CN113322006A

CN113322006A - Preparation method and application of biomass-based super-hydrophobic coating with durability and color diversity

Info

Publication number: CN113322006A
Application number: CN202110658334.8A
Authority: CN
Inventors: 李学林; 任金瓶; 刘利彬; 陶芙蓉; 班青; 盖利刚
Original assignee: Qilu University of Technology
Current assignee: Qilu University of Technology
Priority date: 2021-06-07
Filing date: 2021-06-11
Publication date: 2021-08-31
Anticipated expiration: 2041-06-11
Also published as: CN113322006B

Abstract

The invention belongs to the field of coatings. Relates to a preparation method and application of a biomass-based super-hydrophobic coating, in particular to a preparation method and application of a biomass-based super-hydrophobic coating with color diversity and excellent durability, wherein micro-nano particles are weighed and dispersed into a mixed solution of absolute ethyl alcohol and acetic acid; the micro-nano particles are three or four of cellulose, chitosan, zeolite and PTFE; adding dye into the solution, and stirring at 40-80 deg.C for 5-8 hr to obtain colored suspension; FAS was added dropwise to the above solution and stirred for 1-3 hours; and dropwise adding AS, and continuously stirring for 2-4h to finally obtain the colored coating liquid. The invention obtains colorful super-hydrophobic coatings with various colors and good mechanical property by using the biomass material through a simple method, gives various colors to the super-hydrophobic coatings, and can also draw by dip coating, spray coating or using the coatings as pigments.

Description

Preparation method and application of biomass-based super-hydrophobic coating with durability and color diversity

Technical Field

The invention belongs to the field of coatings. Relates to a preparation method and application of a biomass-based super-hydrophobic coating, in particular to a preparation method and application of a biomass-based super-hydrophobic coating with color diversity and excellent durability.

Background

Colored superhydrophobic materials have received extensive attention due to their potential in the decorative arts for aesthetic appeal, but there has been little research into the preparation of colored superhydrophobic materials.

Wang et al [ F.Wang, X.Zhang, L.Zhang, M.Cao, Y.Lin, J.Zhu, Rapid failure of angle-independent structured files with a super-hydrolytic property, Dyes and Pigments 130(2016)202-]By spraying monodisperse SiO₂The nanosphere and polydimethylsiloxane solution prepare the angle-independent structural colored super-hydrophobic membrane. Can be prepared by changing SiO₂The nanospheres are sized to adjust the color independent of angle. Similarly, Yi et al [ B.Yi, H.Shen, structural coordinated files with hyper-reactivity and de virgins based on bump-like proteins, applied. surf.Sci.427(2018)1129-]Provides a polystyrene particle coated with melanin-like polydopamine based on concave-convexAnd (3) preparing a colorful super-hydrophobic film of the particles. The color of the film is due to the interaction between the submicron structures and light waves in the visible range. However, the structural color has strict requirements on particle size, which is not suitable for the preparation of multiple colors.

Xu et al [ K.xu, S.Ren, J.Song, J.Liu, Z.Liu, J.Sun, S.Ling, Colorfull super hydrophic concrete coating, chem.Eng.J.403(2021)126348] produced a colored superhydrophobic concrete coating, but only four colors were obtained. Therefore, although the color super-hydrophobic coating has made some progress, the wide application of the color coating in outdoor environment is limited due to the problems of complicated preparation, environmentally-friendly raw materials, poor adaptability of the substrate, insufficient color diversity and the like.

Although attempts have been made to produce colored superhydrophobic papers by precipitating cellulose and colored stearates on swollen and nearly dissolved cotton, wet asymmetric cellulose sheets with a two-color surface are achieved by an extrusion drying process. But the manufacturing process is complicated and is not beneficial to large-scale production.

Disclosure of Invention

In response to the deficiencies of the prior art, we designed and manufactured a series of color tunable superhydrophobic coatings with excellent durability that can be coated on different substrates by various methods such as spraying, dipping and painting (fig. 1).

The compounds referred to in the present invention are abbreviated as follows:

FAS: 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane;

AS: [3- (trimethoxysilyl) propyl ] ethylenediamine;

PTFE: polytetrafluoroethylene;

MB: methyl blue;

MO: methyl orange;

rh B: and (3) rhodamine B.

WCA: water contact angle.

The invention provides a preparation method of a color coating liquid, which comprises the following steps:

1) weighing the micro-nano particles, and dispersing the micro-nano particles into a mixed solution of absolute ethyl alcohol and acetic acid; the micro-nano particles are three or four of cellulose, chitosan, zeolite and PTFE;

2) adding dye into the solution, and stirring at 40-80 deg.C for 5-8 hr to obtain colored suspension;

3) FAS was added dropwise to the above solution and stirred for 1-3 hours;

4) and dropwise adding AS, and continuously stirring for 2-4h to finally obtain the colored coating liquid.

Preferably, in the step 1), the mass ratio of the cellulose, the chitosan, the zeolite and the PTFE is (1-9): (9-1): (1-9): (9-1). More preferably, the mass ratio of the cellulose to the chitosan in the step 1) is (4-6): (6-4); the mass ratio of the zeolite to the PTFE is (2-4): (8-6). More preferably, the mass ratio of cellulose, chitosan, zeolite and PTFE in step 1) is 6: 4: 3: 7.

the four micro-nano particles such as cellulose, chitosan, zeolite, PTFE and the like play a role in providing roughness in the preparation of the coating respectively; the accumulation of the micro-nano particles with different scales can generate different roughness, the micro-nano particles with various sizes can provide multi-level roughness, the micron/nano sizes of cellulose, chitosan, zeolite and PTFE can be selected according to needs, three or more different sizes are selected, the multi-level roughness is favorably formed, preferably, the micro-nano particles select three kinds of roughness of 8-30 mu m, 80-120nm and 400-doped 800nm, or the micro-nano particles select four kinds of roughness of 5-15 mu m, 20-30 mu m, 80-120nm and 400-doped 800nm, and a good effect can be achieved.

More preferably, the micro/nano sizes of cellulose, chitosan, zeolite and PTFE are 25 μm, 400 nm, 800nm, 10 μm and 100nm, respectively. The results of the nanoparticle particle study are shown in table 1.

Preferably, in the step 1), the volume ratio of the absolute ethyl alcohol to the acetic acid in the mixed solution of the absolute ethyl alcohol and the acetic acid is (4-8): 1. The addition amount of the mixed solution is 10-30 times of the total weight of the micro-nano particles, preferably 15-20 times.

Preferably, in the step 2), the dye is Methyl Blue (MB), Methyl Orange (MO), rhodamine B (Rh B); during the dyeing process, MO, MB and Rh B are used as the three main dyes. The ternary phase diagram of the dye mixture ratio can be obtained by adjusting the mass ratio of the three dyes (fig. 2). Thereby obtaining coating liquids of different colors.

Preferably, in the step 3), the addition amount of the FAS is 5-75% of the total weight of the micro-nano particles. More preferably, in the step 3), the addition amount of the FAS is 55-75% of the total weight of the micro-nano particles. FAS serves to provide low surface energy in the preparation of coatings, respectively, and can enhance the hydrophobic properties.

Preferably, in the step 4), the addition amount of the AS is 26-130% of the total weight of the micro-nano particles. More preferably, in the step 4), the addition amount of the AS is 75-130% of the total weight of the micro-nano particles. More preferably, in the step 4), the addition amount of the AS is 90-110% of the total weight of the micro-nano particles. The AS plays a role in adhesion in the preparation of the coating respectively, and can enhance the adhesion of the coating liquid and the base material.

The invention also provides the color coating liquid prepared by the method.

The invention provides a preparation method of a colored super-hydrophobic coating, which comprises the following steps:

the color coating liquid prepared by the method is coated on a substrate, the coating material is heated for 4-6h at 70-90 ℃, and then dried for 20-40min at 100-120 ℃ to obtain the color coating.

Preferably, a spray gun is used to spray a colored coating solution (2mL) from a distance of 10cm vertically to coat various substrates such as glass, aluminum sheets, tiles and wood. The cotton fabric may be dipped into the coloured suspension.

Preferably, the colour coating is obtained by heating the coating material in an oven at 80 ℃ for 5h, followed by drying at 110 ℃ for 30 min.

The colored superhydrophobic coating prepared by the method, the SEM image of the cross section of the colored superhydrophobic coating and the element mapping of Si, N and F prove the existence of the anchoring layer in the adhesion mechanism diagram, namely, FIG. 13, a layer area exists near the substrate, wherein Si and N elements are uniformly distributed in the anchoring layer, and F element is almost not existed. This not only indicates that the surface migration of the F element results in superhydrophobicity of the coating, but also confirms the presence of the anchoring layer.

EDX spectra showed that all elements including N, Si, F, Al, S and Na elements were uniformly distributed on the surface of the coating (fig. 10 a-F). The XPS spectra of the coatings show (FIG. 11) that the two significant components at 689.2eV and 688.1eV are due to the decomposition of CF from the F1s peak₂And CF₃A key. These results indicate that the F elements from FAS and PTFE are uniformly distributed on the coating surface, further enhancing the superhydrophobicity of the coating.

SEM images of the coating at different magnifications (see fig. 9(a-c)) show that the micro-nano particles adhere tightly and uniformly to the substrate and show good adhesion between the coating and the substrate. Fig. 14, 16, 17, 18 all show good adhesion between the coating and the substrate.

Peel tests were performed on coated cotton fabrics, glass, aluminum sheets, wood and ceramic tiles. Every 5 peels is defined as one peel cycle. After 20 peel cycles, the WCA on the coated substrate dropped from about 160 ° to about 150 °, confirming the strong adhesion and excellent superhydrophobicity of the coating on the different substrates (fig. 16).

For the hard substrate, the adhesive strength is measured by a drawing adhesion tester, and the adhesive force between the coating and the substrate is 0.8 MPa-1.6 MPa.

Sandpaper abrasion test the coating on the glass substrate was placed face down on 800cW sandpaper weighing 200g and each 10cm was defined as the abrasion cycle. After a wear distance of 40m, the coating still exhibited superhydrophobicity with WCA greater than 150 ° (fig. 19).

Water impact test, the coated glass was placed at a vertical distance of 10cm from the spray gun, the water impact speed was 14.6m/s under 200kPa water pressure (FIG. 21), and after 20min of water impact, the color and superhydrophobicity of the coating did not change significantly, indicating that the coating had excellent water resistance.

And (3) depositing acid, alkali and/or salt droplets with the pH value of 1-14 on the coated glass, measuring the WCA once every 5min, wherein the WCA still exceeds 150 degrees after 30 min.

The whole surface of the superhydrophobic coating was not corroded and the color and superhydrophobicity were not significantly changed after 24 hours of salt spray test, indicating that the coating has excellent salt tolerance and shows great application potential in marine protection (fig. 24). Furthermore, there was little change in WCA and color of the MO-dyed coating after exposing the coated glass to 365nm UV light for 300min, indicating that the coating did not fade readily and exhibited significant UV resistance upon UV exposure (FIG. 25).

The invention also provides application of the colored super-hydrophobic coating, which is used for antifouling paint and painting pigment. The super-hydrophobic coating and the colored super-hydrophobic coating can also reduce resistance, delay icing, prevent fog and the like.

The invention has the beneficial effects that:

the invention can obtain the colorful super-hydrophobic coating with various colors and good mechanical property by utilizing the biomass material through a simple method. The general super-hydrophobic coating only shows a single color, and the super-hydrophobic coating is endowed with various colors on the premise of ensuring the super-hydrophobic property of the coating. In addition, it is also possible to draw by dipping, spraying or using it as a pigment, etc., with various application routes and use patterns.

The color of the coating can be adjusted by changing the mass ratio of the dyes. More importantly, the paint can be used as a pigment for drawing on different substrates and has potential application prospect in the aspect of maintaining artworks.

Adhesion between the coating and the substrate is very important for making a strongly superhydrophobic coating. However, improvement of adhesion requires interaction of the polar groups of the coating with the substrate, and an increase in polar groups inevitably leads to a decrease in superhydrophobicity. Thus, it is a great challenge to produce a vivid, robust superhydrophobic coating from biomass materials by a viable and cost-effective process. The present invention proposes a simple method for manufacturing a colored superhydrophobic coating having excellent robustness by using materials such as cellulose and chitosan. The three main dyes are used as basic colors, and the coating with various colors can be obtained by single dyeing or mixed dyeing. And the coating can be applied to hard substrates (e.g., glass, aluminum sheets, wood and ceramic tiles) and soft substrates (e.g., cotton fabrics) by various methods such as spraying, dipping and painting. Furthermore, the colored coating can adhere strongly to the substrate due to multiple interactions (covalent siloxane bonds and hydrogen bonds). The coating has water repellency, can bear the tests of abrasive paper abrasion, adhesive tape stripping circulation, water impact, ultraviolet irradiation and the like, and has excellent environmental durability. Moreover, the color coating can be used as a novel pigment for drawing on different substrates, and is expected to show great potential application in process design or decoration.

Drawings

FIG. 1 is a schematic diagram of a process for preparing a colored superhydrophobic coating.

FIG. 2 is a ternary phase diagram of dye ratios.

FIG. 3 is a photograph of corresponding multi-colored superhydrophobic coatings prepared according to dye proportioning at points A-P.

FIG. 4 is a graph of the color gradient of a superhydrophobic coating and the corresponding dye proportioning.

Fig. 5(a) N2 adsorption-desorption isotherms typical of the original micro-nano particles. (b) And (3) the pore size distribution diagram of the original micro-nano particles.

Fig. 6 shows the change spectrogram of the ultraviolet-visible absorption spectrum before and after the adsorption of Rh B (a), mo (B), mb (c) by the micro-nano particles.

Figure 7 images of various colored superhydrophobic coatings and WCA.

Figure 8 images and WCA of superhydrophobic coatings with different color gradients.

Fig. 9(a-c) SEM images of MO-stained superhydrophobic coatings at different magnifications.

FIG. 10 shows EDX spectra of the elements N (a), Si (b), F (c), Al (d), S (e) and Na (f) of the MO-dyed superhydrophobic coating.

Fig. 11 XPS spectrum (a) and F1s spectrum (b) of the coating.

FIG. 12 is a graph of the adhesion mechanism of a colored superhydrophobic coating.

Fig. 13 SEM images of cross-sections of the colored superhydrophobic coatings (a) and elemental mapping of si (b), n (c), and f (d).

Figure 14 cross-sectional SEM images of MO dyed superhydrophobic coatings at different magnifications.

Figure 15 water, cola, tea and fruit juice were placed on cotton fabric, wood and ceramic tile, respectively, coated with different color coatings.

FIG. 16 tape peel tests were performed on the coatings on various substrates.

FIG. 17 shows the change of the WCA coating in the rub resistance test, with photographs showing the comparison before and after the rub test.

FIG. 18 adhesion testing of the coating to different substrates (e.g., wood, tile, aluminum panels, and glass), with the coating flaking off.

FIG. 19 abrasion durability test of coating layer in sandpaper abrasion test, inset is static contact angle diagram of water on coating surface before and after abrasion

Fig. 20(a) and (b) SEM images of MO dyed superhydrophobic coatings at different magnifications before and after abrasion testing.

Figure 21 effect of water impact test on coated WCA.

Fig. 22 shows the change of WCA with time by dropping an acid (aqueous HCl solution at pH 2), a base (aqueous NaOH solution at pH 14), and a salt (aqueous 3M NaCl solution) on a coated glass substrate

Fig. 23 measures the contact angle of drops of different pH placed on a coated glass substrate.

FIG. 24 comparative photographs of an original aluminum plate (a) and an MO-dyed superhydrophobic-coated aluminum plate (b) before and after a salt spray test.

FIG. 25 shows the effect of UV irradiation on the WCA of a coating over a long period of time, with the inset being a comparison of the color coating before and after UV irradiation.

FIG. 26 application of colored superhydrophobic coatings on various substrates. Lotus on canvas (a), morning glory on paper (b), Chinese antique on wood (c) and painted pottery (d).

Detailed Description

The following examples further illustrate the invention, but the invention is not limited thereto.

Material

Alpha-cellulose (diameter: 25 μm), zeolite (diameter. ltoreq.10 μm) and [3- (trimethoxysilyl) propyl group]Ethylene diamine (AS) from an Aladdin chemical testAgent limited (china). Chitosan (molecular weight: 9.48X 10)⁵Degree of deacetylation of not less than 95%) was provided by Jiuding chemical reagents, Inc. (China). Polytetrafluoroethylene nanoparticles (PTFE, 100nm diameter) were obtained from Jiangsu Brilliant fluoroplastics GmbH (China). 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane (FAS) was obtained from Tai Fuji chemical company, Inc. (China), North Ji, China. Methyl Blue (MB) and Methyl Orange (MO) were supplied by Tianjin Daloco Chemicals, Inc. (China). Rhodamine B (Rh B) was purchased from national drug-controlled chemical Co., Ltd., China. Cotton cloth, aluminum sheeting, tile, glass, canvas, paper, wood, ceramic and sandpaper (800cw) were purchased from local stores. All chemicals were analytically pure and were used directly without purification.

Mechanical stability test

Tape peel tests were performed on the surfaces of the different coated substrates with strong adhesive tape. For the sandpaper abrasion test, the coating on the glass substrate was placed face down on 800cW sandpaper weighing 200 g. For the water impact test, the coated glass substrate was placed 10cm perpendicular to the spray gun with a water impact velocity (V) of-14.6 m.s^-1(

Q＝1.93×10^- ⁵m³·s^-1Q is the flow rate, and d ═ 1.3mm is the nozzle diameter). The adhesion strength values of the coatings on the different substrates were measured by the drawing method according to ASTM D4541. That is, an aluminum spindle having a diameter of 20mm was stuck on the coating surface. After curing for 72 hours at room temperature, the aluminum spindle was pulled at a uniform speed until the coating had peeled off the substrate.

Chemical stability test

The chemical stability of the colored coatings was tested using acidic solutions (aqueous HCl) and basic solutions (aqueous NaOH) with different pH values and a salt solution (3M NaCl). For the UV resistance test, the coated glass plate was treated with 365nm UV light. The change in color and superhydrophobicity of the coated glass sheet surface was observed and recorded.

Characterization of

The surface morphology of the coating is by SUPRA^TM55 thermal field emission scanning electron microscopy (SEM, Germany) at 5 kV. Energy dispersive X-ray (EDX) spectroscopy was observed using a scanning electron microscope (SEM, Germany). The surface composition of the coating was measured by X-ray photoelectron spectroscopy (XPS, Thermo, America, ESCALABXi +). The pore size distribution and specific surface area (ASAP, Norcross, GA, USA) of the primary micro-nano particles were determined using Brunauer-Tmmet-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods based on N2 adsorption-desorption isotherms. The static contact angle of a 6 μ Ι _ drop was measured on a contact angle measuring instrument (SL250 USA KINO Industry co., Ltd) and at least 3 different zones were used to obtain the average contact angle. Ultraviolet-visible (UV-vis) Diffuse Reflectance Spectra (DRS) were tested in the wavelength range from 200nm to 800nm using a spectrophotometer (UV-2600, Shimadzu, Kyoto, Japan). The coatings were tested for salt resistance using a salt spray box (LS-UT-60, LESTEST, China.) A365 nm ultraviolet lamp (SJMAEA-SJUV4M, Shanghai, China) was used to test the chemical stability of the coatings. The adhesion strength of the coatings on the various substrates was obtained by means of a pull adhesion tester (XH-M, Beijing, China).

Example 1 preparation of colored coating solution and colored super-hydrophobic coating

Generally, 0.6g, 0.4g, 0.3g and 0.7g of cellulose, chitosan, zeolite and PTFE were weighed and dispersed in a mixed solution of 30mL of anhydrous ethanol and 5mL of acetic acid. Then, a certain dye was added to the above solution and stirred at 60 ℃ for 6h to obtain a colored suspension. Thereafter, 800 μ L of FAS was added dropwise to the above solution, and stirred for 2 hours. Then, 2mL of AS was added dropwise and continuously stirred for 3 hours to finally obtain a color coating solution. Various substrates such as glass, aluminum sheets, tiles and wood were coated by spraying a colored coating liquid (2mL) from a distance of 10cm in the vertical direction using a spray gun. The cotton fabric may be dipped into the coloured suspension. Finally, a colour coating was obtained by heating the coating material in an oven at 80 ℃ for 5h, then drying at 110 ℃ for 30 min.

Notably, MO, MB, Rh B serve as the three primary dyes. The total mass of dye was kept at 0.03 g. By adjusting the mass ratio of the dyes, different colors can be obtained. Furthermore, a color gradient can be obtained by adjusting the dye concentration while keeping the dye mass ratio constant.

During the dyeing process, MO, MB and Rh B are used as the three main dyes. The ternary phase diagram of the dye mixture ratio can be obtained by adjusting the mass ratio of the three dyes (fig. 2). The three corners of the diagram (points A-C) represent the pure phases of MO, MB and Rh B, respectively, i.e. the total mass of the added single dye is 0.03 g; points D-L represent the mixing mass ratio of any two dyes, such as point D represents MB: the mass ratio of Rh B is 1:1, namely the addition amount is 0.015g respectively; the point M-P represents the mixed mass ratio of the three dyes, such as point M represents MB: MO: rh B was added in a mass ratio of 1:1:1, i.e., in an amount of 0.01g each.

For example, a colored superhydrophobic coating can be prepared according to the dye ratio from point a to point P in a ternary phase diagram (fig. 3). During the dyeing process of the coating preparation, we succeeded in obtaining the following colors by adding the ratio of dyes at points a-P. It can be seen that the coatings prepared from points a-C exhibit the three primary colors of the dye, and points D-P exhibit colors different from the original, e.g., points F, H and O exhibit green, violet, and brown, respectively, demonstrating the feasibility of using trichromatic dithering to obtain a multi-colored coating.

EXAMPLE 2 investigation and characterization of colored Superhydrophobic coatings

A series of coatings with a color gradient can be obtained by varying the total mass of the dyes while keeping the mass ratio constant, according to the method of example 1. For example, by maintaining a mass ratio of 1: 0(RhB, point a), 1: 0(MB, point C), 1:1 (MB: MO, Point F), 1: 4 (MO: RhB, point I) a gradation of four colors of pink, blue, green and red can be obtained (FIG. 4).

Unlike the colors produced by the interaction of particles with light waves in other documents, or by femtosecond electroplating on special metal surfaces, the color of our coatings is obtained by simple physical adsorption, without being limited by the materials used. In other words, micro-nano particles such as zeolite are directly used as an adsorbent, so that the dye in the solvent can be adsorbed on the surface of the porous material. Different colors can be obtained by absorbing different dyes. It is worth mentioning that the microporous structure and the active hydroxyl groups on the zeolite have certain promotion effect on the combination effect of the particles and the dye and the super-hydrophobic modification.

To confirm the adsorption mechanism, the pore size distribution and specific surface area of the primary micro-nano particles were measured by Brunauer-Emmett-teller (bet) and Barrett-Joyner-halenda (bjh) methods. As shown in FIGS. 5(a-b), the results show that N is₂The adsorption-desorption isotherms showed a clear hysteresis curve, indicating that the samples were predominantly mesoporous. In addition, the pore size distribution of the micro-nano particles is relatively wide, and the micro-nano particles belong to gaps among the particles. This proves that the micro-nano particles have certain adsorption capacity.

On this basis, three primary color dyes with a certain concentration were adsorbed by the particles and the change in absorption intensity before and after absorption was characterized (fig. 6). It can be seen that the absorbance of Rh B, MO and MB decreases significantly at the wavelengths of 554nm, 464nm and 664nm, demonstrating that the particles have a significant adsorption of the dye. In the production process of the color paint, a certain color can be obtained by selecting a dye proportion in the ternary phase diagram. At the same time, various color gradients can be obtained by adjusting the total mass of the dyes, which enhances the selectivity and diversity of the coating in color.

The Water Contact Angle (WCA) of all the multi-color coatings and coatings of different color gradients was greater than 155 ° (fig. 7-8), indicating that the coatings had excellent superhydrophobicity.

In addition, the apparent surface free energy of the coating was calculated according to the Owens-Wendt method. As shown in Table 2, the apparent surface free energy of the coating was about 21.94mN m^-1And the coating is proved to have good liquid repellency.

To further characterize the superhydrophobicity of the coating, we calculated the apparent surface free energy of the coating according to the Owens-Wendt method. The calculation results and process are as follows:

table 1 contact angle data and calculated apparent surface free energy of the coating

Owens-Wendt developed a method for measuring the surface energy of a solid body consisting of dispersion forces and/or hydrogen bonds, which can be written as equation [1]:

in the formula, superscripts d and p are respectively a dispersion force component and a polar component. Young's equation can be written as equation [2 ]:

in the formula, T_SV,T_SL and T_LVSolid-gas, solid-liquid, liquid-gas interfacial energies, respectively; θ is the equilibrium contact angle of the liquid on a smooth surface on the three-phase contact line. Thus, the relationship between surface energy and interfacial energy can be written as equation [3 ]]:

The standard solutions for the Owens-Wendt method were methanol and cyclohexane, and therefore, the above was calculated

And

the surface energy can be obtained. The apparent surface free energy of the coating is about 21.94mN m^-1。

Through the tests, we can prove that various colorful super-hydrophobic coatings are successfully prepared, and the coatings not only have bright colors, but also have excellent super-hydrophobicity. Next we will select one of the coatings to explore its surface morphology and chemical composition.

To illustrate the morphology and composition of the coating, the MO dyed supersize of example 1 was chosenThe hydrophobic coating served as a model to allow a thorough analysis of the coating. SEM images at different magnifications revealed micro/nano-sized protrusions formed from particles of cellulose, chitosan, zeolite and PTFE (fig. 9a-c), which provided the necessary roughness structure for structuring superhydrophobic surfaces. The EDX spectra also show that all elements, including N, Si, F, Al, S and Na elements, are uniformly distributed on the surface of the coating (fig. 10 a-F). Furthermore, the XPS spectra of the coatings (fig. 11) showed that the two significant components at 689.2eV and 688.1eV were attributed to CF decomposed from the F1s peak₂And CF₃A key. These results indicate that the F elements from FAS and PTFE are uniformly distributed on the coating surface, further enhancing the superhydrophobicity of the coating.

The adhesion strength of the coating is equally important as the superhydrophobicity, which is an important indicator for evaluating the excellent performance of the coating. Generally, the adhesion strength depends on the polar group of the coating, but the polar group consumes the hydrophobicity of the coating. In this work, a silane coupling agent AS was used AS an adhesive to enhance the bond strength of the coating to the substrate. Si-O-CH through AS AS shown in FIG. 12₃The active Si-OH obtained by hydrolysis will condense with-OH on the substrate surface to form-Si-OM (M is the surface of a different substrate), while the Si-OH groups between AS molecules will also condense and polymerize to form a "layer" -like network structure. We define a "layer" like network structure AS an "AS anchoring layer", that is, the coating is firmly embedded into the substrate like a rivet. -NH of AS₂and-NH-groups can interact with oxygen and fluorine on the micro-nano particles to generate hydrogen bonds. In addition, multiple hydrogen bonds are formed between AS and FAS and the particles in the matrix coating, further enhancing the strength of the coating. By the above dual action, the coating can be highly adhered to various substrates with good robustness.

To verify the presence of the "AS anchoring layer", cross-sectional SEM microscopy characterization was performed. As shown in fig. 13, in the region near the substrate, the Si and N elements were uniformly distributed in the anchor layer, but the F element was hardly observed. This not only illustrates the surface migration of the F element that contributes to the superhydrophobicity of the coating, but also confirms the presence of the anchoring layer. SEM images of the coating at different magnifications showed that the micro-nano particles adhered tightly and uniformly to the substrate and showed good adhesion between the coating and the substrate (fig. 14).

After that, the suitability and the adhesive strength of the coatings on different substrates were investigated. In fig. 15, colored superhydrophobic coatings are applied on various substrates such as cotton fabric, wood and ceramic tiles. When different water droplets, cola, tea and fruit juice, were placed on the coated substrate, respectively, all droplets were spherical, indicating superhydrophobicity. To demonstrate high bond strength, peel tests were performed on coated cotton fabrics, glass, aluminum sheets, wood and ceramic tiles. Every 5 peels is defined as one peel cycle. After 20 peel cycles, the WCA on the coated substrate dropped from about 160 ° to about 150 °, confirming the strong adhesion and excellent superhydrophobicity of the coating on the different substrates (fig. 16).

In order to more accurately characterize the bond strength between the coating and the substrate, we classified the substrates as soft and hard. The soft base material comprises cotton fabric and filter paper; hard substrates include glass, wood, ceramic tiles and metal sheets (aluminum sheets, iron sheets, etc.). For soft substrates, a 15cm x 12cm scrub test of dip-coated cotton fabric was performed (fig. 17). Every 5 seconds is defined as a kneading cycle. After 100 cycles, the coated cotton fabric still had water repellency (water repellency is characterized by contact angle, and the contact angle magnitude is characterized by the contact angle test of fig. 17) and no significant particle shedding. For the hard substrate, the adhesive strength was measured by a pull adhesion tester. As shown in FIG. 18, the adhesion force between the coating and the wood, aluminum sheet, ceramic tile and glass substrate was 0.800MPa, 1.334MPa, 1.500MPa and 1.522MPa, respectively. Only a small amount of flaking coating was seen on the substrate, fully demonstrating its strong adhesive strength. Therefore, these results not only indicate that the superhydrophobic coating can adhere to various substrates with good robustness, but also demonstrate that the coating material can be obtained by various methods such as dip coating, spray coating, and the like.

Mechanical and chemical stability is crucial for materials used for a long time. Therefore, to evaluate the overall durability of the colored superhydrophobic coating, MO-dyed glass substrates were selected for a series of evaluations. For the sandpaper abrasion test, the coating on the glass substrate was placed face down on 800cW sandpaper weighing 200g, and each 10cm was defined as the abrasion cycle. After a wear distance of 40m, the coating still exhibited superhydrophobicity with WCA greater than 150 ° (fig. 19). SEM images (fig. 20) show that the coating was tightly bonded to the substrate before the abrasion resistance test was performed. After the abrasion resistance test, although the surface morphology was slightly changed, the superhydrophobicity was hardly changed. For the water impact test, the coated glass was placed at a vertical distance of 10cm from the spray gun, and the water impact speed was 14.6m/s under a water pressure of 200kPa (FIG. 21). After 20min of water impact, the color and superhydrophobicity of the coating did not change significantly, indicating that the coating had excellent water resistance.

In addition to mechanical stability, the chemical stability of the coatings was also evaluated by acid, alkali and salt corrosion and uv irradiation. As shown in fig. 22, different acid, base and salt droplets were deposited on the coated glass, measuring WCA every 5 min. The WCA still exceeded 150 after 30 min. Also, the coating can withstand other droplets with different pH values (fig. 23). The salt resistance of the coating was further investigated by a salt spray test. After 24 hours of salt spray testing, the surface of the original aluminum plate was severely corroded, while the entire surface of the MO superhydrophobic coating was not corroded and there was no significant change in color or superhydrophobicity, indicating that the coating has excellent salt resistance and shows great application potential in marine protection (fig. 24). Furthermore, there was little change in WCA and color of the MO-dyed coating after exposing the coated glass to 365nm UV light for 300min, indicating that the coating did not fade readily and exhibited significant UV resistance upon UV exposure (FIG. 25).

The simple application of the colored super-hydrophobic coating in real life is further provided in consideration of the comprehensive advantages of the colored super-hydrophobic coating in the aspects of wettability, substrate applicability, mechanical and chemical stability. First, suspensions of different colors are used as pigments. Various patterns were obtained by drawing with a paintbrush on the original canvas, paper, wood and ceramic. As shown in FIGS. 26a-d, "lotus" on canvas, "morning glory" on paper, "ancient Chinese clothing" on forest and "colorful ceramics" show vivid colors and vivid appearances. It can be seen that the water droplets stood on the coating surface in a spherical state, indicating that all the drawn patterns showed excellent water repellency. This work shows that colored superhydrophobic coatings can also be applied to substrates like pigments. Therefore, the colored super-hydrophobic coating is expected to be used as a novel antifouling coating for painting on various substrates, and has great application potential in art repair.

EXAMPLE 3 preparation of coating solution and Superhydrophobic coating

Otherwise, the composition of the superhydrophobic coating was investigated as in example 1. Except that the dye is not included, and the preparation method does not include the process of preparing the dye into a suspension.

In the manufacturing process of the super-hydrophobic coating, a multi-stage roughness structure and a multi-fluorination method are adopted. Micro-nano particles with the micron/nano sizes of 25 mu m, 400 plus 800nm, 10 mu m and 100nm respectively are used for constructing a multistage coarse structure; mixing to remove certain components was tested. For example, a certain component was removed under the conditions of the optimum ratio (cellulose/chitosan/zeolite/PTFE/FAS/AS-0.6 g/0.4g/0.3g/0.7 g/800. mu.L/2 mL), and the results are shown in Table 2.

Table 2 investigation of the different components.

As can be seen from table 2, FAS provides a lower surface energy, and WCA is only 78 ° without added FAS. The micro-nano particles play a role in providing different roughness in the preparation of the coating, have no roughness without adding the particles, and are difficult to achieve a hydrophobic state only by means of 800 mu L of FAS. It is worth mentioning that PTFE not only provides roughness, but also provides fluorine chains to reduce the surface energy. The contact angles of only three micro-nano particles are less than 150 degrees, and the micro-nano particles are not in a super-hydrophobic state; the contact angle without AS was 158 ℃ but was not tacky (AS in Table 5), and could not be applied to a substrate, and had no practical value.

As can be seen from Table 2, the hydrophobicity of the coating layer without the dye was also good, and since the quality of the added dye was controlled to 0.3g, the hydrophobicity of the colored coating layer after the dye was added was not different from that of the coating layer without the dye, and the addition of the dye did not affect the hydrophobicity.

Example 4

The other example is the same as example 3 except that FAS provides low surface energy and the ratio of four particles of cellulose, chitosan, zeolite and PTFE is controlled to 1:1: 1:1 (keeping the total mass of the four particles at 2g), the optimum amount of FAS was obtained by adjusting the amount of added FAS, which included 65. mu.L, 325. mu.L, 585. mu.L, 800. mu.L, 900. mu.L and 1000. mu.L (in. mu.L). The data are as follows in table 3:

TABLE 3 investigation of the amount of FAS added

It can be observed that the hydrophobicity is increased and the optimal contact angle is reached at 800uL, and the size of the contact angle is basically equal to the dosage of FAS of 900 uL and 1000 uL, so that the dosage of 800uL is selected as the final dosage of FAS according to the principle of saving cost.

Example 5

Otherwise, the same as example 3, except that, while maintaining the total mass of the four particles at 2g and the optimum amount of FAS at 800uL, the ratio of cellulose (Cell-OH) to Chitosan (CS) was changed without adding another two particles, the results were as follows:

TABLE 4 investigation of cellulose and chitosan addition

The optimum ratio of cellulose to chitosan was found to be 0.6: 0.4. the ratio of cellulose to chitosan is (0.5-0.9): (0.5-0.1), all have larger contact angles.

Example 6

TABLE 5 investigation of zeolite and PTFE addition

Otherwise, the same as example 3, except that the ratio of cellulose to chitosan was 0.6, while maintaining a total mass of 2g of the four particles and an optimum amount of FAS of 800 uL: 0.4 (i.e. cellulose 0.6g, chitosan 0.4 g); the amounts of zeolite and polytetrafluoroethylene added were varied and the results are shown in Table 5. The optimum ratio of zeolite to polytetrafluoroethylene was found to be 0.3: 0.7. the ratio of zeolite to polytetrafluoroethylene is (0.2-0.4): (0.8-0.6), all have larger contact angles.

From the above examples 3 to 6, it is understood that, while keeping the total mass of the four particles at 2g, the optimum mass ratio of cellulose, chitosan, zeolite and polytetrafluoroethylene from the above examples 2 to 4 is 0.6: 0.4: 0.3:0.7. The optimum amount of FAS added was 800 uL.

Example 7

The other point is the same as that of example 3, except that the optimal mass ratio of cellulose, chitosan, zeolite and polytetrafluoroethylene is 0.6: 0.4: 0.3:0.7. The optimum amount of FAS added was 800 uL. Studying the addition order of AS; the addition of AS was first fixed at 1mL and added before and after FAS addition, respectively, to explore the effect of AS addition sequence on coating adhesion. It was shown by comparative experiments that the order of addition of AS after FAS made the coating more adherent. Therefore, the order of addition of AS is determined after FAS.

The addition of AS first leads to crosslinking of the suspension, which results in the formation of block-shaped particles with a size of around 1X 2cm, which cannot be sprayed onto the substrate and lose their properties.

Example 8

The other point is the same as that of example 3, except that the optimal mass ratio of cellulose, chitosan, zeolite and polytetrafluoroethylene is 0.6: 0.4: 0.3:0.7. The optimum amount of FAS added was 800 uL. The amount of AS was studied. Amounts of AS include 0.5mL, 1.5mL, 2mL, and 2.5 mL. The final amount was selected to be 2mL, since the adhesion of the coating gradually increased when the amount was increased from 0.5mL to 2mL, and the lyophobicity of the coating decreased when the amount was increased to 2.5 mL.

TABLE 5 investigation of AS addition

The optimal dosage ratio of the working superhydrophobic coating is obtained by determining the proportions of cellulose, chitosan, zeolite, polytetrafluoroethylene and FAS and AS through the above examples 4-8.

Example 9

The other points are the same as example 1, except that the optimal mass ratio of cellulose, chitosan, zeolite and polytetrafluoroethylene is 0.6: 0.4: 0.3:0.7. The optimum amount of FAS added was 800 uL. . The dosage of AS is 2 mL; the ratio of the dyes was investigated.

Methylene blue, methyl orange and rhodamine B are used as three main dyes, and an infinite number of colors can be obtained by using a three-primary-color dyeing method.

In the dyeing process, in order to obtain various colors, methyl orange, methyl blue and rose bengal are used as three primary colors, and a single dyeing method and a mixed dyeing method are used in parallel to obtain the following dyeing processes:

(1) maintaining the total mass of dye added at 0.03g, a yellow (or blue/red) suspension can be obtained by adding a single methyl orange (or methyl blue/rose bengal) dye.

(2) The total mass of the added dyes was kept at 0.03g, two or three of them were added, and suspensions of different colors could be obtained by adjusting the mass ratio of the two or three dyes.

(3) Selecting certain color proportion, keeping the mass ratio of the dye unchanged, and reducing the total mass of the dye to obtain the suspension with different color gradients.

In summary, a series of colored superhydrophobic coatings based on cellulose and chitosan can be adhered to various substrates. The color of these coatings can be obtained by simply controlling the ratio and concentration of the three primary dyes. The colored super-hydrophobic coating can be highly adhered to soft and hard substrates (glass, aluminum sheets, wood, cotton fabrics and ceramic tiles) by spraying, dip coating, drawing and other methods. The super-hydrophobic coating has excellent mechanical and chemical stability, and can bear abrasive paper abrasion, adhesive tape stripping circulation, salt spray test, ultraviolet irradiation and the like. In addition, the paint is also used as a novel pigment for painting on different substrates. The super-hydrophobicity and environmental durability of the coating can extend the preservation time of the artwork. Therefore, the colored super-hydrophobic coating is expected to show wide application prospect in maintenance of artwork or process decoration design.

Claims

1. A preparation method of a color coating liquid comprises the following steps:

3) FAS was added dropwise to the above solution and stirred for 1-3 hours;

2. The method for preparing the colored coating liquid according to claim 1, wherein in the step 1), the mass ratio of the cellulose, the chitosan, the zeolite and the PTFE is (1-9): (9-1): (1-9): (9-1). More preferably, the mass ratio of the cellulose to the chitosan in the step 1) is (4-6): (6-4); the mass ratio of the zeolite to the PTFE is (2-4): (8-6).

The micro-nano particles can achieve good effects by selecting three roughness of 8-30 mu m, 80-120nm and 400-800nm, or selecting four roughness of 5-15 mu m, 20-30 mu m, 80-120nm and 400-800 nm.

3. The method for preparing a color coating liquid according to claim 1, wherein in the step 1), the volume ratio of the absolute ethyl alcohol to the acetic acid in the mixed solution of the absolute ethyl alcohol and the acetic acid is (4-8): 1; the addition amount of the mixed solution is 10-30 times of the total weight of the micro-nano particles, preferably 15-20 times.

4. The method for preparing the color coating liquid according to claim 1, wherein in the step 3), the amount of FAS added is 5-75% of the total weight of the micro-nano particles. More preferably, in the step 3), the addition amount of the FAS is 55-75% of the total weight of the micro-nano particles.

5. The method for preparing the color coating liquid according to claim 1, wherein in the step 4), the addition amount of AS is 26-130% of the total weight of the micro-nano particles. More preferably, in the step 4), the addition amount of the AS is 75-130% of the total weight of the micro-nano particles. More preferably, in the step 4), the addition amount of the AS is 90-110% of the total weight of the micro-nano particles.

6. A colored coating liquid prepared by the method according to any one of claims 1 to 5.

7. A preparation method of a colored super-hydrophobic coating comprises the following steps:

coating the coating liquid of claim 6 or the color coating liquid prepared by the method of any one of claims 1 to 5 on a substrate, heating the coating material at 70-90 ℃ for 4-6h, and drying at 100-120 ℃ for 20-40min to obtain the color coating.

8. The method for preparing a colored superhydrophobic coating according to claim 7, wherein a spray gun is used to spray a colored coating liquid (2mL) from a distance of 10cm in a vertical direction to coat various substrates such as glass, aluminum sheets, tiles and wood. The cotton fabric may be dipped into the coloured suspension.

9. The colored superhydrophobic coating prepared by the method of claim 7 or 8, wherein:

EDX spectra show that all elements, including N, Si, F, Al, S and Na elements, are uniformly distributed on the surface of the coating; XPS spectra of the coatings show that the two significant components at 689.2eV and 688.1eV are due to CF decomposed from the F1s peak₂And CF₃A key.

SEM images of the coating with different magnifications show that the micro-nano particles are tightly and uniformly adhered to the base material and show good adhesion between the coating and the base material.

10. The colored superhydrophobic coating prepared by the method of claim 7 or 8, wherein: