Heat-resistant coating with hot coating and preparation method thereof

Abstract

The invention relates to the field of heat-resistant coatings, in particular to a hot coating type heat-resistant coating which comprises the following substances in parts by weight: 50-70 parts of a potassium silicate aqueous solution, 10-25 parts of zinc oxide, 5-15 parts of a lanthanum-cerium mixture, 0.1-1 part of a defoaming agent, 0.5-2.5 parts of a silane coupling agent, 0.1-1 part of hydroxypropyl methyl cellulose, 0.1-2 parts of hydroxyethyl cellulose, 0.1-1 part of a wetting dispersant, 2-10 parts of water and 1-5 parts of silicon tripolyphosphate. The potassium silicate aqueous solution is used as an inorganic film forming matter, silicon tripolyphosphate is used as a curing agent, cross-linking curing can be achieved at high temperature, and the inorganic heat-resistant coating is formed. Zinc oxide can react with silicon hydroxyl of the potassium silicate aqueous solution to form a compact complex on the surface of the steel member. The silane coupling agent and the defoaming agent are silane substances and are hydrolyzed in the potassium silicate aqueous solution to form free Si-OH, and the free Si-OH can react with active silicon hydroxyl of the potassium silicate aqueous solution to improve the compactness of the coating and can be chemically bonded with a steel matrix to improve the adhesive force of the coating.

Description

Technical Field

[0001] The invention relates to the field of heat-resistant coatings, and in particular to a heat-resistant coating with thermal coating and a preparation method thereof. Background Art

[0002] Heat-resistant coatings, also known as high-temperature resistant coatings, generally refer to a type of functional coating that has no cracking, peeling, or shedding on the surface of the paint film at an ambient temperature above 200°C, and can still maintain good physical and mechanical properties, allowing the protected substrate to work normally. According to the different film-forming materials, heat-resistant coatings are divided into three categories: organic heat-resistant coatings, inorganic heat-resistant coatings, and organic-inorganic composite heat-resistant coatings. The film-forming materials of organic heat-resistant coatings mainly include four types of film-forming resins, such as heterocyclic polymers, organic silicon, organic fluorine, and organic titanium. The film-forming materials of inorganic heat-resistant coatings mainly include four types of film-forming materials, such as ethyl silicate, silica sol, silicate, and phosphate. For example, the Chinese patent CN 115418125A uses sodium silicate aqueous solution as a film-forming material, which is composed of a mixture of organic film-forming materials and inorganic film-forming materials. For example, the Chinese patent CN 116162367 A uses an inorganic modified silicone resin mixed with isopropyl alcohol, silicon dioxide, and aluminum oxide, and the silicone resin is used as an inorganic-organic composite film-forming material.

[0003] During the long-term high-temperature service of steel chimneys, high-temperature pipelines, oil cracking units, high-temperature furnaces and high-temperature reaction equipment in chemical plants, coking plants, gas plants, etc., the heat-resistant coating on the surface of the steel components will change color, crack, peel, fall off, etc., affecting its durability and protective effect. Therefore, it is necessary to carry out thermal protection maintenance on the in-service high-temperature steel components. However, the existing organic heat-resistant coatings, inorganic heat-resistant coatings and organic-inorganic composite coatings are all applied at room temperature. When applied on the surface of high-temperature steel components, they will crack and fall off, and cannot be firmly attached to the surface of high-temperature steel components, and cannot play the role of protecting steel components. Summary of the invention

[0004] In view of the problem that the existing heat-resistant coating is prone to cracking or falling off under high temperature conditions after being coated at room temperature, the present invention provides a heat-resistant coating with heat coating, comprising the following substances in parts by weight: 50-70 parts of potassium silicate aqueous solution, 10-25 parts of zinc oxide, 5-15 parts of lanthanum-cerium mixture, 0.1-1 part of defoaming agent, 0.5-2.5 parts of silane coupling agent, 0.1-1 part of hydroxypropyl methylcellulose, 0.1-2 parts of hydroxyethyl cellulose, 0.1-1 part of wetting dispersant, 2-10 parts of water, and 1-5 parts of silicon tripolyphosphate.

[0005] Specifically, the potassium silicate aqueous solution has a Baume degree of 40 and a modulus of 3.3; the lanthanum-cerium mixture is a mixed powder of lanthanum oxide and cerium oxide in a mass ratio of 1:2, and the powder diameter is 10 to 30 μm; the defoaming agent is a modified polydimethylsiloxane emulsion; the silane coupling agent is methyltrimethoxysilane; and the wetting and dispersing agent is alkylphenol ethoxide or sodium alkylbenzene sulfonate.

[0006] The preparation method of the heat-resistant coating with heat coating of the present invention comprises the following operations: weighing each substance by weight, stirring the potassium silicate aqueous solution and water with a stirrer, adding silane coupling agent, zinc oxide, lanthanum-cerium mixture, hydroxypropyl methylcellulose, hydroxyethyl cellulose, wetting dispersant and defoaming agent into the mixed liquid in sequence during the stirring process, adding silicon tripolyphosphate after stirring evenly, and stirring and mixing to obtain the coating.

[0007] The heat-resistant coating with heat coating of the present invention adopts potassium silicate aqueous solution as an inorganic film-forming material and silicon tripolyphosphate as a curing agent, which can achieve cross-linking and curing at high temperature to form an inorganic heat-resistant coating. Zinc oxide can react with the silanol group of the potassium silicate aqueous solution to form a dense complex on the surface of the steel component. Both the silane coupling agent and the defoamer are silane substances, which are hydrolyzed in the potassium silicate aqueous solution to form free Si-OH. Si-OH can react with the active silanol group of the potassium silicate aqueous solution to increase the density of the coating, and can also chemically bond with the steel substrate to improve the adhesion of the coating; hydroxypropyl methylcellulose and hydroxyethyl cellulose are used as thickeners to adjust the viscosity of the coating. The lanthanum-cerium mixture mainly improves the adhesion and heat resistance of the coating, especially in the high-temperature coating process, it can reduce the internal stress generated by the cross-linking reaction of the potassium silicate aqueous solution and silicon tripolyphosphate to avoid cracking of the coating. Compared with the existing room temperature coating of heat-resistant coatings, the present invention comprehensively utilizes the synergistic effect of various fillers and additives, and can solidify into a film on the surface of a high-temperature steel substrate at 50°C to 150°C. The coating construction can be completed without shutting down the in-service equipment, solving the surface thermal protection problem of high-temperature equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a SEM image of the coating of the heat-resistant coating with thermal coating in Example 1 after being coated and cured on a steel substrate at 150°C; Figure 2 This is the SEM image of the coating of comparative example 1 after the heat-resistant coating with thermal coating was coated and cured on a steel substrate at 150°C. DETAILED DESCRIPTION

[0009] The present invention is described below in conjunction with examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0010] Example 1

[0011] A heat-resistant coating with heat application includes the following materials in parts by weight: 60 parts of potassium silicate aqueous solution, 19 parts of zinc oxide, 10 parts of lanthanum-cerium mixture, 0.5 parts of modified polydimethylsiloxane emulsion, 1.5 parts of methyltrimethoxysilane coupling agent, 0.5 parts of hydroxypropyl methylcellulose, 0.5 parts of hydroxyethyl cellulose, 1 part of sodium alkylbenzene sulfonate, 5 parts of water, and 2 parts of silicon tripolyphosphate. Among them, the Baume degree of the potassium silicate aqueous solution is 40 and the modulus is 3.3; the lanthanum-cerium mixture is a mixed powder of lanthanum oxide and cerium oxide in a mass ratio of 1:2, and the powder diameter is 10 to 30 μm.

[0012] The preparation method of the heat-resistant coating with heat coating in this embodiment includes the following steps: weighing each substance by weight, stirring the potassium silicate aqueous solution and water with a stirrer at room temperature, adding methyltrimethoxysilane coupling agent, zinc oxide powder, lanthanum-cerium mixture, hydroxypropyl methylcellulose, hydroxyethyl cellulose, sodium alkylbenzene sulfonate, and modified polydimethylsiloxane emulsion to the mixed liquid in sequence during the stirring process, adding silicon tripolyphosphate after stirring evenly, and completing the coating as soon as possible with heat after stirring and mixing.

[0013] Example 2

[0014] A heat-resistant coating with heat application, comprising the following materials in parts by weight: 50 parts of potassium silicate aqueous solution, 25 parts of zinc oxide, 5 parts of lanthanum-cerium mixture, 1 part of modified polydimethylsiloxane emulsion, 2.5 parts of methyltrimethoxysilane coupling agent, 0.1 parts of hydroxypropyl methylcellulose, 0.1 parts of hydroxyethyl cellulose, 0.1 parts of alkylphenol ethoxide, 10 parts of water, and 5 parts of silicon tripolyphosphate. Among them, the Baume degree of the potassium silicate aqueous solution is 40 and the modulus is 3.3; the lanthanum-cerium mixture is a mixed powder of lanthanum oxide and cerium oxide in a mass ratio of 1:2, and the powder diameter is 10 to 30 μm.

[0015] The preparation method of the heat-resistant coating with heat coating in this embodiment includes the following steps: weighing each substance by weight, stirring the potassium silicate aqueous solution and water with a stirrer at room temperature, adding methyltrimethoxysilane coupling agent, zinc oxide powder, lanthanum-cerium mixture, hydroxypropyl methylcellulose, hydroxyethyl cellulose, alkylphenol ethoxide, and modified polydimethylsiloxane emulsion to the mixed liquid in sequence during the stirring process, adding silicon tripolyphosphate after stirring evenly, and completing the coating as soon as possible with heat after stirring and mixing.

[0016] Example 3

[0017] A heat-resistant coating with heat application, comprising the following materials in parts by weight: 70 parts of potassium silicate aqueous solution, 10 parts of zinc oxide, 15 parts of lanthanum-cerium mixture, 0.1 parts of modified polydimethylsiloxane emulsion, 0.5 parts of methyltrimethoxysilane coupling agent, 1 part of hydroxypropyl methylcellulose, 2 parts of hydroxyethyl cellulose, 0.5 parts of sodium alkylbenzene sulfonate, 2 parts of water, and 1 part of silicon tripolyphosphate. The Baume degree of the potassium silicate aqueous solution is 40 and the modulus is 3.3; the lanthanum-cerium mixture is a mixed powder of lanthanum oxide and cerium oxide in a mass ratio of 1:2, and the powder diameter is 10 to 30 μm.

[0018] The preparation method of the heat-resistant coating with heat coating in this embodiment includes the following steps: weighing each substance by weight, stirring the potassium silicate aqueous solution and water with a stirrer at room temperature, adding methyltrimethoxysilane coupling agent, zinc oxide powder, lanthanum-cerium mixture, hydroxypropyl methylcellulose, hydroxyethyl cellulose, sodium alkylbenzene sulfonate, and modified polydimethylsiloxane emulsion to the mixed liquid in sequence during the stirring process, adding silicon tripolyphosphate after stirring evenly, and completing the coating as soon as possible with heat after stirring and mixing.

[0019] Comparative Example 1

[0020] A heat-resistant coating comprises the following substances in parts by weight: 60 parts of potassium silicate aqueous solution, 0.5 parts of modified polydimethylsiloxane emulsion, 1.5 parts of methyltrimethoxysilane coupling agent, 0.5 parts of hydroxypropyl methylcellulose, 0.5 parts of hydroxyethyl cellulose, 1 part of sodium alkylbenzene sulfonate, 5 parts of water, and 2 parts of MDI-50 curing agent. The potassium silicate aqueous solution has a Baume degree of 40 and a modulus of 3.3.

[0021] The preparation method of the heat-resistant coating with heat coating in this embodiment includes the following steps: weighing each substance by weight, stirring the potassium silicate aqueous solution and water with a stirrer at room temperature, adding methyltrimethoxysilane coupling agent, hydroxypropyl methylcellulose, hydroxyethyl cellulose, sodium alkylbenzene sulfonate, and modified polydimethylsiloxane emulsion to the mixed liquid in sequence during the stirring process, adding silicon tripolyphosphate after stirring evenly, and completing the coating as soon as possible after stirring and mixing.

[0022] Figure 1 This is a SEM image of the coating of the heat-resistant coating of Example 1 after being coated and cured on a steel substrate at 150°C. It can be seen from the figure that the heat-resistant coating after 150°C heat coating has a continuous structure and forms a dense coating. Figure 2 This is a SEM image of the coating of the heat-resistant coating of comparative example 1 after being coated and cured on a steel substrate at 150°C. It can be seen from the figure that the heat-resistant coating after 150°C heat coating has a discontinuous structure, and each component is in an obvious dispersed state, and no dense coating is formed.

[0023] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat-resistant coating with heat coating, characterized in that: The invention comprises the following substances in parts by weight: 50-70 parts of potassium silicate aqueous solution, 10-25 parts of zinc oxide, 5-15 parts of lanthanum-cerium mixture, 0.1-1 parts of defoaming agent, 0.5-2.5 parts of silane coupling agent, 0.1-1 parts of hydroxypropyl methylcellulose, 0.1-2 parts of hydroxyethyl cellulose, 0.1-1 parts of wetting dispersant, 2-10 parts of water and 1-5 parts of silicon tripolyphosphate.

2. The heat-resistant coating material with heat application according to claim 1, characterized in that: The potassium silicate aqueous solution has a Baume degree of 40 and a modulus of 3.

3.

3. The heat-resistant coating material of the thermal coating type according to claim 1, characterized in that: The lanthanum-cerium mixture is a mixed powder of lanthanum oxide and cerium oxide in a mass ratio of 1:2, and the powder diameter is 10 to 30 μm.

4. The heat-resistant coating material of the thermal coating type according to claim 1, characterized in that: The defoaming agent is modified polydimethylsiloxane emulsion.

5. The heat-resistant coating material of heat-coating type according to claim 1, characterized in that: The silane coupling agent is methyltrimethoxysilane.

6. The heat-resistant coating material of heat-coating type according to claim 1, characterized in that: The wetting and dispersing agent is alkylphenol ethoxylate or sodium alkylbenzene sulfonate.

7. A method for preparing a heat-resistant coating with thermal coating as claimed in any one of claims 1 to 6, characterized in that: The method comprises the following operations: weighing various substances by weight, stirring potassium silicate aqueous solution and water with a stirrer, sequentially adding silane coupling agent, zinc oxide, lanthanum-cerium mixture, hydroxypropyl methylcellulose, hydroxyethyl cellulose, wetting dispersant and defoaming agent into the mixed liquid during the stirring process, adding silicon tripolyphosphate after stirring evenly, and stirring and mixing to obtain the mixture.

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