Flame-retardant modified polyurethane coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses a flame-retardant modified polyurethane coating and a preparation method thereof.The flame-retardant modified polyurethane coating comprises a component A and a component B. The component A is prepared from, by weight, 30-45 parts of polyether glycol 2000D, 20-25 parts of polyether triol 330N and 15-30 parts of phosphate nonaisocyanate; the component B is prepared from the following raw materials in parts by weight: 2.5 to 19.5 parts of chlorinated paraffin, 0.2 to 0.5 part of dispersing agent 755W, 1 to 3 parts of 800-mesh coarse whiting, 1 to 4 parts of phosphate-based nano titanium dioxide, 0.5 to 1 part of flatting agent 100, 0.2 to 0.5 part of defoaming agent 810, 5 parts of propylene glycol methyl ether acetate and 0.1 to 0.3 part of dibutyltin dilaurate, and the flame-retardant modified polyurethane coating is obtained by uniformly mixing the chlorinated paraffin and the dispersing agent 755W. The flame-retardant modified polyurethane coating prepared by the preparation method disclosed by the invention has excellent flame retardance, antibacterial property and mechanical property.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and specifically relates to a flame-retardant modified polyurethane coating and a preparation method thereof. Background Art

[0002] Polyurethane coatings have good properties such as weather resistance and chemical resistance, and are widely used in fields such as woodware, automobiles, and waterproof coiled materials. However, polyurethane has poor flame-retardant performance, and the lack of flame-retardant performance of polyurethane coatings limits their development and application in the field of flame-retardant functionalization. Therefore, under the condition of not affecting the original properties of polyurethane coatings, flame-retardant modification of polyurethane coatings is an urgent problem to be solved at present.

[0003] For example, the patent with the application publication number CN 118480305 A discloses a solvent-free exposed polyurethane waterproof and heat-insulating coating and a preparation method thereof. The invention uses cashew shell oil-modified polyol, polyacrylate polyol, oligophosphate ester flame retardant, modified nano-titanium dioxide, etc. as raw materials, and the prepared polyurethane coating has excellent flame-retardant performance and mechanical properties, but does not improve the antibacterial performance of the coating. Summary of the Invention

[0004] (I) Technical Problems to be Solved Aiming at the deficiencies of the prior art, the present invention provides a flame-retardant modified polyurethane coating and a preparation method thereof. The prepared polyurethane coating not only has excellent flame-retardant performance, but also has excellent antibacterial performance and mechanical properties.

[0005] (II) Technical Solutions A flame-retardant modified polyurethane coating, wherein the polyurethane coating comprises component A and component B; Component A comprises the following raw materials in parts by weight: 30-35 parts of polyether diol 2000D, 20-25 parts of polyether triol 330N, 15-30 parts of phosphate group nona-isocyanate; Component B comprises the following raw materials in parts by weight: 2.5-19.5 parts of chlorinated paraffin, 0.2-0.5 parts of dispersant 755W, 1-3 parts of 800-mesh heavy calcium, 1-4 parts of phosphate group nano-titanium dioxide, 0.5-1 part of leveling agent 100, 0.2-0.5 parts of defoaming agent 810, 5 parts of propylene glycol methyl ether acetate, 0.1-0.3 parts of dibutyltin dilaurate; The preparation method of the phosphate group nano-titanium dioxide is as follows: disperse nano-titanium dioxide in an acetone solvent, add phosphate group nona-isocyanate thereto, heat up to 70-80°C, add dibutyltin dilaurate thereto, react for 1-2 h, after the reaction is completed, wash with ethanol, centrifuge, and dry to obtain phosphate group nano-titanium dioxide.

[0006] Preferably, the dosage of the phosphoric acid ester group nona-isocyanate is 10-20% of the mass of the nano-titanium dioxide.

[0007] Preferably, the preparation method of the phosphoric acid ester group nona-isocyanate comprises the following steps: (1) Add 5-chloro-1-pentanol to a toluene solvent. Under nitrogen protection, add phosphorus pentoxide thereto, stir and disperse evenly, heat up to 90-100 °C, react for 10-14 h. After the reaction is completed, carry out reduced pressure distillation, wash with deionized water, and dry to obtain intermediate product 1; (2) Add toluene diisocyanate and dibutyltin dilaurate to an acetone solvent, stir and mix evenly. At 30-40 °C, add triethanolamine and hydroquinone thereto, control the temperature at 45-50 °C, react for 3-5 h. After the reaction is completed, evacuate to remove acetone, wash with deionized water, and dry to obtain intermediate product 2; (3) Add intermediate product 1 and intermediate product 2 to a n-butanol solvent, stir and disperse, heat up to 60-70 °C, react for 18-24 h. After the reaction is completed, carry out rotary evaporation, wash with deionized water, and dry to obtain the phosphoric acid ester group nona-isocyanate.

[0008] More preferably, in the step (1), the dosage ratio of 5-chloro-1-pentanol to phosphorus pentoxide is (2.5-3) g:1 g.

[0009] More preferably, in the step (2), the dosage ratio of toluene diisocyanate to triethanolamine is (2.6-3.2) g:1 g.

[0010] More preferably, in the step (2), the dosage of dibutyltin dilaurate is 0.5% of the mass of toluene diisocyanate; the dosage of hydroquinone is 0.2% of the mass of triethanolamine.

[0011] More preferably, in the step (3), the dosage ratio of intermediate product 1 to intermediate product 2 is 1 g:(4.8-5.2) g.

[0012] The preparation method of the flame retardant modified polyurethane coating comprises the following steps: (1) Vacuum dehydrate polyether diol 2000D and polyether triol 330N at 110 °C, cool down to 60 °C, add the phosphoric acid ester group nona-isocyanate thereto, heat up to 90 °C, and react for 4 h to obtain component A; (2) Add dispersant 755W, 800-mesh heavy calcium, phosphoric acid ester group nano-titanium dioxide to chlorinated paraffin, vacuum dehydrate at 110 °C for 2 h, cool down to room temperature, add leveling agent 100, defoaming agent 810, propylene glycol methyl ether acetate, and dibutyltin dilaurate thereto, and stir and degas for 1 h to obtain component B; (3) Mix Component A and Component B evenly to obtain the flame-retardant modified polyurethane coating.

[0013] (III) Beneficial technical effects Reaction mechanism of the present invention: In the present invention, 5-chloro-1-pentanol and phosphorus pentoxide are used as raw materials to obtain intermediate product 1 through esterification. Toluene diisocyanate, triethanolamine are used as raw materials, dibutyltin dilaurate is used as a catalyst, and hydroquinone is used as an inhibitor. Through reaction, intermediate product 2 is obtained. The chlorine contained in intermediate product 1 is used to carry out a quaternization reaction with the tertiary amine contained in intermediate product 2 to obtain phosphoric acid ester group nona-isocyanate, which has nine isocyanate groups. Its structure is novel and the preparation method is simple. The isocyanate group contained in phosphoric acid ester group nona-isocyanate reacts with the hydroxyl group contained on the surface of nano-titanium dioxide to obtain phosphoric acid ester group nano-titanium dioxide. Using polyether diol 2000D, polyether triol 330N, and phosphoric acid ester group nona-isocyanate as raw materials for reaction, Component A is obtained. Chlorinated paraffin, dispersant 755W, phosphoric acid ester group nano-titanium dioxide, dibutyltin dilaurate, etc. are stirred and mixed evenly to obtain Component B. Finally, Component A and Component B are mixed evenly to obtain the flame-retardant modified polyurethane coating.

[0014] The phosphoric acid ester group nona-isocyanate prepared in the present invention contains organic flame-retardant elements, namely phosphorus element and nitrogen element. The phosphorus element can generate strongly dehydrating substances such as phosphoric acid when heated, and a dense isolation layer covers the surface of the coating, isolating the transportation of substances and energy; the nitrogen element generates non-combustible gases when heated, diluting the concentration of flammable gases in the air and assisting in improving the flame-retardant performance. In addition, the heavy calcium and nano-titanium dioxide contained in it can be used as inorganic flame-retardant materials to form an organic-inorganic synergistic flame-retardant system with organic flame-retardant materials, jointly improving the flame-retardant effect of the material.

[0015] The phosphoric acid ester group nona-isocyanate prepared in the present invention contains a trimeric quaternary ammonium salt structure, and its antibacterial effect is relatively better than that of the single quaternary ammonium salt structure and the gemini quaternary ammonium salt structure. And the present invention uses nano-titanium dioxide and trimeric quaternary ammonium salt to synergistically improve the antibacterial performance of the polyurethane coating, and the compounding of the two has a synergistic antibacterial effect on Escherichia coli and Staphylococcus aureus.

[0016] The nano-titanium dioxide used in the present invention has a small particle size and a large surface energy. It is easy to agglomerate when directly introduced into the polyurethane coating. The present invention uses phosphoric acid ester-based nona-isocyanate to treat the nano-titanium dioxide, forming an organic-inorganic composite material with nano-titanium dioxide as the cross-linking point. This can not only reduce the agglomeration of nano-titanium dioxide, increase the compatibility, and make it uniformly dispersed in the coating, but also, when subjected to impact, can absorb more impact energy as a stress concentration point, improving the mechanical properties of the material. In addition, the prepared phosphoric acid ester-based nona-isocyanate contains more branched-chain structures. When introduced into the polyurethane coating, its terminal isocyanate reacts with the hydroxyl groups in the polyether alcohol, generating more urethane groups in the molecular chain, which can form a spatial cross-linked network structure. More molecular chains are cross-linked and entangled with each other, the force between the molecular chains is enhanced, forming more chemical links and physical links, and then forming more cross-linking sites. When subjected to external impact, the impact force can be dispersed to other molecular chains along the cross-linking sites, thereby improving the mechanical properties of the polyurethane coating. The prepared polyurethane coating of the present invention has excellent flame retardancy, antibacterial properties, and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the reaction route of intermediate 1; Figure 2 is the reaction route of intermediate 2; Figure 3 is the reaction route of phosphoric acid ester-based nona-isocyanate. DETAILED DESCRIPTION OF THE INVENTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. Example 1

[0019] (1) Add 12.5 g of 5-chloro-1-pentanol to the toluene solvent. Under nitrogen protection, add 5 g of phosphorus pentoxide thereto, stir and disperse evenly, heat up to 95 °C, react for 12 h. After the reaction, carry out reduced pressure distillation, wash with deionized water, and dry to obtain intermediate 1.

[0020] (2) Add 30 g of toluene diisocyanate and 0.15 g of dibutyltin dilaurate to the acetone solvent, stir and mix evenly. At 35 °C, add 10 g of triethanolamine and 0.02 g of hydroquinone thereto, control the temperature at 50 °C, react for 4 h. After the reaction, evacuate to remove acetone, wash with deionized water, and dry to obtain intermediate 2.

[0021] (3) Add 5 g of intermediate 1 and 24 g of intermediate 2 to n-butanol solvent, stir and disperse, heat up to 70 °C, react for 18 h. After the reaction, perform rotary evaporation, wash with deionized water, and dry to obtain phosphoric acid ester group nona-isocyanate.

[0022] (4) Disperse 5 g of nano-titanium dioxide in acetone solvent, add 0.5 g of phosphoric acid ester group nona-isocyanate to it, heat up to 75 °C, add 10 drops of dibutyltin dilaurate to it, react for 1 h. After the reaction, wash with ethanol, centrifuge, and dry to obtain phosphoric acid ester group nano-titanium dioxide.

[0023] (5) By weight, vacuum dehydrate 35 parts of polyether diol 2000D and 20 parts of polyether triol 330N at 110 °C, cool down to 60 °C, add 15 parts of phosphoric acid ester group nona-isocyanate to it, heat up to 90 °C, and react for 4 h to obtain component A.

[0024] (6) By weight, add 0.2 part of dispersant 755W, 3 parts of 800-mesh heavy calcium carbonate, 1 part of phosphoric acid ester group nano-titanium dioxide to 19.5 parts of chlorinated paraffin, vacuum dehydrate at 110 °C for 2 h, cool down to room temperature, add 0.5 part of leveling agent 100, 0.5 part of defoaming agent 810, 5 parts of propylene glycol methyl ether acetate, 0.3 part of dibutyltin dilaurate, stir and degas for 1 h to obtain component B.

[0025] (7) Mix component A and component B evenly to obtain flame retardant modified polyurethane coating. Example 2

[0026] (1) Add 14 g of 5-chloro-1-pentanol to toluene solvent. Under nitrogen protection, add 5 g of phosphorus pentoxide to it, stir and disperse evenly, heat up to 100 °C, react for 10 h. After the reaction, perform reduced pressure distillation, wash with deionized water, and dry to obtain intermediate 1.

[0027] (2) Add 32 g of toluene diisocyanate and 0.16 g of dibutyltin dilaurate to acetone solvent, stir and mix evenly. At 30 °C, add 10 g of triethanolamine and 0.02 g of hydroquinone to it, control the temperature at 50 °C, react for 3 h. After the reaction, evacuate to remove acetone, wash with deionized water, and dry to obtain intermediate 2.

[0028] (3) Add 5 g of intermediate 1 and 25 g of intermediate 2 to n-butanol solvent, stir and disperse, heat up to 60 °C, react for 24 h. After the reaction, perform rotary evaporation, wash with deionized water, and dry to obtain phosphoric acid ester group nona-isocyanate.

[0029] (4) Disperse 5 g of nano-titanium dioxide in acetone solvent, add 0.8 g of phosphoric acid ester-based nona-isocyanate thereto, heat up to 75 °C, add 10 drops of dibutyltin dilaurate thereto, react for 1.5 h. After the reaction is completed, wash with ethanol, centrifuge, and dry to obtain phosphoric acid ester-based nano-titanium dioxide.

[0030] (5) By weight, vacuum dehydrate 30 parts of polyether diol 2000D and 25 parts of polyether triol 330N at 110 °C, cool down to 60 °C, add 20 parts of phosphoric acid ester-based nona-isocyanate thereto, heat up to 90 °C, and react for 4 h to obtain Component A.

[0031] (6) By weight, add 0.2 part of dispersant 755W, 3 parts of 800-mesh heavy calcium carbonate, 2 parts of phosphoric acid ester-based nano-titanium dioxide to 13.3 parts of chlorinated paraffin, vacuum dehydrate at 110 °C for 2 h, cool down to room temperature, add 1 part of leveling agent 100, 0.2 part of defoaming agent 810, 5 parts of propylene glycol methyl ether acetate, 0.3 part of dibutyltin dilaurate thereto, stir and degas for 1 h to obtain Component B.

[0032] (7) Mix Component A and Component B evenly to obtain a flame-retardant modified polyurethane coating. Example Three

[0033] (1) Add 15 g of 5-chloro-1-pentanol to toluene solvent. Under nitrogen protection, add 5 g of phosphorus pentoxide thereto, stir and disperse evenly, heat up to 90 °C, react for 14 h. After the reaction is completed, perform vacuum distillation, wash with deionized water, and dry to obtain Intermediate 1.

[0034] (2) Add 30 g of toluene diisocyanate and 0.15 g of dibutyltin dilaurate to acetone solvent, stir and mix evenly. At 40 °C, add 10 g of triethanolamine and 0.02 g of hydroquinone thereto, control the temperature at 45 °C, react for 4 h. After the reaction is completed, evacuate to remove acetone, wash with deionized water, and dry to obtain Intermediate 2.

[0035] (3) Add 5 g of Intermediate 1 and 26 g of Intermediate 2 to n-butanol solvent, stir and disperse, heat up to 65 °C, react for 20 h. After the reaction is completed, perform rotary evaporation, wash with deionized water, and dry to obtain phosphoric acid ester-based nona-isocyanate.

[0036] (4) Disperse 5 g of nano-titanium dioxide in acetone solvent, add 0.9 g of phosphoric acid ester-based nona-isocyanate thereto, heat up to 80 °C, add 10 drops of dibutyltin dilaurate thereto, react for 1 h. After the reaction is completed, wash with ethanol, centrifuge, and dry to obtain phosphoric acid ester-based nano-titanium dioxide.

[0037] (5) By weight, 35 parts of polyether diol 2000D and 20 parts of polyether triol 330N are vacuum dehydrated at 110 °C, cooled to 60 °C, 25 parts of phosphate group nona-isocyanate are added thereto, and the temperature is raised to 90 °C and reacted for 4 h to obtain Component A.

[0038] (6) By weight, 0.5 part of dispersant 755W, 1 part of 800-mesh heavy calcium carbonate, 3 parts of phosphate group nano-titanium dioxide are added to 9.7 parts of chlorinated paraffin, vacuum dehydrated at 110 °C for 2 h, cooled to room temperature, 0.5 part of leveling agent 100, 0.2 part of defoaming agent 810, 5 parts of propylene glycol methyl ether acetate, and 0.1 part of dibutyltin dilaurate are added thereto, and stirred and degassed for 1 h to obtain Component B.

[0039] (7) Component A and Component B are mixed evenly to obtain the flame-retardant modified polyurethane coating. Example 4

[0040] (1) 14 g of 5-chloro-1-pentanol is added to a toluene solvent. Under nitrogen protection, 5 g of phosphorus pentoxide is added thereto, stirred and dispersed evenly, the temperature is raised to 95 °C, and reacted for 12 h. After the reaction is completed, vacuum distillation is carried out, washed with deionized water, and dried to obtain Intermediate 1.

[0041] (2) 26 g of toluene diisocyanate and 0.13 g of dibutyltin dilaurate are added to an acetone solvent, stirred and mixed evenly. At 35 °C, 10 g of triethanolamine and 0.02 g of hydroquinone are added thereto, the temperature is controlled at 50 °C, and reacted for 5 h. After the reaction is completed, acetone is removed by vacuum, washed with deionized water, and dried to obtain Intermediate 2.

[0042] (3) 5 g of Intermediate 1 and 25 g of Intermediate 2 are added to a n-butanol solvent, stirred and dispersed, the temperature is raised to 70 °C, and reacted for 18 h. After the reaction is completed, rotary evaporation is carried out, washed with deionized water, and dried to obtain phosphate group nona-isocyanate.

[0043] (4) 5 g of nano-titanium dioxide is dispersed in an acetone solvent, 1 g of phosphate group nona-isocyanate is added thereto, the temperature is raised to 70 °C, 10 drops of dibutyltin dilaurate are added thereto, and reacted for 2 h. After the reaction is completed, washed with ethanol, centrifuged, and dried to obtain phosphate group nano-titanium dioxide.

[0044] (5) By weight, 35 parts of polyether diol 2000D and 20 parts of polyether triol 330N are vacuum dehydrated at 110 °C, cooled to 60 °C, 30 parts of phosphate group nona-isocyanate are added thereto, and the temperature is raised to 90 °C and reacted for 4 h to obtain Component A.

[0045] (6) By weight, add 0.4 part of dispersant 755W, 2 parts of 800-mesh heavy calcium carbonate, 4 parts of phosphate group nano-titanium dioxide to 2.5 parts of chlorinated paraffin, dehydrate under vacuum at 110 °C for 2 h, cool to room temperature, then add 0.5 part of leveling agent 100, 0.3 part of defoamer 810, 5 parts of propylene glycol methyl ether acetate, and 0.3 part of dibutyltin dilaurate, stir and degas for 1 h to obtain Component B.

[0046] (7) Mix Component A and Component B evenly to obtain the flame-retardant modified polyurethane coating.

[0047] Comparative Example 1 The flame-retardant modified polyurethane coating provided in this comparative example and its preparation method are generally the same as those in Example 1, and the main difference is that Comparative Example 1 does not contain phosphate group nano-titanium dioxide.

[0048] Comparative Example 2 The flame-retardant modified polyurethane coating provided in this comparative example and its preparation method are generally the same as those in Example 1, and the main difference is that Comparative Example 2 replaces the phosphate group nona-isocyanate in Example 1 with toluene diisocyanate.

[0049] Coat the paint on tinplate and dry it in an oven at 80 °C to form a paint film.

[0050] Use a limiting oxygen index tester to test the oxygen index of the paint, and the specimen size is 120 mm × 6 mm × 3 mm.

[0051] Use a universal tensile testing machine to test the tensile properties of the paint, and the tensile speed is 100 mm / min.

[0052] Use a paint film impact tester to test the impact resistance.

[0053] Table 1: Test results of the flame-retardant properties and mechanical properties of each example and comparative example

[0054] As can be seen from the table, the polyurethane coating prepared by the present invention has excellent flame-retardant properties and mechanical properties.

[0055] Refer to GB / T21866-2008 to test the antibacterial properties of the paint.

[0056] Table 2: Antibacterial test results of each example and comparative example

[0057] As can be seen from the table, the polyurethane coating prepared by the present invention has good antibacterial properties, and with the increase of the dosage of phosphate group nano-titanium dioxide and phosphate group nona-isocyanate, the antibacterial property can reach up to 99.9%.

[0058] In the description of the specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

Claims

1. A flame retardant modified polyurethane coating, characterized in that: The polyurethane coating comprises component A and component B; The component A comprises the following raw materials in parts by weight: 30-35 parts of polyether diol 2000D, 20-25 parts of polyether triol 330N, and 15-30 parts of phosphate nonaisocyanate; The B component includes the following raw materials in parts by weight: 2.5-19.5 parts of chlorinated paraffin, 0.2-0.5 parts of dispersant 755W, 1-3 parts of 800 mesh heavy calcium, 1-4 parts of phosphate-based nano titanium dioxide, 0.5-1 parts of leveling agent 100, 0.2-0.5 parts of defoamer 810, 5 parts of propylene glycol methyl ether acetate, and 0.1-0.3 parts of dibutyltin dilaurate; The preparation method of the phosphate-based nano titanium dioxide is as follows: dispersing nano titanium dioxide in an acetone solvent, adding phosphate-based nonaisocyanate thereto, heating to 70-80° C., adding dibutyltin dilaurate thereto, reacting for 1-2 hours, washing with ethanol after the reaction, centrifuging, and drying to obtain the phosphate-based nano titanium dioxide.

2. The flame retardant modified polyurethane coating according to claim 1, characterized in that: The amount of the phosphate nonaisocyanate is 10-20% of the mass of the nano titanium dioxide.

3. The flame retardant modified polyurethane coating according to claim 1, characterized in that: The preparation method of the phosphate nonaisocyanate comprises the following steps: (1) Add 5-chloro-1-pentanol to toluene solvent, add phosphorus pentoxide under nitrogen protection, stir and disperse evenly, heat to 90-100°C, react for 10-14 hours, and after the reaction is completed, distill under reduced pressure, wash with deionized water, and dry to obtain intermediate 1; (2) Add toluene diisocyanate and dibutyltin dilaurate to acetone solvent, stir and mix evenly, add triethanolamine and hydroquinone at 30-40°C, control the temperature to 45-50°C, react for 3-5h, and after the reaction is completed, remove acetone by vacuum, wash with deionized water, and dry to obtain intermediate product 2; (3) Add intermediate product 1 and intermediate product 2 to n-butanol solvent, stir and disperse, heat to 60-70° C., react for 18-24 hours, and after the reaction, rotary evaporate, wash with deionized water, and dry to obtain phosphate nonaisocyanate.

4. The flame retardant modified polyurethane coating according to claim 3, characterized in that: In the above (1), the usage ratio of 5-chloro-1-pentanol and phosphorus pentoxide is (2.5-3) g:1 g.

5. The flame retardant modified polyurethane coating according to claim 3, characterized in that: In the above (2), the usage ratio of toluene diisocyanate and triethanolamine is (2.6-3.2) g:1 g.

6. The flame retardant modified polyurethane coating according to claim 3, characterized in that: In the above (2), the amount of dibutyltin dilaurate used is 0.5% of the mass of toluene diisocyanate; and the amount of hydroquinone used is 0.2% of the mass of triethanolamine.

7. The flame retardant modified polyurethane coating according to claim 3, characterized in that: In the above (3), the usage ratio of intermediate product 1 to intermediate product 2 is 1g:(4.8-5.2)g.

8. The method for preparing the flame retardant modified polyurethane coating according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Polyether diol 2000D and polyether triol 330N were vacuum dehydrated at 110°C, cooled to 60°C, phosphate nonaisocyanate was added thereto, the temperature was raised to 90°C, and the reaction was carried out for 4 hours to obtain component A; (2) Add dispersant 755W, 800 mesh heavy calcium, phosphate-based nano titanium dioxide to chlorinated paraffin, vacuum dehydrate at 110°C for 2 hours, cool to room temperature, add leveling agent 100, defoamer 810, propylene glycol methyl ether acetate, and dibutyl tin dilaurate, stir and degas for 1 hour to obtain component B; (3) Component A and component B are mixed evenly to obtain a flame retardant modified polyurethane coating.

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