JP4039938B2 - Method for producing electrophotographic photosensitive member and polycarbonate resin for coating solution for electrophotographic photosensitive member - Google Patents

Description

【００１８】
又は単結合を示し、Ｒ1及びＲ2は水素原子、炭素数１〜２０のアルキル基、置換されていてもよいアリール基、又は、ハロゲン化アルキル基を示し、Ｚは４〜２０の置換又は非置換の炭素環を示し、Ｙ1ないしＹ8は、各々独立に、水素原子、ハロゲン原子、炭素数１〜２０のアルキル基、置換されていてもよいアリール基、又は、ハロゲン化アルキル基を示す。）
【００１９】
特に好適な芳香族ジオール類には、２，２−ビス（４−ヒドロキシフェニル）プロパン（ビスフェノールＡ）、２，２−ビス（３，５−ジメチル−４−ヒドロキシフェニル）プロパン、１，１−ビス（４−ヒドロキシフェニル）シクロヘキサン（ビスフェノールＺ）、及び１，１−ビス（４−ヒドロキシフェニル）−３，３，５−トリメチルシクロヘキサンが含まれる。
【００２０】
本発明において分子量調節剤として使用される一般式Ａｒ−ＯＨで表されるモノフェノール類には、種々のフェノール類、例えば、通常のフェノールのほか、ｐ−ｔ−ブチルフェノール及びｐ−クレゾールのような炭素数１〜２０のアルキルフェノール、並びにｐ−クロロフェノール及び２，４，６−トリブロモフェノールのようなハロゲン化フェノールが含まれる。なかでもフェノール、及びｐ−イソプロピルフェノール、ｐ−ドデシルフェノール、ｐ−ｔ−ブチルフェノール等のパラ位に炭素数１〜２０のアルキル基が置換したフェノール類が、更に好適である。モノフェノール類の使用量は、目的とする縮合体の分子量によっても異なるが、通常、原料芳香族ジオール類に対して、０．５〜１０重量％の量で使用される。
なお、Ａｒは置換されていても良い芳香族環残基を表すが、置換基としては、分子量調節剤としての機能を有するためには基質のカーボネート形成化合物又はビフェノール類と反応する水酸基、メルカプト基、アミノ基等は除かれる。芳香族環上の置換基は、これら反応性の置換基以外であれば特に制限はない。
【００２１】
本発明のカーボネートオリゴマー組成物は、芳香族ジオール類とカーボネート形成化合物とをモノフェノール類の存在下に反応させて得られる、粘度平均分子量５００〜１００００のカーボネートオリゴマー組成物である。ここでいう組成物とは、反応により得られたカーボネートオリゴマーの他に、反応により生成する副生物や若干残った原料を含むものである。
【００２２】
本発明のカーボネートオリゴマー組成物は、該オリゴマー組成物中の仕込みモノフェノール類に対する未反応モノフェノール類の割合が５０％以下であり、また、下記一般式（１）で表される化合物の含有量が０．００５重量％以下であることが必須である。一般式（１）で表される化合物は、一般式Ａｒ−ＯＨで表されるモノフェノール類の水酸基末端がホスゲン等のカーボネート形成化合物と反応して生成した化合物であり、例えばモノフェノール類としてｐ−ｔ−ブチルフェノールを使用した場合、前記低分子化合物は下記式（５）で表される化合物である。（以下、この化合物を「ＰＴＢＰＣ」と略記することがある。）
【００２３】
【化２】

【００２４】
（但し、Ａｒは置換されていてもよい芳香族環残基を表す。）
【００２５】
【化３】

【００２６】
（式中、ｔ−Ｂｕは第３級ブチル基、−Ｐｈ−はフェニレン基を示す。）
【００２７】
一般式（１）で表される化合物の含有量は、好ましくは０．００３重量％未満、さらに好ましくは０．００１重量％未満である。前記範囲内とするには、例えば、原料芳香族ジオール類とカーボネート形成化合物とをモノフェノール類を分子量調節剤として反応させてオリゴマー組成物を得る場合、モノフェノール類を、カーボネート形成化合物消費直後、具体的には、カーボネート形成化合物の濃度が０．００１重量％以下となった後に、モノフェノール類を混合することで対応可能となる。また、オリゴマー組成物中に存在する未反応モノフェノールの量は反応に使用したモノフェノールに対して５０％以下であり、好ましくは３０％以下であり、特に好ましくは１０％以下である。
【００２８】
オリゴマー組成物中のモノフェノール濃度を上記範囲にするために、モノフェノールはオリゴマー組成物の分子伸長の中途で混合する。なお、ここでカーボネート形成化合物の濃度とは、原料である芳香族ジオール化合物、カーボネート形成化合物及び生成物であるカーボネートオリゴマー組成物、並びに分子量伸長中途のカーボネートオリゴマー組成物の合計量に対する、消費されていない原料カーボネート形成化合物の量（重量割合）を意味する。
【００２９】
カーボネート形成化合物の共存下でモノフェノール類を添加すると一般式（１）に示すようなモノフェノール類同士の縮合物（炭酸ジフェニル類）が多く生成し、目標とする分子量のポリカーボネート樹脂が得られにくく、電子写真感光体のバインダー樹脂として使用する場合電気特性が悪化し好ましくない。また、モノフェノール類の添加を極端に遅らせた場合、得られるポリカーボネート樹脂の分子末端はＯＨ基量が多くなり、その結果、分子量に再現性がないばかりか分子量分布の低分子側に特異な肩を持った製品となり、成型時にはな垂れを生じたりするような弊害が多くあまり好ましくない。
【００３０】
本発明者らは分子末端のＯＨ基量を２０μｅｑ／ｇ以下、また分子総末端基量に対する分子末端モノフェノール基量の割合が９０％以上にする方法を検討した結果、驚くべきことに分子量調節剤をカーボネート形成性化合物の消費が終了した直後から、分子量伸長が始まる前での間に添加することで達成できることを見いだした。
【００３１】
芳香族ジオール化合物と、カーボネート形成化合物とから得られるカーボネートオリゴマー組成物は、下記一般式（２）で表される構造単位を有する。
【００３２】
【化４】

【００３３】
又は単結合を示し、Ｒ¹及びＲ²は水素原子、炭素数１〜２０のアルキル基、置換されていてもよいアリール基、又は、ハロゲン化アルキル基を示し、Ｚは４〜２０の置換又は非置換の炭素環を示し、Ｙ¹ないしＹ⁸は、各々独立に、水素原子、ハロゲン原子、炭素数１〜２０のアルキル基、置換されていてもよいアリール基、又は、ハロゲン化アルキル基を示す。）
一般式（２）中、Ｘは好ましくは、酸素原子、炭素数５〜１０のシクロアルキリデン基、又は、−ＣＲ¹Ｒ²−であり、Ｒ¹及びＲ²は好ましくは、水素原子、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、又は、フェニル基であり、更に好ましくは水素原子又はメチル基であり、Ｙ¹ないしＹ²は好ましくは、水素原子、塩素原子、臭素原子、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｓｅｃ−ブチル基、ｎ−ブチル基、イソブチル基、ｔｅｒｔ−ブチル基、又は、フェニル基であり、更に好ましくはメチル基又はフェニル基である。
【００３４】
一般式（２）で表される構造単位を具体的に示すと、例えば以下に示す［１−１］〜［１−１２］等の構造単位が挙げられる。本発明のポリカーボネート共重合体は、特に［１−１］、［１−２］、［１−３］、［１−４］、［１−５］から選ばれる１種以上の構造単位を有するものが好ましく、更には［１−１］〜［１−５］から選ばれる２種類以上の構造単位を有するものが好ましい。特に好ましい構造単位は、［１−１］及び［１−２］である。
【００３５】
【化５】

【００３６】
また、本発明においては、任意の分岐剤もカーボネートオリゴマー組成物の原料とすることができる。使用される分岐剤は、３個またはそれ以上の官能基を有する種々の化合物から選ぶことができる。適当な分岐剤としては、３個またはそれ以上のフェノール性ヒドロキシル基を有する化合物が挙げられ、例えば、２，４−ビス（４−ヒドロキシフェニルイソプロピル）フェノール、２，６−ビス（２−ヒドロキシ−５−メチルベンジル）−４−メチルフェノール、２−（４−ヒドロキシフェニル）−２−（２，４−ジヒドロキシフェニル）プロパン及び１，４−ビス（４，４′−ジヒドロキシトリフェニルメチル）ベンゼンが挙げられる。また、３個の官能基を有する化合物である、２，４−ジヒドロキシ安息香酸、トリメシン酸、塩化シアヌルも使用しうる。中でも、３個またはそれ以上のフェノール性ヒドロキシ基を持つものが好適である。分岐剤の使用量は、目的とする分岐度によっても異なるが、通常、芳香族ジオール類に対し、０．０５〜２モル％の量で使用される。
【００３７】
本発明のカーボネートオリゴマー組成物は、通常、カーボネート形成化合物と芳香族ジオール類とを界面重縮合条件下もしくは溶液重合条件下で反応させる方法で製造することができ、芳香族ジオール類の金属塩水溶液とカーボネート形成化合物とを有機溶媒の存在下、乳化状態で反応させてカーボネートオリゴマー組成物を得る方法が代表的であり好ましい。
【００３８】
上記方法において、芳香族ジオール類は、水及び水溶性の金属水酸化物と共に水相を形成する。金属水酸化物としては、通常水酸化ナトリウムや水酸化カリウム等のアルカリ金属水酸化物が用いられる。水相中で芳香族ジオール類は、上記水酸化物と反応して水溶性の金属塩を生じる。この場合、水相中の芳香族ジオール類とアルカリ金属水酸化物のモル比は、１：１．８〜１：３．５が好ましく、更に１：２．０〜１：３．２が好ましい。水相には、ハイドロサルファイト等の還元剤を少量添加してもよい。
【００３９】
使用する有機溶媒としては、反応温度及び反応圧力において、カーボネート形成化合物及びカーボネートオリゴマー組成物、ポリカーボネート等の反応生成物は溶解するが、水を溶解しない（水と溶液をつくらないという意味で）任意の不活性有機溶媒を含む。
代表的な不活性有機溶媒には、ヘキサン及びｎ−ヘプタンのような脂肪族炭化水素、塩化メチレン、クロロホルム、四塩化炭素、ジクロロエタン、トリクロロエタン、テトラクロロエタン、ジクロロプロパン及び１，２−ジクロロエチレンのような塩素化脂肪族炭化水素、ベンゼン、トルエン及びキシレンのような芳香族炭化水素、クロロベンゼン、ｏ−ジクロロベンゼン及びクロロトルエンのような塩素化芳香族炭化水素、その他ニトロベンゼン及びアセトフェノンのような置換芳香族炭化水素が含まれる。
中でも、塩素化された炭化水素、例えば塩化メチレンまたはクロロベンゼンが好適に使用される。これらの不活性有機溶媒は、単独であるいは他の溶媒との混合物として使用することができる。
【００４０】
カーボネート形成化合物は、液状またはガス状で使用される。温度管理の観点からはカーボネート形成化合物は液状であることが好ましく、反応温度において液状を保ち得る反応圧力が選択される。カーボネート形成化合物の好ましい使用量は、反応条件、特に反応温度及び水相中の芳香族ジオール金属塩の濃度によっても影響は受けるが、芳香族ジオール類の１モルに対するカーボネート形成化合物のモル数で、通常１〜２、好ましくは１〜１．５である。この比が大きすぎるとカーボネート形成化合物の損失が多くなり、且つ一般式（１）で表されるような停止剤同志の縮合物の生成が認められる様になり好ましくない。一方、小さすぎると、ＣＯ基が不足し、適切な分子量伸長が行われなくなり好ましくない。
【００４１】
本発明においては二相界面縮合法を採用した場合、カーボネート形成化合物との接触に先立って有機相と水相とを接触させ、乳濁液を形成させるのが特に好ましい。乳濁液を形成させるためには、通常の撹拌翼を有する撹拌機の外、ホモジナイザ、ホモミキサ、コロイドミル、フロージェットミキサ、超音波乳化機等の動的ミキサや、静的ミキサ等の混合機を使用するのが好ましい。乳濁液は通常、０．０１〜１０μｍの液滴径を有し、乳化安定性を有する。
【００４２】
乳化の状態は通常ウェーバー数或いはＰ／ｑ（単位容積当たりの付加動力値）で表現できる。ウェーバー数としては、好ましくは１０，０００以上、さらに好ましくは２０，０００以上、最も好ましくは３５，０００以上である。また、上限としては１，０００，０００以下程度で十分である。また、Ｐ／ｑとしては、好ましくは２００ｋｇ・ｍ／リットル以上、さらに好ましくは５００ｋｇ・ｍ／リットル以上、最も好ましくは１，０００ｋｇ・ｍ／リットル以上である。
【００４３】
乳濁液とカーボネート形成化合物との接触は、前記乳化条件よりも弱い混合条件下で行うのがホスゲンの有機相への溶解を抑制する意味で好ましく、ウェーバー数として１０，０００未満、好ましくは５，０００未満、さらに好ましくは２，０００未満である。また、Ｐ／ｑとしては、２００ｋｇ・ｍ／リットル未満、好ましくは１００ｋｇ・ｍ／リットル未満、さらに好ましくは５０ｋｇ・ｍ／リットル未満である。カーボネート形成化合物との接触は、管型反応器や槽型反応器にカーボネート形成化合物を導入することによって達成することができる。
【００４４】
オリゴマー化反応においては縮合触媒の存在下で行うことができる。添加は、カーボネート形成化合物を消費した後に行う方がよく、縮合触媒としては、二相界面縮合法に使用されている多くの縮重合触媒の中から、任意に選択することができる。中でも、トリアルキルアミン、Ｎ−エチルピロリドン、Ｎ−エチルピペリジン、Ｎ−エチルモルホリン、Ｎ−イソプロピルピペリジン及びＮ−イソプロピルモルホリンが適しており、特にトリエチルアミン及びＮ−エチルピペリジンが特に適している。
【００４５】
オリゴマー化反応で使用する縮合触媒の添加量は、原料芳香族ジオールに対して０．００５〜０．１ｍｏｌ％程度、好ましくは０．０３〜０．０８ｍｏｌ％である。０．００５ｍｏｌ％未満ではオリゴマー組成物中の未反応モノフェノール類が５０％を超え、この状態で縮合しても分子量の制御されたポリカーボネート樹脂を得るのは困難であり好ましくない。一方、０．１ｍｏｌ％を超えると未反応モノフェノール類の量は５０％以下となるものの、重縮合後の洗浄工程で触媒の抽出除去に多大の労力を要し好ましくない。
【００４６】
オリゴマー組成物を得る時の反応温度は、８０℃以下、好ましくは６０℃以下、さらに好ましくは１０℃〜５０℃の範囲にあることが好ましく、また反応時間は反応温度によっても左右されるが、通常０．５分〜１０時間、好ましくは１分〜２時間である。反応温度が高すぎると、副反応の制御ができず、カーボネート形成化合物原単位が悪化する。一方、低すぎると、反応制御上は好ましい状況ではあるが、冷凍負荷が増大して、その分コストアップとなり好ましくない。
【００４７】
また、オリゴマー組成物を得る段階での、有機相中のオリゴマー濃度は、得られるオリゴマー組成物が可溶な範囲であればよく、具体的には、１０〜４０重量％程度である。有機相の割合は芳香族ジオールのアルカリ金属水酸化物水溶液、即ち水相に対して０．２〜１．０の容積比であることが好ましい。このような縮合条件下で得られるオリゴマー組成物の粘度平均分子量は通常５００〜１０，０００程度、好ましくは１，０００〜５，０００である。
【００４８】
このようにして得られたオリゴマー組成物は、常法に従い、重縮合条件下で高分子のポリカーボネート樹脂とする。好ましい実施態様においては、このオリゴマー組成物の溶存する有機相を水相から分離し、必要に応じ前述の不活性有機溶媒を追加し、該オリゴマー組成物の濃度を調整する。すなわち、重縮合によって得られる有機相中のポリカーボネート樹脂の濃度が５〜３０重量％となるように溶媒の量が調整される。しかる後、新たに水及びアルカリ金属水酸化物を含む水相を加え、さらに重縮合条件を整えるために好ましくは縮合触媒を添加して界面重縮合法に従い、所期の重縮合を完結させる。重縮合時の有機相と水相の割合は容積比で有機相：水相＝１：０．２〜１程度が好ましい。
【００４９】
また、ポリカーボネート樹脂の分子鎖中に取り込まれた窒素量は、１０ｐｐｍ以下で且つ末端クロロホーメート基量は０．１μｅｑ／ｇ以下であることが好ましい。分子鎖中に取り込まれた窒素量や末端クロロホーメート基量が多くなると電子写真感光体等に使用した場合、電気特性が悪化する傾向にある。
分子末端に取り込まれる窒素を１０ｐｐｍ以下、また末端クロロホーメート基量を０．１μｅｑ／ｇ以下に低減するには、オリゴマー組成物の重縮合時の反応温度を１５℃以下とすることが好ましく、０℃〜１０℃とすることが更に好ましい。
【００５０】
重縮合完結後は、残存するクロロフォーメート基（ＣＦ基）が０．１μｅｑ／ｇ以下になるまで、水酸化ナトリウムのようなアルカリで洗浄処理する。その後は、電解質が無くなるまで、有機相を洗浄し、最終的には有機相から適宜不活性有機溶媒を除去して、ポリカーボネート樹脂を分離する。
このようにして得られるポリカーボネート樹脂の粘度平均分子量（Ｍｖ）は、通常５，０００〜１００，０００程度であるが、好ましくは１０，０００〜１００，０００、さらに好ましくは２０，０００〜５０，０００である。粘度平均分子量が低すぎると樹脂の機械的強度が低下し実用的でなく、高すぎると、射出成型の際、流動性が悪く成型が困難である。また電子写真感光体のバインダー樹脂として用いた場合は分子量が１００，０００以上であると適当な膜厚に塗布することが困難である。
【００５１】
本発明のポリカーボネート樹脂は、例えば、電子写真感光体に用いることが出来る。ポリカーボネート樹脂を電子写真感光体に用いる場合には、導電性支持体上に設けた感光層中に含有させる。感光層の具体的な構成としての１つ目の例としては、導電性支持体上に電荷発生物質を主成分とする電荷発生層、電荷輸送物質及びバインダ−樹脂を主成分とした電荷輸送層をこの順に積層した積層型感光体、また、２つ目の例としては、導電性支持体上に、電荷輸送物質及びバインダ−樹脂を主成分とした電荷輸送層、電荷発生物質を主成分とする電荷発生層をこの順に積層した逆二層型感光体、そして３つ目の例としては、導電性支持体上に電荷輸送物質及びバインダ−樹脂を含有する層中に電荷発生物質を分散させた分散型感光体の様な構成が基本的な形の例として挙げられる。
本発明のポリカーボネート樹脂を電子写真感光体のバインダー樹脂として用いる場合、複数のポリカーボネート樹脂をブレンドして用いたり、ポリカーボネート樹脂以外の樹脂をブレンドして用いたりすることも可能であるが、バインダー樹脂全体として、上述のロ）〜ニ）の各要件を満足する必要がある。
【００５２】
積層型感光体の場合、本発明のポリカーボネート樹脂は電荷輸送層のバインダー樹脂として用いることが好ましい。電荷発生層に使用される電荷発生物質としては、例えばセレニウム及びその合金、硫化カドミウム、その他無機系光導電材料、フタロシアニン顔料、アゾ顔料、キナクリドン顔料、インジゴ顔料、ペリレン顔料、多環キノン顔料、アントアントロン顔料、ベンズイミダゾール顔料などの有機顔料等各種光導電材料が使用でき、特に有機顔料、更にフタロシアニン顔料、アゾ顔料が好ましい。
【００５３】
これらの微粒子は、通常、ポリエステル樹脂、ポリビニルアセテート、ポリアクリル酸エステル、ポリメタクリル酸エステル、ポリエステル、ポリカーボネート、ポリビニルアセトアセタール、ポリビニルプロピオナール、ポリビニルブチラール、フェノキシ樹脂、エポキシ樹脂、ウレタン樹脂、セルロースエステル、セルロースエーテルなどの各種バインダー樹脂で結着した形、又は微粒子を蒸着した形で使用される。バインダー樹脂を用いる場合の使用比率はバインダー樹脂１００重量部に対して電荷発生物質３０〜５００重量部の範囲より使用され、その膜厚は通常０．１〜１μｍ、特には０．１５〜０．６μｍが好適である。
【００５４】
電荷輸送層の電荷輸送物質としては、例えば、２，４，７−トリニトロフルオレノン、テトラシアノキノジメタンなどの電子吸引性物質、カルバゾール、インドール、イミダゾール、オキサゾール、ピラゾール、オキサジアゾール、ピラゾリン、チアジアゾールなどの複素環化合物、アニリン誘導体、ヒドラゾン化合物、芳香族アミン誘導体、スチルベン誘導体あるいはこれらの化合物からなる基を主鎖もしくは側鎖に有する重合体などの電子供与性物質が挙げられる。特に重合体ではない低分子化合物が好ましい。これらの電荷輸送物質とともにバインダー樹脂が配合される。電荷輸送層には、必要に応じて酸化防止剤、増感剤等の各種添加剤を含んでいてもよい。電荷輸送層の膜厚は１０〜５０μｍ、好ましくは１０〜４０μｍの厚みで使用されるのがよい。
【００５５】
分散型の場合、バインダー樹脂として本発明の上記ポリカーボネート樹脂が用いられ、樹脂１００重量部に対して電荷輸送物質は３０〜１５０重量部の範囲より使用されるのが好ましい。また膜厚は通常５〜５０μｍ、好ましくは１０〜３０μｍが好適である。また必要に応じて酸化防止剤、増感剤等の各種添加剤を含んでいてもよい。
【００５６】
分散型感光層の場合には、上記のような配合比のバインダー樹脂と電荷輸送物質からなる電荷輸送媒体中に、前記の電荷発生物質が分散される。その場合の電荷発生物質の粒子径は充分小さいことが必要であり、好ましくは１μｍ以下、より好ましくは０．５μｍ以下で使用される。感光層内に分散される電荷発生物質の量は少なすぎると充分な感度が得られず、多すぎると帯電性の低下、感度の低下などの弊害があり、例えば好ましくは０．５〜５０重量％の範囲で、より好ましくは１〜２０重量％の範囲で使用される。
【００５７】
感光層の膜厚は通常５−５０μｍ、より好ましくは１０−４５μｍで使用される。またこの場合にも成膜性、可とう性、機械的強度等を改良するための公知の可塑剤、残留電位を抑制するための添加剤、分散安定性向上のための分散補助剤、塗布性を改善するためのレベリング剤、界面活性剤、例えばシリコ−ンオイル、フッ素系オイルその他の添加剤が添加されていても良い。
【００５８】
感光層あるいは電荷輸送層を導電性支持体上に設けるには、通常、適当な溶媒に、本発明のポリカーボネート樹脂、及び電荷輸送材料、その他の添加剤を混合して塗布液とし、好ましくは浸漬塗布により支持体上に塗布し、その後乾燥する。本発明の電子写真感光体用塗布液とは、この塗布液を指すものである。
【００５９】
またこれらの感光体は最表面層として従来公知の例えば熱可塑性或いは熱硬化性ポリマ−を主体とするオ−バ−コ−ト層を設けても良い。これらの感光層はロ−ルコ−ティング、バ−コ−ティング、ディップコ−ティング、スプレ−コティンング、マルチノズルコ−ティング等公知の方法によって導電性支持体上に形成される。感光層を設ける導電性支持体としては、アルミニウム、ステンレス鋼、ニッケル等の金属材料、表面にアルミニウム、銅、パラジウム、酸化スズ、酸化インジウム等の導電性層を設けたポリエステルフィルム、紙、ガラス等の絶縁性支持体が使用される。
【００６０】
導電性支持体と感光層の間には通常使用されるような公知のバリアー層が設けられていても良い。バリアー層としては、例えばアルミニウム陽極酸化被膜、酸化アルミニウム、水酸化アルミニウム等の無機層、ポリビニルアルコール、カゼイン、ポリビニルピロリドン、ポリアクリル酸、セルロース類、ゼラチン、デンプン、ポリウレタン、ポリイミド、ポリアミド、等の有機層が使用される。バリアー層の膜厚は０．１〜２０μｍの範囲が好ましく、０．１〜１０μｍの範囲で使用されるのが最も効果的である。各層の形成方法としては、層に含有させる物質を溶剤に溶解又は分散させて得られた塗布液を順次塗布するなどの公知の方法が適用できる。
【００６１】
【実施例】
以下、実施例によって本発明を具体的に説明するが、本発明はその要旨を越えない限り以下の実施例によって限定されるものではない。
また、実施例中の各測定値は以下の方法により求めたものである。
（１）粘度平均分子量（Ｍｖ）
オリゴマー又はポリマーの０．６ｇ／ｄｌ塩化メチレン溶液を用いて２０℃で測定したη_SPから、以下の式を用いて算出した。
【００６２】
【数１】
η_SP／Ｃ＝［η］（１＋０．２８η_SP）
η_SP＝１．２３×１０^-4Ｍｖ^0.83
【００６３】
から算出した。
（２）オリゴマー末端クロロフォーメート基濃度（ＣＦ基）
オリゴマー組成物溶液を塩化メチレンで希釈した後、アニリンと純水を添加し、フェノールフタレインを指示薬として規定度のＮａＯＨにて滴定し求めた。
【００６４】
（３）オリゴマー末端フェノール性ＯＨ基濃度（ＯＨ基）
オリゴマー組成物溶液を塩化メチレンで希釈した後、四塩化チタン、酢酸溶液を加え発色させ分光光度計（日立（株）製 ＵＶ−１６０型）を用い５４６ｎｍの波長での吸光度を測定した。別に該オリゴマー組成物製造時に使用した芳香族ジオールの塩化メチレン溶液を用い、吸光係数を求め、オリゴマーの末端フェノール性ＯＨ基量を定量した。
【００６５】
（４）オリゴマー中の未反応ｐ−ｔ−ブチルフェノール量及びＰＴＢＰＣの量
オリゴマー組成物溶液を液体クロマトグラフィー（ＬＣ）により測定し（条件：ｎ−ヘキサン／塩化メチレン（１／１）→塩化メチレン１００％へ変化、検出器：ＵＶ２７０ｎｍ、装置：島津ＬＣ−９Ａ）予め求めた面積補正係数よりサンプル中の未反応ｐ−ｔ−ブチルフェノール量及びＰＴＢＰＣの量を算出した。
尚、未反応ｐ−ｔ−ブチルフェノール量は仕込んだｐ−ｔ−ブチルフェノール量に対する割合（％）で示した。
【００６６】
（５）ポリカーボネート樹脂の分子末端クロロホーメート基濃度
ポリカーボネート樹脂約１ｇを秤量し、塩化メチレン２０ｍｌを加えて溶解した。これに４−（ｐ−ニトロベンジル）ピリジンの１ｗｔ％塩化メチレン溶液２ｍｌを加え発色させ、分光光度計（日立（株）製、３３０型）を用い４４０ｎｍの波長での吸光度を測定した。別に、フェニルクロロホーメートの塩化メチレン溶液を用い、吸光係数を求め、サンプル中のクロロホーメート基量を定量した。
【００６７】
（６）ポリカーボネート樹脂分子末端に取り込まれた窒素量
ポリカーボネート樹脂約２０ｍｇを用い、三菱化学（株）製、全窒素分析計（ＴＮ−１０）により測定した。
【００６８】
（７）ポリカーボネート樹脂分子末端モノフェノール類基量
ポリカーボネート樹脂約０．１ｇを秤量し、塩化メチレン２ｍｌに溶解した後、１．０規定の水酸化カリウム−メタノール溶液２０ｍｌを加え６０℃、１Ｈｒ後、加水分解したモノフェノールをＬＣにて測定し（条件：メタノール／水＝４／６、検出器：ＵＶ２７０ｎｍ、装置：島津ＬＣ−９Ａ）予め求めた面積補正係数よりサンプル中の分子末端モノフェノール基量を算出した。
【００６９】
（８）ポリカーボネート樹脂分子総末端基量に対する分子末端モノフェノール基量の割合下記式により算出した。
分子末端モノフェノール基量／（分子末端モノフェノール＋分子末端ＯＨ基量＋分子末端クロロホーメート基量）×１００（％）（９）塗布液粘度
電荷移動層を形成する塗布液としてポリカーボネート樹脂の１０％ジオキサン溶液を調製し、東京計器（株）製、Ｂ型粘度計により調製液の２５℃に於ける粘度を測定した。
【００７０】
[実施例１〜５]
表１記載量の１種類若しくは２種類の芳香族ジオール、水酸化ナトリウム、及び水１０１．１ｋｇ／時を、ハイドロサルファイト０．０１８ｋｇ／時の存在下に、３５℃で溶解した後、２５℃まで冷却した水相、並びに５℃に冷却した塩化メチレン６０．５ｋｇ／時の有機相を、各々内径６ｍｍ、外径８ｍｍのステンレス製配管に供給し、同配管内で混合し、さらにホモミキサー（特殊機化株式会社製、製品名Ｔ．ＫホモミックラインフローＬＦ−５００型）を用いて、乳化し、乳濁液を調製した。
【００７１】
このようにして得られた、芳香族ジオールのナトリウム塩の水溶液（水相）と塩化メチレン（有機相）の乳濁液を、ホモミキサーから分岐する内径６ｍｍ、外径８ｍｍの配管で取出し、これに接続する内径６ｍｍ、長さ３４ｍのポリテトラフルオロエチレン製パイプリアクターにおいて、ここに別途導入される０℃に冷却したパイプより供給された表１記載の液化ホスゲンと接触させた。
【００７２】
上記乳濁液はホスゲンとパイプリアクター内を１．７ｍ／秒の線速にて２０秒間流通する間に、ホスゲン化、オリゴマー化反応を行った。この時、反応温度は、それぞれ６０℃になるように調整しいずれも次のオリゴマー化槽に入る前に３５℃まで外部冷却を行った。このようにしてパイプリアクターより得られるオリゴマー化された乳濁液を、さらに内容積５０リットルの撹拌機付き反応槽に導き、窒素ガス雰囲気下３０℃で撹拌し、オリゴマー化することで、水相中に存在する未反応のＢＰＡ−Ｎａを完全に消費させた後、水相と有機相を静置分離し、オリゴマーの塩化メチレン溶液を得た。
【００７３】
オリゴマー化に際し、トリエチルアミンの２重量％水溶液及び、ｐ−ｔ−ブチルフェノールの２４重量％の塩化メチレン溶液を、表１記載の流量で各々、オリゴマー化槽に添加した。ｐ−ｔ−ブチルフェノールを添加する時点で、オリゴマー化槽中の反応液におけるホスゲンの含有量は、０．００１重量％以下であった。この時のオリゴマーの粘度平均分子量（Ｍｖ）、末端クロロフォーメート基濃度及び末端フェノール性ＯＨ基濃度、またオリゴマー組成物中の未反応ｐ−ｔ−ブチルフェノール量及びＰＴＢＰＣの量を測定し表１に記載した。
【００７４】
上記オリゴマー組成物の塩化メチレン溶液のうち５０ｋｇを、内容積１５０リットルのファウドラー翼付き反応槽に仕込み、これに希釈用塩化メチレン２５ｋｇを追加し、さらに表１記載量の２５重量％水酸化ナトリウム水溶液、水６ｋｇ、及びトリエチルアミン２．２ｇを加え、窒素ガス雰囲気下１０℃で撹拌し、１２０分間重縮合反応を行って、ポリカーボネート樹脂を得た。
【００７５】
この反応液に、塩化メチレン３０ｋｇ及び水７ｋｇを加え、２０分間撹拌した後、撹拌を停止し、水相と有機相を分離した。分離した有機相に、０．１Ｎ塩酸２０ｋｇを加え１５分間撹拌し、トリエチルアミン及び小量残存するアルカリ成分を抽出した後、撹拌を停止し、水相と有機相を分離した。さらに、分離した有機相に、純水２０ｋｇを加え、１５分間撹拌した後、撹拌を停止し、水相と有機相を分離した。この操作を抽出排水中の塩素イオンが検出されなくなるまで（３回）繰り返した。
【００７６】
得られた精製ポリカーボネート樹脂溶液を温水中にフェードしポリマー粉粒体を取得し、通風乾燥機で窒素雰囲気下１２０℃、４８Ｈｒ乾燥した。
尚、各実施例において再現性を確認するため、各々２回ずつ実施した。
各実施例で得られたポリカーボネート樹脂（以下「Ｃ−１」〜「Ｃ−５」と記す）について、平均分子量（Ｍｖ）、分子末端ＯＨ基量（ＯＨ）、分子総末端基量に対する分子末端モノフェノール基量の割合及び塗布液粘度をそれぞれ測定し、その結果を表１に示した。分子末端基量、分子量が制御されたポリカーボネート樹脂が再現良く得られ、塗布液の粘度も安定していた。
【００７７】
[比較例１]
実施例１において、ｐ−ｔ−ブチルフェノールの塩化メチレン溶液をパイプリアクターに導入した後にホスゲンと接触させ、また重縮合時の温度を３０℃とした以外は実施例１と同様の操作を行った。
[比較例２]
実施例２においてｐ−ｔ−ブチルフェノールの塩化メチレン溶液をパイプリアクターに導入した後にホスゲンと接触させ、また重縮合時の温度を３０℃とした以外は実施例２と同様の操作を行った。
【００７８】
[比較例３]
実施例３においてｐ−ｔ−ブチルフェノールの塩化メチレン溶液をパイプリアクターに導入した後にホスゲンと接触させ、また重縮合時の温度を３０℃とした以外は実施例３と同様の操作を行った。
[比較例４]実施例３においてｐ−ｔ−ブチルフェノールの塩化メチレン溶液を重縮合時に添加し、また重縮合時の温度を３０℃とした以外は実施例３と同様の操作を行った。
【００７９】
[比較例５]
実施例４において、ｐ−ｔ−ブチルフェノールの塩化メチレン溶液をパイプリアクターに導入した後にホスゲンと接触させ、また重縮合時の温度を３０℃とした以外は実施例４と同様の操作を行った。
[比較例６]
実施例５において、ｐ−ｔ−ブチルフェノールの塩化メチレン溶液を重縮合時に添加し、また重縮合時の温度を３０℃とした以外は実施例５と同様の操作を行った。
【００８０】
これらの比較例１〜６についても実施例１〜５と同様に再現性を確認するため、各々２回ずつ実施し、得られたポリカーボネート樹脂（以下「Ｃ−６」〜「Ｃ−１１」と記す）について諸特性を評価し、その結果を表２に示した。得られたポリカーボネート樹脂の分子末端基、分子量はばらつき再現性がなかった。この結果塗布液の粘度も大きくばらつきそのまま塗布液として使用することは出来ず、分子量の異なるポリカーボネート樹脂をブレンドし粘度を調整する必要があった。
【００８１】
[実施例６]
実施例１及び２で得られたそれぞれのオリゴマーを表３記載の割合で混合し、内容積１５０リットルのファウドラー翼付き反応槽に仕込み、これに希釈用塩化メチレン２５ｋｇを追加し、さらに２５重量％水酸化ナトリウム水溶液 ５．３６ｋｇ、水６ｋｇ、及びトリエチルアミン２．２ｇを加え、窒素ガス雰囲気下１０℃で撹拌し、１２０分間重縮合反応を行って、ポリカーボネート樹脂を得た。
【００８２】
この反応液に、塩化メチレン３０ｋｇ及び水７ｋｇを加え、２０分間撹拌した後、撹拌を停止し、水相と有機相を分離した。分離した有機相に、０．１Ｎ塩酸２０ｋｇを加え１５分間撹拌し、トリエチルアミン及び小量残存するアルカリ成分を抽出した後、撹拌を停止し、水相と有機相を分離した。さらに、分離した有機相に、純水２０ｋｇを加え、１５分間撹拌した後、撹拌を停止し、水相と有機相を分離した。この操作を抽出排水中の塩素イオンが検出されなくなるまで（３回）繰り返した。
得られた精製ポリカーボネート樹脂溶液を温水中にフェードしポリマー粉粒体を取得し、通風乾燥機で窒素雰囲気下１２０℃、４８Ｈｒ乾燥した。
【００８３】
[比較例７]
実施例１及び２でオリゴマー化反応時にｐ−ｔ−ブチルフェノールの塩化メチレン溶液を導入せずに得られたそれぞれのオリゴマーを表３記載の割合で混合し、内容積１５０リットルのファウドラー翼付き反応槽に仕込み、これに希釈用塩化メチレン２５ｋｇを追加し、さらに２５重量％水酸化ナトリウム水溶液 ５．０８ｋｇ、水６ｋｇ、及びトリエチルアミン２．２ｇ、ｐ−ｔ−ブチルフェノールの２４％塩化メチレン溶液 ０．６１ｋｇを加え、窒素ガス雰囲気下１０℃で撹拌し、１２０分間重縮合反応を行って、ポリカーボネート樹脂を得た。
【００８４】
この反応液に、塩化メチレン３０ｋｇ及び水７ｋｇを加え、２０分間撹拌した後、撹拌を停止し、水相と有機相を分離した。分離した有機相に、０．１Ｎ塩酸２０ｋｇを加え１５分間撹拌し、トリエチルアミン及び小量残存するアルカリ成分を抽出した後、撹拌を停止し、水相と有機相を分離した。さらに、分離した有機相に、純水２０ｋｇを加え、１５分間撹拌した後、撹拌を停止し、水相と有機相を分離した。この操作を抽出排水中の塩素イオンが検出されなくなるまで（３回）繰り返した。
【００８５】
得られた精製ポリカーボネート樹脂溶液を温水中にフェードしポリマー粉粒体を取得し、通風乾燥機で窒素雰囲気下１２０℃、４８Ｈｒ乾燥した。
実施例６、比較例７についても同様再現性を確認するため、各々２回ずつ実施し得られたポリカーボネート樹脂（以下「Ｃ−１２」「Ｃ−１３」と記す）について諸特性を評価し、その結果を表３に示した。
実施例６では安定した分子末端基量、分子量、塗布液が得られるのに対し、比較例７では分子末端基量、分子量にばらつきがみられ再現性がなく塗布液の粘度も大きくばらつきそのまま塗布液として使用することは出来ず、分子量の異なるポリカーボネート樹脂をブレンドし粘度を調整する必要があった。
【００８６】
【表１】

【００８７】
【表２】

【００８８】
【表３】

【００８９】
下記（Ａ）で表わされるビスアゾ化合物１０重量部を、１５０重量部の４−メトキシ−４−メチルペンタノン−２に加え、サンドグラインドミルにて粉砕分散処理を行なった。ここで得られた顔料分散液をポリビニルブチラール（積水化学工業（株）製、商品名ＢＨ−３）の５％ジメトキシエタン溶液に加え、最終的に固形分濃度４．０％の分散液を作製した。
【００９０】
【化６】

【００９１】
この様にして得られた分散液に、表面が鏡面仕上げされた外径８０ｍｍ、長さ３４０ｍｍ、肉厚２．０ｍｍのアルミシリンダーを浸漬塗布し、その乾燥膜厚が約０．４μｍとなるように電荷発生層を設けた。次にこのアルミシリンダーを、下記（Ｂ）で表わされるヒドラゾン化合物９０重量部と実施例１〜３及び比較例２により得られたポリカーボネート樹脂１００重量部を、ジオキサン９００重量部に溶解させて得た塗布液に浸漬塗布し、乾燥後の膜厚が２０μｍとなるように電荷移動層を形成し感光体を作成した。
【００９２】
【化７】

【００９３】
この様に作製した感光体をコピー機、プリンターを模した評価機に装着し１０万枚のコピーテストを行いその時の最も安定した電気特性を測定した。この結果を表４に示した。ここで、各々の電位の測定法を簡単に説明する。複写機の現像槽を取除き、その部分に電位計センサーをとり付けた。次に複写機の原稿台上に真白な原稿と真黒な原稿を半々に置き、この原稿を複写した際の黒地部の電位を帯電電位（Ｖo）、白地部の電位を感度（ＶL）として測定した。除電後に残った電位を残留電位（Ｖr）として測定した。
実施例１〜７、比較例１〜７にて製造されたポリカーボネート樹脂を用いた評価結果を表４に示す。
【００９４】
【表４】

【００９５】
【発明の効果】
本発明のポリカーボネートは、分子量及び分子末端基の制御性に優れ再現良く製造することが出来、さらに、このポリカーボネート樹脂を用いることにより電気特性の良好な電子写真感光体を提供することが出来る。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an electrophotographic photoreceptor and an electrophotographic photoreceptor.For coating solutionThe present invention relates to a method for producing a polycarbonate resin.
[0002]
[Prior art]
  In recent years, electrophotographic technology has been widely used and applied not only in the field of copying machines but also in the field of various printers because of its immediacy and high-quality images. Photoconductors, the core of electrophotographic technology, have been used as conventional photoconductive materials for inorganic photoconductors such as selenium, arsenic-selenium alloys, cadmium sulfide, and zinc oxide. A photoreceptor using an organic photoconductive material having advantages such as easy and easy manufacture has been developed.
[0003]
  Among organic photoreceptors, a so-called multilayer photoreceptor in which a charge generation layer and a charge transport layer are laminated has been devised and has become the mainstream of research. Laminated photoconductors can provide highly sensitive photoconductors by combining highly efficient charge generating materials and charge transport materials, respectively, and can provide a highly safe photoconductor with a wide selection range of materials, In addition, since the productivity of coating is high and relatively advantageous in terms of cost, there is a high possibility that it will become the mainstream of photoconductors.
[0004]
  Usually, the charge transport layer is composed of a solid solution of a binder resin and a charge transport material, and various binder resins have been developed to obtain good electrical characteristics. Conventional binder resins for charge transport layers include vinyl polymers such as polymethacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, thermoplastic resins such as polycarbonate, polyester, polysulfone, phenoxy, epoxy, and silicone resins, and thermosetting. Resin is used. Among them, various polycarbonate resins having excellent performance as binder resins have been developed and put into practical use.
[0005]
  For example, a bisphenol P-type polycarbonate (see, for example, Patent Document 1), a bisphenol Z-type polycarbonate (see, for example, Patent Document 2), a copolymer of bisphenol P and bisphenol A (see, for example, Patent Document 3), bis (4 Various polycarbonate resins such as a polycarbonate copolymer containing a (hydroxyphenyl) ketone type structure (see, for example, Patent Document 4) are disclosed as binder resins.
[0006]
  In the process of forming the charge transport layer, the electrotransport agent and binder resin are dissolved in a mixed solvent, and the coating solution is prepared so as to have a certain concentration and viscosity, and then applied to the drum with a certain film thickness. The method to be taken is taken.
  In this case, if the concentration and viscosity of the coating solution are changed, the coating conditions and the drying conditions must be changed every time in order to obtain a constant film thickness. As a result, a fatal defect as OPC is caused by coating unevenness and the like. There is a possibility, and it is important to control the viscosity at the time of producing the coating solution, that is, the molecular weight of the binder resin.
[0007]
  However, the polycarbonate resin produced by the conventional technique may have a large error from the target molecular weight, and it is difficult to obtain a polycarbonate resin having a controlled molecular weight with good reproducibility. For this reason, polycarbonate resins with different molecular weights must be blended and adjusted so that the concentration and viscosity are within the specifications at the stage of producing the coating solution, and the new labor involved in this process and the production of new resins due to molecular weight deviations. There was a problem that the cost was greatly increased.
  Further, even if polycarbonate resins having the same molecular weight are obtained, the molecular terminals are often different. As a result, when used as an electrophotographic photosensitive member, there are problems such as deterioration of electrical characteristics.
  In order to improve electrical characteristics, it is described that a polycarbonate resin having a molecular terminal OH group concentration of 100 ppm or less is used as a binder resin (see, for example, Patent Document 5). However, a polycarbonate resin with a controlled molecular terminal and molecular weight cannot be obtained only by reducing the molecular terminal OH group concentration.
  In recent years, the conditions for use in printers and copiers have become more severe, and the electrical characteristics as an electrophotographic photoreceptor may be insufficient even when the polycarbonate resin with a reduced molecular terminal OH group concentration is used. .
[0008]
[Problems to be solved by the invention]
  An object of the present invention is to provide an electrophotographic photosensitive member with controlled molecular ends and molecular weight and excellent electrical characteristics.
  An object of the present invention is to provide a coating solution for an electrophotographic photosensitive member that is used for an electrophotographic photosensitive member having excellent electrical characteristics.
  Another object of the present invention is to provide a binder resin for a photosensitive layer of an electrophotographic photoreceptor.UsePolycarbonate treeGreasyTo provide a manufacturing method.
[0009]
[Patent Document 1]
JP 50-98332 A
[Patent Document 2]
JP 59-71057 A
[Patent Document 3]
JP 59-184251
[Patent Document 4]
JP-A-5-21478
[Patent Document 5]
JP-A-4-52654
[0010]
[Means for Solving the Problems]
  In order to solve the above-mentioned problems, the present inventors have made extensive studies and found that the terminal group state of the binder resin is related to the electrical characteristics. In addition, the addition of monophenols, which are molecular weight regulators, during the molecular weight extension immediately after consumption of the carbonate-forming compound, and the polycondensation in the presence of alkali to obtain a polycarbonate resin with controlled end groups and molecular weight with good reproducibility. The present invention has been reached.
  That is, the gist of the present invention is that an electrophotographic photosensitive member having at least a photosensitive layer on a conductive substrate, wherein the binder resin of the photosensitive layer is a polycarbonate resin satisfying the following a) to d): Exists in the body.
B) Monophenols containing at least one aromatic diol and a carbonate-forming compoundWhen the oligomer composition is obtained by reacting as a molecular weight regulator to obtain an oligomer composition, an oligomer composition obtained by mixing monophenols after the carbonate-forming compound concentration is 0.001% by weight or less is mixed with polycondensation conditions. Polymerization belowB) The molecular terminal OH group amount is 20 μeq / g or less, c) and the ratio of the molecular terminal monophenols group amount to the total molecular terminal group amount is 90% or more. The viscosity average molecular weight is 5,000 to 100,000.
[0011]
  Another gist of the present invention is a polycarbonate satisfying at least an organic solvent, a charge transfer material, and the following a) to d):GIt exists in the coating liquid for electrophotographic photoreceptors containing resin.
B) Monophenols containing at least one aromatic diol and a carbonate-forming compoundWhen the oligomer composition is obtained by reacting as a molecular weight regulator to obtain an oligomer composition, an oligomer composition obtained by mixing monophenols after the carbonate-forming compound concentration is 0.001% by weight or less is mixed with polycondensation conditions. Polymerization belowB) The molecular terminal OH group amount is 20 μeq / g or less, c) and the ratio of the molecular terminal monophenols group amount to the total molecular terminal group amount is 90% or more. The viscosity average molecular weight is 5,000 to 100,000.
[0012]
  Further, another gist of the present invention is to react an aromatic diol with a carbonate-forming compound, and after the concentration of the carbonate-forming compound is 0.001% by weight or less, the monophenols are mixed to obtain an average. A step of obtaining a carbonate oligomer composition having a viscosity molecular weight of 500 to 10,000 and a ratio of unreacted monophenols to 50% or less of the charged monophenols, and then subjecting the carbonate oligomer composition to condensation polymerization in the presence of an alkali. A step of obtaining a polycarbonate resin having an average molecular weight of 5,000 to 100,000For binder resin for electrophotographic photosensitive member or coating solution for electrophotographic photosensitive memberIt exists in the manufacturing method of polycarbonate resin.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail.
  The polycarbonate resin is obtained by reacting at least one aromatic diol with a carbonate-forming compound. In the present invention, the polycarbonate resin is reacted in the presence of monophenols.TheThe obtained polycarbonate resin has a molecular terminal OH group amount of 20 μeq / g or less, and a ratio of the molecular terminal monophenol group amount to the molecular total terminal group amount is 90% or more. Yes.
[0014]
  The carbonate-forming compound used as a raw material is a compound that can react with aromatic diols to form a carbonate bond, and for example, phosgene, carbonates such as dimethyl carbonate, diphenyl carbonate, and the like are used. Of these, phosgene is preferred.
  The aromatic diol used as the other raw material is represented by the general formula HO-Z-OH, where Z is one or more aromatic nuclei, and hydrogen bonded to the carbon of the nucleus. Can be substituted with a substituent such as a halogen atom such as chlorine and bromine, an aliphatic group or an alicyclic group. The plurality of aromatic nuclei can also have different substituents. Further, the plurality of aromatic nuclei may be bonded by a crosslinking group. The bridging group includes an aliphatic group, an alicyclic group, a heteroatom, or a combination thereof.
[0015]
  Specifically, hydroquinone, resorcin, biphenol, bis (hydroxyphenyl) alkane, bis (hydroxyphenyl) cycloalkane, bis (hydroxyphenyl) sulfide, bis (hydroxyphenyl) ether, bis (hydroxyphenyl) ketone, bis (hydroxy Phenyl) sulfone, bis (hydroxyphenyl) sulfoxide, bis (hydroxyphenyl) dialkylbenzene, and derivatives thereof having an alkyl or halogen substituent in the nucleus. Of course, two or more of these aromatic diols can be used in combination.
[0016]
  Among these, preferable aromatic diol compounds are those represented by the following general formula (3).
[0017]
[Chemical 1]

[0018]
Or a single bond, R 1 and R 2 represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an optionally substituted aryl group, or a halogenated alkyl group, and Z represents a substituted or unsubstituted group having 4 to 20 carbon atoms. Y1 to Y8 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group which may be substituted, or a halogenated alkyl group. )
[0019]
  Particularly suitable aromatic diols include 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 1,1- Bis (4-hydroxyphenyl) cyclohexane (bisphenol Z) and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are included.
[0020]
  The monophenols represented by the general formula Ar-OH used as the molecular weight regulator in the present invention include various phenols such as pt-butylphenol and p-cresol in addition to ordinary phenols. Alkylphenols having 1 to 20 carbon atoms and halogenated phenols such as p-chlorophenol and 2,4,6-tribromophenol are included. Of these, phenols and phenols substituted with an alkyl group having 1 to 20 carbon atoms in the para position, such as p-isopropylphenol, p-dodecylphenol, and pt-butylphenol, are more preferable. The amount of monophenols used varies depending on the molecular weight of the target condensate, but is usually 0.5 to 10% by weight based on the starting aromatic diol.
  Ar represents an aromatic ring residue which may be substituted. As a substituent, in order to have a function as a molecular weight regulator, a hydroxyl group or a mercapto group which reacts with a carbonate-forming compound or biphenol as a substrate. , Amino groups and the like are excluded. The substituent on the aromatic ring is not particularly limited as long as it is other than these reactive substituents.
[0021]
  The carbonate oligomer composition of the present invention is a carbonate oligomer composition having a viscosity average molecular weight of 500 to 10,000 obtained by reacting an aromatic diol and a carbonate-forming compound in the presence of monophenols. The composition here includes, in addition to the carbonate oligomer obtained by the reaction, by-products produced by the reaction and some remaining raw materials.
[0022]
  In the carbonate oligomer composition of the present invention, the ratio of unreacted monophenols to the charged monophenols in the oligomer composition is 50% or less, and the content of the compound represented by the following general formula (1) Is not more than 0.005% by weight. The compound represented by the general formula (1) is a compound formed by reacting a hydroxyl terminal of a monophenol represented by the general formula Ar-OH with a carbonate-forming compound such as phosgene. When -t-butylphenol is used, the low molecular weight compound is a compound represented by the following formula (5). (Hereinafter, this compound may be abbreviated as “PTBPC”.)
[0023]
[Chemical formula 2]

[0024]
  (However, Ar represents an optionally substituted aromatic ring residue.)
[0025]
[Chemical Formula 3]

[0026]
  (In the formula, t-Bu represents a tertiary butyl group, and -Ph- represents a phenylene group.)
[0027]
  The content of the compound represented by the general formula (1) is preferably less than 0.003% by weight, more preferably less than 0.001% by weight. In order to make it within the above range, for example, when an oligomer composition is obtained by reacting a raw material aromatic diol and a carbonate-forming compound with a monophenol as a molecular weight regulator, the monophenol is immediately after consumption of the carbonate-forming compound. Specifically, after the concentration of the carbonate-forming compound becomes 0.001% by weight or less, it can be handled by mixing monophenols. The amount of unreacted monophenol present in the oligomer composition is 50% or less, preferably 30% or less, particularly preferably 10% or less, based on the monophenol used in the reaction.
[0028]
  In order to make the monophenol concentration in the oligomer composition within the above range, the monophenol is mixed in the middle of the molecular extension of the oligomer composition. Here, the concentration of the carbonate-forming compound is consumed with respect to the total amount of the aromatic diol compound as the raw material, the carbonate-forming compound as the product and the carbonate oligomer composition as the product, and the carbonate oligomer composition in the middle of the molecular weight extension. It means the amount (weight ratio) of the raw material carbonate-forming compound.
[0029]
  When monophenols are added in the presence of a carbonate-forming compound, a large amount of condensates (diphenyl carbonates) of monophenols as shown in general formula (1) are produced, making it difficult to obtain a polycarbonate resin having a target molecular weight. When used as a binder resin for an electrophotographic photosensitive member, the electrical characteristics deteriorate, which is not preferable. In addition, when the addition of monophenols is extremely delayed, the molecular end of the resulting polycarbonate resin has a large amount of OH groups. As a result, the molecular weight is not reproducible and has a unique shoulder on the low molecular weight side of the molecular weight distribution. The product has a lot of harmful effects such as sagging during molding.
[0030]
  As a result of studying a method in which the molecular end OH group amount is 20 μeq / g or less and the ratio of the molecular end monophenol group amount to the total molecular end group amount is 90% or more, the inventors surprisingly adjusted the molecular weight. It was found that this can be achieved by adding the agent immediately after the consumption of the carbonate-forming compound is completed and before the start of molecular weight extension.
[0031]
  A carbonate oligomer composition obtained from an aromatic diol compound and a carbonate-forming compound has a structural unit represented by the following general formula (2).
[0032]
[Formula 4]

[0033]
Or a single bond and R¹And R²Represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an optionally substituted aryl group or a halogenated alkyl group, Z represents a substituted or unsubstituted carbocycle having 4 to 20 carbon atoms, Y¹Or Y⁸Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group which may be substituted, or a halogenated alkyl group. )
  In general formula (2), X is preferably an oxygen atom, a cycloalkylidene group having 5 to 10 carbon atoms, or -CR.¹R²-Yes, R¹And R²Is preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, or a phenyl group, more preferably a hydrogen atom or a methyl group,¹Or Y²Is preferably a hydrogen atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a sec-butyl group, an n-butyl group, an isobutyl group, a tert-butyl group, or a phenyl group. More preferably a methyl group or a phenyl group.
[0034]
  Specific examples of the structural unit represented by the general formula (2) include structural units such as [1-1] to [1-12] shown below. The polycarbonate copolymer of the present invention has at least one structural unit selected from [1-1], [1-2], [1-3], [1-4], and [1-5]. Those having two or more structural units selected from [1-1] to [1-5] are more preferable. Particularly preferred structural units are [1-1] and [1-2].
[0035]
[Chemical formula 5]

[0036]
  In the present invention, any branching agent can also be used as a raw material for the carbonate oligomer composition. The branching agent used can be selected from a variety of compounds having three or more functional groups. Suitable branching agents include compounds having 3 or more phenolic hydroxyl groups such as 2,4-bis (4-hydroxyphenylisopropyl) phenol, 2,6-bis (2-hydroxy- 5-methylbenzyl) -4-methylphenol, 2- (4-hydroxyphenyl) -2- (2,4-dihydroxyphenyl) propane and 1,4-bis (4,4'-dihydroxytriphenylmethyl) benzene Can be mentioned. Further, 2,4-dihydroxybenzoic acid, trimesic acid, and cyanuric chloride, which are compounds having three functional groups, can also be used. Of these, those having three or more phenolic hydroxy groups are preferred. The amount of the branching agent used varies depending on the target branching degree, but is usually used in an amount of 0.05 to 2 mol% with respect to the aromatic diol.
[0037]
  The carbonate oligomer composition of the present invention can be usually produced by a method in which a carbonate-forming compound and an aromatic diol are reacted under interfacial polycondensation conditions or solution polymerization conditions, and an aqueous metal salt solution of the aromatic diols. A typical method is preferred to obtain a carbonate oligomer composition by reacting a carbonate-forming compound in the presence of an organic solvent in an emulsified state.
[0038]
  In the above method, the aromatic diol forms an aqueous phase with water and a water-soluble metal hydroxide. As the metal hydroxide, alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is usually used. In the aqueous phase, aromatic diols react with the hydroxide to produce water-soluble metal salts. In this case, the molar ratio of the aromatic diols to the alkali metal hydroxide in the aqueous phase is preferably 1: 1.8 to 1: 3.5, more preferably 1: 2.0 to 1: 3.2. . A small amount of a reducing agent such as hydrosulfite may be added to the aqueous phase.
[0039]
  As an organic solvent to be used, a reaction product such as a carbonate-forming compound, a carbonate oligomer composition, and a polycarbonate dissolves at a reaction temperature and a reaction pressure, but does not dissolve water (in the sense of not forming a solution with water). Of an inert organic solvent.
  Typical inert organic solvents include aliphatic hydrocarbons such as hexane and n-heptane, methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, dichloropropane and 1,2-dichloroethylene. Chlorinated aliphatic hydrocarbons, aromatic hydrocarbons such as benzene, toluene and xylene, chlorinated aromatic hydrocarbons such as chlorobenzene, o-dichlorobenzene and chlorotoluene, and other substituted aromatic carbons such as nitrobenzene and acetophenone Hydrogen is included.
  Of these, chlorinated hydrocarbons such as methylene chloride or chlorobenzene are preferably used. These inert organic solvents can be used alone or as a mixture with other solvents.
[0040]
  The carbonate-forming compound is used in liquid or gaseous form. From the viewpoint of temperature control, the carbonate-forming compound is preferably in a liquid state, and a reaction pressure that can maintain the liquid state at the reaction temperature is selected. The preferred amount of carbonate-forming compound used is affected by the reaction conditions, in particular the reaction temperature and the concentration of the aromatic diol metal salt in the aqueous phase, but in moles of carbonate-forming compound per mole of aromatic diols, Usually, it is 1 to 2, preferably 1 to 1.5. If this ratio is too large, the loss of the carbonate-forming compound is increased, and the formation of a condensate between the terminators as represented by the general formula (1) is observed, which is not preferable. On the other hand, if it is too small, the CO group is insufficient, and proper molecular weight elongation cannot be performed, which is not preferable.
[0041]
  In the present invention, when the two-phase interfacial condensation method is adopted, it is particularly preferable that the organic phase and the aqueous phase are brought into contact with each other to form an emulsion prior to the contact with the carbonate-forming compound. In order to form an emulsion, in addition to a stirrer having a normal stirring blade, a dynamic mixer such as a homogenizer, a homomixer, a colloid mill, a flow jet mixer, an ultrasonic emulsifier, or a mixer such as a static mixer Is preferably used. The emulsion usually has a droplet diameter of 0.01 to 10 μm and has emulsion stability.
[0042]
  The state of emulsification can be usually expressed by the Weber number or P / q (additional power value per unit volume). The Weber number is preferably 10,000 or more, more preferably 20,000 or more, and most preferably 35,000 or more. Also, the upper limit is about 1,000,000 or less. P / q is preferably 200 kg · m / liter or more, more preferably 500 kg · m / liter or more, and most preferably 1,000 kg · m / liter or more.
[0043]
  The contact between the emulsion and the carbonate-forming compound is preferably performed under mixing conditions weaker than the emulsification conditions in order to suppress dissolution of phosgene in the organic phase, and the Weber number is less than 10,000, preferably 5 Less than 2,000, more preferably less than 2,000. Further, P / q is less than 200 kg · m / liter, preferably less than 100 kg · m / liter, and more preferably less than 50 kg · m / liter. Contact with the carbonate-forming compound can be achieved by introducing the carbonate-forming compound into a tubular reactor or tank reactor.
[0044]
  The oligomerization reaction can be performed in the presence of a condensation catalyst. The addition is preferably performed after consuming the carbonate-forming compound, and the condensation catalyst can be arbitrarily selected from many condensation polymerization catalysts used in the two-phase interfacial condensation method. Among them, trialkylamine, N-ethylpyrrolidone, N-ethylpiperidine, N-ethylmorpholine, N-isopropylpiperidine and N-isopropylmorpholine are suitable, and triethylamine and N-ethylpiperidine are particularly suitable.
[0045]
  The addition amount of the condensation catalyst used in the oligomerization reaction is about 0.005 to 0.1 mol%, preferably 0.03 to 0.08 mol% with respect to the raw material aromatic diol. If it is less than 0.005 mol%, unreacted monophenols in the oligomer composition exceed 50%, and it is difficult to obtain a polycarbonate resin having a controlled molecular weight even if condensation is carried out in this state. On the other hand, when the amount exceeds 0.1 mol%, the amount of unreacted monophenols is 50% or less, but it is not preferable because much labor is required for extraction and removal of the catalyst in the washing step after polycondensation.
[0046]
  The reaction temperature when obtaining the oligomer composition is 80 ° C. or less, preferably 60 ° C. or less, more preferably 10 ° C. to 50 ° C., and the reaction time depends on the reaction temperature, Usually 0.5 minutes to 10 hours, preferably 1 minute to 2 hours. If the reaction temperature is too high, side reactions cannot be controlled, and the carbonate-forming compound basic unit deteriorates. On the other hand, if it is too low, this is a preferable situation in terms of reaction control, but the refrigeration load increases, and the cost increases accordingly, which is not preferable.
[0047]
  Moreover, the oligomer density | concentration in the organic phase in the stage which obtains an oligomer composition should just be a range with which the obtained oligomer composition is soluble, Specifically, it is about 10 to 40 weight%. The ratio of the organic phase is preferably a volume ratio of 0.2 to 1.0 with respect to the aqueous solution of an alkali metal hydroxide of an aromatic diol, that is, the aqueous phase. The viscosity average molecular weight of the oligomer composition obtained under such condensation conditions is usually about 500 to 10,000, preferably 1,000 to 5,000.
[0048]
  The oligomer composition thus obtained is converted into a high-molecular polycarbonate resin under polycondensation conditions according to a conventional method. In a preferred embodiment, the dissolved organic phase of the oligomer composition is separated from the aqueous phase, and the inert organic solvent is added as necessary to adjust the concentration of the oligomer composition. That is, the amount of the solvent is adjusted so that the concentration of the polycarbonate resin in the organic phase obtained by polycondensation is 5 to 30% by weight. Thereafter, an aqueous phase containing water and alkali metal hydroxide is newly added, and in order to further adjust the polycondensation conditions, a condensation catalyst is preferably added and the desired polycondensation is completed according to the interfacial polycondensation method. The ratio of the organic phase to the aqueous phase during polycondensation is preferably about 1: 0.2 to 1 in terms of volume ratio.
[0049]
  Moreover, it is preferable that the amount of nitrogen taken into the molecular chain of the polycarbonate resin is 10 ppm or less and the amount of terminal chloroformate groups is 0.1 μeq / g or less. When the amount of nitrogen incorporated into the molecular chain or the amount of terminal chloroformate groups increases, the electrical properties tend to deteriorate when used in electrophotographic photoreceptors.
  In order to reduce the nitrogen incorporated into the molecular terminals to 10 ppm or less and the amount of terminal chloroformate groups to 0.1 μeq / g or less, the reaction temperature during the polycondensation of the oligomer composition is preferably 15 ° C. or less, It is still more preferable to set it as 0 to 10 degreeC.
[0050]
  After completion of the polycondensation, washing is performed with an alkali such as sodium hydroxide until the remaining chloroformate group (CF group) becomes 0.1 μeq / g or less. Thereafter, the organic phase is washed until the electrolyte disappears, and finally the inert organic solvent is appropriately removed from the organic phase to separate the polycarbonate resin.
  The viscosity average molecular weight (Mv) of the polycarbonate resin thus obtained is usually about 5,000 to 100,000, preferably 10,000 to 100,000, more preferably 20,000 to 50,000. It is. If the viscosity average molecular weight is too low, the mechanical strength of the resin is lowered and is not practical. If it is too high, the fluidity is poor during injection molding, and molding is difficult. Further, when used as a binder resin for an electrophotographic photoreceptor, it is difficult to apply an appropriate film thickness when the molecular weight is 100,000 or more.
[0051]
  The polycarbonate resin of the present invention can be used for, for example, an electrophotographic photoreceptor. When a polycarbonate resin is used for an electrophotographic photoreceptor, it is contained in a photosensitive layer provided on a conductive support. As a first example of a specific configuration of the photosensitive layer, a charge generation layer mainly composed of a charge generation material, a charge transport material and a charge transport layer mainly composed of a binder resin on a conductive support. In a second example, the charge transfer layer mainly comprises a charge transport material and a binder resin, and the charge generation material is a main component. In the third example, the charge generation material is dispersed in a layer containing a charge transport material and a binder resin on a conductive support. An example of a basic shape is a configuration such as a distributed photoconductor.
  When the polycarbonate resin of the present invention is used as a binder resin for an electrophotographic photoreceptor, a plurality of polycarbonate resins can be used in a blend, or a resin other than a polycarbonate resin can be used in a blend. As described above, it is necessary to satisfy the above requirements (b) to (d).
[0052]
  In the case of a multilayer photoreceptor, the polycarbonate resin of the present invention is preferably used as a binder resin for a charge transport layer. Examples of the charge generation material used in the charge generation layer include selenium and its alloys, cadmium sulfide, other inorganic photoconductive materials, phthalocyanine pigments, azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, ant Various photoconductive materials such as organic pigments such as anthrone pigments and benzimidazole pigments can be used, and organic pigments, phthalocyanine pigments, and azo pigments are particularly preferable.
[0053]
  These fine particles are usually polyester resin, polyvinyl acetate, polyacrylate ester, polymethacrylate ester, polyester, polycarbonate, polyvinyl acetoacetal, polyvinyl propional, polyvinyl butyral, phenoxy resin, epoxy resin, urethane resin, cellulose ester, It is used in a form bound with various binder resins such as cellulose ether or a form in which fine particles are vapor-deposited. When the binder resin is used, the usage ratio is from the range of 30 to 500 parts by weight of the charge generating material with respect to 100 parts by weight of the binder resin, and the film thickness is usually 0.1 to 1 μm, particularly 0.15 to 0.005. 6 μm is preferred.
[0054]
  Examples of the charge transport material for the charge transport layer include electron-withdrawing materials such as 2,4,7-trinitrofluorenone and tetracyanoquinodimethane, carbazole, indole, imidazole, oxazole, pyrazole, oxadiazole, pyrazoline, Examples thereof include electron donating substances such as heterocyclic compounds such as thiadiazole, aniline derivatives, hydrazone compounds, aromatic amine derivatives, stilbene derivatives, or polymers having groups composed of these compounds in the main chain or side chain. Particularly preferred are low molecular weight compounds that are not polymers. A binder resin is blended together with these charge transport materials. The charge transport layer may contain various additives such as an antioxidant and a sensitizer as necessary. The charge transport layer may have a thickness of 10 to 50 μm, preferably 10 to 40 μm.
[0055]
  In the case of the dispersion type, the polycarbonate resin of the present invention is used as the binder resin, and the charge transport material is preferably used in the range of 30 to 150 parts by weight with respect to 100 parts by weight of the resin. The film thickness is usually 5 to 50 μm, preferably 10 to 30 μm. Moreover, various additives, such as antioxidant and a sensitizer, may be included as needed.
[0056]
  In the case of a dispersion-type photosensitive layer, the charge generation material is dispersed in a charge transport medium composed of the binder resin and the charge transport material having the blending ratio as described above. In this case, the particle size of the charge generating material needs to be sufficiently small, and is preferably 1 μm or less, more preferably 0.5 μm or less. If the amount of the charge generating material dispersed in the photosensitive layer is too small, sufficient sensitivity cannot be obtained, and if it is too large, there are adverse effects such as reduced chargeability and reduced sensitivity, for example, preferably 0.5 to 50 weights. %, More preferably 1 to 20% by weight.
[0057]
  The film thickness of the photosensitive layer is usually 5-50 μm, more preferably 10-45 μm. Also in this case, known plasticizers for improving film formability, flexibility, mechanical strength, additives for suppressing residual potential, dispersion aids for improving dispersion stability, coatability Leveling agents and surfactants such as silicone oil, fluorine oil and other additives may be added to improve the viscosity.
[0058]
  In order to provide the photosensitive layer or the charge transport layer on the conductive support, the polycarbonate resin of the present invention, the charge transport material, and other additives are usually mixed in an appropriate solvent to form a coating solution, preferably dipping. It is coated on the support by coating and then dried. The coating solution for an electrophotographic photoreceptor of the present invention refers to this coating solution.
[0059]
  These photoreceptors may be provided with an overcoat layer mainly composed of, for example, a conventionally known thermoplastic or thermosetting polymer as the outermost surface layer. These photosensitive layers are formed on the conductive support by known methods such as roll coating, bar coating, dip coating, spray coating, and multi-nozzle coating. Examples of the conductive support on which the photosensitive layer is provided include a metal material such as aluminum, stainless steel, and nickel, a polyester film provided with a conductive layer such as aluminum, copper, palladium, tin oxide, and indium oxide on the surface, paper, glass, etc. Insulating supports are used.
[0060]
  A well-known barrier layer as commonly used may be provided between the conductive support and the photosensitive layer. Examples of the barrier layer include inorganic layers such as aluminum anodized film, aluminum oxide, and aluminum hydroxide, organic materials such as polyvinyl alcohol, casein, polyvinyl pyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, and polyamide. Layers are used. The film thickness of the barrier layer is preferably in the range of 0.1 to 20 μm, and most effectively used in the range of 0.1 to 10 μm. As a method for forming each layer, a known method such as sequentially applying a coating solution obtained by dissolving or dispersing a substance contained in a layer in a solvent can be applied.
[0061]
【Example】
  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
Moreover, each measured value in an Example is calculated | required with the following method.
(1) Viscosity average molecular weight (Mv)
  Η measured at 20 ° C. using 0.6 g / dl methylene chloride solution of oligomer or polymer_SPFrom this, the following formula was used.
[0062]
[Expression 1]
  η_SP/ C = [η] (1 + 0.28η_SP)
  η_SP= 1.23 × 10^-FourMv^0.83
[0063]
Calculated from
(2) Oligomer terminal chloroformate group concentration (CF group)
  After the oligomer composition solution was diluted with methylene chloride, aniline and pure water were added, and titration was performed with normal NaOH using phenolphthalein as an indicator.
[0064]
(3) Oligomeric terminal phenolic OH group concentration (OH group)
  After diluting the oligomer composition solution with methylene chloride, the solution was colored by adding titanium tetrachloride and acetic acid solution, and the absorbance at a wavelength of 546 nm was measured using a spectrophotometer (Hitachi Ltd., UV-160 type). Separately, an extinction coefficient was determined using a methylene chloride solution of an aromatic diol used during the production of the oligomer composition, and the amount of terminal phenolic OH groups of the oligomer was determined.
[0065]
(4) Amount of unreacted pt-butylphenol and amount of PTBPC in the oligomer
  The oligomer composition solution was measured by liquid chromatography (LC) (conditions: n-hexane / methylene chloride (1/1) → change to 100% methylene chloride, detector: UV 270 nm, apparatus: Shimadzu LC-9A). The amount of unreacted pt-butylphenol and the amount of PTBPC in the sample were calculated from the area correction coefficient.
In addition, the amount of unreacted pt-butylphenol was shown by the ratio (%) with respect to the amount of pt-butylphenol prepared.
[0066]
(5) Molecular end chloroformate group concentration of polycarbonate resin
  About 1 g of polycarbonate resin was weighed and dissolved by adding 20 ml of methylene chloride. To this, 2 ml of a 1 wt% methylene chloride solution of 4- (p-nitrobenzyl) pyridine was added for color development, and the absorbance at a wavelength of 440 nm was measured using a spectrophotometer (manufactured by Hitachi, Ltd., Model 330). Separately, an extinction coefficient was determined using a methylene chloride solution of phenyl chloroformate, and the amount of chloroformate group in the sample was quantified.
[0067]
(6) Nitrogen content incorporated into polycarbonate resin molecule ends
  About 20 mg of polycarbonate resin was used, and measurement was performed with a total nitrogen analyzer (TN-10) manufactured by Mitsubishi Chemical Corporation.
[0068]
(7) Polycarbonate resin molecular end monophenol group content
  About 0.1 g of polycarbonate resin was weighed and dissolved in 2 ml of methylene chloride, 20 ml of 1.0N potassium hydroxide-methanol solution was added, and after 1 hour at 60 ° C., hydrolyzed monophenol was measured by LC ( Conditions: methanol / water = 4/6, detector: UV 270 nm, apparatus: Shimadzu LC-9A) The amount of molecular terminal monophenol groups in the sample was calculated from the area correction coefficient determined in advance.
[0069]
(8) Ratio of molecular terminal monophenol group amount to polycarbonate resin molecule total terminal group amount Calculated by the following formula.
  Molecular end monophenol group amount / (molecular end monophenol + molecular end OH group amount + molecular end chloroformate group amount) × 100 (%) (9) Coating solution viscosity
  A 10% dioxane solution of polycarbonate resin was prepared as a coating solution for forming the charge transfer layer, and the viscosity of the prepared solution at 25 ° C. was measured with a B-type viscometer manufactured by Tokyo Keiki Co., Ltd.
[0070]
  [Examples 1 to 5]
  After dissolving one or two kinds of aromatic diol, sodium hydroxide, and water 101.1 kg / hour in Table 1 in the presence of hydrosulfite 0.018 kg / hour at 35 ° C., 25 ° C. An aqueous phase cooled to 5 ° C. and an organic phase of 60.5 kg / h of methylene chloride cooled to 5 ° C. are supplied to stainless steel pipes each having an inner diameter of 6 mm and an outer diameter of 8 mm, mixed in the pipe, and further mixed with a homomixer ( An emulsion was prepared by emulsification using a special machine manufactured by KK Special Product Co., Ltd., product name TK Homomic Line Flow LF-500).
[0071]
  The thus obtained emulsion of an aqueous solution (aqueous phase) and methylene chloride (organic phase) of an aromatic diol sodium salt is taken out from a homomixer through a pipe having an inner diameter of 6 mm and an outer diameter of 8 mm. In a pipe reactor made of polytetrafluoroethylene having an inner diameter of 6 mm and a length of 34 m connected to the liquefied phosgene, it was brought into contact with liquefied phosgene described in Table 1 supplied from a pipe cooled to 0 ° C. separately introduced here.
[0072]
  The emulsion was subjected to phosgenation and oligomerization while flowing through phosgene and a pipe reactor at a linear speed of 1.7 m / sec for 20 seconds. At this time, the reaction temperature was adjusted to 60 ° C., respectively, and both were externally cooled to 35 ° C. before entering the next oligomerization tank. The oligomerized emulsion thus obtained from the pipe reactor is further introduced into a reaction vessel equipped with a stirrer having an internal volume of 50 liters, stirred at 30 ° C. in a nitrogen gas atmosphere, and oligomerized, whereby an aqueous phase is obtained. After the unreacted BPA-Na present therein was completely consumed, the aqueous phase and the organic phase were allowed to stand and separate to obtain an oligomeric methylene chloride solution.
[0073]
  In the oligomerization, a 2% by weight aqueous solution of triethylamine and a 24% by weight methylene chloride solution of pt-butylphenol were respectively added to the oligomerization tank at a flow rate shown in Table 1. At the time of adding pt-butylphenol, the phosgene content in the reaction liquid in the oligomerization tank was 0.001% by weight or less. At this time, the viscosity average molecular weight (Mv) of the oligomer, the terminal chloroformate group concentration and the terminal phenolic OH group concentration, the amount of unreacted pt-butylphenol and the amount of PTBPC in the oligomer composition were measured. Described.
[0074]
  50 kg of the methylene chloride solution of the above oligomer composition was charged into a reaction vessel equipped with a foudler blade with an internal volume of 150 liters, and 25 kg of methylene chloride for dilution was added thereto. 6 kg of water and 2.2 g of triethylamine were added, and the mixture was stirred at 10 ° C. in a nitrogen gas atmosphere and subjected to a polycondensation reaction for 120 minutes to obtain a polycarbonate resin.
[0075]
  To this reaction solution, 30 kg of methylene chloride and 7 kg of water were added and stirred for 20 minutes. Then, stirring was stopped and the aqueous phase and the organic phase were separated. To the separated organic phase, 20 kg of 0.1N hydrochloric acid was added and stirred for 15 minutes to extract triethylamine and a small amount of remaining alkali component, and then stirring was stopped to separate the aqueous phase and the organic phase. Further, 20 kg of pure water was added to the separated organic phase, and the mixture was stirred for 15 minutes, and then the stirring was stopped to separate the aqueous phase and the organic phase. This operation was repeated (three times) until no chlorine ions were detected in the extracted waste water.
[0076]
  The obtained purified polycarbonate resin solution was faded into warm water to obtain polymer particles, and dried at 120 ° C. for 48 hours in a nitrogen atmosphere with a ventilating dryer.
In addition, in order to confirm reproducibility in each Example, it implemented twice each.
  About the polycarbonate resin obtained in each Example (hereinafter referred to as “C-1” to “C-5”), the molecular end relative to the average molecular weight (Mv), molecular end OH group amount (OH), and total molecular end group amount The proportion of the monophenol group and the viscosity of the coating solution were measured, and the results are shown in Table 1. A polycarbonate resin with controlled molecular end group weight and molecular weight was obtained with good reproducibility, and the viscosity of the coating solution was also stable.
[0077]
  [Comparative Example 1]
  In Example 1, a methylene chloride solution of pt-butylphenol was introduced into a pipe reactor and then contacted with phosgene. The same operation as in Example 1 was performed except that the temperature during polycondensation was set to 30 ° C.
  [Comparative Example 2]
  In Example 2, a methylene chloride solution of pt-butylphenol was introduced into a pipe reactor and then contacted with phosgene, and the same operation as in Example 2 was performed except that the temperature during polycondensation was 30 ° C.
[0078]
  [Comparative Example 3]
  In Example 3, a methylene chloride solution of pt-butylphenol was introduced into a pipe reactor and then contacted with phosgene, and the same operation as in Example 3 was performed except that the temperature during polycondensation was 30 ° C.
  [Comparative Example 4] The same operation as in Example 3 was carried out except that a methylene chloride solution of pt-butylphenol was added during polycondensation in Example 3 and the temperature during polycondensation was changed to 30 ° C.
[0079]
  [Comparative Example 5]
  In Example 4, a methylene chloride solution of pt-butylphenol was introduced into a pipe reactor and then contacted with phosgene, and the same operation as in Example 4 was performed, except that the temperature during polycondensation was 30 ° C.
  [Comparative Example 6]
  In Example 5, a methylene chloride solution of pt-butylphenol was added during polycondensation, and the same operation as in Example 5 was performed except that the temperature during polycondensation was set to 30 ° C.
[0080]
  In order to confirm reproducibility in the same manner as in Examples 1 to 5 for Comparative Examples 1 to 6, each was carried out twice, and the obtained polycarbonate resins (hereinafter referred to as “C-6” to “C-11”). Various characteristics were evaluated for the following, and the results are shown in Table 2. The molecular end groups and molecular weights of the obtained polycarbonate resin had no variation reproducibility. As a result, the viscosity of the coating solution varies greatly, and cannot be used as it is, and it is necessary to adjust the viscosity by blending polycarbonate resins having different molecular weights.
[0081]
  [Example 6]
  The respective oligomers obtained in Examples 1 and 2 were mixed in the proportions shown in Table 3, charged into a reaction vessel equipped with a fouler blade having an internal volume of 150 liters, to which 25 kg of methylene chloride for dilution was added, and further 25% by weight A sodium hydroxide aqueous solution (5.36 kg), water (6 kg) and triethylamine (2.2 g) were added, and the mixture was stirred at 10 ° C. in a nitrogen gas atmosphere, and subjected to a polycondensation reaction for 120 minutes to obtain a polycarbonate resin.
[0082]
  To this reaction solution, 30 kg of methylene chloride and 7 kg of water were added and stirred for 20 minutes. Then, stirring was stopped and the aqueous phase and the organic phase were separated. To the separated organic phase, 20 kg of 0.1N hydrochloric acid was added and stirred for 15 minutes to extract triethylamine and a small amount of remaining alkali component, and then stirring was stopped to separate the aqueous phase and the organic phase. Further, 20 kg of pure water was added to the separated organic phase, and the mixture was stirred for 15 minutes, and then the stirring was stopped to separate the aqueous phase and the organic phase. This operation was repeated (three times) until no chlorine ions were detected in the extracted waste water.
  The obtained purified polycarbonate resin solution was faded into warm water to obtain polymer particles, and dried at 120 ° C. for 48 hours in a nitrogen atmosphere with a ventilating dryer.
[0083]
  [Comparative Example 7]
  The oligomers obtained in Examples 1 and 2 without introducing the methylene chloride solution of pt-butylphenol at the time of the oligomerization reaction were mixed in the proportions shown in Table 3, and a reactor having a fouler blade with an internal volume of 150 liters was used. In this, 25 kg of methylene chloride for dilution was added, and 5.08 kg of 25% by weight sodium hydroxide aqueous solution, 6 kg of water, and 2.2 g of triethylamine, 0.61 kg of 24% methylene chloride solution of pt-butylphenol were added. In addition, the mixture was stirred at 10 ° C. in a nitrogen gas atmosphere, and a polycondensation reaction was performed for 120 minutes to obtain a polycarbonate resin.
[0084]
  To this reaction solution, 30 kg of methylene chloride and 7 kg of water were added and stirred for 20 minutes. Then, stirring was stopped and the aqueous phase and the organic phase were separated. To the separated organic phase, 20 kg of 0.1N hydrochloric acid was added and stirred for 15 minutes to extract triethylamine and a small amount of remaining alkali component, and then stirring was stopped to separate the aqueous phase and the organic phase. Further, 20 kg of pure water was added to the separated organic phase, and the mixture was stirred for 15 minutes, and then the stirring was stopped to separate the aqueous phase and the organic phase. This operation was repeated (three times) until no chlorine ions were detected in the extracted waste water.
[0085]
  The obtained purified polycarbonate resin solution was faded into warm water to obtain polymer particles, and dried at 120 ° C. for 48 hours in a nitrogen atmosphere with a ventilating dryer.
In order to confirm the reproducibility in the same manner for Example 6 and Comparative Example 7, various properties were evaluated for the polycarbonate resins (hereinafter referred to as “C-12” and “C-13”) that were obtained twice each. The results are shown in Table 3.
  In Example 6, a stable molecular end group amount, molecular weight, and coating solution can be obtained, whereas in Comparative Example 7, the molecular end group amount and molecular weight vary, there is no reproducibility, and the viscosity of the coating solution varies greatly. It could not be used as a liquid, and it was necessary to adjust the viscosity by blending polycarbonate resins having different molecular weights.
[0086]
[Table 1]

[0087]
[Table 2]

[0088]
[Table 3]

[0089]
10 parts by weight of a bisazo compound represented by the following (A) was added to 150 parts by weight of 4-methoxy-4-methylpentanone-2 and pulverized and dispersed in a sand grind mill. The obtained pigment dispersion is added to a 5% dimethoxyethane solution of polyvinyl butyral (trade name BH-3, manufactured by Sekisui Chemical Co., Ltd.), and finally a dispersion having a solid concentration of 4.0% is prepared. did.
[0090]
[Chemical 6]

[0091]
  An aluminum cylinder having an outer diameter of 80 mm, a length of 340 mm, and a wall thickness of 2.0 mm is dip-coated on the dispersion obtained in this manner so that the dry film thickness is about 0.4 μm. A charge generation layer was provided. Next, this aluminum cylinder was obtained by dissolving 90 parts by weight of the hydrazone compound represented by the following (B) and 100 parts by weight of the polycarbonate resin obtained in Examples 1 to 3 and Comparative Example 2 in 900 parts by weight of dioxane. A charge transfer layer was formed by dip coating in a coating solution and a film thickness after drying of 20 μm to prepare a photoreceptor.
[0092]
[Chemical 7]

[0093]
  The photoconductor produced in this way was installed in an evaluation machine that imitated a copying machine and a printer, and 100,000 copy tests were conducted to measure the most stable electrical characteristics at that time. The results are shown in Table 4. Here, a method for measuring each potential will be briefly described. The developing tank of the copying machine was removed, and an electrometer sensor was attached to that part. Next, place a white document and a black document in half on the document table of the copier, and measure the potential of the black background when charging this document as the charged potential (Vo) and the potential of the white background as sensitivity (VL). did. The potential remaining after static elimination was measured as the residual potential (Vr).
  Table 4 shows the evaluation results using the polycarbonate resins produced in Examples 1 to 7 and Comparative Examples 1 to 7.
[0094]
[Table 4]

[0095]
【The invention's effect】
  The polycarbonate of the present invention is excellent in controllability of molecular weight and molecular end group and can be produced with good reproducibility. Further, by using this polycarbonate resin, an electrophotographic photoreceptor having good electrical characteristics can be provided.

Claims (4)

An electrophotographic photosensitive member having at least a photosensitive layer on a conductive substrate, wherein the binder resin of the photosensitive layer is a polycarbonate resin satisfying the following a) to d).
A) When an oligomer composition is obtained by reacting at least one aromatic diol with a carbonate-forming compound using a monophenol as a molecular weight regulator, the concentration of the carbonate-forming compound is 0.001% by weight. The oligomer composition obtained by mixing after becoming the following is obtained by polymerizing under polycondensation conditions ,
B) The molecular terminal OH group amount is 20 μeq / g or less,
C) The ratio of the molecular end monophenol group amount to the total molecular end group amount is 90% or more,
D) The viscosity average molecular weight is 5,000 to 100,000. At least an organic solvent, charge transport materials, and the following a) to d) for an electrophotographic photoreceptor coating solution containing a Polycarbonate resin satisfying.
A) When an oligomer composition is obtained by reacting at least one aromatic diol with a carbonate-forming compound using a monophenol as a molecular weight regulator, the concentration of the carbonate-forming compound is 0.001% by weight. The oligomer composition obtained by mixing after becoming the following is obtained by polymerizing under polycondensation conditions ,
B) The molecular terminal OH group amount is 20 μeq / g or less,
C) The ratio of the molecular end monophenol group amount to the total molecular end group amount is 90% or more,
D) The viscosity average molecular weight is 5,000 to 100,000. After reacting at least one aromatic diol with a carbonate-forming compound and the concentration of the carbonate-forming compound is 0.001% by weight or less, monophenols are mixed to obtain an average viscosity molecular weight of 500 to 10, 000, a step of obtaining a carbonate oligomer composition in which the ratio of unreacted monophenols to charged monophenols is 50% or less, and then the polycondensation of the carbonate oligomer composition in the presence of an alkali to produce a viscosity average molecular weight of 5,000 to A method for producing a binder resin for an electrophotographic photosensitive member, comprising a step of obtaining 100,000 polycarbonate resin. After reacting at least one aromatic diol with a carbonate-forming compound and the concentration of the carbonate-forming compound is 0.001% by weight or less, monophenols are mixed to obtain an average viscosity molecular weight of 500 to 10, 000, a step of obtaining a carbonate oligomer composition in which the ratio of unreacted monophenols to the charged monophenols is 50% or less, and then the polycondensation of the carbonate oligomer composition in the presence of an alkali to give a viscosity average molecular weight of 5 , 000-100 , A method for producing a polycarbonate resin for a coating solution for an electrophotographic photosensitive member, comprising a step of obtaining a polycarbonate resin of 000.