Waterborne Acrylate Fireproof Coating and Its Preparation Method

Abstract

The present invention relates to the field of fireproof coatings, and specifically discloses a waterborne acrylate fireproof coating and a preparation method thereof. Specifically, the waterborne acrylate fireproof coating comprises the following components in parts by weight: 20-30 parts of montmorillonite-modified acrylate emulsion, 20-30 parts of ammonium polyphosphate, 3-8 parts of pentaerythritol, 10-20 parts of slow-combustion-modified dextrin oligomer, 10-20 parts of melamine, 3-5 parts of titanium dioxide, 0.3-1 part of hydroxyethyl cellulose, 0.5-1 part of dispersant, 0.5-1 part of defoamer, 0-2 parts of mildew preventive, 0.5-1 part of n-octanol, and 3-20 parts of water. The slow-combustion-modified dextrin oligomer refers to a substance obtained by grafting inorganic nanoparticles on the surface of pregelatinized starch. The waterborne acrylate fireproof coating of the present invention has better fireproof performance and mildew-proof performance, and lower cost.

Description

Technical Field

[0001] The present invention relates to the field of fire - retardant coatings, and particularly to an aqueous acrylate fire - retardant coating and a preparation method thereof. Background Art

[0002] Fire - retardant coatings are a special functional coating, which can slow down the spread rate of flames or isolate the fire source within a certain time, so that the base material does not catch fire within a certain time. At present, fire - retardant coatings are generally divided into intumescent fire - retardant coatings and non - intumescent coatings. Intumescent coatings mainly consist of film - forming substances, char - forming agents, foaming agents, etc. When heated, the coating can often carbonize and expand dozens or even hundreds of times, forming a porous carbon layer similar to honeycomb or sponge. This carbon layer has good heat - insulation effect, and at the same time blocks the contact between oxygen and the protected base material, playing a role in fire prevention and flame retardancy. During the process of carbonization and foaming, such as dehydration carbonization and thermal decomposition of each component of the coating, also consume a certain amount of heat, which is beneficial to reducing the system temperature. At the same time, when the intumescent fire - retardant coating is heated, it can also release non - combustible gases such as ammonia, water vapor, nitrogen, and carbon dioxide, reducing the concentration of combustible gases and oxygen near the protected base material, playing a role in flame retardancy. Compared with inorganic flame retardants, this kind of intumescent coating can effectively reduce the negative impact on the mechanical properties of the matrix material due to the addition of flame retardants, so it can be widely used in the fields of construction, high - speed rail, aircraft, ships, electrical appliances, etc.

[0003] Existing intumescent fire - retardant coatings generally use ammonium polyphosphate, pentaerythritol (or dipentaerythritol), and melamine as a combined flame - retardant system. Among them, ammonium polyphosphate decomposes when heated to produce phosphoric acid, which in turn promotes the dehydration decomposition of pentaerythritol, promotes the carbonization of pentaerythritol at high temperature, and expands to form a microporous foam carbonized layer under the action of the gases released by the decomposition of melamine and ammonium polyphosphate. Therefore, the dosage of ammonium polyphosphate and pentaerythritol / dipentaerythritol is relatively large in the common fire - retardant coating system, which leads to high production costs of general fire - retardant coatings. Moreover, pentaerythritol belongs to an explosive - precursor hazardous chemical, and its production control requirements are relatively high.

[0004] In response to the above problems, Patent CN104530890B proposed an aqueous acrylate fire - retardant coating, which uses starch to replace part of the pentaerythritol. However, the decomposition temperature of starch is relatively low and it is easy to burn out quickly, resulting in poor fire - prevention performance of this fire - retardant coating, and the fire - resistance limit is only below 85 min.

[0005] In some other technical solutions, by introducing different types of inorganic fillers, such as introducing nano - titanium dioxide, hollow glass microspheres, etc., the flame - retardant performance is improved. However, these inorganic fillers will affect the performance of the coating film on the one hand, and on the other hand, there is also the problem of high price. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an aqueous acrylate fireproof coating with excellent fire resistance.

[0007] To solve the above technical problem, the present invention provides an aqueous acrylate fireproof coating, comprising the following components in parts by weight:

[0008] Montmorillonite-modified acrylate emulsion 20 - 30 parts, ammonium polyphosphate 20 - 30 parts, pentaerythritol 3 - 8 parts, slow-burning modified dextrin oligomer 10 - 20 parts, melamine 10 - 20 parts, titanium dioxide 3 - 5 parts, hydroxyethyl cellulose 0.3 - 1 part, dispersant 0.5 - 1 part, defoamer 0.5 - 1 part, mildew-proof agent 0 - 2 parts, n-octanol 0.5 - 1 part, water 3 - 20 parts.

[0009] Among them, the slow-burning modified dextrin oligomer refers to the substance obtained by grafting inorganic nanoparticles on the surface of pregelatinized starch. It should be noted that during the heating process of pure starch, below 250 °C, it is basically the restructuring of starch structure and the decomposition of glycosidic bonds, and basically no gas is generated (except for the evaporation of part of the free water). In the range of 250 °C - 360 °C, the decomposition products of starch will burn and carbonize violently to form coke. In the range of 360 - 600 °C, the coke produced by the combustion of starch will decompose and burn out to form carbon dioxide. The decomposition of ammonium polyphosphate generally occurs in the range of 300 - 800 °C, especially in the range of 300 - 500 °C, with more gas generated; the main decomposition of melamine also occurs in the range of 300 - 370 °C. And the coke produced by the carbonization of starch starts to decompose and burn out above 400 °C, which means that the gas released by the combustion of ammonium polyphosphate and melamine is difficult to effectively expand the carbonized layer to form a thick and highly uniform microporous foam carbonized layer. Therefore, in the present invention, the starch is pretreated. First, the high molecular weight starch (with a molecular weight of 10 6 or more) is pregelatinized and decomposed to form low molecular weight oligomers (with a molecular weight of 10 4 or less), and inorganic nanoparticles are partially grafted on its surface. The pre-decomposed oligomers have a small molecular weight and can undergo combustion and carbonization at a lower temperature (200 - 350 °C), releasing CO2 and playing a flame retardant role. After combustion and carbonization, they are tightly combined with inorganic nanoparticles, which effectively hinders their premature complete combustion and decomposition at a high temperature stage (> 350 °C), that is, the carbonized layer is retained, and then, combined with the gas generated by melamine, ammonium polyphosphate, and pentaerythritol, a thick and highly uniform foam carbonized layer is formed, effectively improving the fireproof performance. In addition, in the range of 300 - 500 °C, pentaerythritol will also thermally decompose and carbonize to form a carbonized layer, further increasing the thickness of the foam carbonized layer and improving the fireproof performance. In addition, through the treatment with the inorganic nanoparticles of the present invention, the problem of mildew of the fireproof coating caused by starch mildew can be effectively prevented, and thus the usage amount of the mildew-proof agent can be effectively reduced.

[0010] Specifically, the grafted inorganic nanoparticles can be selected from nano-silica, nano-alumina, nano-barium sulfate, but not limited thereto.

[0011] Preferably, in some embodiments of the present invention, the preparation method of the slow-burning modified dextrin oligomer comprises the following steps:

[0012] (1) Mix starch with water at 10 - 30 °C to obtain a mixed solution; treat the mixed solution with high-pressure steam at a temperature of 100 - 200 °C for 10 - 20 s, and then dry to obtain a dextrin intermediate; the weight ratio of starch to water is 1:3 - 5, and the molecular weight of the dextrin intermediate is 3000 - 8000;

[0013] (2) Mix and treat the dextrin intermediate with nano-alumina, ethoxysilane, and a dispersant in a weight ratio of 1:0.05 - 0.5:0.05 - 0.5:0.3 - 1 for 20 - 30 min, and perform solid-liquid separation to obtain the slow-burning modified dextrin oligomer.

[0014] Through the process of first mixing starch with water at 10 - 30 °C and then treating it with high-pressure steam at 100 - 200 °C, the starch can be decomposed into a dextrin intermediate with a molecular weight of 3000 - 8000 relatively quickly. This dextrin intermediate is not only easy to combine with inorganic nanoparticles but also enables it to burn and carbonize at a lower temperature, achieving the function of fully utilizing the foaming of melamine gas.

[0015] After the high-pressure steam treatment process, by mixing and treating inorganic nanoparticles, ethoxysilane, and a dispersant, the slow-burning modified dextrin oligomer can be obtained. Among them, ethoxysilane helps to improve the compatibility between inorganic nanoparticles and the dextrin intermediate to form stable C-O-Si bonds. Moreover, it can make the inorganic nanoparticles highly hydrophobic, consume the hydroxyl groups on the surface of the dextrin intermediate, prevent it from spontaneously forming a large number of hydrogen bonds during subsequent applications, and prevent it from crystallizing and polymerizing into a high-molecular-weight, starch-like polymer, thus preventing the weakening of its mildew-proof and fire-proof properties. Preferably, nano-alumina is selected as the inorganic nanoparticle, which not only has stronger fire resistance and can increase the burnout temperature. Moreover, it can more effectively prevent the slow-burning modified dextrin oligomer in the coating from spontaneously reforming hydrogen bonds during use and forming a polymer with a higher molecular weight.

[0016] Preferably, in some embodiments, in step (1), the dextrin intermediate is obtained by spray drying the mixed solution after high-pressure steam treatment. The dextrin intermediate obtained by spray drying presents a good spherical shape, is more evenly distributed in the fireproof coating, and improves the fireproof performance.

[0017] Preferably, in some embodiments, in step (2), the dextrin intermediate, nano-aluminum oxide, ethoxysilane, and dispersant are mixed and treated under ultrasonic action with a frequency of 30-50 kHz for 20-30 min, and then solid-liquid separation is carried out to obtain the slow-burning modified dextrin oligomer. Through ultrasonic treatment, the arrangement of the dextrin intermediate can be made more orderly, so that the inorganic nanoparticles can be more evenly combined on the surface of the dextrin intermediate, further improving the fireproof performance and at the same time improving the mildew-proof performance, so that the fireproof coating does not need to use a mildew-proof agent.

[0018] Specifically, in step (2), the dispersant is selected from one or more of ethanol, propanol, acetone, and glycerol, but is not limited thereto. Preferably, in one embodiment, the dispersant is selected as acetone.

[0019] Specifically, in step (2), the ethoxysilane is selected from γ-aminopropyltriethoxysilane and / or γ-methacryloxypropyltrimethoxysilane, but is not limited thereto. Preferably, in one example, the ethoxysilane is selected as γ-aminopropyltriethoxysilane.

[0020] Specifically, in step (2), the starch is selected from potato starch and / or wheat starch, but is not limited thereto.

[0021] Specifically, in step (2), the particle size of the inorganic nanoparticles is 30-100 nm. When its particle size > 100 nm, it will combine with the dextrin intermediate to form a net-like structure, which will increase the decomposition and carbonization temperature of the slow-burning modified dextrin oligomer and make it difficult to effectively cooperate with other substances to foam. When the particle size of the inorganic nanoparticles is less than 30 nm, it is difficult to be evenly dispersed and loaded on the dextrin intermediate. Preferably, in one example, the particle size of the nano-aluminum oxide is 30 nm-50 nm.

[0022] Preferably, in one example, the weight ratio of the nano-aluminum oxide, ethoxysilane, and dispersant is 1:0.05-0.1:0.08-0.12:0.4-0.7.

[0023] Specifically, in the present invention, the montmorillonite-modified acrylate emulsion is an acrylate emulsion modified by organic montmorillonite, which can form a protective layer on the surface of the coating film, thereby preventing the coating from cracking and improving the mechanical properties, thermal stability and waterproof properties of the coating. Specifically, the montmorillonite-modified acrylate emulsion is made from the following raw materials in parts by weight:

[0024] n-butyl acrylate 10-20 parts, methyl methacrylate 5-20 parts, methacrylic acid 1-3 parts, organic montmorillonite 0.2-2 parts, emulsifier 0.5-2 parts, buffer 0.01-0.2 parts, initiator 0.05-0.15 parts, water 18-40 parts;

[0025] Among them, the organic montmorillonite is prepared by modifying sodium-based montmorillonite with surfactant CTAB, and the mass ratio of the surfactant CTAB to sodium-based montmorillonite is (1-2):1;

[0026] The emulsifier is selected from sodium dodecyl sulfate and polyethylene glycol octyl phenyl ether, and the weight ratio of sodium dodecyl sulfate to polyethylene glycol octyl phenyl ether is 1-2:1;

[0027] The initiator is selected from potassium persulfate and / or ammonium persulfate;

[0028] The buffer is selected from sodium bicarbonate and / or potassium bicarbonate.

[0029] The preparation method of the montmorillonite-modified acrylate emulsion includes the following steps:

[0030] (1) Mix 8-15 parts of n-butyl acrylate, 1-4 parts of methacrylate, 0.1-0.5 part of organic montmorillonite, 6-15 parts of water, and 0.05-0.12 part of emulsifier, and emulsify to obtain the first emulsion;

[0031] (2) Mix 1-6 parts of n-butyl acrylate, 5-12 parts of methacrylate, 1-3 parts of methacrylic acid, 0.1-0.5 part of organic montmorillonite, 6-15 parts of water, and 0.05-0.12 part of emulsifier, and emulsify to obtain the second emulsion;

[0032] (3) Mix 0.01-0.2 part of buffer, 6-15 parts of water, and 0.05-0.12 part of emulsifier evenly to obtain a buffer solution, and mix 0.05-0.15 part of initiator and 3-10 parts of water evenly to obtain an initiator solution;

[0033] (4) Mix 40-60 vol% of the first emulsion and the buffer solution, and dropwise add 20-50 vol% of the initiator solution of the total amount of the initiator solution, and react at 65°C-80°C for 20-40 min to obtain a seed emulsion;

[0034] (5) Dropwise add the remaining first emulsion and 20-50 vol% of the initiator solution of the total amount of the initiator solution to the seed emulsion, and react at 70°C-90°C for 20-40 min after dropping to obtain a core emulsion;

[0035] (6) Dropwise add the remaining initiator solution and the second emulsion to the core emulsion, and react at 80-90°C for 20-40 min after dropping, cool, and filter to obtain.

[0036] Correspondingly, the present invention also discloses a preparation method of a waterborne acrylate fireproof coating for preparing the above-mentioned waterborne acrylate fireproof coating, which includes the following steps:

[0037] (1) Mix pentaerythritol, melamine, slow-burning modified dextrin oligomer, titanium dioxide and water evenly.

[0038] (2) Add hydroxyethyl cellulose, defoamer, dispersant and mildew preventive, and mix evenly.

[0039] (3) Add ammonium polyphosphate, montmorillonite-modified acrylate emulsion and n-octanol, and mix evenly to obtain the product.

[0040] Implementing the present invention has the following beneficial effects:

[0041] The waterborne acrylate fireproof coating of the present invention partially replaces the charring agent pentaerythritol with slow-burning modified dextrin oligomer, reducing the production cost. Moreover, the slow-burning modified dextrin oligomer has better fireproof performance and mildew prevention performance than ordinary starch. Specific embodiments

[0042] To make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments.

[0043] Example 1

[0044] This example provides a waterborne acrylate fireproof coating, and its formula is as follows:

[0045] 25 parts of montmorillonite-modified acrylate emulsion, 24 parts of ammonium polyphosphate, 4 parts of pentaerythritol, 15 parts of slow-burning modified dextrin oligomer, 16 parts of melamine, 4 parts of titanium dioxide, 0.9 part of hydroxyethyl cellulose, 0.8 part of dispersant (5040), 0.8 part of defoamer (470), 0.5 part of mildew preventive (DE), 0.8 part of n-octanol, 8.2 parts of water;

[0046] Among them, the preparation method of the slow-burning modified dextrin oligomer is:

[0047] 1) Mix 10 parts of potato starch and 40 parts of water, heat up to 80 °C, and maintain for 30 min; filter and spin dry to obtain pregelatinized starch.

[0048] 2) Mix the pregelatinized starch, γ-methacryloyloxypropyltrimethoxysilane, nano-SiO2 (particle size of 50 - 90 nm), and glycerol in a ratio of 1:0.5:0.1:0.8, stir and mix at 300 rpm for 30 min, and perform solid-liquid separation to obtain the product.

[0049] Among them, the formula of the montmorillonite-modified acrylate emulsion is:

[0050] 12 parts of n-butyl acrylate, 8 parts of methyl methacrylate, 1.2 parts of methacrylic acid, 0.4 part of organic montmorillonite, 0.3 part of polyethylene glycol octyl phenyl ether, 0.6 part of sodium dodecyl sulfate, 0.08 part of buffer (potassium bicarbonate), 0.1 part of initiator (potassium persulfate), 24 parts of water.

[0051] The preparation method of the montmorillonite-modified acrylate emulsion is as follows:

[0052] (1) Mix 10 parts of n-butyl acrylate, 2 parts of methyl methacrylate, 0.2 part of organic montmorillonite, 0.1 part of polyethylene glycol octyl phenyl ether, 0.2 part of sodium dodecyl sulfate and 6 parts of deionized water, and stir well to emulsify to obtain the first emulsion;

[0053] (2) Mix 2 parts of n-butyl acrylate, 6 parts of methyl methacrylate, 1.2 parts of methacrylic acid, 0.2 part of organic montmorillonite, 0.1 part of polyethylene glycol octyl phenyl ether, 0.2 part of sodium dodecyl sulfate and 6 parts of deionized water, and stir well to emulsify to obtain the second emulsion;

[0054] (3) Mix 0.08 part of potassium bicarbonate, 0.1 part of polyethylene glycol octyl phenyl ether, 0.2 part of sodium dodecyl sulfate and 6 parts of deionized water evenly to obtain a buffer solution; dissolve 0.1 part of potassium persulfate in 6 parts of deionized water to obtain an initiator solution;

[0055] (4) Add 30 vol% of the initiator solution of the total amount of the buffer solution and the initiator solution and 50 vol% of the first emulsion of the total amount of the first emulsion to a four-necked flask, heat up to 70 °C, and keep warm for 30 min when blue light appears in the emulsion to obtain a seed emulsion;

[0056] (5) Dropwise add the remaining first emulsion and 30 vol% of the initiator solution of the total amount of the initiator solution to the seed emulsion, finish dropping within 1 h, heat up to 80 °C, and keep warm for 30 min to obtain a core emulsion;

[0057] (6) Dropwise add the remaining initiator solution and the second emulsion to the core emulsion, react at 85 °C for 30 min after dropping, cool naturally to 40 °C, pass through a 200-mesh sieve, and adjust the pH of the system to 8 to obtain the montmorillonite-modified acrylate emulsion.

[0058] Among them, the preparation steps of the organic montmorillonite are as follows: Disperse 10 parts of sodium-based montmorillonite in 200 parts of deionized water, and stir well to make it evenly dispersed. Then take 20 parts of surfactant CTAB and dissolve it in 100 parts of deionized water, and slowly drop it into the sodium-based montmorillonite suspension. After dropping, ultrasonically disperse the mixture at 80 °C for 3 h, take out the mixture, balance it at room temperature for 3 h, filter by suction, wash it with secondary distilled water, and then wash it with deionized water until there is no Br -(It was detected with a dilute AgNO3 solution. The product obtained by suction filtration was dried under an infrared lamp, then ground and passed through a 200-mesh sieve to obtain the organic montmorillonite.

[0059] In this example, the preparation method of the waterborne acrylate fireproof coating is as follows:

[0060] (i) Pentaerythritol, melamine, charring retardant modified dextrin oligomer, titanium dioxide and water were mixed evenly;

[0061] (ii) Hydroxyethyl cellulose, defoamer, dispersant and mildew preventive were added and mixed evenly;

[0062] (iii) Ammonium polyphosphate, montmorillonite modified acrylate emulsion and n-octanol were added and mixed evenly to obtain the product.

[0063] Example 2

[0064] This example provides a waterborne acrylate fireproof coating, which is different from Example 1 in that:

[0065] The preparation method of the charring retardant modified dextrin is as follows:

[0066] Among them, the preparation method of the charring retardant modified dextrin oligomer is as follows:

[0067] 1) 10 parts of potato starch and 40 parts of water were mixed at 20 °C, then treated with high-pressure steam at 150 °C for 20 s and spray-dried to obtain a dextrin intermediate;

[0068] 2) The dextrin intermediate was mixed with nano-aluminum oxide (particle size 30 nm - 50 nm), γ-aminopropyltriethoxysilane, and dispersant (acetone) in a weight ratio of 1:0.08:0.09:0.6, stirred and mixed at 300 rpm for 20 - 30 min, and solid-liquid separation was carried out to obtain the charring retardant modified dextrin oligomer.

[0069] The rest are the same as in Example 1.

[0070] Example 3

[0071] This example provides a waterborne acrylate fireproof coating, and its formula is as follows:

[0072] 25 parts of montmorillonite modified acrylate emulsion, 24 parts of ammonium polyphosphate, 4 parts of pentaerythritol, 15.5 parts of charring retardant modified dextrin oligomer, 16 parts of melamine, 4 parts of titanium dioxide, 0.9 part of hydroxyethyl cellulose, 0.8 part of dispersant (5040), 0.8 part of defoamer (470), 0.8 part of n-octanol, 8.2 parts of water;

[0073] Among them, the preparation method of the charring retardant modified dextrin oligomer is as follows:

[0074] 1) Mix 10 parts of potato starch and 40 parts of water at 20°C, then treat with high-pressure steam at 150°C for 20 s, and spray dry to obtain a dextrin intermediate product.

[0075] 2) Mix the dextrin intermediate product with nano-aluminum oxide (particle size 30 nm - 50 nm), γ-aminopropyltriethoxysilane, and a dispersant (acetone) in a weight ratio of 1:0.08:0.09:0.6, and treat with ultrasound at a frequency of 45 kHz for 25 min, then perform solid-liquid separation to obtain the slow-burning modified dextrin oligomer.

[0076] Among them, the formulation and preparation method of the montmorillonite-modified acrylate emulsion are the same as those in Example 1.

[0077] The preparation method of the waterborne acrylate fireproof coating in this example is as follows:

[0078] (i) Mix pentaerythritol, melamine, the slow-burning modified dextrin oligomer, titanium dioxide, and water evenly.

[0079] (ii) Add hydroxyethyl cellulose, defoamer, and dispersant, and mix evenly.

[0080] (iii) Add ammonium polyphosphate, montmorillonite-modified acrylate emulsion, and n-octanol, and mix evenly to obtain the product.

[0081] Comparative Example 1

[0082] This comparative example provides a waterborne acrylate fireproof coating, and its formulation is as follows:

[0083] 24 parts of montmorillonite-modified acrylate emulsion, 32 parts of ammonium polyphosphate, 5 parts of pentaerythritol, 10 parts of potato starch, 14 parts of melamine, 5 parts of titanium dioxide, 1 part of hydroxyethyl cellulose, 1 part of dispersant (5040), 1 part of defoamer (470), 2 parts of mildew preventive (DE), 1 part of n-octanol, 4 parts of water;

[0084] Among them, the formulation and preparation method of the montmorillonite-modified acrylate emulsion are the same as those in Example 1.

[0085] The preparation method of the waterborne acrylate fireproof coating in this comparative example is as follows:

[0086] (i) Mix pentaerythritol, melamine, potato starch, titanium dioxide, and water evenly.

[0087] (ii) Add hydroxyethyl cellulose, defoamer, dispersant, and mildew preventive, and mix evenly.

[0088] (iii) Add ammonium polyphosphate, montmorillonite-modified acrylate emulsion, and n-octanol, and mix evenly to obtain the product.

[0089] Comparative Example 2

[0090] This comparative example provides an aqueous acrylate fireproof coating, and its formula is as follows:

[0091] Unsaturated polyester: 25 parts, styrene: 0.5 part, olefin solution: 0.25 part, E51 epoxy resin: 6.25 parts, methyl ethyl ketone peroxide: 0.50 part, solvent: 2.66 parts, cobalt naphthenate: 0.04 part, triethylenetetramine: 0.8 part, ammonium polyphosphate: 28 parts, melamine: 17.5 parts, pentaerythritol: 10.50 parts, titanium dioxide: 8 parts.

[0092] The preparation method of the aqueous acrylate fireproof coating in this comparative example is as follows:

[0093] Mix the polyester resin, styrene, methyl ethyl ketone peroxide, cobalt naphthenate, and olefin solution to obtain the first mixed solution;

[0094] Mix the epoxy resin and triethylenetetramine to obtain the second mixed solution;

[0095] Mix the ammonium polyphosphate, pentaerythritol, melamine, and titanium dioxide mask evenly, then add the solvent and mix evenly to obtain the third mixed solution;

[0096] Mix the first mixed solution, the second mixed solution, and the third mixed solution evenly to obtain the product.

[0097] Measure the fireproof coatings obtained in Examples 1 to 3 and Comparative Examples 1 to 2 according to the relevant methods of "Decorative Fireproof Coating" (GB / T 12441-2018) and "Method for Determining Mildew Resistance of Paint Films" (GB / T 1741-2020). The specific results are as follows:

[0098]

[0099] The above is the preferred implementation mode of the invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A water-based acrylic fire retardant coating, characterized in that: The composition comprises the following components in parts by weight: 20-30 parts of montmorillonite modified acrylic emulsion, 20-30 parts of ammonium polyphosphate, 3-8 parts of pentaerythritol, 10-20 parts of slow burnout modified dextrin oligomer, 10-20 parts of melamine, 3-5 parts of titanium dioxide, 0.3-1 parts of hydroxyethyl cellulose, 0.5-1 parts of dispersant, 0.5-1 parts of defoamer, 0-2 parts of mildewproof agent, 0.5-1 parts of n-octanol, and 3-20 parts of water; The preparation method of the slow-burning modified dextrin oligomer comprises the following steps: (1) Mixing starch and water at 10-30° C. to obtain a mixed solution; treating the mixed solution with high-pressure steam at a temperature of 100-200° C. for 10-20 seconds, and then drying to obtain a dextrin intermediate; the weight ratio of starch to water is 1:3-5, and the molecular weight of the dextrin intermediate is 3000-8000; (2) mixing the dextrin intermediate with nano-alumina, ethoxysilane and dispersant in a weight ratio of 1:0.05-0.5:0.05-0.5:0.3-1, treating the mixture under ultrasound at a frequency of 30-50 kHz for 20-30 minutes, and performing solid-liquid separation to obtain a slow-burning modified dextrin oligomer; Wherein, the montmorillonite modified acrylic emulsion is made from the following raw materials in parts by weight: 10-20 parts of n-butyl acrylate, 5-20 parts of methyl methacrylate, 1-3 parts of methacrylic acid, 0.2-2 parts of organic montmorillonite, 0.5-2 parts of emulsifier, 0.01-0.2 parts of buffer, 0.05-0.15 parts of initiator, 18-40 parts of water; The organic montmorillonite is prepared by modifying sodium montmorillonite with a surfactant CTAB, and the mass ratio of the surfactant CTAB to the sodium montmorillonite is (1-2):1; The emulsifier is selected from sodium lauryl sulfate and polyethylene glycol octyl phenyl ether, and the weight ratio of sodium lauryl sulfate to polyethylene glycol octyl phenyl ether is 1-2:1; The initiator is potassium persulfate and / or ammonium persulfate; The buffer is selected from sodium bicarbonate and / or potassium bicarbonate; The preparation method of the montmorillonite modified acrylic emulsion comprises the following steps: (1) 8 to 15 parts of n-butyl acrylate, 1 to 4 parts of methacrylate, 0.1 to 0.5 parts of organic montmorillonite, 6 to 15 parts of water, and 0.05 to 0.12 parts of an emulsifier are mixed and emulsified to obtain a first emulsion; (2) 1 to 6 parts of n-butyl acrylate, 5 to 12 parts of methacrylate, 1 to 3 parts of methacrylic acid, 0.1 to 0.5 parts of organic montmorillonite, 6 to 15 parts of water, and 0.05 to 0.12 parts of an emulsifier are mixed and emulsified to obtain a second emulsion; (3) 0.01-0.2 parts of a buffer, 6-15 parts of water, and 0.05-0.12 parts of an emulsifier are mixed evenly to obtain a buffer solution, and 0.05-0.15 parts of an initiator and 3-10 parts of water are mixed evenly to obtain an initiating solution; (4) 40-60 vol% of the first emulsion and the buffer solution are mixed, and 20-50 vol% of the initiation solution based on the total amount of the initiation solution is added dropwise, and the mixture is reacted at 65°C-80°C for 20-40 min to obtain a seed emulsion; (5) adding the remaining first emulsion and 20 to 50 vol% of the initiating solution to the seed emulsion, reacting at 70° C. to 90° C. for 20 to 40 min after the addition is complete, to obtain a core emulsion; (6) Add the remaining initiating solution and the second emulsion to the core emulsion. After the addition is completed, react at 80-90°C for 20-40 minutes, cool, and filter to obtain the product.

2. The water-based acrylic fire retardant coating according to claim 1, characterized in that: In step (1), the mixed solution is treated with high-pressure steam and then spray-dried to obtain a dextrin intermediate.

3. The water-based acrylic fire retardant coating according to claim 1 or 2, characterized in that: The dispersant is selected from one or more of ethanol, propanol, acetone and glycerol; and / or The ethoxysilane is selected from γ-aminopropyltriethoxysilane and / or γ-methacryloxypropyltrimethoxysilane.

4. The water-based acrylic fire retardant coating according to claim 1 or 2, characterized in that: The particle size of the nano-alumina is 30-100 nm.

5. The water-based acrylic fire retardant coating according to claim 1 or 2, characterized in that: The dispersant is acetone; and / or The ethoxysilane is selected from γ-aminopropyltriethoxysilane; and / or The particle size of the nano-alumina is 30nm~50nm; and / or The weight ratio of the nano-alumina, ethoxysilane and dispersant is 1:0.05-0.1:0.08-0.12:0.4-0.

7.

6. A method for preparing a water-based acrylic fire retardant coating, for preparing the water-based acrylic fire retardant coating as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Evenly mix pentaerythritol, melamine, slow-burning modified dextrin oligomer, titanium dioxide and water; (2) Add hydroxyethyl cellulose, defoamer, dispersant and mildew inhibitor and mix well; (3) Add ammonium polyphosphate, montmorillonite-modified acrylic emulsion and n-octanol and mix well to obtain the product.

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