CN115368521A - Phosphorus-containing copolymer emulsion and preparation method and application thereof - Google Patents

Abstract

The invention discloses a phosphorus-containing copolymer emulsion, a preparation method and application thereof. The method includes: (1) mixing and reacting isocyanate monomers, polyglycols, catalysts, first chain extenders, polyphosphate polyols, and second chain extenders to obtain phosphorus-containing polyurethane prepolymers on the main chain. (2) After mixing and reacting the phosphorus-containing polyurethane prepolymer on the main chain with the hydroxyl group-containing (meth)acrylate monomer, then adding alkali for neutralization reaction, so as to obtain the main chain with double bonds introduced at both ends Phosphorus-containing polyurethane prepolymer; (3) After mixing the phosphorus-containing polyurethane prepolymer on the main chain with double bonds introduced at both ends, vinyl monomers, and phosphorus-containing monomers containing polymerizable carbon-carbon double bonds, adding Stirring with water causes phase inversion, so as to obtain the emulsion of the oil-in-water system; (4) mixing and reacting the emulsion of the oil-in-water system with the initiator, so as to obtain the phosphorus-containing copolymer emulsion. The phosphorus-containing copolymer emulsion prepared by the method has excellent anti-corrosion and flame-retardant functions.

Description

Phosphorus-containing copolymer emulsion and its preparation method and application

technical field

The invention belongs to the technical field of fine chemicals and functional coatings, and in particular relates to a phosphorus-containing copolymer emulsion and its preparation method and application.

Background technique

With the development of society, metal structures, especially steel structures, are widely used in various fields of the national economy such as construction, chemical industry, bridges, and transportation. However, traditional metals have two disadvantages: First, steel is easily corroded in a complex environment. Globally, the loss caused by metal corrosion accounts for about 3-5% of the GDP of each country, which is far greater than that caused by natural disasters and various accidents. The loss has seriously affected human production and life. The second is that the steel structure will lose its support due to the decrease in strength in an environment higher than 500 ° C. Once a fire breaks out, the building will often collapse and bring catastrophic consequences. Improving the corrosion resistance and high temperature resistance of steel structures has always been a hot topic of concern.

There are two main ways to improve the corrosion resistance and high temperature resistance of steel structures: one is to improve the corrosion resistance and temperature resistance of the metal material itself, and the other is to apply a protective coating on the surface of the steel structure after forming and assembly. Among them, the method of coating protective coating has the characteristics of low manufacturing and maintenance costs, convenient construction, and high cost performance. Therefore, various anti-corrosion coatings and fire-resistant coatings have emerged as the times require, and have been widely used in the field of steel structure anti-corrosion and fire protection.

At present, the coatings used for steel structures are mainly solvent-based. The use of a large amount of organic solvents not only pollutes the environment, but also causes harm to human health. Therefore, water-based coatings for steel structures have achieved considerable development in recent years. Polyurethane emulsion and polyacrylate emulsion are two kinds of water-based coating film-forming resins widely used in the market at present. Polyurethane-acrylate copolymer emulsion organically combines the properties of polyurethane and polyacrylate, and has also been applied to a certain extent. However, the above-mentioned polymer emulsions, as film-formers of water-based anti-corrosion coatings for steel structures, have defects such as single function and insufficient anti-corrosion performance. In particular, the paint film is flammable and has no flame retardancy, which greatly limits its application in high-rise buildings and other fields. Applications.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. For this reason, an object of the present invention is to propose a kind of phosphorus-containing copolymer emulsion and its preparation method and application. The main chain and the side chain of the polyurethane-acrylate copolymer obtained by the method of the present application have introduced phosphorus elements, and the prepared phosphorus-containing copolymer emulsion has excellent anti-corrosion and flame-retardant functions. The phosphorus-containing copolymer emulsion is used as Water-based paint film-forming resin, which can significantly improve the adhesion, corrosion resistance and flame retardancy of the coating.

In one aspect of the present invention, the present invention provides a method for preparing a phosphorus-containing copolymer emulsion. According to an embodiment of the invention, the method includes:

(1) mixing reaction of isocyanate monomer, polyglycol, catalyst, first chain extender, polyphosphate polyol, second chain extender, so as to obtain the polyurethane prepolymer containing phosphorus on the main chain;

(2) After mixing the phosphorus-containing polyurethane prepolymer on the main chain with the hydroxyl group-containing (meth)acrylate monomer, and then adding alkali for neutralization reaction, in order to obtain the main chain with double bonds introduced at both ends Phosphorus-containing polyurethane prepolymers;

(3) After mixing the phosphorus-containing polyurethane prepolymer on the main chain with double bonds introduced into the two ends, vinyl monomers, and phosphorus-containing monomers containing polymerizable carbon-carbon double bonds, add water and stir to cause phase inversion, In order to obtain the emulsion of the oil-in-water system;

(4) Mixing and reacting the emulsion of the oil-in-water system with an initiator to obtain a phosphorus-containing copolymer emulsion.

According to the method for preparing a phosphorus-containing copolymer emulsion according to the above-mentioned embodiments of the present invention, first, the isocyanate monomer, polyglycol, catalyst, first chain extender, polyphosphate polyol, and second chain extender are mixed and reacted, Among them, the isocyanate group of the isocyanate monomer reacts with the hydroxyl groups in the polyglycol and polyphosphate polyol to obtain a phosphorus-containing polyurethane prepolymer on the main chain. Among them, polyphosphate polyol is a reactive flame retardant It is an agent with hydroxyl groups at both ends of its molecular chain, which can be copolymerized with polyurethane. When the polymer is heated, the polyphosphate polyol can decompose to form a non-flammable liquid film, and its boiling point can reach 300 ° C. At the same time, phosphoric acid is further dehydrated to form partial Phosphoric acid, and then polymerized to generate polymetaphosphoric acid. In this process, not only the covering layer generated by phosphoric acid has a covering effect, but also the generated polymetaphosphoric acid is a strong acid and a strong dehydrating agent, which dehydrates and carbonizes the polymer, changing It can understand the mode of the polymer combustion process and form a carbon film on its surface to isolate the air, so as to exert a stronger flame retardant effect. Then the phosphorus-containing polyurethane prepolymer on the main chain obtained above is mixed with a hydroxyl group-containing (meth)acrylate monomer. The two ends of the phosphorus-containing polyurethane prepolymer on the main chain contain isocyanate groups, and the phosphorus-containing polyurethane prepolymer on the main chain contains The isocyanate group at both ends of the polyurethane prepolymer reacts with the hydroxyl group of the hydroxyl-containing (meth)acrylate monomer, thereby introducing a carbon-carbon double bond at the two ends of the phosphorus-containing polyurethane prepolymer on the main chain; After the phosphorus-containing polyurethane prepolymer on the main chain with double bonds introduced at both ends is mixed with vinyl monomers and phosphorus-containing monomers containing polymerizable carbon-carbon double bonds, add water and stir to cause phase inversion, so that the reactants are mixed evenly , the emulsion of the oil-in-water system is obtained, that is, the vinyl monomer and the phosphorus-containing monomer containing a polymerizable carbon-carbon double bond are dispersed in the phosphorus-containing polyurethane prepolymer on the main chain with double bonds introduced at both ends, so that The emulsion can exist stably; finally, an initiator is added to the emulsion of the above-mentioned oil-in-water system, and the carbon-carbon double bonds at both ends of the main chain containing double bonds on the main chain of the phosphorus-containing polyurethane prepolymer and the carbon of the ethylenic monomers are introduced at both ends. The carbon-carbon double bond of the carbon-carbon double bond and the carbon-carbon double bond of the phosphorus-containing monomer containing the polymerizable carbon-carbon double bond undergoes a free radical addition reaction, thereby connecting the phosphorus element to the side chain of the polyurethane-acrylate copolymer, which contains a polymerizable The phosphorus-containing monomer with carbon-carbon double bond is a reactive anti-corrosion additive. When the emulsion is applied to the metal surface, the phosphorus-containing monomer containing polymerizable carbon-carbon double bond can chemically react with the metal surface to form a dense phosphating film, so as to achieve the effect of increasing adhesion and preventing corrosion. Thus, phosphorus is introduced into the main chain and side chain of the polyurethane-acrylate copolymer obtained by this method, and the prepared phosphorus-containing copolymer emulsion has excellent anti-corrosion and flame-retardant functions. The phosphorus-containing copolymer emulsion As a film-forming resin for water-based coatings, it can significantly improve the adhesion, corrosion resistance and flame retardancy of the coating.

In addition, the method for preparing the phosphorus-containing copolymer emulsion according to the foregoing embodiments of the present invention may also have the following technical features:

In some embodiments of the present invention, in step (1), the isocyanate monomer, polyglycol and catalyst are first mixed and reacted at 50-110°C for 1-5 hours, and then the first chain extender is added to react 2- 5 hours, then add polyphosphate polyol to react for 2-4 hours, and finally add the second chain extender to react for 1-4 hours. Thus, a polyurethane prepolymer containing phosphorus in the main chain can be prepared.

In some embodiments of the present invention, the molar ratio of the isocyanate monomer to the polyglycol is (2-20):1, preferably (3-15):1.

In some embodiments of the present invention, the molar ratio of the isocyanate monomer to the first chain extender is (1.3-6):1, preferably (1.5-3):1.

In some embodiments of the present invention, the molar ratio of the isocyanate monomer to the polyphosphate polyol is (2-500):1, preferably (2.5-200):1.

In some embodiments of the present invention, the molar ratio of the isocyanate monomer to the second chain extender is (5-40):1, preferably (5-20):1.

In some embodiments of the present invention, the isocyanate monomers include polyisocyanate monomers and/or diisocyanate monomers.

In some embodiments of the present invention, the diisocyanate monomers include isophorone diisocyanate, 1,4-toluene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate and diisocyanate At least one of cyclohexylmethane diisocyanate, preferably isophorone diisocyanate and/or 1,4-toluene diisocyanate.

In some embodiments of the present invention, the polyglycol is a hydroxyl-terminated polymer with an average molecular weight of 400-2500.

In some embodiments of the present invention, the polyglycol includes polyether diol and/or polyester diol, preferably the polyether diol with a molecular weight of 500-1500.

In some embodiments of the present invention, the polyether diol includes polypropylene glycol and/or cyclopoly(ethylene oxide-propylene oxide) diol.

In some embodiments of the present invention, the catalyst includes an organotin compound, preferably at least one of dibutyltin dilaurate and stannous octoate.

In some embodiments of the present invention, the first chain extender includes a carboxyl-containing chain extender and/or a sulfonate-containing chain extender, and the carboxyl-containing chain extender includes dimethylol propionic acid and/or two Methylolbutyric acid, the sulfonate-containing chain extender includes sodium ethylenediamine sulfonate and/or sodium 1,4-butanediol-2-sulfonate, preferably dimethylolpropionic acid and/or or dimethylolbutyrate.

In some embodiments of the present invention, the polyphosphate polyol includes at least one of ethyl phosphate diol, octanol polyoxyethylene ether phosphate and ethylene glycol polyoxyethylene ether phosphate, preferably ethyl phosphate Phosphate diols.

In some embodiments of the present invention, the second chain extender includes diols and/or diamines, and the diols include ethylene glycol, propylene glycol, 1,4-butanediol and 1,4-cyclohexyl At least one of diols, the diamines include at least one of ethylenediamine and diethyltoluenediamine, preferably 1,4-butanediol.

In some embodiments of the present invention, in step (2), after the phosphorus-containing polyurethane prepolymer on the main chain is cooled to 50-70°C, a hydroxyl-containing (meth)acrylate monomer is added for end-capping, and the reaction After 2-4 hours, cool down to 20-40°C, then add alkali for neutralization for 0.5-1 hour.

In some embodiments of the present invention, the molar ratio of the isocyanate monomer to the hydroxyl-containing (meth)acrylate monomer is (2-10):1, preferably (3-6):1.

In some embodiments of the present invention, the hydroxyl-containing (meth)acrylate monomers include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and N-hydroxyethyl At least one of acrylamide, preferably hydroxyethyl methacrylate and/or hydroxypropyl methacrylate.

In some embodiments of the present invention, the base includes an organic base and/or an inorganic base, preferably an organic base, most preferably triethylamine and/or 2-amino-2-methyl-1-propanol.

In some embodiments of the present invention, in step (3), the ethylenic monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate At least one of ester, glycidyl methacrylate, isobornyl methacrylate and styrene, preferably n-butyl acrylate and/or methyl methacrylate.

In some embodiments of the present invention, the phosphorus-containing monomers containing polymerizable carbon-carbon double bonds include vinyl alkoxy phosphate, methacrylate-2-hydroxyethyl phosphate, polyethylene glycol methyl At least one of acrylate phosphate and alkyl acrylate phosphate, preferably at least one of methacrylate-2-hydroxyethyl phosphate and alkyl acrylate phosphate.

In some embodiments of the present invention, the molar ratio of the isocyanate monomer, vinyl monomer and phosphorus-containing monomer containing a polymerizable carbon-carbon double bond is (2-80):(10-300):1, preferably (2-20):(15-200):1.

In some embodiments of the present invention, in step (4), the emulsion of the oil-in-water system is heated to 60-90°C, and then the initiator is added and the reaction is continued for 2-4 hours to obtain a phosphorus-containing copolymer lotion.

In some embodiments of the present invention, the molar ratio of the ethylenic monomer to the initiator is (100-500):1, preferably (200-400):1.

In some embodiments of the present invention, the initiator includes a water-soluble peroxide, and the water-soluble peroxide includes potassium persulfate and/or ammonium persulfate.

In some embodiments of the present invention, the solid content of the phosphorus-containing copolymer emulsion is 30%-60%.

In some embodiments of the present invention, the average particle diameter of the phosphorus-containing copolymer emulsion is 60-500 nanometers.

In another aspect of the present invention, the present invention provides a phosphorus-containing copolymer emulsion. According to an embodiment of the present invention, the phosphorus-containing copolymer emulsion is prepared by the above method. Therefore, the phosphorus-containing copolymer emulsion has excellent anti-corrosion and flame-retardant functions.

In the third aspect of the present invention, the present invention provides an anti-corrosion and flame-retardant coating. According to an embodiment of the present invention, the anti-corrosion and flame-retardant coating includes the above-mentioned phosphorus-containing copolymer emulsion. Thus, the coating has strong adhesion, corrosion resistance and flame retardancy.

In the fourth aspect of the present invention, the present invention provides a metal structure. According to an embodiment of the present invention, the metal structure includes a metal base and a coating, the coating is formed on at least part of the surface of the metal base, wherein the coating is formed using the above-mentioned anti-corrosion and flame-retardant coating. Thus, the metal structural part is resistant to corrosion and high temperature.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is a schematic flow chart of a method for preparing a phosphorus-containing copolymer emulsion according to an embodiment of the present invention.

Detailed ways

The following detailed descriptions of the embodiments of the present invention are intended to explain the present invention, but should not be construed as limiting the present invention.

In one aspect of the present invention, the present invention provides a method for preparing a phosphorus-containing copolymer emulsion. According to an embodiment of the invention, the method includes:

S100: Mix and react isocyanate monomer, polyglycol, catalyst, first chain extender, polyphosphate polyol, and second chain extender

In this step, the isocyanate monomer, polyglycol, catalyst, first chain extender, polyphosphate polyol, and second chain extender are mixed and reacted, wherein, the isocyanate group of the isocyanate monomer is mixed with polyglycol and poly The hydroxyl group in the phosphate polyol reacts to obtain a phosphorus-containing polyurethane prepolymer on the main chain. The polyphosphate polyol is a reactive flame retardant with hydroxyl groups at both ends of its molecular chain, which can be copolymerized with polyurethane. When the polymer is heated, the polyphosphate polyol can decompose to form a non-combustible liquid film, and its boiling point can reach 300 ° C. At the same time, phosphoric acid is further dehydrated to form metaphosphoric acid, and then polymerized to form polymetaphosphoric acid. The covering layer generated by phosphoric acid has a covering effect, and the generated polymetaphosphoric acid is a strong acid and a strong dehydrating agent, which dehydrates and carbonizes the polymer, changes the mode of the polymer combustion process and forms a carbon film on its surface to insulate Air, so as to exert a stronger flame retardant effect, and at the same time, both ends of the phosphorus-containing polyurethane prepolymer on the main chain contain isocyanate groups.

It should be noted that the isocyanate monomer, polyglycol, catalyst, first chain extender, polyphosphate polyol and second chain extender are conventional reagents in the field, and those skilled in the art can choose according to the actual situation. For example, isocyanate monomers include polyisocyanate monomers and/or diisocyanate monomers, wherein polyisocyanate monomers include triphenylmethane triisocyanate, L-lysine triisocyanate and dimethyltriphenylmethane tetraisocyanate At least one of diisocyanate monomers including isophorone diisocyanate, 1,4-toluene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate and dicyclohexylmethane diisocyanate At least one of them, preferably isophorone diisocyanate and/or 1,4-toluene diisocyanate; polyglycol is a hydroxyl-terminated polymer with an average molecular weight between 400-2500, wherein polyglycol Including polyether diol and/or polyester diol, preferably polyether diol with molecular weight between 500-1500, polyether diol includes polypropylene glycol and/or cyclopoly(oxyethylene-propylene oxide ) diol; the catalyst includes an organotin compound, preferably at least one of dibutyltin dilaurate and stannous octoate; the first chain extender is a hydrophilic chain extender, and the first chain extender includes a carboxyl-containing chain extender And/or a sulfonate-containing chain extender, wherein the carboxyl-containing chain extender includes dimethylol propionic acid and/or dimethylol butanoic acid, and the sulfonate-containing chain extender includes ethylenediaminoethanesulfonic acid sodium and/or sodium 1,4-butanediol-2-sulfonate, preferably dimethylolpropionic acid and/or dimethylolbutyric acid; polyphosphate polyols including ethyl phosphate diol, octane At least one of alcohol polyoxyethylene ether phosphate and ethylene glycol polyoxyethylene ether phosphate, preferably ethyl phosphate diol; the second chain extender includes dibasic alcohol and/or diamine, wherein two Alcohols include at least one of ethylene glycol, propylene glycol, 1,4-butanediol and 1,4-cyclohexanediol, and diamines include at least one of ethylenediamine and diethyltoluenediamine, 1,4-Butanediol is preferred.

According to the embodiment of the present invention, the isocyanate monomer, polyglycol and catalyst are first mixed and reacted at 50-110°C for 1-5 hours, then the first chain extender is added to react for 2-5 hours, and then polyphosphoric acid is added The ester polyol is reacted for 2-4 hours, and finally the second chain extender is added to react for 1-4 hours. Specifically, first isocyanate monomer, polyglycol, catalyst and first chain extender react to generate polyurethane containing isocyanate groups, and the first chain extender contains hydrophilic groups, which can make the polyurethane prepolymer have macromolecular The role of emulsifier; then the isocyanate group in the polyurethane prepolymer reacts with the hydroxyl group in the polyphosphate polyol, so that the main chain of the polyurethane prepolymer contains a phosphoric acid functional group, and finally a second chain extender is added to increase the above-mentioned main chain. The molecular weight of the phosphorus-containing polyurethane prepolymer in the chain can be obtained to obtain the phosphorus-containing polyurethane prepolymer in the main chain. Compared with all products mixed and reacted together in one step, this partial reaction can effectively prevent the aggregation of similar functional groups, and make the functional groups such as carboxyl, phosphoric acid, amino and formate evenly distributed, which not only ensures the stability of the emulsion, but also increases the viscosity of the emulsion. Uniformity of performance.

According to an embodiment of the present invention, the molar ratio of the isocyanate monomer to the polyglycol is (2-20):1. The inventors have found that if the amount of polyglycol added is too much, the molecular weight of the polyurethane prepolymer increases greatly, thereby increasing the viscosity of the polyurethane prepolymer, which is unfavorable for the industrial synthesis and stability of the emulsion; if the polyglycol is added If the amount is too small, the molecular weight of the polyurethane prepolymer is small, and the film cannot achieve the ideal mechanical properties. Therefore, the present application chooses the molar ratio of isocyanate monomer to polyglycol to be (2-20): 1, which can make the emulsion have better stability, and the latex film has stronger mechanical properties. Preferably, the molar ratio of isocyanate monomer to polyglycol is (3-15):1.

According to an embodiment of the present invention, the molar ratio of the isocyanate monomer to the first chain extender is (1.3-6):1. The inventors have found that if the amount of the first chain extender added is too much, the hydrophilicity of the emulsion will obviously increase, and the water resistance of the latex film will decrease, which is not conducive to practical application; if the amount of the first chain extender added is too small, the stability of the emulsion will decrease. decline. Therefore, the present application chooses the molar ratio of the isocyanate monomer to the first chain extender to be (1.3-6): 1, which can achieve better water resistance under the condition of ensuring stable storage of the emulsion. Preferably, the molar ratio of the isocyanate monomer to the first chain extender is (1.5-3):1.

According to an embodiment of the present invention, the molar ratio of the isocyanate monomer to the polyphosphate polyol is (2-500):1. The inventors found that if the amount of polyphosphate polyol added is too much, the stability of the emulsion will decrease and the cost will increase. Therefore, this application selects the molar ratio of isocyanate monomer to polyphosphate polyol as (2-500): 1, which can ensure the flame retardancy and economy of the emulsion without destroying the original excellent properties of the emulsion. performance. Preferably, the molar ratio of isocyanate monomer to polyphosphate polyol is (2.5-200):1.

According to an embodiment of the present invention, the molar ratio of the isocyanate monomer to the second chain extender is (5-40):1. The inventors have found that if the amount of the second chain extender is too much, the molecular weight of the polymer will increase greatly, and the viscosity of the polyurethane prepolymer will increase, which is not conducive to the industrial synthesis and stability of the emulsion; if the amount of the second chain extender is too small, the The molecular weight of polyurethane prepolymer is small, and the film cannot achieve ideal mechanical properties. Therefore, the present application chooses the molar ratio of the isocyanate monomer to the second chain extender to be (5-40):1, which can make the emulsion have better stability and the latex film has stronger mechanical properties. Preferably, the molar ratio of the isocyanate monomer to the second chain extender is (5-20):1.

S200: After mixing the phosphorus-containing polyurethane prepolymer on the main chain with the hydroxyl-containing (meth)acrylate monomer, and then adding alkali for neutralization reaction

In this step, the phosphorus-containing polyurethane prepolymer on the main chain is mixed with the hydroxyl-containing (meth)acrylate monomer. Since the two ends of the phosphorus-containing polyurethane prepolymer on the main chain contain isocyanate groups, the The isocyanate group reacts with the hydroxyl group of the hydroxyl group-containing (meth)acrylate monomer, thereby introducing carbon-carbon double bonds at both ends of the phosphorus-containing polyurethane prepolymer on the main chain.

It should be noted that hydroxyl-containing (meth)acrylate monomers and bases are conventional reagents in the art, and those skilled in the art can select according to reality. For example, hydroxyl-containing (meth)acrylate monomers include hydroxyethyl acrylate , at least one of hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and N-hydroxyethylacrylamide, preferably hydroxyethyl methacrylate and/or hydroxypropyl methacrylate; Bases include organic and/or inorganic bases, preferably organic bases, most preferably triethylamine and/or 2-amino-2-methyl-1-propanol.

According to an embodiment of the present invention, after the phosphorus-containing polyurethane prepolymer on the main chain is cooled to 50-70°C, a hydroxyl group-containing (meth)acrylate monomer is added for capping, and the temperature is lowered to 20-20°C after reacting for 2-4 hours. 40°C, then add alkali for neutralization for 0.5-1 hour. First, the two ends of the phosphorus-containing polyurethane prepolymer on the main chain contain isocyanate groups, and the isocyanate groups at both ends react with the hydroxyl groups of the hydroxyl-containing (meth)acrylate monomers, thereby prepolymerizing the phosphorus-containing polyurethane on the main chain. Introduce carbon-carbon double bonds at both ends of the compound, and then add a base to neutralize the carboxyl and phosphoric acid groups in the phosphorus-containing polyurethane prepolymer on the main chain to increase the hydrophilicity of the molecular chain for subsequent phase inversion. Thus, a phosphorus-containing polyurethane prepolymer on the main chain with carbon-carbon double bonds introduced at both ends can be obtained.

According to an embodiment of the present invention, the molar ratio of the isocyanate monomer to the hydroxyl-containing (meth)acrylate monomer is (2-10):1. The inventors have found that if the molar ratio of the isocyanate monomer to the hydroxyl-containing (meth)acrylate monomer is less than 2, the carbon-carbon double bond content introduced on the phosphorus-containing polyurethane prepolymer molecular chain on the main chain is more, Cross-linking reaction is easy to occur to make the emulsion gel; if the molar ratio of isocyanate monomer to hydroxyl-containing (meth)acrylate monomer is greater than 10, the carbon introduced into the molecular chain of the phosphorus-containing polyurethane prepolymer on the main chain The content of carbon double bonds is too small, so that the probability of reaction between the ethylenic monomer and the phosphorus-containing polyurethane prepolymer on the main chain is reduced, and the two cannot be effectively combined. Thus, the molar ratio of the isocyanate monomer and the hydroxyl-containing (meth)acrylate monomer of the present application is (2-10): 1, which can effectively combine the phosphorus-containing polyurethane prepolymer on the main chain with the vinyl monomer Copolymerization of urethane-acrylic acid ester copolymer emulsion with excellent performance. Preferably, the molar ratio of the isocyanate monomer to the hydroxyl-containing (meth)acrylate monomer is (3-6):1.

S300: Mix the phosphorus-containing polyurethane prepolymer on the main chain with double bonds introduced at both ends, vinyl monomers, and phosphorus-containing monomers containing polymerizable carbon-carbon double bonds, then add water and stir

In this step, after the phosphorus-containing polyurethane prepolymer on the main chain with double bonds introduced at both ends is mixed with vinyl monomers and phosphorus-containing monomers containing polymerizable carbon-carbon double bonds, the phase is reversed by adding water and stirring, so that The reactants are mixed evenly to obtain an emulsion of the oil-in-water system, that is, the vinyl monomer and the phosphorus-containing monomer containing a polymerizable carbon-carbon double bond are wrapped on the main chain with double bonds introduced at both ends. The phosphorus-containing polyurethane prepolymerization The interior of the object, so that the emulsion can exist stably.

It should be noted that ethylenic monomers and phosphorus-containing monomers containing polymerizable carbon-carbon double bonds are conventional reagents in the art, and those skilled in the art can choose according to the actual situation. For example, ethylenic monomers include methyl acrylate, acrylic acid At least one of ethyl ester, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, isobornyl methacrylate and styrene, preferably n-acrylate Butyl and/or methyl methacrylate; phosphorus-containing monomers containing polymerizable carbon-carbon double bonds include vinyl alkoxy phosphate, 2-hydroxyethyl methacrylate phosphate, polyethylene glycol methyl At least one of methacrylate phosphate and alkyl acrylate phosphate, preferably at least one of methacrylate-2-hydroxyethyl phosphate and alkyl acrylate phosphate. At the same time, the stirring method is also a conventional method in the art, for example, using a stirrer to stir the above mixed solution at 20-50 degrees Celsius and 500-2000 rpm for 20-60 minutes.

According to an embodiment of the present invention, the molar ratio of the isocyanate monomer, the ethylenic monomer and the phosphorus-containing monomer containing a polymerizable carbon-carbon double bond is (20-80):(10-300):1. The inventors found that, If too much ethylenic monomer is added, the hydrophilicity of the copolymer emulsion will be insufficient and the mechanical toughness of the latex film will be reduced; if too little ethylenic monomer is added, the water resistance and hardness of the latex film will be insufficient; If too much bulk is added, the stability of the emulsion will decrease. Thus, the application adopts the molar ratio of isocyanate monomer, ethylenic monomer and phosphorus-containing monomer containing polymerizable carbon-carbon double bond as (2-80): (10-300): 1 addition, which can make Latex films have excellent stability, mechanical properties, barrier properties and corrosion resistance. Preferably, the molar ratio of the isocyanate monomer, the ethylenic monomer and the phosphorus-containing monomer containing a polymerizable carbon-carbon double bond is (2-20):(15-200):1.

S400: Mixing and reacting the emulsion of the oil-in-water system with the initiator

In this step, an initiator is added to the emulsion of the oil-in-water system prepared above, and the carbon-carbon double bonds at both ends of the phosphorus-containing polyurethane prepolymer on the main chain with double bonds introduced at both ends, and the carbon-carbon carbon-carbon bonds of the vinyl monomers The carbon-carbon double bond of the double bond and the carbon-carbon double bond of the phosphorus-containing monomer containing the polymerizable carbon-carbon double The phosphorus-containing monomer with carbon double bond is a reactive anti-corrosion additive. When the emulsion is applied to the metal surface, the phosphorus-containing monomer containing polymerizable carbon-carbon double bond can chemically react with the metal surface to form a dense phosphating film , so as to achieve the effect of increasing adhesion and preventing corrosion.

It should be noted that the initiator is a free radical initiator, which is a conventional reagent in the art, and those skilled in the art can select according to reality. For example, the initiator includes a water-soluble peroxide, and the water-soluble peroxide includes potassium persulfate and/or or ammonium persulfate.

According to an embodiment of the present invention, the temperature of the emulsion of the oil-in-water system is raised to 60-90° C., and then the reaction is continued for 2-4 hours after adding an initiator to obtain a phosphorus-containing copolymer emulsion.

According to an embodiment of the present invention, the molar ratio of the ethylenic monomer to the initiator is (100-500):1. The inventors have found that if the mol ratio of the vinyl monomer to the initiator is less than 100, the initiator concentration is too high, which may cause the explosion of the emulsion; if the molar ratio of the vinyl monomer to the initiator is greater than 500, the initiator If the concentration is too low, the monomer conversion rate will be reduced and VOC will be generated. Therefore, this application adopts the molar ratio of ethylenic monomer to initiator as (100-500): 1 addition amount, which can ensure the stable and uniform progress of the polymerization reaction at a relatively high monomer conversion rate. Preferably, the molar ratio of ethylenic monomer to initiator is (200-400):1.

Thus, phosphorus is introduced into the main chain and side chain of the polyurethane-acrylate copolymer obtained by this method, and the prepared phosphorus-containing copolymer emulsion has excellent anti-corrosion and flame-retardant functions. The phosphorus-containing copolymer emulsion As a film-forming resin for water-based coatings, it can significantly improve the adhesion, corrosion resistance and flame retardancy of the coating.

In another aspect of the present invention, the present invention provides a phosphorus-containing copolymer emulsion. According to an embodiment of the present invention, the phosphorus-containing copolymer emulsion is prepared by the above method. Therefore, the phosphorus-containing copolymer emulsion has excellent anti-corrosion and flame-retardant functions. It should be noted that the features and advantages described above for the method for preparing the phosphorus-containing copolymer emulsion are also applicable to the phosphorus-containing copolymer emulsion, and will not be repeated here.

According to an embodiment of the present invention, the solid content of the phosphorus-containing copolymer emulsion is 30%-60%. The inventors found that if the solid content of the phosphorus-containing copolymer emulsion is too high, the emulsion is unstable, and if the solid content of the phosphorus-containing copolymer emulsion is too low, the transportation cost increases. Therefore, using the phosphorus-containing copolymer emulsion with a solid content of 30%-60% of the present application can improve the stability of the emulsion and lower transportation costs. Further, the average particle diameter of the phosphorus-containing copolymer emulsion is 60-500 nanometers, thus, the dispersibility and affinity of the emulsion to pigments and fillers can be improved, the paint film is denser, and the neutralization performance of the paint film is improved. It is transparent, light blue to milky white, uniform and stable in nature, and will not separate after 6 months of storage at room temperature.

In the third aspect of the present invention, the present invention provides an anti-corrosion and flame-retardant coating. According to an embodiment of the present invention, the anti-corrosion and flame-retardant coating includes the above-mentioned phosphorus-containing copolymer emulsion. Thus, the coating has strong adhesion, corrosion resistance and flame retardancy. It should be noted that the features and advantages described above for the phosphorus-containing copolymer emulsion and its preparation method are also applicable to the anti-corrosion and flame-retardant coating, and will not be repeated here.

In the fourth aspect of the present invention, the present invention provides a metal structure. According to an embodiment of the present invention, the metal structure includes a metal base and a coating, and the coating is formed on at least part of the surface of the metal base, wherein the coating is formed using the above-mentioned anti-corrosion and flame-retardant coating. Thus, the metal structural part is resistant to corrosion and high temperature. It should be noted that the features and advantages described above for the anti-corrosion and flame-retardant coatings are also applicable to the metal structure, and will not be repeated here.

The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are only illustrative and do not limit the present invention in any way.

Example 1

(1) Add 5.2g (0.024mol) of isophorone diisocyanate, 4.0g (0.004mol) of polypropylene glycol-1000 and a drop of dibutyltin dilaurate into a three-necked flask and mix evenly. React for 2 hours, then add 1.4g (0.011mol) dimethylolpropionic acid for 3 hours, then add 0.6g (0.003mol) ethyl phosphate diol for 3 hours, then add 0.2g (0.002mol) 1 , 4-butanediol was reacted for 2 hours.

(2) Cool down to 60°C, add 0.7g (0.005mol) hydroxyethyl methacrylate for capping, react for 2 hours and cool down to 40°C, then add 1.1g (0.011mol) triethylamine for neutralization for 0.5 hours.

(3) Add 17.7g (0.177mol) methyl methacrylate, 17.7g (0.138mol) butyl acrylate and 0.6g (0.003mol) 2-hydroxyethyl methacrylate phosphate to the step (2) in the there-necked flask and mixed evenly, and then add 111 g of deionized water for phase inversion to obtain polyurethane-olefin monomer emulsion.

(4) Then the above-mentioned polyurethane-alkene monomer emulsion is warmed up to 80°C, and the aqueous solution containing 0.3g (0.001mol) of ammonium persulfate is dripped into the three-necked bottle, and the reaction is continued for 3 hours after the dropwise addition, and the mixture containing Phosphorus polyurethane-acrylate copolymer emulsion.

The solid content of the obtained phosphorus-containing polyurethane-acrylate copolymer emulsion was 30.1%, and the average particle diameter was 105.6 nanometers.

Example 2

(1) Add 5.2g (0.024mol) of isophorone diisocyanate, 4.0g (0.004mol) of polypropylene glycol-1000 and a drop of dibutyltin dilaurate into a three-necked flask and mix evenly. After reacting for 2 hours, 1.5 g (0.013 mol) of dimethylol butyric acid was added for reaction for 3 hours, and then 1.8 g (0.009 mol) of ethyl phosphate diol was added for reaction for 3 hours. Then add 0.2g (0.002mol) 1,4-butanediol to react for 2 hours.

(2) Cool down to 60°C, add 0.7g (0.005mol) hydroxyethyl methacrylate for capping, react for 2 hours and cool down to 40°C, then add 1.1g (0.011mol) triethylamine for neutralization for 0.5 hours.

(3) 10g (0.100mol) methyl methacrylate, 7.7g (0.074mol) styrene, 17.7g (0.060mol) butyl acrylate and 1.8g (0.009mol) methacrylic acid-2-hydroxy Ethyl ester phosphate was added to the three-necked flask in step (2) and mixed evenly, and then 111 g of deionized water was added to perform phase inversion to obtain a polyurethane-olefin monomer emulsion.

(4) Then the above-mentioned polyurethane-alkene monomer emulsion is warmed up to 80°C, and the aqueous solution containing 0.3g (0.001mol) of ammonium persulfate is dripped into the three-necked bottle, and the reaction is continued for 3 hours after the dropwise addition, and the mixture containing Phosphorus polyurethane-acrylate copolymer emulsion.

The solid content of the obtained phosphorus-containing polyurethane-acrylate copolymer emulsion was 30.2%, and the average particle diameter was 95.8 nanometers.

Example 3

(1) Add 5.2g (0.024mol) of isophorone diisocyanate, 1.8g (0.002mol) of polypropylene glycol-1000 and a drop of dibutyltin dilaurate into a three-necked flask and mix evenly. React for 2 hours, then add 1.9g (0.014mol) dimethylolpropionic acid for 3 hours, then add 0.6g (0.003mol) ethyl phosphate diol for 3 hours, then add 0.2g (0.002mol) 1 , 4-butanediol was reacted for 2 hours.

(2) Cool down to 60°C, add 0.7g (0.005mol) hydroxyethyl methacrylate for capping, react for 2 hours and cool down to 40°C, then add 1.1g (0.011mol) triethylamine for neutralization for 0.5 hours.

(3) Add 25.6g (0.254mol) methyl methacrylate, 25.6g (0.199mol) butyl acrylate and 0.6g (0.003mol) 2-hydroxyethyl methacrylate phosphate to the step (2) in the there-necked flask and mix evenly, then add 145g of deionized water to carry out phase inversion to obtain polyurethane-olefin monomer emulsion.

(4) Then the above-mentioned polyurethane-alkene monomer emulsion is warmed up to 80°C, and the aqueous solution containing 0.3g (0.001mol) of ammonium persulfate is dripped into the three-necked bottle, and the reaction is continued for 3 hours after the dropwise addition, and the mixture containing Phosphorus polyurethane-acrylate copolymer emulsion.

The solid content of the obtained phosphorus-containing polyurethane-acrylate copolymer emulsion was 30.1%, and the average particle diameter was 110.5 nanometers.

Example 4

(1) Add 5.2g (0.024mol) of isophorone diisocyanate, 5.6g (0.006mol) of polypropylene glycol-1000 and a drop of dibutyltin dilaurate into a three-necked flask and mix evenly. React for 2 hours, then add 1.6g (0.013mol) dimethylolpropionic acid for 3 hours, then add 0.6g (0.003mol) ethyl phosphate diol for 3 hours, then add 0.2g (0.002mol) 1 , 4-butanediol was reacted for 2 hours.

(2) Cool down to 60°C, add 0.7g (0.005mol) hydroxyethyl methacrylate for capping, react for 2 hours and cool down to 40°C, then add 1.3g (0.013mol) triethylamine for neutralization for 0.5 hour.

(3) Add 20.6g (0.205mol) methyl methacrylate, 20.6g (0.161mol) butyl acrylate and 0.6g (0.003mol) 2-hydroxyethyl methacrylate phosphate to the step (2) was mixed evenly in the three-necked flask, and then 130 g of deionized water was added for phase inversion to obtain a polyurethane-olefin monomer emulsion.

(4) Then the above-mentioned polyurethane-alkene monomer emulsion is warmed up to 80°C, and the aqueous solution containing 0.3g (0.001mol) ammonium persulfate is dropped into the reaction kettle drop by drop, and the reaction is continued for 3 hours after the dropwise addition to obtain the solution containing Phosphorus polyurethane-acrylate copolymer emulsion.

The obtained phosphorus-containing polyurethane-acrylate copolymer emulsion had a solid content of 31% and an average particle diameter of 100.4 nanometers.

Comparative example 1

Add 8.7g of isophorone diisocyanate, 10g of polypropylene glycol-1000 and a drop of dibutyltin dilaurate into a three-necked flask and mix evenly, and react at 80°C for 2 hours while stirring with an electric mixer, and then add 0.7g of dimethylol Propionic acid was reacted for 3 hours, then 1.4g of 1,4-butanediol was added to react for 2 hours, the temperature was lowered to 40°C, and 0.5g of triethylamine was added for neutralization for 0.5 hours, and then 50g of deionized water was added for phase inversion to obtain pure polyurethane emulsion.

Comparative example 2

5g methyl methacrylate, 5g butyl acrylate, 0.6g acrylic acid, 0.6g methacrylate-2-hydroxyethyl phosphate, 65g water, 0.9g OP-10, 0.9g sodium lauryl sulfate, Put 0.45g of sodium bicarbonate and 0.2g of ammonium persulfate into a three-necked flask, stir evenly and react at 80°C for 40 minutes, then mix monomers of 25g of methyl methacrylate, 25g of butyl acrylate and 1.4g of acrylic acid through peristaltic The pump is added dropwise into the three-necked flask, and the dropping time is 2 hours. While adding the mixed monomer dropwise, 10 ml of aqueous solution dissolved with 0.2 g of ammonium persulfate is dropped into the reaction flask through the peristaltic pump, and the dropping time is 2 hours. 2 hours. After adding all the materials dropwise, continue the reaction at 80°C for 2 hours, lower the temperature to below 40°C, add 10% dilute ammonia water dropwise until the pH of the emulsion is neutral, and obtain a pure polyacrylate emulsion.

Comparative example 3

Add 5.2g of isophorone diisocyanate, 4.0g of polypropylene glycol-1000 and a drop of dibutyltin dilaurate into a three-necked flask and mix evenly, and react at 80°C for 2 hours while stirring with an electric mixer, and then add 1.4g of dimethylol Propionic acid was reacted for 3 hours. Cool down to 60°C, add 0.7g of hydroxyethyl methacrylate for capping, react for 2 hours and cool down to 40°C, then add 1.1g of triethylamine for neutralization for 0.5 hours. Under stirring, 17.7 g of methyl methacrylate and 17.7 g of butyl acrylate were mixed evenly in the above-mentioned three-necked flask, and then 111 g of deionized water was added to perform phase inversion to obtain a polyurethane-olefin monomer emulsion. Raise the temperature of the polyurethane-olefin monomer emulsion to 80°C, drop the aqueous solution containing 0.3g of ammonium persulfate into the reaction kettle drop by drop, and continue to react for 3 hours after the dropwise addition, to obtain a phosphorus-free polyurethane-acrylate copolymer emulsion .

The adhesion, corrosion resistance and flame retardancy of the emulsion of embodiment 1-4 and comparative example 1-3 are tested, specifically as follows:

Adhesion test: Refer to GB/T 1720-2020 "Paint Film Circle Test".

Anti-corrosion performance test: refer to QB/T 3824-1999 "Test method for chemical protective layer of ferrous metals in light industrial products by dipping method".

Test vertical combustion: test with reference to GB/T 2408-2021 "Determination of Combustion Properties of Plastics by Horizontal and Vertical Methods". The prepared emulsion is configured into 20g/L～300g/L aqueous solution, and the cotton fabric is finished by dipping, padding, ultrasonic, etc. After drying and curing, the flame-retardant fabric can be obtained, and the flame-retardant fabric is tested for vertical combustion and limiting oxygen index.

See Table 1 for the test results of adhesion, corrosion resistance and flame retardancy of the emulsions of Examples 1-4 and Comparative Examples 1-3.

Table 1

As can be seen from the results in Table 1, compared to the emulsion without adding polyphosphate polyol and the phosphorus-containing monomer containing polymerizable carbon-carbon double bonds, the adhesion, resistance Corrosion and flame retardancy are significantly improved.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (10)

1. A method of making a phosphorus-containing copolymer emulsion, comprising:

(1) Mixing and reacting an isocyanate monomer, a polyglycol, a catalyst, a first chain extender, polyphosphate ester polyol and a second chain extender to obtain a polyurethane prepolymer containing phosphorus on a main chain;

(2) Mixing the polyurethane prepolymer containing phosphorus on the main chain with a hydroxyl (methyl) acrylate monomer for reaction, and then adding alkali for neutralization reaction to obtain the polyurethane prepolymer containing phosphorus on the main chain with double bonds introduced at two ends;

(3) Mixing the phosphorus-containing polyurethane prepolymer on the main chain with double bonds introduced at the two ends with an alkene monomer and a phosphorus-containing monomer containing polymerizable carbon-carbon double bonds, adding water, stirring and turning over so as to obtain an emulsion of an oil-in-water system;

(4) And mixing the emulsion of the oil-in-water system with an initiator for reaction so as to obtain the phosphorus-containing copolymer emulsion.

2. The method as claimed in claim 1, wherein in step (1), the isocyanate monomer, the polyglycol and the catalyst are mixed and then react at 50-110 ℃ for 1-5 hours, then the first chain extender is added to react for 2-5 hours, then the polyphosphate ester polyol is added to react for 2-4 hours, and finally the second chain extender is added to react for 1-4 hours;

optionally, the molar ratio of the isocyanate monomer to the polyglycol is (2-20): 1, preferably (3-15): 1;

optionally, the molar ratio of the isocyanate monomer to the first chain extender is (1.3-6): 1, preferably (1.5-3): 1;

optionally, the molar ratio of the isocyanate monomer to the polyphosphate polyol is (2-500): 1, preferably (2.5 to 200): 1;

optionally, the molar ratio of the isocyanate monomer to the second chain extender is (5-40): 1, preferably (5-20): 1.

3. the method of claim 1 or 2, wherein the isocyanate monomer comprises a diisocyanate monomer and/or a polyisocyanate monomer;

optionally, the diisocyanate monomer comprises at least one of isophorone diisocyanate, 1, 4-toluene diisocyanate, hexamethylene diisocyanate, 4' -diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate, preferably isophorone diisocyanate and/or 1, 4-toluene diisocyanate;

optionally, the polyglycol is a hydroxyl terminated polymer having an average molecular weight between 400 and 2500;

optionally, the polyglycol comprises polyether glycol and/or polyester glycol, preferably the polyether glycol has a molecular weight between 500 and 1500;

optionally, the polyether glycol comprises polypropylene glycol and/or cyclo poly (oxyethylene-oxypropylene) glycol and/or polytetrahydrofuran glycol;

optionally, the catalyst comprises an organotin compound, preferably at least one of dibutyltin dilaurate and stannous octoate;

optionally, the first chain extender comprises a carboxyl-containing chain extender and/or a sulfonate-containing chain extender, the carboxyl-containing chain extender comprises dimethylolpropionic acid and/or dimethylolbutyric acid, the sulfonate-containing chain extender comprises sodium ethylenediamine ethanesulfonate and/or sodium 1, 4-butanediol-2-sulfonate, and preferably dimethylolpropionic acid and/or dimethylolbutyric acid;

optionally, the polyphosphate polyol comprises at least one of ethyl phosphate dihydric alcohol, octanol polyoxyethylene ether phosphate and ethylene glycol polyoxyethylene ether phosphate, preferably ethyl phosphate dihydric alcohol;

optionally, the second chain extender comprises a diol comprising at least one of ethylene glycol, propylene glycol, 1, 4-butanediol, and 1, 4-cyclohexanediol and/or a diamine comprising at least one of ethylene diamine and diethyltoluene diamine, preferably 1, 4-butanediol.

4. The method according to claim 1, wherein in the step (2), the phosphorus-containing polyurethane prepolymer on the main chain is cooled to 50-70 ℃, then hydroxyl-containing (methyl) acrylate monomer is added for end capping, the temperature is cooled to 20-40 ℃ after the reaction is carried out for 2-4 hours, and then alkali is added for neutralization for 0.5-1 hour;

optionally, the molar ratio of the isocyanate monomer to the hydroxyl group-containing (meth) acrylate monomer is (2-10): 1, preferably (3-6): 1.

5. the method of claim 1 or 4, wherein the hydroxyl-containing (meth) acrylate monomer comprises at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and N-hydroxyethyl acrylamide, preferably hydroxyethyl methacrylate and/or hydroxypropyl methacrylate;

optionally, the base comprises an organic base and/or an inorganic base, preferably an organic base, most preferably triethylamine and/or 2-amino-2-methyl-1-propanol.

6. The method according to claim 1, wherein in step (3), the vinyl monomer comprises at least one of methyl acrylate, ethyl acrylate, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, isobornyl methacrylate, and styrene, preferably n-butyl acrylate and/or methyl methacrylate;

optionally, the phosphorus-containing monomer containing a polymerizable carbon-carbon double bond comprises at least one of a vinyl alkoxy phosphate, a 2-hydroxyethyl methacrylate phosphate, a polyethylene glycol methacrylate phosphate and an alkyl acrylate phosphate, preferably at least one of a 2-hydroxyethyl methacrylate phosphate and an alkyl acrylate phosphate;

optionally, the molar ratio of the isocyanate monomer, the alkene monomer and the phosphorus-containing monomer containing polymerizable carbon-carbon double bonds is (2-80): (10-300): 1, preferably (2-20): (15-200): 1.

7. the method of claim 1, wherein in the step (4), the emulsion of the oil-in-water system is heated to 60-90 ℃, and then the reaction is continued for 2-4 hours after the initiator is added, so as to obtain the phosphorus-containing copolymer emulsion;

optionally, the molar ratio of the alkene monomer to the initiator is (100-500): 1, preferably (200-400): 1;

optionally, the initiator comprises a water-soluble peroxide comprising potassium persulfate and/or ammonium persulfate;

optionally, the phosphorus-containing copolymer emulsion has a solids content of 30% to 60%;

optionally, the phosphorus-containing copolymer emulsion has an average particle size of 60 to 500 nanometers.

8. A phosphorus-containing copolymer emulsion prepared by the method according to any one of claims 1 to 7.

9. An anticorrosive flame-retardant coating, characterized in that it comprises the phosphorus-containing copolymer emulsion according to claim 8.

10. A metal structural member, comprising a metal substrate and a coating layer formed on at least a portion of the surface of the metal substrate, wherein the coating layer is formed by using the corrosion-resistant flame-retardant coating material according to claim 9.

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