KR920001442B1 - Epoxy resin composition for light-emitting elements - Google Patents

Abstract

An epoxy resin composition is obtained by mixing (methy) hexahydro phthalic anhydride as a curing agent and diaza- bicyclo alkenes or its salts as a curing accelerator with a main component. The main component is composed of 50-75 wt.% bisphenol-A epoxy resin (1) of 200-250 epoxy equivalent, 5-15 wt.% bisphenol-A (2), 15-35 wt.% alicyclic epoxy resin (3), and 5-20 wt.% dibutyl phthalate (4). The resin (3) is 3,4-cyclohexylmethyl (3,4-epoxy)cyclohexyl carboxilate. The resin composition has a good heat resistance and a low internal stress, and used for the light-emitting elements.

Description

Epoxy Resin Compositions for Light-Emitting Devices

The present invention relates to an epoxy resin composition for a light emitting device.

In particular, it is excellent in heat resistance, so that even when it is left at a high temperature for a long time, transparency decreases, and adhesion to the device is excellent, there is little possibility of failure due to water absorption, and it minimizes the internal stress of the cured product and is suitable for manufacturing large light emitting devices. It relates to an epoxy resin composition.

The light emitting device is widely used in home appliances such as audio equipment, video, TV, etc., display devices of automobiles, desktop calculators, etc. due to various advantages such as low power consumption, long life, and no maintenance during use. In order to protect the light emitting device from external environments such as moisture, vibration, shock and heat, and to maintain the original function of the light emitting device, the device portion is sealed with a thermosetting resin.

The resin encapsulating this light emitting element should be colorless and transparent in order to emit light emitted efficiently to the outside, and this transparency is not degraded by heat, ultraviolet light or other changes of the external environment over time. It is demanded to suppress penetration and to have high reliability.

Epoxy resins are most often used as resins satisfying these conditions. In addition, the encapsulation method includes a deposition method, a embedding method, a transfer molding method, and a molding method. This encapsulation method is selected according to the size and type of product.

In general, the epoxy resin can be used to obtain a cured product excellent in electrical and mechanical properties by using an acid anhydride-based curing agent and an amine-based curing agent.

However, in recent years, as the use of the light emitting device is diversified, the size of the light emitting device is also increased, so that the light transmittance of the cured product is lowered as the stress due to curing shrinkage remains after curing, and in some cases, depending on the external temperature change. There is a problem of cracking.

In addition, in the case of the light emitting device, in addition to the basic requirements mentioned above, it is possible to improve the heat resistance that can be tolerated in the process of depositing lead bath for the connection of the lead wire of the light emitting device, and to prevent the occurrence of cracks and to reduce the luminance deterioration due to the internal stress. Stressing is required, and there is a demand for no deterioration of transparency even for long time use.

As a conventional technique for meeting these demands, Japanese Laid-Open Patent Publication No. 57-71155 discloses a composition mainly composed of bisphenol-A type epoxy resin and an acid anhydride-based curing agent, and Japanese Laid-Open Patent Publication No. 51-26999 Although a method of using diaza bicyclo alkenes and salts thereof as a curing accelerator is known, there is a problem in that it is not sufficient to maintain stress at low stress and high temperature.

Conventional bisphenol A type epoxy resin used as the main component of epoxy resin composition for light emitting device is epoxy equivalent 180 ~ 200, which is advantageous in heat resistance of hardened product and workability due to low viscosity, but due to residual stress due to shrinkage during curing In order to improve this problem, it is recommended to use a high molecular weight epoxy resin which is excellent in heat resistance and crack resistance and can improve adhesion and adhesion. The sex is very poor.

Accordingly, in the present invention, a main component is prepared by mixing a high molecular weight epoxy resin, bisphenol A, an alicyclic epoxy resin, and dibutyl phthalate, having an epoxy equivalent of 250 to 500, and using a hardener having no double bond in an acid anhydride type curing agent. In addition, known diazabicyclo alkenes and salts or mixtures thereof are known as curing accelerators to reduce high molecular weight epoxy efficiency without deterioration of workability.

Specifically, the (1) bisphenol A epoxy epoxy which can be used in the present invention is a known compound prepared by the reaction of ordinary bisphenol A with epichlorohydrin, and an equivalent weight of 250 to 500 is appropriate. The smaller the amount of monomer, the better. The amount of use is suitably in the range of 50 to 75% by weight of the main component. (2) Bisphenol A is suitable to be used in the range of 5 to 15% by weight of the total main ingredient, which is incorporated into the main ingredient and reacts upon curing while suppressing the decrease in workability without significantly affecting the initial mixing viscosity. It can give a high molecular weight epoxy effect. (3) As the alicyclic epoxy resin, 3,4-cyclohexylmethyl (3,4-epoxy) cyclohexyl carboxylate is used, which is used for the purpose of lowering the viscosity of the main ingredient and improving the heat resistance. The range of 15-35 weight% of a main component is suitable. When the amount of alicyclic epoxy resin is 15% by weight or less, the heat resistance improvement is insufficient, and when 35% by weight or more, the crack resistance is insufficient. (4) The dibutyl phthalate is suitably used in an amount of 5 to 20% by weight based on the total amount of main components, which is used for the purpose of improving adhesion and lowering viscosity.

As a hardening | curing agent, in order to prevent the fall of transparency in an acid anhydride type hardening | curing agent, what does not have a double defect is used, In particular, hexahydrophthalic anhydride, methylhexahydrophdalic anhydride, or a mixture thereof is useful. The amount of the anhydride equivalent of 0.7 to 1.3 is most advantageous in terms of the balance between mechanical properties, heat resistance and crack resistance with respect to epoxy equivalent 1 of the main component.

Diaza bicyclo, which is used as a curing accelerator, is 1,5-diaza-bicyclo (4,2,0) octene-5,1,8-diaza-bicyclo, [7,2,0]. Sen-8, 1,4-diaza-bicyclo [4,3,0] nonen-5,1,8-diaza-bicyclo [7,3,0] dodecene-8,1,7-dia Za-bicyclo [4,3,0] nonene-6,1,5-diaza-bicyclo [7,4,0] dodecene-8,1,8-diaza-bicyclo [5,3, 0] decene-7, 1,8-diaza-bicyclo [5,4,0] undecene-7, 1,6-diaza-bicyclo [5,5,0] dodecene-6, 1, 7-diaza-bicyclo [6,5,0] dodecene-7,1,8-diaza-bicyclo [7,5,0] tetradecene-8,1,10-diaza-bicyclo 7,3,0] dodecene-9,1,10-diaza-bicyclo [7.4.0] dodecene-9,1,14-diaza-bicyclo, [11,4,0] heptadecene-13 These salts include, but are not limited to, salts such as straight-chain aliphatic acids such as acetic acid, freonic acid, capronic acid, stearic acid, linoleic acid, acrylic acid, oleic acid and attic acid, unsaturated fatty acids and dibasic fatty acids. There.

As for the addition amount of this hardening accelerator, the range of 0.5-5 weight part is most suitable with respect to 100 weight part of said main components.

In addition, a suitable epoxy resin composition for a light emitting device by blending an appropriate amount of an organophosphate ester compound when the curing agent is mixed in order to prevent color change due to a long heat treatment and to prevent a decrease in luminance due to low stress and to improve crack resistance. It may also be prepared. The addition amount of 0.5-15 weight part is suitable with respect to 100 weight part of main components.

In order to prepare the composition of the present invention, a conventional method for producing a liquid epoxy resin composition is applied.

In addition, pigments, dyes, light dispersants and the like may be added to the composition of the present invention depending on the end use of the cured product.

In order to obtain a cured product using the resin composition of the present invention may vary depending on the shape and size of the molded article, generally after curing 2 to 6 hours at 110 ~ 125 ℃ after 5 to 15 hours at 85 ~ 120 ℃ Desired hardened | cured material can be obtained.

In the following examples, the application method and the effect of the present invention will be described in detail.

However, the following examples do not limit the scope of the present invention.

EXAMPLE

Each formulation was mixed at room temperature by the blending of Table 1 to prepare an epoxy resin composition. The composition thus prepared was first cured at 120 ° C. for 2 hours and then secondary cured at 100 ° C. for 6 hours to obtain the following matters. The evaluation is shown in Table 2 below.

At the time of the mixing, 1,8-diaza-bacciclo [5,4,0] undecene-7 was added at a ratio of 2.0 parts by weight based on 100 parts by weight of the main component as a curing accelerator.

[Evaluation of Hardened Materials]

(1) Failure rate under high temperature, high humidity test

The number of prototypes that failed in personality current after 1000 hours of manufacturing light emitting devices and processing them for 1000 hours at 80 ℃ and 95% relative humidity.

(2) light transmittance after heat treatment

For each composition, a cured product having a thickness of 2 mm was prepared and processed at 120 ° C. for 1000 hours, and then the light transmittance at 800 nm was measured.

(3) Failure rate at the time of nap tank processing

The light emitting device encapsulated with each composition was treated for 10 seconds in a lead bath at 300 ° C., and the number of malfunctioning products among 100 prototypes was displayed.

(4) crack resistance

The light emitting device encapsulated with each composition was manufactured and then repeated 100 times at -30 ° C. for 30 minutes at 125 ° C. for 100 minutes to display the number of defective products in 100 test products.

TABLE 1

TABLE 2

Claims (4)

(A) 50 to 75% by weight of epoxy equivalent of 250 to 500 bisphenol A epoxy resin, (B) 5 to 15% by weight of bisphenol A, (C) 15 to 35% by weight of alicyclic epoxy resin, (D) dibutyl phthalate It is composed of a compound which does not have a double bond in the molecular structure in the acid anhydride type curing agent as a curing agent in the main component composed of 5 to 20% by weight, and a curing accelerator comprising diaza-bicyclo alkenes and salts thereof or mixtures thereof. An epoxy resin composition for light emitting elements. The epoxy resin composition for a light emitting device according to claim 1, wherein the alicyclic epoxy resin is 3,4-cyclohexylmethyl (3,4-epoxy) cyclohexyl carboxylate. The method according to claim 1, wherein the curing agent is hexahydro phthalic anhydride, metal hexahydro phthalic anhydride or a mixture thereof, and the amount used is an anhydride equivalent of 0.7 to 1.3 with respect to epoxy equivalent 1 of the main component. An epoxy resin composition for light emitting elements. The epoxy resin composition for a light emitting device according to claim 1, wherein the amount of the curing accelerator is 0.5 to 5 parts by weight based on 100 parts by weight of the main component.