A fire-retardant polyurethane exterior wall coating and a preparation method thereof

Abstract

The present application relates to the technical field of exterior wall coating, in particular to a kind of flame-retardant polyurethane exterior wall coating and preparation method thereof.The flame-retardant polyurethane exterior wall coating includes component A and component B;Component A includes the following substances:(1) unsaturated polyurethane resin emulsion;(2) antibacterial crosslinking agent prepared by first esterification reaction of dicarboxylic acid containing unsaturated bond with monohydroxy acrylate and alkyl alcohol containing halogenated hydrocarbon, and then quaternization reaction with tertiary amine containing unsaturated bond;(3) photoinitiator;(4) auxiliary agent;The auxiliary agent includes light calcium, kaolin, titanium dioxide, dispersing agent, defoaming agent, thickening agent;Component B includes diisocyanate and anti-UV curing agent.The prepared exterior wall coating is a kind of flame-retardant polyurethane exterior wall coating with durable antibacterial property, durable anti-UV performance and excellent mechanical property.

Description

Technical Field

[0001] This invention relates to the field of exterior wall coating technology, specifically to a flame-retardant polyurethane exterior wall coating and its preparation method. Background Technology

[0002] Polyurethane exterior wall coatings are a fundamental material in construction engineering, directly exposed to the outdoors and subjected to external forces such as wind, sun, rain, and snow. Therefore, key performance indicators are UV resistance and water resistance. Simultaneously, to enhance the functionality of exterior wall coatings, properties such as flame retardancy and antibacterial properties are typically added. Antibacterial properties can inhibit surface mold and other contaminants, reducing hydrolysis and powdering; flame retardancy can reduce the spread of fire and increase safety. However, in existing technologies, such as patents CN201310068838.X (a gray heat-insulating and flame-retardant exterior wall coating) and CN202210559735.2 (a heat-insulating exterior wall coating), low-reactivity antibacterial agents, flame retardants, and UV stabilizers are mixed with resin. These additives exhibit migration, leading to performance degradation with prolonged use; furthermore, their adhesion is low, making powdering likely.

[0003] On the other hand, while waterborne polyurethane coatings are environmentally friendly, their chains contain hydrophilic groups and have a linear structure, resulting in low curing efficiency, insufficient internal cross-linking, and poor mechanical strength. Meanwhile, single-stage UV-cured polyurethane coatings have a large shrinkage rate, leading to brittleness, low adhesion, poor mechanical strength, and cracking issues.

[0004] In summary, solving the above problems and preparing a flame-retardant polyurethane exterior wall coating is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a flame-retardant polyurethane exterior wall coating and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A flame-retardant polyurethane exterior wall coating, the flame-retardant polyurethane exterior wall coating comprising component A and component B; Component A includes the following substances: (1) unsaturated polyurethane resin emulsion; (2) an antibacterial crosslinking agent prepared by first esterifying a dicarboxylic acid containing unsaturated bonds with a monohydroxy acrylate and an alkyl alcohol containing a halogenated hydrocarbon, and then quaternizing it with a tertiary amine containing unsaturated bonds; (3) a photoinitiator; (4) additives; the additives include light calcium carbonate, kaolin, titanium dioxide, dispersant, defoamer, and thickener; Component B includes diisocyanate and UV-resistant curing agent.

[0007] Furthermore, in the antibacterial crosslinking agent, the molar ratio of dicarboxylic acid containing unsaturated bonds, monohydroxy acrylate, alkyl alcohol containing halogenated hydrocarbons, and tertiary amine containing unsaturated bonds is 1:1:1:(0.8~1).

[0008] Furthermore, the antibacterial crosslinking agent is prepared by first esterifying methylene succinic acid with hydroxyethyl acrylate and 4-chloro-1-butanol, and then quaternizing it with N,N-dimethylpropyleneamine.

[0009] Further, component A comprises the following substances by weight: 120-150 parts of unsaturated polyurethane resin emulsion, 8-12 parts of antibacterial crosslinking agent, 2-4 parts of photoinitiator, 5-8 parts of light calcium carbonate, 4-6 parts of kaolin, 12-16 parts of titanium dioxide, 0.2-0.5 parts of dispersant, 0.5-1 part of defoamer, and 2-4 parts of thickener.

[0010] Further, component B comprises the following substances: 5-6 parts by weight of diisocyanate and 8-10 parts by weight of UV-resistant curing agent.

[0011] Further, the UV-resistant curing agent is prepared from phytic acid, monohydroxy acrylate, hydroxybenzotriazole, and diisocyanate in a molar ratio of 1:1:(1~2):(3~4); the diisocyanate is at least one of hexamethyl diisocyanate, toluene diisocyanate, isoflurone diisocyanate, and lysine diisocyanate.

[0012] Furthermore, a method for preparing a flame-retardant polyurethane exterior wall coating includes the following steps: Step 1: Mix light calcium carbonate, kaolin, and titanium dioxide evenly, add them to the unsaturated polyurethane resin emulsion, add dispersant, and stir evenly; add antibacterial crosslinking agent and homogenize; add defoamer and thickener, and stir evenly; add pH adjuster to adjust pH to 8~9; add photoinitiator in the dark and stir evenly to obtain component A; Step 2: Mix the diisocyanate and UV curing agent evenly to obtain component B; Step 3: Mix component A and component B evenly to obtain flame-retardant polyurethane exterior wall coating.

[0013] Further, the preparation method of the antibacterial crosslinking agent is as follows: a dicarboxylic acid containing unsaturated bonds, a monohydroxy acrylate, an alkyl alcohol containing a halogenated hydrocarbon, p-toluenesulfonic acid, and an organic solvent are sequentially added to a reaction vessel; under a nitrogen atmosphere, the mixture is stirred at 60-65°C for 3-4 hours, reacted at 70-75°C for 0.5-1 hours, and then washed and dried; the mixture is dispersed in ethanol, and under a nitrogen atmosphere, the temperature is set at 45-50°C, and a dispersion of tertiary amine-ethanol containing unsaturated bonds is added dropwise, reacted for 2-3 hours, washed and dried to obtain the antibacterial crosslinking agent.

[0014] Further, the preparation method of the UV-resistant curing agent is as follows: phytic acid, monohydroxy acrylate, hydroxybenzotriazole, p-toluenesulfonic acid, and organic solvent are added sequentially to a reaction vessel and mixed evenly; the mixture is placed in a microwave reactor and reacted at 100-120°C for 60-120 seconds, then washed and dried; the mixture is dispersed in dimethyl sulfoxide to obtain solution A; solution A is added dropwise to a reaction vessel containing diisocyanate and stirred at 30-40°C for 2-4 hours; the solvent is removed by rotary evaporation to obtain the UV-resistant curing agent.

[0015] Further, the preparation method of the unsaturated polyurethane resin emulsion is as follows: polyether polyol, diisocyanate, dimethylformamide and catalyst are added sequentially to a reaction vessel, and the reaction is carried out at 70~80℃ for 3~5 hours under a nitrogen atmosphere. The temperature is then lowered to 50~60℃, and a chain extender is added to react for 2~3 hours. The temperature is then lowered to room temperature, triethylamine is added for neutralization, and deionized water is added for emulsification to obtain the unsaturated polyurethane resin emulsion.

[0016] In this technical solution, a crosslinking agent with antibacterial properties and a curing agent with UV resistance are prepared and then used in a polyurethane emulsion containing unsaturated groups to form a dual-curing exterior wall coating. The prepared exterior wall coating exhibits durable antibacterial properties, durable UV resistance, and excellent mechanical properties.

[0017] (1) In this scheme, the carboxyl group in a dicarboxylic acid containing an unsaturated bond is used to perform esterification grafting with a monohydroxy acrylate and a hydroxyl group in an alkyl alcohol containing a haloalkane. Then, a quaternization reaction is performed between the halogen group in the alkyl alcohol of the haloalkane and a tertiary amine to prepare an antibacterial crosslinking agent. Among them, the acrylate group has similar compatibility with the unsaturated polyurethane emulsion, and the unsaturated group can produce UV curing crosslinking; at the same time, the quaternary ammonium salt group is a hydrophilic structure, which can improve its dispersibility and antibacterial properties.

[0018] The introduction of antibacterial crosslinking agents improves the long-chain structure of polyurethane. Its crosslinking occurs within the coating, forming three-dimensional crosslinks, which enhances internal crosslinking, improves curing efficiency and mechanical properties, and effectively inhibits the migration of antibacterial agents, thus improving antibacterial durability. Simultaneously, the increased crosslinking density reduces internal porosity, effectively increasing water resistance. However, the content of the antibacterial crosslinking agent is limited; lower content leads to decreased performance, while higher content results in excessively high crosslinking density, causing microphase separation between the excess crosslinking agent and the polyurethane, increasing brittleness and thus reducing mechanical properties. Furthermore, the introduction of antibacterial crosslinking agents increases the viscosity of the coating, enhancing its adhesion.

[0019] (2) In this scheme, the carboxyl groups in phytic acid are used to perform a semi-esterification reaction (grafting acrylate and benzotriazole) with the hydroxyl groups in monohydroxy acrylate and hydroxybenzotriazole in a microwave reactor; then, the remaining phosphate groups are used to react with an isocyanate group in diisocyanate to obtain an anti-UV curing agent. Among them, benzotriazole is an excellent organic anti-UV additive that can effectively improve UV resistance. Similarly, its reaction grafting onto the curing agent can inhibit migration, thereby improving the longevity of UV resistance; while acrylate can be photocured for grafting. Since the anti-UV curing agent is prepared based on phytic acid and has a snowflake-like shape, it improves the toughness of the coating and synergistically improves the mechanical properties of the polyurethane exterior wall coating with the antibacterial crosslinking agent. In addition, the anti-UV curing agent also improves the viscosity of the coating and enhances the adhesion of the coating.

[0020] (3) In the scheme, the waterborne polyurethane is prepared by using polyether polyol and diisocyanate to obtain a prepolymer, and then using 3-(perfluorobutyl)-2-hydroxymethyl methacrylate and monohydroxy acrylate for chain extension. The fluorinated groups introduced therein effectively improve the water resistance.

[0021] (4) The exterior wall coating prepared contains a lot of fillers (light calcium carbonate, kaolin, titanium dioxide), which makes it flame retardant. It can work synergistically with phosphorus-containing UV curing agents and triazole-containing antibacterial crosslinking agents to improve the flame retardancy of the exterior wall coating, thus making the polyurethane exterior wall coating flame retardant. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0023] Figure 1 This is the chemical equation for preparing the antibacterial crosslinking agent in Example 1. Detailed Implementation

[0024] 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, and 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.

[0025] The following examples illustrate a small-scale process; wherein, methylene succinic acid (Chongqing Ruiya Biotechnology Co., Ltd.) has the product number 97-65-4; hydroxyethyl acrylate (Sigma-Aldrich Shanghai Trading Co., Ltd.) has the product number 292818; 4-chloro-1-butanol (Sigma-Aldrich Shanghai Trading Co., Ltd.) has the product number 278823; N,N-dimethylpropyleneamine (Shanghai Jizhi Biochemical Technology Co., Ltd.) has the product number N16220; and hydroxybenzotriazole (Hebei Zhentian Food Additives Co., Ltd.) has the product number Z. T-21407; Isophorone diisocyanate (Sigma-Aldrich Shanghai Trading Co., Ltd.) item number 8185860250; Polytetrahydrofuran ether diol (Hebei Zhentian Food Additives Co., Ltd.) item number ZT-19033667; Polypropylene glycol PPG-210 (Shanghai Beco Chemical Co., Ltd.) item number PPG1000; 3-(perfluorobutyl)-2-hydroxymethyl methacrylate (Nanjing Qiafenghe Pharmaceutical Technology Co., Ltd.) item number CHLF-01-362.

[0026] Example 1: Step 1: (1) 2.6g of methylene succinic acid, 2.3g of hydroxyethyl acrylate, 2.2g of 4-chloro-1-butanol, 0.05g of p-toluenesulfonic acid, and 15g of N,N-dimethylformamide were added sequentially to the reaction vessel; under a nitrogen atmosphere, the mixture was stirred at 65°C for 3.5 hours and reacted at 70°C for 1 hour, then washed and dried; it was dispersed in 15g of ethanol, and under a nitrogen atmosphere, the temperature was set at 50°C, and a dispersion of 1.5g of N,N-dimethylpropyleneamine-5g of ethanol was added dropwise at a rate of about 30 drops / minute, and the mixture was reacted for 3 hours, then washed and dried to obtain the antibacterial crosslinking agent.

[0027] (2) 13.2g of phytic acid, 2.3g of hydroxyethyl acrylate, 3.5g of hydroxybenzotriazole, 0.02g of p-toluenesulfonic acid and 20g of N,N-dimethylformamide were added to the reaction vessel in sequence and mixed evenly. The mixture was placed in a microwave reactor and reacted at 115°C for 100 seconds. The mixture was then washed and dried. The mixture was dispersed in 60g of dimethyl sulfoxide to obtain solution A. Solution A was added dropwise to a reaction vessel containing 16g of isophorone diisocyanate at a dropping rate of 20 drops / minute. The mixture was stirred at 35°C for 4 hours. Dimethyl sulfoxide was removed by rotary evaporation to obtain an anti-UV curing agent.

[0028] (3) 50g of polytetrahydrofuran ether glycol, 5g of polypropylene oxide glycol, 25g of isophorone diisocyanate and 0.15g of dibutyltin dilaurate were added to the reactor in sequence. The reaction was carried out at 75°C for 4 hours under a nitrogen atmosphere. The temperature was then lowered to 55°C, and 1g of 1,4-dibutanol, 8g of propyl 3-(perfluorobutyl)-2-hydroxymethyl methacrylate and 3g of hydroxyethyl acrylate were added. The reaction was carried out for 2 hours. The temperature was then lowered to 30°C, and 8g of triethylamine was added. The mixture was stirred for 20 minutes, and deionized water was added. The mixture was emulsified at 1200 rpm to obtain an unsaturated polyurethane resin emulsion with a solid content of 50wt%.

[0029] (4) Mix 6g of light calcium carbonate, 5g of kaolin, and 15g of titanium dioxide evenly, add them to 140g of unsaturated polyurethane resin emulsion, add 0.5g of BYK 190, stir evenly, add 10g of antibacterial crosslinking agent, homogenize at 1200rpm for 15 minutes, add 0.5g of polysiloxane diisobutyl ketone and 3g of sodium alginate, stir for 15 minutes, add pH adjuster to adjust pH=8.5; add 3g of photoinitiator TPO in the dark, stir for 30 minutes to obtain component A; Step 2: Mix 6g of isophorone diisocyanate and 8g of UV curing agent evenly to obtain component B.

[0030] Step 3: Mix component A and component B evenly to obtain flame-retardant polyurethane exterior wall coating.

[0031] Example 2: Step 1: (1) 2.6g of methylene succinic acid, 2.3g of hydroxyethyl acrylate, 2.2g of 4-chloro-1-butanol, 0.05g of p-toluenesulfonic acid, and 15g of N,N-dimethylformamide were added sequentially to the reaction vessel; under a nitrogen atmosphere, the mixture was stirred at 65°C for 3 hours and reacted at 70°C for 1 hour, then washed and dried; it was dispersed in 15g of ethanol, and under a nitrogen atmosphere, the temperature was set at 50°C, and a dispersion of 1.7g of N,N-dimethylpropyleneamine and 5g of ethanol was added dropwise at a rate of about 30 drops / minute, and the mixture was reacted for 3 hours, then washed and dried to obtain the antibacterial crosslinking agent.

[0032] (2) 13.2g of phytic acid, 2.3g of hydroxyethyl acrylate, 2.7g of hydroxybenzotriazole, 0.02g of p-toluenesulfonic acid, and 20g of N,N-dimethylformamide were added to the reaction vessel in sequence and mixed evenly. The mixture was placed in a microwave reactor and reacted at 100°C for 120 seconds. The mixture was then washed and dried. The mixture was dispersed in 60g of dimethyl sulfoxide to obtain solution A. Solution A was added dropwise to a reaction vessel containing 13.3g of isophorone diisocyanate at a rate of 20 drops / minute. The mixture was stirred at 30°C for 2 hours. The dimethyl sulfoxide was removed by rotary evaporation to obtain the UV-resistant curing agent.

[0033] (3) 50g of polytetrahydrofuran ether glycol, 5g of polypropylene oxide glycol, 25g of isophorone diisocyanate and 0.15g of dibutyltin dilaurate were added to the reactor in sequence. The reaction was carried out at 70°C for 5 hours under a nitrogen atmosphere. The temperature was then lowered to 50°C, and 1g of 1,4-dibutanol, 8g of 3-(perfluorobutyl)-2-hydroxymethyl methacrylate and 3g of hydroxyethyl acrylate were added. The reaction was carried out for 3 hours. The temperature was then lowered to 30°C, and 8g of triethylamine was added. The mixture was stirred for 20 minutes, and deionized water was added. The mixture was emulsified at 1200 rpm to obtain an unsaturated polyurethane resin emulsion with a solid content of 50wt%.

[0034] (4) Mix 5g of light calcium carbonate, 6g of kaolin, and 16g of titanium dioxide evenly, add them to 150g of unsaturated polyurethane resin emulsion, add 0.5g of BYK 190, stir evenly, add 12g of antibacterial crosslinking agent, homogenize at 1200rpm for 15 minutes, add 1g of polysiloxane diisobutyl ketone and 2g of sodium alginate, stir for 15 minutes, add pH adjuster to adjust pH=8.5; add 4g of photoinitiator TPO in the dark, stir for 30 minutes to obtain component A; Step 2: Mix 5g of isophorone diisocyanate and 10g of UV curing agent evenly to obtain component B.

[0035] Step 3: Mix component A and component B evenly to obtain flame-retardant polyurethane exterior wall coating.

[0036] Example 3: Step 1: (1) 2.6g of methylene succinic acid, 2.3g of hydroxyethyl acrylate, 2.2g of 4-chloro-1-butanol, 0.05g of p-toluenesulfonic acid, and 15g of N,N-dimethylformamide were added sequentially to the reaction vessel; under a nitrogen atmosphere, the mixture was stirred at 60°C for 4 hours and reacted at 75°C for 0.5 hours, then washed and dried; the mixture was dispersed in 15g of ethanol, and under a nitrogen atmosphere, the temperature was set at 45°C. A dispersion of 1.4g of N,N-dimethylpropyleneamine and 5g of ethanol was added dropwise at a rate of about 30 drops / minute. The mixture was reacted for 2 hours, then washed and dried to obtain the antibacterial crosslinking agent.

[0037] (2) 13.2g of phytic acid, 2.3g of hydroxyethyl acrylate, 5.4g of hydroxybenzotriazole, 0.02g of p-toluenesulfonic acid and 20g of N,N-dimethylformamide were added to the reaction vessel in sequence and mixed evenly. The mixture was placed in a microwave reactor and reacted at 120°C for 60 seconds. The mixture was then washed and dried. The mixture was dispersed in 60g of dimethyl sulfoxide to obtain solution A. Solution A was added dropwise to a reaction vessel containing 17.7g of isophorone diisocyanate at a dropping rate of 20 drops / minute. The mixture was stirred at 40°C for 4 hours. Dimethyl sulfoxide was removed by rotary evaporation to obtain the UV-resistant curing agent.

[0038] (3) 50g of polytetrahydrofuran ether glycol, 5g of polypropylene oxide glycol, 25g of isophorone diisocyanate and 0.15g of dibutyltin dilaurate were added to the reactor in sequence. The reaction was carried out at 80°C for 3 hours under a nitrogen atmosphere. The temperature was then lowered to 60°C, and 1g of 1,4-dibutanol, 8g of propyl 3-(perfluorobutyl)-2-hydroxymethyl methacrylate and 3g of hydroxyethyl acrylate were added. The reaction was carried out for 2 hours. The temperature was then lowered to 30°C, and 8g of triethylamine was added. The mixture was stirred for 20 minutes, and deionized water was added. The mixture was emulsified at 1200 rpm to obtain an unsaturated polyurethane resin emulsion with a solid content of 50wt%.

[0039] (4) Mix 8g of light calcium carbonate, 4g of kaolin, and 12g of titanium dioxide evenly, add them to 120g of unsaturated polyurethane resin emulsion, add 0.2g of BYK 190, stir evenly, add 8g of antibacterial crosslinking agent, homogenize at 1200rpm for 15 minutes, add 0.5g of polysiloxane diisobutyl ketone and 4g of sodium alginate, stir for 15 minutes, add pH adjuster to adjust pH=8.5; add 2g of photoinitiator TPO in the dark, stir for 30 minutes to obtain component A; Step 2: Mix 6g of isophorone diisocyanate and 8g of UV curing agent evenly to obtain component B.

[0040] Step 3: Mix component A and component B evenly to obtain flame-retardant polyurethane exterior wall coating.

[0041] Comparative Example 1: Rocima 361 was used as an antifungal agent and hexafluorobutyl acrylate was used as a crosslinking agent. The rest was the same as in Example 1. (4) Mix 6g of light calcium carbonate, 5g of kaolin, and 15g of titanium dioxide evenly, add them to 140g of unsaturated polyurethane resin emulsion, add 0.5g of BYK 190, stir evenly, add 2.5g of antifungal agent Rocima 361 and 10g of hexafluorobutyl acrylate, homogenize at 1200rpm for 15 minutes, add 0.5g of polysiloxane diisobutyl ketone and 3g of sodium alginate, stir for 15 minutes, add pH adjuster to adjust pH=8.5; add 3g of photoinitiator TPO in the dark, stir for 30 minutes to obtain component A; Comparative Example 2: The amount of antibacterial crosslinking agent used was increased, and the rest was the same as in Example 1; (4) Mix 6g of light calcium carbonate, 5g of kaolin, and 15g of titanium dioxide evenly, add them to 140g of unsaturated polyurethane resin emulsion, add 0.5g of BYK 190, stir evenly, add 15g of antibacterial crosslinking agent, homogenize at 1200rpm for 15 minutes, add 0.5g of polysiloxane diisobutyl ketone and 3g of sodium alginate, stir for 15 minutes, add pH adjuster to adjust pH=8.5; add 3g of photoinitiator TPO in the dark, stir for 30 minutes to obtain component A; Comparative Example 3: Hydroxyethyl acrylate was not introduced into the antibacterial crosslinking agent; otherwise, it was the same as in Example 1. Among them, (1) 2.6g of methylene succinic acid, 4.4g of 4-chloro-1-butanol, 0.05g of p-toluenesulfonic acid and 15g of N,N-dimethylformamide were added to the reaction vessel in sequence; under a nitrogen atmosphere, the mixture was stirred at 60~65℃ for 3.5 hours and reacted at 70℃ for 1 hour, then washed and dried; it was dispersed in 15g of ethanol, and under a nitrogen atmosphere, the temperature was set at 50℃, and a dispersion of 1.5g of N,N-dimethylpropyleneamine-5g of ethanol was added dropwise at a rate of about 30 drops / minute, and the mixture was reacted for 3 hours, then washed and dried to obtain the antibacterial crosslinking agent.

[0042] Comparative Example 4: The amount of hydroxyethyl acrylate grafted into the antibacterial crosslinking agent was increased, the amount of 4-chloro-1-butanol grafted was decreased, and the rest was the same as in Example 1; (1) 2.6g of methylene succinic acid, 3.48g of hydroxyethyl acrylate, 1.1g of 4-chloro-1-butanol, 0.05g of p-toluenesulfonic acid, and 15g of N,N-dimethylformamide were added sequentially to a reaction vessel; under a nitrogen atmosphere, the mixture was stirred at 60~65℃ for 3.5 hours, reacted at 70℃ for 1 hour, and then washed and dried; the mixture was dispersed in 15g of ethanol, and under a nitrogen atmosphere, the temperature was set at 50℃, and a dispersion of 1.5g of N,N-dimethylpropyleneamine-5g of ethanol was added dropwise at a rate of about 30 drops / minute, and the mixture was reacted for 3 hours, washed and dried to obtain an antibacterial crosslinking agent.

[0043] Comparative Example 5: Hydroxybenzotriazole was directly introduced, and the rest was the same as in Example 1; (4) Mix 6g of light calcium carbonate, 5g of kaolin, and 15g of titanium dioxide evenly, add them to 140g of unsaturated polyurethane resin emulsion, add 0.5g of BYK 190, stir evenly, add 10g of antibacterial crosslinking agent and 2g of hydroxybenzotriazole, homogenize at 1200rpm for 15 minutes, add 0.5g of polysiloxane diisobutyl ketone and 3g of sodium alginate, stir for 15 minutes, add pH adjuster to adjust pH=8.5; add 3g of photoinitiator TPO in the dark, stir for 30 minutes to obtain component A; Step 2: Use 12g of isophorone diisocyanate as component B.

[0044] Step 3: Mix component A and component B evenly to obtain flame-retardant polyurethane exterior wall coating.

[0045] Experiment: The flame-retardant polyurethane exterior wall coatings prepared in the examples and comparative examples were coated on a 3mm thick flat plate, with a coating thickness of 120μm. The UV dryer was set to an energy of 800mJ / cm². 2 Dry for 30 minutes; dry at 45℃ for 1 hour; cure for one week to obtain test plates. Take a 450mm×150mm test plate and place it in an artificial environment chamber. According to the standard GB / T23987, conduct aging resistance tests under the following conditions: ultraviolet irradiation, irradiation intensity of 45W / m². 2 The coating was dried for 5 hours at 50℃ and 10% relative humidity, followed by 1 hour of spraying at 25℃ with humidity uncontrolled. This spray-drying cycle was repeated, and the coating was observed for chalking or other abnormalities after 600 hours. Simultaneously, the coating was applied to test specimens, and 150mm × 70mm test panels were used. Adhesion was tested according to GB / T1720; antibacterial activity against E. coli before and after aging was tested according to GB / T21866; and tensile strength before and after aging was tested using a tensile testing machine according to JG / T172. The obtained data are shown below: Conclusion: The data in the table above show that the prepared flame-retardant polyurethane exterior wall coating has excellent water resistance and UV resistance, as well as good adhesion and strong mechanical properties. A comparison of the data from Example 1 and Example 5 shows that the prepared antibacterial crosslinking agent significantly improved the mechanical properties. However, due to the low reactivity of the antibacterial agent, the antibacterial activity decreased after aging. In Comparative Example 2, the excessive introduction of the antibacterial crosslinking agent led to a decrease in mechanical properties. In Comparative Example 3, the absence of hydroxyethyl acrylate in the antibacterial crosslinking agent resulted in a significant decrease in mechanical properties. In Comparative Example 4, the increased grafting amount of hydroxyethyl acrylate and the decreased grafting amount of 4-chloro-1-butanol resulted in a slight decrease in mechanical properties, and the reduced introduction of antibacterial segments further reduced the antibacterial activity. Similarly, in Comparative Example 5, the direct introduction of hydroxybenzotriazole reduced photocrosslinking, leading to a decrease in mechanical properties.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0047] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flame-retardant polyurethane exterior wall coating, characterized in that: The flame-retardant polyurethane exterior wall coating comprises component A and component B; Component A includes the following substances: (1) unsaturated polyurethane resin emulsion; (2) an antibacterial crosslinking agent prepared by first esterifying a dicarboxylic acid containing unsaturated bonds with a monohydroxy acrylate and an alkyl alcohol containing a halogenated hydrocarbon, and then quaternizing it with a tertiary amine containing unsaturated bonds; (3) a photoinitiator; (4) additives; the additives include light calcium carbonate, kaolin, titanium dioxide, dispersant, defoamer, and thickener; Component B includes diisocyanate and UV-resistant curing agent; The antibacterial crosslinking agent is prepared by first esterifying methylene succinic acid with hydroxyethyl acrylate and 4-chloro-1-butanol, and then quaternizing it with N,N-dimethylpropyleneamine. The method for preparing the antibacterial crosslinking agent is as follows: a dicarboxylic acid containing unsaturated bonds, a monohydroxy acrylate, an alkyl alcohol containing a halogenated hydrocarbon, p-toluenesulfonic acid, and an organic solvent are sequentially added to a reaction vessel; under a nitrogen atmosphere, the mixture is stirred at 60-65°C for 3-4 hours, reacted at 70-75°C for 0.5-1 hours, and then washed and dried; the mixture is dispersed in ethanol, and under a nitrogen atmosphere, the temperature is set at 45-50°C, and a dispersion of tertiary amine-ethanol containing unsaturated bonds is added dropwise, reacted for 2-3 hours, washed and dried to obtain the antibacterial crosslinking agent; The UV-resistant curing agent is prepared from phytic acid, monohydroxy acrylate, hydroxybenzotriazole and diisocyanate in a molar ratio of 1:1:(1~2):(3~4); the diisocyanate is at least one of hexamethyl diisocyanate, toluene diisocyanate, isoflurane diisocyanate and lysine diisocyanate. The method for preparing the UV-resistant curing agent is as follows: phytic acid, monohydroxy acrylate, hydroxybenzotriazole, p-toluenesulfonic acid, and organic solvent are added sequentially to a reaction vessel and mixed evenly; the mixture is placed in a microwave reactor and reacted at 100-120°C for 60-120 seconds, then washed and dried; the mixture is dispersed in dimethyl sulfoxide to obtain solution A; solution A is added dropwise to a reaction vessel containing diisocyanate and stirred at 30-40°C for 2-4 hours; the solvent is removed by rotary evaporation to obtain the UV-resistant curing agent.

2. The flame-retardant polyurethane exterior wall coating according to claim 1, characterized in that: The antibacterial crosslinking agent contains a dicarboxylic acid with unsaturated bonds, a monohydroxy acrylate, an alkyl alcohol with halogenated hydrocarbons, and a tertiary amine with unsaturated bonds in a molar ratio of 1:1:1:(0.8~1).

3. The flame-retardant polyurethane exterior wall coating according to claim 1, characterized in that: Component A comprises the following substances by weight: 120-150 parts of unsaturated polyurethane resin emulsion, 8-12 parts of antibacterial crosslinking agent, 2-4 parts of photoinitiator, 5-8 parts of light calcium carbonate, 4-6 parts of kaolin, 12-16 parts of titanium dioxide, 0.2-0.5 parts of dispersant, 0.5-1 part of defoamer, and 2-4 parts of thickener.

4. The flame-retardant polyurethane exterior wall coating according to claim 1, characterized in that: Component B comprises the following substances: by weight, 5-6 parts diisocyanate and 8-10 parts UV curing agent.

5. A method for preparing a flame-retardant polyurethane exterior wall coating, characterized in that: Includes the following steps: Step 1: Mix light calcium carbonate, kaolin, and titanium dioxide evenly, add them to the unsaturated polyurethane resin emulsion, add dispersant, and stir evenly; add antibacterial crosslinking agent and homogenize; add defoamer and thickener, and stir evenly; add pH adjuster to adjust pH to 8~9; add photoinitiator in the dark and stir evenly to obtain component A; Step 2: Mix the diisocyanate and UV curing agent evenly to obtain component B; Step 3: Mix component A and component B evenly to obtain flame-retardant polyurethane exterior wall coating.

6. The method for preparing a flame-retardant polyurethane exterior wall coating according to claim 5, characterized in that: The unsaturated polyurethane resin emulsion is prepared by: adding polyether polyol, diisocyanate, dimethylformamide, and catalyst sequentially into a reaction vessel, reacting at 70-80°C for 3-5 hours under a nitrogen atmosphere, cooling to 50-60°C, adding a chain extender, and reacting for 2-3 hours; cooling to room temperature, adding triethylamine for neutralization, and adding deionized water for emulsification to obtain the unsaturated polyurethane resin emulsion.

Images