Photocatalyst antibacterial coating, preparation method thereof, light diffusion plate and refrigerator

Abstract

The invention discloses a photocatalyst antibacterial coating, a preparation method thereof, a light diffusion plate and a refrigerator, and belongs to the field of photocatalyst antibacterial coatings for refrigerator surface light sources. In the preparation method of the photocatalyst antibacterial coating, nitrogen-doped graphene is prepared by the following steps: preparing a graphene oxide dispersion liquid with the mass fraction of 1-3%; taking ammonia water as a nitrogen source, uniformly mixing the graphene oxide dispersion liquid and the ammonia water according to a volume fraction ratio of the ammonia water to the graphene oxide dispersion liquid of (1-2): 1, heating and reacting in a closed container, taking out the mixed liquid, cooling to room temperature, and freeze-drying to obtain powder; and heating the tubular furnace to 450-500 DEG C, putting the powder from one side of the tubular furnace, and pushing out the powder from the other side to obtain the nitrogen-doped graphene. The photocatalyst antibacterial coating is applied to the aspect of a refrigerator photocatalyst antibacterial coating, solves the technical problem that an existing photocatalyst coating cannot meet the requirements of high visible photocatalytic effect and food contact at the same time, and has the characteristics of wide spectrum, visible light response, high catalytic activity and good antibacterial performance.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalyst antibacterial coatings for refrigerator surface light sources, and in particular relates to a photocatalyst antibacterial coating, a preparation method thereof, a light diffusion plate and a refrigerator. Background Art

[0002] When the refrigerator is in use, mixing ingredients will produce odors. Pathogens carried by fresh fish, seafood, fruits and vegetables will cause the growth of bacteria inside the refrigerator and cause peculiar air odor, increasing health risks. High-end refrigerator air duct covers usually choose to use surface light sources as decoration. They have a large surface area. If a wide-spectrum photocatalyst coating with visible light response can be coated on its surface, the antibacterial and odor-removing effect inside the refrigerator will be greatly improved, giving users a better user experience. However, traditional photocatalyst coatings have problems such as narrow light response range (mainly ultraviolet light), poor visible light catalytic effect, non-permanence, and toxic substances, and cannot meet the purpose of use. Existing commonly used antibacterial coatings are usually achieved by adding Ag particle antibacterial agents or graphene, and photocatalysts usually add TiO 2 Realize that ordinary photocatalyst grade TiO 2 It does not have the visible light response effect, or the catalytic effect is poor, and cannot achieve the antibacterial and odor-removing effect, so it is not suitable for installation at surface light sources.

[0003] Chinese patent CN111910443A discloses a graphene antibacterial coating and its preparation method. The antibacterial mechanism of the coating is physical antibacterial of graphene and it does not have photocatalytic properties. Chinese patent CN113430620B discloses a metal-based graphene oxide antibacterial coating, its preparation method and its application, and specifically discloses a method for preparing a metal-based graphene oxide antibacterial coating based on magnetic field-assisted scanning jet electrodeposition, which is mainly based on metal plating and is suitable for the surface of metal substrates. Chinese patent CN116535911A discloses a visible light photocatalyst coating and its preparation method, and the photocatalyst additive uses bismuth nanomaterials.

[0004] In summary, although the prior art has conducted a lot of research on antibacterial coatings, it has not yet been possible to develop a coating that simultaneously meets the requirements of high visible light catalytic effect and photocatalytic coating that meets the requirements of food contact. Summary of the invention

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is that the existing photocatalyst coating cannot simultaneously meet the technical problem of high visible light catalytic effect and food contact. A catalyst antibacterial coating with the characteristics of wide spectrum, visible light response, high catalytic activity and good antibacterial performance, a preparation method thereof, a light diffuser plate and a refrigerator are proposed.

[0006] In order to solve the technical problem, the technical solution adopted by the present invention is:

[0007] On one hand, the present invention provides a method for preparing a photocatalyst antibacterial coating, comprising a nitrogen-doped graphene preparation step, a graphene-titanium dioxide composite photocatalyst additive preparation step, and a photocatalyst coating preparation step; the nitrogen-doped graphene preparation step comprises: preparing a graphene oxide dispersion with a mass fraction of 1-3%; using ammonia water as a nitrogen source, mixing the graphene oxide dispersion with the ammonia water in a ratio of 1-2:1 in volume fraction, heating the mixture in a sealed container for reaction, taking out the mixture, cooling it to room temperature, and freeze-drying it to obtain a powder; heating a tube furnace to 450-500° C., putting the powder in from one side of the tube furnace, and pushing the powder out from the other side to obtain the nitrogen-doped graphene.

[0008] Preferably, the nitrogen-doped graphene preparation step further comprises:

[0009] Select graphene oxide, set the speed of the homogenizer to 4000-6000 r / min, use one of sodium dodecylbenzenesulfonate and sodium p-toluenesulfonate as a dispersant, slowly add the graphene oxide into distilled water to prepare a graphene oxide dispersion with a mass fraction of 1-3%, and the dispersion is uniform and in an emulsion state;

[0010] Using ammonia water as a nitrogen source, the graphene oxide dispersion and the ammonia water are mixed in a ratio of 1-2:1 in volume fraction, the temperature is raised to 180° C. in a sealed container, and after maintaining for 45-60 minutes, the mixed solution is taken out and cooled to room temperature, and the mixed solution is poured into a freeze dryer tray for freeze drying, and the freeze-dried powder is taken out after 24 hours;

[0011] The tube furnace is heated to 450-500° C., the powder is put into the tube furnace from one side, and the powder is pushed out from the other side at a speed of 0.5 m / s to obtain nitrogen-doped graphene.

[0012] Preferably, the steps for preparing the graphene-titanium dioxide composite photocatalyst additive include:

[0013] Adding nitrogen-doped graphene to an aqueous solution containing 50% NMP to prepare a nitrogen-doped graphene NMP dispersion with a concentration of 1-5%;

[0014] Dissolve nano-photocatalyst titanium dioxide in water to obtain a nano-photocatalyst titanium dioxide aqueous solution with a mass fraction of 10-35%, mix the nano-photocatalyst titanium dioxide aqueous solution and nitrogen-doped graphene NMP dispersion at a weight ratio of 1-5:1, and disperse them in an ultrasonic disperser to obtain a dispersed mixed solution;

[0015] The dispersed mixed liquid is placed in a high-pressure homogenizer for homogenization to obtain a graphene-titanium dioxide composite photocatalyst additive.

[0016] Preferably, the graphene-titanium dioxide composite photocatalyst additive preparation step further comprises:

[0017] Under the condition of a homogenizer with a rotation speed of 4000-5000 r / min, adding nitrogen-doped graphene to a 50% NMP aqueous solution to prepare a nitrogen-doped graphene NMP dispersion with a concentration of 1-5%;

[0018] Dissolve nano-photocatalyst titanium dioxide with a particle size of 1-5 nm in water to prepare a nano-photocatalyst titanium dioxide aqueous solution with a mass fraction of 10-35%, mix the nano-photocatalyst titanium dioxide aqueous solution and nitrogen-doped graphene NMP dispersion at a weight ratio of 1-5:1, place in an ultrasonic disperser and disperse for 5-10 minutes to obtain a dispersed mixed solution;

[0019] The dispersed mixed liquid is placed in a high-pressure homogenizer and homogenized at a pressure of 20-30 MPa to obtain a graphene-titanium dioxide composite photocatalyst additive.

[0020] Preferably, the photocatalyst coating preparation step comprises:

[0021] Preparation of component A: Add water-based hydroxy acrylic resin and graphene-titanium dioxide composite photocatalyst additive into a dispersion tank, stir evenly, then add wax additive, film-forming additive, substrate wetting agent, distilled water and silane coupling agent, and finally add thickener to disperse to obtain component A;

[0022] Preparation of component B: Mix and disperse isocyanate, propylene glycol methyl ether and dipropylene glycol methyl ether to obtain component B;

[0023] The component A and the component B are mixed evenly in a mass ratio of 100:5-15, and then 6-10% of the total mass of the components A and B is added. The surface of the substrate is first treated with a PP primer liquid, and then the substrate is applied on a PP light diffusion plate by high-pressure air spraying to obtain a photocatalyst coating.

[0024] Preferably, the photocatalyst coating preparation step further comprises:

[0025] Preparation of component A: add water-based hydroxy acrylic resin and graphene-titanium dioxide composite photocatalyst additive into a dispersion tank, adjust the stirrer speed to 600 r / min, stir evenly, add wax additive, film-forming additive, substrate wetting agent, adjust the speed to 700 r / min, add distilled water and silane coupling agent, and finally add thickener, adjust the speed to 600 r / min, and disperse for 40 minutes to obtain component A;

[0026] Preparation of component B: isocyanate, propylene glycol methyl ether and dipropylene glycol methyl ether are dispersed at a speed of 800 r / min to obtain component B;

[0027] The component A and the component B are mixed evenly in a mass ratio of 100:5-15, and then 6-10% of the total mass of the components A and B is added. After the surface of the substrate is treated with a PP primer, the substrate is sprayed on the PP light diffuser plate by high-pressure air spraying at a spraying pressure of 0.1-0.5 MPa to obtain a photocatalyst coating;

[0028] After the spraying is completed, the PP light diffuser plate is dried, and the obtained coating dry film thickness is any value in the range of 30-100 μm, and the substrate light diffuser plate is mounted on the surface of the light guide plate.

[0029] Preferably, in parts by mass, the component A includes 35-45 parts of water-based hydroxy acrylic resin, 20-50 parts of graphene-titanium dioxide composite photocatalyst additive, 10 parts of wax additive, 2 parts of film-forming aid, and 0.5 parts of substrate wetting agent; the component B includes 5-20 parts of isocyanate, 2-3 parts of propylene glycol methyl ether, and 2-3 parts of dipropylene glycol methyl ether.

[0030] The present invention also provides a photocatalytic antibacterial coating prepared by the preparation method of the photocatalytic antibacterial coating according to any of the above technical solutions, wherein the photocatalytic antibacterial coating comprises nitrogen-doped graphene, wherein the number of layers of the nitrogen-doped graphene is 2-4 and the particle size is 5-10 nm.

[0031] Another aspect of the present invention provides a light diffuser plate, the surface of which is covered with the photocatalyst antibacterial coating described in the above technical solution.

[0032] The present invention also provides a refrigerator, comprising the light diffusion plate described in the above technical solution.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention provides a method for preparing a photocatalyst antibacterial coating, wherein graphene is modified by nitrogen doping and composited with nano titanium dioxide, the high conductivity of graphene is utilized to improve the catalytic activity of titanium dioxide, and a photocatalyst coating additive is prepared. When the additive is added to the coating, the prepared photocatalyst coating has the characteristics of a wide spectrum and visible light response;

[0035] The present invention also provides a light diffuser plate, which forms an antibacterial coating on the surface of the surface light source light diffuser plate through spraying, roller coating and other processes. Under the irradiation of the surface light source, a catalytic reaction occurs on the coating surface to achieve antibacterial and odor reduction effects. DETAILED DESCRIPTION

[0036] The technical scheme in the specific embodiment of the present invention is described in detail and completely below. Obviously, the described embodiment is only a part of the specific implementation of the overall technical scheme of the present invention, rather than all implementations. Based on the overall concept of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention.

[0037] On one hand, the present invention provides a method for preparing a photocatalyst antibacterial coating, comprising a nitrogen-doped graphene preparation step, a graphene-titanium dioxide composite photocatalyst additive preparation step, and a photocatalyst coating preparation step; the nitrogen-doped graphene preparation step comprises: preparing a graphene oxide dispersion with a mass fraction of 1-3%; using ammonia water as a nitrogen source, mixing the graphene oxide dispersion with the ammonia water in a ratio of 1-2:1 in volume fraction, heating the mixture in a sealed container for reaction, taking out the mixture, cooling it to room temperature, and freeze-drying it to obtain a powder; heating a tube furnace to 450-500° C., putting the powder in from one side of the tube furnace, and pushing the powder out from the other side to obtain the nitrogen-doped graphene. The preparation method of the photocatalyst antibacterial coating is to modify the graphene by nitrogen doping, and to compound it with nano titanium dioxide, and to utilize the high conductivity of the graphene to improve the catalytic activity of titanium dioxide, and to prepare a photocatalyst coating additive. When the additive is added to the coating, the prepared photocatalyst coating has the characteristics of wide spectrum and visible light response. The present invention specifically defines the preparation method of nitrogen-doped graphene, because the nitrogen doping rate of the nitrogen-doped graphene obtained by the nitrogen doping method can reach 8-10%, the nitrogen atom directly replaces C and enters the graphene lattice, and can be connected with hydroxyl or amine group. After nitrogen doping, high-temperature reduction is carried out in a high-temperature tube furnace, and the hydroxyl and carboxyl groups at the edge of the original graphene are reduced to carbon dioxide and water, which can further increase the surface area and conductivity of the graphene. The preparation of the existing nitrogen-doped graphene is to first reduce the graphene oxide with hydrazine hydrate, and then graft the functional group with hydroxyl on the surface of the reduced graphene oxide through a diazo addition reaction on the reduced graphene surface, which is not a nitrogen doping reaction in essence. Furthermore, the graphene oxide of the present invention is selected from graphene oxide prepared by freeze-drying method, the nitrogen source is ammonia water, and the graphene oxide is directly doped with nitrogen, so that the graphene oxide has higher activity. The present invention further defines the use of nano-photocatalyst titanium dioxide and nitrogen-doped graphene prepared by the above preparation method to compound to obtain a graphene-titanium dioxide composite photocatalyst additive, because graphene has extremely high conductivity. In the nitrogen-doped graphene / titanium dioxide system, the nitrogen-doped graphene improves the electron conduction efficiency, so that the photogenerated carriers of titanium dioxide are conducted to the graphene surface, thereby reducing the recombination efficiency of the electron-hole pairs of titanium dioxide and improving the photocatalytic efficiency; high-temperature reduced graphene oxide has a very large specific surface area and a strong adsorption force, adsorbs molecules or bacteria to be degraded on the graphene surface, and reacts with the photogenerated carriers transferred on its surface to form free radicals and active oxygen. Therefore, in the composite system, graphene serves as a carrier of the photocatalytic reaction, which greatly improves the efficiency of the photocatalytic reaction; in addition, the surface of the nitrogen-doped graphene prepared in this scheme cannot form a large π bond, but can form a Ti-OC bond with nano-titanium dioxide, thereby increasing the valence band width of titanium dioxide, reducing the band gap width, and increasing the visible light absorption rate.

[0038] In a preferred embodiment, the nitrogen-doped graphene preparation step further comprises: selecting graphene oxide, setting the speed of the homogenizer to 4000-6000 r / min, using one of sodium dodecylbenzenesulfonate and sodium p-toluenesulfonate as a dispersant, slowly adding the graphene oxide to distilled water to obtain a graphene oxide dispersion with a mass fraction of 1-3%, and the dispersion is uniform and emulsified; using ammonia water as a nitrogen source, and mixing the graphene oxide dispersion with a volume fraction of ammonia water: graphene oxide dispersion of 1-3%. Mix the graphene oxide dispersion and the ammonia water in a ratio of 2:1, heat to 180°C in a sealed container, keep for 45-60 minutes, take out the mixed solution and cool to room temperature, pour the mixed solution into the freeze dryer tray, freeze dry, and take out the freeze-dried powder after 24 hours; heat the tube furnace to 450-500°C, put the powder in from one side of the tube furnace, and push the powder out from the other side at a speed of 0.5m / s to obtain nitrogen-doped graphene. It can be understood that the speed of the mass emulsifier can also be 4500r / min, 5000r / min, 5500r / min and any point value within the range; the mass fraction of the graphene oxide dispersion can also be 2%, and the tube furnace can also be heated to 460°C, 470°C, 480°C, 490°C and any point value within the range.

[0039] In a preferred embodiment, the preparation steps of the graphene-titanium dioxide composite photocatalyst additive include: adding nitrogen-doped graphene to a 50% NMP aqueous solution to prepare a nitrogen-doped graphene NMP dispersion with a concentration of 1-5%; taking nano-photocatalyst titanium dioxide and dissolving it in water to prepare a nano-photocatalyst titanium dioxide aqueous solution with a mass fraction of 10-35%, mixing them in a weight ratio of 1-5:1 of nano-photocatalyst titanium dioxide aqueous solution: nitrogen-doped graphene NMP dispersion, and dispersing them in an ultrasonic disperser to obtain a dispersed mixed solution; placing the dispersed mixed solution in a high-pressure homogenizer for homogenization to obtain a graphene-titanium dioxide composite photocatalyst additive. The preparation step of the graphene-titanium dioxide composite photocatalyst additive further comprises: adding nitrogen-doped graphene to a 50% NMP aqueous solution under the condition of a homogenizing emulsifier speed of 4000-5000 r / min to prepare a nitrogen-doped graphene NMP dispersion with a concentration of 1-5%; dissolving nano-photocatalyst titanium dioxide with a particle size of any value between 1-5 nm in water to prepare a nano-photocatalyst titanium dioxide aqueous solution with a mass fraction of 10-35%, mixing the nano-photocatalyst titanium dioxide aqueous solution: nitrogen-doped graphene NMP dispersion at a weight ratio of 1-5:1, placing in an ultrasonic disperser for dispersion for 5-10 minutes to obtain a dispersed mixed solution; placing the dispersed mixed solution in a high-pressure homogenizer, homogenizing it at a pressure of 20-30 MPa to obtain a graphene-titanium dioxide composite photocatalyst additive.

[0040] In a preferred embodiment, the photocatalyst coating preparation steps include: preparation of component A: adding water-based hydroxy acrylic resin and graphene-titanium dioxide composite photocatalyst additives into a dispersion tank, stirring evenly, adding wax additives, film-forming additives, substrate wetting agents, adding distilled water and silane coupling agents, and finally adding thickeners to disperse to obtain component A; preparation of component B: taking isocyanate, propylene glycol methyl ether, and dipropylene glycol methyl ether and mixing and dispersing to obtain component B; the component A and the component B are evenly mixed in a mass ratio of 100:5-15, and then adding 6-10% water of the total mass of the component A and the component B, first treating the surface of the substrate with a PP primer liquid, and then applying it on the PP light diffusion plate by high-pressure air spraying to obtain a photocatalyst coating. The photocatalyst coating preparation step further includes: preparation of component A: adding water-based hydroxy acrylic resin and graphene-titanium dioxide composite photocatalyst additive into a dispersion tank, adjusting the stirrer speed to 600r / min, stirring evenly, adding wax additive, film-forming additive, substrate wetting agent, adjusting the speed to 700r / min, adding distilled water and silane coupling agent, and finally adding thickener, adjusting the speed to 600r / min, and dispersing for 40min to obtain the component A; preparation of component B: taking isocyanate, propylene glycol methyl ether, and dipropylene glycol methyl ether at a speed of 800 r / min, disperse to obtain component B; the component A and the component B are evenly mixed in a mass ratio of 100:5-15, and then 6-10% of the total mass of the component A and the component B is added, and the surface of the substrate is first treated with a PP primer liquid, and then a high-pressure air spraying method is used on the PP light diffuser plate, and the spraying pressure is 0.1-0.5 MPa to obtain a photocatalyst coating; after the spraying is completed, the PP light diffuser plate is dried, and the obtained coating dry film thickness is any value in the range of 30-100 μm, and the substrate light diffuser plate is installed on the surface of the light guide plate.

[0041] Regarding the above steps for preparing the photocatalyst coating, it should be noted that the water-based graphene used in the present invention is nitrogen-doped graphene, and the N atom can be connected to a hydroxyl group or an amine group. The presence of a hydroxyl group improves the dispersibility of graphene in aqueous solution, and has good homogeneity with the water-based coating, avoiding agglomeration. The last step in the photocatalyst slurry preparation process is to prepare the graphene-titanium dioxide photocatalyst additive. The solvent is in the form of NMP+water, and at the same time, it has been subjected to high-pressure homogenization. The graphene-titanium dioxide mixture is stable and has good compatibility with the water-based coating system.

[0042] In a preferred embodiment, the component A includes 35-45 parts of water-based hydroxy acrylic resin, 20-50 parts of graphene-titanium dioxide composite photocatalyst additive, 10 parts of wax additive, 2 parts of film-forming aid, and 0.5 parts of substrate wetting agent, by mass; the component B includes 5-20 parts of isocyanate, 2-3 parts of propylene glycol methyl ether, and 2-3 parts of dipropylene glycol methyl ether.

[0043] The present invention also provides a photocatalytic antibacterial coating prepared by the preparation method of the photocatalytic antibacterial coating according to any of the above technical solutions, wherein the photocatalytic antibacterial coating comprises nitrogen-doped graphene, wherein the number of layers of the nitrogen-doped graphene is 2-4 layers and the particle size is 5-10 nm. The antibacterial mechanism of the photocatalytic antibacterial coating includes: 1. The nitrogen-doped graphene after high-temperature reduction has a higher specific surface area, can adsorb more organic matter, and the graphene sheet structure is raised at the "defects" caused by high temperature on the surface, and the shape is like a blade, which has a cutting effect on the bacterial cell membrane; 2. The photocatalytic effect of nano-titanium dioxide; 3. The synergistic effect of nitrogen-doped graphene and titanium dioxide, graphene enhances the absorption rate of nano-titanium dioxide to visible light, and improves the photocatalytic efficiency.

[0044] Another aspect of the present invention provides a light diffuser plate, the surface of which is coated with the photocatalyst antibacterial coating described in the above technical solution. The light diffuser plate is constructed by spraying, roller coating and other processes to form an antibacterial coating on the surface of the surface light source light diffuser plate. Under the irradiation of the surface light source, a catalytic reaction occurs on the coating surface to achieve the effect of antibacterial and odor reduction.

[0045] The present invention also provides a refrigerator, comprising the light diffusion plate described in the above technical solution.

[0046] In order to more clearly and in detail introduce the photocatalyst antibacterial coating, the preparation method thereof, the light diffuser plate and the refrigerator provided by the embodiments of the present invention, the following description will be made in conjunction with specific embodiments.

[0047] Example 1

[0048] 1. Formula composition

[0049] In parts by mass, component A includes: 44.5 parts of water-based hydroxy acrylic resin, 32 parts of graphene-titanium dioxide composite photocatalyst, 10 parts of wax additive, 2 parts of film-forming additive, 0.5 parts of wetting agent, 10 parts of distilled water, 0.5 parts of thickener, and 0.5 parts of silane coupling agent; component B includes: 10 parts of isocyanate, 2 parts of propylene glycol methyl ether, and 3 parts of dipropylene glycol methyl ether.

[0050] 2. Preparation process of photocatalyst antibacterial coating

[0051] According to the mass fractions, water-based hydroxy acrylic resin and graphene-titanium dioxide composite photocatalyst additive were added to the dispersion tank, the stirrer speed was adjusted to 600 r / min, and after uniform stirring, the dispersed wax additive, film-forming additive and wetting agent were added, the speed was adjusted to 700 r / min, distilled water and silane coupling agent were added, and finally the thickener was added, and then the speed was adjusted to 600 r / min, and dispersed for 40 minutes to obtain component A;

[0052] According to the mass fraction, isocyanate resin, propylene glycol methyl ether and dipropylene glycol methyl ether are added, and dispersed at a speed of 800 r / min to obtain component B;

[0053] A:B are mixed in a weight ratio of 100:15, 6% water is added, stirred evenly and sprayed, and after spraying, it is baked in an environment of 50°C for 2 hours and then taken out.

[0054] 3. The preparation process of the above-mentioned graphene-titanium dioxide composite photocatalyst includes:

[0055] Select graphene oxide, set the speed of the homogenizer to 4000-6000 r / min, use one of sodium dodecylbenzenesulfonate and sodium p-toluenesulfonate as a dispersant, slowly add graphene oxide into distilled water to prepare a graphene oxide dispersion with a mass fraction of 1-3%, and the dispersion is uniform and in an emulsion state;

[0056] Using ammonia water as a nitrogen source, the graphene oxide dispersion and ammonia water are mixed in a ratio of 1-2:1 in volume fraction, and the temperature is raised to 180° C. in a sealed container. After maintaining for 45-60 minutes, the mixed solution is taken out and cooled to room temperature. The mixed solution is poured into a freeze dryer tray for freeze drying. After 24 hours, the freeze-dried powder is taken out;

[0057] The tube furnace is heated to 450-500°C, the powder is placed from one side of the tube furnace, and the powder is pushed out from the other side at a speed of 0.5 m / s to obtain nitrogen-doped graphene;

[0058] Under the condition of a homogenizer with a rotation speed of 4000-5000 r / min, adding nitrogen-doped graphene to a 50% NMP aqueous solution to prepare a nitrogen-doped graphene NMP dispersion with a concentration of 1-5%;

[0059] Dissolve nano-photocatalyst titanium dioxide with a particle size of 1-5 nm in water to prepare a nano-photocatalyst titanium dioxide aqueous solution with a mass fraction of 10-35%, mix the nano-photocatalyst titanium dioxide aqueous solution and nitrogen-doped graphene NMP dispersion at a weight ratio of 1-5:1, place in an ultrasonic disperser and disperse for 5-10 minutes to obtain a dispersed mixed solution;

[0060] The dispersed mixed liquid is placed in a high-pressure homogenizer and homogenized at a pressure of 20-30 MPa to obtain a graphene-titanium dioxide composite photocatalyst additive.

[0061] Example 2

[0062] 1. Formula composition

[0063] In parts by mass, component A includes: 40.5 parts of water-based hydroxy acrylic resin, 36 parts of graphene-titanium dioxide composite photocatalyst, 10 parts of wax additive, 2 parts of film-forming additive, 0.5 parts of wetting agent, 10 parts of distilled water, 0.5 parts of thickener, and 0.5 parts of silane coupling agent; component B includes: 10 parts of isocyanate, 2 parts of propylene glycol methyl ether, and 3 parts of dipropylene glycol methyl ether.

[0064] 2. Preparation process of photocatalyst antibacterial coating

[0065] According to the mass fractions, add water-based hydroxy acrylic resin and graphene-titanium dioxide composite photocatalyst additive into a dispersion tank, adjust the stirrer speed to 600r / min, stir evenly, add dispersed wax additive, film-forming additive, wetting agent, adjust the speed to 700r / min, add distilled water and silane coupling agent, and finally add thickener, then adjust the speed to 600r / min, disperse for 40min, and obtain component A;

[0066] According to the mass fraction, isocyanate resin, propylene glycol methyl ether and dipropylene glycol methyl ether are added, and dispersed at a speed of 800 r / min to obtain component B;

[0067] A:B are mixed in a weight ratio of 100:15, 6% water is added, stirred evenly and sprayed, and after spraying, it is baked in an environment of 50°C for 2 hours and then taken out.

[0068] 3. The preparation process of the above-mentioned graphene-titanium dioxide composite photocatalyst includes:

[0069] Select graphene oxide, set the speed of the homogenizer to 4000-6000 r / min, use one of sodium dodecylbenzenesulfonate and sodium p-toluenesulfonate as a dispersant, slowly add graphene oxide into distilled water to prepare a graphene oxide dispersion with a mass fraction of 1-3%, and the dispersion is uniform and in an emulsion state;

[0070] Using ammonia water as a nitrogen source, the graphene oxide dispersion and ammonia water are mixed in a ratio of 1-2:1 in volume fraction, and the temperature is raised to 180° C. in a sealed container. After maintaining for 45-60 minutes, the mixed solution is taken out and cooled to room temperature. The mixed solution is poured into a freeze dryer tray for freeze drying. After 24 hours, the freeze-dried powder is taken out;

[0071] The tube furnace is heated to 450-500°C, the powder is placed from one side of the tube furnace, and the powder is pushed out from the other side at a speed of 0.5 m / s to obtain nitrogen-doped graphene;

[0072] Under the condition of a homogenizer with a rotation speed of 4000-5000 r / min, adding nitrogen-doped graphene to a 50% NMP aqueous solution to prepare a nitrogen-doped graphene NMP dispersion with a concentration of 1-5%;

[0073] Dissolve nano-photocatalyst titanium dioxide with a particle size of 1-5 nm in water to prepare a nano-photocatalyst titanium dioxide aqueous solution with a mass fraction of 10-35%, mix the nano-photocatalyst titanium dioxide aqueous solution and nitrogen-doped graphene NMP dispersion at a weight ratio of 1-5:1, place in an ultrasonic disperser and disperse for 5-10 minutes to obtain a dispersed mixed solution;

[0074] The dispersed mixed liquid is placed in a high-pressure homogenizer and homogenized at a pressure of 20-30 MPa to obtain a graphene-titanium dioxide composite photocatalyst additive.

[0075] Comparative Example 1

[0076] 1. Formula composition

[0077] In parts by mass, component A includes: 44.5 parts of water-based hydroxy acrylic resin, 2 parts of graphene slurry, 30 parts of nano-silica aqueous solution, 10 parts of wax additive, 2 parts of film-forming additive, 0.5 part of wetting agent, 10 parts of distilled water, 0.5 part of thickener, and 0.5 part of silane coupling agent; component B includes: 10 parts of isocyanate, 2 parts of propylene glycol methyl ether, and 3 parts of dipropylene glycol methyl ether.

[0078] 2. Preparation process of antibacterial coating

[0079] According to the mass fractions, water-based hydroxy acrylic resin, graphene slurry, and silica aqueous solution were added to a dispersion tank, and the stirrer speed was adjusted to 600 r / min. After stirring evenly, the dispersed wax additive, film-forming additive, and wetting agent were added, and the speed was adjusted to 700 r / min. Distilled water and silane coupling agent were added, and finally a thickener was added. Then, the speed was adjusted to 600 r / min, and dispersed for 40 minutes to obtain component A.

[0080] According to the mass fraction, isocyanate resin, propylene glycol methyl ether and dipropylene glycol methyl ether are added, and dispersed at a speed of 800 r / min to obtain component B;

[0081] A:B are mixed in a weight ratio of 100:15, 6% water is added, stirred evenly and sprayed, and after spraying, it is baked in an environment of 50°C for 2 hours and then taken out.

[0082] Performance Testing

[0083] The coatings prepared in Examples 1 and 2 and Comparative Example 1 were tested for their performance, and the results are shown in Table 1.

[0084] Table 1 Performance test results

[0085]

[0086]

Claims

1. A method for preparing a photocatalyst antibacterial coating, characterized in that: The method comprises the steps of preparing nitrogen-doped graphene, preparing graphene-titanium dioxide composite photocatalyst additive, and preparing photocatalyst coating; the nitrogen-doped graphene preparation step comprises: A graphene oxide dispersion liquid with a mass fraction of 1-3% is prepared; using ammonia water as a nitrogen source, the graphene oxide dispersion liquid and the ammonia water are mixed in a ratio of 1-2:1 in volume fraction, and after heating in a closed container for reaction, the mixed liquid is taken out and cooled to room temperature, and freeze-dried to obtain a powder; a tube furnace is heated to 450-500° C., the powder is put into the tube furnace from one side, and the powder is pushed out from the other side to obtain nitrogen-doped graphene.

2. The method for preparing the photocatalyst antibacterial coating according to claim 1, characterized in that: The nitrogen-doped graphene preparation step further comprises: Select graphene oxide, set the speed of the homogenizer to 4000-6000 r / min, use one of sodium dodecylbenzenesulfonate and sodium p-toluenesulfonate as a dispersant, slowly add the graphene oxide into distilled water to prepare a graphene oxide dispersion with a mass fraction of 1-3%, and the dispersion is uniform and in an emulsion state; Using ammonia water as a nitrogen source, the graphene oxide dispersion and the ammonia water are mixed in a ratio of 1-2:1 in volume fraction, the temperature is raised to 180° C. in a sealed container, and after maintaining for 45-60 minutes, the mixed solution is taken out and cooled to room temperature, and the mixed solution is poured into a freeze dryer tray for freeze drying, and the freeze-dried powder is taken out after 24 hours; The tube furnace is heated to 450-500° C., the powder is put into the tube furnace from one side, and the powder is pushed out from the other side at a speed of 0.5 m / s to obtain nitrogen-doped graphene.

3. The method for preparing the photocatalyst antibacterial coating according to claim 1, characterized in that: The preparation steps of the graphene-titanium dioxide composite photocatalyst additive include: Adding nitrogen-doped graphene to an aqueous solution containing 50% NMP to prepare a nitrogen-doped graphene NMP dispersion with a concentration of 1-5%; Dissolve nano-photocatalyst titanium dioxide in water to obtain a nano-photocatalyst titanium dioxide aqueous solution with a mass fraction of 10-35%, mix the nano-photocatalyst titanium dioxide aqueous solution and nitrogen-doped graphene NMP dispersion at a weight ratio of 1-5:1, and disperse them in an ultrasonic disperser to obtain a dispersed mixed solution; The dispersed mixed liquid is placed in a high-pressure homogenizer for homogenization to obtain a graphene-titanium dioxide composite photocatalyst additive.

4. The method for preparing the photocatalyst antibacterial coating according to claim 3, characterized in that: The graphene-titanium dioxide composite photocatalyst additive preparation step further comprises: Under the condition of a homogenizer with a rotation speed of 4000-5000 r / min, adding nitrogen-doped graphene to a 50% NMP aqueous solution to prepare a nitrogen-doped graphene NMP dispersion with a concentration of 1-5%; Dissolve nano-photocatalyst titanium dioxide with a particle size of 1-5 nm in water to prepare a nano-photocatalyst titanium dioxide aqueous solution with a mass fraction of 10-35%, mix the nano-photocatalyst titanium dioxide aqueous solution and nitrogen-doped graphene NMP dispersion at a weight ratio of 1-5:1, place in an ultrasonic disperser and disperse for 5-10 minutes to obtain a dispersed mixed solution; The dispersed mixed liquid is placed in a high-pressure homogenizer and homogenized at a pressure of 20-30 MPa to obtain a graphene-titanium dioxide composite photocatalyst additive.

5. The method for preparing the photocatalyst antibacterial coating according to claim 1, characterized in that: The photocatalyst coating preparation steps include: Preparation of component A: Add water-based hydroxy acrylic resin and graphene-titanium dioxide composite photocatalyst additive into a dispersion tank, stir evenly, then add wax additive, film-forming additive, substrate wetting agent, distilled water and silane coupling agent, and finally add thickener to disperse to obtain component A; Preparation of component B: Mix and disperse isocyanate, propylene glycol methyl ether and dipropylene glycol methyl ether to obtain component B; The component A and the component B are mixed evenly in a mass ratio of 100:5-15, and then 6-10% of the total mass of the components A and B is added. The surface of the substrate is first treated with a PP primer liquid, and then the substrate is applied on a PP light diffusion plate by high-pressure air spraying to obtain a photocatalyst coating.

6. The method for preparing the photocatalyst antibacterial coating according to claim 5, characterized in that: The photocatalyst coating preparation step further comprises: Preparation of component A: add water-based hydroxy acrylic resin and graphene-titanium dioxide composite photocatalyst additive into a dispersion tank, adjust the stirrer speed to 600 r / min, stir evenly, add wax additive, film-forming additive, substrate wetting agent, adjust the speed to 700 r / min, add distilled water and silane coupling agent, and finally add thickener, adjust the speed to 600 r / min, and disperse for 40 minutes to obtain component A; Preparation of component B: isocyanate, propylene glycol methyl ether and dipropylene glycol methyl ether are dispersed at a speed of 800 r / min to obtain component B; The component A and the component B are mixed evenly in a mass ratio of 100:5-15, and then 6-10% of the total mass of the components A and B is added. After the surface of the substrate is treated with a PP primer, the substrate is sprayed on the PP light diffuser plate by high-pressure air spraying at a spraying pressure of 0.1-0.5 MPa to obtain a photocatalyst coating; After the spraying is completed, the PP light diffuser plate is dried, and the obtained coating dry film thickness is any value in the range of 30-100 μm, and the substrate light diffuser plate is mounted on the surface of the light guide plate.

7. The method for preparing the photocatalyst antibacterial coating according to claim 5, characterized in that: In parts by mass, the component A includes 35-45 parts of water-based hydroxy acrylic resin, 20-50 parts of graphene-titanium dioxide composite photocatalyst additive, 10 parts of wax additive, 2 parts of film-forming additive, and 0.5 parts of substrate wetting agent; the component B includes 5-20 parts of isocyanate, 2-3 parts of propylene glycol methyl ether, and 2-3 parts of dipropylene glycol methyl ether.

8. The photocatalyst antibacterial coating prepared by the method for preparing the photocatalyst antibacterial coating according to any one of claims 1 to 7 is characterized in that: The photocatalyst antibacterial coating comprises nitrogen-doped graphene, the number of layers of the nitrogen-doped graphene is 2-4, and the particle size is 5-10 nm.

9. A light diffuser plate, characterized in that: The surface of the light diffusion plate is covered with the photocatalyst antibacterial coating according to claim 8.

10. A refrigerator, characterized in that: The refrigerator includes the light diffuser plate according to claim 9.

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