A high-reflectivity, high-temperature resistant, heat-insulating organic coating, its preparation method and application

Abstract

This invention discloses a high-reflectivity, high-temperature resistant, and heat-insulating organic coating, its preparation method, and its application, belonging to the field of thermal protective coatings. The high-reflectivity organic coating comprises a heat-resistant, high-reflectivity outer layer and a heat-insulating inner layer. The heat-resistant, high-reflectivity outer layer is made from a heat-resistant, high-reflectivity outer layer coating, the raw materials of which include water glass, water-based silicone resin emulsion, nano-dispersible ATO powder, mica powder, and boron oxide powder. The heat-insulating inner layer is made from a heat-insulating inner layer coating, the raw materials of which include water-based silicone resin emulsion, hollow glass microspheres of different particle sizes, mica powder, talc powder, kaolin, and silica. The high-temperature resistant, heat-insulating organic coating prepared by this invention exhibits excellent thermal shock resistance and heat resistance, and can be used as a protective outer layer in fire-fighting equipment. By adopting a double-layer design of a heat-insulating inner layer and a heat-resistant, high-reflectivity outer layer, the service life of fire-fighting equipment during near-fire operation can be improved.

Description

Technical Field

[0001] This invention relates to the field of protective coatings, specifically to a high-reflectivity, high-temperature resistant, heat-insulating organic coating, its preparation method, and its application. Background Technology

[0002] With the development of modern industry, the requirements for the high-temperature resistance of equipment and gear used at high temperatures are becoming increasingly stringent. There are many methods for thermal protection of high-temperature equipment and gear, but a commonly used method is to coat the surface of high-temperature equipment with high-temperature resistant heat-insulating coatings. High-temperature resistant heat-insulating coatings are functional coatings with a wide range of applications, especially in high-temperature equipment such as chimneys, power plant boilers, and fire-fighting equipment, to protect the materials themselves from high-temperature oxidation and corrosion.

[0003] Currently, high-temperature resistant heat-insulating coatings can be divided into two main categories based on the type of binder. The first category is inorganic high-temperature resistant heat-insulating coatings, mainly including silicate high-temperature resistant heat-insulating coatings, phosphate high-temperature resistant coatings, and silica sol high-temperature resistant coatings. Inorganic high-temperature resistant heat-insulating coatings have advantages such as low cost and high heat resistance, but they also have drawbacks such as weak adhesion to metals, high brittleness and easy cracking of the coating, and the need for high-temperature baking and curing. Compared to inorganic high-temperature resistant heat-insulating coatings, the second category, organic high-temperature resistant heat-insulating coatings, has advantages such as strong adhesion and good flexibility. Commonly used organic high-temperature resistant heat-insulating coating systems include organic fluorine resin coatings, organic silicone resin coatings, and heterocyclic polymer coatings.

[0004] Currently, the most widely used high-temperature resistant thermal insulation coatings on the market are solvent-based (oil-based) silicone resin coatings. However, with the successive promulgation of emission standards for volatile organic compounds (VOCs), oil-based silicone resin coatings are increasingly unable to meet the needs of environmentally friendly development. Therefore, developing environmentally friendly coatings such as water-based silicone resin coatings has become of great significance. Compared to oil-based silicone resins, water-based silicone resins often have lower temperature resistance, which limits their application in high-temperature resistant coatings. Therefore, we need to improve the temperature resistance of silicone resin coatings. Common methods for improving the heat resistance of high-temperature resistant thermal insulation coatings include modifying the binder and changing the ratio of binder to pigments and fillers in the coating. In practical applications, high-temperature resistant thermal insulation coatings often need to consider factors such as the temperature they can withstand, their thermal insulation performance, and the required cost. Therefore, selecting appropriate binders and pigments and fillers is of great importance.

[0005] The main chain of silicone resin binders contains a large number of Si-O-Si inorganic structures. Compared with organic resins with carbon chain as the backbone, the bond energy of Si-O bonds (443.7 kJ / mol) is much greater than that of CO bonds (351 kJ / mol) and C-C bonds (347 kJ / mol), giving it high thermal decomposition temperature and outstanding heat resistance. Furthermore, when silicone resin is subjected to high-temperature corrosion, a dense SiO2 protective layer forms on its surface. This SiO2 protective layer has excellent thermal insulation properties, preventing the surface high temperature from continuing to conduct downwards and inhibiting further pyrolysis within the substrate. Simultaneously, the dense structure of this SiO2 layer effectively prevents external air from diffusing inwards, thus intercepting all the oxygen required for thermal oxidative degradation on the surface of the coating and preventing the decomposition of the inner structure of the silicone resin. Therefore, choosing silicone resin as the binder for high-temperature resistant heat-insulating coatings is essential.

[0006] Besides binders, high-temperature resistant heat-insulating coatings often require pigments and fillers to achieve their heat-resistant and heat-insulating properties. Pigments and fillers can be categorized by function into high-temperature pigments, heat-resistant fillers, and heat-insulating fillers. High-temperature pigments mainly refer to pigments that do not change color at high temperatures, such as titanium dioxide, silicon iron red, copper chromium black, and cadmium red, serving an aesthetic purpose in high-temperature resistant heat-insulating coatings. Heat-resistant fillers include high-temperature resistant powders such as talc, mica powder, and kaolin. Heat-insulating fillers mainly include hollow glass microspheres, expanded vermiculite, and diatomaceous earth; these materials have low density, high porosity, and low thermal conductivity, playing a crucial role in high-temperature resistant heat-insulating coatings.

[0007] In summary, the development of high-temperature resistant heat-insulating coatings for fire-fighting equipment is of great significance, especially low-cost, mass-producible high-temperature resistant heat-insulating coatings. Summary of the Invention

[0008] Purpose of the invention: In order to solve the technical problems existing in the prior art, the present invention aims to provide a high-reflectivity, high-temperature resistant, and heat-insulating organic coating with excellent comprehensive performance, and the present invention also provides a preparation method and application of the high-reflectivity, high-temperature resistant, and heat-insulating organic coating.

[0009] Technical Solution: The high-reflectivity, high-temperature resistant, and heat-insulating organic coating of the present invention comprises a heat-resistant, high-reflectivity outer layer and a heat-insulating inner layer. The heat-resistant, high-reflectivity outer layer is made of a heat-resistant, high-reflectivity outer layer coating, the raw materials of which include water glass, water-based silicone resin emulsion, nano-dispersible ATO powder, mica powder, and boron oxide powder. The heat-insulating inner layer is made of a heat-insulating inner layer coating, the raw materials of which include water-based silicone resin emulsion, hollow glass microspheres of different particle sizes, mica powder, talc powder, kaolin, and silica.

[0010] Furthermore, in the heat-resistant, high-reflectivity outer layer, the mass ratio of water glass, water-based silicone resin emulsion, nano-dispersible ATO powder, mica powder, and boron oxide powder is 10-20:20-45:20-45:2-10:2-10.

[0011] Furthermore, in the heat insulation inner layer, the mass ratio of water-based silicone resin emulsion, hollow glass microspheres, mica powder, talc powder, kaolin and precipitated silica is 35-55:20-30:5-10:5-10:5-10:1-5.

[0012] Furthermore, the water glass is one or more of sodium water glass, potassium water glass, or lithium water glass.

[0013] Furthermore, the hollow glass microspheres of different sizes include hollow glass microspheres with particle sizes of 15-25 μm, 35-45 μm, and 60-75 μm in a mass ratio of 0.8-1.2:1.8-2.2:2.8-3.2. Preferably, the hollow glass microspheres of different sizes include hollow glass microspheres with particle sizes of 20 μm, 40 μm, and 65 μm in a mass ratio of 5:10:15.

[0014] Furthermore, the thickness ratio of the heat-resistant, high-reflectivity outer layer to the heat-insulating inner layer is 30-100μm:0.5-1.8mm.

[0015] Furthermore, the mica powder has a particle size of 2000-4000 mesh, the talc powder has a particle size of 2000-4000 mesh, the kaolin has a particle size of 2000-4000 mesh, and the silica has a surface area of ​​130-170 m². 2 / g, with a diameter of 10-20nm.

[0016] The preparation method of the above-mentioned high-reflectivity, high-temperature resistant, and heat-insulating organic coating includes the following steps:

[0017] (1) Preparation of heat-insulating inner layer coating;

[0018] (2) Preparation of heat-resistant, high-reflectivity outer coating;

[0019] (3) First, apply the heat-insulating inner layer coating by scraping or brushing it onto the outer surface of the substrate. After it is dry, a substrate with a heat-insulating inner layer is obtained. Then, spray the heat-resistant and high-reflectivity outer layer coating onto the outer surface of the heat-insulating inner layer. After it is dry, perform a curing treatment. After the curing treatment, a substrate with a high-reflectivity, high-temperature resistant, and heat-insulating organic coating is obtained.

[0020] Further, in step (1), the preparation method of the heat-insulating inner layer coating is as follows: first, hollow glass microspheres of different particle sizes, mica powder, talc powder, kaolin and white carbon black are mixed and stirred to obtain a mixed filler; then, water-based organosilicon resin emulsion is added to the mixed filler and stirred to obtain the heat-insulating inner layer coating.

[0021] Further, in step (2), the method for preparing the heat-resistant high-reflectivity outer coating is as follows: water glass, water-based organosilicon resin emulsion, nano-dispersible ATO powder, mica powder and boron oxide powder are stirred and mixed to obtain the heat-resistant high-reflectivity outer coating.

[0022] Further, in step (3), the spraying process parameters are: the spray gun nozzle diameter is 1.0-4.0mm, the spraying distance is 15-30cm, and the spraying time is 3-10s; the curing parameters are: curing at 180-250℃ for 15-45min.

[0023] The high-reflectivity, high-temperature resistant, and heat-insulating organic coating described in this invention can be used as a protective outer layer on the surface of fire-fighting equipment.

[0024] Invention Principle: In this invention, the high-reflectivity, high-temperature resistant, and heat-insulating organic coating adopts a double-layer design: a heat-insulating inner layer and a heat-resistant, high-reflectivity outer layer. The heat-resistant, high-reflectivity outer layer incorporates a high-reflectivity material—nano-dispersible ATO powder—which can reflect some of the heat radiation, reducing the temperature rise of the coating due to radiation and thus increasing its service temperature. Simultaneously, the heat-resistant, high-reflectivity outer coating uses a binder composed of water-based silicone resin and water glass, improving the coating's own heat resistance.

[0025] Because boron oxide has a low melting point of approximately 450℃, adding a small amount of boron oxide powder to the heat-resistant, high-reflectivity outer coating can repair micro-cracks that occur in the outer layer during application. At high temperatures, it can also dissolve some of the metal oxides in the mica powder in its molten state, forming a secondary film. The combination of boron oxide and mica powder ensures that the heat-resistant, high-reflectivity outer layer adheres firmly to the heat-insulating inner layer, preventing it from easily detaching and improving the coating's thermal shock resistance.

[0026] The inner heat-insulating coating uses hollow glass microspheres of different particle sizes, which increases the filling rate of hollow glass microspheres in the same volume of coating and improves the heat insulation performance of the coating.

[0027] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0028] (1) The high-reflectivity, high-temperature resistant, heat-insulating organic coating of the present invention adopts a double-layer design of heat-insulating inner layer and heat-resistant high-reflectivity outer layer. Applying it to the surface of fire-fighting equipment can improve the service life of fire-fighting equipment when operating near the fire.

[0029] (2) The preparation method of the present invention is simple, and the raw materials are inexpensive and readily available. Detailed Implementation

[0030] The present invention will now be further described with reference to specific embodiments.

[0031] Example 1: The high-reflectivity, high-temperature resistant, and heat-insulating organic coating provided in this example includes a heat-resistant, high-reflectivity outer layer and a heat-insulating inner layer.

[0032] The heat-resistant high-reflectivity outer layer is made of a heat-resistant high-reflectivity outer layer coating. The raw materials of the heat-resistant high-reflectivity outer layer coating include water glass, water-based organosilicon resin emulsion, nano-dispersible ATO powder, mica powder and boron oxide powder in a mass ratio of 15:35:40:6:4. The water glass is composed of sodium water glass, potassium water glass and lithium water glass in a mass ratio of 1:1:2.

[0033] The heat-insulating inner layer is made of a heat-insulating inner layer coating. The raw materials of the heat-insulating inner layer coating include a water-based organosilicon resin emulsion with a mass ratio of 45:30:8:5:5:5:2, hollow glass microspheres of different particle sizes (particle sizes of 20μm, 40μm, and 65μm, with a mass ratio of 5:10:15), mica powder with a particle size of 2000-4000 mesh, talc powder with a particle size of 2000-4000 mesh, kaolin with a particle size of 2000-4000 mesh, and a surface area of ​​130-170 m². 2 / g, silica with a diameter of 10-20nm.

[0034] The thickness ratio of the heat-resistant, high-reflectivity outer layer to the heat-insulating inner layer is 80μm:1.5mm.

[0035] The preparation method of the above-mentioned high-reflectivity, high-temperature resistant, and heat-insulating organic coating includes the following steps:

[0036] (1) Preparation of heat insulation inner layer coating: First, hollow glass microspheres of different particle sizes, mica powder, talc powder, kaolin and white carbon black are mixed and stirred for 10 min to obtain mixed filler; then water-based organosilicon resin emulsion is added to the mixed filler and stirred for 15 min to obtain heat insulation inner layer coating.

[0037] (2) Preparation of heat-resistant high reflectivity outer coating: Water glass, water-based organosilicon resin emulsion, nano-dispersible ATO powder, mica powder and boron oxide powder are stirred and mixed for 15 min to obtain heat-resistant high reflectivity outer coating;

[0038] (3) First, apply the heat-insulating inner layer coating to the outer surface of the substrate by scraping with a putty knife. After 48 hours of surface drying, a substrate with a heat-insulating inner layer is obtained. Then, spray the heat-resistant high-reflectivity outer layer coating onto the outer surface of the heat-insulating inner layer. The spraying process parameters are: the nozzle diameter of the spray gun is 2mm, the spraying distance is 20cm, and the spraying time is 5s. Then, perform a curing treatment and cure at 200℃ for 25 minutes. After the curing is completed, a substrate with a high-temperature heat-insulating organic coating is obtained.

[0039] The coating can withstand temperatures up to 650℃ and can be used for extended periods at temperatures between room temperature and 550℃. In terms of thermal insulation, when the temperature of the exposed surface is 500℃, the temperature of the unexposed surface can be reduced to 300℃.

[0040] Example 2: Same as Example 1, except for the particle size and ratio of the hollow glass microspheres, as shown in Table 1 below:

[0041] Table 1. Particle size and proportion distribution of hollow glass microspheres

[0042] Hollow glass microspheres (20, 40, 65 μm) 0：0：30 0：30：0 30：0：0 10：10：10 15：10：5

[0043] Hollow glass microspheres with particle sizes of 20μm, 40μm, or 65μm exhibit poor thermal insulation performance. This is because the small particle size of the hollow glass microspheres and the use of large-sized particles result in a large number of pores being filled by other powder materials. When the exposed surface temperature is 500℃, the temperature of the unexposed surface is reduced to approximately 350℃. Coatings using hollow glass microspheres in a ratio of 10:10:10 and 15:10:5 provide thermal insulation performance of approximately 200℃, meaning that when the exposed surface temperature is 500℃, the temperature of the unexposed surface is approximately 300℃.

[0044] Example 3: Same as Example 1, except the weight ratio of boron oxide powder in the heat-resistant high-reflectivity outer coating was changed to 0 or 10. The high-reflectivity coating without added boron oxide powder developed microcracks on its surface at 600°C. The high-reflectivity coating with an addition of 10% reduced the overall heat resistance of the coating because excess molten boron oxide became a heat conduction channel.

[0045] Comparative Example 1: The rest is the same as in Example 1. The equipment surface only has a heat-resistant coating and no heat-resistant high-reflective outer layer. The temperature resistance can reach 650°C, but the coating will discolor and fine cracks will appear on the surface.

[0046] Comparative Example 2: Similar to Example 1, except for the total amount of water glass in the heat-resistant high-reflectivity outer coating, with weight ratios of 0, 10, and 20 for each. The high-reflectivity coating without added water glass developed microcracks and turned black at 500°C. The high-reflectivity coating with 10% water glass showed improved heat resistance, while the high-reflectivity coating with 20% water glass exhibited even higher heat resistance but was prone to cracking under thermal shock.

Claims

1. A highly reflective, high-temperature resistant, heat-insulating organic coating used as a protective outer layer in fire-fighting equipment, characterized in that, The organic coating comprises a heat-resistant, high-reflectivity outer layer and a heat-insulating inner layer. The heat-resistant, high-reflectivity outer layer is made of a heat-resistant, high-reflectivity outer layer coating, the raw materials of which include water glass, water-based silicone resin emulsion, nano-dispersible ATO powder, mica powder, and boron oxide powder. The heat-insulating inner layer is made of a heat-insulating inner layer coating, the raw materials of which include water-based silicone resin emulsion, hollow glass microspheres of different particle sizes, mica powder, talc powder, kaolin, and silica. In the heat-resistant, high-reflectivity outer layer, the mass ratio of water glass, water-based silicone resin emulsion, nano-dispersible ATO powder, mica powder, and boron oxide powder is 10-20:20-45:20-45:2-1. 0:2-10; In the heat-insulating inner layer, the mass ratio of water-based silicone resin emulsion, hollow glass microspheres, mica powder, talc powder, kaolin, and silica is 35-55:20-30:5-10:5-10:5-10:1-5; The hollow glass microspheres of different particle sizes include hollow glass microspheres with a mass ratio of 0.8-1.2:1.8-2.2:2.8-3.2 with particle sizes of 15-25μm, 35-45μm, and 60-75μm; The thickness ratio of the heat-resistant high-reflectivity outer layer to the heat-insulating inner layer is 30-100μm:0.5-1.8mm; The preparation method of the high-temperature heat-insulating organic coating includes the following steps: (1) Preparation of the heat-insulating inner coating; (2) Preparation of heat-resistant, high-reflectivity outer coating; (3) First, apply the heat-insulating inner layer coating by scraping or brushing onto the outer surface of the substrate. After surface drying, a substrate with a heat-insulating inner layer is obtained. Then, spray the heat-resistant and high-reflectivity outer layer coating onto the outer surface of the heat-insulating inner layer. After surface drying, perform curing treatment. After completion, a substrate with a high-reflectivity, high-temperature resistant, and heat-insulating organic coating is obtained.

2. The high-reflectivity, high-temperature resistant, heat-insulating organic coating according to claim 1, characterized in that, The water glass is one or more of sodium water glass, potassium water glass, or lithium water glass.

3. The high-reflectivity, high-temperature resistant, heat-insulating organic coating according to claim 1, characterized in that, In step (3), the spraying process parameters are: spray gun nozzle diameter is 1.0-4.0mm, spraying distance is 15-30cm, and spraying time is 3-10s.

4. The high-reflectivity, high-temperature resistant, heat-insulating organic coating according to claim 1, characterized in that, In step (3), the curing parameters are: curing at 180-250℃ for 15-45 minutes.