Room temperature cured waterborne inorganic hybrid high temperature resistant coating and method of making same

Abstract

The application discloses a room-temperature-cured water-based inorganic composite high-temperature-resistant paint and a preparation method thereof. The paint is prepared from a water-soluble inorganic silicon resin as a main film-forming material resin, an aluminum dihydrogen phosphate adhesive and active silicon resin for reaction grafting to prepare a water-based inorganic composite resin, inorganic temperature-resistant pigments such as copper-chromium black, fillers such as talc powder and silicon powder, and water-based wetting and dispersing aids. The paint has excellent adhesion on a metal substrate, can resist high temperature above 1000 DEG C, and can be used for high-temperature-resistant and anti-corrosion protection of various metal surfaces.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a water-based inorganic high-temperature resistant coating that is resistant to high temperatures (1200℃), corrosion-resistant, and has zero VOC emissions, and its preparation method. Background Technology

[0002] High-temperature resistant and anti-corrosion coatings generally refer to special functional coatings that do not change color or peel off at temperatures above 200℃, allowing the protected object to function normally in high-temperature environments. Currently, the most widely used high-temperature resistant coatings in industry are inorganic phosphate coatings. These use an aqueous solution of acidic phosphates as the main film-forming agent and possess excellent heat resistance, weather resistance, solvent resistance, and high-temperature oxidation resistance, maintaining long-term stability at temperatures ranging from 400 to 1000℃. However, inorganic phosphate coatings generally have strong acidity. To protect the metal substrate and pigments, chromic acid passivation treatment is usually required. Chromium has serious effects on human health and the environment. Furthermore, pure phosphate coatings require high-temperature curing (550℃), limiting their application range.

[0003] Inorganic high-temperature resistant coatings with siloxanes as the main film-forming substance have the advantages of being water-based, environmentally friendly, and capable of curing at room temperature. With the increasing research on polysiloxane resins obtained from the hydrolysis and condensation of organoalkoxysilanes, the preparation technology of water-soluble polysiloxane resins has become relatively mature, especially the technology developed by Evonik Specialty Chemicals (Shanghai) Co., Ltd. SIVO140 is a water-based inorganic sol-gel resin. While the resin itself is weakly acidic, its emulsion system is stable and exhibits good compatibility with both inorganic and organic resins. It also boasts the advantage of curing at room temperature or low temperatures. Studies have shown that this resin, when used alone on non-metallic surfaces such as concrete, can withstand temperatures up to 1200℃ with excellent adhesion. However, on metallic substrates, it loses its high-temperature protection due to poor adhesion.

[0004] Current research has not yet utilized this resin for high-temperature corrosion protection, especially for high-temperature protection on metal substrates with temperatures exceeding 1000°C. Therefore, developing a low-temperature curing, corrosion-resistant coating capable of withstanding 1000–1200°C on metal substrates is of great significance. Summary of the Invention

[0005] The application discloses a room-temperature-cured water-based inorganic composite high-temperature-resistant paint and a preparation method thereof. The application selects a water-soluble inorganic silicon resin as a main film-forming material resin for high temperature resistance, and prepares a water-based inorganic composite resin by grafting reaction of the aluminum dihydrogen phosphate adhesive and active silicon resin. The modification of the aluminum dihydrogen phosphate improves the film-forming performance of the weakly acidic water-based inorganic resin, improves the compactness, and makes the composite resin have higher adhesion on a smooth metal substrate. A flash rust inhibitor can be added to prevent the flash rust of the metal substrate, inorganic temperature-resistant pigments such as copper-chromium black, fillers such as talc powder and silicon powder, and water-based wetting and dispersing aids are added to prepare the room-temperature-cured water-based inorganic composite high-temperature-resistant paint. The paint has excellent adhesion on the metal substrate, can resist high temperature above 1000 DEG C, and can be used for high-temperature-resistant and anti-corrosion protection of various metal surfaces.

[0006] The object of the application can be achieved by the following technical scheme.

[0007] A room-temperature-cured water-based inorganic composite high-temperature-resistant paint is composed of the following components.

[0008]

[0009] In the technical scheme, the water-based inorganic composite resin is composed of the following components.

[0010]

[0011] In the technical scheme, the phosphate adhesive is composed of the following components.

[0012] Deionized water 60-70 parts

[0013] Phosphoric acid solution 25-35 parts

[0014] Aluminum hydroxide 3-8 parts

[0015] And the preparation method is that the deionized water and the phosphoric acid solution are heated and stirred, the temperature is increased to 60-80 DEG C, then the aluminum hydroxide is added in batches under constant temperature, the constant temperature condensation reflux is carried out for 0.5-1.5 hours, and the system is cooled to room temperature.

[0016] In the technical scheme, the prepared phosphate adhesive is added into the water-based inorganic gel resin, heated to 60-80 DEG C for constant temperature reaction for 1-3 hours, a pH regulator is added to adjust the pH to 6-7, finally, fumed silica is added, and the water-based inorganic composite resin is obtained after the system is cooled and discharged.

[0017] In the technical scheme, the water-based inorganic sol-gel resin is SIVO 140 resin of WACKER Special Chemicals (Shanghai) Co., Ltd. SIVO 140 resin.

[0018] In the technical solution of the present application: the pigment is at least one of copper-chromium black, chromium oxide green, chromium-iron black, chromium sesquioxide, cobalt blue and rutile titanium white powder; the filler is at least one of mica powder, talc powder, kaolin and silicon powder;

[0019] The glass powder is selected from low-melting-point glass powder with a melting temperature of 700-1000 DEG C; preferably, the glass powder is D270 of Amicron.

[0020] The dispersant is ZetaSperse 179, which is an aqueous pigment dispersant;

[0021] The wetting agent is TEGO 4200, which is an aqueous base material wetting agent;

[0022] The anti-flash rust agent is a complex anti-flash rust agent containing an organic chelate; preferably, the anti-flash rust agent is Pruf FR6100.

[0023] The thickening agent is a 1-10% hydroxyethyl cellulose aqueous solution.

[0024] A preparation method of the room-temperature-cured aqueous inorganic composite high-temperature-resistant coating, the method comprising the following steps:

[0025] S1: uniformly mixing the pigment, the filler, deionized water, the dispersant and grinding to a fineness of ≤30 um.

[0026] S2: adding the aqueous inorganic composite resin to the slurry obtained in step 1 in a proportion, fully stirring and dispersing the glass powder, the anti-flash rust agent and the wetting agent, and adding the thickening agent to adjust to a proper viscosity, and then filtering to obtain the room-temperature-cured aqueous inorganic composite high-temperature-resistant coating.

[0027] The present application has the following advantages:

[0028] (1) The present application uses an aqueous inorganic gel resin and a mixed phosphate binder, the main component of the aqueous inorganic gel resin is a polysiloxane prepolymer containing active groups with a certain degree of polymerization. When the prepolymer is heated alone to form a film, the hydrocarbon group connected to the Si atom is oxidized by heat to form a highly cross-linked Si-O-Si bond, but due to the large shrinkage stress, the film layer is not firmly adhered or falls off on the smooth metal substrate. Therefore, the present application adds a dihydrogen phosphate film former, which contains active hydroxyl groups that can cross-link with water-soluble silicon resin, and forms a more dense Si-O-P bond at high temperature, effectively reducing the shrinkage stress and improving the adhesion to the substrate at high temperature, thereby providing long-term high-temperature resistance. The modification of aluminum dihydrogen phosphate improves the film forming performance of the weakly acidic aqueous inorganic resin, increases the density and improves the adhesion of the composite resin on the smooth metal substrate.

[0029] (2) The present application is to add amine neutralizer to make the PH of the coating system between 6 and 8, to reduce the corrosion of the coating acidity to the metal substrate, and to add anti-flash rust agent to effectively prevent flash rust on the metal substrate.

[0030] (3) The present application selects low-melting point glass powder D270 with a melting temperature of 700-1000℃, which is a new functional powder material for environmental protection. When the temperature reaches 700℃, the product continues to melt into a liquid, realizing the functions of film formation, filling and dispersion.

[0031] (4) The present application is a single-component water-based inorganic coating with low natural cost, convenient construction, room temperature curing, and good corrosion protection. The coating can be used alone on polished metal substrates, and a dry film thickness of 50-100 microns can achieve high temperature protection of 1000-1200℃, with considerable economic benefits.

[0032] Finally, the coating of the present application is a product with almost zero VOC emission, low load and safety and environmental protection. It can be directly sprayed on the surface of an alloy or steel plate sample after oil removal, rust removal, polishing or sandblasting treatment. The coating is easy to apply, and the coating can be used at high temperature after self-drying at room temperature for 24 hours. After testing, a single coating with a dry film thickness of 60 microns does not fall off after 100h of baking at 800℃ and cold water washing, and does not discolor, fade, crack or fall off after 8 hours of 1000h testing, with an adhesion of ≤1 level. DETAILED DESCRIPTION

[0033] The present application will be further described below in conjunction with examples, but the scope of protection of the present application is not limited thereto.

[0034] Preparation of phosphate adhesives of Examples 1-9:

[0035] In a three-necked flask, 660g of deionized water and 270g of 85% phosphoric acid solution were added, heated and stirred, and when the temperature rose to 70℃, 62.4g of aluminum hydroxide was added in batches, and when the temperature rose to 95℃, the system was kept at constant temperature and refluxed for 1h, and then cooled to below 50℃, and the product was discharged for use.

[0036] Preparation of water-based inorganic composite resins of Examples 1-9 and Comparative Examples 1-3:

[0037] The phosphate adhesives and water-based inorganic gel resins were added in the three-necked flask in proportion, heated to 70℃ and kept at constant temperature for 2h, then pH adjuster (N-dimethyl ethanolamine) was added to adjust the pH to 6.5, and finally fumed silica was added to adjust the viscosity of the resin to 60KU, and the system was cooled and discharged.

[0038] The amount of water-based inorganic composite resin is as follows:

[0039]

[0040]

[0041] Preparation of high temperature resistant slurry:

[0042] Slurry A: Take 15g of rutile titanium dioxide, 20g of silica powder, 9g of talc powder, 40g of deionized water, and 0.8g of dispersant (water-based pigment dispersant is Zeta Sperse 179), mix uniformly and grind to a fineness of ≤30um;

[0043] Slurry B: Take 15g of Bayer industrial grade chromium oxide green, 20g of silica powder, 9g of talc powder, 40g of deionized water, and 0.8g of dispersant (water-based pigment dispersant is Zeta Sperse 179), mix uniformly and grind to a fineness of ≤30um;

[0044] Slurry C: Take 15g of copper chromium black, 20g of silica powder, 9g of talc powder, 40g of deionized water, and 0.8g of dispersant (water-based pigment dispersant is Zeta Sperse 179), mix uniformly and grind to a fineness of ≤30um.

[0045] Example 1-9 and Comparative Example 1-3 of room temperature cured water-based inorganic composite high temperature resistant paint

[0046] Add the water-based inorganic composite resin to the slurry A, slurry B or slurry C according to the proportion, add glass powder (D270 of Anmimicro), anti-flash rust agent (anti-flash rust agent is Puwei FR6100), wetting agent (water-based substrate wetting agent TEGO 4200), stir and disperse thoroughly, add thickening agent (5% hydroxyethyl cellulose aqueous solution) and filter, to obtain room temperature cured water-based inorganic composite high temperature resistant paint.

[0047]

[0048] After the obtained water-based inorganic composite high temperature resistant paint is stirred uniformly, air spraying is used for coating. The coated workpiece is placed in a dry and ventilated constant temperature lamp box for 24 hours, and the performance test is carried out according to the following table:

[0049] Table 1 Performance test of room temperature cured water-based inorganic composite high temperature resistant paint

[0050]

[0051]

Claims

1. A room temperature cured, waterborne inorganic hybrid high temperature resistant coating, characterized in that consists of: aqueous inorganic composite resin 55~58 parts pigment 10~20 parts filler 20~40 parts glass powder 12~18 parts deionized water 30~50 parts dispersant 0.3~1 part thickening agent 5~15 parts anti-tarnish agent 0.8~1.5 parts wetting agent 0.1~1 part; The anti-tarnish agent is Pruf FR6100; The aqueous inorganic composite resin consists of: aqueous inorganic gel resin 50 parts phosphate binder 5~10 parts pH regulator 0.2~0.5 parts fumed silica 0.2~0.5 parts; The preparation method of the aqueous inorganic composite resin is to add the prepared phosphate binder to the aqueous inorganic gel resin, heat to 60~80℃, constant temperature reaction for 1~3 hours, add pH regulator to adjust pH to 6~7, finally add fumed silica, cool the system and then discharge to obtain the aqueous inorganic composite resin; The phosphate binder consists of: deionized water 60~70 parts phosphoric acid solution 25~35 parts aluminum hydroxide 3~8 parts; The preparation method of the phosphate binder is to heat and stir deionized water and phosphoric acid solution, the temperature is raised to 60~80℃, then constant temperature and batch addition of aluminum hydroxide, after that constant temperature and condensation reflux for 0.5~1.5 h, cool to room temperature; The mass concentration of the phosphoric acid solution is 80~90%; The aqueous inorganic sol-gel resin is Dynasylan® SIVO 140 resin of Wanjing Special Chemical (Shanghai) Co., Ltd.

2. The room temperature cured, waterborne inorganic hybrid high temperature resistant coating according to claim 1, characterized in that The pH regulator is N-dimethyl ethanolamine.

3. The room temperature cured, waterborne inorganic hybrid high temperature resistant coating according to claim 1, characterized in that: The pigment is at least one of copper-chromium black, chromium oxide green, chromium-iron black, chromium sesquioxide, cobalt blue and rutile titanium white powder; The filler is at least one of mica powder, talc powder, kaolin and silicon powder; The glass powder is low melting point glass powder with melting temperature of 700~1000℃; The dispersant is aqueous pigment dispersant Zeta Sperse 179; The wetting agent is aqueous base material wetting agent TEGO 4200; The thickening agent is 1~10% hydroxyethyl cellulose aqueous solution.

4. The ambient cure waterborne inorganic hybrid high temperature resistant coating according to claim 1, wherein: The glass powder is D270 of Anmi Micro-nano.

5. A process for the preparation of a room temperature cured water borne inorganic hybrid high temperature resistant coating as claimed in claim 1, characterized in that: The method comprises the following steps: S1: mix the pigment, filler, deionized water and dispersant uniformly and grind to fineness ≤30um; S2: add the aqueous inorganic composite resin to the slurry obtained in step 1 according to the proportion, add glass powder, anti-tarnish agent, wetting agent and stir well, add thickening agent to adjust the viscosity, then filter to obtain the room temperature cured aqueous inorganic composite high temperature resistant coating.

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