High and low temperature resistant water-based paint, preparation method and application thereof

Abstract

The application discloses a high and low temperature resistant water-based paint and a preparation method and application thereof. The paint comprises a component A and a component B. The component A is prepared from components including an organic fluorine modified hydroxyl acrylate grafted polyurethane emulsion, an additive, a pigment and a filler. The component B is prepared from components including a curing agent and a solvent. The paint has excellent high and low temperature resistance, stain resistance, water resistance and weather resistance, solves the problems of insufficient high and low temperature resistance, poor stain resistance and durability of the existing paint in a high and cold environment, and is suitable for coating of train interiors in high and cold regions.

Description

Technical Field

[0001] This invention relates to the field of coatings, and more specifically, to a high and low temperature resistant water-based coating, its preparation method, and its application. Background Technology

[0002] With the rapid development of the train transportation industry, the operating environment of trains is becoming increasingly complex, especially in high-altitude and cold regions where winter temperatures can drop to below -40°C and summer temperatures inside the carriages can reach above 60°C. This extreme alternating high and low temperature environment places stringent requirements on the performance of train interior coatings.

[0003] Currently, most train interior coatings on the market are solvent-based. Although they can meet basic requirements in some aspects, solvent-based coatings contain a large amount of volatile organic compounds (VOCs), which are harmful to the environment and human health and do not meet environmental protection requirements.

[0004] Water-based coatings, using water as the dispersion medium, have low VOC content and offer advantages such as environmental friendliness and safety, gradually becoming a development trend in the coatings industry. However, existing water-based train interior coatings lack sufficient high and low temperature resistance in extremely cold environments, and are prone to cracking and peeling after high and low temperature cycling, failing to meet the usage requirements of trains in cold environments. Summary of the Invention

[0005] This invention aims to address the technical shortcomings of existing train interior coatings, such as insufficient high and low temperature resistance, poor stain resistance, and inadequate durability in cold environments. This invention uses polyurethane resin as the core modifying component, and through a chemical grafting process, uniformly introduces organic fluorine monomers and hydroxyl groups into the main chain of acrylic resin molecules. Utilizing the flexible segments of polyurethane, the low-temperature toughness and high-temperature creep resistance of the resin are optimized. By leveraging the low surface energy and high bond energy characteristics of organic fluorine monomers, the resin's heat resistance, stain resistance, water resistance, and weather resistance are significantly improved. Simultaneously, the hydroxyl groups provide sufficient active sites for subsequent crosslinking reactions. This modified resin is then compounded with an isocyanate curing agent, and through the crosslinking reaction of hydroxyl groups and isocyanate groups, a dense three-dimensional network cured film is formed, further enhancing the resin's mechanical strength, adhesion, and chemical corrosion resistance, making it suitable for coating train interiors in cold regions.

[0006] Firstly, one of the objectives of this invention is to provide a water-based coating that is resistant to high and low temperatures.

[0007] Specifically, the above-mentioned high and low temperature resistant water-based coating includes component A and component B, and the mass ratio of component A to component B is (5-7):1; wherein, component A is formulated from components including organofluorine modified hydroxyl acrylic grafted polyurethane emulsion, additives, pigments and fillers; component B is formulated from components including curing agent and solvent.

[0008] Furthermore, in component A, based on a total weight of 100 parts by weight, the weight parts of each component are as follows: 60-70 parts by weight, preferably 60-65 parts by weight, of an organofluorine modified hydroxyl acrylic acid grafted polyurethane emulsion; The additive is 13-22 parts by weight, preferably 16-22 parts by weight; The pigment and filler are 15-25 parts by weight, preferably 20-25 parts by weight.

[0009] Furthermore, the preparation method of the organofluorine modified hydroxyl acrylic grafted polyurethane emulsion includes the following steps: Step 1: Mix the components including polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, and propylene glycol methyl ether acetate, and react them under the action of a catalyst to obtain a prepolymer with NCO end groups; then add hydroxyethyl acrylate and a catalyst to react and obtain an aqueous polyurethane prepolymer containing carbon-carbon double bonds. Step 2: Add methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, tert-dodecyl mercaptan, and azobisisobutyramidine hydrochloride aqueous solution to the waterborne polyurethane prepolymer containing carbon-carbon double bonds, react, cool, adjust pH, filter and discharge to obtain organofluorine modified hydroxyacrylic acid grafted polyurethane emulsion.

[0010] Furthermore, the preparation method of the organofluorine modified hydroxyl acrylic grafted polyurethane emulsion includes the following steps: Step 1: Mix the components including polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, propylene glycol methyl ether acetate, and catalyst, heat to 70-80℃, and react for 2-3 hours to obtain a prepolymer with NCO end groups; then add hydroxyethyl acrylate and catalyst, keep the reaction at the same temperature for 1-2 hours, cool to 40-50℃, add triethylamine, react for 20-30 minutes, and add deionized water under high-speed stirring to obtain a waterborne polyurethane prepolymer containing carbon-carbon double bonds; Step 2: First, heat the aqueous polyurethane prepolymer containing carbon-carbon double bonds to 50-60℃. Then, simultaneously add a mixture of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, and tert-dodecyl mercaptan, along with an aqueous solution of azobisisobutyramidine hydrochloride, to the aqueous polyurethane prepolymer. The addition should be completed over 2-3 hours. After maintaining the temperature for 1-2 hours, add the aqueous solution of azobisisobutyramidine hydrochloride, then heat to 60-70℃ for aging for 0.5-1 hour. Cool to 40-50℃, adjust the pH to 7.5-8.5, and filter to obtain an organofluorine modified hydroxyl acrylic acid grafted polyurethane emulsion.

[0011] This invention modifies acrylic resin with polyurethane resin, improving problems such as low-temperature cracking, poor impact resistance, and poor adhesion to substrates. Specifically, the selected polycarbonate diol exhibits superior heat resistance, water resistance, and weather resistance compared to other polyether diols and polyester diols, and also maintains good elasticity at low temperatures. Furthermore, the selected trifluoroethyl methacrylate monomer has good compatibility with the acrylate monomer, avoiding uneven fluorine atom distribution during synthesis and ensuring the stability of the emulsion.

[0012] Preferably, in the organofluorine modified hydroxyacrylic acid grafted polyurethane emulsion, the mass content of organofluorine modified hydroxyacrylic acid grafted polyurethane is 45%-50%.

[0013] Preferably, in step one, The mass ratio of polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, and hydroxyethyl acrylate is (55-65):(4-8):(20-32):(6-10); Based on the total mass of polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, and hydroxyethyl acrylate monomers, the mass of propylene glycol methyl ether acetate added is 10%-20% of the total mass of the above monomers; the mass of the catalyst added is 0.02%-0.05% of the total mass of the above monomers. The catalyst is selected from dibutyltin dilaurate; the first application of the catalyst is 70%-90% of its total mass, and the second application is 10%-30% of its total mass. The amount of triethylamine used is 60%-80% of the mass of dimethylolpropionic acid.

[0014] Preferably, in step two, The mass ratio of methyl methacrylate to n-butyl acrylate is (20-30):(70-80). Based on the total mass of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, and tert-dodecyl mercaptan monomers, the mass of hydroxyethyl methacrylate added is 15%-25% of the total mass of the reactants; the mass of methacrylic acid added is 1%-5% of the total mass of the reactants; the mass of trifluoroethyl methacrylate added is 10%-20% of the total mass of the reactants; the mass of tert-dodecyl mercaptan added is 0.2%-0.6% of the total mass of the reactants; and the mass of azobisisobutyramidine hydrochloride aqueous solution added is 2%-6% of the total mass of the reactants, wherein the mass concentration of the azobisisobutyramidine hydrochloride aqueous solution is 10%-20%, and its first addition is 80%-90% of its total mass, and its second addition is 10%-20% of its total mass.

[0015] It is worth mentioning that this application uses trifluoroethyl methacrylate, which introduces fluorine atoms uniformly into the acrylic resin chain segments through free radical reaction. When the particles are formed, the fluorine groups can be fully exposed on the particle surface to form a continuous and dense hydrophobic fluorine layer, which isolates the particles from the attack of electrolytes and water molecules in the aqueous phase, avoids particle aggregation and sedimentation, and is beneficial to the storage stability of the emulsion. Meanwhile, this application uses hydroxyethyl acrylate to end-cap the NCO groups of the polyurethane prepolymer, introducing carbon-carbon double bonds at both ends of the polyurethane prepolymer. Then, acrylic monomers are added, including the hard monomer methyl methacrylate, the soft monomer n-butyl acrylate, hydroxyethyl methacrylate with active reactive groups (hydroxyl groups) introduced into the molecular chain, methacrylic acid for stabilizing emulsion, and trifluoroethyl methacrylate with fluorine atoms introduced. Through free radical reaction, fluorine atoms and hydroxyl groups are uniformly introduced into the acrylic resin chain segments. When the synthesized organofluorine modified hydroxyl acrylic grafted polyurethane resin is used in a two-component coating system, the active reactive groups (hydroxyl groups) introduced into the resin chain segments undergo a crosslinking reaction with the isocyanate curing agent, increasing the crosslinking density of the coating. Compared with a single-component system, it can significantly improve the comprehensive properties of the coating, such as heat resistance, water resistance, resistance to methyl ethyl ketone (MEK) wiping, abrasion resistance, and resistance to high and low temperatures.

[0016] Further, the ratio of the total mass of the reacting monomers in step one to the total mass of the reacting monomers in step two is (30-40):(60-70); wherein, in step one, the total mass of the reacting monomers is based on the total mass of polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, and hydroxyethyl acrylate monomers; and in step two, the total mass of the reacting monomers is based on the total mass of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, and tert-dodecyl mercaptan.

[0017] Furthermore, the additives are selected from one or a combination of dispersants, substrate wetting agents, leveling agents, defoamers, antisettling agents, thickeners, antibacterial agents, and flame retardants.

[0018] Preferably, the dispersant is selected from polycarboxylate dispersants, such as BYK-187; the substrate wetting agent is selected from polyether-modified polydimethylsiloxane solution, such as BYK-346; the leveling agent is selected from acrylate leveling agents, such as BYK-358; the defoamer is selected from silicone surfactants, such as BYK-024; the anti-settling agent is selected from treated easily dispersible lithium montmorillonite clay, such as BENTONEDY CE; the thickener is selected from nonionic waterborne polyurethane, such as COAPUR XS-71; the antibacterial agent is selected from one or a combination of silver ion compounds, zinc ion compounds, polyquaternium-73, and isothiazolinone; and the flame retardant is selected from one or a combination of aluminum phosphate, zinc phosphate, melamine, melamine polyphosphate, fumed silica, and kaolin.

[0019] Furthermore, the pigments and fillers are selected from one or a combination of pigments and fillers; wherein the pigments are selected from inorganic pigments and / or organic pigments; wherein the inorganic pigments are selected from one or a combination of titanium dioxide, cobalt blue, carbon black, iron yellow, and iron oxide red; the organic pigments are selected from one or a combination of permanent yellow, phthalocyanine blue, and isoindolineone red; and the fillers are selected from one or a combination of precipitated barium sulfate and calcium carbonate.

[0020] Furthermore, in component B, based on a total weight of 100 parts by weight, the weight parts of each component are as follows: 50-65 parts by weight of curing agent, preferably 55-65 parts by weight; The solvent is 35-50 parts by weight, preferably 35-45 parts by weight.

[0021] Preferably, the curing agent is selected from isocyanate curing agents, more preferably from hydrophilically modified polyisocyanate trimers, such as Bayhydur XP2487 / 1, XP2655, Ultra 304 or a combination thereof; the solvent is selected from organic solvents, more preferably from alcohol ether organic solvents, such as propylene glycol methyl ether acetate, propylene glycol diacetate, dipropylene glycol dimethyl ether or a combination thereof.

[0022] Secondly, another objective of this invention is to provide a method for preparing a high and low temperature resistant water-based coating, which is one of the objectives of this invention.

[0023] Specifically, the above preparation method includes the following steps: Component A is obtained by mixing components including organofluorine modified hydroxy acrylic grafted polyurethane emulsion, additives, pigments and fillers; component B is obtained by mixing components including curing agent and solvent; and high and low temperature resistant water-based coating is obtained by mixing components A and B in a preset ratio.

[0024] Finally, a second objective of the present invention is to provide the application of the high and low temperature resistant water-based coatings that are one of the objectives of the present invention.

[0025] Specifically, one of the objectives of this invention is to provide a high- and low-temperature resistant water-based coating suitable for surface protection of train interior parts; preferably for surface protection of train interior parts in extremely cold environments. Preferably, the above coating application process is as follows: First, sand and activate the substrate surface. Clean the surface thoroughly with isopropanol, ethanol, or other suitable solvents and allow it to dry. Before application, stir component A evenly. Then, mix component A and component B in the specified ratio and stir evenly. Add soft water and stir thoroughly again until the viscosity of the Forco 4 cup is 15-30 seconds. Let it stand for 5-20 minutes to mature. To avoid interference from impurities, it is recommended to filter the coating through a 240-mesh or finer screen before spraying. The dry film thickness for a single coat should be controlled at 20-30 μm, and the total film thickness should be controlled at 40-60 μm.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses a specific preparation method to graft organic fluorine monomers and acrylate monomers onto the molecular chain of waterborne polyurethane. The introduction of organic fluorine improves the high-temperature stability and stain resistance of the resin, while hydroxyl acrylic resin improves the weather resistance of the resin. The reaction of hydroxyl groups with isocyanate curing agents increases the crosslinking density of the coating, thereby improving the wear resistance and density of the coating. Waterborne polyurethane imparts good low-temperature flexibility and wear resistance to the resin. Through the combination and synergistic effect of monomers and resin systems, the coating possesses excellent comprehensive performance.

[0027] 2. The water-based polyurethane coating of the present invention is green and environmentally friendly. The coating has excellent high and low temperature resistance, antibacterial and flame retardant properties, and also has good wear resistance, stain resistance, flexibility, adhesion and scratch resistance, which can better meet the performance requirements of paint for train interiors in cold environments. Detailed Implementation

[0028] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0029] In the following examples and comparative examples, the raw materials were all commercially available products.

[0030] Example 1 This embodiment illustrates the preparation of an organofluorine-modified hydroxyl acrylic acid-grafted polyurethane emulsion. The specific preparation method is as follows: 17 parts by weight of polycarbonate diol (PCDL500), 1.3 parts by weight of dimethylolpropionic acid (DMPA), 9 parts by weight of hexamethylene diisocyanate (HDI), and 4.5 parts by weight of propylene glycol methyl ether acetate (PMA) were added to a reactor. 0.0088 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and heated to 75°C for 2.5 h until the NCO content remained constant. Then, 2.2 parts by weight of hydroxyethyl acrylate (HEA) and 0.0022 parts by weight of dibutyltin dilaurate were added for end-capping. The reaction was maintained at this temperature for 2 h, then cooled to 40°C. 0.8 parts by weight of triethylamine were added for neutralization for 25 min. 85 parts by weight of deionized water were added under high-speed stirring to obtain an aqueous polyurethane prepolymer containing carbon-carbon double bonds.

[0031] The prepolymer was heated to 50°C. 10 parts by weight of methyl methacrylate, 30.5 parts by weight of n-butyl acrylate, 15 parts by weight of hydroxyethyl methacrylate, 1.2 parts by weight of methacrylic acid, 11.5 parts by weight of trifluoroethyl methacrylate, and 0.3 parts by weight of tert-dodecyl mercaptan were mixed evenly and simultaneously added dropwise to the prepolymer along with 3.06 parts by weight of an aqueous solution of 10% azobisisobutyramidine hydrochloride. The addition was completed over 2 hours. After reacting at this temperature for 1 hour, 0.34 parts by weight of an aqueous solution of 10% azobisisobutyramidine hydrochloride was added, and the mixture was heated to 60°C and matured for 0.5 hours. The resulting emulsion was cooled to 40°C, and the pH was adjusted to 8 with an appropriate amount of ammonia solution. The mixture was then cooled, stirred evenly, and filtered to obtain organofluorine modified hydroxyl acrylic grafted polyurethane emulsion A.

[0032] Example 2 This embodiment illustrates the preparation of an organofluorine-modified hydroxyl acrylic acid-grafted polyurethane emulsion. The specific preparation method is as follows: 23 parts by weight of polycarbonate diol (PCDL500), 1.7 parts by weight of dimethylolpropionic acid (DMPA), 12 parts by weight of hexamethylene diisocyanate (HDI), and 6 parts by weight of propylene glycol methyl ether acetate (PMA) were added to a reactor. 0.0112 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and heated to 75°C for 2.5 h until the NCO content remained constant. Then, 3 parts by weight of hydroxyethyl acrylate (HEA) and 0.0028 parts by weight of dibutyltin dilaurate were added for end-capping. The reaction was maintained at this temperature for 2 h, then cooled to 40°C. 1.1 parts by weight of triethylamine were added for neutralization for 25 min. 75 parts by weight of deionized water were added under high-speed stirring to obtain an aqueous polyurethane prepolymer containing carbon-carbon double bonds.

[0033] The prepolymer was heated to 50°C. Nine parts by weight of methyl methacrylate, 27 parts by weight of n-butyl acrylate, 13 parts by weight of hydroxyethyl methacrylate, 1 part by weight of methacrylic acid, 10 parts by weight of trifluoroethyl methacrylate, and 0.26 parts by weight of tert-dodecyl mercaptan were mixed evenly and simultaneously added dropwise to the prepolymer along with 2.7 parts by weight of an aqueous solution of 10% azobisisobutyramidine hydrochloride. The addition was completed over 2 hours. After reacting at this temperature for 1 hour, 0.3 parts by weight of an aqueous solution of 10% azobisisobutyramidine hydrochloride was added, and the mixture was heated to 60°C and matured for 0.5 hours. The resulting emulsion was cooled to 40°C, and the pH was adjusted to 8 with an appropriate amount of ammonia solution. The mixture was then cooled, stirred evenly, and filtered to obtain organofluorine modified hydroxyl acrylic grafted polyurethane emulsion B.

[0034] Example 3 This embodiment illustrates the preparation of a high and low temperature resistant water-based coating. The raw material components and their weight parts are as follows: Weigh out 60 parts by weight of organofluorine modified hydroxyl acrylic grafted polyurethane emulsion A, 2 parts by weight of BYK-187 (dispersant), 0.4 parts by weight of BYK-346 (substrate wetting agent), 0.6 parts by weight of BYK-358 (leveling agent), 0.4 parts by weight of BYK-024 (defoamer), 0.4 parts by weight of BENTONE DY CE (antisettling agent), 0.6 parts by weight of COAPUR XS-71 (thickener), 1 part by weight of zinc sulfide (inorganic antibacterial agent), 0.6 parts by weight of isothiazolinone (organic antibacterial agent), 6 parts by weight of zinc phosphate (phosphorus flame retardant), 4 parts by weight of melamine (nitrogen flame retardant), 2 parts by weight of kaolin (silicon flame retardant), 15 parts by weight of titanium dioxide (pigment), and 7 parts by weight of precipitated barium sulfate (filler).

[0035] The specific preparation method is as follows: (1) Mix the organic fluorine modified hydroxy acrylic grafted polyurethane emulsion A, dispersant, substrate wetting agent, leveling agent, anti-settling agent, 3 / 4 of the defoamer and 3 / 4 of the thickener at a speed of 1500 r / min for 5 min. Then add the pigments, fillers, antibacterial agent and flame retardant in the formula amount and mix at a speed of 2000 r / min for 25 min.

[0036] (2) Grind the uniformly dispersed material in step (1) using a basket mill, with the speed controlled at 3200 r / min and the grinding time at 5 hours, until the fineness is ≤30 μm, and then filter out the material.

[0037] (3) Add 1 / 4 of the defoamer and 1 / 4 of the thickener to the material obtained in step (2), and stir thoroughly at a speed of 2000 r / min for 30 min to obtain component A.

[0038] (4) 60 parts by weight of Bayhydur XP2655 and 40 parts by weight of dipropylene glycol dimethyl ether were stirred thoroughly at a speed of 500 r / min for 20 min, and then filtered to obtain component B.

[0039] (5) The water-based coating with high and low temperature resistance, antibacterial and flame retardant properties is prepared by mixing component A and component B at a weight ratio of 6:1.

[0040] Example 4 This embodiment illustrates the preparation of a high and low temperature resistant water-based coating. The raw material components and their weight parts are as follows: Weigh out 60 parts by weight of organofluorine modified hydroxyl acrylic grafted polyurethane emulsion B, 2 parts by weight of BYK-187 (dispersant), 0.4 parts by weight of BYK-346 (substrate wetting agent), 0.6 parts by weight of BYK-358 (leveling agent), 0.4 parts by weight of BYK-024 (defoamer), 0.4 parts by weight of BENTONE DY CE (antisettling agent), 0.6 parts by weight of COAPUR XS-71 (thickener), 1 part by weight of zinc sulfide (inorganic antibacterial agent), 0.6 parts by weight of polyquaternium-73 (organic antibacterial agent), 6 parts by weight of aluminum phosphate (phosphorus flame retardant), 4 parts by weight of melamine polyphosphate (nitrogen flame retardant), 2 parts by weight of fumed silica (silicon flame retardant), 10 parts by weight of phthalocyanine blue (pigment), and 12 parts by weight of precipitated barium sulfate (filler).

[0041] The specific preparation method is as follows: (1) Mix the organic fluorine modified hydroxy acrylic grafted polyurethane emulsion B, dispersant, substrate wetting agent, leveling agent, anti-settling agent, 3 / 4 of the defoamer and 3 / 4 of the thickener at a speed of 1500 r / min for 5 min. Then add the pigments, fillers, antibacterial agent and flame retardant in the formula amount and mix at a speed of 2000 r / min for 25 min.

[0042] (2) Grind the uniformly dispersed material in step (1) using a basket mill, with the speed controlled at 3300 r / min and the grinding time at 5 hours, until the fineness is ≤30 μm, and then filter out the material.

[0043] (3) Add 1 / 4 of the defoamer and 1 / 4 of the thickener to the material obtained in step (2), and stir thoroughly at a speed of 2000 r / min for 30 min to obtain component A.

[0044] (4) 60 parts by weight of Bayhydur XP2655 and 40 parts by weight of dipropylene glycol dimethyl ether were stirred thoroughly at a speed of 500 r / min for 20 min, and then filtered to obtain component B.

[0045] (5) The water-based coating with high and low temperature resistance, antibacterial and flame retardant properties is prepared by mixing component A and component B at a weight ratio of 7:1.

[0046] Comparative Example This comparative example illustrates the preparation of water-based coatings. The raw material components and their weight parts are as follows: Weigh out 60 parts by weight of commercially available water-based hydroxy acrylic emulsion, 2 parts by weight of BYK-187 (dispersant), 0.4 parts by weight of BYK-346 (substrate wetting agent), 0.6 parts by weight of BYK-358 (leveling agent), 0.4 parts by weight of BYK-024 (defoamer), 0.4 parts by weight of BENTONE DY CE (antisettling agent), 0.6 parts by weight of COAPUR XS-71 (thickener), 1 part by weight of zinc sulfide (inorganic antibacterial agent), 0.6 parts by weight of isothiazolinone (organic antibacterial agent), 6 parts by weight of zinc phosphate (phosphorus flame retardant), 4 parts by weight of melamine (nitrogen flame retardant), 2 parts by weight of kaolin (silicon flame retardant), 15 parts by weight of titanium dioxide (pigment), and 7 parts by weight of precipitated barium sulfate (filler).

[0047] The specific preparation method is as follows: (1) Mix commercially available water-based hydroxy acrylic emulsion, dispersant, substrate wetting agent, leveling agent, anti-settling agent, 3 / 4 of defoamer and 3 / 4 of thickener at a speed of 1500 r / min for 5 min. Then add the formulated amount of pigments, fillers, antibacterial agent and flame retardant and mix at a speed of 2000 r / min for 25 min.

[0048] (2) Grind the uniformly dispersed material in step (1) using a basket mill, with the speed controlled at 3000-3500 r / min and the grinding time at 5 hours, until the fineness is ≤30um, and then filter out the material.

[0049] (3) Add 1 / 4 of the defoamer and 1 / 4 of the thickener to the material obtained in step (2), and stir thoroughly at a speed of 2000 r / min for 30 min to obtain component A.

[0050] (4) 60 parts by weight of Bayhydur XP2655 and 40 parts by weight of dipropylene glycol dimethyl ether were stirred thoroughly at a speed of 500 r / min for 20 min, and then filtered to obtain component B.

[0051] (5) A water-based coating is prepared by mixing component A and component B at a weight ratio of 6:1.

[0052] The coatings prepared in the above embodiments and comparative examples were subjected to performance tests. The test methods and results are as follows: First, the surface of the composite material substrate is sanded and activated. The surface is then cleaned with ethanol and allowed to dry. Before application, the two components of the water-based coating (A and B) are mixed thoroughly. Soft water is then added to adjust the viscosity. The viscosity is measured using a Ford cup (Type 4), maintaining a viscosity of 15-30 seconds. The mixture is then allowed to stand for 5-20 minutes (within the application process parameters). After filtering through a 240-mesh or finer screen, the coating is applied. The dry film thickness for a single coat is controlled at 20-30 μm, and the total film thickness is controlled at 40-60 μm. The test results after 7 days of self-drying are shown in Table 1.

[0053] Table 1:

[0054] As shown in Table 1, this application modifies waterborne hydroxy acrylic acid with organic fluorine and polyurethane resin, which significantly improves the coating's high and low temperature resistance and stain resistance. It also has good adhesion, flexibility and environmental performance. In addition, with the synergistic effect of antibacterial agents and flame retardants, the coating is endowed with excellent antibacterial and flame retardant effects. The above coating is suitable for coating the interior of trains in cold environments.

[0055] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A high and low temperature resistant water-based coating, comprising component A and component B, wherein, Component A is formulated from a mixture including an organofluorine-modified hydroxyl acrylic grafted polyurethane emulsion, additives, pigments and fillers. Component B is formulated from components including a curing agent and a solvent; The mass ratio of component A to component B is (5-7):

1.

2. The high and low temperature resistant water-based coating according to claim 1, characterized in that, In component A, based on a total weight of 100 parts by weight, the weight parts of each component are as follows: 60-70 parts by weight, preferably 60-65 parts by weight, of an organofluorine modified hydroxyl acrylic acid grafted polyurethane emulsion. The additive is 13-22 parts by weight, preferably 16-22 parts by weight; The pigment and filler are 15-25 parts by weight, preferably 20-25 parts by weight.

3. The high and low temperature resistant water-based coating according to claim 1, characterized in that, The preparation method of the organofluorine modified hydroxyl acrylic grafted polyurethane emulsion includes the following steps: Step 1: Mix the components including polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, and propylene glycol methyl ether acetate, and react them under the action of a catalyst to obtain a prepolymer with NCO end groups; then add hydroxyethyl acrylate and a catalyst to react and obtain an aqueous polyurethane prepolymer containing carbon-carbon double bonds. Step 2: Add methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, tert-dodecyl mercaptan, and azobisisobutyramidine hydrochloride aqueous solution to the waterborne polyurethane prepolymer containing carbon-carbon double bonds, react, cool, adjust pH, filter and discharge to obtain organofluorine modified hydroxyacrylic acid grafted polyurethane emulsion.

4. The high and low temperature resistant water-based coating according to claim 3, characterized in that, Step one includes the following steps: The components including polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, propylene glycol methyl ether acetate, and catalyst are mixed and heated to 70-80℃ for 2-3 hours to obtain a prepolymer with NCO end groups. Then, hydroxyethyl acrylate and catalyst are added and the reaction is maintained at a high temperature for 1-2 hours. After cooling to 40-50℃, triethylamine is added and reacted for 20-30 minutes. Deionized water is then added under high-speed stirring to obtain an aqueous polyurethane prepolymer containing carbon-carbon double bonds. Preferably, the mass ratio of polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, and hydroxyethyl acrylate is (55-65):(4-8):(20-32):(6-10). Preferably, the mass of propylene glycol methyl ether acetate added is 10%-20% of the total mass of the monomers, based on the total mass of polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, and hydroxyethyl acrylate monomers. Preferably, the catalyst is selected from dibutyltin dilaurate; Preferably, the added catalyst accounts for 0.02%-0.05% of the total mass of polycarbonate diol, dimethylolpropionic acid, hexamethylene diisocyanate, and hydroxyethyl acrylate monomer; and the first application of the catalyst accounts for 70%-90% of its total mass, while the second application accounts for 10%-30% of its total mass. Preferably, the mass of the triethylamine is 60%-80% of the mass of dimethylolpropionic acid.

5. The high and low temperature resistant water-based coating according to claim 3, characterized in that, Step two includes the following steps: First, the aqueous polyurethane prepolymer containing carbon-carbon double bonds is heated to 50-60℃. Then, a mixture of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, tert-dodecyl mercaptan, and an aqueous solution of azobisisobutyramidine hydrochloride are simultaneously added dropwise to the aqueous polyurethane prepolymer over 2-3 hours. After reacting at this temperature for 1-2 hours, an aqueous solution of azobisisobutyramidine hydrochloride is added. The mixture is then heated to 60-70℃ and matured for 0.5-1 hour. The temperature is then lowered to 40-50℃, the pH is adjusted to 7.5-8.5, and the mixture is filtered to obtain the organofluorine modified hydroxyl acrylic acid grafted polyurethane emulsion. Preferably, the mass ratio of methyl methacrylate to n-butyl acrylate is (20-30):(70-80); preferably, based on the total mass of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, and tert-dodecyl mercaptan, the mass of hydroxyethyl methacrylate is 15%-25% of the total mass of the monomers. Preferably, the mass of the methacrylic acid is 1%-5% of the total mass of the monomers, based on the total mass of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, and tert-dodecyl mercaptan. Preferably, the mass of the trifluoroethyl methacrylate is 10%-20% of the total mass of the monomers, based on the total mass of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, and tert-dodecyl mercaptan. Preferably, the mass of the tert-dodecyl mercaptan, based on the total mass of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, and tert-dodecyl mercaptan, is 0.2%-0.6% of the total mass of the reactants. Preferably, the mass of the aqueous solution of azobisisobutyramidine hydrochloride is 2%-6% of the total mass of the reactants, based on the total mass of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, methacrylic acid, trifluoroethyl methacrylate, and tert-dodecyl mercaptan. Preferably, the mass concentration of the azobisisobutyramidine hydrochloride aqueous solution is 10%-20%, and the first application is 80%-90% of its total mass, while the second application is 10%-20% of its total mass.

6. The high and low temperature resistant water-based coating according to claim 3, characterized in that, The ratio of the total mass of the reactants in step one to the total mass of the reactants in step two is (30-40):(60-70).

7. The high and low temperature resistant water-based coating according to claim 1, characterized in that, The additives are selected from one or a combination of dispersants, substrate wetting agents, leveling agents, defoamers, antisettling agents, thickeners, antibacterial agents, and flame retardants; and / or, The pigments and fillers are selected from one or a combination of pigments and fillers; Preferably, The dispersant is selected from polycarboxylate dispersants; and / or, The substrate wetting agent is selected from polyether-modified polydimethylsiloxane solution; and / or, The leveling agent is selected from acrylate leveling agents; and / or, The defoamer is selected from silicone-based defoamers; and / or, The anti-settling agent is selected from lithium montmorillonite clay; and / or... The thickener is selected from nonionic waterborne polyurethane; and / or, The antibacterial agent is selected from one or a combination of silver ion compounds, zinc ion compounds, polyquaternium-73, and isothiazolinones; and / or, The flame retardant is selected from one or a combination of aluminum phosphate, zinc phosphate, melamine, melamine polyphosphate, fumed silica, and kaolin; and / or, The pigment is selected from inorganic pigments and / or organic pigments; the inorganic pigment is selected from one or a combination of titanium dioxide, cobalt blue, carbon black, iron yellow, and iron oxide red; the organic pigment is one or a combination of permanent yellow, phthalocyanine blue, and isoindolineone red; and / or, The filler is selected from one or a combination of precipitated barium sulfate and calcium carbonate.

8. The high and low temperature resistant water-based coating according to claim 1, characterized in that, In component B, based on a total weight of 100 parts by weight, the weight parts of each component are as follows: 50-65 parts by weight of curing agent, preferably 55-65 parts by weight; The solvent is 35-50 parts by weight, preferably 35-45 parts by weight; Preferably, The curing agent is selected from isocyanate curing agents, and more preferably from self-hydrophilically modified polyisocyanate trimers; The solvent is selected from organic solvents, more preferably from alcohol ether organic solvents.

9. A method for preparing a high and low temperature resistant water-based coating according to any one of claims 1-8, comprising the following steps: The components, including organofluorine modified hydroxy acrylic grafted polyurethane emulsion, additives, pigments and fillers, are mixed to obtain component A; The components, including the curing agent and the solvent, are mixed to obtain component B; component A and component B are mixed in a preset ratio to obtain the high and low temperature resistant water-based coating.

10. The application of the high and low temperature resistant water-based coating according to any one of claims 1-9, for surface protection of train interior parts; preferably for surface protection of train interior parts in cold environments.

Images