JP4192683B2 - Toner for developing electrostatic image, charge control agent for toner, and production method thereof - Google Patents

Description

【００３２】
これより本発明で使用することのできるキシレン樹脂の水酸基価（ＯＨ価）は１００〜２００（ｍｇＫＯＨ／ｇ）であることが好ましく、より好ましくは１１０〜１７０（ｍｇＫＯＨ／ｇ）である。水酸基価が１００（ｍｇＫＯＨ／ｇ）よりも小さいと未反応のアニリンが残存する場合があり、荷電制御剤中のアニリン含有量が１００ｐｐｍを超えてしまう。また水酸基価が２００（ｍｇＫＯＨ／ｇ）よりも大きいと、−ＯＨ基が過剰に存在するため、水分の影響を受けやすくなり、荷電制御剤として環境安定性が低下してしまい、高温高湿下での帯電量の低下による機内飛散、かぶりの増加、低温低湿下での過度の帯電量上昇等の問題が生じてしまう。
【００３３】
また平均分子量は８００〜１８００のものを用いることが好ましく、より好ましくは１０００〜１４００である。この範囲において使用することによりニグロシンベースを良好に分散させることができる。平均分子量が８００以下になってしまうとニグロシンベースの分散不良を起こしやすく、また平均分子量が１８００よりも大きくなってしまうと、軟化温度が高くなり、高温下でのニグロシンベースとの混合が必要になったり、生産性が悪くなってしまう。
具体的に好ましいキシレン樹脂としてはは三菱ガス化学社製ニカノールＨＰ−１００、ＨＰ−７０、ＨＰ−１５０等の熱可塑性キシレン樹脂があげられる。
【００３４】
これらのニグロシンベースとキシレン樹脂とを混合することにより本願発明の組成物を得ることができる。混合する方法としては、（１）キシレン樹脂に可溶な溶媒中に溶解させた上でニグロシンベースを添加して溶液中で混合する方法、（２）混練機等を用いてキシレン樹脂を溶融させた状態でニグロシンベースを添加して混合する方法等がある。具体的には以下のようになる。
（１）ニグロシンベースとキシレン樹脂を溶媒に溶解し、溶媒の沸点温度近傍で１〜２時間加熱しながら混合を行なった後、溶媒を除去し、水中に排出を行い、ろ過、水洗、乾燥を行い組成物を得る。ここでニグロシンベース中のアニリンは、キシレン樹脂と反応し、一部にアミン変性されたキシレン樹脂が生成することにより、アニリンが除去され得られる組成物は残存するアニリンをほとんど含まないものとなる。ここで得られる組成物はキシレン樹脂中にニグロシンベースが分散した状態である。また必要ならば粉砕工程を経て所望の粒度にして組成物を荷電制御剤とすればよい。
ここで具体的に使用する溶媒としては、キシレン樹脂とアニリンの双方を溶解するものであれば使用可能であるが、中でもプロピレングリコールモノメチルエーテルの如きセロソルブ系の溶媒を用いることが好ましい。
（２）ニグロシンベースとキシレン樹脂を加熱ニーダー、バンバリーミキサー、等の混練機に投入して十分に混合し、キシレン樹脂の軟化温度以上の温度で溶融混練を行なう。これによりキシレン樹脂中にニグロシンベースが分散する。このときにニグロシンベース中に含まれるアニリンはキシレン樹脂と反応し、一部にアミン変性されたキシレン樹脂が生成することにより、アニリンが除去され得られる組成物は残存するアニリンをほとんど含まないものとなる。ここで得られる組成物はキシレン樹脂中にニグロシンベースが分散した状態である。さらにこの組成物を粗砕、粉砕して所望の粒度に調整することにより組成物を荷電制御剤とすればよい。
【００３５】
ニグロシンベースとキシレン樹脂との混合比率は、２０：８０〜７０：３０の範囲であれば良好な荷電制御剤を得ることができる。ニグロシンベースの比率が２０よりも小さくなってしまうと荷電制御剤として良好な正電荷を付与することが困難となり、またニグロシンベースの比率が７０を超えてしまうと残存するアニリンの除去が困難となり、荷電制御剤中のアニリン量が１００ｐｐｍよりも大きくなってしまう場合がある。
【００３６】
本発明の静電荷像現像用トナーにおける荷電制御剤の使用量は、使用する結着樹脂の種類により異なるが、通常、結着樹脂１００重量部に対して０．１〜１０重量部、好ましくは０．５〜５重量部、より好ましくは０．８〜３重量部である。また、荷電制御剤の粒径は、体積平均粒径で３０μｍ以下であればよく、２μｍ以上１５μｍ以下であることがより好ましい。２μｍよりも小さいとトナーに過度の帯電量上昇を引き起こしてしまい使用が困難になる。また１５μｍよりも大きいとトナー中に均一に分散、配合を行なうことが困難になってしまう場合がある。
【００３７】
本発明の静電荷像現像用トナーにおいては、荷電制御剤として、ニグロシン染料とともに、トナーに正帯電性を付与することのできる他の荷電制御剤を補助的に用いることもできる。このような荷電制御剤としては、従来からトナーに正帯電性を付与することができることが知られた公知の荷電制御剤であればいずれのものであってもよいが、その中でも、第四級アンモニウム塩化合物、トリフェニルメタン系の塩基性染料が好ましい。
【００３８】
本発明の静電荷像現像用トナーの構成成分としては、上記本発明の荷電制御剤以外に、トナーを構成する公知の材料である、結着樹脂および着色剤が用いられる。磁性トナーを得る場合にはさらに磁性粉体が用いられるが、磁性粉体を用いる場合には、磁性粉体が着色剤としても利用されてもよい。したがって、本発明において、着色剤には磁性粉体も含まれる。静電荷像現像用トナーには、更に必要に応じ離型剤、滑剤、流動性改良剤、研磨剤、導電性付与剤、画像剥離防止剤等が内添または外添される。
【００３９】
本発明の静電荷像現像用トナーに用いられる結着樹脂は、従来静電荷像現像用トナーの結着樹脂として公知のものであればいずれも用いることができる。使用することのできる結着樹脂としては、例えば、ポリスチレン、ポリ−ｐ−クロルスチレン、ポリビニルトルエンなどのスチレン及びその誘導体の単重合体；スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体などのスチレン−スチレン誘導体共重合体；スチレン−ビニルナフタレン共重合体、スチレン−アクリル酸系共重合体、スチレン−メタクリル酸系共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体などのスチレン系共重合体；ポリ塩化ビニル、フェノール樹脂、天然変性フェノール樹脂、天然樹脂変性マレイン酸樹脂、アクリル樹脂、メタクリル樹脂、ポリ酢酸ビニル、シリコーン樹脂、ポリエステル樹脂、ポリウレタン、ポリアミド樹脂、フラン樹脂、エポキシ樹脂、ポリビニルブチラール、テルペン樹脂、クマロンインデン樹脂、石油系樹脂などがあげられる。
【００４０】
これらのなかでも、スチレン単重合体、スチレン−スチレン誘導体共重合体、スチレン−アクリル酸系共重合体、スチレン−メタクリル酸系共重合体が特に好ましいものである。
【００４１】
スチレン−アクリル酸系共重合体、スチレン−メタクリル酸系共重合体のスチレンモノマーに対するコモノマーとしては、例えば、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸ドデシル、アクリル酸オクチル、アクリル酸−２−エチルヘキシル、アクリル酸フェニル、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸オクチルなどがあげられる。
【００４２】
また架橋されたスチレン系共重合体も好ましい結着樹脂である。架橋されたスチレン系共重合体を製造するためにスチレンと共に用いられるコモノマーとしては、上記スチレン誘導体、アクリル酸、メタクリル酸、アクリル酸エステルまたはメタクリル酸エステルの他、アクリロニトリル、メタクリロニトリル、アクリルアミドなどの二重結合を有するモノカルボン酸もしくはその置換体；例えば、マレイン酸、マレイン酸メチル、マレイン酸ブチル、マレイン酸ジメチルなどの二重結合を有するジカルボン酸およびその置換体；例えば塩化ビニル、酢酸ビニル、安息香酸ビニルなどのビニルエステル類；例えばエチレン、プロピレン、ブチレンなどのエチレン系オレフィン類；例えばビニルメチルケトン、ビニルヘキシルケトンなどのビニルケトン類；例えばビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテルなどのビニルエーテル類；等のビニル単量体が単独もしくは２種以上用いられる。
【００４３】
架橋剤としては、主として２個以上の重合可能な二重結合を有する化合物が用いられ、例えば、ジビニルベンゼン、ジビニルナフタレンなどの芳香族ジビニル化合物；例えばエチレングリコールジアクリレート、エチレングリコールジメタクリレート、１，３−ブタンジオールジメタクリレート、ポリエチレングリコールジアクリレート、ポリエチレングリコールジメタクリレートなどの二重結合を２個有するカルボン酸エステル；ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド、ジビニルスルホンなどのジビニル化合物；及び３個以上のビニル基を有する化合物；が単独もしくは混合物として用いられる。これら架橋剤は、他のモノマー成分１００重量部に対し、０．０１〜５重量部程度、より好ましくは０．０３〜３重量部程度の量で用いられる。
【００４４】
また、結着樹脂は、ＧＰＣにより測定される分子量分布で３×１０³〜５×１０⁴の領域に少なくともひとつのピークを有し、１０⁵以上の領域に少なくとも一つのピークあるいはショルダーを有するスチレン系共重合体が定着性の点から好ましい。このような分子量分布を有する結着樹脂は、平均分子量が異なる二種以上の樹脂を混合することによって製造することができるし、上記架橋剤を用いて架橋樹脂とすることにより製造することもできる。
【００４５】
なお、上記ＧＰＣによる分子量分布は、例えば次の条件で測定される。またキシレン樹脂についても同様に測定することができる。
４０℃のヒートチャンバ中でカラムを安定化させ、この温度におけるカラムに、溶媒としてテトラヒドロフラン（ＴＨＦ）を毎分１ｍｌの流速で流し、ＴＨＦに溶解した試料溶液を約１００μｌ注入して測定する。試料の分子量測定にあたっては、試料の有する分子量分布を数種の単分散ポリスチレン標準試料により作成された検量線の対数値とカウント数との関係から算出する。
【００４６】
検量線作成用の標準ポリスチレン試料としては、例えば、東ソー社製あるいは昭和電工社製の分子量が１０²〜１０⁷程度のものを用い、少なくとも１０点程度の標準ポリスチレン試料を用いるのが適当である。検出器にはＲＩ（屈折率）検出器を用いる。なお、カラムとしては市販のポリスチレンジェルカラムを複数本組み合わせるのが良い。例えば、昭和電工社製のｓｈｏｄｅｘ ＧＰＣ ＫＦ−８０１、８０２、８０３、８０４、８０５、８０６、８０７、８００Ｐの組み合わせや、東ソー社製のＴＳＫｇｅｌ Ｇ１０００Ｈ（ＨＸＬ）、Ｇ２０００Ｈ（ＨＸＬ）、Ｇ３０００Ｈ（ＨＸＬ）、Ｇ４０００Ｈ（ＨＸＬ）、Ｇ５０００Ｈ（ＨＸＬ）、Ｇ６０００Ｈ（ＨＸＬ）、Ｇ７０００Ｈ（ＨＸＬ）、ＴＳＫｇｕａｒｄｃｏｌｕｍｎの組み合わせをあげることができる。
【００４７】
また測定用サンプルは以下のようにして作成する。すなわち、試料をＴＨＦ中に入れ、数時間放置した後、充分に振とうし、試料の合一体がなくなるまでＴＨＦと良く混合し、さらに１２時間以上静置する。この時、ＴＨＦ中への放置時間が２４時間以上となるようにする。その後、サンプル処理フィルタ（ポアサイズ０．４５〜０．５μｍ、例えばマイショリディスクＨ−２５−５ 東ソー社製、エキクロディスク２５ＣＲ ゲルマン サイエンス ジャパン社製等が利用できる）を通過させたものをＧＰＣ測定用サンプルとする。また、サンプル濃度は、樹脂成分が０．５〜５ｍｇ／ｍｌとなるように調整する。
【００４８】
なお、ビニル重合体の製造に当たっては重合開始剤が用いられるが、重合開始剤としては、従来公知のものの何れも用いることができる。重合開始剤としては、例えば、過酸化ベンゾイル、過酸化ラウロイル、ターシャリーブチルハイドロパーオキサイド、ターシャリーブチルパーオキシベンゾエート、ジターシャリーブチルパーオキサイド、クメンハイドロパーオキサイド、ジクミルパーオキサイド、アゾイソブチロニトリル、アゾビスバレロニトリルなどが通常好ましく用いられる。開始剤のビニルモノマーに対する使用割合は、０．２〜５重量％が一般的である。重合温度は、使用するモノマーおよび開始剤の種類に応じ適宜選定される。
【００４９】
また、ポリエステル樹脂も本発明の静電荷像現像用トナーの結着樹脂として使用することは可能である。ポリエステル樹脂を構成するアルコール成分としてはエチレングリコール、プロピレングリコール、１，３−ブタンジオール、１，４−ブタンジオール、２，３−ブタンジオール、ジエチレングリコール、トリエチレングリコール、１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコール、２−エチル−１，３−ヘキサンジオール、水素化ビスフェニールＡ、ビスフェノール誘導体等のジオール類、グリセリン、ソルビット、ソルビタン等の多価アルコール類が挙げられる。
【００５０】
酸成分としては二価のカルボン酸として、フタル酸、テレフタル酸、イソフタル酸、無水フタル酸などのベンゼンジカルボン酸類またはその無水物；コハク酸、アジピン酸、セバシン酸、アゼライン酸などのアルキルジカルボン酸類またはその無水物；またさらに炭素数１６〜１８のアルキル基で置換されたコハク酸もしくはその無水物；フマル酸、マレイン酸、シトラコン酸、イタコン酸などの不飽和ジカルボン酸またはその無水物等が挙げられ、三価以上のカルボン酸としてはトリメリット酸、ピロメリット酸、ベンゾフェノンテトラカルボン酸やその無水物等が挙げられる。
【００５１】
好ましいアルコール成分は、前記一般式１で表されるビスフェノール誘導体であり、好ましい酸成分はフタル酸、テレフタル酸、イソフタル酸またはその無水物、コハク酸、ｎ−ドデセニルコハク酸またはその無水物、フマル酸、マレイン酸、無水マレイン酸等のジカルボン酸類、トリメリット酸またはその無水物等のトリカルボン酸類である。
【００５２】
さらに、加圧定着方式を用いる場合には、圧力定着トナー用結着樹脂の使用が可能であり、例えばポリエチレン、ポリプロピレン、ポリメチレン、ポリウレタンエストマー、エチレン−エチルアクリレート共重合体、エチレン−酢酸ビニル共重合体、アイオノマー樹脂、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、線状飽和ポリエステル、パラフィンなどがあげられる。
【００５３】
本発明の静電荷像現像用トナーにおいて用いることができる着色剤としては、従来トナーの製造において用いられることが知られた着色剤がいずれも使用可能であり、これら着色剤の例としては、脂肪酸金属塩、種々のカーボンブラック、アニリンブラック、アセチレンブラック、鉄黒、フタロシアニン系、ローダミン系、キナクリドン系、トリアリールメタン系、アントラキノン系、アゾ系、ジアゾ系、ベンズイミダゾロン系などの染顔料があげられる。これらは単独で或いは２種以上を混合して使用することができる。通常結着樹脂の１００重量部に対し、０．１〜２０重量部、好ましくは０．３〜１０重量部の添加量がよい。
【００５４】
本発明において使用する着色剤は上記のうち、ＢＥＴ法による比表面積が３０〜３００ｍ² ／ｇのものを用いるとより好ましい効果を見い出すことができる。特に本発明の荷電制御剤とともにトナーに用いることにより、カブリ、機内飛散の問題のない良好な品質のトナーを得ることができる。
着色剤のＢＥＴ法による比表面積が３００ｍ² ／ｇを超えるものを用いると、結着樹脂中への分散、分配が困難になり、カブリが増大して、かつトナーの機内飛散が増大して行く傾向があり複写画像の品質が悪化してしまう場合がある。特に高温高湿環境では顕著にかぶりが生じ、機内中のトナー飛散が生じてしまう場合がある。また比表面積が３０ｍ² ／ｇより小さいものを用いると、着色剤の粒子がトナー粒子に十分な着色を行うことが困難になり、トナーとして所望の画像濃度を得ることができなくなる場合がある。
【００５５】
本発明の着色剤のＢＥＴ比表面積測定は、乾燥した状態の着色剤サンプルを、気体吸着法（流動法）である、ユアサアイオニクス社製、マルチソーブ１２を用いて行った。キャリアガスとしては窒素−ヘリウムの混合ガスを用いた。そして脱着ピークの値からＢＥＴ比表面積を算出した。
【００５６】
また、本発明の静電荷像現像用トナーにおいて用いられる磁性粉体は、従来磁性トナーの製造において使用されている強磁性の元素を含む合金、化合物等の何れの粉体であってもよい。これら磁性粉体の例としては、マグネタイト、マグヘマイト、フェライト等の酸化鉄または二価金属と酸化鉄との化合物、鉄、コバルト、ニッケルのような金属或いはこれらの金属のアルミニウム、コバルト、銅、鉛、マグネシウム、スズ、亜鉛、アンチモン、ベリリウム、ビスマス、カドミウム、カルシウム、マンガン、セレン、チタン、タングステン、バナジウムのような金属の合金の粉体およびこれらの混合物があげられる。これらの磁性粉体は、平均粒径が０．１〜２μｍ、更には０．１〜０．５μｍ程度のものが好ましい。また、磁性粉体のトナー中の含有量は、熱可塑性樹脂１００質量部に対して、約２０〜２００質量部、好ましくは４０〜１５０質量部である。また、トナーの飽和磁化としては、１５〜３５ｅｍｕ／ｇ（測定磁場 １キロエルステッド）が好ましい。
【００５７】
本発明のトナーは、キャリアと混合して二成分系現像剤として使用することができる。本発明のトナーとともに用いることのできるキャリアとしては、従来公知のキャリアであればいずれであってもよい。使用することができるキャリアとしては、例えば、鉄粉、フェライト粉、ニッケル粉のような磁性粉体等、あるいはこれらの表面を樹脂などで処理したものが挙げられる。キャリア表面を被覆する樹脂としては、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、アクリル酸エステル共重合体、メタクリル酸エステル共重合体、フッ素含有樹脂、シリコーン含有樹脂、ポリアミド樹脂、アイオノマー樹脂、ポリフェニレンサルファイド樹脂など、あるいはこれらの混合物があげられる。これらのなかでは、スペントトナーの形成が少ないためフッ素含有樹脂、シリコーン含有樹脂が特に好ましい。
【００５８】
本発明の静電荷像現像用トナーの粒径は、重量平均粒径が１〜３０μｍ、好ましくは３〜１５μｍであることが望ましい。特に、５μｍ以下の粒径を有するトナー粒子が１２〜６０個数％含有され、８〜１２．７μｍの粒径を有するトナー粒子が１〜３３個数％含有され、１６μｍ以上の粒径を有するトナー粒子が２．０重量％以下含有され、トナーの重量平均粒径が４〜１２μｍであるものが、現像特性の上からはより好ましい。なお、トナーの粒度分布測定は、例えばコールターカウンターを用いて測定することができる。
【００５９】
本発明のトナーは、さらに必要に応じて離型剤、滑剤、流動性改良剤、研磨剤、導電性付与剤、画像剥離防止剤等のトナーの製造に当たり使用されている公知の添加剤を内添、あるいは外添することができるが、これら添加剤の例としては、離型剤としては、例えば低分子量ポリエチレン、低分子量ポリプロピレン、マイクロクリスタリンワックス、カルナバワックス、サゾールワックス、パラフィンワックスなどのワックス状物質があげられ、これらは通常０．５〜５重量％程度の量でトナー中に加えられる。また、滑剤としては、ポリフッ化ビニリデン、ステアリン酸亜鉛などが、流動性改良剤としては、乾式法あるいは湿式法で製造したシリカ、酸化アルミニウム、酸化チタン、珪素アルミニウム共酸化物、珪素チタン共酸化物およびこれらを疎水性化処理したものなどが、研磨剤としては窒化珪素、酸化セリウム、炭化ケイ素、チタン酸ストロンチウム、タングステンカーバイド、炭酸カルシウムおよびこれらを疎水化処理したものなどが、導電性付与剤としてはカーボンブラック、酸化スズなどがあげられる。また、ポリビニリデンフルオライドなどのフッ素含有重合体の微粉末は、流動性、研磨性、帯電安定性などの点から好ましいものである。
【００６０】
なお、本発明においては、疎水化処理されたシリカ、疎水化処理された酸化アルミニウム、疎水化処理された珪素アルミニウム共酸化物あるいは疎水化処理された珪素チタン共酸化物微粉体を外添剤として用いることが好ましい。シリカ微粉体の疎水化処理としては、シリコーンオイルやジクロロジメチルシラン、ヘキサメチルジシラザン、テトラメチルジシラザンなどのシランカップリング剤による処理等があげられる。また、ブローオフ法により測定したときに、鉄粉キャリアに対してプラスのトリボ電荷を有する正帯電性のシリカを用いることが好ましい。この正帯電性のシリカを得るためには、側鎖に窒素原子を少なくとも１つ有するオルガノ基を有するシリコーンオイル、あるいは窒素含有のシランカップリング剤で処理すればよい。疎水化処理されたシリカ微粉体の使用量は、現像剤重量当り、０．０１〜２０％、好ましくは０．０３〜５％である。
【００６１】
本発明に係るトナーは、従来から公知のトナーの製造方法を用いて製造することができる。一般的には、上述したようなトナー構成材料を、ボールミル、ヘンシェルミキサーなどの混合機により充分混合したのち、熱ロールニーダー、一軸あるいは二軸のエクストルーダーなどの熱混練機を用いて良く混練し、冷却固化後、ハンマーミルなどの粉砕機を用いて機械的に粗粉砕し、次いでジェットミルなどにより微粉砕した後、分級する方法が好ましい。しかし、トナーの製造法はこの方法に限られるものではなく、結着樹脂溶液中に他のトナー構成材料を分散した後、噴霧乾燥する方法、所謂マイクロカプセル法によりトナーを製造する方法、結着樹脂を形成する単量体に所定材料を混合し、乳化あるいは懸濁重合を行いトナーを得る重合法トナー製造法など他の方法も任意に採用することができる。
【００６２】
さらに、必要に応じ、分級されたトナーと外添剤をヘンシェルミキサー等の混合機を用いて十分に混合し、篩い工程を経て、本発明の静電荷現像用トナーを製造することができる。
【００６３】
【実施例】
以下、本発明を実施例によりさらに具体的に説明するが、本発明の態様はこれらの実施例に限定されるものではない。
【００６４】
[ニグロシンベースの製造例１]
アニリン、アニリン塩酸塩を塩化鉄、鉄及び塩酸の存在下にニトロベンゼンで１６０〜１８０℃で酸化、反応させることにより粗製ニグロシンを得た。さらに粗製ニグロシンを中和した後にアニリン、水酸化ナトリウム溶液を加えベース化処理を行い、スクリューデカンタの遠心分離によりニグロシンと水酸化鉄の沈殿物に分離し、水酸化鉄の沈殿物を除去した後、得られた液を水洗した。水洗後、残存するニトロベンゼンを除去するために、さらにメタノールを添加して６０℃に加熱しながら攪拌、洗浄した後、ろ過、乾燥を行い、ジェットミルにて平均粒径７μｍに粉砕を行ないニグロシンベース１を得た。またニトロベンゼンの含有量は５０ｐｐｍで、アニリンの含有量は２５００ｐｐｍであった。
【００６５】
[ニグロシンベースの製造例２]
市販のニグロシンベースＣＣＡ−１（中央合成化学社製）をメタノール中に溶解し６０℃に加温しながら３０分間攪拌しニトロベンゼンの除去を行なった。さらにメタノールで洗浄を行ない、ろ過、乾燥を行い、ジェットミルにて平均粒径６μｍに粉砕を行ないニグロシンベース２を得た。またニトロベンゼンの含有量は４０ｐｐｍ、アニリンの含有量は２０００ｐｐｍであった。
【００６６】
上記ニグロシンベース１〜２の特性値をまとめると表１のとおりである。
【００６７】
【表１】

【００６８】
[荷電制御剤製造例１]
プロピレングリコールモノメチルエーテル３０００ｇ中にキシレン樹脂（三菱ガス化学社製ＨＰ−１００：平均分子量１２００）を６００ｇ添加して十分に混合、溶解した。これに上記で得られたニグロシンベース１を４００ｇ加えた後に、液温を７０〜８０℃に保ちながら２時間攪拌、混合を行なった。さらに溶媒の沸点以上（１２０℃）に温度を上げ、プロピレングリコールモノメチルエーテルを除去した。更に水で洗浄を行い、乾燥した後に、サンプルミルで粉砕を行い７５０ｇの組成物を得た。（平均粒径７．５μｍ）これを荷電制御剤１とする。
荷電制御剤１に含まれるアニリン含有量及びニトロベンゼン含有量をガスクロマトグラフにて分析したところ、アニリン含有量は２５ｐｐｍ、ニトロベンゼン含有量は１０ｐｐｍであった。
【００６９】
[荷電制御剤製造例２〜６、１０]
表２に示す条件であること以外は、荷電制御剤製造例１と同様にして荷電制御剤２〜６を得た。また荷電制御剤１０はキシレン樹脂を用いる代わりに、ロジン無水マレイン酸樹脂（荒川化学社製マルキード樹脂ＮＯ．３３）を用いる以外は、荷電制御剤１と同様に得られた荷電制御剤である。得られた荷電制御剤の特性値を表２に示す。
【００７０】
【表２】

【００７１】
[荷電制御剤製造例７]
キシレン樹脂（三菱ガス化学社製ＨＰ−１００）６００ｇ、上記で得られたニグロシンベース４００ｇを加圧ニーダを用いて１４０℃にて３０分混合、混練を行なった。取り出し、冷却した後にサンプルミル及びジェットミルにて粉砕を行い７００ｇの組成物を得た。（平均粒径７．７μｍ）これを荷電制御剤７とする。荷電制御剤７に含まれるアニリン含有量及びニトロベンゼン含有量をガスクロマトグラフにて分析したところ、アニリン含有量は５０ｐｐｍ、ニトロベンゼン含有量は２０ｐｐｍであった。
【００７２】
なお、実施例および比較例におけるニグロシン中のニトロベンゼン含有量、アニリン含有量は、いずれもガスクロマトグラフ アジレント（旧ヒューレットパッカード）６８９０型を用い、カラムとしてＨＰ−ＩＮＮＯＷＡＸを用いて測定された。
【００７３】
実施例１
スチレン−アクリル酸ｎブチル共重合体 ５６重量部
磁性酸化鉄 ４０重量部
荷電制御剤１ ２重量部
低分子量ポリプロピレンワックス ２重量部
をヘンシェルミキサーで予備混合した後、二軸加熱混練機に投入し、混練、押し出されてきたものを室温で冷却し、ハンマーミルで粗粉砕してチップ状の粉砕物（以下「チップ」という。）を得た。次いで、これをジェットミル粉砕機で微粉砕し、分級機に導き、１０μｍに平均粒度を有する部分をトナー用微粉末として取り出して、磁性トナー（分級されたトナー母粉体）を得た。
【００７４】
ニグロシンベースの結着樹脂中への分配性を調べるため、所定量のチップ、分級されたトナー母粒子および分級微粉を所定量のクロロホルムに溶解し、上澄み液の吸光度（波長：５６７ｎｍ）を測定し、検量線の値からチップ中、分級されたトナー母粉体中および分級微粉中の荷電制御剤中のニグロシンベースの含有量を求めた。ニグロシベースの含有量は、各々０．８１％、０．８０％、０．８２％であった。
【００７５】
なお、検量線は、ニグロシンベースの添加量を０．５〜２．５重量部とし、これに合わせて結着樹脂であるスチレン−アクリル酸ｎブチル共重合体の量を５７．５〜５５．５重量部と変え、全体の量が１００重量部となるようにすることを除き上記実施例と同様にして磁性トナーを作成し、これらトナーの所定量をクロロホルムの所定量に溶解し、実施例同様にして上澄み液の吸光度（波長：５６７ｎｍ）を測定し、吸光度の値を添加量の値と関連付けてプロットすることにより作成した。上澄み液を形成する場合、調整した液を磁石上に放置することにより磁性紛を十分に沈殿させることができる。
【００７６】
実施例２〜７および比較例１〜２
荷電制御剤１を、表２に記載の各荷電制御剤とすることを除き、実施例１と同様に行い、チップ中、分級されたトナー母粒子中および分級微粉中のニグロシンベースの含有量を求めた。結果を表３に示す。
【００７７】
【表３】

【００７８】
表２から、本発明の荷電制御剤（１〜７）は、チップ中、分級されたトナー母粉体中および分級微粉中のいずれにおいてもニグロシンベースの含有量が配合時の添加量と同じであり、このことから結着樹脂への分配性が良好であることがわかる。これに対し、比較品（荷電制御剤１０、ニグロシンベース１）のニグロシンベースの含有量は、トナー母粉体中で配合時の添加量より少なく、一方分級微粉中では多くなり、いずれもニグロシンベースの分配性が悪いことが分る。分配性の悪化は、ニグロシンベース中のニトロベンゼン量、アニリン量に起因するものと推測される。荷電制御剤中のニグロシンベースの分配性が悪いと、分級微粉を再度原料に戻して再利用する際に安定した品質のトナーを得ることができないため、分級微粉の再利用ができないこととなる。
【００７９】
実施例８
スチレン−アクリル酸ｎブチル共重合体 ８８重量部
カーボンブラック（比表面積１４０ｍ^２／ｇ） ８重量部
荷電制御剤１ ２重量部
低分子量ポリプロピレンワックス ２重量部
をヘンシェルミキサーで予備混合した後、二軸加熱混練機に投入し、混練、押し出されてきたものを室温で冷却し、ハンマーミルで粗粉砕してチップを得た。次いで、これをジェットミル粉砕機で微粉砕し、分級機に導き、１０μｍに平均粒度を有する部分をトナー用微粉末として取り出して、トナー母粉体を得た。このトナー母粉体１００重量部に対し、疎水性シリカ（アエロジルＲ９７２）０．３重量部、タングステンカーバイト（日本新金属社製ＷＣ−１０）を加え、ヘンシェルミキサーで混合した後、このトナーの加熱経時変化を調べた。
【００８０】
加熱経時変化の試験は、トナー及びトナーとキャリア（平均粒径が約１００μｍのシリコーンコートフェライトキャリア）とからなる現像剤（トナー濃度５％）を５０℃の乾燥機中に３日間（７２時間）放置して加熱劣化を促進させた後、市販の複写機（松下電送社製複写機 ＦＰ７１１３）を用いて、２３℃、５０ＲＨの環境条件下、１０，０００枚の連続実写を行うことによった。初期および１０，０００枚複写時の画像濃度は各々１．４１および１．４０であり、また初期および１０，０００枚複写時のカブリは各々０．６および０．５で特に変化はなかった。さらに、１０，０００枚複写後におけるトナー粒子の機内飛散はなく、得られた画像の汚れもなかった。
【００８１】
なお、カブリはフォトボルトにて、反射率を測定することにより行った。１．５％以下が良好な値である。
また、トナーの機内飛散は、複写機の転写チャージャー上に飛散トナーが存在するか否かを確認することにより行った。転写チャージャー上にトナー飛散がみられる場合、これに伴う画像汚れが発生する。
【００８２】
実施例９〜１４および比較例３〜４
荷電制御剤１を、表３に記載の荷電制御剤とすることを除き、実施例８と同様に画像試験を行った。結果を表４に示す。
【００８３】
【表４】

【００８４】
表３から、加熱劣化促進試験後のトナーを用いて現像した場合、本発明のトナーおよび比較トナーは画像濃度においては格別の差はでない一方、本発明のトナーでは、加熱劣化促進試験後においても１０，０００枚複写時にカブリの発生、トナーの機内飛散はみられないのに対し、比較トナーは複写の初期からカブリがみられ、またトナーの機内飛散があり、画像汚れがみられた。これは、多量のニトロベンゼンおよびアニリンの存在によりニグロシン染料の均一分散性が悪くなっていることによるものと推測される。
【００８５】
実施例１５
実施例１と同様にして、１０μｍに平均粒度を有する磁性トナー粉体を得た。この磁性トナー粉体１００重量部に対し、疎水性シリカ（アエロジルＲ９７２）０．３０重量部を加え、ヘンシェルミキサーで混合した。このトナーの加熱経時変化を、実施例８同様１０，０００枚複写後の複写画像濃度、画像のカブリの状態および機内へのトナーの飛散の状況を調べることにより行った。実写試験は、市販の複写機（キャノン社製ＮＰ−４１４５）を用い、２３℃、５０ＲＨの環境条件下で行った。初期および１０，０００枚複写時の画像濃度は各々１．４２および１．４１であり、また初期および１０，０００枚複写時のカブリは各々０．６および０．７であった。さらに、１０，０００枚複写後におけるトナー粒子の機内飛散はなく、得られた画像の汚れもなかった。なお、画像濃度はマクベス光度計を用いて行い、１．３以上の濃度であればよい。
【００８６】
実施例１６〜２１および比較例５〜６
荷電制御剤１を、表３に記載の荷電制御剤とすることを除き、実施例１５と同様に画像試験を行った。結果を表５に示す。
【００８７】
【表５】

【００８８】
表５から、加熱劣化促進試験後のトナーを用いて現像した場合、本発明のトナーでは１０，０００枚複写後も画像濃度は初期と変わらず、またカブリの増加もみられなかった。一方、比較トナーにおいては、初期の画像濃度、許容の範囲の濃度であったが、ニグロシン染料の不均一分散に起因すると推測される、画像濃度の低下が発生し、またカブリは複写開始当初から発生し、１０，０００枚後にはますます激しくなった。また、機内へのトナーの飛散は、本発明品では何れもなかったが、比較トナーでは若干の飛散が見られた。
【００８９】
【発明の効果】
以上述べたように、ニグロシンベースとキシレン樹脂とを混合してなる組成物を静電荷像現像用トナーの荷電制御剤として用いることにより、ニグロシンベースが均一に分散された静電荷像現像用トナーを得ることができる。この荷電制御剤は、アニリン、ニトロベンゼンをほとんど含まないため、この荷電制御剤を用いたトナーは初期から良好な画像濃度を有しカブリのない複写画像を得ることができると共に多数枚の複写を重ねた場合にも画像濃度の低下はなく、また、本発明の静電荷像現像用トナーは加熱経時変化もなく、市販するまであるいは購入後のトナーの貯蔵時、あるいは輸送時などにおける加熱ストレスによる特性変化のない、良好なトナーを得ることができる。また、本発明の荷電制御剤は分配性が良好であるため、分級微粉を再利用することが容易となり、省資源化およびトナー製造時のコストの低減に多いに寄与するものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic charge image developing toner used for developing an electrostatic latent image in an electrophotographic copying machine, a laser beam printer or the like in which an image is formed using electrophotography, electrostatic recording method, etc. The present invention relates to a charge control agent used in the electrostatic image developing toner and a method for producing the charge control agent.
[0002]
[Prior art]
Conventionally, as a method for developing an electrostatic latent image formed on an electrostatic image bearing member such as an electrophotographic photosensitive member or an electrostatic recording member, it can be roughly divided into liquid development in which fine toner is dispersed in an electrically insulating liquid. Two methods are known: a method using an agent (wet development method) and a method using a toner in which a colorant or magnetic powder is dispersed in a binder resin (dry development method). In the dry development method, a two-component developer composed of carrier particles and toner is used.
A method using a one-component developer (usually magnetic toner) consisting only of a toner and a toner is known.
[0003]
The toner for developing an electrostatic image used in these dry development methods usually uses a styrene resin or a polyester resin as a binder resin, kneaded with a colorant such as a dye or a pigment, cooled, and then pulverized. It is manufactured through a classification process. The particle diameter of the toner for developing an electrostatic charge image usually has an average particle diameter of about 1 to 30 μm. In the case of magnetic toner, magnetic powder such as magnetite is further used. Further, as carrier particles used in the two-component developer, iron powder, ferrite, magnetite, etc., which are coated with a hydrophobic resin as required, are used.
[0004]
The electrostatic image developing toner as described above is required to hold positive or negative charges depending on the polarity of the electrostatic latent image to be developed. In order to retain the charge in the toner for developing an electrostatic image, it is possible to use frictional charging properties such as a binder resin as a toner component, but this alone usually has a small charge amount and the polarity is not stable. An image obtained by development is easily fogged and unclear. For this reason, a material called a charge control agent is generally added to the toner in order to impart desirable charging characteristics to the toner.
[0005]
Representative examples of conventional charge control agents include those that impart positive chargeability to the toner, such as basic dyes such as nigrosine dyes and triarylmethane dyes, quaternary ammonium salts, organic tin oxides, As an electron donating substance such as a polymer having an amino group or a toner having a negative chargeability, a metal-containing dye such as a metal complex of a monoazo dye or a chromium-containing organic dye (copper phthalocyanine green, chromium-containing monoazo dye) is used. Can be given.
[0006]
2. Description of the Related Art In recent years, an electrophotographic copying machine or printer often uses an organic photoreceptor, and a positively charged toner is used as a developer for a copying machine using the organic photoreceptor. However, many of the positively chargeable charge control agents used for producing the positively chargeable toner are hydrophilic, and the charge amount tends to decrease under high humidity conditions, while the charge amount decreases under high humidity conditions. Many that do not have the problem that the charge amount becomes unnecessarily high under low humidity. For example, triarylmethane-based dyes exhibit excellent positive chargeability at normal temperature and humidity, but tend to cause a decrease in charge amount at high temperatures and high humidity, and depending on the choice of toner components, charging is not possible at low temperatures and low humidity. It may be uniform. Further, the quaternary ammonium salt has a low charge imparting ability, and the image density may be lowered as the number of copies is increased under high temperature and high humidity.
[0007]
Nigrosine dye, on the other hand, has high charging performance and is a relatively excellent charge control agent, but has poor dispersibility in the toner resin and is difficult to disperse uniformly. The required performance as a charge control agent is such that image density decreases, fogging easily occurs, or toner scattering occurs in the machine as the number of copies increases. It is difficult to obtain something that satisfies the conditions sufficiently. In order to solve these problems, a technique (for example, refer to Patent Document 1) such as rake or acid modification of nigrosine dye has been proposed. When such treatment is performed, charge control in the toner is performed. It may cause a decrease in the dispersibility of the agent or the fluidity of the toner.
[0008]
In addition, since nigrosine dye uses nitrobenzene and aniline as raw materials, the manufactured nigrosine dye also contains a trace amount of aniline and nitrobenzene as a residue. These residues not only adversely affect the characteristics of the toner, such as fogging on the image, image density reduction during toner replenishment, and in-machine scattering, but are also not favorable to the environment and should be used after being removed as much as possible. (For example, refer to Patent Documents 2 and 3).
However, the process for removing aniline and nitrobenzene is complicated and the production process becomes complicated, and it is difficult to use as a charge control agent for toner in terms of cost.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-131868
[Patent Document 2]
JP-A-6-230611
[Patent Document 3]
JP 2002-311652 A
[0010]
[Problems to be solved by the invention]
Thus, the nigrosine dye is a relatively excellent charge control agent, but has various problems. To solve these problems, the charge amount is sufficiently high, the temperature and humidity dependence during development is small, the toner characteristics are not deteriorated by the heat stress before use, the dispersibility to the binder resin is good, and the development characteristics Therefore, there is a need for a charge control agent excellent in durability and durability and a positively chargeable toner containing the same.
[0011]
An object of the present invention is to provide a positively chargeable electrostatic image developing toner having excellent characteristics that does not have the above-described problems, that is, a triboelectric charge amount between a toner and a carrier and a toner carrier such as a toner and a developing sleeve. It is an object of the present invention to provide a positively chargeable toner for developing an electrostatic image capable of forming a stable and stable toner image without being affected by temperature and humidity.
[0012]
Another object of the present invention is to provide a toner for developing a positively chargeable electrostatic charge image that has a stable triboelectric charge amount even when the number of copies increases, and that does not generate fog and scatter toner inside the machine.
[0013]
Another object of the present invention is to provide a positively chargeable image that contains a nigrosine base and a xylene resin as a charge control agent and can form a clear image in which the nigrosine base is uniformly dispersed in the toner without fogging. To provide a toner for developing an electrostatic image.
[0014]
Furthermore, an object of the present invention is to provide a positively chargeable electrostatic image developing toner containing a charge control agent that does not deteriorate the toner characteristics due to thermal stress during toner storage.
[0015]
Another object of the present invention is to provide a charge control agent used for producing a toner for developing an electrostatic image having excellent characteristics.
[0016]
Moreover, the objective of this invention is providing the manufacturing method of the said charge control agent.
[0017]
As a result of intensive studies, the present inventors have found that the above object can be achieved by using a composition obtained by mixing a nigrosine base and a xylene resin as a charge control agent, and have reached the present invention. is there.
[0018]
[Means for Solving the Problems]
That is, the first invention includes, as a charge control agent, a composition obtained by mixing a nigrosine base and a xylene resin in an electrostatic charge image developing toner containing at least a binder resin, a colorant, and a charge control agent. An electrostatic charge image developing toner characterized by the above.
[0019]
The second invention is the electrostatic image developing toner according to the first invention, wherein the charge control agent has an aniline content of 100 ppm or less and a nitrobenzene content of 50 ppm or less. It is.
[0020]
A third invention is the electrostatic image developing toner according to the first or second invention, wherein the xylene resin has a number average molecular weight of 800 to 1800.
[0021]
A fourth invention is the electrostatic image developing toner according to any one of the first to third inventions, wherein the mixing ratio of the nigrosine base and the xylene resin is 20:80 to 70:30. is there.
[0022]
According to a fifth aspect of the present invention, there is provided an electrostatic charge image developing toner comprising a mixture of a nigrosine base and a xylene resin, wherein the aniline content is 100 ppm or less and the nitrobenzene content is 50 ppm or less. The charge control agent used.
[0023]
The sixth invention is the charge control agent according to the fifth invention, wherein the number average molecular weight of the xylene resin is 800 to 1800.
[0024]
The seventh invention is the charge control agent according to the fifth or sixth invention, wherein the mixing ratio of the nigrosine base and the xylene resin is 20:80 to 70:30.
[0025]
The eighth invention is to produce a composition having an aniline content of 100 ppm or less and a nitrobenzene content of 50 ppm or less by dissolving a nigrosine base and a xylene resin in a solvent, mixing and drying. This is a method for producing a toner charge control agent.
[0026]
Hereinafter, the present invention will be described in more detail.
The charge control agent of the present invention can be obtained by mixing a conventionally known nigrosine base and a xylene resin.
Nigrosine base is obtained by oxidizing and reacting aniline and aniline hydrochloride with nitrobenzene at 160 ° C to 180 ° C in the presence of iron chloride, iron and hydrochloric acid as raw materials, and then adding an aqueous alkaline solution It is prepared by separating the dye aniline layer, then base-treating with alkali, washing with water, filtering, drying and grinding. The nigrosine dye is made insoluble in water by being made into a base, and is hardly affected by humidity. The nigrosine base obtained here has an aniline content of about 2000 ppm to 4000 ppm and a nitrobenzene content of about 200 to 500 ppm.
Here, the nigrosine base is preferably pulverized to 30 μm or less. If it is larger than 30 μm, it will be difficult to uniformly disperse in the xylene resin.
[0027]
In the present invention, a commercially available nigrosine base can also be used. Specifically, Bontron N-01 and N-07 manufactured by Orient Chemical Co., Ltd., CHUO CCA-1 manufactured by Chuo Synthetic Chemical Co., etc. can be used.
[0028]
If a large amount of nitrobenzene remains in the nigrosine base, charge due to polarization is stored in the nigrosine base, which tends to aggregate, resulting in a decrease in the dispersibility and distribution of the nigrosine base in the binder resin. . This is because nitrobenzene has a high relative dielectric constant. Therefore, it is important to remove nitrobenzene in the nigrosine base.
Nitrobenzene in the nigrosine base can be removed by dissolving the nigrosine base in alcohol and washing. As a preferable alcohol to be used, it is preferable to use methanol, ethanol or the like in view of the fact that the solvent can be easily removed. Thereby, the nitrobenzene content in the nigrosine base can be reduced to 50 ppm or less. After removing and washing with alcohol, filtration, drying, and in some cases, pulverization and pulverization may be performed.
When removing nitrobenzene in a commercially available nigrosine base, the nigrosine base may be dissolved in alcohol and treated in the same manner as described above.
[0029]
Nitrobenzene can also be removed during the nigrosine-based manufacturing process, which is a preferable process for simplifying the manufacturing process and reducing costs. In the nigrosine base manufacturing process, the base is treated with alkali, washed with water, and then added with alcohol to remove nitrobenzene in the nigrosine base, followed by filtration, drying, and in some cases grinding and crushing. That's fine.
[0030]
The xylene resin that can be used in the present invention is preferably a thermoplastic xylene resin represented by the following chemical formula. The —OH group in the xylene resin becomes an important functional group for reducing the aniline content of the charge control agent of the present invention.
That is, the aniline remaining in the nigrosine base reacts with the —OH group in the xylene resin to form a tertiary amine structure. As a result, the aniline in the nigrosine base reacts with the xylene resin, so that the aniline content in the charge control agent of the present invention is reduced to 100 ppm or less. The presence of a tertiary amine is very useful for improving water resistance and oil resistance.
[0031]
[Chemical 1]

[0032]
From this, it is preferable that the hydroxyl value (OH value) of the xylene resin which can be used by this invention is 100-200 (mgKOH / g), More preferably, it is 110-170 (mgKOH / g). If the hydroxyl value is less than 100 (mgKOH / g), unreacted aniline may remain, and the aniline content in the charge control agent will exceed 100 ppm. On the other hand, if the hydroxyl value is larger than 200 (mgKOH / g), since —OH groups are excessively present, they are easily affected by moisture, and the environmental stability as a charge control agent is lowered. Problems such as in-machine scattering due to a decrease in the charge amount, an increase in fogging, and an excessive increase in the charge amount under low temperature and low humidity may occur.
[0033]
Moreover, it is preferable to use a thing with an average molecular weight of 800-1800, More preferably, it is 1000-1400. By using in this range, the nigrosine base can be dispersed well. When the average molecular weight is 800 or less, it is easy to cause a dispersion failure of the nigrosine base, and when the average molecular weight is higher than 1800, the softening temperature becomes high and it is necessary to mix with the nigrosine base at a high temperature. Or productivity will deteriorate.
Specific preferred xylene resins include thermoplastic xylene resins such as Nicanol HP-100, HP-70, and HP-150 manufactured by Mitsubishi Gas Chemical Company.
[0034]
The composition of the present invention can be obtained by mixing these nigrosine base and xylene resin. As a mixing method, (1) a method in which a nigrosine base is added after being dissolved in a solvent that is soluble in the xylene resin, and the mixture is mixed in the solution. (2) the xylene resin is melted using a kneader or the like. There is a method of adding and mixing nigrosine base in a heated state. Specifically:
(1) Dissolve nigrosine base and xylene resin in a solvent, mix with heating for 1-2 hours near the boiling point of the solvent, remove the solvent, drain into water, filter, wash with water and dry To obtain a composition. Here, the aniline in the nigrosine base reacts with the xylene resin to produce a partially amine-modified xylene resin, so that the composition from which the aniline can be removed hardly contains the remaining aniline. The composition obtained here is in a state where the nigrosine base is dispersed in the xylene resin. Further, if necessary, the composition may be made into a desired particle size through a pulverization step to be a charge control agent.
As the solvent specifically used here, any solvent that dissolves both xylene resin and aniline can be used, but among them, a cellosolve type solvent such as propylene glycol monomethyl ether is preferably used.
(2) The nigrosine base and the xylene resin are put into a kneader such as a heating kneader or a Banbury mixer and mixed thoroughly, and melt kneading is performed at a temperature equal to or higher than the softening temperature of the xylene resin. This disperses the nigrosine base in the xylene resin. At this time, the aniline contained in the nigrosine base reacts with the xylene resin to produce a partially amine-modified xylene resin, so that the composition from which aniline can be removed contains little residual aniline. Become. The composition obtained here is in a state where the nigrosine base is dispersed in the xylene resin. Furthermore, the composition may be used as a charge control agent by roughly crushing and pulverizing the composition to adjust to a desired particle size.
[0035]
When the mixing ratio of the nigrosine base and the xylene resin is in the range of 20:80 to 70:30, a good charge control agent can be obtained. If the ratio of nigrosine base is less than 20, it will be difficult to impart a good positive charge as a charge control agent, and if the ratio of nigrosine base exceeds 70, it will be difficult to remove the remaining aniline, The amount of aniline in the charge control agent may be greater than 100 ppm.
[0036]
The amount of charge control agent used in the toner for developing an electrostatic charge image of the present invention varies depending on the type of binder resin used, but is usually 0.1 to 10 parts by weight, preferably 100 parts by weight of the binder resin. 0.5 to 5 parts by weight, more preferably 0.8 to 3 parts by weight. The particle size of the charge control agent may be 30 μm or less in terms of volume average particle size, and more preferably 2 μm or more and 15 μm or less. If it is less than 2 μm, the toner will be excessively charged, making it difficult to use. If it is larger than 15 μm, it may be difficult to uniformly disperse and mix in the toner.
[0037]
In the electrostatic charge image developing toner of the present invention, as the charge control agent, other charge control agents that can impart positive chargeability to the toner can be used in addition to the nigrosine dye. Such a charge control agent may be any known charge control agent that has been conventionally known to be capable of imparting positive chargeability to the toner. Ammonium salt compounds and triphenylmethane basic dyes are preferred.
[0038]
As a constituent component of the toner for developing an electrostatic image of the present invention, a binder resin and a colorant, which are known materials constituting the toner, are used in addition to the charge control agent of the present invention. In the case of obtaining a magnetic toner, a magnetic powder is further used. However, in the case of using a magnetic powder, the magnetic powder may be used as a colorant. Accordingly, in the present invention, the colorant includes magnetic powder. The toner for developing an electrostatic charge image is further internally or externally added with a release agent, a lubricant, a fluidity improver, an abrasive, a conductivity imparting agent, an image peeling preventing agent, and the like as necessary.
[0039]
Any binder resin can be used as the binder resin used in the toner for developing an electrostatic charge image of the present invention as long as it is known as a binder resin for a toner for developing an electrostatic charge image. Examples of binder resins that can be used include homopolymers of styrene and its derivatives such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, and the like. Styrene-styrene derivative copolymer such as polymer; styrene-vinyl naphthalene copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-α-chloromethyl methacrylate copolymer, Styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene- Acrylonitrile-indene copolymer, etc. Styrene copolymer; polyvinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy Examples thereof include resins, polyvinyl butyral, terpene resins, coumarone indene resins, and petroleum resins.
[0040]
Among these, styrene homopolymers, styrene-styrene derivative copolymers, styrene-acrylic acid copolymers, and styrene-methacrylic acid copolymers are particularly preferable.
[0041]
Examples of the comonomer for the styrene monomer of the styrene-acrylic acid copolymer and styrene-methacrylic acid copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, Examples include 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, and the like.
[0042]
A crosslinked styrene copolymer is also a preferred binder resin. Examples of the comonomer used together with styrene to produce a crosslinked styrene-based copolymer include the styrene derivatives, acrylic acid, methacrylic acid, acrylic acid ester or methacrylic acid ester, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a double bond or a substituted product thereof; for example, a dicarboxylic acid having a double bond such as maleic acid, methyl maleate, butyl maleate, dimethyl maleate and the substituted product thereof; for example, vinyl chloride, vinyl acetate, Vinyl esters such as vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; for example vinyl methyl ether and vinyl ethyl ether , Vinyl ethers such as vinyl isobutyl ether; vinyl monomers are used alone or two or more kinds.
[0043]
As the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1, Carboxylic acid esters having two double bonds such as 3-butanediol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and three or more A compound having a vinyl group is used alone or as a mixture. These crosslinking agents are used in an amount of about 0.01 to 5 parts by weight, more preferably about 0.03 to 3 parts by weight with respect to 100 parts by weight of other monomer components.
[0044]
The binder resin has a molecular weight distribution measured by GPC of 3 × 10 ^Three ~ 5x10 ^Four Having at least one peak in the region of 10 ^Five Styrenic copolymers having at least one peak or shoulder in the above region are preferred from the viewpoint of fixability. The binder resin having such a molecular weight distribution can be produced by mixing two or more kinds of resins having different average molecular weights, and can also be produced by using the crosslinking agent as a crosslinked resin. .
[0045]
The molecular weight distribution by GPC is measured, for example, under the following conditions. Moreover, it can measure similarly about xylene resin.
The column is stabilized in a 40 ° C. heat chamber, and tetrahydrofuran (THF) as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml / min, and about 100 μl of a sample solution dissolved in THF is injected for measurement. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts.
[0046]
Examples of standard polystyrene samples for preparing a calibration curve include a molecular weight of 10 manufactured by Tosoh Corporation or Showa Denko KK. ² -10 ⁷ It is appropriate to use a standard polystyrene sample of about 10 points. An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, combinations of shodex GPC KF-801, 802, 803, 804, 805, 806, 807, 800P manufactured by Showa Denko KK, TSKgel G1000H (HXL), G2000H (HXL), G3000H (HXL) manufactured by Tosoh Corporation, A combination of G4000H (HXL), G5000H (HXL), G6000H (HXL), G7000H (HXL), and TSKguardcolumn can be given.
[0047]
The measurement sample is prepared as follows. That is, after putting a sample in THF and leaving it to stand for several hours, the sample is sufficiently shaken, mixed well with THF until the sample is no longer united, and further allowed to stand for 12 hours or more. At this time, the standing time in THF is set to be 24 hours or longer. Then, GPC measurement was performed on a sample processing filter (pore size 0.45 to 0.5 μm, for example, Mysori Disc H-25-5 manufactured by Tosoh Corp., Excro Disc 25CR manufactured by Gelman Science Japan Ltd., etc.). Sample for use. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.
[0048]
In the production of the vinyl polymer, a polymerization initiator is used. Any conventionally known polymerization initiator can be used as the polymerization initiator. Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, tertiary butyl hydroperoxide, tertiary butyl peroxybenzoate, ditertiary butyl peroxide, cumene hydroperoxide, dicumyl peroxide, azoisobutyro Nitrile, azobisvaleronitrile and the like are usually preferably used. The use ratio of the initiator to the vinyl monomer is generally 0.2 to 5% by weight. The polymerization temperature is appropriately selected according to the type of monomer and initiator used.
[0049]
A polyester resin can also be used as a binder resin for the toner for developing an electrostatic charge image of the present invention. Examples of the alcohol component constituting the polyester resin include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, , 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenyl A, diols such as bisphenol derivatives, and polyhydric alcohols such as glycerin, sorbit and sorbitan.
[0050]
As the acid component, divalent carboxylic acids such as benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride or anhydrides thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; Further, succinic acid substituted with an alkyl group having 16 to 18 carbon atoms or an anhydride thereof; unsaturated dicarboxylic acid such as fumaric acid, maleic acid, citraconic acid, itaconic acid, or an anhydride thereof. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid and anhydrides thereof.
[0051]
A preferred alcohol component is a bisphenol derivative represented by the general formula 1, and a preferred acid component is phthalic acid, terephthalic acid, isophthalic acid or its anhydride, succinic acid, n-dodecenyl succinic acid or its anhydride, fumaric acid, Dicarboxylic acids such as maleic acid and maleic anhydride, and tricarboxylic acids such as trimellitic acid or its anhydride.
[0052]
Further, when using the pressure fixing method, a binder resin for pressure fixing toner can be used, for example, polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer. Examples thereof include polymers, ionomer resins, styrene-butadiene copolymers, styrene-isoprene copolymers, linear saturated polyesters, and paraffins.
[0053]
As the colorant that can be used in the toner for developing an electrostatic charge image of the present invention, any colorant known to be used in the production of conventional toners can be used. Examples of these colorants include fatty acids. Metal salts, various carbon blacks, aniline black, acetylene black, iron black, phthalocyanine series, rhodamine series, quinacridone series, triarylmethane series, anthraquinone series, azo series, diazo series, benzimidazolone series, etc. It is done. These can be used alone or in admixture of two or more. Usually, the addition amount is 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight, based on 100 parts by weight of the binder resin.
[0054]
Among the above, the colorant used in the present invention has a specific surface area of 30 to 300 m by the BET method. ² A more favorable effect can be found by using / g. In particular, by using the toner together with the charge control agent of the present invention, it is possible to obtain a good quality toner free from fogging and in-machine scattering problems.
The specific surface area of the colorant by BET method is 300m ² If the amount exceeds / g, dispersion and distribution in the binder resin will be difficult, fogging will increase, and toner scattering will tend to increase, resulting in a deterioration in the quality of the copied image. May end up. In particular, fogging occurs remarkably in a high-temperature and high-humidity environment, and toner scattering in the machine may occur. The specific surface area is 30m ² When a particle smaller than / g is used, it becomes difficult for the colorant particles to sufficiently color the toner particles, and a desired image density as a toner may not be obtained.
[0055]
The BET specific surface area of the colorant of the present invention was measured by using a multisorb 12 manufactured by Yuasa Ionics Co., Ltd., which is a gas adsorption method (flow method), for a dried colorant sample. A nitrogen-helium mixed gas was used as the carrier gas. And the BET specific surface area was computed from the value of the desorption peak.
[0056]
Further, the magnetic powder used in the toner for developing an electrostatic charge image of the present invention may be any powder such as an alloy or a compound containing a ferromagnetic element conventionally used in the production of a magnetic toner. Examples of these magnetic powders include iron oxides such as magnetite, maghemite and ferrite, or compounds of divalent metals and iron oxides, metals such as iron, cobalt and nickel or aluminum, cobalt, copper and lead of these metals. , Magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium metal alloy powders and mixtures thereof. These magnetic powders preferably have an average particle size of about 0.1 to 2 μm, more preferably about 0.1 to 0.5 μm. Further, the content of the magnetic powder in the toner is about 20 to 200 parts by mass, preferably 40 to 150 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Further, the saturation magnetization of the toner is preferably 15 to 35 emu / g (measuring magnetic field: 1 kilo-Oersted).
[0057]
The toner of the present invention can be mixed with a carrier and used as a two-component developer. The carrier that can be used together with the toner of the present invention may be any conventionally known carrier. Examples of the carrier that can be used include magnetic powders such as iron powder, ferrite powder, and nickel powder, and those whose surfaces are treated with a resin or the like. Examples of the resin covering the carrier surface include styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, acrylic acid ester copolymer, methacrylic acid ester copolymer, fluorine-containing resin, silicone-containing resin, and polyamide. Examples thereof include a resin, an ionomer resin, a polyphenylene sulfide resin, and a mixture thereof. Among these, fluorine-containing resins and silicone-containing resins are particularly preferable because they hardly form spent toner.
[0058]
As for the particle diameter of the toner for developing an electrostatic charge image of the present invention, the weight average particle diameter is 1 to 30 μm, preferably 3 to 15 μm. In particular, toner particles having a particle size of 5 μm or less are contained in 12 to 60% by number, toner particles having a particle size of 8 to 12.7 μm are contained in 1 to 33% by number, and toner particles having a particle size of 16 μm or more. Is more preferably 2.0% by weight or less, and the toner has a weight average particle diameter of 4 to 12 μm from the viewpoint of development characteristics. The toner particle size distribution can be measured using, for example, a Coulter counter.
[0059]
The toner of the present invention may further contain known additives used in the production of toners such as a release agent, a lubricant, a fluidity improver, an abrasive, a conductivity imparting agent, and an image peeling prevention agent, if necessary. Examples of these additives include, for example, waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sazole wax, and paraffin wax. These are usually added to the toner in an amount of about 0.5 to 5% by weight. Also, as the lubricant, polyvinylidene fluoride, zinc stearate, etc., as the fluidity improver, silica, aluminum oxide, titanium oxide, silicon aluminum co-oxide, silicon titanium co-oxide produced by the dry method or wet method And those obtained by hydrophobizing these, and as abrasives, silicon nitride, cerium oxide, silicon carbide, strontium titanate, tungsten carbide, calcium carbonate, and hydrophobized ones of these are used as conductivity imparting agents. Examples include carbon black and tin oxide. In addition, fine powders of fluorine-containing polymers such as polyvinylidene fluoride are preferable from the viewpoints of fluidity, abrasiveness, charge stability, and the like.
[0060]
In the present invention, hydrophobized silica, hydrophobized aluminum oxide, hydrophobized silicon aluminum co-oxide or hydrophobized silicon titanium co-oxide fine powder is used as an external additive. It is preferable to use it. Examples of the hydrophobization treatment of the silica fine powder include treatment with a silane coupling agent such as silicone oil, dichlorodimethylsilane, hexamethyldisilazane, and tetramethyldisilazane. Moreover, it is preferable to use positively-charged silica having a positive tribo-charge relative to the iron powder carrier when measured by the blow-off method. In order to obtain this positively chargeable silica, it may be treated with a silicone oil having an organo group having at least one nitrogen atom in the side chain, or a nitrogen-containing silane coupling agent. The amount of the hydrophobized silica fine powder used is 0.01 to 20%, preferably 0.03 to 5%, based on the developer weight.
[0061]
The toner according to the present invention can be manufactured using a conventionally known toner manufacturing method. In general, the above-described toner constituent materials are sufficiently mixed by a mixer such as a ball mill or a Henschel mixer, and then kneaded thoroughly using a thermal kneader such as a hot roll kneader, a uniaxial or biaxial extruder. After cooling and solidifying, a method of coarsely pulverizing mechanically using a pulverizer such as a hammer mill, then finely pulverizing with a jet mill or the like and then classifying is preferable. However, the method for producing the toner is not limited to this method, and the method for producing the toner by the so-called microcapsule method, the method of dispersing the toner after dispersing other toner constituent materials in the binder resin solution, and the binder, Other methods such as a polymerization toner manufacturing method in which a predetermined material is mixed with a monomer forming a resin, and emulsion or suspension polymerization is performed to obtain a toner can be arbitrarily employed.
[0062]
Furthermore, if necessary, the classified toner and the external additive are sufficiently mixed using a mixer such as a Henschel mixer, and the toner for electrostatic charge development of the present invention can be produced through a sieving step.
[0063]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the embodiment of the present invention is not limited to these examples.
[0064]
[Production example 1 of nigrosine base]
Crude nigrosine was obtained by oxidizing and reacting aniline and aniline hydrochloride with nitrobenzene at 160 to 180 ° C. in the presence of iron chloride, iron and hydrochloric acid. Furthermore, after neutralizing the crude nigrosine, aniline and sodium hydroxide solution were added to make a base treatment, and then the precipitates of nigrosine and iron hydroxide were separated by screw decanter centrifugation and the iron hydroxide precipitate was removed. The obtained liquid was washed with water. After washing with water, in order to remove the remaining nitrobenzene, the mixture was further stirred and washed while heating to 60 ° C., filtered, dried, and pulverized to a mean particle size of 7 μm with a nigrosine base. 1 was obtained. The nitrobenzene content was 50 ppm, and the aniline content was 2500 ppm.
[0065]
[Production example 2 of nigrosine base]
A commercially available nigrosine base CCA-1 (manufactured by Chuo Gosei Chemical Co., Ltd.) was dissolved in methanol and stirred for 30 minutes while heating to 60 ° C. to remove nitrobenzene. Furthermore, it wash | cleaned with methanol, filtered and dried, and it grind | pulverized by the jet mill to the average particle diameter of 6 micrometers, and obtained the nigrosine base 2. The nitrobenzene content was 40 ppm and the aniline content was 2000 ppm.
[0066]
The characteristic values of the nigrosine bases 1 and 2 are summarized in Table 1.
[0067]
[Table 1]

[0068]
[Charge control agent production example 1]
To 3000 g of propylene glycol monomethyl ether, 600 g of a xylene resin (HP-100 manufactured by Mitsubishi Gas Chemical Co., Ltd .: average molecular weight 1200) was added, and sufficiently mixed and dissolved. 400 g of the nigrosine base 1 obtained above was added thereto, and then the mixture was stirred and mixed for 2 hours while maintaining the liquid temperature at 70 to 80 ° C. Further, the temperature was raised above the boiling point of the solvent (120 ° C.) to remove propylene glycol monomethyl ether. Furthermore, after washing | cleaning with water and drying, it grind | pulverized with the sample mill and the composition of 750g was obtained. (Average particle diameter 7.5 μm) This is designated as charge control agent 1.
When the aniline content and the nitrobenzene content contained in the charge control agent 1 were analyzed by gas chromatography, the aniline content was 25 ppm and the nitrobenzene content was 10 ppm.
[0069]
[Charge Control Agent Production Examples 2-6, 10]
Except for the conditions shown in Table 2, charge control agents 2 to 6 were obtained in the same manner as in charge control agent production example 1. Further, the charge control agent 10 is a charge control agent obtained in the same manner as the charge control agent 1 except that rosin maleic anhydride resin (Marquide resin NO.33 manufactured by Arakawa Chemical Co., Ltd.) is used instead of xylene resin. The characteristic values of the obtained charge control agent are shown in Table 2.
[0070]
[Table 2]

[0071]
[Charge Control Agent Production Example 7]
600 g of xylene resin (HP-100 manufactured by Mitsubishi Gas Chemical Company) and 400 g of the nigrosine base obtained above were mixed and kneaded at 140 ° C. for 30 minutes using a pressure kneader. After taking out and cooling, it was pulverized by a sample mill and a jet mill to obtain 700 g of a composition. (Average particle diameter 7.7 μm) This is designated as charge control agent 7. When the aniline content and the nitrobenzene content contained in the charge control agent 7 were analyzed by gas chromatography, the aniline content was 50 ppm and the nitrobenzene content was 20 ppm.
[0072]
The nitrobenzene content and aniline content in nigrosine in Examples and Comparative Examples were both measured using Gas Chromatograph Agilent (formerly Hewlett Packard) Model 6890 and using HP-INNOWAX as a column.
[0073]
Example 1
56 parts by weight of styrene-n-butyl acrylate copolymer
40 parts by weight of magnetic iron oxide
Charge control agent 1 2 parts by weight
2 parts by weight of low molecular weight polypropylene wax
After being premixed with a Henschel mixer, the mixture is put into a biaxial heating kneader, and the kneaded and extruded material is cooled at room temperature and coarsely pulverized with a hammer mill (hereinafter referred to as “chip”). ) Subsequently, this was finely pulverized by a jet mill pulverizer, led to a classifier, and a part having an average particle size of 10 μm was taken out as a fine powder for toner to obtain a magnetic toner (classified toner mother powder).
[0074]
In order to investigate the dispersibility in the nigrosine-based binder resin, a predetermined amount of chips, classified toner base particles and classified fine powder are dissolved in a predetermined amount of chloroform, and the absorbance (wavelength: 567 nm) of the supernatant is measured. The content of nigrosine base in the charge control agent in the classified toner base powder and classified fine powder was determined from the value of the calibration curve. The contents of the nigroshi base were 0.81%, 0.80%, and 0.82%, respectively.
[0075]
In the calibration curve, the amount of nigrosine base added was 0.5 to 2.5 parts by weight, and the amount of the styrene-n-butyl acrylate copolymer as the binder resin was adjusted to 57.5 to 55. A magnetic toner was prepared in the same manner as in the above example except that the total amount was changed to 5 parts by weight, and the total amount was 100 parts by weight, and a predetermined amount of these toners were dissolved in a predetermined amount of chloroform. Similarly, the absorbance (wavelength: 567 nm) of the supernatant was measured, and the absorbance value was plotted in association with the added amount value. When forming the supernatant liquid, the magnetic powder can be sufficiently precipitated by leaving the prepared liquid on the magnet.
[0076]
Examples 2-7 and Comparative Examples 1-2
The same procedure as in Example 1 was carried out except that the charge control agent 1 was changed to each charge control agent described in Table 2, and the content of nigrosine base in the chip, classified toner base particles and classified fine powder was determined. Asked. The results are shown in Table 3.
[0077]
[Table 3]

[0078]
From Table 2, the charge control agent (1-7) of the present invention has the same nigrosine base content as the addition amount at the time of blending in both the chip, the classified toner base powder and the classified fine powder. From this, it can be seen that the distribution property to the binder resin is good. On the other hand, the content of nigrosine base of the comparative product (charge control agent 10, nigrosine base 1) is less than the additive amount at the time of blending in the toner base powder, while it increases in the classified fine powder, both of which are nigrosine base. It can be seen that the distribution of is poor. It is estimated that the deterioration of partitioning is caused by the amount of nitrobenzene and aniline in the nigrosine base. If the dispersibility of the nigrosine base in the charge control agent is poor, a stable quality toner cannot be obtained when the classified fine powder is returned to the raw material and reused, and the classified fine powder cannot be reused.
[0079]
Example 8
88 parts by weight of styrene-n-butyl acrylate copolymer
Carbon black (specific surface area 140m ² / G) 8 parts by weight
Charge control agent 1 2 parts by weight
2 parts by weight of low molecular weight polypropylene wax
Was premixed with a Henschel mixer, then charged into a biaxial heating kneader, and the kneaded and extruded material was cooled at room temperature and coarsely ground with a hammer mill to obtain chips. Subsequently, this was finely pulverized by a jet mill pulverizer, led to a classifier, and a part having an average particle size of 10 μm was taken out as a fine powder for toner to obtain a toner base powder. To 100 parts by weight of this toner base powder, 0.3 parts by weight of hydrophobic silica (Aerosil R972) and tungsten carbide (WC-10 manufactured by Nippon Shin Metal Co., Ltd.) were added and mixed with a Henschel mixer. The change with heating was examined.
[0080]
The test of change with time in heating was conducted by using a developer (toner concentration 5%) composed of toner and toner and carrier (silicone-coated ferrite carrier having an average particle diameter of about 100 μm) in a dryer at 50 ° C. for 3 days (72 hours). After allowing the film to stand to accelerate the heat deterioration, a continuous copying of 10,000 sheets was performed using a commercially available copying machine (Copying Machine FP7113 manufactured by Matsushita Dentsu Co., Ltd.) under an environmental condition of 23 ° C. and 50 RH. . The image densities at the initial and 10,000 copies were 1.41 and 1.40, respectively, and the fog at the initial and 10,000 copies was 0.6 and 0.5, respectively. Furthermore, there was no scattering of the toner particles in the machine after copying 10,000 sheets, and there was no stain on the obtained image.
[0081]
The fog was measured by measuring the reflectance with a photovolt. 1.5% or less is a good value.
Further, the scattering of the toner in the machine was performed by checking whether or not the scattered toner was present on the transfer charger of the copying machine. When toner scattering is observed on the transfer charger, image contamination is caused.
[0082]
Examples 9-14 and Comparative Examples 3-4
An image test was conducted in the same manner as in Example 8 except that the charge control agent 1 was changed to the charge control agent shown in Table 3. The results are shown in Table 4.
[0083]
[Table 4]

[0084]
From Table 3, when developed using the toner after the heat deterioration acceleration test, the toner of the present invention and the comparative toner are not significantly different in the image density, whereas the toner of the present invention is not changed even after the heat deterioration acceleration test. Fogging and toner scattering in the machine were not observed when copying 10,000 sheets, whereas the comparative toner was fogged from the beginning of copying, and toner was scattered in the machine, resulting in image smearing. This is presumably due to the deterioration of the uniform dispersibility of the nigrosine dye due to the presence of a large amount of nitrobenzene and aniline.
[0085]
Example 15
In the same manner as in Example 1, a magnetic toner powder having an average particle size of 10 μm was obtained. To 100 parts by weight of the magnetic toner powder, 0.30 part by weight of hydrophobic silica (Aerosil R972) was added and mixed with a Henschel mixer. The change with time of heating of the toner was performed by examining the copy image density after 10,000 copies, the state of fogging of the image, and the state of scattering of the toner into the machine, as in Example 8. The actual image test was performed using a commercially available copying machine (NP-4145 manufactured by Canon Inc.) under environmental conditions of 23 ° C. and 50 RH. The image densities at the initial and 10,000 copies were 1.42 and 1.41, respectively, and the fog at the initial and 10,000 copies were 0.6 and 0.7, respectively. Furthermore, there was no scattering of toner particles in the machine after copying 10,000 sheets, and the obtained image was not smudged. The image density is determined using a Macbeth photometer and may be a density of 1.3 or more.
[0086]
Examples 16-21 and Comparative Examples 5-6
An image test was conducted in the same manner as in Example 15 except that the charge control agent 1 was changed to the charge control agent shown in Table 3. The results are shown in Table 5.
[0087]
[Table 5]

[0088]
From Table 5, when developed using the toner after the heat deterioration acceleration test, the toner density of the present invention was the same as the initial image after 10,000 copies, and no fogging was observed. On the other hand, in the comparative toner, although the initial image density and the density within the allowable range, a decrease in the image density, which is presumed to be caused by the non-uniform dispersion of the nigrosine dye, occurred, and fogging has occurred since the beginning of copying It occurred and became more intense after 10,000 sheets. In addition, although there was no toner scattering in the apparatus of the present invention, the comparative toner showed some scattering.
[0089]
【The invention's effect】
As described above, by using a composition obtained by mixing a nigrosine base and a xylene resin as a charge control agent for an electrostatic charge image developing toner, an electrostatic charge image developing toner in which the nigrosine base is uniformly dispersed can be obtained. Obtainable. Since this charge control agent contains almost no aniline or nitrobenzene, a toner using this charge control agent can have a good image density from the beginning and can produce a copy image free from fogging, and can be used for multiple copies. In this case, the image density is not lowered, and the toner for developing an electrostatic charge image of the present invention does not change with heating, and is characterized by heat stress until it is commercially available, after storage, after storage, or during transportation. A good toner with no change can be obtained. In addition, since the charge control agent of the present invention has good distribution, it is easy to reuse the classified fine powder, which contributes greatly to resource saving and cost reduction at the time of toner production.

Claims (8)

An electrostatic charge image developing toner containing at least a binder resin, a colorant, and a charge control agent, comprising a composition obtained by mixing a nigrosine base and a xylene resin as a charge control agent. Development toner. 2. The electrostatic image developing toner according to claim 1, wherein the charge control agent has an aniline content of 100 ppm or less and a nitrobenzene content of 50 ppm or less. The toner according to claim 1, wherein the xylene resin has a number average molecular weight of 800 to 1800. The toner according to claim 1, wherein the mixing ratio of the nigrosine base and the xylene resin is 20:80 to 70:30. A charge control agent used for a toner for developing an electrostatic charge image, comprising a mixture of a nigrosine base and a xylene resin, an aniline content of 100 ppm or less, and a nitrobenzene content of 50 ppm or less. 6. The charge control agent according to claim 5, wherein the xylene resin has a number average molecular weight of 800 to 1800. The charge control agent according to claim 5 or 6, wherein the mixing ratio of the nigrosine base and the xylene resin is 20:80 to 70:30. A charge control agent for toner, wherein a composition having an aniline content of 100 ppm or less and a nitrobenzene content of 50 ppm or less is obtained by dissolving a nigrosine base and a xylene resin in a solvent, mixing and drying. Production method.