JP2005320383A - Epoxy resin-curing agent and epoxy resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin-curing agent composition which gives an epoxy resin excellent in heat resistance, toughness and transparency. <P>SOLUTION: The epoxy resin composition comprises an epoxy resin bearing at least two epoxy groups in one molecule and the epoxy resin-curing agent comprising a tetracarboxylic dianhydride compound having a tricyclic structure obtained from 1,1-diphenyl ethylene and maleic anhydride. A sealing agent for a light emitting diode comprising the epoxy resin composition is also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel epoxy resin curing agent and an epoxy resin composition containing the curing agent.

Epoxy resins (cured products) are excellent in heat resistance, adhesion, water resistance, mechanical strength, electrical properties, etc., so adhesives, laminates, impregnations, paints, materials for civil engineering and construction, electrical / electronic Widely used in the field of parts.
Conventionally, acid anhydride compounds have been used as curing agents mainly in electronic and electrical equipment. The acid anhydride curing agents are roughly classified into aliphatic, alicyclic, aromatic, and halogen types (see, for example, Non-Patent Document 1).
In particular, in recent years, in the electric and electronic fields, there has been an increasing demand for heat resistance and toughness (particularly, reduction of residual stress evaluated by heat cycle resistance) and deterioration resistance (light transmittance in the ultraviolet region) for high-intensity LED light sources. Therefore, an epoxy resin curing agent made of an alicyclic tetracarboxylic dianhydride compound excellent in solubility in an epoxy resin and an organic solvent has attracted attention.

Methylcyclohexene tetracarboxylic dianhydride (MCTC) is known as an alicyclic tetracarboxylic dianhydride-based epoxy resin curing agent. This compound has a melting point of 167 ° C. and has limited heat resistance. In addition, after the Diels-Alder reaction of 1 mol of maleic anhydride and 1 mol of piperylene, a two-step process of ene reaction between the product and 1 mol of maleic anhydride is required (for example, Patent Document 1). reference). The alicyclic tetracarboxylic dianhydride type epoxy resin curing agent obtained from maleic anhydride and α-methylstyrene (for example, see Patent Document 2) has the same problem.
"Epoxy Resin Handbook", edited by Masaki Shinbo (published in Nikkan Kogyo Shimbun, 1987), pages 179-210 JP-A-55-36406 Japanese Patent Laid-Open No. 62-212419

  The present invention is an epoxy resin curing agent comprising an alicyclic tetracarboxylic dianhydride that is easy to manufacture and has excellent solubility and heat resistance in an epoxy resin and an organic solvent, and an epoxy resin composition containing the curing agent The purpose is to provide goods.

  As a result of intensive studies to solve the above problems, the present inventors have found that a novel epoxy resin curing agent that has overcome the above problems can be obtained by using a tetracarboxylic dianhydride having a specific tricyclo ring structure. It discovered that the epoxy resin composition containing the said hardening | curing agent was obtained, and completed this invention.

The first of the present invention is an epoxy resin curing agent containing at least one of tetracarboxylic dianhydrides represented by general formulas (1), (2), and (3).

  In general formula (1)-(3), R1 represents a hydrogen atom or a C1-C10 alkyl group, and R1 may be same or different, respectively. R2 represents an alkyl group having 1 to 10 carbon atoms. m and n are arbitrary integers from 0 to 5 independent of each other, and when m + n is plural, plural R2s may be the same or different from each other.

  2nd of this invention is an epoxy resin composition characterized by mix | blending the 1st epoxy resin hardening | curing agent of this invention.

  A third aspect of the present invention is a light-emitting diode encapsulant comprising the second epoxy resin composition of the present invention.

4th of this invention is the tetracarboxylic dianhydride represented by General formula (2).

  In General formula (2), R1 represents a hydrogen atom or a C1-C10 alkyl group, and R1 may be same or different, respectively. R2 represents an alkyl group having 1 to 10 carbon atoms. m and n are arbitrary integers from 0 to 5 independent of each other, and when m + n is plural, plural R2s may be the same or different from each other.

5th of this invention is the tetracarboxylic dianhydride represented by General formula (3).

  In General formula (3), R1 represents a hydrogen atom or a C1-C10 alkyl group, and R1 may be same or different, respectively. R2 represents an alkyl group having 1 to 10 carbon atoms. m and n are arbitrary integers from 0 to 5 independent of each other, and when m + n is plural, plural R2s may be the same or different from each other.

The epoxy resin curing agent containing at least one of the tetracarboxylic dianhydrides represented by the general formulas (1), (2), and (3) according to the present invention is derived from its specific chemical structure and cured. The following excellent properties are exhibited as the agent itself and in the epoxy resin composition before and after the curing reaction.
(1) Since the basic structure is an alicyclic structure, and further has an aromatic ring as a substituent, it has excellent solubility in uncured epoxy resins and organic solvents, and is excellent in handleability before the curing reaction.
(2) Since the structure sandwiched between two carboxylic acid anhydride groups is a bicyclo type alicyclic structure, it has a higher melting point than conventional alicyclic tetracarboxylic dianhydride compounds and is cured with epoxy resin. Excellent heat resistance when used.
(3) Since the basic structure is asymmetric and further has a bulky aromatic ring as a substituent, the cured epoxy resin is given flexibility and toughness.
(4) Since the main structure is an alicyclic tricyclo structure, conjugation between aromatic epoxy resins is inhibited, and a highly transparent epoxy resin composition is obtained.
(5) Since purification by recrystallization is possible, it can be used as a high-purity crosslinking agent, and an epoxy resin composition having excellent optical properties can be obtained.

Hereinafter, the present invention will be described in detail.
The present invention is characterized in that a tetracarboxylic dianhydride compound represented by the general formulas (1), (2), and (3) is used as a curing agent for an epoxy resin.
The tetracarboxylic dianhydride represented by the general formula (1) is obtained by reacting 1 mol of the compound represented by the general formula (4) with 2 mol of the compound represented by the general formula (5). (See WNEmmerling et al, European Polymer Journal, Vol.13, p179.) Tetracarboxylic dianhydrides represented by general formulas (2) and (3) can be used to hydrogenate and reduce compounds of general formula (1). Obtained by.

  In the general formulas (4) and (5), R1 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R2 represents an alkyl group having 1 to 10 carbon atoms, and R3 represents a divalent organic group. m and n are arbitrary integers of 0 to 5 independent of each other. When m + n is plural, plural R2s may be the same or different from each other.

  Specific examples of the compound represented by the general formula (4) include 1,1-diphenylethylene, 1,1-di (methylphenyl) ethylene, 1-phenyl-1-methylphenylethylene, 1,1-diphenylpropene. 1,1-di (methylphenyl) propene, 1-phenyl-1-methylphenylpropene, and the like.

  Specific examples of the compound represented by the general formula (5) include maleic anhydride, citraconic anhydride (3-methylmaleic anhydride), 3-ethylmaleic anhydride, 3,4-dimethylmaleic anhydride, 3-chloro. Maleic anhydride, 3,4-dimethylmaleic anhydride, etc. are mentioned.

  1 mol of the compound of the general formula (4) and 2 mol of the compound of the general formula (5) react by the route shown in FIG. 1 to produce a tetracarboxylic dianhydride of the general formula (1) Conceivable. For the progress of the reaction, a catalyst is not particularly required, and it can be obtained by using a solvent as appropriate, mixing them and heating and stirring them. When the solvent is used, the reaction temperature is generally near the boiling point of the solvent, but can be performed at 50 to 200 ° C. More preferably, it is 60-150 degreeC. Although the reaction time is determined from the relationship with the reaction temperature, it is usually preferably in the range of 0.1 to 20 hours.

Hereinafter, the reaction route will be described with reference to FIG.
The compound of the general formula (4) and the general formula (5) forms a charge transfer complex by inducing the difference in the electron density of the carbon / carbon double bond.
Therefore, it is preferable that the substituents present in the compounds of the general formula (4) and the general formula (5) do not reduce the difference in electron density between the carbon and carbon double bonds of both. That is, it is not preferred that a substituent other than the aromatic ring in the compound of the general formula (4) has a strong electron-withdrawing substituent, and a strong electron-donating substituent is present in the carbon of the compound of the general formula (5). It is not preferable to exist. Furthermore, the presence of a substituent having a steric hindrance effect is also undesirable.

Therefore, it is preferable that at least one of R1 in the general formula (4) and R1 in the general formula (5) is a hydrogen atom. Further, when each of R1 and R2 is an alkyl group, it preferably has 10 or less carbon atoms, more preferably 5 or less carbon atoms, and particularly preferably a methyl group or a propyl group.
Moreover, about the compound of General formula (4), it is preferable to set it as m + n <= 4, and m + n <= 2 is especially preferable. Therefore, the most preferable compound represented by the general formula (4) is 1,1-diphenylethylene, and the most preferable compound represented by the general formula (5) is maleic anhydride.

  The charge transfer complex formed from the general formula (4) and the general formula (5) becomes a six-membered ring (cyclohexadiene ring) by an intramolecular cyclization reaction, and the cyclohexadiene part in the six-membered ring compound and the raw material compound It is considered that the carbon / carbon double bond portion of the general formula (5) forms the compound of the general formula (1) via the Diels-Alder reaction. Since the carbon / carbon double bond produced by the Diels-Alder may be decomposed by the reverse Diels-Alder reaction in a high temperature environment, hydrogenation is performed by a conventional method using a known reduction method, etc. The tetracarboxylic dianhydride represented by the general formula (2) as a saturated bond and the aromatic ring in the side chain are hydrogenated to obtain a tetracarboxylic dianhydride represented by the general formula (3).

In the catalytic reduction method, palladium, ruthenium, rhodium, platinum, nickel, cobalt, etc. are used as a metal catalyst, and the hydrogen pressure is in a range from normal pressure to 10 MPa (100 kg / cm 2) in a solvent, and the temperature is 0 to 150. It can be performed in the range of ° C.
More specifically, when the tetracarboxylic dianhydride represented by the general formula (2) is obtained in a high yield, the hydrogen pressure is set in the range of 1 MPa to 5 MPa in the presence of the palladium-based catalyst, and the temperature is set to room temperature to 50-50. It is better to perform catalytic reduction in the range of 5 ° C. for 5 to 20 hours. When the tetracarboxylic dianhydride represented by the general formula (3) is obtained with a high yield, the hydrogen pressure in the presence of a palladium catalyst is 5 MPa The catalytic reduction may be performed in the range of 8 MPa and the temperature in the range of 50 to 100 ° C for 5 to 20 hours.

  The tetracarboxylic dianhydrides represented by the general formulas (1), (2), and (3) have special reaction conditions compared to the tetracarboxylic dianhydrides used in conventional epoxy resin curing agents. It can be obtained in substantially one reaction operation without modification, and by a reaction under mild conditions as compared with an ene reaction or the like without generating a by-product. In particular, it exhibits extremely excellent properties as a production of a curing agent for an epoxy resin composition used in an optical functional member requiring high purity. Among these, the tetracarboxylic dianhydrides represented by the general formulas (2) and (3) do not have a reverse Diels-Alder reaction even in a high-temperature environment, so high heat resistance or long-term stability is required. It is excellent as a curing agent for epoxy resin compositions.

  In the tetracarboxylic dianhydride represented by the general formulas (1), (2), and (3) according to the present invention, two carboxylic dianhydride groups are arranged asymmetrically in a tricyclo ring structure. And a side chain (for example, a benzene ring if n = 0). The present inventors consider that the basic structure is greatly involved in imparting heat resistance, solubility in organic solvents, and toughness of the epoxy resin and the epoxy resin composition.

  In addition to the above basic characteristics, if you want better heat resistance and affinity with aromatic materials, tetracarboxylic dianhydride represented by general formula (2), better transparency and dissolution When desired, the tetracarboxylic dianhydride represented by the general formula (3) is used alone. However, when these properties are desired in a well-balanced manner, they may be mixed and used. In addition, the tetracarboxylic dianhydride represented by the general formula (1) may be used in combination when a chemical modification or a crosslinking reaction is desired, or when a thermal decomposition that does not leave a large amount of residue at 300 ° C. or higher is desired. preferable. In addition, in applications where LED sealants and the like are used at a wide range of temperatures for a long time and high transparency is required, the general formula is considered in consideration of the problem of acid value deterioration in addition to the problem of decomposability. It is preferable to use (2) or (3), particularly a tetracarboxylic dianhydride represented by the general formula (3).

  In order to obtain the epoxy resin composition according to the present invention, a ring-opening polyaddition reaction or a ring-closing reaction is carried out in the tetracarboxylic dianhydride represented by the general formulas (1), (2), and (3). It is preferable that it does not contain a substituent that causes steric hindrance with respect to the progress. Among general formulas (1), (2), and (3), tetracarboxylic dianhydride synthesized from 1,1-diphenylethylene and maleic anhydride Things are preferred.

When using an epoxy resin curing agent containing a tetracarboxylic dianhydride according to the present invention, it can be used as it is, in combination with another epoxy resin curing agent, or to constitute a normal epoxy resin curing agent composition It may be used as a curing agent composition by mixing with the above compound, or it may be used as a curing agent by obtaining a compound having a repeated imide structure obtained by reacting with a diamine compound in advance.
In order to obtain the effect according to the present invention, the general formulas (1), (2), (3) are used in both cases where only one type of epoxy curing agent is used and when two or more types are used. ) Is used at least 5% by mass, preferably 10% by mass or more, and more preferably 40% by mass or more. In addition, what is necessary is just to determine these usage methods and compounding ratio based on the characteristic of each compound as described in the said paragraph 0029. In addition, you may use the compound used for a well-known epoxy resin hardening | curing agent for the other hardening | curing agent.

  There is no restriction | limiting in particular in the epoxy resin used in this invention, What is necessary is just to have two or more epoxy groups per molecule. If it is an aromatic compound, glycidyl ethers, glycidyl esters, glycidyl amines, specific examples include, for example, epoxy compounds, phenol novolac resins or cresols made from bisphenol A or bisphenol F and epichlorohydrin. Examples thereof include polyglycidyl ethers of novolak resins. The corresponding commercially available products are “Epicoat 827”, “828”, “Epicoat 834”, “1001”, “1004”, “Epicoat 152”, “154”, “180S65”, and the like.

  The mixing ratio of the epoxy resin curing agent and the epoxy resin according to the present invention is (epoxy group in epoxy resin): ((acid anhydride group in tetracarboxylic dianhydride represented by general formula (1)) The molar equivalent ratio of + (functional group involved in the curing reaction of another curing agent) is in the range of 0.5 to 1.5 (hereinafter referred to as “functional group equivalent ratio”). When the epoxy resin composition is cured, the epoxy resin composition may be treated according to an ordinary method, and the temperature range may be selected in the range of 50 to 200 ° C., preferably 100 to 200 ° C., in balance with the time required for the curing reaction.

  In the curing reaction, a known curing accelerator may be added. In addition, the epoxy resin composition according to the present invention is a reactive diluent, a plasticizer, an inorganic filler such as silica, a flame retardant, a mold release agent, an antifoaming agent and an anti-settling agent as long as the effects of the present invention are not impaired. An agent, an antioxidant, a silane coupling agent, a dye, a pigment, a colorant and the like can be blended.

  EXAMPLES Hereinafter, although an Example is given and the content of this invention is demonstrated concretely, this invention is not limited to these.

<Synthesis of tetracarboxylic dianhydride>
Place 1,1-diphenylethylene 5.10 g and maleic anhydride 2.78 g (molar ratio 1: 1) into a 20 ml eggplant type flask, degas the dissolved oxygen for 10 minutes, and then keep the oil bath at 140 ° C. The mixture was heated and stirred for 5 hours. The temperature of the reaction system was 106 ° C. After completion of the reaction, toluene was added to the flask, and the deposited precipitate was collected by filtration. The weight of the filtrate was 3.65 g. In this example, 1,1-diphenylethylene is charged as a reaction raw material, and at the same time, the excess functions as a solvent. The yield of this example is 68% based on 2.51 g of 1,1-diphenylethylene and 2.78 g of maleic anhydride (molar ratio 1: 2).
(Melting point measurement by DSC analysis)
The compound recrystallized from ethyl acetate showed a clear endothermic peak at 290 ° C. under the temperature rising condition at 20 ° C./min.

<Determining the structure of tetracarboxylic dianhydride>
(Mass spectrum)
As a result of mass spectrum, the molecular weight of the product was 376.
(IR spectrum measurement)
700 cm-1 to 740 cm-1: 1 substituted aromatic attribute peak 760 cm-1 to 860 cm-1: carbon / carbon double bond attribute peak 1780 cm-1 to 1880 cm-1: carboxylic acid anhydride attribute peak (1H NMR spectrum measurement)
1H NMR spectrum (DMSO-d6)
2.55 (m, 2H), 2.75 (m, 2H): hydrogen on carbon adjacent to the carbonyl group 3.50 to 3.60 (m, 2H)
3.70 (t, 1H): hydrogen on carbon at the cyclohexene ring and cyclohexadiene ring bond 3.80 (m, 2H): methine hydrogen in cyclohexene 6.00 (t, 1H), 6.25 ( t, 1H): hydrogen in carbon-carbon double bond portion 7.20 (d, 2H), 7.35 (t, 1H), 7.45 (t, 2H): hydrogen in 1-substituted benzene portion From the results, the chemical structure of the product was confirmed to be a tetracarboxylic dianhydride represented by the following chemical formula (1) among the tetracarboxylic dianhydrides satisfying the structure of the general formula (1). . Regarding the structure determination of the compound, Non-Patent Document 1 was also referred to.

1 g of the above tetracarboxylic dianhydride represented by the chemical formula (1) is dissolved in 10 ml of THF, 100 mg of 10% palladium / carbon catalyst (manufactured by Kojima Pharmaceutical) is added, and 50 ° C., 5 to 4.50 MPa ( Hydrogen reduction was carried out for 16 hours. After removing the catalyst, THF was distilled under reduced pressure to recover white crystals in a yield of 95%.
When the ¹ HNMR spectrum of the crystal was measured in the same manner as described above, the peak area attributed to two hydrogen atoms of the carbon / carbon double bond portion appearing in the region of δ = 6.00 to 6.25 disappeared. It was shown that the carbon / carbon double bond (disubstituted olefin) at the 11th position in the chemical formula (1) was hydroreduced. On the other hand, at δ = 1.00 to 2.00, no cycloalkane-based methine hydrogen appeared, indicating that no aromatic ring nuclear hydrogenation occurred. There were no other major changes. Further, it was confirmed from IR spectrum analysis that an anhydrous carbonyl group remained, and from the results of mass spectrum, it was confirmed that the molecular weight was 378, which is 2 more than the compound of the chemical formula (6).
From this result, it was confirmed that the said reduction process compound is the tetracarboxylic dianhydride represented by Chemical formula (7) which satisfies the structure of General formula (2).

1 g of tetracarboxylic dianhydride represented by the chemical formula (1) is dissolved in 10 ml of THF, 50 mg of 10% palladium / carbon catalyst (manufactured by Kojima Pharmaceutical) is added, and 100 ° C., 1 to 0.95 MPa (hydrogen pressure) ) For 6 hours. After removing the catalyst, THF was distilled under reduced pressure to recover white crystals in a yield of 95%.
When the ¹ HNMR spectrum of the crystal was measured in the same manner as described above, the peak area attributed to two hydrogen atoms of the carbon / carbon double bond portion appearing in the region of δ = 6.00 to 6.25 and δ = The ratio of the peak area attributed to the five hydrogen atoms of the monosubstituted benzene ring portion appearing in the region of 7.20 to 7.45 changed from 2: 5 before the reduction treatment to 1.2: 5 In addition, a new methine hydrogen peak appeared near δ = 6.00, and a part of the carbon / carbon double bond (2-substituted olefin) at the 11th position in the chemical formula (1) was hydrogenated and reduced. showed that.
On the other hand, at δ = 1.00 to 2.00, no cycloalkane-based methine hydrogen appeared, indicating that no aromatic ring nuclear hydrogenation occurred. There were no other major changes. Further, it was confirmed from IR spectrum analysis that an anhydrous carbonyl group remained.
From this result, the reduction compound is composed of about 60 mol% of tetracarboxylic dianhydride represented by chemical formula (1) and about 40 mol% of tetracarboxylic dianhydride represented by chemical formula (2). It was confirmed that
Hereinafter, the compound obtained by this method is referred to as “hydrogenated tetracarboxylic dianhydride mixture A”.

1 g of the above tetracarboxylic dianhydride represented by the chemical formula (1) is dissolved in 10 ml of THF, 100 mg of 10% palladium / carbon catalyst (manufactured by Kojima Pharmaceutical) is added, 120 ° C., 9.00 to 8.80. Hydrogenation reduction was performed for 16 hours at 50 MPa (hydrogen pressure). After removing the catalyst, THF was distilled under reduced pressure to recover white crystals in a yield of 95%.
When the ¹ HNMR spectrum of the crystal was measured in the same manner as described above, a peak attributed to two hydrogen atoms of the carbon / carbon double bond portion appearing in the region of δ = 6.00 to 6.25 and δ = The peak attributed to the hydrogen atom of the aromatic ring appearing in the region of 7.20 to 7.00 disappears, and the carbon / carbon double bond (2-substituted olefin) at position 11 in chemical formula (1) is hydrogenated. And the aromatic ring was nuclear hydrogenated. On the other hand, cycloalkane methine hydrogen appeared at δ = 1.00 to 2.00. Further, it was confirmed from IR spectrum analysis that an anhydrous carbonyl group remained, and from the result of mass spectrum, it was confirmed that the molecular weight was 386, which is 8 more than the compound of the chemical formula (6).
From this result, it was confirmed that the said reduction process compound is the tetracarboxylic dianhydride represented by Chemical formula (3) which satisfies the structure of General formula (3).
The synthesis route of these alicyclic tetracarboxylic dianhydride compounds is shown in FIG.

1 g of tetracarboxylic dianhydride represented by the chemical formula (1) is dissolved in 10 ml of THF, 50 mg of 10% palladium / carbon catalyst (manufactured by Kojima Pharmaceutical) is added, and 100 ° C., 1 to 0.95 MPa (hydrogen pressure) ) For 6 hours. After removing the catalyst, THF was distilled under reduced pressure to recover white crystals in a yield of 95%.
When the ¹ HNMR spectrum of the crystal was measured in the same manner as described above, the peak attributed to two hydrogen atoms of the carbon / carbon double bond portion that appeared in the region of δ = 6.00 to 6.25 disappeared. The carbon-carbon double bond (disubstituted olefin) at position 11 in chemical formula (1) was hydrogenated. Further, the peak area attributed to five hydrogen atoms of the mono-substituted benzene ring portion appearing in the region of δ = 7.20 to 7.45 and δ = 1.00 to 2.00 include cycloalkane methine hydrogen. Newly appeared. There were no other major changes. Further, it was confirmed from IR spectrum analysis that an anhydrous carbonyl group remained.
From the ratio of the respective peak areas, the reduction compound is about 50 mol% tetracarboxylic dianhydride represented by chemical formula (1) and about 50 mol% tetracarboxylic dianhydride represented by chemical formula (3). It was confirmed that it was composed of
Hereinafter, the compound obtained by this method is referred to as “hydrogenated tetracarboxylic dianhydride mixture B”.

<Production of epoxy resin uncured composition> (Examples 1 to 11)
Tetracarboxylic dianhydrides represented by chemical formulas (1) to (3), “hydrogenated tetracarboxylic dianhydride mixture A”, “hydrogenated tetracarboxylic dianhydride mixture B” and bisphenol A type epoxy resin (Epicoat 828: (manufactured by Japan Epoxy Resin Oil Co., Ltd., epoxy equivalent = 185)) was mixed at a ratio of functional group equivalent ratio shown in Table 1, and benzyldimethylamine (BDMA) was used as a curing accelerator. ) (Tokyo Chemical Industry Co., Ltd. reagent) was added in an amount of 1 part by weight to 100 parts by weight of the epoxy resin and stirred well.

<Toughness (heat cycle resistance) evaluation>
The above epoxy resin uncured composition is molded by a transfer molding machine (molding conditions: 175 ° C., curing time: 2 minutes), then post-cured at 175 ° C. for 8 hours, and Japanese Industrial Standard JIS C-2105 (no solvent for electrical insulation) A cured product test piece was obtained in which metal washers having different thermal conductivities in accordance with the resin test method) were encapsulated.
Heat cycle test: The cracks generated when five test pieces were cooled from 150 ° C. to 0 ° C. were observed, and the average number of cracks was calculated.

<Evaluation of heat resistance (thermal deformation temperature)>
The epoxy resin uncured composition is molded by a transfer molding machine (molding conditions: 175 ° C., curing time: 2 minutes) and then post-cured at 175 ° C. for 8 hours, in accordance with the method of Japanese Industrial Standard JIS K-6901. Test pieces were prepared and measured for heat distortion temperature (HDT).

<UV light transmission resistance evaluation>
The epoxy resin uncured composition is molded by a transfer molding machine (molding conditions: 175 ° C., curing time: 2 minutes), then post-cured at 175 ° C. for 8 hours, cooled, and a test piece of 150 mm × 75 mm is cut out to 400 nm. The initial transmittance and the transmittance after irradiation for 100 hours were measured. The UV irradiation device used was “Dew Panel LightWeather Meter DWPL-5R” manufactured by Suga Test Instruments Co., Ltd., and the test piece was irradiated with a UV lamp. However, the black panel temperature was 63 ° C. and the irradiation intensity was 3 mW / cm 2. .

[Comparative Example 1]
MH-700 (manufactured by Shin Nippon Rika Co., Ltd .: acid anhydride curing agent mainly composed of methylhexahydrophthalic anhydride. Functional group (acid anhydride group) = about 168 g / eq.) Is used as a curing agent. Then, a test piece was prepared and evaluated according to Example 1.

The evaluation results are shown in Table 1.
From Table 1, the cured product obtained from the epoxy resin composition using the curing agent according to the present invention has a small number of cracks even in a wide range of environmental temperature changes, excellent toughness, excellent heat resistance under load, UV The initial transmittance for light is high and the decrease in transmittance is small. This result shows that it is a heat-resistant epoxy resin composition with excellent mechanical properties and transparency maintaining ability to cope with changes in temperature environment, and exhibits extremely excellent properties when used as an LED sealant. It is predicted that

The alicyclic tetracarboxylic acid anhydride represented by the general formulas (1), (2) and (3) in the epoxy resin curing agent composition according to the present invention is a solid having a high melting point, but is an excellent organic solvent. Solubility in water.
In addition, the cured product of the epoxy resin composition obtained by blending the epoxy resin curing agent according to the present invention is excellent in heat resistance and toughness, so that adhesives, paints, civil engineering and building materials, electrical / electronic parts It can be used in various fields such as insulating materials.
Furthermore, it has high transparency and can be used as a sealing material for a light emitting device. In particular, the development of high-intensity blue LEDs (main emission near 460 nm) and the maintenance performance of the transmission performance in the ultraviolet region (for example, 350 to 400 nm) are excellent. And can be used as a sealing material for a display unit.

Reaction path diagram for producing tetracarboxylic dianhydride Reaction path diagram for producing tetracarboxylic dianhydride according to the example

Claims (5)

An epoxy resin curing agent comprising at least one of tetracarboxylic dianhydrides represented by general formulas (1), (2), and (3).

In general formula (1)-(3), R1 represents a hydrogen atom or a C1-C10 alkyl group, and R1 may be same or different, respectively. R2 represents an alkyl group having 1 to 10 carbon atoms. m and n are arbitrary integers from 0 to 5 independent of each other, and when m + n is plural, plural R2s may be the same or different from each other.   An epoxy resin composition comprising the epoxy resin curing agent according to claim 1.   A light-emitting diode encapsulant comprising the epoxy resin composition according to claim 2. A tetracarboxylic dianhydride represented by the general formula (2).

In General formula (2), R1 represents a hydrogen atom or a C1-C10 alkyl group, and R1 may be same or different, respectively. R2 represents an alkyl group having 1 to 10 carbon atoms. m and n are arbitrary integers from 0 to 5 independent of each other, and when m + n is plural, plural R2s may be the same or different from each other. A tetracarboxylic dianhydride represented by the general formula (3).

In General formula (3), R1 represents a hydrogen atom or a C1-C10 alkyl group, and R1 may be same or different, respectively. R2 represents an alkyl group having 1 to 10 carbon atoms. m and n are arbitrary integers from 0 to 5 independent of each other, and when m + n is plural, plural R2s may be the same or different from each other.

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