Preparation process of low VOCs environment-friendly color plate

Abstract

The application relates to the field of color steel plate preparation, and particularly discloses a preparation process of a low-VOCs environment-friendly color plate; the preparation process comprises the following steps: S1, after the pretreatment of a steel plate, uniformly spraying toughening coating and porous toughening fibers on the surface of the steel plate, drying, and die forming to obtain a semi-finished product; and S2, uniformly spraying water-based fluorocarbon coating on the surface of the semi-finished product, drying, and obtaining a finished product; the preparation process has the advantages of low VOCs, and the color steel plate has the advantages of high impact resistance, high corrosion resistance and ultraviolet resistance on the plane of the top of the color steel plate.

Description

Technical Field

[0001] This application relates to the field of color steel sheet preparation, and more specifically, it relates to a preparation process for low-VOCs environmentally friendly color steel sheets. Background Technology

[0002] Color-coated steel sheet is a type of steel sheet with an organic coating. It has the advantages of good corrosion resistance, bright colors, beautiful appearance, and easy processing.

[0003] During the manufacturing process of color-coated steel sheets, a coating needs to be sprayed onto the surface to ensure the sheet's durability and aesthetics. Coatings are divided into oil-based and water-based coatings. Oil-based coatings have high fullness, forming a thicker film to ensure the strength and durability of the color-coated steel sheet. They also have strong wear resistance, resisting mechanical abrasion and chemical corrosion, further extending the service life of the sheet. However, oil-based coatings are not environmentally friendly, as the solvents easily release volatile organic pollutants (VOCs), which can affect human health. Water-based coatings, while more environmentally friendly and free of harmful substances, do not pose a health hazard. However, water-based coatings have a longer drying time, better fluidity, and are easily affected by temperature and humidity in the external environment during the drying process.

[0004] Furthermore, to increase the strength of color steel sheets, they are generally pressed into corrugated sheets. The corrugation increases the strength of the color steel sheet. When water-based coating is applied to the top plane of the corrugations, the water-based coating tends to flow from the top plane of the corrugations to the planes on both sides of the corrugations due to its fluidity, resulting in inconsistent coating thickness between the corrugated and non-corrugated surfaces. Therefore, if the viscosity of the water-based coating is high, it can easily affect the uniformity of the overall coating on the surface of the corrugated sheet. If the viscosity of the water-based coating is low and its fluidity is good, it can easily lead to differences in coating thickness. Since the top plane of the corrugations is more susceptible to external impacts and wear, it is more likely to be damaged first. If the coating on the top plane of the corrugations is thin, it is more susceptible to damage from external impacts and friction, thus affecting the service life of the color steel sheet.

[0005] Therefore, how to prepare a new type of corrugated color steel sheet with low VOCs, and with the corrugated top surface having high impact resistance, high corrosion resistance, and UV resistance, thereby extending the service life of the color steel sheet, is a problem that needs to be solved. Summary of the Invention

[0006] In order to prepare a new type of corrugated color steel sheet with low VOCs, and with the corrugated top surface having high impact resistance, high corrosion resistance, and UV resistance, thereby extending the service life of the color steel sheet, this application provides a preparation process for a low-VOCs environmentally friendly color steel sheet.

[0007] This application provides a manufacturing process for low-VOCs environmentally friendly color-coated steel sheets, which adopts the following technical solution:

[0008] A manufacturing process for low-VOCs environmentally friendly color-coated steel sheets includes the following steps:

[0009] S1. After the steel plate is pretreated, toughening coating and porous toughening fiber are evenly sprayed on the surface, dried, and molded to obtain a semi-finished product;

[0010] S2. Spray water-based fluorocarbon coating evenly onto the surface of the semi-finished product, and then dry it to obtain the finished product.

[0011] By adopting the above technical solution, the surface roughness of the steel plate increases after pretreatment, which facilitates the adhesion of toughening coating and improves the adhesion stability of toughening coating and fiber on the steel plate surface. Then, during the molding process, corrugations appear on the surface of the steel plate. The toughness of the toughening coating and the good toughness of the porous toughening fiber are utilized to improve the impact resistance of the color steel plate surface coating. Furthermore, during the molding process of corrugation, the coating and porous toughening fiber deform with the corrugation of the steel plate. On the one hand, spraying the coating and porous toughening fiber on the flat plate does not easily produce coating thickness changes between corrugated and non-corrugated areas, ensuring the uniformity of the color steel plate surface coating. This makes the top plane of the corrugation have good impact resistance, thereby improving the strength and impact resistance of the color steel plate.

[0012] The semi-finished water-based fluorocarbon coating utilizes the environmental benefits of water-based fluorocarbon coatings to give color steel sheets the advantage of low VOCs. Furthermore, the coating can stably bond to the fiber and toughening coating surfaces, improving the adhesion stability of the coating on the steel sheet surface. At the same time, the fluorocarbon coating has ultra-long weather resistance, high stain resistance, high corrosion resistance, and low friction, making the color steel sheets resistant to acid rain and ultraviolet corrosion, easy to clean, and thus extending the service life of the color steel sheets.

[0013] Preferably, the pretreatment includes the following steps: after shot blasting, a polyvinyl alcohol solution is uniformly sprayed to obtain the product.

[0014] By adopting the above technical solution, shot blasting can improve the surface roughness of the steel plate. Combined with the viscosity of the polyvinyl alcohol solution, it facilitates the stable adhesion of the toughening coating to the steel plate surface, improves the adhesion stability of the toughening coating on the steel plate surface, and utilizes the impact-resistant toughening effect of the toughening coating to improve the impact resistance of the color steel plate, thereby extending the service life of the color steel plate.

[0015] Preferably, the toughening coating comprises the following raw materials in parts by weight:

[0016] 80-100 parts of waterborne polyurethane, 5-10 parts of modified polyether ether ketone, 1-4 parts of modified carbon nanotubes, and 20-30 parts of curing agent.

[0017] By adopting the above technical solution, the combination of waterborne polyurethane and polyvinyl alcohol solution can improve the cross-linking effect of toughening coating on steel plate surface, improve adhesion stability, and utilize the high toughness of polyurethane and modified polyether ether ketone to make the coating formed by the toughening coating on the steel plate surface have high impact resistance. Combined with the filling effect of modified carbon nanotubes, the impact strength of the coating formed by the toughening coating is further improved, thus giving the color steel plate the advantage of good impact resistance.

[0018] Preferably, the modified polyetheretherketone is prepared from polyetheretherketone microparticles, polyethylene glycol solution and silk fibroin fibers in a mass ratio of 1:0.1-0.2:0.1-0.3.

[0019] By adopting the above technical solution, polyetheretherketone (PEEK) microparticles, polyethylene glycol solution, and silk fibroin fibers are combined. The viscosity of the polyethylene glycol solution is used to adhere the silk fibroin fibers to the surface of the PEEK microparticles. The lightweight and porous properties of the silk fibroin are used to further lightly modify the PEEK, making it easier for the PEEK to float on the upper surface of the toughening coating. After the toughening coating is formed, the high impact resistance of the PEEK on the upper surface is used to improve the impact resistance of the coating surface.

[0020] The silk fibroin fibers on the surface of polyetheretherketone (PEEK) microparticles have adsorption properties and contain hydroxyl groups, which facilitate cross-linking and bonding with water-based polyurethane, polyvinyl alcohol solutions, and modified carbon nanotubes. This achieves the effect of cross-linking and dispersing PEEK microparticles in the coating, thereby improving the impact resistance of the coating through the cross-linking network, protecting the impact resistance of the corrugated top surface of the color steel plate, and extending the service life of the color steel plate.

[0021] Preferably, the modified carbon nanotubes are prepared by soaking and dispersing carbon nanotubes in a composite solution of silica and silane coupling agent.

[0022] By employing the above technical solution, carbon nanotubes are dispersed after being soaked in a silane coupling agent, and then nano-silica is added. The permeability of the nano-silica, combined with the binding effect of the silane coupling agent, allows the internal pore structure of the carbon nanotubes to be loaded with nano-silica, resulting in a carbon nanotube density of approximately 2.1 g / cm³. 3 By increasing the loading capacity, the density of the modified carbon nanotubes is improved, making it easier for them to adhere to the coating near the bottom, i.e., near the side of the color steel plate; while the density of polyetheretherketone is approximately 1.21 g / cm³. 3After being treated with porous silk fibroin, the density is further reduced, allowing the modified carbon nanotubes to be positioned closer to the bottom of the coating, while the modified polyether ether ketone (PEEK) is positioned closer to the top. During the molding process, the modified PEEK has good flexibility and is less prone to deformation. Since the modified carbon nanotubes are positioned closer to the bottom of the coating, the square deformation at the bottom of the coating is lower than that at the top, thus ensuring the uniformity of the coating on the corrugated surface of the steel plate. Combined with the high flexibility and impact resistance of the modified PEEK and modified carbon nanotubes, the corrugated surface has high impact resistance, extending the service life of the color steel plate.

[0023] Preferably, the porous toughening fiber is composed of polycaprolactone-modified microcrystalline cellulose fiber and calcium oxide whisker-modified polyester fiber in a mass ratio of 1:1-2.

[0024] By adopting the above technical solution, the bonding effect of polycaprolactone and polyurethane is utilized to improve the bonding effect between polycaprolactone-modified microcrystalline cellulose fibers and toughening coatings. The porous heat insulation properties of microcrystalline cellulose fibers, combined with the flexibility and elasticity of polyester fibers, not only improve the heat insulation and VOCs absorption effects of porous toughening fibers, but also enhance their impact resistance, making them less prone to breakage and improving the impact resistance of the color steel plate surface coating. Furthermore, the addition of calcium oxide whiskers, utilizing their filling effect, in conjunction with microcrystalline cellulose fibers and polyester fibers, further improves the impact resistance and strength of the color steel plate, extending its service life.

[0025] Preferably, the polycaprolactone-modified microcrystalline cellulose fiber is made from microcrystalline cellulose fiber and polycaprolactone solution in a mass ratio of 1:0.1-0.3.

[0026] By adopting the above technical solution, microcrystalline cellulose fibers and polycaprolactone solution are combined. The bonding and cross-linking effect of polycaprolactone solution and toughening coating improves the bonding stability between polycaprolactone-modified microcrystalline cellulose fibers and toughening coating. In addition, polycaprolactone has a certain degree of flexibility, which can buffer the brittleness of microcrystalline cellulose fibers. Combined with the flexibility of polyester fibers, a cross-linking network is formed. When covered with fluorocarbon coating, it has good adsorption effect and high adhesion, which improves the impact resistance of color steel plate and extends the service life of color steel plate.

[0027] Preferably, the calcium oxide whisker modified polyester fiber is made of polyester fiber, sodium polyacrylate solution and calcium oxide whiskers in a mass ratio of 1:0.1-0.2:0.05-0.1.

[0028] By adopting the above technical solution, sodium polyacrylate slowly dissolves in water, allowing calcium oxide whiskers to slowly come into contact with the fluorocarbon coating. During the curing process of the fluorocarbon coating, due to the long curing time, sodium polyacrylate can gradually dissolve, thereby gradually exposing the calcium oxide whiskers. The gradually exposed calcium oxide whiskers react with the moisture in the fluorocarbon coating, releasing heat and accelerating the internal curing of the fluorocarbon coating.

[0029] Because fluorocarbon coatings have a long curing time, they are prone to uneven curing, leading to cracks and bubbles, especially under high ambient temperatures. The gradual exothermic reaction of calcium oxide whiskers allows for more even curing of the fluorocarbon coating, reducing cracks and bubbles, and improving adhesion to the steel plate surface. This, in turn, enhances the strength and impact resistance of the color-coated steel plate.

[0030] The calcium oxide whiskers are small, and the sodium polyacrylate gradually releases the calcium oxide whiskers into contact with moisture. With the appropriate amount of calcium oxide whiskers added, it is easy to control the exothermic temperature and avoid generating too much heat that could affect the adhesion stability of the coating. Meanwhile, the microcrystalline cellulose fiber and polyester fiber have good thermal insulation properties, which, combined with the heat resistance of polyurethane, protect the toughened coating from the exothermic effects of the calcium oxide whiskers.

[0031] Preferably, the water-based fluorocarbon coating comprises the following raw materials in parts by weight:

[0032] 80-100 parts fluorocarbon liquid, 1-2 parts silica, 0.5-1 part film-forming agent, 1-2 parts pigment, 0.5-1 part thickener, 1-3 parts porous heat-insulating filler, 20-30 parts water, 2-8 parts curing agent, 0.5-1 part leveling agent, and 0.2-0.5 parts defoamer.

[0033] By adopting the above technical solution, the high strength of silica is utilized to improve the strength of water-based fluorocarbon coatings. Combined with porous heat-insulating fillers, the high temperature of the external environment is prevented from affecting the curing of fluorocarbon coatings, reducing the generation of cracks and pores during the curing process. Combined with film-forming agents, the fluorocarbon coatings have good film-forming stability, improving the strength of color steel plates and extending their durability.

[0034] Preferably, the porous thermal insulation filler is made of porous perlite and shellac solution in a mass ratio of 1:0.2-0.4.

[0035] By adopting the above technical solution, the heat insulation effect of porous perlite and shellac liquid can prevent the high temperature of the external environment from affecting the curing of fluorocarbon resin. Furthermore, shellac is waterproof and can resist the influence of external humidity, improving the water resistance and high temperature resistance of the fluorocarbon coating. In addition, the porous structure can further improve the UV resistance of the color steel plate by reflecting and refracting ultraviolet rays, thus extending the service life of the color steel plate.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. After pretreatment, the surface roughness of the steel plate increases, which facilitates the adhesion of toughening coatings, fibers, and fluorocarbon coatings, improving adhesion stability. The toughening coating formed by the toughening coating and the good toughness of the porous toughening fibers enhance the impact resistance of the color steel plate surface coating. The environmentally friendly effect of water-based fluorocarbon coatings gives the color steel plate the advantage of low VOCs. Furthermore, the coating can stably bond to the surface of the fibers and toughening coating, improving the adhesion stability of the coating on the steel plate surface. At the same time, the fluorocarbon coating has ultra-long weather resistance, high stain resistance, high corrosion resistance, and low friction, making the color steel plate resistant to acid rain and ultraviolet corrosion, easy to clean, and thus extending the service life of the color steel plate.

[0038] 2. The combination of modified polyetheretherketone, modified carbon nanotubes, calcium oxide whisker modified polyester fiber, and polycaprolactone modified microcrystalline cellulose fiber gives the corrugated top surface of the color steel plate high impact resistance, making it less susceptible to cracking caused by external sand and dust particles, thus ensuring a long service life for the color steel plate.

[0039] 3. Porous tough fibers have a porous nature, which, combined with the porous effect of silk fibroin fibers, further adsorbs VOCs, ensuring the environmental protection effect of color steel plates. Detailed Implementation

[0040] The present application will be further described in detail below with reference to the embodiments.

[0041] Preparation example of toughening coating

[0042] The polyetheretherketone (PEEK) microparticles in the following raw materials were purchased from Vigers UK, model F806; other raw materials are commercially available.

[0043] Preparation Example 1: The toughening coating was prepared by the following method:

[0044] 0.15 kg of polyethylene glycol solution was uniformly sprayed onto the surface of 1 kg of polyetheretherketone (PEEK) microparticles, followed by the addition of 0.2 kg of silk fibroin fiber. The average particle size of the PEEK microparticles was 5 μm. The polyethylene glycol solution was a 3% (w / w) aqueous solution of polyethylene glycol, and the polyethylene glycol was polyethylene glycol 8000. The average length of the silk fibroin fiber was 3 μm. The silk fibroin fiber was added at a rate of 60 g / min. During the addition process, the PEEK microparticles were stirred at a speed of 80 r / min. After uniform mixing, the mixture was dried and dispersed to obtain modified PEEK with an average particle size of 10 μm.

[0045] 1 kg of carbon nanotubes and 1 kg of nano-silica were added to 18 kg of silane coupling agent KH-550 and ultrasonically dispersed at 20 kHz for 30 min. Then, the carbon nanotubes were separated, dried, and dispersed to obtain modified carbon nanotubes. The average length of the carbon nanotubes was 10 μm and the average particle size of the nano-silica was 80 nm.

[0046] Weigh 90 kg of waterborne polyurethane, 8 kg of modified polyether ether ketone, and 3 kg of modified carbon nanotubes, mix and stir evenly. Add 25 kg of curing agent (triethylenetetramine) as needed and mix and stir evenly to obtain a toughened coating.

[0047] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that:

[0048] 0.1 kg of polyethylene glycol solution was uniformly sprayed onto the surface of 1 kg of polyether ether ketone (PEEK) microparticles, and then 0.1 kg of silk fibroin fiber was added at a rate of 60 g / min. During the addition process, the PEEK microparticles were stirred at a speed of 80 r / min. After uniform mixing, the mixture was dried and dispersed to obtain modified PEEK.

[0049] Weigh 80 kg of waterborne polyurethane, 5 kg of modified polyether ether ketone, and 1 kg of modified carbon nanotubes, mix and stir evenly, add 20 kg of curing agent as needed, mix and stir evenly to obtain a toughened coating.

[0050] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that:

[0051] 0.2 kg of polyethylene glycol solution was uniformly sprayed onto the surface of 1 kg of polyetheretherketone (PEEK) microparticles, and then 0.3 kg of silk fibroin fiber was added at a rate of 60 g / min. During the addition process, the PEEK microparticles were stirred at a speed of 80 r / min. After uniform mixing, the mixture was dried and dispersed to obtain modified PEEK with an average particle size of 10 μm.

[0052] Weigh 100 kg of waterborne polyurethane, 10 kg of modified polyether ether ketone, and 4 kg of modified carbon nanotubes, mix and stir evenly, add 30 kg of curing agent as needed, mix and stir evenly to obtain a toughened coating.

[0053] Preparation example of polycaprolactone-modified microcrystalline cellulose fibers

[0054] The polycaprolactone in the following raw materials is PCL-1200; all other raw materials are commercially available.

[0055] Preparation Example 4: Polycaprolactone-modified microcrystalline cellulose fibers were prepared by the following method:

[0056] 0.2 kg of polycaprolactone solution was uniformly sprayed onto the surface of 1 kg of microcrystalline cellulose fiber, and then dried and dispersed to obtain polycaprolactone-modified microcrystalline cellulose fiber; the average length of the microcrystalline cellulose fiber was 100 μm, and the polycaprolactone solution was a 1% by mass polycaprolactone ethanol solution.

[0057] Preparation Example 5: The difference between this preparation example and Preparation Example 4 is that:

[0058] 0.1 kg of polycaprolactone solution was uniformly sprayed onto the surface of 1 kg of microcrystalline cellulose fiber, and then dried and dispersed to obtain polycaprolactone-modified microcrystalline cellulose fiber.

[0059] Preparation Example 6: The difference between this preparation example and Preparation Example 4 is that:

[0060] 0.3 kg of polycaprolactone solution was uniformly sprayed onto the surface of 1 kg of microcrystalline cellulose fiber, and then dried and dispersed to obtain polycaprolactone-modified microcrystalline cellulose fiber.

[0061] Preparation example of calcium oxide whisker modified polyester fiber

[0062] All of the following ingredients are commercially available.

[0063] Preparation Example 7: Calcium oxide whisker modified polyester fibers were prepared by the following method:

[0064] 0.1 kg of sodium polyacrylate solution was uniformly sprayed onto the surface of 0.1 kg of calcium oxide whiskers, and then dried and dispersed to obtain a mixture. 0.1 kg of sodium polyacrylate solution was uniformly sprayed onto the surface of 1 kg of polyester fiber, and then the mixture was added at a rate of 60 g / min. During the addition process, the polyester fiber was stirred at a speed of 80 r / min. After drying and dispersion, calcium oxide whisker-modified polyester fiber was obtained. The average length of the calcium oxide whiskers was 8 μm, the average length of the polyester fiber was 100 μm, and the average length of the calcium oxide whiskers was 10 μm. The sodium polyacrylate solution had a mass fraction of 1%, and the solvent was a 2% sodium hydroxide aqueous solution.

[0065] Preparation Example 8: The difference between this preparation example and Preparation Example 7 is that:

[0066] 0.05 kg of sodium polyacrylate solution was uniformly sprayed onto the surface of 0.05 kg of calcium oxide whiskers, and then dried and dispersed to obtain a mixture. 0.05 kg of sodium polyacrylate solution was uniformly sprayed onto the surface of 1 kg of polyester fiber, and then the mixture was added at a rate of 60 g / min. During the addition process, the polyester fiber was stirred at a speed of 80 r / min. After drying and dispersion, calcium oxide whisker modified polyester fiber was obtained.

[0067] Preparation example of waterborne fluorocarbon coatings

[0068] All of the following ingredients are commercially available.

[0069] Preparation Example 9: Waterborne fluorocarbon coatings were prepared using the following method:

[0070] 0.4 kg of shellac solution was uniformly sprayed onto the surface of 1 kg of porous perlite, and then dried and dispersed to prepare a porous heat-insulating filler. The average particle size of the porous perlite was 80 μm, and the shellac solution was a 1% shellac ethanol solution by mass.

[0071] Weigh out 100 kg of fluorocarbon liquid, 2 kg of silica, 1 kg of film-forming agent, 2 kg of pigment, 1 kg of thickener, 3 kg of porous heat-insulating filler, 30 kg of water, 8 kg of curing agent, 1 kg of leveling agent, and 0.5 kg of defoamer for later use; the average particle size of silica is 40 μm, the film-forming agent is ethyl 3-ethoxypropionate, the pigment is titanium dioxide, the thickener is hydroxyethyl cellulose, the curing agent is diisocyanate, the leveling agent is silicone leveling agent, and the defoamer is silicone defoamer;

[0072] The fluorocarbon liquid, silica, film-forming agent, pigment, thickener, porous heat-insulating filler, water, leveling agent, and defoamer are mixed and stirred evenly. The curing agent is added and mixed evenly as needed to obtain a water-based fluorocarbon coating.

[0073] Preparation Example 10: Waterborne fluorocarbon coatings were prepared using the following method:

[0074] A porous heat-insulating filler is prepared by uniformly spraying 0.2 kg of shellac solution onto the surface of 1 kg of porous perlite, followed by drying and dispersion.

[0075] Weigh out 80 kg of fluorocarbon liquid, 1 kg of silicon dioxide, 0.5 kg of film-forming agent, 1 kg of pigment, 0.5 kg of thickener, 1 kg of porous heat insulation filler, 20 kg of water, 2 kg of curing agent, 0.5 kg of leveling agent, and 0.2 kg of defoamer, and set aside.

[0076] Example

[0077] Example 1: A preparation process for low-VOCs environmentally friendly color-coated steel sheets:

[0078] S1. After cleaning and removing contaminants from the steel plate surface, shot blasting is performed, followed by uniform spraying of polyvinyl alcohol solution for pretreatment. 20g of polyvinyl alcohol solution is sprayed per square meter of steel plate surface. The polyvinyl alcohol solution is a 1% (w / w) aqueous solution of polyvinyl alcohol. After pretreatment, the toughening coating prepared in Preparation Example 1 is uniformly sprayed onto the surface. Then, porous toughening fibers are added. The porous toughening fibers are prepared by uniformly mixing polycaprolactone-modified microcrystalline cellulose fibers prepared in Preparation Example 4 and calcium oxide whisker-modified polyester fibers prepared in Preparation Example 7 at a mass ratio of 1:1. After drying, the mixture is molded to obtain a semi-finished product. The top plane width of each corrugated surface on the semi-finished product is 3cm, the side plane widths are 6cm, the distance between the top plane and the side planes is 3cm, and the tilt angle is 45 degrees, forming an overlapping roof panel shape.

[0079] S2. The water-based fluorocarbon coating prepared in Example 9 is uniformly sprayed onto the surface of the semi-finished product for the first time. After drying, the water-based fluorocarbon coating is sprayed a second time. After drying, the water-based fluorocarbon coating is sprayed a third time. After drying, the finished product is obtained. In the finished product, the water-based fluorocarbon coating forms a fluorocarbon layer after curing. The average thickness of the fluorocarbon layer is 0.4 mm. The average thickness of the toughening layer formed by the toughening coating is 0.1 mm. The average thickness of the steel plate is 0.8 mm. The average thickness of the finished color steel plate is 1.5 mm.

[0080] Example 2: The difference between this example and Example 1 is that:

[0081] S1. After the pretreatment is completed, the toughening coating prepared in Preparation Example 2 is uniformly sprayed on the surface, and then porous toughening fibers are added. The porous toughening fibers are prepared by uniformly mixing polycaprolactone-modified microcrystalline cellulose fibers prepared in Preparation Example 5 and calcium oxide whisker-modified polyester fibers prepared in Preparation Example 8 in a mass ratio of 1:1. After drying, the mixture is molded to obtain a semi-finished product.

[0082] S2. The water-based fluorocarbon coating prepared in Example 10 is uniformly sprayed onto the surface of the semi-finished product for the first time, and dried. Then, the water-based fluorocarbon coating is sprayed a second time, dried, and then sprayed a third time. After drying, the finished product is obtained.

[0083] Example 3: The difference between this example and Example 1 is that:

[0084] S1. After the pretreatment is completed, the toughening coating prepared in Preparation Example 3 is uniformly sprayed on the surface, and then porous toughening fibers are added. The porous toughening fibers are prepared by uniformly mixing polycaprolactone-modified microcrystalline cellulose fibers prepared in Preparation Example 6 and calcium oxide whisker-modified polyester fibers prepared in Preparation Example 7 at a mass ratio of 1:2. After drying, the mixture is molded to obtain a semi-finished product.

[0085] S2. The water-based fluorocarbon coating prepared in Example 9 is uniformly sprayed onto the surface of the semi-finished product for the first time, and dried. Then, the water-based fluorocarbon coating is sprayed a second time, dried, and then sprayed a third time. After drying, the finished product is obtained.

[0086] Example 4: The difference between this example and Example 1 is that:

[0087] No polyvinyl alcohol solution was added during the pretreatment process.

[0088] Example 5: The difference between this example and Example 1 is that:

[0089] In the preparation of toughening coatings, the modified polyether ether ketone is replaced with an equal mass of rosin resin.

[0090] Example 6: The difference between this example and Example 1 is that:

[0091] In the preparation of the toughening coating, the modified carbon nanotubes were replaced with polypropylene particles of equal mass, with an average particle size of 10 μm.

[0092] Example 7: The difference between this example and Example 1 is that:

[0093] The porous toughened fiber is a microcrystalline cellulose fiber.

[0094] Example 8: The difference between this example and Example 1 is that:

[0095] In porous toughening fibers, the calcium oxide whisker-modified polyester fibers are replaced with an equal mass of polyester fibers.

[0096] Example 9: The difference between this example and Example 1 is that:

[0097] No porous heat-insulating filler was added during the preparation of the water-based fluorocarbon coating.

[0098] Example 10: The difference between this example and Example 1 is that:

[0099] The porous heat-insulating filler in water-based fluorocarbon coatings is porous perlite.

[0100] Comparative Example

[0101] Comparative Example 1: The difference between this comparative example and Example 1 is that:

[0102] S1. After pretreatment, the material is molded and then the toughening coating prepared in Preparation Example 1 is uniformly sprayed onto the surface. Then, porous toughening fibers are added. The porous toughening fibers are prepared by uniformly mixing polycaprolactone-modified microcrystalline cellulose fibers prepared in Preparation Example 4 and calcium oxide whisker-modified polyester fibers prepared in Preparation Example 7 at a mass ratio of 1:1 to obtain a semi-finished product.

[0103] Comparative Example 2: This comparative example differs from Example 1 in that:

[0104] No toughening coating or porous toughening fibers were added to the surface of the steel plate.

[0105] Performance testing

[0106] 1. Surface performance testing

[0107] Color steel sheets were prepared using the preparation methods of Examples 1-3, 8, 9 and Comparative Example 1, respectively. The complete drying time of the fluorocarbon coating formed on the surface of the color steel sheet was tested under the conditions of ambient temperature 28°C and relative humidity 55%.

[0108] Furthermore, in accordance with GB / T12755-2008, the UV radiation resistance was tested using UVB-313 for 600 hours. The presence of bubbles, cracks, or other damage was observed, and the damaged area was recorded.

[0109] Simultaneously measure the average difference in coating thickness between the top plane of the corrugated surface and the two side planes of the corrugated surface, and record the data.

[0110] 2. Mechanical performance testing

[0111] Color steel sheets were prepared using the preparation methods of Examples 1-10 and Comparative Examples 1-2, respectively, and the coating adhesion was tested in accordance with GB / T9286-1998.

[0112] In accordance with GB / T1732-1993, the impact resistance of the corrugated top plane of the color steel plate was tested. A 1kg hammer was dropped freely from a height of 50cm 30 times using an impact tester, and the crack area of ​​the coating on the surface of the color steel plate was recorded.

[0113] According to GB / T12755-2008, the wear resistance was tested by rubbing for 500 cycles under 200N conditions, and the wear mass was recorded.

[0114] 3. High temperature resistance test

[0115] Color steel sheets were prepared using the preparation methods of Examples 1-3 and 8-10, respectively. The color steel sheets were exposed to the sun for 24 hours at an external temperature of 42°C and a relative humidity of 50%. The presence of bubbles, cracks, or other damage was observed, and the damaged area was recorded.

[0116] 4. Water resistance test

[0117] Color steel sheets were prepared using the preparation methods of Examples 1-3 and 10, respectively. Water was continuously sprayed onto the fluorocarbon coating surface of the color steel sheet. After 240 hours of water spraying treatment, the cracking and bubbling of the coating surface of the color steel sheet were observed and the area was recorded.

[0118] Table 1 Performance Test Table (In the table, " / " indicates that the corresponding embodiment or comparative example did not test this item, so there is no data)

[0119]

[0120]

[0121] As can be seen from Examples 1-3 and Table 1, the color steel plate prepared in this application has a shorter complete drying time, better UV resistance, better surface flatness, a basic thickness difference between the top plane of the corrugation and the two sides of the corrugation, higher adhesion, and a smaller crack area, indicating better impact resistance; it also has better wear resistance, high temperature resistance, and water resistance.

[0122] Combining Examples 1 and 4-10 with Table 1, it can be seen that in Example 4, no polyvinyl alcohol solution was added during the pretreatment process. Compared with Example 1, the adhesion and impact resistance were worse. This indicates that the addition of polyvinyl alcohol solution can increase the adhesion of the toughening coating to the steel plate surface, and the stable adhesion of the coating improves the impact resistance of the color steel plate surface.

[0123] In Example 5, the modified polyetheretherketone was replaced with the same mass of rosin resin during the preparation of the toughening coating. Compared with Example 1, the adhesion and impact resistance of Example 5 were worse than those of Example 1. This indicates that rosin resin is brittle and is prone to cracking when the surface of the color steel plate is impacted, which affects the service life of the color steel plate. In contrast, the modified polyetheretherketone has high flexibility, which gives the corrugated top surface of the color steel plate better impact resistance.

[0124] In Example 6, the modified carbon nanotubes were replaced with polypropylene particles of the same mass during the preparation of the toughening coating. Compared with Example 1, the adhesion and impact resistance of Example 6 were worse than those of Example 1. This indicates that the polypropylene particles are lightweight and have a lower density than the modified carbon nanotubes, making them easier to adhere to the surface of the toughening coating and affecting the adhesion and impact resistance.

[0125] Example 7 uses microcrystalline cellulose fiber as the porous toughening fiber. Compared with Example 1, the impact resistance of Example 7 is worse than that of Example 1. This indicates that the impact resistance of adding a single microcrystalline cellulose fiber is worse than that of adding a combination of microcrystalline cellulose fiber and polyester fiber, thus affecting the impact resistance of the color steel plate surface.

[0126] In Example 8, the porous toughening fiber was replaced with an equal mass of polyester fiber to replace the calcium oxide whisker modified polyester fiber. Compared with Example 1, the drying time of Example 8 was longer than that of Example 1, and the high-temperature damage area was larger than that of Example 1. This indicates that calcium oxide whiskers can accelerate the complete drying time of fluorocarbon coatings and reduce the problem of bubbles appearing due to the surface drying of fluorocarbon coatings but the interior not drying due to high external environmental temperatures.

[0127] In Example 9, no porous heat-insulating filler was added during the preparation of the water-based fluorocarbon coating. Compared with Example 1, Example 9 had a larger area resistant to UV damage, a larger area resistant to impact cracking, a larger abrasion loss, and a larger area resistant to high-temperature damage than Example 1. This indicates that the addition of porous heat-insulating filler can block the influence of high external environmental temperature on the curing of fluorocarbon coating, thereby ensuring the high-temperature resistance of the coating on the surface of the color steel plate.

[0128] In Example 10, the porous heat-insulating filler in the water-based fluorocarbon coating is porous perlite. Compared with Example 1, Example 10 has a greater wear rate, a larger high-temperature damage area, and poorer water resistance than Example 1. This indicates that the water-repellent properties of shellac make the porous perlite less prone to water absorption, thus ensuring the water resistance of the coating on the color steel plate surface.

[0129] Based on Example 1 and Comparative Examples 1-2, and referring to Table 1, it can be seen that in Comparative Example 1, the steel plate surface was first molded and then sprayed with toughening coating and porous toughening fibers. Compared with Example 1, the uniformity difference of Comparative Example 1 was greater, the adhesion was worse, and the impact resistance was worse. This indicates that molding first and then bonding fibers can easily lead to inconsistent coating and fiber thickness between the top plane of the corrugated surface and the two side planes of the corrugated surface during the coating curing process, affecting the impact resistance of the top plane of the corrugated surface.

[0130] Comparative Example 2 steel plate surface without toughening coating and porous toughening fiber. Compared with Example 1, Comparative Example 2 has poorer adhesion and larger crack area. This shows that the combination of toughening coating and porous toughening fiber can improve impact resistance and adhesion.

[0131] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A manufacturing process for low-VOCs environmentally friendly color-coated steel sheets, characterized in that, Includes the following steps: S1. After shot blasting of the steel plate, a polyvinyl alcohol solution is uniformly sprayed on it, followed by a toughening coating and porous toughening fibers uniformly sprayed on the surface. After drying, it is molded to obtain a semi-finished product. The toughening coating contains the following raw materials in parts by weight: 80-100 parts of waterborne polyurethane, 5-10 parts of modified polyetheretherketone, 1-4 parts of modified carbon nanotubes, and 20-30 parts of curing agent. The modified polyetheretherketone is prepared from polyetheretherketone microparticles, polyethylene glycol solution, and silk fibroin fibers in a mass ratio of 1:0.1-0.2:0.1-0.

3. Modified carbon nanotubes are prepared by soaking and dispersing carbon nanotubes in a composite solution of silica and silane coupling agent; porous toughened fibers are composed of polycaprolactone-modified microcrystalline cellulose fibers and calcium oxide whisker-modified polyester fibers in a mass ratio of 1:1-2. S2. Spray water-based fluorocarbon coating evenly onto the surface of the semi-finished product, and dry it to obtain the finished product. The water-based fluorocarbon coating contains the following raw materials in parts by weight: 80-100 parts fluorocarbon liquid, 1-2 parts silica, 0.5-1 parts film-forming agent, 1-2 parts pigment, 0.5-1 parts thickener, 1-3 parts porous heat-insulating filler, 20-30 parts water, 2-8 parts curing agent, 0.5-1 parts leveling agent, and 0.2-0.5 parts defoamer. The porous heat-insulating filler is made of porous perlite and shellac liquid in a mass ratio of 1:0.2-0.

4.

2. The preparation process of a low-VOCs environmentally friendly color-coated steel sheet according to claim 1, characterized in that, The polycaprolactone-modified microcrystalline cellulose fiber is made from microcrystalline cellulose fiber and polycaprolactone solution in a mass ratio of 1:0.1-0.

3.

3. The preparation process of a low-VOCs environmentally friendly color-coated steel sheet according to claim 1, characterized in that, The calcium oxide whisker modified polyester fiber is made of polyester fiber, sodium polyacrylate solution and calcium oxide whiskers in a mass ratio of 1:0.1-0.2:0.05-0.1.

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