Packaging glue, LED display module and display screen

Abstract

The invention belongs to the technical field of LED display screens, and particularly relates to packaging glue, an LED display module and a display screen. Compared with the prior art, the metal hydroxide flame retardant added in the packaging glue provided by the invention is subjected to surface directional modification, is well dispersed with matrix resin, and can be decomposed to absorb a large amount of heat and decomposed to generate a compact oxide layer to inhibit flame propagation when a fire disaster occurs; meanwhile, by adding the charring catalyst, the carbon residue of the coating is greater than or equal to 45%, the carbon layer is compact, and the fireproof effect is improved; meanwhile, a refractive index difference exists between the metal hydroxide and the cured matrix resin, so that an internal diffusion effect is achieved, and color separation is reduced; the metal hydroxide subjected to surface treatment can be bulged on the surface to form a concave-convex structure, so that an anti-dazzle effect is achieved, visual fatigue is reduced, and the visibility of display content is improved; therefore, the packaging glue can realize the characteristics of internal diffusion, anti-dazzle, flame retardance and fire prevention through one-time mould pressing, the process is simplified, the yield is improved, and the cost is saved.

Description

Technical Field

[0001] This invention belongs to the field of LED display technology, and particularly relates to an encapsulating adhesive, an LED display module, and a display screen. Background Technology

[0002] In recent years, small-pitch LED display technology (pixel pitch ≤ P1.5 mm) has become the mainstream choice in the commercial display field. Small-pitch LED displays have significant advantages in ultra-high-definition image quality, seamless splicing, and flexible adaptation. However, as the pixel pitch decreases, safety risks also increase. The increased heat buildup effect lowers the glass transition temperature of the PCB board, and traditional protective materials such as epoxy resin or silicone resin are flammable. Furthermore, the small distance between modules means that combustion may release toxic gases. Therefore, for applications such as large commercial complexes and transportation hubs, LED fire protection has become a necessity.

[0003] Furthermore, uneven surface treatment of the PCB substrate leads to significant fluctuations in surface reflectivity, resulting in visible differences in ink color. A common solution is to apply a light black anti-glare film after substrate encapsulation to improve these differences, but this increases costs due to reduced yield caused by the increased processing. Additionally, for outdoor applications, prolonged exposure to ultraviolet light can cause the module to yellow, affecting the display. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an encapsulating adhesive, an LED display module and a display screen with high carbon residue, flame retardancy, UV resistance and anti-glare functions.

[0005] This invention provides an encapsulating adhesive, comprising:

[0006] 40-60 parts by weight of surface-treated metal hydroxide;

[0007] 20-30 parts by weight of matrix resin;

[0008] 0.1 to 1 part by weight of char-forming catalyst;

[0009] 18-30 parts by weight of curing agent and curing accelerator;

[0010] Additives: 0.1~1 parts by weight;

[0011] The surface-treated metal hydroxide includes metal hydroxides surface-treated with silane coupling agents;

[0012] The matrix resin is selected from alicyclic epoxy resins and / or alicyclic epoxy resin derivatives.

[0013] Preferably, the particle size D90 of the surface-treated metal hydroxide is 1~10 μm;

[0014] And / or, the refractive index of the surface-treated metal hydroxide is 1.53~1.55;

[0015] And / or, the maximum decomposition temperature of the surface-treated metal hydroxide is 250°C to 350°C.

[0016] Preferably, the surface-treated metal hydroxide is prepared according to the following method:

[0017] The metal hydroxide is immersed in a silane coupling agent solution, and then subjected to natural air drying and heat treatment to obtain a surface-treated metal hydroxide; the silane coupling agent solution includes a silane coupling agent, water and an alcohol solvent; the mass concentration of the silane coupling agent in the silane coupling agent solution is 1% to 5%.

[0018] Preferably, the metal hydroxide is selected from magnesium hydroxide and / or aluminum hydroxide;

[0019] The silane coupling agent is selected from one or more of vinyl silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, ureosilane coupling agents, and mercaptosilane coupling agents;

[0020] The volume ratio of water to alcohol solvent is 1:(7~10).

[0021] The pH value of the silane coupling agent solution is 5.5~7;

[0022] The immersion time is 20-180 min;

[0023] The impregnation temperature is 20℃~60℃;

[0024] The natural air-drying time is 0.5~2 hours;

[0025] The temperature of the heat treatment is 75℃~85℃;

[0026] The heat treatment time is 5 to 30 minutes.

[0027] Preferably, the molecular weight of the alicyclic epoxy resin and the alicyclic epoxy resin derivative is independently 100~1000 g / mol;

[0028] And / or, the epoxy equivalent of the alicyclic epoxy resin and the alicyclic epoxy resin derivative is independently 100~300 g / mol;

[0029] And / or, the refractive index of the alicyclic epoxy resin and the alicyclic epoxy resin derivative are each independently 1.4 to 1.5;

[0030] And / or, the alicyclic epoxy resin derivative is selected from silicon compounds including alicyclic epoxy groups and / or acrylate compounds including alicyclic epoxy groups.

[0031] Preferably, the alicyclic epoxy resin is selected from one or more of the following: bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, bis(3,4-epoxycyclohexylmethyl) carbonate, 2,2-bis(3,3'-epoxycyclohexyl)propane, 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid 6-[[6-[[6-(7-oxabicyclo[4.1.0]heptane-3-methoxy)-6-oxohexyl]oxy]-6-oxohexyl]oxy]-6-oxohexyl ester and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carbonate;

[0032] The alicyclic epoxy resin derivative is selected from one or more of 1,1,3,3-tetramethyl-1,3-bis-[2-[7-oxybicyclo[4.1.0]hept-3-yl]ethyl]disiloxane, tetraepoxycyclohexylethyl 2,4,6,8-tetramethylcyclotetrasiloxane, 3,4-epoxycyclohexylmethyl methacrylate, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

[0033] Preferably, the carbon-forming catalyst is selected from supported iron-based catalysts, supported nickel-based catalysts, and supported cobalt-based catalysts; the particle size of the supported iron-based catalyst is 5~20 nm; the particle size of the supported nickel-based catalyst is 1~10 nm; and the particle size of the supported cobalt-based catalyst is 10~30 nm.

[0034] And / or, the curing agent is selected from one or more of amine curing agents, acid anhydride curing agents and phenolic resin curing agents;

[0035] And / or, the curing accelerator includes one or more of the following: tertiary amine accelerators, imidazole derivative accelerators, acetylacetone metal salt accelerators, metal carboxylate accelerators, peroxide accelerators, and phosphide accelerators;

[0036] And / or, the additives include leveling agents and / or silane coupling agents.

[0037] The present invention also provides an LED display module, including a substrate, a plurality of LED light-emitting chips disposed on the substrate, and an encapsulating adhesive layer disposed between the plurality of LED light-emitting chips and on the surface away from the substrate; the encapsulating adhesive layer is formed by the aforementioned encapsulating adhesive.

[0038] Preferably, the thickness of the encapsulating adhesive layer is 100~500 μm.

[0039] The present invention also provides a display screen, including the LED display module described above.

[0040] Compared with the prior art, the encapsulating adhesive provided by the present invention has the following advantages:

[0041] 1) The metal hydroxide flame retardant added to the encapsulating adhesive provided by this invention undergoes surface-oriented modification and is well dispersed with the matrix resin. In the event of a fire, the metal hydroxide flame retardant decomposes and absorbs a large amount of heat, producing a dense oxide layer that inhibits flame propagation. Simultaneously, by adding a char-forming catalyst, the incomplete combustion products of the polymer material decomposed under thermal radiation are converted into residual char. Through these two additives, the coating achieves a residual char content ≥45% and a dense char layer, exhibiting excellent fire-retardant properties. Especially in the BS476-7 test, the dense char layer significantly reduces the flame spread distance, allowing it to pass Class 1 testing and making it suitable for applications such as large commercial complexes and transportation hubs.

[0042] 2) The refractive index of the metal hydroxide flame retardant added in this invention is 1.53~1.55 after surface orientation modification, and the refractive index of the matrix resin after curing is 1.50~1.52, with a refractive index difference of 0.03. After the composite material is molded, it will produce an internal haze of 5~15%, which plays an internal diffusion role and reduces color separation.

[0043] 3) The surface-treated metal hydroxide added in this invention has a particle size D90 of 1~10 μm. After molding with encapsulating adhesive, the particles protrude on the surface to form an uneven structure with a surface haze of 40%~50%, which plays an anti-glare role, reduces visual fatigue, and improves the visibility of the displayed content.

[0044] 4) The matrix resin used in this invention is an alicyclic epoxy resin and / or an alicyclic epoxy resin derivative that does not contain the benzene ring structure found in bisphenol A. Therefore, it is resistant to ultraviolet radiation, does not yellow after long-term outdoor use, and the yellowness index YI value after UV aging is <1.0.

[0045] 5) The encapsulating adhesive provided by this invention is a high carbon residue dual-effect flame retardant and anti-glare adhesive based on metal hydroxide. It can achieve internal diffusion, anti-glare, flame retardant and fireproof properties in one molding process, replacing the encapsulating adhesive and film, simplifying the process, improving yield and saving costs. Attached Figure Description

[0046] Figure 1 This invention provides a schematic diagram of a specific LED display module manufacturing process.

[0047] Figure 2 The image shows the BS 476-7 Class 1 test results of the LED display module prepared in Embodiment 1 of the present invention. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] This invention provides an encapsulating adhesive, comprising: 40-60 parts by weight of a surface-treated metal hydroxide; 20-30 parts by weight of a matrix resin; 0.1-1 parts by weight of a char-forming catalyst; 18-30 parts by weight of a curing agent and a curing accelerator; and 0.1-1 parts by weight of an additive; wherein the surface-treated metal hydroxide includes a silane coupling agent surface-treated metal hydroxide; and the matrix resin is selected from alicyclic epoxy resins and / or alicyclic epoxy resin derivatives.

[0050] In one specific embodiment of the present invention, optionally, the content of the surface-treated metal oxide in the encapsulating adhesive is 40 parts by weight, 42 parts by weight, 45 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 55 parts by weight, 58 parts by weight, 60 parts by weight, or any two of the above values.

[0051] In one specific embodiment of the present invention, the surface-treated metal hydroxide is preferably surface-treated magnesium hydroxide and / or surface-treated aluminum hydroxide.

[0052] This invention selects surface-treated metal hydroxides, which not only improves the dispersibility of the metal hydroxides with the main resin but also increases the amount of metal hydroxides added. Simultaneously, the refractive index of untreated metal hydroxides is 1.56~1.58, significantly different from the refractive index of the cured matrix resin (1.50~1.52). Therefore, excessive internal haze will cause whitening. The refractive index of the surface-treated metal hydroxides is reduced, decreasing the difference with the cured matrix resin and reducing internal haze. Lower internal haze not only avoids whitening but also has a light diffusion effect, reducing color deviation at large angles. In a specific embodiment of this invention, the refractive index of the surface-treated metal hydroxides is preferably 1.53~1.55; optionally, the refractive index of the surface-treated metal hydroxides is 1.53, 1.54, 1.55, or any two of the above values.

[0053] In a specific embodiment of the present invention, the particle size D90 of the surface-treated metal hydroxide is preferably 1~10 μm; optionally, the particle size D90 of the surface-treated metal hydroxide is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any two of the above values. After surface treatment, the metal hydroxide and the matrix resin are uniformly dispersed, and the surface is uneven, forming light scattering. The incident light undergoes diffuse reflection rather than specular reflection on this surface, disrupting the directional propagation of light and dispersing the reflected light to multiple angles, significantly reducing the intensity of strong reflected light entering the human eye, thereby reducing glaring reflected light and improving the visibility of screen content.

[0054] In a specific embodiment of the present invention, the maximum decomposition temperature of the surface-treated metal hydroxide is preferably 250°C to 350°C; the residual carbon content of the surface-treated metal oxide is greater than or equal to 60%; the surface-treated metal hydroxide has a thermal decomposition curve with the above characteristics, and its maximum decomposition temperature is exactly synchronized with the decomposition temperature of the matrix resin, which can better exert the flame retardant and fireproof properties.

[0055] The surface-treated metal hydroxide includes a silane coupling agent surface-treated metal hydroxide. In a specific embodiment of the present invention, the surface-treated metal hydroxide is prepared by the following method: the metal hydroxide is impregnated in a silane coupling agent solution, and then subjected to natural air-drying and heat treatment to obtain the surface-treated metal hydroxide; the silane coupling agent solution includes a silane coupling agent, water, and an alcohol solvent; the mass concentration of the silane coupling agent in the silane coupling agent solution is 1% to 5%.

[0056] In one specific embodiment of the present invention, the metal hydroxide is preferably magnesium hydroxide and / or aluminum hydroxide.

[0057] In a specific embodiment of the present invention, since the metal hydroxide has a small particle size, in order to avoid its agglomeration and improve its surface activity, it is preferable to first pretreat the metal hydroxide and then impregnate it in a silane coupling agent solution; the pretreatment method includes: drying the metal hydroxide with hot air to remove free water, and then grinding the agglomerated particles to restore them to their original particle size to improve surface activity; specifically, it is preferable to dry it to a water content of less than 0.5%; the grinding is preferably carried out using a honeycomb mill.

[0058] In one specific embodiment of the present invention, the silane coupling agent solution comprises a silane coupling agent, water, and an alcohol solvent; the silane coupling agent can be any silane coupling agent well known to those skilled in the art, and there are no special limitations. In the present invention, it is preferably one or more of vinyl silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, ureosilane coupling agents, and mercaptosilane coupling agents; the vinyl silane coupling agent includes, but is not limited to, vinyltrimethoxysilane and / or vinyltriethoxysilane; the epoxy... The aminosilane coupling agent includes, but is not limited to, one or more of 2-(3,4-epoxycyclohexyl)ethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, 3-glycidyl etheroxypropylmethyldiethoxysilane, and 3-glycidyl etheroxypropyltriethoxysilane; the aminosilane coupling agent includes, but is not limited to, aminopropyltrimethoxysilane, aminoethylaminopropyltrimethoxysilane, and diethylaminopropyltrimethoxysilane. The ureosilane coupling agent comprises, but is not limited to, 3-ureopropyltrimethoxysilane and / or 3-ureopropyltriethoxysilane; the mercaptosilane coupling agent comprises, but is not limited to, one or more of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-mercaptopropylmethyldimethoxysilane; the volume ratio of water to alcohol solvent is preferably 1:(7~10), more preferably 1:(8~10), and even more preferably 1:9; the alcohol solvent is well known to those skilled in the art. Any alcohol solvent is acceptable, with no particular limitation; ethanol is preferred in this invention. The mass concentration of the silane coupling agent in the silane coupling agent solution is preferably 1% to 5%. Optionally, the mass concentration of the silane coupling agent in the silane coupling agent solution is 1%, 2%, 3%, 4%, 5%, or any two of the above values. The pH value of the silane coupling agent solution is preferably 5.5 to 7. Optionally, the pH value of the silane coupling agent solution is 5.5, 6, 6.5, 7, or any two of the above values.

[0059] The metal hydroxide is impregnated in a silane coupling agent solution; specifically, the liquid level of the silane coupling agent is preferably greater than twice the thickness of the metal hydroxide; the impregnation temperature is preferably 20℃~60℃; specifically, the impregnation is preferably carried out at room temperature at the beginning to avoid silane self-polymerization, and the temperature is increased in the middle of the impregnation to promote molecular migration to the active site; the heating rate during impregnation is preferably 2~8℃ / min; optionally, the heating rate during impregnation is 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, or 8℃ / min; the impregnation time is preferably 20~180 min; optionally, the impregnation time is 20 min, 30 min, 50 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, or any two of the above values; the impregnation is preferably carried out under stirring conditions.

[0060] After impregnation, the metal hydroxide is obtained by natural air-drying and heat treatment. The natural air-drying time is preferably 0.5 to 2 hours. Optionally, the natural air-drying time is 0.5 hours, 0.8 hours, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, or any two of the above values. The natural air-drying is preferably carried out under a humidity of 50% to 70%. Optionally, the natural air-drying is carried out under a humidity of 50%, 55%, 60%, 65%, 70%, or any two of the above values. Natural air-drying allows the silane to spread fully. The preferred temperature for the heat treatment is 75℃~85℃; optionally, the temperature is 75℃, 78℃, 80℃, 75℃, 85℃ or any two of the above values; the preferred heat treatment time is 5~30 min; optionally, the heat treatment time is 5 min, 10 min, 15 min, 20 min, 25 min, 30 min or any two of the above values; after heat treatment, it is preferred to wash with an alcohol solvent to remove unreacted substances, and then dry to obtain the surface-treated metal hydroxide; the alcohol solvent can be any alcohol solvent known to those skilled in the art, and there are no special limitations, but ethanol is preferred in this invention; the preferred drying temperature is 100℃~120℃; optionally, the drying temperature is 100℃, 105℃, 110℃, 115℃, 120℃ or any two of the above values; the preferred drying time is 1~3 h; optionally, the drying time is 1 h, 1.5 h, 2 h, 2.5 h, 3 h or any two of the above values.

[0061] In one specific embodiment of the present invention, optionally, the content of the matrix resin in the encapsulating adhesive is 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, or any two of the above values.

[0062] In this invention, the matrix resin is an alicyclic epoxy resin and / or an alicyclic epoxy resin derivative; alicyclic epoxy resin has a tight, rigid molecular structure in which epoxy groups are directly linked to alicyclic rings, resulting in increased crosslinking density after curing and excellent heat resistance; furthermore, alicyclic epoxy resin does not contain the benzene ring structure found in bisphenol A, thus it is resistant to ultraviolet radiation and does not yellow after long-term outdoor use; additionally, alicyclic epoxy resin does not contain chloride ions and sodium ions during synthesis, thus exhibiting good dielectric properties.

[0063] In one specific embodiment of the present invention, the alicyclic epoxy resin derivative preferably includes silicon compounds containing alicyclic epoxy groups and / or acrylate compounds containing alicyclic epoxy groups.

[0064] In one specific embodiment of the present invention, the molecular weight of the alicyclic epoxy resin and the alicyclic epoxy resin derivative is preferably 100-1000 g / mol; optionally, the molecular weight of the alicyclic epoxy resin and the alicyclic epoxy resin derivative is 100 g / mol, 200 g / mol, 300 g / mol, 400 g / mol, 500 g / mol, 600 g / mol, 700 g / mol, 800 g / mol, 900 g / mol, 1000 g / mol, or any two of the above values.

[0065] In a specific embodiment of the present invention, the epoxy equivalent of the alicyclic epoxy resin and the alicyclic epoxy resin derivative is preferably 100~300 g / mol; optionally, the epoxy equivalent of the alicyclic epoxy resin and the alicyclic epoxy resin derivative is 100 g / mol, 120 g / mol, 140 g / mol, 160 g / mol, 180 g / mol, 200 g / mol, 220 g / mol, 240 g / mol, 260 g / mol, 280 g / mol, 300 g / mol or any two of the above values.

[0066] In a specific embodiment of the present invention, the refractive index of the alicyclic epoxy resin and / or the alicyclic epoxy resin derivative is independently 1.4 to 1.5; the refractive index of the alicyclic epoxy resin and / or the alicyclic epoxy resin derivative after curing is preferably 1.50 to 1.52.

[0067] In a specific embodiment of the present invention, the difference between the refractive index of the cured alicyclic epoxy resin and / or alicyclic epoxy resin derivative and the refractive index of the surface-treated metal hydroxide is preferably 0.01 to 0.05; optionally, the difference between the refractive index of the cured alicyclic epoxy resin and / or alicyclic epoxy resin derivative and the refractive index of the surface-treated metal hydroxide is 0.01, 0.02, 0.03, 0.04, 0.05 or any two of the above values.

[0068] In a specific embodiment of the present invention, the alicyclic epoxy resin is preferably bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate (molecular weight 366.45 g / mol, epoxy equivalent 183 g / mol, refractive index n=1.493), 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarbamate (molecular weight 252.31 g / mol, epoxy equivalent 126 g / mol, refractive index n=1.495), bis(3,4-epoxycyclohexylmethyl) carbonate (molecular weight 282.33 g / mol, epoxy equivalent 141 g / mol, refractive index n=1.498), or 2,2-bis(3,3'-epoxycyclohexyl)propane (molecular weight 236.35 g / mol, epoxy equivalent 118 g / mol, refractive index n=1.52). 8) One or more of 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid 6-[[6-[[6-(7-oxabicyclo[4.1.0]heptane-3-methoxy)-6-oxohexyl]oxy]-6-oxohexyl]oxy]-6-oxohexyl ester (molecular weight 594.73 g / mol, epoxy equivalent 298 g / mol, refractive index n=1.487) and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carbonate (molecular weight 252.31 g / mol, epoxy equivalent 127 g / mol, refractive index n=1.498).

[0069] In a specific embodiment of the present invention, the alicyclic epoxy resin derivative is preferably 1,1,3,3-tetramethyl-1,3-bis-[2-[7-oxybicyclo[4.1.0]hept-3-yl]ethyl]disiloxane (molecular weight 382.68 g / mol, epoxy equivalent 191 g / mol, refractive index n=1.481) or tetracyclic cyclohexylethyl 2,4,6,8-tetramethylcyclotetrasiloxane (molecular weight 737.23 g / mol). One or more of the following: 3,4-epoxycyclohexylmethyl methacrylate (molecular weight 196.24 g / mol, epoxy equivalent 196 g / mol, refractive index n=1.487), and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane (molecular weight 288.46 g / mol, epoxy equivalent 288 g / mol, refractive index n=1.446).

[0070] In one specific embodiment of the present invention, optionally, the content of the char-forming catalyst in the encapsulating adhesive is 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, or any two of the above values.

[0071] Polymer materials are prone to incomplete combustion and CO production when exposed to high-temperature thermal radiation. A char-forming catalyst transforms CO into carbon black or carbon nanotubes under high-temperature conditions, and the increased amount of residual char can suppress flame spread. In a specific embodiment of this invention, the char-forming catalyst is preferably a supported iron-based catalyst, a supported nickel-based catalyst, or a supported cobalt-based catalyst.

[0072] In one specific embodiment of the present invention, the particle size of the supported iron-based catalyst is preferably 5-20 nm; optionally, the particle size of the supported iron-based catalyst is 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm or any two of the above values.

[0073] In a specific embodiment of the present invention, the support for the supported iron-based catalyst is preferably MgO or Al2O3; the loading of the supported iron-based catalyst is preferably greater than or equal to 20%.

[0074] In one specific embodiment of the present invention, the particle size of the supported nickel-based catalyst is preferably 1 to 10 nm; optionally, the particle size of the supported nickel-based catalyst is 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm or any two of the above values.

[0075] In one specific embodiment of the present invention, the support for the supported nickel-based catalyst is preferably Al2O3; the loading of the supported nickel-based catalyst is preferably greater than or equal to 20%.

[0076] In one specific embodiment of the present invention, the particle size of the supported cobalt-based catalyst is preferably 10-30 nm; optionally, the particle size of the supported cobalt-based catalyst is 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm or any two of the above values.

[0077] In one specific embodiment of the present invention, the support for the supported cobalt-based catalyst is preferably Al2O3 or carbon nanotubes; the loading of the supported cobalt-based catalyst is preferably greater than or equal to 20%.

[0078] In one specific embodiment of the present invention, optionally, the content of the curing agent and the curing accelerator in the encapsulating adhesive is 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, or any two of the above values.

[0079] In a specific embodiment of the present invention, the mass ratio of the curing agent to the curing accelerator is preferably (10~100):1; optionally, the mass ratio of the curing agent to the curing accelerator is 10:1, 20:1, 30:1, 35:1, 38:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1 or any two of the above values.

[0080] In a specific embodiment of the present invention, the curing agent preferably includes one or more of amine curing agents, acid anhydride curing agents, and phenolic resin curing agents; the amine curing agent includes, but is not limited to, one or more of aliphatic amine curing agents, alicyclic amine curing agents, aromatic amine curing agents, and polyamide curing agents; the aliphatic amine curing agent includes, but is not limited to, ethylenediamine, diethylenetriamine, triethylenetetramine, etc.; the alicyclic amine curing agent includes, but is not limited to, isophorone diamine, montanane diamine, etc.; the aromatic amine curing agent includes, but is not limited to, diaminodiphenylmethane, diaminodiphenyl ether, etc.; the polyamide curing agent is formed by the condensation polymerization of dimer vegetable oil fatty acids and aliphatic amines; the acid anhydride curing agent includes, but is not limited to, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc.

[0081] In a specific embodiment of the present invention, the curing accelerator preferably includes one or more of tertiary amine accelerators, imidazole derivative accelerators, acetylacetone metal salt accelerators, metal carboxylate accelerators, peroxide accelerators, and phosphide accelerators; the tertiary amine accelerators include, but are not limited to, 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, triethylamine, triethanolamine, o-hydroxybenzyldimethylamine, etc.; the imidazole derivative accelerators include, but are not limited to, one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-phenylimidazole; the acetylacetone metal salt accelerator has the general formula M(CH3COCHCOCH3)2, wherein M includes, but is not limited to, aluminum, cobalt, nickel, copper, zinc, iron, vanadium, chromium, titanium, manganese, potassium, zirconium, etc.; the metal carboxylate accelerators include, but are not limited to, stannous octoate, lead octoate, etc.; the peroxide accelerators include, but are not limited to, benzoyl peroxide, etc.; and the phosphide accelerators include, but are not limited to, triphenylphosphine, etc.

[0082] In one specific embodiment of the present invention, the content of the additive in the encapsulating adhesive is 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, or any two of the above values.

[0083] Adding additives can improve certain properties of the encapsulating adhesive, such as improving the leveling and uniformity of the adhesive and enhancing the adhesion of the coating. In this invention, the additives preferably include silane coupling agents and / or leveling agents, more preferably silane coupling agents and leveling agents. The mass ratio of the silane coupling agent to the leveling agent is preferably 1:(0.5~2), more preferably 1:(0.5~1.5), even more preferably 1:(0.8~1.2), and most preferably 1:1.

[0084] In a specific embodiment of the present invention, the silane coupling agent is preferably one or more selected from vinyl silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, ureosilane coupling agents, and mercaptosilane coupling agents; the vinyl silane coupling agent includes, but is not limited to, vinyltrimethoxysilane and / or vinyltriethoxysilane; the epoxy silane coupling agent includes, but is not limited to, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and 3-glycidyl etheroxypropylmethyldimethoxysilane. The aminosilane coupling agent includes, but is not limited to, aminopropyltriethoxysilane, aminopropyltrimethoxysilane, aminoethylaminopropyltrimethoxysilane, and diethylaminopropyltrimethoxysilane; the ureosilane coupling agent includes, but is not limited to, 3-ureopropyltrimethoxysilane and / or 3-ureopropyltriethoxysilane; the mercaptosilane coupling agent includes, but is not limited to, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropylmethyldimethoxysilane.

[0085] In a specific embodiment of the present invention, the leveling agent preferably includes one or more of silicone leveling agents, acrylate leveling agents, and fluorocarbon leveling agents; the silicone leveling agent includes, but is not limited to, polyether-modified polysiloxane, polyester-modified polysiloxane, long-chain alkyl-modified polysiloxane, etc.; the acrylate leveling agent includes, but is not limited to, pure acrylate leveling agents, fluorinated acrylate leveling agents, etc.

[0086] In one specific embodiment of the present invention, the encapsulating adhesive includes:

[0087] 50 parts by weight of surface-treated metal hydroxide;

[0088] 25 parts by weight of matrix resin;

[0089] 1 part by weight of char-forming catalyst;

[0090] 23.6 parts by weight of curing agent and curing accelerator;

[0091] 0.4 parts by weight of auxiliary agent;

[0092] Or, including:

[0093] 60 parts by weight of surface-treated metal hydroxide;

[0094] 20 parts by weight of matrix resin;

[0095] 0.8 parts by weight of char-forming catalyst;

[0096] 18.2 parts by weight of curing agent and curing accelerator;

[0097] Additive 1 part by weight.

[0098] The encapsulating adhesive provided by this invention comprises a surface-treated metal hydroxide. This metal hydroxide flame retardant decomposes at high temperatures, absorbing a large amount of heat, reducing the material surface temperature, and delaying polymer thermal decomposition. The water vapor produced during decomposition also dilutes the concentration of combustible gases and oxygen, inhibiting the combustion chain reaction. The generated metal oxide forms a dense protective layer on the material surface, isolating oxygen and heat transfer and preventing further combustion of deeper materials. Simultaneously, the use of a metal-based char-forming catalyst promotes the formation of carbon nanotubes or carbon black from the incomplete combustion product CO of polymers at 500℃~1000℃. Through these measures, the encapsulating adhesive of this invention has a residual char content ≥45% and a dense char layer, exhibiting excellent fire-retardant properties. Especially in the BS476-7 test, the dense char layer significantly reduces the flame spread distance, allowing it to pass the Class 1 test and making it suitable for applications such as large commercial complexes and transportation hubs.

[0099] Furthermore, the surface-treated metal hydroxide used in this invention has a particle size of 1~10 μm. After molding with the encapsulating adhesive, the particles protrude on the surface to form an uneven structure, resulting in a surface haze of 40%~50%, which serves as an anti-glare effect. Simultaneously, the surface-treated metal hydroxide has a refractive index difference with the matrix resin, resulting in an internal haze of 5%~15%, which serves as an internal diffusion effect, reducing color separation. Moreover, the alicyclic epoxy resin does not contain the benzene ring structure found in bisphenol A, thus it is resistant to ultraviolet radiation and does not yellow after long-term outdoor use.

[0100] According to the present invention, the encapsulating adhesive can be prepared according to methods well known to those skilled in the art, without any special limitations. Specifically, it can be prepared according to the following steps: surface-treated metal hydroxide, matrix resin, carbonization catalyst, curing agent, curing accelerator and additives are degassed by vacuum stirring to obtain the encapsulating adhesive; the stirring speed is preferably 1000~2000 rpm; the stirring time is 10~20 min.

[0101] The present invention also provides the above-mentioned LED display module, including a substrate, a plurality of LED light-emitting chips disposed on the substrate, and an encapsulating adhesive layer disposed between the plurality of LED light-emitting chips and on the surface away from the substrate; the encapsulating adhesive layer is formed by the above-mentioned encapsulating adhesive.

[0102] In this invention, the substrate can be any substrate known to those skilled in the art, and there are no special restrictions. In this invention, a PCB substrate is preferred.

[0103] In this invention, the surface of the substrate is provided with a plurality of LED chips, and more preferably, a plurality of driver ICs are also provided.

[0104] According to the present invention, an encapsulating adhesive layer is disposed between the plurality of LED chips and on the surface of the plurality of LED chips away from the substrate; the thickness of the encapsulating adhesive layer is preferably 100~500 μm; optionally, the thickness of the flame-retardant encapsulating adhesive layer is 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, 300 μm, 310 μm, 320 μm, 330 μm, 340 μm, 350 μm, 360 μm, 370 μm, 380 μm, 390 μm, 400 μm, 410 μm, 420 μm. μm, 430 μm, 440 μm, 450 μm, 460 μm, 470 μm, 480 μm, 490 μm, 500 μm or any two of the above values.

[0105] In one specific embodiment of the present invention, the surface haze of the LED display module is 40%~50%.

[0106] In one specific embodiment of the present invention, the internal haze of the LED display module is 5% to 15%.

[0107] The present invention also provides a method for preparing the above-mentioned LED display module, comprising the following steps: S1) providing a semi-finished LED display module; the semi-finished LED display module includes a substrate and a plurality of LED light-emitting chips disposed on the substrate; S2) transferring encapsulating adhesive to the surface of the semi-finished LED display module, curing it to form an encapsulating adhesive layer, thereby obtaining the LED display module.

[0108] See Figure 1 , Figure 1 This is a schematic diagram illustrating a specific manufacturing process of an LED display module provided by the present invention.

[0109] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available or homemade. The encapsulating adhesive is the same as described above and will not be repeated here.

[0110] In one specific embodiment of the present invention, the LED display module semi-finished product is preferably first subjected to plasma cleaning and then the encapsulating adhesive is transferred to its surface.

[0111] In a specific embodiment of the present invention, step S2) specifically involves: fixing the semi-finished LED display module onto a preset molding fixture after plasma cleaning; applying the aforementioned encapsulating adhesive onto a release film and pressing it; then removing it and curing it to form an encapsulating adhesive layer; the pressing temperature is preferably 130℃~180℃, more preferably 130℃~160℃, and even more preferably 130℃~150℃; the pressing time is preferably 5~15 min; since the pressing is carried out under heating conditions, the encapsulating adhesive is also pre-cured during the pressing process; the pressing thickness is preferably 100~500 μm; the curing temperature is 130℃~180℃; and the curing time is preferably 1~3 h.

[0112] The present invention also provides a display screen, including the LED display module described above.

[0113] To further illustrate the present invention, the following describes in detail, with reference to embodiments, an encapsulating adhesive, an LED display module, and a display screen provided by the present invention.

[0114] All reagents used in the following examples are commercially available.

[0115] Example 1

[0116] 1.1 The ingredient list is shown in Table 1.

[0117] Table 1. Ingredients list for Example 1

[0118]

[0119] 1.2 Surface treatment of aluminum hydroxide:

[0120] 1) Pretreatment of aluminum hydroxide: Place aluminum hydroxide powder with a particle size of 5 μm in a drying device, pass hot air through it to remove free water, and ensure that the water content is <0.5%; deagglomerate the agglomerated particles through a honeycomb mill or other equipment to restore them to their original particle size in order to improve surface activity;

[0121] 2) Preparation of silane coupling agent solution: Weigh 1% of the total mass of silane coupling agent 2-(3,4-epoxycyclohexyl)ethalkyltrimethoxysilane, dilute with ethanol-water mixture (ethanol:water≈9:1), stir until a transparent hydrolysate is obtained, and control the pH value at 6.5.

[0122] 3) Dynamic impregnation treatment: Immerse aluminum hydroxide in silane solution (liquid level > material thickness 2 times), stir for 100 min at room temperature to 60℃ (heating rate 4℃ / min, keep warm after reaching 60℃), and let it air dry naturally for 2 hours (humidity 60%) to allow the silane to spread fully;

[0123] 4) Post-treatment and curing: Bake at 80℃ for 15 min, then wash with ethanol to remove unreacted substances, filter and dry at 120℃ for 2 h.

[0124] 1.3 Add the ingredients from the ingredient list to the mixing tray according to the proportions, and use an empty high-speed mixer to stir and degas at 1000 rpm for 10 minutes. Let the dispersed materials stand for 10 minutes to obtain the encapsulating adhesive.

[0125] 1.4 After plasma cleaning, the LED light board with attached chips and driver ICs is fixed onto a preset molding fixture. Adhesive is extruded onto the release film for pressing. The pressing temperature is 130℃, the pressing time is 15 min, and the molding thickness is 300 μm. After molding, the substrate is removed and then post-cured. The post-curing temperature is 130℃ and the post-curing time is 3 h to obtain the LED display module.

[0126] Performance testing

[0127] Flame retardancy test: A 270 mm × 295 mm LED module was prepared and flame retardancy was tested according to BS 476-7 Class 1 standard. The flame spread results were obtained and are shown in Table 2. The BS 476-7 Class 1 test effect diagram is shown below. Figure 2 As shown.

[0128] Internal and external haze tests: The dispersed and degassed adhesive was poured into a 30 mm × 30 mm × 0.5 mm thick PTFE fixture. After curing, it was removed and the total haze W was measured using a haze meter. Then, a 50 μm thick layer of OCA tape with a haze <0.5% was applied to the surface, and the haze W1 was measured again using a haze meter. The internal haze is then determined to be W1, and the external haze to be W-W1, as shown in Table 2.

[0129] Carbon residue test: The carbon residue of the cured adhesive was tested using a TGA tester. 10 mg of the cured encapsulating adhesive was placed in a ceramic crucible and placed in the TGA tester, and the test program was set. The heating rate was 10℃ / min, the atmosphere was N2, and the temperature was set from 40℃ to 750℃. The results are shown in Table 2.

[0130] Module reliability testing: The molded and cured module was lit up and placed in a device at 85℃ and 85% humidity for 168 hours. The display effect was observed for any abnormalities, and the lamp surface was checked for cracks, bubbles, wrinkles, or other appearance abnormalities. The molded and cured module was then lit up and subjected to thermal shock testing at -40℃ to 80℃, with a cold shock time of 30 minutes and a hot shock time of 30 minutes, constituting one cycle. A total of 500 cycles were performed, and the display effect was observed for any abnormalities, and the lamp surface was checked for cracks, bubbles, or other appearance abnormalities. The results are shown in Table 2.

[0131] Module UV aging resistance test: The molded and cured module is placed in a UV aging test equipment. UV aging conditions: test chamber temperature 80℃, irradiation intensity 0.76 W / m 2 (340 nm), time 8 h; then stored in a 50℃ aging chamber for 4 h, this is one cycle, a total of 14 cycles, or 168 h. The yellowness index was measured using a yellowness index meter, and the results are shown in Table 2.

[0132] Table 2 Performance test results of the display module prepared in Example 1

[0133]

[0134] Note: The numbers in Table 1 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0135] Example 2

[0136] 2.1 The ingredient list is shown in Table 3.

[0137] Table 3 Ingredients list for Example 2

[0138]

[0139] 2.2 Surface treatment of magnesium hydroxide:

[0140] 1) Magnesium hydroxide pretreatment: Place magnesium hydroxide powder with a particle size of 7 μm in a drying device, pass hot air through it to remove free water, and ensure that the water content is <0.5%; deagglomerate the agglomerated particles through a honeycomb mill or other equipment to restore them to their original particle size in order to improve surface activity;

[0141] 2) Preparation of silane coupling agent solution: Weigh 2-(3,4-epoxycyclohexyl)ethalkyltrimethoxysilane, which is 3% of the total mass of raw materials, and dilute it with ethanol-water mixture (ethanol:water ≈9:1). Stir until a transparent hydrolysate is obtained and the pH value is controlled at 5.5.

[0142] 3) Dynamic impregnation treatment: Immerse aluminum hydroxide in silane solution (liquid level > material thickness 2 times), stir for 180 min at room temperature to 60℃ (heating rate 4℃ / min, keep warm after reaching 60℃), and let it air dry naturally for 1 hour (humidity 70%) to allow the silane to spread fully.

[0143] 4) Post-treatment and curing: Bake at 80℃ for 15 min, then wash with ethanol to remove unreacted substances, filter and dry at 120℃ for 2 h.

[0144] 2.3 Add the ingredients from the ingredient list to the mixing tray according to the proportions, and use an empty high-speed mixer to stir and degas at 1500 rpm for 15 minutes. Let the dispersed materials stand for 10 minutes to obtain the encapsulating adhesive.

[0145] 2.4 After plasma cleaning, the LED light board with attached chips and driver ICs is fixed onto a preset molding fixture. Adhesive is extruded onto the release film for pressing. The pressing temperature is 150℃, the pressing time is 10 min, and the molding thickness is 180 μm. After molding, the substrate is removed and then post-cured. The post-curing temperature is 150℃ and the post-curing time is 2 h to obtain the LED display module.

[0146] Performance testing

[0147] Flame retardancy test: LED modules with specifications of 270 mm × 295 mm were prepared and flame retardancy tests were conducted according to BS 476-7 Class 1 standard. The flame spread results were obtained and are shown in Table 4.

[0148] Internal and external haze tests: The dispersed and degassed adhesive was poured into a 30 mm × 30 mm × 0.5 mm thick PTFE fixture. After curing, it was removed and the total haze W was measured using a haze meter. Then, a 50 μm thick layer of OCA tape with a haze < 0.5% was applied to the surface, and the haze W1 was measured again using a haze meter. The internal haze is then determined to be W1, and the external haze to be W-W1, as shown in Table 4.

[0149] Carbon Residue Test: The carbon residue of the cured encapsulating adhesive was tested using a TGA tester. 10 mg of the cured encapsulating adhesive was placed in a ceramic crucible and placed in the TGA tester, and the test program was set. The heating rate was 10℃ / min, the atmosphere was N2, and the temperature was set from 40℃ to 750℃. The results are shown in Table 4.

[0150] Module reliability testing: The molded and cured module was lit up and placed in a device at 85℃ and 85% humidity for 168 hours. The display effect was observed for any abnormalities, and the lamp surface was checked for cracks, bubbles, wrinkles, or other appearance abnormalities. The molded and cured module was then lit up and subjected to thermal shock testing at -40℃ to 80℃, with a cold shock time of 30 minutes and a hot shock time of 30 minutes, constituting one cycle. A total of 500 cycles were performed, and the display effect was observed for any abnormalities, and the lamp surface was checked for cracks, bubbles, or other appearance abnormalities. The results are shown in Table 4.

[0151] Module UV aging resistance test: The molded and cured module is placed in a UV aging test equipment. UV aging conditions: test chamber temperature 80℃, irradiation intensity 0.76 W / m 2(340 nm), time 8 h; then stored in a 50℃ aging chamber for 4 h, this is one cycle, a total of 14 cycles, or 168 h. The yellowness index was measured using a yellowness index meter, and the results are shown in Table 4.

[0152] Table 4 Performance test results of the display module prepared in Example 2

[0153]

[0154] Note: The numbers in Table 4 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0155] Comparative Example 1

[0156] The ingredients and preparation method are the same as in Example 1, except that aluminum hydroxide with the same particle size is used instead of surface-treated aluminum hydroxide.

[0157] The detection was performed according to the detection method in Example 1, and the results are shown in Table 5.

[0158] Table 5 Performance test results of the display module prepared in Comparative Example 1

[0159]

[0160] Note: The numbers in Table 5 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0161] Comparative Example 2

[0162] The ingredients and preparation method are the same as in Example 1, except that the particle size of the surface-treated aluminum hydroxide is 500 nm.

[0163] The detection was performed according to the detection method in Example 1, and the results are shown in Table 6.

[0164] Table 6 Performance test results of the display module prepared in Comparative Example 2

[0165]

[0166] Note: The numbers in Table 6 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0167] Comparative Example 3

[0168] The ingredients and preparation method are the same as in Example 1, except that the particle size of the surface-treated aluminum hydroxide is 15 μm.

[0169] The detection was performed according to the detection method in Example 1, and the results are shown in Table 7.

[0170] Table 7 Performance test results of the display module prepared in Comparative Example 3

[0171]

[0172] Note: The numbers in Table 7 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0173] Comparative Example 4

[0174] The ingredients and preparation method are the same as in Example 1, except that surface-treated alumina is used (the preparation method is the same as the surface-treated aluminum hydroxide in Example 1, except that aluminum hydroxide is replaced with alumina of the same particle size).

[0175] The detection was performed according to the detection method in Example 1, and the results are shown in Table 8.

[0176] Table 8 Performance test results of the display module prepared in Comparative Example 4

[0177]

[0178] Note: The numbers in Table 8 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0179] Comparative Example 5

[0180] The ingredients and preparation method are the same as in Example 1, except that the matrix resin is replaced with 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarbamate instead of epoxybisphenol A-E12.

[0181] The detection was performed according to the detection method in Example 1, and the results are shown in Table 9.

[0182] Table 9 Performance test results of the display module prepared in Comparative Example 5

[0183]

[0184] Note: The numbers in Table 9 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0185] Comparative Example 6

[0186] The ingredients and preparation method are the same as in Example 1, except that no carbonization catalyst is added and the amount of matrix resin is increased.

[0187] The detection was performed according to the detection method in Example 1, and the results are shown in Table 10.

[0188] Table 10 Performance test results of the display module prepared in Comparative Example 6

[0189]

[0190] Note: The numbers in Table 10 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0191] Comparative Example 7

[0192] The ingredients and preparation method are the same as in Example 1, except that the amount of char-forming catalyst is increased to 2 wt%, and the amount of matrix resin is reduced accordingly.

[0193] The detection was performed according to the detection method in Example 1, and the results are shown in Table 11.

[0194] Table 11 Performance test results of the display module prepared in Comparative Example 7

[0195]

[0196] Note: The numbers in Table 11 refer to the numbers of multiple samples in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0197] In summary, the metal hydroxide flame retardant added to the encapsulating adhesive provided by this invention, after surface-oriented modification, disperses well with the alicyclic epoxy resin. In the event of a fire, the metal hydroxide flame retardant decomposes and absorbs a large amount of heat, producing a dense oxide layer that inhibits flame propagation. Simultaneously, the addition of a metal-based catalyst transforms the incomplete combustion products of the polymer material under thermal radiation into residual char. These two additives result in a char content ≥45% and a dense char layer in the coating, providing excellent fire resistance. Especially in the BS476-7 test, the dense char layer can significantly reduce the flame spread distance, passing the Class 1 test and suitable for applications such as large commercial complexes and transportation hubs; the refractive index of the metal hydroxide flame retardant added in this invention, after surface orientation modification, is 1.53~1.55, while the refractive index of the alicyclic epoxy resin after curing is 1.50~1.52, with a refractive index difference of 0.03. After the composite material is molded, it will produce an internal haze of 5%~15%, which plays an internal diffusion role and reduces color separation; the particle size D90 of the surface-treated metal hydroxide added in this invention is 1~10. μm particles, after molding, form an uneven structure on the surface, with a surface haze of 40%~50%, which serves to prevent glare and reduce visual fatigue. The alicyclic epoxy resin used in this invention does not contain the benzene ring structure found in bisphenol A, thus it is resistant to ultraviolet radiation, does not yellow after long-term outdoor use, and the YI value after UV aging is <1.0. The high carbon residue dual-effect flame retardant and anti-glare encapsulating adhesive based on metal hydroxide of this invention can achieve internal diffusion, anti-glare, and flame retardant properties in a single molding process, replacing encapsulating adhesive and film application, simplifying the process, improving yield, and saving costs.

[0198] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An encapsulation adhesive characterized by, Comprising: a surface-treated metal hydroxide 40-60 parts by weight; a base resin 20-30 parts by weight; a carbonization catalyst 0.1-1 parts by weight; a curing agent and a curing accelerator 18-30 parts by weight; an auxiliary agent 0.1-1 parts by weight; the surface-treated metal hydroxide comprises a silane coupling agent surface-treated metal hydroxide; the base resin is selected from a cycloaliphatic epoxy resin and / or a cycloaliphatic epoxy resin derivative.

2. The encapsulation adhesive of claim 1, wherein, the particle size D90 of the surface-treated metal hydroxide is 1-10 μm; and / or, the refractive index of the surface-treated metal hydroxide is 1.53-1.55; and / or, the maximum decomposition temperature of the surface-treated metal hydroxide is 250-350℃.

3. The encapsulation adhesive of claim 1, wherein the surface-treated metal hydroxide is prepared by: immersing a metal hydroxide in a silane coupling agent solution, and then obtaining a surface-treated metal hydroxide after natural air-drying and heating treatment; the silane coupling agent solution comprises a silane coupling agent, water, and an alcohol solvent; the mass concentration of the silane coupling agent in the silane coupling agent solution is 1-5%.

4. The encapsulation adhesive of claim 3, wherein, the metal hydroxide is selected from magnesium hydroxide and / or aluminum hydroxide; the silane coupling agent is selected from one or more of a vinyl silane coupling agent, an epoxy silane coupling agent, an amino silane coupling agent, a urea silane coupling agent, and a mercapto silane coupling agent; the volume ratio of the water to the alcohol solvent is 1:(7-10); the pH value of the silane coupling agent solution is 5.5-7; the immersion time is 20-180 min; the immersion temperature is 20-60℃; the natural air-drying time is 0.5-2 h; the heating treatment temperature is 75-85℃; the heating treatment time is 5-30 min.

5. The encapsulation adhesive of claim 1, wherein, the molecular weight of the cycloaliphatic epoxy resin and the cycloaliphatic epoxy resin derivative is independently 100-1000 g / mol; and / or, the epoxy equivalent weight of the cycloaliphatic epoxy resin and the cycloaliphatic epoxy resin derivative is independently 100-300 g / mol; and / or, the refractive index of the cycloaliphatic epoxy resin and the cycloaliphatic epoxy resin derivative is independently 1.4-1.5; and / or, the cycloaliphatic epoxy resin derivative is selected from a silicon compound containing a cycloaliphatic epoxy group and / or an acrylate compound containing a cycloaliphatic epoxy group.

6. The encapsulation adhesive of claim 5, wherein, the cycloaliphatic epoxy resin is selected from one or more of bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carboxylate, di(3,4-epoxycyclohexylmethyl) carbonate, 2,2-bis(3,3'-epoxycyclohexyl)propane, 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid 6-[[6-[[6-(7-oxabicyclo[4.1.0]heptane-3-methoxy)-6-oxohexyl]oxy]-6-oxohexyl]oxy]-6-oxohexyl ester, and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carbonate. The alicyclic epoxy resin derivative is selected from one or more of 1,1,3,3-tetramethyl-1,3-bis-[2-[7-oxidobicyclo[4.1.0]hept-3-yl]ethyl]disiloxane, tetraepoxy cyclohexyl ethyl 2,4,6,8-tetramethylcyclotetrasiloxane, 3,4-epoxycyclohexylmethyl methacrylate and 2-(3,4-epoxycyclohexyl)ethyl triethoxysilane.

7. The encapsulation adhesive of claim 1, wherein, The char-forming catalyst is selected from a supported iron-based catalyst, a supported nickel-based catalyst and a supported cobalt-based catalyst; the particle size of the supported iron-based catalyst is 5-20 nm; the particle size of the supported nickel-based catalyst is 1-10 nm; and the particle size of the supported cobalt-based catalyst is 10-30 nm; And / or, the curing agent is selected from one or more of an amine curing agent, an acid anhydride curing agent and a phenol-formaldehyde resin curing agent; And / or, the curing accelerator comprises one or more of a tertiary amine accelerator, an imidazole derivative accelerator, an acetylacetone metal salt accelerator, a metal carboxylate accelerator, a peroxide accelerator and a phosphide accelerator; And / or, the auxiliary agent comprises a leveling agent and / or a silane coupling agent.

8. An LED display module, characterized in that, The LED display module comprises a substrate, a plurality of LED light emitting chips arranged on the substrate, and an encapsulating adhesive layer arranged between the plurality of LED light emitting chips and away from the surface of the substrate; the encapsulating adhesive layer is formed by the encapsulating adhesive of any one of claims 1-7. 9.The LED display module of claim 1, wherein, The thickness of the encapsulating adhesive layer is 100-500 μm.

10. A display screen, characterized by The LED display module comprises the LED display module of claim 8 or 9. The LED display module comprises the LED display module of claim 8 or 9.

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