Optical adhesive and method for preparing the same, display screen

Abstract

This application discloses an optical adhesive, its preparation method, and a display screen. The optical adhesive includes a resin matrix and a dehumidifying additive. The dehumidifying additive includes a modified porous material. The modified porous material includes a porous material matrix, an aminosilane coupling agent linked to hydroxyl groups on the surface of the porous material matrix, and an acrylate grafted with amino groups of the aminosilane coupling agent. On one hand, the hydroxyl and amino groups on the surface of the modified porous material chemically adsorb water molecules through hydrogen bonds. On the other hand, the porous structure of the modified porous material can undergo capillary condensation to form multilayer adsorption, trapping water molecules within the modified porous material. This allows the optical adhesive to maintain structural stability under hygroscopic conditions, thereby reducing the moisture content around the silver paste lines and fundamentally reducing silver ion migration caused by moisture intrusion into the silver paste lines, thus improving the long-term operational reliability of the display screen.

Description

Technical Field

[0001] This application relates to the field of optical adhesive material preparation, and in particular to an optical adhesive, its preparation method, and a display screen. Background Technology

[0002] In the module integration stage of displays, optical adhesives (OCAs) are the core bonding materials. Acrylic optical adhesives are widely used due to their excellent bonding performance. Among them, acrylic optical adhesives use polyurethane acrylate (PUA) or epoxy acrylate as the matrix.

[0003] However, acrylic optical adhesives have a significant drawback – a water absorption rate as high as 0.5% to 1%. In high-temperature and high-humidity environments, the adhesive layer will absorb a large amount of moisture, thus affecting the long-term reliability of the display screen. Summary of the Invention

[0004] In view of this, this application provides an optical adhesive, a method for preparing the same, and a display screen to improve the self-dehumidifying performance of the optical adhesive.

[0005] To solve the above-mentioned technical problems, the first technical solution adopted in this application is: to provide an optical adhesive, comprising: a resin matrix and a dehumidifying additive; the dehumidifying additive comprises a modified porous material; the modified porous material comprises a porous material matrix, an aminosilane coupling agent linked to hydroxyl groups on the surface of the porous material matrix, and an acrylate grafted with amino groups of the aminosilane coupling agent.

[0006] In one embodiment, the average pore size of the modified porous material is 2 nm to 5 nm; and / or, The volumetric porosity of the modified porous material is 40%~70%; and / or, The modified porous material has a specific surface area of ​​300 m². 2 / g~2000m 2 / g.

[0007] In one embodiment, the porous material matrix includes one or more of porous silica, porous alumina, and MOF@SiO2.

[0008] In one embodiment, the aminosilane coupling agent comprises an aminoalkoxysilane coupling agent.

[0009] In one embodiment, the aminosilane coupling agent includes one or more of γ-aminopropyltriethoxysilane coupling agent, γ-aminopropyltrimethoxysilane, and N-β-aminoethyl-γ-aminopropyltriethoxysilane.

[0010] In one embodiment, the acrylate includes a hydroxyacrylate.

[0011] In one embodiment, the acrylate includes one or more of hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and hydroxybutyl methacrylate.

[0012] In one embodiment, the molar ratio of the resin matrix to the dehumidifying additive is 15:1 to 30:1.

[0013] In one embodiment, the optical adhesive further includes an infrared blocking additive, which includes one or more of infrared reflective additives and infrared absorbing additives.

[0014] In one embodiment, the infrared reflective additive includes one or more of ITO nanoparticles, AZO nanoparticles, and GZO nanoparticles; and / or, The infrared absorbing additive includes one or more of polyethyleneimine and polylysine.

[0015] In one embodiment, the infrared blocking additive includes an infrared reflecting additive and an infrared absorbing additive, wherein the infrared reflecting additive includes ITO nanoparticles and the infrared absorbing additive includes polyethyleneimine.

[0016] In one embodiment, the average particle size of the ITO nanoparticles is 30 nm-50 nm; and / or, The molar ratio of indium oxide to tin oxide in the ITO nanoparticles is 4:1 to 12:1. The resistivity of the ITO nanoparticles is less than 100 Ω·cm.

[0017] In one embodiment, the weight-average molecular weight of the polyethyleneimine is 1000 Da to 3000 Da.

[0018] In one embodiment, the infrared blocking additive includes an infrared reflecting additive and an infrared absorbing additive, wherein the mass ratio of the infrared reflecting additive to the infrared absorbing additive is (3-5):1.

[0019] In one embodiment, the molar ratio of the resin matrix to the infrared blocking additive is 50:1 to 100:1.

[0020] In one embodiment, the resin matrix comprises polyurethane acrylate and isobornyl methacrylate, wherein the molar ratio of polyurethane acrylate to isobornyl methacrylate is 2:1 to 4:1.

[0021] The second technical solution adopted in this application is: providing a method for preparing optical adhesive, comprising: Obtain a resin matrix and a dehumidifying additive; wherein the dehumidifying additive includes a modified porous material; the modified porous material includes a porous material matrix, an aminosilane coupling agent linked to hydroxyl groups on the surface of the porous material matrix, and an acrylate grafted with amino groups of the aminosilane coupling agent. The dehumidifying additive is mixed with the resin matrix to obtain a mixed adhesive solution; The mixed adhesive solution is applied to a carrier, cured, and then post-treated to obtain the optical adhesive.

[0022] In one embodiment, the method for preparing the dehumidifying additive includes: Obtain a porous material matrix; A porous material matrix is ​​dispersed in a first solvent to form a first suspension; The aminosilane coupling agent is dissolved in a second solvent to form an aminosilane coupling agent solution; The aminosilane coupling agent solution is added to the first suspension and refluxed at 75℃~90℃ for 10h~14h, while controlling the moisture content to be less than 100ppm, to obtain a porous material matrix grafted with aminosilane coupling agent. The porous material matrix grafted with the aminosilane coupling agent, the acrylate, the activator and the catalyst are mixed and reacted at 55℃~65℃ for 20h~28h under an inert atmosphere to obtain the modified porous material.

[0023] In one embodiment, the mass ratio of the porous material matrix to the aminosilane coupling agent is 5:1 to 20:1; and / or, The molar ratio of the acrylate to the aminosilane coupling agent is 1:1 to 1.5:1; and / or, The molar ratio of the activator to the acrylate is 1:1 to 1.5:1; and / or, The molar ratio of the catalyst to the acrylate is 0.1:1 to 0.5:1.

[0024] In one embodiment, the step of mixing the dehumidifying additive with the resin matrix to obtain a mixed adhesive further includes: The dehumidifying additive is mixed with the resin matrix to obtain a first mixture; An infrared blocking additive is added to the first mixture to obtain the mixed adhesive; wherein the infrared blocking additive includes one or more of infrared reflective additives and infrared absorbing additives.

[0025] In one embodiment, the infrared blocking additive includes an infrared reflecting additive and an infrared absorbing additive, wherein the infrared reflecting additive includes ITO nanoparticles and the infrared absorbing additive includes polyethyleneimine; the preparation method of the infrared blocking additive includes: The ITO nanoparticles are dispersed in a third solvent to form a second suspension; The polyethyleneimine is dissolved in a fourth solvent to form a polyethyleneimine solution; Under conditions of 25°C or less, the polyethyleneimine solution is added to the second suspension to obtain a second mixture; wherein, during the addition of the polyethyleneimine solution, the pH of the solution is maintained at 9-10. The second mixture was reacted at 55℃~100℃ for 3h~5h, washed, and dried to obtain the infrared blocking additive.

[0026] In one embodiment, the mass ratio of the ITO nanoparticles to the polyethyleneimine is (3-5):1.

[0027] In one embodiment, the step of coating the mixed adhesive onto a carrier, curing, and post-processing to obtain the optical adhesive includes: The mixed adhesive solution is applied onto the carrier; The mixed adhesive solution is first cured using a first light source with a wavelength of 360nm~370nm; wherein the power of the first light source is 50mW / cm². 2 ~100mW / cm 2 The irradiation time is 2 to 5 minutes; The mixed adhesive is cured a second time using a second light source with a wavelength of 400nm to 410nm; wherein the power of the second light source is 150mW / cm². 2 ~300mW / cm 2 The irradiation time is 3 to 8 minutes; The cured adhesive layer is placed in an environment with a temperature of 35℃~45℃ and a humidity of 20%~40% for 1h~3h to obtain the optical adhesive.

[0028] The third technical solution adopted in this application is: providing a display screen, including: a functional layer, a cover plate and an optical adhesive, wherein the optical adhesive is disposed between the functional layer and the cover plate, and the optical adhesive includes the optical adhesive described in any one of the above claims or the optical adhesive prepared by the preparation method of the optical adhesive described in any one of the above claims.

[0029] The beneficial effects of this application are as follows: This application provides an optical adhesive and its preparation method, as well as a display screen. The optical adhesive includes a resin matrix and a dehumidifying additive; the dehumidifying additive includes a modified porous material; the modified porous material includes a porous material matrix, an aminosilane coupling agent linked to hydroxyl groups on the surface of the porous material matrix, and an acrylate grafted with amino groups of the aminosilane coupling agent. On one hand, the hydroxyl and amino groups on the surface of the modified porous material undergo chemical adsorption with water molecules through hydrogen bonds; on the other hand, the porous structure of the modified porous material can undergo capillary condensation, forming a multilayer adsorption, capturing water molecules within the modified porous material. This allows the optical adhesive to maintain structural stability under hygroscopic conditions, thereby reducing the moisture content around the silver paste lines, fundamentally reducing silver ion migration caused by moisture intrusion into the silver paste lines, and improving the long-term operational reliability of the display screen. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic flowchart of the method for preparing the optical adhesive provided in the embodiments of this application; Figure 2 This is a schematic flowchart of the preparation method of the dehumidifying additive provided in the embodiments of this application; Figure 3 This is a schematic flowchart of the preparation method of the infrared blocking additive provided in the embodiments of this application; Figure 4 This is a flowchart illustrating step S03 of the method for preparing optical adhesive provided in this application embodiment. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that the terms "first" and "second" in this application are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0033] In the module integration stage of displays, optical adhesive (OCA) is a core bonding material. Currently, commonly used optical adhesives include acrylic optical adhesives and silicone optical adhesives.

[0034] In related technologies, silicone optical adhesives utilize hydroxyl-terminated polydimethylsiloxane (PDMS) combined with a crosslinking agent (such as methyltrimethoxysilane). The characteristics of silicone optical adhesives are: resistance to high and low temperatures (-50~200℃), good hydrophobicity (contact angle >110°), light transmittance of 85%, and high-temperature curing: 80-120℃. However, silicone optical adhesives are not suitable for bonding polycarbonate (PC), polyethylene terephthalate (PET), and other similar panels.

[0035] In related technologies, acrylate-based optical adhesives use polyurethane acrylate (PUA) or epoxy acrylate as the matrix, combined with a UV photoinitiator. Acrylic-based optical adhesives have a visible light transmittance of over 90% and excellent adhesion. However, acrylate-based optical adhesives have a significant drawback—a water absorption rate as high as 0.5% to 1%, and generally poor weather resistance (500h damp heat test). In high-temperature and high-humidity environments, the adhesive layer absorbs a large amount of moisture. For example, when acrylate-based optical adhesives are used in displays, the sensor layer is the core area for touch sensing. It typically uses ITO (indium tin oxide) conductive patterns to sense touch signals, which are transmitted via silver paste lines. Moisture intrusion can damage the stability of the silver paste lines, triggering an electrolytic reaction and promoting silver ion migration, leading to short circuits, display malfunctions, and other issues, threatening the long-term performance of the display. The mechanism of silver migration in silver paste wires is as follows: Silver migration refers to the phenomenon where, in a humid environment (typically 60% RH) with a DC voltage gradient (usually above 3V), water molecules penetrate the surface of the silver-containing conductor and electrolyze to form hydrogen ions and hydroxide ions. The electrolysis reaction is H2O. H + +OH- Silver dissociates to produce silver ions under the influence of an electric field and hydroxide ions: Ag → Ag + +e Ag + With OH - Combined to form silver hydroxide (AgOH), Ag + +OH → AgOH, but AgOH is extremely unstable and rapidly decomposes into Ag₂O, 2AgOH → Ag₂O + H₂O, Ag + Under the influence of an electric field, Ag migrates towards the cathode (low potential), and may form a complex along the way. + It gains electrons and is reduced to Ag atoms, which then aggregate into dendritic deposits. + +e →Ag, dendrite growth may pierce the insulation layer, leading to a short circuit.

[0036] To address the issue of silver migration in silver paste lines caused by the high water absorption rate of acrylate-based optical adhesives, one solution involves coating the surface of the transparent conductive film of the silver nanowires with an ultrathin and transparent insulating layer. This insulating layer, positioned above the silver paste, completely isolates the surface of the conductive film from the external environment, preventing contact between the silver nanowires and air. This overcomes the drawbacks of decreased chemical stability and conductivity in the conductive film caused by electro-corrosion and silver migration. Another solution is to increase the distance between the signal and ground planes, thereby increasing the silver migration distance. However, neither of these solutions addresses the problem by reducing moisture around the silver paste lines.

[0037] Based on the technical need to reduce the moisture content around the silver paste line to inhibit silver migration, the relevant technical solution provides a hygroscopic hydrogel, which is prepared by polymerization reaction of zwitterionic monomers and hydrophilic monomers in a hygroscopic salt solution system; the types of hygroscopic salts include, but are not limited to, lithium chloride, calcium chloride, magnesium chloride, cobalt chloride, lithium bromide, calcium bromide, magnesium bromide, magnesium sulfate, sodium sulfate, copper sulfate, lithium nitrate and calcium nitrate, etc. However, such hygroscopic hydrogels have significant performance defects and application limitations, making them difficult to adapt to the actual usage requirements of display modules: First, they lack mechanical strength. The mechanical properties of this hydrogel are weak, making it unable to withstand high load conditions or long-term stress, and it is prone to deformation and breakage. Second, they are highly sensitive to the environment. The structural stability of this hydrogel is highly dependent on moisture. In dry environments, it is prone to embrittlement and cracking due to water loss. In high-temperature or high-humidity environments, it may over-swell or even degrade, which will negatively affect the bonding stability between various components of the module and make it unsuitable as a functional adhesive such as optical adhesive to achieve the curing and bonding function between two structural components. Third, the thickness is incompatible with the module design. The thickness of the hydrogel material prepared by this technology can reach 3mm, while current modules are developing towards ultra-thinness, and the limit of its overall thickness has been reduced to 3mm. Moreover, the thickness range of optical adhesives actually used in modules is only 0.075mm~0.25mm. The thickness of this hydrogel far exceeds the size requirements of display modules for functional materials and cannot meet the assembly requirements of ultra-thin designs.

[0038] In view of this, embodiments of this application provide an optical adhesive and its preparation method, as well as a display screen, to improve the self-hygroscopic properties of the optical adhesive, reduce the moisture content around the silver paste lines, inhibit silver migration, and improve the temperature and humidity tolerance of the display screen.

[0039] This application provides an optical adhesive comprising a resin matrix and a dehumidifying additive; the dehumidifying additive comprises a modified porous material; the modified porous material comprises a porous material matrix, an aminosilane coupling agent linked to hydroxyl groups on the surface of the porous material matrix, and an acrylate grafted with an amino group of the aminosilane coupling agent.

[0040] A porous material matrix refers to a solid material framework with a continuous three-dimensional network structure and rich in interconnected pores.

[0041] The hydroxyl groups on the surface of porous material matrices can be either primary or secondary. Primary hydroxyl groups are surface groups directly introduced during the synthesis or preparation of porous materials, and their origin is closely related to the precursor characteristics and synthetic reaction pathway. Secondary hydroxyl groups are surface groups introduced after the porous material is prepared, through subsequent treatment or interaction with the environment.

[0042] For example, porous silica is typically prepared using silanols (such as tetraethyl orthosilicate and methyl orthosilicate) as precursors. Under acidic (pH 2-5) or alkaline (pH > 10) catalytic conditions, the alkoxy groups (-OR) in the silanol molecules undergo hydrolysis with water molecules to generate hydrolysis products containing silanol groups (Si-OH). Subsequently, condensation reactions occur between the silanol groups, forming Si-O-Si bonds to construct a three-dimensional porous framework of silica. Since the condensation reaction cannot proceed completely, a large number of uncondensed silanol groups remain on the surface and inner walls of the porous framework. These hydroxyl groups are primary hydroxyl groups directly formed during the synthesis of porous silica. After the porous silica is prepared, if the silicon atoms on the surface of the porous silica are in an unsaturated coordination state due to framework defects, they will spontaneously adsorb water molecules from the air when exposed to air. The water molecules dissociate and adsorb at the unsaturated silicon sites, and the hydroxyl groups combine with the silicon atoms, while the hydrogen ions combine with the adjacent oxygen atoms, thereby forming secondary hydroxyl groups.

[0043] Aminosilane coupling agents are silane coupling agents whose molecular structure contains amino groups. Aminosilane coupling agents hydrolyze to generate silanol intermediates (Si-OH). These silanol intermediates (Si-OH) undergo a dehydration condensation reaction with hydroxyl groups on the surface of the porous material matrix, anchoring the aminosilane coupling agent to the surface of the porous material matrix and introducing amino groups onto the surface of the porous material matrix.

[0044] On the one hand, the modified porous material inherits the pore structure of the porous material matrix. This pore structure can adsorb water molecules, achieving capillary condensation, allowing water molecules to form multilayers through physical adsorption under high humidity conditions. It should be noted that the coupling reaction between the porous material matrix and the aminosilane coupling agent, and the grafting reaction between the aminosilane coupling agent and the acrylate, do not damage the pore structure of the porous material matrix. Therefore, the modified porous material inherits the pore structure of the porous material matrix, maintaining a high specific surface area for water vapor adsorption.

[0045] On the other hand, the hydroxyl groups on the surface of the porous material matrix are linked to aminosilane coupling agents, introducing amino functional groups. The residual amino groups that did not participate in the grafting reaction can chemically adsorb water molecules through hydrogen bonds. At the same time, the residual hydroxyl groups on the surface of the porous material that did not participate in the coupling reaction can also interact strongly with water molecules through hydrogen bonds. This hydrogen bond-based adsorption can effectively fix water molecules, thereby enhancing the material's moisture absorption capacity and humidity stability.

[0046] Through the chemical bonding structure between the porous material matrix and the aminosilane coupling agent, under low relative humidity conditions (≤RH40%), water molecules are mainly chemically adsorbed onto the amino and hydroxyl groups of the modified porous material via hydrogen bonds. Under high relative humidity conditions (>RH40%), capillary condensation occurs mainly through the pore structure of the modified porous material, forming multilayer physical adsorption, which traps water molecules within the modified porous material, achieving a gradient dehumidification function. The pore structure of the modified porous material and the effects of the amino and hydroxyl groups enable the optical adhesive to maintain structural stability under hygroscopic conditions, thereby helping to reduce the moisture content around the silver paste lines. This reduces the migration of silver ions caused by moisture intrusion into the silver paste lines at the source, improving the long-term operational reliability of the display screen.

[0047] Furthermore, the carboxyl and amino groups of the acrylate undergo esterification, and the grafting of the acrylate with the amino groups of the aminosilane coupling agent reduces the aggregation of the modified porous material in the resin matrix through the steric hindrance effect of the grafted acrylate. This improves the compatibility of the optical adhesive material in humid and hot environments and reduces the risk of decreased light transmittance due to interfacial hydration or refractive index changes after moisture absorption. Through the grafting of the acrylate with the amino groups of the aminosilane coupling agent, the modified porous material forms an organic-inorganic hybrid structure. The hydroxyl groups on the surface of the modified porous material form stable interfacial bonds with the resin matrix (such as -C=O, -OH) through hydrogen bonds. The strength of this interaction is higher than that of the hydrogen bonds between the porous material and water molecules, ensuring the stability of the optical adhesive material under humidity conditions.

[0048] It should be noted that the grafting reaction of acrylate with aminosilane coupling agent only consumes part of the amino group, and the remaining amino group can adsorb water molecules through hydrogen bonds.

[0049] The specific composition testing methods for the resin matrix of optical adhesives are as follows: one or more of the following methods are used: Fourier transform infrared spectroscopy (FTIR) to qualitatively identify functional groups, nuclear magnetic resonance spectroscopy (NMR) to resolve molecular structure, and gel permeation chromatography (GPC) to determine molecular weight and distribution.

[0050] The specific testing method for the dehumidifying additives in optical adhesives is to use one or more of the following methods: X-ray diffraction (XRD) and nitrogen adsorption-desorption (BET).

[0051] In one embodiment, the average pore size of the modified porous material is 2 nm to 5 nm; and / or, the volume porosity of the modified porous material is 40% to 70%; and / or, the specific surface area of ​​the modified porous material is 300 m². 2 / g~2000m 2 / g.

[0052] By designing the average pore size of the modified porous material as described above, the modified material maintains a strong adsorption capacity for water vapor, enabling water molecules to effectively form multilayer adsorption through capillary condensation under high humidity conditions. The average pore size of the modified porous material can be 2nm, 3nm, 4nm, 5nm, or any range of two of the above values, such as 2nm~4nm, 3nm~5nm, etc.

[0053] By designing the volumetric porosity of the modified porous material as described above, sufficient channels are ensured for water molecule adsorption while maintaining structural stability. This reduces the decrease in light transmittance caused by particle agglomeration after moisture absorption, thereby maintaining the transparency and interfacial bonding of the optical adhesive. The volumetric porosity of the modified porous material can be 40%, 50%, 60%, 70%, etc., or it can be a range of any two of the above values, such as 40%~60% or 50%~70%.

[0054] By designing the specific surface area of ​​the modified porous material as described above, a large number of adsorption sites can be provided. This allows water molecules to chemically adsorb onto the amino and hydroxyl groups on the material's surface via hydrogen bonding under low relative humidity conditions, and to achieve multilayer adsorption through capillary condensation under high relative humidity conditions, thereby improving the moisture absorption rate and capacity. The specific surface area of ​​the modified porous material can be 300 m². 2 / g、500m 2 / g、800m 2 / g, 1000m 2 / g、1200m 2 / g, 1400m 2 / g, 1500m 2 / g, 1600m 2 / g、1800m 2 / g、2000m 2 / g, etc., can also be a range consisting of any two of the above values, for example, 300m. 2 / g~800m 2 / g, 1500m 2 / g~2000m 2 / g、500m 2 / g~1500m 2 / g etc.

[0055] In one embodiment, the porous material matrix includes one or more of porous silica, porous alumina, and MOF@SiO2 materials.

[0056] By specifying the exact type of porous material matrix, optical adhesives can select the most suitable matrix for each application scenario, further improving dehumidification performance. By selecting porous materials with specific average pore size, volumetric porosity, and specific surface area, water molecules can chemically adsorb onto the material surface via hydrogen bonds under low relative humidity conditions, and physically adsorb into a multi-molecular layer through capillary condensation under high relative humidity conditions, thus achieving a more efficient gradient dehumidification function. Furthermore, by using different types of porous materials, the dehumidification stability of the optical adhesive under various environmental conditions is optimized, which helps extend the lifespan of the display screen.

[0057] Optionally, the specific surface area of ​​the porous silica is 600 m². 2 / g~2000m 2 / g.

[0058] Optionally, the specific surface area of ​​porous alumina is 300 m². 2 / g~800m 2 / g.

[0059] Optionally, the specific surface area of ​​the MOF@SiO2 material is 500 m². 2 / g~1500m 2 / g.

[0060] In the case where the porous material matrix includes porous silica, modified silica is obtained by modifying the porous silica. The optical adhesive formed by mixing the modified silica and the resin matrix can be applied to the display screen to solve the silver migration problem of the silver paste line.

[0061] When the porous material matrix includes porous silica, the unsaturated coordinated silicon atoms on the surface of the porous silica spontaneously react with water molecules in the environment to form silanol groups (Si-OH). The aminosilane coupling agent undergoes a hydrolysis reaction to generate a silanol intermediate (Si-OH). The silanol intermediate undergoes a dehydration condensation reaction with the silanol groups on the surface of the porous silica to form a stable Si-O-Si covalent bond. The aminosilane coupling agent is anchored on the surface of the porous silica. At the same time, amino functional groups are introduced into the surface of the porous silica. The amino groups can chemically adsorb water molecules through hydrogen bonds, effectively fixing water molecules, thereby enhancing the material's moisture absorption capacity and humidity stability.

[0062] In one embodiment, the aminosilane coupling agent includes an aminoalkoxysilane coupling agent.

[0063] Aminoalkoxysilane coupling agents are silane coupling agents whose molecular structure contains both amino and alkoxy groups. During hydrolysis, the alkoxy group (such as ethoxy or methoxy) is replaced by a hydroxyl group (-OH), forming a silanol intermediate (Si-OH), which promotes the dehydration condensation reaction with hydroxyl groups on the surface of the porous material matrix. Due to the strong leaving ability of the alkoxy group, the hydrolysis reaction is highly efficient, and the silanol intermediate generated after hydrolysis can rapidly dehydrate and condense with the hydroxyl groups on the surface of the porous material matrix to form stable covalent bonds.

[0064] By designing aminosilane coupling agents, including aminoalkoxysilane coupling agents, these agents can efficiently hydrolyze and form stable covalent bonds with the porous material matrix, ensuring the material maintains structural stability under hygroscopic conditions and reducing the risk of silver ion migration caused by moisture intrusion into the silver paste lines.

[0065] In one embodiment, the aminosilane coupling agent includes one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-β-aminoethyl-γ-aminopropyltriethoxysilane.

[0066] By designing aminosilane coupling agents as the above materials, aminoalkoxysilane coupling agents can be efficiently hydrolyzed and form stable covalent bonds with the porous material matrix, ensuring that the material maintains structural stability under hygroscopic conditions and reducing the risk of silver ion migration caused by moisture intrusion in the silver paste lines.

[0067] In one embodiment, the acrylate includes a hydroxyacrylate.

[0068] Hydroxyacrylates are organic compounds whose molecular structure contains both acrylate functional groups and hydroxyl groups. By designing acrylates including hydroxyacrylates, the carboxyl and amino groups of hydroxyacrylates undergo esterification reactions to graft flexible segments onto the surface of porous material matrices, forming an organic-inorganic hybrid structure. This improves the compatibility of the modified porous material with the resin matrix. Simultaneously, the residual hydroxyl groups of the hydroxyacrylates that are not bound to the resin matrix undergo chemisorption with water molecules through hydrogen bonds, further enhancing the material's adsorption capacity for water molecules. This ensures that the material maintains structural stability under hygroscopic conditions and reduces the risk of silver ion migration caused by moisture intrusion into the silver paste lines.

[0069] In one embodiment, the acrylate includes one or more of hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and hydroxybutyl methacrylate.

[0070] By designing acrylates including the aforementioned materials, the carboxyl and amino groups of the acrylates undergo esterification to graft flexible segments onto the surface of the porous material matrix, forming an organic-inorganic hybrid structure. This improves the compatibility between the modified porous material and the resin matrix. Simultaneously, the residual hydroxyl groups of the acrylates that are not combined with the resin matrix undergo chemical adsorption with water molecules through hydrogen bonds, further enhancing the material's adsorption capacity for water molecules. This ensures that the material maintains structural stability under hygroscopic conditions and reduces the risk of silver ion migration caused by moisture intrusion into the silver paste lines.

[0071] In one embodiment, the molar ratio of the resin matrix to the dehumidifying additive is 15:1 to 30:1.

[0072] By controlling the molar ratio of the resin matrix to the dehumidifying additive within the above range, the dehumidifying additive is uniformly dispersed in the resin matrix, avoiding particle agglomeration that leads to a decrease in light transmittance. At the same time, it ensures sufficient moisture absorption capacity of the optical adhesive, ensures the structural stability of the optical adhesive in a moisture-absorbing state, reduces the water vapor concentration around the silver paste lines, improves the silver ion migration problem caused by water vapor intrusion into the silver paste lines, and improves the long-term operational reliability of the display screen.

[0073] The molar ratio of the resin matrix to the dehumidifying additive can be 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, etc., or it can be a range of any two of the above values, such as 15:1~20:1, 18:1~28:1, etc.

[0074] In one embodiment, the optical adhesive further includes an infrared blocking additive, which includes one or more of infrared reflective additives and infrared absorbing additives.

[0075] By using infrared reflective additives to reflect infrared radiation, the optical adhesive can reduce the temperature rise of the module caused by direct sunlight, resulting in a higher blocking rate of the optical adhesive for the infrared band and improving the working stability of the display screen in high-temperature environments.

[0076] Infrared radiation is absorbed by infrared absorbing additives, reducing heat accumulation in the module and improving the stability of the display screen in high-temperature environments.

[0077] By utilizing infrared reflective additives and / or infrared absorber additives, the opacity of traditional infrared coatings in the visible light band is avoided, thus maintaining the high visible light transmittance of the optical adhesive.

[0078] The optical adhesive includes both dehumidifying additives and infrared blocking additives. While achieving self-dehumidification, the optical adhesive also has infrared heat insulation function, improving the weather resistance and stability of the display screen.

[0079] The testing methods for infrared reflective additives are as follows: one or more of the following methods are used: X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM).

[0080] The testing method for infrared absorbing additives is one or more of the following: nuclear magnetic resonance, Fourier transform infrared spectroscopy (FTIR), etc.

[0081] In one embodiment, the infrared reflective additive includes one or more of ITO nanoparticles, AZO nanoparticles, and GZO nanoparticles; and / or, the infrared absorbent additive includes one or more of polyethyleneimine and polylysine.

[0082] Infrared reflective additives refer to materials capable of reflecting infrared radiation in the near-infrared band (0.7-2.5 μm) through plasmon resonance, such as one or more of ITO nanoparticles, AZO nanoparticles, and GZO nanoparticles. Infrared absorber additives refer to materials capable of absorbing infrared radiation in the mid-infrared band (2.5-25 μm) as supplementary absorbers, such as one or more of polyethyleneimine (PEI) and polylysine. Optionally, polyethyleneimine includes linear polyethyleneimine.

[0083] By designing infrared reflective additives, including one or more of ITO nanoparticles, AZO nanoparticles, and GZO nanoparticles, the near-infrared band dielectric constant is negative due to their highly doped transparent conductive oxide properties, which can generate a strong free carrier reflection effect. When infrared light irradiates the surface of ITO nanoparticles, AZO nanoparticles, or GZO nanoparticles, free electrons generate collective oscillations under the action of the light field, forming surface plasmon polaritons, thereby achieving strong reflection.

[0084] By designing infrared absorbing additives, including one or more of polyethyleneimine and polylysine, these additives exhibit strong absorption in the mid-infrared band due to the large number of amino groups in their molecules. For example, the CN, NH, and CH bonds in the polyethyleneimine molecule produce characteristic absorption peaks in the mid-infrared band, thus achieving effective absorption of infrared radiation.

[0085] By using infrared reflective additives to reflect infrared radiation in the near-infrared band, the optical adhesive can reduce the temperature rise of the module caused by direct sunlight; by using infrared absorbing additives to absorb infrared radiation in the mid-infrared band, the heat accumulation of the module is reduced; the synergistic effect of infrared reflective additives and infrared absorbing additives gives the optical adhesive a high blocking rate in the infrared band, further improving the working stability of the display screen in high-temperature environments.

[0086] In one embodiment, the infrared blocking additive includes an infrared reflecting additive and an infrared absorbing additive, wherein the infrared reflecting additive includes ITO nanoparticles and the infrared absorbing additive includes polyethyleneimine.

[0087] ITO nanoparticles, as infrared reflective additives, utilize the characteristics of highly doped transparent conductive oxides of indium tin oxide to exhibit a negative dielectric constant in the near-infrared band, generating a free carrier reflection effect and achieving strong infrared reflection through surface plasmon resonances; polyethyleneimine, as an infrared absorber additive, absorbs infrared radiation in the mid-infrared band through the vibration of CN and NH bonds in its molecular structure of amino and imine groups.

[0088] The synergistic effect of ITO nanoparticles and polyethyleneimine reduces the temperature rise of the display module caused by direct sunlight, reduces heat accumulation in the module, and improves the working stability of the display in high-temperature environments.

[0089] ITO has high reflectivity in the near-infrared band and is transparent to visible light, while polyethyleneimine has strong absorption in the mid-infrared band. The two work together to cover a wide-spectrum infrared region, avoiding the opacity of traditional infrared coatings in the visible light band, while maintaining the high visible light transmittance of the optical adhesive.

[0090] In one embodiment, the average particle size of the ITO nanoparticles is 30 nm to 50 nm; and / or, the molar ratio of indium oxide to tin oxide in the ITO nanoparticles is 4:1 to 12:1; the resistivity of the ITO nanoparticles is less than 100 Ω·cm.

[0091] By designing ITO nanoparticles with an average particle size of 30nm to 50nm, this particle size can precisely match the wavelength of near-infrared light, maintaining high infrared reflection efficiency. The average particle size of ITO nanoparticles can be 30nm, 35nm, 40nm, 45nm, 50nm, etc., or it can be a range of any two of the above values, such as 30nm-40nm, 35nm-50nm, etc.

[0092] By designing the molar ratio of indium oxide to tin oxide in ITO nanoparticles to be 4:1 to 12:1, the high indium oxide content ensures a basic level of conductivity, while the appropriate amount of tin oxide doping suppresses lattice defects in indium oxide, preventing increased visible light absorption and achieving an optimal balance between conductivity and transparency. The molar ratio of indium oxide to tin oxide in ITO nanoparticles can be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, etc., or it can be a range of any two of the above values, such as 4:1 to 8:1, 6:1 to 10:1, etc.

[0093] By designing the resistivity of ITO nanoparticles to be less than 100 Ω·cm, sufficient free electron concentration is ensured, maximizing the free carrier reflection effect in the near-infrared band. The optical adhesive generates a strong free carrier reflection effect in the near-infrared band, thereby reducing the temperature rise of the display module caused by direct sunlight. The resistivity of the ITO nanoparticles can be 99 Ω·cm, 98 Ω·cm, 95 Ω·cm, 90 Ω·cm, 80 Ω·cm, etc., as long as it is less than 100 Ω·cm.

[0094] In one embodiment, the weight-average molecular weight of polyethyleneimine is 1000 Da to 3000 Da.

[0095] By designing the weight-average molecular weight of polyethyleneimine to be 1000 Da to 3000 Da, we can reduce the short molecular chain and insufficient absorption intensity of CN and NH bond vibrations caused by excessively low molecular weight; and reduce the chain entanglement and uneven dispersion caused by excessively high molecular weight, which reduces infrared absorption efficiency.

[0096] The weight-average molecular weight of polyethyleneimine is 1000 Da to 3000 Da, which allows the molecular chain length and structure of polyethyleneimine to achieve the best balance. This maximizes the intensity of the characteristic absorption peak in the mid-infrared band, significantly improving the infrared absorption efficiency of polyethyleneimine in the mid-infrared band, thereby more effectively reducing the heat accumulation of the display module. At the same time, it ensures that the infrared absorbing additives are uniformly dispersed in the optical adhesive matrix, avoiding the decrease in light transmittance caused by agglomeration.

[0097] The weight-average molecular weight of polyethyleneimine can be 1000 Da, 1500 Da, 2000 Da, 2500 Da, 3000 Da, etc., or it can be a range of any two of the above values, such as 1000 Da~2500 Da, 1500 Da~3000 Da, etc.

[0098] In one embodiment, the polyethyleneimine is linear polyethyleneimine.

[0099] In one embodiment, the polyethyleneimine is a branched polyethyleneimine.

[0100] In one embodiment, the infrared blocking additive includes an infrared reflecting additive and an infrared absorbing additive, wherein the mass ratio of the infrared reflecting additive to the infrared absorbing additive is (3~5):1.

[0101] By designing the mass ratio of infrared reflective additive to infrared absorber to be (3~5):1, the composite system is uniformly distributed in the resin matrix, thereby achieving uniform infrared blocking. This mass ratio also maximizes the synergistic efficiency of near-infrared reflection and mid-infrared absorption, further improving the infrared blocking rate. It should be noted that when the infrared absorber is insufficient (e.g., a mass ratio of infrared reflective additive to infrared absorber of 10:1), mid-infrared absorption is weak; when the infrared absorber is excessive (e.g., a mass ratio of infrared reflective additive to infrared absorber of 2:1), although mid-infrared absorption is enhanced, the infrared absorber molecules are prone to aggregation.

[0102] The mass ratio of infrared reflective additive to infrared absorber additive can be 3:1, 3.5:1, 4:1, 4.5:1, 5:1, etc., or it can be a range of any two of the above values, such as (3~4):1, (3.5~4.5):1, etc.

[0103] In one embodiment, the molar ratio of the resin matrix to the infrared blocking additive is 50:1 to 100:1.

[0104] The molar ratio of resin matrix to infrared blocking additive is 50:1 to 100:1, which allows the infrared blocking additive to be uniformly dispersed in the resin matrix, thereby reducing the decrease in visible light transmittance caused by additive agglomeration. This molar ratio range further improves the infrared blocking rate, which is beneficial to the working stability of the display screen in high-temperature environments.

[0105] The molar ratio of the resin matrix to the infrared blocking additive can be 50:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, 100:1, etc., or it can be a range of any two of the above values, such as 60:1~85:1, 75:1~95:1, etc.

[0106] In one embodiment, the resin matrix comprises polyurethane acrylate and isobornyl methacrylate, wherein the molar ratio of polyurethane acrylate to isobornyl methacrylate is 2:1 to 4:1.

[0107] Polyurethane acrylate, as the main resin matrix, provides excellent adhesive properties. Introducing isobornyl methacrylate into the resin matrix can reduce the curing shrinkage rate of the material. By designing the molar ratio of polyurethane acrylate to isobornyl methacrylate to be 2:1 to 4:1, the shrinkage rate during curing can be effectively reduced while ensuring bond strength. This effectively reduces curing internal stress, avoids problems such as microcracks in the adhesive layer, and ensures the excellent optical properties of the optical adhesive, guaranteeing its light transmission imaging quality, bonding reliability, and service durability.

[0108] The molar ratio of polyurethane acrylate to isobornyl methacrylate can be 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc., or it can be a range of any two of the above values, such as 2:1~3:1, 3:1~4:1, etc.

[0109] In one embodiment, the weight-average molecular weight of the polyurethane acrylate is 500 Da to 1200 Da.

[0110] In one specific embodiment, the optical adhesive includes a resin matrix, a dehumidifying additive, and an infrared blocking additive; the resin matrix includes polyurethane acrylate and isobornyl methacrylate; the dehumidifying additive includes a modified porous material, which includes a silica matrix, an aminoalkoxysilane coupling agent covalently linked to hydroxyl groups on the surface of the silica matrix, and an acrylate grafted with an amino group of the aminoalkoxysilane coupling agent; the infrared blocking additive includes ITO nanoparticles and polyethyleneimine.

[0111] The optical adhesive provided in this application has a transmittance of ≥80% for visible light in the range of 400nm to 760nm; a transmittance of 82% for visible light in the range of 550nm; an infrared isolation of ≥12% for the range of 2.5μm to 25μm; a self-dehumidification rate of ≥0.06% / h at 25℃@95%RH, which can prevent water vapor from entering the silver paste lines and reduce silver migration; the curing shrinkage rate of the adhesive layer formed by the optical adhesive is ≤0.5%; and the shear bond strength of the optical adhesive is ≥1.5MPa.

[0112] In one embodiment, the thickness of the adhesive layer formed by the optical adhesive in this application embodiment is 50μm-100μm.

[0113] This application also provides a method for preparing an optical adhesive, which can be used to prepare the optical adhesive provided in the above embodiments.

[0114] Please see Figures 1-4 , Figure 1 This is a schematic flowchart of the method for preparing the optical adhesive provided in the embodiments of this application. Figure 2 This is a schematic flowchart of the preparation method of the dehumidifying additive provided in the embodiments of this application. Figure 3 This is a schematic flowchart of the preparation method of the infrared blocking additive provided in the embodiments of this application. Figure 4 This is a flowchart illustrating step S03 of the method for preparing optical adhesive provided in this application embodiment.

[0115] The method for preparing the optical adhesive provided in this application specifically includes: Step S01: Obtain a resin matrix and a dehumidifying additive; wherein the dehumidifying additive includes a modified porous material; the modified porous material includes a porous material matrix, an aminosilane coupling agent linked to hydroxyl groups on the surface of the porous material matrix, and an acrylate grafted with an amino group of the aminosilane coupling agent.

[0116] In one embodiment, the resin matrix comprises polyurethane acrylate and isobornyl methacrylate. The polyurethane acrylate, as the main component of the resin matrix, provides good adhesive properties; by introducing isobornyl methacrylate into the resin matrix, the curing shrinkage rate of the material can be reduced.

[0117] In one embodiment, the method for preparing the resin matrix includes: adding polyurethane acrylate (PUA) and isobornyl methacrylate (IBOMA) to a reactor under an inert atmosphere, heating to 35°C~45°C, adding a photoinitiator, and stirring for 20min~40min for prepolymerization at a stirring speed of 200r / min~500r / min to obtain a resin matrix with suitable viscosity. It should be noted that since the photoinitiator reacts under oxygen conditions, the resin matrix is ​​prepared under a nitrogen atmosphere.

[0118] Optionally, the inert atmosphere includes a nitrogen atmosphere.

[0119] Optionally, the weight average molecular weight of the polyurethane acrylate is 500 Da to 1200 Da.

[0120] Optionally, the molar ratio of polyurethane acrylate to isobornyl methacrylate is 2:1 to 4:1, which can effectively reduce the shrinkage rate of the material during the curing process while ensuring the bonding strength. This can effectively reduce the internal stress during curing, avoid problems such as microcracks in the adhesive layer, and ensure the light transmission imaging quality, bonding reliability and service durability of the optical adhesive.

[0121] Optionally, the photoinitiator is hydroxycyclohexylphenyl ketone.

[0122] Optionally, the molar ratio of polyurethane acrylate to photoinitiator is 100:1 to 100:5.

[0123] In one embodiment, the method for preparing the dehumidifying additive includes: Step S011: Obtain a porous material matrix.

[0124] A porous material matrix refers to a solid material framework with a continuous three-dimensional network structure and rich in interconnected pores. The surface of the porous material matrix has hydroxyl groups, which can be primary or secondary hydroxyl groups. Optionally, the average pore size of the porous material matrix is ​​2 nm to 5 nm; and / or, the volume porosity of the porous material matrix is ​​40% to 70%; and / or, the specific surface area of ​​the porous material matrix is ​​300 m².2 / g~2000m 2 / g.

[0125] In one embodiment, the step of obtaining a porous material matrix includes: 1) obtaining a pre-made porous material matrix; 2) activating the pre-made porous material matrix: vacuum drying the pre-made porous material matrix at 100℃~140℃ for 5h~6h to remove physically adsorbed water.

[0126] In one embodiment, the porous material matrix includes one or more of porous silica, porous alumina, and MOF@SiO2 materials.

[0127] Step S012: Disperse the porous material matrix in a first solvent to form a first suspension.

[0128] In one embodiment, the first solvent includes toluene. That is, the porous material matrix is ​​dispersed in toluene to form a first suspension. Optionally, ultrasound is used to assist in the uniform dispersion of the porous material matrix in the first solvent.

[0129] Step S013: Dissolve the aminosilane coupling agent in the second solvent to form an aminosilane coupling agent solution.

[0130] In one embodiment, the second solvent comprises toluene. For example, the aminosilane coupling agent is dissolved in toluene in a mass fraction of 5 wt%.

[0131] Step S014: Add the aminosilane coupling agent solution to the first suspension and reflux at 75℃~90℃ for 10h~14h, while controlling the moisture content to be less than 100ppm, to obtain a porous material matrix grafted with the aminosilane coupling agent. It should be noted that during the entire reflux process, controlling the moisture content to be less than 100ppm prevents the aminosilane coupling agent from agglomerating and clogging the pore structure of the porous material matrix.

[0132] In one embodiment, the aminosilane coupling agent solution is added to the first suspension by dropwise addition.

[0133] In one embodiment, the mass ratio of the porous material matrix to the aminosilane coupling agent is 5:1 to 20:1, so as to introduce a sufficient number of amino groups on the surface of the porous material matrix. Some of the amino groups are used to graft acrylate, and some of the amino groups are used to adsorb water vapor.

[0134] In one embodiment, an aminosilane coupling agent solution is added to a first suspension, refluxed at 75°C to 90°C for 10 to 14 hours, centrifuged to remove free aminosilane coupling agent, washed multiple times with a second solvent, and vacuum dried at 50°C to 70°C for 18 to 36 hours to obtain a porous material matrix grafted with aminosilane coupling agent.

[0135] Step S015: Mix the porous material matrix grafted with aminosilane coupling agent, acrylate, activator and catalyst, and react at 55℃~65℃ for 20h~28h under an inert atmosphere to obtain the modified porous material.

[0136] In one embodiment, the inert atmosphere includes a nitrogen atmosphere. It should be noted that an inert atmosphere can suppress the free radical polymerization side reaction of the double bonds of the acrylate, ensuring the grafting of the acrylate with the amino groups.

[0137] In one embodiment, the molar ratio of acrylate to aminosilane coupling agent is 1:1 to 1.5:1, which optimizes the esterification reaction kinetics of acrylate and aminosilane coupling agent, so that the grafted acrylate segments form a flexible structure and enhance compatibility with the resin matrix.

[0138] In one embodiment, the activator comprises N,N'-dicyclohexylcarbodiimide (DCC). The activator is used to activate the carboxyl group.

[0139] In one embodiment, the molar ratio of activator to acrylate is 1:1 to 1.5:1, which is beneficial to improving reaction efficiency.

[0140] In one embodiment, the catalyst comprises 4-dimethylaminopyridine (DMAP). The catalyst is used to lower the activation energy of the reaction and improve the selectivity of the reaction.

[0141] In one embodiment, the molar ratio of catalyst to acrylate is 0.1:1 to 0.5:1, which improves reaction efficiency and reduces unreacted monomer residue.

[0142] In one embodiment, after the porous material matrix grafted with an aminosilane coupling agent reacts with acrylate, it is centrifuged and washed sequentially with tetrahydrofuran (THF) and ethanol to remove unreacted acrylate and byproducts (such as urea). The material is then vacuum dried at 50°C to 70°C to constant weight to obtain the modified porous material.

[0143] Step S02: Mix the dehumidifying additive with the resin matrix to obtain a mixed adhesive solution.

[0144] In one embodiment, the dehumidifying additive is added to the resin matrix in multiple portions, while ultrasonic-assisted dispersion is used. The mixture is stirred at 35°C to 45°C for 0.5 to 2 hours to ensure uniform mixing of the dehumidifying additive and the resin matrix. At this time, the hydroxyl groups on the surface of the porous material form hydrogen bonds with the hydroxyl groups of polyurethane acrylate (PUA), forming a stable interfacial bond.

[0145] In one embodiment, the molar ratio of the resin matrix to the dehumidifying additive is 15:1 to 30:1.

[0146] In one embodiment, the step of obtaining the mixed adhesive includes: mixing a dehumidifying additive with a resin matrix to obtain a first mixture; adding an infrared blocking additive to the first mixture to obtain the mixed adhesive; wherein the infrared blocking additive includes one or more of infrared reflective additives and infrared absorbing additives.

[0147] In one embodiment, the infrared blocking additive includes an infrared reflecting additive and an infrared absorbing additive, wherein the infrared reflecting additive includes ITO nanoparticles and the infrared absorbing additive includes polyethyleneimine; the method for preparing the infrared blocking additive includes: Step S021: Disperse ITO nanoparticles in a third solvent to form a second suspension.

[0148] In one embodiment, the average particle size of the ITO nanoparticles is 30 nm to 50 nm; and / or, the molar ratio of indium oxide to tin oxide in the ITO nanoparticles is 4:1 to 12:1; the resistivity of the ITO nanoparticles is less than 100 Ω·cm.

[0149] In one embodiment, the third solvent includes deionized water.

[0150] In one embodiment, ultrasound is used to assist in the uniform dispersion of ITO nanoparticles in a third solvent.

[0151] In one embodiment, ITO nanoparticles are dispersed in a third solvent under ice bath conditions (temperature ≤25°C) to maintain the uniformity of ITO nanoparticle dispersion while avoiding damage to the ITO nanoparticle structure.

[0152] In one embodiment, dispersing the ITO nanoparticles in a third solvent includes: dispersing the ITO nanoparticles in an acidic solution and sonicating them to remove the oxide layer and contaminants on the surface of the ITO nanoparticles, followed by ion washing to neutral (pH=7), and vacuum drying to obtain the ITO nanoparticles. Optionally, the acidic solution includes a nitric acid solution; that is, dispersing the ITO nanoparticles in a nitric acid solution. Optionally, the mass fraction of the nitric acid solution is 5%.

[0153] Step S022: Dissolve polyethyleneimine in a fourth solvent to form a polyethyleneimine solution.

[0154] In one embodiment, the polyethyleneimine is a branched polyethyleneimine.

[0155] In one embodiment, the weight-average molecular weight of polyethyleneimine is 1000 Da to 3000 Da.

[0156] In one embodiment, the fourth solvent includes deionized water.

[0157] In one embodiment, the pH of the polyethyleneimine solution is 10-11 to maintain high surface activity of the polyethyleneimine. Optionally, the pH of the polyethyleneimine solution is adjusted with NaOH.

[0158] For example, polyethyleneimine is dissolved in deionized water to prepare a 10 wt% solution (pH=10-11, adjusted with NaOH).

[0159] Step S023: Under conditions of less than or equal to 25°C, add the polyethyleneimine solution to the second suspension to obtain the second mixture; wherein, during the addition of the polyethyleneimine solution, maintain the pH of the solution at 9-10.

[0160] In one embodiment, the polyethyleneimine solution is added to the second suspension by dropping. Optionally, the dropping rate is 1 mL / min.

[0161] It should be noted that during the mixing of polyethyleneimine and ITO nanoparticles, the pH is maintained at 9-10 to preserve the surface activity of polyethyleneimine. The amino groups of polyethyleneimine and the carboxyl groups on the surface of ITO nanoparticles are combined through electrostatic adsorption or hydrogen bonding.

[0162] Step S024: React the second mixture at 55℃~100℃ for 3h~5h, wash, and dry to obtain the infrared blocking additive. It should be noted that under ice bath conditions (temperature ≤25℃), the amino groups of polyethyleneimine and the carboxyl groups on the surface of ITO nanoparticles are bonded together through electrostatic adsorption or hydrogen bonding; under 55℃~100℃ conditions, the carboxyl groups of ITO condense with the amino groups of polyethyleneimine (PEI).

[0163] In one embodiment, a condensing agent is introduced into the second mixture, and the carboxyl groups of ITO condense with the amino groups of polyethyleneimine (PEI) at 55°C to 65°C. Optionally, the condensing agent includes 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC).

[0164] In one embodiment, no condensing agent needs to be introduced into the second mixture, and the carboxyl group of ITO condenses with the amino group of polyethyleneimine (PEI) at 80~100°C.

[0165] In one embodiment, the second mixture is reacted at 55°C to 100°C for 3 to 5 hours, the precipitate is collected by centrifugation, and the precipitate is washed three times with ethanol to remove free polyethyleneimine. The precipitate is then vacuum dried at 50°C to 70°C for 8 to 24 hours and sieved to obtain an infrared blocking additive composed of ITO nanoparticles and polyethyleneimine.

[0166] In one embodiment, the mass ratio of ITO nanoparticles to polyethyleneimine is (3-5):1. This ratio allows the ITO nanoparticles and polyethyleneimine to form a uniform and stable composite, optimizing the synergistic effect of near-infrared reflection and mid-infrared absorption, which is beneficial for improving infrared blocking efficiency and maintaining the long-term infrared blocking performance of the optical adhesive.

[0167] In one embodiment, the infrared blocking additive is added to the first mixture (the first mixture is obtained by mixing the dehumidifying additive with the resin matrix) in multiple batches, while ultrasonic-assisted dispersion is used to ensure the uniform dispersion of the infrared blocking additive.

[0168] In one embodiment, the mixed adhesive comprises a resin matrix, a dehumidifying additive, and an infrared blocking additive, and further comprises an antioxidant and a silane coupling agent; specifically, after mixing the resin matrix, the dehumidifying additive, and the infrared blocking additive, an antioxidant and a silane coupling agent are added, and the mixture is stirred evenly to obtain the mixed adhesive. Optionally, the antioxidant comprises pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Optionally, the silane coupling agent comprises γ-aminopropyltriethoxysilane.

[0169] Resin matrices are susceptible to free radical generation due to heat or ultraviolet radiation. Antioxidants can actively capture these free radicals, interrupting chain oxidation reactions and preventing resin molecular chain breakage. The inorganic end of the silane coupling agent hydrolyzes to generate silanol, which undergoes a condensation reaction with the hydroxyl groups (-OH) on the surface of inorganic particles such as infrared blocking additives (e.g., nano-indium tin oxide ITO) and dehumidifying additives, forming strong Si-O-Si covalent bonds. The amino groups at the organic end of the silane coupling agent react with carboxyl, epoxy, or hydroxyl groups in the resin matrix to form hydrogen bonds or chemical bonds, significantly reducing the interfacial energy between the inorganic fillers such as infrared blocking additives and dehumidifying additives and the resin, thus improving the dispersion uniformity of the infrared blocking additives and dehumidifying additives.

[0170] Step S03: Apply the mixed adhesive solution onto the carrier, cure it, and perform post-treatment to obtain the optical adhesive.

[0171] In one embodiment, the mixed adhesive solution is coated onto a carrier, cured, and post-treated to obtain the optical adhesive, specifically including: Step S031: Apply the mixed adhesive solution onto the carrier.

[0172] In one embodiment, the carrier includes a PET release film.

[0173] In one embodiment, the coating thickness of the mixed adhesive solution on the PET release film is 50 μm-100 μm. Optionally, the coating speed is 1.5 m / min to 3 m / min to ensure uniform film thickness.

[0174] Step S032: The mixed adhesive is cured for the first time using a first light source with a wavelength of 360nm~370nm; wherein the power of the first light source is 50mW / cm². 2 ~100mW / cm 2 The irradiation time is 2 to 5 minutes.

[0175] Through the first curing stage, the surface layer rapidly solidifies to form a dense protective layer. The first light source, with a wavelength of 360nm~370nm, possesses strong surface penetration and high photon energy, effectively exciting the photoinitiator to generate free radicals and rapidly initiating the polymerization reaction of the surface layer. The power is controlled at 50mW / cm². 2 ~100mW / cm 2 This method ensures sufficient initiation efficiency without causing surface overheating or photo-oxidation due to excessive power. An irradiation time of 2 to 5 minutes ensures that the surface layer is fully cured, forming a dense protective layer that prevents oxygen from penetrating deeper layers and avoids oxygen inhibition polymerization.

[0176] Step S033: The mixed adhesive is cured a second time using a second light source with a wavelength of 400nm~410nm; wherein the power of the second light source is 150mW / cm. 2 ~300mW / cm 2 The irradiation time is 3 to 8 minutes.

[0177] Through a second curing process, light penetrates the surface layer to cure the deeper adhesive layers. The second light source, with a wavelength of 400nm~410nm, has a longer wavelength and better penetration, enabling it to reach deep into the adhesive layer for curing. Power is controlled at 150mW / cm². 2 ~300mW / cm 2 The power is higher than that of the first light source, mainly because the photon energy of the first light source is lower, requiring a higher light intensity to achieve the same initiation efficiency. The irradiation time is 3 to 8 minutes, longer than the surface curing time, to ensure that the deep adhesive is fully cured.

[0178] Through gradient curing with a first and second curing cycle, the curing shrinkage rate is less than or equal to 0.5%, ensuring the curing effect.

[0179] Step S034: Place the cured adhesive layer in an environment with a temperature of 35℃~45℃ and a humidity of 20%~40% for 1h~3h to obtain optical adhesive.

[0180] After curing, place the adhesive layer in an environment with a temperature of 35℃~45℃ and humidity of 20%~40% for 1h~3h. This removes any trace solvent residues and low-molecular-weight volatiles that may have been generated during the curing process, promotes the movement and rearrangement of molecular chains, and eliminates internal stress generated during curing. At the same time, it promotes the full activation of the hygroscopic activity of the modified porous material, and allows the adsorption of trace amounts of residual moisture inside the adhesive layer, further improving its self-dehumidification stability and preventing the release of moisture from affecting optical performance during subsequent use.

[0181] The optical adhesive prepared by the method provided in this application has virtually no volatile organic compound (VOC) emissions. It can maintain high visible light transmittance and high infrared blocking rate even under high and low temperature cycling and high humidity environments.

[0182] This application also provides a display screen, which includes a functional layer, a cover plate, and an optical adhesive. The optical adhesive is disposed between the functional layer and the cover plate. The optical adhesive is the optical adhesive provided in the above embodiments or an optical adhesive prepared by the method described in the above embodiments. The cover plate can be a rigid cover plate or a flexible cover plate. Rigid cover plates include, but are not limited to, glass. Flexible cover plates include, but are not limited to, polyimide (PI) and polyethylene terephthalate (PET). Optionally, the functional layer is a touch layer.

[0183] To facilitate understanding of the embodiments of this application, the following non-limiting embodiments are provided to further illustrate the application in detail.

[0184] Example 1: I. Preparation of dehumidifying additives.

[0185] (1) Activation of mesoporous silica: mSiO2 (specific surface area of ​​1300m²) 2 The water (g, average pore size 4nm, volume porosity 60%) was vacuum dried at 120℃ for 6h to remove physically adsorbed water.

[0186] (2) Grafting with silane coupling agent: ① Disperse mSiO2 in toluene and sonicate for 30 min (40 kHz, 500 W) to form a uniform suspension.

[0187] ② Add γ-aminopropyltriethoxysilane (APTES) solution dropwise, reflux at 80℃ for 12 h (circulate in condenser, moisture content <100ppm); wherein, the mass ratio of mSiO2 to γ-aminopropyltriethoxysilane (APTES) is 10:1; the γ-aminopropyltriethoxysilane (APTES) solution is obtained by dissolving γ-aminopropyltriethoxysilane in toluene, with a mass fraction of 5wt%.

[0188] ③ Centrifuge (8000 rpm, 10 min) to remove free APTES, wash 3 times with toluene, and vacuum dry at 60℃ for 24 h.

[0189] (3) Grafting of hydroxyacrylates: ① APTES-mSiO2, hydroxyethyl methacrylate (HEMA), N,N'-dicyclohexylcarbodiimide (DCC), and 4-dimethylaminopyridine (DMAP) were mixed and reacted at 60°C for 24 h under nitrogen protection; wherein the molar ratio of DCC to HEMA was 1.2:1, the molar ratio of DMAP to HEMA was 0.1:1, and the molar ratio of HEMA to APTES was 1.2:1.

[0190] ② Centrifuge at 8000 rpm for 10 min, then wash with tetrahydrofuran (THF) and ethanol in sequence to remove unreacted monomers and byproducts (urea).

[0191] ③ Vacuum dry at 60℃ to constant weight.

[0192] II. Preparation of infrared blocking additives.

[0193] (1) ITO with a particle size of 35 nm (In2O3:SnO2=6:1, resistivity 1Ω·cm) was selected. ITO was dispersed in 5% HNO3 and sonicated for 30 min with the following parameters: 40 kHz, 200 W. The surface oxide layer was removed, and the mixture was centrifuged and washed until neutral (pH=7). It was then vacuum dried at 60 °C.

[0194] (2) Branched polyethyleneimine (PEI, M) w =1800Da) was dissolved in deionized water to prepare a 10wt% solution (pH=10-11, adjusted with NaOH).

[0195] (3) Take 3g of ITO nanoparticles from step (1) above, disperse them in 100ml of deionized water, and sonicate for 1h under ice bath temperature control at 20℃ with an ultrasonic power of 400W. Slowly add 1g of PEI solution (10wt%, i.e., containing 0.1g of PEI), controlling the dropping rate at 1mL / min, and magnetically stir (500rpm) while maintaining pH=9-10. The mass ratio of ITO to PEI is 3:1.

[0196] (4) React in a water bath at 60℃ for 4 hours, centrifuge (12000 rpm, 15 min) to collect the precipitate, and wash with ethanol 3 times to remove free PEI.

[0197] (5) Dry under vacuum at 60°C for 12 hours, and then use a 400-mesh sieve to obtain composite powder.

[0198] III. Preparation of the resin matrix.

[0199] Under a nitrogen atmosphere, polyurethane acrylate (PUA) and isobornyl methacrylate (IBOMA) were added to a reactor, heated to 40°C, and then the photoinitiator hydroxycyclohexylphenyl ketone was added. Prepolymerization was carried out by stirring for 30 minutes at a stirring speed of 200-500 r / min to obtain a prepolymer matrix with suitable viscosity. The molar ratio of polyurethane acrylate to isobornyl methacrylate was 3:1, and the molar ratio of polyurethane acrylate to hydroxycyclohexylphenyl ketone was 100:2.

[0200] IV. Combination of resin matrix with dehumidifying additives and infrared blocking additives.

[0201] (1) The dehumidifying additive prepared above was added to the resin matrix in three batches (each 20 min apart), while ultrasonic-assisted dispersion was turned on (power 200W, 10 min apart), and stirred at 40℃ for 1 h to ensure uniform dispersion. The molar ratio of the dehumidifying additive to the resin matrix was 1:20.

[0202] (2) Then, infrared blocking additives were added, and ultrasonic high-humidity stirring and dispersion were carried out under the conditions of 2000 rpm and ultrasonic power of 300W. The ultrasonic stirring time was 5 min each time and the interval was 10 min. The molar ratio of infrared blocking additives to resin matrix was 1:75.

[0203] (3) Add 0.5 parts of antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 0.3 parts of silane coupling agent (KH550, γ-aminopropyltriethoxysilane), stir at 30°C for 30 min to obtain a uniform mixed solution.

[0204] V. Curing and Post-treatment.

[0205] (1) Coating: The mixed adhesive solution is evenly coated on the PET release film, and the thickness is controlled at 75μm (coating speed 2m / min).

[0206] (2) Surface curing: Using a 365nm UV LED light source with a power of 100mW / cm², the surface is rapidly cured for 3 minutes to form a dense protective layer.

[0207] (3) Deep curing: Switch to 405nm LED light source, power 200mW / cm², irradiate for 5 minutes, light penetrates the surface to cure the deep adhesive.

[0208] (4) Low temperature post-treatment: After curing, place the adhesive layer in an environment of 40℃ and 30% humidity for 2 hours.

[0209] An optical adhesive that is self-dehumidifying and infrared-blocking was prepared.

[0210] The difference between Examples 2-3 and Example 1 is that the molar ratio of the dehumidifying additive to the resin matrix is ​​different.

[0211] The difference between Examples 4-5 and Example 1 is that the molar ratio of the infrared blocking additive to the resin matrix is ​​different.

[0212] The difference between Example 6 and Example 1 is that no infrared blocking additive was added to the resin matrix.

[0213] The difference between Example 7 and Example 1 is that the infrared blocking additive only includes ITO nanoparticles, that is, ITO and PEI were not combined during the preparation of the infrared blocking additive.

[0214] The difference between Example 8 and Example 1 is that the infrared blocking additive only includes PEI, that is, ITO and PEI were not compounded during the preparation of the infrared blocking additive.

[0215] The difference between Comparative Example 1 and Example 1 is that no dehumidifying additives and infrared blocking additives were added to the resin matrix.

[0216] The relevant parameter testing process for the embodiments and comparative examples of this application is as follows: 1. Test of transmittance of visible light in the range of 400nm-760nm.

[0217] The results were obtained using a UV-Vis spectrophotometer.

[0218] 2. 550nm visible light transmittance test.

[0219] The results were obtained using a UV-Vis spectrophotometer at a fixed wavelength of 550 nm.

[0220] 3. Infrared blocking rate test of 2.5μm-25μm.

[0221] The results were obtained using a Fourier transform infrared spectrometer.

[0222] 4. Dehumidification rate test at 25℃@95%RH.

[0223] ① Pretreatment: Dry the film sample to constant weight (e.g., vacuum dry at 80℃ for 24h), cool it and weigh it (recorded as m0); ② Moisture absorption treatment: Place the sample in a constant temperature and humidity chamber at 25℃ and 95% relative humidity, and let it stand until it is saturated with moisture (the weight no longer changes, recorded as m1). ③ Dehumidification test: After the sample has absorbed moisture to a saturation, remove it and immediately place it in the same environment at 25℃@95%RH (or simulate dehumidification conditions). Weigh the sample at fixed intervals (e.g., 1 hour, 2 hours) (recorded as m). t ); ④ Dehumidification rate calculation: Dehumidification rate at a certain time point = (m1 - m) t ) / (m1- m0) ÷ time t (unit: % / h), or plot the dehumidification rate-time curve to analyze the rate change.

[0224] 5. Curing shrinkage rate.

[0225] ① Sampling: Take a wet film sample before curing (ensure uniform thickness, such as preparing a wet film of fixed thickness by scraping), and measure the initial dimensions of the wet film (such as thickness d0, area A0, or volume V0).

[0226] ② Curing: Curing is completed according to the curing process of the film layer (such as heating, UV irradiation, etc.).

[0227] ③ Test the dimensions after curing: Use precision instruments (such as a micrometer to measure thickness, or an image measuring instrument to measure area) to measure the dimensions (d1, A1, or V1) after curing.

[0228] ④ Shrinkage rate calculation: Thickness shrinkage rate = [(d0 - d1) / d0] × 100% Volume shrinkage rate = [(V0- V1) / V0] × 100% (If it is uniform shrinkage, it can also be estimated by thickness / area shrinkage rate).

[0229] 6. Shear bond strength.

[0230] ① Sample preparation: The film layer is used as an adhesive layer and coated on the overlapping surface of two rigid substrates (such as aluminum plates or glass plates, which must meet the standard size: usually 100mm×25mm×2mm). The overlap length is controlled to 12.5mm (standard recommended value) to ensure uniform film thickness.

[0231] ② Curing: Complete the bonding and curing process according to the curing process of the film layer.

[0232] ③ Test: Clamp the specimen in the fixture of the universal testing machine and apply an axial tensile load at a loading rate of 1 mm / min to 5 mm / min until the joint fails. Record the maximum failure load.

[0233] ④ Strength calculation: Shear bond strength = Maximum failure load / Overlap area (unit: MPa).

[0234] Table 1 Test parameters of Examples 1-8 and Comparative Example 1

[0235] All equivalent structural or procedural modifications made using the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. An optical adhesive, characterized in that, include: A resin matrix and a dehumidifying additive; the dehumidifying additive includes a modified porous material; The modified porous material comprises a porous material matrix, an aminosilane coupling agent linked to hydroxyl groups on the surface of the porous material matrix, and an acrylate grafted with an amino group of the aminosilane coupling agent.

2. The optical adhesive according to claim 1, characterized in that, The modified porous material has an average pore size of 2 nm to 5 nm; and / or, The modified porous material has a volume porosity of 40% to 70%; and / or, The modified porous material has a specific surface area of ​​300 m². 2 / g~2000m 2 / g.

3. The optical adhesive according to claim 1, characterized in that, The porous material matrix includes one or more of porous silica, porous alumina, and MOF@SiO2.

4. The optical adhesive according to claim 1, characterized in that, The aminosilane coupling agent includes an aminoalkoxysilane coupling agent.

5. The optical adhesive according to claim 1 or 3, characterized in that, The aminosilane coupling agent includes one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-β-aminoethyl-γ-aminopropyltriethoxysilane.

6. The optical adhesive according to claim 1, characterized in that, The acrylates include hydroxyacrylates.

7. The optical adhesive according to claim 1 or 6, characterized in that, The acrylates include one or more of hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and hydroxybutyl methacrylate.

8. The optical adhesive according to claim 1, characterized in that, The molar ratio of the resin matrix to the dehumidifying additive is 15:1 to 30:

1.

9. The optical adhesive according to claim 1, characterized in that, The optical adhesive also includes infrared blocking additives, which include one or more of infrared reflective additives and infrared absorbing additives.

10. The optical adhesive according to claim 9, characterized in that, The infrared reflective additive includes one or more of ITO nanoparticles, AZO nanoparticles, and GZO nanoparticles; and / or, The infrared absorbing additive includes one or more of polyethyleneimine and polylysine.

11. The optical adhesive according to claim 9, characterized in that, The infrared blocking additive includes an infrared reflective additive and an infrared absorbing additive. The infrared reflective additive includes ITO nanoparticles, and the infrared absorbing additive includes polyethyleneimine.

12. The optical adhesive according to claim 10 or 11, characterized in that, The average particle size of the ITO nanoparticles is 30nm-50nm; and / or, The molar ratio of indium oxide to tin oxide in the ITO nanoparticles is 4:1 to 12:

1. The resistivity of the ITO nanoparticles is less than 100 Ω·cm.

13. The optical adhesive according to claim 10 or 11, characterized in that, The weight-average molecular weight of the polyethyleneimine is 1000 Da to 3000 Da.

14. The optical adhesive according to claim 9, characterized in that, The infrared blocking additive includes an infrared reflective additive and an infrared absorber, and the mass ratio of the infrared reflective additive to the infrared absorber is (3~5):

1.

15. The optical adhesive according to claim 9, characterized in that, The molar ratio of the resin matrix to the infrared blocking additive is 50:1 to 100:

1.

16. The optical adhesive according to claim 1, characterized in that, The resin matrix comprises polyurethane acrylate and isobornyl methacrylate, wherein the molar ratio of polyurethane acrylate to isobornyl methacrylate is 2:1 to 4:

1.

17. A method for preparing an optical adhesive, characterized in that, include: Obtain a resin matrix and a dehumidifying additive; wherein the dehumidifying additive includes a modified porous material; The modified porous material includes a porous material matrix, an aminosilane coupling agent linked to hydroxyl groups on the surface of the porous material matrix, and an acrylate grafted with amino groups of the aminosilane coupling agent. The dehumidifying additive is mixed with the resin matrix to obtain a mixed adhesive solution; The mixed adhesive solution is applied to a carrier, cured, and then post-treated to obtain the optical adhesive.

18. The method for preparing optical adhesive according to claim 17, characterized in that, The preparation method of the dehumidifying additive includes: Obtain a porous material matrix; A porous material matrix is ​​dispersed in a first solvent to form a first suspension; The aminosilane coupling agent is dissolved in a second solvent to form an aminosilane coupling agent solution; The aminosilane coupling agent solution is added to the first suspension and refluxed at 75℃~90℃ for 10h~14h, while controlling the moisture content to be less than 100ppm, to obtain a porous material matrix grafted with aminosilane coupling agent. The porous material matrix grafted with the aminosilane coupling agent, the acrylate, the activator and the catalyst are mixed and reacted at 55℃~65℃ for 20h~28h under an inert atmosphere to obtain the modified porous material.

19. The method for preparing optical adhesive according to claim 18, characterized in that, The mass ratio of the porous material matrix to the aminosilane coupling agent is 5:1 to 20:1; and / or, The molar ratio of the acrylate to the aminosilane coupling agent is 1:1 to 1.5:1; and / or, The molar ratio of the activator to the acrylate is 1:1 to 1.5:1; and / or, The molar ratio of the catalyst to the acrylate is 0.1:1 to 0.5:

1.

20. The method for preparing the optical adhesive according to claim 17, characterized in that, The step of mixing the dehumidifying additive with the resin matrix to obtain the mixed adhesive further includes: The dehumidifying additive is mixed with the resin matrix to obtain a first mixture; An infrared blocking additive is added to the first mixture to obtain the mixed adhesive; wherein the infrared blocking additive includes one or more of infrared reflective additives and infrared absorbing additives.

21. The method for preparing the optical adhesive according to claim 20, characterized in that, The infrared blocking additive includes an infrared reflecting additive and an infrared absorbing additive. The infrared reflecting additive includes ITO nanoparticles, and the infrared absorbing additive includes polyethyleneimine. The preparation method of the infrared blocking additive includes: The ITO nanoparticles are dispersed in a third solvent to form a second suspension; The polyethyleneimine is dissolved in a fourth solvent to form a polyethyleneimine solution; Under conditions of 25°C or less, the polyethyleneimine solution is added to the second suspension to obtain a second mixture; wherein, during the addition of the polyethyleneimine solution, the pH of the solution is maintained at 9-10. The second mixture was reacted at 55℃~100℃ for 3h~5h, washed, and dried to obtain the infrared blocking additive.

22. The method for preparing the optical adhesive according to claim 21, characterized in that, The mass ratio of the ITO nanoparticles to the polyethyleneimine is (3-5):

1.

23. The method for preparing the optical adhesive according to claim 17, characterized in that, The steps of coating the mixed adhesive onto a carrier, curing, and post-processing to obtain the optical adhesive include: The mixed adhesive solution is applied onto the carrier; The mixed adhesive solution is first cured using a first light source with a wavelength of 360nm~370nm; wherein the power of the first light source is 50mW / cm². 2 ~100mW / cm 2 The irradiation time is 2 to 5 minutes; The mixed adhesive is cured a second time using a second light source with a wavelength of 400nm to 410nm; wherein the power of the second light source is 150mW / cm². 2 ~300mW / cm 2 The irradiation time is 3 to 8 minutes; The cured adhesive layer is placed in an environment with a temperature of 35℃~45℃ and a humidity of 20%~40% for 1h~3h to obtain the optical adhesive.

24. A display screen, characterized in that, include: The invention comprises a functional layer, a cover plate, and an optical adhesive, wherein the optical adhesive is disposed between the functional layer and the cover plate, and the optical adhesive includes the optical adhesive according to any one of claims 1-16 or the optical adhesive prepared by any one of claims 17-23.

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