Water-based optical coating for projection screen and projection screen

Abstract

The present application provides a projection screen with water-based optical paint and a projection screen. The projection screen with water-based optical paint comprises: inorganic particles, a water-based hydroxyl acrylate polymer, an isocyanate polymer, a dispersing agent and water, wherein the hydroxyl value of the water-based hydroxyl acrylate polymer is 10 mgKOH / g-20 mgKOH / g, and the glass transition temperature of the water-based hydroxyl acrylate polymer is -30 DEG C to 10 DEG C. Therefore, after the water-based optical paint composed of the present application is coated on the projection screen substrate, the adhesion between the formed coating and the substrate is good, and the coating is not easy to peel off.

Description

Technical Field

[0001] The present invention relates to the technical field of projection display, and in particular, to an aqueous optical coating for a projection screen and a projection screen. Background Art

[0002] A laser TV is a display device that uses laser projection display technology and is equipped with a dedicated projection screen, which can display broadcast TV programs or Internet TV programs. It includes two parts: a host and a dedicated anti-glare projection screen. Currently, the anti-glare projection screens supporting laser TVs mainly include Fresnel structure anti-glare screens and black grid structure anti-glare screens. Both use an optical microprism structure and a light reflection coating to reflect the light projected by the laser TV host into the viewer's eyes, and at the same time use their light absorption structure or light absorption coating to achieve the anti-glare effect. Most of the anti-glare projection screens with a black grid structure on the market are made of a thermoplastic polyurethane (TPU) substrate with a microprism structure and a light reflection coating is applied on a part of its surface.

[0003] TPU is an organic polymer material with excellent comprehensive properties, having advantages such as a wide hardness range, high mechanical strength, strong cold resistance, and easy processing, and is widely used in various fields. Since TPU itself is a good adhesive and can have a strong bonding effect with metals, the TPU substrate is not easily peeled off from the metal roller during molding, which easily causes the loss and deformation of its microprism structure, forming apparent defects such as bright and dark longitudinal stripes or dots macroscopically. In order to improve the problem of poor demolding and deformation of the TPU substrate, a release agent needs to be added to the TPU resin so that the TPU substrate can be quickly and undamagedly detached from the metal roller mold. However, the use of the release agent will cause the problem of poor adhesion of the aqueous optical coating on the TPU substrate, resulting in the easy peeling of the coating. Summary of the Invention

[0004] The present invention aims to at least partly solve one of the technical problems in the related art. For this reason, an object of the present invention is to provide an aqueous optical coating for a projection screen and a projection screen. After the aqueous optical coating is coated on the projection screen substrate, the adhesion between the formed coating and the substrate is good, and the coating is not easily peeled off.

[0005] In one aspect of the present invention, the present invention provides an aqueous optical coating for a projection screen. According to an embodiment of the present invention, the coating includes: inorganic particles, an aqueous hydroxyacrylate polymer, an isocyanate polymer, a dispersant, and water, wherein the hydroxyl value of the aqueous hydroxyacrylate polymer is 10 mgKOH / g - 20 mgKOH / g, and the glass transition temperature of the aqueous hydroxyacrylate polymer is -30°C to 10°C.

[0006] Therefore, the waterborne optical coating provided in this application comprises inorganic particles, a waterborne hydroxy acrylate polymer, an isocyanate polymer, a dispersant, and water. The addition of the dispersant can improve the dispersibility of the inorganic particles in the coating, thereby improving the smoothness of the coating. The waterborne hydroxy acrylate polymer reacts with the isocyanate polymer to form polyurethane. Furthermore, this application uses a waterborne hydroxy acrylate polymer that meets the above-mentioned hydroxyl value and glass transition temperature. On the one hand, using a waterborne hydroxy acrylate polymer within the above-mentioned hydroxyl value range allows for the reaction with the isocyanate polymer to obtain a polyurethane with a higher crosslinking density, thereby giving the coating better adhesion. Simultaneously, the waterborne hydroxy acrylate polymer within the above-mentioned hydroxyl value range reacts with the isocyanate polymer... The coating obtained by the polymer reaction has suitable hardness, can be easily rolled up, and is not easily peeled off. On the other hand, the glass transition temperature of the waterborne hydroxy acrylate polymer meets the above-mentioned range. Since its glass transition temperature is lower than room temperature, the polymer formed by the waterborne hydroxy acrylate polymer and the isocyanate polymer is in a rubber state at room temperature. This gives the coating better spreading ability, allowing it to adhere well to the surface of the projection screen substrate during application. Furthermore, the prepared coating has suitable hardness, resulting in good scratch resistance, while avoiding excessive hardness that would cause the coating to become brittle and easily peel off when the projection screen is rolled up. Therefore, when the waterborne optical coating of this application is applied to the projection screen substrate, the resulting coating has good adhesion to the substrate and is not easily peeled off.

[0007] In addition, the water-based optical coating for the projection screen according to the above embodiments of the present invention may also have the following additional technical features:

[0008] According to an embodiment of the present invention, the solid content of the waterborne hydroxy acrylate polymer is 35wt%-45wt%. Therefore, the resulting coating has good adhesion to the substrate and is not easily peeled off.

[0009] According to an embodiment of the present invention, the mass ratio of the inorganic particles, the aqueous hydroxy acrylate polymer, the isocyanate polymer, the dispersant, and the water is (45-60):(25-40):(1-2.5):(0.1-0.5):(10-25). Therefore, the resulting coating exhibits good adhesion to the substrate and is less prone to peeling.

[0010] According to embodiments of the present invention, the inorganic particles include at least one of titanium dioxide, boehmite, alumina, barium sulfate, magnesium hydroxide, silicon dioxide, and calcium carbonate. Therefore, the resulting coating exhibits good adhesion to the substrate and is less prone to peeling.

[0011] According to an embodiment of the present invention, the inorganic particles include titanium dioxide and boehmite, wherein the mass ratio of titanium dioxide to boehmite is (5-12):1. This reduces the light reflectivity of the coating and decreases its solar effect.

[0012] According to an embodiment of the present invention, the average particle size of the titanium dioxide is 200nm-400nm. This improves the light reflectivity of the coating and enhances its hiding power on the substrate.

[0013] According to an embodiment of the present invention, the boehmite particles have a hexahedral structure; the average particle size of the boehmite is 0.8 μm-1.2 μm. This reduces the light reflectivity of the coating and decreases its solar effect.

[0014] According to embodiments of the present invention, the dispersant comprises at least one of ammonium polycarboxylate dispersants, sodium polycarboxylate dispersants, ammonium polyacrylate dispersants, sodium polyacrylate dispersants, and nonionic polymer dispersants. This improves the dispersibility of inorganic particles in the coating, thereby enhancing the smoothness of the coating.

[0015] According to embodiments of the present invention, the waterborne optical coating further includes a leveling agent, said leveling agent comprising at least one of a polyether-modified organosiloxane copolymer and an acetylenic diol ethoxylate. This improves the spreading ability of the coating, thereby enhancing the adhesion between the coating and the substrate.

[0016] According to an embodiment of the present invention, the mass ratio of the polyether-modified organosiloxane copolymer to the acetylacetonate ethoxylate is (3-8):1. This improves the spreading ability of the coating, thereby enhancing the adhesion between the coating and the substrate.

[0017] According to an embodiment of the present invention, the mass ratio of the waterborne hydroxy acrylate polymer to the leveling agent is (25-40):(0.5-3). Therefore, the resulting coating exhibits good adhesion to the substrate and is less prone to peeling.

[0018] According to an embodiment of the present invention, the viscosity of the water-based optical coating is 30 mPa·s-60 mPa·s. Therefore, the resulting coating has good adhesion to the substrate and is not easily peeled off.

[0019] According to an embodiment of the present invention, the surface tension of the water-based optical coating is 20 mN / m-25 mN / m. This reduces the occurrence of problems such as edge shrinkage and pinholes in the coating.

[0020] In another aspect, the present invention provides a projection screen. According to an embodiment of the invention, the projection screen includes a substrate and a coating, the coating being disposed on at least a portion of the surface of the substrate, and the coating being prepared using the aforementioned coating material. Thus, the projection screen provided by this application, by using the aforementioned water-based optical coating material to prepare the coating, achieves better adhesion between the coating and the substrate, and the coating has suitable hardness, thereby improving the problem of easy peeling of the projection screen coating.

[0021] In addition, the projection screen according to the above embodiments of the present invention may also have the following additional technical features:

[0022] According to embodiments of the present invention, the substrate comprises at least one of a polyester-type TPU substrate or a polyether-type TPU substrate. According to embodiments of the present invention, the coating thickness is 5 μm-10 μm. Therefore, the coating exhibits excellent adhesion to the substrate.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a side cross-sectional view of a TPU substrate provided in one embodiment of the present invention;

[0026] Figure 2 This is a partial enlarged view of a projection screen provided in one embodiment of the present invention. Detailed Implementation

[0027] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0028] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0029] In one aspect of the present invention, an aqueous optical coating for a projection screen is provided. According to an embodiment of the present invention, the coating comprises: inorganic particles, an aqueous hydroxyl acrylate polymer, an isocyanate polymer, a dispersant, and water, wherein the hydroxyl value of the aqueous hydroxyl acrylate polymer is 10 mg KOH / g-20 mg KOH / g, and the glass transition temperature of the aqueous hydroxyl acrylate polymer is -30°C to 10°C.

[0030] Therefore, an aqueous optical coating for a projection screen is prepared by mixing inorganic particles, an aqueous hydroxy acrylate polymer, an isocyanate polymer, a dispersant, and water. The addition of the dispersant can improve the dispersibility of the inorganic particles in the coating, thereby improving the smoothness of the coating. The aqueous hydroxy acrylate polymer reacts with the isocyanate polymer to form polyurethane. This application uses an aqueous hydroxy acrylate polymer that meets the above-mentioned hydroxyl value and glass transition temperature. On the one hand, an aqueous hydroxy acrylate polymer with a hydroxyl value in the range of 10 mg KOH / g-20 mg KOH / g (e.g., hydroxyl values ​​can be 10 mg KOH / g, 11 mg KOH / g, 12 mg KOH / g, 13 mg KOH / g, 14 mg KOH / g, 15 mg KOH / g, 16 mg KOH / g, 17 mg KOH / g, 18 mg KOH / g, 19 mg KOH / g, 20 mg KOH / g, etc.) is used. Its reaction with the isocyanate polymer can yield a polyurethane with a high crosslinking density. This results in coatings with excellent adhesion. Furthermore, the coating obtained by reacting the waterborne hydroxy acrylate polymer with the isocyanate polymer within the aforementioned hydroxyl value range exhibits suitable hardness, allowing for good curling and preventing peeling. On the other hand, the glass transition temperature of the waterborne hydroxy acrylate polymer falls within the range of -30℃ to 10℃ (e.g., glass transition temperatures can be -30℃, -25℃, -20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, etc.). Because its glass transition temperature is lower than room temperature, the polymer formed by the waterborne hydroxy acrylate polymer and the isocyanate polymer is in a rubbery state at room temperature. This allows the coating to have excellent spreading ability, enabling it to adhere well to the projection screen substrate surface during application. It also ensures the prepared coating has suitable hardness, resulting in good scratch resistance, while preventing the coating from becoming brittle due to excessive hardness and easily peeling off when the projection screen is curled. Therefore, when the water-based optical coating of this application is applied to the projection screen substrate, the resulting coating has good adhesion to the substrate and is not easily peeled off.

[0031] In some embodiments of the present invention, the solid content of the waterborne hydroxyacrylate polymer is 35wt%-45wt%, such as 35wt%, 37wt%, 39wt%, 41wt%, 43wt%, 45wt%, etc. Therefore, the above-mentioned solid content of the waterborne hydroxyacrylate polymer allows the final waterborne optical coating to have a suitable solid content, and a coating of suitable thickness can be obtained after coating. If the solid content of the waterborne hydroxyacrylate polymer is too low, the solid content of the waterborne optical coating will be too low, resulting in a thinner coating and insufficient hiding power; if the solid content of the waterborne hydroxyacrylate polymer is too high, the synthesized particle size of the waterborne hydroxyacrylate polymer will be larger and the distribution will be uneven, making the reaction difficult to control during the preparation process.

[0032] In some embodiments of the present invention, the aqueous hydroxy acrylate polymer is prepared by emulsion polymerization using (meth)acrylate monomers and hydroxyl-containing (meth)acrylate monomers. In some specific embodiments of the present invention, the (meth)acrylate monomers may be selected from a mixture of one or more monomers selected from methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, glycidyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, glycidyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, and lauryl methacrylate.

[0033] The hydroxyl-containing (meth)acrylate monomer may be selected from one or more monomers selected from 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate.

[0034] In some embodiments of the present invention, the inorganic particles include at least one of titanium dioxide, boehmite, alumina, barium sulfate, magnesium hydroxide, silicon dioxide, and calcium carbonate. Specifically, titanium dioxide particles with a nanometer-sized particle size are selected as the white pigment, which can be more uniformly dispersed in the aqueous medium, thereby making the surface of the formed optical coating smoother, with stronger reflectivity and greater gloss. For example, the titanium dioxide particles used in this application have an average particle size of 200nm-400nm, which is about half of the visible light wavelength range (0.4μm-0.7μm). Thus, the titanium dioxide particles can have high light reflectivity, making the color of the projection screen coating appear whiter. When the particle size of titanium dioxide is less than 200nm, the transparency of titanium dioxide crystals to light will reduce the covering power of the coating; when the particle size of titanium dioxide is greater than 400nm, the larger particle size will reduce the light reflectivity of the titanium dioxide particles, resulting in a decrease in the whiteness of the coating.

[0035] Furthermore, in some embodiments of the present invention, the titanium dioxide can be anatase titanium dioxide or / and rutile titanium dioxide, preferably rutile titanium dioxide. Compared with anatase titanium dioxide, rutile titanium dioxide has a smaller and more compact unit lattice, thus exhibiting greater stability and relative density. Therefore, rutile titanium dioxide has a relatively higher refractive index (rutile titanium dioxide refractive index 2.73, anatase titanium dioxide refractive index 2.55), which can better disperse visible light and improve the gloss of the coating.

[0036] In some embodiments of the present invention, the inorganic particles include titanium dioxide and boehmite, wherein the mass ratio of titanium dioxide to boehmite is (5-12):1, for example, the mass ratio can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, etc. Thus, the addition of titanium dioxide can act as a white pigment to give the coating a white appearance, and by optimizing the particle size and crystal form of titanium dioxide, the whitening effect of titanium dioxide can be improved, resulting in a whiter coating. However, while whitening the coating, a more pronounced "sun effect" also occurs, meaning that the brightness of the part where the line connecting the human eye and the lens intersects with the screen is significantly higher than other parts of the screen, and the bright spot moves with the movement of the human eye, also giving a slightly glaring feeling. Therefore, in the embodiments of the present invention, a certain amount of boehmite is incorporated into the inorganic particles. On the one hand, boehmite can increase the surface roughness of the optical coating, achieving the purpose of exfoliation, i.e., eliminating the "sun effect." On the other hand, the particle morphology of boehmite is a hexahedral structure, which can be a parallelepiped structure or an irregular hexahedral structure. The hexahedral structure has obvious edges and corners, so a small amount of boehmite can effectively increase the surface roughness of the optical coating, reduce the "sun effect" of the coating, and thus create a good visual effect. Among them, the refractive index of boehmite is 1.63-1.67. If too much boehmite is added, it will reduce the whiteness of the water-based optical coating and affect the gain of the projection screen. If too little boehmite is added, it will not have the effect of exfoliation. Therefore, the above-mentioned mass ratio of titanium dioxide and boehmite can achieve a good exfoliation effect without affecting the whiteness of the coating, so that the visual effect of the projection screen reaches a better level.

[0037] In some embodiments of the present invention, the average particle size of boehmite is 0.8μm-1.2μm, such as 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, etc. Therefore, using boehmite with the above-mentioned particle size can effectively eliminate the "sun effect" of the coating without affecting the whiteness of the coating.

[0038] In some embodiments of the present invention, the isocyanate polymer is a hydrophilic aliphatic polyisocyanate, which allows it to mix well and uniformly in an aqueous system. In some specific embodiments of the present invention, the isocyanate polymer can be selected from products of brands such as Covestro (Germany) and Guanzhi (Guangzhou), such as Covestro XP2655, Covestro XP2487, and Guanzhi OS-9012.

[0039] In some embodiments of the present invention, the dispersant includes at least one of the following: ammonium polycarboxylate dispersant, sodium polycarboxylate dispersant, ammonium polyacrylate dispersant, sodium polyacrylate dispersant, and nonionic polymer dispersant. For example, the ammonium polycarboxylate dispersant can be PROHMON's Dispersant 5050, the sodium polycarboxylate dispersant can be SN-5040 from Nippon-Nopco (Japan) or Guangdong Nanhui sodium polycarboxylate dispersant, the ammonium polyacrylate dispersant can be SN-5027 from Nippon-Nopco (Japan), the sodium polyacrylate dispersant can be Dispersogen PL 20 from Clariant (Switzerland), and the nonionic polymer dispersant can be F4190 from Foshan Aona. This effectively improves the dispersibility of inorganic particles in the coating, thereby improving the smoothness of the coating.

[0040] In some embodiments of the present invention, the water is preferably deionized water, where the ion content is close to 0, which can improve the stability of the waterborne optical coating.

[0041] In some embodiments of the present invention, the water-based optical coating for the projection screen provided by the present invention has an inorganic particle, water-based hydroxy acrylate polymer, isocyanate polymer, dispersant and water mass ratio of (45-60):(25-40):(1-2.5):(0.1-0.5):(10-25), for example, a mass ratio of 45:25:1:0.1:10, 47:28:1.5:0.2:18, 50:30:2:0.3:20, 60:40:2.5:0.5:25, etc. Therefore, by preparing the water-based optical coating according to the above proportions, the coating can have better wetting and spreading ability, better adhesion, better adhesion between the coated layer and the substrate, and the coating has suitable thickness and hardness.

[0042] In some embodiments of the present invention, the above-mentioned waterborne optical coating may further include a leveling agent, which includes at least one of polyether-modified organosiloxane copolymer and acetylation diol ethoxylate. Thus, by adding a leveling agent, the wetting and spreading ability of the waterborne optical coating can be significantly improved. At the same time, the leveling agent also has significant defoaming and foam-suppressing effects, thereby enabling the waterborne optical coating to spread well on the surface of the projection screen substrate and improving its adhesion.

[0043] In some embodiments of the present invention, the mass ratio of the waterborne hydroxy acrylate polymer to the leveling agent is (25-40):(0.5-3), for example, the mass ratio can be 25:0.5, 25:1, 30:1, 30:3, 35:2, 35:3, 40:1, 40:2, 40:3, etc. Therefore, using the leveling agent with the above-mentioned mass ratio allows the waterborne optical coating to have relatively optimal wetting and spreading ability, and relatively optimal defoaming and foam-suppressing effects.

[0044] In some specific embodiments of the present invention, the leveling agent includes a polyether-modified organosiloxane copolymer and an acetylation glycol ethoxylate. The polyether-modified polysiloxane contains both polyether and polysiloxane in its molecular structure. The hydrophobic polysiloxane backbone provides extremely low surface tension, while the hydrophilic polyether groups provide good water solubility. The acetylation glycol ethoxylate is a highly branched, multifunctional nonionic surfactant with a hydrophobic-hydrophilic-hydrophobic structure, exhibiting good wetting and spreading properties, as well as a certain defoaming effect. Therefore, using a mixture of the polyether-modified organosiloxane copolymer and the acetylation glycol ethoxylate as a leveling agent can significantly reduce the surface tension of the waterborne optical coating, improve its wetting and spreading properties on the projection screen substrate, and also provide a certain defoaming ability, ensuring that the formed waterborne optical coating does not exhibit defects such as pinholes or edge shrinkage.

[0045] Furthermore, the mass ratio of the polyether-modified organosiloxane copolymer to the acetylenol ethoxylate in the above-mentioned leveling agent is (3-8):1, for example, the mass ratio can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, etc. Therefore, using the leveling agent with the above composition can effectively improve the wetting and spreading properties of waterborne optical coatings while also giving them good defoaming and foam-suppressing abilities. If too much polyether-modified organosiloxane is added, although the wetting and spreading properties of the waterborne optical coating are good, its defoaming and foam-suppressing abilities are poor, easily leading to defects such as pores, defects, and stringing on the surface of the waterborne optical coating. If too much acetylenol ethoxylate is added, although the defoaming and foam-suppressing abilities of the waterborne optical coating are strong, its wetting and spreading properties are average, and its leveling properties are poor, easily leading to defects such as pinholes and edge shrinkage on the surface of the waterborne optical coating. At the same time, poor leveling properties will also result in insufficient coating width and poor reflectivity. According to embodiments of the present invention, the polyether-modified organosiloxane can specifically be selected from Qingdao Baisenmao BSM11485, Sichuan Ruikaibang RianPont2903, Shanghai Huiyan HY-7608, German BYK 20990, American Momentive 7608, etc., and the ethynylene glycol ethoxylate can specifically be selected from German Evonik Dynol 604, Tianjin Hepufele superwet-360, etc.

[0046] In some embodiments of the present invention, the viscosity of the water-based optical coating is 30 mPa·s-60 mPa·s, for example, the viscosity can be 30 mPa·s, 35 mPa·s, 40 mPa·s, 45 mPa·s, 50 mPa·s, 55 mPa·s and 60 mPa·s, etc. Therefore, the water-based optical coating of the present invention has good leveling properties, and the coating can easily penetrate into the screen substrate during coating, thereby obtaining high adhesion. At the same time, the coating with the above viscosity can also obtain a coating of suitable thickness during coating, so that the visual effect of the coating reaches a better level.

[0047] In some embodiments of the present invention, the surface tension of the water-based optical coating is 20mN / m-25mN / m, for example, the surface tension can be 20mN / m, 21mN / m, 22mN / m, 23mN / m, 24mN / m, 25mN / m, etc. Therefore, the water-based optical coating of the present invention has good wettability and can effectively wet the projection screen substrate during coating, reducing the occurrence of defects such as edge shrinkage and pinholes in the coating.

[0048] In another aspect, the present invention provides a projection screen. According to an embodiment of the invention, the projection screen includes a substrate (such as...) Figure 1 (as shown) and a coating, the coating being disposed on at least a portion of the surface of the substrate, the coating being prepared using the coating described above. Thus, the projection screen (as shown) provided in this application... Figure 2 As shown in the figure, by using the aforementioned water-based optical coating to prepare the coating, the coating and the substrate have good adhesion, and the coating has suitable hardness, thereby improving the problem of easy peeling of the projection screen coating. Those skilled in the art will understand that this projection screen has all the characteristics and advantages of the aforementioned water-based optical coating, which will not be elaborated further here.

[0049] In some embodiments of the present invention, the substrate includes a TPU substrate, wherein the TPU may be a polyester-type TPU or a polyether-type TPU.

[0050] In other embodiments of the present invention, the coating thickness is 5μm-10μm, for example, the coating thickness can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc. Coatings of the above thicknesses can adhere well to the surface of the screen substrate and have good coverage of the screen substrate, thus giving the projection screen a better visual effect.

[0051] In some embodiments of the present invention, the method for preparing the water-based optical coating for the projection screen of the present invention includes:

[0052] S100: Weigh the raw materials according to the components and mass ratio of the water-based optical coating for the projection screen according to the present invention.

[0053] S200: Mix the raw materials weighed in step S100 and stir them thoroughly to obtain the water-based optical coating for the projection screen of the present invention.

[0054] In some embodiments of the present invention, a high-shear mixer is used for stirring in step S200, wherein the stirring rate is 3000 rpm to 4500 rpm and the stirring time is 1 h to 2 h. This allows the components in the water-based optical coating to be thoroughly and uniformly mixed, and the inorganic particles in the components to be uniformly dispersed in the water-based system. A uniformly dispersed water-based optical coating results in a more uniform light reflectivity on the prepared coating surface, thereby further improving the visual effect of the projection screen.

[0055] In some embodiments of the present invention, the method for preparing a projection screen using the water-based optical coating of the present invention includes:

[0056] S300: Provide a substrate and perform a matte finish on the substrate.

[0057] In some embodiments of the present invention, the matte finish can be formed during the substrate production process, such as by using a matte roller for embossing, or it can be a surface treatment after substrate production, such as sandblasting, corona treatment, or primer coating on the substrate surface. Applying a matte finish to the substrate can increase the roughness of the substrate surface, thereby increasing the adhesion of the water-based optical coating to the substrate surface and improving the adhesion of the coating after drying.

[0058] S400: Coat at least a portion of the surface of the substrate with the water-based optical coating of the projection screen of the present invention.

[0059] In some embodiments of the present invention, the coating method includes roller coating, spraying, etc., and roller coating is preferred, that is, using roller coating equipment to uniformly coat the water-based optical coating onto at least a portion of the surface of the substrate.

[0060] S500: Ventilation and drying are performed to evaporate the moisture in the water-based optical coating applied to the substrate surface and form a white optical coating on the substrate surface. Then, heating and curing are performed to obtain the projection screen of the present invention.

[0061] In this step, the purpose of heating and curing is to allow the water-based hydroxy acrylate polymer and isocyanate polymer in the coating to react fully, thereby improving the adhesion between particles inside the water-based optical coating and the adhesion between the water-based optical coating and the substrate, thus solving the problems of easy powdering and scratching of the coating.

[0062] Example 1

[0063] The specific steps for preparing the projection screen of the present invention by coating it with a water-based optical coating on a substrate are as follows:

[0064] (1) Weigh the raw materials according to the mass ratio. The components of the raw materials are as follows: 45 parts of inorganic particles (the mass ratio of rutile titanium dioxide to boehmite is 10:1, the average particle size of titanium dioxide is 400nm, and the average particle size of boehmite is 0.8μm), 40 parts of waterborne hydroxy acrylate polymer (hydroxyl value is 10mgKOH / g, glass transition temperature is -20℃, and solid content is 45wt%), 2.5 parts of isocyanate polymer (Covestro XP2655), 0.1 parts of dispersant (DISPERSANT 5050), 0.5 parts of leveling agent (the mass ratio of RianPont2903 and Evonik Dynol 604 is 3:1), and 11.9 parts of deionized water.

[0065] (2) The raw materials weighed in step (1) are mixed and stirred using a high shear mixer at a stirring rate of 3000 rpm for 1.5 hours to obtain the water-based optical coating for the projection screen of the present invention, wherein the viscosity of the water-based optical coating is 46 mPa·s and the surface tension is 25 mN / m.

[0066] (3) Provide a substrate (TPU substrate) and sandblast the surface of the substrate.

[0067] (4) Use a roller coating machine to uniformly coat the water-based optical coating obtained in step (2) onto a portion of the substrate surface.

[0068] (5) The substrate in step (4) is dried and cured to obtain the projection screen of the present invention, wherein the coating thickness is 8μm, the bonding force between the coating and the substrate is 3.1N, and the viewing comfort level is level 2.

[0069] Examples 2-9

[0070] The steps for preparing water-based optical coatings and projection screens in Examples 2-9 are the same as those in Example 1. The types and amounts of each component in the raw materials, the stirring parameters in step (2), and the parameters of the prepared coatings and the test results of the projection screens are shown in Tables 1-3.

[0071] Comparative Examples 1-4

[0072] The steps for preparing water-based optical coatings and projection screens in Comparative Examples 1-4 are the same as those in Example 1. The types and amounts of each component in the raw materials, the stirring parameters in step (2), and the test results of the obtained projection screens are shown in Tables 1-3.

[0073] Performance testing methods

[0074] 1. Coating-substrate adhesion test

[0075] The adhesion between the coating and the substrate was tested using a scratch tester. First, the projection screen sample to be tested was placed on the sample stage. Then, the scratch tester was brought into contact with the surface of the screen sample. During the process of linearly applying a normal load along the surface of the screen sample, the coating will exhibit adhesion failure phenomena such as micro-cracks, cracking, and peeling from the substrate. The critical load value at which the coating peels from the substrate is taken as the magnitude of the adhesion between the coating and the substrate.

[0076] 2. Testing the "Solar Effect"

[0077] The presence of the "solar effect" was observed visually, and the observer's visual comfort level was set on a five-level scale, with level one being extremely inconspicuous, level two being inconspicuous, level three being generally noticeable, level four being noticeable, and level five being extremely noticeable.

[0078] Table 1

[0079]

[0080]

[0081] Table 2

[0082]

[0083] Table 3

[0084]

[0085]

[0086] As can be seen from the data in Tables 1-3, compared with Comparative Examples 1-4, the projection screens prepared in Examples 1-9 of this invention show a significantly improved adhesion between the coating and the substrate. This indicates that the addition of an aqueous hydroxyl acrylate polymer with the aforementioned hydroxyl value range and glass transition temperature range to the aqueous optical coating of this invention effectively improves the adhesion between the aqueous optical coating and the screen substrate, thus mitigating the problem of easy coating peeling. In Example 7, the insufficient addition of inorganic particles resulted in a thinner coating and insufficient coverage.

[0087] By comparing the test results of the "solar effect" of Examples 1-7 and Example 9, it can be seen that the addition of boehmite in Examples 1-7 effectively improved the "solar effect" of the coating.

[0088] By comparing the test results of the "solar effect" of Examples 1-7 and Example 8, it can be seen that the mass of titanium dioxide added in Example 8 is higher than that in Examples 1-7, while the mass of boehmite added is lower (compared to the mass ratio of titanium dioxide and boehmite in the inorganic particles of this invention). As a result, the extinction effect of boehmite is not obvious, and the coating still exhibits a significant "solar effect".

[0089] The terms "first" and "second" used in this document are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature marked "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0090] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0091] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A water-based optical coating for a projection screen, characterized in that, include: Inorganic particles, aqueous hydroxy acrylate polymer, isocyanate polymer, dispersant and water, The aqueous hydroxyl acrylate polymer has a hydroxyl value of 10 mg KOH / g-20 mg KOH / g and a glass transition temperature of -30℃ to 10℃. The inorganic particles include titanium dioxide and boehmite, and the mass ratio of titanium dioxide to boehmite is (5-12):

1. The average particle size of the titanium dioxide is 200nm-400nm; The boehmite particles have a hexahedral structure. The average grain size of the boehmite is 0.8 μm-1.2 μm; The mass ratio of the inorganic particles, the aqueous hydroxy acrylate polymer, the isocyanate polymer, the dispersant, and the water is (45-60):(25-40):(1-2.5):(0.1-0.5):(10-25).

2. The coating according to claim 1, characterized in that, The solid content of the aqueous hydroxy acrylate polymer is 35wt%-45wt%.

3. The coating according to claim 1 or 2, characterized in that, The dispersant includes at least one of the following: ammonium polycarboxylate dispersants, sodium polycarboxylate dispersants, and nonionic polymer dispersants.

4. The coating according to claim 1 or 2, characterized in that, It also includes leveling agents, said leveling agents comprising at least one of polyether-modified organosiloxane copolymers and acetylenic diol ethoxylates.

5. The coating according to claim 4, characterized in that, The mass ratio of the polyether-modified organosiloxane copolymer to the acetylacetonate ethoxylate is (3-8):

1.

6. The coating according to claim 4, characterized in that, The mass ratio of the aqueous hydroxy acrylate polymer to the leveling agent is (25-40):(0.5-3).

7. The coating according to claim 1, characterized in that, The viscosity of the water-based optical coating is 30 mPa·s-60 mPa·s.

8. The coating according to claim 1, characterized in that, The surface tension of the water-based optical coating is 20mN / m-25mN / m.

9. A projection screen, characterized in that, include: Substrate; A coating provided on at least a portion of the surface of the substrate, the coating being prepared using the coating material according to any one of claims 1-8.

10. The projection screen according to claim 9, characterized in that, The substrate includes at least one of polyester-type TPU substrate or polyether-type TPU substrate.

11. The projection screen according to claim 9, characterized in that, The coating thickness is 5μm-10μm.

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