Coating, LED display module and display screen

Abstract

The invention belongs to the technical field of LED display screens, and particularly relates to a coating, an LED display module and a display screen. Compared with the prior art, the coating provided by the invention has the following advantages: flame-retardant and fireproof safety: through a P-N bond chemical structure of polydichlorophosphazene modified resin, a synergistic flame-retardant effect of a gas phase (releasing flame-retardant free radicals) and a condensed phase (promoting char formation) is realized at the same time; the display quality is improved; the ambient light interference is remarkably reduced due to the low reflection characteristic, so that the display screen still keeps high contrast under strong light; the self-cleaning characteristic is that the surface water contact angle is larger than or equal to 105 degrees, so that the dust adhesion amount is remarkably reduced, and surface cleaning can be completed by rain wash; the combination of the epoxy functional group and the covalent bond of the resin ensures that the perfluorocarbon structure is still stable under the aging condition; the flame-retardant, fireproof, anti-reflection and self-cleaning effects can be achieved through one-time mold pressing, the process is simplified, the yield is increased, and the cost is saved.

Description

Technical Field

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

[0002] Traditional LED encapsulation materials often use epoxy resin or silicone, which are difficult to meet the UL-94 5VA flame retardant standard. In outdoor advertising screens, traffic lights, and other applications, high temperatures or short circuits can easily cause fires. Traditional flame retardant solutions involve adding flame retardant additives to the potting compound, which improves flame retardancy but causes the coating to whiten, affecting display quality. The surface reflectivity of LED modules is typically 5%–8%, resulting in significant light loss and a substantial reduction in screen visibility under strong light.

[0003] Furthermore, traditional antireflective materials often employ multilayer film structures with different refractive index gradients, such as SiO2-TiO2. While this structure can reduce reflectivity, it suffers from poor mechanical strength.

[0004] In addition, outdoor displays suffer from insufficient hydrophobicity in their surface coatings (water contact angle <90°). Dust adsorption forms a scattering layer that further reduces light transmittance, increasing maintenance costs. Therefore, LED display modules need to have self-cleaning properties on their surface. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a coating, an LED display module and a display screen with intrinsic flame retardant, anti-reflective and self-cleaning functions.

[0006] This invention provides a coating comprising:

[0007] 40-50 parts by weight of intrinsic flame-retardant self-cleaning resin;

[0008] 10-30 parts by weight of intrinsic flame-retardant hollow particles;

[0009] Curing agent and accelerator 30-40 parts by weight;

[0010] Toughening agent 1-10 parts by weight;

[0011] The intrinsic flame-retardant self-cleaning resin comprises the structure shown in formula (I):

[0012] Formula (I)

[0013] The intrinsic flame-retardant hollow particles comprise a hollow particle body and flame-retardant groups grafted onto the surface of the hollow particles; the schematic structure of the intrinsic flame-retardant hollow particles is shown in formula (II):

[0014] Equation (II)

[0015] In Equation (I) and Equation (II), n is an integer from 5 to 400; m is an integer from 5 to 20; and the circle in Equation (II) represents the hollow particle body.

[0016] Preferably, the intrinsic flame-retardant self-cleaning resin has a number-average molecular weight of 10,000 to 100,000.

[0017] Preferably, the intrinsic flame-retardant self-cleaning resin is prepared according to the following method:

[0018] S) Under a protective atmosphere and ice bath conditions, polydichlorophosphononitrile, 2-methyl-2,3-epoxy-1-propanol and the first catalyst are mixed, perfluoroalcohol is added by heating, and the reaction is carried out to obtain an intrinsic flame-retardant self-cleaning resin.

[0019] And / or, the intrinsically flame-retardant hollow particles are prepared according to the following method:

[0020] A1) After plasma treatment, hollow particle bodies are reacted with polydichlorophosphononitrile in a solvent by heating to obtain hollow particle bodies grafted with polydichlorophosphononitrile.

[0021] A2) Under a protective atmosphere and ice bath conditions, the hollow particle bulk of grafted polydichlorophosphononitrile, 2-methyl-2,3-epoxy-1-propanol and a second catalyst are mixed and then heated to obtain intrinsic flame-retardant hollow particles.

[0022] Preferably, the refractive index of the hollow particle body is less than 1.4;

[0023] The particle size of the hollow particle body is 1~100 μm;

[0024] The intrinsic flame-retardant hollow particles have a refractive index of less than 1.35.

[0025] Preferably, the hollow particle body is selected from inorganic hollow microspheres and / or organic hollow microspheres;

[0026] The inorganic hollow microspheres are selected from silica hollow microspheres;

[0027] 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.

[0028] Preferably, the curing agent is selected from one or more of amine curing agents, acid anhydride curing agents, and phenolic resin curing agents;

[0029] 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;

[0030] And / or, the mass ratio of the curing agent to the curing accelerator is (10~100):1;

[0031] And / or, the toughening agent is selected from one or more of rubber elastomer toughening agents, thermoplastic resin toughening agents, and glycidyl ether toughening agents.

[0032] Preferably, the curing agent is selected from acid anhydride curing agents; the acid anhydride curing agent is selected from one or more of methylnadic anhydride, phthalic anhydride, tetrahydrophthalic anhydride and methylhexahydrophthalic anhydride;

[0033] The curing accelerator is selected from imidazole derivative accelerators; the imidazole derivative accelerator is selected from one or more of 2-methylimidazolium, 2-ethylimidazolium, 2-propylimidazolium, 2-isopropylimidazolium, 2-phenylimidazolium, 1-isobutyl-2-methylimidazolium, 2-ethyl-4-methylimidazolium, 1,2-dimethylimidazolium and 1-benzylimidazolium;

[0034] The rubber elastomer toughening agent is selected from one or more of chloroprene rubber, nitrile rubber, polysulfide rubber, epoxy-terminated nitrile rubber, and carboxyl-terminated nitrile rubber.

[0035] The thermoplastic resin toughening agent is selected from one or more of polyethersulfone, polyimide and polyaryletherketone;

[0036] The glycidyl ether toughening agent is selected from one or more of diethylene glycol diglycidyl ether, glycidyl 12-14 alkyl ether, polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and butyl glycidyl ether.

[0037] Preferably, it further includes 0.1 to 1 part by weight of an auxiliary agent; the auxiliary agent includes a silane coupling agent.

[0038] 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 above-mentioned coating.

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

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

[0041] 1) Flame retardant and fire safety: Through the PN bond chemical structure of the polydichlorophosphononitrile modified resin, the synergistic flame retardant effect of the gas phase (releasing flame retardant free radicals) and the condensed phase (promoting char formation) is achieved simultaneously, enabling the LED module to pass the highest level 5VA certification of UL-94 (vertical burning test for 3 mm thick samples), meeting stringent fire safety requirements; the cross-linking reaction between the side chain epoxy functional groups and the resin matrix forms a three-dimensional network structure, which significantly improves the dimensional stability of the coating in high-temperature environments and can adapt to the heat accumulation conditions during long-term operation of the LED module;

[0042] 2) Improved display quality: After the hollow particles are modified with linear polydiphosphonium, the refractive index is reduced to below 1.35, forming a gradient refractive index structure with the resin matrix (refractive index 1.5), so that the surface reflectivity is ≤3%. The low reflectivity significantly reduces ambient light interference, allowing the display screen to maintain high contrast under strong light.

[0043] 3) Self-cleaning properties: The perfluorocarbon side chains form a nanoscale rough structure on the coating surface. Combined with the low surface energy of fluorine, the surface water contact angle is ≥105°, which significantly reduces the amount of dust adhering and allows rainwater to clean the surface. The covalent bond between the epoxy functional groups and the resin ensures that the perfluorocarbon structure remains stable under aging conditions.

[0044] 4) Simple to use: The coating of this invention can achieve flame retardant, fireproof, anti-reflective and self-cleaning effects with one molding process, which simplifies the process, improves the yield and saves costs. Attached Figure Description

[0045] Figure 1 This is a schematic diagram illustrating a specific manufacturing process of an LED display module provided by the present invention. Detailed Implementation

[0046] 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.

[0047] The present invention provides a coating comprising: 40-50 parts by weight of intrinsic flame-retardant self-cleaning resin; 10-30 parts by weight of intrinsic flame-retardant hollow particles; 30-40 parts by weight of curing agent and accelerator; and 1-10 parts by weight of toughening agent.

[0048] In one specific embodiment of the present invention, optionally, the content of the intrinsic flame-retardant self-cleaning resin in the coating is 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, or any two of the above values.

[0049] In this invention, the intrinsic flame-retardant self-cleaning resin comprises the structure shown in formula (I):

[0050] Formula (I)

[0051] Wherein, n is an integer from 5 to 400; optionally, n is an integer within the range of 5, 10, 20, 50, 80, 100, 110, 120, 150, 180, 200, 210, 220, 250, 280, 300, 310, 320, 350, 380, 390, 400, or any two of the above ranges; m is an integer from 5 to 20; optionally, m is an integer within the range of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any two of the above ranges. This intrinsically flame-retardant self-cleaning resin is based on the reaction product of polyphosphononitrile chloride. The phosphorus-nitrogen bonds in the molecular skeleton decompose at high temperatures, releasing non-flammable gases such as nitrogen and hydrogen phosphate dioxide, diluting the concentration of flammable gases and interrupting the combustion chain reaction. Meanwhile, the PO· free radicals generated by its decomposition can capture H· and HO· free radicals, inhibiting flame propagation. In addition, the phosphoric acid substances generated by its decomposition catalyze the dehydration of polymers to form a dense carbon layer, which isolates oxygen and heat, thus having a very good flame retardant and fireproof effect.

[0052] The intrinsic flame-retardant self-cleaning resin provided by this invention has a perfluorocarbon structure in its side chains, with fluorine atoms closely arranged to form a highly symmetrical structure, resulting in extremely low surface energy. This low surface energy characteristic makes it difficult for dust and stains to adhere, and they are easily washed away by rainwater. The intermolecular forces of the perfluoropolymer are weak (only van der Waals forces), and the molecular chains are arranged in a helical conformation. When external forces are applied, the molecular layers easily slide relative to each other, resulting in a low coefficient of friction (approximately 0.05~0.1), further enhancing the self-cleaning effect.

[0053] Furthermore, the other side chain of this intrinsic flame-retardant self-cleaning resin contains epoxy functional groups, which form a three-dimensional cross-linked structure under the action of the curing agent, thereby improving the resin's heat resistance.

[0054] In one specific embodiment of the present invention, the number-average molecular weight of the intrinsic flame-retardant self-cleaning resin is preferably 10,000 to 100,000; below this molecular weight, the coating will become brittle after curing, while above this molecular weight, the viscosity will increase sharply, affecting construction. Optionally, the number-average molecular weight of the intrinsic flame-retardant self-cleaning resin is 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, or any two of the above values.

[0055] In a specific embodiment of the present invention, the intrinsic flame-retardant self-cleaning resin is prepared by the following method: S) Under a protective atmosphere and ice bath conditions, polydichlorophosphononitrile, 2-methyl-2,3-epoxy-1-propanol and a first catalyst are mixed, and perfluoroalcohol is added at a higher temperature to react and obtain the intrinsic flame-retardant self-cleaning resin; the protective atmosphere can be any protective atmosphere known to those skilled in the art and is not particularly limited, but nitrogen is preferred in the present invention; the temperature of the ice bath is preferably 0℃~5℃; the molar ratio of polydichlorophosphononitrile to 2-methyl-2,3-epoxy-1-propanol can be selected according to the degree of polymerization of polydichlorophosphononitrile to ensure that it is in stoichiometric proportion. One side chain is converted into a side chain containing an epoxy functional group; the first catalyst is preferably an aqueous solution comprising an inorganic acid and an organic amine; the inorganic acid is preferably hydrochloric acid and / or sulfuric acid; the organic amine is preferably pyridine and / or triethylamine; the volume concentration of the inorganic acid in the first catalyst is preferably 1% to 5%, more preferably 2% to 4%, and even more preferably 3%; the volume concentration of the organic amine in the first catalyst is preferably 3% to 8%, more preferably 4% to 6%, and even more preferably 5%; the molar number of the first catalyst is preferably 0.05% to 0.2% of the molar number of polydichlorophosphononil (based on monomer units), more preferably 0.08% to 0.15%, and even more preferably 0.1%; the mixing time is preferably 10-60 min, more preferably 20-50 min, even more preferably 20-40 min, and most preferably 30 min; the heating is preferably to a temperature of 20℃-30℃, more preferably 25℃; the molar ratio of polydichlorophosphononitrile to perfluoroalcohol can be selected according to the degree of polymerization of polydichlorophosphononitrile, so that one side chain is converted into a side chain with a perfluorocarbon structure according to the stoichiometric ratio; the perfluoroalcohol is preferably added slowly to avoid local overheating; in this invention, the reaction after adding the perfluoroalcohol specifically includes reacting under ice bath conditions, then reacting at room temperature, then heating to a first target temperature, and then continuing the reaction at a second target temperature; the reaction time under ice bath conditions is preferably 10-50 min; optionally, the reaction time under ice bath conditions is 10 min, 20 min, 30 min, 40 min, 50 min or any two of the above values; the reaction time at room temperature is preferably 30-90 min; optionally, the reaction time at room temperature is 30 min, 40 min, 50 min, 60 min, 70 min or more. The target temperature is 30 min, 80 min, 90 min, or any two of the above values; the first target temperature is preferably 50℃~70℃, more preferably 55℃~65℃, and even more preferably 60℃; the reaction time at the first target temperature is preferably 30~90 min; specifically, the reaction time at the first target temperature is 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, or any two of the above values; the second target temperature is preferably 100℃~120℃, more preferably 105℃~115℃, and even more preferably 110℃; the reaction at the second target temperature is preferably a reflux reaction; in this invention, the reaction endpoint is preferably detected by TLC.

[0056] Furthermore, to avoid hydrolysis side reactions, the polydichlorophosphononitrile, 2-methyl-2,3-epoxy-1-propanol, and perfluoroalcohol are preferably pretreated with dehydration before being used to prepare the intrinsic flame-retardant self-cleaning resin. Specifically, the polydichlorophosphononitrile is preferably vacuum dried; the vacuum drying temperature is preferably 110℃~130℃, more preferably 120℃; the vacuum drying time is preferably 3~6 h, more preferably until the moisture content is less than or equal to 0.1%; the 2-methyl-2,3-epoxy-1-propanol and perfluoroalcohol are dehydrated using molecular sieves (4Å); the perfluoroalcohol can be any perfluoroalcohol well known to those skilled in the art, and there are no special limitations, including but not limited to 1H,1H-perfluoro-1-n-decanol, 1H,1H-perfluoro-1-dodecylol, 1H,1H,13H-perfluorotert-butyl-1-ol, 1H, One or more of 1H-perfluorooctadecane-1-ol, 1H,1H-perfluoro-1-tetradecane(ol)ol and 1H,1H-perfluoro-hexadecaneol.

[0057] Furthermore, after the heating reaction is completed, the solvent is preferably removed by vacuum distillation, followed by extraction with ethyl acetate, washing with water until neutral, drying, and collection by silica gel column chromatography to obtain the intrinsic flame-retardant self-cleaning resin; the pressure of the vacuum distillation is preferably less than or equal to 10 mmHg; the temperature of the vacuum distillation is preferably less than or equal to 50°C; the vacuum distillation is preferably carried out in batches to avoid the decomposition of perfluoroalcohols while removing excess solvent; the drying is preferably carried out using anhydrous magnesium sulfate; the drying time is preferably 2-6 h, more preferably 3-5 h, and even more preferably 4 h.

[0058] In one specific embodiment of the present invention, optionally, the content of the intrinsic flame-retardant hollow particles in the coating is 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 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.

[0059] In this invention, the intrinsically flame-retardant hollow particle comprises a hollow particle body and flame-retardant groups grafted onto the surface of the hollow particle; the schematic structure of the intrinsically flame-retardant hollow particle is shown in formula (II):

[0060] Equation (II)

[0061] Wherein, the circle represents the hollow particle body; the grafted groups on it are only schematic and do not indicate that only 4 flame-retardant groups are grafted on it; n is an integer from 5 to 400; optionally, n is 5, 10, 20, 50, 80, 100, 110, 120, 150, 180, 200, 210, 220, 250, 280, 300, 310, 320, 350, 380, 390, 400 or any two of the above numerical ranges.

[0062] In one specific embodiment of the present invention, the refractive index of the intrinsic flame-retardant hollow particles is preferably less than 1.35.

[0063] In a specific embodiment of the present invention, the intrinsic flame-retardant hollow particles are prepared by the following method: A1) After plasma treatment, the hollow particle body is reacted with polydichlorophosphononitrile in a solvent by heating to obtain a hollow particle body grafted with polydichlorophosphononitrile; A2) Under a protective atmosphere and ice bath conditions, the hollow particle body grafted with polydichlorophosphononitrile, 2-methyl-2,3-epoxy-1-propanol and a second catalyst are mixed and then reacted to obtain intrinsic flame-retardant hollow particles.

[0064] The intrinsically flame-retardant low-refractive-index hollow particles provided by this invention are modified with linear polydiphosphononitrile and epoxy functional groups through a two-step modification method. The PN bonds of polydiphosphononitrile endow it with flame-retardant properties, while the epoxy functional groups improve its dispersibility with intrinsically flame-retardant self-cleaning resin.

[0065] In a specific embodiment of the present invention, the refractive index of the hollow particle body is preferably less than 1.4, more preferably less than 1.37, and even more preferably less than 1.35; the hollow particle body is selected from inorganic hollow microspheres and / or organic hollow microspheres; the inorganic hollow microspheres include, but are not limited to, silica hollow microspheres; the organic hollow microspheres include, but are not limited to, one or more of polystyrene hollow microspheres, polyacrylate hollow microspheres, polylactic acid hollow microspheres, and thermoplastic elastomer hollow microspheres; considering cost and material refractive index, silica hollow microspheres are preferred; the particle size of the hollow particle body is preferably 1~100 μm; optionally, the particle size of the hollow particle body is 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or any two of the above values.

[0066] In this invention, the hollow particle body is first subjected to plasma treatment. Plasma treatment introduces polar groups on the surface of the hollow particle body, increasing the surface free energy to facilitate the subsequent grafting reaction. The gas used for plasma treatment is preferably argon. The power of plasma treatment is preferably 50~500 W. Optionally, the power of plasma treatment is 50 W, 100 W, 150 W, 200 W, 250 W, 300 W, 350 W, 400 W, 450 W, 500 W, or any two of the above values. The time of plasma treatment is preferably 5~15 min. Optionally, the time of plasma treatment is 5 min, 8 min, 10 min, 12 min, 15 min, or any two of the above values.

[0067] The hollow particle bulk material after plasma treatment is reacted with polydichlorophosphononitrile in a solvent by heating to obtain hollow particle bulk material grafted with polydichlorophosphononitrile; specifically, the hollow particle bulk material after plasma treatment is dispersed in a solvent to obtain a suspension, and then mixed with a solution containing polydichlorophosphononitrile and heated to obtain hollow particle bulk material grafted with polydichlorophosphononitrile; the solvent can be any organic solvent well known to those skilled in the art, and there are no special limitations, but N,N-dimethylformamide (DMF) is preferred in this invention; the hollow particle bulk material after plasma treatment is preferably dispersed in the solvent by ultrasonication; the ultrasonication time is preferably 0.5~2 h, more preferably 0.8~1.5 h, and even more preferably 1 h. h; the mass concentration of the hollow particle bulk after plasma treatment in the suspension is preferably 5%~30%, more preferably 5%~25%, and even more preferably 10%~20%; the heating reaction is preferably carried out in the presence of a catalyst; the catalyst is preferably an organic amine, more preferably including but not limited to pyridine and / or triethylamine; the heating reaction is preferably carried out in a protective atmosphere; the protective atmosphere is any protective atmosphere known to those skilled in the art and is not particularly limited, but nitrogen is preferred in this invention; the temperature of the heating reaction is preferably 40℃~70℃, more preferably 50℃~60℃; the time of the heating reaction is preferably 6~10 h, more preferably 7~9 h, and even more preferably 8 h. h; After the heating reaction is completed, the hollow particles grafted with polydichlorophosphononitrile are preferably obtained after solid-liquid separation, washing, and drying; the solid-liquid separation method is preferably centrifugation; the washing is preferably carried out with N,N-dimethylformamide (DMF) to remove unreacted substances; the drying is preferably freeze-drying to avoid solvent residue; the freeze-drying temperature is preferably -30℃ to -80℃, more preferably -40℃ to -60℃, and even more preferably -50℃; the freeze-drying time is preferably 15 to 30 h, more preferably 20 to 28 h, and even more preferably 24 h.

[0068] Under a protective atmosphere and ice bath conditions, hollow particles grafted with polydichlorophosphononitrile, 2-methyl-2,3-epoxy-1-propanol, and a second catalyst are mixed. The protective atmosphere can be any atmosphere well-known to those skilled in the art and is not particularly limited; nitrogen is preferred in this invention. The ice bath temperature is preferably 0°C to 5°C. The mass ratio of the hollow particles grafted with polydichlorophosphononitrile to 2-methyl-2,3-epoxy-1-propanol is preferably (1~10):1. Optionally, the mass ratio of the hollow particles grafted with polydichlorophosphononitrile to the epoxy compound shown in formula (IV) is 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1. 1 or any two of the above ratios; the second catalyst is preferably an aqueous solution comprising an inorganic acid and an organic amine; the inorganic acid is preferably hydrochloric acid and / or sulfuric acid; the organic amine is preferably pyridine and / or triethylamine; the volume concentration of the inorganic acid in the second catalyst is preferably 1% to 5%, more preferably 2% to 4%, and even more preferably 3%; the volume concentration of the organic amine in the second catalyst is preferably 3% to 8%, more preferably 4% to 6%, and even more preferably 5%; the molar number of the second catalyst is preferably 0.05% to 0.2% of the molar number of polydichlorophosphononium (based on monomer units), more preferably 0.08% to 0.15%, and even more preferably 0.1%; the mixing time is preferably 10 to 60 min, more preferably 20 to 50 min, even more preferably 20 to 40 min, and most preferably 30 min.

[0069] After mixing, the reaction proceeds; specifically, the reaction includes reacting under ice bath conditions, then raising the temperature to a first preset temperature, then heating to a second preset temperature, and finally raising the temperature to a third preset temperature to continue the reaction; the reaction time under ice bath conditions is preferably 10-50 min; optionally, the reaction time under ice bath conditions is 10 min, 20 min, 30 min, 40 min, 50 min, or any two of the above values; the first preset temperature is preferably 20℃-30℃, more preferably 25℃; the reaction time at the first preset temperature is preferably 30-90 min; optionally, the reaction time at the first preset temperature is 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, or any two of the above values; the second preset temperature is preferably 50℃-70℃, more preferably 55℃-65℃, and even more preferably 60℃; the reaction time at the second preset temperature is preferably 30-90 min; specifically, the reaction time at the second preset temperature is 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, or any two of the above values. The third preset temperature is either min or any two of the above values; the third preset temperature is preferably 100℃~120℃, more preferably 105℃~115℃, and even more preferably 110℃; specifically, the reaction at the third preset temperature is preferably a reflux reaction; in this invention, the reaction endpoint is preferably detected by TLC.

[0070] Furthermore, after the heating reaction is completed, the solvent is preferably removed by vacuum distillation, followed by centrifugation, washing, and drying to obtain intrinsically flame-retardant hollow particles; the pressure of vacuum distillation is preferably less than or equal to 10 mmHg; the temperature of vacuum distillation is preferably less than or equal to 50°C; the vacuum distillation is preferably carried out in batches; the washing is preferably carried out using N,N-dimethylformamide (DMF) to remove unreacted substances; the drying is preferably freeze-drying to avoid solvent residue; the freeze-drying temperature is preferably -30°C to -80°C, more preferably -40°C to -60°C, and even more preferably -50°C; the freeze-drying time is preferably 15 to 30 h, more preferably 20 to 28 h, and even more preferably 24 h.

[0071] In a specific embodiment of the present invention, the content of the curing agent and the accelerator in the coating is preferably 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, or any two of the above values.

[0072] 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, 15:1, 19:1, 20:1, 25:1, 29:1, 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.

[0073] 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, menthol 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, one or more of methylnadic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0074] In a specific embodiment of the present invention, the curing accelerator preferably 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; 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, 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-isopropylimidazole, etc. One or more of 2-phenylimidazole, 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, and 1-benzylimidazole; 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 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.

[0075] Because each repeating unit of the intrinsic flame-retardant self-cleaning resin has a reactive epoxy functional group, its cross-linked structure is tightly packed during the curing agent reaction. Although it has high mechanical strength, it has poor toughness, and is prone to cracking, especially under thermal shock. Therefore, a toughening agent is needed to toughen it. In a specific embodiment of the present invention, the content of the toughening agent in the coating is preferably 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, or any two of the above values.

[0076] In a specific embodiment of the present invention, the toughening agent is preferably one or more of rubber elastomer toughening agents, thermoplastic resin toughening agents, and glycidyl ether toughening agents; the rubber elastomer toughening agent preferably includes, but is not limited to, one or more of chloroprene rubber, nitrile rubber, polysulfide rubber, epoxy-terminated nitrile rubber, and carboxyl-terminated nitrile rubber; the thermoplastic resin toughening agent preferably includes, but is not limited to, one or more of polyethersulfone, polyimide, and polyaryletherketone; the glycidyl ether toughening agent preferably includes, but is not limited to, one or more of diethylene glycol diglycidyl ether, glycidyl 12-14 alkyl ether, polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and butyl glycidyl ether.

[0077] In one specific embodiment of the present invention, the coating preferably further includes 0.1 to 1 part by weight of an additive; optionally, the content of the additive in the coating is 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight, 0.5 part by weight, 0.6 part by weight, 0.7 part by weight, 0.8 part by weight, 0.9 part by weight, 1 part by weight, or any two of the above values.

[0078] Additives can improve certain properties of coatings, such as improving leveling and uniformity, and enhancing adhesion. In this invention, the additives preferably include silane coupling agents. The silane coupling agents are 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 agents include, but are not limited to, vinyltrimethoxysilane and / or vinyltriethoxysilane. The epoxy silane coupling agents include, but are not limited to, 2-(3,4-epoxycyclohexyl)ethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, and 3-glycidyl etheroxysilane. The aminosilane coupling agent includes, but is not limited to, one or more of aminopropyltrimethoxysilane, 3-glycidyl etheroxypropylmethyldiethoxysilane, and 3-glycidyl etheroxypropyltriethoxysilane; the ureosilane coupling agent includes, but is not limited to, one or more of aminopropyltrimethoxysilane, 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, one or more of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropylmethyldiethoxysilane.

[0079] In one specific embodiment of the present invention, the coating comprises:

[0080] 40 parts by weight of intrinsic flame-retardant self-cleaning resin;

[0081] 30 parts by weight of intrinsic flame-retardant hollow particles;

[0082] 20 parts by weight of curing agent and accelerator;

[0083] 9 parts by weight of toughening agent;

[0084] 1 part by weight of auxiliary agent;

[0085] Or, including:

[0086] 50 parts by weight of intrinsic flame-retardant self-cleaning resin;

[0087] 10 parts by weight of intrinsic flame-retardant hollow particles;

[0088] 30 parts by weight of curing agent and accelerator;

[0089] 9 parts by weight of toughening agent;

[0090] Additive 1 part by weight.

[0091] According to the present invention, the coating can be prepared by methods well known to those skilled in the art, without any special limitations. Specifically, it can be prepared by the following steps: the intrinsic flame-retardant self-cleaning resin, intrinsic flame-retardant hollow particles, curing agent and accelerator, toughening agent and additives are degassed by vacuum stirring to obtain the coating; the stirring speed is preferably 1000~2000 rpm; the stirring time is 10~20 min.

[0092] The intrinsically flame-retardant self-cleaning resin used in this invention is a modified resin based on polydichlorophosphononitrile. Polyphosphononitrile achieves flame retardancy through gas-phase and condensed-phase flame-retardant mechanisms, while the perfluorocarbon structure of the side chains and the reactive epoxy functional groups achieve self-cleaning and improved heat resistance. Intrinsically flame-retardant low-refractive-index hollow particles are modified with a two-step modification method to enhance the linear polydiphosphononitrile and epoxy functional groups. The PN bonds of the polydiphosphononitrile impart flame-retardant properties, while the epoxy functional groups improve its dispersibility and reactivity with the intrinsically flame-retardant self-cleaning resin. Its low refractive index reduces the overall refractive index of the coating, resulting in reduced surface reflectivity after treatment of LED modules. Encapsulating LED modules with intrinsically flame-retardant self-cleaning resin, intrinsically flame-retardant low-refractive-index hollow particles, and other components yields the following benefits: flame-retardant and fire-resistant properties, passing the 5VA standard in the UL-94 flame-retardant test; surface reflectivity ≤3%, improving display quality, making images brighter and darker details clearer; surface water contact angle ≥105°, making it difficult for dust and stains to adhere, and they easily detach when washed away by rain, exhibiting self-cleaning characteristics.

[0093] 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 coating.

[0094] 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.

[0095] In this invention, a plurality of LED chips are disposed on the surface of the substrate, and more preferably, a plurality of driver ICs are also disposed thereon.

[0096] 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.

[0097] 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 a coating onto the surface of the semi-finished LED display module, curing it to form an encapsulating adhesive layer, thereby obtaining the LED display module.

[0098] 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.

[0099] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available or homemade. The coating is the same as described above and will not be repeated here.

[0100] In one specific embodiment of the present invention, the LED display module semi-finished product is preferably first subjected to plasma cleaning before the coating is transferred to its surface.

[0101] In a specific embodiment of the present invention, step S2) specifically involves: fixing the LED display module semi-finished product onto a preset molding fixture after plasma cleaning; applying the above-mentioned coating onto the release film and pressing it; then removing it and curing it to form an encapsulating adhesive layer; the pressing temperature is preferably 100℃~150℃, more preferably 120℃~130℃; the pressing time is preferably 5~15 min; since the pressing is carried out under heating conditions, the coating is also pre-cured during the pressing process; the pressing thickness is preferably 100~500 μm; the curing temperature is 100℃~150℃, more preferably 120℃~130℃; the curing time is preferably 2~5 h.

[0102] The present invention also provides a display screen, including the LED display module described above.

[0103] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a coating, an LED display module, and a display screen provided by the present invention.

[0104] All reagents used in the following examples are commercially available; the aqueous catalyst solution used in the examples includes: 5% pyridine by volume, 3% concentrated sulfuric acid by volume, and the remainder is water.

[0105] Example 1

[0106] 1.1 The ingredient list is shown in Table 1.

[0107] Table 1. Ingredients list for Example 1

[0108]

[0109] 1.2 Preparation of Intrinsic Flame-Retardant Self-Cleaning Resin

[0110] 1) Preparation of polyphosphononitrile chloride

[0111] PCl5 was added to the solvent and stirred until dissolved. Then, ZnCl2 catalyst was added. NH4Cl (PCl5: ZnCl2:NH4Cl = 1:0.05:1.3 molar ratio) (which needs to be pre-ground into a fine powder) was slowly added, and the reaction temperature was controlled at 125℃. Nitrogen gas was continuously purged (flow rate 60 mL / min) to remove the byproduct HCl. The reaction was kept at this temperature for 2.0 h until no HCl gas was released. After cooling the reaction solution, it was filtered to remove insoluble matter. The solvent (chlorobenzene boiling point 131℃) was recovered by vacuum distillation of the filtrate. The crude product was sublimated at 60℃ / 13 mmHg, and white crystals were collected. The crude product was dissolved in chlorobenzene and cooled to 0℃ to crystallize, yielding hexachlorocyclotriphosphazene.

[0112] Hexachlorocyclotriphosphazene was ground into a fine powder and placed in a high-temperature resistant reactor. It was heated at 200°C for 5 h, cooled, pulverized, and washed with an organic solvent (such as benzene) to remove unreacted monomers, thus obtaining polydichlorophosphazene.

[0113] 2) Preparation of intrinsic flame-retardant self-cleaning resin

[0114] Raw material pretreatment: Polydichlorophosphononitrile: vacuum dried at 120℃ for 4 hours (moisture content ≤0.1%) to avoid hydrolysis side reactions; 2-methyl-2,3-epoxy-1-propanol and perfluoroalcohol: dehydrated by molecular sieve (4Å) to achieve solvent purity ≥99.5%.

[0115] Reaction Procedure: A three-necked flask was placed in an ice bath and purged with nitrogen for 30 minutes to remove oxygen and moisture. Polydichlorophosphononitrile (0.1 mol, based on monomer units) and 2-methyl-2,3-epoxy-1-propanol (0.5 mol) were added in the ice bath (3°C). 0.1 mmol of an aqueous catalyst solution was slowly added dropwise, and the mixture was stirred for 30 minutes. The temperature was raised to 25°C, and 1H,1H-perfluoro-1-n-decyl alcohol (0.5 mol) was slowly added, avoiding localized overheating. After the addition of 1H,1H-perfluoro-1-n-decyl alcohol was complete, the reaction was initiated. The reaction temperature was successively controlled at 3°C ​​(30 minutes), 25°C (1 hour), 60°C (1 hour), and 110°C (refluxed to the TLC endpoint).

[0116] Vacuum distillation: Pressure ≤10 mmHg, temperature ≤50℃, remove excess solvent in batches (to avoid decomposition of perfluoroalcohols);

[0117] Extraction and washing: Extracted three times with ethyl acetate and washed with water until neutral (pH=7); dried with anhydrous magnesium sulfate for 4 hours and collected by silica gel column chromatography.

[0118] 1.3 Preparation of Intrinsic Flame-Retardant Hollow Particles

[0119] 1) Hollow particle bulk surface grafted with linear polydichlorophosphononitrile

[0120] 100 g of hollow silica particles with an average particle size of 40 μm were subjected to plasma treatment (the gas used for plasma treatment was argon; the power of the plasma treatment was 100 W; the plasma treatment time was 10 min), followed by washing three times with anhydrous ethanol. The particles were then dispersed in 900 g of DMF solvent and ultrasonically dispersed (power 100 W) for 1 hour to form a homogeneous suspension. 10 g of linear polydichlorophosphononitrile was dispersed in 500 mL of DMF solvent and mixed with the activated hollow particles. 0.05 g of triethylamine catalyst was added, and the mixture was reacted at 50 °C for 8 hours under nitrogen protection. The mixture was centrifuged, and washed three times with DMF to remove unreacted substances. The product was freeze-dried (-50 °C, 24 hours) for storage to avoid solvent residue.

[0121] 2) Preparation of flame-retardant hollow particles

[0122] Reaction Procedure: A three-necked flask was placed in an ice bath and purged with nitrogen for 30 minutes to remove oxygen and moisture. 100 g of grafted linear polydichlorophosphononitrile hollow particles and 20 g of 2-methyl-2,3-epoxy-1-propanol were added to the ice bath (2°C). 0.1 mmol of an aqueous catalyst solution was slowly added dropwise, and the mixture was stirred for 30 minutes before proceeding with the reaction. The reaction temperature was successively controlled at 2°C (30 minutes), 25°C (1 hour), 60°C (1 hour), and 110°C (refluxed to the TLC endpoint).

[0123] Vacuum distillation: pressure ≤10 mmHg, temperature ≤50℃, excess solvent removed by batch distillation; centrifugation, washing three times with DMF to remove unreacted substances. The product is freeze-dried (-50℃, 24 hours) for storage to avoid solvent residue.

[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 material stand for 10 minutes to obtain the coating.

[0125] 1.4 After plasma cleaning, the LED light board with attached chips and driver ICs is fixed on a preset molding fixture. The coating is extruded onto the release film and pressed together. 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 module.

[0126] Performance testing

[0127] ① Flame retardancy test: Cut the cured LED module into strips 125 mm long and 13 mm wide, and conduct flame retardancy test according to UL 945V standard to obtain the flame retardancy afterflame and afterburn test results. The results are shown in Table 2.

[0128] ② Reflectivity test: The surface reflectivity of the molded module was tested using a reflectivity tester, and the results are shown in Table 2.

[0129] ③ Surface water contact angle test: The surface water contact angle of the molded module was tested using a water contact angle tester, and the results are shown in Table 2.

[0130] ④ Module reliability test: The molded and cured module was lit up and placed in a device with a temperature of 85℃ and a humidity of 85% for a total of 168 hours. The display effect was observed to see if there were any abnormalities, and whether there were any appearance abnormalities such as cracks, bubbles, or wrinkles on the lamp surface. The results are shown in Table 2.

[0131] The molded and cured module was lit and subjected to thermal shock test at a temperature of -40℃ to 80℃. The cold shock time was 30 minutes and the hot shock time was 30 minutes. This constituted one cycle. A total of 500 cycles were performed. The display effect was observed for any abnormalities, and the lamp surface was checked for any cracks, bubbles, or other appearance abnormalities. The results are shown in Table 2.

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

[0133]

[0134] Note: The numbers in Table 2 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 Preparation of Intrinsic Flame-Retardant Self-Cleaning Resin

[0140] 1) Preparation of polyphosphononitrile chloride

[0141] PCl5 was added to the solvent and stirred until dissolved. Then, ZnCl2 catalyst was added. NH4Cl (PCl5: ZnCl2:NH4Cl = 1:0.05:1.3 molar ratio) (which needs to be pre-ground into a fine powder) was slowly added, and the reaction temperature was controlled at 125℃. Nitrogen gas was continuously purged (flow rate 60 mL / min) to remove the byproduct HCl. The reaction was kept at this temperature for 2.0 h until no HCl gas was released. After cooling the reaction solution, it was filtered to remove insoluble matter. The solvent (chlorobenzene boiling point 131℃) was recovered by vacuum distillation of the filtrate. The crude product was sublimated at 60℃ / 13 mmHg, and white crystals were collected. The crude product was dissolved in chlorobenzene and cooled to 0℃ to crystallize, yielding hexachlorocyclotriphosphazene.

[0142] Hexachlorocyclotriphosphazene was ground into a fine powder and placed in a high-temperature resistant reactor. It was heated at 200°C for 5 h, cooled, pulverized, and washed with an organic solvent (such as benzene) to remove unreacted monomers, thus obtaining polychlorinated phosphazene.

[0143] 2) Preparation of intrinsic flame-retardant self-cleaning resin

[0144] Raw material pretreatment: Polyphosphononitrile chloride: vacuum dried at 120℃ for 4 hours (moisture content ≤0.1%) to avoid hydrolysis side reactions; 2-methyl-2,3-epoxy-1-propanol and perfluoroalcohol: dehydrated by molecular sieve (4Å) to achieve solvent purity ≥99.5%.

[0145] Reaction Procedure: A three-necked flask was placed in an ice bath and purged with nitrogen for 30 minutes to remove oxygen and moisture. Polyphosphononitrile chloride (0.1 mol, based on monomer units) and 2-methyl-2,3-epoxy-1-propanol (0.5 mol) were added under ice bath (3°C). 0.1 mmol of an aqueous catalyst solution was slowly added dropwise, and the mixture was stirred for 30 minutes. The temperature was raised to 25°C, and 1H,1H-perfluorooctadecane-1-ol (0.5 mol) was slowly added, avoiding localized overheating. After the addition of 1H,1H-perfluorooctadecane-1-ol was complete, the reaction was initiated. The reaction temperature was successively controlled at 3°C ​​(30 minutes), 25°C (1 hour), 60°C (1 hour), and 110°C (refluxed to the TLC endpoint).

[0146] Vacuum distillation: Pressure ≤10 mmHg, temperature ≤50℃, remove excess solvent in batches (to avoid decomposition of perfluoroalcohols);

[0147] Extraction and washing: Extracted three times with ethyl acetate and washed with water until neutral (pH=7); dried with anhydrous magnesium sulfate for 4 hours and collected by silica gel column chromatography.

[0148] 2.3 Preparation of Intrinsic Flame-Retardant Hollow Particles

[0149] 1) Hollow particle bulk surface grafted with linear polydichlorophosphononitrile

[0150] 100 g of hollow silica particles with an average particle size of 50 μm were subjected to plasma treatment (the gas used for plasma treatment was argon; the power of the plasma treatment was 100 W; the plasma treatment time was 10 min), washed three times with anhydrous ethanol, dispersed in 900 g of DMF solvent, and ultrasonically dispersed for 1 hour to form a homogeneous suspension. 10 g of linear polydichlorophosphononitrile was dispersed in 500 mL of DMF solvent, mixed with the activated hollow particles, and 0.05 g of triethylamine catalyst was added. The mixture was reacted at 50 °C for 8 hours under nitrogen protection. After centrifugation, the mixture was washed three times with DMF to remove unreacted substances. The product was freeze-dried (-50 °C, 24 hours) for storage to avoid solvent residue.

[0151] 2) Preparation of flame-retardant hollow particles

[0152] Reaction Procedure: A three-necked flask was placed in an ice bath and purged with nitrogen for 30 minutes to remove oxygen and moisture. 100 g of grafted linear polydichlorophosphononitrile hollow particles and 20 g of 2-methyl-2,3-epoxy-1-propanol were added to the ice bath (2°C). A 0.1 mmol aqueous catalyst solution was slowly added dropwise, and the mixture was stirred for 30 minutes before proceeding with the reaction. The reaction temperature was successively controlled at 2°C (30 minutes), 25°C (1 hour), 60°C (1 hour), and 110°C (refluxed to the TLC endpoint).

[0153] Vacuum distillation: pressure ≤10 mmHg, temperature ≤50℃, excess solvent removed by batch distillation; centrifugation, washing three times with DMF to remove unreacted substances. The product is freeze-dried (-50℃, 24 hours) for storage to avoid solvent residue.

[0154] 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 1000 rpm for 10 minutes. Let the dispersed material stand for 10 minutes to obtain the coating.

[0155] 2.4 After plasma cleaning, the LED board with the chip and driver IC is fixed on the preset molding fixture. The coating is extruded onto the release film and pressed. 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 3h to obtain the LED module.

[0156] Performance testing

[0157] ① Flame retardancy test: Cut the cured LED module into strips 125 mm long and 13 mm wide, and conduct flame retardancy test according to UL 945V standard to obtain the flame retardancy afterflame and afterburn test results. The results are shown in Table 4.

[0158] ② Reflectivity test: The surface reflectivity of the molded module was tested using a reflectivity tester, and the results are shown in Table 4.

[0159] ③ Surface water contact angle test: The surface water contact angle of the molded module was tested using a water contact angle tester, and the results are shown in Table 4.

[0160] ④ Module reliability test: The molded and cured module was lit and placed in a device with a temperature of 85℃ and a humidity of 85% for a total of 168 hours. The display effect was observed to see if there were any abnormalities, and whether there were any appearance abnormalities such as cracks, bubbles, or wrinkles on the lamp surface. The results are shown in Table 4.

[0161] The molded and cured module was lit and subjected to a thermal shock test at a temperature of -40℃ to 80℃. The cold shock time was 30 minutes and the hot shock time was 30 minutes. This constituted one cycle, and a total of 500 cycles were performed. The display effect was observed for any abnormalities, and the lamp surface was checked for any cracks, bubbles, or other appearance abnormalities. The results are shown in Table 4.

[0162] Table 4 Performance test results of the LED module prepared in Example 2

[0163]

[0164] 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.

[0165] Comparative Example 1

[0166] The ingredients and preparation method are the same as in Example 1, except that 40 parts by weight of intrinsic flame-retardant self-cleaning resin are replaced with 40 parts by weight of epoxy bisphenol A resin E-12 resin and polyphosphonic nitrile flame retardant. The ratio of epoxy bisphenol A resin E-12 resin to polyphosphonic nitrile flame retardant is the same as the ratio of 2-methyl-2,3-epoxy-1-propanol to polydichlorophosphonic nitrile in Example 1.

[0167] The performance was tested according to the test method in Example 1, and the results are shown in Table 5.

[0168] Table 5 Performance test results of the LED module prepared in Comparative Example 1

[0169]

[0170] 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.

[0171] Comparative Example 2

[0172] The ingredients and preparation method are the same as in Example 1, except that the intrinsic flame-retardant self-cleaning resin is used in the same amount of ungrafted perfluorool. That is, after adding the catalyst and stirring for 30 min, there is no need to add perfluorool. The reaction temperature is controlled successively at 3℃ (30 min), 25℃ (1 hour), 60℃ (1 hour) and 110℃ (reflux to TLC monitoring endpoint). The subsequent steps are the same as in Example 1.

[0173] The performance was tested according to the test method in Example 1, and the results are shown in Table 6.

[0174] Table 6 Performance test results of the LED module prepared in Comparative Example 2

[0175]

[0176] 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.

[0177] Comparative Example 3

[0178] The ingredients and preparation method are the same as in Example 1, except that the intrinsic flame-retardant low refractive index hollow particles are replaced with silica hollow microspheres with a particle size of 40 μm (i.e., ungrafted hollow microspheres).

[0179] The performance was tested according to the test method in Example 1, and the results are shown in Table 7.

[0180] Table 7 Performance test results of the LED module prepared in Comparative Example 3

[0181]

[0182] 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.

[0183] Comparative Example 4

[0184] The ingredients and preparation method are the same as in Example 1, except that the intrinsic flame-retardant low-refractive-index hollow particles are the surface-grafted linear polydichlorophosphononitrile hollow particles prepared in Example 1.

[0185] The performance was tested according to the test method in Example 1, and the results are shown in Table 8.

[0186] Table 8 Performance test results of the LED module prepared in Comparative Example 4

[0187]

[0188] 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.

[0189] As shown in Tables 2, 4, and 5-8, the LED display module prepared by this invention has flame-retardant and fire-resistant effects. When subjected to the UL-94 standard flame retardant test, it can pass the 5VA standard; the surface reflectivity is ≤3%, which improves the display effect, making the displayed image brighter and the details in the darker areas clearer; the surface water contact angle is ≥105°, making it difficult for dust, stains, etc. to adhere, and they are easily washed off by rainwater, thus having self-cleaning characteristics.

[0190] 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. A coating, characterized in that, include: 40-50 parts by weight of intrinsic flame-retardant self-cleaning resin; 10-30 parts by weight of intrinsic flame-retardant hollow particles; 30-40 parts by weight of curing agent and accelerator; Toughening agent 1-10 parts by weight; The intrinsic flame-retardant self-cleaning resin comprises the structure shown in formula (I): Equation (I) The intrinsic flame-retardant hollow particles comprise a hollow particle body and flame-retardant groups grafted onto the surface of the hollow particles; the schematic structure of the intrinsic flame-retardant hollow particles is shown in formula (II): Equation (II) In Equation (I) and Equation (II), n is an integer from 5 to 400; m is an integer from 5 to 20; and the circle in Equation (II) represents the hollow particle body.

2. The coating according to claim 1, characterized in that, The intrinsic flame-retardant self-cleaning resin has a number-average molecular weight of 10,000 to 100,000.

3. The coating according to claim 2, characterized in that, The intrinsic flame-retardant self-cleaning resin is prepared according to the following method: S) Under a protective atmosphere and ice bath conditions, polydichlorophosphononitrile, 2-methyl-2,3-epoxy-1-propanol and the first catalyst were mixed, and perfluoroalcohol was added at a higher temperature to react and obtain an intrinsic flame-retardant self-cleaning resin. And / or, the intrinsically flame-retardant hollow particles are prepared according to the following method: A1) After plasma treatment, hollow particle bodies are reacted with polydichlorophosphononitrile in a solvent by heating to obtain hollow particle bodies grafted with polydichlorophosphononitrile. A2) Under a protective atmosphere and ice bath conditions, the hollow particle bulk of grafted polydichlorophosphononitrile, 2-methyl-2,3-epoxy-1-propanol and a second catalyst are mixed and reacted to obtain intrinsic flame-retardant hollow particles.

4. The coating according to claim 1, characterized in that, The refractive index of the hollow particle body is less than 1.4; The particle size of the hollow particle body is 1~100 μm; The intrinsic flame-retardant hollow particles have a refractive index of less than 1.

35.

5. The coating according to claim 4, characterized in that, The hollow particle body is 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.

6. The coating according to claim 1, characterized in that, The curing agent is selected from one or more of amine curing agents, acid anhydride curing agents, and phenolic resin curing agents; 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; And / or, the mass ratio of the curing agent to the curing accelerator is (10~100):1; And / or, the toughening agent is selected from one or more of rubber elastomer toughening agents, thermoplastic resin toughening agents, and glycidyl ether toughening agents.

7. The coating according to claim 6, characterized in that, The curing agent is selected from acid anhydride curing agents; the acid anhydride curing agent is selected from one or more of methylnadic anhydride, phthalic anhydride, tetrahydrophthalic anhydride and methylhexahydrophthalic anhydride; The curing accelerator is selected from imidazole derivative accelerators; the imidazole derivative accelerator is selected from one or more of 2-methylimidazolium, 2-ethylimidazolium, 2-propylimidazolium, 2-isopropylimidazolium, 2-phenylimidazolium, 1-isobutyl-2-methylimidazolium, 2-ethyl-4-methylimidazolium, 1,2-dimethylimidazolium and 1-benzylimidazolium; The rubber elastomer toughening agent is selected from one or more of chloroprene rubber, nitrile rubber, polysulfide rubber, epoxy-terminated nitrile rubber, and carboxyl-terminated nitrile rubber. The thermoplastic resin toughening agent is selected from one or more of polyethersulfone, polyimide and polyaryletherketone; The glycidyl ether toughening agent is selected from one or more of diethylene glycol diglycidyl ether, glycidyl 12-14 alkyl ether, polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and butyl glycidyl ether.

8. The coating according to claim 1, characterized in that, It also includes 0.1 to 1 part by weight of additives; said additives include silane coupling agents.

9. An LED display module, characterized in that, It includes 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 coating described in any one of claims 1 to 8.

10. A display screen, characterized in that, Includes the LED display module as described in claim 9.

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