Waterborne polyurethane coating with low surface energy, fire retardant and preparation method thereof

Abstract

The application discloses a fireproof and flame-retardant coating, which comprises, in parts by weight, 80-100 parts of organic silicon modified water-based polyurethane, 2-5 parts of zirconium phosphate-platinum catalyst, 5-10 parts of mica powder and 5-10 parts of silicon dioxide. The application further discloses a preparation method of the fireproof and flame-retardant coating. The fireproof and flame-retardant coating has the characteristics of low surface energy, fireproof and flame-retardant due to the low surface energy of organic silicon, the introduction of silicon into the polyurethane base material, the catalytic effect of ZrP-Pt, the catalytic characteristics of zirconium phosphate, the porcelain characteristics of platinum, the interlayer structure of zirconium phosphate, the solidification of platinum compounds, the introduction of phosphorus elements, the carbon change of organic matter into amorphous carbon, the formation of a carbon layer, the support of the mica powder, the maintenance of the integrity of the ceramic structure and the synergistic effect of the coating.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a waterborne polyurethane coating with low surface energy and fire retardancy, and its preparation method. Background Technology

[0002] Coatings with low surface free energy and high water contact angles make it difficult for liquids to adhere to or penetrate the substrate surface; these are called low surface energy antifouling coatings. In the industrial field, antifouling coatings have good practical performance and low cost, showing great development potential. Currently, organofluorine and organosilicon are two commonly used antifouling coatings, with organosilicon being more environmentally friendly than organofluorine. Thanks to the unique molecular chain structure of organosilicon, these materials have good thermal stability, good water resistance, and excellent flexibility. However, pure organosilicon materials have low mechanical strength, limiting their application scenarios. Therefore, it is often necessary to copolymerize and modify organosilicon to improve its performance, creating high-performance low surface energy coating polymers.

[0003] Waterborne polyurethane is an environmentally friendly new material that retains the wear resistance of solvent-based polyurethane while possessing low VOC content, making it widely applicable in various fields. However, the introduction of hydrophilic groups to achieve a self-emulsifying effect results in a hydrophilic surface, reducing overall water resistance and limiting its further promotion. By copolymerizing and chemically bonding organosilicon into the structure, organosilicon-modified waterborne polyurethane composite coatings are obtained. This introduces hydrophobic organosilicon segments into the structure, reducing the surface free energy and enhancing water resistance, thus combining the excellent mechanical properties of polyurethane with the outstanding water resistance of organosilicon. Therefore, organosilicon-modified polyurethane coatings have significant research value and application potential.

[0004] However, due to the inherent molecular structure of polyurethane, it is extremely flammable, which greatly limits its application prospects. Especially in industrial and home decoration fields, coatings are required not only to have flame-retardant properties but also to have certain fire-resistant properties to prevent further damage to internal materials from flames. How to maintain the excellent properties of polyurethane while also ensuring its excellent flame-retardant and fire-resistant performance has been a hot research topic in this field. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the main objective of this invention is to provide a waterborne polyurethane coating with low surface energy and fire-retardant properties, and a method for preparing the same.

[0006] The objective of this invention is achieved through the following technical solution: A waterborne polyurethane coating with low surface energy and fire retardancy comprises, by weight, 80-100 parts of silicone-modified waterborne polyurethane, 2-5 parts of zirconium phosphate-platinum catalyst, 5-10 parts of mica powder, and 5-10 parts of silica.

[0007] In some specific embodiments, the zirconium phosphate-platinum catalyst is prepared by the following method: S1) Swelling and alcoholization treatment of zirconium phosphate: The purification agent aqueous solution and zirconium phosphate solution are stirred and mixed evenly to obtain a swollen gelled solution of zirconium phosphate; S2) Preparation of zirconium phosphate-platinum catalyst: Add aqueous chloroplatinic acid to zirconium phosphate swelling gel solution, sonicate until chloroplatinic acid is completely dissolved in zirconium phosphate swelling gel solution, then centrifuge, wash and dry the mixture to obtain zirconium phosphate-platinum catalyst.

[0008] In some specific embodiments, the mica powder is submicron mica powder, the particle size D50 of the mica powder is 0.8-1.5 micrometers, the D97 is 2.5-3.5 micrometers, and the silica is fumed silica.

[0009] In some specific embodiments, the preparation method of the organosilicon-modified waterborne polyurethane includes the following steps: 1) Polyol and organosilicon are premixed, and then isocyanate, 2,2-dimethylolpropionic acid (DMPA) and catalyst (DBTDL) are added. The prepolymerization reaction is carried out under stirring to obtain polyurethane prepolymer. 2) Cool the polyurethane prepolymer from step 1) to room temperature, add acrylic monomer and triethylamine, adjust the pH of the reaction system to neutral, add ethylenediamine (EDA) and deionized water, and disperse evenly by high-speed mechanical dispersion to obtain a pre-emulsion. 3) Add an initiator to the pre-emulsion in step 2) and continue stirring the polymerization reaction to obtain silicone-modified waterborne polyurethane.

[0010] In some specific embodiments, the organosilicon-modified waterborne polyurethane comprises, by weight: 1-10 parts of polyol, 1-15 parts of organosilicon, 1-10 parts of isocyanate, 10-20 parts of 2,2-dimethylolpropionic acid, 0.05-0.1 parts of catalyst, 2-20 parts of acrylic monomer, 10-20 parts of triethylamine, 1-10 parts of ethylenediamine, 20-50 parts of deionized water, and 0.01-1 parts by weight of initiator.

[0011] In some specific embodiments, the polyol includes, but is not limited to, at least one of polycarbonate diol (PCDL-1000), polyacrylol (PPG-1000), and polyacrylol (PPG-2000).

[0012] In some specific embodiments, the organosilicon includes, but is not limited to, at least one of hydroxypropyl-terminated polydimethylsiloxane (PDMS), γ-aminopropyltriethoxysilane (KH550), and γ-glycidoxypropyltrimethoxysilane (KH560).

[0013] In some specific embodiments, the isocyanate includes, but is not limited to, at least one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), and diphenylmethane diisocyanate (MDI).

[0014] In some specific embodiments, the acrylic monomer includes, but is not limited to, at least one of methyl acrylate (MA) or butyl acrylate (BA); the catalyst includes, but is not limited to, dibutyltin dilaurate; and the initiator includes, but is not limited to, potassium persulfate.

[0015] In some specific embodiments, the premixing conditions in step 1) are: under a nitrogen protective atmosphere, at a temperature of 110-130℃ and a vacuum degree of 0.06-0.08MPa, water is removed for 1-3 hours; the prepolymerization reaction conditions in step 1) are: a prepolymerization reaction temperature of 70-90℃ and a time of 1-3 hours; the polymerization reaction conditions in step 3) are: a polymerization reaction time of 70-90℃ and a time of 4-6 hours.

[0016] Compared with the prior art, the present invention has at least the following advantages: 1) This invention successfully introduces hydrophobic segments of organosilicon into the structure, reduces the free energy of the coating surface, and enhances the water resistance of the surface, so that the prepared organosilicon-modified polyurethane polymer not only has the excellent mechanical properties of polyurethane, but also the excellent water resistance of organosilicon. 2) The zirconium phosphate-platinum catalyst in this invention not only introduces phosphorus into the system to increase the flame retardancy of the coating, but also improves the stability of platinum after it is immobilized on ZrP. The larger interlayer structure and specific surface area of ​​zirconium phosphate make it easier to adsorb and decompose free silicon. The adsorbed free silicon, under the co-catalysis of the pre-intercalated Pt zirconium phosphate, more easily forms a SIOC ceramic structure. The layered structure of zirconium phosphate supplements the structural strength of mica powder, further increasing the stability of the ceramic body. This allows the coating to form a dense ceramic protective layer when exposed to fire, preventing damage to the internal structure or components of the coating from the flame. In other words, the synergistic effect between Si-WPU, ZrP-Pt, mica powder, and silica in this application results in a waterborne polyurethane coating with excellent flame retardant and fire-resistant properties.

[0017] 3) In the fire-retardant waterborne polyurethane coating provided by the present invention, the addition of silica and mica powder is beneficial to the stability and density of the ceramic structure and protects the stability of the carbon layer structure. At the same time, silica can provide the silicon required for ceramic formation to form SIOC ceramics. Meanwhile, the hardness of inorganic materials can also increase the wear resistance of the coating.

[0018] 4) The fire-retardant waterborne polyurethane coating provided by this invention utilizes the low surface energy of organosilicon to impart a low surface energy effect to the waterborne composite polyurethane. Simultaneously, silicon is introduced into the polyurethane substrate, and together with the fumed silica in the composite material, under the catalytic action of ZrP-Pt, in the silicon-containing system, the unique interlayer structure of zirconium phosphate is used to immobilize platinum compounds, introduce phosphorus elements, and increase flame retardancy. The catalytic properties of zirconium phosphate enhance the ceramic-forming properties of platinum. By promoting cross-linking and capturing active free radicals in the solid phase, it exhibits excellent catalytic ceramic-forming properties, and its carbon-fixing effect retards flames upon contact with fire, forming a ceramic structure. ZrP-Pt can transform the carbon in organic matter into amorphous carbon that remains in the matrix, forming a carbon layer that provides flame retardancy. Mica powder acts as a skeletal support, maintaining the integrity of the ceramic structure. Submicron particle size is preferred to ensure the coating's fineness and facilitate construction and application. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0020] Figure 1 The image shows the FTIR-ATR spectrum of the film formed by the organosilicon-modified waterborne polyurethane in Example 1 of this invention. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific accompanying drawings and embodiments. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.

[0022] When a quantity, concentration or other value or parameter is expressed as a range, preferred range, or preferred upper and lower limits, it should be understood as specifically revealing any range by combining any pair of upper or preferred values ​​with any lower or preferred values, without regard to that point and all integers and fractions within that range.

[0023] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.

[0024] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.

[0025] In the following embodiments, the mica powder is submicron mica powder, and the particle size D50 of the mica powder is 0.8-1.5 micrometers, and the D97 is 2.5-3.5 micrometers. The silica is fumed silica.

[0026] Example 1

[0027] This embodiment provides a method for preparing a waterborne polyurethane coating with low surface energy and fire retardancy, which includes the following steps: 1) Preparation of organosilicon-modified waterborne polyurethane Si-WPUA First, 1g PPG-1000 and 1.5g PDMS were added to the reaction vessel and dehydrated at (120±1)℃ and 0.07MPa for 2 hours under a nitrogen atmosphere. After the water was removed, 5g IPDI, 10g DMPA and 0.05g DBTDL were added. After mechanical stirring and mixing, the mixture was reacted at 80℃ for 2 hours to prepare a polyurethane prepolymer. Then, the mixture was cooled to room temperature, 1g MA and 1g BA were added and stirred, and then 10g TEA was added to adjust the pH of the system to neutral. 1g EDA and 20g deionized water were added while stirring at 1000r / min. After high-speed mechanical dispersion for 1 hour, 0.01g potassium persulfate was added and the mixture was stirred and reacted at 70℃ for 4 hours to obtain silicone-modified waterborne polyurethane Si-WPUA. (ii) Preparation of zirconium phosphate-platinum catalyst ZrP-Pt 1) Swelling and alcoholization treatment of zirconium phosphate: Dissolve 20g of ethanolamine in 100ml of distilled water, and then stir at 200r / min to obtain an alcoholization agent aqueous solution, which is then left to stand for later use; dissolve 7g of zirconium phosphate powder in distilled water (the solid-liquid ratio of the zirconium phosphate solution is 10ml / g), and then stir at 200r / min. Then pour the zirconium phosphate solution into the aforementioned alcoholization agent aqueous solution, and sonicate at 100W for 30min to obtain a swollen and gelled zirconium phosphate solution; 2) Preparation of zirconium phosphate-platinum catalyst ZrP-Pt: Take 0.26g of chloroplatinic acid aqueous solution (mass concentration of 0.2g / g) into zirconium phosphate swelling gelling solution (mass ratio of chloroplatinic acid aqueous solution to zirconium phosphate swelling gelling solution is 1:800), and sonicate at 150W power for 30min until chloroplatinic acid is completely dissolved in zirconium phosphate swelling gelling solution. Then centrifuge, wash and dry the mixture to obtain the product, which is zirconium phosphate-platinum catalyst ZrP-Pt. (iii) Preparation of waterborne polyurethane coatings with low surface energy and fire-retardant properties After mixing and stirring 80g of Si-WPU, 2g of ZrP-Pt, 5g of mica powder, and 5g of silica evenly, a waterborne polyurethane coating with low surface energy and fire retardancy is obtained.

[0028] The prepared waterborne polyurethane coating with low surface energy and fire retardancy was poured into a polytetrafluoroethylene mold and dried in a 40ºC forced-air drying oven for 1 hour. Then the cured film was dried in a 70℃ vacuum oven for 2 hours to obtain a waterborne polyurethane coating film with low surface energy and fire retardancy.

[0029] Example 2

[0030] This embodiment provides a method for preparing a waterborne polyurethane coating with low surface energy and fire retardancy, which includes the following steps: 1) Preparation of organosilicon-modified waterborne polyurethane Si-WPUA First, 10g of PCDL-1000 and 11g of KH550 were added to the reaction vessel and dehydrated at (120±1)℃ and 0.07MPa for 2 hours under a nitrogen protective atmosphere. After the water was removed, 10g of MDI, 20g of DMPA and 0.10g of DBTDL were added. After mechanical stirring and mixing, the mixture was reacted at 90℃ for 2 hours to prepare a polyurethane prepolymer. Then, the mixture was cooled to room temperature, and 10g of MA and 10g of BA were added and stirred. Then, 20g of TEA was added and the pH of the system was adjusted to neutral. 10g of EDA and 50g of deionized water were added while stirring at 1000r / min. After high-speed mechanical dispersion for 1 hour, 1g of potassium persulfate was added and the mixture was stirred and reacted at 90℃ for 4 hours to obtain silicone-modified waterborne polyurethane Si-WPUA. (ii) Preparation of zirconium phosphate-platinum catalyst ZrP-Pt (1) Swelling and alcoholization treatment of zirconium phosphate: Dissolve 20g of ethanolamine in 100ml of distilled water, and then stir at 500r / min to obtain an alcoholization agent aqueous solution, and let it stand for later use; dissolve 7g of zirconium phosphate powder in distilled water (the solid-liquid ratio of zirconium phosphate solution is 15ml / g), and then stir at 500r / min. Then pour the zirconium phosphate solution into the aforementioned alcoholization agent aqueous solution, and sonicate at 150W power for 60min to obtain a swollen gelled solution of zirconium phosphate.

[0031] (2) Preparation of zirconium phosphate-platinum catalyst ZrP-Pt: Take 0.26g of chloroplatinic acid aqueous solution (mass concentration of 0.2g / g) into zirconium phosphate swelling gel solution (mass ratio of chloroplatinic acid aqueous solution to zirconium phosphate swelling gel solution is 1:800), and sonicate at 250W power for 60min until chloroplatinic acid is completely incorporated into zirconium phosphate swelling gel solution. Then centrifuge, wash and dry the mixture to obtain the product, namely zirconium phosphate-platinum catalyst ZrP-Pt. (iii) Preparation of waterborne polyurethane coatings with low surface energy and fire-retardant properties After mixing and stirring Si-WPU: 100g; ZrP-Pt: 5g; mica powder: 10g; silica: 10g evenly, a water-based polyurethane coating with low surface energy and fire retardant properties is produced. The waterborne polyurethane coating with low surface energy and fire retardancy prepared in this embodiment was poured into a polytetrafluoroethylene mold and dried in a 40ºC forced-air drying oven for 1 hour. Then the cured film was dried in a 70ºC vacuum oven for 2 hours to obtain a waterborne polyurethane coating film with low surface energy and fire retardancy.

[0032] Example 3

[0033] This embodiment provides a method for preparing a waterborne polyurethane coating with low surface energy and fire retardancy, which includes the following steps: 1) Preparation of organosilicon-modified waterborne polyurethane Si-WPUA First, 5g PPG-2000 and 6g KH560 were added to the reaction vessel and dehydrated at (120±1)℃ and 0.07MPa for 2 hours under a nitrogen protective atmosphere. After the water was removed, 10g TDI, 10g DMPA and 0.08g DBTDL were added. After mechanical stirring and mixing, the mixture was reacted at 70℃ for 3 hours to prepare a polyurethane prepolymer. Then, the mixture was cooled to room temperature, 5g MA and 3g BA were added and stirred, and then 10g TEA was added to adjust the pH of the system to neutral. 3g EDA and 40g deionized water were added while stirring at 1000r / min. After high-speed mechanical dispersion for 1 hour, 0.5g potassium persulfate was added and the mixture was stirred and reacted at 70℃ for 6 hours to obtain silicone-modified waterborne polyurethane Si-WPUA. (ii) Preparation of zirconium phosphate-platinum catalyst ZrP-Pt (1) Swelling and alcoholization treatment of zirconium phosphate: Dissolve 20g of isopropanolamine in 100ml of distilled water, and then stir at 600r / min to obtain an alcoholization agent aqueous solution, and let it stand for later use; dissolve 11g of zirconium phosphate powder in distilled water (the solid-liquid ratio of zirconium phosphate solution is 20ml / g), and then stir at 600r / min. Then pour the zirconium phosphate solution into the aforementioned alcoholization agent aqueous solution, and sonicate at 300W power for 45min to obtain a swollen gelled zirconium phosphate solution.

[0034] (2) Preparation of zirconium phosphate-platinum catalyst ZrP-Pt: Take 0.13g of chloroplatinic acid aqueous solution (mass concentration of 0.2g / g) into zirconium phosphate swelling gel solution (mass ratio of chloroplatinic acid aqueous solution to zirconium phosphate swelling gel solution is 1:800), and sonicate at 600W power for 45min until chloroplatinic acid is completely incorporated into zirconium phosphate swelling gel solution. Then centrifuge, wash and dry the mixture to obtain the product, namely zirconium phosphate-platinum catalyst ZrP-Pt. (iii) Preparation of waterborne polyurethane coatings with low surface energy and fire retardancy; After mixing and stirring Si-WPU: 80g; ZrP-Pt: 2g; mica powder: 5g; silica: 5g evenly, a water-based polyurethane coating with low surface energy and fire retardant properties is produced. The waterborne polyurethane coating with low surface energy and fire retardancy prepared in this embodiment was poured into a polytetrafluoroethylene mold and dried in a 40ºC forced-air drying oven for 1 hour. Then the cured film was dried in a 70°C vacuum oven for 2 hours to obtain a waterborne polyurethane coating film with low surface energy and fire retardancy.

[0035] Comparative Example 1 This comparative example provides a method for preparing waterborne polyurethane WPUA, including the following steps: First, 1g of PPG-1000 and 1.5g of PDMS were added to the reaction vessel. Under a nitrogen protective atmosphere, the mixture was dehydrated at (120±1)℃ and 0.07MPa for 2 hours. After the water was completely removed, 5g of IPDI, 10g of DMPA and 0.05g of DBTDL were added. After mechanical stirring and mixing, the mixture was reacted at 80℃ for 2 hours to prepare a polyurethane prepolymer. Then, the mixture was cooled to room temperature, and 1g of MA and 1g of BA were added and stirred. Then, 10g of TEA was added and the pH of the system was adjusted to neutral. 1g of EDA and 20g of deionized water were added while stirring at 1000r / min. After high-speed mechanical dispersion for 1 hour, 0.01g of potassium persulfate was added and the mixture was stirred and reacted at 70℃ for 4 hours to obtain silicone-modified waterborne polyurethane Si-WPUA.

[0036] Comparative Example 2 This comparative example provides a method for preparing a waterborne polyurethane coating with low surface energy and fire retardancy, which is basically the same as that in Example 2, except that the polyurethane is not modified with organosilicon, that is, 11g of KH550 is not added when preparing the waterborne polyurethane in step one). The remaining steps two and three are the same as in Example 2, specifically: 1) Preparation of waterborne polyurethane WPUA First, 10g of PCDL-1000 was added to the reaction vessel and dehydrated for 2 hours at (120±1)℃ and 0.07MPa under a nitrogen atmosphere. After the water was removed, 10g of MDI, 20g of DMPA and 0.10g of DBTDL were added. After mechanical stirring and mixing, the mixture was reacted at 90℃ for 2 hours to prepare a polyurethane prepolymer. Then, the mixture was cooled to room temperature, and 10g of MA and 10g of BA were added and stirred. Then, 20g of TEA was added and the pH of the system was adjusted to neutral. 10g of EDA and 50g of deionized water were added while stirring at 1000r / min. After high-speed mechanical dispersion for 1 hour, 1g of potassium persulfate was added and the mixture was stirred and reacted at 90℃ for 4 hours to obtain silicone-modified waterborne polyurethane Si-WPUA. Comparative Example 3 This comparative example provides a method for preparing a waterborne polyurethane coating with low surface energy and fire retardancy, which is basically the same as that in Example 2, except that mica powder is not added, and steps one) and two) are the same as in Example 2, specifically: (iii) Preparation of waterborne polyurethane coatings with low surface energy and fire-retardant properties Mix 100g of Si-WPU, 5g of ZrP-Pt, and 10g of silica evenly, pour the mixture into a polytetrafluoroethylene mold, and dry it in a 40ºC forced-air drying oven for 1 hour. Then, dry the cured film in a 70℃ vacuum oven for 2 hours.

[0037] Comparative Example 4 This comparative example provides a method for preparing a waterborne polyurethane coating with low surface energy and fire retardancy, which is basically the same as that in Example 2, except that silica is not added, and steps one) and two) are the same as in Example 2, specifically: Mix 100g of Si-WPU, 5g of ZrP-Pt, and 10g of mica powder evenly, pour the mixture into a polytetrafluoroethylene mold, and dry it in a 40ºC forced-air drying oven for 1 hour. Then, dry the cured film in a 70℃ vacuum oven for 2 hours.

[0038] Comparative Example 5 This comparative example provides a method for preparing a waterborne polyurethane coating with low surface energy and fire retardancy, which is basically the same as that in Example 1, except that equal amounts of zirconium phosphate and chloroplatinic acid catalyst are directly added, instead of preparing a zirconium phosphate-platinum catalyst. Specifically, it includes the following steps: 1) Preparation of organosilicon-modified waterborne polyurethane Si-WPUA Same as Example 2 (ii) Preparation of fire-retardant waterborne polyurethane coatings Mix 100g of Si-WPU, 4.96g of zirconium phosphate, 0.04g of chloroplatinic acid, 10g of mica powder, and 10g of silica evenly, pour the mixture into a polytetrafluoroethylene mold, and dry it in a 40ºC forced-air drying oven for 1 hour. Then, dry the cured film in a 70℃ vacuum oven for 2 hours.

[0039] Performance test example: This application conducts performance tests on the waterborne polyurethane coatings with low surface energy and fire-retardant properties prepared in Examples 1-3 and Comparative Examples 1-5, specifically as follows: 1) Structural characterization This test uses Example 1 as an example to characterize the film formed by the prepared organosilicon-modified waterborne polyurethane using FTIR-ATR. The results are as follows: Figure 1 As shown in the figure, all spectral lines are located at 3327 cm⁻¹. -1 1700 cm -1 and 2850 cm -1 The broad absorption bands at these positions are due to the stretching vibrations of the NH bond, the C=O group in the urethane bond, and the CH2 and CH3 groups, respectively. The silicone-modified coating shows a similar absorption band at 1240 cm⁻¹. -1 1095cm -1 and 802cm -1 The positions correspond to the absorption peaks of Si-OC asymmetric stretching vibration, Si-O-Si stretching vibration, and Si-CH3 rocking vibration. In summary, the organosilicon-modified waterborne polyurethane WPUA was successfully prepared by the method described above.

[0040] 2) Chemical performance testing This application tests the performance of waterborne polyurethane coatings with low surface energy and fire retardancy prepared in Examples 1-3 and Comparative Examples 1-5. The fire retardancy performance was tested after calcining the samples in a muffle furnace at 1000°C for 1 hour. Integrity was assessed by visual inspection. The compressive strength of the ceramic-forming samples was tested according to GB / T 1041-2008. Other properties were tested after the coatings were dried, using standard samples. The oxygen index was tested according to GB / T 2406-2009, and the flame retardancy was tested according to UL 94. The contact angle was measured using a contact angle meter by adding a 2 μL water droplet to the surface. The results are shown in Table 1 below. Table 1 Performance data of the composite coatings prepared in Examples 1-7 and Comparative Example 1

[0041] As shown in Table 1, the fire-retardant waterborne polyurethane coating of this application can significantly improve the flame retardant performance of the coating after film formation by adding ZrP-Pt catalyst. The more ZrP-Pt catalyst is added, the better the flame retardant effect. Increasing the amount of mica powder can also increase the flame retardant performance. At the same time, it has a better ceramic effect and a denser coating, which can effectively prevent fire. Moreover, the addition of organosilicon-modified polyurethane can form a hydrophobic structure in the coating, which can improve the water contact angle of the coating film.

[0042] In addition, the fire-retardant waterborne polyurethane coating provided in this application has excellent flame-retardant and fire-resistant properties due to the synergistic effect between Si-WPU, ZrP-Pt, mica powder and silica. As can be seen from the data of Example 1 and Comparative Example 1, without the addition of functional additives and fillers such as ZrP-Pt, the coating has no flame-retardant and ceramic properties. Data from Example 2 and Comparative Example 2 show that without the addition of silane KH550, the contact angle of the coating is significantly reduced, its surface energy is high, and its water resistance is poor. Furthermore, the polyurethane chain segments lack silicon structures, resulting in decreased ceramic-forming properties. This is because, upon exposure to fire, the polymer degrades through combustion. Under the catalytic ceramic-forming action of ZrP-Pt, the absence of silicon in the chain segments prevents the formation of a SIOC ceramic structure, leading to poor ceramicization performance. This poor ceramic fire resistance also affects the overall flame-retardant effect. Data from Example 2 and Comparative Example 3 show that without the addition of mica powder, the ceramic-forming and flame-retardant effects deteriorate. This is because mica powder has a layered structure, which provides support and prevents structural collapse caused by the decomposition of organic matter during ceramic-forming, thus affecting the integrity of the ceramic formation. Poor ceramic-forming results consequently affect fire insulation and flame-retardant performance. Data from Example 2 and Comparative Example 4 show that without the addition of silica, the coating's processing performance is primarily affected, and its viscosity... The low viscosity leads to poor adhesion during coating. Secondly, silicon dioxide itself contains silicon, and silicon plays a synergistic role in flame retardancy. Adding it will improve the flame retardancy. According to the data from Example 2, Comparative Examples 3 and 4, it also helps with ceramic formation. This is because after the silicon-containing polyurethane organic matter decomposes when exposed to fire, the free silicon is more easily loaded and adsorbed onto silicon dioxide, thus forming a SIOC ceramic structure. According to the data from Example 2 and Comparative Example 5, although the direct addition of zirconium phosphate and chloroplatinic acid has a certain ceramic effect, the effect is poor. This is because chloroplatinic acid has poor stability and is prone to deterioration and failure when added directly. After being fixed on ZrP, its stability is better. The interlayer structure of zirconium phosphate is larger and the specific surface area is larger, making it easier to adsorb and decompose free silicon. When the adsorbed free silicon encounters zirconium phosphate that has been pre-intercalated with Pt, it is easier to form a SIOC ceramic structure. Zirconium phosphate has a layered structure, which supplements the structural strength of mica powder and further increases the stability of the ceramic body. The synergistic effect between Si-WPU, ZrP-Pt, mica powder and silica in this application results in the preparation of a waterborne polyurethane coating with excellent flame retardant and fireproof properties. The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A waterborne polyurethane coating with low surface energy and fire-retardant properties, characterized in that, By weight, it includes 80-100 parts of silicone-modified waterborne polyurethane, 2-5 parts of zirconium phosphate-platinum catalyst, 5-10 parts of mica powder, and 5-10 parts of silica.

2. The waterborne polyurethane coating with low surface energy and fire-retardant properties according to claim 1, characterized in that, The zirconium phosphate-platinum catalyst was prepared by the following method: S1) Swelling and alcoholization treatment of zirconium phosphate: The purification agent aqueous solution and zirconium phosphate solution are stirred and mixed evenly to obtain a swollen gelled solution of zirconium phosphate; S2) Preparation of zirconium phosphate-platinum catalyst: Add aqueous chloroplatinic acid to zirconium phosphate swelling gel solution, sonicate until chloroplatinic acid is completely dissolved in zirconium phosphate swelling gel solution, then centrifuge, wash and dry the mixture to obtain zirconium phosphate-platinum catalyst.

3. The waterborne polyurethane coating with low surface energy and fire-retardant properties according to claim 1, characterized in that, The organosilicon-modified waterborne polyurethane is obtained by the following preparation method, which includes the following steps: 1) Polyol and organosilicon are premixed, and then isocyanate, 2,2-dimethylolpropionic acid and catalyst are added. The prepolymerization reaction is carried out under stirring to obtain polyurethane prepolymer. 2) Cool the polyurethane prepolymer from step 1) to room temperature, add acrylic monomer and triethylamine, adjust the pH of the reaction system to neutral, add ethylenediamine (EDA) and deionized water, and disperse evenly by high-speed mechanical dispersion to obtain a pre-emulsion. 3) Add an initiator to the pre-emulsion in step 2) and continue stirring the polymerization reaction to obtain silicone-modified waterborne polyurethane.

4. The waterborne polyurethane coating with low surface energy and fire-retardant properties according to claim 1, characterized in that, The organosilicon-modified waterborne polyurethane comprises, by weight: 1-10 parts of polyol, 1-15 parts of organosilicon, 1-10 parts of isocyanate, 10-20 parts of 2,2-dimethylolpropionic acid, 0.05-0.1 parts of catalyst, 2-20 parts of acrylic monomer, 10-20 parts of triethylamine, 1-10 parts of ethylenediamine, 20-50 parts of deionized water, and 0.01-1 parts by weight of initiator.

5. The waterborne polyurethane coating with low surface energy and fire-retardant properties according to claim 2, characterized in that, The polyols include, but are not limited to, at least one of polycarbonate diol, polyacrylol, and polyacrylol.

6. The waterborne polyurethane coating with low surface energy and fire-retardant properties according to claim 3, characterized in that, The organosilicon includes, but is not limited to, at least one of hydroxypropyl-terminated polydimethylsiloxane, γ-aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane.

7. The waterborne polyurethane coating with low surface energy and fire-retardant properties according to claim 4, characterized in that, The isocyanate includes, but is not limited to, at least one of toluene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate.

8. The waterborne polyurethane coating with low surface energy and fire retardant properties according to claim 5, characterized in that, The acrylic monomer includes, but is not limited to, at least one of methyl acrylate or butyl acrylate; the catalyst includes, but is not limited to, dibutyltin dilaurate; and the initiator includes, but is not limited to, potassium persulfate.

9. The waterborne polyurethane coating with low surface energy and fire-retardant properties according to claim 6, characterized in that, The premixing conditions in step 1) are: under a nitrogen protective atmosphere, at a temperature of 110-130℃ and a vacuum of 0.06-0.08MPa, water is removed for 1-3 hours; the prepolymerization reaction conditions in step 1) are: a prepolymerization reaction temperature of 70-90℃ and a time of 1-3 hours; the polymerization reaction conditions in step 3) are: a polymerization reaction time of 70-90℃ and a time of 4-6 hours.

10. A method for preparing a waterborne polyurethane coating with low surface energy and fire retardancy as described in any one of claims 1-9, characterized in that, Includes the following steps: 1) Preparation of organosilicon-modified waterborne polyurethane; 2) Preparation of zirconium phosphate-platinum catalyst; 3) According to the formula requirements, stir and mix the organosilicon-modified waterborne polyurethane, zirconium phosphate-platinum catalyst, mica powder and silica evenly to obtain a waterborne polyurethane coating with low surface energy and fire resistance.

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