Functional resin, preparation method thereof, potting glue and LED display module

Abstract

The invention belongs to the technical field of LED display screens, and particularly relates to functional resin, a preparation method of the functional resin, potting glue and an LED display module. The functional resin is formed by crosslinking bisphenol A epoxy resin, hollow microspheres modified by a silane coupling agent and a phosphorus flame retardant through an isocyanate crosslinking agent; the isocyanate crosslinker includes at least three isocyanate groups. Compared with the prior art, the functional resin provided by the invention contains bisphenol A epoxy resin, and can effectively protect an LED chip after being cured with an anhydride curing agent; meanwhile, the functional resin contains a phosphorus-based flame retardant component, has a flame-retardant function, and can realize a good flame-retardant effect when being used for packaging an LED (Light Emitting Diode); in addition, the functional resin also contains hollow particles with low refractive index, so that the functional resin has a good antireflection effect after being used for packaging an LED (Light Emitting Diode).

Description

Technical Field

[0001] The present invention belongs to the technical field of LED display screens, and in particular relates to a functionalized resin, a preparation method thereof, a potting glue and an LED display module. Background Art

[0002] COB (chip on board) and MIP (MLED in Package) are the mainstream solutions for lowering the dot pitch of LED displays (<1mm) and applying Mini / Micro LED chips (MLED). They have obvious advantages in high luminous efficiency and uniformity, compact design and high power density, heat dissipation performance, and cost-effectiveness.

[0003] LED display modules must meet both optical performance and safety requirements for indoor and outdoor use. Currently, both COB and MIP are encapsulated using potting glue. While this provides dust and water resistance, the potting glue, typically epoxy or silicone, lacks flame retardancy and poses a fire risk. The encapsulated glossy surface can easily cause visual fatigue in strong ambient light. Furthermore, the encapsulated surface has high reflectivity, resulting in high brightness in the dark state, which reduces display contrast. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a functionalized resin with flame retardant and anti-reflection functions, a preparation method thereof, a potting glue and an LED display module.

[0005] The present invention provides a functionalized resin, which is formed by cross-linking bisphenol A epoxy resin, hollow microspheres modified by a silane coupling agent, and a phosphorus flame retardant through an isocyanate cross-linking agent; the isocyanate cross-linking agent includes at least three isocyanate groups.

[0006] Preferably, the molecular weight of the bisphenol A epoxy resin is 300 to 700 g / mol; the epoxy equivalent weight of the bisphenol A epoxy resin is 180 to 250 g / eq.

[0007] Preferably, the hollow microspheres are selected from inorganic hollow microspheres and / or organic hollow microspheres; the inorganic hollow microspheres are selected from silica hollow microspheres; the organic hollow microspheres are selected from one or more of polystyrene hollow microspheres, polyacrylate hollow microspheres, polylactic acid hollow microspheres and thermoplastic elastomer hollow microspheres;

[0008] The refractive index of the hollow microspheres is less than 1.4;

[0009] The particle size of the hollow microspheres is 1 to 10 μm.

[0010] Preferably, the phosphorus-based flame retardant includes an organic phosphorus compound and / or a phosphorus-nitrogen-based flame retardant;

[0011] The organophosphorus compound includes phosphaphenanthrene compounds and / or phosphate compounds;

[0012] The phosphaphenanthrene compounds include one or more of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, an adduct of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and maleic acid, and hexa-(N-hydroxyethylamino-DOPO-methylene-phenoxy)-cyclotriphosphazene;

[0013] The phosphate compound includes one or more of triphenyl phosphate, pentaerythritol caged phosphate, bisphenol A bis(diphenyl) phosphate and resorcinol (diphenyl) phosphate.

[0014] Preferably, the hollow microspheres include hollow silica microspheres;

[0015] And / or, the phosphorus-based flame retardant is selected from one or more of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, an adduct of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and maleic acid, hexa-(N-hydroxyethylamino-DOPO-methylene-phenoxy)-cyclotriphosphazene and pentaerythritol caged phosphate;

[0016] And / or, the isocyanate cross-linking agent is selected from one or more of HDI trimer, TDI trimer, IPDI trimer, triphenylmethane triisocyanate and thiophosphate triphenyl isocyanate.

[0017] Preferably, the mass ratio of the bisphenol A epoxy resin, the hollow microspheres modified by the silane coupling agent, the phosphorus flame retardant and the isocyanate crosslinking agent is (80-90): (1-5): (10-20): (20-40).

[0018] The present invention also provides a method for preparing the functionalized resin, comprising the following steps:

[0019] In the presence of a catalyst, hollow microspheres modified with a silane coupling agent, a phosphorus-based flame retardant, a bisphenol A epoxy resin and an isocyanate crosslinking agent are heated in an organic solvent for reaction to obtain a functionalized resin.

[0020] The present invention also provides a potting glue comprising the above functionalized resin.

[0021] Preferably, it comprises 20 to 40 parts by weight of functionalized resin, 20 to 50 parts by weight of flame retardant and anti-glare particles, 20 to 40 parts by weight of curing agent and curing accelerator, and 0.1 to 1 part by weight of auxiliary agent; the flame retardant and anti-glare particles are phosphorus-based flame retardant particles.

[0022] The present invention also provides an LED display module, comprising a substrate, a plurality of LED light-emitting chips arranged on the substrate, and a potting compound arranged between the plurality of LED light-emitting chips and on a surface away from the substrate; the potting compound is formed by the above-mentioned potting glue.

[0023] The present invention provides a functionalized resin formed by cross-linking bisphenol A epoxy resin, hollow microspheres modified with a silane coupling agent, and a phosphorus-based flame retardant via an isocyanate crosslinker; the isocyanate crosslinker comprises at least three isocyanate groups. Compared with the prior art, the functionalized resin provided by the present invention contains bisphenol A epoxy resin, which can effectively protect LED chips after being cured with an anhydride curing agent. Furthermore, the functionalized resin contains a phosphorus-based flame retardant component, exhibiting flame retardancy and achieving excellent flame retardancy when used to encapsulate LEDs. Furthermore, the functionalized resin also contains hollow particles with a low refractive index, which provide excellent anti-reflection properties when used to encapsulate LEDs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic structural diagram of the functionalized resin provided by the present invention;

[0025] Figure 2 A schematic diagram of the preparation process of the LED display module provided by the present invention;

[0026] Figure 3 IR spectra of bisphenol A epoxy resin and the functionalized resin obtained in Example 1. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The present invention provides a functionalized resin, which is formed by cross-linking bisphenol A epoxy resin, hollow microspheres modified by a silane coupling agent, and a phosphorus flame retardant through an isocyanate cross-linking agent; the isocyanate cross-linking agent includes at least three isocyanate groups.

[0029] See also Figure 1 , Figure 1This is a schematic diagram of the structure of the functionalized resin provided by the present invention, wherein the circle on the left represents the hollow microsphere, R(N / P) represents the phosphorus-based flame retardant; and the middle R represents the group of the isocyanate crosslinker other than the isocyanate group.

[0030] According to the present invention, the molecular weight of the bisphenol A epoxy resin is preferably 300-700 g / mol; a molecular weight lower than this will reduce the cross-linking density, which may lead to insufficient heat resistance and mechanical strength; a molecular weight higher than this will have poor miscibility with fillers, resulting in uneven components after molding, thereby affecting appearance and performance; optionally, the molecular weight of the bisphenol A epoxy resin is 300 g / mol, 350 g / mol, 400 g / mol, 450 g / mol, 500 g / mol, 550 g / mol, 600 g / mol, 650 g / mol, 700 g / mol or a range between any two of the above values.

[0031] According to the present invention, the epoxy equivalent of the bisphenol A epoxy resin is preferably 180 to 250 g / eq; an epoxy equivalent below this may result in excessively high crosslinking density and increased brittleness, while an epoxy equivalent above this may reduce heat resistance and chemical resistance; optionally, the epoxy equivalent of the bisphenol A epoxy resin is 180 g / eq, 190 g / eq, 200 g / eq, 210 g / eq, 220 g / eq, 230 g / eq, 240 g / eq, 250 g / eq or a range between any two of the above values.

[0032] According to the present invention, the silane coupling agent used in the hollow microspheres modified by the silane coupling agent is any silane coupling agent well known to those skilled in the art, and there is no special limitation. Considering the subsequent reactivity with isocyanate, the present invention preferably uses a silane coupling agent containing a mercapto group at the end, including but not limited to 3-mercaptopropylmethyldimethoxysilane and / or 3-mercaptopropyltrimethoxysilane; the hollow microspheres used in the hollow microspheres modified by the silane coupling agent are hollow microspheres well known to those skilled in the art, including inorganic hollow microspheres and / or organic hollow microspheres; the inorganic hollow microspheres are any inorganic hollow microspheres well known to those skilled in the art, and there is no special limitation, including but not limited to silica hollow microspheres; The organic hollow microspheres can be organic hollow microspheres well known to those skilled in the art without any special restrictions, including but not limited to one or more of polystyrene hollow microspheres, polyacrylate hollow microspheres, polylactic acid hollow microspheres and thermoplastic elastomer hollow microspheres; considering the cost and material refractive index, silica hollow microspheres are preferably used; the refractive index of the hollow microspheres is preferably less than 1.4, more preferably less than 1.37, and even more preferably less than 1.35; the particle size of the hollow microspheres is preferably 1 to 10 μm; optionally, the particle size of the hollow microspheres is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or a range between any two of the above values.

[0033] According to the present invention, the phosphorus-based flame retardant preferably includes an organic phosphorus compound and / or a phosphorus-nitrogen-based flame retardant; the organic phosphorus compound includes but is not limited to phosphaphenanthrene compounds and / or phosphate compounds; the phosphorus-nitrogen-based flame retardant includes but is not limited to one or more of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, an adduct of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and maleic acid, and hexa(N-hydroxyethylamino-DOPO-methylene-phenoxy)-cyclotriphosphazene; the phosphate compound preferably includes but is not limited to one or more of triphenyl phosphate, pentaerythritol caged phosphate, bisphenol A bis(diphenyl) phosphate, and resorcinol (diphenyl) phosphate.

[0034] In order to make the phosphorus-based flame retardant more easily react with the isocyanate crosslinker, the phosphorus-based flame retardant preferably contains one or more of a hydroxyl group, an amino group, and a carboxyl group; in a specific embodiment provided by the present invention, the phosphorus-based flame retardant includes but is not limited to one or more of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, an adduct of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and maleic acid, hexa-(N-hydroxyethylamino-DOPO-methylene-phenoxy)-cyclotriphosphazene, and pentaerythritol caged phosphate.

[0035] According to the present invention, the isocyanate crosslinking agent preferably includes but is not limited to one or more of HDI trimer, TDI trimer, IPDI trimer, triphenylmethane triisocyanate and thiophosphate triphenyl isocyanate.

[0036] According to the present invention, the mass ratio of the bisphenol A epoxy resin, the hollow microspheres modified by the silane coupling agent, the phosphorus flame retardant and the isocyanate crosslinking agent is preferably (80-90): (1-5): (10-20): (20-40), more preferably (80-85): (2-5): (10-18): (20-35), further preferably (80-82): (3-5): (10-15): (20-33), and most preferably 80: (3-5): (10-15): (20-30).

[0037] The present invention also provides a method for preparing the above-mentioned functionalized resin, comprising the following steps: in the presence of a catalyst, heating hollow microspheres modified with a silane coupling agent, a phosphorus-based flame retardant, a bisphenol A epoxy resin and an isocyanate crosslinking agent in an organic solvent to react to obtain a functionalized resin.

[0038] The present invention has no particular limitation on the sources of all raw materials, and any commercially available raw materials may be used.

[0039] According to the present invention, the catalyst is preferably an organotin catalyst, including but not limited to dibutyltin dilaurate.

[0040] According to the present invention, the mass ratio of the bisphenol A epoxy resin, the hollow microspheres modified by the silane coupling agent, the phosphorus flame retardant, the isocyanate crosslinking agent and the catalyst is preferably (80-90): (1-5): (10-20): (20-40): (0.05-0.1), more preferably (80-85): (2-5): (10-18): (20-35): (0.05-0.08), further preferably (80-82): (3-5): (10-15): (20-33): (0.05-0.06), and most preferably 80: (3-5): (10-15): (20-30): 0.05.

[0041] According to the present invention, the hollow microspheres modified with the silane coupling agent can be prepared by methods well known to those skilled in the art without particular limitation. Specifically, the steps are as follows: A1) pre-treating the hollow microspheres to form surface hydroxyl groups; hydrolyzing the silane coupling agent in an acidic alcohol aqueous solution to obtain a hydrolyzed silane solution; and A2) mixing the pre-treated hollow microspheres with the hydrolyzed silane solution, heating the mixture for reaction, and obtaining the hollow microspheres modified with the silane coupling agent.

[0042] In a specific embodiment provided by the present invention, the pretreatment method in step A1) is a method well known to those skilled in the art and is not particularly limited. Preferably, the method comprises: soaking the hollow microspheres in a sodium hydroxide solution, ultrasonically treating, centrifuging, washing, and drying to obtain pretreated hollow microspheres; the concentration of the sodium hydroxide solution is preferably 0.1 to 1 mol / L, more preferably 0.5 to 1 mol / L; the ultrasonic treatment time is preferably 20 to 40 min; the centrifugal speed is preferably 5000 to 10000 rpm, more preferably 5000 to 8000 rpm; the centrifugal time is preferably 5 to 10 min; the washing is preferably carried out with deionized water; the washing is preferably carried out until neutral; the drying is preferably vacuum drying; the drying temperature is preferably 50° C. to 100° C.; and the drying time is preferably 4 to 6 h.

[0043] By putting the silane coupling agent into water, it can be hydrolyzed into active silanol, which is convenient for the subsequent condensation reaction. In a specific embodiment provided by the present invention, the silane coupling agent is hydrolyzed in an acidic alcohol aqueous solution to obtain a hydrolyzed silane solution; the alcohol in the alcohol aqueous solution is preferably ethanol; the volume ratio of alcohol to water in the alcohol aqueous solution is preferably (92-98): (8-2), more preferably (94-96): (4-6), and even more preferably 95:5; the pH value of the acidic alcohol aqueous solution is preferably 3-5, more preferably 3-4; the acidic alcohol aqueous solution is preferably adjusted to pH value with glacial acetic acid; the mass of the silane coupling agent is preferably 1% to 5% of the total mass of the silane coupling agent and the acidic alcohol aqueous solution, more preferably 3% to 5%; the hydrolysis is preferably carried out under stirring conditions. The stirring speed is preferably 500-1500 rpm; optionally, the stirring speed is 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm or a range between any two of the above values; the hydrolysis time is preferably 30-60 min; optionally, the hydrolysis time is 30 min, 40 min, 50 min, 60 min or a range between any two of the above values; specifically, the hydrolysis is carried out until the solution is transparent and free of precipitation to obtain a hydrolyzed silane solution.

[0044] The pretreated hollow microspheres are mixed with the hydrolyzed silane solution and heated for reaction; the mass ratio of the pretreated hollow microspheres to the hydrolyzed silane solution is preferably 1: (10-20); optionally, the mass ratio of the pretreated hollow microspheres to the hydrolyzed silane solution is 1: 10, 1: 11, 1: 12, 1: 13, 1: 14, 1: 15, 1: 16, 1: 17, 1: 18, 1: 19, 1: 20 or a range between any two of the above ratios; the heating reaction The corresponding temperature is preferably 40°C to 60°C, more preferably 45°C to 60°C, and more preferably 50°C to 60°C; the heating reaction time is preferably 2 to 6 hours, more preferably 3 to 6 hours, and more preferably 4 to 6 hours; the heating reaction is preferably carried out under stirring; the stirring speed is preferably 200 to 500 rpm; optionally, the stirring speed is 200 rpm, 300 rpm, 400 rpm, 500 rpm or a range between any two of the above values.

[0045] After the heating reaction, the reaction is preferably centrifuged, washed to remove the unreacted coupling agent, and dried to obtain hollow microspheres modified with a silane coupling agent; the centrifugal separation speed is preferably 5000 to 10000 rpm; the centrifugal separation time is preferably 5 to 10 minutes, more preferably 5 to 8 minutes; the washing is preferably carried out with an ethanol aqueous solution; the number of washes is preferably 2 to 3 times; the drying is preferably vacuum drying; the drying temperature is preferably 80°C to 120°C, more preferably 80°C to 110°C, and more preferably 80°C to 100°C; the drying time is preferably 2 to 4 hours; and drying can promote Si-O-Si crosslinking.

[0046] In a specific embodiment provided by the present invention, after drying, washing optimization is preferably performed, centrifugal separation is performed, and the loose adsorption layer is removed to obtain hollow microspheres modified with a silane coupling agent; the washing optimization is preferably performed using an ethanol-water solution with a volume ratio of 1: (0.5-2), more preferably using an ethanol-water solution with a volume ratio of 1: (0.5-1.5), more preferably using an ethanol-water solution with a volume ratio of 1: (0.8-1.2), and most preferably using an ethanol-water solution with a volume ratio of 1: 1; the washing optimization is preferably ultrasonic washing.

[0047] In the presence of a catalyst, hollow microspheres modified with a silane coupling agent, a phosphorus-based flame retardant, a bisphenol A epoxy resin, and an isocyanate crosslinking agent are heated in an organic solvent for reaction to obtain a functionalized resin; the organic solvent is any organic solvent well known to those skilled in the art and is not particularly limited. In the present invention, dichloromethane is preferably used; the reaction temperature is preferably 40° C. to 80° C.; the reaction time is preferably 5 to 10 hours; the reaction is preferably carried out in a protective atmosphere; the protective atmosphere is any protective atmosphere well known to those skilled in the art and is not particularly limited. In the present invention, nitrogen is preferably used; the reaction is preferably carried out under stirring; and the stirring speed is preferably 1000 to 2000 rpm.

[0048] In a specific embodiment provided by the present invention, preferably, the hollow microspheres modified with a silane coupling agent are first mixed with an organic solvent and ultrasonically dispersed for the first time; then, a phosphorus-based flame retardant and a bisphenol A epoxy resin are added and ultrasonically dispersed for the second time; then, an isocyanate crosslinking agent and a catalyst are added and ultrasonically dispersed for the third time; and finally, heating is performed to react to obtain a hybrid flame retardant material; and the time for the first ultrasonic dispersion, the second ultrasonic dispersion, and the third ultrasonic dispersion are each independently preferably 10 to 30 minutes.

[0049] After the reaction is completed, the solvent is removed, and the mixture is stirred in an alcohol solvent to induce precipitation, filtered, washed, and dried to obtain a functionalized resin. The method for removing the solvent is a method well known to those skilled in the art and is not particularly limited. In the present invention, the solvent is preferably removed by evaporation under reduced pressure. The temperature for evaporating the solvent under reduced pressure is preferably 40°C to 60°C. The alcohol solvent is preferably methanol. Specifically, the product from which the solvent is removed is slowly added dropwise to an alcohol solvent and stirred to induce precipitation. The washing is preferably carried out with an alcohol solvent, more preferably with methanol. The number of washings is preferably 2 to 3 times. The drying is preferably vacuum drying. The drying temperature is preferably 40°C to 60°C. The drying time is preferably 12 to 24 hours.

[0050] The present invention also provides a potting glue comprising the above functionalized resin.

[0051] According to the present invention, specifically, the potting glue includes 20 to 40 parts by weight of functionalized resin, 20 to 50 parts by weight of flame retardant and anti-glare particles, 20 to 40 parts by weight of curing agent and curing accelerator, and 0.1 to 1 part by weight of auxiliary agent; the flame retardant and anti-glare particles are phosphorus-based flame retardant particles.

[0052] In a specific embodiment provided by the present invention, optionally, the content of the functionalized resin in the potting glue is 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight or a range between any two of the above values.

[0053] In a specific embodiment provided by the present invention, optionally, the content of the flame retardant anti-glare particles in the potting glue is 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight or a range between any two of the above values.

[0054] According to the present invention, the phosphorus-based flame retardant particles can be used as outward-diffusion particles to scatter surface light and blur edges; the phosphorus-based flame retardant particles are preferably one or more of organic hypophosphites, phosphaphenanthrene flame retardants, phosphate flame retardants, and phosphorus-nitrogen flame retardants; the organic hypophosphites are organic hypophosphites well known to those skilled in the art, and are not particularly limited. In the present invention, preferably include but are not limited to one or more of methylethylphosphinate, diethylphosphinate, and methylcyclohexylphosphinate; the phosphaphenanthrene flame retardants are phosphaphenanthrene flame retardants well known to those skilled in the art, and are not particularly limited. In the present invention, preferably include but are not limited to 9,10- Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and / or 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide; the phosphate flame retardant is any phosphate flame retardant well known to those skilled in the art, without any special restrictions, and preferably includes but is not limited to one or more of triphenyl phosphate, pentaerythritol caged phosphate, bisphenol A bis(diphenyl) phosphate and resorcinol (diphenyl) phosphate; the phosphorus-nitrogen flame retardant is any phosphazene flame retardant well known to those skilled in the art, without any special restrictions, and preferably includes but is not limited to phosphazene and / or ammonium polyphosphate.

[0055] To ensure the anti-glare function of the coating, the particle size of the phosphorus-based flame retardant particles is 1 to 10 μm; below this particle size, the surface roughness is insufficient and the anti-glare performance decreases, and above this particle size, the coating will appear white in appearance; optionally, the particle size of the phosphorus-based flame retardant particles is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or a range between any two of the above values.

[0056] In a specific embodiment provided by the present invention, optionally, the content of the curing agent and the curing accelerator in the potting glue is 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight or a range between any two of the above values.

[0057] According to the present invention, the mass ratio of the curing agent to the curing accelerator is preferably 1:0.1-0.2.

[0058] According to the present invention, the curing agent is any curing agent well known to those skilled in the art without any particular limitation, and includes one or more of an amine curing agent, an acid anhydride curing agent, and a phenolic resin curing agent; 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 isophoronediamine, menthanediamine, etc.; the aromatic amine curing agent includes but is not limited to diaminodiphenylmethane, diaminodiphenyl ether, etc.; the polyamide curing agent is formed by condensation of dimerized vegetable oil fatty acid and aliphatic amine; the acid anhydride curing agent includes but is not limited to phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc.

[0059] According to the present invention, the curing accelerator includes one or more of a tertiary amine accelerator, an imidazole derivative accelerator, an acetylacetonate metal salt accelerator, a metal carboxylate accelerator, a peroxide accelerator and a phosphide accelerator; the tertiary amine accelerator includes but is not limited to 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, triethylamine, triethanolamine, o-hydroxybenzyldimethylamine, etc.; the imidazole derivative accelerator includes but is not limited to one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole; the general formula of the acetylacetonate metal salt accelerator is 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 accelerator includes but is not limited to stannous octoate, lead octoate, etc.; the peroxide accelerator includes but is not limited to benzoyl peroxide, etc.; the phosphide accelerator includes but is not limited to triphenylphosphine, etc.

[0060] In a specific embodiment provided by the present invention, optionally, the content of the auxiliary agent in the potting glue is 0.1 parts by weight, 0.2 parts by weight, 0.6 parts by weight, 0.8 parts by weight, 1 part by weight or a range between any two of the above values.

[0061] By adding additives, certain properties of the potting glue can be improved, such as improving the leveling, uniformity and adhesion of the glue. In the present invention, the additives preferably include one or more of a leveling agent, a silane coupling agent and a defoaming agent.

[0062] According to the present invention, the leveling agent includes one or more of an organosilicon leveling agent, an acrylate leveling agent and a fluorocarbon leveling agent; the organosilicon 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 agent, fluorine-modified acrylate leveling agent, etc.

[0063] According to the present invention, the silane coupling agent includes but is not limited to one or more of vinyl silane coupling agent, epoxy silane coupling agent, amino silane coupling agent, urea silane coupling agent and mercapto silane coupling agent; the vinyl silane coupling agent includes but is not limited to vinyl triethoxysilane, vinyl trimethoxysilane, etc.; the epoxy silane coupling agent includes but is not limited to 2-(3,4-epoxycyclohexyl) ethyl trimethoxysilane, 3-glycidyloxypropyl methyl dimethoxysilane, 3-glycidyloxypropyl trimethoxysilane, 3-glycidyloxypropyl methyl diethoxysilane , 3-glycidoxypropyltriethoxysilane, etc.; the aminosilane coupling agent includes but is not limited to γ-aminopropyltriethoxysilane (KH550), N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH792), N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane (KH602), etc.; the urea-based silane coupling agent includes but is not limited to γ-urea-based propyl-trimethoxysilane, γ-urea-based propyl-methyldimethoxysilane, etc.; the mercaptosilane coupling agent includes but is not limited to 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, etc.

[0064] According to the present invention, the defoaming agent includes silicone defoaming agent and / or non-silicone defoaming agent; the silicone defoaming agent includes but is not limited to polydimethylsiloxane defoaming agent, polyether modified silicone defoaming agent, etc.; the non-silicone defoaming agent includes but is not limited to mineral oil-based defoaming agent, polyether defoaming agent, alcohol defoaming agent, etc.

[0065] According to the present invention, the potting glue can be prepared according to a method well known to those skilled in the art without any special restrictions. Specifically, it can be carried out according to the following steps: functionalized resin, flame retardant and anti-glare particles, curing agent, curing accelerator and auxiliary agent are degassed by vacuum stirring to obtain potting glue; the stirring speed is preferably 1000-2000 rpm; the stirring time is 10-20 minutes; after vacuum stirring and degassed, it is preferably allowed to stand; the standing time is preferably 10-20 minutes.

[0066] The present invention also provides an LED display module, comprising a substrate, a plurality of LED light-emitting chips arranged on the substrate, and a potting compound arranged between the plurality of LED light-emitting chips and on a surface away from the substrate; the potting compound is formed by the above-mentioned potting glue.

[0067] The present invention also provides a method for preparing the above-mentioned LED display module, comprising the following steps: fixing a substrate provided with a plurality of LED light-emitting chips on a preset molding jig after plasma cleaning, coating the above-mentioned potting glue on a release film for molding, and then taking it out for curing to obtain an LED display module; the molding temperature is preferably 130°C to 180°C, more preferably 140°C to 160°C, and even more preferably 150°C; the molding time is preferably 5 to 15 minutes; since the molding is carried out under heating conditions, the potting glue can also be pre-cured during the molding; the molding thickness is preferably 150 to 250 μm; the curing temperature is 130°C to 180°C; and the curing time is preferably 1 to 3 hours.

[0068] See also Figure 2 , Figure 2 This is a schematic diagram of the preparation process of the LED display module provided by the present invention.

[0069] The present invention also provides a display screen, comprising the above-mentioned LED display module.

[0070] To further illustrate the present invention, a functionalized resin, a preparation method thereof, a potting glue, and an LED display module provided by the present invention are described in detail below with reference to embodiments.

[0071] The reagents used in the following examples are all commercially available.

[0072] Example 1

[0073] Table 1 Composition of potting glue in Example 1

[0074]

[0075] 1.1 Preparation of functionalized main resin

[0076] (1) Hollow silica particles with a particle size of 1 μm and a refractive index of 1.35 were weighed and immersed in a 1 mol / L NaOH solution. The mixture was ultrasonically treated for 20 min, centrifuged (speed 5000 rpm, time 5 min) to remove the supernatant, washed with deionized water to neutrality (pH = 7), and vacuum dried at 50°C for 6 h to obtain pretreated hollow silica particles.

[0077] (2) Prepare an ethanol-water mixed solution with a volume ratio of 95:5, add the silane coupling agent 3-mercaptopropylmethyldimethoxysilane to a concentration of 3%, adjust the pH to 3 with glacial acetic acid, and stir magnetically at 500 rpm for 30 minutes until the solution is transparent and free of precipitation, thereby obtaining a hydrolyzed silane solution.

[0078] (3) The pretreated hollow silica particles were added to the hydrolyzed silane solution at a mass ratio of 1:10, reacted in a constant temperature water bath (constant temperature water bath temperature 60°C, stirring speed 500 ppm, stirring time 6 h), centrifuged at 5000 rpm for 5 min, and washed three times with an ethanol-water mixture to remove the unreacted coupling agent.

[0079] (4) Drying: The modified particles were placed in a vacuum drying oven and dried at 80 °C for 2 h to promote Si-O-Si crosslinking. Washing optimization: Ultrasonic washing was performed twice with an ethanol-water mixture with a volume ratio of 1:1, and centrifuged to remove the loose adsorption layer to obtain the modified hollow particles.

[0080] (5) Take 5 g of the modified hollow particles and add them to 500 g of organic solvent dichloromethane, and ultrasonically disperse them for 10 min; add 10 g of pentaerythritol caged phosphate flame retardant and 80 g of bisphenol A epoxy resin (epoxy equivalent 180 g / eq, molecular weight 500 g / mol) to the dispersion, and continue ultrasonically dispersing for 10 min; add 20 g of the modifier HDI trimer and 0.05 g of the catalyst dibutyltin dilaurate, and continue ultrasonically dispersing for 10 min; then stir the reaction in an oil bath at 60 ° C, the stirring speed is 1000 rpm, the stirring time is 5 h, and N2 is introduced during the reaction; the reaction solution is transferred to a rotary evaporator, and the solvent is evaporated under reduced pressure (vacuum degree 0.1 MPa) at 40 ° C; the concentrated product is slowly added dropwise to methanol, stirred to induce precipitation, filtered with a Buchner funnel, and the filter cake is washed twice with methanol; the product is placed in a vacuum oven and dried at 40 ° C for 12 h to obtain a functionalized resin.

[0081] 1.2 Add the materials into the ingredient tray according to the ingredient list in Table 1, use a vacuum high-speed stirring degassing machine to stir and degas, the speed is 1000 rpm, the time is 10 minutes, and the dispersed materials are allowed to stand for 10 minutes to obtain the potting glue.

[0082] 1.3 After plasma cleaning, the LED light board with the chip and driver IC is fixed on the preset molding fixture, and the glue is squeezed onto the release film for pressing. The pressing temperature is 150℃, the pressing time is 5min, and the molding thickness is 150μm. After molding, the substrate is removed and post-cured at 150℃ and 2h to obtain the LED display module.

[0083] The bisphenol A epoxy resin and the functionalized resin obtained in Example 1 were analyzed by infrared spectroscopy, and their infrared spectra were as follows: Figure 3 shown.

[0084] Performance Testing

[0085] Flame retardancy testing: Five strips of the cured LED modules, measuring 125 mm long by 13 mm wide, were cut and subjected to flame retardancy testing according to UL 94. The flame spread test results are shown in Table 2. Five sets of 270 mm by 295 mm LED modules were prepared and subjected to flame spread testing according to BS 476-7. The flame spread test results are shown in Table 2.

[0086] Anti-glare test: The cured LED module was subjected to a light shadow test, and the results are shown in Table 2.

[0087] Reflectivity test: The reflectivity of the surface of the packaged LED module was tested using a reflectivity tester. The results are shown in Table 2.

[0088] Table 2 Test results of Example 1

[0089]

[0090] Note: The numbers in Table 2 refer to multiple sample numbers in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0091] Example 2

[0092] Table 3 Composition of potting glue in Example 2

[0093]

[0094] 2.1 Preparation of functionalized main resin

[0095] (1) Hollow silica particles with a particle size of 3 μm and a refractive index of 1.30 were weighed and immersed in a 0.5 mol / L NaOH solution. The solution was ultrasonically treated for 40 min and centrifuged (speed 8000 rpm, time 10 min) to remove the supernatant. The solution was washed with deionized water until neutral (pH = 7) and vacuum dried at 100 °C for 4 h to obtain pretreated hollow silica particles.

[0096] (2) Prepare a mixed solution of ethanol and water with a volume ratio of 95:5, add the silane coupling agent 3-mercaptopropylmethyldimethoxysilane to a concentration of 5%, adjust the pH to 4 with glacial acetic acid, and stir magnetically at 1500 rpm for 40 minutes until the solution is transparent and free of precipitation, thereby obtaining a hydrolyzed silane solution.

[0097] (3) The pretreated hollow silica particles were added to the hydrolyzed silane solution at a mass ratio of 1:20, reacted in a constant temperature water bath (constant temperature water bath temperature 60°C, stirring speed 500 ppm, stirring time 4 h), centrifuged at 10,000 rpm for 8 min, and washed three times with an ethanol-water mixture to remove the unreacted coupling agent.

[0098] (4) Drying: The modified particles were placed in a vacuum drying oven and dried at 100 °C for 4 h to promote Si-O-Si crosslinking. Washing optimization: Ultrasonic washing was performed twice with an ethanol-water mixture (volume ratio 1:1), and centrifuged to remove the loose adsorption layer to obtain the modified hollow particles.

[0099] (5) Take 3g of the modified hollow particles and add them to 500g of organic solvent dichloromethane, and ultrasonically disperse them for 20min; add 15g of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphophananthen-10-oxide flame retardant and 80g of bisphenol A epoxy resin (epoxy equivalent 200g / eq, molecular weight 300g / mol) to the dispersion, and continue ultrasonically disperse them for 20min; add 30g of the modifier triphenylmethane triisocyanate and the catalyst dibutyl dilaurate; 0.05 g of tin was added and ultrasonic dispersion was continued for 10 min. The mixture was then stirred in an oil bath at 80°C with a stirring speed of 1200 rpm for 8 h, and N2 was introduced during the reaction. The reaction solution was transferred to a rotary evaporator and the solvent was evaporated under reduced pressure (vacuum degree 0.1 MPa) at 60°C. The concentrated product was slowly added dropwise to methanol, stirred to induce precipitation, and filtered with a Buchner funnel. The filter cake was washed twice with methanol. The product was placed in a vacuum oven and dried at 50°C for 20 h to obtain a functionalized resin.

[0100] 2.2 Add the materials into the ingredient tray according to the proportions listed in Table 3, use a vacuum high-speed stirring degassing machine to stir and degas, the speed is 1000 rpm, the time is 10 minutes, and the dispersed materials are allowed to stand for 10 minutes to obtain the potting glue.

[0101] 2.3 After plasma cleaning, the LED light board with the chip and driver IC is fixed on the preset molding fixture, and the glue is squeezed onto the release film for pressing. The pressing temperature is 130℃, the pressing time is 15min, and the molding thickness is 190μm. After molding, the substrate is removed and post-cured at 13℃ and 3h to obtain the LED display module.

[0102] Performance Testing

[0103] Flame retardancy testing: Five strips of the cured LED modules, measuring 125 mm long by 13 mm wide, were cut and subjected to flame retardancy testing according to UL 94. The flame spread test results are shown in Table 4. Five sets of 270 mm by 295 mm LED modules were prepared and subjected to flame spread testing according to BS 476-7. The flame spread results are shown in Table 4.

[0104] Anti-glare test: The cured LED module was subjected to a light shadow test, and the results are shown in Table 4.

[0105] Reflectivity test: The reflectivity of the surface of the packaged LED module was tested using a reflectivity tester. The results are shown in Table 4.

[0106] Table 4 Test results of Example 2

[0107]

[0108] Note: The numbers in Table 4 refer to multiple sample numbers in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0109] Comparative Example 1

[0110] The preparation method is the same as that in Example 1, and the amount of raw materials is the same as that in Example 1, except that the functionalized resin is not prepared. The modified hollow particles, pentaerythritol caged phosphate flame retardant, bisphenol A epoxy resin, modifier HDI trimer, catalyst dibutyltin dilaurate, flame retardant and anti-glare particles, curing agent, catalyst and leveling agent are directly stirred and degassed using a vacuum high-speed stirring degassing machine.

[0111] The test was carried out according to the test method of Example 1, and the results are shown in Table 5.

[0112] Table 5 Test results of comparative example 1

[0113]

[0114]

[0115] Note: The numbers in Table 5 refer to multiple sample numbers in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0116] Comparative Example 2

[0117] The preparation method is the same as that of Example 1, except that the hollow silica particles are replaced with solid silica when preparing the functionalized main resin.

[0118] The test was carried out according to the test method of Example 1, and the results are shown in Table 6.

[0119] Table 6 Test results of comparative example 2

[0120]

[0121] Note: The numbers in Table 6 refer to multiple sample numbers in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0122] Comparative Example 3

[0123] The preparation method is the same as that of Example 1, except that the pentaerythritol caged phosphate flame retardant is replaced by triphenyl phosphate without active functional groups during the preparation of the functionalized main resin.

[0124] The test was carried out according to the test method of Example 1, and the results are shown in Table 7.

[0125] Table 7 Test results of comparative example 3

[0126]

[0127]

[0128] Note: The numbers in Table 7 refer to multiple sample numbers in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0129] Comparative Example 4

[0130] The preparation method is the same as that of Example 1, except that the modifier HDI trimer is replaced by n-butyl isocyanate during the preparation of the functionalized main resin.

[0131] The test was carried out according to the test method of Example 1, and the results are shown in Table 8.

[0132] Table 8 Test results of comparative example 4

[0133]

[0134] Note: The numbers in Table 8 refer to multiple sample numbers in different tests. Samples with the same number in different tests are not necessarily the same sample.

[0135] As can be seen from the above, the LED display module prepared by the present invention can pass the UL-94V-0 and 5VA standards, and can also pass the Class 1 standard of BS476-7, indicating that this LED module and display screen can be used in buildings; and the functionalized resin contains hollow particles with a low refractive index, so it has an anti-reflection effect after encapsulation, and the module reflectivity is ≤3%; the flame-retardant and anti-glare particles in the potting glue have an anti-glare effect, which can reduce the irritation and burden caused by ambient light reflection to the human eye; the LED display module and display screen using the potting glue provided by the present invention have anti-glare, anti-reflection and flame-retardant effects, simple process, and good cost advantages.

[0136] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A functionalized resin, characterized in that: The functionalized resin is formed by cross-linking bisphenol A epoxy resin, hollow microspheres modified by a silane coupling agent, and a phosphorus-based flame retardant through an isocyanate cross-linking agent; the isocyanate cross-linking agent includes at least three isocyanate groups.

2. The functionalized resin according to claim 1, characterized in that The molecular weight of the bisphenol A epoxy resin is 300 to 700 g / mol; the epoxy equivalent of the bisphenol A epoxy resin is 180 to 250 g / eq.

3. The functionalized resin according to claim 1, characterized in that The hollow microspheres are selected from inorganic hollow microspheres and / or organic hollow microspheres; the inorganic hollow microspheres are selected from silica hollow microspheres; the organic hollow microspheres are selected from one or more of polystyrene hollow microspheres, polyacrylate hollow microspheres, polylactic acid hollow microspheres and thermoplastic elastomer hollow microspheres; The refractive index of the hollow microspheres is less than 1.4; The particle size of the hollow microspheres is 1 to 10 μm.

4. The functionalized resin according to claim 1, characterized in that The phosphorus-based flame retardant includes an organic phosphorus compound and / or a phosphorus-nitrogen-based flame retardant; The organophosphorus compound includes phosphaphenanthrene compounds and / or phosphate compounds; The phosphaphenanthrene compounds include one or more of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, an adduct of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and maleic acid, and hexa-(N-hydroxyethylamino-DOPO-methylene-phenoxy)-cyclotriphosphazene; The phosphate compound includes one or more of triphenyl phosphate, pentaerythritol caged phosphate, bisphenol A bis(diphenyl) phosphate and resorcinol (diphenyl) phosphate.

5. The hybrid flame retardant material according to claim 1, characterized in that: The hollow microspheres include hollow silica microspheres; And / or, the phosphorus-based flame retardant is selected from one or more of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, an adduct of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and maleic acid, hexa-(N-hydroxyethylamino-DOPO-methylene-phenoxy)-cyclotriphosphazene and pentaerythritol caged phosphate; And / or, the isocyanate cross-linking agent is selected from one or more of HDI trimer, TDI trimer, IPDI trimer, triphenylmethane triisocyanate and thiophosphate triphenyl isocyanate.

6. The functionalized resin according to claim 1, characterized in that The mass ratio of the bisphenol A epoxy resin, the hollow microspheres modified by the silane coupling agent, the phosphorus flame retardant and the isocyanate crosslinking agent is (80-90): (1-5): (10-20): (20-40).

7. A method for preparing the functionalized resin according to any one of claims 1 to 6, characterized in that: The following steps are involved: In the presence of a catalyst, hollow microspheres modified with a silane coupling agent, a phosphorus-based flame retardant, a bisphenol A epoxy resin and an isocyanate crosslinking agent are heated in an organic solvent for reaction to obtain a functionalized resin.

8. A potting glue comprising the functionalized resin according to any one of claims 1 to 6 or the functionalized resin prepared by the preparation method according to claim 7.

9. The potting glue according to claim 8, characterized in that: The invention comprises 20 to 40 parts by weight of functionalized resin, 20 to 50 parts by weight of flame retardant and anti-glare particles, 20 to 40 parts by weight of curing agent and curing accelerator, and 0.1 to 1 part by weight of auxiliary agent; the flame retardant and anti-glare particles are phosphorus-based flame retardant particles.

10. An LED display module, characterized in that: It comprises a substrate, a plurality of LED light-emitting chips arranged on the substrate, and a potting glue arranged between the plurality of LED light-emitting chips and on a surface away from the substrate; the potting glue is formed by the potting glue according to claim 8 or 9.

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