JP4003551B2 - Alicyclic epoxy compound, alicyclic epoxy resin composition, and sealing material for light emitting diode - Google Patents

Description

【００２０】
更に、２価以上のフェノール化合物とエピクロロヒドリンから得られる種々の芳香族エポキシ化合物も使用することが出来る。斯かる芳香族エポキシ化合物の具体例としては、ハイドロキノンジグリシジルエーテル、レゾルシンのジグリシジルエーテル、ビフェノールのジグリシジルエーテル、３、３’、５、５’−テトラメチルビフェノールのジグリシジルエーテル等が挙げられる。
【００２１】
上記の中では、式（Ｉ）で表されるビスフェノールＡ型エポキシ化合物および式（II）で表されるオルソクレゾールノボラックのポリグリシジルエーテルが好ましく、特に、ビスフェノールＡのジグリシジルエーテル（式（Ｉ）のｎ＝０）及びそのオリゴマーが好ましい。
【００２２】
なお、例えば、ビスフェノールＡのジグリシジルエーテルは、「エピコート８２７」、「８２８」として、そのオリゴマーは、「エピコート８３４」、「１００１」、「１００４」等として、式（II）のものは、「エピコート１５２」、「１５４」、「１８０Ｓ６５」として、何れも、ジャパンエポキシレジン（株）より市販されている。
【００２３】
本発明で使用される水素添加触媒は、主として白金族元素を活性成分とする触媒であり、この中ではロジウム（Ｒｈ）又はルテニウム（Ｒｕ）触媒が好ましく、特にＲｈ触媒が好ましい。また、担体に活性成分を担持して成る触媒が好ましい。担体としては、炭素系担体、酸化物担体の何れでもよい。炭素系担体としては、活性炭、グラファイト、カーボンブラック等が挙げられる。酸化物担体としては、シリカ、アルミナ、チタニア等が挙げられる。これらの中では、炭素系担体が好ましく、高表面積グラファイト（high surface areagraphite）と呼ばれるグラファイトが特に好ましい。炭素系担体の比表面積は通常５〜６００ｍ²／ｇ、粒径は通常５〜５００μである。
【００２４】
水素添加触媒の調製法は、例えば特開平１１−２１７３７９号公報に示す方法などを採用し得る。
【００２５】
水素化反応の反応溶媒としては、水素化に対して安定で触媒に対し被毒性のないエーテル系溶媒、エステル系溶媒、アルコール系溶媒、パラフィン系溶媒などが挙げられる。具体的には、ジエチルエーテル、イソプロピルエーテル、メチル−ｔ−ブチルエーテル、エチレングリコールジメチルエーテル、テトラヒドロフラン、ジオキサン、ジオキソラン等の鎖状または環状のエーテル類、酢酸エチル、酢酸ブチル等のエステル類、エチレングリコールメチルエーテルアセテート等のエーテルエステル類等が好適に使用される。これらの溶媒は、単独使用の他、併用することも出来る。
【００２６】
特に、本発明においては、上記の水素化反応は、エステル系溶媒の含有率が５０重量％以上である反応溶媒の存在下に反応を行なうのが好ましい。斯かる反応溶媒の使用により、脂環式エポキシ化合物中の白金族元素の濃度を低減することが出来る。
【００２７】
エステル系溶媒としては、脂肪酸エステル、炭酸エステル、ラクトン等が挙げられるが、特に脂肪酸エステルが好ましい。また、取扱の面から、常圧下での沸点が５０〜１８０℃の範囲にある脂肪酸エステルが好ましい。斯かる脂肪酸エステルとしては、酢酸メチル、酢酸エチル、酢酸プロピル、酢酸ブチル、酢酸アミル、プロピオン酸メチル、プロピオン酸プロピル、プロピオン酸ブチル、酪酸メチル、酪酸エチル、イソ吉草酸メチル等を挙げることが出来る。これらの中では、酢酸エステルとプロピオン酸エステルが好ましい。具体的には、酢酸エチル、酢酸プロピル、酢酸ブチル、プロピオン酸メチルが好ましく、特に酢酸エチルが好適である。
【００２８】
エステル系溶媒は、従来技術で広く使用されているエーテル系溶媒、アルコール系溶媒、パラフィン系溶媒と混合して使用してもよいが、本発明で得られるエポキシ化合物の品質のためには、エステル系溶媒の割合は、混合溶媒に対し、通常５０重量％以上、好ましくは９０％以上とされる。また、本発明で得られるエポキシ化合物の品質や製造工程の安全性のためには、エーテル系溶媒は実質的に含まないことが好ましく、具体的には、エーテル系溶媒の含有割合は１重量％以下にするのが好ましい。
【００２９】
反応溶媒の使用量は、原料のエポキシ化合物に対する重量比として、通常０．０５〜１０、好ましくは０．１〜３である。反応溶媒の量が余りにも少ない場合は、一般に原料のエポキシ化合物の粘度が高いため、水素の拡散が悪くなり、反応速度が低下したり、水素化反応の選択性が低下する。逆に、反応溶媒の量が余りにも多い場合は、生産性が低下し経済的に不利になる。
【００３０】
反応温度は、通常３０〜１５０℃、好ましくは５０〜１３０℃である。反応温度が低すぎる場合は、反応速度が低下し反応を完結するために多量の水素添加触媒および長時間を必要とする。反応温度が高すぎる場合は、エポキシ基の水素化分解などの副反応が増加し、製品の品質が低下する。反応圧力は、通常１〜３０ＭＰａ、好ましくは３〜１５ＭＰａである。反応圧力が低すぎる場合は、反応速度が低下し反応を完結するために多量の水素添加触媒および長時間を必要とする。反応圧力が高すぎる場合は、必要な設備が大掛かりとなり、経済的に不利となる。
【００３１】
反応方式としては、液相懸濁反応または固定床反応が可能であるが、特に液相懸濁反応が好ましい。水素は、流通方式で導入してもよいし、消費分だけ導入してもよい。また、水素は、液中に導入して分散させることも出来るし、気相から攪拌などの手段で液中に巻き込んで吸収させることも出来る。反応の終点は、水素吸収のモニター又はサンプリングによる分析で判断することが出来る。
【００３２】
反応終了後、反応液から触媒を濾過・遠心分離などの操作で分離し、その後、蒸留によって反応溶媒を留去し、目的生成物を得ることが出来る。反応溶媒の留去は、減圧下において、通常５０〜２００℃、好ましくは７０〜１５０℃の条件で行う。使用時の環境に与える影響、特に臭気の観点から、反応溶媒の残在量は、通常１重量％以下、好ましくは０．２重量％以下とされる。反応溶媒の残在量の下限は通常０．００１重量％である。それ以上の反応溶媒の留去は、長時間の加熱を必要とし、製品の安定性が低下する懸念がある。反応溶媒の残存量の一層の低減には、窒素などの不活性ガスの導入が効果的である。
【００３３】
本発明において、脂環式エポキシ化合物中の白金族元素の低減方法としては、水素化反応して得られるエポキシ化合物を吸着剤と接触させる方法を採用する。そして、更に、必要に応じ、次の（１）〜（５）に記載の方法を組み合わせることが出来る。
【００３４】
（１）水素化反応に使用する触媒の調製方法
（２）水素化反応条件を選択する方法
（３）溶存する白金族元素を還元にて析出させる方法
（４）溶存する白金族元素を液液抽出にて抽出除去する方法
（５）真空蒸留にてエポキシ化合物を留出液として回収する方法
【００３５】
例えば、上記の（３）以降の手段を併用することにより、触媒からの白金族金属の溶出が許容されるため、上記（１）の触媒の調製方法の自由度が広がり、上記（２）の反応条件をより高温にして触媒当たりの生産性を向上させたり、吸着剤処理への負荷を少なくすることが可能となる。
【００３６】
上記の吸着剤としては、活性炭、活性白土、イオン交換樹脂、合成吸着剤などが挙げられる。これらの中では活性炭が好ましい。吸着剤の活性表面としては、酸性、中性または塩基性の何れをも採り得るが、塩基性が好ましい。斯かる塩基性の吸着剤としては、酸化マグネシウム等の固体塩基性化合物、塩基性イオン交換樹脂、塩基性の活性炭などが挙げられる。
【００３７】
上記の吸着法は、粉末吸着剤による回分接触処理、吸着剤充填層への流通処理の何れの方式であってもよい。粉末吸着剤としては平均粒径が１〜１０００μｍの吸着剤が好適に用され、粒状吸着剤としては平均粒径が１〜１０ｍｍの吸着剤が好適に使用される。
【００３８】
活性炭の種類は、特に制限されず、ヤシ殻原料、木質原料、石炭原料などの各種の原料から製造される各種の活性炭を使用することが出来る。各種の原料から製造される各種の各種の活性炭を使用することが出来るが、特に好ましい活性炭は表面性状が塩基性の活性炭である。具体的には、水に分散させたスラリーのｐＨが８〜１２のものである。活性炭の比表面積としては５００〜３０００ｍ²／ｇの範囲が好適である。なお、上記のｐＨは、ＪＩＳ Ｋ−１４７０（粉末活性炭試験法）に従って測定した値である。
【００３９】
吸着剤の使用量は、吸着剤の種類によっても異なるが、処理液に含まれるエポキシ化合物に対し、通常０．０１〜１００重量％、好ましくは０．１〜２０重量％、更に好ましくは０．２〜１０重量％である。吸着剤の使用量が０．０１重量％未満では吸着剤の使用効果が十分発揮されず、１００重量％を超える場合は製品の損失が増加する。
【００４０】
接触処理の温度は、通常０〜１００℃、好ましくは１０〜８０℃である。また、接触処理の状態は、作業性、回収率、吸着効率などの面から、溶媒を含む状態が好ましい。溶媒の種類は、エポキシ化合物が溶解すれば特に制限されない。上記の精製工程は、通常、反応液を濃縮する前に行われるため、反応溶媒がそのまま好適に使用される。溶媒の含有量は溶液中の濃度として、通常５〜８０重量％である。溶媒の量が余りにも少ない場合は、適宜に溶媒を添加して処理液の粘度を調節し、吸着効率を向上させる。
【００４１】
本発明においては、水素化反応後、水素添加触媒を分離せず、反応液に吸着剤を入れて混合し、触媒と吸着剤とを一緒に固液分離することも出来る。斯かる方法によれば、次の様な利点がある。
【００４２】
すなわち、水素化反応後、反応液に吸着剤を入れずに触媒の固液分離を行なう場合は、触媒表面に付着した有機物の粘着性によって固液分離性が低下する。これに対し、上記の方法に従って、吸着剤（特には活性炭）と共に触媒の固液分離を行なう場合は固液分離性が極めて良好となる。勿論、斯かる方法にっても白金族元素の除去効率は殆ど変化しない。吸着剤と共に触媒の固液分離を行なう場合、吸着剤の使用量は、触媒に対して１〜３０重量比とするのが好ましい。
【００４３】
脂環式エポキシ化合物中の白金族元素濃度は、ＬＥＤ用封止材に使用するため、２ｐｐｍ以下にする必要がある。白金族元素濃度は、好ましくは１ｐｐｍ以下、更に好ましくは０．５ｐｐｍであり、品質要求が厳しい特殊用途の場合は０．１ｐｐｍ以下である。白金族元素の濃度が２ｐｐｍを超える場合は、脂環式エポキシ化合物の可視域および紫外域の透過率が低下したり、脂環式エポキシ化合物を主成分とする組成物の透過率が紫外線により経的的に劣化し易くなる。
【００４４】
白金族元素の分析は、サンプルを直接溶媒に希釈するか、または、有機物を燃焼した後、ピロ硫酸カリウムを添加して湿式分解して水溶液系で溶解した後、原子吸光法やＩＣＰ発光分析などの公知の手法で行うことが出来る。
【００４５】
白金族元素の存在が製品に与える影響としては、製品の透過率の低下が挙げられる。特に短い波長側での透過率の低下が大きい。このことは、以下の式の様に、４００ｎｍと７００ｎｍの透過率の値の比（石英１ｃｍセル）によって定量化することが出来る。
【００４６】
【数１】
Ｋ＝Ｔ400／Ｔ700
【００４７】
すなわち、上記の透過率の比（Ｋ値）が１に近い程に色むらが小さい。また、白金族元素の値が多い程、Ｋ値は１より小さくなり、短波長側の吸収が増加する。上記のＫ値は０．９以上あることが好ましい。また、白金族元素以外の要因により、Ｋ値が１より大きくなる場合、Ｋ値は１．１以下であることが好ましい。また、紫外線領域での吸収は３４０ｎｍにおける透過率で測定することが出来る。３４０ｎｍにおける透過率は、紫外線領域での封止材の安定性の観点から、好ましくは８０％以上、更に好ましくは９０％以上である。
【００４８】
本発明の脂環式エポキシ化合物の水素化率は、通常８５％以上、好ましくは９５％以上、更に好ましくは９８％以上である。芳香環の水素化率が８５％未満の場合は、エポキシ樹脂硬化物の色相の再現性、均一性、安定性が低下し、更に、ＬＥＤの放射光度も経時的に低下するため、好ましくない。芳香環の水素化率は、芳香環が脂肪族環に変化した割合であり、核磁気共鳴分析、吸光度分析などの方法により求めることが出来る。
【００４９】
本発明の脂環式エポキシ化合物におけるエポキシ基の分解率は２０％以下であることが好ましい。エポキシ基の分解率はエポキシ基が水酸基などの他の官能基に分解された割合である。エポキシ基の分解率が２０％を超える場合は、エポキシ樹脂硬化物の耐熱性が低下する傾向にある。エポキシ基の分解率は芳香環のみが水素化された場合の理論エポキシ当量と製品の実際のエポキシ当量から計算で求めることが出来る。エポキシ当量は、過塩素酸による滴定などの公知の方法で測定することが出来る。また、エポキシ分解率をガスクロマトグラフィー等で直接検出することも出来る。
【００５０】
また、本発明の脂環式エポキシ化合物における塩素の含有量は０．３重量％以下であることが好ましい。ここで、塩素含量とは、エポキシ化合物中に含有される有機塩素および無機塩素の総量である。塩素の含有量が０．３重量％を超える場合は、耐湿性、高温電気特性および耐候性が低下する傾向にあるため、特に、電気・電子用エポキシ樹脂としての用途に不適当な場合がある。塩素の含有量は、ビフェニルナトリウムでエポキシ化合物中の塩素を反応させた後、硝酸銀で滴定する方法により測定することが出来る。
【００５１】
脂環式エポキシ化合物は、エポキシ樹脂用硬化剤と混合し、必要に応じ、その他の脂環式エポキシ化合物や助剤と混合して脂環式エポキシ樹脂組成物とする。斯かる脂環式エポキシ樹脂組成物は、例えばＬＥＤ用封止材として使用することが出来る。
【００５２】
本発明においては、上記の脂環式エポキシ樹脂組成物（ＬＥＤ用封止材）中の白金族元素濃度も低減する必要がある。すなわち、白金族元素濃度は、上記と同様に２ｐｐｍ以下とされ、好ましい態様は上記と同じである。
【００５３】
上記の硬化剤としては、アミン類、酸無水物類、多価フェノール類、イミダゾール類、ブレンステッド酸塩類、ジシアンジアミド類、有機酸ヒドラジッド類、ポリメルカプタン類、有機ホスフィン類などが挙げられるが、この中では酸無水物類が好ましい。
【００５４】
上記の酸無水物類としては、例えば、無水フタル酸、無水トリメリット酸、無水ピロメリット酸などの芳香族酸無水物類、無水テトラヒドロフタル酸、無水メチルテトラヒドロフタル酸、無水ヘキサヒドロフタル酸、無水メチルヘキサヒドロフタル酸、無水メチルエンドメチレンテトラヒドロフタル酸、無水ドデセニルコハク酸、無水トリアルキルテトラヒドロフタル酸などの環状脂肪族酸無水物が挙げられる。これらの中では、環状脂肪族酸無水物が好ましく、特に飽和脂肪族である無水ヘキサヒドロフタル酸または無水メチルヘキサヒドロフタル酸が好ましい。
【００５５】
上記の硬化剤は、それぞれ、単独使用の他、２種以上を併用することが出来るが、全硬化剤中に占める芳香族化合物の割合が１０重量％以下になる様に調節するのが好ましい。硬化剤の使用量は、脂環式エポキシ化合物１００重量部に対し、通常０．０１〜２００重量部、好ましくは０．１〜１５０重量部である。
【００５６】
前記のその他の脂環式エポキシ化合物としては、代表的には、シクロオレフィンのエポキシ化物が挙げられ、その具体例としては、３，４−エポキシシクロヘキシルメチル−３’，４’−エポキシシクロヘキサンカルボキシレート等が挙げられる。斯かる脂環式エポキシ化合物の使用量は、前述の本発明に係る脂環式エポキシ化合物に対し、通常０．０１〜１０重量比、好ましくは０．０５〜１重量比である。
【００５７】
また、上記のその他の助剤としては、脂環式エポキシ樹脂組成物の場合は、硬化促進剤、酸化防止剤、紫外線吸収剤、補強材、充填剤、着色剤、顔料、難燃剤が挙げられる。ＬＥＤ用封止材の場合は、上記の他に蛍光体が挙げられる。蛍光体は、発光素子の発光を受けて励起し、励起波長よりも長い波長の光を発光する。
【００５８】
本発明のＬＥＤ用封止材が適用される発光素子の一例としてはIII族窒素化合物半導体が挙げられる。発光素子から発光される主波長は、３５０ｎｍ以上５５０ｎｍ以下であるのが好ましい。特に好ましい主波長は３６０〜４８０ｎｍである。封止材で発光素子を封止して成るＬＥＤの構造は、例えば、特開平５９−５４２７７号公報、特許第２９２７２７９号公報などに記載されている。本発明のＬＥＤ用封止材は、これらの波長の光で経時劣化が少ないという特徴を有する。
【００５９】
【実施例】
以下、本発明を実施例により更に詳細に説明するが、本発明は、その要旨を超えない限り、以下の実施例に限定されるものではない。なお、以下の諸例中で使用した分析方法および物性測定方法は次の通りである。
【００６０】
（１）ロジウム濃度の分析：
ロジウム濃度の分析は、エタノールに溶解した試料を使用し原子吸光測定により行なった。具体的には、装置として、バリアン・テクノロジーズ・ジャパンリミテッド社製の「ＧＦ−ＡＡＳ Ｓｐｅｃｔｒａ ＡＡ−３００」を使用し、ロジウム標準液により検量線を作成し、試料中のロジウム濃度に応じ、エタノールによる希釈倍率を５〜５０００倍に変化させ、この濃度が検量線の濃度範囲に入る様に分析した。この方法のロジウム分析下限界は０．０２ｐｐｍであった。
【００６１】
（２）芳香環の水素化率：
酢酸エチルに溶解した試料を使用し２７５ｎｍでの吸光度を測定し、原料の芳香族エポキシ化合物の吸光度と比較して算出した。酢酸エチルによる希釈倍率は水素化率に応じ１０〜１０００倍とした。
【００６２】
（３）エポキシ当量：
ＪＩＳ Ｋ７２３６−１９９５に準拠し、酢酸と臭化セチルトリメチルアンモニウムの存在下、過塩素酸で滴定し、発生する臭化水素をエポキシ基に付加させ、終点を電位差で判定した。試料は製品（原液）を使用した。
【００６３】
（４）エポキシ基の分解率：
下記の式で計算した。なお、原料としてジャパンエポキシレジン社製「エピコート８２８ＵＳ」（エポキシ当量１８６）を使用した際の理論エポキシ当量は１９２とした。
【００６４】
【数２】

【００６５】
（５）塩素含量：
ビフェニルナトリウムでエポキシ化合物中の塩素を反応させた後、硝酸銀で滴定して測定した。
【００６６】
（６）透過率：
島津製作所製の「ＵＶ−２４００ＰＣ」を使用し、１ｃｍセルを使用し、蒸留水をブランクとして測定した。試料は製品（原液）を使用した。
【００６７】
実施例１
１Ｌ誘導攪拌式オートクレーブ内に、ビスフェノールＡ型エポキシ化合物（ジャパンエポキシレジン社製「エピコート８２８ＥＬ」エポキシ当量１８６）４００ｇ、テトラヒドロフラン（ＴＨＦ）１００ｇ、水素添加触媒として５重量％ロジウム／グラファイト触媒１．２ｇを仕込み、オートクレーブ内を窒素置換した後、水素置換した。その後、１１０℃、８ＭＰａの水素圧力で水素化反応を行った。３時間で水素の吸収がほぼ停止した。
【００６８】
反応液に反応溶媒（ＴＨＦ）を添加してエポキシ樹脂濃度が５０重量％になるように希釈した後、５Ｃの濾紙を使用して反応液から水素添加触媒を濾過した。すなわち、１Ｌの濾過器を使用し、０．０５ＭＰａの濾過圧で濾過した。濾過時間は１時間要した。そして、反応液にｐＨ５〜８の粉末活性炭（二村化学製「太閤Ｋ」ｄｒｙ品）１６ｇを入れて３０分混合した後、活性炭を濾別した。次いで、減圧下１００℃で少量の窒素を吹き込みながら反応溶媒を留去して透明な製品を得た。製品の分析結果を表１及び表２に示す。
【００６９】
実施例２
実施例１において、活性炭の量を１６ｇから２４ｇに変更する以外は、実施例１と同様の操作を行った。結果は表１及び表２に示す通りであった。
【００７０】
実施例３
実施例１において、反応溶媒をテトラヒドロフランから酢酸エチルに、活性炭の量を１６ｇから４ｇに変更する以外は、実施例１と同様の操作を行った。結果は表１及び表２に示す通りであった。
【００７１】
比較例１
実施例１において、活性炭による吸着処理を行わない以外は、実施例１と同様の操作を行った。結果は表１及び表２に示す通りであった。
【００７３】
【表１】

【００７４】
【表２】

【００７５】
実施例４
窒素置換した１３００Ｌのオートクレーブ内に、ビスフェノールＡ型エポキシ化合物（ジャパンエポキシレジン社製「エピコート８２８ＵＳ」エポキシ当量１８６）７５０ｋｇ、酢酸エチル１８８ｋｇ、水素添加触媒として５重量％ロジウム／グラファイト触媒２．３ｋｇを仕込み、オートクレーブ内を水素置換した。その後、１１０℃、８ＭＰａの水素圧力で８時間水素化反応を行った。
反応液にｐＨ５〜８の活性炭（二村化学製「太閤Ｋ」ｄｒｙ品）１５ｋｇと酢酸エチル５６０ｋｇを入れて３０分混合した後、活性炭を濾別した。次いで、減圧下１００℃で少量の窒素を吹き込みながら反応溶媒を留去して透明な製品を得た。製品の分析結果を表３及び表４に示す。
【００７６】
【表３】

【００７７】
【表４】

【００７８】
実施例５
実施例４で得たエポキシ樹脂１００ｇ、硬化剤として４−メチルヘキサヒドロフタル酸無水物（新日本理化社製「ＭＨ−７００」）８３ｇ、硬化触媒（日本化学工業社製「ヒシコーリンＰＸ−４ＥＴ）」１．０ｇを混合し、厚さ３ｍｍに注型し、１００℃で３時間予備硬化した後に１２０℃で３時間本硬化した。冷却後、１５０ｍｍ×７５ｍｍの試験片を切り出し、測定波長：３４０ｎｍ、４００ｎｍ、７００ｎｍにおける透過率を測定した。紫外線による劣化評価は、紫外線照射装置（スガ試験機社製「Ｄｅｗ Ｐａｎｅｌ Ｌｉｇｈｔ Ｃｏｎｔｒｏｌ Ｗｅａｔｈｅｒ Ｍｅｔｅｒ ＤＷＰＬ−５Ｒ」）を使用し、紫外線（ＵＶ）蛍光ランプで試験片に紫外線を連続的に照射することにより行なった。ただし、ブラックパネル温度は６３℃、照射強度は３ｍＷ／ｃｍ^２とした。１５０時間のＵＶ照射後、再度、上記の測定波長で透過率を測定した。結果を表５に示す。
【００７９】
実施例６
実施例５において、エポキシ樹脂として、実施例４及び比較例１で得たエポキシ樹脂の混合物（混合比率６５：３５重量比）を使用した以外は、実施例５と同様にして試験片を作成し、透過率を測定した。硬化物中のＲｈ濃度は１．７ｐｐｍであった。結果を表５に示す。
【００８０】
比較例２
実施例５において、エポキシ樹脂として、比較例１で得たエポキシ樹脂（Ｒｈ濃度９ｐｐｍ）を使用した以外は、実施例５と同様にして試験片を作成し、透過率を測定した。硬化物中のＲｈ濃度は５．０ｐｐｍであった。結果を表５ に示す。
【００８１】
比較例３
芳香族エポキシ樹脂（ビスフェノール型エポキシ樹脂、ジャパンエポキシレジン（株）製「エピコート８２８ＵＳ」）１００ｇ、硬化剤（新日本理化社製「ＭＨ−７００」）９０ｇ、硬化触媒（日本化学工業社製「ヒシコーリンＰＸ−４ＥＴ）」１．０ｇを混合し、厚さ３ｍｍに注型し、１００℃で３時間予備硬化した後に１２０℃で３時間本硬化した。以降、実施例５と同様にして試験片を作成し、透過率を測定した。結果を表５に示す。
【００８２】
【表５】

【００８３】
表５に示す様に、実施例５及び６の場合は、封止材（エポキシ樹脂硬化物）中のＲｈ濃度が低いため、初期の透過率も高く且つＵＶ１５０Ｈｒ照射後の透過率の劣化も小さい。これに対し、比較例２の場合は、封止材中のＲｈ濃度が高いため、ＵＶ１５０Ｈｒ照射後の透過率の劣化が大きい。比較例３の場合は、Ｒｈが含まれないが、芳香環を含むために透過率の低下が大きい。
【００８４】
【発明の効果】
以上説明した本発明によれば、色相の再現性、均一性、安定性などの変化が小さく、しかも、ＬＥＤの放射光度の経時的低下が小さい脂環式エポキシ化合物（封止材）が提供され、本発明の工業的価値は顕著である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alicyclic epoxy compound, an alicyclic epoxy resin composition, and a light-emitting diode sealing material (LED sealing material).
[0002]
[Prior art]
Epoxy compounds are excellent in heat resistance, adhesiveness, water resistance, mechanical strength, electrical properties, etc., so they are used in various fields such as adhesives, paints, materials for civil engineering and construction, and insulation materials for electrical and electronic parts. in use.
[0003]
As said epoxy compound, aromatic epoxy resins, such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, phenol, or a cresol novolak type epoxy resin, are common.
[0004]
On the other hand, LEDs are put into practical use in various display boards, image reading light sources, traffic signals, large display units, and the like. In LED light-emitting devices, the periphery of a light-emitting element is generally sealed with a transparent resin from the viewpoint of protecting the semiconductor and collecting light, and particularly with an epoxy compound from the viewpoint of adhesion and the like. It is common to do.
[0005]
However, in the case of an epoxy resin cured with an acid anhydride, it is known that alteration due to the acid anhydride is likely to occur. Further, when the cured resin is exposed outdoors or when exposed to a light source that generates ultraviolet rays, there is a problem of causing yellowing. In particular, in recent years, development of high-brightness blue (main emission in the vicinity of 460 nm) LEDs and development of LEDs having main emission in the ultraviolet region (for example, 350 to 400 nm) are progressing.
[0006]
Further, in addition to the conventional red LED and green LED, the performance of the blue LED is improved, so that the display of the three primary colors becomes possible, and it is used for a display unit or the like. Further, a white LED that uses a light emitting element and a phosphor together and mixes colors by converting a part or all of light emission on the short wavelength side of the light emitting element to the long wavelength side has also been proposed. It is used for lights.
[0007]
By the way, as described above, as the emission wavelength becomes shorter, the energy of light increases, so that the sealing material is easily deteriorated. For example, Japanese Patent Application Laid-Open No. 8-148717 describes that the sealing material deteriorates due to heat and light generated from a blue LED and the luminous intensity is reduced. Moreover, since white LED is a mixed color, there is a concern that the color tone changes if the sealing material has light absorption in the visible region wavelength. In particular, the human color sensation for white is sensitive. For example, Japanese Patent Laid-Open No. 2000-315826 describes that color unevenness occurs due to refraction by a sealing material depending on the measurement orientation of an LED.
[0008]
In order to solve the above-described problems caused by light having a short wavelength, JP-A No. 2001-19742 proposes a composition comprising a nuclear hydride of an aromatic epoxy compound and a cation curing catalyst. This composition has improved toughness and coloring of the cured product and is excellent in light resistance.
[0009]
On the other hand, various attempts have been proposed to produce corresponding alicyclic epoxy compounds by hydrogenating the aromatic rings of aromatic epoxy compounds. For example, U.S. Pat. No. 3,336,241 describes at least one epoxy group and at least one carbon-carbon in the presence of a hydrogenation catalyst having rhodium or ruthenium supported on an inert carrier such as activated carbon. A method for hydrogenating an organic compound having a double bond has been proposed.
[0010]
Japanese Patent Application Laid-Open No. 11-217379 proposes a hydrogenation catalyst in which rhodium or ruthenium is supported on a carbonaceous support having a specific surface area in the range of 5 to 600 m ² / g in order to improve activity and selectivity. . Furthermore, Japanese Patent Application Laid-Open No. 11-199645 proposes an epoxy compound with a low chlorine content that has a high hydrogenation rate and a small loss of epoxy groups based on the above method.
[0011]
However, in the hydrogenation method using a noble metal catalyst, the transmittance on the short wavelength side of the resulting alicyclic epoxy compound (encapsulant) decreases with time. Therefore, with such an alicyclic epoxy compound, in the case of an LED having a main emission wavelength on the short wavelength side, the emitted light intensity of the LED decreases with time. In the case of a white LED, there is a problem that the color tone of white changes due to the transmittance distribution in the visible light region.
[0012]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and the purpose thereof is an alicyclic epoxy in which changes in hue reproducibility, uniformity, stability, etc. are small, and a decrease in radiant intensity of an LED is small over time. The object is to provide a compound (sealing material).
[0013]
[Means for Solving the Problems]
The above object is achieved by the present inventions (1) to (3) below.
[0014]
(1) An alicyclic epoxy compound obtained by selectively hydrogenating an aromatic ring of an aromatic epoxy compound in the presence of a platinum group element-containing hydrogenation catalyst and then contacting with an adsorbent , wherein the platinum group element The alicyclic epoxy compound characterized by having a concentration of 2 ppm or less.
[0015]
(2) An alicyclic ring mainly composed of an alicyclic epoxy compound obtained by selectively hydrogenating an aromatic ring of an aromatic epoxy compound in the presence of a platinum group element-containing hydrogenation catalyst and then contacting with an adsorbent. An alicyclic epoxy resin composition having a platinum group element concentration of 2 ppm or less.
[0016]
(3) A light-emitting diode encapsulant comprising the above alicyclic epoxy resin composition.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. The aromatic epoxy compound used in the present invention is an aromatic compound having two or more epoxy groups in the molecule, and includes various compounds such as glycidyl ethers, glycidyl esters, and glycidyl amines.
[0018]
Specific examples of the aromatic compound include, for example, an epoxy compound represented by the general formula (I) using bisphenol A or bisphenol F and epichlorohydrin as raw materials, and a phenol novolak represented by the general formula (II). Examples thereof include polyglycidyl ethers of resins or cresol novolac resins.
[0019]
[Chemical 1]

[0020]
Furthermore, various aromatic epoxy compounds obtained from a divalent or higher valent phenol compound and epichlorohydrin can also be used. Specific examples of such aromatic epoxy compounds include hydroquinone diglycidyl ether, resorcin diglycidyl ether, biphenol diglycidyl ether, diglycidyl ether of 3,3 ′, 5,5′-tetramethylbiphenol, and the like. .
[0021]
Among the above, the bisphenol A type epoxy compound represented by the formula (I) and the polyglycidyl ether of orthocresol novolak represented by the formula (II) are preferable, and in particular, the diglycidyl ether of bisphenol A (formula (I) N = 0) and oligomers thereof are preferred.
[0022]
For example, diglycidyl ether of bisphenol A is “Epicoat 827” and “828”, its oligomer is “Epicoat 834”, “1001”, “1004”, etc., and those of formula (II) are “ All of them are commercially available from Japan Epoxy Resins Co., Ltd. as Epicoat 152 ”,“ 154 ”, and“ 180S65 ”.
[0023]
The hydrogenation catalyst used in the present invention is a catalyst mainly containing a platinum group element as an active component. Among them, a rhodium (Rh) or ruthenium (Ru) catalyst is preferable, and an Rh catalyst is particularly preferable. Also preferred is a catalyst comprising an active component supported on a carrier. As the support, either a carbon-based support or an oxide support may be used. Examples of the carbon-based carrier include activated carbon, graphite, and carbon black. Examples of the oxide carrier include silica, alumina, titania and the like. Among these, carbon-based carriers are preferable, and graphite called high surface area graphite is particularly preferable. The specific surface area of the carbon-based carrier is usually 5 to 600 m ² / g, and the particle size is usually 5 to 500 μm.
[0024]
As a method for preparing the hydrogenation catalyst, for example, a method shown in JP-A-11-217379 can be employed.
[0025]
Examples of the reaction solvent for the hydrogenation reaction include ether solvents, ester solvents, alcohol solvents, and paraffin solvents that are stable to hydrogenation and are not toxic to the catalyst. Specifically, chain ethers such as diethyl ether, isopropyl ether, methyl-t-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, dioxolane, esters such as ethyl acetate and butyl acetate, ethylene glycol methyl ether Ether esters such as acetate are preferably used. These solvents can be used alone or in combination.
[0026]
In particular, in the present invention, the hydrogenation reaction is preferably performed in the presence of a reaction solvent having an ester solvent content of 50% by weight or more. By using such a reaction solvent, the concentration of the platinum group element in the alicyclic epoxy compound can be reduced.
[0027]
Examples of ester solvents include fatty acid esters, carbonate esters, and lactones, with fatty acid esters being particularly preferred. Moreover, the fatty acid ester which has the boiling point in the range of 50-180 degreeC under a normal pressure from the surface of handling is preferable. Examples of such fatty acid esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, methyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, and methyl isovalerate. . Of these, acetates and propionates are preferred. Specifically, ethyl acetate, propyl acetate, butyl acetate, and methyl propionate are preferable, and ethyl acetate is particularly preferable.
[0028]
The ester solvent may be used by mixing with an ether solvent, alcohol solvent, or paraffin solvent widely used in the prior art, but for the quality of the epoxy compound obtained in the present invention, an ester solvent may be used. The proportion of the system solvent is usually 50% by weight or more, preferably 90% or more, based on the mixed solvent. Further, for the quality of the epoxy compound obtained in the present invention and the safety of the production process, it is preferable that the ether solvent is not substantially contained. Specifically, the content of the ether solvent is 1% by weight. The following is preferable.
[0029]
The use amount of the reaction solvent is usually 0.05 to 10, preferably 0.1 to 3, as a weight ratio with respect to the raw material epoxy compound. When the amount of the reaction solvent is too small, since the viscosity of the raw material epoxy compound is generally high, hydrogen diffusion becomes worse, the reaction rate is lowered, and the selectivity of the hydrogenation reaction is lowered. On the other hand, when the amount of the reaction solvent is too large, the productivity is lowered and it is economically disadvantageous.
[0030]
The reaction temperature is usually 30 to 150 ° C, preferably 50 to 130 ° C. If the reaction temperature is too low, the reaction rate decreases and a large amount of hydrogenation catalyst and a long time are required to complete the reaction. When the reaction temperature is too high, side reactions such as epoxy group hydrogenolysis increase and the product quality decreases. The reaction pressure is usually 1-30 MPa, preferably 3-15 MPa. If the reaction pressure is too low, the reaction rate decreases and a large amount of hydrogenation catalyst and a long time are required to complete the reaction. If the reaction pressure is too high, the necessary equipment becomes large, which is economically disadvantageous.
[0031]
As a reaction system, a liquid phase suspension reaction or a fixed bed reaction is possible, but a liquid phase suspension reaction is particularly preferable. Hydrogen may be introduced by a distribution method or may be introduced only for consumption. Further, hydrogen can be introduced and dispersed in the liquid, or it can be absorbed in the liquid by means of stirring from the gas phase. The end point of the reaction can be determined by analysis of hydrogen absorption monitoring or sampling.
[0032]
After completion of the reaction, the catalyst is separated from the reaction solution by operations such as filtration and centrifugation, and then the reaction solvent is distilled off by distillation to obtain the desired product. The reaction solvent is distilled off under reduced pressure, usually at 50 to 200 ° C., preferably 70 to 150 ° C. From the viewpoint of influence on the environment at the time of use, particularly odor, the residual amount of the reaction solvent is usually 1% by weight or less, preferably 0.2% by weight or less. The lower limit of the remaining amount of the reaction solvent is usually 0.001% by weight. Further distillation of the reaction solvent requires long-time heating, and there is a concern that the stability of the product is lowered. Introducing an inert gas such as nitrogen is effective in further reducing the remaining amount of the reaction solvent.
[0033]
In the present invention, as a method for reducing the platinum group element in the alicyclic epoxy compound, a method of bringing an epoxy compound obtained by a hydrogenation reaction into contact with an adsorbent is employed . Furthermore, the methods described in the following (1) to (5) can be combined as necessary.
[0034]
(1) Method for preparing catalyst used for hydrogenation reaction (2) Method for selecting hydrogenation reaction conditions (3) Method for depositing dissolved platinum group element by reduction (4) Liquid platinum for dissolved platinum group element Method of extracting and removing by extraction (5) Method of recovering epoxy compound as distillate by vacuum distillation
For example, since the elution of the platinum group metal from the catalyst is allowed by using the means after the above (3) in combination, the degree of freedom of the preparation method of the catalyst of the above (1) is expanded, It becomes possible to improve the productivity per catalyst by increasing the reaction conditions, and to reduce the load on the adsorbent treatment.
[0036]
Examples of the adsorbent include activated carbon, activated clay, ion exchange resin, and synthetic adsorbent. Among these, activated carbon is preferable. The active surface of the adsorbent can be acidic, neutral or basic, but is preferably basic. Examples of such basic adsorbents include solid basic compounds such as magnesium oxide, basic ion exchange resins, and basic activated carbon.
[0037]
The adsorption method described above may be any system of batch contact treatment with a powder adsorbent and distribution treatment to the adsorbent packed bed. As the powder adsorbent, an adsorbent having an average particle diameter of 1 to 1000 μm is suitably used, and as the granular adsorbent, an adsorbent having an average particle diameter of 1 to 10 mm is suitably used.
[0038]
The kind of activated carbon is not particularly limited, and various activated carbons produced from various raw materials such as coconut shell raw material, woody raw material, and coal raw material can be used. Various types of activated carbon produced from various raw materials can be used, and particularly preferable activated carbon is activated carbon having a basic surface property. Specifically, the slurry dispersed in water has a pH of 8-12. The specific surface area of the activated carbon is preferably in the range of 500 to 3000 m ² / g. In addition, said pH is the value measured according to JISK-1470 (powder activated carbon test method).
[0039]
The amount of adsorbent used varies depending on the type of adsorbent, but is usually 0.01 to 100% by weight, preferably 0.1 to 20% by weight, more preferably 0.8%, based on the epoxy compound contained in the treatment liquid. 2 to 10% by weight. When the amount of the adsorbent used is less than 0.01% by weight, the effect of using the adsorbent is not sufficiently exhibited, and when it exceeds 100% by weight, the loss of the product increases.
[0040]
The temperature of the contact treatment is usually 0 to 100 ° C, preferably 10 to 80 ° C. The contact treatment is preferably in a state containing a solvent from the viewpoints of workability, recovery rate, adsorption efficiency, and the like. The type of the solvent is not particularly limited as long as the epoxy compound is dissolved. Since the above purification step is usually performed before the reaction solution is concentrated, the reaction solvent is preferably used as it is. The content of the solvent is usually 5 to 80% by weight as the concentration in the solution. When the amount of the solvent is too small, the solvent is appropriately added to adjust the viscosity of the treatment liquid to improve the adsorption efficiency.
[0041]
In the present invention, after the hydrogenation reaction, the hydrogenation catalyst is not separated, but the adsorbent is put into the reaction solution and mixed, and the catalyst and the adsorbent can be solid-liquid separated together. Such a method has the following advantages.
[0042]
That is, when the solid-liquid separation of the catalyst is performed without adding an adsorbent to the reaction solution after the hydrogenation reaction, the solid-liquid separation property is lowered due to the stickiness of the organic matter attached to the catalyst surface. On the other hand, when performing solid-liquid separation of the catalyst together with the adsorbent (particularly activated carbon) according to the above method, the solid-liquid separation property is extremely good. Of course, even with such a method, the removal efficiency of the platinum group element hardly changes. When performing solid-liquid separation of the catalyst together with the adsorbent, the amount of adsorbent used is preferably 1 to 30 weight ratio with respect to the catalyst.
[0043]
The platinum group element concentration in the alicyclic epoxy compound needs to be 2 ppm or less in order to be used for an LED encapsulant. The platinum group element concentration is preferably 1 ppm or less, more preferably 0.5 ppm, and 0.1 ppm or less in the case of special applications with strict quality requirements. When the concentration of the platinum group element exceeds 2 ppm, the transmittance of the alicyclic epoxy compound in the visible region and the ultraviolet region is reduced, or the transmittance of the composition mainly composed of the alicyclic epoxy compound is increased by ultraviolet rays. It becomes easy to deteriorate automatically.
[0044]
For analysis of platinum group elements, the sample is diluted directly in a solvent, or after burning organic matter, potassium pyrosulfate is added and wet-decomposed and dissolved in an aqueous solution, and then atomic absorption spectrometry, ICP emission analysis, etc. It can carry out by the well-known method.
[0045]
The influence of the presence of the platinum group element on the product includes a decrease in the transmittance of the product. In particular, the transmittance is greatly reduced on the short wavelength side. This can be quantified by the ratio of the transmittance values of 400 nm and 700 nm (quartz 1 cm cell) as in the following equation.
[0046]
[Expression 1]
K = T400 / T700
[0047]
That is, the color unevenness is smaller as the transmittance ratio (K value) is closer to 1. Further, the greater the value of the platinum group element, the smaller the K value is and the shorter wavelength side absorption increases. The K value is preferably 0.9 or more. Moreover, when K value becomes larger than 1 by factors other than a platinum group element, it is preferable that K value is 1.1 or less. Absorption in the ultraviolet region can be measured by transmittance at 340 nm. The transmittance at 340 nm is preferably 80% or more, more preferably 90% or more, from the viewpoint of the stability of the sealing material in the ultraviolet region.
[0048]
The hydrogenation rate of the alicyclic epoxy compound of the present invention is usually 85% or more, preferably 95% or more, and more preferably 98% or more. When the hydrogenation rate of the aromatic ring is less than 85%, the reproducibility, uniformity and stability of the hue of the cured epoxy resin are lowered, and the emitted light intensity of the LED is also lowered with time. The hydrogenation rate of the aromatic ring is the ratio at which the aromatic ring is changed to an aliphatic ring, and can be determined by methods such as nuclear magnetic resonance analysis and absorbance analysis.
[0049]
The decomposition rate of the epoxy group in the alicyclic epoxy compound of the present invention is preferably 20% or less. The decomposition rate of the epoxy group is a ratio in which the epoxy group is decomposed into another functional group such as a hydroxyl group. When the decomposition rate of the epoxy group exceeds 20%, the heat resistance of the cured epoxy resin tends to decrease. The decomposition rate of the epoxy group can be calculated from the theoretical epoxy equivalent when only the aromatic ring is hydrogenated and the actual epoxy equivalent of the product. The epoxy equivalent can be measured by a known method such as titration with perchloric acid. Further, the epoxy decomposition rate can be directly detected by gas chromatography or the like.
[0050]
Moreover, it is preferable that content of chlorine in the alicyclic epoxy compound of this invention is 0.3 weight% or less. Here, the chlorine content is the total amount of organic chlorine and inorganic chlorine contained in the epoxy compound. If the chlorine content exceeds 0.3% by weight, the moisture resistance, high-temperature electrical characteristics and weather resistance tend to be reduced, so it may be particularly unsuitable for use as an epoxy resin for electrical and electronic use. . The chlorine content can be measured by a method in which chlorine in the epoxy compound is reacted with biphenyl sodium and then titrated with silver nitrate.
[0051]
The alicyclic epoxy compound is mixed with a curing agent for epoxy resin, and if necessary, mixed with other alicyclic epoxy compound or auxiliary agent to obtain an alicyclic epoxy resin composition. Such an alicyclic epoxy resin composition can be used, for example, as an LED sealing material.
[0052]
In the present invention, it is necessary to reduce the platinum group element concentration in the alicyclic epoxy resin composition (LED sealing material). That is, the platinum group element concentration is set to 2 ppm or less similarly to the above, and the preferred embodiment is the same as above.
[0053]
Examples of the curing agent include amines, acid anhydrides, polyphenols, imidazoles, Bronsted acid salts, dicyandiamides, organic acid hydrazides, polymercaptans, and organic phosphines. Of these, acid anhydrides are preferred.
[0054]
Examples of the acid anhydrides include aromatic acid anhydrides such as phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, Examples thereof include cyclic aliphatic acid anhydrides such as methylhexahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, dodecenyl succinic anhydride, and trialkyltetrahydrophthalic anhydride. Among these, cycloaliphatic acid anhydrides are preferred, and saturated aliphatic hexahydrophthalic anhydride or methylhexahydrophthalic anhydride is particularly preferred.
[0055]
Each of the above-mentioned curing agents can be used alone or in combination of two or more, but it is preferable to adjust the ratio of the aromatic compound in the total curing agent to 10% by weight or less. The usage-amount of a hardening | curing agent is 0.01-200 weight part normally with respect to 100 weight part of alicyclic epoxy compounds, Preferably it is 0.1-150 weight part.
[0056]
Examples of the other alicyclic epoxy compounds typically include epoxidized products of cycloolefin, and specific examples thereof include 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate. Etc. The usage-amount of such an alicyclic epoxy compound is 0.01-10 weight ratio normally with respect to the alicyclic epoxy compound which concerns on the above-mentioned this invention, Preferably it is 0.05-1 weight ratio.
[0057]
Moreover, as said other adjuvant, in the case of an alicyclic epoxy resin composition, a hardening accelerator, antioxidant, a ultraviolet absorber, a reinforcing material, a filler, a coloring agent, a pigment, a flame retardant is mentioned. . In the case of an LED encapsulant, a phosphor may be used in addition to the above. The phosphor is excited by receiving light emitted from the light emitting element, and emits light having a wavelength longer than the excitation wavelength.
[0058]
An example of a light emitting device to which the LED sealing material of the present invention is applied is a group III nitrogen compound semiconductor. The dominant wavelength emitted from the light emitting element is preferably 350 nm or more and 550 nm or less. A particularly preferred dominant wavelength is 360 to 480 nm. The structure of an LED formed by sealing a light emitting element with a sealing material is described in, for example, Japanese Patent Application Laid-Open Nos. 59-54277 and 2927279. The LED encapsulant of the present invention is characterized by little deterioration over time with light of these wavelengths.
[0059]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded. The analysis methods and physical property measurement methods used in the following examples are as follows.
[0060]
(1) Analysis of rhodium concentration:
The rhodium concentration was analyzed by atomic absorption measurement using a sample dissolved in ethanol. Specifically, using “GF-AAS Spectra AA-300” manufactured by Varian Technologies Japan Limited as a device, a calibration curve is prepared with a rhodium standard solution, and ethanol is used according to the rhodium concentration in the sample. The dilution ratio was changed to 5 to 5000 times, and the analysis was performed so that this concentration was within the concentration range of the calibration curve. The lower limit of rhodium analysis of this method was 0.02 ppm.
[0061]
(2) Hydrogenation rate of aromatic ring:
Using a sample dissolved in ethyl acetate, the absorbance at 275 nm was measured and calculated by comparing with the absorbance of the starting aromatic epoxy compound. The dilution ratio with ethyl acetate was 10 to 1000 times depending on the hydrogenation rate.
[0062]
(3) Epoxy equivalent:
In accordance with JIS K7236-1995, titration was carried out with perchloric acid in the presence of acetic acid and cetyltrimethylammonium bromide, the generated hydrogen bromide was added to the epoxy group, and the end point was determined by the potential difference. The product (stock solution) was used as a sample.
[0063]
(4) Decomposition rate of epoxy group:
The following formula was used for calculation. In addition, the theoretical epoxy equivalent at the time of using "Epicoat 828US" (epoxy equivalent 186) by Japan Epoxy Resin Co. as a raw material was set to 192.
[0064]
[Expression 2]

[0065]
(5) Chlorine content:
After reacting chlorine in the epoxy compound with biphenyl sodium, titration with silver nitrate was performed for measurement.
[0066]
(6) Transmittance:
“UV-2400PC” manufactured by Shimadzu Corporation was used, a 1 cm cell was used, and distilled water was measured as a blank. The product (stock solution) was used as a sample.
[0067]
Example 1
In a 1 L induction stirring autoclave, 400 g of a bisphenol A type epoxy compound (“Epicoat 828EL” epoxy equivalent 186 manufactured by Japan Epoxy Resin Co., Ltd.), 100 g of tetrahydrofuran (THF), 1.2 g of 5 wt% rhodium / graphite catalyst as a hydrogenation catalyst After charging, the autoclave was purged with nitrogen and then purged with hydrogen. Thereafter, a hydrogenation reaction was performed at 110 ° C. and a hydrogen pressure of 8 MPa. Hydrogen absorption almost stopped in 3 hours.
[0068]
A reaction solvent (THF) was added to the reaction solution to dilute the epoxy resin concentration to 50% by weight, and then the hydrogenation catalyst was filtered from the reaction solution using 5C filter paper. That is, it filtered with the filtration pressure of 0.05 Mpa using the 1 L filter. The filtration time took 1 hour. Then, 16 g of powdered activated carbon having a pH of 5 to 8 (“Taiko K” dry product manufactured by Nimura Chemical) was mixed in the reaction solution for 30 minutes, and then the activated carbon was filtered off. Subsequently, the reaction solvent was distilled off while blowing a small amount of nitrogen at 100 ° C. under reduced pressure to obtain a transparent product. Tables 1 and 2 show the analysis results of the products.
[0069]
Example 2
In Example 1, the same operation as in Example 1 was performed except that the amount of activated carbon was changed from 16 g to 24 g. The results were as shown in Tables 1 and 2.
[0070]
Example 3
In Example 1, the same operation as in Example 1 was performed except that the reaction solvent was changed from tetrahydrofuran to ethyl acetate and the amount of activated carbon was changed from 16 g to 4 g. The results were as shown in Tables 1 and 2.
[0071]
Comparative Example 1
In Example 1, the same operation as in Example 1 was performed except that the adsorption treatment with activated carbon was not performed. The results were as shown in Tables 1 and 2.
[0073]
[Table 1]

[0074]
[Table 2]

[0075]
Example 4
750 kg of a bisphenol A type epoxy compound (“Epicoat 828US” epoxy equivalent 186 manufactured by Japan Epoxy Resin Co., Ltd.), 188 kg of ethyl acetate, and 2.3 kg of 5 wt% rhodium / graphite catalyst as a hydrogenation catalyst are charged into a 1300 L autoclave purged with nitrogen. The inside of the autoclave was replaced with hydrogen. Thereafter, a hydrogenation reaction was performed at 110 ° C. and a hydrogen pressure of 8 MPa for 8 hours.
The reaction solution was charged with 15 kg of activated carbon having a pH of 5 to 8 (“Dazai K” dry product manufactured by Nimura Chemical) and 560 kg of ethyl acetate and mixed for 30 minutes, and then the activated carbon was filtered off. Subsequently, the reaction solvent was distilled off while blowing a small amount of nitrogen at 100 ° C. under reduced pressure to obtain a transparent product. Tables 3 and 4 show the analysis results of the products.
[0076]
[Table 3]

[0077]
[Table 4]

[0078]
Example 5
100 g of epoxy resin obtained in Example 4, 83 g of 4-methylhexahydrophthalic anhydride (“MH-700” manufactured by Shin Nippon Rika Co., Ltd.) as a curing agent, curing catalyst (“Hishicolin PX-4ET manufactured by Nippon Chemical Industry Co., Ltd.) 1.0 g was mixed, cast to a thickness of 3 mm, precured at 100 ° C. for 3 hours, and then fully cured at 120 ° C. for 3 hours. After cooling, a test piece of 150 mm × 75 mm was cut out, and the transmittance at measurement wavelengths: 340 nm, 400 nm, and 700 nm was measured. Degradation evaluation by ultraviolet rays is performed by continuously irradiating the test piece with ultraviolet rays (UV) fluorescent lamps using an ultraviolet ray irradiation device (“Sew Tester Light Weather Control Meter DWPL-5R” manufactured by Suga Test Instruments Co., Ltd.). I did it. However, the black panel temperature was 63 ° C. and the irradiation intensity was 3 mW / cm ² . After 150 hours of UV irradiation, the transmittance was measured again at the above measurement wavelength. The results are shown in Table 5.
[0079]
Example 6
In Example 5, a test piece was prepared in the same manner as in Example 5 except that the epoxy resin mixture (mixing ratio 65:35 weight ratio) obtained in Example 4 and Comparative Example 1 was used as the epoxy resin. The transmittance was measured. The Rh concentration in the cured product was 1.7 ppm. The results are shown in Table 5.
[0080]
Comparative Example 2
In Example 5, a test piece was prepared in the same manner as in Example 5 except that the epoxy resin obtained in Comparative Example 1 (Rh concentration: 9 ppm) was used as the epoxy resin, and the transmittance was measured. The Rh concentration in the cured product was 5.0 ppm. The results are shown in Table 5.
[0081]
Comparative Example 3
100 g of aromatic epoxy resin (bisphenol type epoxy resin, “Epicoat 828US” manufactured by Japan Epoxy Resin Co., Ltd.), 90 g of curing agent (“MH-700” manufactured by Shin Nippon Chemical Co., Ltd.), curing catalyst (“Hishikolin manufactured by Nippon Chemical Industry Co., Ltd.) PX-4ET) ”1.0 g was mixed, cast to a thickness of 3 mm, precured at 100 ° C. for 3 hours, and then fully cured at 120 ° C. for 3 hours. Thereafter, test pieces were prepared in the same manner as in Example 5, and the transmittance was measured. The results are shown in Table 5.
[0082]
[Table 5]

[0083]
As shown in Table 5, in Examples 5 and 6, since the Rh concentration in the sealing material (cured epoxy resin) is low, the initial transmittance is also high, and the deterioration of the transmittance after UV 150 Hr irradiation is also small. . On the other hand, in the case of the comparative example 2 , since the Rh concentration in the sealing material is high, the deterioration of the transmittance after irradiation with UV150Hr is large. In the case of Comparative Example 3 , Rh is not included, but since the aromatic ring is included, the transmittance is greatly reduced.
[0084]
【The invention's effect】
According to the present invention described above, an alicyclic epoxy compound (encapsulant) is provided in which changes in hue reproducibility, uniformity, stability and the like are small and the decrease in radiant intensity of the LED with time is small. The industrial value of the present invention is remarkable.

Claims (6)

An alicyclic epoxy compound obtained by selectively hydrogenating an aromatic ring of an aromatic epoxy compound in the presence of a platinum group element-containing hydrogenation catalyst and then contacting with an adsorbent, wherein the concentration of the platinum group element is An alicyclic epoxy compound characterized by being 2 ppm or less. The alicyclic epoxy compound according to claim 1, wherein the platinum group element is rhodium. The alicyclic epoxy compound according to claim 1 or 2, which satisfies the following conditions (a) to (c).
(A) Hydrogenation rate of aromatic ring is 85% or more (b) Epoxy group decomposition rate is 20% or less (c) Chlorine content is 0.3% by weight or less An alicyclic epoxy resin mainly composed of an alicyclic epoxy compound obtained by selectively hydrogenating an aromatic ring of an aromatic epoxy compound in the presence of a platinum group element-containing hydrogenation catalyst and then contacting with an adsorbent An alicyclic epoxy resin composition having a platinum group element concentration of 2 ppm or less. The alicyclic epoxy resin composition according to claim 4, wherein the platinum group element is rhodium. A sealing material for a light emitting diode, comprising the alicyclic epoxy resin composition according to claim 4.