JP3632141B2 - Solid epoxy resin, method for producing the same, and curable composition containing solid epoxy resin - Google Patents

Description

【０００８】
（式（１）中、Ａ、Ｂは２官能フェノールから水素原子を除いた２価の残基であり、Ａ＝ＢでもＡ≠Ｂでも良い。また、ｎは繰り返し単位数で１より大きい整数である。）
【０００９】
【発明の実施の形態】
本発明に用いることのできる２官能フェノールとしては、ビスフェノールＡ、ビスフェノールＦ、ビスフェノールＳ、テトラブロモビスフェノールＡ、ビスフェノールＡＤ、ビスフェノールＣ、カテコール、レゾルシン、ハイドロキノン等が挙げられる。また、２官能のエポキシ樹脂としては、これらの２官能フェノール類の単独もしくは２種類以上を併用してエポキシ化したエポキシ樹脂や、水添ビスフェノールＡ、１、６ヘキサンジオール、ポリプロピレングリコール等のアルコールのジグリシジルエーテル類、ヘキサヒドロフタル酸、ダイマー酸等のジグリシジルエステル類等が挙げられるが、特にビスフェノール型エポキシ樹脂が好ましい。ビスフェノール型エポキシ樹脂としては、直接合成法により得られる低分子量のものが好ましく、汎用液状タイプとして市販されているビスフェノールＡ型やビスフェノールＦ型液状エポキシ樹脂が特に好ましい。
【００１０】
本発明のエポキシ樹脂の原料として用いられるフェノール性水酸基を有する樹脂は、前述の２官能エポキシ樹脂１モルに対して２官能フェノール類を１．２モル〜１０モルの範囲内で過剰に反応させるものであり、反応に用いる２官能フェノール類としては前述したフェノール類を単独または２種類以上併用して用いることができる。
【００１１】
また、エポキシ樹脂と２官能フェノール類との反応は、エポキシ基とは反応しない溶剤中で行う事ができ、具体的にはトルエン、キシレン等の芳香族炭化水素類、メチルイソブチルケトン、メチルエチルケトン、シクロヘキサノン、アセトン等のケトン類、ジエチレングリコールメチルエーテル、プロピレングリコールメチルエーテル、ジプロピレングリコールメチルエーテル等のグリコールエーテル類、ジエチルエーテル、ジブチルエーテル、エチルプロピルエーテル等の脂肪族エーテル類、ジオキサン、テトラヒドロフラン等の脂環式エーテル類が挙げられる。また反応はエポキシ樹脂とビスフェノール類とを一括で仕込んでも良く、２官能フェノール類にエポキシ樹脂を徐々に添加していっても良い。
【００１２】
また、反応は触媒存在下３０℃〜２２０℃の範囲で、３０分〜２０時間、好ましくは８０℃〜１６０℃で１〜６時間で行うことができる。また使用できる触媒としては水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物類、トリエチルアミン、ベンジルジメチルアミン等の３級アミン類、２−メチルイミダゾール、２−エチル４メチルイミダゾール等のイミダゾール類、テトラメチルアンモニウムブロマイド、ベンジルトリメチルアンモニウムブロマイド等の４級アンモニウム塩類、トリフェニルホスフィン、トリブチルホスフィン等のホスフィン類、ｎ−ブチルトリフェニルホスホニウムブロミド等のホスホニウム塩類等が挙げられる。触媒の使用量は反応に使用される２官能フェノール類に対して、１０〜１０，０００ｐｐｍの範囲内が好ましい。なおエポキシ基が消失した時点を反応の終点とする。
【００１３】
上記の反応は化学量論的には２官能エポキシ樹脂１モルに対して２官能フェノール２モルを反応させれば良いが、実際に反応するとエポキシ樹脂との反応により生成する末端フェノール性水酸基含有樹脂にもエポキシ樹脂が反応するために高分子量体が生成するのと未反応の２官能フェノールが残ってくる。高分子量体の生成を抑制するには大過剰の２官能フェノールを用いれば良いが、多量に未反応で残ってくるため工業的に不利になる。一方、未反応の２官能フェノールを低減するには反応時の２官能フェノールの仕込み量を減らせば良いが、高分子量体が多くなり固形化するのが難しくなる。このため２官能エポキシ樹脂１モルに対して２官能フェノールは１．２〜１０モル、より好ましくは１．５〜６モルの範囲とする。
【００１４】
反応終了後に残存してくる未反応の２官能フェノールを除去する方法としては、溶媒抽出法、再結晶法、分子蒸留法、分離膜による処理法、アルカリ水溶液に溶解して除去する方法等が挙げられ、何れの方法も用いることが出来るが、工業的には分子蒸留法やアルカリ水溶液溶解法が好ましい。
アルカリ水溶液溶解法としては、２官能エポキシ樹脂と２官能フェノールとの反応終了後に前述した溶媒を固形分が２０〜５０％になる様に添加して希釈した後、生成した末端フェノール性水酸基変性樹脂と未反応フェノール類のフェノール性水酸基の合計に対して１．０〜１．５モルに相当するアルカリ金属水酸化物を加えて反応し、アルカリ金属フェノラートを生成させる。反応は３０℃〜１００℃で、１０分〜５時間程度で実施することが出来る。次に溶剤に溶解している高分子量の生成物より、フェノール類のアルカリ金属フェノラートのみを水分離するものである。アルカリ金属水酸化物としては苛性ソーダや苛性カリの水溶液が好ましく、特に苛性ソーダの水溶液が好ましい。一回の分離操作で殆どの残存２官能フェノール類は除去することができるが、更に同様の操作を１〜２回繰り返すことにより完全に除去することができる。
残存する未反応フェノール類を除去した後、燐酸や燐酸ソーダ等の酸により中和及び水洗してから、溶剤を留去することにより、末端にフェノール性水酸基を有する固形樹脂が得られる。
【００１５】
本発明の固形エポキシ樹脂は、上記の様にして得られた末端にフェノール性水酸基を有する固形樹脂を、エピハロヒドリンによりアルカリ金属水酸化物の存在下でエポキシ化する公知の方法により得ることが出来る。エピハロヒドリンとしてはエピクロロヒドリン、エピブロモヒドリン、エピヨードヒドリン等が挙げられるがエピクロロヒドリンが好ましい。またアルカリ金属水酸化物としては苛性ソーダが好ましい。原料樹脂のフェノール性水酸基１モルに対してエピハロヒドリンを２〜３０モル、より好ましくは７〜１５モルの過剰量を使用し、アルカリ金属水酸化物の使用量は原料のフェノール性水酸基当量に対して０．７〜１．１モルの範囲である。反応温度は４０〜１２０℃の範囲で生成した水を系外に除去しながら反応させることが望ましい。
【００１６】
反応終了後に過剰のエピクロロヒドリンを留去した後、メチルイソブチルケトンやトルエン等の溶剤に溶解して、更に生成したエポキシ樹脂の加水分解性塩素に対し１〜５０モルのアルカリ金属水酸化物を添加して精製反応を行った後、副生成した塩を水洗または濾過等により除去し、溶媒を留去することにより、エポキシ当量が４５０〜２５００ｇ／ｅｑで低分子量成分を含有しない本発明のエポキシ樹脂を得ることができる。尚、エポキシ当量が４５０ｇ／ｅｑ以下のものは原料のフェノールを製造する際に生産性が悪いことと、２５００ｇ／ｅｑ以上のものはエポキシ化後の溶媒除去が困難となるためであり、より好ましくは５００〜１５００ｇ／ｅｑの範囲である。
また、本発明で２官能エポキシ樹脂がビスフェノール型エポキシ樹脂で、２官能フェノールがビスフェノールの時に得られるビスフェノール型の固形エポキシ樹脂の軟化点は、６０〜１５０℃の範囲が好ましい。６０℃以下では貯蔵中の耐ブロッキング性が悪くなり１５０℃を超えると加熱硬化時の流動性が悪くなるためであり、より好ましくは７０〜１２０℃の範囲である。
【００１７】
本発明の硬化性組成物は、少なくとも該固形エポキシ樹脂と硬化剤より成るものである。硬化剤としては、一般的にエポキシ樹脂の硬化剤として用いられている物を使用することができる。例えば、ジエチレントリアミン、トリエチレントリアミン、イソホロンジアミン、メタキシレンジアミン、ジアミノジフェニルメタン等のアミン類、無水フタル酸、無水ヘキサヒドロフタル酸、無水ナジック酸、無水トリメリット酸等の酸無水物、酸官能基末端のポリエステル樹脂、ダイマー酸とジエチレントリアミン、トリエチルアミン等との縮合物であるアミノポリアミド樹脂、メルカプタン基を末端に持つポリスルフィド樹脂、三弗化ホウ素アミンコンプレックス、フェノール類とホルマリンの縮合反応により得られるノボラック樹脂、フェノール性水酸基を有する各種の化合物、ジシアンジアミド、アジピン酸ジヒドラジド、セバシン酸ジヒドラジド等の有機酸ジヒドラジド、ポリイソシアネート類、イミダゾール類、レゾールフェノール樹脂、アミノ樹脂等が挙げられる。
【００１８】
本発明の硬化性組成物には、必要に応じて通常のエポキシ樹脂、例えばビスフェノールＡおよびビスフェノールＦ等のビスフェノール類のポリグリシジルエーテル、ポリエチレングリコールやポリプロピレングリコール等のアルコール類のポリグリシジルエーテル、ヘキサヒドロフタル酸やダイマー酸等のポリグリシジルエステル、ジアミノジフェニルメタン等のポリグリシジルアミン、フェノールノボラックやクレゾールノボラック等のノボラック型ポリグリシジルエーテル等の１種または数種類を選択して添加することができる。なお、これら通常のエポキシ樹脂の添加量はエポキシ樹脂１００重量％のうち７０重量％を超えると本発明の効果が得られなくなるため、７０重量％未満より好ましくは５０重量％未満とする。
また、必要に応じて充填剤、希釈剤、硬化促進剤等を添加することができる。本発明の硬化性組成物は、重防食塗料、粉体塗料、ＰＣＭ塗料、缶塗料等の塗料用途や土木・建設用途、接着用途、電気絶縁（粉体）用、半導体チップ仮止剤等の電気・電子部品用途及び積層板（プリント配線基盤）や炭素繊維強化プラスチック（ＣＦＲＰ）を始めとする各種複合材料用途等に適している。
【００１９】
【実施例】
以下、実施例により本発明を具体的に説明するが、これらに限定されるものではない。なお、特に断わらない限り実施例及び比較例中の「部」及び「％」は、それぞれ「重量部」及び「重量％」を示す。
実施例１．
攪拌機、温度計及び冷却管を備えた反応装置にＹＤ−１２８（東都化成社製；エポキシ当量１８６ｇ／ｅｑ、粘度１２５００ｍＰａ・ｓ／２５℃）を２００部とビスフェノールＡを６０８部仕込み、１２０℃に加熱溶融させた後、トリフェニルホスフィンを０．２部添加し、１５０℃で５時間反応した。その後、メチルイソブチルケトンを１１５３部仕込溶解し、１０．７％の水酸化ナトリウム水溶液を１９０８部仕込み、９０℃で３０分攪拌した後、靜置分液し、樹脂溶液層を燐酸で中和、更に水洗してからメチルイソブチルケトンを留去して、フェノール性水酸基当量が４３５ｇ／ｅｑ、軟化点が９７℃の末端フェノール性水酸基変性樹脂を得た。なお、水酸基当量は、テトラヒドロフランとメタノール３重量％の混合溶液中でフェノール性水酸基にテトラメチルアンモニウムヒドロキサイドを作用させて発色させ、分光光度計を用いて、３０５ｎｍにおける吸光度を測定し、予めビスフェノールＡを標準として同様の操作により作成した検量線により換算して求めた。また、軟化点はＪＩＳ Ｋ−７２３４により測定した。
【００２０】
攪拌機、温度計、滴下装置及び反応水回収装置を備えた反応器に、前記で得られた樹脂１３０部とエピクロロヒドリン２６０部を仕込み、樹脂を溶解させた。次いで系内を８０℃まで加熱し、４９％苛性ソーダ水溶液１８．６部を２時間にわたって滴下した。この間系内温度を８０〜８５℃に保ち、反応により生成する水及び苛性ソーダ水溶液の水をエピクロロヒドリンとの共沸混合物の形で反応系から除去し、蒸気を濃縮させてエピクロロヒドリンは系中に戻した。
次に、苛性ソーダ水溶液の滴下終了後、系内を常圧に戻し２時間熟成させた後、過剰のエピクロロヒドリンを蒸発除去し、生成したエポキシ樹脂及び塩化ナトリウムの混合物にＭＩＢＫ（メチルイソブチルケトン）を２４５部と水１５０部を加えて溶解させ、３０分静置後水を分液した。更に樹脂層に２０％苛性ソーダ水溶液を１４．１部加え、８０〜８５℃で２時間精製反応を行った。反応後、ＭＩＢＫ４０部と水１５０部を加え、８０℃まで加熱してから３０分静置し、水層を分離した。次に１０％燐酸ソーダ水溶液５部と水１００部を加え中和、分液し更に水１００部で水洗、分液してから脱水した。次に濾過してからＭＩＢＫを蒸発除去して、固形のエポキシ樹脂を得た。得られた固形エポキシ樹脂のエポキシ当量、軟化点、一般式におけるｎ＝０、ｎ＝１、ｎ＝２の含有量、数平均分子量、重量平均分子量、重量平均分子量／数平均分子量、ガラス転移温度を表１に示す。
【００２１】
実施例２．
実施例１と同様の反応装置にエポキシ樹脂としてＹＤ−１２８、３００部とビスフェノールＡを３６４．９部加え、１２０℃で溶融させた後、触媒としてトリフェニルホスフィンを０．２部加えて１７０℃で３時間反応させた。次にメチルイソブチルケトンを１６６６部仕込、６．６％の水酸化ナトリウム水溶液を１１５６部加えて、９０℃で３０分攪拌後靜置して、水層を分液した。更に樹脂溶液を、燐酸で中和、水洗してからメチルイソブチルケトンを留去することにより、水酸基当量６６４ｇ／ｅｑ、軟化点が１０５℃の末端フェノール性水酸基変性樹脂を得た。
攪拌機、温度計、滴下装置及び反応水回収装置を備えた反応器に、前記で得られた樹脂１５０部とエピクロロヒドリン３３０部を仕込み、樹脂を溶解させた。次いで系内を８０℃まで加熱し、４９％苛性ソーダ水溶液１６．２部を２時間にわたって滴下した。以下実施例１と同様に、熟成反応、エピクロロヒドリンの蒸発除去、ＭＩＢＫ溶解、水分離、精製反応、中和、水洗、脱水、濾過、ＭＩＢＫ蒸発除去操作を行って、固形のエポキシ樹脂を得た。得られたエポキシ樹脂の性状を表１に示す。
【００２２】
比較例１．
ビスフェノールＡ型液状エポキシ樹脂とビスフェノールＡとの間接法により合成される市販の汎用固形エポキシ樹脂、ＹＤ−９０２（東都化成社製）の性状を表１に示す。
比較例２．
ビスフェノールＡとエピクロロヒドリンとの直接法で合成される市販の汎用固形エポキシ樹脂、ＹＤ−０１３（東都化成社製）の性状を表１に示す。
【００２３】
表１における各項目の測定方法は次の方法によった。
・エポキシ当量；ＪＩＳ Ｋ−７２３６により測定した。
・ｎ＝０、ｎ＝１、ｎ＝２の含有量
数平均分子量、重量平均分子量、重量平均分子量／数平均分子量
以下の条件でＧＰＣの分析により、面積百分率によりｎ＝０〜２の含有量と数平均分子量、重量平均分子量を求めた。
ＧＰＣ分析条件
装置；東ソー社製ＨＬＣ−８０２Ａ
溶媒；ＴＨＦ
カラム；東ソー社製、ＴＳＫ−ＧＥＬ、Ｇ２０００Ｈを１本、Ｇ３０００Ｈを１本、Ｇ４０００Ｈを１本。
カラム温度；４０℃
移動相；ＴＨＦ
流量；１．５ｍｌ／ｍｉｎ．
検出器；東ソー社製ＲＩ−８型
試料濃度；５ｍｇ／ｌ
検量線；ビスフェノールＡ型エポキシ樹脂
・ガラス転移温度（Ｔｇ）
示差走査熱量計（ＤＳＣ）により昇温速度１０℃／分で測定した。
【００２４】
【表１】

【００２５】
実施例３．
実施例１で得られたエポキシ樹脂１００部、ジシアンジアミド３．８部、２ーメチルイミダゾール０．２部、酸化チタン４０部、流れ調整剤としてモダフロー０．５部をドライブレンド後にエクストルーダー（池貝鉄工社製ＰＣＭ−３０）で溶融混練を行い、冷却後に微粉砕して粉体塗料を得た。エクストルーダーの溶融混練条件は次の条件で行った。
シリンダー１；冷却、シリンダー２；８０℃、シリンダー３；９０℃、
ヘッド；１１０℃、メインスクリュー；２００ｒｐｍ、フィードスクリュー；２０ｒｐｍ。
得られた粉体塗料をサンドブラスト処理を行った軟鋼板（１５０×７０×０．８ｍｍ）に静電粉体塗装を行い、２００℃のオーブンで２０分焼き付けを行い膜厚１００μｍの塗装試験片を得た。粉体塗料の耐ブロッキング性、流れ性、焼き付け塗装試験片の塗膜の光沢、密着性、エリクセン、耐衝撃性等を評価して表２に示した。
【００２６】
実施例４．
実施例２で得られたエポキシ樹脂を用いた以外は実施例３と同様の配合、混練、冷却、粉砕を行って粉体塗料を得、これを静電粉体塗装後に焼付けて実施例４の塗装試験片を得た。得られた試験片について、実施例３と同様に評価を行いその結果を表２に示した。
【００２７】
比較例３．
比較例１のエポキシ樹脂を用いた以外は実施例３と同様の配合、混練、冷却、粉砕を行って粉体塗料を得、これを静電粉体塗装後に焼き付けて比較例３の塗装試験片を得た。得られた試験片について、実施例３と同様に評価を行いその結果を表２に示した。
比較例４．
比較例２のエポキシ樹脂を用いた以外は実施例４と同様の配合、混練、冷却、粉砕を行って粉体塗料を得、これを静電粉体塗装後に焼き付けて比較例２の塗装試験片を得た。得られた試験片について、実施例３と同様に評価を行いその結果を表２に示した。
【００２８】
表２における評価方法は下記のとおりである。
・耐ブロッキング性；粉体塗料を４０℃の恒温槽に１０日間入れたのちブロッキングの状態を調べた。（○；流動性がある。 ×；流動性がない。）
・流れ性；粉体塗料０．５ｇを採取して常温で１００ｋｇ／ｃｍ^２の圧力で直径１３ｍｍのタブレットを作成した。このタブレットを傾斜角が３０°に調整された軟鋼板にセットし、２００℃のオーブン中に放置して塗料の流れた距離を測定し、次式により流れ性を求めた。
流れ性＝（試料の流れた距離（ｍｍ）−１３（ｍｍ））／タブレットの厚さ（ｍｍ）
・光沢；ＪＩＳ Ｋ ５４００，６．７（６０゜鏡面反射率）に準じて光沢（％）を測定した。
・密着性；塗装試験片を水中に浸し、１００℃で２時間熱水処理を行った後、１ｍｍ碁盤目テープ剥離試験を行い、塗膜上に残った碁盤目数を測定した。
・エリクセン；エリクセン試験器を用いて、ポンチを１０ｍｍ押し出し、塗膜のピンホールの有無を調べた。（○；ピンホール無し、×；ピンホール有り）
・耐衝撃性；ＪＩＳ Ｋ−５４００に従いデュポン衝撃試験機により１／２インチの撃心とこれに対応する台を用いて１ｋｇの重りを５０ｃｍの高さより落下させて、塗膜の割れや剥がれを目視で判定した。（○；異状無し、×；塗膜に割れや剥がれ有り）
【００２９】
【表２】

【００３０】
【発明の効果】
本発明のエポキシ樹脂は、低分子量成分を含有していないため一般に市販されているエポキシ樹脂と比べて分子量分布がシャープで、流動性に優れる。またエポキシ当量６００ｇ／ｅｑ程度と低いものでもガラス転移温度が高いため耐ブロッキング性に優れる。更に該樹脂を用いた組成物もその硬化物は密着性や加工性、耐衝撃性等に優れる。
【図面の簡単な説明】
【図１】実施例１で得られたエポキシ樹脂のＧＰＣチャートである。
【図２】比較例１で用いたエポキシ樹脂のＧＰＣチャートである。
【図３】実施例１で得られたエポキシ樹脂の赤外吸収スペクトルチャートである。
【図４】実施例２で得られたエポキシ樹脂のＧＰＣチャートである。
【図５】比較例２で用いたエポキシ樹脂のＧＰＣチャートである。
【図６】実施例２で得られたエポキシ樹脂の赤外吸収スペクトルチャートである。
【符号の説明】
図１、図２及び図４、図５における縦軸は溶離量を、横軸は溶離時間を示す。尚、図１と図４は校正曲線における溶離時間（横軸）と分子量の対数（縦軸；ｌｏｇＭ）を同時にプロットしたものである。また、図３と図６における縦軸は吸収強度を、横軸は吸収波長を示す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel solid epoxy resin, a method for producing the solid epoxy resin, and a curable resin composition containing the solid epoxy resin, and more specifically, a novel solid epoxy resin substantially free of low molecular weight components. The present invention relates to a solid epoxy resin, a method for producing the same, and a curable resin composition comprising the solid epoxy resin and a curing agent.
[0002]
[Prior art]
Epoxy resins are used in a wide range of applications such as paints, electricity, civil engineering, and adhesives due to their excellent chemical and physical properties, and the performance required for each application is becoming increasingly sophisticated. For example, in the fields of powder coatings and molding materials, low epoxy equivalents and high fluidity are required, but conventional solid epoxy resins that have low epoxy equivalents can be easily blocked and storage stable. There was a problem of inferiority. In particular, considering blocking resistance, it is preferable that the low molecular weight component of n = 0 in the general formula (1) is smaller at the same softening point, and a solid epoxy resin having a sharp molecular weight distribution is desired from the viewpoint of fluidity. However, there has been no report on a solid epoxy resin containing no low molecular components of n = 0 and n = 1 or less, and no technique relating to the production method has been found.
[0003]
Conventionally, for solid epoxy resins, a direct synthesis method in which bisphenols and epihalhydrin are reacted in the presence of an alkali metal hydroxide, and a polyaddition reaction of bisphenols with the epoxy resin obtained by this direct synthesis method. Indirect synthesis methods are known. Solid epoxy resins produced by the direct synthesis method and the indirect synthesis method are known to have a large difference in molecular weight distribution. In the case of the direct synthesis method, n = 0, 1, 2, 3,. Even and odd polymerization degrees all appear, but in the case of the indirect synthesis method, peaks of even polymerization degrees appear mainly as n = 0, 2, 4. In any method, the solid epoxy resins obtained by these conventionally known methods are obtained as a mixture of molecules having various degrees of polymerization, and include low molecular weight components of n = 0 and n = 1. Yes. For example, a commercially available bisphenol A-type solid epoxy resin YD-013 (manufactured by Tohto Kasei Co., Ltd .; epoxy equivalent 853 g / eq; softening point 91 ° C.) is determined by area percentage by GPC in the general formula (1). And n = 0 (molecular weight 340) is 3.5%, n = 1 (molecular weight 624) is 6.3%, YD-902 by the indirect synthesis method (epoxy equivalent 655 g / eq; softening point 86 ° C.) In addition, n = 0 includes 8.4% and n = 1 includes 1.6%.
[0004]
Conventionally, as a method of removing low molecular components in these solid epoxy resins, for example, a method of removing low molecular components by molecular distillation is known. However, in this method, it is possible to remove components of n = 1 or more. It is difficult and requires a high temperature during distillation, so that there is a problem that the solid epoxy resin decomposes by heat, and in order to completely remove the n = 0 component, it is necessary to perform several distillations, and industrially Was also not an advantageous method. JP-A-61-231018 reports a method of removing low molecular weight components by contacting with a hydrocarbon solvent such as xylene. In this method, only components of n = 0 or n = 1 are selectively used. However, if other components are also removed together, the low molecular weight component cannot be completely removed. JP-A-1-230678 reports a purified bisphenol type epoxy resin in which a high molecular weight epoxy resin having a number average molecular weight of 2000 to 6000 is contacted with a lower alcohol in a parent solvent to reduce or remove components having a molecular weight of 800 or less. Yes. However, in this method, the epoxy resin has a high molecular weight, so that the content of low molecular components of n = 0 or n = 1 is reduced or reduced by 2% or less, but the washing operation with alcohol is repeated five times. However, these low molecular weight components were not completely removed, and this was not an industrially advantageous method.
[0005]
[Problems to be solved by the present invention]
The inventors of the present invention have arrived at the present invention as a result of intensive studies on a method for obtaining a solid epoxy resin substantially free of low molecular components. That is, the present invention provides a solid epoxy resin substantially free of low-molecular components of n = 0 or n = 1 that could not be obtained by a conventionally known production method, a production method thereof, and a composition thereof. To do.
[0006]
[Means for Solving the Problems]
The gist of the present invention is that a product obtained by reacting 1 mol of a bifunctional epoxy resin with 1.2 mol to 10 mol of a bifunctional phenol and then removing the remaining unreacted bifunctional phenol, Epoxy equivalent is 450 to 2,500 g / eq, characterized by epoxidizing with epihalohydrin, and contains substantially no component having a repeating unit number n of 1 or less represented by general formula (1) The present invention provides a solid epoxy resin and a curable composition thereof.
[0007]
[Chemical formula 2]

[0008]
(In the formula (1), A and B are divalent residues obtained by removing a hydrogen atom from a bifunctional phenol, and A = B or A ≠ B. N is an integer greater than 1 in terms of the number of repeating units. .)
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the bifunctional phenol that can be used in the present invention include bisphenol A, bisphenol F, bisphenol S, tetrabromobisphenol A, bisphenol AD, bisphenol C, catechol, resorcin, and hydroquinone. In addition, as the bifunctional epoxy resin, an epoxy resin obtained by epoxidizing these bifunctional phenols singly or in combination of two or more kinds, alcohols such as hydrogenated bisphenol A, 1, 6 hexanediol, polypropylene glycol, etc. Examples include diglycidyl ethers, diglycidyl esters such as hexahydrophthalic acid and dimer acid, and bisphenol type epoxy resins are particularly preferable. As the bisphenol type epoxy resin, those having a low molecular weight obtained by a direct synthesis method are preferable, and bisphenol A type and bisphenol F type liquid epoxy resins commercially available as general-purpose liquid types are particularly preferable.
[0010]
The resin having a phenolic hydroxyl group used as a raw material for the epoxy resin according to the present invention is obtained by excessively reacting a bifunctional phenol within a range of 1.2 mol to 10 mol with respect to 1 mol of the above-mentioned bifunctional epoxy resin. As the bifunctional phenols used in the reaction, the above-described phenols can be used alone or in combination of two or more.
[0011]
The reaction between the epoxy resin and the bifunctional phenols can be carried out in a solvent that does not react with the epoxy group. Specifically, aromatic hydrocarbons such as toluene and xylene, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone. , Ketones such as acetone, glycol ethers such as diethylene glycol methyl ether, propylene glycol methyl ether and dipropylene glycol methyl ether, aliphatic ethers such as diethyl ether, dibutyl ether and ethylpropyl ether, and alicyclic rings such as dioxane and tetrahydrofuran And formula ethers. In addition, the reaction may be performed by adding an epoxy resin and bisphenols all at once, and the epoxy resin may be gradually added to the bifunctional phenols.
[0012]
The reaction can be carried out in the presence of a catalyst in the range of 30 ° C. to 220 ° C. for 30 minutes to 20 hours, preferably 80 ° C. to 160 ° C. for 1 to 6 hours. Examples of catalysts that can be used include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, tertiary amines such as triethylamine and benzyldimethylamine, imidazoles such as 2-methylimidazole and 2-ethyl4-methylimidazole, Examples include quaternary ammonium salts such as tetramethylammonium bromide and benzyltrimethylammonium bromide, phosphines such as triphenylphosphine and tributylphosphine, and phosphonium salts such as n-butyltriphenylphosphonium bromide. The amount of the catalyst used is preferably in the range of 10 to 10,000 ppm with respect to the bifunctional phenols used in the reaction. The time when the epoxy group disappears is taken as the end point of the reaction.
[0013]
The above reaction may be carried out stoichiometrically by reacting 2 mol of bifunctional phenol with 1 mol of bifunctional epoxy resin, but terminal phenolic hydroxyl group-containing resin produced by reaction with epoxy resin when actually reacted. In addition, since the epoxy resin reacts, a high molecular weight product is formed and an unreacted bifunctional phenol remains. A large excess of bifunctional phenol may be used to suppress the formation of a high molecular weight product, but a large amount remains unreacted, which is industrially disadvantageous. On the other hand, in order to reduce the unreacted bifunctional phenol, it is sufficient to reduce the amount of the bifunctional phenol charged during the reaction, but the amount of high molecular weight increases and it becomes difficult to solidify. For this reason, bifunctional phenol is 1.2-10 mol with respect to 1 mol of bifunctional epoxy resins, More preferably, it shall be the range of 1.5-6 mol.
[0014]
Examples of methods for removing unreacted bifunctional phenol remaining after completion of the reaction include solvent extraction, recrystallization, molecular distillation, separation membrane treatment, and dissolution in an alkaline aqueous solution. Any method can be used, but industrially, a molecular distillation method or an alkaline aqueous solution dissolution method is preferable.
As the alkaline aqueous solution dissolution method, after the reaction between the bifunctional epoxy resin and the bifunctional phenol is completed, the above-described solvent is added and diluted so that the solid content is 20 to 50%, and then the resulting terminal phenolic hydroxyl group-modified resin is formed. Then, an alkali metal hydroxide corresponding to 1.0 to 1.5 mol is added to the total of the phenolic hydroxyl groups of the unreacted phenols and reacted to form an alkali metal phenolate. The reaction can be carried out at 30 ° C. to 100 ° C. for about 10 minutes to 5 hours. Next, only the alkali metal phenolate of phenol is separated from the high molecular weight product dissolved in the solvent. As the alkali metal hydroxide, an aqueous solution of caustic soda or caustic potash is preferable, and an aqueous solution of caustic soda is particularly preferable. Although most of the remaining bifunctional phenols can be removed by a single separation operation, it can be completely removed by repeating the same operation once or twice.
After removing the remaining unreacted phenols, the resin is neutralized with an acid such as phosphoric acid or sodium phosphate and washed with water, and then the solvent is distilled off to obtain a solid resin having a phenolic hydroxyl group at the terminal.
[0015]
The solid epoxy resin of the present invention can be obtained by a known method of epoxidizing a solid resin having a phenolic hydroxyl group at the terminal obtained as described above with epihalohydrin in the presence of an alkali metal hydroxide. Examples of the epihalohydrin include epichlorohydrin, epibromohydrin, epiiodohydrin, and the like, but epichlorohydrin is preferable. As the alkali metal hydroxide, caustic soda is preferable. An excess of 2 to 30 mol, more preferably 7 to 15 mol of epihalohydrin is used per 1 mol of phenolic hydroxyl group of the raw material resin, and the amount of alkali metal hydroxide used is relative to the phenolic hydroxyl group equivalent of the raw material. The range is 0.7 to 1.1 mol. It is desirable that the reaction is carried out while removing the water generated in the reaction temperature range of 40 to 120 ° C. out of the system.
[0016]
Excess epichlorohydrin is distilled off after completion of the reaction, and then dissolved in a solvent such as methyl isobutyl ketone or toluene, and further 1 to 50 mol of alkali metal hydroxide with respect to the hydrolyzable chlorine of the produced epoxy resin. After the purification reaction was performed by adding the salt, the by-produced salt was removed by washing or filtration, and the solvent was distilled off, whereby the epoxy equivalent was 450-2500 g / eq and no low molecular weight component was contained. An epoxy resin can be obtained. In addition, when the epoxy equivalent is 450 g / eq or less, productivity is poor when producing the raw material phenol, and 2500 g / eq or more is because it is difficult to remove the solvent after epoxidation. Is in the range of 500-1500 g / eq.
In the present invention, the softening point of the bisphenol-type solid epoxy resin obtained when the bifunctional epoxy resin is a bisphenol-type epoxy resin and the bifunctional phenol is bisphenol is preferably in the range of 60 to 150 ° C. If it is 60 ° C. or lower, blocking resistance during storage deteriorates, and if it exceeds 150 ° C., fluidity at the time of heat curing deteriorates, more preferably in the range of 70 to 120 ° C.
[0017]
The curable composition of the present invention comprises at least the solid epoxy resin and a curing agent. As a hardening | curing agent, the thing generally used as a hardening | curing agent of an epoxy resin can be used. For example, amines such as diethylenetriamine, triethylenetriamine, isophoronediamine, metaxylenediamine, diaminodiphenylmethane, acid anhydrides such as phthalic anhydride, hexahydrophthalic anhydride, nadic acid anhydride, trimellitic anhydride, acid functional group terminal Polyester resins, aminopolyamide resins that are condensates of dimer acid and diethylenetriamine, triethylamine, etc., polysulfide resins having terminal mercaptan groups, boron trifluoride amine complexes, novolac resins obtained by the condensation reaction of phenols and formalin, Various compounds having a phenolic hydroxyl group, organic acid dihydrazides such as dicyandiamide, adipic acid dihydrazide, sebacic acid dihydrazide, polyisocyanates, imidazoles, resole Lumpur resins, amino resins.
[0018]
The curable composition of the present invention contains, as necessary, a normal epoxy resin, for example, polyglycidyl ethers of bisphenols such as bisphenol A and bisphenol F, polyglycidyl ethers of alcohols such as polyethylene glycol and polypropylene glycol, hexahydro One or several kinds of polyglycidyl esters such as phthalic acid and dimer acid, polyglycidyl amines such as diaminodiphenylmethane, and novolac-type polyglycidyl ethers such as phenol novolak and cresol novolak can be selected and added. In addition, since the effect of this invention will not be acquired when the addition amount of these normal epoxy resins exceeds 70 weight% out of 100 weight% of epoxy resins, it is less than 70 weight%, Preferably it is less than 50 weight%.
Moreover, a filler, a diluent, a hardening accelerator, etc. can be added as needed. The curable composition of the present invention can be used in coatings such as heavy anticorrosion coatings, powder coatings, PCM coatings, can coatings, civil engineering / construction applications, bonding applications, electrical insulation (powder) applications, semiconductor chip temporary fixing agents, etc. It is suitable for electrical / electronic component applications and various composite materials including laminates (printed circuit boards) and carbon fiber reinforced plastics (CFRP).
[0019]
【Example】
Hereinafter, the present invention will be specifically described by way of examples, but is not limited thereto. Unless otherwise specified, “parts” and “%” in Examples and Comparative Examples represent “parts by weight” and “% by weight”, respectively.
Example 1.
A reactor equipped with a stirrer, a thermometer and a cooling tube was charged with 200 parts of YD-128 (manufactured by Tohto Kasei Co., Ltd .; epoxy equivalent 186 g / eq, viscosity 12500 mPa · s / 25 ° C.) and 608 parts of bisphenol A at 120 ° C. After melting by heating, 0.2 part of triphenylphosphine was added and reacted at 150 ° C. for 5 hours. Thereafter, 1153 parts of methyl isobutyl ketone was charged and dissolved, 1908 parts of a 10.7% aqueous sodium hydroxide solution was added, and the mixture was stirred at 90 ° C. for 30 minutes, followed by liquid separation, and the resin solution layer was neutralized with phosphoric acid. Further, after washing with water, methyl isobutyl ketone was distilled off to obtain a terminal phenolic hydroxyl group-modified resin having a phenolic hydroxyl group equivalent of 435 g / eq and a softening point of 97 ° C. The hydroxyl group equivalent was determined by allowing tetramethylammonium hydroxide to act on a phenolic hydroxyl group in a mixed solution of tetrahydrofuran and methanol at 3% by weight, and measuring the absorbance at 305 nm using a spectrophotometer. Was converted by a calibration curve prepared by the same operation as a standard. The softening point was measured according to JIS K-7234.
[0020]
In a reactor equipped with a stirrer, a thermometer, a dropping device, and a reaction water recovery device, 130 parts of the resin obtained above and 260 parts of epichlorohydrin were charged to dissolve the resin. Next, the system was heated to 80 ° C., and 18.6 parts of a 49% sodium hydroxide aqueous solution was added dropwise over 2 hours. During this time, the temperature in the system is kept at 80 to 85 ° C., water generated by the reaction and water of the caustic soda aqueous solution are removed from the reaction system in the form of an azeotrope with epichlorohydrin, and the vapor is concentrated to epichlorohydrin. Returned to the system.
Next, after the dripping of the caustic soda aqueous solution is completed, the system is returned to normal pressure and aged for 2 hours. Then, excess epichlorohydrin is removed by evaporation, and MIBK (methyl isobutyl ketone) is added to the resulting mixture of epoxy resin and sodium chloride. ) And 245 parts and 150 parts of water were added and dissolved, and after standing for 30 minutes, water was separated. Further, 14.1 parts of a 20% aqueous sodium hydroxide solution was added to the resin layer, and a purification reaction was performed at 80 to 85 ° C. for 2 hours. After the reaction, 40 parts of MIBK and 150 parts of water were added, heated to 80 ° C. and allowed to stand for 30 minutes to separate the aqueous layer. Next, 5 parts of a 10% sodium phosphate aqueous solution and 100 parts of water were added to neutralize and separate, and after further washing with 100 parts of water and liquid separation, dehydration. Next, after filtration, MIBK was removed by evaporation to obtain a solid epoxy resin. Epoxy equivalent of the obtained solid epoxy resin, softening point, content of n = 0, n = 1, n = 2 in the general formula, number average molecular weight, weight average molecular weight, weight average molecular weight / number average molecular weight, glass transition temperature Is shown in Table 1.
[0021]
Example 2
In the same reactor as in Example 1, 300 parts of YD-128 as epoxy resin and 364.9 parts of bisphenol A were added and melted at 120 ° C. Then, 0.2 part of triphenylphosphine was added as a catalyst and 170 ° C. For 3 hours. Next, 1666 parts of methyl isobutyl ketone was charged, 1156 parts of a 6.6% aqueous sodium hydroxide solution was added, and the mixture was stirred at 90 ° C. for 30 minutes and then placed to separate the aqueous layer. Further, the resin solution was neutralized with phosphoric acid and washed with water, and then methyl isobutyl ketone was distilled off to obtain a terminal phenolic hydroxyl group-modified resin having a hydroxyl group equivalent of 664 g / eq and a softening point of 105 ° C.
In a reactor equipped with a stirrer, a thermometer, a dropping device and a reaction water recovery device, 150 parts of the resin obtained above and 330 parts of epichlorohydrin were charged to dissolve the resin. Next, the system was heated to 80 ° C., and 16.2 parts of 49% aqueous sodium hydroxide solution was added dropwise over 2 hours. In the same manner as in Example 1, aging reaction, epichlorohydrin evaporative removal, MIBK dissolution, water separation, purification reaction, neutralization, water washing, dehydration, filtration, MIBK evaporative removal operation were performed to obtain a solid epoxy resin. Obtained. Table 1 shows the properties of the obtained epoxy resin.
[0022]
Comparative Example 1
Table 1 shows properties of a commercially available general-purpose solid epoxy resin, YD-902 (manufactured by Tohto Kasei Co., Ltd.) synthesized by the indirect method of bisphenol A type liquid epoxy resin and bisphenol A.
Comparative Example 2
Table 1 shows the properties of YD-013 (manufactured by Tohto Kasei Co., Ltd.), a commercially available general-purpose solid epoxy resin synthesized by a direct method of bisphenol A and epichlorohydrin.
[0023]
The measuring method of each item in Table 1 was based on the following method.
Epoxy equivalent: measured according to JIS K-7236.
-Content of n = 0, n = 1, n = 2 Number average molecular weight, weight average molecular weight, weight average molecular weight / number average molecular weight According to GPC analysis, content of n = 0-2 by area percentage The number average molecular weight and the weight average molecular weight were determined.
GPC analysis condition apparatus; HLC-802A manufactured by Tosoh Corporation
Solvent; THF
Column: manufactured by Tosoh Corporation, one TSK-GEL and G2000H, one G3000H, and one G4000H.
Column temperature: 40 ° C
Mobile phase: THF
Flow rate: 1.5 ml / min.
Detector; RI-8 type sample concentration manufactured by Tosoh Corporation; 5 mg / l
Calibration curve: bisphenol A type epoxy resin, glass transition temperature (Tg)
It measured with the temperature increase rate of 10 degree-C / min with the differential scanning calorimeter (DSC).
[0024]
[Table 1]

[0025]
Example 3 FIG.
100 parts of the epoxy resin obtained in Example 1, 3.8 parts of dicyandiamide, 0.2 part of 2-methylimidazole, 40 parts of titanium oxide, and 0.5 part of Modaflow as a flow control agent were dry blended before an extruder (Ikegai Iron Works). PCM-30) was used for melt kneading, and after cooling, pulverized to obtain a powder coating material. Extruder melt kneading conditions were as follows.
Cylinder 1; cooling, cylinder 2; 80 ° C., cylinder 3; 90 ° C.
Head: 110 ° C., main screw: 200 rpm, feed screw: 20 rpm.
The obtained powder coating is coated with electrostatic powder on a sandblasted mild steel plate (150 x 70 x 0.8 mm) and baked in an oven at 200 ° C for 20 minutes to obtain a coating specimen having a thickness of 100 µm. Obtained. The blocking resistance and flowability of the powder coating material, and the gloss, adhesion, elixsen, impact resistance and the like of the coating film of the baked coating test piece were evaluated and shown in Table 2.
[0026]
Example 4
Except for using the epoxy resin obtained in Example 2, the same composition, kneading, cooling, and pulverization as in Example 3 were performed to obtain a powder paint, which was baked after electrostatic powder coating, and A painted specimen was obtained. The obtained test pieces were evaluated in the same manner as in Example 3, and the results are shown in Table 2.
[0027]
Comparative Example 3
Except for using the epoxy resin of Comparative Example 1, the same composition, kneading, cooling, and pulverization as in Example 3 were performed to obtain a powder coating, which was baked after electrostatic powder coating, and the coating test piece of Comparative Example 3 Got. The obtained test pieces were evaluated in the same manner as in Example 3, and the results are shown in Table 2.
Comparative Example 4
Except for using the epoxy resin of Comparative Example 2, the same composition, kneading, cooling, and pulverization as in Example 4 were carried out to obtain a powder coating, which was baked after electrostatic powder coating, and a coating test piece of Comparative Example 2 Got. The obtained test pieces were evaluated in the same manner as in Example 3, and the results are shown in Table 2.
[0028]
The evaluation methods in Table 2 are as follows.
Blocking resistance: The powder coating was placed in a constant temperature bath at 40 ° C. for 10 days, and then the blocking state was examined. (○: fluidity ×: no fluidity)
Flowability: 0.5 g of powder coating material was sampled and a tablet having a diameter of 13 mm was prepared at a normal temperature and a pressure of 100 kg / cm ² . This tablet was set on a mild steel plate whose inclination angle was adjusted to 30 °, and was left in an oven at 200 ° C. to measure the distance that the paint flowed, and the flowability was obtained by the following equation.
Flowability = (Distance flowed by sample (mm) −13 (mm)) / tablet thickness (mm)
Gloss: Gloss (%) was measured according to JIS K 5400, 6.7 (60 ° specular reflectance).
-Adhesiveness: A coating test piece was immersed in water and subjected to hydrothermal treatment at 100 ° C for 2 hours, and then a 1 mm cross-cut tape peeling test was performed to measure the number of cross-cuts remaining on the coating film.
Eriksen: Using an Eriksen tester, the punch was extruded 10 mm, and the presence or absence of pinholes in the coating was examined. (○: No pinhole, ×: With pinhole)
・ Impact resistance: according to JIS K-5400, using a DuPont impact tester and dropping a 1 kg weight from a height of 50 cm using a ½ inch striker and a stand corresponding thereto, the coating film is cracked or peeled off. Judgment was made visually. (○: No abnormality, ×: Cracking or peeling on the coating)
[0029]
[Table 2]

[0030]
【The invention's effect】
Since the epoxy resin of the present invention does not contain a low molecular weight component, it has a sharp molecular weight distribution and excellent fluidity compared to commercially available epoxy resins. Further, even a low epoxy equivalent of about 600 g / eq is excellent in blocking resistance because of its high glass transition temperature. Furthermore, the cured product of the composition using the resin is excellent in adhesion, workability, impact resistance and the like.
[Brief description of the drawings]
1 is a GPC chart of an epoxy resin obtained in Example 1. FIG.
2 is a GPC chart of an epoxy resin used in Comparative Example 1. FIG.
3 is an infrared absorption spectrum chart of the epoxy resin obtained in Example 1. FIG.
4 is a GPC chart of the epoxy resin obtained in Example 2. FIG.
5 is a GPC chart of an epoxy resin used in Comparative Example 2. FIG.
6 is an infrared absorption spectrum chart of the epoxy resin obtained in Example 2. FIG.
[Explanation of symbols]
1, 2, 4, and 5, the vertical axis represents the elution amount, and the horizontal axis represents the elution time. 1 and 4 are plots of the elution time (horizontal axis) and the logarithm of molecular weight (vertical axis; log M) at the same time in the calibration curve. 3 and 6, the vertical axis represents the absorption intensity, and the horizontal axis represents the absorption wavelength.

Claims (5)

After reacting 1.2 mol to 10 mol of bifunctional phenol with respect to 1 mol of bifunctional epoxy resin, the remaining unreacted bifunctional phenol is removed, and the obtained product is epoxidized with epihalohydrin. The manufacturing method of the solid epoxy resin characterized by these. The value of the repeating unit number n represented by the following general formula (1) obtained by the method according to claim 1 does not contain a component of 1 or less, and the epoxy equivalent is within 450 to 2,500 g / eq. Characteristic solid epoxy resin.

(In the formula (1), A and B are divalent residues obtained by removing a hydrogen atom from a bifunctional phenol, and A = B or A ≠ B. N is an integer greater than 1 in terms of the number of repeating units. .) The value of the repeating unit number n represented by the following general formula (1) obtained by the method according to claim 1 does not contain a component of 1 or less, an epoxy equivalent is within 450 to 2,500 g / eq, and A solid epoxy resin characterized by being a bisphenol type solid epoxy resin having a softening point of 60 to 150 ° C.

(In the formula (1), A and B are divalent residues obtained by removing a hydrogen atom from a bifunctional phenol, and A = B or A ≠ B. N is an integer greater than 1 in terms of the number of repeating units. .) A curable composition comprising an epoxy resin and a curing agent, wherein 30% by weight or more of the epoxy resin is the epoxy resin according to claim 2. A curable composition comprising an epoxy resin and a curing agent, wherein the epoxy resin according to claim 3 is 30% by weight or more of the epoxy resin.

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