A projection screen and a method of manufacturing the same

Abstract

The application discloses a projection screen and a preparation method thereof, and relates to the technical field of projection screens.The projection screen comprises a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer; the surface of the fiber of the fabric layer is provided with an interfacial bonding layer formed by polyethylene imine, which helps to improve the interlayer bonding force; the base layer contains furan group modified polyurethane resin and bismaleimide crosslinking agent, and can realize thermal repair of surface micro scratches; the optical layer uses silica@graphene-silver core-shell structure composite powder, which helps to realize multifunctional synergy such as scattering, absorption and brightening, and improves the viewing effect.The projection screen provided by the application has the characteristics of high adhesion strength, damage self-repairing ability, high brightness, wide viewing angle, excellent anti-environmental light interference and long service life, and solves the technical bottlenecks of easy peeling between layers, easy damage on the surface and difficult consideration of optical performance in the prior art.

Description

Technical Field

[0001] This invention relates to the field of projection screen technology, and in particular to a projection screen and its manufacturing method. Background Technology

[0002] As a core component of a projection display system, the performance of the projection screen directly affects the clarity, color reproduction, and visual comfort of the final image. From a technological development perspective, projection screens have evolved from traditional white plastic screens to glass bead screens, and then to metal screens. Each generation of products has attempted to balance the three core parameters of gain, viewing angle, and color reproduction. In recent years, with the popularization of 4K / 8K ultra-high-definition content and HDR technology, the market has placed more stringent demands on projection screen performance. High gain is required to ensure brightness, a wide viewing angle is needed to accommodate viewing from multiple angles, and excellent ambient light resistance is necessary to ensure that pure and vibrant images are presented even in bright environments.

[0003] In existing technologies, projection screens can be broadly categorized into two types based on optical principles: reflective and transmissive. They can also be classified into different types based on surface structure, such as flat screens and curved screens. In terms of materials, mainstream products on the market include white plastic screens, fiberglass screens, pearl screens, and metal screens. While these traditional screens each have their advantages in specific applications, they generally share a common problem: it's difficult to simultaneously achieve a combination of high gain, wide viewing angle, clear imaging, anti-reflection, and scratch resistance. For example, while high-gain metal screens can effectively improve brightness, they have narrow viewing angles and are prone to hotspot effects; white plastic screens have wide viewing angles but low gain, resulting in a significant drop in image quality in bright ambient light.

[0004] For example, existing technologies disclose a three-layer projection screen comprising a fabric layer, a substrate layer, and an optical layer. This design attempts to provide basic support through a fabric layer woven from multiple fibers, achieve basic reflective function through a silver-powder-containing substrate layer, and enhance optical performance through an optical layer containing silicon dioxide and graphene. However, the separate design of the reflective and anti-glare layers easily creates a significant optical interface, causing interface reflection and scattering, reducing light energy utilization. Furthermore, the material properties between the layers differ greatly, and during long-term use, with changes in temperature and humidity and mechanical stress relaxation, the coating at the interface is prone to cracking and peeling, severely affecting the screen's lifespan.

[0005] Therefore, there is an urgent need to optimize existing projection screens to meet the high performance requirements of simultaneously achieving high gain, wide viewing angle, clear imaging, anti-reflection, and scratch resistance. Summary of the Invention

[0006] The technical problem to be solved by this invention is that existing projection screens cannot meet the high performance requirements of simultaneously achieving high gain, wide viewing angle, clear imaging, anti-reflection and scratch resistance.

[0007] To address the above problems, the present invention proposes the following technical solution: In a first aspect, the present invention provides a projection screen, comprising a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer; wherein, The fiber surface of the fabric layer has an interfacial bonding layer formed of polyethyleneimine; The base layer comprises the following components in parts by weight: 3-9 parts of nano silver powder, 100 parts of furan group modified polyurethane resin, 3-8 parts of bismaleimide crosslinking agent, 40-66 parts of solvent, and 5-8 parts of base curing agent. The optical layer comprises the following components in parts by weight: 5-15 parts of silicon dioxide@graphene-silver composite powder, 30-60 parts of ethanol, 3-9 parts of optical curing agent, 100 parts of matte resin base, 2-5 parts of film-forming aid, and 0.2-3 parts of defoamer.

[0008] A further technical solution is that the furan-modified polyurethane resin is prepared by reacting isophorone diisocyanate, polycarbonate diol and furan methacrylamide, wherein the isocyanate index is 1.05-1.15.

[0009] A further technical solution is that the solvent is any one or a combination of acetone, ethyl acetate, methyl isobutyl ketone, and propylene glycol methyl ether acetate.

[0010] A further technical solution is that the substrate curing agent is an isocyanate curing agent with an NCO content of 15-20%; the optical curing agent is an acrylate photoinitiator, which is any one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0011] A further technical solution is that the fabric layer is composed of interwoven fiber materials, which are any one or more of pineapple fiber, flax fiber, and jute fiber, interwoven with basalt fiber.

[0012] A further technical solution is that the silicon dioxide@graphene-silver composite powder is prepared by the following method: a) Monodisperse silica microspheres are provided, and they are aminated using aminopropyltriethoxysilane to obtain aminated silica; b) The aminated silica was dispersed in an aqueous solution of graphene oxide with a pH of 3.5-4.5, wherein the mass ratio of aminated silica to graphene oxide was 1:0.5-2, and stirred at 30-50°C for 2-4 hours; then hydrazine hydrate was added, and the mixture was reduced at 80-95°C for 2-4 hours. After centrifugation, washing, and drying, silica@graphene composite powder was obtained. c) The silica@graphene composite powder is dispersed in a 0.01-0.1 mol / L silver ammonia solution, wherein the mass ratio of silver to silica@graphene composite powder is 0.05-0.15:1, and the mixture is stirred at 40-60℃ for 1-3 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain the silica@graphene-silver composite powder. The silica microspheres have a particle size of 200-300 nanometers.

[0013] In a second aspect, the present invention provides a method for preparing a projection screen as described in the first aspect, comprising the following steps: S1: Pretreatment of the fabric layer: Immerse the woven fabric layer in a solution containing polyethyleneimine, remove and dry it to form an interfacial bonding layer on the fiber surface; S2: Coating and curing of the base layer: The base layer slurry is uniformly coated on the surface of the interface bonding layer and cured by UV irradiation to form the base layer; S3: Coating and curing of the optical layer: The optical layer slurry is uniformly coated on the surface of the substrate and cured by UV irradiation to form the optical layer.

[0014] The further technical solution is that the concentration of polyethyleneimine in the solution of step S1 is 0.3% - 3%, the soaking time is 5-30 minutes, and the drying temperature is 50-80℃.

[0015] The further technical solution is that, in steps S2 and S3, the ultraviolet curing conditions are: wavelength 300-400nm, irradiation time 5-30 seconds.

[0016] A further technical solution is that step S3 also includes calendering at 40-60℃ after curing.

[0017] Compared with the prior art, the technical effects achieved by the present invention include: The projection screen provided by this invention introduces an interface bonding layer composed of polyethyleneimine. The amine groups in the layer react chemically with the curing agent in the base layer to form strong covalent bonds, which in turn form strong electrostatic adsorption and entanglement with the fabric fibers. This achieves super strong interfacial adhesion between the base coating and the fabric layer, effectively avoiding the risk of interlayer peeling under long-term use.

[0018] The base layer of this invention contains furan-modified polyurethane resin and a bismaleimide crosslinking agent, which can form a crosslinked network. This network enhances the mobility of polymer chain segments when heated (e.g., 50-70°C), promoting contact at damaged interfaces and rebonding as the temperature decreases. This effectively repairs surface micro-scratches and significantly improves the screen's durability and long-term optical stability. Simultaneously, the uniform dispersion of nano-silver powder constitutes a highly efficient reflective layer, providing a foundation for the screen's high brightness.

[0019] Furthermore, the optical layer of this invention uses a silicon dioxide@graphene-silver core-shell structured composite powder instead of traditional single graphene and silicon dioxide powders, which helps to achieve synergistic effects of scattering, absorption, and brightness enhancement, thereby improving the viewing experience. The projection screen provided by this invention features high adhesion strength, self-healing ability, high brightness, wide viewing angle, excellent resistance to ambient light interference, and long service life, solving the technical bottlenecks commonly found in existing technologies, such as easy peeling between layers, easy surface damage, and difficulty in achieving both optical performance and durability. Detailed Implementation

[0020] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0022] It should also be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0023] This invention provides a projection screen, comprising a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer; wherein, The fiber surface of the fabric layer has an interfacial bonding layer formed of polyethyleneimine.

[0024] In practice, the fabric layer serves as the supporting substrate for the screen and is constructed by weaving basalt fibers with any one or more of pineapple fibers, flax fibers, and jute fibers in a crisscross pattern. Jute fibers and basalt fibers are preferred. These natural fibers provide excellent mechanical properties and dimensional stability, while basalt fibers endow the entire fabric layer with high-temperature resistance and flame retardancy.

[0025] In this embodiment of the invention, the fiber surface of the fabric layer contains an interfacial bonding layer formed by polyethyleneimine (PEI). PEI is a high molecular weight polymer rich in amine groups (-NH2), and its aqueous solution is cationic. This invention utilizes the strong hydrogen bonds and electrostatic interactions formed by its amine groups with polar groups (such as hydroxyl groups) on the fiber surface to achieve excellent initial adhesion. More importantly, these highly reactive amine groups can undergo irreversible chemical reactions with the subsequent base curing agent (isocyanate, -NCO group) in the base layer to generate strong urea bonds, thereby improving interlayer bonding and solving the problem of insufficient interlayer adhesion between the fabric layer and the base layer.

[0026] In practice, the interfacial bonding layer can be formed by immersing the fabric layer in a 0.3% - 3% PEI aqueous solution. Within this concentration range, it can be ensured that a continuous, uniform film with sufficient reaction sites is formed.

[0027] The substrate layer comprises the following components in parts by weight: 3-9 parts of nano silver powder, 100 parts of furan-modified polyurethane resin, 3-8 parts of bismaleimide crosslinking agent, 40-66 parts of solvent, and 5-8 parts of substrate curing agent.

[0028] In practice, the nano-silver powder, as the main functional reflective material, has a particle size controlled between 0.5 and 0.8 μm. This particle size range ensures that the silver powder has extremely high reflectivity for visible light, while avoiding the problems of excessively large specific surface area and easy agglomeration due to excessively small particle size, or increased surface roughness of the coating due to excessively large particle size.

[0029] In specific implementation, the base layer of the present invention contains a furan-modified polyurethane resin and a bismaleimide crosslinking agent, which can form a reversible crosslinking network through a Diels-Alder reaction. When the coating is damaged (e.g., scratched) and heated (e.g., 50-70°C), the dynamic covalent bonds break reversibly, causing the material to flow locally and achieving crack healing.

[0030] In practice, the furan-modified polyurethane resin is prepared by reacting isophorone diisocyanate, polycarbonate diol and furan methacrylamide, wherein the isocyanate index is 1.05-1.15.

[0031] In specific implementations, the solvent is any one or a combination of acetone, ethyl acetate, methyl isobutyl ketone, and propylene glycol methyl ether acetate, used to adjust the viscosity of the slurry and ensure coating processability. This invention does not limit the specific type of solvent; those skilled in the art can select suitable organic solvents according to actual process requirements.

[0032] In practice, the substrate curing agent is an isocyanate curing agent with an NCO content of 15-20%. The isocyanate curing agent can react with the hydroxyl groups (-OH) in the resin and the amine groups (-NH2) in the interfacial bonding layer PEI to improve the interlayer bonding force.

[0033] The optical layer comprises the following components in parts by weight: 5-15 parts of silicon dioxide@graphene-silver composite powder, 30-60 parts of ethanol, 3-9 parts of optical curing agent, 100 parts of matte resin base, 2-5 parts of film-forming aid, and 0.2-3 parts of defoamer.

[0034] In a specific embodiment, the silica@graphene-silver composite powder uses monodisperse silica microspheres with a particle size of 200-300 nanometers as the core, which can provide effective scattering of light, thereby widening the viewing angle; the graphene shell can effectively absorb ambient stray light and improve contrast; while the silver nanoparticles (particle size of 20-50 nanometers) loaded on the graphene utilize their local surface plasmon resonance effect to selectively enhance the reflectivity of specific wavelengths (such as blue light), thereby synergistically improving gain and color performance.

[0035] It is important to emphasize that silicon dioxide is a dielectric, forming a "dielectric core-conductive shell" structure with the outer graphene and silver nanoparticles. This structure can modulate and enhance the localized surface plasmon resonance (LSPR) effect of the silver nanoparticles. Without the silicon dioxide core, the silver nanoparticles would grow directly on the graphene, and their optical enhancement effect would be significantly reduced.

[0036] In a specific embodiment, the silica@graphene-silver composite powder is prepared by the following method: a) Monodisperse silica microspheres are provided, and they are aminated using aminopropyltriethoxysilane to obtain aminated silica; b) The aminated silica was dispersed in an aqueous solution of graphene oxide with a pH of 3.5-4.5, wherein the mass ratio of aminated silica to graphene oxide was 1:0.5-2, and stirred at 30-50°C for 2-4 hours; then hydrazine hydrate was added, and the mixture was reduced at 80-95°C for 2-4 hours. After centrifugation, washing, and drying, silica@graphene composite powder was obtained. c) The silica@graphene composite powder is dispersed in a 0.01-0.1 mol / L silver ammonia solution, wherein the mass ratio of silver to silica@graphene composite powder is 0.05-0.15:1, and the mixture is stirred at 40-60℃ for 1-3 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain the silica@graphene-silver composite powder. The silica microspheres have a particle size of 200-300 nm, and the loaded silver particles have a particle size of 20-50 nm.

[0037] In practice, the optical curing agent is an acrylate photoinitiator, specifically one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. It can generate free radicals under UV light irradiation of a specific wavelength, initiating the rapid polymerization and curing of active monomers or oligomers in the slurry to form a hard coating.

[0038] In specific implementation, the matte resin base material comprises a film-forming resin and a matting filler. The film-forming resin is a UV-curable resin, preferably an acrylate resin. Examples include epoxy acrylates, polyurethane acrylates, and polyester acrylates, which exhibit excellent leveling and color tolerance. This invention does not limit the specific resin type; any resin suitable for UV curing and capable of providing the required mechanical properties to the coating can be used. The matting filler can be fumed silica, uniformly dispersed in the film-forming resin, scattering light to reduce specular reflection (matte finish). The matte resin base material of this invention can be a specially formulated custom mixture, or commercially available UV-curable matte varnishes or UV-curable matte paints can be directly selected.

[0039] In specific implementations, film-forming aids can be selected from medium- to high-boiling-point solvents such as texanol, propylene glycol phenyl ether (PPH), or benzyl alcohol. This invention does not limit the specific type of film-forming aid.

[0040] In practice, defoamers can be selected from silicone defoamers, non-silicone defoamers (such as mineral oil-based and polyether-based defoamers), etc. For example, modified silicone defoamers (such as the BYK series) have excellent compatibility and long-lasting foam suppression ability. This invention does not limit the specific type of defoamer.

[0041] This invention also provides a method for preparing the projection screen, comprising the following steps: S1: Pretreatment of the fabric layer: Immerse the woven fabric layer in a solution containing polyethyleneimine, remove and dry it to form an interfacial bonding layer on the fiber surface; S2: Coating and curing of the base layer: The base layer slurry is uniformly coated on the surface of the interface bonding layer and cured by UV irradiation to form the base layer; S3: Coating and curing of the optical layer: The optical layer slurry is uniformly coated on the surface of the substrate and cured by UV irradiation to form the optical layer.

[0042] In specific implementation, the concentration of polyethyleneimine in the solution of step S1 is 0.3% - 3%, the soaking time is 5-30 minutes, and the drying temperature is 50-80℃.

[0043] In specific implementation, in step S2, a spraying process is used to uniformly coat the substrate slurry onto the surface of the interface bonding layer, with the coating thickness controlled between 50-200 μm. The ultraviolet curing conditions are: wavelength 300-400 nm, irradiation time 5-30 seconds.

[0044] In specific implementation, in step S3, the optical layer slurry is uniformly coated onto the surface of the substrate using a spraying process, with the coating thickness controlled between 30-100 μm. The ultraviolet curing conditions are: wavelength 300-400 nm, irradiation time 5-30 seconds.

[0045] In specific implementation, step S3 also includes a calendering process at 40-60℃ after curing to eliminate microscopic unevenness and obtain a smooth surface.

[0046] It should be noted that the coating thickness of the substrate layer and the optical layer can be set according to performance requirements, and this invention does not limit this.

[0047] Example 1 This embodiment discloses a projection screen, comprising a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer. In this embodiment, the fabric layer is woven from jute fibers and basalt fibers alternately in a 1:1 mass ratio.

[0048] The slurry formulation for the base layer is as follows: 6 parts of nano silver powder (particle size 0.6μm), 100 parts of furan group modified polyurethane resin, 5 parts of bismaleimide crosslinking agent, 50 parts of solvent (acetone and ethyl acetate mixed in a 1:1 ratio), and 6 parts of isocyanate curing agent (NCO content 18%).

[0049] The slurry formulation for the optical layer is as follows: 10 parts silica@graphene-silver composite powder, 45 parts ethanol, 5 parts 2-hydroxy-2-methyl-1-phenyl-1-propanone, 100 parts UV-curable matte varnish (containing epoxy acrylate and fumed silica), 3 parts alcohol ester dodecyl film-forming agent, and 1 part silicone defoamer.

[0050] The silica@graphene-silver composite powder in this embodiment was prepared by the following method: a) Add 500 mL of anhydrous ethanol and 50 mL of deionized water to a 1000 mL three-necked flask, add 20 mL of concentrated ammonia (28%), and mechanically stir (300 rpm); dissolve 40 mL of tetraethyl orthosilicate (TEOS) in 100 mL of anhydrous ethanol and slowly add it dropwise to the reaction system. React at 25 °C for 12 hours to obtain a monodisperse silica microsphere suspension. Centrifuge at 8000 rpm for 10 min to collect the silica microspheres (particle size 250 ± 15 nm), and wash three times with ethanol; redisperse the obtained silica microspheres in 200 mL of ethanol; add 4 mL of aminopropyltriethoxysilane (APTES), reflux at 70 °C for 6 hours, centrifuge to collect the aminated silica, wash three times with ethanol, and vacuum dry at 60 °C for 12 hours to obtain aminated silica.

[0051] b) Disperse 1.0 g of aminated silica in 500 mL of deionized water, adjust the pH to 4.0 with dilute hydrochloric acid, add an aqueous solution containing 0.8 g of graphene oxide (total volume 800 mL), and mechanically stir at 40 °C (400 rpm) for 3 hours to complete electrostatic self-assembly; then add 5 mL of hydrazine hydrate (80% volume fraction), reflux at 90 °C for 3 hours, centrifuge (10000 rpm, 15 min) to collect the product, wash with deionized water until neutral, and vacuum dry at 60 °C for 24 hours to obtain silica@graphene composite powder.

[0052] c) Preparation of 0.05 mol / L silver ammonia solution: Dissolve 0.85 g silver nitrate in 50 mL deionized water, and add ammonia dropwise until the precipitate just dissolves; disperse 0.5 g silica@graphene composite powder in 80 mL deionized water, sonicate for 30 minutes, then add 100 mL of 0.05 mol / L silver ammonia solution (silver element to composite powder mass ratio 0.1:1), stir and react in a 50 °C water bath for 2 hours, centrifuge (12000 rpm, 20 min) to collect the product, wash 3 times with deionized water and 1 time with ethanol, and vacuum dry at 60 °C for 24 hours to obtain silica@graphene-silver composite powder.

[0053] The silica@graphene-silver composite powder obtained in this embodiment was determined to contain 9.8 wt% silver (ICP-OES determination) and 35 ± 8 nm particle size; 15.3 wt% carbon (elemental analysis); and 74.9 wt% silica.

[0054] The projection screen manufacturing process in this embodiment is as follows: The fabric layer was immersed in a 1.5% PEI solution for 15 minutes and dried at 65°C to form an interfacial bonding layer on the fiber surface. The base layer slurry was uniformly coated on the surface of the interface bonding layer and cured by 365nm UV irradiation for 15 seconds to form the base layer with a wet film thickness of 120μm. The optical layer slurry was uniformly coated on the surface of the substrate and cured by 365nm UV irradiation for 15 seconds to form the optical layer with a wet film thickness of 60μm. Finally, the cured screen undergoes a 50°C heat treatment.

[0055] Example 2 This embodiment discloses a projection screen, comprising a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer. In this embodiment, the fabric layer is woven from alternating layers of pineapple fiber and basalt fiber in a 1:2 mass ratio.

[0056] The slurry formulation for the base layer is as follows: 8 parts of nano silver powder (particle size 0.7μm), 100 parts of furan group modified polyurethane resin, 6 parts of bismaleimide crosslinking agent, 55 parts of propylene glycol methyl ether acetate, and 7 parts of isocyanate curing agent (NCO content 16%).

[0057] The slurry formulation for the optical layer is as follows: 12 parts of silica@graphene-silver composite powder (same as in Example 1), 50 parts of ethanol, 6 parts of 1-hydroxycyclohexylphenyl ketone, 100 parts of UV-curable matte varnish (containing polyurethane acrylate and fumed silica), 4 parts of propylene glycol phenyl ether film-forming agent, and 2 parts of mineral oil-based defoamer.

[0058] The projection screen manufacturing process in this embodiment is as follows: The fabric layer was immersed in a 2.0% PEI solution for 20 minutes and dried at 70°C to form an interfacial bonding layer on the fiber surface. The substrate slurry was uniformly coated on the surface of the interface bonding layer and cured by 385nm UV irradiation for 20 seconds to form the substrate layer with a wet film thickness of 150μm. The optical layer slurry was uniformly coated on the surface of the substrate and cured by 385nm UV irradiation for 20 seconds to form the optical layer with a wet film thickness of 80μm. Finally, the cured screen undergoes a 50°C heat treatment.

[0059] Comparative Example 1 This comparative example provides a projection screen, including a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer.

[0060] The fabric layer material in this comparative example is the same as that in Example 1, but without the PEI interface bonding layer. The formulations of the substrate layer and optical layer are the same as in Example 1.

[0061] In the preparation process, the fabric layer is directly coated with the base layer, and other processes are the same as in Example 1.

[0062] Comparative Example 2 This comparative example provides a projection screen, including a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer.

[0063] In this comparative example, only the formulation of the base layer is different: 6 parts of nano silver powder (particle size 0.6 μm), 100 parts of unmodified ordinary polyurethane resin, 50 parts of solvent (acetone and ethyl acetate mixed in a 1:1 ratio), and 6 parts of isocyanate curing agent (NCO content 18%). Other formulations and processes are the same as in Example 1.

[0064] Comparative Example 3 This comparative example provides a projection screen, including a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer.

[0065] In this comparative example, only the formulation of the optical layer is different: 6 parts silica powder (particle size 250nm), 3 parts graphene powder, 1 part nano silver powder (particle size 30nm), 45 parts ethanol, 5 parts 2-hydroxy-2-methyl-1-phenyl-1-propanone, 100 parts UV-curable matte varnish (containing epoxy acrylate and fumed silica), 3 parts alcohol ester dodecyl film-forming agent, and 1 part silicone defoamer. All other formulations and processes are the same as in Example 1.

[0066] Comparative Example 4 This comparative example provides a projection screen, including a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer.

[0067] In this comparative example, only the nano-silver powder in the substrate layer has a particle size of 2.5 μm; the other formulations and processes are the same as in Example 1.

[0068] Performance tests were conducted on the projection screens of the above embodiments and comparative examples, and the results are shown in Table 1. The following optical performance indicators were measured in a darkroom using a luminance meter equipped with an integrating sphere and a standard projector: Gain: The ratio of the brightness along the central axis of the screen to that of a standard white board; Viewing angle: The angle at which the brightness drops to half of the brightness along the central axis; Contrast Ratio: The ratio of brightness of a full white screen to a full black screen is measured under 20 lux ambient light.

[0069] Adhesion: Tested using a cross-cut adhesion tester (ASTM D3359), rated from 0B (worst) to 5B (best).

[0070] Abrasion resistance: Using a standard abrasion tester (CS-10 grinding wheel, 500g load), record the number of friction revolutions at which obvious scratches appear.

[0071] Self-healing: Standard scratches were created using a metal scratcher, and then placed in a 60°C oven for 30 minutes. The healing of the scratches was observed under a microscope, and the repair rate was calculated.

[0072] Table 1 Performance Test Results

[0073] As shown in Table 1, the projection screen provided by the present invention, by introducing an interface bonding layer composed of polyethyleneimine, can form strong covalent bonds with the curing agent in the base layer through a chemical reaction of its rich amine groups. This results in strong electrostatic adsorption and entanglement with the fabric fibers, achieving super strong interfacial adhesion between the base coating and the fabric layer, effectively avoiding the risk of interlayer peeling under long-term use.

[0074] The base layer of this invention contains furan-modified polyurethane resin and a bismaleimide crosslinking agent, which can form a crosslinked network. This network enhances the mobility of polymer chain segments when heated (e.g., 50-70°C), promoting contact at damaged interfaces and rebonding as the temperature decreases. This effectively repairs surface micro-scratches and significantly improves the screen's durability and long-term optical stability. Simultaneously, the uniform dispersion of nano-silver powder constitutes a highly efficient reflective layer, providing a foundation for the screen's high brightness.

[0075] Furthermore, the optical layer of this invention uses a silicon dioxide@graphene-silver core-shell structured composite powder instead of traditional single graphene and silicon dioxide powders, which helps to achieve synergistic effects of scattering, absorption, and brightness enhancement, thereby improving the viewing experience. The projection screen provided by this invention features high adhesion strength, self-healing ability, high brightness, wide viewing angle, excellent resistance to ambient light interference, and long service life, solving the technical bottlenecks commonly found in existing technologies, such as easy peeling between layers, easy surface damage, and difficulty in achieving both optical performance and durability.

[0076] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0077] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A projection screen, characterized in that, It includes a fabric layer, a base layer covering the surface of the fabric layer, and an optical layer covering the surface of the base layer; wherein, The fiber surface of the fabric layer has an interfacial bonding layer formed of polyethyleneimine; The base layer comprises the following components in parts by weight: 3-9 parts of nano silver powder, 100 parts of furan group modified polyurethane resin, 3-8 parts of bismaleimide crosslinking agent, 40-66 parts of solvent, and 5-8 parts of base curing agent. The optical layer comprises the following components in parts by weight: 5-15 parts of silicon dioxide@graphene-silver composite powder, 30-60 parts of ethanol, 3-9 parts of optical curing agent, 100 parts of matte resin base, 2-5 parts of film-forming aid, and 0.2-3 parts of defoamer.

2. The projection screen according to claim 1, characterized in that, The furan-modified polyurethane resin is prepared by reacting isophorone diisocyanate, polycarbonate diol and furan methacrylamide, wherein the isocyanate index is 1.05-1.

15.

3. The projection screen according to claim 1, characterized in that, The solvent is any one or a combination of acetone, ethyl acetate, methyl isobutyl ketone, and propylene glycol methyl ether acetate.

4. The projection screen according to claim 1, characterized in that, The substrate curing agent is an isocyanate curing agent with an NCO content of 15-20%; the optical curing agent is an acrylate photoinitiator, which is any one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

5. The projection screen according to claim 1, characterized in that, The fabric layer is composed of interwoven fiber materials, which are any one or more of pineapple fiber, flax fiber, and jute fiber, interwoven with basalt fiber.

6. The projection screen according to claim 1, characterized in that, The silica@graphene-silver composite powder is prepared by the following method: a) Monodisperse silica microspheres are provided, and they are aminated using aminopropyltriethoxysilane to obtain aminated silica; b) The aminated silica was dispersed in an aqueous solution of graphene oxide with a pH of 3.5-4.5, wherein the mass ratio of aminated silica to graphene oxide was 1:0.5-2, and stirred at 30-50°C for 2-4 hours; then hydrazine hydrate was added, and the mixture was reduced at 80-95°C for 2-4 hours. After centrifugation, washing, and drying, silica@graphene composite powder was obtained. c) The silica@graphene composite powder is dispersed in a 0.01-0.1 mol / L silver ammonia solution, wherein the mass ratio of silver to silica@graphene composite powder is 0.05-0.15:1, and the mixture is stirred at 40-60℃ for 1-3 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain the silica@graphene-silver composite powder. The silica microspheres have a particle size of 200-300 nanometers.

7. A method for preparing a projection screen as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Pretreatment of the fabric layer: Immerse the woven fabric layer in a solution containing polyethyleneimine, remove and dry it to form an interfacial bonding layer on the fiber surface; S2: Coating and curing of the base layer: The base layer slurry is uniformly coated on the surface of the interface bonding layer and cured by UV irradiation to form the base layer; S3: Coating and curing of the optical layer: The optical layer slurry is uniformly coated on the surface of the substrate and cured by UV irradiation to form the optical layer.

8. The preparation method according to claim 7, characterized in that, In step S1, the concentration of polyethyleneimine in the solution is 0.3% - 3%, the soaking time is 5-30 minutes, and the drying temperature is 50-80℃.

9. The preparation method according to claim 7, characterized in that, In steps S2 and S3, the UV curing conditions are: wavelength 300-400nm, irradiation time 5-30 seconds.

10. The preparation method according to claim 7, characterized in that, Step S3 also includes a calendering process at 40-60°C after curing.

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