JP2004279772A - Electrostatic charge image developing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing toner which improves dot reproducibility, printing properties, and storage stability. <P>SOLUTION: The electrostatic charge image developing toner comprises toner particles comprised of at least a binder resin, a colorant, a charge control agent, and a release agent. The volume mode diameter (a) of the toner particles is 5-10 μm, a volume average particle diameter (Dv) to number average particle diameter (Dp) ratio (Dv/Dp) is 1.0-1.3, an average circularity is 0.97-0.995, and a standard deviation (b) of particle diameter of the toner particles is ≤2 μm. The ratio (C1/C2) between an average circularity (C1) of toner particles having a particle diameter of (a-2b) to less than a μm and an average circularity (C2) of toner particles having a particle diameter of a to less than (a+2b) μm is 1.00-1.02, the content of a component extracted by n-hexane is 1-15 wt.%, and the content of a component extracted by methanol is ≤5 wt.%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２６】
上記式において、ｎは円形度Ｃｉを求めた粒子の個数である。
上記式においてＣｉは０．６〜４００μｍの円相当径の粒子群の各粒子について測定された円周長を元に次式により算出された各粒子の円形度である。
円形度（Ｃｉ）＝粒子の投影面積に等しい円の周囲長／粒子投影像の周囲長
上記式において、ｆｉは円形度Ｃｉの粒子の頻度である。
上記円形度及び平均円形度は、シスメックス社製フロー式粒子像分析装置「ＦＰＩＡ−１０００」又は「ＦＰＩＡ−２０００」を用いて測定することができる。
【００２７】
本発明の静電荷像現像用トナーを構成するトナー粒子の粒径の標準偏差（ｂ）は２μｍ以下であり、好ましくは１．５μｍ以下である。トナー粒子の粒径の標準偏差が２μｍを超えるとカブリが発生する。
トナー粒子の標準偏差は、円形度及び平均円形度と同様、シスメックス社製フロー式粒子像分析装置「ＦＰＩＡ−１０００」又は「ＦＰＩＡ−２０００」を用いて測定することができる体積基準の値である。
【００２８】
本発明の静電荷像現像用トナーを構成するトナー粒子は、体積モード径をａとし、トナー粒子の粒径の標準偏差をｂとした場合、（ａ−２ｂ）μｍ以上ａμｍ未満の粒径を有するトナー粒子の平均円形度をＣ１とし、ａμｍ以上（ａ＋２ｂ）μｍ未満の粒径を有するトナー粒子の平均円形度をＣ２とした場合、（Ｃ１／Ｃ２）が１．００〜１．０２であり、好ましくは１．００〜１．０１である。この数値はトナー粒子の合一状態を表現する意義がある。（Ｃ１／Ｃ２）が大きいと、トナー粒子が２個結合した、いわゆる合一粒子が多くなっていることを示している。（Ｃ１／Ｃ２）が上記範囲にあると、カブリが発生し難く、また良好な画質が得られる。
なお、上記Ｃ１及びＣ２についても、円形度及び平均円形度と同様、シスメックス社製フロー式粒子像分析装置「ＦＰＩＡ−１０００」又は「ＦＰＩＡ−２０００」を用いて測定することができる。
【００２９】
本発明の静電荷像現像用トナーは、そのｎ−ヘキサン抽出成分含有量が１〜１５重量％であり、３〜１３重量％であることが好ましい。ｎ−ヘキサン抽出成分含有量が１重量％未満であると定着温度が上昇し、ホットオフセットを生じやすくなる。一方、１５重量％を超えると保存性が低下する。なお、ｎ−ヘキサン抽出成分含有量は後述の方法によって測定することができる
【００３０】
本発明の静電荷像現像用トナーは、そのメタノール抽出成分含有量が５重量％以下であり、４重量％以下であることが好ましい。メタノール抽出成分含有量が５重量％を超えると、吸湿性となり、環境安定性（細線再現性）が低下し、カブリが発生する。なお、メタノール抽出成分含有量は後述の方法によって測定することができる。
【００３１】
本発明の静電荷像現像用トナーは、そのままで電子写真の現像に用いることもできるが、通常は、静電荷像現像用トナーの帯電性、流動性、保存安定性等を調整するために、トナー粒子表面に、該トナー粒子よりも小さい粒径の微粒子（以下、外添剤という。）を付着又は埋設させてから用いることが好ましい。
外添剤としては、通常、流動性や帯電性を向上させる目的で使用されている無機粒子や有機樹脂粒子が挙げられる。外添剤として添加するこれらの粒子は、トナー粒子よりも平均粒径が小さい。例えば、無機粒子としては、シリカ、酸化アルミニウム、酸化チタン、酸化亜鉛、酸化錫などが挙げられ、有機樹脂粒子としては、メタクリル酸エステル重合体粒子、アクリル酸エステル重合体粒子、スチレン−メタクリル酸エステル共重合体粒子、スチレン−アクリル酸エステル共重合体粒子、コアがスチレン重合体で、シェルがメタクリル酸エステル重合体で形成されたコアシェル型粒子などが挙げられる。これらのうち、シリカ粒子や酸化チタン粒子が好適であり、この表面を疎水化処理した粒子が好ましく、疎水化処理されたシリカ粒子が特に好ましい。外添剤の量は、特に限定されないが、トナー粒子１００重量部に対して、通常、０．１〜６重量部である。
【００３２】
本発明の静電荷像現像用トナーは、前述した範囲の特性を有するものを与えることができる方法であれば、その製造方法に特に制限はないが、重合法によって製造することが好ましい。
次に、重合法により静電荷像現像用トナーを構成するトナー粒子を製造する方法について説明する。
本発明の静電荷像現像用トナーを構成するトナー粒子は、例えば、水溶性多価無機塩に水酸化アルカリ金属を添加して生成させた難水溶性無機化合物のコロイドを分散安定化剤として含有する水性分散媒を調製し、１５〜３５℃の温度で４〜１８時間放置して熟成させる工程；重合性単量体、着色剤、帯電制御剤及び重合開始剤を含有する重合性単量体組成物を、上記熟成された水性分散媒に添加して液滴を形成させ、水性分散媒中にホウ素化合物の水溶液を添加した後、該水性分散媒の温度を上昇させて重合してトナー粒子を得ることができる。
【００３３】
本発明では、重合性単量体組成物を得るときに、予め着色剤と帯電制御樹脂を混合して製造した帯電制御樹脂組成物を得、それを離型剤等とともに重合性単量体に添加して混合してもよい。その際、着色剤の量は、帯電制御樹脂１００重量部に対して、通常１０〜２００重量部、好ましくは２０〜１５０重量部である。帯電制御樹脂組成物の製造には、有機溶剤を用いることが好ましい。有機溶剤を用いることで、帯電制御樹脂が柔らかくなり、顔料と混合し易くなる。
【００３４】
有機溶剤の量は、帯電制御樹脂１００重量部に対して、通常、０〜１００重量部、好ましくは５〜８０重量部、さらに好ましくは１０〜６０重量部であり、この範囲にあると分散性と加工性のバランスが優れる。また、このとき、有機溶剤は、一度に全量を添加しても、あるいは混合状態を確認しながら、何回かに分割して添加しても良い。
混合は、ロール、ニーダー、一軸押出機、二軸押出機、バンバリー、ブス・コニーダー等を用いて行うことができる。有機溶剤を用いる場合は、有機溶剤が外部に漏れない密閉系の混合機が好ましい。
また、混合機にはトルクメーターが設置されていることが、トルクのレベルで分散性を管理することができるので好ましい。
【００３５】
重合性単量体としては、例えば、モノビニル単量体、架橋性単量体、マクロモノマー等を挙げることができる。この重合性単量体が重合され、結着樹脂成分となる。
モノビニル単量体としては、スチレン、ビニルトルエン、α−メチルスチレン等の芳香族ビニル単量体；（メタ）アクリル酸；（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、（メタ）アクリル酸ブチル、（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸イソボニル等の（メタ）アクリル系共重合体；エチレン、プロピレン、ブチレン等のモノオレフィン単量体；等が挙げられる。
モノビニル単量体は、単独で用いても、複数の単量体を組み合わせて用いても良い。これらモノビニル単量体のうち、芳香族ビニル単量体単独、芳香族ビニル単量体と（メタ）アクリル系単量体との併用などが好適に用いられる。
【００３６】
モノビニル単量体と共に、架橋性単量体を用いるとホットオフセットが有効に改善される。架橋性単量体は、２個以上のビニル基を有する単量体である。具体的には、ジビニルベンゼン、ジビニルナフタレン、エチレングリコールジメタクリレート、ペンタエリスリトールトリアリルエーテルやトリメチロールプロパントリアクリレート等を挙げることができる。これらの架橋性単量体は、それぞれ単独で、あるいは２種以上組み合わせて用いることができる。架橋性単量体の量は、モノビニル単量体１００重量部当たり、通常１０重量部以下、好ましくは、０．１〜２重量部である。
【００３７】
また、モノビニル単量体と共に、マクロモノマーを用いると、保存性と低温での定着性とのバランスが良好になるので好ましい。マクロモノマーは、分子鎖の末端に重合可能な炭素−炭素不飽和二重結合を有するもので、数平均分子量が、通常、１，０００〜３０，０００のオリゴマーまたはポリマーである。
マクロモノマーは、前記モノビニル単量体を重合して得られる重合体のガラス転移温度よりも、高いガラス転移温度を有する重合体を与えるものが好ましい。
マクロモノマーの量は、モノビニル単量体１００重量部に対して、通常、０．０１〜１０重量部、好ましくは０．０３〜５重量部、さらに好ましくは０．０５〜１重量部である。
【００３８】
重合開始剤としては、例えば過硫酸カリウム、過硫酸アンモニウム等の過硫酸塩；４，４’−アゾビス（４−シアノバレリック酸）、２，２’−アゾビス（２−メチル−Ｎ−（２−ヒドロキシエチル）プロピオンアミド、２，２’−アゾビス（２−アミジノプロパン）ジヒドロクロライド、２，２’−アゾビス（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル等のアゾ化合物；ジ−ｔ−ブチルパーオキシド、ベンゾイルパーオキシド、ｔ−ブチルパーオキシ−２−エチルヘキサノエート、ｔ−ヘキシルパーオキシ−２−エチルヘキサノエート、ｔ−ブチルパーオキシピバレート、ジ−イソプロピルパーオキシジカーボネート、ジ−ｔ−ブチルパーオキシイソフタレート、ｔ−ブチルパーオキシイソブチレート等の過酸化物類等が挙げられる。また、上記重合開始剤と還元剤とを組み合わせたレドックス開始剤を用いてもよい。
【００３９】
重合性単量体の重合に用いられる重合開始剤の量は、重合性単量体１００重量部に対して、好ましくは０．１〜２０重量部であり、更に好ましくは０．３〜１５重量部であり、最も好ましくは０．５〜１０重量部である。重合開始剤は、液滴形成後の水性分散媒中に添加してもよいが、重合性単量体組成物中にあらかじめ添加しておく方が好ましい。
【００４０】
分散安定化剤として用いられる難水溶性無機化合物のコロイドは、水溶性多価無機塩と水酸化アルカリ金属とを水性分散媒中で混合して生成したものである。このような難水溶性無機化合物としては、例えば水酸化マグネシウム等が挙げられる。難水溶性無機化合物コロイドを含有する水性分散媒を熟成させてからトナー製造に用いると、容易に本発明の静電荷像現像用トナーを得ることができるので好ましい。本発明で熟成とは、難水溶性無機化合物のコロイドを含有する水性分散媒を調製した後、直ちに用いず、一定時間放置することである。具体的には、１５〜３５℃の温度、好ましくは２０〜３５℃の温度で４〜１８時間、好ましくは５〜２０時間放置することである。
【００４１】
上記分散安定化剤の量は、重合性単量体１００重量部に対して、好ましくは０．１〜２０重量部である。分散安定化剤の量が０．１重量部未満であると十分な重合安定性を得ることが困難になり、重合凝集物が生成しやすくなる場合があり、一方、２０重量部を超えて使用すると、重合安定性の効果が飽和し、経済的でないことに加え、水性分散媒の粘度が高くなりすぎ、混合後の小さな液滴を形成することが困難となる場合がある。
重合に際しては、水溶性高分子を重合トナーの帯電特性の環境依存性や定着性の変化が大きくならない範囲で併用することができる。水溶性高分子としては、例えばポリビニルアルコール、メチルセルロース、ゼラチン等が挙げられる。
【００４２】
また、重合に際しては、重合性単量体の液滴を形成した後、この液滴を含む水性分散媒中にホウ素化合物の水溶液を添加することが好ましい。ホウ素化合物としては、三フッ化ホウ素、三塩化ホウ素、テトラフルオロホウ酸、テトラヒドロホウ酸ナトリウム、テトラヒドロホウ酸カリウム、四ホウ酸ナトリウム、四ホウ酸ナトリウム十水和物、メタホウ酸ナトリウム、メタホウ酸ナトリウム四水和物、ペルオキソホウ酸ナトリウム四水和物、ホウ酸、メタホウ酸カリウム、四ホウ酸カリウム八水和物等が挙げられる。ホウ素化合物は水溶液の状態で添加することが好ましい。上記ホウ素化合物の量は、難水溶性化合物のコロイド１００重量部に対して、好ましくは０．１〜１０００重量部であり、更に好ましくは１〜１００重量部である。
【００４３】
更に、重合に際しては、分子量調整剤を使用することが好ましい。該分子量調整剤としては、例えばｔ−ドデシルメルカプタン、ｎ−ドデシルメルカプタン、ｎ−オクチルメルカプタン、２，２，４，６，６−ペンタメチルヘプタン−４−チオール等のメルカプタン類等が挙げられる。上記分子量調整剤は、重合開始前または重合途中に添加することができる。上記分子量調整剤の量は、重合性単量体１００重量部に対して、好ましくは０．０１〜１０重量部であり、更に好ましくは０．１〜５重量部である。
【００４４】
コアシェル型トナー粒子を製造する方法としては特に制限はなく、従来公知の方法によって製造することができる。例えば、スプレイドライ法、界面反応法、ｉｎ ｓｉｔｕ重合法、相分離法などの方法が挙げられる。具体的には、粉砕法、重合法、会合法又は転相乳化法により得られたトナー粒子をコア粒子として、それに、シェル層を被覆することによりコアシェル型トナー粒子が得られる。この製造方法の中でも、ｉｎ ｓｉｔｕ重合法や相分離法が、製造効率の点から好ましい。
【００４５】
ｉｎ ｓｉｔｕ重合法によるコアシェル型トナー粒子の製造方法を以下に説明する。
コア粒子が分散している水系分散媒体中に、シェルを形成するための重合性単量体（シェル用重合性単量体）と重合開始剤とを添加し、重合することでコアシェル型トナー粒子を得ることができる。
シェルを形成する具体的な方法としては、コア粒子を得るために行った重合反応の反応系にシェル用重合性単量体を添加して継続的に重合する方法、または別の反応系で得たコア粒子を仕込み、これにシェル用重合性単量体を添加して重合する方法などを挙げることができる。
シェル用重合性単量体は反応系中に一括して添加しても、またはプランジャポンプなどのポンプを使用して連続的もしくは断続的に添加してもよい。
【００４６】
シェル用重合性単量体としては、スチレン、アクリロニトリル、メチルメタクリレートなどのガラス転移温度が８０℃を超える重合体を形成する単量体をそれぞれ単独で、あるいは２種以上組み合わせて使用することができる。
【００４７】
シェル用重合性単量体を添加する際に、水溶性の重合開始剤を添加することがコアシェル型トナー粒子を得やすくなるので好ましい。シェル用重合性単量体の添加の際に水溶性重合開始剤を添加すると、コア粒子の外表面近傍に水溶性重合開始剤が移動し、コア粒子表面で、シェル用重合性単量体が重合しやすくなると考えられる。
【００４８】
水溶性重合開始剤としては、過硫酸カリウム、過硫酸アンモニウム等の過硫酸塩；２，２’−アゾビス（２−メチル−Ｎ−（２−ヒドロキシエチル）プロピオンアミド）、２，２’−アゾビス−（２−メチル−Ｎ−（１，１−ビス（ヒドロキシメチル）２−ヒドロキシエチル）プロピオンアミド）等のアゾ系開始剤などを挙げることができる。水溶性重合開始剤の量は、シェル用重合性単量体１００重量部に対して、通常、０．１〜５０重量部、好ましくは１〜３０重量部である。
【００４９】
重合の際の温度は、好ましくは５０℃以上であり、更に好ましくは８０〜９５℃である。また、反応時間は好ましくは１〜２０時間であり、更に好ましくは２〜１０時間である。重合終了後に、常法に従い、濾過、洗浄、脱水および乾燥の操作を、必要に応じて数回繰り返すことが好ましい。
【００５０】
分散安定化剤として無機化合物コロイドを用いた場合、重合によって得られるトナー粒子の水分散液のｐＨが６．５以下になるように酸を添加して難水溶性無機化合物コロイドを溶解することが好ましい。添加する酸としては、硫酸、塩酸、硝酸などの無機酸、蟻酸、酢酸などの有機酸を用いることができるが、除去効率の大きいことや製造設備への負担が小さいことから、特に硫酸が好適である。
水分散液中からトナー粒子を濾過脱水する方法は特に制限されない。例えば、遠心濾過法、真空濾過法、加圧濾過法などを挙げることができる。これらのうち遠心濾過法が好適である。濾過後、トナー粒子は必要に応じて真空乾燥機等を用いて乾燥する。
【００５１】
本発明の静電荷像現像用トナーは、トナー粒子及び外添剤、また必要に応じてその他の微粒子をヘンシェルミキサー等の高速撹拌機を用いて混合することにより得られる。
【００５２】
【実施例】
以下、本発明を実施例により更に詳細に説明する。なお、本発明の範囲は、かかる実施例に限定されないことはいうまでもない。なお、以下の実施例において、部および％は、特に断りのない限り重量部又は重量％を表す。
【００５３】
本実施例では、以下の方法でトナーの評価を行った。
（１）粒径、平均円形度
トナー粒子の粒径分布、すなわち体積平均粒径と個数平均粒径（Ｄｐ）との比（Ｄｖ／Ｄｐ）は粒径測定機（ベックマン・コールター社製、機種名「マルチサイザー」）により測定した。このマルチサイザーによる測定は、アパーチャー径：１００μｍ、媒体：イソトンＩＩ、濃度１０％、測定粒子個数：５０，０００個の条件で行った。
【００５４】
（２）体積モード径、平均円形度、標準偏差
２０ｍｇのトナー粒子に分散媒として０．１％アニオン系界面活性剤水溶液を１００μｌ加えてなじませた後、水１０ｍｌを加えて撹拌し、体積モード径、平均円形度、標準偏差の測定を行った。測定はシスメックス社製フロー式粒子像分析装置「ＦＰＩＡ−２０００」を用いて行った。解析は体積基準（１５μｍ以下の区分について）にて行った。
更に、（ａ−２ｂ）μｍ以上ａμｍ未満の粒径を有するトナー粒子の平均円形度（Ｃ１）、及びａμｍ以上（ａ＋２ｂ）μｍ未満の粒径を有するトナー粒子の平均円形度（Ｃ２）についても、上記装置により求めた。
【００５５】
（３）ｎ−ヘキサン抽出成分含有量
静電荷像現像用トナー１．０ｇとｎ−ヘキサン１００ｍｌとを、円筒ろ紙（東洋ろ紙製：Ｎｏ．８６Ｒ）の入ったソックスレー抽出器に入れ、常圧下で６時間還流して抽出液を得た。抽出液から溶媒を蒸発させ、固形分を５０℃の温度で１時間真空乾燥して秤量した。この秤量値を、最初に秤量した静電荷像現像用トナーの秤量値で除して１００倍し、ｎ−ヘキサン抽出成分含有量（％）とした。
【００５６】
（４）メタノール抽出成分含有量
静電荷像現像用トナー１．０ｇとメタノール１００ｍｌとを、円筒ろ紙（東洋ろ紙製：Ｎｏ．８６Ｒ）の入ったソックスレー抽出器に入れ、常圧下で６時間還流して抽出液を得た。抽出液から溶媒を蒸発させ、固形分を５０℃の温度で１時間真空乾燥して秤量した。この秤量値を、最初に秤量した静電荷像現像用トナーの秤量値で除して１００倍し、メタノール抽出成分含有量（％）とした。
【００５７】
（５）流動性
目開きが、それぞれ１５０μｍ、７５μｍ及び４５μｍの３種の篩を、この順に上から重ね、一番上に配置された篩の上に、試料（静電荷像現像用トナー）４ｇを精秤して載せた。次いで、重ねた３種の篩を、粉体測定機（ホソカワミクロン社製：商品名「Ｐｏｗｅｒ Ｔｅｓｔｅｒ」）を用いて、振動強度４の条件で１５秒間振動させてから、各篩の上に残留した静電荷像現像用トナーの質量を測定する。各測定値を以下の算出式に挿入し、流動性の値とする。１試料について３度測定を行い、その平均値を求めた。
算出式：
ａ＝（目開き１５０μｍの篩の上に残留した静電荷像現像用トナーの質量（ｇ））／４（ｇ）×１００
ｂ＝（目開き７５μｍの篩の上に残留した静電荷像現像用トナーの質量（ｇ））／４（ｇ）×１００×０．６
ｃ＝（目開き４５μｍの篩の上に残留した静電荷像現像用トナーの質量（ｇ））／４（ｇ）×１００×０．２
流動性（％）＝１００−（ａ＋ｂ＋ｃ）
【００５８】
（６）保存性
静電荷像現像用トナーを密閉可能な容器に入れて、密閉した後、温度を５５℃にした恒温水槽の中に沈め、８時間経過した後に取り出して、４２メッシュの篩いの上にできるだけ構造を破壊しないように、容器内から静電荷像現像用トナーを取り出し、かつ注意深く篩上に移す。この篩を（６）で用いた粉体測定機で振動の強度を４．５に設定して、３０秒間振動した後、篩い上に残った静電荷像現像用トナーの重量を測定し、これを凝集したトナーの重量とした。最初に容器に入れた静電荷像現像用トナーの重量に対する凝集トナーの重量の割合（重量％）を算出した。１サンプルにつき３回測定し、その平均値を保存性の指標とした。
なお、トナーの保存性（重量％）は、数値が小さい方が優れたものである。
【００５９】
（７）カブリ
市販の非磁性一成分現像方式のプリンター（１８枚機）に再生紙をセットして、このプリンター装置に静電荷像現像用トナーを入れ、温度１０℃、湿度２０％の（Ｌ／Ｌ）環境、温度２３℃、湿度５０％の（Ｎ／Ｎ）環境、温度３５℃、湿度８０％の（Ｈ／Ｈ）環境下でそれぞれ、一昼夜放置した後、プリンターの印字濃度を５％に設定して印字を行い、５００枚毎に印字を一時停止させ、現像後の感光体上の非現像部のトナーを粘着テープ（住友スリーエム社製、スコッチメンディングテープ８１０−３−１８）に付着させた。それを印字用紙に貼り付け、その白色度（Ｂ）を白色度計（日本電色社製）で測定した。同時に、粘着テープだけを貼り付けた印字用紙の白色度（Ａ）を測定し、それぞれの白色度の差（Ａ−Ｂ）（％）を求めた。この価と、印字初期（１０枚印字時）の白色度の差（Ａ−Ｂ）（％）との差が１％以下である最大枚数（５００枚単位でカウント）を調べた。なお、試験は１０，０００枚で終了した。
【００６０】
（８）細線再現性
（７）で使用したプリンターを用いて、温度１０℃及び湿度２０％の（Ｌ／Ｌ）環境下、温度２３℃及び湿度５０％の（Ｎ／Ｎ）環境下、温度３５℃及び湿度８０％の（Ｈ／Ｈ）環境下で一昼夜放置した後、２×２ドットライン（幅約８５μｍ）で連続して線画像を形成し、５００枚毎に、印字評価システム「ＲＴ２０００」（ＹＡ−ＭＡ社製）によって測定し、線画像の濃度分布データを採取した。
この時、その濃度の最大値の半値における全幅を線幅として、一枚目の線画像の線幅を基準として、その線幅の差が１０μｍ以下のものは１枚目の線画像を再現しているとして、線画像の線幅の差が１０μｍ以下を維持できる枚数を調べた。
【００６１】
（９）印字濃度
（７）で使用したプリンターに印字用紙をセットし、現像装置にトナーを入れ、温度３５℃及び湿度８０％の（Ｈ／Ｈ）環境下で一昼夜放置後、プリンターの印字濃度を５％に設定して初期から連続印字を行い、１００枚目印字（初期印字）、及び１０，０００枚目印字（連続印字）に黒ベタ印字を行い、ＭｃＢｅｔｈ社製透過式画像濃度測定機を用いて、印字濃度を測定した。なお、この試験は１０，０００枚で終了した。
【００６２】
（１０）トナーの定着温度
市販の非磁性一成分現像方式のプリンター（マイクロライン１８ＮＲ 沖データ社製（１８枚機）の定着ロール部の温度を変化できるように改造したプリンターを用いて、定着試験を行った。定着試験は、改造プリンターの定着ロールの温度を５℃ずつ変化させて、それぞれの温度での現像剤の定着率を測定し、温度−定着率の関係を求めることにより行った。定着率は、改造プリンターで印刷した試験用紙における黒ベタ領域の、テープ剥離操作前後の画像濃度の比率から計算した。すなわち、テープ剥離前の画像濃度をＩＤ前、テープ剥離後の画像濃度をＩＤ後とすると、定着率は、下記式から算出することができる。
定着率（％）＝（ＩＤ後／ＩＤ前）×１００
なお、テープ剥離操作とは、試験用紙の測定部分に粘着テープ（住友スリーエム社製 スコッチメンディングテープ８１０−３−１８）を貼り、５００ｇのスチールローラで押圧して付着させ、次いで、一定速度で紙に沿った方向に粘着テープを剥離する一連の操作のことを意味する。また、画像濃度は、マクベス社製反射式画像濃度測定機を用いて測定した。定着試験において、定着率が８０％になる定着ロールの温度を現像剤の定着温度とした。
【００６３】
（１１）ホットオフセット
上記（１０）の定着温度の測定と同様にして、定着ロールの温度を５℃ずつ変化させて印字し、定着ロール上にトナーが残留して汚れが発生する温度をホットオフセット発生温度とした。
【００６４】
実施例１
フラスコに、トルエン９００部、スチレン７８部、２−エチルヘキシルアクリレート１９部、２−アクリルアミド−２−メチルプロパンスルホン酸３部、及びアゾビスジメチルバレロニトリル２部を仕込み、撹拌しながら９０℃で８時間反応させた。反応終了後、トルエンを減圧留去して、帯電制御樹脂Ａ（テトラヒドロフランを用いたゲル・パーミエーション・クロマトグラフィーによって測定される重量平均分子量Ｍｗ＝２１，０００）を得た。
上述した帯電制御樹脂Ａ５部と、スチレン９０部、ｎ−ブチルアクリレート９．３部及びジビニルベンゼン０．７部からなるコア用単量体と、シアン着色剤である、Ｃ．Ｉ．ピグメントブルー１５：３（クラリアント社製）５部と、ポリメタクリル酸エステルマクロモノマー（東亜合成化学工業社製、商品名「ＡＡ６」、Ｔｇ＝９４℃）０．８部、ジペンタエリスリトールヘキサミリステート（融点：６５℃、水酸基価：０．１６ｍｇＫＯＨ／ｇ）１０部とを、通常の撹拌機で均一になるまで撹拌し、均一混合液を得た。この均一混合液に重合開始剤ｔ−ブチルパーオキシ２−エチルヘキサノエート（商品名「パーブチルＯ」、日本油脂社製）５部を添加し重合性単量体組成物を得た。
一方、メタクリル酸メチル４部及び水１００部を混合し、超音波乳化機にて微分散化処理してシェル用重合性単量体の水分散液を得た。
【００６５】
他方、イオン交換水２５０部に塩化マグネシウム９．５部を溶解した水溶液に、イオン交換水５０部に水酸化ナトリウム５．９部を溶解した水溶液を撹拌下で徐々に添加して、水酸化マグネシウムコロイド分散液を製造し、６時間放置して熟成させた。この熟成した分散液に、上述の重合性単量体組成物を投入し、連続乳化分散機であるエバラマイルダーＭＤＮ３０４型（荏原製作所社製）を用いて、１５，０００ｒｐｍの回転数で１０分間攪拌して、重合性単量体組成物の液滴を形成させた。この液滴を含む水酸化マグネシウムコロイド分散液に、四ホウ酸ナトリウム十水和物を１部添加し、攪拌翼を装着した反応器に入れ、８５℃の温度で重合反応を開始させ、重合転化率がほぼ１００％に達した時に、上述のシェル用重合性単量体の水分散液、及び２，２’−アゾビス（２−メチル−Ｎ（２−ヒドロキシエチル）−プロピオンアミド（和光純薬社製、商品名「ＶＡ−０８６」）０．３部を反応器に入れた。重合反応を４時間継続した後、反応を停止し、コアシェル型トナー粒子の水分散液を得た。
【００６６】
上述のようにして得られたコアシェル型重合体トナー粒子の水分散液を攪拌しながら、硫酸により系のｐＨを４以下に調整して酸洗浄（２５℃、１０分間）を行い、濾過により水を分離した後、新たにイオン交換水５００部を加えて再スラリー化し３８℃の水で洗浄を行った。次いで、再度、脱水及び水洗浄を数回繰り返し行い、固形分を濾過分離した後、乾燥機にて４５℃で２昼夜乾燥を行い、トナー粒子を得た。
上述のようにして得られたトナー粒子１００部に、疎水化処理されたコロイダルシリカ（日本アエロジル社製：ＲＸ−２００）０．６部を添加し、ヘンシェルミキサーを用いて混合し、負帯電性静電荷像現像用トナーを調製した。得られた静電荷像現像用トナーについて、上述した評価を行った。評価結果を表１に示す。
【００６７】
実施例２
トルエン９００部、スチレン７８部、２−エチルヘキシルアクリレート７部、２−アクリルアミド−２−メチルプロパンスルホン酸９部、エタノール２部に、水酸化カリウム０．１３４部とアゾビスジメチルバレロニトリル２部を仕込み、９０℃で８時間反応させた後、溶剤を減圧留去して帯電制御樹脂Ｂ（Ｍｗ＝２１，０００）を得た。得られた帯電制御樹脂Ｂの酸価は６．７ｍｇＫＯＨ／ｇであった。
上述のようにして得られた帯電制御樹脂Ｂを用いた以外は、実施例１と同様に操作を行い、静電荷像現像用トナーを得た。得られた静電荷像現像用トナーについて、実施例１と同様に評価を行った。評価結果を表１に示す。
【００６８】
比較例１
スチレン８０．５部及びｎ−ブチルアクリレート１９．５部からなるコア用重合性単量体（これらの単量体を共重合して得られた共重合体のＴｇ＝５５℃）、ポリメタクリル酸エステルマクロモノマー（東亜合成化学工業社製、商品名「ＡＡ６」、Ｔｇ＝９４℃）０．３部、ジビニルベンゼン０．５部、ｔ−ドデシルメルカプタン１．２部、Ｃ．Ｉ．ピグメントブルー１５：３（クラリアント社製）７部、帯電制御樹脂Ａ５部、離型剤（フィッシャートロプシュワックス、日本精蝋社製、商品名「ＳＰ−３０４０」、吸熱ピーク温度：１００℃、融点：６３℃、水酸基価：０．１ｍｇＫＯＨ／ｇ以下）２部を、メディア型湿式粉砕機の撹拌槽内に投入して離型剤を湿式粉砕し、次いで重合開始剤としてｔ−ブチルパーオキシ−２−エチルヘキサノエート（日本油脂社製、商品名「パーブチルＯ」）５部を添加して、コア用重合性単量体組成物を得た。
一方、メチルメタクリレート（Ｔｇ＝１０５℃）２部と水６５部を超音波乳化機にて微分散化処理して、シェル用重合性単量体の水分散液を得た。
【００６９】
他方、イオン交換水２５０部に塩化マグネシウム１０．２部を溶解した水溶液に、イオン交換水５０部に水酸化ナトリウム６．２部を溶解した水溶液を攪拌下で徐々に添加して、水酸化マグネシウムコロイド分散液を調製した。得られた水酸化マグネシウムコロイド分散液に５％四ホウ酸ナトリウム十水和物水溶液を２０部添加し、分散安定化剤の水分散液を調製した。
【００７０】
分散安定化剤の水分散液を調製した後、直ちに上述したコア用重合性単量体を添加し、次いで１５，０００ｒｐｍで回転するエバラマイルダー（荏原製作所社製：商品名ＭＤＮ３０３Ｖ）を総滞留時間３秒で通過させ、通過させた分散液を、インナーノズルを経て、元の撹拌槽内に噴出速度０．５ｍ／ｓで戻し循環させ単量体組成物の液滴を形成させた。次いで９０℃に加温し重合反応を開始させた。重合転化率がほぼ１００％に達した後、前記シェル用重合性単量体の水分散液に２−メチル−Ｎ−（２−ハイドロキシエチル）−プロピオンアミド（和光純薬社製、商品名「ＶＡ−０８６」）０．３部を溶解し、それを反応器に入れた。４時間重合を継続した後、反応を停止し、トナー粒子の水分散液を得た。このトナー粒子の水分散液を酸洗浄した後、脱水、乾燥して、トナー粒子を得た。
得られたトナー粒子１００部に、疎水化処理したコロイダルシリカ（日本アエロジル社製：ＲＸ−１００）０．６部を添加し、ヘンシェルミキサーを用いて混合し、静電荷像現像用トナーを得た。得られた静電荷像現像用トナーについて、実施例１と同様に評価を行った。評価結果を表２に示す。
【００７１】
比較例２
４つ口フラスコに環流冷却器、水分離装置、窒素ガス導入管、温度計、撹拌装置を取り付け、マントルヒーター中に設置し、ビスフェノールＡ−ＥＯ付加物５部、ビスフェノールＡ−ＰＯ付加物５部、テレフタル酸４部及フマル酸５部からなる単量体組成物を仕込み、フラスコ内に窒素を導入しながら加熱・撹拌して反応させポリエステル樹脂を得た。
次いで、上述のようにして得られたポリエステル樹脂７０部及びＣ．Ｉ．ピグメントブルー１５：３（クラリアント社製）３０部を加圧ニーダーに仕込み混合した。得られた混合物を冷却後、フェザーミルにより粉砕し顔料マスターバッチを得た。
【００７２】
次いで、上述のようにして得られたポリエステル樹脂９３部、顔料マスターバッチ１０部及びサリチル酸亜鉛金属錯体（オリエント化学工業社製、商品名「Ｅ８４」）２部、酸化型低分子ポリプロピレン（三洋化成工業社製、商品名「ビスコールＴＳ２００」、融点：１４０℃、水酸基価：３．３ｍｇＫＯＨ／ｇ）２部をヘンシェルミキサーで十分混合した後、混合物を２軸押出混練機で溶融混練し、得られた混練物を迅速に冷却した後、フェザーミルで粗粉砕した。その粗砕物をジェット粉砕機（日本ニューマチック工業社製、商品名「ＩＤＳ」）で粉砕粗粉分級したのち、ＤＳ分級機（日本ニューマチック工業社製）で微粉分級することによりトナー母粒子を得た。
【００７３】
得られたトナー母粒子１００部に対して疎水性シリカＴＳ５００ （キャボジル社製、ＢＥＴ比表面積２２５ｍ^２／ｇ）０．５部及び疎水性シリカＮＡＸ５０ （日本アエロジル社製、ＢＥＴ比表面積４０ｍ^２／ｇ）０．３重量部を添加し、ヘンシェルミキサーを用い周速３０ｍ／ｓｅｃで９０秒間混合処理を行った。次いで、表面改質装置（サーフュージングシステム；日本ニューマチック工業社製）を用いて、最高温度；２５０℃、滞留時間；０．５秒、粉体分散濃度；１００ｇ／ｍ^３、冷却風温度；１８℃、冷却水温度１０℃の条件でトナー母粒子の表面改質処理を行い、トナー母粒子１００部に対して、疎水性シリカＲ９７２（日本アエロジル社製、ＢＥＴ比表面積１１０ｍ^２／ｇ）０．５部及びチタン酸ストロンチウム粒子Ａ１を０．３部添加し、ヘンシェルミキサーを用いて周速３０ｍ／ｓｅｃで１８０秒間混合処理を行い、静電荷像現像用トナーを得た。得られた静電荷像現像用トナーについて、上述した評価を行った。評価結果を表２に示す。
【００７４】
比較例３
水５００部にリン酸カルシウム１０重量部を微分散させ、６５℃に昇温し、水性分散媒を得た。
また、スチレン９０部、２−エチルヘキシルアクリレート９部、メチルメタクリレート１部、着色剤（Ｃ．Ｉ．ピグメントブルー１５：３）５部、ジーｔ−ブチル−サリチル酸金属化合物０．５部、ポリエステル樹脂５部、エステル系ワックス（融点：６０℃、水酸基価：１．２ｍｇＫＯＨ／ｇ、重量平均分子量；３，５００）１０部、及びジビニルベンゼン０．０５部を混合し、６５℃に加温して十分に溶解分散し、重合性単量体組成物とした。
【００７５】
上記水性分散媒を高速回転剪断撹拌機クレアミックス（エム・テクニック社製）で、高撹拌下に撹拌し、上記で調製した重合性単量体組成物を投入して１０分間、液滴の形成を行った。ここに、重合開始剤として２，２’−アゾビス（２，４−ジメチルバレロニトリル）４部を添加し、さらに５分間液滴の形成を行った。液滴形成終了後、液滴を含む水性分散媒をマックスブレンド翼（住友重工社製）を備えた撹拌機の容器内に移し、回転数を、６０回転／分になるよう調整した。内温６５℃で重合を継続させた。転化率が９０％になった時点で、ベンゾイルパーオキサイド１部を６０秒間かけて添加した。
【００７６】
重合温度を７５℃に昇温し、加熱撹拌を５時間継続して重合を完了した。重合反応終了後、減圧下で残存モノマーを留去し、冷却後、希塩酸を添加して分散剤を溶解し、固液分離、水洗、ろ過、乾燥することによりトナー粒子を得た。
上述のようにして得られたトナー粒子１００部に、疎水化処理されたコロイダルシリカ（日本アエロジル社製：ＲＸ−２００）０．６部を添加し、ヘンシェルミキサーを用いて混合し、負帯電性静電荷像現像用トナーを調製した。得られた静電荷像現像用トナーについて、上述した評価を行った。評価結果を表２に示す
【００７７】
【表１】

【００７８】
【表２】

【００７９】
表１及び表２の静電荷像現像用トナーの評価結果から、以下のことがわかる。
（ａ−２ｂ）μｍ以上ａμｍ未満の粒径を有するトナー粒子の平均円形度（Ｃ１）と、ａμｍ以上（ａ＋２ｂ）μｍ未満の粒径を有するトナー粒子の平均円形度（Ｃ２）との比（Ｃ１／Ｃ２）が、本発明で規定する範囲より大きい比較例１〜３の静電荷像現像用トナーは、保存性及び流動性が低下しており、カブリが発生しやすく、細線再現性が低下しており、連続印字における印字濃度が低下している。
これに対して、本発明の実施例１及び実施例２の静電荷像現像用トナーは、保存性、流動性、細線再現性が良好であり、印字濃度が高く、カブリの発生しないものである。
【００８０】
【発明の効果】
本発明により、ドット再現性、印字特性及び保存性に優れた静電荷像現像用トナーが提供される。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrostatic image developing toner, and more particularly, to an electrostatic image developing toner having excellent dot reproducibility, printing characteristics, and storage stability.
[0002]
[Prior art]
Electrophotography generally involves forming an electrical latent image on a photoreceptor by various means, then developing the latent image with toner to form a visible image, and transferring the latent image to a transfer material such as paper or an OHP sheet. This method refers to a method of obtaining a printed matter by transferring a toner that has become a visual image and then fixing the transferred toner on a transfer material by pressure or the like.
In recent years, the functions of printers and copiers have become more sophisticated, and there has been a demand for a method of forming an electrostatic charge image with a laser to achieve high resolution and high speed at the same time. For this reason, toners are required to have a small particle size and a sharp particle size distribution so as to be able to cope with a higher resolution, as well as a low-temperature fixing that can be used for a high-speed model. In particular, in the case of a color toner, the required level is high because an image is formed by superimposing toners of four colors.
Further, as in the conventional case, the toner is required to have performance such as stability of charging characteristics and cleaning properties. This is because if the charging characteristics change over time, the quality of an image is greatly affected, and a softening agent or a release agent added for low-temperature fixing lowers storage stability and causes problems such as toner blocking. It is.
[0003]
Conventionally, a toner is manufactured by melt-kneading a colorant of a dye or a pigment or other additives in a binder resin such as a thermoplastic resin and uniformly dispersing the same, followed by finely pulverizing with a pulverizer. The so-called grinding method was used. In this pulverization method, it is difficult to reduce the particle size of the toner to about 5 to 6 μm or less, and there is a limit in narrowing the particle size distribution even in the classification operation. Further, since additives such as a softening agent and a release agent are exposed on the surface of the toner, the controllability of the charge amount and the storage stability of the toner are reduced, and problems such as blocking of the toner occur.
In order to solve the above problems, various toners manufactured by a polymerization method have been proposed.
JP-A-2003-29459 discloses that an average circularity obtained by aggregating a polymer obtained by an emulsion polymerization method is 0.94 to 0.98, and a gradient of circularity with respect to a circle equivalent diameter is −0.0. 005 to -0.001 are disclosed. This toner has a problem that aggregation occurs due to long-term storage and the toner characteristics are deteriorated.
[0004]
[Patent Document 1]
JP 2003-29459 A
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a toner for developing an electrostatic image, which is excellent in dot reproducibility, printing characteristics and storage stability.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, in an electrostatic image developing toner containing at least a binder resin, a colorant, a charge control agent and a toner particle comprising a release agent, the toner particles Volume mode diameter, ratio (Dv / Dp) of volume average particle diameter (Dv) to number average particle diameter (Dp), average circularity, standard deviation of particle diameter, average circularity of toner particles having a specific particle diameter And the average circularity of the toner particles having other specific particle diameters in a specific range, and the content of the n-hexane extractable component and the content of the methanol extractable component in the specific range, thereby achieving the above object. Was found to be able to achieve.
[0007]
The present invention has been made based on the above findings, and is an electrostatic image developing toner containing at least toner particles comprising a binder resin, a colorant, a charge control agent, and a release agent. Has a volume mode diameter (a) of 5 to 10 μm, a ratio (Dv / Dp) of a volume average particle diameter (Dv) to a number average particle diameter (Dp) of 1.0 to 1.3, and an average circular shape. Degree is 0.97 to 0.995, the standard deviation (b) of the particle diameter of the toner particles is 2 μm or less, and (a−2b) the average circularity of the toner particles having a particle diameter of not less than μm and less than a μm ( The ratio (C1 / C2) of C1) to the average circularity (C2) of toner particles having a particle diameter of a μm or more and less than (a + 2b) μm is 1.00 to 1.02, and contains an n-hexane extraction component. The amount is 1 to 15% by weight, and the content of the methanol extraction component is 5% by weight. Is lower, there is provided a toner for developing electrostatic images.
The toner for developing an electrostatic image is excellent in dot reproducibility, printing characteristics and storage stability.
[0008]
The release agent preferably has a weight average molecular weight of 1,000 to 3,000, or a melting point of 40 to 100 ° C.
The release agent preferably has a hydroxyl value of 0 to 5 mgKOH / g.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the toner for developing an electrostatic image of the present invention will be described.
The toner particles constituting the toner for developing an electrostatic image of the present invention include at least a binder resin, a colorant, a charge control agent, and a release agent.
Specific examples of the binder resin include polystyrene, styrene-butyl acrylate copolymer, polyester resin, and epoxy resin, which are conventionally used widely in toner.
[0010]
As the colorant, any pigments and dyes can be used in addition to carbon black, titanium black, magnetic powder, oil black, and titanium white. As the black carbon black, those having a primary particle diameter of 20 to 40 nm are suitably used. When the particle size is in this range, carbon black can be uniformly dispersed in the toner, and fog is reduced, which is preferable.
[0011]
When a color toner is obtained, a yellow colorant, a magenta colorant or a cyan colorant is usually used.
As the yellow colorant, for example, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 83, 90, 93, 97, 120, 138, 155, 180, 181, 185, 186, and 186.
As the magenta colorant, for example, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Red 31, 48, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 150, 163, 170, 184, 185, 187, 202, 206, 207, 209, 251; I. Pigment Violet 19 and the like.
As the cyan coloring agent, for example, a copper phthalocyanine compound and a derivative thereof, an anthraquinone compound, and the like can be used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17, 60 and the like.
The amount of the colorant is preferably 1 to 10 parts by weight based on 100 parts by weight of the binder resin.
In order to obtain a full-color image, development is performed by combining a toner containing three colors of cyan, magenta, and yellow and, if necessary, a black colorant.
[0012]
As the charge control agent, a charge control resin is preferable. The reason for this is that the charge control resin has high compatibility with the binder resin, is colorless, and can provide a toner for developing an electrostatic charge image with stable chargeability even in high-speed color continuous printing. Examples of the charge control resin include quaternary ammonium produced according to the description in JP-A-63-60458, JP-A-3-175456, JP-A-3-243954, JP-A-11-15192 and the like. A (salt) group-containing copolymer, a sulfonic acid (salt) group-containing copolymer produced according to the description in JP-A-1-217464, JP-A-3-15858 and the like can be used. .
The content of the monomer having a quaternary ammonium (salt) group or a sulfonic acid (salt) group contained in these copolymers is preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight. % By weight. When the content is within this range, the charge amount of the toner for developing an electrostatic image is easily controlled, and the occurrence of fog can be reduced.
[0013]
The charge control resin preferably has a weight average molecular weight of 3,000 to 300,000, more preferably 4,000 to 50,000, and most preferably 6,000 to 35,000. If the weight average molecular weight of the charge control resin is less than 3,000, the viscosity at the time of kneading in producing the toner for developing an electrostatic image may be too low, and the dispersion of the pigment may be insufficient.
The glass transition temperature of the charge control resin is preferably from 40 to 80 ° C, more preferably from 45 to 75 ° C, and most preferably from 45 to 70 ° C. If the glass transition temperature is lower than 40 ° C., the storage stability of the toner for developing an electrostatic image deteriorates, and if it exceeds 80 ° C., the fixability may decrease.
[0014]
The amount of the charge control agent is usually 0.01 to 30 parts by weight, preferably 0.3 to 25 parts by weight, based on 100 parts by weight of the binder resin.
[0015]
Examples of the release agent include polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; natural plant waxes such as candelilla, carnauba, rice, wood wax, jojoba; paraffin, microcrystalline, petrolatum, and the like. Petroleum waxes and modified waxes thereof; synthetic waxes such as Fischer-Tropsch wax; polyfunctional ester compounds such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, and dipentaerythritol hexamyristate;
The release agent can be used alone or in combination of two or more.
[0016]
Among the above release agents, a synthetic wax and a polyfunctional ester compound are preferable. Among these, in the DSC curve measured by the differential scanning calorimeter, the endothermic peak temperature at the time of temperature rise is preferably in the range of 30 to 150 ° C, more preferably 40 to 100 ° C, and most preferably 50 to 80 ° C. A polyfunctional ester compound is preferable because a toner having an excellent balance between fixation and releasability at the time of fixing can be obtained. In particular, those having a weight average molecular weight of 1,000 to 3,000 are preferable, and those having a weight average molecular weight of 1,500 to 2,500 are more preferable. Further, those having a melting point of not less than 5 parts by weight based on 100 parts by weight of styrene at 25 ° C. and an acid value of not more than 10 mgKOH / g are more preferable since they have a remarkable effect on lowering the fixing temperature. Endothermic peak temperature means the value measured by ASTM D3418-82. The release agent preferably has a melting point of 40 to 100 ° C, more preferably 60 to 80 ° C.
[0017]
The hydroxyl value of the release agent is preferably 0 to 5 mgKOH / g, more preferably 0 to 3 mgKOH / g. If the hydroxyl value of the release agent exceeds 5 mgKOH / g, the image quality tends to decrease.
The amount of the release agent is usually 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the binder resin.
[0018]
The toner particles can be so-called core-shell type (or also referred to as “capsule type”) particles obtained by combining two different polymers inside (core layer) and outside (shell layer) of the particles. . In the core-shell type particles, by lowering the softening point substance inside (core layer) with a substance having a higher softening point, it is possible to balance between lowering the fixing temperature and preventing aggregation during storage. preferable.
Usually, the core layer of the core-shell type particles is composed of the binder resin, the colorant, the charge control resin, and the release agent, and the shell layer is composed of only the binder resin.
[0019]
The weight ratio between the core layer and the shell layer of the core-shell type particles is not particularly limited, but is usually from 80/20 to 99.9 / 0.1.
By setting the proportion of the shell layer in the above range, it is possible to provide both the storage stability of the toner for developing an electrostatic image and the fixability at a low temperature.
[0020]
The average thickness of the shell layer of the core-shell type particles is usually 0.001 to 1.0 μm, preferably 0.003 to 0.5 μm, more preferably 0.005 to 0.2 μm. When the thickness is large, the fixability is reduced, and when the thickness is small, the storability may be reduced. The core particles forming the core-shell type toner particles do not need to have all surfaces covered with the shell layer, and may have a part of the surface of the core particles covered with the shell layer.
When the core particle diameter and the shell layer thickness of the core-shell type particles can be observed by an electron microscope, they can be obtained by directly measuring the size and shell thickness of randomly selected particles from the observation photograph, When it is difficult to observe the core and the shell in the above, it can be calculated from the particle size of the core particles and the amount of the monomer forming the shell used in the production of the toner for developing an electrostatic image.
[0021]
The toner particles constituting the electrostatic image developing toner of the present invention have a volume mode diameter (a) of 5 to 10 μm, preferably 5 to 8 μm. If the volume mode diameter (a) is less than 5 μm, the fluidity of the toner becomes small, fog may occur, transfer residue may occur, or the cleaning property may decrease. May decrease. The volume mode diameter (a) is the most frequent value in the particle size distribution on a volume basis. The volume mode diameter of the toner particles can be measured using, for example, a flow type particle image analyzer “FPIA-1000” or “FPIA-2000” manufactured by Sysmex Corporation.
[0022]
The ratio (Dv / Dp) of the volume average particle diameter (Dv) to the number average particle diameter (Dp) of the toner particles constituting the toner for developing an electrostatic image of the present invention is 1.0 to 1.3. , Preferably 1.0 to 1.2. When Dv / Dp exceeds 1.3, fog occurs.
The volume average particle diameter and the number average particle diameter of the toner particles can be measured using, for example, a Multisizer (manufactured by Beckman Coulter, Inc.).
[0023]
The toner particles constituting the electrostatic image developing toner of the present invention have an average circularity measured by a flow type particle image analyzer of 0.97 to 0.995, preferably 0.975 to 0.995. And more preferably 0.98 to 0.995. When the average circularity is less than 0.97, the reproducibility of fine lines is obtained in an L / L environment (temperature: 10 ° C., humidity: 20%), in an N / N environment (temperature: 23 ° C., humidity: 50%), Inferior in any H / H environment (temperature: 35 ° C., humidity: 80%).
The average circularity can be relatively easily adjusted to the above range by manufacturing using a phase inversion emulsification method, a dissolution suspension method, a polymerization method (suspension polymerization method or emulsion polymerization method) or the like.
[0024]
In the present invention, the circularity is defined as a value obtained by dividing the perimeter of a circle having the same projected area as the particle image by the perimeter of the projected image of the particle. Further, the average circularity in the present invention is used as a simple method for quantitatively expressing the shape of particles, and is an index indicating the degree of unevenness of the toner. In the case of 1, the value becomes smaller as the surface shape of the toner particles becomes more complicated.
The average circularity (Ca) is a value obtained by the following equation.
[0025]
(Equation 1)

[0026]
In the above equation, n is the number of particles for which the circularity Ci has been determined.
In the above equation, Ci is the circularity of each particle calculated by the following equation based on the circumference measured for each particle of the particle group having a circle equivalent diameter of 0.6 to 400 μm.
Circularity (Ci) = Circumference length of circle equal to projected area of particle / Circumference length of particle projected image In the above equation, fi is the frequency of particles having circularity Ci.
The circularity and the average circularity can be measured using a flow particle image analyzer “FPIA-1000” or “FPIA-2000” manufactured by Sysmex Corporation.
[0027]
The standard deviation (b) of the particle size of the toner particles constituting the toner for developing an electrostatic image of the present invention is 2 μm or less, preferably 1.5 μm or less. When the standard deviation of the particle size of the toner particles exceeds 2 μm, fogging occurs.
The standard deviation of the toner particles is a volume-based value that can be measured using a flow particle image analyzer “FPIA-1000” or “FPIA-2000” manufactured by Sysmex Corporation, similarly to the circularity and the average circularity. .
[0028]
Assuming that the volume mode diameter is a and the standard deviation of the toner particle diameter is b, the toner particles constituting the electrostatic image developing toner of the present invention have a particle diameter of (a−2b) μm or more and less than a μm. (C1 / C2) is 1.00 to 1.02 when the average circularity of the toner particles is C1 and the average circularity of the toner particles having a particle diameter of a μm or more and less than (a + 2b) μm is C2. , Preferably 1.00 to 1.01. This numerical value is significant in expressing the coalesced state of the toner particles. When (C1 / C2) is large, it indicates that so-called coalesced particles in which two toner particles are bonded are increased. When (C1 / C2) is in the above range, fog hardly occurs and good image quality can be obtained.
In addition, C1 and C2 can also be measured using a flow type particle image analyzer “FPIA-1000” or “FPIA-2000” manufactured by Sysmex Corporation, similarly to the circularity and the average circularity.
[0029]
The electrostatic image developing toner of the present invention has an n-hexane extractable component content of 1 to 15% by weight, and preferably 3 to 13% by weight. When the content of the n-hexane extractable component is less than 1% by weight, the fixing temperature rises, and hot offset tends to occur. On the other hand, if it exceeds 15% by weight, the storage stability will decrease. Note that the content of the n-hexane extractable component can be measured by the method described below.
The toner for developing an electrostatic image of the present invention has a methanol extractable component content of 5% by weight or less, and preferably 4% by weight or less. If the content of the methanol-extracted component exceeds 5% by weight, it becomes hygroscopic, environmental stability (reproducibility of fine lines) is reduced, and fogging occurs. Incidentally, the content of the methanol extractable component can be measured by the method described later.
[0031]
The electrostatic image developing toner of the present invention can be used as it is for electrophotographic development, but usually, in order to adjust the chargeability, fluidity, storage stability, etc. of the electrostatic image developing toner, It is preferable that fine particles having a particle size smaller than the toner particles (hereinafter, referred to as an external additive) are attached or embedded on the surface of the toner particles before use.
Examples of the external additive include inorganic particles and organic resin particles that are generally used for the purpose of improving fluidity and chargeability. These particles added as external additives have a smaller average particle size than the toner particles. For example, as the inorganic particles, silica, aluminum oxide, titanium oxide, zinc oxide, tin oxide and the like can be mentioned, and as the organic resin particles, methacrylate polymer particles, acrylate polymer particles, styrene-methacrylate ester Copolymer particles, styrene-acrylate copolymer particles, core-shell type particles in which the core is a styrene polymer and the shell is formed of a methacrylate polymer, and the like. Among these, silica particles and titanium oxide particles are preferable, particles whose surface is subjected to a hydrophobic treatment are preferable, and silica particles whose surface is subjected to a hydrophobic treatment are particularly preferable. The amount of the external additive is not particularly limited, but is usually 0.1 to 6 parts by weight based on 100 parts by weight of the toner particles.
[0032]
The method for producing the toner for developing an electrostatic image of the present invention is not particularly limited as long as it can provide a toner having the characteristics in the above-mentioned range, but is preferably produced by a polymerization method.
Next, a method for producing toner particles constituting the electrostatic image developing toner by a polymerization method will be described.
The toner particles constituting the toner for developing an electrostatic image of the present invention contain, as a dispersion stabilizer, a colloid of a poorly water-soluble inorganic compound formed by adding an alkali metal hydroxide to a water-soluble polyvalent inorganic salt. Preparing an aqueous dispersion medium to be treated and leaving it at a temperature of 15 to 35 ° C. for 4 to 18 hours for aging; a polymerizable monomer containing a polymerizable monomer, a colorant, a charge control agent and a polymerization initiator The composition is added to the aged aqueous dispersion medium to form droplets, an aqueous solution of a boron compound is added to the aqueous dispersion medium, and then the temperature of the aqueous dispersion medium is increased to polymerize the toner particles. Can be obtained.
[0033]
In the present invention, when obtaining a polymerizable monomer composition, to obtain a charge control resin composition manufactured by previously mixing a colorant and a charge control resin, it is converted to a polymerizable monomer together with a release agent and the like. You may add and mix. At that time, the amount of the colorant is usually 10 to 200 parts by weight, preferably 20 to 150 parts by weight, based on 100 parts by weight of the charge control resin. For the production of the charge control resin composition, it is preferable to use an organic solvent. The use of the organic solvent makes the charge control resin soft and easy to mix with the pigment.
[0034]
The amount of the organic solvent is usually from 0 to 100 parts by weight, preferably from 5 to 80 parts by weight, more preferably from 10 to 60 parts by weight, based on 100 parts by weight of the charge control resin. And the balance of workability is excellent. At this time, the organic solvent may be added all at once, or may be added in several portions while checking the mixed state.
Mixing can be carried out using a roll, a kneader, a single screw extruder, a twin screw extruder, a Banbury, a Buss co-kneader or the like. When an organic solvent is used, a closed mixer in which the organic solvent does not leak to the outside is preferable.
Further, it is preferable that a torque meter is installed in the mixer because the dispersibility can be controlled at the torque level.
[0035]
Examples of the polymerizable monomer include a monovinyl monomer, a crosslinkable monomer, and a macromonomer. This polymerizable monomer is polymerized to become a binder resin component.
Monovinyl monomers include aromatic vinyl monomers such as styrene, vinyltoluene and α-methylstyrene; (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid. (Meth) acrylic copolymers such as propyl, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobonyl (meth) acrylate; monomers such as ethylene, propylene, and butylene Olefin monomers; and the like.
Monovinyl monomers may be used alone or in combination of a plurality of monomers. Of these monovinyl monomers, an aromatic vinyl monomer alone, or a combination of an aromatic vinyl monomer and a (meth) acrylic monomer is preferably used.
[0036]
When a crosslinkable monomer is used together with the monovinyl monomer, hot offset is effectively improved. The crosslinkable monomer is a monomer having two or more vinyl groups. Specific examples include divinylbenzene, divinylnaphthalene, ethylene glycol dimethacrylate, pentaerythritol triallyl ether, and trimethylolpropane triacrylate. These crosslinkable monomers can be used alone or in combination of two or more. The amount of the crosslinkable monomer is usually 10 parts by weight or less, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the monovinyl monomer.
[0037]
Further, it is preferable to use a macromonomer together with the monovinyl monomer, because the balance between the preservability and the fixing property at a low temperature is improved. The macromonomer has a polymerizable carbon-carbon unsaturated double bond at the terminal of the molecular chain, and is usually an oligomer or polymer having a number average molecular weight of 1,000 to 30,000.
The macromonomer is preferably one that gives a polymer having a glass transition temperature higher than the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer.
The amount of the macromonomer is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the monovinyl monomer.
[0038]
Examples of the polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-methyl-N- (2- Hydroxyethyl) propionamide, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, etc. Azo compounds: di-t-butyl peroxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-hexyl peroxy-2-ethylhexanoate, t-butyl peroxypivalate, -Peracids such as isopropylperoxydicarbonate, di-t-butylperoxyisophthalate and t-butylperoxyisobutyrate Goods and the like can be mentioned. It is also possible to use a redox initiator which is a combination of the polymerization initiator and a reducing agent.
[0039]
The amount of the polymerization initiator used for the polymerization of the polymerizable monomer is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 15 parts by weight, based on 100 parts by weight of the polymerizable monomer. Parts, most preferably 0.5 to 10 parts by weight. The polymerization initiator may be added to the aqueous dispersion medium after the formation of the droplets, but it is more preferable to add the polymerization initiator to the polymerizable monomer composition in advance.
[0040]
The colloid of a poorly water-soluble inorganic compound used as a dispersion stabilizer is formed by mixing a water-soluble polyvalent inorganic salt and an alkali metal hydroxide in an aqueous dispersion medium. Examples of such poorly water-soluble inorganic compounds include magnesium hydroxide. It is preferable to use the aqueous dispersion medium containing the poorly water-soluble inorganic compound colloid for aging after it is aged because the toner for developing an electrostatic image of the present invention can be easily obtained. In the present invention, aging means that an aqueous dispersion medium containing a colloid of a poorly water-soluble inorganic compound is prepared and then left for a certain period of time without immediate use. Specifically, it is left at a temperature of 15 to 35 ° C., preferably 20 to 35 ° C. for 4 to 18 hours, preferably 5 to 20 hours.
[0041]
The amount of the dispersion stabilizer is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer. When the amount of the dispersion stabilizer is less than 0.1 part by weight, it is difficult to obtain sufficient polymerization stability, and a polymer aggregate may be easily generated. On the other hand, when the amount exceeds 20 parts by weight, Then, the effect of the polymerization stability is saturated, and in addition to being uneconomical, the viscosity of the aqueous dispersion medium becomes too high, and it may be difficult to form small droplets after mixing.
At the time of polymerization, a water-soluble polymer can be used in combination as long as the environment-dependent charging characteristics of the polymerized toner and the change in fixability do not become large. Examples of the water-soluble polymer include polyvinyl alcohol, methyl cellulose, gelatin and the like.
[0042]
In the polymerization, it is preferable to form a droplet of the polymerizable monomer and then add an aqueous solution of a boron compound to an aqueous dispersion medium containing the droplet. Examples of the boron compound include boron trifluoride, boron trichloride, tetrafluoroborate, sodium tetrahydroborate, potassium tetrahydroborate, sodium tetraborate, sodium tetraborate decahydrate, sodium metaborate, and sodium metaborate Tetrahydrate, sodium peroxoborate tetrahydrate, boric acid, potassium metaborate, potassium tetraborate octahydrate and the like can be mentioned. The boron compound is preferably added in the form of an aqueous solution. The amount of the boron compound is preferably 0.1 to 1000 parts by weight, more preferably 1 to 100 parts by weight, based on 100 parts by weight of the colloid of the poorly water-soluble compound.
[0043]
Further, it is preferable to use a molecular weight modifier during the polymerization. Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2,4,6,6-pentamethylheptane-4-thiol. The molecular weight modifier can be added before or during the polymerization. The amount of the molecular weight modifier is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer.
[0044]
The method for producing the core-shell toner particles is not particularly limited, and can be produced by a conventionally known method. For example, a method such as a spray drying method, an interfacial reaction method, an in situ polymerization method, and a phase separation method may be used. Specifically, core-shell type toner particles can be obtained by using a toner particle obtained by a pulverization method, a polymerization method, an association method or a phase inversion emulsification method as a core particle and coating a shell layer thereon. Among these production methods, an in situ polymerization method and a phase separation method are preferable from the viewpoint of production efficiency.
[0045]
A method for producing core-shell type toner particles by an in situ polymerization method will be described below.
A polymerizable monomer for forming a shell (polymerizable monomer for shell) and a polymerization initiator are added to an aqueous dispersion medium in which the core particles are dispersed, and the polymerization is performed. Can be obtained.
As a specific method of forming the shell, a method of continuously polymerizing by adding a polymerizable monomer for shell to the reaction system of the polymerization reaction performed to obtain the core particles, or a method obtained by another reaction system And a method of charging the core particles prepared above, adding a polymerizable monomer for shell to the core particles, and performing polymerization.
The polymerizable monomer for shell may be added to the reaction system at once, or may be added continuously or intermittently using a pump such as a plunger pump.
[0046]
As the polymerizable monomer for the shell, monomers that form a polymer having a glass transition temperature exceeding 80 ° C., such as styrene, acrylonitrile, and methyl methacrylate, can be used alone or in combination of two or more. .
[0047]
When adding the polymerizable monomer for shell, it is preferable to add a water-soluble polymerization initiator since core-shell type toner particles can be easily obtained. When the water-soluble polymerization initiator is added during the addition of the shell-polymerizable monomer, the water-soluble polymerization initiator moves to the vicinity of the outer surface of the core particle, and the shell-polymerizable monomer is transferred to the surface of the core particle. It is considered that polymerization is likely to occur.
[0048]
Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) propionamide), 2,2′-azobis- An azo initiator such as (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide) and the like can be mentioned. The amount of the water-soluble polymerization initiator is usually 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight, based on 100 parts by weight of the polymerizable monomer for shell.
[0049]
The temperature during the polymerization is preferably 50 ° C. or higher, more preferably 80 to 95 ° C. The reaction time is preferably from 1 to 20 hours, more preferably from 2 to 10 hours. After completion of the polymerization, it is preferable to repeat the operations of filtration, washing, dehydration and drying several times as necessary according to a conventional method.
[0050]
When an inorganic compound colloid is used as a dispersion stabilizer, an acid is added to dissolve the poorly water-soluble inorganic compound colloid so that the pH of an aqueous dispersion of toner particles obtained by polymerization is 6.5 or less. preferable. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid and acetic acid can be used. However, sulfuric acid is particularly preferred because of high removal efficiency and a small burden on manufacturing equipment. It is.
The method for filtering and dewatering the toner particles from the aqueous dispersion is not particularly limited. For example, a centrifugal filtration method, a vacuum filtration method, a pressure filtration method, and the like can be given. Of these, the centrifugal filtration method is preferred. After filtration, the toner particles are dried using a vacuum drier or the like as necessary.
[0051]
The toner for developing an electrostatic image of the present invention can be obtained by mixing toner particles, external additives, and, if necessary, other fine particles using a high-speed stirrer such as a Henschel mixer.
[0052]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples. It goes without saying that the scope of the present invention is not limited to the examples. In the following examples, parts and% represent parts by weight or% by weight unless otherwise specified.
[0053]
In this embodiment, the toner was evaluated by the following method.
(1) Particle Size, Average Circularity The particle size distribution of the toner particles, that is, the ratio (Dv / Dp) between the volume average particle size and the number average particle size (Dp) is determined by a particle size analyzer (manufactured by Beckman Coulter, Inc.). ("Multisizer"). The measurement by this multisizer was performed under the conditions of an aperture diameter: 100 μm, a medium: Isoton II, a concentration of 10%, and the number of particles measured: 50,000.
[0054]
(2) Volume mode 100 μl of a 0.1% aqueous solution of an anionic surfactant is added as a dispersion medium to toner particles having a diameter, an average circularity and a standard deviation of 20 mg as a dispersion medium. The diameter, average circularity, and standard deviation were measured. The measurement was performed using a flow particle image analyzer “FPIA-2000” manufactured by Sysmex Corporation. The analysis was performed on a volume basis (for a section of 15 μm or less).
Furthermore, the average circularity (C1) of toner particles having a particle diameter of (a-2b) μm or more and less than aμm and the average circularity (C2) of toner particles having a particle diameter of aμm or more and less than (a + 2b) μm are also described. Was determined by the above apparatus.
[0055]
(3) Content of n-hexane extraction component 1.0 g of the toner for developing an electrostatic image and 100 ml of n-hexane were put into a Soxhlet extractor containing a cylindrical filter paper (manufactured by Toyo Roshi Kaisha, No. 86R) under normal pressure. After refluxing for 6 hours, an extract was obtained. The solvent was evaporated from the extract, and the solid content was vacuum-dried at a temperature of 50 ° C. for 1 hour and weighed. This weighed value was divided by the weighed value of the toner for developing an electrostatic charge image initially weighed and multiplied by 100 to obtain the content (%) of the n-hexane extractable component.
[0056]
(4) Content of methanol-extracted component 1.0 g of the toner for developing an electrostatic image and 100 ml of methanol were put into a Soxhlet extractor containing a cylindrical filter paper (No. 86R, manufactured by Toyo Roshi Kaisha), and refluxed at normal pressure for 6 hours. To obtain an extract. The solvent was evaporated from the extract, and the solid content was vacuum-dried at a temperature of 50 ° C. for 1 hour and weighed. This weighed value was divided by the weighed value of the toner for developing an electrostatic charge image initially weighed and multiplied by 100 to obtain the content (%) of the methanol extractable component.
[0057]
(5) Three types of sieves each having a flow opening of 150 μm, 75 μm, and 45 μm are stacked in this order from the top, and 4 g of a sample (toner for developing an electrostatic image) is placed on the uppermost sieve. Was weighed and placed. Next, the three kinds of stacked sieves were vibrated for 15 seconds under the condition of a vibration intensity of 4 using a powder measuring device (trade name “Power Tester” manufactured by Hosokawa Micron Corporation), and then remained on each sieve. The mass of the electrostatic image developing toner is measured. Each measured value is inserted into the following formula to obtain a value of fluidity. One sample was measured three times, and the average value was determined.
Calculation formula:
a = (mass (g) of toner for developing an electrostatic image remaining on a sieve having an aperture of 150 μm) / 4 (g) × 100
b = (mass (g) of toner for developing an electrostatic image remaining on a sieve having an opening of 75 μm) / 4 (g) × 100 × 0.6
c = (mass (g) of toner for developing an electrostatic image remaining on a sieve having an opening of 45 μm) / 4 (g) × 100 × 0.2
Flowability (%) = 100− (a + b + c)
[0058]
(6) Preservation The toner for developing an electrostatic image is placed in a sealable container, sealed, then immersed in a thermostatic water bath at 55 ° C., taken out after 8 hours, and sieved with a 42 mesh sieve. The electrostatic image developing toner is taken out of the container and carefully transferred onto a sieve so as not to destroy the structure as much as possible. This sieve was vibrated for 30 seconds with the vibration intensity set to 4.5 using the powder measuring machine used in (6), and the weight of the electrostatic image developing toner remaining on the sieve was measured. As the weight of the aggregated toner. First, the ratio (% by weight) of the weight of the aggregated toner to the weight of the electrostatic image developing toner put in the container was calculated. The measurement was performed three times for each sample, and the average value was used as an index of storage stability.
The smaller the numerical value, the better the storage stability (% by weight) of the toner.
[0059]
(7) Fog A recycled paper is set on a commercially available non-magnetic one-component developing system printer (18-sheet machine), toner for developing an electrostatic image is put into the printer, and (L) at a temperature of 10 ° C. and a humidity of 20% is used. / L) in a (N / N) environment with a temperature of 23 ° C. and a humidity of 50%, and a (H / H) environment with a temperature of 35 ° C. and a humidity of 80%, respectively. The printing is paused after every 500 sheets, and the toner of the non-developed portion on the photoreceptor after development is applied to an adhesive tape (Sumitomo 3M, Scotch Mending Tape 810-3-18). Attached. It was affixed to printing paper, and its whiteness (B) was measured with a whiteness meter (manufactured by Nippon Denshoku). At the same time, the whiteness (A) of the printing paper to which only the adhesive tape was stuck was measured, and the difference (AB) (%) between the whiteness was determined. The maximum number of sheets (counted in units of 500 sheets) in which the difference between this value and the difference in whiteness (AB) (%) at the beginning of printing (at the time of printing 10 sheets) was 1% or less was examined. The test was completed after 10,000 sheets.
[0060]
(8) Fine line reproducibility Using the printer used in (7), under an (L / L) environment at a temperature of 10 ° C. and a humidity of 20%, under an (N / N) environment at a temperature of 23 ° C. and a humidity of 50%. After standing overnight in a (H / H) environment at 35 ° C. and 80% humidity, a line image is continuously formed on 2 × 2 dot lines (about 85 μm in width), and the print evaluation system “RT2000” is printed every 500 sheets. (Manufactured by YA-MA), and the density distribution data of the line image was collected.
At this time, when the full width at half the maximum value of the density is defined as the line width and the line width of the first line image is 10 μm or less, the line image of the first line image is reproduced. It was determined that the difference between the line widths of the line images was 10 μm or less.
[0061]
(9) Set the printing paper in the printer used in the printing density (7), put the toner in the developing device, and leave it overnight (H / H) at a temperature of 35 ° C. and a humidity of 80%, and then print the printing density of the printer. Is set to 5%, continuous printing is performed from the beginning, black solid printing is performed on the 100th printing (initial printing), and the 10,000th printing (continuous printing), and a transmission image density measuring device manufactured by McBeth Co., Ltd. Was used to measure the print density. This test was completed after 10,000 sheets.
[0062]
(10) Fixing Temperature of Toner A fixing test was performed using a commercially available non-magnetic one-component developing system printer (Microline 18NR, manufactured by Oki Data Co., Ltd. (18-sheet machine)) modified so that the temperature of the fixing roll part can be changed. The fixing test was performed by changing the temperature of the fixing roll of the modified printer by 5 ° C. at a time and measuring the fixing rate of the developer at each temperature to obtain the relationship between the temperature and the fixing rate. The fixation rate was calculated from the ratio of the image density before and after the tape peeling operation in the black solid area of the test paper printed by the remodeled printer, that is, the image density before the tape peeling before the ID, and the image density after the tape peeling before the ID. In the latter case, the fixing rate can be calculated from the following equation.
Fixing rate (%) = (after ID / before ID) × 100
In addition, the tape peeling operation means that an adhesive tape (Scotch Mending Tape 810-3-18 manufactured by Sumitomo 3M) is attached to the measurement portion of the test paper, adhered by pressing with a 500 g steel roller, and then at a constant speed. It means a series of operations for peeling the adhesive tape in the direction along the paper. The image density was measured using a Macbeth reflection image densitometer. In the fixing test, the temperature of the fixing roll at which the fixing rate became 80% was defined as the fixing temperature of the developer.
[0063]
(11) Hot offset In the same manner as in the measurement of the fixing temperature in the above (10), printing is performed by changing the temperature of the fixing roll by 5 ° C., and the temperature at which the toner remains on the fixing roll to cause contamination is determined by the hot offset. The generation temperature was used.
[0064]
Example 1
A flask is charged with 900 parts of toluene, 78 parts of styrene, 19 parts of 2-ethylhexyl acrylate, 3 parts of 2-acrylamido-2-methylpropanesulfonic acid, and 2 parts of azobisdimethylvaleronitrile, and stirred at 90 ° C. for 8 hours. Reacted. After completion of the reaction, toluene was distilled off under reduced pressure to obtain a charge control resin A (weight average molecular weight Mw = 21,000 measured by gel permeation chromatography using tetrahydrofuran).
5 parts of the charge control resin A described above, a core monomer composed of 90 parts of styrene, 9.3 parts of n-butyl acrylate and 0.7 part of divinylbenzene, and C.I. I. Pigment Blue 15: 3 (manufactured by Clariant), 5 parts, polymethacrylate macromonomer (manufactured by Toa Gosei Chemical Industry Co., Ltd., trade name "AA6", Tg = 94 ° C), 0.8 part, dipentaerythritol hexamyristate (Melting point: 65 ° C., hydroxyl value: 0.16 mg KOH / g) was stirred with a usual stirrer until the mixture became uniform to obtain a uniform mixture. 5 parts of a polymerization initiator t-butyl peroxy 2-ethylhexanoate (trade name "Perbutyl O", manufactured by NOF CORPORATION) was added to the homogeneous mixture to obtain a polymerizable monomer composition.
On the other hand, 4 parts of methyl methacrylate and 100 parts of water were mixed and finely dispersed by an ultrasonic emulsifier to obtain an aqueous dispersion of a polymerizable monomer for shell.
[0065]
On the other hand, an aqueous solution obtained by dissolving 9.5 parts of sodium hydroxide in 50 parts of ion-exchanged water was gradually added to an aqueous solution obtained by dissolving 9.5 parts of magnesium chloride in 250 parts of ion-exchanged water while stirring. A colloidal dispersion was prepared and left to mature for 6 hours. The above-mentioned polymerizable monomer composition is added to the aged dispersion, and a continuous emulsifying and dispersing machine, Ebara Milder MDN304 (manufactured by Ebara Corporation), is used at 15,000 rpm for 10 minutes. The mixture was stirred to form droplets of the polymerizable monomer composition. One part of sodium tetraborate decahydrate is added to the magnesium hydroxide colloidal dispersion containing the droplets, and the mixture is placed in a reactor equipped with a stirring blade, and the polymerization reaction is started at a temperature of 85 ° C. to effect polymerization conversion. When the ratio reaches almost 100%, the aqueous dispersion of the above-mentioned polymerizable monomer for shell and 2,2′-azobis (2-methyl-N (2-hydroxyethyl) -propionamide (Wako Pure Chemical Industries, Ltd.) The polymerization reaction was continued for 4 hours, and the reaction was stopped to obtain an aqueous dispersion of core-shell type toner particles.
[0066]
While stirring the aqueous dispersion of the core-shell type polymer toner particles obtained as described above, the pH of the system was adjusted to 4 or less with sulfuric acid, and acid washing (25 ° C., 10 minutes) was performed. After the separation, 500 parts of ion-exchanged water was newly added to reslurry, and the slurry was washed with water at 38 ° C. Next, dehydration and washing with water were repeated several times, and the solid content was separated by filtration, followed by drying at 45 ° C. for two days and nights using a drier to obtain toner particles.
To 100 parts of the toner particles obtained as described above, 0.6 part of colloidal silica (RX-200, manufactured by Nippon Aerosil Co., Ltd.) that has been subjected to a hydrophobic treatment is added, and mixed using a Henschel mixer to obtain a negatively chargeable toner. An electrostatic image developing toner was prepared. The above-mentioned evaluation was performed on the obtained electrostatic image developing toner. Table 1 shows the evaluation results.
[0067]
Example 2
To 900 parts of toluene, 78 parts of styrene, 7 parts of 2-ethylhexyl acrylate, 9 parts of 2-acrylamido-2-methylpropanesulfonic acid, and 2 parts of ethanol, 0.134 part of potassium hydroxide and 2 parts of azobisdimethylvaleronitrile were charged. After reacting at 90 ° C. for 8 hours, the solvent was distilled off under reduced pressure to obtain a charge control resin B (Mw = 21,000). The acid value of the obtained charge control resin B was 6.7 mgKOH / g.
The same operation as in Example 1 was carried out except that the charge control resin B obtained as described above was used, to obtain a toner for developing an electrostatic image. The obtained electrostatic image developing toner was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.
[0068]
Comparative Example 1
Core polymerizable monomer composed of 80.5 parts of styrene and 19.5 parts of n-butyl acrylate (Tg of copolymer obtained by copolymerizing these monomers = 55 ° C.), polymethacrylic acid 0.3 parts of ester macromonomer (manufactured by Toa Gosei Chemical Industry Co., Ltd., trade name "AA6", Tg = 94 ° C), 0.5 parts of divinylbenzene, 1.2 parts of t-dodecyl mercaptan, 1.2 parts of C.I. I. Pigment Blue 15: 3 (manufactured by Clariant), 7 parts, charge control resin A, 5 parts, release agent (Fisher Tropsch wax, manufactured by Nippon Seiro Co., Ltd., trade name: “SP-3040”), endothermic peak temperature: 100 ° C., melting point: 63 ° C., hydroxyl value: 0.1 mg KOH / g or less) 2 parts were charged into a stirring tank of a media type wet pulverizer to wet-pulverize the release agent, and then t-butyl peroxy-2 was used as a polymerization initiator. 5 parts of ethylhexanoate (trade name "Perbutyl O" manufactured by NOF CORPORATION) was added to obtain a polymerizable monomer composition for a core.
On the other hand, 2 parts of methyl methacrylate (Tg = 105 ° C.) and 65 parts of water were finely dispersed by an ultrasonic emulsifier to obtain an aqueous dispersion of a polymerizable monomer for shell.
[0069]
On the other hand, an aqueous solution obtained by dissolving 6.2 parts of sodium hydroxide in 50 parts of ion-exchanged water was gradually added to an aqueous solution obtained by dissolving 10.2 parts of magnesium chloride in 250 parts of ion-exchanged water. A colloidal dispersion was prepared. To the obtained magnesium hydroxide colloidal dispersion, 20 parts of a 5% aqueous solution of sodium tetraborate decahydrate was added to prepare an aqueous dispersion of a dispersion stabilizer.
[0070]
Immediately after preparing the aqueous dispersion of the dispersion stabilizer, the above-mentioned polymerizable monomer for a core is added, and then an Ebara Milder (trade name: MDN303V, manufactured by Ebara Corporation) that rotates at 15,000 rpm is totally retained. After passing for 3 seconds, the passed dispersion was returned and circulated through the inner nozzle into the original stirring tank at an ejection speed of 0.5 m / s to form droplets of the monomer composition. Then, the mixture was heated to 90 ° C. to start the polymerization reaction. After the polymerization conversion reached almost 100%, 2-methyl-N- (2-hydroxyethyl) -propionamide (trade name, manufactured by Wako Pure Chemical Industries, Ltd.) was added to the aqueous dispersion of the polymerizable monomer for shell. 0.3 g of VA-086 ") was dissolved and placed in the reactor. After the polymerization was continued for 4 hours, the reaction was stopped to obtain an aqueous dispersion of toner particles. The aqueous dispersion of the toner particles was washed with an acid, then dehydrated and dried to obtain toner particles.
To 100 parts of the obtained toner particles, 0.6 parts of colloidal silica (RX-100, manufactured by Nippon Aerosil Co., Ltd.) was added and mixed using a Henschel mixer to obtain a toner for developing an electrostatic image. . The obtained electrostatic image developing toner was evaluated in the same manner as in Example 1. Table 2 shows the evaluation results.
[0071]
Comparative Example 2
A four-necked flask was equipped with a reflux condenser, a water separator, a nitrogen gas inlet tube, a thermometer, and a stirrer, and was installed in a mantle heater. 5 parts of bisphenol A-EO adduct, 5 parts of bisphenol A-PO adduct Then, a monomer composition comprising 4 parts of terephthalic acid and 5 parts of fumaric acid was charged and heated and stirred while introducing nitrogen into the flask to obtain a polyester resin.
Next, 70 parts of the polyester resin obtained as described above and C.I. I. 30 parts of CI Pigment Blue 15: 3 (manufactured by Clariant) were charged into a pressure kneader and mixed. After cooling the obtained mixture, it was pulverized by a feather mill to obtain a pigment master batch.
[0072]
Next, 93 parts of the polyester resin obtained as described above, 10 parts of a pigment master batch, and 2 parts of a zinc salicylate metal complex (trade name “E84” manufactured by Orient Chemical Industries, Ltd.), oxidized low-molecular-weight polypropylene (Sanyo Chemical Industries, Ltd.) (Trade name: Viscol TS200, melting point: 140 ° C., hydroxyl value: 3.3 mg KOH / g) were sufficiently mixed with a Henschel mixer, and the mixture was melt-kneaded with a twin-screw extruder to obtain a mixture. After rapidly cooling the kneaded material, it was coarsely pulverized with a feather mill. The coarsely crushed product is crushed and coarse-powder-classified by a jet pulverizer (trade name “IDS” manufactured by Nippon Pneumatic Industries Co., Ltd.), and then finely classified by a DS classifier (manufactured by Nippon Pneumatics Co., Ltd.) to obtain toner base particles. Obtained.
[0073]
The obtained hydrophobic silica TS500 per 100 parts of the toner mother particles (Kyabojiru Co., BET specific surface area 225m ² /g)0.5 parts and hydrophobic silica NAX50 (Nippon Aerosil Co., Ltd., BET specific surface area ^{40 m} 2 / g ) Was added and mixed by a Henschel mixer at a peripheral speed of 30 m / sec for 90 seconds. Then, using a surface reforming apparatus (Surfusing system; manufactured by Nippon Pneumatic Industries, Ltd.), the maximum temperature: 250 ° C., the residence time: 0.5 seconds, the powder dispersion concentration: 100 g / m ³ , the cooling air temperature; A surface modification treatment of the toner base particles is performed under the conditions of 18 ° C. and a cooling water temperature of 10 ° C., and hydrophobic silica R972 (manufactured by Nippon Aerosil Co., Ltd., BET specific surface area 110 m ² / g) is applied to 100 parts of the toner base particles. 0.5 part and 0.3 part of strontium titanate particles A1 were added, and the mixture was subjected to a mixing treatment using a Henschel mixer at a peripheral speed of 30 m / sec for 180 seconds to obtain a toner for developing an electrostatic image. The above-mentioned evaluation was performed on the obtained electrostatic image developing toner. Table 2 shows the evaluation results.
[0074]
Comparative Example 3
10 parts by weight of calcium phosphate was finely dispersed in 500 parts of water, and the temperature was raised to 65 ° C. to obtain an aqueous dispersion medium.
Also, 90 parts of styrene, 9 parts of 2-ethylhexyl acrylate, 1 part of methyl methacrylate, 5 parts of a coloring agent (CI Pigment Blue 15: 3), 0.5 part of a metal compound of di-t-butyl-salicylate, and a polyester resin 5 Parts, 10 parts of an ester wax (melting point: 60 ° C., hydroxyl value: 1.2 mg KOH / g, weight average molecular weight: 3,500) and 0.05 parts of divinylbenzene, and heated to 65 ° C. Was dissolved and dispersed into a polymerizable monomer composition.
[0075]
The aqueous dispersion medium is stirred under high stirring with a high-speed rotary shear stirrer CLEARMIX (manufactured by M Technique Co., Ltd.), and the polymerizable monomer composition prepared as described above is charged and droplets are formed for 10 minutes. Was done. Here, 4 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and a droplet was formed for another 5 minutes. After the formation of the droplets, the aqueous dispersion medium containing the droplets was transferred into a container of a stirrer equipped with Max Blend blades (manufactured by Sumitomo Heavy Industries, Ltd.), and the rotation speed was adjusted to 60 rotations / minute. The polymerization was continued at an internal temperature of 65 ° C. When the conversion reached 90%, 1 part of benzoyl peroxide was added over 60 seconds.
[0076]
The polymerization temperature was raised to 75 ° C., and heating and stirring were continued for 5 hours to complete the polymerization. After completion of the polymerization reaction, residual monomers were distilled off under reduced pressure. After cooling, dilute hydrochloric acid was added to dissolve the dispersant, and solid-liquid separation, washing with water, filtration and drying were performed to obtain toner particles.
To 100 parts of the toner particles obtained as described above, 0.6 part of colloidal silica (RX-200, manufactured by Nippon Aerosil Co., Ltd.) that has been subjected to a hydrophobic treatment is added, and mixed using a Henschel mixer to obtain a negatively chargeable toner. An electrostatic image developing toner was prepared. The above-mentioned evaluation was performed on the obtained electrostatic image developing toner. The evaluation results are shown in Table 2.
[Table 1]

[0078]
[Table 2]

[0079]
The following can be seen from the evaluation results of the electrostatic image developing toners in Tables 1 and 2.
(A-2b) The ratio of the average circularity (C1) of toner particles having a particle diameter of not less than μm and less than aμm to the average circularity (C2) of toner particles having a particle diameter of not less than aμm and (a + 2b) μm ( C1 / C2) is larger than the range specified in the present invention, the toners for developing electrostatic images of Comparative Examples 1 to 3 have reduced storage stability and fluidity, are apt to generate fog, and have reduced fine line reproducibility. And the print density in continuous printing is reduced.
On the other hand, the toners for developing electrostatic images of Examples 1 and 2 of the present invention have good storability, fluidity and fine line reproducibility, high print density and no fog. .
[0080]
【The invention's effect】
According to the present invention, there is provided an electrostatic image developing toner having excellent dot reproducibility, printing characteristics and storage stability.

Claims (4)

At least a binder resin, a colorant, a toner for electrostatic image development containing toner particles composed of a charge control agent and a release agent,
The volume mode diameter (a) of the toner particles is 5 to 10 μm, and the ratio (Dv / Dp) of the volume average particle diameter (Dv) to the number average particle diameter (Dp) is 1.0 to 1.3. Has an average circularity of 0.97 to 0.995,
The standard deviation (b) of the particle diameter of the toner particles is 2 μm or less, the average circularity (C1) of the toner particles having a particle diameter of (a−2b) μm or more and less than a μm, A ratio (C1 / C2) of the average circularity (C2) of the toner particles having a particle diameter to 1.00 to 1.02,
A toner for developing an electrostatic image, wherein the content of an n-hexane extraction component is 1 to 15% by weight and the content of a methanol extraction component is 5% by weight or less. The toner for developing electrostatic images according to claim 1, wherein the release agent has a weight average molecular weight of 1,000 to 3,000. The toner according to claim 1, wherein the release agent has a melting point of 40 to 100 ° C. 4. The electrostatic image developing toner according to any one of claims 1 to 3, wherein the release agent has a hydroxyl value of 0 to 5 mgKOH / g.