High temperature stable epoxy resin composition and encapsulant containing same

Abstract

The present invention relates to a high-temperature stable epoxy resin composition and an encapsulant containing the same, which can be applied to various methods of spraying a low-viscosity liquid, such as an inkjet or dispense coating method, to fill gaps and then curing the liquid. The high-temperature stable epoxy resin composition has high adhesive strength and high-temperature stability upon curing, and thus can be used to bond and mold glass parts of organic or inorganic light-emitting display screens. The present invention also relates to an encapsulant containing the same.

Description

[Technical field]

[0001] The present invention relates to a high-temperature stable epoxy resin composition and an encapsulant containing the same, which can be applied to various methods of spraying a low-viscosity liquid, filling gaps, and curing the resulting mixture, such as an inkjet or dispenser coating method, and has high adhesive strength and high-temperature stability upon curing, and can be used to bond and mold glass components of organic or inorganic light-emitting display screens, and an encapsulant containing the same. [Background technology]

[0002] As user demands for displays change, such as higher integration and lighter, thinner, shorter, and smaller, the physical and chemical properties and usage of encapsulation materials have changed. In the past, cathode ray tubes containing electron beams and fluorescent materials, field emission displays using light emitted by emitter arrays, plasma display panels using the photoelectric effect of plasma gas, and liquid crystal displays using the electrical arrangement and movement of liquid crystals have been widely used in the industry, but their performance and lifespan have varied widely due to issues such as the weight of the display itself, quality issues with dynamic screen display, heat generation, burn-in phenomenon, and high power consumption. In order to improve the various shortcomings of such displays, organic light-emitting display devices have been developed since the late 1980s. Organic light-emitting displays are lighter in weight than conventional displays, have excellent readability, contrast ratio, and have excellent power efficiency and response speed. However, it is known that such display devices also have weaknesses to the burn-in phenomenon and changes in external temperature or humidity.

[0003] In the past, to solve these problems, a method was adopted in which an organic light-emitting display element was enclosed and sealed in a heavy glass or transparent inorganic chamber, but this may cause major problems in the future in terms of product operability, handling reliability, and thinning. A liquid phase is the most effective state for users to freely adjust the shape of the display. Therefore, in order to solve the current problems, the present invention has developed a material that is beneficial for the development of display elements with high adhesive strength and high temperature stability. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical objective of the present invention is to provide a high-temperature stable epoxy resin composition that can be applied to various methods of spraying a low-viscosity liquid, such as an inkjet or dispense coating method, to fill gaps and then cured, generates a low level of gas during the curing process, and has high adhesive strength and high-temperature stability properties during curing, and can be used to bond and mold glass parts of organic or inorganic light-emitting display screens, and an encapsulant containing the same. [Means for solving the problem]

[0005] In order to achieve the above object, the high temperature stable epoxy resin composition of the present invention is characterized by comprising: a highly adhesive epoxy resin containing a compound represented by the following Chemical Formula 1; a diluted epoxy resin; a latent heat curing agent; and a curing retarder.

[0006] [ka]

[0007] In the above formula 1, G is a glycidyl group-containing organic group, and X 1 and X 2 each independently represents a hydrogen atom or a methyl group, each n independently represents an integer of 1 to 10, and R represents a substituted or unsubstituted C10 to C100 alkylene or alkenylene group.

[0008] The high temperature stable epoxy resin composition may include 5 to 150 parts by weight of a highly adhesive epoxy resin, 10 to 100 parts by weight of a diluted epoxy resin, 0.5 to 5.0 parts by weight of a heat curing agent, and 0.1 to 1.0 part by weight of a curing retarder.

[0009] The diluted epoxy resin can be at least one selected from the group consisting of i) epoxy resins containing a substituted or unsubstituted alkyl group, alkylene group, or alkenylene group having 5 to 100 carbon atoms, ii) epoxy resins containing a cycloaliphatic group, and iii) aromatic epoxy resins.

[0010] The diluted epoxy resin may be prepared by including a compound selected from the group consisting of the following A-1 to A-6.

[0011] [ka]

[0012] The thermal curing agent may be a latent thermal curing agent.

[0013] The set retarder may be an amide carboxylic acid.

[0014] In order to achieve the above object, another encapsulant for display elements of the present invention can contain the above-mentioned high-temperature stable epoxy resin composition. Effect of the Invention

[0015] The present invention has the excellent processability, electrical, mechanical and chemical properties that conventional liquid epoxy materials have, and also has excellent high temperature stability, so that users of the composition can obtain workability, productivity and reliability when using this material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The epoxy resin composition according to the present invention will be described in more detail below.

[0017] Epoxy resin is a representative thermosetting resin that changes its linear structure into a three-dimensional network structure through the curing process, and is industrially very important as an electrical and electronic material because it has excellent physical properties such as heat resistance, corrosion resistance, adhesive strength, and insulation. The main reasons why epoxy resin can be used in the electrical and electronic material field are that i) there are many types of epoxy resins and their hardeners, so it can provide various required physical properties, ii) it has excellent physical properties inherent to resins such as excellent adhesive strength, mechanical properties, and chemical resistance, iii) it has less shrinkage deformation during the curing reaction compared to other thermosetting resins, iv) when properly formulated into one-component products, and when a proper hardener is used in the preparation of two-component products, it has a long shelf life and does not generate by-products during the curing reaction, and v) it is suitable for packaging of electrical parts because it can be molded into complex shapes through transfer molding, coating, casting, and manual application.

[0018] In addition, the present invention provides an epoxy resin composition that contains the following high refractive index epoxy resin, diluted epoxy resin, and high adhesive epoxy resin, and has high adhesive strength and high temperature stability when cured while maintaining the mechanical, chemical, and thermal properties inherent to epoxy.

[0019] (a) Highly adhesive epoxy resin The highly adhesive epoxy resin according to the present invention is a bifunctional epoxy resin represented by the following chemical formula 1, and can be used to contribute to the cured structure of an epoxy composition, relieve stress between each substrate of a display, and increase the adhesive strength between a chip and a substrate.

[0020] [ka]

[0021] In the above formula 1, G is a glycidyl group-containing organic group, and X 1 and X 2each independently represents a hydrogen atom or a methyl group, each n independently represents an integer of 1 to 10, and R represents a substituted or unsubstituted C10 to C100 alkylene or alkenylene group.

[0022] The difunctional epoxy resin represented by Chemical Formula 1 is preferably a diglycidyl ether-based difunctional epoxy resin, and specifically, at least one selected from the group consisting of bisphenol F diglycidyl ether type epoxy resin, bisphenol A diglycidyl ether type epoxy resin, polyolefin-added bisphenol A diglycidyl ether type epoxy resin, polyolefin-added bisphenol F diglycidyl type epoxy resin, 1,6-hexanediol diglycidyl ether type epoxy resin, and 1,4-butanediol diglycidyl ether type epoxy resin can be used.

[0023] In the present invention, the bifunctional epoxy resin is preferably included in an amount of 5 to 150 parts by weight. If the content of the bifunctional epoxy resin is less than 5 parts by weight, the time during which the product can be used at room temperature is reduced, and the product does not have a favorable effect on high temperature and high humidity reliability. In addition, the inherent hardness of the composition increases too much, making the product prone to cracking, and may have a negative effect on the adhesive strength, which is undesirable.

[0024] (b) Diluted epoxy resin The diluted epoxy resin according to the present invention can be at least one selected from the group consisting of i) epoxy resins containing a substituted or unsubstituted alkyl group, alkylene group, or alkenylene group having 5 to 100 carbon atoms, ii) epoxy resins containing a cycloaliphatic group, and iii) aromatic epoxy resins, and more specifically, can be produced from a compound selected from the group consisting of the following A-1 to A-6.

[0025] [ka]

[0026] (c) Heat hardener The thermosetting agent of the present invention is a thermosetting polymer, and in order for epoxy resin to perform its proper function, it always needs a suitable curing agent, and the epoxy resin's unique properties are expressed through the curing reaction caused by the curing agent. Conventionally, amine, acid, and phenol curing agents have been used, and selected to have adhesive properties, electrical properties, and resistance to high temperature and humidity that are distinct from other plastic materials. Representatively, the reaction between epoxy resin and amine curing agent is as follows. The amine curing agent attacks the ring of the epoxy resin to open the ring, and the epoxy-amine molecule that has become large by attaching to a specific position attacks the surrounding epoxy resin, causing a chain reaction. After most of the molecules with amine attached are consumed, the reaction ends, and the reaction that creates such a dense structure is called a curing reaction. In this reaction, hydroxyl groups always appear, which has a significant effect on the adhesive strength and the usable life of the product, but it also deteriorates moisture resistance and is unreliable, which can cause cracks.

[0027] [ka]

[0028] In the present invention, a latent heat curing agent that induces a direct reaction between epoxy resins is used as follows. In this reaction, unlike the epoxy-amine reaction, no hydroxyl groups are produced, and a cured product with a long fibrous molecular structure can be obtained. Therefore, unlike the conventional epoxy-curing agent reaction, a structure that is advantageous for long-term reliability can be obtained.

[0029] [ka]

[0030] The latent heat curing agent used herein may include any or commercially available curing agent. Specifically, one or more compounds selected from the group consisting of tetradecyl(trihexyl)phosphonium dicyandiamide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium methanesulfonate, triylcumyl iodonium tetrakis(pentafluorophenyl)borate, Opton CP-66, Opton CP-77 (manufactured by ADEKA Corporation, Japan), 2-ethyl-4 methylimidazolium tetraphenylborate, tetraphenylphosphonium tetraphenylborate, quaternary ammonium borate, (4-acetoxyphenyl)benzyl(methyl)sulfonium, tetrakis(pentafluorophenyl)borate, SI-B2, SI-B3, SI-B3A, SI-B4, and SI-B7 (manufactured by Samshin Chemical Industry Co., Ltd., Korea) may be used.

[0031] In the present invention, the latent heat curing agent is preferably contained in an amount of 0.5 to 5.0 parts by weight, more preferably 0.5 to 3.0 parts by weight, and even more preferably 0.5 to 1.5 parts by weight. If the content of the latent heat curing agent is less than 0.5 parts by weight, it is undesirable because there is a possibility of uncured matter being generated, and if the content of the latent heat curing agent is more than 1.5 parts by weight, it is undesirable because it may cause a decrease in pot life at room temperature or high temperature, a problematic risk of heat generation during curing, and a possibility of the dispensing needle tip being tied up or solidified during the dispensing process, which may affect the use of the product by the user.

[0032] In the present invention, instead of the above-mentioned latent heat curing agent, a general latent curing agent can be used as long as it exhibits physical and chemical properties, and a commercially available product can be used. For example, Ajicure MY-24, Ajicure MY-H, Ajicure PN-23, Ajicure PN-H, Ajicure PN-31, Ajicure PN-40, Ajicure PN-50, VDH, VDH-J, AH-154, ADH, DDH, SAH, IDH, SDH, LDH, UDH, Anka Mine 2441, Anka Mine 2442, Anka Mine 2014AS, Technicure LC-80, Technicure LC-100, Technicure LC-214, Technicure MDU-11, Technicure PDU-250, Technicure IPDU- 8, Technicure TDU-200, EH-4357, Novacure HX-3721, Novacure HX-3722, Novacure HX-3748, Novacure HX-3741, Novacure HX-3742, Novacure HX-3088, Novacure HX-3613, Novacure HX-3921HP, Novacure HX-3941HP, Novacure HX-3932HP, FXR-1081, FXR-1020, FXR-1060, etc. can be used as latent curing agents, and these can be used alone or in combination of two or more. These latent curing agents have a microcapsule form in which the epoxy resin encapsulates the imidazole curing accelerator, and can accelerate the curing action of the epoxy composition only at high temperatures of 80 to 100 ° C or less, and can contribute to storage stability at room temperature.

[0033] (d) Additives, including set retarders The additive according to the present invention may include a curing retarder, and the curing retarder may be an amide represented by the following formula 2. For reference, when stored at 40°C or higher, a composition to which a cationic initiator is applied usually undergoes a change in viscosity, which is due to the generation of a Lewis acid.

[0034] [ka]

[0035] In the above formula 2, R 3 and R 4 may be the same or different and may be alkyl groups.

[0036] Therefore, the present invention makes it possible to obtain a highly reliable resin with little change in viscosity by introducing the curing retarder.

[0037] For reference, amines are highly reactive and therefore have poor safety at high temperatures when added to a composition. However, amide carboxylic acids can reduce amide reactivity through the following resonance stabilization, and thus can suppress viscosity changes caused by curing inhibition at temperatures above 40°C by reacting with the Lewis acid of the cationic thermal initiator, thereby improving high temperature stability.

[0038] [ka]

[0039] The epoxy resin composition according to the present invention may further include an additional additive, if necessary. The additional additive is used to enhance the property of the epoxy composition flowing into the gap between the chip and the substrate and to prevent the occurrence of gaps, and may be, for example, BYK018, BYK019, BYK021, BYK024, BYK066N, BYK909, ethoxyethanol, monoether glycol polyethylene, etc., but is not limited thereto. The above substances may be used alone or in combination of two or more.

[0040] The content of the additive may be 0.01 to 1.0 part by weight. If the content of the additive is less than 0.01 part by weight, the desired effect cannot be obtained, and if the content of the additive is more than 1.0 part by weight, the fluidity may increase excessively, resulting in a decrease in physical properties, which is not preferable. EXAMPLES

[0041] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the following examples.

[0042] [Examples 1 to 6 / Comparative Example: Production of Epoxy Resin Composition] The diluted epoxy resin and adhesive epoxy resin were added to a planetary mixer with the ingredients and amounts shown in Table 1 below, and stirred at room temperature and pressure for 2 hours to make them uniform, and then the set retarder and latent heat curing agent were added in measured amounts and stirred at room temperature and pressure for 2 hours. After that, the mixture was degassed in a vacuum to obtain a viscous liquid.

[0043] [Table 1]

[0044] (1) A-1: ​​Bifunctional liquid epoxy resin, (3',4'-epoxycyclohexane)methyl 3,4-epoxycyclohexylcarboxylate (2) A-2: Bifunctional solid epoxy resin, 2H-Indeno[1,2-b:5,6-b']bisoxirene, octahydro- (3) A-3: Bifunctional liquid epoxy resin, 1,2-epoxy-4-(epoxyethyl)cyclohexane (4) A-4: Monofunctional liquid epoxy resin, (4-tert-butyl-benzyl)-oxirane (5) A-5: 4-functional liquid epoxy resin, pentaerythritol tetraglycidyl ether (6) A-6: Monofunctional liquid epoxy resin, 2-biphenylyl glycidyl ether (7) B-1: Bifunctional liquid epoxy resin, bisphenol A-bisphenol A diglycidyl ether polymer (8) B-2: Bifunctional liquid epoxy resin, 2,2-Bis(4-glycidoxyphenyl)propane (9) E: Additives, Amide Carboxylic Acid Compounds (10) C: Latent heat curing agent, phenylamine borate

[0045] [Basic evaluation of epoxy resin compositions] The epoxy resin compositions prepared in Examples 1 to 6 and the epoxy compositions prepared in Comparative Examples 1 and 2 were evaluated for viscosity, adhesive strength, and high temperature stability (40° C.), and the results are shown in Table 2 below.

[0046] [Table 2]

[0047] 1. Viscosity: Measured at 25±5°C using a Brookfield DV2T viscometer and a cone-and-plate type CPA-51Z spindle, and the viscosity after 30 minutes is recorded. 2. Adhesion: 0.01g of the epoxy composition was applied to a 76mm x 26mm x 3mm glass plate, pressed, and cured in an oven adjusted to 100℃ for 60 minutes, after which the adhesion was measured using a UTM. 3. High temperature stability (40℃): Fill a glass bottle sealed with a rubber stopper with epoxy composition and nitrogen gas, leave it at 40±5℃, measure the viscosity on a daily basis, and if the viscosity change rate is 1.2 times or less compared to the initial viscosity, it is listed.

[0048] As shown in Table 2, it was confirmed that the epoxy compositions prepared in Examples 1 to 6 of the present invention have an appropriate viscosity level, high adhesive strength, and good storage stability. In particular, when an amidocarboxylic acid compound is contained as in Examples 1 to 6, the high temperature stability is increased. In particular, when a bifunctional bisphenol A-bisphenol A diglycidyl ether polymer is used as in Examples 1 to 6, the adhesive strength and high temperature stability properties are ensured. From the physical property evaluation, it was confirmed that the epoxy resin compositions of Examples 1 to 6 can be usefully used as a composition for a sealant for display elements.

[0049] Although the specific parts of the present invention have been described in detail above, it is obvious to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the present invention. Therefore, the substantial scope of the present invention should be defined by the appended claims and their equivalents.

Claims

1. A high temperature stable epoxy resin composition comprising: a high adhesion epoxy resin; a diluted epoxy resin; a cure retarder; and a thermal curing agent. The high adhesive epoxy resin is at least one selected from the group consisting of bisphenol F diglycidyl ether type epoxy resins and bisphenol A diglycidyl ether type epoxy resins; The diluted epoxy resin is at least one selected from the group consisting of i) epoxy resins containing a substituted or unsubstituted alkyl group, alkylene group, or alkenylene group having 5 to 100 carbon atoms, ii) epoxy resins containing a cycloaliphatic group, and iii) aromatic epoxy resins; The hardening retarder is an amide carboxylic acid, 1. A high temperature stable epoxy resin composition, wherein the heat curing agent is a latent heat curing agent.

2. 2. The high temperature stable epoxy resin composition of claim 1, wherein the high temperature stable epoxy resin composition comprises 5 to 150 parts by weight of a high adhesion epoxy resin, 10 to 100 parts by weight of a diluent epoxy resin, and 0.01 to 1.0 parts by weight of a cure retarder.

3. The high temperature stable epoxy resin composition according to claim 1, wherein the diluted epoxy resin comprises a compound selected from the group consisting of A-1 to A-6 below. 【Chemistry 1】

4. An encapsulant for display elements comprising the high temperature stable epoxy resin composition of claim 1.

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