Corrosion-resistant, hydrophilic, easy-to-clean coating and method for its preparation

Abstract

The application discloses a kind of corrosion-resistant hydrophilic easy-to-clean coatings, it is characterized in that: the weight parts composition of the corrosion-resistant hydrophilic easy-to-clean coatings is: water 20-60 parts, potassium silicate 30-50 parts, methyl potassium silicate 1-8 parts, silane oligomer 2-8 parts, acetylenic diol polyoxyethylene ether 0.2-0.6 parts, butanol 0.8 parts, boron trifluoride monoethylamine complex 0.5 parts.Compared with the prior art, the application is coated to the surface of stainless steel plate, glass, galvanized sheet, cold plate, magnesium-aluminum alloy and other metal materials, the manufacturing steps are simple, and the water resistance and corrosion resistance are good.

Description

Technical Field

[0001] This invention relates to the field of inorganic hydrophilic coatings, specifically to a corrosion-resistant, hydrophilic, and easy-to-clean coating and its preparation method. Background Technology

[0002] Hydrophilic coatings possess unique surface wetting properties, allowing them to quickly form a water film upon contact with water, thus lifting surface stains and achieving an easy-to-clean effect. They are increasingly being used in industries such as construction, photovoltaics, automobiles, and home appliances. However, due to issues such as low coating thickness and poor wetting properties, hydrophilic coatings are currently only widely used on glass and stainless steel surfaces.

[0003] Currently, existing hydrophilic coatings have the following problems:

[0004] 1. Existing inorganic hydrophilic coatings mainly rely on potassium and sodium ions to increase hydrophilicity and are prepared using silicate materials. However, silicate materials retain water solubility even after high-temperature baking and undergo hydrolysis in humid environments, forming a gel. Repeated wetting and drying can lead to cracking, reducing the coating's lifespan. 2. Most existing inorganic hydrophilic coatings are suitable for high-surface-energy, smooth surfaces such as stainless steel and glass. This is due to the poor wetting properties caused by the high surface energy of hydrophilic coatings. 3. Because hydrophilic materials are highly hydrophilic and relatively thin, they offer poor protection to the substrate. When applied to galvanized steel, cold-rolled steel, and other metal surfaces, they are prone to rusting, peeling, and failure.

[0005] For example, Chinese invention patent application number 202210984728.7, entitled "Waterborne Long-Lasting Anti-Fog Self-Cleaning Coating and its Preparation Method," discloses a waterborne long-lasting anti-fog self-cleaning coating and its preparation method. The method includes the following steps: placing silicate in a reaction vessel, adding a silane coupling agent to react, then adding a hydrolysis stabilizer and stirring to obtain silane-modified silicate; placing a portion of aluminosilicate sol and undecenoic acid in a reaction vessel, stirring, and initiating polymerization through ultraviolet light irradiation to obtain aluminosilicate sol; then, placing the silane-modified silicate and aluminosilicate sol in a reaction vessel and stirring, adding potassium hydroxide dropwise, and stirring until the liquid changes from milky white to transparent to obtain the product; adding the product, deionized water, silicate curing agent, and wetting and leveling agent to a stirring vessel and stirring evenly to prepare a waterborne inorganic long-lasting anti-fog self-cleaning coating. This coating has a long service life and good hydrophilicity. However, silicates are water-soluble and will hydrolyze in humid environments. Furthermore, this coating is only suitable for smooth surfaces such as glass, and its coating power is poor on metal surfaces such as galvanized sheets. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a corrosion-resistant, hydrophilic, and easy-to-clean coating with good water resistance and salt spray resistance, in view of the above-mentioned technical status.

[0007] The second technical problem to be solved by the present invention is to provide a corrosion-resistant, hydrophilic and easy-to-clean coating with good coatability, in view of the above-mentioned technical status.

[0008] The third technical problem to be solved by the present invention is to provide a method for preparing a corrosion-resistant, hydrophilic, and easy-to-clean coating, in light of the aforementioned technical situation.

[0009] The technical solution adopted by this invention to solve the first and second technical problems mentioned above is: a corrosion-resistant, hydrophilic, and easy-to-clean coating, characterized in that:

[0010] The corrosion-resistant, hydrophilic, and easy-to-clean coating has the following composition by weight: 20-60 parts water, 30-50 parts potassium silicate, 1-8 parts potassium methylsilicate, 2-8 parts silane oligomer, 0.2-0.6 parts acetylacetonate diol polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex.

[0011] Alkyne glycol polyoxyethylene ether can form an effective water-resistant molecular film on the material surface. The hydroxyl groups on the molecule can form hydrogen bonds with the silanol groups, making the polyoxyethylene ether adhered to the surface more firmly. The hydroxyl groups can also react with the epoxy groups on the silane oligomers. Simultaneously, the polyoxyethylene ether significantly reduces the viscosity of the coating, increasing its leveling and wetting properties. Due to its unique molecular arrangement, the hydrophilic groups are horizontally aligned on the bubble film wall, and the alkyl groups are distributed further away, reducing the intermolecular attraction and making the bubble film wall relatively unstable, thus making it easier to break bubbles. Therefore, it can reduce the formation of bubbles in the coating during production and processing.

[0012] Potassium methylsilicate can react with CO2 to form a waterproof and breathable membrane, and also has a certain potassium-fixing effect, so that potassium ions can be evenly dispersed on the outer surface of the coating, increasing hydrophilicity. However, since both potassium methylsilicate and acetylenol polyoxyethylene ether have hydrophobic functional groups, the amount added must be controlled, otherwise the hydrophilicity of the material will be greatly reduced.

[0013] Silane oligomers contain epoxy groups, which can undergo cross-linking reactions with hydroxyl groups (silanol groups or hydroxyl groups on polyoxyethylene ethers) at temperatures above 200°C, thereby increasing the overall degree of cross-linking of the material. Boron trifluoride monoethylamine complexes are latent catalysts for epoxy groups, which can cure and cross-link epoxy groups with amino groups at high temperatures, reducing the problem of hydrolysis in the later stages of the material and increasing the lifespan of the material.

[0014] Because the silane oligomers are over-capped and the catalyst is a latent catalyst that can only undergo cross-linking reaction at temperatures above 100 degrees Celsius, the coating has strong overall stability and can be made into a single-component coating. It can maintain stability for a long time at room temperature and does not need to be prepared into a two-component catalyst. No further curing process is required before using the coating.

[0015] Preferably, the potassium silicate has a solid content of 35% and a modulus of 3.5.

[0016] Preferably, the silane oligomer is 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer.

[0017] Preferably, the solid content of the 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer is 30%, and the CAS number before hydrolysis polymerization is 2530-83-8.

[0018] Preferably, the degree of polymerization of the 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer is 2 to 3.

[0019] The technical solution adopted by the present invention to solve the third technical problem mentioned above is: a method for preparing a corrosion-resistant, hydrophilic, and easy-to-clean coating, characterized in that: at room temperature, the weight parts of the aforementioned corrosion-resistant, hydrophilic, and easy-to-clean coating are stirred and added, and then stirring is continued for 2 hours to obtain the corrosion-resistant, hydrophilic, and easy-to-clean coating.

[0020] Compared with existing technologies, the advantages of this invention are as follows: By adding potassium methylsilicate, silane oligomers, and boron trifluoride monoethylamine complexes, and adjusting the proportions, the water resistance and salt spray resistance of the hydrophilic coating are increased while maintaining good hydrophilicity; the addition of acetylenol polyoxyethylene ether increases the wettability of the hydrophilic coating on the substrate. This results in a coating with better adhesion and coating ability, thus allowing it to be applied to the surfaces of metal materials such as stainless steel plates, glass, galvanized plates, cold-rolled plates, and magnesium-aluminum alloys. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments.

[0022] The reagents and equipment used in the examples and comparative examples are as follows:

[0023] Potassium silicate, solid content 35%, modulus 2.8-4.0;

[0024] 3-(2,3-epoxypropoxy)propyltrimethoxysilane; solid content 30%; CAS: 2530-83-8; degree of polymerization 2-3;

[0025] One part of acetylenic diol polyoxyethylene ether, CAS: 9014-85-1.

[0026] Example 1

[0027] Under ambient temperature and at 1500 rpm in a high-speed disperser, the following components were added by weight: 40 parts water, 40 parts potassium silicate with a modulus of 3.5, 3 parts potassium methyl silicate, 5 parts 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer, 0.5 parts acetylacetonate polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex. After addition, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was then applied to the surface of a galvanized sheet and dried at 210℃.

[0028] Example 2

[0029] Under ambient temperature and at 1500 rpm in a high-speed disperser, the following components were added by weight: 20 parts water, 30 parts potassium silicate with a modulus of 3.5, 1 part potassium methyl silicate, 2 parts 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer, 0.2 parts acetylacetonate polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex. After addition, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was then applied to the surface of a galvanized sheet and dried at 210℃.

[0030] Example 3

[0031] Under ambient temperature and at 1500 rpm in a high-speed disperser, the following components were added by weight: 60 parts water, 50 parts potassium silicate with a modulus of 3.5, 8 parts potassium methylsilicate, 8 parts 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer, 0.6 parts acetylacetonate diol polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex. After addition, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was then applied to the surface of a galvanized sheet and dried at 210℃.

[0032] Example 4

[0033] Under ambient temperature and at 1500 rpm in a high-speed disperser, the following components were added by weight: 40 parts water, 40 parts potassium silicate with a modulus of 2.8, 3 parts potassium methyl silicate, 5 parts 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer, 0.5 parts acetylacetonate polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex. After addition, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was then applied to the surface of a galvanized sheet and dried at 210℃.

[0034] Example 5

[0035] Under ambient temperature and at 1500 rpm in a high-speed disperser, the following components were added by weight: 40 parts water, 40 parts potassium silicate with a modulus of 4.0, 3 parts potassium methyl silicate, 5 parts 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer, 0.5 parts acetylacetonate polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex. After addition, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was then applied to the surface of a galvanized sheet and dried at 210℃.

[0036] Comparative Example 1:

[0037] Under ambient temperature and at 1500 rpm in a high-speed disperser, the following components were added by weight: 40 parts water, 40 parts potassium silicate, 5 parts 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer, 0.5 parts acetylacetonate polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex. After addition, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was then applied to the surface of a galvanized sheet and dried at 210℃.

[0038] Comparative Example 2:

[0039] At room temperature and 1500 rpm in a high-speed disperser, 40 parts by weight of water, 40 parts by weight of potassium silicate, 3 parts by weight of potassium methylsilicate, 0.5 parts by weight of acetylacetonate diol polyoxyethylene ether, and 0.8 parts by weight of butanol were added. After the addition was complete, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was applied to the surface of a galvanized sheet and dried at 210℃.

[0040] Comparative Example 3:

[0041] Under ambient temperature and at 1500 rpm in a high-speed disperser, the following components were added by weight: 40 parts water, 40 parts potassium silicate, 10 parts potassium methyl silicate, 10 parts 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer, 0.5 parts acetylacetonate diol polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex. After addition, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was then applied to the surface of a galvanized sheet and dried at 210℃.

[0042] Comparative Example 4

[0043] Under ambient temperature and at 1500 rpm in a high-speed disperser, the following components were added by weight: 40 parts water, 40 parts potassium silicate with a modulus of 3.5, 3 parts potassium methylsilicate, 5 parts 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex. After addition, stirring was continued for 2 hours to obtain a corrosion-resistant, hydrophilic, and easy-to-clean coating. The prepared coating was then applied to the surface of a galvanized sheet and dried at 210℃.

[0044] The results of testing the coatings obtained in Examples 1-5 and Comparative Examples 1-4 are shown in Table 1:

[0045] The testing methods for coated galvanized steel sheets are as follows:

[0046] 1. Oil contact angle and water contact angle test: The test was conducted using a Shengwu 350H multi-functional contact angle tester; Test conditions: At room temperature of 30℃, 0.2uL of test liquid was dropped into the test sample and the test was conducted at the 1 / 4, 1 / 2 and 3 / 4 positions respectively, and the average value was taken.

[0047] 2. Water Resistance Test: At room temperature, the prepared samples were placed in different beakers, positioned at a 75° angle to the horizontal. Pure water was added to submerge the samples to half their length. The samples were left to stand and observed every 24 hours. Failure was defined as the appearance of large white spots exceeding 2 mm on the submerged portion; the failure time was recorded.

[0048] 3. Neutral salt spray: Tested according to GB10125-1997, observed every 24 hours. If corrosion (black and white rust) extends more than 2mm along the edge of the galvanized sheet, or if 2mm of white rust appears in the middle of the galvanized sheet, it is considered a failure.

[0049] The coatability of the coating is tested as follows:

[0050] The coating is applied using the dip-coating method. Different metal samples are immersed in the coating for 1 minute, and the samples are pulled out at a speed of 10 mm / s. When the samples are completely pulled out, the surface is observed for sagging, pinholes, and dripping. After the samples have been left to stand for 5 minutes, they are carefully observed. If the sample surface is smooth and without defects, it is considered excellent; if there are a few sagging marks (the marks are concentrated in the lower 1 / 4 of the sample surface) but no pinholes, it is considered good; if there are sagging marks (the marks are concentrated in the 1 / 2 of the sample surface), it is considered good.

[0051] Table 1

[0052]

[0053] As shown in Table 1, the water immersion resistance and salt spray resistance of Examples 1-5 are higher than those of Comparative Examples 1-2, while the water contact angle and wet contact angle of Examples 1-5 are lower than those of Comparative Examples 1-2. Therefore, the cleaning coating improves water resistance and salt spray resistance while maintaining good hydrophilicity and oleophilicity. Furthermore, it can be coated onto metal surfaces with excellent adhesion and coating ability. Comparative Example 3 shows that excessive addition of potassium methylsilicate and epoxy silane oligomers reduces the hydrophilicity and increases the oleophilicity of the material, making it less easy to clean. Examples 1 and Comparative Example 4 show that the absence of acetylenic glycol polyoxyethylene ether worsens the coating's coatability.

Claims

1. A corrosion resistant, hydrophilic, easy-to-clean coating, characterized in that: The corrosion-resistant, hydrophilic, and easy-to-clean coating has the following composition by weight: Water 20-60 parts, potassium silicate 30-50 parts, potassium methylsilicate 1-8 parts, silane oligomer 2-8 parts, acetylacetonate diol polyoxyethylene ether 0.2-0.6 parts, butanol 0.8 parts, boron trifluoride monoethylamine complex 0.5 parts; The silane oligomer is 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer.

2. The corrosion resistant, hydrophilic, easy-to-clean coating of claim 1, wherein: The corrosion-resistant, hydrophilic, and easy-to-clean coating has the following composition by weight: 30-45 parts water, 30-45 parts potassium silicate, 2-6 parts potassium methylsilicate, 2-6 parts silane oligomer, 0.2-0.6 parts acetylacetonate diol polyoxyethylene ether, 0.8 parts butanol, and 0.5 parts boron trifluoride monoethylamine complex.

3. The corrosion resistant, hydrophilic, easy-to-clean coating of claim 2, wherein: The potassium silicate has a solid content of 35% and a modulus of 2.8-4.

0.

4. The corrosion resistant, hydrophilic, easy-to-clean coating of claim 1, wherein: The solid content of the 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer is 30%; CAS: 2530-83-8.

5. The corrosion resistant, hydrophilic, easy-to-clean coating of claim 4, wherein: The degree of polymerization of the 3-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer is 2 to 3.

6. A process for the preparation of the corrosion resistant, hydrophilic, easy-to-clean coating according to any one of claims 1 to 5, characterized in that: At room temperature, the corrosion-resistant, hydrophilic, and easy-to-clean coating components of claim 1 are stirred and added, and then stirring is continued to obtain the corrosion-resistant, hydrophilic, and easy-to-clean coating.

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