Water-based environment-friendly high-temperature-resistant inorganic ceramic anticorrosive paint and preparation method thereof

Abstract

The invention discloses a water-based environment-friendly high-temperature-resistant inorganic ceramic anticorrosive coating and a preparation method thereof, and belongs to the field of coating preparation. According to the scheme, the water-based environment-friendly high-temperature-resistant inorganic ceramic anticorrosive coating is prepared from the following components in parts by weight: 40 to 60 parts of silica sol, 30 to 36 parts of methyltriethoxysilane, 5 to 10 parts of montmorillonite, 3 to 8 parts of colloidal cellulose, 5 to 8 parts of copper complex black, 0.5 to 2.0 parts of other fillers and 5 to 20 parts of deionized water. The preparation method adopts a classic sol-gel method, the production process is simple and efficient, and the cost is low. The water-based environment-friendly high-temperature-resistant inorganic ceramic anticorrosive paint prepared by the formula can resist the high temperature of 800 DEG C, and the corrosion area is less than 1% according to a 720-hour neutral salt spray test result. The formula is free of organic solvents and artificially synthesized polymer materials, the water-based ceramic coating is prepared from natural montmorillonite and cellulose structures, VOC pollution is avoided, the production cost is low, and the water-based ceramic coating is a very environment-friendly inorganic ceramic coating.

Description

Technical Field

[0001] The present invention relates to the field of coating preparation, and particularly relates to an environmentally friendly waterborne high-temperature resistant inorganic ceramic anti-corrosion coating and a preparation method thereof. Background Art

[0002] A coating is a material that can be applied to the surface of an object by different construction processes to form a firmly adhered, continuous solid film with a certain strength. The formed film is generally called a coating film, also known as a coating layer. The composition of a coating generally includes film-forming substances (i.e., binders), pigments and fillers, solvents, additives, etc. According to the different film-forming substances used in the coating, it is divided into two major categories: waterborne coatings and organic solvent-based coatings. Organic solvent-based coatings will release volatile organic compounds such as formaldehyde and benzene during the production, preparation, coating and curing processes, causing VOC pollution. Waterborne coatings use water as a solvent, which can avoid VOC pollution. According to the different film-forming substances in the coating, they are divided into inorganic waterborne coatings and synthetic organic waterborne coatings.

[0003] Ceramic coating is a kind of waterborne coating, usually a liquid or solid material prepared with nano-inorganic compounds as film-forming substances, water as a solvent and supplemented with other fillers, additives, etc. It can be compounded with organic fillers to form an organic-inorganic composite ceramic coating. Ceramic coatings were first prepared by the sol-gel method technology that emerged in the 1960s, using liquid solutions to form a three-dimensional network structure gel to form solid films with a wide range of chemical compositions. Waterborne ceramic coatings have the characteristics of water resistance, alcohol resistance, wear resistance, scratch resistance, and high temperature resistance. Inorganic high-temperature resistant coatings have high hardness, but the paint film is brittle, has poor water resistance before complete curing, and has relatively strict requirements for substrate treatment. The existing waterborne inorganic high-temperature resistant anti-corrosion coatings in the prior art can generally only withstand temperatures below 500°C. When the temperature exceeds 500°C, the coating is prone to cracking, and the adhesion and anti-corrosion performance are poor. General anti-corrosion coatings need to add fillers with anti-corrosion functions to achieve the purpose, and their components are mostly organic components, with relatively high costs, but they perform poorly in terms of oxidation resistance and aging resistance. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide an environmentally friendly waterborne high-temperature resistant inorganic ceramic anti-corrosion coating; another object of the present invention is to provide a preparation method of an environmentally friendly waterborne high-temperature resistant inorganic ceramic anti-corrosion coating.

[0005] Technical Solution: An environmentally friendly waterborne high-temperature resistant inorganic ceramic anti-corrosion coating, the formula contains 40-60 parts by weight of silica sol, 30-36 parts by weight of methyltriethoxysilane, 5-10 parts by weight of montmorillonite, 3-8 parts by weight of colloidal cellulose, 5-8 parts by weight of copper complex black, 0.5-2.0 parts by weight of other fillers, and 5-20 parts by weight of deionized water.

[0006] Preferably, the filler is an antifoaming agent and an anti-cracking powder. More preferably, the antifoaming agent is selected from one of antifoaming agent 532 or antifoaming agent 757, and the anti-cracking powder is GT-50.

[0007] Preferably, the silica sol is an alkaline silica sol with a silica content of not less than 50%.

[0008] Preferably, the D90 particle size of montmorillonite does not exceed 35 μm.

[0009] Preferably, the D90 particle sizes of copper complex black and other fillers do not exceed 50 μm.

[0010] The preparation method of the water-based environmentally friendly high-temperature resistant inorganic ceramic anticorrosive coating comprises the following steps: S1. Add the silica sol into a dispersion container according to the formula amount. Under rapid stirring, successively add montmorillonite and colloidal cellulose, and continue stirring until uniform to obtain liquid material 1; S2. Add methyltriethoxysilane into another dispersion container of the liquid material according to the formula amount. Add 1 part of formic acid under stirring and stir evenly to obtain liquid material 2; S3. Slowly add liquid material 2 into liquid material 1, control the reaction temperature not to exceed 45 °C. After the addition is completed, stir and react for 3 - 7 h to obtain liquid material 3; S4. Add copper complex black, other fillers, and deionized water into liquid material 3 according to the formula amount, stir evenly, adjust the pH of the system to 3 - 5 with formic acid. Under ultrasonic treatment, stir until there are no bubbles in the system, and continue stirring for 1 - 2 h to obtain the coating.

[0011] Preferably, in step S1, the rapid stirring rate is not less than 450 r / min.

[0012] Preferably, in step S4, the ultrasonic power is 80 - 150 W.

[0013] Beneficial effects:

[0014] 1. The principle of inorganic ceramic coatings is that crosslinking occurs between silanol hydroxyl groups, between silanol and alkoxy groups, between silanol and hydroxyl groups on the substrate surface, between silanol and hydroxyl groups on the surface of pigments and fillers, as well as coordination bond binding between molecules, ultimately forming a hard ceramic-like coating. Conventional waterborne inorganic ceramic coatings can generally only withstand high temperatures below 500°C. When the temperature exceeds 500°C, the coating is prone to cracking and the adhesion decreases. In this solution, natural montmorillonite, which is widely sourced and inexpensive, is used as a high-temperature resistant filler. The main components of montmorillonite are silica, alumina, and other minerals. Its silica is the same as the silica sol component in the formula and can also form a three-dimensional network structure with siloxane, which is the classic structure of inorganic ceramic coatings and will not cause a decline in coating performance. The contained alumina can also form a three-dimensional network structure with siloxane. Finally, the prepared coating has a high-temperature resistance performance improved to about 700°C. After physically blending with copper complex black, the high-temperature resistance performance of the coating is further improved, and the finally prepared coating can withstand high temperatures of 800°C.

[0015] 2. Inorganic ceramic coatings prepared by the classical sol-gel method will degrade under high-temperature conditions, and large-area defects will form on the coating surface, and their corrosion resistance is average. The traditional method generally uses organosilicon resin to prepare organic-inorganic hybrid ceramic coatings to improve corrosion resistance, and organic compounds are required to modify the silicone resin, which undoubtedly increases production costs. At the same time, it is impossible to avoid the problem of excessive VOC pollution caused by organic coatings mentioned in the background technology. Cellulose is a natural polysaccharide macromolecule compound containing a large number of hydroxyl groups. Colloidal cellulose generally has a smaller molecular weight than natural cellulose and has good solubility. It can be inserted into the Si-O bond crosslinking network structure formed between silanol, silanol hydroxyl groups, alkoxy groups, and hydroxyl groups on the substrate surface through the C-O bond connection method, endowing the ceramic coating with a certain flexibility. Since the C-O bond energy is lower than the Si-O bond energy, under corrosive conditions, the C-O bond formed between cellulose molecules and the ceramic coating is preferentially broken to protect the main molecular structure of the coating, thereby improving the corrosion resistance of the coating. After the prepared coating is maintained at 500°C for 100 hours, the rust area after 720 hours of neutral salt spray is less than 1%.

[0016] 3. The formula of this solution contains no organic solvents and no synthetic polymer materials. It uses natural montmorillonite and cellulose structures to prepare waterborne ceramic coatings, which have no VOC pollution and low production costs, and is a very environmentally friendly formula. Description of the Drawings

[0017] Figure 1 It is a graph of the high-temperature resistance test results of Coating 1 prepared in Example 1 of the present invention at 600 - 700°C; Figure 2 It is a graph of the high-temperature resistance test results of Coating 1 prepared in Example 1 of the present invention at 700 - 800°C; Figure 3It is the salt spray test result diagram of Coating 1 prepared in Example 1 of the present invention; Figure 4 It is the salt spray test result diagram of Coating 6 prepared in Comparative Example 3 of the present invention; Figure 5 It is the salt spray test result diagram of Coating 7 prepared in Comparative Example 4 of the present invention. Detailed implementation manners

[0018] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Example 1

[0020] Add 50 kg of silica sol (silicon dioxide content 50%) to a dispersion container, stir at 450 r / min for 20 min, and sequentially add 7 kg of montmorillonite (particle size D90 = 28 μm) and 5 kg of colloidal cellulose (degree of polymerization ≤ 350, viscosity 1500 - 4500 mPa·S), and continue to stir for 2 h until uniform to obtain Feed Liquid 1.

[0021] Add 33 kg of methyltriethoxysilane to another stirring container, stir at 250 r / min for 10 min, then add 1 kg of formic acid, and continue to stir for 10 min to obtain Feed Liquid 2.

[0022] Drop Feed Liquid 2 into Feed Liquid 1, control the reaction temperature not to exceed 45°C, after the feeding is completed, stir and react for 5 h to obtain Feed Liquid 3.

[0023] Add 6 kg of copper complex black (particle size D90 = 30 μm), 0.5 kg of defoamer 532, 0.5 kg of anti-cracking powder GT-50 (particle size 20 μm), and 10 kg of deionized water to Feed Liquid 3, stir at 250 r / min for 1 h, adjust the pH of the system to 4 with formic acid, perform ultrasonic treatment at 120 W, stir until there are no bubbles in the system, and continue to stir for 1.5 h to obtain Coating 1.

[0024] Example 2

[0025] Add 40 kg of silica sol (silicon dioxide content 55%) to a dispersion container, stir at 500 r / min for 20 min, and sequentially add 5 kg of montmorillonite (particle size D90 = 35 μm) and 3 kg of colloidal cellulose (degree of polymerization ≤ 350, viscosity 1500 - 4500 mPa·S), and continue to stir for 2 h until uniform to obtain Feed Liquid 1.

[0026] Add 30 kg of methyltriethoxysilane to another stirring container, stir at 250 r / min for 10 min, then add 1 kg of formic acid, and continue to stir for 10 min to obtain Feed Liquid 2.

[0027] Add feed liquid 2 dropwise to feed liquid 1, control the reaction temperature not to exceed 45°C, and after the addition is completed, stir the reaction for 5 hours to obtain feed liquid 3.

[0028] To liquid 3, add 5 kg of copper complex black (particle size D90 = 50 μm), 0.25 kg of defoamer 757, 0.25 kg of anti-cracking powder GT-50 (particle size D90 = 50 μm), and 5 kg of deionized water. Stir at 250 r / min for 1 h. Adjust the pH of the system to 3 with formic acid. Ultrasonicate at 80 W and stir until there are no bubbles in the system. Continue stirring for 1.5 h to obtain coating 2.

[0029] Example 3

[0030] Add 60 kg of silica sol (silicon dioxide content 50%) into a dispersion container and stir at 500 r / min for 20 min. Then, add 10 kg of montmorillonite (particle size D90 = 18 μm) and 8 kg of colloidal cellulose (degree of polymerization ≤ 350, viscosity 1500-4500 mPa·s) in sequence. Continue stirring for 2 h until the mixture is homogeneous to obtain liquid 1.

[0031] 36 kg of methyltriethoxysilane was added to another stirring container, and after stirring at 250 r / min for 10 min, 1 kg of formic acid was added and stirring was continued for 10 min to obtain feed solution 2.

[0032] Add feed liquid 2 dropwise to feed liquid 1, control the reaction temperature not to exceed 45°C, and after the addition is completed, stir the reaction for 7 hours to obtain feed liquid 3.

[0033] To liquid 3, add 8 kg of copper complex black (particle size D90 = 20 μm), 1 kg of defoamer 757, 1 kg of anti-cracking powder GT-50 (particle size D90 = 20 μm), and 20 kg of deionized water. Stir at 250 r / min for 1 h. Adjust the pH of the system to 5 with formic acid. Ultrasonicate at 150 W and stir until there are no bubbles in the system. Continue stirring for 1.5 h to obtain coating 3.

[0034] Comparative Example 1

[0035] Add 50 kg of silica sol (silicon dioxide content 50%) into a dispersion container and stir at 500 r / min for 20 min. Then, add 7 kg of montmorillonite and 5 kg of colloidal cellulose (degree of polymerization ≤ 350, viscosity 1500-4500 mPa·s) in sequence. Continue stirring for 2 h until the mixture is uniform, to obtain liquid 1.

[0036] 33 kg of methyltriethoxysilane was added to another stirring container, and after stirring at 250 r / min for 10 min, 1 kg of formic acid was added and stirring was continued for 10 min to obtain feed solution 2.

[0037] Add 2 drops of liquid material 2 to liquid material 1, control the reaction temperature not exceeding 45 °C. After the addition is completed, stir and react for 5 h to obtain liquid material 3.

[0038] Add 0.5 kg of defoaming agent 532, 0.5 kg of anti-cracking powder GT-50, and 10 kg of deionized water to liquid material 3, stir at 250 r / min for 1 h, adjust the pH of the system to 4 with formic acid, perform ultrasonic treatment at 120 W, stir until there are no bubbles in the system, and continue to stir for 1.5 h to obtain coating 4.

[0039] Comparative Example 2

[0040] Add 60 kg of silica sol (silicon dioxide content 50%) to a dispersion container, stir at 450 r / min for 20 min, add 5 kg of colloidal cellulose (degree of polymerization ≤ 350, viscosity 1500 - 4500 mPa·S), and continue to stir for 2 h until uniform to obtain liquid material 1.

[0041] Add 33 kg of methyltriethoxysilane to another stirring container, stir at 250 r / min for 10 min, then add 1 kg of formic acid and continue to stir for 10 min to obtain liquid material 2.

[0042] Add liquid material 2 dropwise to liquid material 1, control the reaction temperature not exceeding 45 °C. After the addition is completed, stir and react for 5 h to obtain liquid material 3.

[0043] Add 6 kg of copper complex black, 0.5 kg of defoaming agent 532, 0.5 kg of anti-cracking powder GT-50, and 10 kg of deionized water to liquid material 3, stir at 250 r / min for 1 h, adjust the pH of the system to 4 with formic acid, perform ultrasonic treatment at 120 W, stir until there are no bubbles in the system, and continue to stir for 1.5 h to obtain coating 5.

[0044] Comparative Example 3

[0045] Add 50 kg of silica sol (silicon dioxide content 50%) to a dispersion container, stir at 450 r / min for 20 min, add 7 kg of montmorillonite, and continue to stir for 2 h until uniform to obtain liquid material 1.

[0046] Add 33 kg of methyltriethoxysilane to another stirring container, stir at 250 r / min for 10 min, then add 1 kg of formic acid and continue to stir for 10 min to obtain liquid material 2.

[0047] Add liquid material 2 dropwise to liquid material 1, control the reaction temperature not exceeding 45 °C. After the addition is completed, stir and react for 5 h to obtain liquid material 3.

[0048] Add 6 kg of copper complex black, 0.5 kg of defoamer 532, 0.5 kg of anti-cracking powder GT-50, and 10 kg of deionized water to the feed liquid 3, stir at 250 r / min for 1 h, adjust the pH of the system to 4 with formic acid, perform ultrasonic treatment at 120 W, stir until there are no bubbles in the system, and continue stirring for 1.5 h to obtain coating 6.

[0049] Comparative Example 4

[0050] Add 50 kg of silica sol (silicon dioxide content 50%) to the dispersion container, stir at 450 r / min for 2 h until uniform to obtain feed liquid 1.

[0051] Add 33 kg of methyltriethoxysilane to another stirring container, stir at 250 r / min for 10 min, then add 1 kg of formic acid and continue stirring for 10 min to obtain feed liquid 2.

[0052] Drop feed liquid 2 into feed liquid 1, control the reaction temperature not to exceed 45 °C. After the addition is complete, stir and react for 5 h to obtain feed liquid 3.

[0053] Add 0.5 kg of defoamer 532, 0.5 kg of anti-cracking powder GT-50, and 10 kg of deionized water to the feed liquid 3, stir at 250 r / min for 1 h, adjust the pH of the system to 4 with formic acid, perform ultrasonic treatment at 120 W, stir until there are no bubbles in the system, and continue stirring for 1.5 h to obtain coating 7.

[0054] Adhesion test:

[0055] Test method: pull-off method; Test process: Apply the coating on a steel plate with a uniform surface structure and a thickness of 3 mm with a uniform thickness, let it stand for 48 h, and keep it warm at 80 °C for 2 h to obtain the test sample; wipe the surface of the sample to ensure the surface of the sample is clean. After mixing the adhesive evenly at 1:1, apply it on the test column, and place the test column directly on the surface of the test sample coating; after the adhesive cures, use a special cutter to cut through the coating to expose the substrate, and the test area for pulling is 100π mm 2 ; Connect the fully automatic digital display adhesion tester to the test column, set the pulling speed limit measurement value of the instrument to the appropriate range, perform the pulling test until the coating is damaged, and record the pulling force value at this time; perform the test 3 times and take the average value. The results are shown in Table 1.

[0056] Pencil hardness test:

[0057] Test method: manual pushing method; Testing process: Use a blade to cut out the lead of a Zhonghua pencil so that the lead part is about 4 mm, and grind it flat with sandpaper. Place the hardness tester flat on the test piece. Insert the processed pencil into the instrument, hold it with the thumb and middle finger at the center of the two wheels, push the hardness tester forward 3 cm, remove the hardness tester, and wipe off the scratched pencil with an eraser. After each test, the pencil needs to be polished again. Repeat the above steps until the coating is scratched. Do at least three positions for each coating, take the average value, and the results are summarized in Table 1.

[0058] Table 1: Test Results of Mechanical Properties

[0059] From the results in the above table, it can be seen that the hardness of the coating prepared after adding colloidal cellulose is lower than that of coatings 6 and 7 without adding cellulose. This indicates that the hydroxyl groups of cellulose are inserted into the Si-O bond cross-linked network structure formed between silanol, silanol groups, alkoxy groups and the hydroxyl groups on the substrate surface through the C-O bond connection method, endowing the ceramic coating with a certain flexibility.

[0060] High-temperature resistance performance test:

[0061] Test method: Coat the coating on a steel plate with a uniform surface structure and a thickness of 3 mm with a uniform thickness, let it stand for 48 h, and keep it at 80 °C for 2 h to obtain the test sample; wipe the surface of the sample to ensure that the surface of the sample is clean; place it in a high-temperature electric furnace for 2 h, record the surface state of the specimen, and the results are summarized in Table 2 below. The high-temperature test results of Coating 1 at 600 - 700 °C are shown in the appendix Figure 1 and the high-temperature test results of Coating 1 at 700 - 800 °C are shown in the appendix Figure 2 .

[0062] Table 2: Test Results of Temperature Resistance Performance

[0063] From the results in the above table, it can be seen that Coating 7 prepared without adding montmorillonite and copper complex black starts to crack at 500 - 600 °C, Coating 4 prepared with only montmorillonite and without copper complex black does not crack at 600 - 700 °C and cracks when the temperature is raised to 700 - 800 °C, and Coating 5 prepared with only copper complex black cracks at 600 - 700 °C. This indicates that the montmorillonite component has a more significant impact on the high-temperature resistance performance of the coating. When both montmorillonite and copper complex black are added, the high-temperature resistance performance of the coating is the best, and it remains intact even at 800 °C.

[0064] Salt spray performance test:

[0065] Test method: Prepare a sodium chloride solution with a concentration of 5% and a pH of 6.8; Reference standard: GB / T 6461-2002, High-temperature calcination conditions for test samples: Maintain at 500 °C for 100 h; Test time: 720 h. The summary of test results is shown in Table 3 below. The salt spray test results of Coating 1 are shown in the appendix Figure 3 , The salt spray test results of Coating 6 are shown in the appendix Figure 4 , The salt spray test results of Coating 7 are shown in the appendix Figure 5 . Table 3: Salt spray test results

[0066] It can be seen from the results in the above table that after Coating 6 and Coating 7 prepared without adding colloidal cellulose are calcined at 500 °C for 100 h, the corrosion rate after 720 h is 17%; After Coating 1, Coating 2 and Coating 3 prepared by adding colloidal cellulose are calcined at 500 °C for 100 h, they still have the neutral salt spray resistance performance after 720 h, and the corrosion rate is less than 10%. It shows that the inorganic ceramic coating prepared by this solution has excellent anti-corrosion effect.

[0067] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. An aqueous environmentally friendly high-temperature resistant inorganic ceramic anti-corrosion coating, characterized in that: The formulation contains 40 - 60 parts by weight of silica sol, 30 - 36 parts of methyltriethoxysilane, 5 - 10 parts of montmorillonite, 3 - 8 parts of colloidal cellulose, 5 - 8 parts of copper complex black, 0.5 - 2.0 parts of filler, and 5 - 20 parts of deionized water.

2. The water-based environmentally friendly high-temperature resistant inorganic ceramic anti-corrosion coating according to claim 1, characterized in that: The other fillers are defoamer and anti - cracking powder. Among them, the defoamer is selected from one of defoamer 532 or defoamer 757, and the anti - cracking powder is GT - 50.

3. The water-based environmentally friendly high-temperature resistant inorganic ceramic anti-corrosion coating according to claim 1, wherein: The silica sol is alkaline silica sol with a silica content of not less than 50%.

4. The waterborne environmentally friendly high-temperature resistant inorganic ceramic anti-corrosion coating according to claim 1, wherein: The particle size D90 of montmorillonite does not exceed 35μm.

5. The water-based environmentally friendly high-temperature resistant inorganic ceramic anti-corrosion coating according to claim 1, characterized in that: The particle size D90 of copper complex black and other fillers does not exceed 50μm.

6. A preparation method of the waterborne environmentally friendly high-temperature resistant inorganic ceramic anticorrosive coating according to any one of claims 1-5, characterized in that, It includes the following steps: S1. Add the silica sol into the dispersion container according to the formulation amount. Under rapid stirring, successively add montmorillonite and colloidal cellulose, and continue stirring until homogeneous to obtain liquid material 1. S2. Add methyltriethoxysilane into another stirring container according to the formulation amount. Add 1 part of formic acid under stirring and stir evenly to obtain liquid material 2. S3. Slowly add liquid material 2 into liquid material 1, control the reaction temperature not to exceed 45°C. After the addition is completed, stir and react for 3 - 7h to obtain liquid material 3. S4. Add copper complex black, other fillers, and deionized water into liquid material 3 according to the formulation amount, stir evenly, adjust the pH of the system to 3 - 5 with formic acid. Under ultrasonic treatment, stir until there are no bubbles in the system, and continue stirring for 1 - 2h to obtain the coating.

7. The preparation method of the water-based environmentally friendly high-temperature resistant inorganic ceramic anti-corrosion coating according to claim 6, characterized in that, In step S1, the rapid stirring rate is not less than 450 r / min.

8. The preparation method of the waterborne environmentally friendly high-temperature resistant inorganic ceramic anti-corrosion coating according to claim 6, characterized in that, In step S4, the ultrasonic power is 80 - 150W.

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