CN116285604A

CN116285604A - Coating and method for forming anti-fog self-cleaning coating based on same

Info

Publication number: CN116285604A
Application number: CN202310049372.2A
Authority: CN
Inventors: 张友法; 邓伟林; 余新泉
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2023-02-01
Filing date: 2023-02-01
Publication date: 2023-06-23
Anticipated expiration: 2043-02-01

Abstract

The invention discloses a coating and a method for forming an anti-fog and self-cleaning coating based on the coating, wherein the coating comprises the following components in parts by weight: 0.5 to 2 parts of acrylic epoxy resin, 0.1 to 0.3 part of curing agent, 1 to 4 parts of tetraethyl orthosilicate, 0.5 to 1 part of acetic acid, 0.5 to 2 parts of metal oxide nanoparticle sol, 0.4 to 3 parts of anionic surfactant and 85 to 90 parts of water. Si-OH formed by hydrolysis of tetraethyl orthosilicate and OH, -COOH formed by hydrolysis of acrylic epoxy resin in the coating, and SiO ₂ 、ZrO ₂ 、Al ₂ O ₃ the-OH on the surface of the nano particles and the-Si-OH on the surface of the glass substrate are bonded through covalent bonds, so that the bonding force between the nano particles and each component in the coating is improved, and the strong adhesion between the coating and the glass substrate is realized, thereby formingThe coating of the (C) has a high-density and strong cross-linked structure and shows excellent wear resistance.

Description

Coating and method for forming anti-fog self-cleaning coating based on same

Technical Field

The invention relates to a coating for forming an anti-fog and self-cleaning coating and a method for forming a coating based on the coating.

Background

The glass has the characteristics of high transmittance, high strength, high wear resistance and the like, and can be widely used as a functional and decorative material. However, the glass surface is easy to generate the phenomenon of vapor condensation and fogging, and the phenomenon of fogging not only reduces the transparency of the glass material, but also influences the use of related products, and also brings potential safety hazards to the operation of equipment, so that the glass surface fogging phenomenon is solved, and the glass surface fogging device has great production practical value.

Hydrophilic groups (-OH, -COOH, -SO) on the surface of the super-hydrophilic coating ₃ H, etc.) has a strong adsorption effect on water molecules, so that droplets formed by condensing water vapor can be rapidly spread to form a water film, and the reflection and scattering of light in the droplets are reduced, thereby playing an anti-fog effect. However, the existing glass antifogging coating is low in hardness and poor in binding force with a glass substrate, and the conventional cleaning process is easy to cause friction damage of the coating, so that the antifogging coating is invalid.

Disclosure of Invention

The invention aims to: the invention aims to provide a coating and a method for forming an anti-fog and self-cleaning coating based on the coating, and the coating prepared by the method can solve the problems of low hardness, poor binding force with a glass substrate and failure of the anti-fog coating caused by friction damage in the cleaning process of the existing anti-fog coating.

The technical scheme is as follows: the coating disclosed by the invention comprises the following components in parts by weight: 0.5 to 2 parts of acrylic epoxy resin, 0.1 to 0.3 part of curing agent, 1 to 4 parts of tetraethyl orthosilicate, 0.5 to 1 part of acetic acid, 0.5 to 2 parts of metal oxide nanoparticle sol, 0.4 to 3 parts of anionic surfactant and 85 to 90 parts of water; wherein the pH value of the paint is 3-4. In an acid solution with the pH value of 3-4 regulated by acetic acid, tetraethyl orthosilicate is incompletely hydrolyzed to form a large amount of-Si-OH; the epoxy acrylic resin is hydrolyzed to form epoxy resin and acrylic monomer, and the epoxy group is opened under the catalysis of triethanolamine, so that a large amount of-COOH and-OH exist in the solution; introduced SiO ₂ 、ZrO ₂ And Al ₂ O ₃ The nano particles ensure high hardness of the coating and SiO in the sol ₂ 、ZrO ₂ And Al ₂ O ₃ The surface is rich in-OH, a large amount of-COOH and-OH existing in the solution are taken as reaction sites,esterification reaction and etherification reaction are carried out, and the components are bonded together through the mutual staggered reaction of the functional groups among the components to form a three-dimensional network structure, so that the bonding force among the components in the coating after the coating is formed is improved, and the wear resistance of the coating is further improved.

Wherein the molecular weight of the acrylic epoxy resin is 400-600. The selection of the low molecular weight acrylic epoxy resin mainly considers that the quantity of the epoxy resin and the acrylic monomer after the acrylic epoxy resin is hydrolyzed is increased, so that the content of-COOH and-OH in the solution is increased, and more reaction sites are provided for the esterification and etherification reaction between the components in the solution.

Wherein the curing agent is one or more of diethylenetriamine, ethylenediamine or triethanolamine.

The particle size of the nano particles in the metal oxide nano particle sol is 5-15 nm, and the metal oxide nano particle sol is a mixture of silica sol, aluminum sol and zirconium sol; wherein the silica sol, the zirconium sol and the aluminum sol are prepared according to SiO ₂ 、ZrO ₂ 、Al ₂ O ₃ Mass ratio 6:1:3, mixing.

Wherein the anionic surfactant is one or more of alpha-sodium alkenyl sulfonate, sodium cetyl sulfonate or sodium cetyl sulfate.

The method for forming the anti-fog self-cleaning coating based on the coating comprises the following steps:

(1) Activating the cleaned glass substrate: firstly, degreasing a glass substrate by using absolute ethyl alcohol, then, putting the glass substrate into a mixed solution of hydrogen peroxide and concentrated sulfuric acid, soaking for 10-30 seconds, taking out, washing with water, and drying for later use; after the glass substrate is soaked in the mixed solution of hydrogen peroxide and concentrated sulfuric acid, a large amount of-Si-OH is formed on the surface, and the glass substrate can react with a large amount of-COOH and-OH existing in the coating, and dehydration is carried out to carry out esterification reaction and etherification reaction, so that the binding force between the coating and the glass substrate is improved;

(2) Coating the coating on the surface of the glass substrate in the step (1) in a dip coating, spray coating, roller coating or knife coating mode, and forming an anti-fog and self-cleaning coating on the surface of the glass substrate after curing.

In the step (1), the mixing volume ratio of the hydrogen peroxide to the concentrated sulfuric acid is 3:7, preparing a base material; the mass concentration of the hydrogen peroxide is 30%; the mass concentration of the concentrated sulfuric acid is 98%.

Wherein, in the step (2), the curing condition is that the curing agent is heated for 25 to 30 minutes at 100 to 300 ℃ or is placed for 22 to 24 hours at normal temperature.

The beneficial effects are that: compared with the prior art, the invention has the following remarkable advantages: functional groups-Si-OH formed by incomplete hydrolysis of tetraethyl orthosilicate and-OH, -COOH formed by hydrolysis of acrylic epoxy resin in the coating, and SiO ₂ 、ZrO ₂ 、Al ₂ O ₃ the-OH on the surfaces of the nano particles and the-Si-OH on the surfaces of the activated glass substrates are covalently bonded, so that the bonding force between the nano particles and each component in the coating is improved, and the strong adhesion between the coating and the glass substrates is realized, so that the formed coating has a high-density and strong cross-linked structure and has excellent wear resistance; the Taber friction and wear experiment proves that the coating has good anti-fog performance after the CS-10F grinding wheel bearing 250g load rubs for 400 circles; meanwhile, as the nano particles are coated by the resin, the coating has a compact structure and a smooth surface, and simultaneously, oil stains and dust on the surface of the coating can be rapidly removed in a wetting environment, so that the self-cleaning performance is excellent.

Drawings

FIG. 1 is a view showing the Water Contact Angle (WCA), surface Atomic Force Microscope (AFM) roughness structure and antifogging effect of the coating of example 1; wherein, (a) the WCA coated with the anti-fog coating of example 1; (b) Light transmittance of the blank glass was compared with the coated glass samples of example 1 and example 5; (c) AFM roughness structure of the anti-fog coating; (d) Is an anti-fog effect graph of the anti-fog coating after 2 minutes in a hydrothermal humidifying environment at 80 ℃;

FIG. 2 is a graph of the self-cleaning effect of the oil stain on the coating of example 1;

FIG. 3 shows the Scanning Electron Microscope (SEM) surface structures of the coatings of example 1 (a) and example 2 (b);

FIG. 4 is a photograph of an anti-fog coating of example 1 (a) and example 2 (b) cross-hatched under a metallographic microscope after cross-hatch adhesion test according to ISO 2409;

FIG. 5 is a graph showing the anti-fog effect of a CS-10F grinding wheel subjected to a load of 250g in a Taber friction test after (a) 400 turns of coating friction in example 1, (b) 30 turns of coating friction in example 2, (c) 20 turns of coating friction in example 3, and (d) 20 turns of coating friction in example 4; the area in the broken line is a wearing part;

FIG. 6 shows the SEM microstructures of the coating surface of (a) example 5, (b) example 6, and (c) example 7;

FIG. 7 shows SEM microstructure of a CS-10F grinding wheel subjected to a load of 250g in a Taber friction test at (a) 400 cycles of coating friction of example 5, (b) 20 cycles of coating friction of example 6, and (c) 20 cycles of coating friction of example 7;

FIG. 8 is (a) the initial anti-fog properties of the coating of example 5; in the Taber friction experiment, a CS-10F grinding wheel bearing 250g load is subjected to anti-fog effect graph after (b) 400 circles of coating friction of the embodiment 5, (c) 20 circles of coating friction of the embodiment 6 and (d) 20 circles of coating friction of the embodiment 7; the area within the dashed line is the wearing point.

Detailed Description

The technical scheme of the invention is further described below with reference to the accompanying drawings.

Example 1

The invention relates to a method for forming an anti-fog and self-cleaning coating, which comprises the following steps:

(1) Adding 0.5 part of acrylic epoxy resin, 0.2 part of triethanolamine and 0.5 part of acetic acid into 85 parts of water, and uniformly stirring to obtain a mixed solution; adding 1 part of tetraethyl orthosilicate, 1 part of nanoparticle sol and 0.4 part of anionic surfactant alpha-alkenyl sodium sulfonate into the mixed solution, and fully and uniformly stirring to obtain a transparent super-hydrophilic anti-fog coating; wherein SiO is used as ₂ 、ZrO ₂ 、Al ₂ O ₃ Silica sol, zirconium sol and aluminum sol by mass based on SiO ₂ 、ZrO ₂ 、Al ₂ O ₃ Mass ratio 6:1:3, mixing;

(2) Firstly, degreasing a glass sample by using absolute ethyl alcohol, then washing the glass sample by using distilled water, and then placing the glass sample into a container with the volume ratio of 3:7 (30% of AR) and concentrated sulfuric acid (98% of AR), soaking for 20s, taking out, washing with distilled water, and drying for later use;

(3) The super-hydrophilic anti-fog coating in the step (1) is coated on the surface of the glass in the step (2) in a spraying mode, is dried for 10min at room temperature, is then put into an oven to be baked for 30min at 200 ℃, and forms an anti-fog self-cleaning coating on the surface of the glass after being cured.

The Taber abrasion test demonstrates that the coating of example 1 still has good anti-fog properties after 400 cycles of abrasion with a CS-10F wheel bearing a load of 250g (fig. 5 a).

Example 2

The method of forming the anti-fog, self-cleaning coating of example 2 is substantially the same as example 1, with the only difference that example 2 does not add acrylic epoxy resin and triethanolamine during the preparation of the anti-fog coating, and the resulting coating has poor abrasion resistance. The reason is that the sites of crosslinking with the nanoparticles and the glass substrate in the coating are reduced, so that the internal crosslinking strength of the coating and the binding force with the substrate are reduced, the wear resistance of the coating is reduced, and the Taber friction and wear experiment proves that the coating has lost the anti-fog performance after 30 circles of friction of a CS-10F grinding wheel bearing a load of 250g (figure 5 b).

Example 3

The method of forming the anti-fog, self-cleaning coating of example 3 is substantially the same as example 1, compared to example 1, except that example 3 does not add an aluminum sol during the preparation of the anti-fog coating, resulting in a significant reduction in the hardness of the coating, resulting in a reduction in the wear resistance of the coating, and Taber abrasion test shows that the coating has lost anti-fog properties after 20 cycles of abrasion with a CS-10F grinding wheel bearing a load of 250g (fig. 5 c).

Example 4

The method of forming the anti-fog, self-cleaning coating of example 4 is essentially the same as example 1, compared to example 1, the only difference being that example 4 does not add zirconium sol during the preparation of the anti-fog coating, resulting in a significant reduction in the hardness of the coating, resulting in a reduction in the wear resistance of the coating, and the Taber abrasion test proves that the coating has lost anti-fog properties after 20 cycles of abrasion with a CS-10F grinding wheel bearing a load of 250g (fig. 5 d).

Example 5

Compared with example 1, the formation method of the anti-fog and self-cleaning coating of example 5 is basically the same as that of example 1, the only difference is that the tetraethyl orthosilicate is added to 2 parts in the preparation process of the anti-fog coating of example 5, so that the coating has a compact cross-linked structure, a smooth surface and excellent wear resistance and self-cleaning performance.

Example 6

Compared with example 1, the formation method of the anti-fog and self-cleaning coating of example 6 is basically the same as that of example 1, and the only difference is that in the preparation process of the anti-fog coating, tetraethyl orthosilicate is added into the coating in an amount of 0 part, so that a three-dimensional network structure formed after hydrolysis of the tetraethyl orthosilicate is not formed in the coating, the cross-linking sites among the components of the coating are reduced, the cross-linking strength is reduced, and the wear resistance of the coating is reduced.

Example 7

Compared with example 1, the anti-fog and self-cleaning coating of example 7 is basically the same as example 1, and the only difference is that in the preparation process of the anti-fog coating, 5 parts of tetraethyl orthosilicate is added in example 7, so that excessive crosslinking sites are generated after the tetraethyl orthosilicate in the coating is hydrolyzed, a large number of agglomerated nanoparticle particles appear on the surface of the coating, the roughness of the coating is larger, and the light transmittance and the wear resistance are reduced.

The coating samples prepared in examples 1-4 all show super-hydrophilic performance, the contact angle is smaller than 5 degrees, wherein the water contact angle of the coating in example 1 is 3.7 degrees (shown in figure 1 a), as shown in figure 1b, the light transmittance of the coating sample in example 1 is not obviously different from that of a sample of blank glass, the light transmittance of the coating sample reaches 91.5%, the AFM three-dimensional morphology of the surface of the coating sample is shown in figure 1c, the surface of the coating is smooth, the mean square error roughness is lower (9.06 nm), and the detection result of the antifogging performance shows that the coating has good antifogging performance. The oil stain resistance test results (fig. 2) and the sand dust resistance test results show that the coating sample of example 1 shows excellent self-cleaning performance. Fig. 3a and 3b are SEM surface microtopography of the coatings of example 1 and example 2, respectively, and by comparison, it is clear that the coating structure of example 2 without the addition of acrylic epoxy and triethanolamine is loose (fig. 3 b), and the particles are not tightly bonded. Meanwhile, the results of the cross-cut adhesion test in fig. 4 show that the coating in the example 2 is fragile due to the fact that the acrylic epoxy resin and the triethanolamine are not added, and the coating is not peeled off from the substrate in the cross-cut adhesion test, but a large number of brittle cracks appear on the surface of the coating (fig. 4 b), in contrast, the coating in the example 1 can still keep the structural integrity of the coating after the cross-cut adhesion test, and strong adhesion of the substrate is shown. The adhesion test results showed that the coating of example 2 had a bonding force to the substrate of 2.3MPa (see table 1). Fig. 5 shows the anti-fog effect of the coatings of examples 1-4 after abrasion by a CS-10F wheel bearing a 250g load in a Taber abrasion test, and the results show that the coating of example 1 still has good anti-fog properties after 400 cycles of abrasion (fig. 5 a), and the coating of example 2 has lost anti-fog properties after 30 cycles of abrasion (fig. 5 b). By comparing examples 1, 3 and 4, the coating material is added with alumina and zirconia nano particles, so that the hardness of the coating layer is increased (table 1), and the wear resistance of the coating layer is further improved. Meanwhile, the absence of the resin on the surface of the nano-particles causes the coating of the example 2 to have surface roughness, the underwater oil contact angle (see table 1) is obviously smaller than that of the coating samples of the examples 1, 3 and 4, and the coating has no self-cleaning performance.

As shown in fig. 1b, the coating of example 5 has no significant difference in light transmittance from the sample of the blank glass, and the coated sample has a higher light transmittance (91.3%). The SEM microstructure of the coating surface of example 5 shows that the coating surface of example 5 still has a smoother structure (fig. 6 a), and that example 6 without the addition of tetraethyl orthosilicate results in reduced cross-linking sites between the components of the coating during formation, and the coating structure becomes porous (fig. 6 b). Example 7 the coating was added with an excess of tetraethyl orthosilicate, and during the formation of the coating, a large number of Si-OH adsorption sites resulted in agglomeration of the nanoparticles, and the surface of the coating became more rough (fig. 6 c). FIG. 7 is a SEM microstructure of the coating of example 5 after 400 cycles of abrasion with a CS-10F wheel under a 250g load in a Taber abrasion test, which shows that the coating of example 5 still has good integrity after 400 cycles of abrasion (FIG. 7 a). The coating of example 5 still had good anti-fog properties after 400 cycles of rubbing (fig. 8 b) compared to the initial anti-fog properties (fig. 8 a). Example 6 the cross-linking strength between the components in the coating was reduced, resulting in the coating having been abraded through after 20 cycles of rubbing, exposing the glass substrate, and the anti-fog properties had been lost (fig. 8 c); example 7 the coating was added with an excess of tetraethyl orthosilicate, agglomeration of the nanoparticles, resulting in a significant increase in the roughness of the coating (table 1), the coating was worn through after 20 friction cycles, losing anti-fog properties (fig. 8 d).

Meanwhile, the coating layers of examples 6 and 7 have obviously smaller underwater oil contact angles (table 1) than the coating sample of example 5 due to the increase of the roughness of the coating layers, and the coating layers of examples 6 and 7 have no self-cleaning performance.

(1) Substrate bonding force: and detecting the adhesive force between the coating and the substrate by using a BGD 500 digital display pull-off adhesive force tester according to the standard test method for measuring the coating peel strength by the portable adhesive tester. (2) antifogging property: the surface of the coating was placed on hot water at 80℃so as to have a distance of 50mm from the hot water surface, and the presence or absence of an antifogging effect of the sample was visually confirmed within 120 seconds. (3) self-cleaning performance of oil stains: the coated samples were tilted 30 °, and 100 μl of dyed soybean oil was titrated at the top of the samples under 95% humidity. And confirming the oil-free self-cleaning effect according to whether the light transmittance of the sample is greater than 90% within 1 h. (4) self-cleaning property of sand dust: the coating sample is inclined by 30 degrees, 100mg of sand dust with the particle size of 20 mu m is placed on the surface of the sample in a 95% humidity environment, and whether the self-cleaning effect of the sand dust exists or not is confirmed according to whether the light transmittance of the sample is greater than 90% within 1 h.

The results of the properties of the coating samples of examples 1-7 are shown in Table 1.

TABLE 1

Claims

1. The coating is characterized by comprising the following components in parts by weight: 0.5 to 2 parts of acrylic epoxy resin, 0.1 to 0.3 part of curing agent, 1 to 4 parts of tetraethyl orthosilicate, 0.5 to 1 part of acetic acid, 0.5 to 2 parts of metal oxide nanoparticle sol, 0.4 to 3 parts of anionic surfactant and 85 to 90 parts of water.

2. The coating of claim 1, wherein: the pH value of the paint is 3-4.

3. The coating of claim 1, wherein: the molecular weight of the acrylic epoxy resin is 400-600.

4. The coating of claim 1, wherein: the curing agent is one or more of diethylenetriamine, ethylenediamine or triethanolamine.

5. The coating of claim 1, wherein: the particle size of the nano particles in the metal oxide nano particle sol is 5-15 nm, and the metal oxide nano particle sol is a mixture of silica sol, aluminum sol and zirconium sol; wherein the silica sol, the zirconium sol and the aluminum sol are prepared according to SiO ₂ 、ZrO ₂ 、Al ₂ O ₃ Mass ratio 6:1:3, mixing.

6. The coating of claim 1, wherein: the anionic surfactant is one or more of alpha-sodium alkenyl sulfonate, sodium hexadecyl sulfonate or sodium hexadecyl sulfate.

7. A method of forming an anti-fog, self-cleaning coating based on the coating of claim 1, comprising the steps of:

(1) Activating the cleaned glass substrate: firstly, degreasing a glass substrate by using absolute ethyl alcohol, then, putting the glass substrate into a mixed solution of hydrogen peroxide and concentrated sulfuric acid, soaking for 10-30 seconds, taking out, washing with water, and drying for later use;

8. The method of forming an anti-fog, self-cleaning coating of claim 7, wherein: in the step (1), the mixing volume ratio of the hydrogen peroxide to the concentrated sulfuric acid is 3:7, preparing a base material; the mass concentration of the hydrogen peroxide is 30%; the mass concentration of the concentrated sulfuric acid is 98%.

9. The method of forming an anti-fog, self-cleaning coating of claim 7, wherein: in the step (2), the curing condition is that the curing agent is heated for 25 to 30 minutes at the temperature of 100 to 300 ℃ or is placed for 22 to 24 hours at the normal temperature.