Preparation method of zirconium-doped organic silicon resin modified epoxy resin-based fireproof coating

Abstract

The invention relates to a preparation method of a zirconium-doped organic silicon resin modified epoxy resin-based fireproof coating. The preparation method comprises the following steps: preparing zirconium-doped organic silicon resin from methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane, dimethyldiethoxysilane, n-butyl alcohol, zirconium n-propoxide, acetylacetone, water and hydrochloric acid; the preparation method comprises the following steps: grafting zirconium-doped organic silicon resin and epoxy resin to synthesize zirconium-doped organic silicon resin modified epoxy resin, and preparing and synthesizing the zirconium-doped organic silicon resin modified epoxy resin based fireproof coating by taking the zirconium-doped organic silicon resin modified epoxy resin as a coating matrix, melamine, ammonium polyphosphate, pentaerythritol and aluminum hydroxide as fillers and a 593 curing agent as a curing aid. The invention has the following effects: after the coating is fired for 2 hours under butane flame (1200-1300 DEG C), the back temperature does not exceed 160 DEG C, and the heat insulation performance is excellent; the total heat release (THR) is as low as 56.97 MJ / m < 2 >, the limit oxygen index value is increased to 33.27%, the flame retardant grade reaches V-0 grade, the total smoke release (TSP) is as low as 6.97 m < 2 >, and the flame retardant and smoke suppression performance is excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of fireproof coatings, and particularly relates to a preparation method of a zirconium-doped organosilicon resin-modified epoxy resin-based intumescent flame-retardant and heat-insulating coating. Background Art

[0002] Epoxy resin-based intumescent fireproof coatings are widely used in the construction field, aerospace field, etc. due to their excellent adhesion and corrosion resistance. However, epoxy resin is essentially a polymer material composed of elements such as carbon, hydrogen, and oxygen. Its limiting oxygen index (LOI) value is only 19.8%, which is extremely flammable, and a large amount of smoke will be released during combustion. In addition, the ablation resistance of the expanded carbon layer structure generated after it expands by heating is extremely poor. This severely limits its application in the field of fireproof coatings, and it is urgent to modify it.

[0003] Aiming at the shortcomings of epoxy resin-based fireproof coatings, the in-situ vitrification / ceramization technology modification means at high temperature can be applied to the field of epoxy resin-based intumescent fireproof coatings. The vitrification / ceramization technology is a cutting-edge technology in the field of materials science. Its core mechanism is to introduce glass and ceramization precursors under specific pressure and temperature conditions, so that specific glass phase and ceramic phase substances are generated inside the material. This can not only increase the content of ablation-resistant substances in the residual carbon and improve its anti-burning-through performance, but also improve the porous structure of the residual carbon and endow it with excellent mechanical properties and heat-insulating properties.

[0004] Organosilicon resin is a network polymer with a Si-O-Si main chain and other organic groups connected to silicon atoms. Due to the simultaneous presence of organic and inorganic structures in its structure, it has good high-temperature resistance. A large amount of SiO2 will be generated when organosilicon resin is heated, and it can form a glass phase and a ceramic phase with other coating fillers at high temperature, so as to realize in-situ vitrification and ceramization in the expanded carbon layer structure of the coating when it encounters fire. Therefore, organosilicon resin can be used as a vitrification / ceramization modification precursor material to modify epoxy resin-based intumescent fireproof coatings. However, organosilicon resin is rich in a large number of non-polar bonds, which makes its bonding performance poor in the temperature range from room temperature to 500°C. In addition, the weight loss of organosilicon resin is still relatively high, and the decomposed components are still single. Therefore, the flame-retardant and heat-insulating effect of only using organosilicon to modify epoxy resin-based intumescent flame-retardant and heat-insulating coatings is limited.

[0005] If zirconium atoms are introduced into the Si-O-Si main chain of silicone resin, not only can the bonding ability of silicone resin be effectively enhanced within the temperature range from room temperature to 500 °C by introducing polar bonds, but also its heat resistance can be effectively improved. In addition, zirconium-doped silicone resin can introduce silicon source and zirconium source simultaneously, and it is expected to generate various silicon-containing and zirconium-containing glass phase and ceramic phase substances under high-temperature sintering conditions. If zirconium-doped silicone resin is introduced into the epoxy resin-based coating, not only can the overall heat resistance and bonding performance of the coating be improved, but also the types and contents of ceramic phase and glass phase in the residual carbon (such as ZrO2, ZrP2O7, etc.) can be further increased, thereby improving the flame retardancy and heat insulation effect of the coating. However, the research on the modification of epoxy resin by zirconium-modified silicone resin has not been reported yet, and the development of zirconium-modified silicone resin-modified epoxy resin-based fireproof coating has important application value. Summary of the Invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a preparation method of a zirconium-doped silicone resin-modified epoxy resin-based fireproof coating.

[0007] In order to achieve the above purpose, the preparation method of the zirconium-doped silicone resin-modified epoxy resin-based fireproof coating provided by the present invention includes the following steps carried out in sequence:

[0008] (1) Weigh methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane and dimethyldiethoxysilane in proportion and place them in a three-necked flask. After stirring at room temperature, a mixed siloxane solution is obtained.

[0009] (2) Weigh hydrochloric acid, water and the mixed siloxane solution obtained in step (1) in proportion. Then pour hydrochloric acid and water into the three-necked flask containing the mixed siloxane solution in sequence and mix them. Heat the mixture to a certain temperature using a water bath; then stir the mixture under constant temperature conditions to obtain mixed solution 1.

[0010] (3) Weigh acetylacetone, zirconium propoxide and n-butanol in proportion and place them in a three-necked flask to mix. Heat the mixture to a certain temperature using a water bath; then stir the mixture under constant temperature conditions to obtain mixed solution 2.

[0011] (4) Weigh the mixed solution 2 obtained in step (3) and the mixed solution 1 obtained in step (2) in proportion. Then gradually drop the mixed solution 2 into the mixed solution 1. After reacting for a certain period of time under water bath conditions, then carry out vacuum distillation to obtain liquid zirconium-doped silicone resin.

[0012] (5) Weigh the zirconium-doped silicone resin obtained in step (4) and epoxy resin in proportion. First, place the epoxy resin in a three-necked flask, heat it to a certain temperature using a water bath, then incorporate the zirconium-doped silicone resin into the epoxy resin, and finally stir the mixture at room temperature to obtain mixed solution 3.

[0013] (6) Weigh phosphoric acid proportionally and add it to the mixed solution 3. After stirring at room temperature, the mixed solution 4 is obtained. Subsequently, vacuum distillation is carried out on the mixed solution 4 to obtain a liquid zirconium-doped organosilicon resin-modified epoxy resin.

[0014] (7) Weigh and mix pentaerythritol, ammonium polyphosphate and melamine proportionally and grind them evenly to obtain a mixed powder; then mix the mixed powder, aluminum hydroxide and the liquid zirconium-doped organosilicon resin-modified epoxy resin obtained in step (6) proportionally, and stir at room temperature to obtain a coating slurry; subsequently, a certain amount of 593 curing agent is added to the coating slurry, and after stirring at room temperature, a coating of zirconium-doped organosilicon resin-modified epoxy resin-based coating is obtained.

[0015] (8) Coat the coating obtained in step (7) on the surface of the substrate to be protected, and use a coater to brush it evenly. Cure it at room temperature for 8 - 16 h to obtain a zirconium-doped organosilicon resin-modified epoxy resin-based fireproof coating.

[0016] In step (1), the mass ratios of methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane and dimethyldiethoxysilane are 0.7 - 1.3:0.7 - 1.3:0.5 - 1.1:0.9 - 1.5 in sequence, and their concentrations are all 99%; the stirring speed at room temperature is 250 - 350 r / mi n , and the stirring duration is 20 - 30 min.

[0017] In step (2), the mass ratios of hydrochloric acid, water and the mixed siloxane solution obtained in step (1) are 0.0007 - 0.0013:0.7 - 1.3:0.7 - 1.3; the concentration of hydrochloric acid is 36 - 38%; the required water includes tap water, purified water or deionized water; the water bath temperature is 45 - 55°C; the stirring speed under constant temperature is 250 - 350 r / min, and the stirring duration is 1 - 3 h.

[0018] In step (3), the mass ratios of acetylacetone, zirconium n-propoxide and n-butanol are 0.7 - 1.3:0.7 - 1.3:0.7 - 1.3; the water bath temperature is 45 - 55°C; the stirring speed under constant temperature is 250 - 350 r / min, and the stirring duration is 1 - 3 h; the concentration of zirconium n-propoxide is 70%, the concentration of acetylacetone is 99%, and the concentration of n-butanol is 99%.

[0019] In step (4), the mass ratio of the mixed solution 2 obtained in step (3) to the mixed solution 1 obtained in step (2) is 0.7 - 1.3:0.7 - 1.3; the water bath temperature is 65 - 75°C, the reaction time is 5 - 7 h, and stirring is not required during the water bath reaction process; the vacuum distillation conditions are a vacuum pressure of 0.05 - 0.2 MPa, a reaction temperature of 65 - 75°C, and a duration of 15 - 25 min.

[0020] In step (5), the mass ratio of the zirconium-doped organosilicon resin obtained in step (4) to the epoxy resin is 0.8 - 1.5:2.5 - 3.5; the water bath temperature for heating the epoxy resin is 65 - 75°C; the stirring speed at room temperature is 250 - 350 r / min, and the stirring duration is 10 - 30 min. The liquid epoxy resin is E-51 epoxy resin with an epoxy value of 185 - 195 g / mol.

[0021] In step (6), the mass ratio of the phosphoric acid to the mixed solution 3 obtained in step (5) is 0.7 - 1.3:130 - 170; the stirring speed at room temperature is 250 - 350 r / min, and the stirring duration is 5 - 15 min; the vacuum distillation conditions are a vacuum pressure of 0.05 - 0.2 MPa, a reaction temperature of 75 - 85°C, and a duration of 1 - 3 h; the phosphoric acid used is concentrated phosphoric acid with a concentration of 85%.

[0022] In step (7), the mass ratio of pentaerythritol, ammonium polyphosphate, and melamine is 0.8 - 1.2:0.3 - 0.5:0.5 - 0.7; the mass ratio of the mixed powder, aluminum hydroxide, and the liquid zirconium-doped organosilicon resin-modified epoxy resin obtained in step (4) is 0.7 - 1.3:0.7 - 1.3:2.5 - 3.5; the mass ratio of the 593 curing agent to the coating slurry is 0.7 - 1.5:5 - 9; the stirring conditions for both the first and second times at room temperature are a stirring speed of 250 - 350 r / min and a stirring duration of 5 - 15 min; the number of molecules n of ammonium polyphosphate (NH4PO3) n ≥ 1000.

[0023] The interval between step (5) and step (6) should not be too long. After step (5) is completed, step (6) needs to be quickly executed, that is, phosphoric acid is incorporated within 3 - 5 min after the mixed solution 3 obtained in step (5); alternatively, the coating slurry in step (7) can be stored for standby without adding the 593 curing agent.

[0024] The method for preparing a zirconium-doped organosilicon resin-modified epoxy resin-based fireproof coating provided by the present invention has the following beneficial effects:

[0025] 1. The coating exhibits excellent heat insulation performance. In the heat insulation performance test conducted in accordance with GB / T 12441-2008, after being burned from the front by a butane flame (1200-1300 °C) for 2 h, the back temperature of the substrate coated with 1.5 mm of the coating of the present invention still remains below 160 °C.

[0026] 2. The coating exhibits excellent heat insulation performance. The cone calorimeter data shows that the peak heat release rate (PHRR) and total heat release (THR) of the coating are as low as 147.28 kW / m 2 、56.97 MJ / m 2 ; the limiting oxygen index value rises to 33.27%, and the flame retardant rating reaches V-0 grade.

[0027] 3. The coating exhibits excellent smoke suppression performance. The cone calorimeter data shows that the peak smoke release rate (PSPR) and total smoke release (TSP) of the coating are as low as 0.092 m 2 / s, 6.97 m 2 .

[0028] 4. The coating exhibits excellent environmental friendliness. The cone calorimeter data shows that the CO release rate (PCOPR) and CO2 release rate (PCO2PR) of the coating are as low as 0.0049 g / s and 0.13 g / s.

[0029] 5. The coating can in-situ generate ceramic phase substances such as ZrO2, ZrP2O7, and AlPO4 under high-temperature flames, effectively realizing in-situ ceramization when encountering fire at high temperatures; after being burned by a 1300 °C flame for 2 h, no melting pits are formed on the surface of the char residue, showing excellent ablation resistance.

[0030] 6. After being modified with zirconium-doped silicone resin, the mechanical properties of the coating are significantly improved. Its flexural strength is as high as 45.86 MPa, and its tensile strength is as high as 29.33 MPa.

[0031] 7. High versatility, the coating can be applied to the surfaces of various materials such as metal materials, fiberglass, wood products, fiber cloth, and organic products, and has good interfacial adhesion. Description of the Drawings

[0032] Figure 1 is a comparison of the heat insulation effects between the zirconium-doped silicone resin modified fireproof coating prepared in Example 1 and the blank fireproof coating without zirconium-doped silicone resin modification;

[0033] Figure 2Comparison of the cone calorimetry results of the zirconium-doped silicone resin modified fireproof coating prepared in Example 1 and the blank fireproof coating without zirconium-doped silicone resin modification; (a: Peak heat release rate PHRR; b: Total heat release THR; c: Peak smoke production rate PSPR; d: Total smoke production TSP; e: Peak CO production rate PCOPR; f: Peak CO2 production rate PCO2PR)

[0034] Figure 3 Comparison of the cross-sectional scanning electron microscope photos of the char residues after the heat insulation test of the zirconium-doped silicone resin modified fireproof coating prepared in Example 1 and the blank fireproof coating without zirconium-doped silicone resin modification; (a and c: Zirconium-doped silicone resin modified fireproof coating prepared in Example 1; b and d: Blank fireproof coating without zirconium-doped silicone resin modification)

[0035] Figure 4 Comparison of the XRD patterns of the char layers of the zirconium-doped silicone resin modified fireproof coating prepared in Example 1 and the blank fireproof coating without zirconium-doped silicone resin modification;

[0036] Figure 5 Comparison of the mechanical property data of the zirconium-doped silicone resin modified fireproof coating prepared in Example 1 and the blank fireproof coating without zirconium-doped silicone resin modification; (a: Tensile strength; b: Flexural strength; c: Experimental force-displacement curve of tensile test; d: Experimental force-displacement curve of bending test) Detailed implementation manners

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] Example 1

[0039] A preparation method of a zirconium-doped silicone resin modified epoxy resin-based fireproof coating, comprising the following steps:

[0040] (1) Weigh methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane and dimethyldiethoxysilane according to a mass ratio of 1:1:0.8:1.2 and place them in a three-necked flask, and stir at a speed of 300 r / min at room temperature for 25 min to obtain a mixed siloxane solution.

[0041] (2) Weigh hydrochloric acid, water, and the mixed siloxane solution obtained in step (1) according to a mass ratio of 0.001:1:1. Then, pour hydrochloric acid and water into a three-necked flask containing the mixed siloxane solution in sequence for mixing, and heat it to 50 °C using a water bath. Maintain a constant temperature condition and stir at a speed of 300 r / min for 2 h to obtain mixed solution 1.

[0042] (3) Weigh acetylacetone, zirconium propoxide, and n-butanol in a three-necked flask according to a mass ratio of 1:1:1 for uniform mixing, and heat it to 50 °C using a water bath. Maintain a constant temperature condition and stir at a speed of 300 r / min for 2 h to obtain mixed solution 2.

[0043] (4) Weigh the mixed solution 2 obtained in step (3) and the mixed solution 1 obtained in step (2) according to a mass ratio of 1:1. Then, gradually drip the mixed solution 2 into the mixed solution 1, heat it to 70 °C using a water bath and react for 6 h, and then perform vacuum distillation for 20 min under the conditions of 0.1 MPa and 70 °C to obtain a liquid zirconium-doped organosilicon resin.

[0044] (5) Weigh the zirconium-doped organosilicon resin obtained in step (4) and epoxy resin according to a mass ratio of 1:3. First, place the epoxy resin in a three-necked flask, heat it to 70 °C using a water bath, then incorporate the zirconium-doped organosilicon resin into the epoxy resin, and finally stir the mixture at a speed of 300 r / min at room temperature for 20 min to obtain mixed solution 3.

[0045] (6) Weigh phosphoric acid according to a mass ratio of 1:150 to the mixed solution 3 obtained in step (5), quickly add it to the mixed solution 3, and stir at a speed of 300 r / min at room temperature for 10 min to obtain mixed solution 4. Subsequently, perform vacuum distillation on the mixed solution 4 for 2 h under the conditions of 0.1 MPa and 80 °C to obtain a liquid zirconium-doped organosilicon resin-modified epoxy resin.

[0046] (7) Mix pentaerythritol, ammonium polyphosphate, and melamine according to a mass ratio of 5:2:3 and grind them evenly to obtain a mixed powder. Then, mix the mixed powder, aluminum hydroxide, and the liquid zirconium-doped organosilicon resin-modified epoxy resin obtained in step (4) in sequence according to a mass ratio of 1:1:3, and stir at a speed of 300 r / min at room temperature for 10 min to obtain a coating slurry. Subsequently, add 593 curing agent to the coating slurry according to a mass ratio of 593 curing agent to coating slurry of 1:7, and stir at a speed of 300 r / min at room temperature for 10 min to obtain a coating of zirconium-doped organosilicon resin-modified epoxy resin-based coating.

[0047] (8) Coat the coating obtained in step (7) on the surface of the substrate to be protected, and use a coater to brush it evenly. Cure it at room temperature for 10 h to obtain a zirconium-doped organosilicon resin-modified epoxy resin-based fireproof coating.

[0048] Example 2

[0049] A preparation method of a zirconium-doped organosilicon resin modified epoxy resin-based fireproof coating, comprising the following steps:

[0050] (1) Weigh methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane and dimethyldiethoxysilane according to a mass ratio of 0.7:1.3:0.5:1.5 and place them in a three-necked flask. Stir at a speed of 250 r / min for 30 min at room temperature to obtain a mixed siloxane solution.

[0051] (2) Weigh hydrochloric acid, water and the mixed siloxane solution obtained in step (1) according to a mass ratio of 0.0007:1.3:0.7. Then pour hydrochloric acid and water into the three-necked flask containing the mixed siloxane solution in sequence for mixing, and heat it to 45 °C using a water bath; keep the constant temperature condition, and stir at a speed of 250 r / min for 3 h to obtain mixed solution 1.

[0052] (3) Weigh acetylacetone, zirconium propoxide and n-butanol in a three-necked flask according to a mass ratio of 0.7:1.3:0.7 for uniform mixing, and heat it to 45 °C using a water bath; keep the constant temperature condition, and stir at a speed of 250 r / min for 3 h to obtain mixed solution 2.

[0053] (4) Weigh the mixed solution 2 obtained in step (3) and the mixed solution 1 obtained in step (2) according to a mass ratio of 0.7:1.3. Then gradually drop the mixed solution 2 into the mixed solution 1, heat it to 65 °C using a water bath and react for 7 h, and then carry out vacuum distillation at 0.05 MPa and 75 °C for 15 min to obtain a liquid zirconium-doped organosilicon resin.

[0054] (5) Weigh the zirconium-doped organosilicon resin obtained in step (4) and epoxy resin according to a mass ratio of 3:5. First, place the epoxy resin in a three-necked flask, heat it to 75 °C using a water bath, then incorporate the zirconium-doped organosilicon resin into the epoxy resin, and finally stir the mixed solution at a speed of 250 r / min for 30 min at room temperature to obtain mixed solution 3.

[0055] (6) Weigh phosphoric acid according to a mass ratio of 1:100 to the mixed solution 3 obtained in step (5), quickly add it to the mixed solution 3, and stir at a speed of 250 r / min for 15 min at room temperature to obtain mixed solution 4. Then carry out vacuum distillation on the mixed solution 4 at 0.05 MPa and 85 °C for 1 h to obtain a liquid zirconium-doped organosilicon resin modified epoxy resin.

[0056] (7) Mix pentaerythritol, ammonium polyphosphate, and melamine in a mass ratio of 2.4:1:1 and grind them evenly to obtain a mixed powder. Then, mix the mixed powder, aluminum hydroxide, and the liquid zirconium-doped organosilicon resin-modified epoxy resin obtained in step (6) in a mass ratio of 1.3:0.7:2.5 in sequence, and stir at a speed of 250 r / min at room temperature for 15 min to obtain a coating slurry. Subsequently, add 593 curing agent to the coating slurry according to the mass ratio of 593 curing agent to the coating slurry of 3:10, and stir at a speed of 250 r / min at room temperature for 15 min to obtain a coating for a zirconium-doped organosilicon resin-modified epoxy resin-based coating.

[0057] (8) Coat the coating obtained in step (7) on the surface of the substrate to be protected, and use a coater to brush it evenly, and cure it at room temperature for 8 h to obtain a zirconium-doped organosilicon resin-modified epoxy resin-based fireproof coating.

[0058] Example 3

[0059] A method for preparing a zirconium-doped organosilicon resin-modified epoxy resin-based fireproof coating includes the following steps:

[0060] (1) Weigh methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane, and dimethyldiethoxysilane in a mass ratio of 1.3:0.7:1.1:0.9 and place them in a three-necked flask, and stir at a speed of 350 r / min at room temperature for 20 min to obtain a mixed siloxane solution.

[0061] (2) Weigh hydrochloric acid, water, and the mixed siloxane solution obtained in step (1) in a mass ratio of 0.0013:0.7:1.3, then pour hydrochloric acid and water into the three-necked flask containing the mixed siloxane solution in sequence for mixing, and heat it to 55 °C using a water bath; keep the constant temperature condition, and stir at a speed of 350 r / min for 1 h to obtain a mixed solution 1.

[0062] (3) Weigh acetylacetone, zirconium n-propoxide, and n-butanol in a mass ratio of 1.3:0.7:1.3 in a three-necked flask and mix them evenly, and heat it to 55 °C using a water bath; keep the constant temperature condition, and stir at a speed of 350 r / min for 1 h to obtain a mixed solution 2.

[0063] (4) Weigh the mixed solution 2 obtained in step (3) and the mixed solution 1 obtained in step (2) in a mass ratio of 1.3:0.7, then gradually drop the mixed solution 2 into the mixed solution 1, heat it to 75 °C using a water bath and react for 5 h, and then perform vacuum distillation at 0.2 MPa and 65 °C for 25 min to obtain a liquid zirconium-doped organosilicon resin.

[0064] (5) Weigh the zirconium-doped organosilicon resin obtained in step (4) and epoxy resin according to a mass ratio of 0.8:3.5. First, place the epoxy resin in a three-necked flask, heat it in a water bath to 65 °C, then incorporate the zirconium-doped organosilicon resin into the epoxy resin, and finally stir the mixture at a speed of 350 r / min for 10 min at room temperature to obtain mixed solution 3.

[0065] (6) Weigh phosphoric acid according to a mass ratio of 0.7:170 to the mixed solution 3 obtained in step (5), quickly add it to the mixed solution 3, and stir at a speed of 350 r / min for 5 min at room temperature to obtain mixed solution 4. Subsequently, carry out vacuum distillation of the mixed solution 4 at 0.2 MPa and 75 °C for 3 h to obtain a liquid zirconium-doped organosilicon resin-modified epoxy resin.

[0066] (7) Mix pentaerythritol, ammonium polyphosphate, and melamine according to a mass ratio of 8:3:7 and grind them evenly to obtain a mixed powder; then mix the mixed powder, aluminum hydroxide, and the liquid zirconium-doped organosilicon resin-modified epoxy resin obtained in step (6) in sequence according to a mass ratio of 0.7:1.3:3.5, and stir at a speed of 350 r / min for 5 min at room temperature to obtain a coating slurry; subsequently, add 593 curing agent to the coating slurry according to a mass ratio of 0.7:9 of the 593 curing agent to the coating slurry, and stir at a speed of 350 r / min for 5 min at room temperature to obtain a coating of a zirconium-doped organosilicon resin-modified epoxy resin-based coating.

[0067] (8) Coat the coating obtained in step (7) on the surface of the substrate to be protected, use a coater to brush it evenly, and cure it at room temperature for 16 h to obtain a zirconium-doped organosilicon resin-modified epoxy resin-based fireproof coating.

[0068] Example 4

[0069] A preparation method of a zirconium-doped organosilicon resin-modified epoxy resin-based fireproof coating, comprising the following steps:

[0070] (1) Weigh methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane, and dimethyldiethoxysilane according to a mass ratio of 1.2:1:1:1.2 and place them in a three-necked flask, and stir at a speed of 280 r / min for 20 min at room temperature to obtain a mixed siloxane solution.

[0071] (2) Weigh hydrochloric acid, water, and the mixed siloxane solution obtained in step (1) according to a mass ratio of 0.001:1.3:1.3, then pour hydrochloric acid and water into the three-necked flask containing the mixed siloxane solution in sequence for mixing, and heat it to 50 °C using a water bath; keep the constant temperature condition, and stir at a speed of 250 r / min for 3 h to obtain mixed solution 1.

[0072] (3) Weigh acetylacetone, zirconium propoxide, and n-butanol in a mass ratio of 1.3:1:1 into a three-necked flask, mix them evenly, and heat them to 50 °C using a water bath; maintain a constant temperature condition and stir for 3 h at a rotation speed of 250 r / min to obtain mixed solution 2.

[0073] (4) Weigh the mixed solution 2 obtained in step (3) and the mixed solution 1 obtained in step (2) in a mass ratio of 1:1.3, then gradually drop the mixed solution 2 into the mixed solution 1, heat it to 75 °C using a water bath and react for 7 h, and then perform vacuum distillation for 25 min under the conditions of 0.05 MPa and 75 °C to obtain a liquid zirconium-doped silicone resin.

[0074] (5) Weigh the zirconium-doped silicone resin obtained in step (4) and epoxy resin in a mass ratio of 3:7. First, place the epoxy resin in a three-necked flask, heat it to 75 °C using a water bath, then incorporate the zirconium-doped silicone resin into the epoxy resin, and finally stir the mixture at a rotation speed of 250 r / min for 30 min at room temperature to obtain mixed solution 3.

[0075] (6) Weigh phosphoric acid in a mass ratio of 1:160 to the mixed solution 3 obtained in step (5), quickly add it to the mixed solution 3, and stir at a rotation speed of 350 r / min for 10 min at room temperature to obtain mixed solution 4. Subsequently, perform vacuum distillation on the mixed solution 4 for 3 h under the conditions of 0.05 MPa and 75 °C to obtain a liquid zirconium-doped silicone resin-modified epoxy resin.

[0076] (7) Mix pentaerythritol, ammonium polyphosphate, and melamine in a mass ratio of 5:3:3 and grind them evenly to obtain a mixed powder; then mix the mixed powder, aluminum hydroxide, and the liquid zirconium-doped silicone resin-modified epoxy resin obtained in step (4) in a mass ratio of 1:1.3:3 in sequence, and stir at a rotation speed of 250 r / min for 15 min at room temperature to obtain a coating slurry; subsequently, add 593 curing agent to the coating slurry according to a mass ratio of 593 curing agent to coating slurry of 1:8, and stir at a rotation speed of 300 r / min for 10 min at room temperature to obtain a coating of zirconium-doped silicone resin-modified epoxy resin-based coating.

[0077] (8) Coat the coating obtained in step (7) on the surface of the substrate to be protected, use a coater to brush it evenly, and cure it at room temperature for 12 h to obtain a zirconium-doped silicone resin-modified epoxy resin-based fireproof coating.

[0078] In the preparation of the zirconium-doped silicone resin modified epoxy resin-based fireproof coating provided by the present invention, first, a novel zirconium-doped silicone resin was prepared by a two-step sol-gel method. Subsequently, the zirconium-doped silicone resin was grafted with epoxy resin to synthesize a novel zirconium-doped silicone resin modified epoxy resin, which was used as the coating matrix, and then a variety of fillers were added to prepare an intumescent flame-retardant and heat-insulating coating. Among them, the zirconium-doped silicone resin modified epoxy resin can not only maintain excellent adhesion with a variety of materials at room temperature, but also generate ceramic phase substances such as ZrO2 and ZrP2O7 in a high-temperature environment, realizing in-situ ceramization when encountering fire and enhancing the anti-burn-through ability of the coating. In addition, during the thermal decomposition process of the zirconium-doped silicone resin modified epoxy resin, Zr inside changes from +3 to +4 valence, and a large amount of heat will be absorbed during this process, endowing the coating with excellent cooling ability. Ammonium polyphosphate, melamine, and pentaerythritol are used as the dehydration catalyst, foaming agent, and charring agent of the coating. After the coating is heated, a synergistic reaction will occur among the three, causing violent expansion and foaming, and generating an expanded carbon layer structure to resist the invasion of external heat. Aluminum hydroxide is an inorganic filler of the coating. The Al2O3 generated by its decomposition at high temperature can react with ammonium polyphosphate to generate a ceramic phase substance AlPO4, further enhancing the ablation resistance of the carbon layer structure. The 593 curing agent is a curing aid for the coating. Its amino group will undergo a ring-opening addition reaction with the epoxy group in the epoxy resin molecule, so that the epoxy resin molecular chains are connected to each other to form a three-dimensional network structure, completing the curing process.

[0079] The zirconium-doped silicone resin modified epoxy resin-based fireproof coating prepared by the present invention can be directly brush-coated. If spraying on the substrate to be protected is desired, it can be diluted with an active diluent (such as 1,4-butanediol diglycidyl ether, etc.) and then sprayed.

[0080] In order to verify the effect of the zirconium-doped organosilicon resin modified epoxy resin-based fireproof coating described in the above embodiments, the inventor of the present invention used a blank fireproof coating without zirconium-doped silicone resin modification as a comparison and conducted the following experiments:

[0081] (I) Preparation of the blank fireproof coating slurry without zirconium-doped silicone resin modification:

[0082] (1) Pentaerythritol, ammonium polyphosphate, and melamine were mixed and ground evenly according to a mass ratio of 5:2:3 to obtain a mixed powder.

[0083] (2) The mixed powder, aluminum hydroxide, and epoxy resin solution were mixed in a mass ratio of 1:1:2 in sequence, and stirred at a speed of 300 r / min for 10 min at room temperature to obtain a coating slurry.

[0084] (3) According to the mass ratio of 593 curing agent to the coating slurry obtained in step (2) of 1:7, add the 593 curing agent to the coating slurry and stir at a speed of 300 r / min at room temperature for 10 min to obtain a blank fireproof coating slurry without zirconium-doped silicone resin modification.

[0085] () Coating performance test comparison and characterization analysis:

[0086] (1) Heat insulation performance test: Lay the polished, cleaned and dried thin steel plate (100 mm × 100 mm × 1 mm) flat on a flat and flawless glass plate with the protected surface facing up; first simply apply the zirconium-doped silicone resin modified fireproof coating slurry prepared in Example 1 or the blank fireproof coating slurry without zirconium-doped silicone resin modification on the protected surface, and then evenly coat it with a coater, and control the thickness of the cured coating to be 1.5 mm; conduct the heat insulation performance test after curing at room temperature for 10 h.

[0087] Connect 5 K-type thermocouples to the back of the steel plate to collect the change of the back temperature of the coating with time. The experimental heat source is a butane flame (1200 °C - 1300 °C), the flame length during the test is 80 mm, and the test time is 2 h. In the coating test, the curve of the back temperature changing with time is as Figure 1 shown.

[0088] Figure 1 shown as the time-temperature curves obtained in the heat insulation performance tests of the two coatings. The back temperature of the blank fireproof coating without zirconium-doped silicone resin modification exceeded 275 °C after being burned by the flame for 2 h, while the back temperature of the zirconium-doped silicone resin modified fireproof coating prepared in Example 1 was only 156.77 °C after being burned by the flame for 2 h, a decrease of about 43.2%. In addition, the back temperature of the zirconium-doped silicone resin modified fireproof coating prepared in Example 1 decreased from the initial 208.12 °C to 156.77 °C because during the ablation process of zirconium-doped silicone resin at 1200 °C, the valence of Zr changed from +3 to +4, and a large amount of heat was continuously absorbed during this process.

[0089] (2) Cone calorimeter test: Pour the zirconium-doped silicone resin modified fireproof coating slurry prepared in Example 1 or the blank fireproof coating slurry without zirconium-doped silicone resin modification into a mold with specifications of 100 mm × 100 mm × 4 mm, and use it for the cone calorimeter test after curing. In this experiment, a Vouch6180 cone calorimeter tester is used, and the test is carried out in accordance with the standard ISO 5660. During the test, the heat flux is 35 kW / m 2 , and the obtained cone calorimeter test data is as Figure 2 shown.

[0090] As Figure 2 a and Figure 2As shown in Fig. b, the peak heat release rate (PHRR) and total heat release (THR) of the blank fireproof coating without zirconium-doped silicone resin modification are 227.94 kW / m 2 and 93.24 MJ / m 2 , respectively. While the PHRR and THR of the fireproof coating modified by zirconium-doped silicone resin prepared in Example 1 are 147.28 kW / m 2 and 56.97 MJ / m 2 , respectively, which are 35.39% and 38.90% lower than those of the blank fireproof coating without zirconium-doped silicone resin modification. As shown in Figure 2 Fig. c and Figure 2 Fig. d, the peak smoke release rate (PSPR) and total smoke release (TSP) of the blank fireproof coating without zirconium-doped silicone resin modification are 0.143 m 2 / s and 12.96 m 2 , respectively. While the PSPR and TSP of the fireproof coating modified by zirconium-doped silicone resin prepared in Example 1 are 0.092 m 2 / s and 6.97 m 2 , respectively, which are 35.66% and 46.22% lower than those of the blank fireproof coating without zirconium-doped silicone resin modification. As shown in Figure 2 Fig. e and Figure 2 Fig. f, the peak CO release rate (PCORR) and peak CO2 release rate (PCO2RR) of the blank fireproof coating without zirconium-doped silicone resin modification are 0.0096 g / s and 0.312 g / s, respectively. While the PCORR and PCO2RR of the fireproof coating modified by zirconium-doped silicone resin prepared in Example 1 are 0.0049 g / s and 0.13 g / s, respectively, which are 48.96% and 58.33% lower than those of the blank fireproof coating without zirconium-doped silicone resin modification.

[0091] (3) Limiting oxygen index (LOI) and vertical burning test: The LOI value of the coating sample was tested using a JF-3 oxygen index analyzer. The test sample size was 100 mm × 13 mm × 3 mm. The test was based on the standard ASTM D2863-97; The vertical burning test of the coating sample was carried out using an HS-RS-5 type device, and the flame retardant grade of the test sample was classified according to the UL-94 standard system. The test sample size was set to 100 mm × 100 mm × 4 mm. The test was carried out according to the standard ASTM D3801.

[0092] The experimental results show that the LOI value of the blank fireproof coating without zirconium-doped silicone resin modification is 22.19%, while the LOI value of the fireproof coating modified with zirconium-doped silicone resin is 33.27%, which is 49.32% higher than that of the unmodified sample. The fire retardancy rating of the blank fireproof coating without zirconium-doped silicone resin modification is V-2, while the fire retardancy rating of the fireproof coating modified with zirconium-doped silicone resin reaches V-0.

[0093] (4) Analysis of the cross-sectional microstructure of the char residue of the coating: The scanning electron microscope (Nanosem430, FEI) was used to observe the cross-sectional microstructure of the char residue structure of the coating after the heat insulation performance test, so as to understand the improvement of the physical heat insulation of the condensed phase of the coating by the introduction of zirconium-doped silicone resin.

[0094] As Figure 3 shown, the internal porous structure of the carbon layer of the blank fireproof coating without zirconium-doped silicone resin modification is extremely uneven, while the internal porous structure of the char residue layer of the fireproof coating modified with zirconium-doped silicone resin gradually densifies and is more evenly distributed. This uniformly distributed and densified porous structure can significantly improve the physical heat insulation effect of the condensed phase of the coating.

[0095] (5) Component analysis of the char residue of the coating: In order to explore what substances will be generated during the ceramization process of the coating, XRD tests were carried out on the char residue structure obtained after the heat insulation performance test. The test instrument was an XRD tester (D / Max 2500v / PC, Rigaku), and the obtained XRD pattern is as Figure 4 shown.

[0096] In Figure 4 it can be observed that both coatings have an obvious broad diffraction peak between 2θ = 20° - 35°, which corresponds to amorphous carbon. Only Al2O3 appears in the XRD pattern of the blank fireproof coating without zirconium-doped silicone resin modification. In the XRD pattern of the fireproof coating modified with zirconium-doped silicone resin, not only AlPO4 and SiO2 appear, but also zirconium-containing ceramic phase substances ZrO2 and ZrP2O7 appear. This shows that the introduction of zirconium-doped silicone resin increases the types of ceramic phases in the char residue structure of the coating and can further enhance the ability of the char residue layer to resist flame penetration.

[0097] (6) Mechanical property test: According to the provisions of GB / T 2567-2008, specimens for tensile test and bending test were prepared by casting method. First, the prepared coating slurry was poured into the test sample mold. At room temperature, after 30 minutes of curing, the test samples were taken out and their mechanical properties were tested with an electronic universal testing instrument AMT4504. Among them, the tensile test sample was dumbbell-shaped, with a total length of 200 mm, a thickness of 4 mm, a width of 2 mm at both ends, and a width of 10 mm in the middle part. The bending test sample was rectangular, with a length of 80 mm, a width of 15 mm, and a thickness of 3 mm. The test data was the average value of the results of five tests.

[0098] As Figure 5 shown in Figure 5 Figures a and b, the flexural strength of the blank fireproof coating without zirconium-doped silicone resin modification was 36.38 MPa, and the tensile strength was 21.87 MPa. While the flexural strength of the fireproof coating modified with zirconium-doped silicone resin was 45.86 MPa, and the tensile strength was 29.33 MPa. Compared with the unmodified blank sample, they were increased by 26.06% and 34.1% respectively. As Figure 5 shown in Figure 5 Figures c and d, the maximum tensile force and flexural force that the blank fireproof coating without zirconium-doped silicone resin modification could withstand were 1.17 KN and 134.52 N respectively. While the maximum tensile force and flexural force that the fireproof coating modified with zirconium-doped silicone resin could withstand were 1.5 KN and 149.7 N respectively. Compared with the blank fireproof coating without zirconium-doped silicone resin modification, they were increased by 28.21% and 11.28% respectively. In addition, the displacement amounts of the blank fireproof coating without zirconium-doped silicone resin modification in the tensile and bending tests were 3.03 mm and 4.55 mm respectively. While the displacement amounts of the fireproof coating modified with zirconium-doped silicone resin in the tensile and bending tests were 5.17 mm and 8.46 mm respectively, which were increased by 70.62% and 85.93% respectively.

Claims

1. A preparation method of a zirconium-doped silicone resin modified epoxy resin-based fireproof coating, characterized in that: The preparation method of the zirconium-doped organosilicon resin modified epoxy resin-based fireproof coating comprises the following steps carried out in sequence: (1) Weigh methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane and dimethyldiethoxysilane in proportion and place them in a three-necked flask. After stirring at room temperature, a mixed siloxane solution is obtained; (2) Weigh hydrochloric acid, water and the mixed siloxane solution obtained in step (1) in proportion. Then pour hydrochloric acid and water into the three-necked flask containing the mixed siloxane solution in sequence for mixing, and heat it to a certain temperature by water bath. Subsequently, stir the mixed solution under constant temperature conditions to obtain mixed solution 1; (3) Weigh acetylacetone, zirconium propoxide and n-butanol in proportion and place them in a three-necked flask for mixing. Heat it to a certain temperature by water bath. Subsequently, stir the mixed solution under constant temperature conditions to obtain mixed solution 2; (4) Weigh the mixed solution 2 obtained in step (3) and the mixed solution 1 obtained in step (2) in proportion. Then gradually drop the mixed solution 2 into the mixed solution 1. After reacting for a certain period of time under water bath conditions, carry out vacuum distillation to obtain liquid zirconium-doped organosilicon resin; (5) Weigh the zirconium-doped organosilicon resin obtained in step (4) and epoxy resin in proportion. First, place the epoxy resin in a three-necked flask, heat it to a certain temperature by water bath, then incorporate the zirconium-doped organosilicon resin into the epoxy resin, and finally stir the mixed solution at room temperature to obtain mixed solution 3; (6) Weigh phosphoric acid in proportion and add it to the mixed solution 3. After stirring at room temperature, mixed solution 4 is obtained. Subsequently, carry out vacuum distillation on the mixed solution 4 to obtain liquid zirconium-doped organosilicon resin modified epoxy resin; (7) Weigh pentaerythritol, ammonium polyphosphate and melamine in proportion, mix and grind them evenly to obtain a mixed powder. Then mix the mixed powder, aluminum hydroxide and the liquid zirconium-doped organosilicon resin modified epoxy resin obtained in step (6) in proportion, and stir at room temperature to obtain a coating slurry. Subsequently, add a certain amount of 593 curing agent to the coating slurry and stir at room temperature to obtain the coating of the zirconium-doped organosilicon resin modified epoxy resin-based coating; (8) Coat the coating obtained in step (7) on the surface of the substrate to be protected, and use a coater to brush it evenly. Cure it at room temperature for 8 - 16 h to obtain the zirconium-doped organosilicon resin modified epoxy resin-based fireproof coating.

2. The preparation method of the zirconium-doped silicone resin modified epoxy resin-based fireproof coating according to claim 1, characterized in that: In step (1), the mass ratio of methyltriethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane and dimethyldiethoxysilane is 0.7 - 1.3:0.7 - 1.3:0.5 - 1.1:0.9 - 1.5 in sequence, and their concentrations are all 99%; the stirring speed at room temperature is 250 - 350 r / min, and the stirring duration is 20 - 30 min.

3. The preparation method of the zirconium-doped organosilicon resin modified epoxy resin-based fireproof coating according to claim 1, wherein: In step (2), the mass ratio of the hydrochloric acid, water, and the mixed siloxane solution obtained in step (1) is 0.0007 - 0.0013: 0.7 - 1.3: 0.7 - 1.3; the concentration of the hydrochloric acid is 36 - 38%; the required water includes tap water, purified water, or deionized water; the water bath temperature is 45 - 55°C; the stirring speed at constant temperature is 250 - 350 r / min, and the stirring duration is 1 - 3 h.

4. The preparation method of the zirconium-doped organosilicon resin modified epoxy resin-based fireproof coating according to claim 1, characterized in that: In step (3), the mass ratio of the acetylacetone, zirconium propoxide, and n-butanol is 0.7 - 1.3: 0.7 - 1.3: 0.7 - 1.3; the water bath temperature is 45 - 55°C; the stirring speed at constant temperature is 250 - 350 r / min, and the stirring duration is 1 - 3 h; the concentration of zirconium propoxide is 70%, the concentration of acetylacetone is 99%, and the concentration of n-butanol is 99%.

5. The preparation method of the zirconium-doped silicone resin modified epoxy resin-based fireproof coating according to claim 1, characterized in that: In step (4), the mass ratio of the mixed solution 2 obtained in step (3) to the mixed solution 1 obtained in step (2) is 0.7 - 1.3: 0.7 - 1.3; the water bath temperature is 65 - 75°C, the reaction time is 5 - 7 h, and stirring is not required during the water bath reaction process; the vacuum distillation conditions are a vacuum pressure of 0.05 - 0.2 MPa, a reaction temperature of 65 - 75°C, and a duration of 15 - 25 min.

6. The preparation method of the zirconium-doped silicone resin modified epoxy resin-based fireproof coating according to claim 1, characterized in that: In step (5), the mass ratio of the zirconium-doped organosilicon resin obtained in step (4) to the epoxy resin is 0.8 - 1.5: 2.5 - 3.5; the water bath temperature for heating the epoxy resin is 65 - 75°C; the stirring speed at room temperature is 250 - 350 r / min, and the stirring duration is 10 - 30 min; the liquid epoxy resin is E-51 epoxy resin with an epoxy value of 185 - 195 g / mol.

7. The preparation method of the zirconium-doped silicone resin modified epoxy resin-based fireproof coating according to claim 1, characterized in that: In step (6), the mass ratio of the phosphoric acid to the mixed solution 3 obtained in step (5) is 0.7 - 1.3: 130 - 170; the stirring speed at room temperature is 250 - 350 r / min, and the stirring duration is 5 - 15 min; the vacuum distillation conditions are a vacuum pressure of 0.05 - 0.2 MPa, a reaction temperature of 75 - 85°C, and a duration of 1 - 3 h; the phosphoric acid used is concentrated phosphoric acid with a concentration of 85%.

8. The preparation method of the zirconium-doped organosilicon resin modified epoxy resin-based fireproof coating according to claim 1, wherein: In step (7), the mass ratio of pentaerythritol, ammonium polyphosphate and melamine is 0.8 - 1.2: 0.3 - 0.5: 0.5 - 0.7; the mass ratio of the mixed powder, aluminum hydroxide and the liquid zirconium-doped organosilicon resin-modified epoxy resin obtained in step (4) is 0.7 - 1.3: 0.7 - 1.3: 2.5 - 3.5; the mass ratio of the 593 curing agent to the coating slurry is 0.7 - 1.5: 5 - 9; the stirring conditions for both times before and after at room temperature are a stirring speed of 250 - 350 r / min and a stirring duration of 5 - 15 min; the number of molecules n of ammonium polyphosphate (NH4PO3) n is ≥ 1000.

9. The preparation method of the zirconium-doped organosilicon resin modified epoxy resin-based fireproof coating according to claim 1, characterized in that: The interval between step (5) and step (6) should not be too long. After step (5) is completed, step (6) needs to be carried out quickly, that is, phosphoric acid is incorporated within 3 - 5 min after the mixed solution 3 obtained in step (5); alternatively, the coating slurry in step (7) can be stored for standby without adding 593 curing agent.

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