A color-changeable water-based paint, a preparation method and application thereof

Abstract

The application discloses a variable color water-based paint and a preparation method and application thereof. The paint comprises the following components in percentage by weight: 30-50% of water-based acrylic emulsion, 1-5% of 2-hydroxyanthraquinone, 1-5% of chitosan, 0.1-3% of wetting agent, 0.1-1% of defoaming agent, 0-2% of pH regulator, 0.5-2% of dispersing agent, and the rest of water. The paint contains 2-hydroxyanthraquinone and chitosan. The hydroxyl group in the 2-hydroxyanthraquinone is located on the side of anthraquinone, the orbit of the hydroxyl group can overlap the orbit of the benzene ring, so that the hydroxyl group can form a p-p conjugation effect with the benzene ring. The chitosan is rich in amino groups and hydroxyl groups at the same time, the amino group on the chitosan can form a hydrogen bond with the carbonyl group on the 2-hydroxyanthraquinone, and the hydroxyl group on the chitosan can form a hydrogen bond with the hydroxyl group on the 2-hydroxyanthraquinone. After cross-linking, electronic transition occurs when the environmental temperature, ultraviolet light, pH or electric field intensity changes, so that the color change of the coating can be observed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coatings, and particularly relates to a water-based paint capable of changing color, and a preparation method and application thereof. BACKGROUND

[0002] Coatings are a kind of viscous liquid prepared by using resin, or oil, or emulsion as the main component, adding or not adding pigments, fillers, and corresponding additives, and using organic solvents or water as the solvent, which is coated on the surface of an object to be protected or decorated, and can form a continuous film firmly attached to the coated object. Water-based coatings use water as the solvent, and have the advantages of non-flammability, non-explosiveness, low VOC (volatile organic compound) content, low odor, etc. compared with organic solvent-based coatings, and are more in line with the current social and economic development concept of energy saving, emission reduction and environmental protection.

[0003] Acrylic emulsion is a milky white or nearly transparent viscous liquid, which is an emulsion copolymerized from pure acrylic ester monomers. It is a small-particle-size, multi-purpose and outstanding-performance emulsion suitable for various coating formulations. Water-based acrylic emulsion has good water resistance, alkali resistance and stain resistance, and has good adhesion to masonry, wood and steel surfaces. It is also widely used as a film-forming material for water-based coatings due to its zero VOC advantage.

[0004] Color-changing coatings refer to coatings that change color reversibly or irreversibly with changes in external environmental conditions, including changes in temperature, light intensity, pH, electric field strength and magnetic field strength. Color-changing coatings exhibit phenomena such as thermochromism, photochromism, acid-base color change, electrochromism and magnetochromism in response to these changes. By imparting the function of color change to coatings, the application scenarios of coatings can be enriched and the market can be broadened. Chinese Patent Application CN115093759A prepared a water-based wood paint including a main agent and a curing agent by using an acrylic dispersion as a film-forming material. The film strength was enhanced and a dense cross-linked network was formed to improve the adhesion by formula design and raw material selection, and modification and cross-linking pretreatment of the acrylic dispersion. The color of the paint was adjusted by adding color paste, but it did not have the function of color change. Chinese Patent Application CN113930115A disclosed a temperature-controlled color-changing acrylic ester coating and a preparation method thereof. The coating used a thermoreversible pigment as a color-developing material to achieve color change by one or more of the mechanisms of losing crystal water, changing crystal form and reacting with acid during heating. The acrylic ester polymer was used as the coating material to provide good film-forming property, spreading property and binding force between the thermoreversible pigment and the substrate as a medium. Chinese Patent Application CN113930115A did not explicitly specify the specific color-developing material of the thermoreversible pigment, and the temperature-induced color change range depended on the different thermoreversible pigments leading to different color change temperature ranges. SUMMARY

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a water-based paint with variable color.

[0006] Another purpose of the present application is to provide a preparation method of the water-based paint with variable color.

[0007] Still another purpose of the present application is to provide an application of the water-based paint with variable color.

[0008] The purpose of the present application is achieved by the following technical solutions:

[0009] A water-based paint with variable color comprises the following components in percentage by weight: 30-50% of water-based acrylic emulsion, 1-5% of 2-hydroxyanthraquinone, 1-5% of chitosan, 0.1-3% of wetting agent, 0.1-1% of defoaming agent, 0-2% of pH regulator, 0.5-2% of dispersing agent, and the balance of water.

[0010] Further, the water-based acrylic emulsion is a water-based fluorosilicon modified acrylic emulsion, which is prepared by the following steps:

[0011] (1) uniformly mix sodium vinyl sulfonate and distilled water, heat to 65-75℃, then add methyl methacrylate and potassium persulfate into the reaction system, and condense backflow reaction for 30-40 min to obtain a seed emulsion with blue light;

[0012] (2) add perfluorooctyl ethyl methacrylate, butyl acrylate, divinyl tetramethyl disiloxane and potassium persulfate into the reaction system of step (1), and react at 65-75℃ for 3-4 h to obtain the water-based fluorosilicon modified acrylic emulsion.

[0013] Preferably, in the preparation of the water-based fluorosilicon modified acrylic emulsion, the amount of sodium vinyl sulfonate is 0.5-2% of the total mass of methyl methacrylate, perfluorooctyl ethyl methacrylate, butyl acrylate and divinyl tetramethyl disiloxane.

[0014] Preferably, in the preparation of the water-based fluorosilicon modified acrylic emulsion, the molar ratio of methyl methacrylate to butyl acrylate is 1:(1-3).

[0015] Preferably, in the preparation of the water-based fluorosilicon modified acrylic emulsion, the molar ratio of perfluorooctyl ethyl methacrylate, butyl acrylate and vinyl triethoxy silane is 1:(1-2):(1-2).

[0016] Preferably, in step (1) of the preparation of the water-based fluorosilicon modified acrylic emulsion, the amount of potassium persulfate is 0.1-1wt% of methyl methacrylate.

[0017] Preferably, the amount of potassium persulfate used in step (2) of preparing the aqueous fluorosilicon-modified acrylic emulsion is 0.1-0.5wt% of the butyl acrylate.

[0018] Further, the wetting agent is an organic silicon wetting agent, which reduces the surface tension and improves the wetting performance and anti-cratering performance of the substrate, such as BYK-346, BYK3455, TEGO Twin 4100.

[0019] Further, the defoaming agent is one of an organic silicon defoaming agent, a polyether defoaming agent, and a polyether-modified polysiloxane defoaming agent, such as AFE-1410, TEGO 270, TEGO 810, and TEGO Airex902W.

[0020] Further, the pH regulator is at least one of an acidic substance and a basic substance.

[0021] Further, the dispersant is at least one of methyl cellulose, cellulose nanofiber, and cellulose nanocrystal.

[0022] Further, the color-changeable water-based paint further comprises at least one of carbon black, titanium dioxide, phthalocyanine green, cobalt blue, molybdenum chromium red, and iron oxide yellow.

[0023] Further, the color-changeable water-based paint further comprises at least one of a preservative, a mildewcide, and an anti-aging agent.

[0024] The preparation method of the color-changeable water-based paint comprises the following steps:

[0025] S1, dispersing a dispersant in water by ultrasonic to obtain a first mixture;

[0026] S2, adding a wetting agent, 2-hydroxyanthraquinone, and 50% of the formula amount of a defoaming agent into the first mixture and mixing by ultrasonic to obtain a second mixture;

[0027] S3, adding an aqueous acrylic emulsion, chitosan, a pH regulator, and the remaining defoaming agent into the second mixture and mixing by ultrasonic to obtain the color-changeable water-based paint.

[0028] Preferably, the frequency of the ultrasonic is 40-50 kHz, and the time is 20-40 min.

[0029] It should be noted that if the paint further comprises at least one of a pigment, a preservative, a mildewcide, or an anti-aging agent, they are all added in step S2, and the specific amount can be adjusted according to actual needs.

[0030] The application of the above-mentioned variable color water-based paint is to coat the variable color water-based paint on the surface of a substrate, and after the coating film is formed, the environmental temperature, ultraviolet light, pH value or electric field intensity is changed to realize the color change of the coating film.

[0031] The present application has the following advantages and effects relative to the prior art:

[0032] (1) The paint of the present application contains 2-hydroxyanthraquinone and chitosan. The hydroxyl group in 2-hydroxyanthraquinone is connected to the 2-position of anthraquinone, i.e. the hydroxyl group is located on the side of anthraquinone, and the orbit of the hydroxyl group can overlap with the orbit of the benzene ring, so that the hydroxyl group can form p-p conjugation effect with the benzene ring. Chitosan is rich in amino and hydroxyl groups, and the amino group on chitosan can form a hydrogen bond with the carbonyl group on 2-hydroxyanthraquinone, and the hydroxyl group on chitosan can form a hydrogen bond with the hydroxyl group on 2-hydroxyanthraquinone. After cross-linking, electron transition occurs when the environmental temperature, ultraviolet light, pH value or electric field intensity changes, so that the color change of the coating film can be observed. In addition, the addition of chitosan can also make the paint form a film better after being applied, without the need for additional film-forming aids.

[0033] (2) The present application introduces fluorine and silicon elements into the acrylic polymer to obtain a water-based fluorine and silicon modified acrylic emulsion, which can increase the surface activity of the acrylic emulsion and further improve the application performance of the paint, so that the paint has better adhesion and water and oil resistance.

[0034] (3) The cellulose dispersant used in the paint of the present application is rich in hydroxyl groups, which can better maintain the rheological property, dispersibility and stability of the paint in cooperation with other components in the paint, thereby further improving the adhesion of the paint, and the hydroxyl groups carried by the cellulose dispersant can also participate in the formation of hydrogen bonds.

[0035] (4) The paint of the present application can also contain pigments. When different colored pigments are mixed with the paint, the corresponding mixed colors can be presented, thereby further enriching the application scenarios of the paint. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0037] Figure 1 The preparation method steps of the variable color water-based paint of the present application are shown in the schematic diagram.

[0038] Figure 2The test results of the adhesion test of GB / T 9286-2021 Paint and Varnish Crosshatch Test are classified.

[0039] Figure 3 The test results of the hydrophobicity of the coating of the examples and the comparative examples of the present application.

[0040] Figure 4 The test results of the oil repellency of the coating of the examples and the comparative examples of the present application. DETAILED DESCRIPTION

[0041] The embodiments of the present application will be described clearly and completely below with reference to the examples, and the described examples are only a part of the embodiments of the present application, but not all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0042] The reagents or instruments used in the present application are not specified by the manufacturer, and are conventional products that can be purchased on the market. For process parameters not specifically mentioned, refer to conventional techniques.

[0043] Example 1

[0044] The example provides a water-based paint with variable color, which includes the following components by weight percentage: water-based acrylic emulsion 40%, 2-hydroxyanthraquinone 3%, chitosan 3%, wetting agent 1%, defoaming agent 0.5%, pH adjuster 0.5%, dispersant 1%, and deionized water 51%.

[0045] The water-based acrylic emulsion is purchased from Shenzhen Yitian Chemical Co., Ltd., and the item number is E0503.

[0046] The chitosan is purchased from Shanghai Aladdin Biochem Technology Co., Ltd., and the item number is C105803.

[0047] The wetting agent is BYK-346.

[0048] The defoaming agent is silicone defoaming agent AFE-1410, purchased from Guangzhou Suixin Chemical Co., Ltd.

[0049] The pH adjuster is sodium bicarbonate.

[0050] The dispersant is cellulose nanofiber CNF, purchased from ScienceK.

[0051] The water-based paint with variable color of the example is prepared by the following steps:

[0052] S1, cellulose nanofiber was ultrasonically dispersed in deionized water to obtain a first mixture, the frequency of the ultrasonic was 40 kHz, and the time was 20 min;

[0053] S2, BYK-346, 2-hydroxyanthraquinone and 50% of the formula amount of AFE-1410 were added to the first mixture for ultrasonic mixing to obtain a second mixture, the frequency of the ultrasonic was 40 kHz, and the time was 20 min;

[0054] S3, the water-based acrylic emulsion, chitosan, sodium bicarbonate and the remaining AFE-1410 were added to the second mixture for ultrasonic mixing to obtain the color-changeable water-based paint, the frequency of the ultrasonic was 50 kHz, and the time was 30 min.

[0055] Example 2

[0056] The color-changeable water-based paint provided by the example comprises the following components by weight percentage: water-based acrylic emulsion 50%, 2-hydroxyanthraquinone 4%, chitosan 4%, wetting agent 2%, defoaming agent 1%, pH adjuster 1%, dispersant 2%, and deionized water 36%.

[0057] The water-based acrylic emulsion was purchased from Shenzhen Yitian Chemical Co., Ltd., and the item number was E0503.

[0058] The chitosan was purchased from Shanghai Aladdin Biochem Technology Co., Ltd., and the item number was C105803.

[0059] The wetting agent was TEGO Twin 4100.

[0060] The defoaming agent was TEGO 810.

[0061] The pH adjuster was sodium bicarbonate.

[0062] The dispersant was cellulose nanocrystals CNCs, which was purchased from ScienceK.

[0063] The color-changeable water-based paint of the example was prepared by the following steps:

[0064] S1, cellulose nanocrystals were ultrasonically dispersed in deionized water to obtain a first mixture, the frequency of the ultrasonic was 45 kHz, and the time was 30 min;

[0065] S2, TEGO Twin 4100, 2-hydroxyanthraquinone and 50% of the formula amount of TEGO 810 were added to the first mixture for ultrasonic mixing to obtain a second mixture, the frequency of the ultrasonic was 45 kHz, and the time was 25 min;

[0066] S3, the water-based acrylic emulsion, chitosan, sodium bicarbonate and the remaining TEGO 810 are added to the second mixed solution for ultrasonic mixing, i.e. a color-changeable water-based paint is prepared, the frequency of the ultrasonic is 45 kHz, and the time is 40 min.

[0067] Example 3

[0068] The color-changeable water-based paint provided in the example includes the following components in percentage by weight: water-based fluorosilicon modified acrylic emulsion 45%, 2-hydroxyanthraquinone 4%, chitosan 4%, wetting agent 2%, defoaming agent 0.5%, pH regulator 0.5%, dispersant 1%, and deionized water 43%.

[0069] The chitosan is purchased from Shanghai Aladdin Biochem Technology Co., Ltd. with the item number C105803.

[0070] The wetting agent is BYK3455.

[0071] The defoaming agent is TEGO 270.

[0072] The pH regulator is sodium bicarbonate.

[0073] The dispersant is cellulose nanofiber CNF, which is purchased from ScienceK.

[0074] The water-based fluorosilicon modified acrylic emulsion used in the example is prepared by the following steps:

[0075] (1) After the sodium vinyl sulfonate and distilled water are uniformly mixed, they are heated to 70°C, then methyl methacrylate and potassium persulfate are added to the reaction system, and the condensation reflux reaction is carried out for 30 min to obtain a seed emulsion with blue light;

[0076] (2) The perfluorooctyl ethyl methacrylate, butyl acrylate, divinyl tetramethyl disiloxane and potassium persulfate are added to the reaction system of step (1), and the reaction is carried out at 70°C for 3.5 h to obtain the water-based fluorosilicon modified acrylic emulsion;

[0077] The amount of sodium vinyl sulfonate is 1% of the total mass of methyl methacrylate, perfluorooctyl ethyl methacrylate, butyl acrylate and divinyl tetramethyl disiloxane; the molar ratio of methyl methacrylate and butyl acrylate is 1:1; the molar ratio of perfluorooctyl ethyl methacrylate, butyl acrylate and vinyl triethoxy silane is 1:1:1; the amount of potassium persulfate in step (1) is 0.5wt% of methyl methacrylate; the amount of potassium persulfate in step (2) is 0.4wt% of butyl acrylate.

[0078] The color-changeable water-based paint of the example is prepared by the following steps:

[0079] S1, ultrasonic dispersion of cellulose nanofiber in deionized water to obtain a first mixture, the frequency of the ultrasonic is 40 kHz, the time is 30 min;

[0080] S2, BYK3455, 2-hydroxy anthraquinone and 50% of the formula amount of TEGO 270 are added to the first mixture for ultrasonic mixing to obtain a second mixture, the frequency of the ultrasonic is 40 kHz, the time is 30 min;

[0081] S3, the water-based fluorosilicon modified acrylic emulsion, chitosan, sodium bicarbonate and the remaining TEGO 270 are added to the second mixture for ultrasonic mixing, and the water-based paint with variable color is prepared, the frequency of the ultrasonic is 40 kHz, and the time is 40 min.

[0082] Example 4

[0083] The example provides a water-based paint with variable color, which includes the following components in percentage by weight: water-based fluorosilicon modified acrylic emulsion 35%, 2-hydroxy anthraquinone 5%, chitosan 5%, wetting agent 1%, defoaming agent 0.5%, pH regulator 0.5%, dispersant 1%, deionized water 52%.

[0084] The chitosan is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the item number is C105803.

[0085] The wetting agent is TEGO Twin 4100.

[0086] The defoaming agent is TEGO Airex902W.

[0087] The pH regulator is sodium bicarbonate.

[0088] The dispersant is cellulose nanocrystal CNCs, which is purchased from ScienceK.

[0089] The water-based fluorosilicon modified acrylic emulsion used in the example is prepared by the following steps:

[0090] (1) After mixing sodium vinyl sulfonate and distilled water, heat to 65℃, then add methyl methacrylate and potassium persulfate to the reaction system, and condense backflow reaction for 40 min to obtain a seed emulsion with blue light;

[0091] (2) Add perfluoro octyl ethyl methacrylate, butyl acrylate, divinyl tetramethyl disiloxane and potassium persulfate to the reaction system of step (1), and react at 65℃ for 4h to obtain a water-based fluorosilicon modified acrylic emulsion;

[0092] The amount of sodium vinyl sulfonate is 1.5% of the total mass of methyl methacrylate, perfluorooctyl ethyl methacrylate, butyl acrylate and divinyl tetramethyl disiloxane; the molar ratio of methyl methacrylate and butyl acrylate is 1:2; the molar ratio of perfluorooctyl ethyl methacrylate, butyl acrylate and vinyl triethoxy silane is 1:1.5:2; the amount of potassium persulfate in step (1) is 1wt% of methyl methacrylate; the amount of potassium persulfate in step (2) is 0.5wt% of butyl acrylate.

[0093] The color-changeable water-based paint of the present embodiment is prepared according to the following steps:

[0094] S1, ultrasonically disperse cellulose nanocrystals in deionized water to obtain a first mixture, the frequency of the ultrasonic is 50 kHz, and the time is 20 min;

[0095] S2, add TEGO Twin 4100, 2-hydroxy anthraquinone and 50% of the formula amount of TEGO Airex902W into the first mixture and continue ultrasonic mixing to obtain a second mixture, the frequency of the ultrasonic is 50 kHz, and the time is 20 min;

[0096] S3, add the water-based fluorosilicon modified acrylic emulsion, chitosan, sodium bicarbonate and the remaining TEGO Airex902W into the second mixture and ultrasonically mix to obtain the color-changeable water-based paint, the frequency of the ultrasonic is 50 kHz, and the time is 30 min.

[0097] Comparative Example 1

[0098] The present comparative example provides a water-based paint, which comprises the following components by weight percentage: water-based acrylic emulsion 50%, chitosan 4%, wetting agent 2%, defoaming agent 1%, pH adjuster 1%, dispersant 2%, deionized water 40%.

[0099] The water-based acrylic emulsion is purchased from Shenzhen Jitian Chemical Co., Ltd., and the item number is E0503.

[0100] The chitosan is purchased from Shanghai Aladdin Biochem Technology Co., Ltd., and the item number is C105803.

[0101] The wetting agent is TEGO Twin 4100.

[0102] The defoaming agent is TEGO 810.

[0103] The pH adjuster is sodium bicarbonate.

[0104] The dispersant is cellulose nanocrystals CNCs, which is purchased from ScienceK.

[0105] The water-based paint of the present comparative example was prepared according to the following steps:

[0106] S1, ultrasonic dispersion of cellulose nanocrystals in deionized water to obtain a first mixture, the frequency of the ultrasonic is 45 kHz, and the time is 30 min;

[0107] S2, adding TEGO Twin 4100 and 50% of the formula amount of TEGO 810 into the first mixture for continuous ultrasonic mixing to obtain a second mixture, the frequency of the ultrasonic is 45 kHz, and the time is 25 min;

[0108] S3, adding the water-based acrylic emulsion, chitosan, sodium bicarbonate and the remaining TEGO 810 into the second mixture for ultrasonic mixing to obtain the water-based paint, the frequency of the ultrasonic is 45 kHz, and the time is 40 min.

[0109] Comparative Example 2

[0110] The present comparative example provides a water-based paint, which comprises the following components by weight percentage: water-based fluorosilicon modified acrylic emulsion 35%, 2-hydroxyanthraquinone 5%, chitosan 5%, wetting agent 1%, defoaming agent 0.5%, pH regulator 0.5%, deionized water 53%.

[0111] The chitosan is purchased from Shanghai Aladdin Biochem Technology Co., Ltd., and the item number is C105803.

[0112] The wetting agent is TEGO Twin 4100.

[0113] The defoaming agent is TEGO Airex902W.

[0114] The pH regulator is sodium bicarbonate.

[0115] The water-based fluorosilicon modified acrylic emulsion used in the present comparative example is prepared according to the following steps:

[0116] (1) After mixing sodium vinyl sulfonate and distilled water, heat to 65℃, then add methyl methacrylate and potassium persulfate into the reaction system, and condense reflux reaction for 40 min to obtain a seed emulsion with blue light;

[0117] (2) Add perfluoroalkyl ethyl methacrylate, butyl acrylate, divinyl tetramethyl disiloxane and potassium persulfate into the reaction system of step (1), and react at 65℃ for 4 h to obtain the water-based fluorosilicon modified acrylic emulsion;

[0118] The amount of sodium vinyl sulfonate is 1.5% of the total mass of methyl methacrylate, perfluorooctyl ethyl methacrylate, butyl acrylate and divinyl tetramethyl disiloxane; the molar ratio of methyl methacrylate and butyl acrylate is 1:2; the molar ratio of perfluorooctyl ethyl methacrylate, butyl acrylate and vinyl triethoxysilane is 1:1.5:2; the amount of potassium persulfate in step (1) is 1wt% of methyl methacrylate; the amount of potassium persulfate in step (2) is 0.5wt% of butyl acrylate.

[0119] The water-based paint of the present comparative example was prepared according to the following steps:

[0120] S1, TEGO Twin 4100, 2-hydroxy anthraquinone and 50% of the formula amount of TEGO Airex902W were added to deionized water and ultrasonically mixed to obtain a mixed solution, the frequency of the ultrasonic was 50 kHz and the time was 20 min;

[0121] S2, the water-based fluorosilicon modified acrylic emulsion, chitosan, sodium bicarbonate and the remaining TEGO Airex902W were added to the mixed solution and ultrasonically mixed to obtain the water-based paint, the frequency of the ultrasonic was 50 kHz and the time was 30 min.

[0122] Performance test

[0123] In order to further prove the effect of the present application, the following performance tests were carried out on the paints prepared in the above examples and comparative examples:

[0124] 1. Centrifugal stability test: the prepared paint was centrifuged at 3000 rpm by a centrifuge, and the percentage of the ultraviolet absorbance after centrifugation to that before centrifugation, i.e. r value, was tested, the higher the r value, the stronger the centrifugal stability, and the test results are shown in Table 1.

[0125] 2. Adhesion test: the prepared paint was brushed on the surface of melamine board and tested according to “GB / T 9286-2021 Paints and varnishes Cross-hatch test”, and the test results are shown in Table 1.

[0126] 3. Hydrophobicity test: tested according to “GB / T 24368-2009”, and the test results are shown in Table 1. Figure 3

[0127] 4. Oleophobicity test: tested according to “GB / T 24368-2009”, and the test results are shown in Table 1. Figure 4

[0128] 5. Thermochromic test: the paint was coated on a glass substrate, the coating amount was 100g / m 2 ​​, the coating sample plate is placed in an oven and heated from 20°C to 100°C at a heating rate of 5°C / min to test the color change. It can be observed that the color of the coating corresponding to Examples 1-4 and Comparative Example 2 gradually lightens from the initial brownish yellow to light yellow with the increase of temperature; while the color of the coating corresponding to Comparative Example 1 does not change significantly with the increase of temperature.

[0129] 6. Photochromic test: the coating is applied on a glass substrate at a coating amount of 100 g / m 2 , the coating sample plate is placed in an ultraviolet light irradiation box, the wavelength of the ultraviolet light is set to 360 nm, the temperature is 40°C, the irradiation intensity is 0.6 W / m 2 , and the color change is tested after irradiation for 0-10 h. It can be observed that the color of the coating corresponding to Examples 1-4 and Comparative Example 2 gradually lightens from the initial brownish yellow to light yellow with the increase of irradiation time; while the color of the coating corresponding to Comparative Example 1 does not change significantly with the increase of irradiation time.

[0130] 7. Acid-base color change test: the coating is applied on a glass substrate at a coating amount of 100 g / m 2 , the coating sample plate is immersed in water solutions with pH values of 4, 7 and 10 respectively to test the color change. It can be observed that the color of the coating corresponding to Examples 1-4 and Comparative Example 2 changes with the change of pH value, when the coating sample plate is placed in water solutions with pH values of 4, 7 and 10 respectively, the color of the coating all lightens from the initial brownish yellow but the degree is not the same, and the color order from deep to shallow is pH value 7 > pH value 10 > pH value 4; while the color of the coating corresponding to Comparative Example 1 does not change significantly with the change of pH value of the water solution.

[0131] 8. Electrochromic test: the coating is applied on a stainless steel standard test plate at a coating amount of 100 g / m 2 , the coating sample plate is connected to an alternating power source, the power source is adjusted to 50 Hz, the output wave is a sine wave, the output voltage is 36 v, and the color change is tested after power-on for 0-3 h. It can be observed that the color of the coating corresponding to Examples 1-4 and Comparative Example 2 all lightens from the initial brownish yellow after about 10 seconds of power-on, and the color changes to light yellow after about 2 minutes of power-on, and no obvious color change is observed with the increase of power-on time.

[0132] From the test results, the water-based paint prepared in Examples 1-4 and Comparative Example 2 of the present application can change color in response to changes in environmental temperature, ultraviolet light, pH or electric field intensity, indicating that the water-based paint of the present application has a color-changing function. The water-based paint prepared in Comparative Example 1 does not have a color-changing function because it does not contain 2-hydroxyanthraquinone.

[0133] Table 1

[0134] Number Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Centrifuge stability (r) 80-90% 90-100% 80-90% 90-100% 90-100% 40-50% Adhesion rating 0 0 0 0 0 1

[0135] As shown in the data in Table 1, the water-based paints prepared in Examples 1-4 and Comparative Example 1 of the present application all have good centrifugal stability and strong adhesion, while the paint in Comparative Example 2 does not contain a cellulose dispersant and thus has poor centrifugal stability and adhesion, indicating that the cellulose dispersant can better maintain the rheological properties, dispersibility and stability of the paint, thereby further improving the adhesion of the paint. The water-based paints prepared in the examples and comparative examples of the present application all have good hydrophobic and oleophobic properties, but the paint prepared from the water-based fluorosilicon-modified acrylic emulsion has better hydrophobic and oleophobic properties than the paint prepared directly from a commercially available water-based acrylic emulsion, indicating that the water-based fluorosilicon-modified acrylic emulsion can further improve the application properties of the paint.

[0136] The above examples are preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. A water-based paint which changes color, characterized by, comprises the following components by weight percentage: water-based acrylic emulsion 30-50%, 2-hydroxyanthraquinone 1-5%, chitosan 1-5%, wetting agent 0.1-3%, defoaming agent 0.1-1%, pH adjuster 0-2%, dispersant 0.5-2%, and the balance being water; The water-based acrylic emulsion is a water-based fluorosilicon modified acrylic emulsion prepared by the following steps: (1) After mixing sodium vinyl sulfonate and distilled water, heat to 65-75℃, then add methyl methacrylate and potassium persulfate to the reaction system, and condense reflux reaction for 30-40min to obtain a seed emulsion with blue light; (2) Add perfluoroalkyl ethyl methacrylate, butyl acrylate, divinyl tetramethyl disiloxane and potassium persulfate to the reaction system of step (1), and react at 65-75℃ for 3-4h to obtain a water-based fluorosilicon modified acrylic emulsion.

2. The water-based paint according to claim 1, wherein: The amount of sodium vinyl sulfonate is 0.5-2% of the total mass of methyl methacrylate, perfluoroalkyl ethyl methacrylate, butyl acrylate and divinyl tetramethyl disiloxane; The molar ratio of methyl methacrylate to butyl acrylate is 1:(1-3); The molar ratio of perfluoroalkyl ethyl methacrylate, butyl acrylate and divinyl tetramethyl disiloxane is 1:(1-2):(1-2); The amount of potassium persulfate in step (1) is 0.1-1wt% of methyl methacrylate; The amount of potassium persulfate in step (2) is 0.1-0.5wt% of butyl acrylate.

3. The color-changeable water-based paint according to claim 1, wherein The wetting agent is an organic silicon wetting agent.

4. The color-changeable water-based paint according to claim 1, wherein The pH adjuster is at least one of an acidic substance or a basic substance.

5. The color-changeable water-based paint according to claim 1, wherein The defoaming agent is one of an organic silicon defoaming agent, a polyether defoaming agent, and a polyether modified polysiloxane defoaming agent.

6. The color-changeable water-based paint according to claim 1, wherein The dispersant is at least one of methyl cellulose, cellulose nanofiber and cellulose nanocrystal.

7. The color-changeable water-based paint according to claim 1, wherein The pigment is at least one of carbon black, titanium dioxide, phthalocyanine green, cobalt blue, molybdenum chromium red, and iron oxide yellow.

8. The color-changeable water-based paint according to claim 1, wherein At least one of a preservative, a mildewcide or an anti-aging agent is also included.

9. The method of producing the color-variable water-based paint according to claim 1, characterized by, The following steps are included: S1, ultrasonic dispersion of the dispersant in water to obtain a first mixture; S2, ultrasonic mixing of the wetting agent, 2-hydroxyanthraquinone and 50% of the formula amount of defoaming agent into the first mixture to obtain a second mixture; S3, ultrasonic mixing of the water-based acrylic emulsion, chitosan, pH adjuster and the remaining defoaming agent into the second mixture to obtain the water-based paint with variable color; The frequency of the ultrasonic is 40-50kHz and the time is 20-40min.

10. Use of the water-borne colour changeable coating according to any one of claims 1 to 8, characterized in that The water-based paint with variable color is coated on the surface of the substrate, and after the coating film is formed, the environmental temperature, ultraviolet light, pH or electric field intensity is changed to realize the color change of the paint coating.

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