Polyurea coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of coatings, and particularly relates to a polyurea coating as well as a preparation method and application thereof. The polyurea coating comprises a component A and a component B, the component A comprises polyaspartic acid ester polyurea resin, a compound flame retardant, an auxiliary agent and a filler; the compound flame retardant is prepared from melamine polyphosphate, polyhedral oligomeric silsesquioxane and double-layer coated aluminum phytate; the double-layer coated aluminum phytate comprises a coupling agent layer and a stearic acid layer which are sequentially arranged outwards from the aluminum phytate side; and the component B comprises an isocyanate prepolymer. According to the invention, melamine polyphosphate, double-layer coated aluminum phytate and polyhedral oligomeric silsesquioxane are adopted to synergistically construct a flame-retardant system, and inorganic-organic phosphorus is adopted to synergistically form charcoal, a POSS dynamic cage structure is adopted to inhibit smoke and molten drops, and a bio-based acid source is adopted to improve the strength of a carbon source, so that the polyurea coating has good flame retardance, thermal stability and mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and specifically relates to a polyurea coating, its preparation method, and its application. Background Technology

[0002] Polyurea elastomers are widely used in protective coatings and flooring due to their excellent mechanical strength, adhesion, and chemical resistance. However, conventional polyurea is highly flammable, with an oxygen index of only about 20-21%. It can rapidly fail under high temperatures or ignition sources, producing large amounts of smoke and molten droplets, posing a serious fire hazard.

[0003] Currently, the main way to improve the flame retardant properties of polyurea is to add inorganic or organic flame retardants. However, traditional filler-type flame retardants have poor compatibility with organic matrices, and the flame retardants are prone to migration and precipitation, resulting in a decrease in the mechanical properties and durability of the coating film, and making it difficult to meet the requirements of modern green construction (such as solvent-free and low volatile organic compound (VOC)).

[0004] Therefore, it is of great significance to provide an environmentally friendly polyurea coating with good flame retardancy, thermal stability and mechanical properties. Summary of the Invention

[0005] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial solution. Specifically, the present invention provides a polyurea coating that has good flame retardancy, thermal stability and mechanical properties, and is suitable for manual application and is environmentally friendly.

[0006] The inventive concept of this invention: The polyurea coating of this invention comprises component A and component B; component A comprises polyaspartic acid ester polyurea resin, compound flame retardant, additives, and fillers; the compound flame retardant comprises melamine polyphosphate, cage-type silsesquioxane, and double-layer coated aluminum phytate; the double-layer coated aluminum phytate comprises a coupling agent layer and a stearic acid layer sequentially from the aluminum phytate side outwards; component B comprises isocyanate prepolymer.

[0007] This invention employs melamine polyphosphate (MPP), double-layer coated aluminum phytate (APA), and cage-like silsesquioxane (POSS) to synergistically construct a flame-retardant system. Through the synergistic char formation of inorganic and organic phosphorus, the dynamic cage structure of POSS suppresses smoke and dripping, the bio-based acid source enhances the carbon source strength, and the cage-like silsesquioxane forms a dense ceramicized silica film at high temperatures. This allows for the achievement of no dripping and an oxygen index greater than 38% even with an ultra-thin coating (≤0.8mm). At the same time, it significantly reduces the adverse effects of high filler content on toughness, achieving synergistic optimization of flame retardancy and mechanical properties, that is, possessing good flame retardant performance, thermal stability, and mechanical properties.

[0008] Therefore, a first aspect of the present invention provides a polyurea coating.

[0009] Specifically, the polyurea coating includes component A and component B; Component A includes polyaspartic acid ester polyurea resin, compounded flame retardant, additives, and fillers; The compound flame retardant includes melamine polyphosphate, double-coated aluminum phytate, and cage-type silsesquioxane. The double-layered aluminum phytate includes a coupling agent layer and a stearic acid layer arranged sequentially from the aluminum phytate side outwards. Component B includes isocyanate prepolymer.

[0010] Preferably, the polyaspartic ester polyurea resin comprises a first polyaspartic ester polyurea resin and a second polyaspartic ester polyurea resin; the first polyaspartic ester polyurea resin comprises methylene bis(2-methyl-4,1-cyclohexyl)bisaspartic ester; and the second polyaspartic ester polyurea resin comprises an aromatic amine type amino resin.

[0011] Preferably, the mass ratio of the first polyaspartic acid ester polyurea resin to the second polyaspartic acid ester polyurea resin is (1-2):1; more preferably, the mass ratio of the first polyaspartic acid ester polyurea resin to the second polyaspartic acid ester polyurea resin is 1:1.

[0012] Preferably, the mass ratio of the double-coated aluminum phytate, melamine polyphosphate, and cage-like silsesquioxane is (0.8-1.2):(1.8-2.2):(0.5-0.9); more preferably, the mass ratio of the double-coated aluminum phytate, melamine polyphosphate, and cage-like silsesquioxane is (0.9-1.1):(1.9-2.1):(0.6-0.8); even more preferably, the mass ratio of the double-coated aluminum phytate, melamine polyphosphate, and cage-like silsesquioxane is 1:2:0.7.

[0013] Preferably, the cage-like silsesquioxane comprises an aminocage-like silsesquioxane.

[0014] Preferably, by mass parts, component A comprises 100 parts of polyaspartic acid ester polyurea resin, 20-35 parts of compound flame retardant, 0.9-8.3 parts of additives, and 4-39 parts of filler.

[0015] More preferably, by mass parts, component A comprises 100 parts of polyaspartic acid ester polyurea resin, 25-30 parts of compound flame retardant, 4.7-8.3 parts of additives, and 31-39 parts of filler.

[0016] Preferably, the mass content of NCO groups in component B is 17-23%; more preferably, the mass content of NCO groups in component B is 19-21%.

[0017] Specifically, component B provides NCO groups that react with component A to form a highly cross-linked polyurea network structure.

[0018] Preferably, the additive includes at least one of a dispersant, a defoamer, a leveling agent, and a latent curing agent; more preferably, the additive includes a dispersant, a defoamer, a leveling agent, and a latent curing agent.

[0019] Preferably, the dispersant comprises a polyurethane dispersant.

[0020] Preferably, the defoamer includes an organosilicone defoamer.

[0021] Preferably, the leveling agent comprises an acrylate leveling agent.

[0022] Preferably, the latent curing agent includes aliphatic amine-modified latent curing agents.

[0023] Specifically, component A contains a latent curing agent, which makes the open time of the mixed polyurea coating 15-20 minutes. It is suitable for manual roller coating, scraper coating or brush coating in the temperature range of 0℃ to 40℃. The surface drying time at room temperature does not exceed 4 hours, and it is fully cured within 24 hours.

[0024] Preferably, the filler includes at least one of titanium dioxide and silicon micropowder; more preferably, the filler includes titanium dioxide and silicon micropowder.

[0025] Preferably, by mass parts, component A comprises 100 parts of polyaspartic acid ester polyurea resin, 20-35 parts of compound flame retardant, 0.9-1.1 parts of dispersant, 0.9-1.1 parts of defoamer, 0.9-1.1 parts of leveling agent, 2-5 parts of latent curing agent, 4-6 parts of titanium dioxide, and 27-33 parts of silica powder.

[0026] More preferably, by weight, component A comprises 100 parts of polyaspartic acid ester polyurea resin, 25-30 parts of compound flame retardant, 0.9-1.1 parts of dispersant, 0.9-1.1 parts of defoamer, 0.9-1.1 parts of leveling agent, 2-5 parts of latent curing agent, 4-6 parts of titanium dioxide, and 27-33 parts of silica powder.

[0027] Preferably, the volume ratio of component A to component B is (1.5-2.5):1; more preferably, the volume ratio of component A to component B is (1.8-2.2):1; even more preferably, the volume ratio of component A to component B is 2:1.

[0028] A second aspect of the present invention provides a method for preparing the polyurea coating described in the first aspect of the present invention.

[0029] Specifically, the preparation method of the polyurea coating includes the following steps: The raw material components of component A are mixed to obtain component A; The components A and B constitute the polyurea coating.

[0030] Preferably, the preparation method of the compound flame retardant includes the following steps: The mixture of melamine polyphosphate, double-coated aluminum phytate, and cage-type silsesquioxane was ground, then polydopamine solution was added, followed by heat treatment to obtain the final product.

[0031] Preferably, the grinding includes ball milling, the ball milling speed is 80-120 rpm, the ball milling time is 8-12 min, and the ball-to-material ratio of the ball milling is (4-6):1.

[0032] More preferably, the grinding includes ball milling, the ball milling speed is 90-110 rpm, the ball milling time is 9-11 min, and the ball-to-material ratio of the ball milling is (4.5-5.5):1.

[0033] More preferably, the grinding includes ball milling, the ball milling speed is 100 rpm, the ball milling time is 10 min, and the ball-to-material ratio of the ball milling is 5:1.

[0034] Specifically, the purpose of ball milling is to avoid agglomeration and obtain a free-flowing powder (angle of repose ≤ 30°).

[0035] Preferably, the solvent in the polydopamine solution includes ethanol.

[0036] Preferably, the mass fraction of the polydopamine solution is 0.8-1.2%; more preferably, the mass fraction of the polydopamine solution is 0.9-1.1%; and even more preferably, the mass fraction of the polydopamine solution is 1%.

[0037] Preferably, the polydopamine solution is added and then stirred.

[0038] Preferably, during the stirring process after adding the polydopamine solution, the stirring temperature is 50-70°C and the stirring time is 0.8-1.2 h; more preferably, the stirring temperature is 55-65°C and the stirring time is 0.9-1.1 h; even more preferably, the stirring temperature is 60°C and the stirring time is 1 h.

[0039] Preferably, the heat treatment temperature is 110-130℃ and the heat treatment time is 25-35 min; more preferably, the heat treatment temperature is 115-125℃ and the heat treatment time is 27-33 min; even more preferably, the heat treatment temperature is 120℃ and the heat treatment time is 30 min.

[0040] Preferably, the melamine polyphosphate is pretreated before mixing, and the pretreatment includes the following steps: Stearic acid and solvent are mixed, then melamine polyphosphate is added and dried.

[0041] Preferably, the solvent used in the pretreatment process includes ethanol.

[0042] Preferably, the mass fraction of stearic acid after mixing with the solvent is 1.5-2.5%; more preferably, the mass fraction of stearic acid after mixing with the solvent is 1.8-2.2%; and even more preferably, the mass fraction of stearic acid after mixing with the solvent is 2%.

[0043] Preferably, the mass ratio of stearic acid to melamine polyphosphate is (1-2):100; more preferably, the mass ratio of stearic acid to melamine polyphosphate is 1:50.

[0044] Preferably, during the drying process of adding melamine polyphosphate, the drying temperature is 65-85℃ and the drying time is 1.5-2.5h; more preferably, the drying temperature is 70-80℃ and the drying time is 1.8-2.2h; even more preferably, the drying temperature is 75℃ and the drying time is 2h.

[0045] Preferably, after adding melamine polyphosphate, the mixture is first subjected to ultrasonic treatment and then dried.

[0046] Preferably, the ultrasonic treatment time is 25-35 min; more preferably, the ultrasonic treatment time is 27-33 min; even more preferably, the ultrasonic treatment time is 30 min.

[0047] Preferably, the method for preparing the double-layer coated aluminum phytate includes the following steps: The coupling agent, stearic acid, and solvent are mixed, and then aluminum phytate is added and dried to obtain the final product.

[0048] Preferably, the coupling agent comprises a silane coupling agent; more preferably, the silane coupling agent comprises γ-glycidoxypropyltrimethoxysilane.

[0049] Preferably, when preparing double-coated aluminum phytate, the solvent includes ethanol.

[0050] Preferably, in preparing the double-coated aluminum phytate, the mixture obtained after mixing contains a coupling agent with a mass fraction of 4-6% and a stearic acid mass fraction of 1.5-2.5%; more preferably, the mixture contains a coupling agent with a mass fraction of 4.5-5.5% and a stearic acid mass fraction of 1.8-2.2%; even more preferably, the mixture contains a coupling agent with a mass fraction of 5% and a stearic acid mass fraction of 2%.

[0051] Preferably, the mass ratio of aluminum phytate to coupling agent is (35-50):(1-2); more preferably, the mass ratio of aluminum phytate to coupling agent is 45:1.

[0052] Preferably, after adding the aluminum phytate, the mixture is stirred at a temperature of 50-70°C for 1.5-2.5 hours; more preferably, the stirring temperature is 55-65°C for 1.8-2.2 hours; and even more preferably, the stirring temperature is 60°C for 2 hours.

[0053] Preferably, when preparing double-coated aluminum phytate, the drying temperature is 70-90℃ and the drying time is 1.5-2.5h; more preferably, when preparing double-coated aluminum phytate, the drying temperature is 75-85℃ and the drying time is 1.8-2.2h; even more preferably, when preparing double-coated aluminum phytate, the drying temperature is 80℃ and the drying time is 2h.

[0054] Preferably, when preparing double-coated aluminum phytate, the drying is performed using vacuum drying.

[0055] A third aspect of the present invention provides an application of the polyurea coating described in the first aspect of the present invention in fireproof building flooring.

[0056] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows: (1) The present invention uses melamine polyphosphate, double-layer coated aluminum phytate and cage-type silsesquioxane (POSS) to synergistically construct a flame retardant system. Through the synergistic char formation of inorganic-organic phosphorus, the dynamic cage structure of POSS suppresses smoke and dripping, and the bio-based acid source enhances the carbon source strength. This enables the effect of no dripping and an oxygen index greater than 38% under ultra-thin coating conditions (≤0.8mm). At the same time, it significantly reduces the adverse effects of high filler on toughness, achieves synergistic optimization of flame retardancy and mechanical properties, and has good flame retardant performance, thermal stability and mechanical properties.

[0057] (2) The present invention adopts a latent curing agent system design to achieve an open time of 15-20 minutes, supports construction in a low temperature environment of 0℃, and the coating can be manually operated by scraping, rolling, brushing, etc., breaking the construction limitation that polyurea systems must be sprayed.

[0058] (3) By constructing a composite flame retardant and latent curing functional system, this invention combines an internally stable chemical structure (urea bond) with externally excellent physical properties (high strength, high elasticity, and wear resistance), breaking through the technical bottlenecks of traditional polyurea materials in terms of flame retardant rating, construction method, and service life. It is particularly suitable for fireproof flooring systems in high-risk application scenarios such as chemical plants, lithium battery workshops, and tunnels. Detailed Implementation

[0059] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0060] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0061] Example 1 This embodiment provides a polyurea coating, which is composed of component A and component B; By mass, component A consists of 100 parts of a mixture of first polyaspartic ester polyurea resin (methylene bis(2-methyl-4,1-cyclohexyl)bisaspartic ester) and second polyaspartic ester polyurea resin (aromatic amine type amino resin, Guangzhou Yinxu R108), 30 parts of compound flame retardant, 5 parts of titanium dioxide, 30 parts of silica powder, 1 part of polyurethane dispersant (BYK-163, purchased from BYK Chemical), 1 part of defoamer (BYK-054, purchased from BYK Chemical), 1 part of leveling agent (EFKA-3777, purchased from BASF), and 3.5 parts of latent curing agent (AFCONA-K125). Component B is a hexamethylene diisocyanate prepolymer (HDI prepolymer) with an NCO content of 20.5 wt%. The mass ratio of the first polyaspartic acid ester polyurea resin to the second polyaspartic acid ester polyurea resin is 1:1. The volume ratio of component A to component B is 2:1.

[0062] The preparation process of the above polyurea coating is as follows: Mix all raw material components of component A and disperse at high speed of 1500 rpm for 30 minutes until uniform to obtain component A; component A and component B constitute polyurea coating.

[0063] The preparation process of the compound flame retardant is as follows: (1) Add aluminum phytate to 5wt% KH-560 ethanol solution and 2wt% stearic acid ethanol solution. The mass ratio of aluminum phytate to coupling agent KH-560 is 45:1. Stir at 60℃ for 2h and then vacuum dry at 80℃ for 2h to obtain double-layer coated aluminum phytate. MPP was added to a 2wt% stearic acid ethanol solution, with a stearic acid to MPP mass ratio of 1:50. The solution was ultrasonically treated for 30 min and then dried at 75℃ for 2 h to obtain pretreated MPP. (2) The double-coated aluminum phytate, pretreated MPP and POSS were mixed at a mass ratio of 1:2:0.7 and dry ball milled at a speed of 100 rpm for 10 minutes. The ball-to-material ratio during ball milling was 5:1 to obtain a free-flowing powder (angle of repose ≤30°). (3) Add 1 wt% polydopamine ethanol solution to the free-flowing powder obtained in step (2), stir at 60°C for 1 h, and then heat treat at 120°C for 30 min to obtain a ternary compound flame retardant.

[0064] Example 2 This embodiment provides a polyurea coating, which is composed of component A and component B; By mass, component A consists of 100 parts of a mixture of first polyaspartic ester polyurea resin methylene bis(2-methyl-4,1-cyclohexyl) bisaspartic ester and second polyaspartic ester polyurea resin aromatic amine amino resin, 25 parts of compound flame retardant, 5 parts of titanium dioxide, 30 parts of silica powder, 1 part of polyurethane dispersant (BYK-163, purchased from BYK Chemical), 1 part of defoamer (BYK-054, purchased from BYK Chemical), 1 part of leveling agent (EFKA-3777, purchased from BASF), and 2 parts of latent curing agent (AFCONA-K125). Component B is an HDI prepolymer with an NCO content of 20.5 wt%. The mass ratio of the first polyaspartic acid ester polyurea resin to the second polyaspartic acid ester polyurea resin is 1:1. The volume ratio of component A to component B is 2:1.

[0065] The preparation process of the above polyurea coating is as follows: Mix all raw material components of component A and disperse at high speed of 1500 rpm for 30 minutes until uniform to obtain component A; component A and component B constitute polyurea coating.

[0066] The preparation process of the compound flame retardant is the same as in Example 1.

[0067] Example 3 This embodiment provides a polyurea coating, which is composed of component A and component B; By mass, component A consists of 100 parts of a mixture of first polyaspartic ester polyurea resin methylene bis(2-methyl-4,1-cyclohexyl) bisaspartic ester and second polyaspartic ester polyurea resin aromatic amine amino resin, 20 parts of compound flame retardant, 5 parts of titanium dioxide, 30 parts of silica powder, 1 part of polyurethane dispersant (BYK-163, purchased from BYK Chemical), 1 part of defoamer (BYK-054, purchased from BYK Chemical), 1 part of leveling agent (EFKA-3777, purchased from BASF), and 5 parts of latent curing agent (AFCONA-K125). Component B is an HDI prepolymer with an NCO content of 20.5 wt%. The volume ratio of component A to component B is 2:1.

[0068] The preparation process of the above polyurea coating is as follows: Mix all raw material components of component A and disperse at high speed for 30 minutes until homogeneous to obtain component A; component A and component B constitute polyurea coating.

[0069] The preparation process of the compound flame retardant is the same as in Example 1.

[0070] Performance testing The performance of the polyurea coatings prepared in Examples 1-3 was tested. The test items and methods are as follows: Limiting Oxygen Index (LOI) Test: Performed according to ASTM D2863; 1mm drip test: Refer to UL 94 "Tests for flammability of plastic materials for equipment and appliance components"; Carbon residue: Tested in accordance with ISO 11358 "Thermogravimetric analysis (TG) of plastic polymers - General principles"; The performance test results of the polyurea coatings prepared in Examples 1-3 are shown in Table 1.

[0071] Table 1: Performance test results of polyurea coatings prepared in Examples 1-3

[0072] As shown in Table 1, when the amount of compound flame retardant added is 25-30 parts, the LOI is >42%, the UL94 V-0 rating is achieved, and the mechanical properties are maintained well (tensile strength >15MPa, which can be tested using conventional methods in this field). This proves that the ternary synergistic flame retardant system effectively balances mechanical properties while ensuring flame retardant performance, and can achieve an open time of 15-20 minutes.

[0073] In summary, this invention employs melamine polyphosphate, double-layered aluminum phytate, and cage-type silsesquioxane to synergistically construct a flame-retardant system. Through the synergistic char formation of inorganic and organic phosphorus, the POSS dynamic cage structure suppresses smoke and dripping, and the bio-based acid source enhances the carbon source strength, the polyurea coating exhibits excellent flame-retardant properties, thermal stability, and mechanical properties.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polyurea coating, characterized in that, Includes component A and component B; Component A includes polyaspartic acid ester polyurea resin, compounded flame retardant, additives, and fillers; The compound flame retardant includes melamine polyphosphate, cage-type silsesquioxane, and double-coated aluminum phytate. The double-layered aluminum phytate includes a coupling agent layer and a stearic acid layer arranged sequentially from the aluminum phytate side outwards. Component B includes isocyanate prepolymer.

2. The polyurea coating according to claim 1, characterized in that, The polyaspartic acid ester polyurea resin includes a first polyaspartic acid ester polyurea resin and a second polyaspartic acid ester polyurea resin; the first polyaspartic acid ester polyurea resin includes methylene bis(2-methyl-4,1-cyclohexyl)bisaspartic acid ester; the second polyaspartic acid ester polyurea resin includes an aromatic amine type amino resin.

3. The polyurea coating according to claim 2, characterized in that, The mass ratio of the first polyaspartic acid ester polyurea resin to the second polyaspartic acid ester polyurea resin is (1-2):1; And / or, in the compound flame retardant, the mass ratio of the double-coated aluminum phytate, melamine polyphosphate and cage-type silsesquioxane is (0.8-1.2):(1.8-2.2):(0.5-0.9). And / or, the cage-like silsesquioxanes include amino cage-like silsesquioxanes.

4. The polyurea coating according to claim 1, characterized in that, By weight, component A comprises 100 parts of polyaspartic acid ester polyurea resin, 20-35 parts of compound flame retardant, 0.9-8.3 parts of additives, and 4-39 parts of filler; And / or, the mass content of NCO groups in component B is 17-23%.

5. The polyurea coating according to claim 1, characterized in that, The additives include at least one of dispersants, defoamers, leveling agents, and latent curing agents; and / or, the fillers include at least one of titanium dioxide and silica powder.

6. The method for preparing the polyurea coating according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: The raw material components of component A are mixed to obtain component A; The components A and B constitute the polyurea coating.

7. The preparation method according to claim 6, characterized in that, The preparation method of the compound flame retardant includes the following steps: The mixture of melamine polyphosphate, double-coated aluminum phytate, and cage-type silsesquioxane was ground, then polydopamine solution was added, followed by heat treatment to obtain the final product.

8. The preparation method according to claim 7, characterized in that, The grinding includes ball milling, the ball milling speed is 80-120 rpm, the ball milling time is 8-12 min, and the ball-to-material ratio of the ball milling is (4-6):1; And / or, the heat treatment temperature is 110-130℃, and the heat treatment time is 25-35 min; And / or, the method for preparing the double-layer coated aluminum phytate includes the following steps: The coupling agent, stearic acid, and solvent are mixed, and then aluminum phytate is added and dried to obtain the product. And / or, the melamine polyphosphate is pretreated before mixing, the pretreatment comprising the following steps: Stearic acid and solvent are mixed, then melamine polyphosphate is added and dried.

9. The preparation method according to claim 8, characterized in that, In preparing the double-layer coated aluminum phytate, the mixture obtained after mixing contains a coupling agent with a mass fraction of 4-6% and a stearic acid mass fraction of 1.5-2.5%. And / or, when preparing the double-coated aluminum phytate, the mass ratio of aluminum phytate to coupling agent is (35-50):(1-2). And / or, when pretreating the melamine polyphosphate, the mass ratio of stearic acid to melamine polyphosphate is (1-2):

100.

10. The application of the polyurea coating according to any one of claims 1-5 in fireproof building flooring.

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