JP5522043B2 - Epoxy resin curing agent, epoxy resin composition, cured product thereof, and optical semiconductor device - Google Patents

Description

  The present invention relates to an epoxy resin curing agent, an epoxy resin composition, a cured product thereof, and an optical semiconductor device. More specifically, the present invention relates to an epoxy resin curing agent, an epoxy resin composition, a cured product thereof, and an optical semiconductor device that give a cured product with little coloring and excellent crack resistance and transparency.

  Generally, epoxy resin cured products obtained from acid anhydrides and epoxy resins are inexpensive and have excellent transparency, electrical insulation, chemical resistance, moisture resistance, adhesiveness, etc., electrical insulation materials, semiconductor materials, adhesives It is used in various applications such as materials and paint materials. As a typical use example, a sealing material for protecting a light emitting element of a light emitting diode (hereinafter abbreviated as LED) can be given. In recent years, as white LEDs that combine a light source that emits light of a short wavelength and a phosphor have become widespread, degradation of the sealing material has become a problem.

  That is, in the case of a white LED, since a higher energy light source is used, there is a problem that the sealing material is degraded and easily colored as compared with a conventional red or green LED, and the life of the LED is shortened. . In addition, as the size of the light emitting element is improved and the current is increased, the heat generated when the LED is lit for a long time is increased, which also causes deterioration of the sealing material.

  Suppressing such deterioration due to light and heat is an important issue in the further spread of epoxy resins. As a method for solving this problem, there has been proposed an epoxy resin composition using an alicyclic epoxy resin in place of an aromatic epoxy resin that is easily deteriorated by light or heat (see, for example, Patent Documents 1, 2, and 3). ).

  On the other hand, an epoxy resin composition using such an alicyclic epoxy resin has a drawback that the obtained cured product has poor toughness and is liable to crack due to changes in conditions such as temperature. In order to solve this problem, as a method for toughening a cured product obtained from an epoxy resin composition, a method using a modifier composed of various polymers is known. For example, a method for improving toughness without impairing the transparency of a cured product by adding a polyester resin to an epoxy resin composition has been proposed (see, for example, Patent Document 4).

  However, since a polyester resin generally tends to be colored at the time of condensation, in the invention described in Patent Document 4, the cured product is markedly colored from yellow to brown as shown in the examples. For this reason, there has been a practical problem in applications that are required to be colorless and transparent, such as the LED sealing material.

  In order to solve such a problem, a method of adding a dendritic polymer has been proposed (see, for example, Patent Document 5).

JP 2000-196151 A JP 2003-012896 A JP 2003-221490 A JP 2004-131553 A JP 2007-314740 A

  However, the method of adding the dendritic polymer has a problem that it is difficult to handle because the viscosity after mixing tends to be high and the strength of the cured product tends to be poor. Thereby, it was not suitable especially when fine processing and surface smoothness were required for sealing of LED.

  The present invention has been made in view of the above problems, and can cure both low viscosity after mixing and strength after curing, and is cured with an epoxy resin that provides a cured product with little coloration and excellent crack resistance and transparency. An agent is provided. The present invention also provides a low-viscosity epoxy resin composition, a cured product and an optical semiconductor device that are less colored and excellent in crack resistance and transparency.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have achieved low viscosity by using an epoxy resin curing agent in which a specific dendritic polymer is added and mixed as a modifier to the polycarboxylic anhydride. The present inventors have found that an epoxy resin composition that is easy to handle and a cured product that is less colored and that is excellent in strength, crack resistance and transparency can be easily obtained.

  The present invention relates to the following [1] to [15].

[1] An epoxy resin curing agent comprising a polyvalent carboxylic acid anhydride and a dendritic polymer having a hydroxyl value of 550 mgKOH / g or less.

[2] The epoxy resin curing agent according to [1], wherein the dendritic polymer has a weight average molecular weight of 2000 or less.

[3] The epoxy resin curing agent according to [1] or [2], wherein the dendritic polymer has a viscosity of 10 Pa · s (25 ° C.) or less.

[4] The epoxy resin curing agent according to any one of [1] to [3], wherein the polyvalent carboxylic acid anhydride is a compound represented by the following general formula (1).

(Wherein R _{1 to} R ₄ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and two selected from R _{1 to} R ₄ are bonded to form a ring. It may be formed.)
[5] The epoxy resin curing agent according to any one of [1] to [4], wherein the dendritic polymer is polyester.

[6] The epoxy resin curing agent according to any one of [1] to [5], wherein the dendritic polymer is contained in an amount of 1 to 60 parts by weight with respect to 100 parts by weight of the polyvalent carboxylic acid anhydride.

[7] An epoxy resin composition comprising an epoxy resin and the epoxy resin curing agent according to any one of [1] to [6].

[8] An epoxy resin composition comprising an epoxy resin, a polyvalent carboxylic acid anhydride, and a dendritic polymer having a hydroxyl value of 550 mgKOH / g or less.

[9] The epoxy resin composition according to [8], wherein the dendritic polymer has a weight average molecular weight of 2000 or less.

[10] The epoxy resin composition according to [8] or [9], wherein the dendritic polymer has a viscosity of 10 Pa · s (25 ° C.) or less.

[11] The epoxy resin composition according to any one of [8] to [10], wherein the polyvalent carboxylic acid anhydride is a compound represented by the following general formula (1).

(Wherein R _{1 to} R ₄ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and two selected from R _{1 to} R ₄ are bonded to form a ring. It may be formed.)
[12] The epoxy resin composition according to any one of [8] to [11], wherein the dendritic polymer is polyester.

[13] The epoxy resin composition according to any one of [8] to [12], wherein the dendritic polymer is contained in an amount of 1 to 60 parts by weight per 100 parts by weight of the polyvalent carboxylic acid anhydride.

[14] A cured product obtained by curing the epoxy resin composition according to any one of [7] to [13].

[15] An optical semiconductor device in which an optical semiconductor element is sealed with the cured product according to [14].

  The disclosure of the present invention relates to the subject matter described in Japanese Patent Application No. 2008-194808 filed on July 29, 2008 and Japanese Patent Application No. 2009-127596 filed on May 27, 2009. These disclosures are incorporated herein by reference.

  According to the present invention, it is possible to obtain an epoxy resin curing agent that provides an epoxy resin composition that has low viscosity after mixing and is easy to handle and that has a cured product with good strength. A cured product having excellent transparency can be obtained.

  Hereinafter, the present invention will be described in detail.

  The polycarboxylic acid anhydride used in the present invention is not particularly limited. For example, succinic anhydride, maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, itaconic anhydride Examples include acid, pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, and the like. Two or more of these may be used in combination.

  In order for the cured product obtained by the present invention to exhibit the effects of less coloring and excellent crack resistance and transparency, the polyvalent carboxylic acid anhydride is represented by the general formula (1). A compound is preferred.

  Examples of such compounds include hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylendomethylenehexahydrophthalic anhydride, and the like. Two or more of these may be used in combination.

  The amount of polyvalent carboxylic acid anhydride used is preferably such that the acid anhydride group is 0.8-1 equivalent to 1 equivalent of epoxy group in the epoxy resin, and is 0.9-1 equivalent. It is more preferable to blend so that. When the acid anhydride group is 0.8 equivalent or more, curing is sufficient, and there is no possibility that the mechanical properties of the cured product are significantly deteriorated. In addition, when the acid anhydride group is 1 equivalent or less, a decrease in mechanical properties of the cured product can be similarly avoided.

  The dendritic polymer used in the present invention has a hydroxyl value of 550 mgKOH / g or less, preferably a hydroxyl value of 400 to 500 mgKOH / g. If it is 550 mgKOH / g or less, it can prevent becoming high viscosity.

  In view of problems such as high viscosity and a decrease in transparency, the weight average molecular weight is preferably 2000 or less, more preferably 1000 to 2000.

  Furthermore, it is preferable to use a dendritic polymer having a viscosity of 10 Pa · s (25 ° C.), more preferably 1 to 10 Pa · s (25 ° C.).

  The effect that the resin composition obtained by the present invention is low in viscosity and easy to handle, and the effect of being excellent in strength and transparency such as crack resistance and the like, which are characteristic of the obtained cured product, are less colored. In order to exhibit it, the dendritic polymer is preferably a polyester. Further, it is more preferably a polyester in which at least one dihydroxy monocarboxylic acid of 1 to 50 generations, preferably 1 to 10 generations, is added to a nucleus having at least one reactive epoxy group or hydroxyl group.

  Preferred nuclei include alcohols such as neopentyl glycol, trimethylolpropane, pentaerythritol, 2-butyl-2-ethyl-1,3-propanediol, epoxides such as glycidyl esters of monocarboxylic acids, glycidyl ethers of monoalcohols, etc. And the like.

  Examples of the dihydroxy monocarboxylic acid include 2,2-bis (hydroxymethyl) propionic acid and 2,2-bis (hydroxymethyl) butanoic acid. There is no restriction | limiting in particular in the manufacturing method of the dendritic polymer used for this invention, A well-known method is applicable.

  In the present invention, the dendritic polymer is preferably contained in an amount of 1 to 60 parts by weight, more preferably 10 to 50 parts by weight, based on 100 parts by weight of the polyvalent carboxylic acid anhydride. When the content of the dendritic polymer is 1 part by weight or more, the toughness of the obtained cured product is sufficient, and there is no possibility that the crack resistance is lowered. Further, when the content of the dendritic polymer is 60 parts by weight or less, it is easy to handle without high viscosity, and there is no fear that the glass transition temperature of the obtained cured product is remarkably lowered, which is preferable in practical use.

  Although there is no restriction | limiting in particular in the epoxy resin used for this invention, An alicyclic epoxy resin is preferable from the surface of light resistance and heat resistance. The alicyclic epoxy resin has an alicyclic skeleton and two or more epoxy groups in one molecule. For example, 3 ', 4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis ( 3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene dioxide, hydrogenated bisphenol A diglycidyl ether, and the like. Two or more of these may be used in combination.

  Further, an epoxy resin other than the alicyclic epoxy resin can also be used depending on the purpose. Examples of such epoxy resins include bisphenol type epoxy resins obtained by reaction of bisphenols such as bisphenol A and bisphenol S with epichlorohydrin, and phenol novolak types obtained by reaction of phenol novolac and epichlorohydrin. Examples thereof include an epoxy resin, a glycidyl ester type epoxy resin obtained by a reaction between a polyvalent carboxylic acid and epichlorohydrin. Two or more of these may be used in combination.

  The amount of the epoxy resin other than these alicyclic epoxy resins is preferably 0 to 80 parts by weight, more preferably 0 to 20 parts by weight with respect to 100 parts by weight of the alicyclic epoxy resin. If the usage-amount of epoxy resins other than an alicyclic epoxy resin is 80 weight part or less, it can prevent that the light resistance and heat resistance of hardened | cured material fall.

  In the present invention, a target epoxy resin curing agent can be obtained by mixing a polyvalent carboxylic acid anhydride and a dendritic polymer, but the production method is not particularly limited, and a known method is applied. can do. Furthermore, the epoxy resin composition can be obtained by mixing the epoxy resin curing agent and the epoxy resin, but the production method is not particularly limited, and known methods can be applied. In addition, an epoxy resin composition can be obtained by separately mixing a dendritic polymer and a polyvalent carboxylic acid anhydride with an epoxy resin.

  In the epoxy resin composition of the present invention, a curing accelerator can be appropriately added depending on the purpose. Examples of the curing accelerator include imidazoles such as 2-ethyl-4-methylimidazole and 1-methylimidazole, tertiary amines such as benzyldimethylamine and N, N-dimethylaniline, tetramethylammonium chloride, and benzyltriethylammonium chloride. Quaternary ammonium salts such as tetra-n-butylphosphonium o, o-diethyl phosphorodithionate, phosphonium salts such as tetrabutylphosphonium benzotriazolate, metal salts such as zinc octylate and zinc stearate, zinc acetylacetone, Examples thereof include metal complexes such as benzoylacetone zinc.

  When the curing accelerator is used, the amount of the epoxy resin composition is preferably 0.01 to 8% by weight, more preferably 0.1 to 5% by weight. A sufficient effect is obtained when the blending amount of the curing accelerator is 0.01% by weight or more. Moreover, when the compounding quantity of a hardening accelerator is 8 weight% or less, it can reduce that the hardened | cured material obtained is colored or heat resistance falls.

  Various additives can be further added to the epoxy resin composition according to the present invention depending on the purpose within a range that does not impair the properties of the resulting cured product. Examples of the additive include a flexibilizer, a heat stabilizer, an ultraviolet absorber, a flame retardant, an antistatic agent, an antifoaming agent, a thixotropic agent, and a release agent. Furthermore, for example, an antioxidant for further improving the light resistance and heat resistance of the cured product, a chain transfer agent for controlling the polymerization reaction during curing, and improving the mechanical properties, adhesiveness, and handleability of the cured product. Fillers, plasticizers, stress reducing agents, coupling agents, dyes, light scattering agents and the like.

  By curing the epoxy resin composition in the present invention with heat, a cured product with little coloration and excellent crack resistance and transparency can be obtained. There is no restriction | limiting in particular in the manufacturing method of hardened | cured material, A well-known method is applicable. Although the temperature and time of heat-curing are not specifically limited, 90-180 degreeC and 1-12 hours are preferable. The LED light-emitting element or the like can be sealed by providing the epoxy resin composition on the surface of the LED light-emitting element or the like by a method such as coating, potting, or impregnation, followed by heat curing.

  The optical semiconductor device of the present invention is an optical semiconductor element such as an LED light emitting element or a photodiode element sealed with the above cured product, has little coloring, is excellent in crack resistance and transparency, and further has light resistance and It also has excellent heat resistance.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited by these examples.

Example 1
Polyester dendritic polymer (hydroxyl value 470 mg KOH / g, weight average molecular weight 1800, viscosity 7.6 Pa · s (25 ° C.), BOLTORN P-1000: trade name manufactured by Perstorp) 20 parts by weight, polycarboxylic anhydride 116 parts by weight of 4-methylhexahydrophthalic anhydride (HN-7000: manufactured by Hitachi Chemical Co., Ltd./acid anhydride equivalent 168 (g / eq)) as a product, heated to 70 ° C. and stirred, uniformly It was made to melt | dissolve until it became epoxy resin hardening | curing agent (I).

  3 ', 4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Celoxide 2021P: Daicel Chemical Industries, Ltd. trade name / epoxy equivalent) as an epoxy resin with respect to 136 parts by weight of the epoxy resin curing agent (I) 138 (g / eq)) 100 parts by weight, tetra-n-butylphosphonium o, o-diethyl phosphorodithionate (Hishicolin PX-4ET: trade name, manufactured by Nippon Chemical Industry Co., Ltd.) as a curing accelerator, stable Add 1 part by weight of 9,10-dihydro-9-phospha-10-oxaphenanthrene-9-oxide (HCA: manufactured by Sanko Chemical Co., Ltd.) as an agent, heat to 80 ° C., and stir until uniform. It was made to melt | dissolve and epoxy resin composition (I) was obtained.

  Next, after sufficiently defoaming the epoxy resin composition (I) under reduced pressure, a part of (a) is gently poured into a metal petri dish with a metal clip placed in the center, and the rest (b) ) It was poured into a plate-shaped mold, heated at 120 ° C. for 1 hour, and further heated at 150 ° C. for 4 hours to obtain two types of cured products (I).

(Example 2)
An epoxy resin curing agent (II) was obtained in the same manner as in Example 1 except that 40 parts by weight of the polyester dendritic polymer was used instead of 20 parts by weight.

  An epoxy resin composition (II) was obtained in the same manner as in Example 1 except that 156 parts by weight of the epoxy resin curing agent (II) was used instead of the epoxy resin curing agent (I). Further, a cured product (II) was obtained in the same manner as in Example 1.

(Example 3)
As polyvalent carboxylic acid anhydride, a mixture of 3-methylhexahydrophthalic anhydride and 4-methylhexahydrophthalic anhydride (hereinafter referred to as 3 & 4-methylhexahydrophthalic anhydride. HN-5500E: Hitachi Chemical Co., Ltd. Product / acid anhydride equivalent 168 (g / eq)) Except for using 116 parts by weight, an epoxy resin curing agent (III) was obtained in the same manner as in Example 1.

  In the same manner as in Example 1, an epoxy resin composition (III) was obtained from the epoxy resin curing agent (III). Further, a cured product (III) was obtained in the same manner as in Example 1.

Example 4
An epoxy resin curing agent (IV) was obtained in the same manner as in Example 3 except that 40 parts by weight of the polyester dendritic polymer was used instead of 20 parts by weight.

  An epoxy resin composition (IV) was obtained in the same manner as in Example 1 except that 156 parts by weight of the epoxy resin curing agent (IV) was used instead of the epoxy resin curing agent (I). Further, a cured product (IV) was obtained in the same manner as in Example 1.

(Comparative Example 1)
Except for using 20 parts by weight of a polyester dendritic polymer (hydroxyl value 600 mg KOH / g, weight average molecular weight 1800, viscosity 32.8 Pa · s (25 ° C.), BOLTORN P-500: product name of Perstorp) as the dendritic polymer. Obtained an epoxy resin curing agent (V) in the same manner as in Example 1.

  From the epoxy resin curing agent (V), an epoxy resin composition (V) was obtained in the same manner as in Example 1. Further, a cured product (V) was obtained in the same manner as in Example 1.

(Comparative Example 2)
An epoxy resin curing agent (VI) was obtained in the same manner as in Comparative Example 1 except that 40 parts by weight of the polyester dendritic polymer was used instead of 20 parts by weight.

  An epoxy resin composition (VI) was obtained in the same manner as in Example 1 except that 156 parts by weight of the epoxy resin curing agent (VI) was used instead of the epoxy resin curing agent (I). Further, a cured product (VI) was obtained in the same manner as in Example 1.

(Comparative Example 3)
The epoxy resin composition (VII) was used in the same manner as in Example 1 except that the polyester dendritic polymer was not used and 116 parts by weight of 4-methylhexahydrophthalic anhydride was used instead of the epoxy resin curing agent (I). )

  A cured product (VII) was obtained from the epoxy resin composition (VII) in the same manner as in Example 1.

  Hue and viscosity of epoxy resin compositions (I) to (VII) obtained in Examples 1 to 4 and Comparative Examples 1 to 3, appearance of cured products (I) to (VII), cracks, glass transition temperature, bending strength The bending elastic modulus was evaluated, and the results are shown in Tables 1 and 2. Of the cured products, (a) was used for crack evaluation, and (b) was used for the evaluation of other cured products. The characteristic evaluation methods in Tables 1 and 2 are as follows.

-Hue: Visually compared with APHA standard solution.

Viscosity: Measured with an E-type viscometer at 25 ° C.

Appearance: The cured product (b) was visually determined.

Crack: The cured product (a) having two samples was allowed to stand at −30 ° C. for 20 hours and then allowed to stand at room temperature (25 ° C.) for 10 hours, and the presence or absence of cracks was visually confirmed.

○: No crack
×: One or more cracks in the sample. Glass transition temperature: A 2 mm × 5 mm × 5 mm sample was cut out from the cured product (b) and measured by mechanical thermal analysis (TMA).

Measuring device SSC-5200 (Seiko Electronics Co., Ltd.)
Measurement conditions: Load 20 g / minute 10 ° C. Heating / bending strength: Measured according to JIS (Japanese Industrial Standard) standard number K7171.

-Flexural modulus: measured in accordance with the above JIS K7171.

  As shown in Tables 1 and 2, the resin compositions obtained in Examples 1 to 4 have both low viscosity and bending strength, and the cured product is colorless and transparent without cracks. I understood. On the other hand, Comparative Example 1 has a relatively low viscosity due to a small amount of the dendritic polymer, but has a poor bending strength. In Comparative Example 2, the bending strength increased with an increase in the amount of the dendritic polymer added, but the viscosity became very high, and the cured product was colored yellow. In the cured product of Comparative Example 3, cracks occurred and the bending strength was low, and the cured product was colored yellow.

  According to the present invention, it was possible to obtain an epoxy resin composition having a low viscosity and easy handling, and a cured product excellent in crack resistance and transparency, having high strength and little coloring.

Industrial applicability

  According to the present invention, it is possible to obtain an epoxy resin curing agent that provides an epoxy resin composition that has low viscosity after mixing and is easy to handle and that has a cured product with good strength. A cured product having excellent transparency can be obtained.

Claims (13)

A polyvalent carboxylic acid anhydride and a dendritic polymer which is a polyester having a hydroxyl value of 550 mgKOH / g or less and at least one dihydroxymonocarboxylic acid added to a nucleus having at least one reactive epoxy group or hydroxyl group Epoxy resin curing agent containing.   The epoxy resin curing agent according to claim 1, wherein the dendritic polymer has a weight average molecular weight of 2000 or less.   The epoxy resin curing agent according to claim 1 or 2, wherein the dendritic polymer has a viscosity of 10 Pa · s (25 ° C) or less. The epoxy resin curing agent according to any one of claims 1 to 3, wherein the polyvalent carboxylic acid anhydride is a compound represented by the following general formula (1).

(Wherein R _{1 to} R ₄ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and two selected from R _{1 to} R ₄ are bonded to form a ring. It may be formed.) The epoxy resin curing agent according to any one of claims 1 to 4 , wherein the dendritic polymer is contained in an amount of 1 to 60 parts by weight based on 100 parts by weight of the polyvalent carboxylic acid anhydride. The epoxy resin composition containing an epoxy resin and the epoxy resin hardening | curing agent in any one of Claims 1-5 . An epoxy resin, a polyvalent carboxylic acid anhydride , and a dendron which is a polyester having a hydroxyl value of 550 mgKOH / g or less and at least one dihydroxymonocarboxylic acid added to a nucleus having at least one reactive epoxy group or hydroxyl group Epoxy resin composition comprising a glassy polymer. The epoxy resin composition according to claim 7 , wherein the dendritic polymer has a weight average molecular weight of 2000 or less. The epoxy resin composition according to claim 7 or 8, wherein the dendritic polymer has a viscosity of 10 Pa · s (25 ° C) or less. The epoxy resin composition according to any one of claims 7 to 9 , wherein the polyvalent carboxylic acid anhydride is a compound represented by the following general formula (1).

(Wherein R _{1 to} R ₄ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and two selected from R _{1 to} R ₄ are bonded to form a ring. It may be formed.) The epoxy resin composition according to any one of claims 7 to 10 , wherein the dendritic polymer is contained in an amount of 1 to 60 parts by weight with respect to 100 parts by weight of the polyvalent carboxylic acid anhydride. A cured product obtained by curing the epoxy resin composition according to any one of claims 6-11. An optical semiconductor device comprising an optical semiconductor element sealed with the cured product according to claim 12 .