Unshielded spraying finish paint for railway vehicles and preparation process of unshielded spraying finish paint

Abstract

The invention relates to the technical field of high polymer materials, in particular to unshielded spraying finish paint for railway vehicles and a preparation process of the unshielded spraying finish paint. The invention relates to a shielding-free spraying finish paint for a railway vehicle. The shielding-free spraying finish paint is prepared from 35 to 50 parts of silicon modified waterborne polyurethane resin, 12 to 18 parts of modified polyether resin, 7 to 11 parts of anticorrosive filler, 0.8 to 1.3 parts of accelerant, 0.2 to 0.7 part of defoaming agent, 1.2 to 1.5 parts of solvent and 0.1 to 0.3 part of flatting agent. According to the non-shielding spraying finish paint for the railway vehicle, the defects that the adhesive force between coatings is poor, the corrosion resistance is poor, the adhesion time is short, and sagging is likely to happen are overcome, and the spraying finish paint has the good corrosion resistance and cohesiveness.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and more specifically, to a non-shielded spray topcoat for rail vehicles and a preparation method thereof. Background Art

[0002] In order to improve the congestion of urban traffic, in recent years, domestic high-speed rail, subway, light rail and other rail transit vehicles have been rapidly developed, and the demand for rail transit vehicles such as high-speed trains and subway vehicles has increased significantly. In order to adapt to the development of urban rail trains, the use of high-performance and highly decorative coatings that match them has increased rapidly, and the performance requirements for coatings for rail transit equipment are constantly increasing. At present, the commonly used automotive topcoat coatings will show different degrees of corrosion after the coating reaches a certain service life, especially the uneven parts that are difficult to completely coat, such as flange interfaces. After rusting, the rusted parts need to be polished and painted again, so the maintenance cost is very high.

[0003] The topcoat is more susceptible to corrosion after repair. The main reason is that the adhesion between the new and old coatings is poor, the adhesion time is short, and it is easy to sag and other defects. The coating must be repaired continuously. Since the anti-corrosion effect of the repaired coating is very poor, the number of repairs is high, and the accumulated cost is very high. The above problems have become the pain points of the coating industry. Therefore, many customers require that the coating can extend its service life as much as possible after repair, so as to shorten the maintenance cycle, increase equipment utilization, and save costs. Summary of the invention

[0004] In order to solve the problems of insufficient corrosion resistance, poor adhesion and easy sagging of existing external surface spray paints, the present application provides a non-shielded spray topcoat for rail vehicles and a preparation method thereof.

[0005] In the first aspect, the present application provides a rail vehicle unshielded spray topcoat, using the following technical solution: A non-shielded spray topcoat for rail vehicles comprises the following components in parts by weight: 35-50 parts of silicon-modified waterborne polyurethane resin, 12-18 parts of modified polyether resin, 7-11 parts of anticorrosive filler, 0.8-1.3 parts of accelerator, 0.2-0.7 parts of defoamer, 1.2-1.5 parts of solvent, and 0.1-0.3 parts of leveling agent.

[0006] By adopting the above technical scheme, the water-based coating polyurethane resin is silicon-modified so that it can be well wetted and spread, leveled quickly and produce thixotropy after being stationary, so that the spray topcoat is not easy to sag, greatly improving production efficiency and reducing the production of defective products. The silicon modifier has the advantages of low-temperature flexibility and low surface energy. Therefore, the low surface energy formed by the migration of the flexible silicon oxygen chain segment in the silicon modifier to the resin surface gives the slurry significant thixotropic properties, improves the toughness and high temperature resistance of the water-based polyurethane resin, and can reduce the crosslinking density and internal stress of the water-based polyurethane resin. Adding modified polyether resin increases the flexibility of the material while having good gloss and mechanical properties. Combined with the smaller silicon oxygen chain segment in the silicon modifier, the resin will not appear oily or dry after curing, thereby ensuring the bonding performance and quick-drying performance of the slurry, and further improving the adhesion performance of the product and not easy to sag.

[0007] It is then made from a variety of raw materials such as anti-corrosion fillers, accelerators, defoaming agents, solvents, leveling agents, etc. The various raw materials work together to produce a topcoat that has strong adhesion and good weather resistance, making the paint evenly dispersed and maintaining the stability of the paint and improving the film-forming effect, making the finished spray paint easy to use, with strong adhesion, high heat dissipation efficiency, good quick-drying performance, and good stability.

[0008] In a specific embodiment, the modified polyether resin is a silyl-terminated polyether resin.

[0009] By adopting the above technical scheme, silyl groups are introduced into the polyether, so that the silyl-terminated polyether can play a wetting and dispersing role, making it easier for the material to diffuse and adsorb on different surfaces. The silyl-terminated polyether has the characteristics of high surface activity and low surface energy, which can greatly improve the adhesion and wettability of the spray paint, enhance the adhesion of the spray paint and prevent sagging.

[0010] In a specific embodiment, the anti-corrosion filler includes nano titanium dioxide and graphene.

[0011] Nano-titanium dioxide, which has good heat resistance and chemical corrosion resistance, is used to improve the weather resistance and salt-alkali resistance of the spray paint. Graphene is added to enhance the mechanical properties of the coating and further increase its service life. Graphene has low solubility in gases and reduces the amount of penetration, further improving the barrier properties of the spray paint. Nano-titanium dioxide and graphene are mixed to prevent nano-titanium dioxide from agglomerating, thereby obtaining a good dispersion effect and further achieving a comprehensive anti-corrosion effect on the surface and inside.

[0012] In a specific implementation manner, the mass ratio of the nano-titanium dioxide to graphene is (2-4):1.

[0013] In a specific embodiment, the accelerator includes diphenylguanidine and K54 epoxy accelerator.

[0014] By adding diphenylguanidine and K54 epoxy accelerator, the curing speed is adjusted, the viscosity is increased and leveling is achieved, as well as the balance with sagging, which stabilizes the foam of the system. By adding diphenylguanidine as a medium-speed accelerator to the K54 epoxy accelerator, the adhesion time of the spray paint is further controlled to be short, and sagging is prevented.

[0015] In a specific embodiment, the mass ratio of the diphenylguanidine to the epoxy accelerator is (1-3):1.

[0016] In the second aspect, the present application provides a preparation process for an unshielded spray topcoat for rail vehicles, adopting the following technical scheme: comprising the following steps: taking a silicon-modified waterborne polyurethane resin in proportion, adding a defoaming agent, and dispersing at 600-750 r / min for 30 minutes, then weighing an anti-corrosion filler, a corrosion inhibitor, a accelerator, and a leveling agent and adding them in sequence, mixing and stirring evenly, then adding a solvent, adjusting the speed to 900-1100 r / min, and dispersing at high speed for 2-4 hours to obtain a topcoat slurry, and grinding the slurry to a fineness of 20-40 μm before discharging.

[0017] In a specific embodiment, the mixing and stirring is performed at a rotation speed of 800-1000 r / min for 1-3 hours.

[0018] In summary, this application has the following beneficial effects: 1. Silicon modification of waterborne polyurethane resin enables it to be well wetted and spread, leveled quickly and produce thixotropy after being stationary, so that the sprayed topcoat is not easy to sag, greatly improving production efficiency and reducing the production of defective products. Silicon modifiers have the advantages of low-temperature flexibility and low surface energy. Therefore, the low surface energy formed by the migration of the flexible silicon oxygen chain segments in the silicon modifier to the resin surface gives the slurry significant thixotropic properties, improves the toughness and high temperature resistance of the waterborne polyurethane resin, and can reduce the crosslinking density and internal stress of the waterborne polyurethane resin. Adding modified polyether resin increases the flexibility of the material while having good gloss and mechanical properties. Combined with the smaller silicon oxygen chain segments in the silicon modifier, the resin will not seep oil or not dry after curing, thereby ensuring the bonding and quick-drying properties of the slurry, and further improving the adhesion and non-sag properties of the product. It is then made from a variety of raw materials such as anti-corrosion fillers, accelerators, defoaming agents, solvents, leveling agents, etc. The various raw materials work together to produce a topcoat that has strong adhesion and good weather resistance, making the paint evenly dispersed and maintaining the stability of the paint and improving the film-forming effect, making the finished spray paint easy to use, with strong adhesion, high heat dissipation efficiency, good quick-drying performance, and good stability.

[0019] 2. Nano titanium dioxide with good heat resistance and chemical corrosion resistance improves the weather resistance and salt-alkali resistance of the spray paint. Graphene is added to enhance the mechanical properties of the coating and further improve the service life. Graphene has low solubility in gases and reduces the amount of penetration. The barrier properties of the spray paint are further improved. Nano titanium dioxide and graphene are mixed to prevent nano titanium dioxide from agglomerating, obtain good dispersion effects, ensure mechanical properties, and further achieve comprehensive surface and internal anti-corrosion effects. DETAILED DESCRIPTION

[0020] The present application is further described in detail below with reference to the embodiments.

[0021] Some of the raw materials used in the preparation examples and embodiments: polyurethane prepolymer was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.; the modified polyether resin is a methoxysilyl-terminated polyether resin model: S888E; the epoxy accelerator is K54 epoxy resin tertiary amine accelerator item number: 230324; diphenylguanidine was purchased from Shijiazhuang Shengpeng Chemical Co., Ltd.; the solvent is xylene, purchased from Shandong Youwang Chemical Products Co., Ltd., the defoamer model: ht-09; the leveling agent model: Dow DOWSIL56.

[0022] The raw materials used in the examples and comparative examples that are not otherwise specified are all conventional products that can be purchased from the market.

[0023] Preparation Example of Silicon-modified Waterborne Polyurethane Resin Preparation Example 1 Take 15g of polyurethane prepolymer and heat it to 60°C, add dimethylolpropionic acid, then add 1,4-butanediol dropwise, continue to add for 1h, adjust the temperature to 85°C, continue for 2h, add 5g of ethylene glycol tert-butyl ether during the reaction, and obtain a polyurethane prepolymer containing a hydrophilic group after the reaction; then add 11g of trimethylolpropane, adjust the temperature to 80°C, react for 1h to obtain a polyurethane prepolymer; then cool to below 50°C, add 8g of triethylamine under continuous stirring, KH550 react for 30min, then add deionized water, then add isophorone diamine, stir for 30min, and emulsify to obtain a silicon-modified waterborne polyurethane resin. Example

[0024] Example 1 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 35 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 18 kg of modified polyether resin, 11 kg of anticorrosive filler, 1.3 kg of accelerator, 0.2 kg of defoamer, 1.2 kg of solvent, and 0.3 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 600r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. After mixing and stirring at a speed of 1000r / min for 1h, add solvent, adjust the speed to 1100r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 40μm and then discharge it.

[0025] Example 2 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 50 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 12 kg of modified polyether resin, 7 kg of anticorrosive filler, 0.8 kg of accelerator, 0.7 kg of defoamer, 1.5 kg of solvent, and 0.1 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 750r / min for 30 minutes. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 800r / min for 3 hours, then add solvent, adjust the speed to 900r / min, and disperse at high speed for 4 hours to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0026] Example 3 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0027] Example 4 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 4:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0028] Example 5 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:2; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0029] Example 6 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano titanium dioxide; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0030] Example 7 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is graphene; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0031] Example 8 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 3:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0032] Example 9 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 0.5:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0033] Example 10 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0034] Embodiment 11 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is K54 epoxy accelerator; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0035] Comparative Example Comparative Example 1 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 54 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anti-corrosion filler is nano titanium dioxide and graphene, and the mass ratio of nano titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Silicon-modified waterborne polyurethane resin, modified polyether resin and defoamer are dispersed in proportion at a speed of 700 r / min for 30 minutes. Subsequently, accelerator and leveling agent are weighed in proportion and added in sequence. After mixing and stirring at a speed of 900 r / min for 2 hours, the solvent is added, the speed is adjusted to 1000 r / min, and high-speed dispersion is performed for 2 hours to obtain topcoat slurry. The slurry is ground to a fineness of 20 μm and then discharged.

[0036] Comparative Example 2 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 45.2 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 16 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, and 1.5 kg of solvent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take silicon-modified waterborne polyurethane resin, modified polyether resin and defoaming agent in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler and accelerator in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0037] Comparative Example 3 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 61 kg of modified polyether resin, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano titanium dioxide and graphene, and the mass ratio of nano titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take modified polyether resin and defoamer in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0038] Comparative Example 4 A non-shielded spray topcoat for rail vehicles, comprising the following components in parts by weight: 61 kg of silicon-modified waterborne polyurethane resin prepared in Preparation Example 1, 9 kg of anticorrosive filler, 1.2 kg of accelerator, 0.6 kg of defoamer, 1.5 kg of solvent, and 0.2 kg of leveling agent; wherein the anticorrosive filler is nano-titanium dioxide and graphene, and the mass ratio of nano-titanium dioxide to graphene is 2:1; the accelerator is diphenylguanidine and K54 epoxy accelerator, and the mass ratio of diphenylguanidine to epoxy accelerator is 1:1; Take silicon-modified waterborne polyurethane resin and defoamer in proportion and disperse them at a speed of 700r / min for 30min. Then, weigh anti-corrosion filler, accelerator and leveling agent in proportion and add them in turn. Mix and stir at a speed of 900r / min for 2h, then add solvent, adjust the speed to 1000r / min, and disperse at high speed for 2h to obtain topcoat slurry. Grind the slurry to a fineness of 20μm and then discharge it.

[0039] Performance Testing The unshielded spray topcoat for a rail vehicle prepared in the spraying example and the comparative example was dried at room temperature for 20 minutes and then cured at 60°C for 4 hours to produce a sample spray topcoat with a spray thickness of 25 um. The performance of the spray topcoat was then tested by the following method: a. Adhesion test: According to the method specified in GB / 1720-89, the adhesion of the paint film of the embodiment and the comparative example was tested; b. Salt spray corrosion resistance: Refer to GB / T1771-2007, no damage within 500 hours is qualified; c. Appearance of topcoat: Refer to GB / T1729-1979; the paint film is flat and uniform, without defects such as bubbles and pinholes, and without sagging. The paint film is qualified if it is in normal leveling state; d. Sagging performance: The surface drying time shall be in accordance with Method B of the determination method in GB / T 1728, and the actual drying time shall be in accordance with Method A; The comparison results are shown in Table 1 below: Table 1 Performance test results As can be seen from Table 1, the unshielded spray topcoat for rail vehicles obtained in the above embodiment meets the requirements of the spray topcoat for flow and quick-drying properties, bonding properties and salt spray corrosion resistance on the basis of mechanical properties.

[0040] Compared with Example 3 and Comparative Examples 3-4, the topcoat appearance, bonding performance, sagging performance and salt spray corrosion resistance of a rail vehicle unshielded spray topcoat prepared in Example 3 are better than those of Comparative Examples 3-4. Analysis shows that the low surface energy formed by the migration of the flexible silicon oxygen segment in the silicon modifier to the resin surface gives the slurry significant thixotropic properties, improves the toughness and high temperature resistance of the waterborne polyurethane resin, and can reduce the crosslinking density and internal stress of the waterborne polyurethane resin. The addition of modified polyether resin increases the flexibility of the material while having good gloss and mechanical properties. Combined with the smaller silicon oxygen segment in the silicon modifier, the resin will not seep oil or not dry after curing, thereby ensuring the bonding performance and quick-drying performance of the slurry, and further improving the adhesion performance and non-sagging of the product.

[0041] By comparing Example 3 with Examples 4-7, it can be seen that the topcoat appearance, bonding performance, sagging performance and salt spray corrosion resistance of a rail vehicle unshielded spray topcoat prepared in Example 3 are better than those of Examples 6-7. It is analyzed that nano-titanium dioxide with good heat resistance and chemical corrosion resistance improves the weather resistance and salt and alkali resistance of the spray paint, and the addition of graphene to enhance the mechanical properties of the coating further improves the service life. Graphene has low solubility in gas and reduces the amount of penetration. The barrier properties of the spray paint are further improved. Nano-titanium dioxide and graphene are mixed to prevent nano-titanium dioxide from agglomerating, obtain a good dispersion effect, and further achieve a comprehensive surface and internal anti-corrosion effect.

[0042] By comparing Example 3 with Examples 8-11, it can be seen that the appearance, adhesion performance, sagging performance and salt spray corrosion resistance of a rail vehicle unshielded spray topcoat prepared in Example 3 are better than those of Examples 10-11. It is analyzed that the diphenylguanidine and K54 epoxy accelerator in the proportion disclosed in the present application have the best effect on adjusting the curing speed. By adding diphenylguanidine as a medium-speed accelerator to the K54 epoxy accelerator, the adhesion time of the spray paint is further controlled to be short to prevent sagging, etc.

[0043] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A non-shielded spray topcoat for rail vehicles, characterized in that: The invention comprises the following components in parts by weight: 35-50 parts of silicon-modified waterborne polyurethane resin, 12-18 parts of modified polyether resin, 7-11 parts of anticorrosive filler, 0.8-1.3 parts of accelerator, 0.2-0.7 parts of defoamer, 1.2-1.5 parts of solvent and 0.1-0.3 parts of leveling agent.

2. The unshielded spray topcoat for rail vehicles according to claim 1, characterized in that: The modified polyether resin is a silyl-terminated polyether resin.

3. The unshielded spray topcoat for rail vehicles according to claim 1, characterized in that: The anti-corrosion filler comprises nano titanium dioxide and graphene.

4. The unshielded spray topcoat for rail vehicles according to claim 3, characterized in that: The mass ratio of the nano-titanium dioxide to graphene is (2-4):

1.

5. The unshielded spray topcoat for rail vehicles according to claim 1, characterized in that: The accelerators include diphenylguanidine and K54 epoxy accelerator.

6. The unshielded spray topcoat for rail vehicles according to claim 5, characterized in that: The mass ratio of the diphenylguanidine to the epoxy accelerator is (1-3):

1.

7. A process for preparing a non-shielded spray topcoat for a rail vehicle according to claims 1-6, characterized in that: The method comprises the following steps: taking silicon-modified waterborne polyurethane resin in proportion, adding a defoamer, dispersing at 600-750 r / min for 30 minutes, then weighing an anticorrosive filler, an accelerator and a leveling agent and adding them in sequence, mixing and stirring evenly, then adding a solvent, adjusting the rotation speed to 900-1100 r / min, dispersing at high speed for 2-4 hours to obtain a topcoat slurry, and discharging the slurry after grinding it to a fineness of 20-40 μm.

8. The process for preparing a non-shielded spray topcoat for a rail vehicle according to claim 7, characterized in that: The mixing and stirring is performed at a rotation speed of 800-1000 r / min for 1-3 hours.

Images