Waterproof coating capable of being applied to mirrors and mirror cabinets and preparation method of waterproof coating

Abstract

The invention relates to the technical field of coating compositions, in particular to a waterproof coating capable of being applied to mirrors and mirror cabinets and a preparation method of the waterproof coating. The modified polydimethylsiloxane is obtained by reacting the bis (aminopropyl) polydimethylsiloxane with the modifier and then reducing, and the prepared coating not only is waterproof, but also is better in durability. Compared with the prior art, the prepared waterproof coating has good adhesive force and can achieve self-repairing after being damaged, so that a longer waterproof effect can be maintained, the waterproof coating is suitable for being applied to various base materials such as a mirror or a mirror cabinet, water on a mirror surface can slide down, and the effect of being not stained with water is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of coating compositions, and in particular to a waterproof coating applicable to mirrors and mirror cabinets and a preparation method thereof. Background Art

[0002] Waterproof coatings are special materials that can be applied to various surfaces to prevent water from penetrating. Such coatings are often used on buildings, textiles, electronic devices, outdoor gear, and other items that need waterproof protection. Waterproof coatings can be achieved in different ways, including physical barriers, chemical adsorption, surface modification, etc. They include hydrophobic coatings, which repel water by reducing the surface energy and usually contain silicon, fluorine, or nanotechnology-based materials. Nano coatings, nanotechnology can be used to create ultra-thin waterproof layers. These coatings can penetrate into the microstructure of the material to form a nearly invisible barrier. Polymer coatings such as polyurethane, epoxy resin, and acrylic can all be used as waterproof coatings. They can form a protective film to prevent water from penetrating. Ceramic coatings can provide excellent waterproofing properties while also enhancing the material's wear resistance and high temperature resistance. In addition to waterproofing, oleophobic coatings can also repel oil and other liquids and are often used in kitchen utensils and industrial equipment. Some advanced waterproof coatings are able to self-heal after damage. This technology usually involves microencapsulation technology, which contains healing agents that can be released when the coating is damaged. Thermoplastic coatings soften when heated and harden again after cooling, which can form a seamless waterproof barrier during construction. Aerogel is a lightweight, porous material that can be made into a coating that provides good thermal insulation and waterproofing properties. Waterproof coatings are used in a wide range of applications, from everyday items such as umbrellas and shoes to industrial uses such as maintenance of bridges and ships. When choosing a suitable waterproof coating, you need to consider its durability, environmental adaptability, cost, and suitability for the needs of a specific application.

[0003] The bathroom is a humid environment, and the mirrors and mirror cabinets placed in it are often damaged by water vapor. The mirror surface will fog up due to temperature difference and humidity, and the metal parts will rust. The mirror cabinets will also be corroded by the water, causing the materials to peel off, rot, or become moldy. Waterproofing the mirrors and mirror cabinets can effectively avoid these phenomena.

[0004] CN112521851A belongs to the field of coating technology, and specifically relates to a super-hydrophobic, super-wear-resistant anti-fog coating composition and its application. The coating composition is prepared by the following raw materials in parts by weight: 100 parts of resin-based polymerized monomers, 1-3 parts of modified glass fiber whiskers, 0.1-1 parts of photoinitiators, 0.1-0.3 parts of leveling agents, and 0.3-0.5 parts of defoamers; the resin matrix contains 60-80 parts of silicon acrylate oligomers and 20-40 parts of silicon-containing acrylate monomers. The polymerized monomers in the coating of the present invention are a mixture of silicon-containing acrylate oligomers and silicon-containing acrylate monomers, and have excellent water resistance, light resistance and hydrophobicity; modified glass fiber whiskers are added, and the modified glass fiber whiskers can be evenly dispersed in the coating system to play a long-term wear-resistant role. The prepared coating has higher wear resistance, scratch resistance and hydrophobicity, and plays an excellent anti-fog effect; the coating of the invention is applied to the surface of glasses, automobile glass, bathroom mirrors, goggles, and swimming goggles.

[0005] CN111393942B provides a kind of super hydrophobic coating agent, transparent super hydrophobic coating and its preparation method and application, and the super hydrophobic coating agent includes polymer microspheres, fluoropolymers and polymer crosslinking agents dispersed in solvent.Inorganic filler is not needed in the super hydrophobic coating agent, stable transparent super hydrophobic coating can be formed on a variety of substrates, and its adhesion with substrate is good, and contact angle is more than 150 °, and rolling angle is less than 10 °, and visible light transmittance reaches 83~95%.When the super hydrophobic coating agent is used to prepare transparent super hydrophobic coating, processing method is simple, and universality is strong, and the surface of building curtain wall, automobile windshield, optical lens and solar panel etc. can be widely used in, and the effect of waterproof, anti-fouling and self-cleaning can be played.

[0006] The existing technology uses low surface energy materials to achieve waterproof effect, but in actual application, low surface energy materials are easily decomposed by the stimulation of temperature, light and strong oxidants, and the micro-nano rough structure is also easily damaged by physical effects such as mechanical friction or wear, thereby affecting the adhesion and wettability of the coating, resulting in a decrease or loss of waterproof performance, limiting its application. Therefore, the development of a more durable waterproof coating has become the key. Summary of the invention

[0007] In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is to provide a waterproof coating applicable to mirrors and mirror cabinets and a preparation method thereof.

[0008] The decline in waterproof effect is often due to the following reasons: first, the adhesion between the coating surface and the substrate is poor, which makes the coating easy to fall off; second, the low surface energy substances and rough structures on the coating surface are easy to be destroyed. Therefore, in order to solve the above problems, chemical bonds can be introduced to improve the adhesion between the coating surface and the substrate or elastic substances can be introduced on the coating surface to make the low surface energy substances and rough structures deform during friction or wear to avoid being destroyed. In addition, the polymer itself is used to form a micro-nano rough structure to avoid the use of inorganic nanomaterials. During friction or wear, the plastic deformation of the micro-nano rough structure itself allows its morphology to be maintained. However, these measures cannot avoid the decline in waterproofness after the hydrophobic surface is destroyed.

[0009] Therefore, the present invention provides a waterproof coating, which has good adhesion and can achieve self-repair after being damaged, so as to maintain a longer waterproof effect, and obtains a modified polydimethylsiloxane having a borane six-membered ring by Schiff base reaction between bisaminopropyl polydimethylsiloxane and a modifier and then reducing the borane six-membered ring as a reversible dynamic covalent bond, thereby making the coating self-repairing, and polydimethylsiloxane as a polymer can form a micro-nano rough structure on the surface of the substrate, and its adhesion can also improve the wear resistance of the coating, so the prepared coating is not only waterproof, but also has better durability. When there is an amino group or a hydrophobic alkyl chain in the modifier, since the amino groups can form hydrogen bonds with each other, the coating can have dynamic covalent bonds and non-covalent bonds at the same time, and the hydrophobic alkyl chain can give the coating better waterproofness.

[0010] To achieve the above object, the present invention provides a method for preparing a waterproof coating that can be applied to mirrors and mirror cabinets, comprising the following steps:

[0011] S1, adding bisaminopropyl polydimethylsiloxane and a modifier into a solvent, causing a Schiff base reaction under acid catalysis, and then reducing and post-treating to obtain modified polydimethylsiloxane;

[0012] S2: Modified polydimethylsiloxane and hydrophobic nano-silica are mixed and dispersed, and then sprayed on the surface of a clean mirror or mirror cabinet, and a waterproof coating is obtained after drying.

[0013] Furthermore, the method for preparing the waterproof coating applicable to mirrors and mirror cabinets comprises the following steps:

[0014] S1, adding bisaminopropyl polydimethylsiloxane and a modifier to ethanol with a volume of 5 to 10 times that of bisaminopropyl polydimethylsiloxane, adding acetic acid and heating and stirring, cooling to room temperature after the reaction, continuing to cool and then adding sodium borohydride, stirring at room temperature and concentrating to obtain a residue, adding the residue to 5 to 15 times the volume of dichloromethane, then adding sodium bicarbonate solution, water, and brine to wash and extract, and then drying and drying to obtain modified polydimethylsiloxane;

[0015] S2 adds modified polydimethylsiloxane and hydrophobic nano-silica into ethanol, sprays them on the surface of a clean mirror or mirror cabinet by ultrasonic dispersion, and obtains a waterproof coating after drying.

[0016] Furthermore, the molar ratio of the bisaminopropyl polydimethylsiloxane to the modifier, acetic acid and sodium borohydride is 1:4-8:0.1-0.2:6-8.

[0017] Furthermore, the temperature range of the heating is 70-80°C.

[0018] Furthermore, the heating and stirring time is 4 to 12 hours.

[0019] Furthermore, the stirring time at room temperature is 12 to 24 hours.

[0020] Furthermore, the cooling temperature range is 0 to 5°C.

[0021] Furthermore, the mass ratio of the modified polydimethylsiloxane to the hydrophobic nano-silica and ethanol is 1:0.5-2:500-800.

[0022] Furthermore, the ultrasonic dispersion time is 4 to 6 hours.

[0023] Preferably, the modifier is one of (4-amino-3-formylphenyl)boric acid, 3-formylphenylboric acid, and 4-nonanoylphenylboric acid.

[0024] The present invention also provides a waterproof coating which can be applied to mirrors and mirror cabinets and is prepared by the above method.

[0025] Beneficial effects of the present invention:

[0026] 1. Compared with the prior art, the present invention obtains a modified polydimethylsiloxane having a hexacyclic borane by Schiff base reaction between bisaminopropyl polydimethylsiloxane and a modifier and then reducing the same. The hexacyclic borane acts as a reversible dynamic covalent bond, thus making the coating self-healing. Polydimethylsiloxane, as a polymer, can form a micro-nano rough structure on the surface of the substrate, and its adhesion can also improve the wear resistance of the coating. Therefore, the prepared coating is not only waterproof, but also has better durability.

[0027] 2. The present invention provides a waterproof coating that has good adhesion and can also achieve self-repair after being damaged, thereby maintaining a longer waterproof effect. DETAILED DESCRIPTION

[0028] (4-Amino-3-formylphenyl)boronic acid, CAS: 1416252-20-4.

[0029] 4-Nonanoylphenylboronic acid, CAS: 2377611-17-9.

[0030] Bisaminopropyl polydimethylsiloxane, model: CM-226, viscosity: 5000~10000mPa·s, Guangzhou Tingyang Chemical Co., Ltd.

[0031] Polydimethylsiloxane, model: PMX-200, Dow Corning.

[0032] Hydrophobic nano-silica, model: MGS-1, particle size: 15-25 nm, Zhengzhou Dongshen Petrochemical Technology Co., Ltd.

[0033] Example 1

[0034] A method for preparing a waterproof coating applicable to mirrors and mirror cabinets comprises the following steps, measured in parts by weight:

[0035] S1, add 5 parts of bisaminopropyl polydimethylsiloxane and 0.8 parts of (4-amino-3-formylphenyl)boric acid to ethanol with a volume of 5 times that of bisaminopropyl polydimethylsiloxane, add 0.006 parts of acetic acid, heat to 75°C and stir for 8 hours, cool to room temperature after the reaction, continue to cool to 0°C and then add 0.25 parts of sodium borohydride, stir at room temperature for 18 hours and then concentrate to obtain a residue, add the residue to 10 times the volume of dichloromethane, add sodium bicarbonate solution, water and brine to wash and extract, dry, and dry to obtain modified polydimethylsiloxane;

[0036] S2: Add 1 part of modified polydimethylsiloxane and 1 part of hydrophobic nano-silica to 600 parts of ethanol, disperse them ultrasonically for 6 hours, spray them on the surface of a clean mirror or mirror cabinet, and dry them to obtain a waterproof coating.

[0037] Example 2

[0038] A method for preparing a waterproof coating applicable to mirrors and mirror cabinets comprises the following steps, measured in parts by weight:

[0039] S1, add 5 parts of bisaminopropyl polydimethylsiloxane and 0.75 parts of 3-formylphenylboronic acid to 5 times the volume of ethanol of bisaminopropyl polydimethylsiloxane, add 0.006 parts of acetic acid, heat to 75°C and stir for 8 hours, cool to room temperature after the reaction, continue to cool to 0°C and then add 0.25 parts of sodium borohydride, stir at room temperature for 18 hours and then concentrate to obtain a residue, add the residue to 10 times the volume of dichloromethane, then add sodium bicarbonate solution, water and brine to wash and extract, dry, and dry to obtain modified polydimethylsiloxane;

[0040] S2: Add 1 part of modified polydimethylsiloxane and 1 part of hydrophobic nano-silica to 600 parts of ethanol, disperse them ultrasonically for 6 hours, spray them on the surface of a clean mirror or mirror cabinet, and dry them to obtain a waterproof coating.

[0041] Example 3

[0042] A method for preparing a waterproof coating applicable to mirrors and mirror cabinets comprises the following steps, measured in parts by weight:

[0043] S1, adding 5 parts of bisaminopropyl polydimethylsiloxane and 1.31 parts of 4-nonanoylphenylboric acid to ethanol with a volume of 5 times that of bisaminopropyl polydimethylsiloxane, adding 0.006 parts of acetic acid, heating to 75°C and stirring for 8 hours, cooling to room temperature after the reaction, continuing to cool to 0°C and adding 0.25 parts of sodium borohydride, stirring at room temperature for 18 hours and concentrating to obtain a residue, adding the residue to 10 times the volume of dichloromethane, then adding sodium bicarbonate solution, water, and brine to wash and extract, and then drying and drying to obtain modified polydimethylsiloxane;

[0044] S2: Add 1 part of modified polydimethylsiloxane and 1 part of hydrophobic nano-silica to 600 parts of ethanol, disperse them ultrasonically for 6 hours, spray them on the surface of a clean mirror or mirror cabinet, and dry them to obtain a waterproof coating.

[0045] Example 4

[0046] It is basically the same as Example 1, the only difference being that the hydrophobic nano-silica is 0.5 parts.

[0047] Example 5

[0048] It is basically the same as Example 1, the only difference being that the hydrophobic nano-silica is 1.5 parts.

[0049] Comparative Example 1

[0050] A method for preparing a waterproof coating applicable to mirrors and mirror cabinets comprises the following steps, measured in parts by weight:

[0051] Add 1 part of polydimethylsiloxane and 1 part of hydrophobic nano-silica to 600 parts of ethanol, disperse them ultrasonically for 6 hours, and spray them on the surface of a clean mirror or mirror cabinet. Dry them to obtain a waterproof coating.

[0052] Comparative Example 2

[0053] A method for preparing a waterproof coating applicable to mirrors and mirror cabinets comprises the following steps, measured in parts by weight:

[0054] Add 2 parts of hydrophobic nano-silica to 600 parts of ethanol, disperse it ultrasonically for 6 hours, and spray it on the surface of a clean mirror or mirror cabinet. Dry it to obtain a waterproof coating.

[0055] Test Example 1

[0056] The coatings prepared in the examples and control examples were tested for water contact angle and adhesion, and the coating adhesion was tested with reference to the method in GB / T9286-2021 "Paint and Varnish Cross-cut Test". A grid was drawn on the surface of the coating using a grid knife, and the coating adhesion grade (0 to 5, 0 is the best) was determined by comparing it with the standard chart. The water contact angle was tested using a contact angle meter, and the specific results are shown in Table 1.

[0057] Table 1 Hydrophobicity and adhesion test of waterproof coating

[0058] Experimental protocol Water contact angle / ° Adhesion / Grade Example 1 150.1 0 Example 2 148.6 0 Example 3 155.2 0 Example 4 130.2 0 Example 5 149.8 0 Comparative Example 1 148.8 0 Comparative Example 2 151.2 3

[0059] As can be seen from Table 1, the coating prepared by the present invention has a good waterproof effect, a high water contact angle, and the coating liquid shows good adhesion. This is because polydimethylsiloxane can form a micro-nano rough structure on the surface of the substrate as a polymer, and its adhesion to the substrate can also improve the adhesion of the coating, and the adhesion of the coating is significantly worse than that of the reference example 2 and the reference example 1 because polydimethylsiloxane is not added. Compared with Example 4, the amount of hydrophobic silica in Example 1 is more, so the water contact angle in Example 1 is larger, but hydrophobic silica is not colorless and transparent in the solvent, so when the amount of addition increases, although the hydrophobicity can be improved, it will also affect the color of the coating, thereby affecting the coating effect, so the amount used in Example 1 is relatively the best. Since the modifier in Example 3 contains a hydrophobic alkyl chain, and the hydrophobic alkyl chain can give the coating better waterproofness, the water contact angle is the largest.

[0060] Test Example 2

[0061] The coatings prepared in the examples and control examples were subjected to a self-healing test. After the coatings were scratched by cutting with a knife, they were placed at room temperature for 24 hours to measure the water contact angles before and after the scratches. The coatings were also subjected to O2 plasma etching for 2 minutes and then repaired at room temperature. The water contact angles of the coating surfaces before and after the treatment were measured. The specific test results are shown in Table 2.

[0062] Table 2 Self-healing performance test of waterproof coating

[0063]

[0064] It can be seen from Table 2 that the coating prepared in the embodiment has good self-healing properties. This is because the coating in the embodiment is subjected to Schiff base reaction between bisaminopropyl polydimethylsiloxane and the modifier and then reduced to obtain a modified polydimethylsiloxane having a borane oxygen six-membered ring. The borane oxygen six-membered ring is a reversible dynamic covalent bond, so that the coating has self-healing properties. When the coating surface is damaged, the dynamic covalent bonds are rebonded to achieve self-repair of the coating surface. The modifier in Example 1 has amino groups. Since the amino groups can form hydrogen bonds with each other, the coating can have dynamic covalent bonds and non-covalent bonds at the same time. Therefore, the self-healing effect after damage is better, and the water contact angle decreases less. The modifier in Example 3 contains a hydrophobic alkyl chain, and the hydrophobic alkyl chain can give the coating better water resistance, so the water contact angle is the largest. The control example has poor self-healing performance due to the lack of dynamic reversible bonds. In control example 1, since polydimethylsiloxane has fluidity, it can achieve partial repair through molecular chain movement when scratched. However, when faced with etching, both have basically lost their waterproof effect.

[0065] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for preparing a waterproof coating applicable to mirrors and mirror cabinets, characterized in that: The steps include: S1, adding bisaminopropyl polydimethylsiloxane and a modifier into a solvent, causing a Schiff base reaction under acid catalysis, and then reducing and post-treating to obtain modified polydimethylsiloxane; S2: Modified polydimethylsiloxane and hydrophobic nano-silica are mixed and dispersed, and then sprayed on the surface of a clean mirror or mirror cabinet, and a waterproof coating is obtained after drying.

2. The method for preparing a waterproof coating applicable to mirrors and mirror cabinets according to claim 1, characterized in that: The steps include: S1, adding bisaminopropyl polydimethylsiloxane and a modifier to ethanol with a volume of 5 to 10 times that of bisaminopropyl polydimethylsiloxane, adding acetic acid and heating and stirring, cooling to room temperature after the reaction, continuing to cool and then adding sodium borohydride, stirring at room temperature and concentrating to obtain a residue, adding the residue to 5 to 15 times the volume of dichloromethane, then adding sodium bicarbonate solution, water, and brine to wash and extract, and then drying and drying to obtain modified polydimethylsiloxane; S2 adds modified polydimethylsiloxane and hydrophobic nano-silica into ethanol, sprays them on the surface of a clean mirror or mirror cabinet by ultrasonic dispersion, and obtains a waterproof coating after drying.

3. The method for preparing a waterproof coating applicable to mirrors and mirror cabinets according to claim 1, characterized in that: The molar ratio of the bisaminopropyl polydimethylsiloxane to the modifier, acetic acid and sodium borohydride is 1:4-8:0.1-0.2:6-8.

4. The method for preparing a waterproof coating applicable to mirrors and mirror cabinets according to claim 1, characterized in that: The temperature range of the heating is 70-80°C.

5. The method for preparing a waterproof coating applicable to mirrors and mirror cabinets according to claim 1, characterized in that: The heating and stirring time is 4 to 12 hours.

6. The method for preparing a waterproof coating applicable to mirrors and mirror cabinets according to claim 1, characterized in that: The stirring time at room temperature is 12 to 24 hours.

7. The method for preparing a waterproof coating applicable to mirrors and mirror cabinets according to claim 1, characterized in that: The temperature range of the cooling is 0-5°C.

8. The method for preparing a waterproof coating applicable to mirrors and mirror cabinets according to claim 1, characterized in that: The mass ratio of the modified polydimethylsiloxane to the hydrophobic nano-silicon dioxide and ethanol is 1:0.5-2:500-800.

9. The method for preparing a waterproof coating applicable to mirrors and mirror cabinets according to claim 1, characterized in that: The ultrasonic dispersion time is 4 to 6 hours.

10. A waterproof coating applicable to mirrors and mirror cabinets, characterized in that: Prepared by the method according to any one of claims 1 to 9.

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