High filling super-solidified intermediate coating paint in rail transit field

Abstract

The present application relates to the field of paint technology, and disclose a kind of high filling super-solidification intermediate coating in rail transit field, and intermediate coating composition includes nanometer titanium dioxide base end hydroxyl hyperbranched polyester, medium molecular weight acrylic resin, blocked high functionality polyisocyanate crosslinking agent, dispersant etc..The super-solidification system of nanometer titanium dioxide base end hydroxyl hyperbranched polyester and isocyanate crosslinking agent used in the present application obtains coating crosslinking density, and toughness is good, significantly improves the resistance of coating resistance, such as water resistance, moisture resistance, achieves higher level of protection effect to putty, especially water resistance can reach 48h, meanwhile, the intermediate coating of the present application is quick-drying, easy to construction, has higher gloss and fullness, leveling property, matched high-performance putty and finish, can be widely used in rail transit field, and realizes life cycle performance guarantee.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a high-filling super-cured intermediate coating for rail transit. BACKGROUND

[0002] In the field of rail transit, intermediate coating is a key link in construction. The intermediate coating is a coating between the primer / filler and the topcoat. Its main function is to fill the fine defects on the surface of the primer / filler, increase the thickness of the coating to improve the overall protection and decoration performance, enhance the adhesion of the primer / filler and the topcoat, make the topcoat smoother, and improve the wear resistance, corrosion resistance, weather resistance and other properties of the coating, thereby prolonging the service life of rail transit equipment. Based on the development needs of the rail transit industry, the performance requirements of the intermediate coating have also increased. The super-cured intermediate coating of the present application makes a great contribution to the concept of protecting the entire life cycle of the rail transit industry. SUMMARY

[0003] (I) Technical problems solved

[0004] To overcome the shortcomings of the prior art, the present application provides a high-filling super-cured intermediate coating for rail transit, which is matched with a putty and a topcoat, and is applied to the rail transit industry to play a high-filling role on the surface of the putty, enhance the adhesion of the coating, and improve the resistance of the coating.

[0005] (II) Technical solutions

[0006] A high-filling super-cured intermediate coating for rail transit, wherein the high-filling super-cured intermediate coating is mixed from a main agent and a curing agent, and the mass ratio of the main agent to the curing agent is 90.8-93:7-9.2.

[0007] The intermediate coating is a two-component coating.

[0008] The main agent comprises a polymer resin, an additive, a filler, and a cosolvent.

[0009] Preferably, the polymer resin comprises a medium molecular weight acrylic resin polymer, the amount of which is 14.5-18.2% of the total mass of the coating, and the monomer composition of the medium molecular weight acrylic resin polymer comprises any of styrene, acrylic acid, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, isobornyl methacrylate, glycidyl tertiocarbonate, glycidyl methacrylate, and glycidyl acrylate.

[0010] Preferably, the polymer resin comprises a nano-titanium dioxide-based hydroxyl-terminated hyperbranched polyester, the amount of which is 9.2-12.1% of the total mass of the coating, and the preparation method comprises the following steps:

[0011] (1) magnesium powder is added to tetrahydrofuran solvent, stirred and heated for 20-30 min, slowly heated to 55-65℃, then p-chlorostyrene tetrahydrofuran solution is added, stirred and reacted for 2-3 h, the temperature is controlled at 10-20℃, then cyanuric chloride tetrahydrofuran solution is added, the molar ratio of magnesium powder, p-chlorostyrene and cyanuric chloride is 1-1.2:1:0.9-1.2, stirred and reacted for 3-5 h, then toluene and 12% hydrochloric acid aqueous solution are added, the organic phase is separated, washed with deionized water, and concentrated to obtain 2-chloro-4,6-diphenylstyryl-1,3,5-triazine, in this reaction, 2-chloro-4,6-diphenylstyryl-1,3,5-triazine is obtained by Grignard reaction with magnesium powder, p-chlorostyrene and cyanuric chloride as raw materials, that is, a styrene structure is introduced into the product, which not only contains a benzene ring structure with ultraviolet resistance, but also has a double bond structure, which is an active group for the next reaction, and the reaction route is as follows:

[0012] ;

[0013] (2) 2-chloro-4,6-diphenylstyryl-1,3,5-triazine and resorcinol are added to chlorobenzene solvent, stirred and dispersed, then aluminum chloride is added, the molar ratio of 2-chloro-4,6-diphenylstyryl-1,3,5-triazine, resorcinol and aluminum chloride is 1:0.8-1:0.05-0.08, heated and stirred to dissolve, the temperature is controlled at 70-80℃, reacted for 5-8 h, after the reaction is completed, water vapor is distilled, cooled, filtered and dried to obtain 2-(2',4'-hydroxyphenyl)-4,6-diphenylstyryl-1,3,5-triazine, in this reaction, 2-chloro-4,6-diphenylstyryl-1,3,5-triazine reacts with resorcinol by Friedel-Crafts reaction under the action of aluminum chloride to obtain 2-(2',4'-hydroxyphenyl)-4,6-diphenylstyryl-1,3,5-triazine, the product obtained by this reaction contains triazine ultraviolet absorption structure, which can convert the absorbed ultraviolet energy into harmless energy by opening and closing the intramolecular hydrogen bond, and the reaction route is as follows:

[0014] ;

[0015] (3) adding sodium hydroxide into N,N-dimethylformamide solvent, heating and stirring to dissolve, then adding 2-(2',4'-hydroxyphenyl)-4,6-diphenylvinyl-1,3,5-triazine into the solution, heating to 65-75°C, then adding 2-bromoethyl isocyanate into the solution, the molar ratio of sodium hydroxide, 2-(2',4'-hydroxyphenyl)-4,6-diphenylvinyl-1,3,5-triazine and 2-bromoethyl isocyanate being 1-1.4:1:1-1.2, after the reaction, cooling, vacuum filtration, dissolving in dichloromethane, recrystallization to obtain compound A, in this reaction, compound A is obtained by substitution reaction of 2-(2',4'-hydroxyphenyl)-4,6-diphenylvinyl-1,3,5-triazine and 2-bromoethyl isocyanate, and an isocyanate active structure is introduced into compound A for the next reaction, and the reaction route is as follows:

[0016] ;

[0017] (4) adding nanometer titanium dioxide into toluene solvent, ultrasonic dispersion for 5 min, then adding compound A and dibutyltin dilaurate into the solution, the molar ratio of nanometer titanium dioxide and compound A being 1:4-6, continuing ultrasonic dispersion for 10 min, reaction under nitrogen protection at 80-90°C for 5-7 h, after the reaction, filtration, toluene extraction, drying to obtain compound B, in this reaction, nanometer titanium dioxide is obtained by in-situ polymerization of hydroxyl groups contained on the surface of nanometer titanium dioxide and isocyanate groups in compound A, at this time, compound A can not only disperse easily-aggregated nanometer titanium dioxide and improve the comprehensive performance of nanometer titanium dioxide, but also can improve the ultraviolet resistance of the material in cooperation with nanometer titanium dioxide, and the reaction route is as follows:

[0018] , wherein is nanometer titanium dioxide;

[0019] (5) adding diethanolamine into ethanol solvent, introducing nitrogen, heating to 65-75°C, then adding compound B into the solution, the molar ratio of diethanolamine and compound B being 2-2.4:1, reaction for 20-28 h, after the reaction, distillation under reduced pressure, washing with deionized water, drying to obtain nanometer titanium dioxide-based tetrahydroxytriazine, in this reaction, nanometer titanium dioxide-based tetrahydroxytriazine is obtained by Michael addition reaction of the alkenyl structure contained in compound B and diethanolamine, that is, a tetrahydroxy structure is introduced into the product for the next reaction, and the reaction route is as follows:

[0020] ;

[0021] (6) 2,2-dihydroxypropionic acid, nano-titanium dioxide-based tetrahydroxy triazine is added to N,N-dimethylformamide solvent, stirred and dispersed, and then N,N'-dicyclohexyl carbodiimide is added, wherein the molar ratio of 2,2-dihydroxypropionic acid, nano-titanium dioxide-based tetrahydroxy triazine, N,N'-dicyclohexyl carbodiimide is 12-12.5:1:12-13, and the reaction is carried out in an ice water bath for 3-5 h. After the reaction is completed, centrifugation, deionized water washing, and drying are performed to obtain nano-titanium dioxide-based hydroxyl-terminated hyperbranched polyester. In this reaction, nano-titanium dioxide-based tetrahydroxy triazine is used as the core molecule, 2,2-dihydroxypropionic acid is used as the polymerization monomer, and N,N'-dicyclohexyl carbodiimide is used as the dehydrating agent. A one-step method is used to synthesize a second-generation nano-titanium dioxide-based hydroxyl-terminated hyperbranched polyester with a regular structure. The molecular chain is not prone to entanglement, and the end contains active hydroxyl structures, so that secondary reactions continue to occur during the preparation of the coating, the crosslinking density of the coating is improved, and the comprehensive performance of the coating is improved.

[0022] Preferably, the curing agent is a blocked high-functionality polyisocyanate crosslinker part containing a high-functionality macromolecule releasing isocyanate groups after deblocking. The functional degree of the curing agent after deblocking is 2-9, and the deblocking temperature is 90-120℃.

[0023] Preferably, the cosolvent is any one of ethanol, butanol, isopropyl alcohol, isobutyl alcohol, xylene, toluene, ethyl acetate, butyl acetate, methyl formate, methyl acetate, and butyl benzoate, and the amount thereof is 18-30%.

[0024] Preferably, the additive is a wetting agent, a defoaming agent, a dispersing agent, an adhesion promoter, and a anti-settling agent. The adhesion promoter is any one of γ-aminopropyl triethoxysilane (KH-550), γ-glycidyl ether propyltrimethoxysilane (KH-560), γ-methacryloyloxypropyltrimethoxysilane (KH-570), vinyltrimethoxysilane (A-171), and γ-mercaptopropyltrimethoxysilane (KH-590).

[0025] Preferably, the filler is titanium white, heavy calcium, and barium sulfate.

[0026] Further preferably, the high-filling super-cured intermediate coating for the rail transit field is used to improve the resistance of the coating, enhance the adhesion, and adjust the leveling property. The application fields include, but are not limited to, the rail transit field and the industrial corrosion prevention field.

[0027] Preferably, the intermediate coating can be coated on the substrate by an electrostatic spraying method and can be cured under heating conditions. The curing temperature is 100-120℃.

[0028] (Three) Beneficial technical effects

[0029] The nanometer titanium dioxide based end hydroxyl hyperbranched polyester used in the application, wherein the nanometer titanium dioxide contains hydroxyl structure on the surface, and is easy to secondary aggregate, which is not conducive to its dispersion in the material, and affects the comprehensive performance of the material, the isocyanate group in the compound A is used to disperse the nanometer titanium dioxide, on the one hand, the dispersion effect of the nanometer titanium dioxide can be improved, on the other hand, the nanometer titanium dioxide can form an organic-inorganic synergistic anti-ultraviolet structure with the triazine structure and the benzene ring structure, and the anti-ultraviolet ability of the material can be improved by introducing the structure into the coating, thereby prolonging the service life of the coating, and on the other hand, the nanometer titanium dioxide can be used as a stress concentration point in the coating material, and the mechanical properties of the coating can be improved by cooperating with the branched structure.

[0030] The nanometer titanium dioxide based end hydroxyl hyperbranched polyester used in the application contains a large number of branched structures, on the one hand, the branched structures can be crosslinked with each other to increase the compactness of the material and improve the performance of the coating, on the other hand, when the nanometer titanium dioxide based end hydroxyl hyperbranched polyester is added to the coating, the isocyanate groups in the multifunctional isocyanate curing agent further react to produce secondary crosslinking, so that the coating has higher crosslinking density, that is, higher compactness, which can further enhance the performance of the coating, and a large number of polar groups such as urethane and hydroxyl can produce hydrogen bonds with the polar groups on the surface of the substrate material, thereby further improving the adhesion and mechanical properties, which far exceeds the industry standard in practical application, and has a long service life.

[0031] The medium molecular weight acrylic polymer with a specific monomer structure introduced in the application can perform molecular-level filling on the surface of the putty during the crosslinking process, and can improve the appearance and leveling effect of the intermediate coating, and the adhesion of the coating can be further enhanced due to better filling effect (promoting the filling of the coating on the pores and / or defects of the putty). BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a schematic diagram of the medium molecular weight acrylic polymer filling coating. DETAILED DESCRIPTION

[0033] As used herein, unless otherwise expressly indicated, it is to be understood that the numerical values, ranges, amounts or percentages expressed in the specification and claims using the terms "about," "substantially," or "approximately" can be varied in all instances by the term "approximately," even if the term is not expressly shown. Therefore, unless expressly stated to the contrary, or otherwise readily apparent from the context, it is intended that all amount values or ranges set forth in the description and claims are approximate.

[0034] Dispersants, wetting agents, anti-settling agents were purchased from DeGussa;

[0035] Defoamers were purchased from BYK;

[0036] Titanium dioxide, talc, barium sulfate were purchased from DuPont;

[0037] Solvents were purchased from Dow Chemical;

[0038] Curing agents were purchased from Wanhua Chemical;

[0039] Adhesion promoters were γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, all purchased from Momentive.

[0040] Medium molecular weight acrylic resin polymer 1, hereinafter referred to as acrylic resin 1, medium molecular weight acrylic resin polymer 2, hereinafter referred to as acrylic resin 2.

[0041] Acrylic resin 1 is a medium molecular weight acrylic resin polymer with a molecular weight of 80000-150000, and its monomer composition is a combination of styrene (40% of the total monomer mass), methyl methacrylate (30% of the total monomer mass), acrylic acid (10% of the total monomer mass), and hydroxypropyl methacrylate (10% of the total monomer mass).

[0042] Acrylic resin 2 is a medium molecular weight acrylic resin polymer with a molecular weight of 100000-500000, and its monomer composition is a combination of methyl methacrylate (35% of the total monomer mass), hydroxypropyl methacrylate (25% of the total monomer mass), isobornyl methacrylate (10% of the total monomer mass), acrylic acid (10% of the total monomer mass), glycidyl versatate (5% of the total monomer mass), glycidyl methacrylate (5% of the total monomer mass), and glycidyl acrylate (10% of the total monomer mass).

[0043] Example 1

[0044] (1) 0.4 mol of magnesium powder was added to a tetrahydrofuran solvent, stirred and heated for 30 min, slowly warmed to 65°C, and then 0.4 mol of p-chlorostyrene in tetrahydrofuran solution was added, stirred and reacted for 3 h, the temperature was controlled at 10°C, and then 0.36 mol of cyanuric chloride in tetrahydrofuran solution was added, stirred and reacted for 5 h. After the reaction was completed, toluene and 12% hydrochloric acid aqueous solution were added, stirred and mixed uniformly, the organic phase was separated, washed with deionized water, and the organic phase was concentrated to obtain 2-chloro-4,6-diphenylstyryl-1,3,5-triazine.

[0045] (2) 0.5 mol of 2-chloro-4,6-diphenylvinyl-1,3,5-triazine and 0.5 mol of resorcinol were added to a chlorobenzene solvent, stirred and dispersed, 0.025 mol of aluminum chloride was added thereto, heated and stirred to dissolve, the temperature was controlled at 80°C, and the reaction was performed for 5 hours. After the reaction was completed, water vapor was distilled off, cooled, filtered, and dried to obtain 2-(2',4'-hydroxyphenyl)-4,6-diphenylvinyl-1,3,5-triazine.

[0046] (3) 0.5 mol of sodium hydroxide was added to an N,N-dimethylformamide solvent, heated and stirred to dissolve, 0.5 mol of 2-(2',4'-hydroxyphenyl)-4,6-diphenylvinyl-1,3,5-triazine was added thereto, the temperature was raised to 65°C, 0.6 mol of 2-bromoethyl isocyanate was added thereto, and the reaction was performed for 60 minutes. After the reaction was completed, cooled, vacuum filtered, dissolved in dichloromethane, and recrystallized to obtain Compound A.

[0047] (4) 0.08 mol of nano titanium dioxide was added to a toluene solvent, ultrasonically dispersed for 5 minutes, 0.48 mol of Compound A and 3 drops of dibutyltin dilaurate were added thereto, ultrasonically dispersed for 10 minutes, and the reaction was performed for 7 hours at 90°C under nitrogen. After the reaction was completed, filtered, extracted with toluene, and dried to obtain Compound B.

[0048] (5) 0.4 mol of diethanolamine was added to an ethanol solvent, nitrogen was introduced, the temperature was raised to 75°C, 0.2 mol of Compound B was added thereto, and the reaction was performed for 20 hours. After the reaction was completed, distilled under reduced pressure, washed with deionized water, and dried to obtain nano titanium dioxide-based tetrahydroxytriazine.

[0049] (6) 1.25 mol of 2,2-dihydroxypropionic acid and 0.1 mol of nano titanium dioxide-based tetrahydroxytriazine were added to an N,N-dimethylformamide solvent, stirred and dispersed, 1.2 mol of N,N'-dicyclohexyl carbodiimide was added thereto, and the reaction was performed for 3 hours in an ice water bath. After the reaction was completed, centrifuged, washed with deionized water, and dried to obtain nano titanium dioxide-based hydroxyl-terminated hyperbranched polyester.

[0050] Example 2

[0051] (1) 0.48 mol of magnesium powder was added to a tetrahydrofuran solvent, stirred and heated for 20 min, slowly warmed to 55°C, and then 0.4 mol of p-chlorostyrene in a tetrahydrofuran solution was added thereto, stirred and reacted for 2 h while controlling the temperature at 20°C, 0.48 mol of cyanuric chloride in a tetrahydrofuran solution was added thereto, stirred and reacted for 3 h, after the reaction was completed, toluene and 12% by mass of hydrochloric acid aqueous solution were added thereto, stirred and mixed uniformly, the organic phase was separated, washed with deionized water, and the organic phase was concentrated to obtain 2-chloro-4,6-bistyryl-1,3,5-triazine.

[0052] (2) 0.5 mol of 2-chloro-4,6-bistyryl-1,3,5-triazine and 0.4 mol of resorcinol were added to a chlorobenzene solvent, stirred and dispersed, 0.04 mol of aluminum chloride was added thereto, stirred and dissolved while heating, the temperature was controlled at 70°C, and reacted for 8 h, after the reaction was completed, water vapor distillation was performed, cooled, filtered, and dried to obtain 2-(2',4'-hydroxyphenyl)-4,6-bistyryl-1,3,5-triazine.

[0053] (3) 0.7 mol of sodium hydroxide was added to an N,N-dimethylformamide solvent, stirred and dissolved while heating, 0.5 mol of 2-(2',4'-hydroxyphenyl)-4,6-bistyryl-1,3,5-triazine was added thereto, warmed to 75°C, and 0.5 mol of 2-bromoethyl isocyanate was added thereto and reacted for 40 min, after the reaction was completed, cooled, vacuum filtered, dissolved in dichloromethane, and recrystallized to obtain compound A.

[0054] (4) 0.08 mol of nano titanium dioxide was added to a toluene solvent, ultrasonically dispersed for 5 min, 0.32 mol of compound A and 5 drops of dibutyltin dilaurate were added thereto, ultrasonically dispersed for 10 min, and reacted for 5 h at 80°C under nitrogen protection, after the reaction was completed, filtered, extracted with toluene, and dried to obtain compound B.

[0055] (5) 0.48 mol of diethanolamine was added to an ethanol solvent, nitrogen was introduced, warmed to 65°C, and 0.2 mol of compound B was added thereto and reacted for 28 h, after the reaction was completed, distilled under reduced pressure, washed with deionized water, and dried to obtain nano titanium dioxide-based tetrahydroxytriazine.

[0056] (6) 1.2 mol of 2,2-dihydroxypropionic acid and 0.1 mol of nano titanium dioxide-based tetrahydroxytriazine were added to an N,N-dimethylformamide solvent, stirred and dispersed, 1.3 mol of N,N'-dicyclohexyl carbodiimide was added thereto, and reacted for 5 h in an ice water bath, after the reaction was completed, centrifuged, washed with deionized water, and dried to obtain nano titanium dioxide-based hydroxyl-terminated hyperbranched polyester.

[0057] Examples 3-5:

[0058] Examples 3-5 of the coating composition according to the present application were prepared by mixing the raw materials uniformly according to the following weight part formulation sequence.

[0059] Material Name Example 3 Example 4 Example 5 Nano-titania-based end-hydroxyl hyperbranched polyester of Example 1 22.9 24.9 26.9 Acrylic Resin 1 19.6 19.6 19.6 Acrylic Resin 2 20 20 20 Dispersant 1 1 1 Defoamer 0.3 0.3 0.3 Titanium Dioxide 48 48 48 Talc 17 17 17 Barium Sulfate 20 20 20 Wetting Agent 0.5 0.5 0.5 Isobutyl Alcohol Solvent 40 40 40 Ethyl Acetate Solvent 40 40 40 Anti-settling Agent 6 6 6 Butyl Benzoate Solvent 2.7 2.7 2.7 Curing Agent 20 20 20

[0060] Examples 6-7:

[0061] Examples 6-7 of the coating composition according to the present application were prepared by mixing the raw materials uniformly according to the following weight part formulation sequence, by parallel experiment, comparative example 4.

[0062] Material Name Example 4 Example 6 Example 7 Nano-titania-based end-hydroxyl hyperbranched polyester of Example 1 24.9 24.9 24.9 Acrylic Resin 1 19.6 17.6 21.6 Acrylic Resin 2 20 20 20 Dispersant 1 1 1 Defoamer 0.3 0.3 0.3 Titanium Dioxide 48 48 48 Talc 17 17 17 Barium Sulfate 20 20 20 Wetting Agent 0.5 0.5 0.5 Isobutyl Alcohol Solvent 40 40 40 Ethyl Acetate Solvent 40 40 40 Anti-settling Agent 6 6 6 Butyl Benzoate Solvent 2.7 2.7 2.7 Curing Agent 20 20 20

[0063] Examples 8-9:

[0064] Examples 8-9 of the coating composition according to the present application were prepared by mixing the raw materials uniformly according to the following weight part formulation sequence, by parallel experiment, comparative example 4.

[0065] Material Name Example 4 Example 8 Example 9 Nano-titania-based end-hydroxyl hyperbranched polyester of Example 1 24.9 24.9 24.9 Acrylic Resin 1 19.6 19.6 19.6 Acrylic Resin 2 20 20 20 Dispersant 1 1 1 Defoamer 0.3 0.3 0.3 Titanium Dioxide 48 48 48 Talc 17 17 17 Barium Sulfate 20 20 20 Wetting Agent 0.5 0.5 0.5 Isobutyl Alcohol Solvent 40 40 40 Ethyl Acetate Solvent 40 40 40 Anti-settling Agent 6 6 6 Butyl Benzoate Solvent 3 2.7 2.7 2.7 Curing Agent 20 18 22

[0066] Examples 10-14:

[0067] Examples 10-14 of the coating composition according to the present application were prepared by mixing the raw materials uniformly according to the following weight part formulation sequence.

[0068] Material Name Example 10 Example 11 Example 12 Example 13 Example 14 Nano-titania-based end-hydroxyl hyperbranched polyester of Example 2 24.9 24.9 24.9 24.9 24.9 Acrylic Resin 1 19.6 19.6 19.6 19.6 19.6 Acrylic Resin 2 20 20 20 20 20 Dispersant 1 1 1 1 1 Defoamer 0.3 0.3 0.3 0.3 0.3 Titanium Dioxide 48 48 48 48 48 Talc 17 17 17 17 17 Barium Sulfate 20 20 20 20 20 Wetting Agent 0.5 0.5 0.5 0.5 0.5 Isobutyl Alcohol Solvent 40 40 40 40 40 Ethyl Acetate Solvent 40 40 40 40 40 Anti-settling Agent 6 6 6 6 6 Butyl Benzoate Solvent 2.7 2.7 2.7 2.7 2.7 γ-Aminopropyl Triethoxysilane 2 0 0 0 0 γ-Glycidoxypropyl Trimethoxysilane 0 2 0 0 0 γ-Methacryloyloxypropyl Trimethoxysilane 0 0 2 0 0 Vinyl Trimethoxysilane 0 0 0 2 0 γ-Mercaptopropyl Trimethoxysilane 0 0 0 0 2 Curing Agent 20 20 20 20 20

[0069] Performance test

[0070] The intermediate coating composition obtained above was coated on the surface of self-made putty, with the following specific parameters: the temperature of the working environment was maintained at 25°C, the humidity was 50-60%; air spray gun was used for spraying; the coating thickness was finally controlled at 50 microns; the sprayed coating was first flash-dried at ambient temperature for 30 min, and then baked at 100°C for 20 min; the cured coating was tested for the following performances.

[0071] 1. Appearance: the appearance of the intermediate coating surface was tested by BYK orange peel instrument, and the operation was specified according to the BYK orange peel instrument operation manual. The long wave Lw, the short wave Sw, and the distinctness of image Doi were mainly recorded.

[0072] 2. Impact resistance test: The test is conducted at 23 ± 2°C and relative humidity 50 ± 5%. The painted test panel is placed flat on an anvil with the paint film facing up. The impact area is at least 15 mm from the edge of the panel and the edge of each impact point is at least 15 mm apart. The weight is fixed at a certain height on the slide tube by the control device. The weight is free to fall on the punch when the control button is pressed. Lift the weight and remove the test panel. Record the height of the weight falling on the test panel. The same test panel is tested three times. Use a 4x magnifying lens to observe and judge whether the paint film has cracks, wrinkles, and peeling, etc.

[0073] 3. Cupping test: The test is conducted at 23 ± 2°C and relative humidity 50 ± 5%. The test panel is fixed between the fixed ring and the stretch punch film without applying additional pressure. The coating side faces the punch, and the hemispherical tip of the punch is just in contact with the uncoated side of the test panel. The hemispherical tip of the punch is pushed towards the test panel at a constant speed of 0.1-0.3 mm / s until the specified depth is reached, i.e. the distance the punch has moved from zero position. Check the coating of the test panel for cracking and separation from the substrate using corrected normal vision or, if necessary, a microscope or 10x magnifying lens.

[0074] 4. Adhesion test: Place the sample on a hard flat surface to prevent any deformation of the sample during the test. Hold the cutting tool so that the blade is perpendicular to the surface of the sample and apply even pressure to the cutting tool. Use suitable spacing guides to make a specified number of cuts at an even cutting rate. Make the same number of parallel cuts to form a grid pattern at an angle to the original cuts. Gently sweep a soft brush along each diagonal of the grid pattern a few times backwards and then forwards. Cut a length of about 75 mm of adhesive tape and place the center point of the tape over the grid in a direction parallel to one set of cuts. Hold the free end of the tape and tear it away at an angle as close to 60° as possible within 0.5-1 s. Carefully examine the cut area of the test coating using a visual magnifying lens and rate the test results.

[0075] 5. Solvent wipe resistance test: The solvent resistance of the sample is tested by a Taber 5750 linear abrasion tester. Select a 120 mm long wiping area on the surface of the sample. The test end of the abrasion tester is fixed with butanone soaked degreasing cotton (no liquid droplets should drop when squeezed by hand). Visually inspect the coating film in the middle 8 cm area of the test panel under scattered daylight to observe whether the coating film is damaged to expose the substrate.

[0076] 6. Water resistance test: refer to GB / T 5209 standard, immerse the sample board in a constant temperature water tank at 40°C, take it out every 2h, wipe the surface of the sample board, and observe the appearance defects such as blistering, discoloration, and blooming. Add enough amount of required deionized water into the tank, keep the sample board three-quarters immersed in water, and then start the water circulation or aeration in the tank. Adjust the water temperature to 40±1°C, when the intermediate inspection is carried out during the test period, take the sample board out of the tank, absorb the water marks with filter paper, and check the damage immediately, and then put it back into the tank. Take the sample board out of the tank at the end of the specified period, absorb the water marks with filter paper, and check the damage.

[0077] The performance test results of examples 3-8 are as follows:

[0078] Test Item Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Appearance - Lw 22.8 23.4 23.8 25.5 22.0 23.8 Appearance - Sw 19.6 20.2 20.7 22.9 19.9 20.7 Doi 88.6 88.2 87.2 85.7 89.2 86.9 Impact Resistance 40 70 80 45 90 70 Cupping Test 3.5 4.5 5 4 5 5 Cross-hatch Test 2 3 5 3 4 2 Solvent Wipe Resistance 50 40 30 40 30 20 Water Resistance 48 48 48 48 24 24

[0079] The performance test results of examples 9-14 are as follows:

[0080] Test Item Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Appearance - Lw 23.9 22.9 23.1 23.3 23.8 23.4 Appearance - Sw 20.7 20.2 20.4 20.5 20.5 20.6 Doi 88.2 88.7 88.5 88.6 88.2 88.5 Impact Resistance 90 70 70 70 70 70 Cupping Test 4.5 4.5 4.5 4.5 4.5 4.5 Cross-hatch Test 3 3 1 1 1 1 Solvent Wipe Resistance 30 30 30 30 30 30 Water Resistance 48 48 48 48 48 48

[0081] From the table, it can be seen that with the increase of the amount of nanometer titanium dioxide-based end hydroxyl hyperbranched polyester, the comprehensive performance increases, and with the increase of the amount of curing agent, the compactness is further increased, and the comprehensive performance increases. For the mid-coat paint involved in the protection of the present patent, the main role is to link the putty and the topcoat, and through the appearance performance of the mid-coat paint, the filling effect of the mid-coat on the putty layer can be seen. In the examples listed in the present patent, the comprehensive performance of the appearance test results is good. The present application has excellent filling performance.

[0082] Although specific aspects of the application have been explained and described, it is obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the application. Therefore, the appended claims are intended to cover all such changes and modifications falling within the scope of the present application.

Claims

1. A high-filled super-cured mid-coat paint in the field of rail transportation, characterized in that, The high filling super-cured intermediate coating is mixed by a main agent and a curing agent, and the mass ratio is 90.8-93:7-9.2; The intermediate coating is a two-component coating; The main agent comprises a polymer resin, an additive, a filler and a cosolvent; The polymer resin comprises a medium molecular weight acrylic resin polymer, and the amount of the medium molecular weight acrylic resin polymer is 14.5-18.2% of the total mass of the coating; the monomers of the medium molecular weight acrylic resin polymer are any of styrene, acrylic acid, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, isobornyl methacrylate, glycidyl versatate, glycidyl methacrylate and glycidyl acrylate; The polymer resin comprises a nano-titanium dioxide-based terminal hydroxyl hyperbranched polyester, and the amount of the nano-titanium dioxide-based terminal hydroxyl hyperbranched polyester is 9.2-12.1% of the total mass of the coating; the preparation method comprises the following steps: (1) magnesium powder is added into a tetrahydrofuran solvent, and stirred and heated for 20-30 min; the temperature is slowly increased to 55-65 ℃; then p-chlorostyrene tetrahydrofuran solution is added into the mixture, and stirred and reacted for 2-3 h, with the temperature being controlled to be 10-20 ℃; then cyanuric chloride tetrahydrofuran solution is added into the mixture, and stirred and reacted for 3-5 h; after the reaction is completed, toluene and hydrochloric acid aqueous solution with a mass fraction of 12% are added into the mixture; the organic phase is separated; the organic phase is washed with deionized water; and the organic phase is concentrated to obtain 2-chloro-4,6-bisstyryl-1,3,5-triazine; (2) 2-chloro-4,6-bisstyryl-1,3,5-triazine and resorcinol are added into a chlorobenzene solvent, and stirred and dispersed; then aluminum chloride is added into the mixture, and the molar ratio of 2-chloro-4,6-bisstyryl-1,3,5-triazine, resorcinol and aluminum chloride is 1:0.8-1:0.05-0.08; the mixture is heated and stirred to be dissolved, and the temperature is controlled to be 70-80 ℃; the mixture is reacted for 5-8 h; after the reaction is completed, the mixture is subjected to steam distillation, cooled, filtered and dried to obtain 2-(2',4'-hydroxyphenyl)-4,6-bisstyryl-1,3,5-triazine; (3) sodium hydroxide is added into a N,N-dimethylformamide solvent, and heated and stirred to be dissolved; then 2-(2',4'-hydroxyphenyl)-4,6-bisstyryl-1,3,5-triazine is added into the mixture, and the temperature is increased to 65-75 ℃; then 2-bromoethyl isocyanate is added into the mixture, and the molar ratio of sodium hydroxide, 2-(2',4'-hydroxyphenyl)-4,6-bisstyryl-1,3,5-triazine and 2-bromoethyl isocyanate is 1-1.4:1:1-1.2; the mixture is reacted for 40-60 min; after the reaction is completed, the mixture is cooled, vacuum filtered, dissolved in dichloromethane and recrystallized to obtain compound A. (4) adding nano-titanium dioxide into toluene solvent, ultrasonic dispersion for 5 minutes, then adding compound A and dibutyltin dilaurate into the mixture, wherein the molar ratio of nano-titanium dioxide and compound A is 1:4-6, continuing ultrasonic dispersion for 10 minutes, reacting for 5-7 hours under nitrogen protection at 80-90℃, after the reaction, filtering, toluene extraction, drying to obtain compound B; (5) adding diethanolamine into ethanol solvent, passing nitrogen, heating to 65-75℃, adding compound B into the mixture, wherein the molar ratio of diethanolamine and compound B is 2-2.4:1, reacting for 20-28 hours, after the reaction, distilling under reduced pressure, washing with deionized water, drying to obtain nano-titanium dioxide based tetrahydroxy triazine; (6) adding 2,2-dihydroxypropionic acid and nano-titanium dioxide based tetrahydroxy triazine into N,N-dimethylformamide solvent, stirring and dispersing, then adding N,N'-dicyclohexyl carbodiimide into the mixture, wherein the molar ratio of 2,2-dihydroxypropionic acid, nano-titanium dioxide based tetrahydroxy triazine and N,N'-dicyclohexyl carbodiimide is 12-12.5:1:12-13, reacting for 3-5 hours in ice water bath, after the reaction, centrifuging, washing with deionized water, drying to obtain nano-titanium dioxide based hydroxyl-terminated hyperbranched polyester; The curing agent is a blocked high-functionality polyisocyanate crosslinking agent, containing a high-functionality macromolecule releasing isocyanate group after deblocking, the curing agent has a functionality of 2-9 after deblocking, and the deblocking temperature is 90-120℃.

2. The high build ultra-cured mid-coat coating for rail transportation sector as claimed in claim 1 wherein, The cosolvent is any one of ethanol, butanol, isopropanol, isobutanol, xylene, toluene, ethyl acetate, butyl acetate, methyl formate, methyl acetate, butyl benzoate, and the amount is 18-30%.

3. The high build ultra-cured mid-coat paint for rail transportation sector as claimed in claim 1 wherein, The additive is a wetting agent, a defoaming agent, a dispersing agent, an adhesion promoter, and a anti-settling agent; the adhesion promoter is any one of γ-aminopropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-methacryloyloxypropyl trimethoxysilane, vinyl trimethoxysilane, and γ-mercaptopropyl trimethoxysilane.

4. The high build ultra-cured mid-coat coating for rail transportation applications according to claim 1, wherein, The filler is one or more of titanium white, heavy calcium, and barium sulfate.

5. The high build ultra-cured mid-coat paint for rail transportation applications according to any one of claims 1 to 4, characterized in that, The midcoat coating is coated on the substrate by electrostatic spraying method, and is cured under heating condition, and the curing temperature is 100-120℃.

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