Sound-insulation noise-reduction flame-retardant air-drying water-soluble damping coating for rail train

Abstract

The invention belongs to the technical field of rail train coatings, and particularly relates to a sound-insulation noise-reduction flame-retardant air-drying water-soluble damping coating for a rail train. The coating is prepared from the following components in parts by weight: 35 to 60 parts of acrylic emulsion, 15 to 20 parts of 325-mesh ground calcium carbonate, 6 to 10 parts of modified aluminum hydroxide, 1 to 2 parts of modified wood fiber, 2 to 3 parts of modified wollastonite, 0.1 to 0.5 part of thickening agent, 0.5 to 1 part of fast dispersing agent, 0.5 to 2 parts of sterilizing agent and 0.5 to 1 part of coalescing agent. The coating disclosed by the invention has the functions of sound insulation, noise reduction and damping, and has flame-retardant and air-drying normal-temperature curing properties. And the system is water-based acrylic acid, so that the smell is relatively small after spraying or blade coating curing, and the comfort level after use can be improved.

Description

Technical Field

[0001] This invention belongs to the field of rail train coating technology, specifically relating to a sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains. Background Technology

[0002] In recent years, with the rapid development of high-speed trains in China, the manufacturing and usage of these trains have increased daily, and they are exported in large quantities overseas. The increase and extension of railway, light rail, and subway lines have also created a huge demand for railcars, and increasingly stringent passenger requirements. Currently, most damping coatings used in railcars require high-temperature baking to meet sound insulation and noise reduction performance requirements. These coatings have low damping factors, produce a strong odor after baking, and have weak flame retardant and smoke suppression functions, making them easily combustible and exhibiting poor adhesion.

[0003] To improve comfort, this sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains was developed. When sprayed inside the rail train, it can reduce vibration and noise during operation. Most importantly, it has flame-retardant and smoke-suppressing properties. If a high-speed rail train catches fire, the number of people affected is incalculable. Therefore, it is necessary to raise the standards for flammability or flame retardancy to ensure greater safety.

[0004] A sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains is sprayed inside the carriages. The coating thickness is 1.0-2.0 mm, and it can be fully dried at room temperature in 12-24 hours without baking. It has a low odor, meets the national standard for low VOCs, and has significant sound insulation and noise reduction performance, as well as superior damping performance, which reduces vibration. Its market potential is expected to grow. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to develop a water-soluble damping coating that provides sound insulation and noise reduction, cures at room temperature, has low VOCs, and exhibits high flame retardancy and smoke suppression properties. This invention utilizes a self-formulated acrylic emulsion, which enhances sound insulation and noise reduction, increases damping factors, improves vibration damping, and allows for room temperature curing. It also boasts improved adhesion, lower odor (meeting low VOC requirements), and flame retardancy and smoke suppression, reducing safety risks.

[0006] To achieve the above objectives, the technical solution of this invention is as follows: a sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains, comprising, by weight, 35-60 parts of self-prepared acrylic emulsion, 15-20 parts of 325-mesh heavy calcium carbonate, 6-10 parts of modified aluminum hydroxide, 1-2 parts of modified wood fiber, 2-3 parts of modified wollastonite, 0.1-0.5 parts of thickener, 0.5-1 part of fast-dispersant, 0.5-2 parts of bactericide, and 0.5-1 part of film-forming aid, dodecyl ester;

[0007] The self-prepared acrylic emulsion comprises, by weight, 20-25 parts butyl acrylate, 10-16 parts isooctyl acrylate, 13-20 parts methyl methacrylate, 6-15 parts styrene, 1-3 parts acrylic acid, 1-3 parts methacrylic acid, 1-2 parts hydroxyethyl acrylate, 0.5-1 part acrylamide, 1-2 parts ammonium persulfate, 1-2 parts ammonia, 0.5-1 part triethylamine, 1-2 parts organic defoamer, 1-2 parts wetting and dispersing agent, and 15-18 parts deionized water.

[0008] The above-mentioned sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains, wherein the self-prepared acrylic emulsion is prepared by the following method:

[0009] Step 1: Preparation of pre-emulsion: Add 10% deionized water to the reactor in sequence, then add all the soft monomers butyl acrylate (BA) and isooctyl acrylate (2-EHA) in sequence, stir evenly, turn on high speed stirring at 800-1200 r / min, add all the hard monomers methyl methacrylate (MMA) and styrene (St) in sequence and continue stirring, then add the functional monomers acrylate (AA), methacrylate (MAA), hydroxyethyl acrylate (HEA), and acrylamide (AM) and disperse them fully. After stirring at high speed for 30 min, a uniform, non-layered, and particle-free milky white pre-emulsion is formed.

[0010] Step 2: Prepare the initiator: Add the remaining deionized water to the reactor and turn on the low speed of 60 r / min;

[0011] Step 3: Bottom vessel feeding: Add one-third of the initiator solution to the reactor, start stirring at 300 r / min, purge with nitrogen 3 times, slowly raise the temperature to 84±2℃, and keep the temperature stable;

[0012] Step 4: Seed emulsion preparation: Add 10% pre-emulsion to the reaction vessel at a uniform rate, keep warm for 20±10 min, and observe whether a light blue fluorescent liquid appears;

[0013] Step 5: Droplet polymerization: Maintain the reactor temperature at 85±2℃, and simultaneously and uniformly add the remaining 90% of the pre-emulsion and two-thirds of the initiator solution, controlling the total droplet time to 2.5h, and prohibiting the rate from being too fast;

[0014] Step 6: Incubation and ripening: After the addition is complete, keep the temperature at 88±2℃ for 60 minutes, then raise the temperature to 90±2℃ and continue to keep the temperature for 30 minutes to ensure that all monomers are fully converted.

[0015] Step 6: Cooling and neutralization: Turn on the cooling water to cool the system to below 50°C. While stirring, slowly and evenly add ammonia and triethylamine, adjust the pH to 7.5-8.5, and continue stirring for 15 minutes to ensure complete neutralization.

[0016] Step 7: Addition and treatment of additives: Add organic defoamer, stir at low speed for 10 minutes, then add wetting and dispersing agent, and continue stirring for 15 minutes. Control the foam throughout the process to avoid introducing excessive air.

[0017] Step 8: Filtration: Use a 200-mesh filter under pressure to remove some of the gel and particles, and test the appearance and pH data before use.

[0018] The aforementioned sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains uses Dow's high-performance KUAIYI dispersant as the wetting and dispersing agent, which can improve its durability. It has a solid content of 45%, high dispersion efficiency, and low foaming.

[0019] The aforementioned sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains has a 325-mesh heavy calcium carbonate with an oil absorption value of 18-28 g / 100g. The 325-mesh heavy calcium carbonate can be sourced from Liaoning Kaiyuan Xinxin Mining Co., Ltd., with a calcium carbonate content ≥99.61%, whiteness ≥95%, and calcium oxide content ≥55.8%. After modification, it disperses faster, does not clump, has a lower oil absorption value, saves on emulsion usage, and exhibits better compatibility with acrylic emulsions, better fluidity, smoother application, stronger stability, and no long-term sedimentation.

[0020] The above-mentioned sound insulation, noise reduction, flame retardant, self-drying water-soluble damping coating for rail trains, wherein the modified aluminum hydroxide is prepared by drying the aluminum hydroxide to remove surface moisture, placing the dried aluminum hydroxide into a high-speed mixer, starting the stirring, heating to 100-140℃, slowly adding PK121 silane coupling agent at a dosage of 0.8-1.0% of the mass of aluminum hydroxide, stirring at high speed for 30 minutes, cooling to below 60℃, and discharging for later use.

[0021] The aluminum hydroxide has a purity of 99.5%, is manufactured by Hubei Tuoyuan Fine Chemical Co., Ltd., has a fineness of 1250 mesh, and an oil absorption value of 28-35g / 100g. After modification, the oil absorption value is even lower, at 22-28g / 100g. It is easy to disperse, does not clump or agglomerate, has good compatibility with acrylic emulsions, produces a dense paint film, has a whiteness greater than 96%, and exhibits good flame retardancy, smoke suppression, and water resistance.

[0022] The above-mentioned sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains, wherein the PK121 silane coupling agent is prepared as follows: according to the weight parts, 0.5 to 2 parts of sodium hydroxide catalyst are added to 1 to 3 parts of γ-chloropropyltriethoxysilane, 2 to 5 parts of alcohol are added dropwise at 20°C, and the reaction is carried out at 30 to 60°C. High-purity silane coupling agent is obtained by vacuum distillation, wherein the alcohol is methanol.

[0023] The above-mentioned sound insulation, noise reduction, flame retardant, self-drying water-soluble damping coating for rail trains is prepared by the following method of modifying wood fiber: 500μm wood fiber is mixed with deionized water to form a mixture, heated to 70-90℃, 1% hydrolyzed stearic acid is added, stirred for 30-60min, and then pressure filtered, dried and pulverized to obtain modified wood fiber.

[0024] The modified wood fibers form a three-dimensional network structure, which prevents the paint film from cracking after drying. During high-temperature fireproofing, it can prevent the coating from peeling off and powdering, enhances thixotropy and anti-sagging properties, has excellent water retention, enhances the toughness of the coating film after it is formed, improves impact resistance, hydrophobic and water-resistant properties, has better dispersion properties, and enhances crack resistance, thixotropy and other properties.

[0025] The aforementioned sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains uses 53L thickener from Arkema. This thickener is a self-associating acrylic alkali-swelling thickener, solvent-free, APEO-free, with extremely high viscosity at low shear, preventing sedimentation and delamination, and providing good leveling.

[0026] The aforementioned sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains uses 2.5SF as a bactericide, manufactured by Zhejiang Fenghong New Materials. It is easy to disperse, has low oil absorption, good water resistance, and is suitable for high-filler systems.

[0027] The aforementioned sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains uses dodecyl alcohol ester as a film-forming aid, manufactured by Ruentex Co., Ltd. This aid can lower the minimum film-forming temperature, prevent cracking and whitening at low temperatures, and improve the coating's adhesion, scrub resistance, non-decomposition, and non-pinhole formation.

[0028] The above-mentioned sound insulation, noise reduction, flame retardant, self-drying water-soluble damping coating for rail trains, with modified wollastonite prepared as follows: 1250 mesh wollastonite is put into a high-speed mixer, dried, surface moisture is removed, 1% PK122 titanate coupling agent is slowly added directly, heated and coated for modification at 110-130℃ for 30 minutes, stirred at high speed, and then cooled before use.

[0029] The PK121 silane coupling agent is a laboratory-formulated compound. In the overall formulation system, it enhances the compatibility between fillers and resins, solves dispersion problems, strengthens the adhesion between the paint film and the substrate, and to a certain extent eliminates paint peeling and flaking. It also improves the surface activity of fillers and is suitable for full coating processes. Specifically, butyl acrylate (BA) adjusts the flexibility of the paint film and has a low Tg; methyl methacrylate (MMA) adjusts the hardness of the paint film and has a high Tg; acetic acid (AA) provides carboxyl groups, improving emulsion stability and adhesion to electrophoretic or cold-rolled steel substrates; and the emulsifier improves emulsion stability and reduces foaming.

[0030] The modified wollastonite described above has needle-like reinforcement, super crack resistance, good dispersion, improved hardness, and meets the requirements of wear resistance and scratch resistance. It also has the advantages of yellowing resistance and water resistance.

[0031] The PK122 titanate coupling agent comprises, by weight, 12 parts titanium tetrachloride, 16 parts isopropanol, 10 parts 2-ethylhexanol, 42 parts stearic acid, 18 parts xylene, and 2 parts triethylamine. The preparation method of the PK122 titanate coupling agent is as follows: 2-ethylhexanol and xylene are mixed, heated to 100–120°C to remove water, cooled to 30–50°C, titanium tetrachloride is slowly added dropwise, ammonia water is added to neutralize to pH 7–8, NH4Cl precipitate is removed, stearic acid is added, the temperature is raised to 120–150°C, and the reaction is carried out for 3–5 hours. The solvent is removed and the mixture is filtered to obtain the PK122 titanate coupling agent.

[0032] The PK122 titanate coupling agent can make the adhesion of heavy calcium carbonate, aluminum hydroxide and wollastonite stronger, without powdering or cracking, improve water resistance, prevent alkali return, increase adhesion, and be more stable under high temperature fireproofing.

[0033] This invention uses heavy calcium carbonate as the main filler material, specifically 325 calcium carbonate. After low-temperature short-time curing, it exhibits extremely high non-flammability and smoke suppression properties, while also achieving lightweighting. As an inorganic flame retardant, it does not contain harmful elements such as halogens and phosphorus, and its price is relatively low. Furthermore, talc and modified silica can improve the mechanical strength, impact resistance, and thixotropy of the product. Due to their uniform particle size, they can not only improve processing fluidity but also make the surface smoother during construction.

[0034] The defoamer is 2902 organosilicon defoamer, which has the characteristics of fast defoaming, long-lasting foam suppression, high temperature resistance, stable chemical properties, no impact on leveling, and stability under high shear. It is suitable for water-soluble coating systems.

[0035] The wetting and dispersing agent mentioned is EF406, manufactured by BASF, which can effectively reduce surface tension, wet and penetrate the substrate, and provide leveling and smoothness.

[0036] The above-mentioned sound insulation, noise reduction, flame retardant, self-drying, water-soluble damping coating for rail trains is used in the internal coating of rail trains.

[0037] A sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains has the following advantages compared to traditional technologies:

[0038] 1. The present invention provides a sound insulation, noise reduction, flame retardant, self-drying, water-soluble damping coating for rail trains, which has stronger sound insulation and noise reduction functions. Its damping advantage can reduce vibration during high-speed operation, improve driving and riding comfort, and has the advantages of flame retardancy, smoke suppression, and low VOC. Compared with traditional coatings, it is more environmentally friendly, and can be fully cured at room temperature in 12-24 hours.

[0039] 2. The self-formulated acrylic emulsion of the present invention has the following advantages: after film formation, it is cross-linked, water-resistant, solvent-resistant, has denser paint film, stronger adhesion, better weather resistance and salt spray resistance than ordinary acrylic emulsions, and the solid content of the emulsion can be adjusted, so the film flexibility and hardness can be balanced, making it suitable for use in a variety of environments and for applications on multiple substrates. During the film formation process, the shrinkage area is small, the paint film performance is better, it is not easy to crack or chalk, and it is also more resistant to yellowing.

[0040] 3. The self-formulated silane coupling agent and self-formulated titanate coupling agent used in this product enhance the adhesion between the paint film and the substrate, effectively preventing paint peeling and flaking, improving filler surface activity, and making it suitable for full coating processes. Specifically, butyl acrylate (BA) adjusts the flexibility of the paint film, resulting in a low Tg; methyl methacrylate (MMA) adjusts the hardness of the paint film, resulting in a high Tg; and acetic acid (AA) provides carboxyl groups, improving emulsion stability and adhesion to electrophoretic or cold-rolled steel substrates. The emulsifier enhances emulsion stability and reduces foaming, while the titanate coupling agent strengthens the bond of calcium carbonate, aluminum hydroxide, and wollastonite, preventing powdering and cracking, improving water resistance, preventing alkali return, increasing adhesion, and providing greater stability during high-temperature fireproofing.

[0041] The modified aluminum hydroxide in this product has a lower oil absorption value of 22-28g / 100g, making it easy to disperse, non-clumping, and non-agglomerating. It is well-matched with acrylic emulsions, resulting in a dense paint film with a whiteness greater than 96%. It is flame-retardant, smoke-suppressing, and has good water resistance. It is non-toxic and has higher tensile strength. The modified wood fiber forms a three-dimensional network structure, preventing the paint film from cracking after drying. During high-temperature fireproofing, it can prevent the coating from peeling off and chalking, enhance thixotropy and anti-sagging properties, and has excellent water retention. It also enhances the toughness of the coating film after formation, making it impact-resistant, hydrophobic, and water-resistant. The modified wollastonite has needle-like reinforcement, super crack resistance, good dispersion, and improved hardness, meeting the requirements for wear resistance and scratch resistance. It also has the advantages of yellowing resistance and water resistance. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the embodiments.

[0043] All raw materials mentioned in the following examples are commercially available.

[0044] Example 1 Acrylic emulsion

[0045] The self-prepared acrylic emulsion comprises, by weight, 22.5 parts butyl acrylate (BA), 13 parts isooctyl acrylate (2-EHA), 16.5 parts methyl methacrylate (MMA), 10.5 parts styrene (St), 2 parts acrylic acid (AA), 2 parts methacrylate (MAA), 1.5 parts hydroxyethyl acrylate (HEA), 0.75 parts acrylamide (AM), 1.5 parts ammonium persulfate, 1.5 parts ammonia, 0.75 parts triethylamine, 1.5 parts 2902 silicone defoamer, 1.5 parts BASF EF406 dispersant, and 16.5 parts deionized water.

[0046] The preparation method of acrylic emulsion is as follows:

[0047] Step 1: Preparation of pre-emulsion: Add 10% deionized water to the reactor in sequence, then add all the soft monomers butyl acrylate (BA) and isooctyl acrylate (2-EHA) in sequence, stir evenly, turn on high speed stirring at 800-1200 r / min, add all the hard monomers methyl methacrylate (MMA) and styrene (St) in sequence and continue stirring, then add functional monomers acrylate (AA), methacrylate (MAA), hydroxyethyl acrylate (HEA), and acrylamide (AM) and disperse them fully. After stirring at high speed for 30 min, a uniform, non-layered, and particle-free milky white pre-emulsion is formed.

[0048] Step 2: Prepare the initiator: Add the remaining deionized water to the reactor and turn on the low speed of 60 r / min;

[0049] Step 3: Bottom vessel feeding: Add one-third of the initiator ammonium persulfate solution to the reactor, start stirring at 300 r / min, purge with nitrogen 3 times, slowly raise the temperature to 84±2℃, and keep the temperature stable;

[0050] Step 4: Seed emulsion preparation: Add 10% pre-emulsion to the reaction vessel at a uniform rate, keep warm for 20±10 min, and observe whether a light blue fluorescent liquid appears;

[0051] Step 5: Droplet polymerization: Maintain the reactor temperature at 85±2℃, and simultaneously and uniformly add the remaining 90% of the pre-emulsion and two-thirds of the initiator solution, controlling the total droplet time to 2.5h, and prohibiting the rate from being too fast;

[0052] Step 6: Incubation and ripening: After the addition is complete, keep the temperature at 88±2℃ for 60 minutes, then raise the temperature to 90±2℃ and continue to keep the temperature for 30 minutes to ensure that all monomers are fully converted.

[0053] Step 6: Cooling and neutralization: Turn on the cooling water to cool the system to below 50°C. While stirring, slowly and evenly add ammonia and triethylamine, adjust the pH to 7.5-8.5, and continue stirring for 15 minutes to ensure complete neutralization.

[0054] Step 7: Addition and treatment of additives: Add 2902 silicone defoamer, stir at low speed for 10 minutes, then add BASF EF406 dispersant, continue stirring for 15 minutes, control the foam throughout the process and avoid introducing excessive air;

[0055] Step 8: Filtration: Use a 200-mesh filter under pressure to remove some of the gel and particles, and test the appearance and pH data before use.

[0056] Example 2: PK-121 silane coupling agent, PK-122 titanate coupling agent

[0057] PK-121 silane coupling agent is prepared by adding 0.5 to 2 parts of sodium hydroxide catalyst to 1 to 3 parts of γ-chloropropyltriethoxysilane, adding 2 to 5 parts of methanol dropwise at 20°C, reacting at 30 to 60°C, and removing low-boiling substances and salt residue by vacuum distillation to obtain a high-purity silane coupling agent.

[0058] PK-122 titanate coupling agent, by mass parts, includes 12 parts titanium tetrachloride, 16 parts isopropanol, 10 parts 2-ethylhexanol, 42 parts stearic acid, 18 parts xylene, and 2 parts triethylamine. The preparation method of PK122 titanate coupling agent is as follows: 2-ethylhexanol and xylene are mixed, heated to 100-120℃ to remove water, cooled to 30-50℃, titanium tetrachloride is slowly added dropwise, ammonia water is added to neutralize to pH 7-8, NH4Cl precipitate is removed, stearic acid is added, the temperature is raised to 120-150℃, the reaction is carried out for 3-5 hours, the solvent is removed and the mixture is filtered to obtain PK122 titanate coupling agent.

[0059] Example 3 Modified aluminum hydroxide

[0060] Modified aluminum hydroxide includes 800-mesh aluminum hydroxide powder and silane coupling agent PK121.

[0061] The preparation method is as follows: dry the aluminum hydroxide raw powder at 100℃ to remove surface moisture and improve the modification effect. Put the dried aluminum hydroxide into a high-speed mixer, start stirring, heat to 100-140℃, slowly add 1% PK121 silane coupling agent, stir at high speed for 30 minutes, cool down to below 60℃, and discharge for later use.

[0062] Example 4 Modified wood fiber

[0063] Preparation of sodium stearate: Based on the principle of stearic acid hydrolysis, stearic acid is added to an alkali to form sodium stearate. Chemical formula: C 17 H 35 COOH + NaOH → C 17 H 35 COONa + H2O, which is the saponification process of stearic acid, makes it water-soluble.

[0064] Mix 60 g of 500μm wood fiber with 37 g of deionized water, heat to 70-90℃, add 3 g of the sodium stearate obtained above, continue stirring for 30-60 min, then filter under pressure, dry and pulverize. The modified wood fiber has significantly improved hydrophobicity, better dispersion performance, and enhanced crack resistance, thixotropy, and water retention properties.

[0065] Example 5 Modified Wollastonite

[0066] 1250 mesh wollastonite was put into a high-speed mixer and dried at 100-110℃ for 30 minutes to remove surface moisture. 97g of 1250 mesh wollastonite was slowly and directly added to 2g of titanate coupling agent PK122, followed by 1g of ethanol. The mixture was then heated and coated for modification at 110-130℃ for 30 minutes with high-speed stirring. After cooling, it was ready for use.

[0067] Example 6: A sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains

[0068] (a) The formula composition is as follows

[0069] Total 800g: 440.0g acrylic emulsion obtained in Example 1, 160.0g modified heavy calcium carbonate (325 mesh), 64.0g modified aluminum hydroxide (1250 mesh) obtained in Example 3, 12.0g modified wood fiber obtained in Example 4, 24.0g modified wollastonite obtained in Example 5, 2.4g Arkema 53L thickener, 6.4g Dow high-performance KUAIYI dispersant, 8.0g bactericide 2.5SF, and 8.0g dodecyl alcohol ester (film-forming aid).

[0070] (II) The preparation method is as follows:

[0071] 1. Start stirring at 60 r / min. Add the raw materials 325 mesh heavy calcium carbonate, modified wood fiber, modified aluminum hydroxide, and modified wollastonite to the acrylic emulsion obtained in Example 1. After the above raw materials are evenly mixed, add them in 5 batches with an interval of 30 seconds between each addition. After all the raw materials are added, stir for 3 minutes.

[0072] 2. Start the low-speed stirring at 60 r / min, slowly add the raw material dispersant, bactericide 2.5SF and dodecyl ester, then start the low-speed stirring at 30 r / min and the high-speed stirring at 600 r / min, stirring for a total of 15 minutes.

[0073] 3. Start the low-speed stirring at 30 rpm, add the Arkema 53L thickener, then start the low-speed stirring at 30 rpm and the high-speed stirring at 600 rpm for a total of 10 minutes.

[0074] 4. Sampling and testing.

[0075] 5. Based on the viscosity results, add Arkema 53L thickener or pure water again. Start low-speed stirring at 30 rpm, then high-speed stirring at 600 rpm. Degas under vacuum at -0.05 MPa for 5 minutes, then under vacuum at 0.08 MPa for 6 minutes. Measure the temperature with a thermometer; the temperature should not exceed 30℃. If the temperature exceeds this limit, immediately turn on the cooling circulating water.

[0076] 6. Sampling and testing.

[0077] 7. Packed after double filtration with 20 mesh and 30 mesh filters.

[0078] Example 7

[0079] The self-prepared acrylic emulsion in Example 1 was replaced with Wanhua acrylic emulsion, and the other components and preparation methods were the same as in Example 6.

[0080] Example 8

[0081] Ordinary aluminum hydroxide, wood fiber, and wollastonite were used instead of the modified aluminum hydroxide in Example 6. The modified wood fiber and modified wollastonite were used, and the emulsion was the acrylic emulsion obtained in Example 1. Other components and preparation methods remained the same as in Example 6.

[0082] Comparative Example 1

[0083] 325-mesh heavy calcium carbonate was used to replace the modified aluminum hydroxide, modified wood fiber, and modified wollastonite in Example 6. Other components and preparation methods were the same as in Example 6.

[0084] Comparative Example 2

[0085] A waterborne polyurethane TL-1 emulsion with a glass transition temperature of 50°C was used to replace the acrylic emulsion obtained in Example 1. Other components and preparation methods were the same as in Example 6.

[0086] Comparative Example 3

[0087] 325 heavy calcium carbonate was used to replace the modified heavy calcium carbonate, modified aluminum hydroxide, and modified wollastonite in Example 6, and TL-1 emulsion was used to replace the acrylic emulsion obtained in Example 1.

[0088] Comparative Example 4

[0089] Commercially available water-soluble coatings.

[0090] Example 9 Performance Testing

[0091] Specific testing technical indicators are shown in Table 1.

[0092] Table 1. Comparison of coating performance between the examples and comparative examples.

[0093]

[0094] As shown in Table 1, after Comparative Example 1 replaced the modified aluminum hydroxide, modified wood fiber, and modified wollastonite in Example 6 with 325 mesh heavy calcium carbonate, the adhesion was poor, the room temperature curing time was prolonged, and the flame retardant performance was reduced.

[0095] Example 7 used other acrylic emulsions, and the surface drying time exceeded the expected time, and the effect did not reach the ideal state.

[0096] Example 8 shows that the adhesion of ordinary aluminum hydroxide, wood fiber, and wollastonite is poor, and the curing time at room temperature is prolonged.

[0097] Comparative Example 2: The water-based polyurethane emulsion with a similar glass transition temperature used has a certain flame retardant effect, but it has a strong odor, a long curing time, and the adhesion does not meet the cross-cut adhesion test requirements. This deviates from the original design intention of room temperature curing, has an unpleasant odor, and the adhesion does not meet the corresponding technical standards.

[0098] Comparative Example 3 showed unsatisfactory adhesion and increased curing time.

[0099] Comparative Example 4 requires low-temperature baking to cure, has acceptable adhesion, but has a strong odor and is flammable, thus failing to meet the requirements.

[0100] Therefore, the invention has obvious advantages such as good sound insulation and noise reduction, vibration reduction, flame retardancy, room temperature curing, and environmental protection.

Claims

1. A sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains, characterized in that, The formula, by weight, includes 35-60 parts acrylic emulsion, 15-20 parts 325-mesh heavy calcium carbonate, 6-10 parts modified aluminum hydroxide, 1-2 parts modified wood fiber, 2-3 parts modified wollastonite, 0.1-0.5 parts thickener, 0.5-1 part fast-dispersant, 0.5-2 parts bactericide, and 0.5-1 part film-forming aid. The acrylic emulsion comprises, by weight, 20-25 parts butyl acrylate, 10-16 parts isooctyl acrylate, 13-20 parts methyl methacrylate, 6-15 parts styrene, 1-3 parts acrylic acid, 1-3 parts methacrylic acid, 1-2 parts hydroxyethyl acrylate, 0.5-1 part acrylamide, 1-2 parts ammonium persulfate, 1-2 parts ammonia, 0.5-1 part triethylamine, 1-2 parts organic defoamer, 1-2 parts wetting and dispersing agent, and 15-18 parts deionized water.

2. The sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains according to claim 1, characterized in that, The preparation method of the acrylic emulsion is as follows: Step 1: Preparation of pre-emulsion: Add 10% deionized water to the reactor in sequence, then add all the soft monomers butyl acrylate and isooctyl acrylate in sequence, stir evenly, turn on high speed stirring at 800-1200 r / min, add all the hard monomers methyl methacrylate and styrene in sequence and continue stirring, then add the functional monomers acrylic acid, methacrylic acid, hydroxyethyl acrylate and acrylamide, and disperse them fully. After high speed stirring, a uniform, non-layered, and particle-free milky white pre-emulsion is formed. Step 2: Preparation of initiator: Add the remaining deionized water to the reactor and start the low speed at 60 r / min. Step 3: Bottom vessel feeding: Add one-third of the initiator ammonium persulfate solution to the reactor, start stirring at 300 r / min, purge with nitrogen 3 times, slowly raise the temperature to 84±2℃, and keep the temperature stable. Step 4: Seed emulsion preparation: Add 10% pre-emulsion to the reaction vessel at a uniform rate, keep warm for 20±10 min, and observe whether a light blue fluorescent liquid appears; Step 5: Droplet polymerization: Maintain the reactor temperature at 85±2℃, and simultaneously and uniformly add the remaining 90% of the pre-emulsion and two-thirds of the initiator ammonium persulfate solution, controlling the total droplet time to 2.5h, and prohibiting the rate from being too fast; Step 6: Incubation and ripening: After the addition is complete, keep the temperature at 88±2℃ for 60 minutes, then raise the temperature to 90±2℃ and continue to keep the temperature for 30 minutes to ensure that all monomers are fully converted. Step 6: Cooling and neutralization: Turn on the cooling water to cool the system to below 50°C. While stirring, slowly and evenly add ammonia and triethylamine, adjust the pH to 7.5-8.5, and continue stirring for 15 minutes to ensure complete neutralization. Step 7: Addition and treatment of additives: Add organic defoamer, stir at low speed for 10 minutes, then add wetting and dispersing agent, and continue stirring for 15 minutes. Control the foam throughout the process to avoid introducing excessive air. Step 8: Filtration: Use a 200-mesh filter under pressure to remove some gel and particles, test the appearance and pH data, and then proceed with the application.

3. The sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains according to claim 1, characterized in that, The wetting and dispersing agent is BASF EF406 dispersant.

4. The sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains according to claim 1, characterized in that, The modified aluminum hydroxide is prepared by drying the aluminum hydroxide to remove surface moisture, placing the dried aluminum hydroxide into a high-speed mixer, starting the stirring, heating to 100-140℃, slowly adding PK121 silane coupling agent at a dosage of 0.8-1.0% of the mass of aluminum hydroxide, stirring at high speed for 30 minutes, cooling to below 60℃, and then discharging for later use.

5. The sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains according to claim 4, characterized in that, The preparation method of the PK121 silane coupling agent is as follows: according to the weight parts, 0.5 to 2 parts of sodium hydroxide catalyst are added to 1 to 3 parts of γ-chloropropyltriethoxysilane, 2 to 5 parts of alcohol are added dropwise at 20°C, and the reaction is carried out at 30 to 60°C. The high-purity silane coupling agent is obtained by vacuum distillation, wherein the alcohol is methanol.

6. The sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains according to claim 1, characterized in that, The modified wood fiber is prepared as follows: 500μm wood fiber is mixed with deionized water to form a mixture, heated to 70-90℃, 1% hydrolyzed stearic acid is added, stirred for 30-60 minutes, and then pressure filtered, dried and pulverized to obtain modified wood fiber.

7. The sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains according to claim 1, characterized in that, The bactericide is 2.5SF; the thickener is 53L.

8. The sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains according to claim 1, characterized in that, The film-forming aid is dodecyl alcohol ester.

9. The sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for railway trains according to claim 1, characterized in that, The preparation method of modified wollastonite is as follows: 1250 mesh wollastonite is put into a high-speed mixer, dried, and surface moisture is removed. 1% titanate coupling agent PK122 is slowly added directly. The mixture is heated and coated for modification at a temperature of 110-130℃ for 30 minutes. The mixture is stirred at high speed and cooled before use.

10. A sound-insulating, noise-reducing, flame-retardant, self-drying, water-soluble damping coating for rail trains according to claim 9, characterized in that, The PK122 titanate coupling agent comprises, by weight, 12 parts titanium tetrachloride, 16 parts isopropanol, 10 parts 2-ethylhexanol, 42 parts stearic acid, 18 parts xylene, and 2 parts triethylamine. The preparation method of the PK122 titanate coupling agent is as follows: 2-ethylhexanol and xylene are mixed, heated to 100–120°C to remove water, cooled to 30–50°C, titanium tetrachloride is slowly added dropwise, ammonia water is added to neutralize to pH 7–8, NH4Cl precipitate is removed, stearic acid is added, the temperature is raised to 120–150°C, and the reaction is carried out for 3–5 hours. The solvent is removed and the mixture is filtered to obtain the PK122 titanate coupling agent.

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