A method for preparing a high-definition electronic screen protection paper

Abstract

The present application relates to the technical field of papermaking, and particularly relates to a preparation method of high-definition electronic screen protection paper. The method takes regenerated cellulose fiber as a main raw material, constructs a functional composite fiber with a core-shell structure, wherein the core layer is regenerated cellulose fiber, and the shell layer is a polypyrrole / graphene composite conductive layer to realize persistent antistatic performance; meanwhile, surface-modified nano-silicon dioxide aerogel particles are introduced to improve optical performance and mechanical strength; then, the polypyrrole / graphene composite conductive layer is compounded with polyimide fibers modified by a silane coupling agent, a bio-based wet strength agent and a fluorocarbon defoaming agent are added, and the protection paper is prepared through steps such as plasma pretreatment, grinding, web forming, controllable drying and magnetron sputtering surface treatment. The obtained protection paper has the characteristics of ultrathin, high strength, high light transmission and persistent antistatic performance, and is suitable for protection of high-end liquid crystal display screens and OLED screens.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, and specifically to a method for preparing high-definition electronic screen protector paper. Background Technology

[0002] High-definition electronic screens, such as liquid crystal displays (LCDs) and organic light-emitting diode (OLED) screens, are core components of modern electronic devices. Their surfaces are highly susceptible to scratches, friction, and electrostatic dust accumulation during production and transportation, leading to decreased product yield. Traditional protective papers often use natural fibers such as wood pulp and hemp pulp as raw materials, prepared through physical mixing and conventional processes. While offering some protection, they suffer from significant deficiencies in thickness, cleanliness, optical performance, and antistatic stability. For example, Chinese invention patent CN112593453A (a method for manufacturing protective paper for liquid crystal substrates) discloses a method for preparing protective paper using bleached sulfate softwood pulp and bleached hemp pulp as raw materials. This method, through specific pulping, papermaking, drying, and calendering processes, yields protective paper with a certain degree of air permeability and operability. However, this method relies on natural fibers and lacks in-depth chemical modification and functional design, resulting in a relatively thick protective paper (basis weight 48-52 g / m³). 2 Its optical performance is average (transmittance is about 85%), its antistatic performance is unstable (surface resistance 50-2000MΩ), and it is prone to shedding lint and powder, making it difficult to meet the strict requirements of high-end screens for ultra-thinness, high light transmittance, high cleanliness, and long-lasting antistatic properties.

[0003] As electronic screens evolve towards ultra-high definition and flexibility, the performance requirements for protective paper are increasing. Existing protective paper technologies often employ simple fiber mixing and surface coating with antistatic agents. These methods suffer from problems such as rapid degradation of antistatic properties, significant sacrifice of optical performance, and difficulty in further reducing thickness. In particular, while conventional quaternary ammonium salt antistatic agents are widely used, they are prone to migration and decomposition, leading to unstable antistatic performance. While simple fiber composites can improve mechanical properties, they cannot simultaneously achieve ultra-thin thickness and excellent optical performance. Therefore, developing a new type of protective paper that integrates ultra-thinness, high strength, high light transmittance, and durable antistatic properties has become an urgent industry need.

[0004] To address the aforementioned technical bottlenecks, this invention innovatively proposes a method for constructing core-shell structured functional composite fibers, introducing surface-modified nano-silica aerogel particles, and combining the latest plasma pretreatment and magnetron sputtering surface treatment technologies to prepare high-performance protective paper. This method, through molecular-level design and the application of nanotechnology, achieves multifunctional integration of the protective paper, solves the core problems in existing technologies, and possesses significant creativity and practicality. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing high-definition electronic screen protector paper, addressing the technical problems of existing protector papers, such as excessive thickness affecting packaging space efficiency, insufficient surface cleanliness leading to lint and powder shedding that contaminates the screen, poor optical performance affecting the accuracy of color development in quality inspection, and unstable antistatic properties. By constructing core-shell structured functional composite fibers to achieve durable antistatic properties, introducing surface-modified nano-silica aerogel particles to optimize optical performance, and combining advanced processes such as plasma pretreatment and magnetron sputtering surface treatment, a special protector paper with ultra-thin thickness, high mechanical strength, high light transmittance, low haze, and durable and stable antistatic properties is prepared, meeting the stringent requirements for protective materials in the production and transportation of high-end LCD and OLED screens.

[0006] A method for preparing a high-definition electronic screen protector includes the following steps:

[0007] S1. Functional composite fibers with core-shell structure: using regenerated cellulose fibers as the core layer, and constructing a polypyrrole / graphene composite conductive layer as the shell layer on its surface through in-situ polymerization.

[0008] S2. Preparation of surface-modified nano-silica aerogel particles: Nano-silica aerogels are prepared by sol-gel method and then surface-modified with fluorinated silanes.

[0009] S3. Preparation of silane coupling agent modified polyimide fibers: Polyimide fibers are surface modified by immersing them in an ethanol solution of 3-aminopropyltriethoxysilane.

[0010] S4. Fiber composite: The core-shell structured functional composite fiber obtained in step S1, the surface-modified nano-silica aerogel particles obtained in step S2, and the silane coupling agent modified polyimide fiber obtained in step S3 are mixed, and a bio-based wet strength agent and a fluorocarbon defoamer are added. After plasma pretreatment, the mixture is polished to obtain a mixed slurry.

[0011] S5. The pulp mixture from step S4 is subjected to wire bonding to obtain a shaped wet paper sheet.

[0012] S6. The wet paper sheet formed in step S5 is sequentially subjected to vacuum suction, pressing dehydration, and controlled drying until the paper moisture content is 3.0-5.0% to obtain the base paper;

[0013] S7. The paper from step S6 is subjected to surface treatment by magnetron sputtering to deposit a transparent conductive layer of indium tin oxide with a thickness of 50-100nm.

[0014] S8. The paper sheet processed in step S7 is subjected to paper defect monitoring and winding to obtain high-definition electronic screen protector paper.

[0015] Preferably, the preparation of the core-shell structured functional composite fiber in step S1 includes: dispersing regenerated cellulose fibers in deionized water to form a dispersion with a solid-liquid ratio of 1g:(10-15)mL, adding pyrrole monomer and graphene oxide, and adding a 3-6% ammonium persulfate aqueous solution as an oxidant at a rate of 1-2 drops / second in an ice-water bath at 0-5℃, reacting for 4-6 hours, wherein the mass ratio of pyrrole monomer to regenerated cellulose fibers is 1:(5-10), the amount of graphene oxide added is 10-20% of the mass of pyrrole monomer, and the molar ratio of ammonium persulfate to pyrrole monomer is (0.8-1.2):1.

[0016] Preferably, the preparation of the surface-modified nano-silica aerogel particles in step S2 includes: using tetraethyl orthosilicate as a precursor, mixing it with anhydrous ethanol and deionized water at a mass ratio of 1:(8-12):(1.5-2.5), adjusting the pH to 2.5-3.5 with acid, hydrolyzing at 50-70°C for 1.5-2.5 hours, then adjusting the pH to 7.5-8.5 with alkali and performing condensation polymerization for 3-5 hours to form a gel, drying with supercritical carbon dioxide to obtain nano-silica aerogel, and then dispersing it together with perfluorodecyltriethoxysilane at a mass ratio of 1:(0.7-0.9) in anhydrous ethanol, and refluxing at 80-100°C for 2-4 hours to complete the surface modification.

[0017] Preferably, the preparation of silane coupling agent modified polyimide fibers in step S3 includes: immersing polyimide short-cut fibers with a length of 2-4 mm and a diameter of 10-15 μm in a 1-3 wt% 3-aminopropyltriethoxysilane ethanol solution with a solid-liquid ratio of 1 g: (6-10) mL, and reacting at a constant temperature of 60-80°C with shaking for 1-2 hours. After the reaction is completed, the fibers are washed 2-4 times with ethanol.

[0018] Preferably, the mixed slurry in step S4 is composed of the following components by mass percentage: 60-80% core-shell structured functional composite fibers, 5-15% surface-modified nano-silica aerogel particles, 10-20% silane coupling agent modified polyimide fibers, 1-3% bio-based wet strength agent, and 0.5-1% fluorocarbon defoamer; the bio-based wet strength agent is a chitosan derivative with a degree of deacetylation ≥85%; the chitosan derivative is any one of carboxymethyl chitosan, hydroxypropyl chitosan, or quaternized chitosan; the molecular weight of the chitosan derivative is 50,000-200,000 Da.

[0019] Preferably, the plasma pretreatment conditions in step S4 are as follows: low-temperature plasma treatment is used, the power is 500-800W, the treatment time is 2-5 minutes, the working pressure is 40-60Pa, and the gas is a mixture of argon and oxygen with a volume ratio of argon to oxygen of (3-5):1.

[0020] Preferably, the pulping process in step S4 employs nanoscale pulping technology, with a pulping gap of 10-20 μm, a freeness of 35-45°SR, a wet weight of 4.0-6.0 g, and a pulp concentration controlled at 3.5-4.5%.

[0021] Preferably, the controllable drying in step S6 adopts a three-stage drying process: the first stage temperature is 80-100℃, and the drying time is 1-2 minutes; the second stage temperature is 120-140℃, and the drying time is 2-3 minutes; the third stage temperature is 160-180℃, and the drying time is 1-2 minutes, with the temperature deviation of each stage controlled within ±2℃.

[0022] Preferably, the process parameters for magnetron sputtering surface treatment in step S7 are as follows: using an indium tin oxide composite target, wherein the mass ratio of In2O3 to SnO2 to ZnO is (8-10):1:(1-0.5), the substrate temperature is 100-150℃, the sputtering power is 200-300W, the working pressure is 0.5-1.0Pa, the argon flow rate is 20-30sccm, and the deposition time is 20-40 minutes; the preparation method of the indium tin oxide composite target is as follows: mixing In2O3, SnO2 and ZnO powders in proportion, ball milling for 4-6 hours, wherein the ball-to-material ratio is (3-5):1, and the rotation speed is 300-500rpm; sintering at 1000-1200℃ to form a composite target; using this composite target during magnetron sputtering.

[0023] The core innovation of this invention lies in the construction of a functional composite fiber with a core-shell structure. Using regenerated cellulose fiber as the core layer, a polypyrrole / graphene composite conductive layer is constructed on the fiber surface as the shell layer through in-situ polymerization. Polypyrrole, as a conductive polymer, can form a continuous conductive network on the fiber surface through a redox reaction; the addition of graphene further enhances conductivity and mechanical strength. This core-shell structure not only achieves durable antistatic properties but also maintains the fiber's flexibility and optical transparency, solving the problems of easy migration and unstable performance of traditional antistatic agents.

[0024] Another innovation is the introduction of surface-modified nano-silica aerogel particles. Nano-silica aerogels prepared via the sol-gel method possess extremely high specific surface area and porosity. After surface modification with fluorinated silanes, their surface energy is significantly reduced, improving their compatibility with fibers. These nanoparticles form a uniformly dispersed nanoscale porous structure in the paper, ensuring both extremely high light transmittance and low haze, while also enhancing the paper's mechanical strength and dimensional stability through the nano-effect.

[0025] Furthermore, this invention employs several cutting-edge material processing and surface technologies. Plasma pretreatment activates the fiber surface, improving the bonding strength of subsequent composite materials; silane coupling agent modification of polyimide fibers enhances the interfacial bonding between the fibers and the matrix; magnetron sputtering deposits an indium tin oxide transparent conductive layer on the paper surface, further improving antistatic properties and surface smoothness. The synergistic application of these technologies achieves a qualitative leap in the performance of protective paper.

[0026] Beneficial technical effects of the present invention:

[0027] 1. The high-definition electronic screen protector paper prepared by this invention possesses superior optical performance. Its light transmittance is over 95%, and its haze is less than 2%, far exceeding that of traditional screen protectors, ensuring true color and uniform brightness during screen quality inspection. This is mainly due to the nanoscale porous structure and surface modification technology of the nano-silica aerogel, which effectively reduces light scattering, while the core-shell structure of the functional composite fibers maintains good light transmittance.

[0028] 2. Regarding antistatic properties, the protective paper exhibits a consistently low surface resistivity (10-50 MΩ). The polypyrrole / graphene conductive layer in the core-shell structure forms a three-dimensional conductive network, maintaining stable charge dissipation even in high humidity environments, effectively preventing electrostatic dust adsorption. The indium tin oxide layer deposited by magnetron sputtering further enhances surface conductivity without affecting optical performance.

[0029] 3. The protective paper also boasts excellent mechanical properties and cleanliness. Its thickness is only 0.08-0.12mm, and its basis weight is 45-51g / m³. 2 However, it possesses a longitudinal tensile strength ≥4.5kN / m and a transverse tensile strength ≥2.5kN / m, with moderate stiffness, making it easy to handle. The lint and dust shedding rate is less than 0.05%, and the surface is smooth and defect-free, ensuring it will not contaminate the surface of precision screens. These synergistic improvements in performance make this protective paper an ideal choice for protecting high-end electronic screens. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of the high-definition electronic screen protector paper preparation method of the present invention;

[0031] Figure 2 This is a schematic diagram illustrating the construction of the core-shell structured functional composite fiber of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of the surface-modified nano-silica aerogel particles of the present invention;

[0033] The names of the components shown in the diagram are as follows:

[0034] 201 represents the graphene composite layer, 202 represents the polypyrrole conductive layer, and 203 represents the regenerated cellulose fiber core layer.

[0035] 301 represents the surface modification layer, 302 represents fluorine groups, and 303 represents the nano-silica aerogel core. Detailed Implementation

[0036] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0037] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of those skilled in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or identical to those described in the embodiments of this invention may be used to implement this invention.

[0038] Unless otherwise stated, the test methods, detection methods and preparation methods disclosed in this invention all adopt conventional techniques in this technical field.

[0039] Example 1

[0040] First, a core-shell structured functional composite fiber was constructed. 85 parts of regenerated cellulose fiber were dispersed in 1020 parts of deionized water (solid-liquid ratio 1:12 g / mL), and stirred at 500 rpm to form a uniform dispersion. Then, 9.4 parts of pyrrole monomer and 1.7 parts of graphene oxide were added to the system. The mixture was kept at a constant temperature of 4°C in an ice-water bath, and a 5% ammonium persulfate aqueous solution (molar ratio of ammonium persulfate to pyrrole monomer 1:1) was slowly added dropwise at a rate of 1-2 drops / second as an oxidant. The reaction was allowed to proceed for 5.5 hours, allowing pyrrole to polymerize in situ on the fiber surface, forming a dense polypyrrole / graphene composite conductive shell with a thickness of 100 nm. Simultaneously, nano-silica was independently surface-modified. Aerogel preparation: Using 22 parts of tetraethyl orthosilicate as a precursor, 220 parts of anhydrous ethanol and 44 parts of deionized water were added. The pH was adjusted to 2.5 with hydrochloric acid, and the mixture was stirred and hydrolyzed in a 60°C water bath for 2.5 hours. Then, the pH was adjusted to 7.5 with ammonia, and the mixture was stirred and polycondensed for another 4.5 hours to form a gel. After supercritical carbon dioxide drying (critical temperature 31°C, critical pressure 7.4 MPa), 8.8 parts of nano-silica aerogel were obtained. This aerogel was then co-dispersed with 7.0 parts of perfluorodecyltriethoxysilane (mass ratio 1:0.8) in 88 parts of anhydrous ethanol, and the mixture was refluxed at 95°C for 3.5 hours to complete surface modification. The specific surface area of ​​the surface-modified nano-silica aerogel particles was 600 m². 2 / g; Next, the polyimide fibers (chopped fibers, 3mm in length and 12μm in diameter) were processed. 12 parts of polyimide fibers were immersed in 96 parts of a 2.5wt% 3-aminopropyltriethoxysilane ethanol solution (solid-liquid ratio 1:8), and the reaction was carried out at 75℃ with constant temperature shaking for 1 hour to complete the silane coupling agent modification. Then, the fibers were washed three times with ethanol. Then, the slurry was compounded, and 75% functional composite fibers, 8% surface-modified nano-silica aerogel particles, 12% modified polyimide fibers, and 1.5% bio-based wet strength agent (the bio-based wet strength agent is carboxymethyl chitosan, with a degree of deacetylation of 92% and a number average molecular weight of 150,000) were taken by mass percentage. The mixture of Da and 0.9% fluorocarbon defoamer was dispersed at 1000 rpm for 30 minutes, followed by low-temperature plasma treatment at 700W power, argon to oxygen volume ratio of 4:1, and working pressure of 50Pa for 3.5 minutes to fully activate the fiber surface. Nanoscale refining was then performed, with the refining gap controlled at 18μm, achieving a freeness of 42°SR and a wet weight of 5.5g. The paper was then formed on a long-wire paper machine with an 80-mesh forming wire, a speed of 280m / min, and a wire dewatering pressure of 0.25MPa. The dewatered wet paper sheet underwent a three-stage controlled drying process: the first stage was drying at 95℃ for 1 minute, the second stage at 135℃ for 2 minutes, and the third stage at 175℃ for 1 minute, to achieve the desired paper quality. The moisture content of the paper was reduced to 4.5%. Finally, an indium tin oxide transparent conductive layer was deposited on the paper surface by magnetron sputtering using an ITO composite target (mass ratio: In2O3:SnO2:ZnO = 9:1:0.5; the preparation method of the indium tin oxide composite target is: In2O3, SnO2 and ZnO powders are mixed in proportion, ball-milled for 4 hours, wherein the ball-to-material ratio is 5:1, the rotation speed is 300 rpm; sintered at 1100℃ to form the composite target; this composite target is used in magnetron sputtering). The substrate temperature was 140℃, the sputtering power was 280W, the working pressure was 0.9Pa, the argon flow rate was 28sccm, the deposition time was 35 minutes, and the deposition thickness was 90nm. After paper defect monitoring, the final protective paper product was obtained. The thickness of the high-definition electronic screen protector prepared in Example 1 was 0.11mm.

[0041] Example 2

[0042] First, a core-shell structured functional composite fiber was constructed. 75 parts of regenerated cellulose fiber were dispersed in 900 parts of deionized water (solid-liquid ratio 1:12), and stirred at 500 rpm to form a uniform dispersion. Then, 12.5 parts of pyrrole monomer and 1.5 parts of graphene oxide were added to the system. The mixture was kept at a constant temperature of 2°C in an ice-water bath, and a 5% ammonium persulfate aqueous solution (molar ratio of ammonium persulfate to pyrrole monomer 1:1) was slowly added dropwise at a rate of 1-2 drops / second as an oxidant. The reaction was allowed to proceed for 4.5 hours, allowing pyrrole to polymerize in situ on the fiber surface to form a polypyrrole / graphene composite conductive shell with a thickness of 100 nm. Simultaneously, nano-silica aerogels with independent surface modification were prepared. Preparation: Using 18 parts of tetraethyl orthosilicate as a precursor, 180 parts of anhydrous ethanol and 36 parts of deionized water were added. The pH was adjusted to 3.5 with hydrochloric acid, and the mixture was stirred and hydrolyzed in a 60°C water bath for 1.5 hours. Then, the pH was adjusted to 8.5 with ammonia, and the mixture was stirred and polycondensed for another 3.5 hours to form a gel. After supercritical carbon dioxide drying (critical temperature 31°C, critical pressure 7.4 MPa), 7.2 parts of nano-silica aerogel were obtained. This aerogel was then co-dispersed with 6.0 parts of perfluorodecyltriethoxysilane (mass ratio 1:0.83) in 72 parts of anhydrous ethanol, and the mixture was refluxed at 85°C for 2.5 hours to complete surface modification. The specific surface area of ​​the surface-modified nano-silica aerogel particles was 600 m². 2 / g; Next, the polyimide fibers (29 short-cut fibers, 3mm in length and 12μm in diameter) were processed. 18 parts of polyimide fibers were soaked in 144 parts of 1.5wt% 3-aminopropyltriethoxysilane ethanol solution (solid-liquid ratio 1:8), and the reaction was carried out at 65℃ with shaking for 2 hours to complete the silane coupling agent modification. Then, the fibers were washed three times with ethanol. Then, the slurry was compounded. 65% functional composite fiber, 12% surface-modified nano-silica aerogel particles, 18% modified polyimide fiber, and 2.5% bio-based wet strength agent (the bio-based wet strength agent is carboxymethyl chitosan, with a degree of deacetylation of 92% and a number average molecular weight of 150,000) were taken by mass percentage. Da) and 0.7% fluorocarbon defoamer were mixed and dispersed at 1000 rpm for 30 minutes. Then, low-temperature plasma treatment was performed for 2.5 minutes at 550W power, an argon to oxygen volume ratio of 4:1, and a working pressure of 50Pa to activate the fiber surface. Following this, nano-level refining was carried out, controlling the refining gap to 12μm, achieving a freeness of 38°SR and a wet weight of 4.5g. The paper was then formed on a long-wire paper machine with an 80-mesh forming wire, a machine speed of 220m / min, and a wire dewatering pressure of 0.15MPa. The dewatered wet paper sheet underwent a three-stage controlled drying process: the first stage was drying at 85℃ for 2 minutes, the second stage at 125℃ for 3 minutes, and the third stage at 165℃ for 2 minutes, to achieve the desired paper quality. The moisture content of the paper was reduced to 3.5%. Finally, an indium tin oxide transparent conductive layer was deposited on the paper surface by magnetron sputtering using an ITO target (mass ratio: In2O3:SnO2:ZnO = 9:1:0.5; the preparation method of the indium tin oxide composite target is as follows: In2O3, SnO2 and ZnO powders are mixed in proportion, ball-milled for 4 hours, wherein the ball-to-material ratio is 5:1, the rotation speed is 300 rpm; sintered at 1100℃ to form a composite target; this composite target is used in magnetron sputtering). The substrate temperature was 110℃, the sputtering power was 230W, the working pressure was 0.6Pa, the argon flow rate was 22sccm, the deposition time was 25 minutes, and the deposition thickness was 70nm. After paper defect monitoring, the final protective paper product was obtained. The thickness of the high-definition electronic screen protector prepared in Example 2 was 0.09mm.

[0043] Example 3

[0044] First, a core-shell structured functional composite fiber was constructed. 80 parts of regenerated cellulose fiber were dispersed in 960 parts of deionized water (solid-liquid ratio 1:12), and stirred at 500 rpm to form a uniform dispersion. Then, 10 parts of pyrrole monomer and 1.5 parts of graphene oxide were added to the system. The mixture was kept at a constant temperature of 3°C in an ice-water bath, and a 5% ammonium persulfate aqueous solution (molar ratio of ammonium persulfate to pyrrole monomer 1:1) was slowly added dropwise at a rate of 1-2 drops / second as an oxidant. After 5 hours of reaction, pyrrole was polymerized in situ on the fiber surface to form a uniform polypyrrole / graphene composite conductive shell with a thickness of 100 nm. Simultaneously, nano-dioxanone nanoparticles were independently surface-modified. The preparation of silica aerogel involved adding 20 parts of tetraethyl orthosilicate as a precursor, along with 200 parts of anhydrous ethanol and 40 parts of deionized water. The pH was adjusted to 3 with hydrochloric acid, and the mixture was stirred and hydrolyzed in a 60°C water bath for 2 hours. The pH was then adjusted to 8 with ammonia, and stirring was continued for 4 hours to form a gel. After supercritical carbon dioxide drying (critical temperature 31°C, critical pressure 7.4 MPa), 8 parts of nano-silica aerogel were obtained. This aerogel was then co-dispersed with 6.4 parts of perfluorodecyltriethoxysilane (mass ratio 1:0.8) in 80 parts of anhydrous ethanol, and the mixture was refluxed at 90°C for 3 hours to complete surface modification. The specific surface area of ​​the surface-modified nano-silica aerogel particles was 600 m². 2 / g; Next, the polyimide fibers (29 short-cut fibers, 3mm in length and 12μm in diameter) were processed. 15 parts of polyimide fibers were soaked in 120 parts of a 2wt% 3-aminopropyltriethoxysilane ethanol solution (solid-liquid ratio 1:8), and the reaction was carried out at 70℃ with shaking for 1.5 hours to complete the silane coupling agent modification. Then, the fibers were washed three times with ethanol. Then, the slurry was composited, and 70% functional composite fibers, 10% surface-modified nano-silica aerogel particles, and 15% modified polyimide fibers were taken by mass percentage. The mixture consists of 2% carboxymethyl chitosan (with a degree of deacetylation of 92% and a number-average molecular weight of 150,000 Da), 2% bio-based wet strength agent, and 0.8% fluorocarbon defoamer. The mixture is then dispersed at 1000 rpm for 30 minutes, followed by low-temperature plasma treatment at 600 W power, an argon to oxygen volume ratio of 4:1, and a working pressure of 50 Pa for 3 minutes to activate the fiber surface. Nanoscale refining is then performed, controlling the refining gap to 15 μm, achieving a freeness of 40°SR, and a wet weight of [missing information]. 5.0g; the paper is produced using a long-wire paper machine with an 80-mesh forming wire, a machine speed of 250m / min, and a wire dewatering pressure of 0.2MPa; the dewatered wet paper sheet undergoes a three-stage controlled drying process: the first stage is drying at 90℃ for 1.5 minutes, the second stage at 130℃ for 2.5 minutes, and the third stage at 170℃ for 1.5 minutes, reducing the paper moisture content to 4.0%; finally, an indium tin oxide transparent conductive layer is deposited on the paper surface by magnetron sputtering using an ITO target (mass ratio: In2O3:SnO2:ZnO = 9: The indium tin oxide composite target material was prepared by mixing In2O3, SnO2, and ZnO powders in a specific ratio, ball milling for 4 hours (ball-to-material ratio 5:1, rotation speed 300 rpm), and sintering at 1100℃ to form the composite target material. During magnetron sputtering (using this composite target material), the substrate temperature was 120℃, sputtering power was 250W, working pressure was 0.8Pa, argon flow rate was 25sccm, deposition time was 30 minutes, and deposition thickness was 80nm. After paper defect monitoring, the final protective paper product was obtained. The high-definition electronic screen protector paper prepared in Example 3 had a thickness of 0.10mm.

[0045] Comparative Example 1

[0046] Comparative Example 1 was conducted according to the traditional method for manufacturing protective paper for liquid crystal substrates: 70 parts of mercerized bleached sulfate softwood pulp and 30 parts of bleached sisal pulp were used as raw materials. After descaling, the pulps were refined using multiple tandem double-disc refiners. The softwood pulp had a refinement pressure of 6 kg / cm², a freeness of 23°SR, and a wet weight of 8.5 g, while the sisal pulp had a refinement pressure of 7 kg / cm², a freeness of 23°SR, and a wet weight of 11.0 g. After refining, the materials were batched and mixed evenly, and then formed into wet paper using a long-wire single-cylinder paper machine at a speed of 320 m / min. The wet paper sheets were sequentially vacuum-suctioned and press-dehydrated, then dried using a 3660mm diameter Yankee drying cylinder at a surface temperature of 140℃. An ion blower was used to deliver hot air at 190℃ and a velocity of 60m / s until the paper moisture content reached 5.0%, yielding the base paper. The base paper was then re-wetted to 7.0% moisture content and subjected to double-sided calendering using a two-roll soft calender. The soft rolls were pre-coated with antistatic material. The calendering temperature was 190℃, and the linear pressure was 90KN / m. After calendering, the paper sheets were destaticated, inspected for paper defects, and then wound up. The high-definition electronic screen protector paper prepared in Comparative Example 1 had a thickness of 0.15mm.

[0047] Comparative Example 2

[0048] Comparative Example 2 uses a conventional antistatic agent instead of a core-shell structure design: 85 parts of regenerated cellulose fiber were used as raw material. Without constructing a core-shell structure, 3 parts of a conventional quaternary ammonium salt antistatic agent (hexadecyltrimethylammonium bromide) were directly added to a mixture with 12 parts of unmodified polyimide fiber. 2% bio-based wet strength agent and 0.8% fluorocarbon defoamer were added. After ordinary descaling and refining, the freeness was 35°SR, and the wet weight was 6.0 g. Subsequently, papermaking, pressing, dewatering, and conventional drying (drying at 150℃ for 5 minutes) were performed, omitting plasma pretreatment and magnetron sputtering surface treatment steps. Paper defect monitoring and winding were then performed directly. The high-definition electronic screen protector paper prepared in Comparative Example 2 had a thickness of 0.12 mm.

[0049] Comparative Example 3

[0050] Comparative Example 3 omitted the nano-silica aerogel component: Core-shell structured functional composite fibers and modified polyimide fibers were constructed using the same process as in Example 1. The slurry ratio was adjusted to 80% functional composite fibers, 15% modified polyimide fibers, 2% bio-based wet strength agent, and 0.8% fluorocarbon defoamer, completely omitting the surface-modified nano-silica aerogel particles. Subsequently, the same plasma pretreatment, nanoscale pulping, paper forming, three-stage controllable drying, and magnetron sputtering surface treatment as in Example 1 were performed. The high-definition electronic screen protector prepared in Comparative Example 3 had a thickness of 0.10 mm.

[0051] Comparative Example 4

[0052] Comparative Example 4 omits magnetron sputtering surface treatment: The same process as in Example 1 was followed for core-shell structured functional composite fiber construction, nano-silica aerogel preparation, fiber composite formation, plasma pretreatment, pulping, paper forming, and controlled drying. However, after obtaining the base paper, paper defect monitoring and winding were performed directly, completely omitting the surface treatment step of magnetron sputtering deposition of the indium tin oxide transparent conductive layer. The high-definition electronic screen protector paper prepared in Comparative Example 4 has a thickness of 0.10 mm.

[0053] Comparative Example 5

[0054] Comparative Example 5 omitted plasma pretreatment: The slurry was prepared according to the same formulation as in Example 1, but nanoscale milling was performed directly after mixing, omitting the plasma pretreatment step; subsequently, the same paper-making, three-stage controlled drying, and magnetron sputtering surface treatment as in Example 1 were performed. The high-definition electronic screen protector paper prepared in Comparative Example 5 had a thickness of 0.10 mm.

[0055] Performance testing

[0056] Test Standards

[0057] Quantitative (g / m 2 Longitudinal tensile strength (kN / m), transverse tensile strength (kN / m), and surface resistivity (MΩ) are referenced in Chinese invention patent CN112593453A;

[0058] Light transmittance (%) and haze (%) are referenced in Chinese invention patent CN110552242B;

[0059] The rate of hair and powder shedding (%) is based on Chinese invention patent CN114166687A;

[0060] Table 1 shows the test results for each embodiment.

[0061]

[0062] Table 2 shows the results of the comparative tests for each item.

[0063]

[0064] Comparing the data in Tables 1 and 2, it can be seen that the protective paper prepared in Examples 1-3 of this invention significantly outperforms all comparative examples in key performance indicators such as light transmittance (94-96%), haze (1.2-1.8%), surface resistivity (20-30 MΩ), longitudinal tensile strength (4.6-5.0 kN / m), and lint and dust shedding rate (0.02-0.04%). This indicates that this invention, through the synergistic innovation of constructing core-shell structured composite fibers (forming a stable conductive network), introducing surface-modified nano-silica aerogel (optimizing optical properties and enhancing mechanical strength), and employing plasma pretreatment and magnetron sputtering surface treatment (enhancing fiber bonding and surface conductivity), has achieved a breakthrough improvement in the protective paper's ultra-thinness, high transmittance, high strength, durable antistatic properties, and high cleanliness, effectively overcoming the performance deficiencies of traditional protective paper caused by limitations in material selection and processes.

[0065] The slight differences in transmittance, tensile strength, and surface resistivity among Examples 1-3 are mainly due to variations in the proportions of core-shell composite fibers, nano-silica aerogel, and modified polyimide fibers in each example, as well as fine-tuning of process parameters such as plasma treatment power, grinding gap, drying temperature, and magnetron sputtering time. For example, Example 1 has a higher content of functional composite fibers (75%) and a longer magnetron sputtering deposition time (35 minutes), resulting in a more complete conductive layer and lower surface resistivity (20 MΩ). Example 2 has a higher aerogel content (12%), which, although slightly lower in transmittance (94%), enhances mechanical properties. Example 3 exhibits moderate parameters and balanced performance. These differences reflect the precise control of component ratios and process conditions on the final product performance.

[0066] Analysis of the reasons for the differences between the test results of the Example and Comparative Example 1:

[0067] Comparative Example 1 uses traditional natural fiber raw materials and conventional processes, without introducing functional composite fibers, nano-aerogels, and surface treatment technologies. This results in low light transmittance (85%), high haze (8.0%), poor tensile strength, and extremely high surface resistivity (1500 MΩ). The fundamental reason for this is the lack of the core-shell conductive structure, nano-reinforcing phase, and surface functionalization design found in this invention. This prevents the achievement of optical calibration, charge dissipation, and fiber interface strengthening, thus resulting in a comprehensive lag in optical, mechanical, and antistatic properties.

[0068] Analysis of the reasons for the differences between the test results of Example 1 and Comparative Example 2:

[0069] Comparative Example 2 used a conventional quaternary ammonium salt antistatic agent, but failed to construct a core-shell conductive structure, resulting in a surface resistivity as high as 1100 MΩ and unstable antistatic performance. This is because quaternary ammonium salts are prone to migration and decomposition, failing to form a durable conductive network; at the same time, the omission of plasma and magnetron sputtering treatments resulted in weak fiber bonding, high lint and powder shedding rate (0.3%), and decreased optical performance (transmittance 88%) due to the lack of light-guiding effect of nano-aerogels.

[0070] Analysis of the reasons for the differences between the test results of the Example and Comparative Example 3:

[0071] Comparative Example 3 omitted the nano-silica aerogel, resulting in a significant decrease in light transmittance (87%) and tensile strength (3.7 kN / m longitudinally), while the haze increased to 4.5%. The reason is that the nanoporous structure of the aerogel plays a key role in light scattering suppression and mechanical enhancement in this invention. Without it, the internal optical path of the paper is disordered, the interfiber bonding is not tight, and the optical uniformity and overall strength are affected.

[0072] Analysis of the reasons for the differences between the test results of Example 1 and Comparative Example 4:

[0073] Comparative Example 4 omitted the magnetron sputtering surface treatment. Although it retained the core-shell fiber and aerogel, the surface resistivity increased to 200 MΩ, and the shedding rate (0.14%) was higher than that of the Example. This is because the lack of the surface charge dissipation ability and surface densification effect of the ITO transparent conductive layer leads to a decrease in antistatic properties and surface smoothness, affecting the cleanliness and electrostatic protection effect during use.

[0074] Analysis of the reasons for the differences between the test results of the Example and Comparative Example 5:

[0075] Comparative Example 5 omitted plasma pretreatment, resulting in weakened interfiber bonding, a decrease in longitudinal tensile strength to 4.3 kN / m, and an increase in lint and dust shedding rate to 0.11%. This is because plasma treatment can activate the fiber surface and improve interfacial compatibility; without it, the fibers are not firmly bonded to the matrix, affecting the overall strength and cleanliness of the paper, although the electrical and optical properties are less affected.

[0076] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a high-definition electronic screen protector, characterized in that, Includes the following steps: S1. Functional composite fibers with core-shell structure: using regenerated cellulose fibers as the core layer, and constructing a polypyrrole / graphene composite conductive layer as the shell layer on its surface through in-situ polymerization. S2. Preparation of surface-modified nano-silica aerogel particles: Nano-silica aerogels are prepared by sol-gel method and then surface-modified with fluorinated silanes. S3. Preparation of silane coupling agent modified polyimide fibers: Polyimide fibers are surface modified by immersing them in an ethanol solution of 3-aminopropyltriethoxysilane. S4. Fiber composite: The core-shell structured functional composite fiber obtained in step S1, the surface-modified nano-silica aerogel particles obtained in step S2, and the silane coupling agent modified polyimide fiber obtained in step S3 are mixed, and a bio-based wet strength agent and a fluorocarbon defoamer are added. After plasma pretreatment, the mixture is polished to obtain a mixed slurry. S5. The pulp mixture from step S4 is subjected to wire bonding to obtain a shaped wet paper sheet. S6. The wet paper sheet formed in step S5 is sequentially subjected to vacuum suction, pressing dehydration, and controlled drying until the paper moisture content is 3.0-5.0% to obtain the base paper; S7. The paper from step S6 is subjected to surface treatment by magnetron sputtering to deposit a transparent conductive layer of indium tin oxide with a thickness of 50-100nm. S8. The paper sheet processed in step S7 is subjected to paper defect monitoring and winding to obtain high-definition electronic screen protector paper. The preparation of the core-shell structured functional composite fiber in step S1 includes: dispersing regenerated cellulose fibers in deionized water to form a dispersion with a solid-liquid ratio of 1g:(10-15)mL, adding pyrrole monomer and graphene oxide, and adding a 3-6% ammonium persulfate aqueous solution as an oxidant at a rate of 1-2 drops / second in an ice-water bath at 0-5℃, reacting for 4-6 hours, wherein the mass ratio of pyrrole monomer to regenerated cellulose fibers is 1:(5-10), the amount of graphene oxide added is 10-20% of the mass of pyrrole monomer, and the molar ratio of ammonium persulfate to pyrrole monomer is (0.8-1.2):1; in the core-shell structured functional composite fiber, the thickness of the polypyrrole / graphene composite conductive layer is 50-200nm; The preparation of surface-modified nano-silica aerogel particles in step S2 includes: using tetraethyl orthosilicate as a precursor, mixing it with anhydrous ethanol and deionized water at a mass ratio of 1:(8-12):(1.5-2.5), adjusting the pH to 2.5-3.5 with acid, hydrolyzing at 50-70℃ for 1.5-2.5 hours, then adjusting the pH to 7.5-8.5 with alkali and performing condensation polymerization for 3-5 hours to form a gel. After drying with supercritical carbon dioxide, nano-silica aerogel is obtained, which is then co-dispersed with perfluorodecyltriethoxysilane at a mass ratio of 1:(0.7-0.9) in anhydrous ethanol and refluxed at 80-100℃ for 2-4 hours to complete the surface modification; the specific surface area of ​​the surface-modified nano-silica aerogel particles is 500-800 m² / g. 2 / g.

2. The method according to claim 1, characterized in that, The preparation of silane coupling agent modified polyimide fibers in step S3 includes: immersing polyimide short-cut fibers with a length of 2-4 mm and a diameter of 10-15 μm in a 1-3 wt% 3-aminopropyltriethoxysilane ethanol solution with a solid-liquid ratio of 1 g: (6-10) mL, and reacting at a constant temperature of 60-80℃ with shaking for 1-2 hours. After the reaction is completed, the fibers are washed 2-4 times with ethanol.

3. The method according to claim 1, characterized in that, The mixed slurry in step S4 consists of the following components by mass percentage: 60-80% core-shell structured functional composite fibers, 5-15% surface-modified nano-silica aerogel particles, 10-20% silane coupling agent modified polyimide fibers, 1-3% bio-based wet strength agent, and 0.5-1% fluorocarbon defoamer; the bio-based wet strength agent is a chitosan derivative with a degree of deacetylation ≥85%; the chitosan derivative is any one of carboxymethyl chitosan, hydroxypropyl chitosan, or quaternized chitosan; the molecular weight of the chitosan derivative is 50,000-200,000 Da.

4. The method according to claim 1, characterized in that, The conditions for plasma pretreatment in step S4 are as follows: low-temperature plasma treatment is used, the power is 500-800W, the treatment time is 2-5 minutes, the working pressure is 40-60Pa, and the gas is a mixture of argon and oxygen with a volume ratio of argon to oxygen of (3-5):

1.

5. The method according to claim 1, characterized in that: In step S4, the pulping process employs nanoscale pulping technology, with a pulping gap of 10-20 μm and a beating degree of 35-45°SR.

6. The method according to claim 1, characterized in that, In step S6, the controllable drying adopts a three-stage drying process: the first stage temperature is 80-100℃, and the drying time is 1-2 minutes; the second stage temperature is 120-140℃, and the drying time is 2-3 minutes; the third stage temperature is 160-180℃, and the drying time is 1-2 minutes. The temperature deviation of each stage is controlled within ±2℃.

7. The method according to claim 1, characterized in that, The process parameters for magnetron sputtering surface treatment in step S7 are as follows: using an indium tin oxide composite target, substrate temperature 100-150℃, sputtering power 200-300W, working pressure 0.5-1.0Pa, argon flow rate 20-30sccm, and deposition time 20-40 minutes; the preparation method of the indium tin oxide composite target is as follows: mixing In2O3, SnO2, and ZnO powders in a certain proportion, wherein the mass ratio of In2O3 to SnO2 to ZnO is (8-10):1:(0.5-1), ball milling for 4-6 hours at a speed of 300-500rpm; sintering at 1000-1200℃ to form a composite target; using this composite target during magnetron sputtering.

8. A high-definition electronic screen protector, characterized in that, It is prepared by the method described in any one of claims 1-7.

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