modified alkyd dispersion and a preparation method and application thereof, belonging to the technical field of functional coatings. The raw materials of the composite modified alkyd dispersion include an organosilicon monomer, an epoxy resin, an unsaturated oleic acid, a polyol, a polyacid, an acid anhydride, an acrylate mixed monomer, a catalyst, a first organic solvent, an initiator, and a neutralizer. The present invention triple-modifies the alkyd resin by organosilicon, epoxy resin, and acrylate, thereby greatly improving the performance of the alkyd resin, making the prepared composite modified alkyd dispersion suitable for preparing water-based coatings. Not only does the water-based coating exhibit the characteristics of rapid drying, high gloss, good fullness, and high hardness at room temperature, but it also greatly improves the storage stability and hydrolysis resistance of the water-based coating, so that the coating has better adhesion, water resistance, and chemical corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of functional coatings, and in particular to a composite modified alkyd dispersion and a preparation method and application thereof. Background Art

[0002] Alkyd resins, with their advantages of high gloss, excellent fullness, strong adhesion, and good pigment wettability, are used in a significant portion of traditional coatings. Their raw materials are inexpensive and readily available, and one of their primary raw materials, vegetable oil, is a renewable resource, exempt from petrochemical restrictions. With growing environmental awareness and increasingly stringent environmental regulations, water-based coatings are gradually replacing solvent-based coatings due to their safety and environmental friendliness. The trend toward water-based alkyd resins has become a major industry trend.

[0003] However, since the relative molecular weight of the water-based alkyd resin itself is small, the solubility of oxygen in water is low, and the latent heat of evaporation of water is large, its drying speed is slow, the hardness is low, and the water resistance is poor; and the main chain of the alkyd resin itself has a large number of ester bonds that are easily hydrolyzed, resulting in poor storage stability and hydrolysis resistance of the coating. In order to solve the above technical problems, the existing technical methods mainly achieve water-based coating by grafting hydrophilic monomers on oily alkyd resins. The invention patent with publication number CN115322302A discloses a preparation method and application of an acrylic acid alkyd hybrid emulsion, in which an acrylic acid hybrid alkyd resin is prepared by emulsion polymerization, thereby improving the performance of the alkyd resin. In the emulsion polymerization process, non-ionic emulsifiers such as ethoxylated fatty alcohols and ethoxylated alkylphenols need to be used, but such non-ionic emulsifiers are easy to migrate to the coating surface, affecting the water resistance and gloss of the coating. The invention patent of publication number CN107200836A discloses a preparation method of a water-based alkyd resin that cures quickly at room temperature. By grafting benzoic acid and trimellitic anhydride, the alkyd resin is made water-based. At the same time, a carbodiimide crosslinking agent is used to increase the crosslinking density of the resin itself. However, the main chain of the alkyd resin itself has a large number of ester bonds that are easily hydrolyzed, which may lead to poor storage stability and hydrolysis resistance of the coating. Secondly, the amount of carbodiimide is limited, and there is no significant improvement in improving the drying speed and water resistance of the coating. The invention patent of publication number CN105348498A discloses a water-based alkyd resin with good weather resistance and water resistance. The alkyd resin is prepared by a fatty acid method, and the epoxy group in the epoxy organosiloxane reacts with the alcoholic hydroxyl group and the carboxyl group in the alkyd resin molecular chain, thereby introducing the organosiloxane segment into the water-based alkyd resin system. Although an organosilicon group is introduced, the organosilicon group is mainly present in the side chain and both ends of the molecular chain, and the amount is limited, and the performance of the alkyd resin cannot be significantly improved.

[0004] Therefore, it is very necessary to provide a composite modified alkyd dispersion to improve the performance of alkyd resin. Summary of the Invention

[0005] The object of the present invention is to overcome the shortcomings of the prior art and provide a composite modified alkyd dispersion, a preparation method and application thereof. The present invention triple-modifies the alkyd resin by using silicone, epoxy resin and acrylate, thereby greatly improving the performance of the alkyd resin. The prepared composite modified alkyd dispersion is suitable for preparing water-based coatings. Not only does the water-based coating exhibit the characteristics of fast drying, high gloss, good fullness and high hardness at room temperature, but it also greatly improves the storage stability and hydrolysis resistance of the water-based coating, so that the coating has better adhesion, water resistance, chemical resistance and corrosion resistance.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a composite modified alkyd dispersion comprising the following raw materials in parts by weight: 66-160 parts of an organosilicon-modified epoxy resin prepolymer, 210-220 parts of unsaturated oleic acid, 105-120 parts of a polyol, 86-111 parts of a polyacid, 15-34 parts of an acid anhydride, 77-189 parts of an acrylate mixed monomer, 0.1-0.5 parts of a catalyst, 80-110 parts of a first organic solvent, 2-6 parts of an initiator, 31-48 parts of a neutralizer, and 630-760 parts of deionized water;

[0008] The organosilicon-modified epoxy resin prepolymer is prepared by hydrolyzing and condensing organosilicon monomers and reacting with epoxy resin;

[0009] The acrylic ester mixed monomer comprises the following raw materials in parts by weight: 35 to 90 parts of acrylic ester monomer, 20 to 98 parts of vinyl monomer, and 22 to 34 parts of carboxyl functional monomer.

[0010] The present invention triple-modifies alkyd resin by using silicone, epoxy resin and acrylate, thereby greatly improving the performance of the alkyd resin. The prepared composite modified alkyd dispersion is suitable for preparing water-based coatings. Not only does the water-based coating exhibit the characteristics of rapid drying, high gloss, good fullness and high hardness at room temperature, but the storage stability and hydrolysis resistance of the water-based coating are also greatly improved, so that the coating has better adhesion, water resistance and chemical corrosion resistance.

[0011] As a preferred embodiment of the present invention, in the composite modified alkyd dispersion, the weight portion of the organosilicon-modified epoxy resin prepolymer is 66 to 96 parts.

[0012] As a preferred embodiment of the present invention, the acrylate monomer mixture comprises the following raw materials in parts by weight: 43-90 parts acrylate monomer, 30-68 parts vinyl monomer, and 23-31 parts carboxyl-functional monomer. Assuming the other raw material components of the dispersion are constant, an acrylate monomer mixture that meets these conditions will result in better overall performance of the dispersion.

[0013] As a preferred embodiment of the present invention, the organosilicon-modified epoxy resin prepolymer is prepared by the following method: after mixing an organosilicon monomer and a water-soluble solvent, deionized water is uniformly added dropwise at 60-75°C with stirring. After the addition is completed, the mixture is kept warm and stirred for 3-4 hours to hydrolyze and condense the organosilicon into an organosilicon intermediate. Then, the epoxy resin and the second organic solvent are added, and the mixture is stirred at 150-170°C for 3-5 hours to obtain the organosilicon-modified epoxy resin prepolymer.

[0014] Since water-soluble solvents are miscible with deionized water, pre-mixing the silicone monomer with the water-soluble solvent can effectively accelerate the hydrolysis and condensation reaction of the silicone, thereby obtaining a silicone intermediate. Subsequently, in a second organic solvent, the active end groups (such as hydroxyl, alkoxy, silicon hydrogen, etc.) on the silicone intermediate react with the active groups (such as epoxy, secondary hydroxyl, etc.) in the epoxy resin at high temperature to generate a silicone-modified epoxy resin prepolymer.

[0015] More preferably, the deionized water is added dropwise for 1 to 3 hours.

[0016] Further preferably, the organosilicon-modified epoxy resin prepolymer comprises the following raw materials in parts by weight: 180-260 parts of organosilicon monomer, 50-70 parts of water-soluble solvent, 50-70 parts of deionized water, 800-1200 parts of epoxy resin, and 200-400 parts of a second organic solvent.

[0017] More preferably, the organosilicon-modified epoxy resin prepolymer comprises the following raw materials in parts by weight: 200-260 parts of organosilicon monomer, 60-70 parts of water-soluble solvent, 60-70 parts of deionized water, 800-1080 parts of epoxy resin, and 200-300 parts of a second organic solvent.

[0018] More preferably, the water-soluble solvent is ethanol, and the second organic solvent is xylene.

[0019] As a preferred embodiment of the present invention, the organic silicon monomer includes at least two of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, propyltrimethoxysilane, propyltriethoxysilane and tetraethyl orthosilicate.

[0020] As a preferred embodiment of the present invention, the epoxy resin includes at least one of bisphenol A epoxy resin E-51, bisphenol A epoxy resin E-44, bisphenol A epoxy resin E-20, bisphenol A epoxy resin E-12 and bisphenol A epoxy resin E-03.

[0021] In the present invention, the organosilicon-modified epoxy resin prepolymer is made from the following raw materials in parts by weight: 134-158 parts trimethoxysilane, 42-104 parts dimethoxysiloxane, 60-70 parts ethanol, 60-70 parts deionized water, 800-1080 parts epoxy resin, and 200-300 parts xylene. The trimethoxysilane is preferably at least one of methyltrimethoxysilane, propyltrimethoxysilane, and phenyltrimethoxysilane, and the epoxy resin is preferably bisphenol A epoxy resin E-20. When the raw material composition of the organosilicon-modified epoxy resin prepolymer meets the above conditions, the dispersion can be used to prepare a water-based coating with better overall performance.

[0022] As a preferred embodiment of the present invention, the unsaturated oleic acid includes at least one of linoleic acid, soybean oleic acid, dehydrated ricinoleic acid, tall oil acid, eleostearic acid and ricinoleic acid.

[0023] It is understood that the polyols described in the present invention refer to alcohol compounds containing two or more hydroxyl groups in the molecule; and the polyacids described in the present invention refer to acid compounds containing two or more carboxylic acids in the molecule.

[0024] As a preferred embodiment of the present invention, the polyol includes at least one of neopentyl glycol, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, methyl-1,2-propanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol and glycerol; the polyacid includes at least one of phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, oxalic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; and the acid anhydride includes at least one of maleic anhydride, tetrahydrophthalic anhydride and hexahydrophthalic anhydride.

[0025] As a preferred embodiment of the present invention, the catalyst includes at least one of lithium hydroxide, an organic tin catalyst, and an organic titanium catalyst, the organic tin catalyst includes at least one of monobutyltin oxide and dibutyltin oxide, and the organic titanium catalyst includes at least one of titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide, and titanium butyl isopropoxide.

[0026] As a preferred embodiment of the present invention, the acrylate monomer comprises C1-C 18 Acrylate, the C1-C 18The acrylic acid ester includes at least one of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate; the vinyl monomer includes at least one of styrene and α-methylstyrene; the carboxyl functional monomer includes at least one of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and maleic anhydride; and the initiator includes at least one of benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, tert-amyl peroxybenzoate, di-tert-butyl peroxide, and di-tert-amyl peroxide.

[0027] As a preferred embodiment of the present invention, the first organic solvent includes at least one of xylene, toluene, ethanol, methanol, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol butyl ether, propylene glycol methyl ether acetate, and dipropylene glycol butyl ether.

[0028] As a preferred embodiment of the present invention, the neutralizing agent includes at least one of an organic amine and a water-soluble inorganic base, and the organic amine includes at least one of dimethylethanolamine, methyldiethanolamine, triethylamine and triethanolamine; the molar ratio of the neutralizing agent to the carboxyl functional monomer in the acrylate mixed monomer is (1.0-1.2):1.

[0029] In the present invention, the neutralizer is used to neutralize excess carboxyl functional monomers. The neutralizer reacts with the carboxyl functional monomers to form salts. When the neutralizer is excessive, unreacted neutralizer remains in the composite modified alkyd dispersion, thereby significantly improving the dispersion stability and wettability of the coating.

[0030] In a second aspect, the present invention provides a method for preparing the composite modified alkyd dispersion as described in the first aspect, comprising the following steps:

[0031] (1) unsaturated oleic acid, polyol, polyacid, acid anhydride, catalyst, reflux solvent and organosilicon modified epoxy resin prepolymer are refluxed at 200-230° C., while being kept warm and stirred until the acid value of the reaction system reaches 3-5 mgKOH / g, the reflux solvent is removed under reduced pressure, the temperature is lowered to 125-150° C., and a first organic solvent is added for dilution to obtain a composite modified copolymer A;

[0032] (2) adding the acrylic acid ester mixed monomer and the initiator dropwise to the composite modified copolymer A at 125-150° C. with stirring, and continuing to keep warm and stir for 1-3 hours after the addition is complete. After cooling, a neutralizing agent is added to obtain a composite modified copolymer B;

[0033] (3) The composite modified copolymer B is mixed and dispersed with deionized water to obtain a composite modified alkyd dispersion.

[0034] As a preferred embodiment of the present invention, in step (2), the acrylic ester mixed monomer and the initiator are added dropwise at a uniform speed simultaneously, and the addition time is 3 to 4 hours.

[0035] As a preferred embodiment of the present invention, the acid value of the composite modified alkyd dispersion is 12.5 to 16.6 mgKOH / g.

[0036] As a preferred embodiment of the present invention, the solid content of the composite modified alkyd dispersion is not less than 42.5%.

[0037] The present invention conducts an esterification reaction on unsaturated oleic acid, polyol, polyacid, acid anhydride and organosilicon-modified epoxy resin prepolymer under specific conditions to obtain a copolymer A of organosilicon and epoxy resin double modification; then, an acrylate composite monomer is grafted to obtain a triple modified copolymer B; finally, the copolymer is dispersed in water to obtain a composite modified alkyd dispersion; the organosilicon, epoxy resin and acrylate are synergistically modified to greatly improve the performance of the alkyd resin, making the prepared composite modified alkyd dispersion suitable for preparing water-based coatings, not only making the water-based coatings exhibit the characteristics of rapid drying, high gloss, good fullness and high hardness at room temperature, but also greatly improving the storage stability and hydrolysis resistance of the water-based coatings, so that the coatings have better adhesion, water resistance and chemical corrosion resistance.

[0038] In a third aspect, the present invention provides a use of the composite modified alkyd dispersion as described in the first aspect in the preparation of a water-based anti-corrosion coating.

[0039] As a preferred embodiment of the present invention, the water-based anti-corrosion coating is prepared by the following method:

[0040] S1. Mix deionized water, a pH regulator, a dispersant, a portion of a wetting agent, a portion of a defoaming agent, and a pigment and filler, and grind the mixture to a fineness of less than 20 μm to obtain an aqueous slurry;

[0041] S2. Add the composite modified alkyd dispersion, cosolvent, drier, anti-flash rust agent, thickener, remaining wetting agent and remaining defoamer to the aqueous slurry obtained in step S1, stir and mix evenly to obtain a water-based single-component metal anti-corrosion coating.

[0042] In the present invention, the water-based anti-corrosion coating can be applied to a substrate to form a surface coating. The application method includes any one of air spraying, airless spraying, electrostatic spraying, brushing, roller coating, or knife coating. The substrate includes metal, glass, or ceramic. The water-based anti-corrosion coating of the present invention is more suitable for application to the surface of a metal substrate as a metal topcoat or primer.

[0043] Further preferably, the co-solvent includes an alcohol ether solvent, and the alcohol ether solvent includes at least one of ethanol, n-butanol, isobutanol, isopropanol, ethylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether and dipropylene glycol butyl ether.

[0044] The leveling agent includes at least one of a fluorine-containing surfactant and a polyacrylic acid copolymer; the wetting agent includes an organosiloxane copolymer, and the organosiloxane copolymer can be at least one of Tego270 and Tego4100; the defoaming agent includes at least one of mineral oil, polyether and silicone defoaming agent (preferably an organosilicone defoaming agent), and the silicone defoaming agent can be at least one of silicone defoaming agent Tego810 and silicone defoaming agent Tego902W; the drying agent includes at least one of cobalt naphthenate, zirconium naphthenate and zinc naphthenate; for example, the drying agent is a water-based drying agent OMG123; the thickener includes a non-ionic polyurethane thickener, and the non-ionic polyurethane thickener can be Hemmings 299.

[0045] The pigments and fillers include at least one of inorganic pigments, organic pigments, metal complex pigments, and fillers; the inorganic pigments include at least one of carbon black, graphite, titanium dioxide, red iron oxide, yellow iron oxide, silver powder, aluminum powder, zinc phosphate, aluminum tripolyphosphate, strontium chrome yellow, and zinc chrome yellow; the organic pigments include azo pigments and non-azo pigments; the azo pigments include at least one of monoazo pigments, disazo pigments, condensed azo pigments, and azo condensed pigments; the non-azo pigments include at least one of phthalocyanine blue, phthalocyanine green, thioindigo pigments, anthraquinone pigments, dioxazine pigments, and triarylmethane pigments. The anthraquinone pigments may be at least one of anthrapyrimidine pigments, indanthrone pigments, pyrenanthrone pigments, and dibenzopyrene dione pigments; the fillers include at least one of precipitated barium sulfate, light calcium carbonate, heavy calcium carbonate, kaolin, talc, sericite, and bentonite.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The present invention introduces epoxy resin, which makes the coating have excellent chemical corrosion resistance;

[0048] (2) The present invention introduces organosilicon, and the hydrolyzed organosilicon intermediate has an active group, silanol, so that when the dispersion is used to prepare water-based anti-corrosion coatings, it can form hydrogen bonds with the hydroxyl groups of inorganic pigments or dehydrate to form covalent bonds, forming a "body-shaped" structure with a cross-linked network, increasing the relative molecular weight, or physically interacting and / or chemically bonding with the polar groups on the surface of the substrate, thereby improving the adhesion and water resistance of the coating to the substrate.

[0049] (3) The present invention adopts graft modification by acrylic ester composite monomer to form a modified alkyd resin as a core and an acrylic ester composite monomer as a shell, which is beneficial to the ester bond protection "wrapping", so that the composite modified alkyd dispersion exhibits good storage stability and hydrolysis resistance, and can also make the coating exhibit the characteristics of fast drying, high gloss, good fullness, and high hardness;

[0050] (4) The dispersion of the present invention uses water as the main medium, is easy to construct, has little pollution to the environment, and has no safety hazards such as fire. DETAILED DESCRIPTION

[0051] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0052] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0053] Example 1

[0054] The preparation method of the composite modified alkyd dispersion provided in this embodiment is:

[0055] (1) After mixing the organosilicon monomer and ethanol, deionized water was added dropwise at a uniform rate at 70° C. with stirring for 2 hours. After the addition was completed, the mixture was kept warm and stirred for 4 hours to hydrolyze and condense the organosilicon into an organosilicon intermediate. Epoxy resin and xylene were then added and stirred at 160° C. for 4 hours to obtain the organosilicon-modified epoxy resin prepolymer.

[0056] (2) After unsaturated oleic acid, polyol, polyacid, acid anhydride, monobutyltin oxide, xylene and organosilicon modified epoxy resin prepolymer are mixed, the solvent is refluxed at 220° C., while being kept warm and stirred until the acid value of the reaction system reaches 3 to 5 mgKOH / g, the solvent (such as xylene, ethanol and deionized water) is removed under reduced pressure, the temperature is lowered to 135° C., and ethylene glycol butyl ether is added for dilution to obtain a composite modified copolymer A;

[0057] (3) Mixing the raw materials of the acrylic acid mixed monomer, and simultaneously adding the acrylic acid mixed monomer and the initiator dropwise to the copolymer A at a uniform rate under stirring at 135° C. for 3 hours. After the addition is complete, continue to keep warm and stir for 2 hours. After cooling, add a neutralizer to obtain a composite modified copolymer B;

[0058] (4) The composite modified copolymer B is mixed and dispersed with deionized water to obtain a composite modified alkyd dispersion.

[0059] The raw materials for step (1) are shown in Table 1, and the raw materials for steps (2) to (4) are shown in Table 2.

[0060] Examples 2 to 9

[0061] The preparation methods of the composite modified alkyd dispersions provided in Examples 2 to 9 are different from those in Example 1 in that the raw materials used in step (1) of Examples 2 to 9 are as shown in Table 1.

[0062] Examples 10 to 13

[0063] The preparation method of the composite modified alkyd dispersion provided in Examples 10 to 13 is different from that in Example 1 in that the weight fractions of the organosilicon-modified epoxy resin prepolymer added in step (2) of Examples 10 to 13 are as shown in Table 2.

[0064] Examples 14 to 17

[0065] The preparation methods of the composite modified alkyd dispersions provided in Examples 14 to 17 differ from those in Example 1 in that the weight proportions of the acrylic acid mixed monomers, initiator, triethylamine, and deionized water used in Examples 14 to 17 are as shown in Table 2.

[0066] Examples 18-19

[0067] The preparation method of the composite modified alkyd dispersion provided in Examples 18 to 19 is different from that in Example 1 in that the weight fractions of the raw materials in steps (2) to (4) of Examples 18 to 19 are as shown in Table 2.

[0068] Example 20

[0069] The preparation method of the composite modified alkyd dispersion provided in this embodiment is different from that in Example 1 in that the weight parts of the raw materials in steps (2) to (4) of this embodiment are as shown in Table 2. The preparation method of this embodiment comprises the following steps:

[0070] (1) After mixing the organosilicon monomer and ethanol, deionized water was added dropwise at a uniform rate at 75° C. with stirring for 1 hour. After the addition was completed, the mixture was kept warm and stirred for 3 hours to hydrolyze and condense the organosilicon into an organosilicon intermediate. Epoxy resin and xylene were then added and stirred at 170° C. for 3 hours to obtain the organosilicon-modified epoxy resin prepolymer.

[0071] (2) After unsaturated oleic acid, polyol, polyacid, acid anhydride, monobutyltin oxide, xylene and organosilicon modified epoxy resin prepolymer are mixed, the solvent is refluxed at 230° C., while being kept warm and stirred until the acid value of the reaction system reaches 3 to 5 mgKOH / g, the solvent (such as xylene, ethanol and deionized water) is removed under reduced pressure, the temperature is lowered to 150° C., and ethylene glycol butyl ether is added for dilution to obtain a composite modified copolymer A;

[0072] (3) Mixing the raw materials of the acrylic acid mixed monomer, and simultaneously adding the acrylic acid ester mixed monomer and the initiator dropwise to the copolymer A at a uniform rate under stirring at 150° C. for 3 hours. After the addition is complete, continue to keep warm and stir for 1 hour. After cooling, add a neutralizer to obtain a composite modified copolymer B;

[0073] (4) The composite modified copolymer B is mixed and dispersed with deionized water to obtain a composite modified alkyd dispersion.

[0074] Example 21

[0075] The preparation method of the composite modified alkyd dispersion provided in this embodiment is different from that in Example 1 in that the weight proportions of the raw materials in steps (2) to (4) of this embodiment are as shown in Table 2. The preparation method of this embodiment comprises the following steps: mixing an organosilicon monomer and ethanol, adding deionized water dropwise at a constant speed at 60° C. with stirring for 3 hours, and after the addition is complete, maintaining the temperature and stirring for 4 hours to hydrolyze and condense the organosilicon into an organosilicon intermediate, and then adding epoxy resin and xylene, and stirring at 150° C. for 5 hours to obtain the organosilicon-modified epoxy resin prepolymer;

[0076] (2) After unsaturated oleic acid, polyol, polyacid, acid anhydride, monobutyltin oxide, xylene and organosilicon modified epoxy resin prepolymer are mixed, the solvent benzene is refluxed at 200° C., while being kept warm and stirred until the acid value of the reaction system reaches 3-5 mgKOH / g, the solvent (such as xylene, ethanol and deionized water) is removed under reduced pressure, the temperature is lowered to 125° C., and ethylene glycol butyl ether is added for dilution to obtain a composite modified copolymer A;

[0077] (3) adding the acrylic acid ester mixed monomer and the initiator dropwise to the copolymer A at a constant speed at 125° C. while stirring for 4 hours. After the addition is complete, the mixture is kept warm and stirred for 3 hours. After cooling, a neutralizer is added to obtain a composite modified copolymer B;

[0078] (4) The composite modified copolymer B is mixed and dispersed with deionized water to obtain a composite modified alkyd dispersion.

[0079] Table 1

[0080]

[0081] Table 2

[0082]

[0083]

[0084] Comparative Example 1

[0085] This comparative example provides a method for preparing a composite modified alkyd dispersion, comprising the following steps:

[0086] (1) Linoleic acid, pentaerythritol, diethylene glycol, isophthalic acid, tetrahydrophthalic anhydride, monobutyltin oxide, xylene and epoxy resin E-20 are mixed, and xylene is refluxed at 220° C. while being kept warm and stirred until the acid value of the reaction system reaches 3 to 5 mgKOH / g. Xylene is removed under reduced pressure, the temperature is lowered to 135° C., and ethylene glycol butyl ether is added to dilute the mixture to obtain an epoxy resin modified copolymer;

[0087] (2) Methyl methacrylate, n-butyl methacrylate, styrene, and acrylic acid are uniformly mixed to obtain an acrylate mixed monomer, and the acrylate mixed monomer and an initiator are simultaneously added dropwise to the epoxy resin modified copolymer at a constant speed under stirring at 135° C. for 3 hours. After the addition is completed, the mixture is kept warm and stirred for 2 hours. After cooling, a neutralizer is added to obtain a composite modified copolymer;

[0088] (3) Mixing and dispersing the composite modified copolymer with deionized water to obtain a composite modified alkyd dispersion.

[0089] The following raw materials were used in each step of this comparative example in parts by weight: 66 parts of epoxy resin E-20, 10 parts of xylene, 210 parts of linoleic acid, 75 parts of pentaerythritol, 30 parts of diethylene glycol, 101 parts of isophthalic acid, 34 parts of tetrahydrophthalic anhydride, 0.5 parts of monobutyltin oxide, 110 parts of ethylene glycol butyl ether, 80 parts of methyl methacrylate, 10 parts of n-butyl methyl acrylate, 68 parts of styrene, 31 parts of acrylic acid, 6 parts of tert-butyl peroxide 2-ethylhexyl ester, 43.5 parts of triethylamine, and 730 parts of deionized water.

[0090] Comparative Example 2

[0091] This comparative example provides a method for preparing a composite modified alkyd dispersion, comprising the following steps:

[0092] (1) Methyltrimethoxysilane, dimethyldimethoxysilane, propyltrimethoxysilane and ethanol were mixed, and deionized water was added dropwise at a constant speed at 70° C. with stirring for 2 h. After the addition was completed, the mixture was kept warm and stirred for 4 h to hydrolyze and condense the organosilicon into an organosilicon intermediate, and the deionized water and ethanol were removed under reduced pressure to obtain an organosilicon prepolymer;

[0093] (2) After unsaturated oleic acid, polyol, polyacid, acid anhydride, monobutyltin oxide, xylene and silicone prepolymer are mixed, xylene is refluxed at 220° C. while being kept warm and stirred until the acid value of the reaction system reaches 3 to 5 mgKOH / g, xylene is removed under reduced pressure, the temperature is lowered to 135° C., and ethylene glycol butyl ether is added for dilution to obtain a composite modified copolymer A;

[0094] (3) Methyl methacrylate, n-butyl methyl acrylate, styrene, and acrylic acid are uniformly mixed to obtain an acrylate mixed monomer, and the acrylate mixed monomer and an initiator are simultaneously added dropwise to the copolymer A at a constant speed under stirring at 135° C. for 3 hours. After the addition is completed, the mixture is stirred at this temperature for 2 hours. After cooling, a neutralizer is added to obtain a composite modified copolymer B;

[0095] (4) The composite modified copolymer B is mixed and dispersed with deionized water to obtain a composite modified alkyd dispersion.

[0096] The following raw materials were used in step (1) of this comparative example in parts by weight: 112 parts of methyltrimethoxysilane, 42 parts of dimethyldimethoxysilane, 46 parts of propyltrimethoxysilane, 60 parts of ethanol and 60 parts of deionized water.

[0097] In this comparative example, steps (2) to (4) use the following raw materials in parts by weight: 66 parts of organosilicon prepolymer, 10 parts of xylene, 210 parts of linoleic acid, 75 parts of pentaerythritol, 30 parts of diethylene glycol, 101 parts of isophthalic acid, 34 parts of tetrahydrophthalic anhydride, 0.5 parts of monobutyl tin oxide, 110 parts of ethylene glycol butyl ether, 80 parts of methyl methacrylate, 10 parts of n-butyl methyl acrylate, 68 parts of styrene, 31 parts of acrylic acid, 6 parts of tert-butyl peroxide 2-ethylhexyl ester, 43.5 parts of triethylamine, and 730 parts of deionized water.

[0098] Comparative Example 3

[0099] This comparative example provides a method for preparing a composite modified alkyd dispersion, comprising the following steps:

[0100] (1) Linoleic acid, pentaerythritol, diethylene glycol, isophthalic acid, tetrahydrophthalic anhydride, monobutyltin oxide, xylene and epoxy resin E-20 are mixed, and xylene is refluxed at 220° C. while being kept warm and stirred until the acid value of the reaction system reaches 3 to 5 mgKOH / g. Xylene is removed under reduced pressure, the temperature is lowered to 135° C., and ethylene glycol butyl ether is added to dilute the mixture to obtain an epoxy resin modified copolymer;

[0101] (2) Methyl methacrylate, vinylsiloxysilane (A-171), styrene, and acrylic acid are uniformly mixed to obtain an acrylate mixed monomer, and the acrylate mixed monomer and the initiator are simultaneously added dropwise to the epoxy resin modified copolymer at a uniform rate under stirring at 135° C. for 3 hours. After the addition is completed, the mixture is kept warm and stirred for 2 hours. After cooling, a neutralizer is added to obtain a composite modified copolymer;

[0102] (3) Mixing and dispersing the composite modified copolymer with deionized water to obtain a composite modified alkyd dispersion.

[0103] The following raw materials are used in each step of this comparative example in parts by weight: 66 parts of epoxy resin E-20, 10 parts of xylene, 210 parts of linoleic acid, 75 parts of pentaerythritol, 30 parts of diethylene glycol, 101 parts of isophthalic acid, 34 parts of tetrahydrophthalic anhydride, 0.5 parts of monobutyltin oxide, 110 parts of ethylene glycol butyl ether, 80 parts of methyl methacrylate, 10 parts of vinylsiloxysilane (A-171), 68 parts of styrene, 31 parts of acrylic acid, 6 parts of initiator, 43.5 parts of triethylamine, and 730 parts of deionized water; wherein the initiator is tert-butyl peroxy-2-ethylhexyl ester.

[0104] Comparative Example 4

[0105] This comparative example provides a method for preparing an acrylic acid-modified alkyd dispersion, comprising the following steps:

[0106] (1) Linoleic acid, pentaerythritol, diethylene glycol, isophthalic acid, tetrahydrophthalic anhydride, monobutyltin oxide, and xylene are mixed, and xylene is refluxed at 220° C. while being kept warm and stirred until the acid value of the reaction system reaches 3 to 5 mgKOH / g. Xylene is removed under reduced pressure, the temperature is lowered to 135° C., and ethylene glycol butyl ether is added to dilute the mixture to obtain a copolymer;

[0107] (2) Methyl methacrylate, n-butyl methyl acrylate, styrene, and acrylic acid are uniformly mixed to obtain an acrylate mixed monomer, and the acrylate mixed monomer and an initiator are simultaneously added dropwise to the copolymer at a uniform rate under stirring at 135° C. for 3 hours. After the addition is completed, the mixture is kept warm and stirred for 2 hours. After cooling, a neutralizer is added to obtain an acrylic acid modified copolymer;

[0108] (3) Mixing and dispersing the acrylic acid-modified copolymer with deionized water to obtain an acrylic acid-modified alkyd dispersion.

[0109] The following raw materials are used in each step of this comparative example in parts by weight: 10 parts of xylene, 210 parts of linoleic acid, 75 parts of pentaerythritol, 30 parts of diethylene glycol, 101 parts of isophthalic acid, 34 parts of tetrahydrophthalic anhydride, 0.5 parts of monobutyltin oxide, 110 parts of ethylene glycol butyl ether, 80 parts of methyl methacrylate, 10 parts of n-butyl methyl acrylate, 68 parts of styrene, 31 parts of acrylic acid, 6 parts of initiator, 43.5 parts of triethylamine, and 730 parts of deionized water. The initiator is tert-butyl peroxide 2-ethylhexyl.

[0110] Comparative Example 5

[0111] This comparative example provides a method for preparing a modified alkyd dispersion, comprising the following steps:

[0112] (1) Linoleic acid, pentaerythritol, diethylene glycol, isophthalic acid, benzoic acid, monobutyltin oxide and xylene are mixed, and xylene is refluxed at 220° C. while being kept warm and stirred until the acid value of the reaction system reaches 3-5 mgKOH / g. The temperature is then lowered to 160° C., tetrahydrophthalic anhydride and trimellitic anhydride are added to the mixture, and the temperature is then raised to 175° C., and the temperature is continued to be kept warm and stirred until the acid value of the reaction system reaches 30-35 mgKOH / g. The xylene is removed under reduced pressure, the temperature is lowered to 135° C., ethylene glycol butyl ether is added for dilution, and the mixture is then cooled to 60° C., triethylamine is added, and the mixture is kept warm and stirred for 30 minutes to obtain a modified copolymer;

[0113] (2) The modified copolymer obtained in step (1) is mixed and dispersed with deionized water to obtain a modified alkyd dispersion.

[0114] The following raw materials were used in each step of this comparative example in parts by weight: 10 parts of xylene, 210 parts of linoleic acid, 75 parts of pentaerythritol, 30 parts of diethylene glycol, 101 parts of isophthalic acid, 34 parts of tetrahydrophthalic anhydride, 0.5 parts of monobutyltin oxide, 110 parts of ethylene glycol butyl ether, 30 parts of benzoic acid, 55 parts of trimellitic anhydride, 29 parts of triethylamine, and 730 parts of deionized water.

[0115] Effect Example 1

[0116] The products obtained in the above examples and comparative examples were characterized and tested, and the testing method is as follows:

[0117] (1) Place the samples in a transparent glass container and visually observe the appearance of each sample;

[0118] (2) Take 1 g of sample, dry it at 125°C for 1 hour, measure the weight of the dried sample, and calculate the non-volatile content of the sample;

[0119] (3) Test the viscosity of each sample using a rotational viscometer at 25°C.

[0120] (4) The acid value of the sample was tested by titration, and the OH content relative to 100% solids was further tested;

[0121] (5) using a laser particle size analyzer to measure the average particle size of the polymer in the sample;

[0122] (6) Dilute the sample with deionized water at a mass ratio of 1:4, and then use a pH meter to measure the pH value of the diluted sample;

[0123] (7) Place the sample in a drying oven at 50°C for 30 days and observe the appearance of the sample.

[0124] The test results are shown in Table 3.

[0125] Table 3

[0126]

[0127]

[0128] Application Example 1

[0129] A method for preparing a water-based single-component metal anti-corrosion coating comprises the following steps:

[0130] (1) Weigh the following raw materials in parts by weight: 10.2 parts of deionized water, 0.2 parts of N,N-dimethylethanolamine (DMEA), 0.5 parts of dispersant (BYK190), 0.1 parts of wetting agent (Tego270), 0.3 parts of defoaming agent (Tego810), 6 parts of titanium dioxide (R996), 0.2 parts of carbon black (MA-100), 20 parts of 1250 mesh precipitated barium sulfate, 5 parts of zinc phosphate, and 0.5 parts of bentonite (EW); mix and stir the raw materials evenly, add them to a sand mill, and grind them to a fineness of less than 20 μm to obtain an aqueous slurry;

[0131] (2) The following raw materials in parts by weight are added to the color paste in sequence: 50 parts of a composite modified alkyd dispersion, 0.8 parts of an aqueous drying agent (OMG123), 5 parts of ethylene glycol butyl ether (BCS), 0.2 parts of a wetting agent (Tego4100), 0.1 parts of a defoaming agent (Tego902W), 0.5 parts of an anti-flash rust agent (T730) and 0.4 parts of a thickener (Hemmings 299), and dispersed uniformly to obtain a water-based one-component metal anti-corrosion coating; the composite modified alkyd dispersion is prepared by the preparation method of Example 1.

[0132] Application Examples 2 to 21 and Comparative Application Examples 1 to 5

[0133] Application Examples 2 to 21 and Comparative Examples 1 to 5 respectively provide a method for preparing a water-based one-component metal anticorrosive coating, which differs from Application Example 1 in that:

[0134] The dispersion used in Application Example 2 was prepared by the preparation method of Example 2;

[0135] The dispersion used in Application Example 3 was prepared by the preparation method of Example 3;

[0136] The dispersion used in Application Example 4 was prepared by the preparation method of Example 4;

[0137] The dispersion used in Application Example 5 was prepared by the preparation method of Example 5;

[0138] The dispersion used in Application Example 6 was prepared by the preparation method of Example 6;

[0139] The dispersion used in Application Example 7 was prepared by the preparation method of Example 7;

[0140] The dispersion used in Application Example 8 was prepared by the preparation method of Example 8;

[0141] The dispersion used in Application Example 9 was prepared by the preparation method of Example 9;

[0142] The dispersion used in Application Example 10 was prepared by the preparation method of Example 10;

[0143] The dispersion used in Application Example 11 was prepared by the preparation method of Example 11;

[0144] The dispersion used in Application Example 12 was prepared by the preparation method of Example 12;

[0145] The dispersion used in Application Example 13 was prepared by the preparation method of Example 13;

[0146] The dispersion used in Application Example 14 was prepared by the preparation method of Example 14;

[0147] The dispersion used in Application Example 15 was prepared by the preparation method of Example 15;

[0148] The dispersion used in Application Example 16 was prepared by the preparation method of Example 16;

[0149] The dispersion used in Application Example 17 was prepared by the preparation method of Example 17;

[0150] The dispersion used in Application Example 18 was prepared by the preparation method of Example 18;

[0151] The dispersion used in Application Example 19 was prepared by the preparation method of Example 19;

[0152] The dispersion used in each Example 20 was prepared by the preparation method of Example 20;

[0153] The dispersion used in Application Example 21 was prepared by the preparation method of Example 21;

[0154] The dispersion used in Comparative Example 1 was prepared by the preparation method of Comparative Example 1;

[0155] The dispersion used in Comparative Example 2 was prepared by the preparation method of Comparative Example 2;

[0156] The dispersion used in Comparative Example 3 was prepared by the preparation method of Comparative Example 3;

[0157] The dispersion used in Comparative Example 4 was prepared by the preparation method of Comparative Example 4;

[0158] The dispersion used in Comparative Example 5 was prepared by the preparation method of Comparative Example 5.

[0159] Effect Example 2

[0160] The water-based one-component metal anti-corrosion coatings prepared in each application example and application comparison example were subjected to construction and performance characterization tests.

[0161] 1. The construction method is as follows: Mix the water-based one-component metal anti-corrosion coating with deionized water, spray it on the tinplate, the spray viscosity is 23", the construction temperature is 25℃, the construction humidity is 55%, and the curing time is 7 days at 25℃. The dry film thickness of the coating is 35-45μm.

[0162] 2. The performance characterization test method is as follows:

[0163] (1) Viscosity test: The viscosity test was carried out according to GB / T1723-1979 using the Tu-4 cup produced by Guangzhou Biaogeda Co., Ltd.

[0164] (2) Non-volatile matter test: According to GB / T1725-2007, 1g of coating sample was taken and dried at 125℃ for 1h. The weight of the dried sample was measured and the non-volatile content in the sample was calculated.

[0165] (3) Surface drying time: The surface drying time is determined in accordance with GB / T 1728-1979. The coating sample is coated on a glass plate with a coating thickness of about 100 μm. A cotton ball is gently placed on the coating surface. The cotton ball is blown lightly in a horizontal direction at a distance of 10 to 15 cm from the mouth. If the cotton ball can be blown away without leaving any cotton fibers on the coating surface, the surface is considered dry and the time is recorded.

[0166] (4) Actual drying time: The coating sample is coated on a glass plate with a coating thickness of about 100 μm. A piece of qualitative filter paper is placed on the coating. A drying tester is then gently placed on the filter paper while the stopwatch is started. After 30 seconds, the drying tester is removed and the sample is turned over (coating downward). If the filter paper can fall freely or the back of the sample is tapped several times with the index finger of the hand holding the sample, the filter paper can fall freely without the filter paper fibers sticking to the coating. The coating is considered to be actually dry and the time is recorded.

[0167] (5) Gloss test: The gloss test was carried out in accordance with GB / T9754-1998 using a BGD516 / 2 dual-angle gloss meter produced by Guangzhou Biaogeda Co., Ltd.

[0168] (6) Adhesion test: The test was carried out in accordance with GB / T 9286-1998 using the BGD502 tester produced by Guangzhou Biaogeda Co., Ltd.

[0169] (7) Pencil hardness test: The test was carried out in accordance with GB / T 6739-2006 using a BGD 505 combination pencil hardness tester manufactured by Guangzhou Biaogeda Co., Ltd.

[0170] (8) Impact resistance test: The test was carried out in accordance with GB / T 1732-1993 using a BGD 304 coating impactor produced by Guangzhou Biaogeda Co., Ltd.

[0171] (9) Water resistance test: According to GB / T1733-1993, the sample is sealed with 3M's 600 type tape at room temperature and then immersed in 25°C water. The coating is observed and the blistering time is recorded.

[0172] (10) Acid resistance test: According to GB / T9274-1988, the sample is sealed with 3M 600 type tape at room temperature and then immersed in H2SO4 solution with a mass concentration of 0.1 mol / L. The coating is observed and the immersion time is recorded.

[0173] (11) Alkali resistance test: According to GB / T9274-1988, the sample is sealed with 3M 600 type tape at room temperature and then immersed in a NaOH solution with a mass concentration of 0.1 mol / L. The coating is observed and the etching time is recorded.

[0174] (12) Salt water resistance test: The test was conducted according to GT / 9274-1988. At room temperature, the sample was sealed with 3M 600 type tape and then immersed in a 5% NaCl solution. The coating was observed and the blistering time was recorded.

[0175] (13) Salt spray resistance test: The test was carried out in accordance with GB / T1771-2007. At room temperature, the sample was sealed with 3M's 600 tape. Two damage lines with an angle of 60° were cut in the middle of the sample with a blade. The coating was observed and the corrosion time was recorded.

[0176] (14) Storage stability test: The test was carried out in accordance with GB / T 6753.3-1986. Three samples were taken and placed in a 0.4L standard pressure-capped metal paint can. The sample volume should be about 15mm from the top of the can. After weighing, the samples were placed in a constant temperature drying oven at 50±2℃. After storage for 7 days, the samples were checked for crusting, sedimentation, coarse lumps, viscosity changes, corrosion or corruption odor, etc.

[0177] (15) Artificial aging resistance test: The test was carried out in accordance with GB / T23987-2009 using the QUV / se type ultraviolet accelerated aging tester of the American Q-Panel Company, UVA aging, UVA-340nm lamp, 4 hours of ultraviolet irradiation, and 4 hours of condensation.

[0178] The test results are shown in Table 4.

[0179] Table 4

[0180]

[0181]

[0182]

[0183]

[0184] Comparing the test results of Application Examples 1 to 9, it can be seen that the water resistance, acid resistance, alkali resistance, salt resistance and other properties of the paint coatings of Application Examples 1 to 6 are significantly better than those of other embodiments. This shows that the silicone-modified epoxy resin prepolymer is made of the following raw materials in parts by weight: 134 to 158 parts of trimethoxysilane, 42 to 104 parts of dimethoxysiloxane, 60 to 70 parts of ethanol, 60 to 70 parts of deionized water, 800 to 1080 parts of epoxy resin, and 200 to 300 parts of xylene. The trimethoxysilane can be at least one of methyltrimethoxysilane, propyltrimethoxysilane, and phenyltrimethoxysilane, and the epoxy resin is preferably epoxy resin E-20.

[0185] Comparing the test results of Application Example 1 and Application Examples 10 to 13, it can be seen that the comprehensive performance of the paint coatings of Application Example 1 and Application Example 11 is better, which means that when other raw material components of the dispersion remain unchanged, the addition amount of the silicone-modified epoxy resin prepolymer is preferably 66 to 96 parts. In Application Example 10 and Application Example 13, the addition amount of the silicone-modified epoxy resin prepolymer is too much, and the storage stability is reduced; in Application Example 12, the addition amount of the silicone-modified epoxy resin prepolymer is too little, and the stability of the prepared paint coating in water, acid, alkali or salt environment is reduced.

[0186] Comparing the test results of Application Example 1 and Application Examples 14 to 17, it can be seen that the comprehensive performance of Application Example 1 and Application Examples 14 to 15 is better. The acrylate mixed monomer is composed of the following components in parts by weight: 43 to 90 parts of acrylate monomer, 30 to 68 parts of styrene, and 23 to 31 parts of acrylic acid. The acrylate monomer is composed of methyl methacrylate and n-butyl methacrylate, and the prepared coating has better comprehensive performance.

[0187] Compared with Example 1, Comparative Example 1 directly uses epoxy resin E-20 to modify the alkyd resin, Comparative Example 2 directly uses silicone prepolymer to modify the alkyd resin, Comparative Example 3 uses epoxy resin E-20 and vinylsiloxysilane to modify the alkyd resin, and Comparative Examples 4 to 5 do not use silicone-modified epoxy resin prepolymer to modify the alkyd resin. The coatings prepared using the dispersions of Comparative Examples 1 to 5 have significantly worse stability in water, acid, alkali or salt environments than Example 1, and even have the problem of unstable storage.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite modified alkyd dispersion, characterized in that: The invention comprises the following raw materials in parts by weight: 66-160 parts of organosilicon-modified epoxy resin prepolymer, 210-220 parts of unsaturated oleic acid, 105-120 parts of polyol, 86-111 parts of polyacid, 15-34 parts of acid anhydride, 77-189 parts of acrylate mixed monomer, 0.1-0.5 parts of catalyst, 80-110 parts of first organic solvent, 2-6 parts of initiator, 31-48 parts of neutralizer and 630-760 parts of deionized water; The organosilicon-modified epoxy resin prepolymer is prepared by hydrolyzing and condensing organosilicon monomers and reacting with epoxy resin; The acrylic ester mixed monomer comprises the following raw materials in parts by weight: 35 to 90 parts of acrylic ester monomer, 20 to 98 parts of vinyl monomer, and 22 to 34 parts of carboxyl functional monomer.

2. The composite modified alkyd dispersion according to claim 1, wherein The organosilicon-modified epoxy resin prepolymer is prepared by the following method: after mixing an organosilicon monomer and a water-soluble solvent, deionized water is uniformly added dropwise at 60-75° C. with stirring; after the addition is complete, the mixture is kept warm and stirred for 3-4 hours to hydrolyze and condense the organosilicon into an organosilicon intermediate; then, epoxy resin and a second organic solvent are added, and the mixture is stirred at 150-170° C. for 3-5 hours to obtain the organosilicon-modified epoxy resin prepolymer.

3. The composite modified alkyd dispersion according to claim 1, wherein The organosilicon-modified epoxy resin prepolymer comprises the following raw materials in parts by weight: 180-260 parts of organosilicon monomer, 50-70 parts of water-soluble solvent, 50-70 parts of deionized water, 800-1200 parts of epoxy resin, and 200-400 parts of a second organic solvent.

4. The composite modified alkyd dispersion according to claim 1, wherein The organic silicon monomer includes at least two of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, propyltrimethoxysilane, propyltriethoxysilane and tetraethyl orthosilicate.

5. The composite modified alkyd dispersion according to claim 1, wherein The epoxy resin includes at least one of bisphenol A epoxy resin E-51, bisphenol A epoxy resin E-44, bisphenol A epoxy resin E-20, bisphenol A epoxy resin E-12 and bisphenol A epoxy resin E-03.

6. The composite modified alkyd dispersion according to claim 1, wherein The acrylate monomer includes C1-C 18 Acrylate, the C1-C 18 The acrylic acid ester includes at least one of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate; the vinyl monomer includes at least one of styrene and α-methylstyrene; and the carboxyl functional monomer includes at least one of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and maleic anhydride.

7. The composite modified alkyd dispersion according to claim 1, wherein The initiator includes at least one of benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, tert-amyl peroxybenzoate, di-tert-butyl peroxide and di-tert-amyl peroxide.

8. A method for preparing a composite modified alkyd dispersion according to any one of claims 1 to 7, characterized in that: The steps include: (1) unsaturated oleic acid, polyol, polyacid, acid anhydride, catalyst, reflux solvent and organosilicon modified epoxy resin prepolymer are refluxed at 200-230° C., while being kept warm and stirred until the acid value of the reaction system reaches 3-5 mgKOH / g, the reflux solvent is removed under reduced pressure, the temperature is lowered to 125-150° C., and a first organic solvent is added for dilution to obtain a composite modified copolymer A; (2) adding the acrylic acid ester mixed monomer and the initiator dropwise to the composite modified copolymer A at 125-150° C. with stirring, and continuing to keep warm and stir for 1-3 hours after the addition is complete. After cooling, a neutralizing agent is added to obtain a composite modified copolymer B; (3) The composite modified copolymer B is mixed and dispersed with deionized water to obtain a composite modified alkyd dispersion.

9. The method for preparing the composite modified alkyd dispersion according to claim 8, wherein: In the step (2), the acrylic acid ester mixed monomer and the initiator are added dropwise at a uniform speed simultaneously, and the addition time is 3 to 4 hours.

10. Use of the composite modified alkyd dispersion according to any one of claims 1 to 7 in the preparation of water-based coatings.

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