Highly efficient fire-retardant and stain-resistant coating for building exterior walls

Abstract

This invention relates to the field of architectural coatings technology, specifically to a high-efficiency flame-retardant and stain-resistant exterior wall coating. Exterior wall coatings obtained by directly adding small-molecule flame retardants to the coating have poor compatibility with the polymer matrix, are prone to migration and precipitation, and exhibit unstable flame-retardant performance. To address these problems, this invention provides a high-efficiency flame-retardant and stain-resistant exterior wall coating, the formulation of which includes a self-made flame-retardant and stain-resistant modified acrylic emulsion. During the polymerization process of this emulsion, amphiphilic HCCP-AA-PFOT is used as a reactive emulsifier. The HCCP-AA-PFOT molecule contains both a cyclotriphosphonium flame-retardant structure and a perfluoroalkyl stain-resistant segment. HCCP-AA-PFOT is covalently bonded to the acrylic polymer backbone, overcoming the problems of easy migration and precipitation of small-molecule flame retardants, resulting in a more durable and stable flame-retardant and stain-resistant coating.

Description

Technical Field

[0001] This invention relates to the field of architectural coatings technology, specifically to a high-efficiency flame-retardant and stain-resistant exterior wall coating. Background Technology

[0002] As the "outer garment" of buildings, exterior wall coatings not only play an important role in beautifying the urban landscape, but also serve as a crucial barrier to protect the wall structure and extend the building's lifespan. With increasing societal focus on building safety, energy conservation, environmental protection, and long-term maintenance costs, the market demand for high-performance exterior wall coatings has shifted from basic decoration and protection to a trend towards multi-functional coatings that integrate flame retardancy, safety, easy cleaning, stain resistance, durability, and environmental friendliness.

[0003] Imparting flame retardancy to coatings typically involves adding flame retardants, such as aluminum hydroxide, intumescent flame retardants (IFR), or halogenated flame retardants. However, these physical blending methods have significant drawbacks: 1) Small molecule flame retardants have poor compatibility with the polymer matrix, easily migrating and precipitating (commonly known as "frosting"), leading to a rapid decline in flame retardant efficacy over time; 2) Excessive addition (usually requiring a high addition rate of 20-40%) severely damages the mechanical properties, adhesion, and weather resistance of the coating film, while also affecting the dispersion stability of pigments and fillers, resulting in surface defects in the coating; 3) Some halogenated flame retardants produce toxic and corrosive gases during combustion.

[0004] Stain resistance is crucial for maintaining a building's appearance and reducing cleaning and maintenance costs. Existing stain-resistant technologies primarily rely on adding silicone or fluorine-containing additives to the formulation. These additives migrate to the paint film surface, utilizing their extremely low surface energy to achieve hydrophobic and oleophobic effects. However, this physical migration mode has persistence issues: small-molecule additives gradually dissipate due to wind, sun, and rain, making it difficult to maintain the stain-resistant effect in the long term. Summary of the Invention

[0005] The existing technology has the problem that building exterior wall coatings obtained by directly adding flame retardants to the coating have poor compatibility between small molecule flame retardants and the polymer matrix, making them prone to migration and precipitation, resulting in unstable flame retardant performance. To address the above technical problems, this invention provides a high-efficiency flame-retardant and stain-resistant building exterior wall coating, which, by weight, comprises the following components:

[0006] 100 parts of flame-retardant and stain-resistant modified acrylic emulsion;

[0007] 30-40 parts of pigments and fillers;

[0008] 3-5 parts zinc borate;

[0009] 3.5-5.5 parts of auxiliary agent;

[0010] Film-forming aid 1.5-2.5 parts;

[0011] 1.5-2.5 parts of ethylene glycol;

[0012] pH adjuster 0.8-1.5 parts;

[0013] 8-12 parts water.

[0014] Preferably, the pH adjuster is AMP-95 or ammonia.

[0015] Preferably, the flame-retardant and stain-resistant modified acrylic emulsion is obtained by seed emulsion polymerization and comprises the following raw material components by weight:

[0016] 45-55 parts deionized water;

[0017] Amphiphilic cyclic triphosphonium derivative (HCCP-AA-PFOT) 3-8 parts;

[0018] Sodium bicarbonate (NaHCO3) 0.1-0.3 parts;

[0019] 12-15 parts of methyl methacrylate (MMA);

[0020] Butyl acrylate (BA) 52-55 parts;

[0021] Acrylic acid (AA) 1-2 parts;

[0022] Hydroxyethyl methacrylate (HEMA) 1-1.5 parts;

[0023] 1H,1H,2H,2H-Perfluorooctyl methacrylate (DFHMA) 1-1.5 parts;

[0024] Initiator (the initiator is a persulfate initiator, specifically potassium persulfate or ammonium persulfate) 0.3-0.5 parts.

[0025] Preferably, the preparation method of the HCCP-AA-PFOT includes the following steps:

[0026] (1) The amino group of allylamine undergoes a nucleophilic substitution reaction with the chlorine atom in hexachlorocyclotriphosphazene (HCCP) to obtain double bond modified cyclotriphosphazene. The molar ratio of allylamine to hexachlorocyclotriphosphazene is 3:1 to 4:1.

[0027] (2) Double-bond modified cyclotriphosphonium undergoes a conventional mercapto-alkene click reaction with 2-mercaptoethanol. Double-bond modified cyclotriphosphonium reacts with 2-mercaptoethanol to obtain modified cyclotriphosphonium compound I. The molar ratio of double-bond modified cyclotriphosphonium to 2-mercaptoethanol is 1:1.5~1:1.8.

[0028] (3) Modified cyclotriphosphonon compound I reacts with excess 1H,1H,2H,2H-perfluorooctyl mercaptan to undergo a mercapto-alkene click reaction to obtain HCCP-AA-PFOT.

[0029] Preferably, the specific preparation method of the HCCP-AA-PFOT is as follows:

[0030] (1) Under the protection of inert gas or nitrogen, 5.00 g HCCP (14.4 mmol) was stirred and dissolved in 100 mL anhydrous THF. The reaction system was placed in a low temperature bath and cooled to -20℃.

[0031] (2) Dissolve 3.22-4.32 mL of allylamine (43-57.6 mmol) in 20 mL of anhydrous THF to form an allylamine solution. Add the allylamine solution dropwise to the reaction system in step (1). During the dropwise addition, keep the reaction temperature below -10℃. After the dropwise addition is complete, stir the reaction at -20℃ for at least 2 hours. After the reaction is complete, remove the ice bath and allow the reaction system to naturally warm up to room temperature. Continue stirring the reaction for at least 12 hours.

[0032] (3) After the reaction in step (2) is completed, the obtained reaction solution is centrifuged and the supernatant is collected. The obtained supernatant is then concentrated by rotary evaporation and added dropwise to 100 mL of cold n-hexane (0℃) for precipitation. The white solid precipitate is then collected by centrifugation. The white solid precipitate is then washed three times with cold n-hexane and dried under vacuum to obtain the target intermediate. After the reaction is completed, an active amino group is introduced into the cyclotriphosphonium molecule structure.

[0033] (4) Under inert gas or nitrogen protection, 1.3 g of the target intermediate was dissolved in 60 mL of anhydrous THF. Then, 4.8 mmol of 2-mercaptoethanol and 50 mg of 2-dimethylamino-2-methylphenylacetone (DMPA, photoinitiator) were added to the reaction system. After stirring evenly, the mixture was irradiated under UV light (25-30℃) for 1.5 h while stirring vigorously. The UV light was then turned off (after the first photoreaction, a hydroxyl hydrophilic group was introduced into the structure of the target intermediate). 9.6 mmol of 1H,1H,2H,2H-perfluorooctyl mercaptan (PFOT) and 50 mg of 2-dimethylamino-2-methylphenylacetone (DMPA, photoinitiator) were added. After stirring evenly, the reaction was irradiated under UV light (25-30℃) again. The reaction was then analyzed by TLC (developing solvent: petroleum ether / ethyl acetate). Monitor the reaction progress. The reaction is complete when the product spots stabilize (after the second light irradiation reaction, a perfluoroalkyl antifouling hydrophobic segment was introduced into the target product structure).

[0034] (5) After the reaction is completed, the reaction solution obtained in step (4) is concentrated to dryness using a rotary evaporator to obtain a viscous crude product. The crude product is then dissolved in 10 mL of THF and added dropwise to 200 mL of ice-cold n-hexane (0 °C) while stirring vigorously to obtain a light yellow flocculent solid product. The solid product is collected by centrifugation. The obtained solid product is washed thoroughly with diethyl ether three times to remove unreacted thiols and initiator byproducts. The obtained solid product is then placed in a vacuum drying oven and vacuum dried at 40-45 °C for at least 24 h to obtain HCCP-AA-PFOT.

[0035] Preferably, the preparation method of the flame-retardant and stain-resistant modified acrylic emulsion is as follows:

[0036] Step (1) Preparation of pre-emulsion

[0037] Add 25.0 parts of deionized water, 2.0 parts of HCCP-AA-PFOT, 13 parts of MMA, 54 parts of BA, 2 parts of AA, 1.5 parts of HEMA and 1.5 parts of DFHMA to a beaker in sequence, homogenize and emulsify at high speed to obtain a uniform milky white pre-emulsion, and transfer it to a constant pressure dropping funnel for later use.

[0038] Step (II) Preparation of Seed Liquid

[0039] (1) Under nitrogen protection, add 20.0 parts of deionized water, 3.0 parts of HCCP-AA-PFOT and 0.2 parts of NaHCO3 to a four-necked flask, start stirring (200-250 rpm) for 20-30 min, raise the temperature of the reaction system to 78-80℃ and keep it constant.

[0040] (2) Weigh 0.4 parts of potassium persulfate and dissolve it in 5 parts of deionized water to obtain an initiator solution. Add 1 / 2 of the total amount of the initiator solution to the reaction system in step (1). Stir and observe that the system turns slightly blue and becomes opalescent. Continue to stir at a constant temperature for 15-20 minutes to obtain the seed liquid.

[0041] Step (3) Emulsion Polymerization

[0042] After the seed reaction in step (II) is completed, under nitrogen protection, the reaction temperature is controlled at 78±1℃. While stirring, the pre-emulsion obtained in step (I) and the remaining initiator solution are added dropwise. The dropping rate is controlled to ensure that the addition is completed within 2.5~3h. The stirring speed is 200-250 rpm to ensure uniform mixing and no emulsion breaking. After the addition is completed, the reaction system is kept at 78℃ and stirred for 1h to ensure complete monomer conversion. After the reaction is completed, the reaction system is naturally cooled to below 40℃. The pH of the emulsion is adjusted to 7.5~8.5 by stirring. The emulsion is filtered through a 100-mesh sieve, and the flame-retardant and stain-resistant modified acrylate emulsion is obtained.

[0043] Preferably, the pigments and fillers include one or more of rutile titanium dioxide, heavy calcium carbonate, and kaolin.

[0044] Preferably, the additives, by weight, include at least 0.6-1 parts wetting and dispersing agent, 0.3-0.5 parts defoamer and 0.2-0.6 parts thickener.

[0045] Preferably, the wetting and dispersing agent is BYK-190 or Tego-755W.

[0046] Preferably, the defoamer is a mineral oil-based defoamer or an organosilicon-based defoamer.

[0047] Preferably, the thickener is an alkali-swellable thickener; more preferably, the thickener is a hydrophobically modified alkali-swellable thickener.

[0048] Preferably, the hydrophobically modified alkali-swellable thickener is one or more of Dow Chemical ASE™ 60, BASF Rheovis® AS1130, and Clariant Rheolate® 210.

[0049] Preferably, the film-forming aid includes one or more of Eastman Texanol ester alcohol, BASF Loxanol CA5308, and Dow Chemical dodecyl alcohol ester. Beneficial effects

[0050] This invention provides a high-efficiency flame-retardant and stain-resistant exterior wall coating and its preparation method, which has the following advantages:

[0051] (1) This invention abandons the simple idea of ​​directly adding small molecule flame retardants and small molecule anti-fouling additives to coatings. Through molecular design, an HCCP-AA-PFOT with a cyclic triphosphonium flame retardant structure, perfluoroalkyl segments, hydroxyl groups and reactive double bonds is synthesized. This derivative can be directly used as a reactive emulsifier in emulsion polymerization and is covalently bonded to the acrylate polymer skeleton. This fundamentally solves the problem of easy migration and precipitation of small molecule functional additives leading to functional failure, making the flame retardancy and anti-fouling properties of the obtained building coating more durable and stable.

[0052] (2) The cyclotriphosphonium structure (from HCCP) in the HCCP-AA-PFOT structure obtained in this invention is a highly efficient phosphorus-nitrogen intumescent flame retardant. During combustion, it can promote the formation of a dense and solid char layer, effectively isolate oxygen and heat, and decompose to produce non-combustible gas to dilute combustibles. It has high flame retardant efficiency. This structure is chemically bonded to the acrylate skeleton, avoiding the negative impact of adding a large amount of inorganic flame retardant on the mechanical properties and workability of the paint film.

[0053] (3) The HCCP-AA-PFOT structure obtained in this invention also contains perfluoroalkyl segments, which give the paint film a low surface energy anti-fouling effect. The perfluorooctyl hydrophobic segments (from PFOT) introduced on the acrylate skeleton through chemical bonding can be stably enriched on the paint film surface to form a durable and efficient hydrophobic and oleophobic layer, giving the coating excellent anti-fouling and self-cleaning ability. Rainwater can wash it clean, which greatly reduces the maintenance and cleaning cost of buildings.

[0054] (4) In the process of synthesizing flame-retardant and stain-resistant modified acrylate emulsion by seed emulsion polymerization, this invention not only adds HCCP-AA-PFOT, a reactive emulsifier that has both flame-retardant and stain-resistant properties, but also adds DFHMA, which also has good stain-resistant properties. HCCP-AA-PFOT and DFHMA participate in the emulsion polymerization reaction in the form of covalent bonds, further improving the stain resistance of the obtained flame-retardant and stain-resistant modified acrylate emulsion.

[0055] (5) In the process of synthesizing flame-retardant and stain-resistant modified acrylic emulsion, the traditional small molecule emulsifier was not used, which avoids the damage to the paint film performance caused by its migration. The physical and mechanical properties of the final paint film, such as density, water whitening resistance, scrub resistance, and adhesion, are significantly improved. Detailed Implementation

[0056] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0057] The preparation methods of HCCP-AA-PFOT used in Examples 1-3 of this invention are all as follows:

[0058] (1) Under nitrogen protection, 5.00 g HCCP (14.4 mmol) was stirred and dissolved in 100 mL anhydrous tetrahydrofuran (anhydrous THF), and the reaction system was placed in a low temperature bath and cooled to -20 °C;

[0059] (2) Dissolve 4.2 mL of allylamine (55.5 mmol) in 20 mL of anhydrous THF to form an allylamine solution. Add the allylamine solution dropwise to the reaction system in step (1). During the dropwise addition, keep the reaction temperature below -10℃. After the dropwise addition is complete, stir the reaction at -20℃ for 2 hours. After the reaction is complete, remove the ice bath and let the reaction system naturally rise to room temperature. Continue stirring the reaction for 12 hours.

[0060] (3) After the reaction in step (2) is completed, the obtained reaction solution is centrifuged (10000 rpm, 15 min), and the supernatant is collected. The obtained supernatant is then concentrated by rotary evaporation and added dropwise to 100 mL of cold n-hexane (0℃) for precipitation. The white solid precipitate is then collected by centrifugation. The white solid precipitate is then washed three times with cold n-hexane and dried under vacuum to obtain the target intermediate.

[0061] (4) Under nitrogen protection, 1.3 g (about 3 mmol) of the target intermediate was dissolved in 60 mL of anhydrous THF. Then, 4.8 mmol of 2-mercaptoethanol and 50 mg of DMPA were added to the reaction system. After stirring evenly, the mixture was irradiated under UV light (30 °C) for 1.5 h while stirring vigorously. After turning off the UV light, 9.6 mmol of PFOT and 50 mg of DMPA were added. After stirring evenly, the reaction was irradiated under UV light (25 °C) again. The reaction was monitored by TLC (developing solvent: petroleum ether / ethyl acetate = 2:1). The reaction was considered complete when the product spots were stable.

[0062] (5) After the reaction is completed, the reaction solution obtained in step (4) is concentrated to dryness using a rotary evaporator to obtain a viscous crude product. The crude product is then dissolved in 10 mL of THF and added dropwise to 200 mL of ice-cold n-hexane (0℃) while stirring vigorously to obtain a light yellow flocculent solid product. The solid product is collected by centrifugation (8000 rpm, 10 min). The obtained solid product is washed thoroughly with diethyl ether three times to remove unreacted thiols and initiator byproducts. The obtained solid product is then placed in a vacuum drying oven and vacuum dried at 45℃ for 24 h to obtain flame-retardant and stain-resistant HCCP-AA-PFOT. Example

[0063] A high-efficiency flame-retardant and stain-resistant exterior wall coating, comprising the following components by weight:

[0064] 100 parts of flame-retardant and stain-resistant modified acrylic emulsion;

[0065] 30 parts of pigments and fillers;

[0066] 3 parts zinc borate;

[0067] 3.5 parts of auxiliary agent;

[0068] 1.5 parts of film-forming aid;

[0069] 1.5 parts ethylene glycol;

[0070] pH adjuster 0.8 parts;

[0071] 8 parts water.

[0072] The pH adjuster in the above formula is AMP-95, the pigments and fillers are composed of rutile titanium dioxide (0.4μm), heavy calcium carbonate (800 mesh), and kaolin (1250 mesh) in a mass ratio of 18:8:5, the additives are composed of BYK-190, BYK-024, and Dow Chemical ASE™ 60 in a ratio of 0.6:0.3:0.2, and the film-forming aid is Eastman Texanol ester alcohol.

[0073] The preparation method of the flame-retardant and stain-resistant modified acrylic emulsion is as follows:

[0074] Step (1) Preparation of pre-emulsion

[0075] Add 25.0 parts of deionized water, 2.0 parts of HCCP-AA-PFOT, 13 parts of MMA, 54 parts of BA, 2 parts of AA, 1.5 parts of HEMA and 1.5 parts of DFHMA to a beaker in sequence, homogenize and emulsify at high speed to obtain a uniform milky white pre-emulsion, and transfer it to a constant pressure dropping funnel for later use.

[0076] Step (II) Preparation of Seed Liquid

[0077] (1) Under nitrogen protection, add 20.0 parts of deionized water, 3.0 parts of HCCP-AA-PFOT and 0.2 parts of NaHCO3 to a four-necked flask, start stirring (200 rpm) for 30 min, raise the temperature of the reaction system to 80℃ and keep it constant.

[0078] (2) Weigh 0.4 parts of potassium persulfate and dissolve it in 5 parts of deionized water to obtain an initiator solution. Add 1 / 2 of the total weight of the initiator solution to the reaction system in step (1). Stir and observe that the system turns slightly blue and opalescent. Continue stirring at a constant temperature for 20 minutes to obtain the seed liquid.

[0079] Step (3) Emulsion Polymerization

[0080] After the seed reaction in step (II) is completed, under nitrogen protection, the reaction temperature is controlled at 78℃. While stirring, the pre-emulsion obtained in step (I) and the remaining initiator solution are added dropwise. The dropping rate is controlled to ensure that the addition is completed within 2.5 hours. The stirring speed is 250 rpm to ensure uniform mixing and no emulsion breaking. After the addition is completed, the reaction system is kept at 78℃ and stirred for another hour to ensure complete monomer conversion. After the reaction is completed, the reaction system is naturally cooled to 40℃. While stirring, 30% ammonia water is added dropwise to adjust the pH of the emulsion to 7.5. The emulsion is filtered through a 100-mesh sieve, and the flame-retardant and stain-resistant modified acrylate emulsion is obtained.

[0081] The preparation method of the above-mentioned high-efficiency flame-retardant and stain-resistant exterior wall coating, according to the formula dosage, is as follows:

[0082] (1) Pre-dispersion: Add 2 / 3 of the total water volume to the mixing tank, start stirring at low speed (500 rpm), and slowly add wetting and dispersing agent, half of the defoamer, ethylene glycol, pigments and fillers in sequence while stirring at low speed. When adding materials, they should be slowly and evenly sprinkled into the vortex to avoid dust and clumping. After all the powders are added, increase the speed to medium-high speed (1000 rpm) and continue to disperse for 10 minutes until the slurry is initially uniform and there are no obvious dry powder lumps, thus obtaining a pre-dispersioned slurry.

[0083] (2) Grinding: Transfer the pre-dispersed slurry to a sand mill, add an appropriate amount of grinding beads (zirconium beads) for grinding, and use circulating cooling water to control the slurry temperature to not exceed 50℃, and grind to a fineness of 50μm;

[0084] (3) Paint mixing: Pour the flame-retardant and stain-resistant modified acrylic emulsion into the paint mixing tank, turn on the stirrer at medium speed (400 rpm) to form a gentle vortex, and slowly pour the slurry ground in step (2) into the emulsion system (within 10 minutes) to avoid rapid pouring, so as to avoid local flocculation or demulsification.

[0085] (4) Keep stirring at medium speed (400 rpm), slowly add film-forming aids one by one, stir evenly, start adding pH adjuster dropwise, then add zinc borate and stir evenly, then dilute the thickener with the remaining amount of water in the formula, add it to the coating system under low speed (200 rpm) stirring, and finally add the remaining amount of defoamer in the formula, defoam under low speed (200 rpm) stirring for 15 minutes, filter the coating with a 120 mesh screen to remove gel particles or impurities, and obtain a high-efficiency flame-retardant and stain-resistant building exterior wall coating. Example

[0086] A high-efficiency flame-retardant and stain-resistant exterior wall coating, with the following composition by weight:

[0087] 100 parts of flame-retardant and stain-resistant modified acrylic emulsion;

[0088] 35 parts of pigments and fillers;

[0089] 4 parts zinc borate;

[0090] 4.6 parts of additives;

[0091] 2 parts of film-forming aid;

[0092] 2 parts ethylene glycol;

[0093] One part pH adjuster;

[0094] 10 parts water.

[0095] The pH adjuster in the above formula is AMP-95, the pigments and fillers are composed of rutile titanium dioxide (0.3μm), heavy calcium carbonate (1000 mesh), and kaolin (1200 mesh) in a mass ratio of 20:10:6.5, the additives are composed of Tego-755W, Tego-902W, and BASF Rheovis® AS 1130 in a mass ratio of 0.8:0.4:0.3, and the film-forming aid is BASF Loxanol CA5308.

[0096] The preparation method of the flame-retardant and stain-resistant modified acrylic emulsion is as follows:

[0097] Step (1) Preparation of pre-emulsion

[0098] 25.0 parts deionized water, 2.0 parts HCCP-AA-PFOT, 15.0 parts MMA, 55.0 parts BA, 2.0 parts AA, 1.5 parts HEMA and 1.5 parts DFHMA were added to a beaker in sequence and emulsified at high speed (2000 rpm) to obtain a uniform milky white pre-emulsion, which was then transferred to a constant pressure dropping funnel for later use.

[0099] Step (II) Preparation of Seed Liquid

[0100] (1) Under nitrogen protection, add 20.0 parts of deionized water, 3.0 parts of HCCP-AA-PFOT and 0.2 parts of NaHCO3 to a four-necked flask, start stirring (250 rpm) for 30 min, raise the temperature of the reaction system to 78℃ and keep it constant.

[0101] (2) Weigh 0.4 parts of potassium persulfate and dissolve it in 5 parts of deionized water to obtain an initiator solution. Add 1 / 2 of the total weight of the initiator solution to the reaction system in step (1). Stir and observe that the system turns slightly blue and opalescent. Continue stirring at a constant temperature for 20 minutes to obtain the seed liquid.

[0102] Step (3) Emulsion Polymerization

[0103] After the seed reaction in step (II) is completed, under nitrogen protection, the reaction temperature is controlled at 79℃. While stirring, the pre-emulsion obtained in step (I) and the remaining initiator solution are added dropwise to the seed liquid obtained in step (II). The dropping rate is controlled to ensure that the addition is completed within 3 hours. The stirring speed is 250 rpm to ensure uniform mixing and no emulsion breaking. After the addition is completed, the reaction system is kept at 78℃ and stirred for another 1 hour to ensure complete monomer conversion. After the reaction is completed, the reaction system is naturally cooled to 40℃. While stirring, 30% ammonia water is added dropwise to adjust the pH of the emulsion to 8. The emulsion is filtered through a 100-mesh sieve, and the flame-retardant and stain-resistant modified acrylic emulsion is obtained.

[0104] The preparation method of the above-mentioned high-efficiency flame-retardant and stain-resistant exterior wall coating, according to the formula dosage, is as follows:

[0105] (1) Pre-dispersion: Add 2 / 3 of the total water volume to the mixing tank, turn on the stirrer, and stir at low speed (400 rpm). While stirring at low speed, slowly add the wetting and dispersing agent, half of the defoamer, ethylene glycol, and pigments and fillers in sequence. When adding the materials, they should be slowly and evenly sprinkled into the vortex to avoid dust and clumping. After all the powders are added, increase the speed to medium-high speed (1200 rpm) and continue to disperse for 15 minutes until the slurry is initially uniform and there are no obvious dry powder lumps, thus obtaining a pre-dispersed slurry.

[0106] (2) Grinding: Transfer the pre-dispersed slurry to a sand mill, add an appropriate amount of grinding beads (zirconium beads) for grinding, and use circulating cooling water to control the slurry temperature to not exceed 50℃, and grind to a fineness of 50μm;

[0107] (3) Paint mixing: Pour the flame-retardant and stain-resistant modified acrylic emulsion into the paint mixing tank, turn on the stirrer at medium speed (500 rpm) to form a gentle vortex, and slowly pour the slurry ground in step (2) into the emulsion system (within 15 minutes) to avoid rapid pouring to prevent local flocculation or demulsification.

[0108] (4) Keep stirring at medium speed (500 rpm), slowly add film-forming aids one by one, stir evenly, start adding pH adjuster dropwise, then add zinc borate and stir evenly, then dilute the thickener with the remaining amount of water in the formula, add it to the coating system under low speed (300 rpm) stirring, and finally add the remaining amount of defoamer in the formula, defoam under low speed (250 rpm) stirring for 15 minutes, filter the coating with a 120 mesh screen to remove gel particles or impurities, and you will get a high-efficiency flame-retardant and stain-resistant building exterior wall coating. Example

[0109] A high-efficiency flame-retardant and stain-resistant exterior wall coating, with the following composition by weight:

[0110] 100 parts of flame-retardant and stain-resistant modified acrylic emulsion;

[0111] 40 parts of pigments and fillers;

[0112] 5 parts zinc borate;

[0113] 5.5 parts of auxiliary agent;

[0114] 2.5 parts of film-forming aid;

[0115] 2.5 parts ethylene glycol;

[0116] 1.5 parts pH adjuster;

[0117] 12 parts water.

[0118] The pH adjuster in the above formula is AMP-95, the pigments and fillers are composed of rutile titanium dioxide (0.4μm), heavy calcium carbonate (1250 mesh), and kaolin (1250 mesh) in a mass ratio of 22:12:8, the additives are composed of BYK-190, Tego-902W, and Clariant Rheolate® 210 in a ratio of 1:0.5:0.5, and the film-forming aid is Dow Chemical dodecyl alcohol ester.

[0119] The preparation method of the flame-retardant and stain-resistant modified acrylic emulsion is as follows:

[0120] Step (1) Preparation of pre-emulsion

[0121] 25.0 parts deionized water, 2.0 parts HCCP-AA-PFOT, 15.0 parts MMA, 55.0 parts BA, 2.0 parts AA, 1.5 parts HEMA and 1.5 parts DFHMA were added to a beaker in sequence and emulsified at high speed (2000 rpm) to obtain a uniform milky white pre-emulsion, which was then transferred to a constant pressure dropping funnel for later use.

[0122] Step (II) Preparation of Seed Liquid

[0123] (1) Under nitrogen protection, add 20.0 parts of deionized water, 3.0 parts of HCCP-AA-PFOT and 0.2 parts of NaHCO3 to a four-necked flask, start stirring (230 rpm) for 30 min, raise the temperature of the reaction system to 78℃ and keep it constant.

[0124] (2) Weigh 0.4 parts of potassium persulfate and dissolve it in 5 parts of deionized water to obtain an initiator solution. Add 1 / 2 of the total weight of the initiator solution to the reaction system in step (1). Stir and observe that the system turns slightly blue and appears opalescent. Continue to stir at a constant temperature for 18 minutes to obtain the seed liquid.

[0125] Step (3) Emulsion Polymerization

[0126] After the seed reaction in step (II) is completed, under nitrogen protection, the reaction temperature is controlled at 77℃. While stirring, the pre-emulsion obtained in step (I) and the remaining initiator solution are added dropwise. The dropping rate is controlled to ensure that the addition is completed within 3 hours. The stirring speed is 250 rpm to ensure uniform mixing and no emulsion breaking. After the addition is completed, the reaction system is kept at 78℃ and stirred for 1 hour to ensure complete monomer conversion. After the reaction is completed, the reaction system is naturally cooled to 40℃. While stirring, 30% ammonia water is added dropwise to adjust the pH of the emulsion to 8.5. The emulsion is filtered through a 100-mesh sieve, and the flame-retardant and stain-resistant modified acrylate emulsion is obtained.

[0127] The preparation method of the above-mentioned high-efficiency flame-retardant and stain-resistant exterior wall coating, according to the formula dosage, is as follows:

[0128] (1) Pre-dispersion: Add 2 / 3 of the total water volume to the mixing tank, start stirring at low speed (500 rpm), and slowly add wetting and dispersing agent, half of the defoamer, ethylene glycol, pigments and fillers in sequence while stirring at low speed. When adding materials, they should be slowly and evenly sprinkled into the vortex to avoid dust and clumping. After all the powders are added, increase the speed to medium-high speed (1200 rpm) and continue to disperse for 15 minutes until the slurry is initially uniform and there are no obvious dry powder lumps, thus obtaining a pre-dispersioned slurry.

[0129] (2) Grinding: Transfer the pre-dispersed slurry to a sand mill, add an appropriate amount of grinding beads (zirconium beads) for grinding, and use circulating cooling water to control the slurry temperature to not exceed 50℃, and grind to a fineness of 50μm;

[0130] (3) Paint mixing: Pour the flame-retardant and stain-resistant modified acrylic emulsion into the paint mixing tank, turn on the stirrer at medium speed (600 rpm) to form a gentle vortex, and slowly pour the slurry ground in step (2) into the emulsion system (within 15 minutes) to avoid rapid pouring to prevent local flocculation or demulsification.

[0131] (4) Keep stirring at medium speed (600 rpm), slowly add film-forming aids one by one, stir evenly, start adding pH adjuster dropwise, then add zinc borate and stir evenly, then dilute the thickener with the remaining amount of water in the formula, add it to the coating system under low speed (400 rpm) stirring, and finally add the remaining amount of defoamer in the formula, defoam under low speed (300 rpm) stirring for 15 minutes, filter the coating with a 120 mesh screen to remove gel particles or impurities, and obtain a high-efficiency flame-retardant and stain-resistant building exterior wall coating.

[0132] Comparative Example 1 is the same as Example 1, except that the same amount of commercially available BASF Acronal 7590 was added to replace the flame-retardant and stain-resistant modified acrylic emulsion in Example 1.

[0133] Comparative Example 2 is the same as Example 1, except that in the process of synthesizing HCCP-AA-PFOT, PFOT was replaced with pentafluoropentanethiol (CAS: 148757-88-4) in the same molar amount.

[0134] Comparative Example 3 is the same as Example 1, except that in the process of synthesizing HCCP-AA-PFOT, the amount of 2-mercaptoethanol added was changed to 6 mmol and the amount of PFOT added was changed to 8.4 mmol.

[0135] Comparative Example 4 is the same as Example 1, except that the exterior wall coating obtained in Comparative Example 4 did not contain the synergistic flame retardant zinc borate.

[0136] Comparative Example 5 is the same as Example 1, except that DFHMA was not added in the process of synthesizing the flame-retardant and stain-resistant modified acrylate emulsion in Comparative Example 5, and the amount of HCCP-AA-PFOT added in the pre-emulsion was changed to 3.5 parts.

[0137] Comparative Example 6 is the same as Example 1, except that in the process of synthesizing HCCP-AA-PFOT, the amount of 2-mercaptoethanol added was changed to 4 mmol and the amount of PFOT added was changed to 10.4 mmol.

[0138] Performance testing

[0139] Standard samples of the building exterior wall coatings obtained in the above embodiments and comparative examples were prepared and, after curing under standard conditions, the following performance tests were conducted:

[0140] Flame retardancy: Test standard: GB / T 12441-2018 "Fire-retardant Coatings for Finishing" or comparison using the small chamber method and limiting oxygen index (LOI) method. For rapid screening, the alcohol torch burning method is commonly used: the coating is evenly applied to an oak board of a specific size, and after drying, the sample surface is burned with an alcohol torch at a 45° angle for a certain period of time (e.g., 30s). After removing the flame source, the afterflame extinguishing time (s), char length (mm), and whether dripping occurred are recorded.

[0141] Evaluation criteria: The shorter the charring length and the shorter the afterflame time, the better the flame retardant performance.

[0142] Stain resistance: Test standard: GB / T 9780-2013 "Test method for stain resistance of architectural coatings".

[0143] Evaluation index: The dry surface of the coating was contaminated with fly ash suspension, rinsed and dried, and the reflectance loss rate was measured using a reflectometer. The smaller the reflectance loss rate, the better the anti-fouling performance.

[0144] Water resistance: Test standard: GB / T 1733-1993 "Determination of water resistance of paint film". Immerse the sample in deionized water and observe after 96 hours.

[0145] Evaluation criteria: Observe whether the paint film shows signs of blistering, whitening, peeling, etc. No abnormalities are considered optimal.

[0146] Adhesion: Test standard: GB / T 9286-1998 "Cross-cut test for paint and varnish film".

[0147] Evaluation criteria: The method of tearing tape (1mm spacing) is used to evaluate the results on a scale of 0-5. Grade 0 (no peeling) is the best.

[0148] Scratch resistance: Test standard: GB / T 9279-2007 "Scratch test for paints and varnishes". Use a scratch resistance tester or hardness tester (such as pencil hardness tester).

[0149] Evaluation criteria: Pencil hardness (H~9H), the higher the hardness, the better the scratch resistance. Or record the minimum weight (g) required to scratch the paint film.

[0150] The specific test results are shown in Tables 1 and 2:

[0151] Table 1

[0152] ,

[0153] Table 2

[0154] ,

[0155] Based on the test data above, it is clear that, compared to Comparative Example 1, Examples 1-3 exhibit significantly superior flame retardancy, stain resistance, and adhesion. Comparative Example 1 uses a common water-based acrylic emulsion, which is completely non-flame retardant, decomposes rapidly during combustion, and has a long char length. Its stain resistance relies on a small amount of additives added later, resulting in poor performance and easy runoff. In Examples 1-3, the flame-retardant and stain-resistant modified acrylic emulsions firmly integrate phosphorus-nitrogen flame-retardant structures and fluorocarbon stain-resistant structures into the polymer network through chemical bonds, achieving durable intrinsic flame retardancy and stain resistance. Simultaneously, the use of reactive emulsifiers avoids the damage to water resistance and adhesion caused by the migration of small molecule emulsifiers.

[0156] Compared with Comparative Example 2, the stain resistance of Comparative Example 2 was significantly reduced because the carbon chain of pentafluoropentanethiol was too short, making it difficult to form a sufficiently dense and low surface energy arrangement on the paint film surface, resulting in a decrease in stain resistance.

[0157] Compared to Comparative Example 3, Example 1 showed a significant decrease in both flame retardancy and stain resistance. Comparative Example 3 altered the ratio of hydrophilic hydroxyl groups to hydrophobic fluorocarbon chains in the HCCP-AA-PFOT molecule. The excess of 2-mercaptoethanol resulted in an excessively large proportion of the hydrophilic portion in the molecule, reducing the allyl double bonds available for the second reaction step and leading to insufficient perfluorooctyl (PFOT) groups introduced into the final product. This directly resulted in decreased stain resistance. Furthermore, the altered molecular structure may have affected its self-assembly behavior during emulsion polymerization and its final distribution in the coating film, thereby weakening the synergistic effect of flame retardancy.

[0158] Compared to Comparative Example 4, Example 1 showed significantly worse flame retardancy, indicating a significant synergistic effect between zinc borate and the phosphorus-nitrogen flame retardant system. During combustion, zinc borate reacts with phosphoric acid compounds produced by the decomposition of HCCP-AA-PFOT, generating a denser and stronger glassy boron-phosphorus-carbon composite char layer. This char layer more effectively isolates oxygen and heat, preventing the escape of combustible gases, thus greatly improving flame retardant efficiency. Without zinc borate, relying solely on the phosphorus-nitrogen system results in insufficient char yield and char layer quality.

[0159] Compared to Comparative Example 5, Example 1 showed decreased antifouling properties. Comparative Example 6, relying solely on PFOT from HCCP-AA-PFOT, may not have had sufficient total fluorine content and distribution density in the coating film to form the optimal low surface energy layer. With the addition of DFHMA, more fluorinated segments enter the polymer backbone through copolymerization and migrate to the surface in tandem with PFOT segments during film formation, further reducing surface energy and enhancing the redundancy and reliability of the antifouling effect.

[0160] Compared with Comparative Example 6, Example 1 reduced the number of hydrophilic groups (-OH) and increased the number of hydrophobic groups (-C8F). 17 The alteration of the molecular structure of "HCCP-AA-PFOT" significantly reduced its hydrophilic-lipophilic balance (HLB), impairing its function as an emulsifier and causing problems in the emulsion polymerization process and film quality. Although the goal of improving stain resistance was achieved, the change in molecular structure affected its self-assembly behavior in emulsion polymerization and its distribution in the paint film, weakening its flame-retardant synergistic effect.

[0161] 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 inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A high efficiency fire retardant stain resistant architectural exterior wall coating, characterized in that, It comprises the following components by weight: 100 parts of flame-retardant and stain-resistant modified acrylic emulsion; 30-40 parts of pigments and fillers; 3-5 parts zinc borate; 3.5-5.5 parts of auxiliary agent; Film-forming aid 1.5-2.5 parts; pH adjuster 0.8-1.5 parts; 8-12 parts deionized water; The flame-retardant and stain-resistant modified acrylic emulsion is obtained through seed emulsion polymerization and mainly comprises the following raw material components by weight: 45-55 parts deionized water; HCCP-AA-PFOT 3-8 portions; NaHCO3 0.1-0.3 parts; MMA 12-15 portions; BA 52-55 copies; AA 1-2 portions; HEMA 1-1.5 parts; DFHMA 1-1.5 parts; Initiator 0.3-0.5 parts; The preparation method of the HCCP-AA-PFOT includes the following steps: (1) The amino group of allylamine undergoes a nucleophilic substitution reaction with the chlorine atom in HCCP to obtain double bond modified cyclotriphosphonium. The molar ratio of allylamine to hexachlorocyclotriphosphonium is 3:1 to 4:

1. (2) The double bond modified cyclotriphosphonium undergoes a mercapto-alkene click reaction with 2-mercaptoethanol. The double bond modified cyclotriphosphonium reacts with 2-mercaptoethanol to obtain modified cyclotriphosphonium compound I. The molar ratio of the double bond modified cyclotriphosphonium to 2-mercaptoethanol is 1:1.5~1:1.

8. (3) Modified cyclotriphosphonon compound I reacts with excess 1H,1H,2H,2H-perfluorooctyl mercaptan to undergo a mercapto-alkene click reaction to obtain HCCP-AA-PFOT; The preparation method of the flame-retardant and stain-resistant modified acrylic emulsion is as follows: Step (1) Preparation of pre-emulsion Add 25.0 parts of deionized water, 2.0 parts of HCCP-AA-PFOT, 15.0 parts of MMA, 55.0 parts of BA, 2.0 parts of AA, 1.5 parts of HEMA and 1.5 parts of DFHMA to a beaker in sequence, homogenize and emulsify at high speed to obtain a uniform milky white pre-emulsion, and transfer it to a constant pressure dropping funnel for later use. Step (II) Preparation of Seed Liquid (1) Under nitrogen protection, add 20.0 parts of deionized water, 3.0 parts of HCCP-AA-PFOT and 0.2 parts of NaHCO3 to a four-necked flask, stir for 20-30 min, raise the temperature of the reaction system to 78-80℃ and keep it constant. (2) Weigh 0.4 parts of potassium persulfate and dissolve it in 5 parts of deionized water to obtain an initiator solution. Add 1 / 2 of the total amount of the initiator solution to the reaction system in step (1). Stir and observe that the system turns slightly blue and becomes opalescent. Continue to stir at a constant temperature for at least 15 minutes to obtain the seed liquid. Step (3) Emulsion Polymerization After the seed reaction in step (II) is completed, under nitrogen protection, the reaction temperature is controlled at 78±1℃. The pre-emulsion obtained in step (I) and the remaining initiator solution are added dropwise to the seed liquid obtained in step (II) while stirring, ensuring that the addition is completed within 2.5~3h. The stirring speed is 200-250rpm. After the addition is completed, the reaction system is kept at 78℃ and stirred for 1h. After the reaction is completed, the reaction system is naturally cooled to below 40℃. The pH of the emulsion is adjusted to 7.5~8.5 by stirring. The emulsion is filtered through a sieve, and the flame-retardant and stain-resistant modified acrylic emulsion is obtained.

2. The high-efficiency flame-retardant and stain-resistant exterior wall coating according to claim 1, characterized in that, The pH adjuster is AMP-95 or ammonia.

3. The high-efficiency flame-retardant and stain-resistant exterior wall coating according to claim 1, characterized in that, The pigments and fillers include one or more of rutile titanium dioxide, heavy calcium carbonate, and kaolin.

4. The high-efficiency flame-retardant and stain-resistant exterior wall coating according to claim 1, characterized in that, The additives, by weight, include at least 0.6-1 parts wetting and dispersing agent, 0.3-0.5 parts defoamer, and 0.2-0.6 parts thickener.

5. The high efficiency fire-retardant stain resistant exterior architectural coating according to claim 4, wherein, The defoamer is a mineral oil-based defoamer or an organosilicon-based defoamer.

6. A high efficiency fire retardant stain resistant exterior architectural coating according to claim 4, wherein, The thickener is an alkali-swellable thickener.

7. The high efficiency fire-retardant stain resistant exterior architectural coating according to claim 1, wherein The film-forming aids include one or more of Eastman Texanol ester alcohol, BASF Loxanol CA5308, and Dow Chemical dodecyl alcohol ester.