Composition for packaging, packaging material, packaging method, application of packaging material in LED display module and repair method of packaging material in LED display module

Abstract

The invention provides a composition for packaging, a packaging material, a packaging method, an LED display module and a repair method, the composition for packaging comprises ethylene-vinyl acetate copolymer resin, an organic solvent, a filler and an auxiliary agent, and the weight percentage of a vinyl acetate chain segment in the ethylene-vinyl acetate copolymer resin is 35%-45%. The components of the composition for packaging are good in dispersity, the composition for packaging has the advantage of being short in drying time, and when the composition is applied to an LED lamp panel, high light emitting uniformity and high blackness value can be achieved, the good light emitting effect is achieved, and repairing is easy before curing.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a packaging composition, a packaging material, a packaging method, and an LED display module and a rework method thereof. Background Art

[0002] With the continuous development of display technology, MiniLED technology is gradually becoming a research hotspot. Among them, MiniLED direct display, as the outpost of the next generation of new display technology MicroLED, is more technically difficult. As an upgraded alternative product for small-pitch display screens, MiniLED can improve reliability and pixel density. The current demand for display screen display capabilities in the commercial display, professional display, and general consumer markets is increasing. MiniLED is a high-value-added product with a smaller size, more closely arranged LED lamp beads, and a higher PPI. It is also more difficult to upgrade production, packaging, testing, and maintenance technology.

[0003] At present, conventional encapsulation films are generally used for encapsulation of LED display modules. During the encapsulation process, conventional encapsulation films are directly laminated. In order to enable the films to fill the gaps between LED lamp beads, high-temperature hot pressing is generally required to melt the films so that they can flow into the gaps to achieve the encapsulation effect. The encapsulation conditions are high. In addition, the adhesion of conventional encapsulation films cannot meet the encapsulation requirements of special LED lamp bead arrangements, and it is difficult to achieve a tight encapsulation effect. Summary of the invention

[0004] The invention provides a packaging composition, a packaging material, a packaging method, an LED display module and a rework method thereof, so as to solve the existing problems.

[0005] According to a first aspect of the present invention, the present invention provides a composition for encapsulation, comprising an ethylene-vinyl acetate copolymer resin, an organic solvent, a filler and an additive, wherein the weight percentage of the vinyl acetate segment in the ethylene-vinyl acetate copolymer resin is 35%-45%.

[0006] Furthermore, the solubility parameter SP of the ethylene-vinyl acetate copolymer resin is 1 The solubility parameter SP of the organic solvent 2 The absolute value of the difference |ΔSP|=|SP 1 -SP 2 | is 0-2.

[0007] Furthermore, the ethylene-vinyl acetate copolymer resin also satisfies at least one of the following characteristics (1)-(3): (1) The ethylene-vinyl acetate copolymer resin is a transparent ethylene-vinyl acetate copolymer resin, and the resin transmittance is above 90%; (2) The weight of the ethylene-vinyl acetate copolymer resin is 12%-40% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent; (3) Solubility parameter SP of the ethylene-vinyl acetate copolymer resin 1 It is 9.0-9.5.

[0008] Furthermore, the solubility parameter SP of the organic solvent is 2 is 8.0-9.0; preferably, the organic solvent is selected from one or more of xylene, ethyl acetate, and propylene glycol methyl ether acetate.

[0009] Furthermore, the auxiliary agent includes a cross-linking agent, and the amount of the cross-linking agent is 1%-5% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent.

[0010] Furthermore, the auxiliary agent also includes diffusion powder, which includes at least one of inorganic diffusion powder and organic diffusion powder, and the inorganic diffusion powder includes one or more of ethylene bisstearamide, nano-silicon dioxide, nano-barium sulfate or nano-calcium carbonate; the organic diffusion powder includes silicone resin type diffusion powder, styrene resin type diffusion powder, acrylic resin type diffusion powder or acrylate resin type diffusion powder; preferably, the diffusion powder is silicone resin spherical micropowder.

[0011] Preferably, the average particle size of the diffusion powder is 1-10 um.

[0012] Preferably, the amount of the diffusion powder is 5-15% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent.

[0013] Furthermore, the amount of the filler is 5%-20% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent; preferably, the filler is a black filler.

[0014] According to the second aspect of the present invention, the present invention further provides a packaging material, comprising a packaging film formed from the above-mentioned packaging composition.

[0015] According to the third aspect of the present invention, the present invention also provides a packaging method, comprising the following steps: applying the above-mentioned packaging composition on the LED light board, drying to form a packaging layer on the LED light board, and then thermally curing to form a packaging structure; preferably, it also includes the following steps: after the packaging layer is formed, other packaging films are attached to the packaging layer by vacuum pressing or rolling, and then thermally curing to form a packaging structure; more preferably, the drying temperature is 80-90°C and the time is 3-10min; the vacuum pressing method has a pressure of 1-10kg, a temperature of 70-90°C, and a time of 2-5min; Or it includes the following steps: coating the above-mentioned encapsulation composition on the substrate layer, drying to form an encapsulation film, or hot-pressing the above-mentioned encapsulation film on the LED light board, and thermally curing to form an encapsulation structure; Preferably, the thermal curing temperature is 120-150° C. and the time is 20-40 min.

[0016] According to a fourth aspect of the present invention, the present invention further provides an LED display module, comprising an LED light board and a packaging structure formed by the above-mentioned packaging material, wherein the packaging material is attached to the LED light board by using the above-mentioned packaging method.

[0017] According to the fifth aspect of the present invention, the present invention also provides a repair method for the above-mentioned LED display module. During the packaging process of the LED lamp board, if a dead lamp phenomenon is found before thermal curing, the packaging material is removed and the LED lamp beads are repaired. After the repair is completed, the packaging is performed again according to the above-mentioned packaging method; preferably, the removal is carried out at room temperature or after heating treatment, the heating temperature is 70-100°C, and the heating time is 1-5min.

[0018] The encapsulation composition provided by the present invention selects an ethylene-vinyl acetate copolymer resin with a weight percentage of 35%-45% of vinyl acetate segments as a functional resin, and is used in combination with an organic solvent, a filler and an auxiliary agent. The encapsulation composition can ensure good dispersibility between the components and has the advantage of a short drying time. When applied to an LED light panel, it can achieve high light uniformity, a high blackness value, a good light emission effect, and is easy to repair before curing. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0020] As analyzed in the background art, for the packaging of LED display modules, conventional packaging films in the prior art have problems such as high packaging conditions, difficulty in achieving a tight packaging effect, and difficulty in rework.

[0021] In a first typical embodiment of the present invention, the present invention provides a composition for encapsulation. According to some specific embodiments of the present invention, the composition for encapsulation includes ethylene-vinyl acetate copolymer resin, an organic solvent, a filler and an additive, and the weight percentage of the vinyl acetate segment in the ethylene-vinyl acetate copolymer resin is 35%-45%.

[0022] Optionally, the weight percentage of the vinyl acetate segment in the ethylene-vinyl acetate copolymer resin can be 35%, 37%, 39%, 42%, 45%, etc., and of course, it can also be other values ​​within the above range, which are not limited here. Preferably, the weight percentage of the vinyl acetate segment in the ethylene-vinyl acetate copolymer resin is 39%-42%.

[0023] In the above scheme, the encapsulation composition of the present invention includes ethylene-vinyl acetate copolymer resin, organic solvent, filler and auxiliary agent. The transparent ethylene-vinyl acetate copolymer resin with a vinyl acetate content of 35%-45% is selected, which has good flexibility and elasticity, can reduce the hardness of the encapsulation material, and can ensure that the obtained encapsulation composition is easy to fit tightly with the encapsulation part to be encapsulated when encapsulated under the action of external force. In particular, for LED light boards with gaps, the heat viscosity of the encapsulation composition is small, and a very high temperature is not required to achieve the melting effect, and the fluidity is good, so that it can be directly filled into the gap of the LED light board, thereby achieving a tighter encapsulation effect. The ethylene-vinyl acetate copolymer resin with a vinyl acetate content of 35%-45% has high transparency, can be well matched with the filler, and ensures the color purity of the ethylene-vinyl acetate copolymer encapsulation composition. In addition, the use of transparent ethylene-vinyl acetate copolymer resin with a vinyl acetate content of 35%-45% can improve the solubility of ethylene-vinyl acetate, making it soluble in solvent to make a packaging composition that can be directly coated, which improves the filling property on the one hand, reduces the high temperature requirement of the packaging on the other hand, and can also improve the peel strength between the packaging film and the LED light board, and improve the overall packaging performance of the ethylene-vinyl acetate copolymer packaging composition. The additive can play the role of cross-linking, anti-oxidation, anti-ultraviolet, and anti-aging, thereby further improving the adhesion, anti-oxidation and other properties of the packaging composition. The organic solvent plays the role of effectively dissolving the ethylene-vinyl acetate copolymer resin, and can make the filler and the auxiliary agent evenly dispersed in the organic solvent containing the ethylene-vinyl acetate copolymer resin, so as to ensure the good dispersibility and particle size of each component in the film formed by the encapsulation composition, so that the components can better play a synergistic role, and can achieve the effects of room temperature coating, short drying time and good uniformity. At the same time, the encapsulation film prepared by the encapsulation composition of the present invention is applied to the LED (especially miniled) lamp board, which can achieve the purpose of high light uniformity, high black value and good light effect. The encapsulation composition can be directly filled into the gap of the lamp board, and can be initially pressed at about 80°C and has a certain adhesion with the lamp board, and is easier to tear off from the entire surface of the lamp board, which can protect the chip from damage during the rework process, and achieve the effect of easy rework before curing.

[0024] According to some specific embodiments of the present invention, the solubility parameter SP of ethylene-vinyl acetate copolymer resin is 1 Solubility parameter SP with organic solvents 2 The absolute value of the difference |ΔSP|=|SP 1 -SP 2 | is 0-2, preferably 0-1.5, more preferably 0-1.

[0025] In the above scheme, it is found through experiments that the solubility parameter SP of ethylene-vinyl acetate copolymer resin is 1 Solubility parameter SP with organic solvents 2 The absolute value of the difference is limited within a reasonable range, so that the ethylene-vinyl acetate copolymer resin can be more effectively dissolved in the organic solvent, and then more effectively blended with the filler and the additive to obtain a highly uniform encapsulation composition.

[0026] According to some specific embodiments of the present invention, the solubility parameter SP of the organic solvent is 2 It is 8.0-9.0.

[0027] According to some specific embodiments of the present invention, the organic solvent is selected from one or more of xylene, ethyl acetate, and propylene glycol methyl ether acetate, preferably xylene.

[0028] In the above scheme, by selecting a suitable type of organic solvent, it is possible to effectively dissolve the ethylene-vinyl acetate copolymer resin while facilitating coating and drying.

[0029] According to some specific embodiments of the present invention, the ethylene-vinyl acetate copolymer resin is a transparent ethylene-vinyl acetate copolymer resin, and the resin transmittance is above 90%.

[0030] In the above scheme, the addition of the transparent ethylene-vinyl acetate copolymer resin enables the composition to better present the color of the filler and achieve an ideal color encapsulation effect.

[0031] According to some specific embodiments of the present invention, the weight of the ethylene-vinyl acetate copolymer resin is 12%-40% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent.

[0032] The weight of the ethylene-vinyl acetate copolymer resin is 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent. Of course, it can also be other values ​​within the above range, which is not limited here.

[0033] In the above scheme, by limiting the weight percentage of the ethylene-vinyl acetate copolymer resin to the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent within a reasonable range, it is possible to ensure that the ethylene-vinyl acetate copolymer resin is fully dissolved in the organic solvent.

[0034] According to some specific embodiments of the present invention, the molecular weight of the ethylene-vinyl acetate copolymer resin is greater than 1000.

[0035] In the above scheme, the molecular weight determines the melting temperature, solubility, viscosity, mechanical strength and processing performance of the resin. By limiting the molecular weight of the ethylene-vinyl acetate copolymer resin to a reasonable range, it can better meet the performance requirements of the encapsulation composition of the present invention.

[0036] According to some specific embodiments of the present invention, the solubility parameter SP of ethylene-vinyl acetate copolymer resin is 1 It is 9.0-9.5.

[0037] According to some specific embodiments of the present invention, the auxiliary agent includes a cross-linking agent, and the cross-linking agent includes tert-butyl peroxy isopropyl carbonate, 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane, 1-bis(tert-butyl peroxy)-3,3,5-trimethylcyclohexane, tert-butyl peroxy carbonate-2-ethylhexyl ester, 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexane, 1,1-bis(tert-butyl peroxy)-3,3,5-trimethyl One or more of cyclohexane, 1,1-bis(tert-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-amyl peroxy 2-ethylhexyl carbonate, 2,5-dimethyl 2,5-bis(benzoylperoxy)-hexane, tert-amyl peroxy carbonate, and tert-butyl peroxy 3,3,5-trimethylhexanoate.

[0038] In the above scheme, the crosslinking agent can form a three-dimensional crosslinking structure between the resin molecules, so that the gaps between the resin molecules are filled, thereby improving the hardness, strength, stability and heat resistance of the ethylene-vinyl acetate copolymer resin. By selecting a suitable type of crosslinking agent, the performance of the ethylene-vinyl acetate copolymer resin can be more effectively improved, thereby improving the overall performance of the encapsulation composition.

[0039] Preferably, the amount of the crosslinking agent is 1%-5% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent.

[0040] According to some specific embodiments of the present invention, the auxiliary agent also includes diffusion powder, the diffusion powder includes inorganic diffusion powder and organic diffusion powder, the inorganic diffusion powder includes one or more of ethylene bisstearamide, nano-silicon dioxide, nano-barium sulfate or nano-calcium carbonate; the organic diffusion powder includes silicone resin type diffusion powder, styrene resin type diffusion powder, acrylic resin type diffusion powder or acrylate resin type diffusion powder.

[0041] In the above scheme, the diffusion powder has stress relaxation, impact resistance, lubricity, wear resistance, soft feel and light diffusion. Adding the diffusion powder to the encapsulation composition can improve the light diffusion, increase the cushioning, wear resistance and other properties.

[0042] Preferably, the diffusion powder is organic diffusion powder; more preferably, the diffusion powder is silicone resin spherical powder.

[0043] In the above scheme, the organosilicon resin spherical micropowder can improve the diffusivity of light, increase the cushioning property, wear resistance and other properties, because it has a three-dimensional cross-linked network molecular structure, it can achieve better synergy with the transparent ethylene-vinyl acetate copolymer resin, and increase the bonding performance of the ethylene-vinyl acetate copolymer encapsulation composition. In some specific embodiments, the organosilicon resin spherical micropowder has high brightness, small addition amount, good light diffusivity, high light transmittance, good dispersibility in the resin, and can be directly added. The organosilicon resin spherical micropowder has good solvent resistance, does not dissolve or swell in common organic solvents, and therefore is particularly demanding for the selection of organic solvents. The present invention selects an organic solvent of a suitable type, which is also conducive to the dissolution of the diffusion powder, so that it can play a better material role and prepare a higher uniformity encapsulation composition.

[0044] According to some specific embodiments of the present invention, the amount of the diffusion powder is 5-15% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent.

[0045] Optionally, the amount of diffusion powder is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15% of the sum of the weight of ethylene-vinyl acetate copolymer resin and organic solvent. Of course, it can also be other values ​​within the above range, which is not limited here.

[0046] In the above scheme, by limiting the amount of diffusion powder within a reasonable range, the diffusion powder and the ethylene-vinyl acetate copolymer resin can play a better synergistic role, thereby improving the overall performance of the encapsulation composition.

[0047] Preferably, the average particle size of the diffusion powder is 1-10 μm. The diffusion powder with this average particle size is more easily dispersed in an organic solvent containing ethylene-vinyl acetate copolymer resin.

[0048] According to some specific embodiments of the present invention, the auxiliary agent further includes one or more of a co-crosslinking agent, an antioxidant, an anti-ultraviolet absorber, a diluent, a leveling agent, a tackifier, a defoaming agent and an adhesion promoter.

[0049] Optionally, the auxiliary crosslinking agent includes cyclohexanedimethanol diacrylate, ethylene glycol dimethacrylate, 1,12-dodecyl dimethacrylate, tetraethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol dipropionate, 9-nonanediol diacrylate, 1,10-decanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, ethoxylated bisphenol A dimethacrylate, triethylene glycol dipropionate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, tetrapropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, 2-hydroxy-3-acryloxypropyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, polytetramethylene glycol diacrylate, glycerol diacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, neopentyl glycol dimethacrylate, propoxylated neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, triethylene glycol dimethyl propionate, tripropylene glycol dimethacrylate, tricyclodecane dimethanol dimethacrylate, glycerol dimethacrylate, ethoxylated poly Propylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethallyl isocyanate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, ethoxylated glycerol tripropionate, tetramethylolmethane triacrylate, ethoxylated pentaerythritol tetraacrylate, dimethylolpropane tetraacrylate, trimethylolethane trimethacrylate ester, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, tetramethylolmethane tetraacrylate, di-trimethylolpropane tetraacrylate, pentaerythritol tetramethacrylate, tetramethylolmethane tetramethacrylate, di-trimethylolpropane tetramethacrylate, dipentaerythritol polyacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, dipentaerythritol polymethacrylate, dipentaerythritol hexamethacrylate, polytriallyl isocyanurate, divinylbenzene, di-isopropenylbenzene, diallyl phthalate, p-quinone dioxime, p-p'-dibenzoylquinone dioxime and phenylmaleimide.

[0050] According to some specific embodiments of the present invention, the amount of filler used is 5%-20% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent.

[0051] Optionally, the amount of filler can be 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20% of the sum of the weight of ethylene-vinyl acetate copolymer resin and the organic solvent. Of course, it can also be other values ​​within the above range, which is not limited here.

[0052] In the above scheme, by limiting the amount of filler to a reasonable range, it can play a better synergistic role with other components, thereby improving the overall performance of the encapsulation composition.

[0053] Preferably, the filler is a black filler. The black filler can ensure that the a value and the b value in the Lab value of the packaging material tend to 0, thereby achieving the pure black property of the ethylene-vinyl acetate copolymer packaging composition.

[0054] Preferably, the black filler includes an inorganic black filler and an organic black filler. The black filler can be a single black filler, for example, the inorganic black filler can include one or more of carbon black, manganese iron black, iron oxide black and copper chromium black. The black filler can also be a filler mixture that is a mixture of multiple colored fillers and can ultimately appear black. According to some specific embodiments of the present invention, the preparation method of the encapsulation composition is as follows: adding ethylene-vinyl acetate copolymer resin to an organic solvent and stirring until fully dissolved, then adding an auxiliary agent and a black filler and stirring and sand grinding to make it evenly dispersed.

[0055] In a second typical embodiment of the present invention, the present invention further provides a packaging material, comprising a packaging film formed from the above-mentioned packaging composition.

[0056] According to some specific embodiments of the present invention, the packaging material also includes a substrate layer, one side of which is connected to a packaging film, which serves as a base when the composition is coated and is removed as a release film during packaging; if the release film that has not been removed still exists in the final packaging structure, it can also play a role in protection, light uniformity, and improving surface hardness; optionally, the substrate layer includes but is not limited to PET, PP, PE, PEN, PI, release paper and other materials.

[0057] According to some specific embodiments of the present invention, the packaging material further includes an adhesive layer; optionally, the adhesive layer includes but is not limited to materials such as POE, EVA, PVB, and epoxy resin film.

[0058] Preferably, the thickness of the packaging material is 15-300 μm; the thickness of the packaging film is 15-50 μm.

[0059] The conventional encapsulation film is generally thick, which will have a certain impact on the display effect of the encapsulated LED display module. If the encapsulation film is formed by co-extrusion of a multi-layer film, there may be problems such as poor thickness uniformity, which will also have a certain impact on the display effect of the encapsulated LED display module. The encapsulation film of the encapsulation material of the present invention is formed by direct coating of the solution and has a small thickness, which can improve the uniformity of the encapsulation material and the encapsulation effect.

[0060] In a third typical embodiment of the present invention, the present invention further provides a packaging method, including packaging method one or packaging method two.

[0061] The first encapsulation method comprises the following steps: applying the encapsulation composition on the LED light board, drying to form an encapsulation layer on the LED light board; and then performing thermal curing to form an encapsulation structure. Preferably, the following steps are also included: after the encapsulation layer is formed, attaching other encapsulation films to the encapsulation layer by vacuum pressing or rolling, and then performing thermal curing to form an encapsulation structure.

[0062] In the above scheme, the encapsulation method of the present invention first coats the encapsulation composition on the LED light board and dries it to form an encapsulation layer on the LED light board. The coating process is simple. If the encapsulation layer also contains other encapsulation film structures, the lamination process can be used to tightly combine the encapsulation film with the laminate of "encapsulation layer + LED light board" in a short time, and then the resin system in the encapsulation layer is induced to produce chemical cross-linking through thermal curing, so that it produces a strong bonding force in a short time to achieve bonding with the LED light board. The ethylene-vinyl acetate copolymer in the encapsulation layer is not cross-linked before thermal curing. Therefore, the customer checks whether there is any abnormality during the initial press-fit encapsulation and before curing. If there is, the encapsulation film can be directly torn off on the entire surface for repair. The bonding force between the encapsulation structure and the LED light board after thermal curing can be >80N / cm.

[0063] The second encapsulation method comprises the following steps: coating the above-mentioned encapsulation composition on the substrate layer, drying to form an encapsulation film; hot pressing the encapsulation film on the LED light board, and thermally curing to form an encapsulation structure.

[0064] According to some specific embodiments of the present invention, other packaging films are bonded to the laminate of "packaging layer + LED light board" by vacuum pressing or rolling, so that the packaging film is tightly bonded to the packaging layer.

[0065] According to some specific embodiments of the present invention, the drying temperature is 80-90° C. and the drying time is 3-10 minutes. The drying conditions are mild and the drying time is short.

[0066] According to some specific embodiments of the present invention, the pressure of vacuum pressing is 1-10 kg, the temperature is 70-90° C., and the time is 2-5 min; the temperature of thermal curing is 120-150° C., and the time is 20-40 min.

[0067] In the above scheme, by limiting the pressure, temperature and time of vacuum pressing within a reasonable range, it is more conducive to achieving a tight combination of the LED packaging structure as a whole. By limiting the temperature and time of thermal curing within a reasonable range, it is more conducive to inducing chemical cross-linking of the resin system of the packaging layer, generating stronger bonding force, and thus achieving a better packaging effect.

[0068] According to some specific embodiments of the present invention, the packaging film is attached to the LED light board by vacuum pressing or rolling, so that the packaging film is tightly attached to the LED light board and fills the gaps of the LED lamp beads.

[0069] In a fourth typical embodiment of the present invention, the present invention further provides an LED display module, including an LED light board and the above-mentioned packaging material, wherein the packaging material is attached to the LED light board by the above-mentioned packaging method.

[0070] In the fifth typical embodiment of the present invention, the present invention also provides a rework method for the above-mentioned LED display module. During the packaging process of the LED lamp board, if dead lamps are found before thermal curing, the packaging material is removed for repair, and after the repair is completed, it is packaged again according to the above-mentioned packaging method.

[0071] According to some specific embodiments of the present invention, the removal method is to directly tear off the entire surface at room temperature, or to tear off the entire surface after heating the encapsulation layer, the heating temperature is 70-100° C., and the heating time is 1-5 min.

[0072] In the above repair method, because the ethylene-vinyl acetate copolymer is basically not cross-linked before thermal curing and the peeling strength between it and the LED lamp board is relatively small, it is possible to check whether there is a dead lamp phenomenon before the initial pressing and packaging and thermal curing. If there is, the packaging layer can be directly torn off and the lamp beads can be repaired, instead of repairing after the hot pressing and curing packaging is completed. It is difficult to remove the packaging structure after thermal curing. The present invention avoids the damage to the lamp beads caused by the repair operation itself after thermal curing to a certain extent, and improves the repair efficiency. The beneficial effects of the present invention will be described below in combination with specific embodiments and comparative examples.

[0073] Example 1-1 This embodiment provides a packaging composition, including 20 parts of ethylene-vinyl acetate copolymer resin (the weight percentage of vinyl acetate is equal to 40%, the solubility parameter is 9.4, and the transmittance is 93%), 80 parts of organic solvent xylene (solubility parameter is 8.5), 10 parts of black filler carbon black, 3 parts of cross-linking agent tert-butyl peroxy isopropyl carbonate and 10 parts of diffusion powder (organic silicone resin spherical micropowder, particle size 2um).

[0074] The preparation method of the encapsulation composition is as follows: adding ethylene-vinyl acetate copolymer resin into an organic solvent and stirring until fully dissolved, then adding a crosslinking agent, diffusion powder and black filler, stirring fully, and sand grinding to make them evenly dispersed.

[0075] Example 1-2 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that it is an ethylene-vinyl acetate copolymer resin (the weight percentage of vinyl acetate is equal to 37%, the solubility parameter is 9.3, and the transmittance is 91%).

[0076] Examples 1-3 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that it is an ethylene-vinyl acetate copolymer resin (the weight percentage of the vinyl ester segment is equal to 35%, the solubility parameter is 9.1, and the transmittance is 90%).

[0077] Examples 1-4 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that it is an ethylene-vinyl acetate copolymer resin (the weight percentage of the vinyl ester segment is equal to 45%, the solubility parameter is 9.6, and the transmittance is 95%).

[0078] Examples 1-5 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that the organic solvent is ethyl acetate (solubility parameter 8.3).

[0079] Examples 1-6 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that the organic solvent is propylene glycol methyl ether acetate (solubility parameter 9.4).

[0080] Examples 1-7 This embodiment provides a composition for encapsulation. Compared with Embodiment 1-1, the difference is that the amount of ethylene-vinyl acetate copolymer resin used is 12 parts, and the amount of organic solvent used is 88 parts.

[0081] Examples 1-8 This embodiment provides a composition for encapsulation. Compared with Embodiment 1-1, the difference is that the amount of ethylene-vinyl acetate copolymer resin used is 40 parts, and the amount of organic solvent used is 60 parts.

[0082] Examples 1-9 This embodiment provides a composition for encapsulation. Compared with Embodiment 1-1, the difference is that the amount of ethylene-vinyl acetate copolymer resin used is 10 parts, and the amount of organic solvent used is 90 parts.

[0083] Examples 1-10 This embodiment provides a composition for encapsulation. Compared with Embodiment 1-1, the difference is that the amount of ethylene-vinyl acetate copolymer resin used is 45 parts, and the amount of organic solvent used is 55 parts.

[0084] Examples 1-11 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that the particle size of the diffusion powder is 4 um.

[0085] Examples 1-12 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that the particle size of the diffusion powder is 10 um.

[0086] Examples 1-13 This embodiment provides a composition for encapsulation, which is different from the embodiment 1-1 in that the diffusion powder is spherical SiO 2 .

[0087] Examples 1-14 This embodiment provides a composition for encapsulation. Compared with Embodiment 1-1, the difference lies in that the diffusion powder is polymethyl methacrylate (PMMA).

[0088] Examples 1-15 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that the components include: 25 parts of ethylene-vinyl acetate copolymer resin (the weight percentage of vinyl acetate is 40%, the solubility parameter is 9.3, and the transmittance is 93%), 75 parts of organic solvent xylene (solubility parameter is 8.5), 5 parts of black filler carbon black, 5 parts of cross-linking agent (tert-butyl peroxyisopropyl carbonate) and 8 parts of diffusion powder (organic silicone resin spherical micropowder, particle size 2um).

[0089] Examples 1-16 This embodiment provides a composition for encapsulation, which is different from Embodiment 1-1 in that the components include 30 parts of ethylene-vinyl acetate copolymer resin (the weight percentage of vinyl acetate is equal to 40%, the solubility parameter is 9.3, and the transmittance is 93%), 70 parts of organic solvent xylene (solubility parameter is 8.5), 15 parts of black filler carbon black, 8 parts of a cross-linking agent (tert-butyl peroxyisopropyl carbonate) and 13 parts of diffusion powder (spherical micropowder of silicone resin, particle size 2 um).

[0090] Examples 1-17 This embodiment provides a composition for encapsulation, which is different from Example 1-1 in that it uses ethylene-vinyl acetate copolymer resin (the weight percentage of vinyl acetate is 40%, the solubility parameter is 9.3, and the transmittance is 93%), and the organic solvent is n-propanol (solubility parameter is 11.9).

[0091] Example 2-1 This embodiment provides a packaging method for an LED light board, which is as follows: The encapsulation composition of Example 1 is applied to the encapsulation of the miniled lamp board, and the encapsulation method includes: coating the encapsulation composition of Example 1 on the miniled lamp board, drying (85°C, 5 minutes) to form an encapsulation layer on the miniled lamp board; and then performing thermal curing (temperature of 135°C, time of 30 minutes) to complete the encapsulation of the miniled lamp board.

[0092] Example 2-2 This embodiment provides a packaging method for an LED light board, which is as follows: The packaging material of Example 1 is applied to the packaging of a miniled light board, and the packaging method includes: coating the packaging composition of Example 1 on a PET film, drying (85°C, 5 minutes) to form a packaging film; then hot pressing the packaging film onto the miniled light board, the hot pressing method is vacuum pressing, the pressure is 5kg, the temperature is 80°C, and the time is 3 minutes; finally, heat curing (temperature is 135°C, time is 30 minutes) to complete the packaging of the miniled light board.

[0093] Example 3 This embodiment provides a method for repairing an LED display module, and the encapsulation layer formed by the encapsulation composition of embodiment 1-1 can also realize the repair and tearing function. Before the thermal curing process in the encapsulation process of embodiment 2-1 and embodiment 2-2, the resin in the encapsulation layer is not completely cross-linked, and the adhesion to the substrate lamp beads is less than 40N, and the entire surface of the encapsulation layer is torn off from the lamp board.

[0094] Comparative Example 1 This comparative example provides a packaging composition, which, compared with Example 1-1, uses a conventional EVA film, specifically including 100 parts of ethylene-vinyl acetate copolymer resin (the weight percentage of vinyl acetate is 27%, the solubility parameter is 8.9, and the transmittance is 83%), 10 parts of black filler carbon black, 3 parts of a cross-linking agent (tert-butyl peroxyisopropyl carbonate) and 10 parts of diffusion powder (spherical micropowder of silicone resin, particle size 2um).

[0095] Comparative Example 2 This comparative example provides a composition for encapsulation, which is different from Example 1-1 in that the ethylene-vinyl acetate copolymer resin (the weight percentage of vinyl acetate is equal to 30%, the solubility parameter is 6, and the transmittance is 87%), and a uniform solution cannot be obtained.

[0096] The encapsulated mini-led lamp board was tested for peel strength, black value (L value), light uniformity, light efficiency, and rework effect. The test results are shown in Table 1 below.

[0097] Peel strength: The test method refers to the standard GB / T2790 "Adhesive 180° Peel Strength Test Method Flexible Material to Rigid Material" to test the peel strength between the encapsulation layer and the miniLED light board. Sample size: 200mm*15mm; tensile speed: 100mm / min.

[0098] Blackness value (L value): Use 3nh colorimeter to test the L value of the sample and record it.

[0099] Light uniformity: refer to the standard T / SLDA 01-2022 "General Technical Specifications for Mini LED Commercial Displays" to test the light intensity. The test equipment is LMD, drive power supply, and drive signal equipment. Adjust the display to the working state, and randomly select 5 points on the surface of the packaged miniled lamp board. Test and record the light intensity of these 5 points, and calculate the ratio of the minimum and maximum light intensity of the 5 points.

[0100] Light output efficiency: refer to the standard T / SLDA 01-2022 "General Technical Specifications for Mini LED Commercial Displays" to test the light output intensity. The test equipment is LMD, driving power supply, and driving signal equipment. Adjust the display to the working state, and test the brightness of the center point of the miniled lamp board as the light output intensity. Record the light output intensity of the miniled lamp board before and after encapsulation respectively. Light output efficiency = light output intensity after encapsulation / light output intensity before encapsulation.

[0101] Rework effect: According to the rework method of Example 3, the encapsulation layer formed by the encapsulation composition of Example 1-1 to Example 1-17 is torn off on the entire surface before thermal curing, and the number of damaged lamp beads and the percentage of the area of ​​the remaining encapsulation layer fragments in the whole encapsulation layer are observed and recorded, and the grade is evaluated; A—undamaged lamp beads, residual area percentage ≤5%, B—0<The number of damaged lamp beads ≤5, 5%<The residual area percentage ≤8%, C—5<The number of damaged lamp beads ≤10, 8%<The residual area percentage ≤10%, D—The number of damaged lamp beads>10, the residual area percentage>10%.

[0102] Table 1 (Note: The thickness of the encapsulation layer in the examples is uniformly set to 35 microns, and the minimum thickness of the conventional film in Comparative Example 1 can only be 100 microns)

[0103] It can be seen from the experimental data in Table 1 that the present invention can make the ethylene-vinyl acetate copolymer resin more effectively dissolved in the organic solvent by selecting a transparent ethylene-vinyl acetate copolymer resin with a vinyl acetate content of 35%-45% and an organic solvent with a specific solubility parameter for use, thereby more effectively achieving blending with fillers and additives to obtain a packaging composition with high uniformity, and the packaging film prepared from the packaging composition is applied to the LED (especially miniled) lamp board to achieve excellent packaging effect, and can also achieve high light uniformity (>0.9), high black value (L value>22), good light effect (light efficiency ≥52%). The packaging composition can be directly filled into the gap of the lamp board, and can be initially pressed at around 80°C and has a certain adhesion to the lamp board, and is easier to tear off from the entire surface of the lamp board, and can protect the chip from damage during the rework process, and achieve the effect of easy rework before curing. Compared with the conventional EVA film composition of comparative example 1, the encapsulation structure prepared from the encapsulation composition of the present invention is used to encapsulate the mini-led light board, which can achieve higher light uniformity and higher light efficiency, and is easy to repair before curing. 1 Solubility parameter SP with organic solvents 2 The absolute value of the difference |ΔSP|=|SP 1 -SP 2 When | is controlled within the range of 0-2 (preferably 0-1.5, more preferably 0-1), the above-mentioned properties of the encapsulating composition can be further improved.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composition for encapsulation, characterized in that The invention comprises ethylene-vinyl acetate copolymer resin, organic solvent, filler and auxiliary agent, wherein the weight percentage of vinyl acetate chain segment in the ethylene-vinyl acetate copolymer resin is 35%-45%.

2. The encapsulation composition according to claim 1, characterized in that The absolute value of the difference between the solubility parameter SP1 of the ethylene-vinyl acetate copolymer resin and the solubility parameter SP2 of the organic solvent |ΔSP|=|SP1-SP2| is 0-2.

3. The encapsulation composition according to claim 1 or 2, characterized in that The ethylene-vinyl acetate copolymer resin also satisfies at least one of the following characteristics (1)-(3): (1) The ethylene-vinyl acetate copolymer resin is a transparent ethylene-vinyl acetate copolymer resin, and the resin transmittance is above 90%; (2) The weight of the ethylene-vinyl acetate copolymer resin is 12%-40% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent; (3) The solubility parameter SP1 of the ethylene-vinyl acetate copolymer resin is 9.0-9.

5.

4. The encapsulation composition according to any one of claims 1 to 3, characterized in that The solubility parameter SP2 of the organic solvent is 8.0-9.0; preferably, the organic solvent is selected from one or more of xylene, ethyl acetate, and propylene glycol methyl ether acetate.

5. The encapsulation composition according to any one of claims 1 to 4, characterized in that The auxiliary agent includes a cross-linking agent, and the amount of the cross-linking agent is 1%-5% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent; and / or, The auxiliary agent further comprises diffusion powder, and the diffusion powder comprises at least one of inorganic diffusion powder and organic diffusion powder, and the inorganic diffusion powder comprises one or more of ethylene bis stearamide, nano silicon dioxide, nano barium sulfate or nano calcium carbonate; the organic diffusion powder comprises silicone resin diffusion powder, styrene resin diffusion powder, acrylic resin diffusion powder or acrylate resin diffusion powder; preferably, the diffusion powder is silicone resin spherical micropowder; Preferably, the average particle size of the diffusion powder is 1-10 um; Preferably, the amount of the diffusion powder is 5-15% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent.

6. The encapsulation composition according to any one of claims 1 to 5, characterized in that The amount of the filler is 5%-20% of the sum of the weight of the ethylene-vinyl acetate copolymer resin and the organic solvent; preferably, the filler is a black filler.

7. A packaging material, characterized in that: The invention comprises an encapsulation film formed from the encapsulation composition according to any one of claims 1 to 6.

8. A packaging method, characterized in that: The method comprises the following steps: applying the encapsulation composition according to any one of claims 1 to 6 on an LED light board, drying to form an encapsulation layer on the LED light board, and then thermally curing to form an encapsulation structure; preferably, the method further comprises the following steps: after forming the encapsulation layer, laminating other encapsulation films on the encapsulation layer by vacuum pressing or rolling, and then thermally curing to form an encapsulation structure; more preferably, the drying temperature is 80-90°C and the time is 3-10min; the vacuum pressing pressure is 1-10kg, the temperature is 70-90°C, and the time is 2-5min; Or comprising the following steps: coating the encapsulation composition according to any one of claims 1 to 6 on the substrate layer, drying to form an encapsulation film, or hot pressing the encapsulation film according to claim 7 on the LED light board, and thermally curing to form an encapsulation structure; Preferably, the thermal curing temperature is 120-150° C. and the time is 20-40 min.

9. An LED display module, characterized in that: A packaging structure comprising an LED light board and the packaging material according to claim 7, wherein the packaging material is attached to the LED light board by the packaging method according to claim 8.

10. The LED display module repair method according to claim 9, characterized in that: During the packaging process of the LED lamp board, if dead lamps are found before thermal curing, the packaging material is removed and the LED lamp beads are repaired. After the repair is completed, the packaging is performed again according to the packaging method of claim 8; preferably, the removal is performed at room temperature or after heating treatment, the heating temperature is 70-100°C, and the heating time is 1-5min.

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