Epoxy resin composition, adhesive film containing epoxy resin composition and LED device containing epoxy resin composition

Abstract

The invention relates to an epoxy resin composition and an adhesive film and an LED device containing the epoxy resin composition, and the epoxy resin composition comprises the following components in parts by weight: 5-25 parts of epoxy resin, 2-5 parts of a flexibilizer, 8-20 parts of a curing agent and 1-5 parts of a diffusant, the epoxy resin comprises a combination of organosilicon epoxy resin, alicyclic epoxy resin and other epoxy resin; the content of the alicyclic epoxy resin is 25-50% of the total mass of the epoxy resin; the organic silicon epoxy resin is organic silicon epoxy resin with a specific structure. By adopting the epoxy resin composition with specific composition, the adhesive film with more excellent toughness and thermal shock resistance is prepared, when the adhesive film is applied to LED device packaging, the product yield can be improved, the problems of lamp panel deformation, lamp failure, interlayer cracking and the like caused by warping in the packaging and curing process are avoided, the process stability is improved, and the production cost is reduced. And an effective scheme is provided for large-scale commercial application of the Mini LED.

Description

Technical Field

[0001] The invention relates to the technical field of packaging adhesives, and in particular to an epoxy resin composition and an adhesive film and an LED device containing the same. Background Art

[0002] With the continuous development of display technology, Mini LED, as a new display technology, has been widely used in the display field due to its advantages such as high brightness, high contrast and high resolution. However, the packaging process of Mini LED is still one of the key factors restricting its large-scale production and application.

[0003] Molding is a traditional Mini LED packaging process. The exposed chip is encapsulated and protected with epoxy resin plastic material through a mold under pressure and temperature to provide interconnection between the chip and other electronic components. Its main advantages include high-precision manufacturing, complex structure manufacturing capabilities, simplified manufacturing process, fast molding cycle, overflow-free and runner-free molding, high-performance characteristics, etc. For example, CN109251723A discloses a Molding high-refractive index LED encapsulation silica gel, comprising component A and component B, wherein the weight ratio of component A to component B is 3:1; wherein: component A comprises the following raw materials in parts by weight: 50-60 parts of methylphenyl vinyl silicone resin, 10-15 parts of vinyl silicone oil, 20-40 parts of hydrogen-containing small molecules, 5-10 parts of chain extender, and 0.5-1.0 parts of inhibitor; component B comprises the following raw materials in parts by weight: 75-85 parts of vinyl silicone oil, 10-20 parts of methylphenyl vinyl silicone resin, 5-10 parts of adhesive, and 0.5-1.5 parts of catalyst; the obtained Molding high-refractive index LED encapsulation silica gel has the characteristics of high brightness, high refractive index, and is suitable for rapid curing in the fast stage of the Molding process; the preparation process is simple, and it is easy to mass produce, and is suitable for use as LED encapsulation silica gel.

[0004] However, the traditional Mini LED packaging process has many shortcomings. For example, the traditional liquid glue has a high curing shrinkage rate and large internal stress, which leads to an uneven packaging surface, and the chip position offset leads to dead light. Moreover, the molding process involves complex mechanical operations and chemical treatments, which makes the entire packaging process time-consuming, seriously affecting production efficiency. Secondly, due to the high requirements for operating precision and the instability of material properties, it is difficult to effectively improve the yield rate, which increases production costs. In addition, the traditional packaging process may also cause damage to Mini LED devices during the packaging process, further reducing product quality. At present, although there are some research reports on LED packaging films, the packaging films warp after curing, have poor process stability, and poor applicability, and cannot meet the use needs of Mini LED direct display screens with different pixel pitches on the market.

[0005] Therefore, in response to the above problems, a new Mini LED packaging film technology has been developed to simplify the packaging process, improve production efficiency, reduce production costs, and at the same time ensure packaging quality and yield, which has very important practical significance and application value. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an epoxy resin composition, an adhesive film and an LED device containing the same. By compounding a specific epoxy resin composition with other components, the product yield is improved and the stability of the production process is effectively controlled. By further structuring the packaging process, efficient and high-quality Mini LED packaging is achieved, which solves the problems of long time consumption and low yield in the traditional MiniLED packaging process, warping of the existing packaging film, poor stability and practicality, etc., and provides an effective solution to the problems existing in the traditional molding process.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an epoxy resin composition, which comprises the following components in parts by weight: 5-25 parts of epoxy resin, 2-5 parts of toughening agent, 8-20 parts of curing agent, and 1-5 parts of diffusing agent;

[0009] The epoxy resin includes a combination of silicone epoxy resin, alicyclic epoxy resin and other epoxy resins;

[0010] The content of the alicyclic epoxy resin is 25-50% of the total mass of the epoxy resin;

[0011] The organosilicon epoxy resin includes a compound having a structure as shown in Formula I:

[0012]

[0013] Among them, n 1 -n 4 are each independently selected from 1-5 (for example, 1, 2, 3, 4 or 5), R 1 -R 4 Each is independently selected from a C1-C5 (eg, C1, C2, C3, C4 or C5) straight chain or branched chain alkyl group, a C1-C5 (eg, C1, C2, C3, C4 or C5) alkoxy group.

[0014] The epoxy resin composition provided by the present invention includes a combination of at least three epoxy resins, wherein the silicone epoxy resin has a lower surface tension, has a very good wetting and dispersing effect with the diffusant, and the silicone epoxy resin has excellent heat resistance, and its addition solves the poor agglomeration of the diffusant in the packaging process of the Mini LED display screen, and improves the product yield. On the other hand, the reaction speed is faster when the content of the alicyclic epoxy resin is high during the heating pre-curing process. The present invention can effectively control the stability of the production process by limiting the ratio of the alicyclic epoxy resin to the non-alicyclic epoxy resin. In addition, since the molecular weight of the general alicyclic epoxy resin is small, the poor toughness after curing is not conducive to film formation, and the proportion control of the alicyclic epoxy can effectively solve the problem of severe warping of the Mini LED display screen and the fracture of the film material. At the same time, the present invention uses a multifunctional silicone epoxy resin to improve the degree of crosslinking with other components in the composition, further improve the toughness of the cured adhesive film, and reduce the generation of warping or film fracture problems.

[0015] Wherein, in parts by weight, the epoxy resin is 5-25 parts, for example, 6 parts, 7 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts or 24 parts.

[0016] In parts by weight, the toughening agent is 2-5 parts, for example, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts.

[0017] In parts by weight, the curing agent is 8-20 parts, for example, 9 parts, 10 parts, 11 parts, 13 parts, 15 parts, 17 parts or 19 parts.

[0018] In parts by weight, the diffusing agent is 1-5 parts, for example, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts.

[0019] The content of the alicyclic epoxy resin is 25-50% of the total mass of the epoxy resin, for example, it can be 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% or 48%, etc.

[0020] Preferably, the content of the organosilicon epoxy resin is 8-20% of the total mass of the epoxy resin, for example, it may be 9%, 10%, 12%, 14%, 16% or 18%.

[0021] Preferably, the silicone epoxy resin comprises a compound having a structure as shown in Formula II:

[0022]

[0023] Preferably, the relative molecular weight of the alicyclic epoxy resin is 200-500, for example, 250, 300, 350, 400 or 450.

[0024] Preferably, the other epoxy resin comprises an aromatic epoxy resin.

[0025] Preferably, the aromatic epoxy resin comprises bisphenol A epoxy resin and / or bisphenol F epoxy resin.

[0026] Preferably, the epoxy equivalent of the other epoxy resin is 100-200 g / eq, for example, 110 g / eq, 130 g / eq, 150 g / eq, 170 g / eq or 190 g / eq.

[0027] Preferably, the toughening agent includes any one of acrylic rubber, core-shell structured styrene-butadiene rubber, nitrile rubber-modified epoxy resin, polyurethane-modified epoxy resin or polyol, or a combination of at least two thereof, and more preferably polyol.

[0028] Preferably, the polyol includes any one of ethylene glycol, propylene glycol, glycerol, dipropylene glycol, polypropylene glycol, polyester polyol or polyether polyol, or a combination of at least two thereof.

[0029] Preferably, the hydroxyl value of the polyol is 150-300 mgKOH / g, for example, 160 mgKOH / g, 180 mgKOH / g, 200 mgKOH / g, 220 mgKOH / g, 240 mgKOH / g, 260 mgKOH / g or 280 mgKOH / g.

[0030] As the preferred technical method of the present invention, a polyol toughening agent with a hydroxyl value of 150-300 mgKOH / g is used. Due to its excellent toughness and low glass transition temperature (Tg), it can improve the toughness of the film. At the same time, the Tg of the film after complete curing is small. When applied to Mini LED packaging, it can be completely removed by heating after curing to achieve rework, which solves the problem of difficult Mini LED rework in the prior art and further reduces costs.

[0031] Preferably, the curing agent includes an anhydride curing agent.

[0032] Preferably, the anhydride curing agent includes any one of methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride or tetrahydrophthalic anhydride, or a combination of at least two thereof.

[0033] Preferably, the diffusing agent includes any one of organic silicon microspheres, spherical silicon dioxide or spherical calcium carbonate, or a combination of at least two thereof.

[0034] Preferably, the particle size distribution D50 of the diffusing agent is 1-4 μm, for example, 1.5 μm, 2 μm, 2.5 μm, 3 μm or 3.5 μm.

[0035] In the present invention, the particle size distribution D50 refers to the particle size corresponding to when the cumulative particle size distribution percentage of the sample reaches 50%, also known as the median particle size or median particle size.

[0036] Preferably, the refractive index of the diffusing agent is 1.4-1.5, for example, it may be 1.41, 1.43, 1.45, 1.47 or 1.49.

[0037] Preferably, the amount of the diffusing agent is 5-10% of the total mass of the epoxy resin composition, for example, 5.5%, 6%, 6.5%, 7%, 8% or 9%.

[0038] Preferably, the epoxy resin composition further comprises 0.1-0.3 parts of coupling agent, for example, 0.12 parts, 0.15 parts, 0.18 parts, 0.2 parts, 0.22 parts, 0.25 parts or 0.28 parts, etc., by weight.

[0039] Preferably, the coupling agent comprises a silane coupling agent.

[0040] Preferably, the silane coupling agent includes any one of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane or 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, or a combination of at least two thereof.

[0041] Preferably, the epoxy resin composition further comprises 0.2-0.8 parts of accelerator, for example, 0.25 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts or 0.7 parts, etc., in parts by weight.

[0042] Preferably, the accelerator includes any one of tetramethylammonium bromide, tetrabutylammonium bromide or triphenylphosphine, or a combination of at least two thereof.

[0043] Preferably, the epoxy resin composition further comprises 0.02-0.08 parts of a color enhancer, for example, 0.03 parts, 0.04 parts, 0.05 parts, 0.06 parts or 0.07 parts, etc., in parts by weight.

[0044] Preferably, the colorant includes a black colorant, such as black toner, black color paste, etc.

[0045] For example, the color enhancer in the present invention may be nano carbon black.

[0046] In the present invention, the problem of difficulty in covering defects on substrates in the traditional process is effectively solved by adding a black color enhancer.

[0047] Preferably, the haze of the epoxy resin composition is ≥90%, for example, it may be 91%, 93%, 95%, 97% or 99%.

[0048] Preferably, the shading rate of the epoxy resin composition is ≥70%, for example, it may be 72%, 75%, 78%, 80%, 85%, 90% or 95%.

[0049] Preferably, the refractive index of the epoxy resin composition is ≥1.5, for example, it may be 1.55, 1.6, 1.7, 1.8, 1.9 or 2.0.

[0050] Preferably, the moisture content of the epoxy resin composition is less than 2%, for example, it may be 1.8%, 1.6%, 1.4%, 1.2%, 1%, 0.8%, 0.6%, 0.4%, 0.2%, 0.1% or 0.05%, etc., and more preferably less than 1%.

[0051] In a second aspect, the present invention provides a method for preparing the epoxy resin composition according to the first aspect, the preparation method comprising the following steps:

[0052] The epoxy resin, toughening agent, diffusing agent, optional coupling agent, optional accelerator and optional color enhancer are mixed to obtain the epoxy resin composition.

[0053] Preferably, the preparation method comprises the following steps:

[0054] (1) mixing epoxy resin, toughening agent and coupling agent to obtain a liquid mixture, then adding a diffusing agent and a color enhancer and stirring to obtain an epoxy resin matrix;

[0055] mixing a curing agent with an accelerator to obtain an epoxy reaction component;

[0056] (2) Mixing the epoxy resin matrix obtained in step (1) with epoxy reaction components to obtain the epoxy resin composition.

[0057] Preferably, the mixing time in step (1) is 20-30 min, for example, 21 min, 23 min, 25 min, 27 min or 29 min.

[0058] Preferably, the stirring time in step (1) is 1-2 h, for example, 1.1 h, 1.3 h, 1.5 h, 1.7 h or 1.9 h.

[0059] Preferably, the mixing time in step (1) is 10-20 min, for example, 11 min, 13 min, 15 min, 17 min or 19 min.

[0060] Preferably, the mixing in step (1) is performed under vacuum.

[0061] Preferably, the mixing time in step (2) is 10-20 min, for example, 11 min, 13 min, 15 min, 17 min or 19 min.

[0062] Preferably, the mixing in step (2) is performed under vacuum.

[0063] In a third aspect, the present invention provides an adhesive film, which is obtained by curing the epoxy resin composition as described in the first aspect.

[0064] Preferably, the adhesive film comprises a first release layer, a semi-cured adhesive film and a second release layer stacked in sequence; wherein the raw material for preparing the semi-cured adhesive film comprises the epoxy resin composition described in the first aspect.

[0065] Preferably, the curing rate of the semi-cured adhesive film is 20-30%, for example, 22%, 24%, 26% or 28%.

[0066] Preferably, the release force of the first release layer is 1-15g / 25mm, for example, it can be 2g / 25mm, 4g / 25mm, 6g / 25mm, 8g / 25mm, 10g / 25mm, 12g / 25mm or 14g / 25mm, and more preferably 5-10g / 25mm.

[0067] Preferably, the release force of the second release layer is 15-35g / 25mm, for example, it can be 16g / 25mm, 18g / 25mm, 20g / 25mm, 22g / 25mm, 24g / 25mm, 26g / 25mm, 28g / 25mm, 30g / 25mm, 32g / 25mm or 34g / 25mm, and more preferably 20-25g / 25mm.

[0068] As a preferred technical solution of the present invention, the use of a release layer with a specific release force has a positive effect on the appearance of the film when it is torn off.

[0069] In a fourth aspect, the present invention provides a method for preparing the adhesive film according to the third aspect, the preparation method comprising the following steps:

[0070] The epoxy resin composition as described in the first aspect is coated between the first release layer and the second release layer, and cured to obtain the adhesive film.

[0071] Preferably, the coating speed is 0.1-0.5 m / min, for example, 0.15 m / min, 0.2 m / min, 0.25 m / min, 0.3 m / min, 0.35 m / min, 0.4 m / min or 0.45 m / min, etc., more preferably 0.2-0.3 m / min.

[0072] Preferably, the curing includes pre-curing and cooling curing.

[0073] Preferably, the pre-curing temperature is 90-105°C, for example, 92°C, 95°C, 98°C, 100°C or 102°C.

[0074] Preferably, the pre-curing time is 8-12 min, for example, it can be 8.5 min, 9 min, 9.5 min, 10 min, 10.5 min, 11 min or 11.5 min.

[0075] Preferably, the temperature of the cooling and curing is 85-100°C, for example, 88°C, 90°C, 92°C, 95°C or 98°C.

[0076] Preferably, the cooling and curing time is 8-12 min, for example, it can be 8.5 min, 9 min, 9.5 min, 10 min, 10.5 min, 11 min or 11.5 min.

[0077] In a fifth aspect, the present invention provides a packaging method, which uses the adhesive film as described in the third aspect.

[0078] Preferably, the packaging method comprises the following steps:

[0079] The adhesive film as described in the third aspect is attached to the panel to be packaged, and heated to complete the packaging.

[0080] Preferably, the first release film is removed before the lamination, and the exposed semi-cured adhesive film is laminated to the panel to be packaged.

[0081] Preferably, the lamination method includes roll lamination or heat press lamination.

[0082] Preferably, the lamination method is roll lamination, and the packaging method includes removing the first release film, preheating the adhesive film, and performing roll lamination with the panel to be packaged.

[0083] Preferably, the preheating temperature is 70-90°C, for example, it can be 72°C, 75°C, 78°C, 80°C, 82°C, 85°C or 88°C.

[0084] Preferably, the preheating time is 10-15 min, for example, it can be 10.5 min, 11 min, 12 min, 13 min or 14 min.

[0085] Preferably, the rolling and laminating operation includes lifting one side of the adhesive film, making the other side of the semi-cured film layer overlap with one side of the panel to be packaged, and simultaneously pressing the adhesive on the top, applying pressure, and rolling toward the other side.

[0086] Preferably, the applied pressure is ≥ 0.6 kg / cm 2 , for example, it can be 0.65kg / cm 2 , 0.7kg / cm 2 , 0.8kg / cm 2 , 0.9kg / cm 2 , 1kg / cm 2 , 1.1kg / cm 2 , 1.2kg / cm 2 , 1.5kg / cm 2 , 1.8kg / cm 2 or 2kg / cm 2 etc., more preferably 0.8-1.2kg / cm 2 .

[0087] Preferably, the rolling speed is ≤1 m / min, for example, it can be 0.95 m / min, 0.9 m / min, 0.8 m / min, 0.7 m / min, 0.6 m / min, 0.5 m / min, 0.4 m / min, 0.2 m / min, 0.1 m / min or 0.05 m / min, etc., and more preferably 0.4-0.8 m / min.

[0088] Preferably, the temperature of the hot pressing bonding is 40-80°C, for example, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C or 75°C.

[0089] Preferably, the pressure of the hot pressing bonding is 0.2-1 MPa, for example, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa or 0.8 MPa.

[0090] Preferably, the hot pressing bonding time is 1-5 min, for example, it can be 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min or 4.5 min.

[0091] Preferably, the heating temperature is 70-130°C, for example, 75°C, 80°C, 90°C, 100°C, 110°C or 120°C.

[0092] Preferably, the heating time is 0.5-3 h, for example, 0.8 h, 1 h, 1.2 h, 1.5 h, 2 h or 2.5 h.

[0093] Preferably, the packaging method further comprises removing the second release film.

[0094] In a sixth aspect, the present invention provides an LED device, wherein the LED device comprises the epoxy resin composition as described in the first aspect or the adhesive film as described in the third aspect.

[0095] Compared with the prior art, the present invention has at least the following beneficial effects:

[0096] The epoxy resin composition provided by the present invention is compounded with other components through a specific epoxy resin composition, which reduces the warping of the encapsulation film, improves the product yield, and effectively controls the stability of the production process; by further limiting the hydroxyl value of the polyol toughening agent, the obtained film can be repaired at a relatively low temperature, solving the pain point of the difficulty of repairing liquid molding glue. The epoxy composition provided by the present invention is applied to Mini LED packaging, which can achieve efficient and high-quality bonding of the panel, and the overall process is short in time and low in equipment investment, which is conducive to promoting the further development and application of Mini LED technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 This is a schematic diagram of the structure of the adhesive film obtained in Example 1 of the present invention;

[0098] Figure 2 Schematic diagram of the preparation of the adhesive film in Example 1 of the present invention;

[0099] in, Figure 1 1-first release layer, 2-semi-cured adhesive film, 3-second release layer;

[0100] Figure 2 1-first release layer, 12-epoxy resin composition, 3-second release layer, 4-first oven, 5-second oven. DETAILED DESCRIPTION

[0101] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0102] The specific grades of the materials used in the following examples are shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] Example 1

[0107] An epoxy resin composition, which comprises, by weight, 5 parts of liquid bisphenol A epoxy resin, 5 parts of bisphenol F epoxy resin, 7 parts of alicyclic epoxy resin, 1.5 parts of silicone epoxy resin, 3 parts of toughening agent polyester polyol (AG-9006), 0.2 parts of silane coupling agent, 3.5 parts of diffusing agent silicone microspheres, 14.8 parts of anhydride curing agent, 0.5 parts of nitrogen-containing accelerator, and 0.07 parts of color enhancer;

[0108] The epoxy resin composition is prepared by the following method:

[0109] (1) Accurately weighing epoxy resin, toughening agent, and coupling agent, placing them in a new type of stirrer and stirring for 25 minutes to obtain a uniformly mixed liquid mixture, and then adding accurately weighed diffusing agent and color enhancer thereto, stirring for 1 hour to make all the materials uniformly mixed, to obtain a black epoxy resin matrix;

[0110] Accurately weigh the curing agent and accelerator, and stir them in another container under vacuum for 20 minutes to obtain a clear epoxy reaction component;

[0111] (2) The epoxy reaction component obtained in step (1) and a black epoxy resin matrix are vacuum sealed and stirred for 20 minutes to obtain a viscous black glue, which is the epoxy resin composition.

[0112] Examples 2-5, Comparative Examples 1-3

[0113] An epoxy resin composition, which differs from Example 1 in that the formula of the epoxy resin composition is different, as shown in Table 2; wherein the dosage unit of each component is "parts by weight" of solid content; and the preparation method of the epoxy resin composition is the same as that of Example 1.

[0114] Table 2

[0115]

[0116] Comparative Example 4

[0117] The commercially available molding glue is polomo EP2271, and the molding glue is a liquid packaging glue.

[0118] Application Example 1-5, Comparative Application Example 1-3

[0119] A film, the film structure is as follows Figure 1 As shown, it includes a first release layer, a semi-cured adhesive film of the epoxy resin composition obtained in Examples 1-5 and Comparative Examples 1-3, and a second release layer;

[0120] The preparation method of the film is as follows Figure 2 As shown, the following steps are included:

[0121] The epoxy resin composition obtained in Examples 1-5 and Comparative Examples 1-3 was coated between the first release layer and the second release layer at a speed of 0.3 m / min, and passed through a first oven and a second oven, both of which were 4.5 m in length, with the first oven temperature being 100° C. and the second oven temperature being 90° C., to obtain the adhesive film.

[0122] Comparative Application Example 4

[0123] The molding glue of comparative example 4 was used to encapsulate the Mini LED module using the traditional molding process, and the bonding and lighting effects of the molding glue were tested.

[0124] The above film was tested as follows:

[0125] 1. Test of basic properties of film

[0126] 1) Curing rate

[0127] The test was conducted according to the national standard GB / T 37498-2019. Samples from different batches of the same embodiment or comparative example were tested 10 times, and the variance was calculated.

[0128] The above film was further cured at 130° C. for 90 min, and then the film state, glass transition temperature, and tensile strength were tested.

[0129] 2) Film status

[0130] Fold the film 180 degrees and observe its breaking condition.

[0131] 3) Glass transition temperature

[0132] The test was carried out using a differential scanning calorimeter (DSC).

[0133] 4) Tensile strength

[0134] The elongation at break is tested according to the national standard GBT 30776-2014.

[0135] The test results of the basic properties of the film are summarized in Table 3.

[0136] Table 3

[0137]

[0138]

[0139] Note: The experimental data in Table 3 are the physical properties of complete curing. The molding glue in Comparative Example 4 is liquid glue, and the degree of curing is uncontrollable, which is different from the semi-cured adhesive film of the present invention, so there is no curing rate test.

[0140] 2. Film lamination and lighting effect

[0141] After tearing off the first release layer of the above-mentioned film, the semi-cured film layer is hot-pressed onto the mini LED light board with a laminating pressure of 0.7 MPa and a laminating temperature of 80°C. It is then cured at 130°C for 2 hours. After complete curing, the second release layer is removed to obtain a Mini LED module, which is then tested as follows.

[0142] 1) Lamination yield rate

[0143] The above method was used to encapsulate and bond 100 Mini LED modules, and the proportion of those that could be successfully lit and had no poor diffusion powder agglomeration was counted.

[0144] 2)Rework capability

[0145] After the film is completely cured, heat the module to 130℃ for 10 minutes, tear off the film, and observe the residual film on the surface of the light board. The residual film area on the surface of the light board is less than 10%, which is qualified.

[0146] 3) Warpage performance

[0147] After the Mini LED module cutting process edge is completely cured, lay the display surface flat on an absolutely flat plane and measure the distance between the center of the light board and the plane.

[0148] The test results of film lamination and lighting effect are summarized in Table 4.

[0149] Table 4

[0150]

[0151] It can be seen from the test results that the epoxy resin composition and the cured adhesive film provided by the present invention, through the compounding of specific components, solve the problems of low yield, severe warping, and agglomeration of diffusants of traditional liquid molding adhesives, while further improving its weather resistance and process stability. The curing rate is between 24-30%, and the variance of 10 repeated experiments is 0.3-0.41. In some preferred technical solutions, a rework function that cannot be achieved by traditional molding adhesives is provided, which greatly reduces the production cost of MiniLED and is conducive to the large-scale commercial use of MiniLED.

[0152] By comparing Example 1 with Examples 4 and 5, it can be seen that the present invention can improve the toughness of the film by adopting a polyol toughening agent and limiting the hydroxyl value range. The Tg after complete curing is less than 90°C, and it can be applied to Mini LED light board packaging and heated at 130°C for 10 minutes after curing, thereby achieving rework.

[0153] By comparing Example 1 with Comparative Example 1, it can be seen that the present invention controls the ratio of alicyclic epoxy with faster reaction rate to non-alicyclic epoxy with lower reaction rate in the preparation of the adhesive film, reduces warping, improves product yield, and effectively controls the stability of the production process.

[0154] By comparing Example 1 with Comparative Examples 2 and 3, it can be seen that the present invention uses a low surface tension silicone epoxy resin to promote the dispersion of the diffusing agent, which can effectively avoid the undesirable phenomenon of the diffusing agent agglomerating during the packaging process. After the Mini LED module is lit, there is no undesirable phenomenon such as agglomeration of the diffusion powder. In addition, the Mini LED module after film encapsulation has low warpage and small internal stress, which can effectively avoid problems such as deformation of the lamp board, dead lamps, and interlayer cracking caused by warping during the encapsulation curing process.

[0155] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. An epoxy resin composition, characterized in that The epoxy resin composition comprises the following components in parts by weight: 5-25 parts of epoxy resin, 2-5 parts of toughening agent, 8-20 parts of curing agent, and 1-5 parts of diffusing agent; The epoxy resin includes a combination of silicone epoxy resin, alicyclic epoxy resin and other epoxy resins; The content of the alicyclic epoxy resin is 25-50% of the total mass of the epoxy resin; The organosilicon epoxy resin includes a compound having a structure as shown in Formula I: Wherein, n1-n4 are each independently selected from 1-5, and R1-R4 are each independently selected from C1-C5 straight chain or branched chain alkyl, C1-C5 alkoxy.

2. The epoxy resin composition according to claim 1, characterized in that The content of the organosilicon epoxy resin is 8-20% of the total mass of the epoxy resin; Preferably, the silicone epoxy resin comprises a compound having a structure as shown in Formula II:

3. The epoxy resin composition according to claim 1 or 2, characterized in that The relative molecular weight of the alicyclic epoxy resin is 200-500; Preferably, the other epoxy resin comprises an aromatic epoxy resin; Preferably, the aromatic epoxy resin comprises bisphenol A epoxy resin and / or bisphenol F epoxy resin; Preferably, the epoxy equivalent of the other epoxy resin is 100-200 g / eq.

4. The epoxy resin composition according to any one of claims 1 to 3, characterized in that The toughening agent includes any one or a combination of at least two of acrylic rubber, core-shell structured styrene-butadiene rubber, nitrile rubber-modified epoxy resin, polyurethane-modified epoxy resin or polyol, preferably polyol; Preferably, the polyol includes any one or a combination of at least two of ethylene glycol, propylene glycol, glycerol, dipropylene glycol, polypropylene glycol, polyester polyol or polyether polyol; Preferably, the hydroxyl value of the polyol is 150-300 mgKOH / g; Preferably, the curing agent comprises an anhydride curing agent; Preferably, the acid anhydride curing agent includes any one of methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride or tetrahydrophthalic anhydride, or a combination of at least two thereof; Preferably, the diffusing agent includes any one of organic silicon microspheres, spherical silicon dioxide or spherical calcium carbonate, or a combination of at least two thereof; Preferably, the particle size distribution D50 of the diffusant is 1-4 μm; Preferably, the refractive index of the diffusing agent is 1.4-1.5; Preferably, the amount of the diffusing agent is 5-10% of the total mass of the epoxy resin composition.

5. The epoxy resin composition according to any one of claims 1 to 4, characterized in that The epoxy resin composition further comprises 0.1-0.3 parts of a coupling agent in parts by weight; Preferably, the coupling agent comprises a silane coupling agent; Preferably, the silane coupling agent includes any one of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane or 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane or a combination of at least two thereof; Preferably, the epoxy resin composition further comprises 0.2-0.8 parts by weight of an accelerator; Preferably, the accelerator comprises any one of tetramethylammonium bromide, tetrabutylammonium bromide or triphenylphosphine or a combination of at least two thereof; Preferably, the epoxy resin composition further comprises 0.02-0.08 parts of a color enhancer, based on parts by weight; Preferably, the haze of the epoxy resin composition is ≥90%; Preferably, the shading rate of the epoxy resin composition is ≥70%; Preferably, the refractive index of the epoxy resin composition is ≥1.5; Preferably, the moisture content of the epoxy resin composition is less than 2%, and more preferably less than 1%.

6. A method for preparing the epoxy resin composition according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: The epoxy resin composition is mixed with an epoxy resin, a toughening agent, a diffusing agent, an optional coupling agent, an optional accelerator, and an optional color enhancer; Preferably, the preparation method comprises the following steps: (1) mixing epoxy resin, toughening agent and coupling agent to obtain a liquid mixture, then adding a diffusing agent and a color enhancer and stirring to obtain an epoxy resin matrix; mixing a curing agent with an accelerator to obtain an epoxy reaction component; (2) mixing the epoxy resin matrix obtained in step (1) with an epoxy reaction component to obtain the epoxy resin composition; Preferably, the mixing time in step (1) is 20-30 min; Preferably, the stirring time in step (1) is 1-2 hours; Preferably, the mixing time in step (1) is 10-20 min; Preferably, the mixing in step (1) is performed under vacuum; Preferably, the mixing time in step (2) is 10-20 min; Preferably, the mixing in step (2) is performed under vacuum.

7. A film, characterized in that: The adhesive film is obtained by curing the epoxy resin composition according to any one of claims 1 to 5; Preferably, the adhesive film comprises a first release layer, a semi-cured adhesive film and a second release layer stacked in sequence; wherein the raw material for preparing the semi-cured adhesive film comprises the epoxy resin composition according to any one of claims 1 to 5; Preferably, the release force of the first release layer is 1-15 g / 25 mm, more preferably 5-10 g / 25 mm; Preferably, the release force of the second release layer is 15-35 g / 25 mm, more preferably 20-25 g / 25 mm.

8. A method for preparing the adhesive film as claimed in claim 7, characterized in that: The preparation method comprises the following steps: Applying the epoxy resin composition according to any one of claims 1 to 5 between the first release layer and the second release layer, and curing to obtain the adhesive film; Preferably, the coating speed is 0.1-0.5 m / min, more preferably 0.2-0.3 m / min; Preferably, the curing includes pre-curing and cooling curing; Preferably, the pre-curing temperature is 90-105°C; Preferably, the pre-curing time is 8-12 minutes; Preferably, the temperature of the cooling and curing is 85-100°C; Preferably, the cooling and curing time is 8-12 minutes.

9. A packaging method, characterized in that: The packaging method uses the adhesive film as claimed in claim 7; Preferably, the packaging method comprises the following steps: Laminating the adhesive film as claimed in claim 7 to the panel to be packaged, heating, and completing the packaging; Preferably, the first release film is removed before laminating, and the exposed semi-cured adhesive film is laminated to the panel to be packaged; Preferably, the lamination method includes roll lamination or heat press lamination; Preferably, the lamination method is roll lamination, and the packaging method includes removing the first release film, preheating the adhesive film, and rolling laminating it with the panel to be packaged; Preferably, the preheating temperature is 70-90°C; Preferably, the preheating time is 10-15 minutes; Preferably, the rolling lamination operation includes lifting one side of the adhesive film, making the other side of the semi-cured film layer overlap with one side of the panel to be packaged, and simultaneously pressing the adhesive on the top, applying pressure, and rolling toward the other side; Preferably, the applied pressure is ≥ 0.6 kg / cm 2 , more preferably 0.8-1.2kg / cm 2 ; Preferably, the rolling speed is ≤1 m / min, more preferably 0.4-0.8 m / min; Preferably, the temperature of the hot pressing bonding is 40-80°C; Preferably, the pressure of the hot pressing bonding is 0.2-1MPa; Preferably, the heat pressing bonding time is 1-5min; Preferably, the heating temperature is 70-130°C; Preferably, the heating time is 0.5-3h; Preferably, the packaging method further comprises removing the second release film.

10. An LED device, characterized in that: The LED device comprises the epoxy resin composition according to any one of claims 1 to 5 or the adhesive film according to claim 7.

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