Preparation method of emulsifier applied to acid resin emulsification and application thereof

Abstract

The application discloses a preparation method of an emulsifier applied to acid resin emulsification and application of the emulsifier, and comprises the following steps: S1, reacting a hydrophilic diisocyanate and a blocking agent to prepare a hydrophilic isocyanate partially blocked by the blocking agent; and S2, adding the hydrophilic isocyanate partially blocked by the blocking agent into a cosolvent and a diamine to prepare the emulsifier applied to acid resin emulsification. The emulsifier contains a hydrophilic sulfonate group and an amine group in a molecular structure, the amine group is neutralized with a carboxyl group in the acid resin to generate an ammonium salt with good hydrophilicity, and therefore, the emulsifier can play a role in internal emulsification, and the water solubility of the acid resin after emulsification is further improved. Moreover, the amine group in the emulsifier structure and the isocyanate group which is unblocked at high temperature can participate in a curing reaction of a resin system and become a part of a product structure, and therefore, there is no free emulsifier left, and the emulsifier applied to acid resin emulsification will not affect the water resistance, strength and other performances of the resin, and is a hydrophilic, convenient-to-use and low-cost emulsifier for acid resin.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis, and more particularly to a method for preparing an emulsifier for emulsifying acidic resins and its application. Background Technology

[0002] With increasingly stringent national environmental protection requirements and restrictions on VOC emissions, the chemical industry as a whole is gradually shifting towards water-based solutions. However, the water-based transformation of acidic resins faces bottlenecks. Currently, most manufacturers still use external emulsifiers such as sodium alkyl sulfonate, alkylbenzene sulfonate, and ether-based nonionic additives to emulsify oily acidic resins into water-based emulsions. Since these external emulsifiers do not react with the main components of the acidic resin emulsion during film formation, they remain free in the system after film formation, forming emulsifier residues. Relatively hydrophilic small-molecule emulsifiers are prone to free accumulation, creating water intrusion channels in the coating and reducing its water resistance.

[0003] Chinese Patent Publication No. CN113736029A discloses a core-shell structured vinyl chloride copolymer emulsion and its preparation method. The anionic and nonionic emulsifiers used in the preparation process lack reactive groups such as double bonds and hydroxyl groups. Therefore, even under the action of an initiator, they do not participate in the chain extension reaction between the soft and hard monomers. After the emulsion cures, both the anionic and nonionic emulsifiers remain in the waterborne polyvinyl chloride copolymer system as external emulsifiers, affecting the water resistance of the copolymer.

[0004] Chinese Patent Publication No. CN112708304A discloses a method for preparing a maleic rosin ester-acrylate composite emulsion for water-based inks. This method also uses emulsifiers such as sodium alkyl sulfonate, alkylbenzene sulfonate, and ether-based nonionic additives to emulsify maleic rosin ester and acrylate. During film formation of the water-based maleic rosin ester-acrylate composite emulsion, the emulsifier does not react with the effective components in the emulsion and remains free in the system, forming emulsifier residues that affect the water resistance of the coating film.

[0005] Chinese Patent Publication No. CN112724421A discloses a method for preparing alkyd resin emulsions. This method utilizes a modified epoxy emulsifier to prepare waterborne alkyd resin emulsions. The modified epoxy emulsifier acts as an emulsifier, and during film formation, the epoxy groups in the emulsifier structure undergo an epoxy carboxylation reaction with the carboxyl groups in the alkyd resin to produce an alkene oxide intermediate. Under the catalysis of an organic amine, a carboxylic acid is generated. Through a combination of internal and external emulsification, an emulsion with low particle size, suitable viscosity, and excellent water and salt spray resistance is obtained.

[0006] Based on the aforementioned invention patent, an emulsifier that can participate in the curing reaction of the resin system has been prepared, which will effectively promote the water-based nature of acidic resins and improve the water resistance of the coating film. Summary of the Invention

[0007] This invention provides a method for preparing an emulsifier for emulsifying acidic resins. The prepared emulsifier has a good emulsifying effect on acidic resins and can also participate in the curing reaction of the resin system without leaving any emulsifier residue.

[0008] The present invention solves its technical problem by adopting the following technical solution: A method for preparing an emulsifier for use in emulsifying acidic resins includes the following steps: S1: Hydrophilic diisocyanate and blocking agent are reacted to prepare hydrophilic isocyanate partially capped by blocking agent; S2: The hydrophilic isocyanate partially capped by the blocking agent is added to a cosolvent and a diamine to react and prepare an emulsifier for use in the emulsification of acidic resins.

[0009] As a preferred embodiment, in step S1, the hydrophilic diisocyanate and the blocking agent are reacted for 2-4 hours without heating, then the temperature is raised to 45-85℃ and reacted for 4-6 hours. After the NCO reaches the theoretical value, the temperature is lowered to room temperature to prepare a partially blocked hydrophilic isocyanate. In step S2, the prepared partially blocked hydrophilic isocyanate is stirred and mixed in a co-solvent environment until the temperature stops rising. A diamine is added, and the temperature is maintained at 50-60℃ for 4-6 hours to obtain an emulsifier for acidic resin emulsification.

[0010] As a preferred embodiment, the ratio of the sum of the moles of the blocking agent and the diamine to the moles of the hydrophilic diisocyanate is (2.1-2):1.

[0011] As a preferred embodiment, the molar ratio of the sealing agent to the diamine is 1:(1-1.1).

[0012] As a preferred embodiment, the hydrophilic diisocyanate is at least one of aqueous TDI, aqueous MDI, aqueous IPDI, aqueous HDI, and aqueous HMDI, and is provided by Foshan Jingxin Huiming Technology Co., Ltd.

[0013] As a preferred embodiment, the blocking agent is a compound containing active hydrogen, including at least one of methanol, ethanol, isopropanol, tert-butanol, 1,4-butanediol, neopentyl glycol, propylene glycol, propylene glycol monomethyl ether, methyl ethyl ketone oxime, acetone oxime, methyl isobutyl oxime, imidazole, 2-methylpyrazole, 3,5-dimethylpyrazole, 3-methyl-5-ethylpyrazole, 3-ethyl-5-propylpyrazole, acetylacetone, ethyl acetoacetate, diethyl malonate, caprolactam, phenol, and catechol.

[0014] As a preferred embodiment, the co-solvent includes at least one of propylene glycol methyl ether acetate, propylene glycol diacetate, propylene glycol polyether acetate, N-methylpyrrolidone, ethyl acetate, butyl acetate, cyclohexanone, and acetone. As a preferred embodiment, the diamine comprises at least one of sodium ethylenediaminoethanesulfonate (50% aqueous solution), sodium 2,4-diaminobenzenesulfonate, ethylenediamine, propylenediamine, cyclohexanediamine, and diethyltoluenediamine.

[0015] The present invention also provides an application of an emulsifier for emulsifying acidic resins in the emulsification of acidic resins.

[0016] As a preferred embodiment, the acidic resin includes one of acrylic resin, polyurethane resin, alkyd resin, unsaturated polyester resin, rosin resin, and ternary vinyl chloride resin.

[0017] The aforementioned emulsification method for acidic resin is achieved by adding an emulsifier used for emulsifying acidic resin to the acidic resin for emulsification and dispersion.

[0018] The emulsifier used for emulsifying acidic resins is an isocyanate with an amino group at one end and a capped end at the other.

[0019] The emulsifier used for emulsifying acidic resins is formed by partially end-capping hydrophilic diisocyanate and blocking agent in a cosolvent environment, followed by secondary end-capping with the addition of diamine.

[0020] The method for emulsifying an acidic resin involves adding acidic resin and an emulsifier for emulsifying the acidic resin to a four-necked reaction flask. The mass ratio of the acidic resin to the emulsifier is (10~30):1. At room temperature, under the action of a high-power stirrer with a power of 1000W or more, the stirring speed is 1500~2000r / min. Water is added in several batches for emulsification, with each addition being 30~60% of the total mass of water added, and the addition is completed in 2~3 batches. The ratio of the total mass of water added to the mass of the acidic resin is 50~100%. The resulting product is an aqueous resin.

[0021] If the acidic resin is a solid resin, it needs to be prepared into a solution by adding an organic solvent and then emulsified after appropriate heating. The specific solid content depends on the viscosity of the solution.

[0022] The emulsifier provided by this invention for emulsifying acidic resins incorporates a strong hydrophilic sulfonate group in its molecular structure. During the emulsification of acidic resins, the amine group in the emulsifier structure neutralizes the carboxyl group of the acidic resin to generate a hydrophilic ammonium salt. The hydrophilic group in the emulsifier structure and the newly generated ammonium salt encapsulate the molecules of the oily resin, forming an oil-in-water emulsion for internal emulsification. This allows the acidic resin to be easily dispersed in water, greatly improving the water solubility of the resulting water-based resin.

[0023] Emulsifiers used for emulsifying acidic resins have amine groups in their molecular structure. These amine groups react with the carboxyl groups in the acidic resin to form hydrophilic ammonium salts, resulting in a system with more hydrophilic groups than the added emulsifier. Only 5-10% of these emulsifiers are needed to achieve a good emulsification effect.

[0024] When waterborne resins prepared using emulsifiers applied to emulsify acidic resins are cured at high temperatures, the amine groups in the emulsifier structure react with the carboxyl groups in the acidic resin to form amide groups. The blocked isocyanate groups are also unblocked at high temperatures and react with the hydroxyl groups in the resin to form urethane groups. Therefore, the emulsifier becomes part of the cured resin structure, avoiding the impact of residual emulsifier on the water resistance and other chemical properties of waterborne products.

[0025] Based on the above summary, the advantages of this invention compared to the prior art are as follows: 1. This invention has low cost. Existing technologies require 1-3 times the mass of the raw materials to produce water-based products using low-boiling-point solvents. However, this invention, except for dissolving the solid resin during emulsification, does not require the addition of organic solvents to produce water-based products. Subsequent dilution can also use water instead of organic solvents.

[0026] 2. The product of this invention is easy to use. Water-based resins can be prepared simply by adding an emulsifier used for emulsifying acidic resins to the acidic resin, and then slowly adding water in portions for emulsification.

[0027] 3. The water-based resin obtained by emulsification of the product of this invention has good water solubility. Not only does the emulsifier contain hydrophilic sulfonate groups in its structure, but the amine groups in the emulsifier structure also neutralize the carboxyl groups in the acidic resin during emulsification to form hydrophilic ammonium salts, effectively improving the water solubility of the water-based resin.

[0028] 4. The product of this invention has a good emulsifying effect. The molecular structure of the emulsifier contains amine groups, which react with the carboxyl groups in the acidic resin to generate ammonium salts with good hydrophilicity. This results in the system having more hydrophilic groups than the added emulsifier, and only 5-10% is needed to achieve a good emulsifying effect.

[0029] 5. The waterborne resin obtained by emulsification of the product of this invention has no emulsifier residue after high-temperature curing. When the waterborne resin prepared by the product of this invention is cured at high temperature, the amine groups in the emulsifier structure react with the carboxyl groups in the acidic resin to form amide groups. At the same time, the blocked isocyanate groups are also unblocked at high temperature and react with the hydroxyl groups in the resin to form urethane groups. Therefore, the emulsifier becomes part of the cured resin structure, avoiding the impact of residual emulsifier on the water resistance and other chemical properties of the waterborne product.

[0030] The beneficial effects of this invention are as follows: This invention provides a method for preparing an emulsifier for emulsifying acidic resins and its application. By introducing a strong hydrophilic sulfonate group into the molecular structure of the emulsifier used for emulsifying acidic resins, and during the emulsification of acidic resins, the amine group in the emulsifier structure reacts with the carboxyl group in the acidic resin to form a hydrophilic ammonium salt, which greatly improves the water solubility of the resulting water-based resin. When the water-based resin prepared using the emulsifier for emulsifying acidic resins is cured at high temperature, the amine group in the emulsifier structure polymerizes with the carboxyl group in the acidic resin to generate amide groups, while the blocked isocyanate groups are also unblocked at high temperature and react with the hydroxyl groups in the resin to generate urethane groups. Therefore, the emulsifier becomes part of the cured resin structure, avoiding the decline in the water resistance and other chemical properties of water-based products due to residual emulsifier. This invention provides an emulsifier with better hydrophilicity, convenient use, and low cost for emulsifying acidic resins. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The raw materials used in the examples are described below: SSIPD-75 diisocyanate (sulfonate modified IPDI) is produced by Foshan Jingxin Huiming Technology Co., Ltd., with a solid content of 75%, a viscosity of 2800 mPa·s / 25℃, and an NCO content of 12.17% (i.e., the average molecular weight of the prepolymer is 467 g / mol).

[0033] SSHD-80 diisocyanate (sulfonate modified HDI) is produced by Foshan Jingxin Huiming Technology Co., Ltd., with a solid content of 80%, a viscosity of 11500 mPa·s / 25℃, and an NCO content of 14.2% (i.e., the average molecular weight of the prepolymer is 420 g / mol).

[0034] ACR6688 hydroxy acrylic resin is produced by Guangdong Tongde New Materials Co., Ltd., with a solid content of (61±2)% and a viscosity of 3000~4000mPa.s / 30℃.

[0035] AK3015 alkyd resin is produced by Guangdong Tongde New Materials Co., Ltd., with a solid content of (70±2)% and a viscosity of 1000~2000 mPa.s / 30℃.

[0036] Example 1 S1: In a four-necked reaction flask, add 100g SSIPDI-75 and 6.7g anhydrous ethanol, then allow the mixture to react naturally for 3 hours without heating. Then, heat the mixture to 65℃ and react for 5 hours. After the NCO value reaches 5.7%, cool the mixture to room temperature to obtain a hydrophilic isocyanate partially capped with ethanol.

[0037] S2 continues in a four-necked reaction flask, adding 20g of propylene glycol methyl ether acetate and stirring until well mixed. Then, 55g of sodium ethylenediamine ethanesulfonate is added and stirred until the temperature in the flask no longer rises. The reaction is maintained at 50°C for 5 hours, then cooled to room temperature. The product is discharged to obtain an emulsifier with a solid content of 60% for use in emulsifying acidic resins.

[0038] In a four-necked reaction flask, 100g of ACR6688 acrylic resin and 10g of the emulsifier prepared in Example 1 for emulsifying acidic resins were added. The mixture was heated to 70°C and reacted for 1 hour. Then, it was cooled to room temperature, and 15g of water was added while dispersing at 1500 rpm for 10 minutes to emulsify. Another 15g of water was added, and emulsification continued for another 10 minutes. Finally, 20g of water was added, and emulsification continued for another 10 minutes. The resulting product was a waterborne acrylic resin with a solid content of 41%. This waterborne resin was left at room temperature for 6 months without separation.

[0039] Example 2 In S1, 100g of SSHD-80 and 15g of methyl ethyl ketone oxime were added to a four-necked reaction flask. The mixture was allowed to react naturally for 2 hours without heating, and then heated to 60°C and reacted for 5 hours. After the NCO value reached 6.1%, the mixture was cooled to room temperature to obtain a partially capped hydrophilic isocyanate of methyl ethyl ketone oxime.

[0040] S2 continues in the four-necked reaction flask, adding 33g of propylene glycol methyl ether acetate and stirring until well mixed, then adding 63.3g of AAS and stirring until the temperature in the flask no longer rises. The reaction is maintained at 60°C for 6 hours, then cooled to room temperature, and the product is discharged to obtain an emulsifier with a solid content of 60% for use in the emulsification of acidic resins.

[0041] In a four-necked reaction flask, 100g of AK3015 alkyd resin and 5g of the emulsifier prepared in Example 2 for emulsifying acidic resins were added. The mixture was heated to 70°C and reacted for 1 hour. Then, it was cooled to room temperature, and while dispersing at 2000 rpm, 15g of water was added for emulsification for 10 minutes. Another 15g of water was added, and emulsification continued for another 10 minutes. Finally, 20g of water was added, and emulsification continued for another 10 minutes. The resulting product was a waterborne alkyd resin with a solid content of 47%. This waterborne resin was left at room temperature for 6 months without stratification.

[0042] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses conventional diisocyanates with the same reactive groups instead of the sulfonate-modified diisocyanate of the present invention. All other steps are the same.

[0043] In S1, 100g of IPDI (isophorone diisocyanate) and 20.5g of anhydrous ethanol were added to a four-necked reaction flask. The mixture was allowed to react naturally for 3 hours without heating, and then heated to 65°C and reacted for 5 hours. After the NCO value reached 15.6%, the mixture was cooled to room temperature to obtain ethanol-terminated diisocyanate.

[0044] S2 continues in the four-necked reaction flask, adding 73g of propylene glycol methyl ether acetate and stirring until well mixed, then adding 42.5g of sodium ethylenediamine ethanesulfonate and stirring until the temperature in the flask no longer rises. The reaction is maintained at 50°C for 5 hours, then cooled to room temperature, and the product is discharged to obtain an emulsifier with a solid content of 60% for use in emulsifying acidic resins.

[0045] In a four-necked reaction flask, 100g of ACR6688 acrylic resin and 10g of the emulsifier prepared in Comparative Example 1 for emulsifying acidic resins were added. The mixture was heated to 70℃ and reacted for 1 hour. Then, it was cooled to room temperature, and 15g of water was added while dispersing at 1500 rpm for 10 minutes for emulsification. Another 15g of water was added, and emulsification continued for another 10 minutes. Finally, 20g of water was added, and emulsification continued for another 10 minutes. The resulting product was a waterborne acrylic resin with a solid content of 42%. After being left at room temperature for 30 days, this waterborne resin showed signs of stratification.

[0046] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 uses methyl ethyl ketone oxime instead of the diamine of the present invention, while the other steps are the same.

[0047] S1: In a four-necked reaction flask, add 100g SSIPDI-75 and 6.7g anhydrous ethanol, then allow the mixture to react naturally for 3 hours without heating. Then, heat the mixture to 65℃ and react for 5 hours. After the NCO value reaches 5.7%, cool the mixture to room temperature to obtain a hydrophilic isocyanate partially capped with ethanol.

[0048] S2 continues in the four-necked reaction flask, adding 34g of propylene glycol methyl ether acetate and stirring until well mixed, then adding 13.2g of methyl ethyl ketone oxime and stirring until the temperature in the flask no longer rises. The reaction is maintained at 50°C for 5 hours, then cooled to room temperature, and the product is discharged to obtain an emulsifier with a solid content of 62% for use in emulsifying acidic resins.

[0049] In a four-necked reaction flask, 100g of ACR6688 acrylic resin and 10g of the emulsifier prepared in Comparative Example 2 for emulsifying acidic resins were added. At room temperature, while dispersing at 1500 rpm, 15g of water was added and emulsified for 10 minutes. Then, another 15g of water was added and emulsification continued for 10 minutes. Finally, 20g of water was added and emulsification continued for 10 minutes. The resulting product was a waterborne acrylic resin with a solid content of 42%. After the waterborne resin was left at room temperature for 7 days, it showed signs of stratification.

[0050] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that Comparative Example 2 uses 1,4-butanediol instead of the diamine of the present invention, while the other steps are the same.

[0051] S1: In a four-necked reaction flask, add 100g SSIPDI-75 and 6.7g anhydrous ethanol, then allow the mixture to react naturally for 3 hours without heating. Then, heat the mixture to 65℃ and react for 5 hours. After the NCO value reaches 5.7%, cool the mixture to room temperature to obtain a hydrophilic isocyanate partially capped with ethanol.

[0052] S2 continues in the four-necked reaction flask, adding 38g of propylene glycol methyl ether acetate and stirring until well mixed, then adding 13g of 1,4-butanediol and stirring until the temperature in the flask no longer rises. The reaction is maintained at 50°C for 5 hours, then cooled to room temperature, and the product is discharged to obtain an emulsifier with a solid content of 60% for use in the emulsification of acidic resins.

[0053] In a four-necked reaction flask, 100g of ACR6688 acrylic resin and 10g of the emulsifier prepared in Comparative Example 3 for emulsifying acidic resins were added. At room temperature, while dispersing at 1500 rpm, 15g of water was added and emulsified for 10 minutes. Then, another 15g of water was added and emulsification continued for 10 minutes. Finally, 20g of water was added and emulsification continued for 10 minutes. The resulting product was a waterborne acrylic resin with a solid content of 42%. After the waterborne resin was left at room temperature for 14 days, it showed signs of stratification.

[0054] Analyzing Examples 1-2 and Comparative Examples 1-3 above, the reason why the acidic resin emulsion prepared by the emulsifier of the present invention has good storage stability is that, compared with Comparative Example 1, Example 1-2 uses an aqueous diisocyanate containing a strongly hydrophilic sulfonate group in step S1, and a diamine in step S2, which gives the emulsifier structure an amine group at one end. The amine group can neutralize the carboxyl group of the acidic resin to form a hydrophilic ammonium salt, increasing the hydrophilic groups of the emulsifier. Therefore, Example 1-2 has good emulsifying performance. In contrast, Comparative Example 1 uses a conventional diisocyanate, which does not have a hydrophilic group in its structure. Only a small amount of sulfonate group is introduced in step S2. The emulsifier structure prepared only contains sulfonate groups, resulting in poor emulsifying ability for difficult-to-emulsify acidic resins, and therefore the prepared emulsion has poor stability. Although aqueous diisocyanates containing strong hydrophilic sulfonate groups were used in step S1 of Comparative Examples 2 and 3, diamines were not used in step S2. As a result, the emulsifiers prepared in this way do not have amine groups in their structure. When emulsifying acidic resins, they cannot generate ammonium salts with good hydrophilicity. Since the emulsifiers have fewer hydrophilic groups, their emulsifying ability is poor, and the emulsions prepared quickly separate into layers.

[0055] By comparing Examples 1-2 with Comparative Examples 1-3, it can be seen that the emulsifier prepared by the present invention can effectively emulsify acidic resins with water, and the emulsion does not separate into layers after being placed at room temperature for 6 months, indicating that the emulsifier prepared by the present invention emulsifies acidic resins into water-based resins, and the water-based resins have good stability.

[0056] When the waterborne acidic resin prepared by the emulsifier of this invention is cured at high temperature in subsequent applications, the amine group in the emulsifier structure reacts with the carboxyl group in the acidic resin to generate amide group. The isocyanate group blocked in the emulsifier structure is unblocked at high temperature and reacts with the hydroxyl group in the resin to generate urethane group. The emulsifier becomes part of the cured resin structure, and there are no residual small molecules of emulsifier. Therefore, it has basically no impact on the performance of the original acidic resin.

[0057] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical spirit of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing an emulsifier used in the emulsification of acidic resins, characterized in that, Includes the following steps: S1: The hydrophilic diisocyanate and the blocking agent are reacted for 2-4 hours without heating, and then the temperature is increased to 45-85℃ and reacted for 4-6 hours. After the NCO reaches the theoretical value, the temperature is reduced to room temperature to prepare the hydrophilic isocyanate with the blocking agent partially closed. S2: The hydrophilic isocyanate partially capped by the prepared blocking agent is stirred and mixed in a cosolvent environment until the temperature no longer rises. Diamine is added, and the temperature is maintained at 50~60℃. The reaction is carried out for 4~6 hours to obtain an emulsifier for acid resin emulsification. The ratio of the sum of the molar numbers of the blocking agent and the diamine to the molar number of the hydrophilic diisocyanate is (2.1-2):1; The blocking agent is a compound containing active hydrogen, including at least one of methanol, ethanol, isopropanol, tert-butanol, 1,4-butanediol, neopentyl glycol, propylene glycol, propylene glycol monomethyl ether, methyl ethyl ketone oxime, acetone oxime, methyl isobutyl oxime, imidazole, 2-methylpyrazole, 3,5-dimethylpyrazole, 3-methyl-5-ethylpyrazole, 3-ethyl-5-propylpyrazole, acetylacetone, ethyl acetoacetate, diethyl malonate, caprolactam, phenol, and catechol. The acidic resin includes one of acrylic resin and alkyd resin; The hydrophilic diisocyanate is at least one of SSIPD-75 diisocyanate and SSHD-80 diisocyanate; The diamine is sodium ethylenediamine ethanesulfonate.

2. The method for preparing an emulsifier for emulsifying acidic resins as described in claim 1, characterized in that, The ratio of the molar number of the blocking agent to the molar number of the diamine is 1:(1-1.1).

3. The method for preparing an emulsifier for emulsifying acidic resins as described in claim 1, characterized in that, The co-solvent includes at least one of propylene glycol methyl ether acetate, propylene glycol diacetate, propylene glycol polyether acetate, N-methylpyrrolidone, ethyl acetate, butyl acetate, cyclohexanone, and acetone.

4. The application of the emulsifier prepared by the method for preparing an emulsifier for emulsifying acidic resins as described in any one of claims 1-3 in the emulsification of acidic resins.

5. The application as described in claim 4, characterized in that, The acidic resin includes one of acrylic resin and alkyd resin.