CN113444434A

CN113444434A - Preparation method and application of antifouling photocatalytic coating

Info

Publication number: CN113444434A
Application number: CN202110920859.4A
Authority: CN
Inventors: 田雪林; 吴成蛟; 王宏鑫
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2021-08-11
Filing date: 2021-08-11
Publication date: 2021-09-28
Anticipated expiration: 2041-08-11
Also published as: CN113444434B

Abstract

The invention belongs to the technical field of antifouling paints, and particularly relates to a preparation method and application of an antifouling photocatalytic paint. The invention adopts triethanolamine to carry out amino (-NH) on the nano catalyst₂) Pre-modifying, grafting isocyanate by low surface energy molecules, and reacting with a polyhydroxy reaction substrate to prepare the novel antifouling photocatalytic coating/coat. The prepared coating has antifouling performance and catalytic property, can effectively degrade organic residues, and improves antifouling efficiency; the product has certain transparency, and can be applied to the field of low transparency; the adhesive force is high, and the paint can be coated on the surfaces of various materials to enhance the antifouling efficiency; no fluorine substance and environmental protection; the preparation condition is mild, and high-temperature calcination is not needed; the block material can be prepared by various methods such as spin coating, drawing coating, brushing coating, dip coating and the like, and can be prepared by various methods such as casting, extrusion, hot pressing and the like.

Description

Preparation method and application of antifouling photocatalytic coating

Technical Field

The invention belongs to the technical field of antifouling paints, and particularly relates to a preparation method and application of an antifouling photocatalytic paint.

Background

In recent years, products such as materials and equipment are developed to be highly precise and highly precise, and in order to ensure the cleanness of the surface of the products, the field of antifouling paints is also developed to be highly durable, transparent, self-cleaning and multifunctional so as to resist the adhesion or contamination of aqueous and oily liquids, such as durable antifogging coatings, frost-proof coatings, anti-icing coatings, anti-oil coatings, anti-bioadhesion coatings, self-cleaning coatings and metal corrosion coatings. At present, antifouling paint is widely used in bathroom accessories, building protection, the field of petroleum/liquid transportation pipelines, electronic touch screens, ocean engineering, metal industry, optical lenses, microfluidics, antibiosis, antivirus, biological detection and other fields.

Currently, antifouling materials are mainly classified into three types, roughened ultraphobic surfaces, lubricated surfaces, and catalytic materials. Wherein, the super-hydrophobic surface can be super-hydrophobic or super-oleophobic (the static contact angle is more than 150 degrees), so as to realize liquid repulsion; the lubricated plane generally has a low contact angle hysteresis (difference between an advancing angle and a receding angle) or a rolling angle, and can reduce liquid residue or easily slide away liquid to realize liquid repellency; the catalytic material may be excited by external energy to degrade the contaminants.

In the aspect of catalytic materials, although research and development in the field of catalytic materials degrading organic matters have been carried out to some extent, the existing catalytic coatings still have many defects, such as poor lyophobic performance, rough structure (which may bring more residues to cause pollution), low durability, low adhesion with substrates, and the like, so that the application of the catalytic materials in the antifouling field is limited to some extent. Therefore, there is a need to develop a catalytic coating that can both repel liquid contamination and catalytically degrade organic residues.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a preparation method of an antifouling photocatalytic coating, wherein a composite coating/coating which can repel liquid pollution and can catalyze and degrade organic residues is prepared by using a fluorine-free material, and meanwhile, the coating has the advantages of mild preparation conditions, certain transparency, high adhesive force, coating universality, capability of being made into a block material and the like.

In order to achieve the purpose, the invention adopts the technical scheme that:

the invention provides a preparation method of an antifouling photocatalytic coating, which comprises the following steps:

s1, modification of the nano catalyst: firstly, adding water with the same volume to 10-50g of triethanolamine to prepare triethanolamine solution, then dispersing a nano catalyst in the water according to the feed-to-liquid ratio of 1-10g/180mL, adding the triethanolamine solution by constant pressure titration, continuously stirring for 12-24 hours, and then washing, centrifuging and drying to obtain a modified nano catalyst;

s2, grafting of isocyanate: firstly, preparing a catalyst into a catalyst solution with the weight percent of 2-20, then adding toluene, the catalyst solution and low surface energy molecules into isocyanate, placing the mixture into an oil bath with the temperature of 80-120 ℃, stirring and reacting for 1-4h, cooling to remove the toluene, then adding acetonitrile, centrifuging, taking supernate and removing the solvent to obtain grafted isocyanate; the low surface energy molecule is polydimethylsiloxane or a copolymer thereof;

s3, preparation of the antifouling photocatalytic coating: and (3) adding the isocyanate grafted in the step S2 and a polyhydroxy reaction substrate into a cosolvent, adding 2-10 wt% of the nano catalyst modified in the step S1, and uniformly stirring to prepare the antifouling photocatalytic coating.

Preferably, the nanocatalyst comprises titanium dioxide, zirconium oxide, zinc oxide, tungsten oxide, iron oxide, tin oxide, strontium titanate, lead sulfide, zinc sulfide, cadmium sulfide, platinum, rhodium, palladium. Specifically, the nano-catalyst is titanium dioxide (TiO)₂)。

Preferably, the particle size of the nano-catalyst is 1 to 100 nm. Specifically, the particle size of the nano-catalyst is 25 nm.

Preferably, the adding proportion of the isocyanate, the toluene, the catalyst solution and the low surface energy molecule is as follows: 13.9 g: 3-30 mL: 20 μ L of: 0.1-11.4 g. Specifically, the adding proportion of the isocyanate, the toluene, the catalyst solution and the low surface energy molecule is as follows: 13.9 g: 3mL of: 20 μ L of: 0.19 g.

Preferably, the addition ratio of the grafted isocyanate to the polyhydroxy reaction substrate and the cosolvent is 1 g: 1-5 g: 1-50 mL. Specifically, the addition ratio of the grafted isocyanate to the polyhydroxy reaction substrate and the cosolvent is 1 g: 3 g: 20 mL.

Preferably, the isocyanate is an isocyanate-based mono-or oligomer comprising 2 or more functional groups, and the isocyanate group content of the isocyanate is 10 to 30 wt%.

Further, the isocyanate includes at least one of hexamethylene diisocyanate or a dimer or trimer thereof, toluene diisocyanate, p-phenylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, methylene diisocyanate, lysine diisocyanate, 1, 5-naphthalene diisocyanate, cyclohexane diisocyanate, 3 '-dimethyl-4, 4' -diphenyl diisocyanate, m-xylylene diisocyanate, ethyl (yl) phenyl diisocyanate, xylene diisocyanate, triphenylmethane triisocyanate, and L-lysine triisocyanate.

Specifically, the isocyanate is Hexamethylene Diisocyanate trimer (Hexamethylene Diisocyanate trimer, HDIT).

Preferably, the low surface energy molecules comprise monohydroxy terminated linear polydimethylsiloxane, monohydroxy terminated poly branched polydimethylsiloxane, monohydroxy terminated polydimethylsiloxane copolymer, and the low surface energy molecules have a hydroxyl equivalent weight of 10-20g/mol and a molecular weight of 1000-10000 g/mol.

Specifically, the low surface energy molecule is monohydroxy terminated Linear Polydimethylsiloxane (LPDMS), and the hydroxyl equivalent weight of the low surface energy molecule is 12 g/mol.

Preferably, the polyhydroxy reaction substrate comprises a linear polyhydroxy acrylate copolymer, a branched polyhydroxy acrylate copolymer, and the polyhydroxy reaction substrate has a hydroxyl content of 1 to 10 wt%.

Specifically, the polyhydroxy reaction substrate is Polyacrylate copolymer (PAC), and the hydroxyl group content of the polyhydroxy reaction substrate is 3 wt%.

Preferably, the catalyst comprises dibutyltin dilaurate, triethylenediamine, and bis (dimethylaminoethyl) ether. Specifically, the catalyst is Dibutyltin Dilaurate (DBTDL).

Further, the solvent dissolving the catalyst includes at least one of acetone, acetonitrile, diethyl ether, ethyl acetate, and butyl acetate.

Preferably, the cosolvent comprises at least one of acetonitrile, ethyl acetate, butyl acetate and tetrahydrofuran.

The invention also provides the antifouling photocatalytic coating prepared by the preparation method.

The invention also provides an application of the antifouling photocatalytic coating in preparation of an antifouling photocatalytic coating, which specifically comprises the following steps: the antifouling photocatalytic coating is coated on the surface of a material and is heated and cured for 1-4 hours at the temperature of 80-100 ℃ to obtain the antifouling photocatalytic coating.

Preferably, the coating method comprises spin coating, draw coating, brush coating and dip coating.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a preparation method of an antifouling photocatalytic coating, which adopts triethanolamine to carry out amino (-NH) on a nano catalyst₂) Pre-modifying, grafting isocyanate through low surface energy molecules, and reacting with a polyhydroxy reaction substrate to prepare the novel antifouling photocatalytic coating/coating, thereby greatly enhancing the composite performance of the antifouling material. Overall, the invention has the following advantages:

(1) the prepared coating has antifouling performance (can repel liquid pollution) and catalytic property, can effectively degrade organic residues, and improves antifouling efficiency; (2) the prepared product has certain transparency, and can be applied to the field of low transparency; (3) the prepared coating has high adhesive force, can be coated on the surfaces of various materials, and enhances the antifouling efficiency; (4) the prepared coating is free of fluorine substances and is environment-friendly; (5) the prepared coating has mild preparation conditions and does not need high-temperature calcination; (6) during the preparation process, the nanometer catalyst particle is processed by amino (-NH)₂) The pre-modification can not only increase the dispersibility of particles, but also enhance the bonding force with the reaction of a coating and reduce the defects of cavities and the like; (7) the prepared coating can be prepared by spin coating, drawing coating, brush coating,Dip coating and the like, and can be used for preparing block profiles by various methods such as casting, extrusion, hot pressing and the like.

Drawings

FIG. 1 is an XRD pattern of an antifouling photocatalytic coating;

FIG. 2 is an energy dispersive X-ray spectrum of the anti-fouling photocatalytic coating;

FIG. 3 is a demonstration of the transparency of the anti-fouling photocatalytic coating (a) and the transparency values tested under an ultraviolet-visible spectrometer (b);

FIG. 4 is a graph of the static and dynamic contact angles of water (a), the static and dynamic contact angles of C16 (b), the sliding angles of water and C16 (C) for the antifouling photocatalytic coating;

FIG. 5 is an adhesion test for comparative coating 1(a), coating 1(b), coating 2(c), coating 3 (d);

FIG. 6 shows the results of a catalytic performance test of an antifouling photocatalytic coating;

FIG. 7 is a schematic view of the anti-fouling principle of the anti-fouling photocatalytic coating.

Detailed Description

The following further describes the embodiments of the present invention. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The experimental procedures in the following examples were carried out by conventional methods unless otherwise specified, and the test materials used in the following examples were commercially available by conventional methods unless otherwise specified.

EXAMPLE 1 preparation of antifouling photocatalytic coating

(1) Modification of the nano-catalyst: taking 25g of triethanolamine and deionized water with the same volume, uniformly mixing, and adding the obtained triethanolamine solution into a 500mL beaker; 2g of TiO with a particle size of 25nm were taken₂Dispersing the nanometer catalyst in 180mL deionized water, ultrasonic or cell pulverizing, and adding into the triethanolamine solution via constant pressure titration funnel at minimum rate (10 drops)One minute) is added, and the mixture is continuously stirred for 24 hours, after the modification is finished, ethyl acetate is used for cleaning and centrifuging, and the supernatant fluid is collected and dried for 24 hours in vacuum, so as to obtain the modified nano catalyst;

(2) isocyanate grafting: dissolving 10 wt% of dibutyltin dilaurate (DBTDL) in 5g of acetone to obtain a catalyst solution, then taking 13.9g of HDIT (with the content of isocyanate groups being 23.0 wt%) in a 250mL three-neck flask, respectively adding 3mL of toluene, 20 uL of the catalyst solution and 1.9g of LPDMS (with the hydroxyl equivalent being 12g/mol) into the flask, placing the flask in a 90 ℃ oil bath kettle, stirring for reaction for 3 hours, removing the toluene by using a rotary evaporator after the reaction, adding acetonitrile, centrifuging at 10000rpm for 10 minutes, taking a supernatant, and distilling to obtain grafted isocyanate;

(3) preparation of the antifouling photocatalytic coating: adding 1g of grafted isocyanate and 3g of PAC (hydroxyl content is 3 wt%) into 20mL of acetonitrile, adding 2 wt% of modified nano catalyst (solid content), stirring uniformly, spin-coating on the surface of glass, heating at 100 ℃ for 1 hour, and curing to obtain the antifouling photocatalytic coating 1.

Example 2 preparation of antifouling photocatalytic coating

The preparation method is the same as example 1, except that the addition amount of the modified nano catalyst is 2 wt%, and finally the antifouling photocatalytic coating 2 is prepared.

Example 3 preparation of antifouling photocatalytic coating

The preparation method is the same as example 1, except that the addition amount of the modified nano catalyst is 10 wt%, and finally the antifouling photocatalytic coating 3 is prepared.

Comparative example 1 preparation of antifouling photocatalytic coating

(1) Isocyanate grafting: dissolving 10 wt% of dibutyltin dilaurate (DBTDL) in 5g of acetone to obtain a catalyst solution, then taking 13.9g of isocyanate (the content of isocyanate groups is 23.0 wt%) in a 250mL three-neck flask, respectively adding 3mL of toluene, 20 uL of the catalyst solution and 1.9g of LPDMS (hydroxyl equivalent weight is 12g/mol) into the flask, placing the flask in a 90 ℃ oil bath kettle, stirring and reacting for 3 hours, removing the toluene by using a rotary evaporator after the reaction, adding acetonitrile, centrifuging at 10000rpm for 10 minutes, taking a supernatant and distilling to obtain grafted isocyanate;

(2) preparation of the antifouling photocatalytic coating: adding 1g of grafted isocyanate and 3g of PAC (hydroxyl content is 3 wt%) into 20mL of acetonitrile, uniformly stirring, spin-coating on the surface of glass, and heating at 100 ℃ for 1 hour for curing to obtain the antifouling photocatalytic coating 1.

Experimental example 1 Performance test

(1) Contact angle value test

Using the coatings applied to the glass sheets in examples 1 to 3 and comparative example 1 as test samples

Contact angle meters test their contact angle values for water, C16. Wherein, the angle of water: the static contact angle was measured by averaging 3 points using 5. mu.L of water; the advancing angle and the retreating angle were measured by the liquid adding and reducing method, and the volume was 15. mu.L, and the liquid adding and reducing rate was 0.05. mu.L/s. The roll angle was 10. mu.L of water and the tilt rate was 10 °/min. Angle of C16: static angle used 2. mu.L of C16, rolling angle used 5. mu.L of C16, and other test conditions with water.

The larger the static contact angle, the smaller the contact angle hysteresis and the smaller the rolling angle of the coating to water or n-hexadecane, the better the lyophobic performance is. It can be seen from table 1 that after the content of the nano-catalyst is increased, the static angles of water and n-hexadecane are reduced to a certain extent, but the nano-catalyst still shows strong lyophobic property, which indicates that the nano-catalyst still has high antifouling effect after being added into the coating. The adhesion of the coating remains at level 4B. Therefore, the antifouling coating and the nano catalyst are combined to increase the catalytic property of the coating, so that the comprehensive performance of the material is improved.

TABLE 1 contact Angle value test results for different antifouling photocatalytic coatings

(2) X-ray diffraction pattern (XRD)

The coating samples of examples 1-3 and comparative example 1 were scraped from the material and introduced into a test mold (as virgin TiO)₂Nanoparticles as a control), and then XRD test was performed using a D-MAX2200 VPC X-ray diffractometer of japan association of science, and during the test, a Cu K α source was used, and the measurement angle was 10 ° to 80 °. As can be seen from FIG. 1, in XRD test, the absorption peaks of the five curves can correspond to the absorption peaks of the crystal planes (101), (004), (200), (105), (211), (204), (116), (220) and (215) of anatase crystal form, which shows that the crystal form of the titanium dioxide powder is not changed after the titanium dioxide powder is modified, coated, heated at 100 ℃.

(3) Energy dispersive X-ray spectroscopy

The coating samples of examples 1-3 and comparative example 1 were subjected to elemental analysis using energy dispersive X-ray (EDX) with FEI Quanta 400FEG attached and semi-quantitatively determined for elemental content. From FIG. 2, TiO of four samples can be obtained₂The mass fractions were 0 wt%, 1.29 wt%, 9.82 wt%, 21.02 wt%, respectively, since EDX is a semi-quantitative detection method, it can be seen that the test results are consistent with the actual trend.

(4) Transparency test

The glass coated with the catalytic coating in examples 1 to 3 and comparative example 1 was used as a sample, and the test was carried out by Shimazu UV-2600 UV-visible spectrometer of Shimazu, Japan, at a scanning rate of 2nm/s and in a scanning range of 400nm to 800 nm. As can be seen from FIG. 3, TiO₂When the amount is 2 wt%, the transparency is high, and as the amount increases, the transparency decreases, but the transparency still remains in the visible light region. The method has potential application in the field of low transparency, such as ground glass.

(5) Contact angle value test

Use of

Contact angle meter, wherein the angle of water: static contact Angle of 3 points using 5. mu.L of WaterAverage value; the advancing angle and the retreating angle are tested by a liquid adding and reducing method, the volume is 15 mu L, and the liquid adding and reducing speed is 0.05 mu L/s. The roll angle was 10. mu.L of water and the tilt rate was 10 °/min.

Angle of C16: the static angle used was 2. mu.L of C16, and the roll angle used was 5. mu.L of C16. Other test conditions were the same as water.

As can be seen from FIG. 4, TiO₂When the addition amount is as large as 10 wt%, the static contact angle of water can be kept at 93.92 degrees, and the static contact angle of C16 is 30.27 degrees, compared with the static contact angle of the water without TiO₂The coating is respectively reduced by 10.2 percent and 13.4 percent, but the lyophobic performance is still stronger. The contact angle hysteresis of the water and the C16 are respectively increased by 93.2 percent and 412.3 percent, and the rolling angle is increased by 33.7 percent and 129.1 percent. Indicating that the coating is still capable of repelling liquids and maintaining antifouling properties.

(6) Adhesion test

The coatings of examples 1-3 and comparative example 1 were cross-hatch tested according to ASTM D3359-17 using Elcometer 99 tape, UK, easy high. As can be seen from FIG. 5, the coating had only a very small amount of peeling after the tape peeling test, and met the 4B rating (< 5% peeling. the highest rating of the method is 5B), which proves that the coating has strong adhesion and can be coated on the surfaces of various materials.

(7) Test for catalytic Performance

Preparing 10L/mol methylene blue aqueous solution as a catalytic substrate, putting the glass sheets containing the coatings in examples 1-3 and comparative example 1 into a container containing the methylene blue aqueous solution at a rate of 1W/cm^-2The irradiation intensity of (2) is irradiated for 15 h. Then, the test was carried out by using Shimazu UV-2600 UV-visible spectrometer of Shimadzu, Japan, at a scanning rate of 2nm/s and a scanning range of 400nm-800 nm.

According to the Lambert-Beer law, when parallel monochromatic light vertically passes through a light-absorbing object, the absorbance and the concentration of a light-absorbing substance are in a direct proportion relation. From FIG. 6, it can be observed that the intensity of the maximum absorption peak of methylene blue at 662nm varies with TiO₂The addition amount is increased and obviously reduced, which shows that the coatings have catalytic performance, and the coating of the organic coating does not obviously reduce TiO₂The catalytic performance of (A) indicates that the two can cooperatePlays a role and realizes the combination of functions.

It can be seen from the above analysis that the antifouling photocatalytic coating of the present invention combines the antifouling organic component and the nanoparticles having catalytic effect, which can reduce the residue when contacting the organic pollutant droplets and degrade the residual organic matters after contacting, thereby greatly enhancing the antifouling performance of the coating (the antifouling principle is shown in fig. 7).

The embodiments of the present invention have been described in detail, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.

Claims

1. The preparation method of the antifouling photocatalytic coating is characterized by comprising the following steps:

s1, modification of the nano catalyst: firstly, adding triethanolamine solution prepared by water with the same volume into 10-50g of triethanolamine, dispersing a nano catalyst into the water according to the proportion of 1-10g/180mL, adding the triethanolamine solution by constant pressure titration, continuously stirring for 12-24 hours, and then washing, centrifuging and drying to obtain a modified nano catalyst;

s2, grafting of isocyanate: firstly, preparing a catalyst into a catalyst solution with the weight percent of 2-20%, then adding toluene, the catalyst solution and low surface energy molecules into isocyanate, placing the mixture into an oil bath with the temperature of 80-120 ℃ to be stirred and react for 1-4h, cooling to remove the toluene, then adding acetonitrile, centrifuging, taking supernate, and removing the solvent to obtain grafted isocyanate; the low surface energy molecule is polydimethylsiloxane or a copolymer thereof;

2. The method of claim 1, wherein the nano-catalyst comprises titanium dioxide, zirconium oxide, zinc oxide, tungsten oxide, iron oxide, tin oxide, strontium titanate, lead sulfide, zinc sulfide, cadmium sulfide, platinum, rhodium, palladium.

3. The method of claim 1, wherein the particle size of the nano-catalyst is 1-100 nm.

4. The method of claim 1, wherein the isocyanate is a monomolecular or oligomer isocyanate having 2 or more functional groups, and the isocyanate group content of the isocyanate is 10 to 30 wt%.

5. The method of claim 4, wherein the isocyanate comprises at least one of hexamethylene diisocyanate or its dimer or trimer, toluene diisocyanate, p-phenylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, methylene diisocyanate, lysine diisocyanate, 1, 5-naphthalene diisocyanate, cyclohexane diisocyanate, 3 '-dimethyl-4, 4' -diphenyl diisocyanate, m-xylylene diisocyanate, ethyl (yl) benzene diisocyanate, xylene diisocyanate, triphenylmethane triisocyanate, and L-lysine triisocyanate.

6. The method as claimed in claim 1, wherein the low surface energy molecule comprises monohydroxy terminated linear polydimethylsiloxane, monohydroxy terminated poly branched polydimethylsiloxane, and monohydroxy terminated polydimethylsiloxane copolymer, and the low surface energy molecule has a hydroxyl equivalent weight of 10-20g/mol and a molecular weight of 1000-10000 g/mol.

7. The method of claim 1, wherein the polyol reaction substrate comprises a linear polyol acrylate copolymer, a branched polyol acrylate copolymer, and the hydroxyl group content of the polyol reaction substrate is 1 to 10 wt%.

8. The method of claim 1, wherein the catalyst comprises dibutyltin dilaurate, triethylenediamine, and bis (dimethylaminoethyl) ether.

9. An antifouling photocatalytic coating material produced by the production method according to any one of claims 1 to 8.

10. The application of the antifouling photocatalytic coating of claim 9 in preparing an antifouling photocatalytic coating, which is characterized in that the antifouling photocatalytic coating of claim 9 is coated on the surface of a material and is heated and cured for 1-4 hours at 80-100 ℃.