JP4385507B2 - Toner for electrostatic latent image development - Google Patents

Description

により算出される値の平均値であり、「粒子の投影面積に等しい円の周囲長」および「粒子投影像の周囲長」はフロー式粒子像分析装置（FPIA-1000またはFPIA-2000；東亜医用電子株式会社製）を用いて水分散系で測定を行って得られる値をもって示している。1に近いほど、真円に近いことを示している。このように平均円形度は、「粒子の投影面積に等しい円の周囲長」および「粒子投影像の周囲長」から求められるため、当該値はトナー粒子の形状、すなわち粒子表面の凹凸状態を正確に反映する指標となる。また、平均円形度はトナー粒子3000個の平均値として得られる値であるため、本発明における平均円形度の信頼性は極めて高い。なお、本明細書中において、平均円形度は上記装置によって測定されなければならないというわけでなく、原理的に上式に基づいて求めることができる装置であればいかなる装置によって測定されてもよい。
【００５１】
本発明の第1のトナーにおいてトナー粒子は公知のいかなるトナー粒子であってよく、通常、少なくとも結着樹脂および着色剤を含んでなり、所望により荷電制御剤、離型剤（オフセット防止剤）、磁性粉等をさらに含む。
【００５２】
トナー粒子は公知の方法、例えば、粉砕法等の乾式法、または乳化分散法、乳化重合法または懸濁重合法等の湿式法等によって製造されてよく、製造容易性の観点から、粉砕法を用いて製造されることが好ましい。例えば、トナー粒子が粉砕法によって製造される場合、例えば、結着樹脂および着色剤、所望により荷電制御剤、離型剤（オフセット防止剤）、磁性粉を混合し、溶融混練し、冷却した後、粗粉砕および微粉砕し、分級してトナー粒子を得る。トナー粒子の体積平均粒径は3〜8.5μm、好ましくは4〜7μmであることが望ましい。それより大きい場合、ハーフトーン画像のキメ感や細線再現性が悪化するため好ましくなく、またそれより小さい場合はトナーの粉体ハンドリング性が著しく悪化し、また、トナーが粉体のまま機外に放出された場合の人体への影響が懸念されるため好ましくない。
【００５３】
トナー粒子を構成する結着樹脂としては、静電潜像現像用トナーの分野で使用される熱可塑性の公知の合成樹脂および天然樹脂を用いることができる。例えば、スチレン系樹脂、アクリル系樹脂、オレフィン系樹脂、ジエン系樹脂、ポリエステル系樹脂、ポリアミド系樹脂、エポキシ系樹脂、シリコーン系樹脂、フェノール系樹脂、石油樹脂、ウレタン系樹脂等の合成樹脂および天然樹脂が挙げられる。本発明においては、ガラス転移温度が50〜75℃、軟化点が80〜160℃、数平均分子量が1000〜30000および重量平均分子量／数平均分子量が2〜100である樹脂を用いることが好ましい。
【００５４】
特に、フルカラートナー（黒トナーを含む）を目的とするときは、ガラス転移点50〜75℃、軟化点80〜120℃、数平均分子量2000〜30000および重量平均分子量／数平均分子量が2〜20である樹脂を使用するのがよい。また、モノクロ用トナーまたは磁性トナーを目的とするときは、ガラス転移点50〜75℃および軟化点80〜125℃の第1樹脂と、ガラス転移点50〜75℃および軟化点125〜160℃の第2樹脂とからなる結着樹脂を使用するのがよい。
【００５５】
トナー結着樹脂としては、より好ましくは、上記特性を有し、酸価が2〜50KOHmg/g、好ましくは3〜30KOHmg/gのポリエステル系樹脂を使用する。このような酸価を有するポリエステル系樹脂を用いることによって、カーボンブラックを含む各種顔料や荷電制御剤の分散性を向上させるとともに、十分な帯電量を有するトナーとすることができる。
【００５６】
着色剤としては、公知の顔料及び染料が使用される。例えば、各種カーボンブラック、活性炭、チタンブラック、アニリンブルー、カルコイルブルー、クロムイエロー、ウルトラマリンブルー、デュポンオイルレッド、キノリンイエロー、メチレンブルークロリド、銅フタロシアニン、マラカイトグリーンオキサレート、ランプブラック、ローズベンガル、C.I.ピグメント・レッド48:1、C.I.ピグメント・レッド122、C.I.ピグメント・レッド57:1、C.I.ピグメント・レッド184、C.I.ピグメント・イエロー97、C.I.ピグメント・イエロー12、C.I.ピグメント・イエロー17、C.I.ソルベント・イエロー162、C.I.ピグメント・イエロー180、C.I.ピグメント・イエロー185、C.I.ピグメント・ブルー15:1、C.I.ピグメント・ブルー15:3等を挙げることができる。また、黒トナー粒子には、各種カーボンブラック、活性炭、チタンブラックに加えて、着色剤の一部または全部を磁性体と置き換えることができる。このような磁性体としては、例えば、フェライト、マグネタイト、鉄、ニッケル等、公知の磁性体微粒子が使用可能である。磁性粒子の平均粒径は製造時における分散性を得る意味において、好ましくは1μm以下、特に0.5μm以下が好ましい。
【００５７】
黒トナー粒子において着色剤の含有量は結着樹脂100重量部に対して3〜15重量部が好適である。カラートナー粒子（黒トナー粒子以外のフルカラートナー粒子）において着色剤の含有量は結着樹脂100重量部に対して2〜6重量部が好適である。カラートナー粒子において着色剤は、トナー粒子中での分散性向上の観点から、使用される結着樹脂と相溶性のよい樹脂、好ましくは使用される結着樹脂と予め溶融混練し、粉砕して得られるマスターバッチとして使用されることが好ましい。この場合においてマスターバッチの使用量は、当該マスターバッチ中の着色剤の含有量が上記範囲内であればよい。
【００５８】
磁性トナーとして用いる場合は、上記着色剤の一部または全部を磁性体と置き換えてもよい。このような磁性体としては、黒トナー粒子の説明で例示した公知の磁性体微粒子が使用可能である。磁性体は結着樹脂100重量部に対して20〜60重量部添加するとよい。
【００５９】
帯電制御剤としては、特に制限されず、例えば、フッ素系界面活性剤、サリチル酸金属錯体、アゾ系金属化合物のような含金属染料、マレイン酸を単量体成分として含む共重合体の如き高分子酸、第４級アンモニウム塩、ニグロシン等のアジン系染料、カーボンブラック等を添加することができる。
【００６０】
さらに、耐オフセット性等の特性を向上させるために離型剤としてワックスを含有させてもよい。このようなワックスとしてはポリオレフィン系ワックス、カルナバワックス、ライスワックス、サゾールワックス、モンタン系エステルワックス、フィッシャートロプシュワックス等を挙げることができ、好ましくはポリオレフィン系ワックスを用いる。このようにトナーにワックスを含有させる場合、その含有量は特に制限されないが、結着樹脂100重量部に対して0.5〜5重量部とすることがフィルミング等の問題を生じることなく添加による効果を得る上で好ましい。離型剤は2種以上組み合わせて用いてもよく、その場合においてはそれらの合計量が上記範囲内であればよい。
【００６１】
ポリオレフィン系ワックスとしては、例えば、酸化型ポリプロピレンワックス、酸化型ポリエチレンワックス、ポリプロピレンワックス、ポリエチレンワックス等が挙げられる。結着樹脂としてポリエステル樹脂を用いる場合においては、酸化型ポリプロピレンワックスを使用することが、ワックスの分散性の観点から特に好ましい。
【００６２】
ポリオレフィン系ワックス、特に低分子量ポリプロピレンワックスを用いる場合は、トナーの流動性のさらなる向上の観点から、カルボン酸または酸無水物で変性したものを用いることが好ましい。特に、低分子量ポリプロピレンをアクリル酸、メタクリル酸、マレイン酸および無水マレイン酸からなる群から選択される1種以上の酸モノマーで変性した変性ポリプロピレンが好適に使用される。変性ポリプロピレンは、例えば、ポリプロピレンに、上記1種以上の酸モノマーを過酸化物触媒存在下もしくは無触媒下でグラフトあるいは付加反応させることにより得ることができる。変性ポリプロピレンは酸価が0.5〜30KOHmg/g、好ましくは1〜20KOHmg/gであることが好ましい。
【００６３】
変性ポリプロピレンワックスとして市販されているものでは、例えば、三洋化成工業社製のビスコール100TS（軟化点140℃，酸価3.5）、ビスコール110TS（軟化点140℃，酸価3.5）等が使用できる。
【００６４】
以上のようにして得られる本発明の第1のトナーは、フルカラー画像形成方法、好ましくは像担持体上に形成されたトナー像の中間転写体上への押圧転写を各色毎に重ねて行った後、中間転写体上に転写されたトナー像を記録部材上に押圧転写することを含むフルカラー画像形成方法において有効に使用され得る。すなわち、本発明の上記第1のトナーを用いたフルカラー画像形成方法においては１次および２次転写時におけるトナー画像の中抜けやキャリアおよび感光体への無機微粒子のスペントが長期にわたって抑制されるため、BSやカブリ等のノイズがない転写性に優れた高画質フルカラー画像を長期にわたって得ることができる。特に、１成分現像方式を適用した場合にはトナー担持体上でのトナー選別（特定の形状または粒径のトナーが消費される現象)が発生せず、長期的に渡って安定した画像が得られる。さらに瞬間的加熱処理をほどこして得られた第1のトナーはトナー形状がそろっており、表面平滑性が高いため、ストレスに対して強く、無機微粒子の埋没およびトナーの割れによる微粉発生が低減され得る。
【００６５】
本発明はまた、少なくとも結着樹脂および着色剤を含むトナー粒子に無機微粒子を外添してなり、無機微粒子の付着強度分布において強付着ピークと弱付着ピークの2つのピークを有する静電潜像現像用トナーであって、2種類以上の無機微粒子がトナー粒子に強付着している第2のトナーにも関する。
【００６６】
第2のトナーは、無機微粒子の添加量および付着強度比率が制限されることなく、2種類以上の無機微粒子がトナー粒子に強付着していること以外、第1のトナーと同様である。第2のトナーにおいて弱付着している無機微粒子は、2種類以上の無機微粒子がトナー粒子に強付着している限り特に制限されず、強付着している上記2種類以上の無機微粒子の一部または全部と同一であってもよいし、異なっていてもよい。2種類以上の無機微粒子とは材料の種類が異なる2種類以上の無機微粒子を意味する。
【００６７】
このような構成とすることによって、優れたトナーの帯電安定性および帯電環境特性が得られる。すなわち、長期使用や環境変動によるトナー帯電量の変動を抑制し、特に高温高湿環境下または低温低湿環境下で使用した場合の画像濃度の低下を防止することができる。1種類の無機微粒子を単独でトナー粒子に強付着させても、帯電安定性および帯電環境特性の向上効果は得られない。
【００６８】
詳しくは、強付着される無機微粒子として、公知の無機微粒子から選択される2種類以上の無機微粒子を用い、好ましくは少なくともシリカを含む2種類以上の無機微粒子を用いる。さらに好ましくは、シリカ、チタニアおよびアルミナからなる群から選択され、少なくともシリカを含む2種類以上の無機微粒子を用いる。一般に、強付着される無機微粒子の組み合わせとしては、シリカとチタニア、またはシリカとアルミナの組み合わせが好ましい。
弱付着される無機微粒子は、強付着される無機微粒子から独立して選択され、詳しくは、公知の無機微粒子から選択される1種類以上の無機微粒子を用い、好ましくはシリカ、チタニアおよびアルミナからなる群から選択される1種類以上の無機微粒子を用いる。
強付着される無機微粒子および弱付着される無機微粒子は、第1のトナーにおける無機微粒子と同様に、疎水化剤によって表面処理されていることが好ましい。
【００６９】
第2のトナーの製造方法としては、強付着されるべき無機微粒子を2種類以上用いること以外、上記の第1のトナーの製造方法とほぼ同様である。
【００７０】
第2のトナーにおける強付着されるべき無機微粒子および弱付着されるべき無機微粒子の添加量および平均1次粒径、ならびに付着強度比率は特に制限されないが、それぞれ第1のトナーにおいてと同様であることが好ましい。
【００７１】
本発明においては、上記第2の発明（第2のトナー）を第1のトナーに適用することによって、第1のトナーにおける効果と第2のトナーにおける効果を同時に得ることができる。すなわち、第1のトナーにおいて、強付着される無機微粒子として、公知の無機微粒子から選択される2種類以上の無機微粒子を用い、好ましくは少なくともシリカを含む2種類以上の無機微粒子を用いる。さらに好ましくは、シリカ、チタニアおよびアルミナからなる群から選択され、少なくともシリカを含む2種類以上の無機微粒子を用いる。一般に、強付着される無機微粒子の組み合わせとしては、シリカとチタニア、またはシリカとアルミナの組み合わせが好ましい。第1のトナーにおいて強付着される無機微粒子を上記のように選択することによって、キャリアや感光体への無機微粒子のスペントを抑制し、優れた流動性を長期にわたって維持する、帯電安定性および帯電環境特性に優れたトナーを得ることができる。
【００７２】
このとき、弱付着される無機微粒子は、強付着される無機微粒子から独立して選択され、詳しくは、公知の無機微粒子から選択される1種類以上の無機微粒子を用い、好ましくはシリカ、チタニアおよびアルミナからなる群から選択される1種類以上の無機微粒子を用いる。強付着される無機微粒子および弱付着される無機微粒子は、第1のトナーにおける無機微粒子と同様に、疎水化剤によって表面処理されていることが好ましい。
【００７３】
このようなトナーは、強付着される無機微粒子および弱付着される無機微粒子として上記のような材料を用いること以外、第1のトナーと同様である。製造方法としては、強付着されるべき無機微粒子を2種類以上用いること以外、上記の第1のトナーの製造方法と同様である。
【００７４】
【実施例】
（ポリエステル樹脂Aの製造）
2リットルの4つ口フラスコに還流冷却器、水分離装置、窒素ガス導入管、温度計、攪拌装置を取り付け、マントルヒーター中に設置し、ビスフェノールA-エチレンオキサイド付加物、ビスフェノールA-プロピレンオキサイド付加物、テレフタル酸およびフマル酸を、モル比（ビスフェノールA-エチレンオキサイド付加物：ビスフェノールA-プロピレンオキサイド付加物：テレフタル酸：フマル酸）が5：5：4：5となるように仕込み、フラスコ内に窒素を導入しながら加熱・攪拌して反応させた。酸価を測定しながら反応の進行を追跡し、所定の酸価に達した時点で反応を終了し、数平均分子量Mnが4800、重量平均分子量Mwと数平均分子量Mnとの比Mw/Mnが3.9、ガラス転移温度が61℃、軟化温度が102℃のポリエステル樹脂Aを得た。
【００７５】
（使用する外添剤）
・シリカA；シリカ#130(粒径15nm)をヘキサメチレンジシラザン（HMDS）で表面処理したもの（疎水化度65％）
・シリカB；シリカ#90(粒径30nm)をHMDSで表面処理したもの（疎水化度70％）
・シリカC；OX50(粒径30〜100nm、アエロジル社製)をHMDSで表面処理したもの（疎水化度70％）
・チタニアA;粒径30nmのアナターゼ型チタニア粒子をイソブチルトリメトキシシランで表面処理したもの（疎水化度65％）
・チタニアB;粒径50nmのアナターゼ型チタニア粒子をイソブチルトリメトキシシランで表面処理したもの（疎水化度65％）
・チタニアC;粒径70nmのアナターゼ型チタニア粒子をイソブチルトリメトキシシランで表面処理したもの（疎水化度60％）
・アルミナA；粒径20nmのアルミナをイソブチルトリメトキシシランで表面処理したもの（疎水化度55％）
・アルミナB；粒径60nmのアルミナをイソブチルトリメトキシシランで表面処理したもの（疎水化度60％）
・アルミナC；粒径100nmのアルミナをイソブチルトリメトキシシランで表面処理したもの（疎水化度60％）
【００７６】
（熱処理および混合処理の条件）
・条件1（熱処理）；最高温度；200℃、滞留時間；0.5秒、粉体分散濃度；100g/m³、冷却風温度；18℃、冷却水温度10℃。
・条件2（混合処理）；周速40m/s、混合時間3分、ST/Ao羽根。
・条件3（混合処理）；周速20m/s、混合時間1分、ST/Ao羽根。
・条件4（混合処理）；周速40m/s、混合時間6分、ST/Ao羽根。
【００７７】
（トナー母粒子の製造）
ポリエステル樹脂Ａ（Tg：61℃、Tm：102℃）70重量部およびマゼンタ顔料(C.I.ピグメントレッド184）30重量部を加圧ニーダーに仕込み混練した。得られた混練物を冷却後、フェザーミルにより粉砕し顔料マスターバッチを得た。
ポリエステル樹脂A93重量部、上記顔料マスターバッチ10重量部、サリチル酸亜鉛金属錯体(E84；オリエント化学工業社製)2重量部、酸化型低分子ポリプロピレン(ビスコール100TS；三洋化成工業社製)2重量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(PCM-30；池貝鉄工社製)の排出部ノズルの口径を大きくしたもので溶融混練し、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(IDS；日本ニューマチック工業社製)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体積平均粒径6.5μmのトナー母粒子を得た。
【００７８】
（実験例1）
熱処理工程
トナー母粒子100重量部にシリカB0.8重量部およびチタニアB0.8重量部を添加し、ヘンシェルミキサーで周速30m/sにて1分間混合した。混合物を図3に示す表面改質装置(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)により条件1にて熱処理した。
混合処理工程
得られた混合物にシリカB0.4重量部およびチタニアB0.4重量部を添加し、仕込量約1kg、9Lヘンシェルミキサーにより条件2にて混合処理した。
篩工程
得られた混合物を円形振動篩器(目開き77μm)にてふるってトナーを得た。
【００７９】
（実施例1〜4、実験例1〜16および参考例1〜9）
熱処理工程および混合処理工程で添加される外添剤の種類および添加量ならびに処理条件を表1〜3に示すように変更したこと以外、実験例1と同様にしてトナーを得た。
なお、参考例4においては混合処理工程を行わず、熱処理工程で得られた混合物をそのまま篩工程に供した。
また、参考例5においては熱処理工程の代わりに混合処理工程を行った。すなわち熱処理工程を行わず、トナー母粒子100重量部をそのまま混合処理工程に供し、得られた混合物をさらに混合処理工程に供した。
また、参考例6においては熱処理工程を行わず、トナー母粒子100重量部をそのまま混合処理工程に供した。
【００８０】
（評価項目）
・付着強度分布
トナー4gを、容量100mlのビーカ中で、ポリオキシエチルフェニルエーテルの0.2%水溶液に濡れさせたものを10セット用意した。各容器の溶媒中に沈降しているトナーを攪拌棒による手攪拌で10〜20回程度かき上げたのち、ただちに超音波式ホモジナイザーUS-1200T(日本精機社製；仕様周波数15kHz)にて、超音波エネルギーを本体装置に付属の振動指示値を示す電流計の値が60μA(50w)を示すように調整しながら各容器ごとに30秒、60秒、90秒、・・・、270秒、300秒の水準で付与し、トナーから溶媒中に外添剤を離脱させた。その後、デカンテーションによりトナー粒子を沈降させ、離脱外添剤が含まれる上澄み溶液を除去し、純水を60ml加えてトナーを手攪拌して洗浄し、目開き1μmのメンブランフィルターをセットした吸引ろ過器により、洗浄液を除去した。この洗浄を再度繰り返した後得られたトナーを真空乾燥器にて乾燥させて超音波付与により離脱した外添剤を除去した乾燥トナーを得た。
【００８１】
これらのトナーと超音波を付与していないトナーを蛍光Ｘ線分析に供し、超音波付与後のトナーに残留する外添剤の量（X）および超音波付与前のトナーに付着していた外添剤の量（Y）を定量することによって、外添剤の離脱量を下式に基づいて求めた。なお、上記XおよびYは、トナーを焙焼することによって得られる残渣の量を測定することによっても得ることができる。
外添剤離脱量（重量％）＝（Y−X）/Y
【００８２】
超音波時間と外添剤離脱量の関係をヒストグラム化して付着強度分布グラフを得た。例えば、実験例1のトナーについての付着強度分布グラフを図1に示した。上記グラフから、ピークを示す超音波時間を読み取り、超音波時間150秒以下で現れるピークを弱付着ピーク、超音波時間が150秒を越えて現れるピークを強付着ピークとした。
【００８３】
また、上記グラフから付着強度比率（％）を求めた。詳しくは、「強付着ピークの山を構成する外添剤離脱量の和」に対する「弱付着ピークの山を構成する外添剤離脱量の和」の割合を求めた。なお、弱付着ピークの山と強付着ピークの山との間の谷に相当するチャンネルの外添剤離脱量はいずれの和にも加算されていない。
【００８４】
・円形度
フロー式粒子像分析装置（FPIA-1000またはFPIA-2000；東亜医用電子株式会社製）を用いて水分散系で測定を行って得られる値をもって示している。
・流動性
パウダーテスターで測定されるAD値により評価した。
×；AD値は0.30未満であった；
△；AD値は0.30以上0.35未満であった；
○；AD値は0.35以上0.40未満であった；
◎；AD値は0.40以上0.45未満であった。
【００８５】
各トナーと後述のキャリアをトナー濃度6%で混合して現像剤、フルカラーコピー機（CF910；ミノルタ社製）およびCFペーパを用いて以下の評価を行った。
・キャリア劣化
上記マシンにて３万枚耐久試験後の現像剤からトナーを電解分離し、キャリアのみを得る。そのキャリアをトナー種を固定して帯電量測定し、Newキャリアが有する帯電レベル（Q/M）と耐久後キャリアが有する帯電レベル（Q/M）を測定して、耐久後キャリアの荷電能力を下式に基づいて算出した。
荷電能力＝(耐久後キャリアのQ/M)/(NewキャリアのQ/M)×100
◎；荷電能力が90%以上であった；
○；荷電能力が80%以上であった；
△；荷電能力が70%以上であった；
×；荷電能力が70%未満であった。
【００８６】
・BS（ブラックスポット）
上記マシンにて３万枚耐久試験後の感光体を観察し、外添剤の固着物(BS)の状態を評価した。
◎；全く固着がなかった；
○；わずかに固着が認められたが印字画像には認められなかった；
△；固着はあるが実用上問題とはならなかった；
×；固着により実用上問題となる画像ノイズ(BS)が発生した。
【００８７】
・中抜け
上記マシンにて３万枚耐久試験後、電子写真学会チャートをコピーし、文字画像の中抜け状態を観察した。
◎；中抜けが全く発生しなかった；
○；肉眼では判別不能の中抜けが一部の文字で認められたが、実用上全く問題なかった；
△；中抜けがわずかに発生しているのが肉眼で確認できるが、実用上問題なかった；
×；明らかに文字品位に影響するレベルの中抜けが発生している。
【００８８】
・トナー付着量
LL環境（10℃、20％）下およびHH環境（40℃、80％）下で上記マシンにて３万枚耐久試験後、ベタ画像をコピーし、任意の5点のトナー付着量を測定した。極端に帯電が高すぎたり、低すぎたりした場合、LL環境やHH環境において付着量が低くなる。各環境下で評価を行い、悪い方の結果を表に示した。
○；付着量平均値が5g/m²以上であった；
△；付着量平均値が3.5g/m²以上5g/m²未満であり、実用上問題なかった；
×；付着量平均値が3.5g/m²未満であり、実用上問題があった。
【００８９】
・帯電環境特性
LL環境（10℃、20％）下およびHH環境（40℃、80％）下で1日間以上保存した現像剤の帯電量を測定した。測定値を以下のランク付けに従って評価した。LL環境で保存された現像剤の帯電量およびHH環境で保存された現像剤の帯電量の評価結果のうち悪い方の結果を当該トナーの結果とする。
○；45μC/g≦帯電量≦55μC/g；
△；35μC/g＜帯電量＜45μC/gまたは55μC/g＜帯電量＜65μC/g；
×；帯電量≦35μC/gまたは65μC/g≦帯電量。
【００９０】
【表１】

【００９１】
【表２】

【００９２】
【表３】

【００９３】
（キャリアの製造）
攪拌器、コンデンサー、温度計、窒素導入管、滴下装置を備えた容量500mlのフラスコにメチルエチルケトンを100重量部仕込んだ。窒素雰囲気下80℃で、メチルメタクリレート36.7重量部、2-ヒドロキシエチルメタクリレート5.1重量部、3-メタクリロキシプロピルトリス(トリメチルシロキシ)シラン58.2重量部および1,1'-アゾビス(シクロヘキサン-1-カルボニトリル)1重量部をメチルエチルケトン100重量部に溶解させて得られた溶液を2時間にわたり反応器中に滴下し、5時間熟成させた。
得られた樹脂に対して、架橋剤としてイソホロンジイソシアネート／トリメチロールプロパンアダクト(IPDI/TMP系：NCO%＝6.1%)をOH/NCOモル比率が1/1となるように調整した後、メチルエチルケトンで希釈して固形比3重量％であるコート樹脂溶液を調製した。
コア材として焼成フェライト粉F-300(体積平均粒径：50μm、パウダーテック社製)を用い、上記コート樹脂溶液をコア材に対する被覆樹脂量が1.5重量％になるようにスピラコーター(岡田精工社製)により塗布・乾燥した。
得られたキャリアを熱風循環式オーブン中にて160℃で1時間放置して焼成した。冷却後フェライト粉バルクを目開き106μmと75μmのスクリーンメッシュを取り付けたフルイ振とう器を用いて解砕し、樹脂被覆キャリアを得た。
【００９４】
【発明の効果】
本発明のトナーは、キャリアや感光体への無機微粒子のスペントが抑制され、かつ優れた流動性を長期にわたって維持することができる。また、強付着させる無機微粒子を選択することによって、優れた帯電安定性および帯電環境特性を得ることができる。
【図面の簡単な説明】
【図１】 本発明のトナーについての無機微粒子の付着強度分布を示す。
【図２】 （ａ）および（ｂ）はともに、従来のトナーについての無機微粒子の付着強度分布を示す。
【図３】 瞬間的加熱処理を行うための装置の概略構成図を示す。
【図４】 図3の装置における試料粉砕室を水平方向に切ったときの概略断面図を示す。
【符号の説明】
101；熱風発生装置、102；導入管、103；試料噴射ノズル。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic latent image developing toner for developing an electrostatic latent image formed on an electrostatic latent image carrier.
[0002]
[Prior art]
In recent years, attempts have been actively made to improve the fluidity and chargeability of toner. The most well-known means for improving the fluidity of the toner is to use inorganic fine particles such as hydrophobic silica or hydrophobic titania having an average primary particle size of 10 to 30 nm as toner particles. Externally adding the fine particles to the toner particle surface. However, there is a problem that the fluidizing agent is detached from the toner particles and transferred (spent) to the carrier or the photoreceptor. In particular, color toners that require significantly higher fluidity than monochrome toners from the standpoint of developability and image quality have a configuration in which a large amount of the above-described fluidizing agent is added, and thus the above-described adverse effects are remarkable. . That is, when the fluidizing agent is transferred to the carrier, the charging ability of the carrier is reduced (carrier deterioration), and the toner cannot be charged to a desired level. Further, when the fluidizing agent moves to the photoreceptor, the fluidizing agent adheres and accumulates in the cleaning portion and transfer portion of the photoreceptor, and defects (black spots; BS, etc.) are generated in the obtained image. As described above, the fluidizing agent has a high fluidity-imparting effect, but it tends to cause a problem of spent on the carrier and the photoconductor (detachment from the toner particles), and this conflict item can be solved at the same time by extending the conventional technology. Was difficult.
[0003]
Therefore, a toner having a structure in which the fluidizing agent is strongly adhered to the surface of the toner particles so that the fluidizing agent is not detached from the toner particles is known. There have been problems such as poor developability and voids during transfer.
[0004]
In addition, it is known that the chargeability of toner is adjusted by using inorganic fine particles to improve the chargeability. For example, silica is generally used as the charge level adjusting means to increase the negative charge level, and metal oxides such as titania and alumina are used to suppress fluctuations in the charge amount due to environmental fluctuations. Further, these combined compositions are generally used as means for arbitrarily controlling the charge level. In addition, in order to stably obtain good chargeability over a long period of time, a technique that suppresses the transfer of fine particles to the carrier by strongly attaching inorganic fine particles to the surface of the toner particles (in contrast to the purpose of toner) There has been proposed a technique in which polar chargeability fine particles are added to a toner so that the chargeability of the carrier does not decrease even when transferred to the carrier. However, a toner added with a large amount of an external additive such as a full-color toner has not been sufficiently charged for long-term use (charging stability) and charged for environmental fluctuations (charging environment characteristics). That is, there is a problem that the charge amount of the toner fluctuates due to long-term use or environmental fluctuation, and a desired image density cannot be obtained particularly when used in a high temperature and high humidity environment or a low temperature and low humidity environment.
[0005]
Regarding the adhesion state of the inorganic fine particles on the surface of the toner particles, various configurations have been proposed in addition to the configuration in which the inorganic fine particles are simply strongly adhered to the toner particle surface as described above. For example, in Japanese Patent Publication No. 2956247, it is described that one of two types of external additives can be attached to the surface in a semi-buried state and the other can be attached in a non-buried state to achieve both chargeability and environmental resistance. ing. Also, for example, in Japanese Patent Laid-Open Nos. 11-24301, 6-282097, 7-199519, 8-15899, and 9-146293, ultrasonic waves at a level that is in toner are used. Proposals have been made to achieve both the fluidity and chargeability of the toner, filming due to the external additive, etc., by regulating the amount of external additive removed and the amount of external additive added when energy is applied. The external additive adhesion state control means for achieving these configurations can be achieved by optimizing the rotational speed of a mixing device having rotating blades such as a conventionally known Henschel mixer and parameter conditions related to the blades. ing.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides a toner for developing an electrostatic latent image that suppresses spent fine inorganic particles on a carrier or a photoreceptor and maintains excellent fluidity over a long period of time. The first purpose.
[0007]
The second object of the present invention is to provide a toner for developing an electrostatic latent image having excellent charging stability and charging environment characteristics.
[0008]
[Means for Solving the Problems]
In the present invention, inorganic particles are externally added to toner particles containing at least a binder resin and a colorant in an amount of 1.3 parts by weight or more with respect to 100 parts by weight of the toner particles. A toner for developing an electrostatic latent image having two peaks, an “inorganic that constitutes a peak of weak adhesion peak” relative to “the sum of the amount of inorganic fine particles that constitute a peak of strong adhesion peak” in the adhesion strength distribution The present invention relates to a toner for developing an electrostatic latent image, characterized in that a ratio (adhesion strength ratio) of “the sum of fine particle separation amounts” is 10 to 100%. The first object is achieved by the toner.
[0009]
The present invention also includes an electrostatic latent image obtained by externally adding inorganic fine particles to toner particles containing at least a binder resin and a colorant, and having two peaks of a strong adhesion peak and a weak adhesion peak in the adhesion strength distribution of the inorganic fine particles. The present invention relates to a developing toner, which is an electrostatic latent image developing toner in which two or more kinds of inorganic fine particles are strongly adhered to the toner particles. The second object is achieved by the toner.
[0010]
The inventors of the present invention pay attention to the adhesion state of inorganic fine particles and have two peaks, a strong adhesion peak and a weak adhesion peak, in the inorganic fine particle adhesion strength distribution in which the inorganic fine particle adhesion strength is quantified. In this case, it has been found that a high fluidity-imparting effect can be obtained without causing problems due to spent inorganic fine particles on the carrier and photoreceptor.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
First, the first toner that achieves the first object will be described.
The first toner of the present invention is obtained by externally adding inorganic fine particles to toner particles, and has two peaks, a strong adhesion peak and a weak adhesion peak, in the adhesion strength distribution of the inorganic fine particles. In the present specification, external addition means that the material is added to the toner particles so that the added material adheres to the surface (external) of the toner particles.
[0012]
The adhesion strength distribution is a distribution that quantitatively represents the relative adhesion strength of inorganic fine particles (hereinafter also simply referred to as “external additive”) that are externally added and adhered to the toner particle surface, that is, the toner particle surface. A distribution in which the amount of inorganic fine particles adhering to the surface is expressed by adhesion strength. In this specification, as such an adhesion strength distribution, after dispersing 4 g of toner in 40 ml of a surfactant, the toner particles obtained when ultrasonic energy having a frequency of 15 kHz / output of 60 w is applied every 30 seconds. Although a graph created by creating a histogram of the amount of separated inorganic fine particles according to ultrasonic wave application time is used (hereinafter referred to as an ultrasonic method), it does not have to be created by the above method. In addition, any method may be used as long as an adhesion strength distribution measured by energy corresponding to the ultrasonic energy of the above method is obtained.
[0013]
In addition, the adhesion strength distribution has two peaks, a strong adhesion peak and a weak adhesion peak. In the distribution in which the amount of inorganic fine particles adhering to the toner particle surface is represented by the adhesion strength, the inorganic fine particles having a specific adhesion strength are used. Means that there are two portions where the amount of inorganic particles is larger than the amount of inorganic fine particles of the adhesion strength before and after that. In other words, from the viewpoint of adhesion strength, it is roughly divided and adheres to the toner particles with a relatively large adhesion strength. It means that there are inorganic fine particles and inorganic fine particles adhering to the toner particles with a relatively small adhesion strength. In the present invention, the strongly adhering inorganic fine particles coat the toner particle surface relatively firmly and uniformly, and are not easily peeled off by mechanical stress (that is, are not easily released). It is considered that excellent fluidity can be maintained for a long time while suppressing the inorganic fine particle spent. In the present specification, of the two peaks in the adhesion strength distribution, a peak that exists with a relatively large adhesion strength is called a strong adhesion peak, and a peak that exists with a relatively small adhesion strength is called a weak adhesion peak.
[0014]
Specifically, the adhesion strength distribution is, for example, a graph as shown in FIG. The graph of FIG. 1 is an adhesion strength distribution of an example of the first toner prepared by the ultrasonic method, and the toner has a strong adhesion peak at an ultrasonic application time of 210 seconds and an ultrasonic application time of 90 seconds. It turns out that it has a weak adhesion peak.
[0015]
The first toner has a weak adhesion peak in the ultrasonic application time of 30 to 150 seconds in the adhesion strength distribution created by the ultrasonic method from the viewpoint of further improving the fluidity and more effective prevention of spent fine particles of inorganic fine particles. It is preferable to have a strong adhesion peak at an ultrasonic wave application time of 150 to 300 seconds.
[0016]
If the toner has only one peak in the adhesion strength distribution by the ultrasonic method and the peak is present for 150 seconds or more of the ultrasonic wave application time, the fluidity imparting effect is low, the transferability is deteriorated and the transfer efficiency is deteriorated. This causes problems such as lowering and hollowing out. Even in this case, when the adhesion strength distribution is broad, the amount of free external additive becomes relatively large, and the problem of BS due to carrier deterioration due to spent or adhesion to the photoreceptor occurs. In addition, in the adhesion strength distribution by the ultrasonic method, when there is only one peak and the peak is present for less than 150 seconds of ultrasonic wave application, the amount of free external additive becomes relatively large, and carrier deterioration due to spent And BS problems due to sticking on the photoreceptor.
[0017]
In the first toner, in the adhesion strength distribution as described above, the ratio of “sum of the amount of inorganic fine particles constituting the peak of the weak adhesion peak” to “sum of the amount of inorganic fine particles constituting the peak of the strong adhesion peak” (Adhesion strength ratio) is 10 to 100%, and preferably from 10 to 50%, more preferably 10 from the viewpoint of further improving fluidity and preventing the accompanying voids and more effectively preventing inorganic fine particles spent. ~ 35%. In calculating the adhesion strength ratio, the amount of inorganic fine particles detached from the channel corresponding to the valley between the peak of the weak adhesion peak and the peak of the strong adhesion peak is not added to any sum, for example, as shown in FIG. The above-mentioned adhesion strength ratio in such an adhesion strength distribution is calculated as a ratio of the sum of the amount of inorganic fine particles detached at an ultrasonic wave application time of 30 to 120 seconds to the sum of the amount of inorganic fine particles detached at an ultrasonic wave application time of 180 to 300 seconds. . When the adhesion strength ratio is less than 10%, the problems of decrease in fluidity and deterioration in transferability become remarkable. On the other hand, when the adhesion strength ratio exceeds 100%, the influence of the free external additive becomes large, that is, the problem of carrier contamination and BS becomes remarkable.
[0018]
Hereinafter, the first toner will be described in detail together with its manufacturing method.
The first toner can be effectively produced by the following two-stage process. First, inorganic fine particles are added to the toner particles and mixed, and then the inorganic fine particles are fixed to the toner particle surfaces with thermal energy, thereby achieving strong adhesion of the inorganic fine particles to the toner particles and adhesion strength distribution. A strong adhesion peak at is obtained. Further, inorganic fine particles are further added to the obtained toner particles and mixed with a known mixing device to achieve weak adhesion of the inorganic fine particles to the toner particles, thereby obtaining a weak adhesion peak in the adhesion strength distribution. At this time, the peak of the strong adhesion peak in the distribution of adhesion strength is mainly composed of inorganic fine particles added before fixation by thermal energy (hereinafter, simply referred to as heat treatment), while the peak of the weak adhesion peak is mainly It is comprised by the inorganic fine particle added after heat processing.
[0019]
On the other hand, when inorganic fine particles are added to toner particles as in the past and simply mixed with a known rotary blade type mixing device such as a Henschel mixer, an adhesion strength distribution having a weak adhesion peak and a strong adhesion peak is obtained. Thus, a broad adhesion strength distribution having only weak adhesion peaks is obtained. In addition, when mixing under relatively strong conditions with a known rotary blade type mixing device such as a Henschel mixer, the inorganic fine particles may be completely buried in the toner particles or free floating. As shown in FIG. 2 (a), a broad adhesion strength distribution having only a strong adhesion peak is obtained. Even if inorganic fine particles are added and mixed in two stages, an adhesion strength distribution having a weak adhesion peak and a strong adhesion peak cannot be obtained. As shown in FIG. It has a broad adhesion strength distribution. Thus, when a known rotary blade mixing device such as a Henschel mixer is used alone, only a broad adhesion strength distribution can be obtained, and an adhesion strength distribution having a weak adhesion peak and a strong adhesion peak cannot be obtained.
[0020]
The kind of inorganic fine particles added before and after the heat treatment is not particularly limited, and known inorganic fine particles used for improving the fluidity of the toner in the field of electrostatic latent image developing toner can be used. From the viewpoint of more effectively improving the fluidity, it is preferable to use inorganic fine particles having an average primary particle size of 10 to 100 nm, more preferably silica having an average primary particle size of 10 to 100 nm, and an average primary particle size. One or more inorganic fine particles selected from the group consisting of titania having a diameter of 20 to 100 nm and alumina having an average primary particle diameter of 20 to 100 nm are used. The inorganic fine particles added before the heat treatment and the inorganic fine particles added after the heat treatment may be independently selected.
[0021]
As the silica with an average primary particle size of 10 to 100 nm, for example, equivalent to # 300, # 200, # 130, # 90, # 70, # 50 in grades of specific surface area commercially available from Nippon Aerosil Co., Ltd. and Clariant Japan Co., Ltd. Silica and OX50 (manufactured by Nippon Aerosil Co., Ltd.) are preferably used.
In addition, as the titania having an average primary particle size of 20 to 100 nm, for example, the specific surface area commercially available from Teika's MT series, Titanium Industry's ST series, Ishihara Sangyo's TTO series, etc. is 30 to 150 m. ² / g titanium oxide particles are preferably used.
As the alumina having an average primary particle size of 20 to 100 nm, for example, a commercially available AKP-G series (manufactured by Sumitomo Chemical Co., Ltd.) or oxide C (manufactured by Degussa) is preferably used.
[0022]
The inorganic fine particles are preferably surface-treated with a hydrophobizing agent from the viewpoint of maintaining good fluidity even after long-term use and environmental fluctuations. As the hydrophobizing agent, silane coupling agents, titanate coupling agents, silicone oils, silicone varnishes and the like can be used. Examples of silane coupling agents include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, methyltrimethoxysilane, methyltriethoxysilane, and isobutyl. Trimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-butyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, Vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, etc. A possible use, as the silicone oils, such as dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenyl polysiloxane can be used.
[0023]
In order to treat the surface of inorganic fine particles using a hydrophobizing agent, the following method can be employed. First, while forcibly stirring the inorganic fine particles with a blender or the like, a dilute solution obtained by mixing and diluting the hydrophobizing agent alone or with a solvent such as tetrahydrofuran (THF), toluene, ethyl acetate, methyl ethyl ketone or acetone. Add by dripping or spraying and mix well. Next, the obtained mixture is transferred to a vat or the like, placed in an oven, heated and dried. After that, the mixture is stirred again with a blender and sufficiently crushed. In such a method, two or more hydrophobizing agents may be used in combination. In addition to such a dry method, a wet treatment method in which inorganic fine particles are immersed in a solution in which a hydrophobizing agent is dissolved in an organic solvent, dried and crushed may be employed. For inorganic fine particles having low surface activity such as titania and alumina, it is preferable to use a surface treatment method using an alcohol solution of the hydrophobizing agent in an aqueous system.
[0024]
The inorganic fine particles are preferably heat-treated at 100 ° C. or higher before the surface treatment with the hydrophobizing agent. The amount of the hydrophobizing agent needs to be adjusted depending on the type of inorganic fine particles, but is 0.1 to 5% by weight, preferably 0.2 to 3% by weight based on the inorganic fine particles. If it is less than 0.1% by weight, there is no effect of hydrophobization, and if it is more than 5% by weight, many aggregates of inorganic fine particles are produced, and the original effects of inorganic fine particles such as improvement of developer fluidity are hindered.
[0025]
The degree of hydrophobicity of the inorganic fine particles is 40 to 100%, preferably 50 to 100%. In the present specification, the degree of hydrophobicity is a value measured by a methanol titration method (Aerosil standard method). Specifically, 0.2 g of sample is collected in a 100 ml beaker, and 50 ml of pure water is added. Methanol is added below the liquid level while electromagnetically stirring, and the degree of hydrophobicity is calculated from the amount of methanol required (X (ml)), with the end point being the point at which no sample is found on the liquid level.
Hydrophobicity (V / V%) = X / (50 + X) x 100
[0026]
The total addition amount of the inorganic fine particles added before the heat treatment and the inorganic fine particles added after the heat treatment in the first toner is 1.3 parts by weight or more, preferably 1.5 to 10 parts by weight, more preferably 100 parts by weight of the toner particles. 1.5-8 parts by weight. If the amount of the inorganic fine particles added is too small, the fluidity imparting effect is small, so that a void is generated, which is not preferable.
[0027]
The addition amount of the inorganic fine particles added before the heat treatment is such that the total amount with the addition amount of the inorganic fine particles added after the heat treatment is within the above range, and the adhesion strength ratio of the obtained toner is within the above range, Although not particularly limited, from the viewpoint of further improving fluidity in the obtained toner and more effective prevention of spent fine particles of inorganic fine particles, 0.1 to 8 parts by weight, preferably 0.8 to 5 parts by weight, based on 100 parts by weight of toner particles. The amount is preferably 1.0 to 3.0 parts by weight. As described above, two or more kinds of inorganic fine particles may be used as the inorganic fine particles added before the heat treatment, and in that case, the total amount thereof may be within the above range.
[0028]
The mixing before the heat treatment is not particularly limited, but is preferably performed under a relatively weak condition by a known mixing apparatus such as a Henschel mixer so that the inorganic fine particles are uniformly adhered to the toner particle surface with a relatively weak force. . This is because a uniform process can be performed in the fixing process using thermal energy, and inorganic fine particles can be uniformly and strongly adhered.
[0029]
The immobilization (heat treatment) by thermal energy will be described.
In the present invention, immobilization of inorganic fine particles by heat energy is achieved by instantaneous heat treatment. A preferable instantaneous heat treatment is achieved by spraying a mixture of toner particles and inorganic fine particles in hot air by using compressed air, whereby the toner particles are strongly adhered to the inorganic fine particles while being surface-modified by heat. A sharp strong adhesion peak in the adhesion strength distribution that could not be achieved with the method can be achieved. That is, the inorganic fine particles can be uniformly and strongly attached. Further, the surface of the toner particles is smoothed by heat, and the angular irregularly shaped toner becomes rounded, and an excellent effect of improving voids during transfer can be obtained by improving fluidity and aggregation.
[0030]
A schematic configuration diagram of an apparatus for performing a preferable instantaneous heat treatment will be described in more detail with reference to FIGS. 3 and 4. FIG. As shown in FIG. 3, the high-temperature and high-pressure air (hot air) prepared by the hot air generator 101 is jetted from the hot air jet nozzle 106 through the introduction tube 102. On the other hand, a mixture of toner particles 105 and inorganic fine particles mixed before the treatment (hereinafter simply referred to as toner particles) is conveyed from a quantitative supply device 104 by a predetermined amount of pressurized air through an introduction tube 102 ′, and the hot air jet The sample is injected into a sample injection chamber 107 provided around the nozzle 106.
[0031]
As shown in FIG. 4, the sample injection chamber 107 has a hollow donut shape, and a plurality of sample injection nozzles 103 are arranged at equal intervals on the inner wall thereof. The toner particles sent into the sample injection chamber 107 are diffused and uniformly dispersed in the injection chamber 107, and are subsequently injected into the hot air stream from the plurality of sample injection nozzles 103 by the pressure of the air that is sent in.
[0032]
Further, it is preferable to provide the sample injection nozzle 103 with a required inclination so that the jet flow of the sample injection nozzle 103 does not cross the hot air flow. Specifically, it is preferable that the toner jet flow is jetted so as to follow the hot air flow to some extent, and the angle formed between the toner jet flow and the flow direction of the central region of the hot air flow is 20 to 40 °, preferably 25 to 35 °. Is preferred. If it is wider than 40 °, the jetted toner flow will be jetted across the hot air flow, colliding with the toner particles jetted from other nozzles, causing the toner particles to agglomerate. If it is narrow, toner particles that are not taken into the hot air are generated, and the effect of the instantaneous heat treatment is small.
[0033]
Further, a plurality of sample injection nozzles 103 are necessary, and at least three or more and four or more are preferable. By using a plurality of sample jet nozzles, the toner particles can be uniformly dispersed in the hot air stream, and the heat treatment for each toner particle can be performed reliably. As a state of being ejected from the sample ejection nozzle, it is desirable that it is diffused widely at the time of ejection and is dispersed throughout the hot air stream without colliding with other toner particles.
[0034]
The toner particles ejected in this manner are instantaneously brought into contact with high-temperature hot air and subjected to a uniform heat treatment. That is, the toner particles are instantaneously melted by instantaneous contact with high-temperature hot air, and at the same time, the inorganic fine particles adhering to the particle surface are appropriately buried in the particles, and then cooled by subsequent cooling. As a result, toner particles to which inorganic fine particles adhere strongly are obtained. Here, “instantaneous” refers to a time during which necessary toner particle modification (heat treatment) is achieved and aggregation of the toner particles does not occur, depending on the processing temperature and the concentration of the toner particles in the hot air stream. Usually, it is 2 seconds or less, preferably 1 second or less. This instantaneous time is expressed as the residence time of the toner particles until the toner particles are ejected from the sample ejection nozzle and introduced into the introduction tube 102 ". When this residence time exceeds 2 seconds, coalesced particles are generated. It becomes easy.
[0035]
Next, the instantaneously heated toner particles are immediately cooled by the cold air introduced from the cooling air introduction unit 108, and collected by the cyclone 109 via the introduction tube 102 "without adhering to the apparatus wall or aggregating the particles. The product air is collected in the product tank 111. The carrier air after the toner particles are collected passes through the bag filter 112, and fine powder is removed, and then is discharged into the atmosphere through the blower 113. Is preferably provided with a cooling jacket through which cooling water flows to prevent aggregation of toner particles.
[0036]
Other important conditions for performing the instantaneous heat treatment are hot air flow rate, dispersed air flow rate, dispersion concentration, processing temperature, cooling air temperature, suction air flow rate, and cooling water temperature.
[0037]
The hot air volume is the volume of hot air supplied by the hot air generator 101. Increasing the amount of hot air is preferable in terms of improving the uniformity and processing capability of the heat treatment.
The dispersed air volume is an air volume that is sent into the introduction pipe 102 ′ by pressurized air. Although depending on other conditions, it is preferable that the amount of the dispersed air is suppressed and heat-treated for improving and stabilizing the dispersed state of the toner particles.
The dispersion concentration refers to the dispersion concentration of the toner particles in the heat treatment region, specifically, the nozzle discharge region. The preferred dispersion concentration depends on the specific gravity of the toner particles, and the value obtained by dividing the dispersion concentration by the specific gravity of each toner particle is 50 to 300 g / m. ^Three , Preferably 50-200 g / m ^Three It is preferable to treat with.
[0038]
The processing temperature refers to the temperature in the heat treatment region. In the heat treatment region, a temperature gradient actually exists from the center to the outside, but it is preferable to perform the treatment while reducing this temperature distribution. From the surface of the apparatus, it is preferable to supply the wind in a stabilized laminar flow state by a stabilizer or the like. For non-magnetic toner particles using a binder resin having a sharp molecular weight distribution, for example, a binder resin having a weight average molecular weight / number average molecular weight of 2 to 20, the glass transition point of the binder resin + 100 ° C. or higher It is preferable to treat in the peak temperature range of glass transition point + 300 ° C. More preferably, the treatment is performed in the peak temperature range of the glass transition point of the binder resin + 120 ° C. or more to the glass transition point + 250 ° C. The peak temperature range refers to the maximum temperature in the region where the toner is in contact with hot air.
[0039]
For non-magnetic toner particles using a binder resin having a relatively wide molecular weight distribution, for example, a binder resin having a weight average molecular weight / number average molecular weight of 30 to 100, the glass transition temperature of the binder resin +100 It is preferable to perform the treatment at a peak temperature range of from ℃ to glass transition temperature +300 ℃. More preferably, the treatment is performed in a peak temperature range of the glass transition temperature of the binder resin + 150 ° C. or higher to the glass transition temperature + 280 ° C. In order to achieve uniform and strong adhesion of inorganic fine particles to the toner particles (uniformity of the toner particle surface) and, if desired, uniform spheroidization of the toner particles, modification of the high molecular weight region of the binder resin is required. This is because it is necessary to set a higher processing temperature to achieve the above. However, if the processing temperature is set higher, coalesced particles are more likely to be generated. Therefore, the amount of inorganic fine particles added before the processing (inorganic fine particles strongly adhered to the toner particles) is increased within the above range. Tuning such as setting to a low dispersion concentration during processing is required.
[0040]
The cooling air temperature is the temperature of the cold air introduced from the cooling air introduction unit 108. After the instantaneous heat treatment, the toner particles are preferably returned to an atmosphere below the glass transition temperature by cooling air so as to be instantaneously cooled to a temperature range in which toner particles do not aggregate or coalesce excessively. Therefore, the cooling air is cooled at a temperature of 25 ° C. or lower, preferably 15 ° C. or lower, more preferably 10 ° C. or lower. However, if the temperature is lowered more than necessary, condensation may occur depending on the conditions, and conversely, side effects occur. In such an instantaneous heat treatment, since the time during which the toner particle surface is in a molten state is extremely short in combination with cooling with cooling water in the apparatus, which will be described later, the particles do not adhere to each other and to the wall of the heat treatment apparatus. As a result, the stability during continuous production is excellent, the frequency of cleaning the manufacturing apparatus can be extremely reduced, and the yield can be stably controlled at a high level.
[0041]
The suction air volume is air for conveying the toner particles processed by the blower 113. Increasing the suction air volume is preferable in terms of reducing the cohesiveness of the toner particles.
The cooling water temperature refers to the temperature of cooling water in the cooling jacket provided in the cyclones 109 and 114 and the introduction pipe 102 ″. The cooling water temperature is 25 ° C. or less, preferably 15 ° C. or less, more preferably, 10 ° C or less.
[0042]
In order to increase the degree of immobilization of the inorganic fine particles and achieve uniform strong adhesion, that is, a sharp strong adhesion peak in the adhesion strength distribution, it is preferable to further devise the following.
(1) The amount of toner particles supplied in the hot air stream is controlled to be constant so as not to generate pulsation or the like. For this purpose: (i) A plurality of types of table feeders, vibration feeders, etc. used at 115 in FIG. If it is possible to use a table feeder and a vibratory feeder with high accuracy, it is possible to connect the fine pulverization or classification process and supply the toner particles to the heat treatment process as it is; (ii) After supplying the toner particles with compressed air and before supplying them into the hot air, the toner particles are redispersed in the sample supply chamber 107 to improve uniformity. For example, a means such as re-dispersing with secondary air, providing a buffer unit to make the dispersed state of toner particles uniform, or re-dispersing with a coaxial double tube nozzle or the like is adopted.
[0043]
(2) To optimize and uniformly control the dispersion concentration of toner particles when sprayed into a hot air stream. For this purpose: (i) Supply into the hot air stream is performed uniformly and in a highly dispersed state from the entire circumferential direction. More specifically, when supplying from a dispersion nozzle, a nozzle having a stabilizer or the like is used to improve dispersion uniformity of toner particles dispersed from each nozzle; (ii) toner particles in a hot air stream In order to make the dispersion density uniform, the number of nozzles is at least 3 or more, preferably 4 or more as described above, and is arranged symmetrically with respect to the entire circumferential direction. You may supply a toner particle uniformly from the slit part provided in the 360 degree | times perimeter area | region.
[0044]
(3) The temperature distribution of the hot air in the region where the toner particles are processed is controlled so that uniform heat energy is applied to all the particles, and the hot air is controlled in a laminar flow state. . For this purpose: (i) To reduce the temperature variation of the heat source supplying hot air; (ii) To make the straight pipe part before the hot air supply as long as possible. Alternatively, it is also preferable to provide a stabilizer for stabilizing the hot air near the hot air supply port. Furthermore, the apparatus configuration illustrated in FIG. 3 is an open system, and therefore hot air tends to diffuse in a direction in contact with the outside air. Therefore, the hot air supply port may be throttled as necessary.
[0045]
(4) Collection of heat-treated products must be controlled so as not to generate heat. For this purpose: (i) Heat treated and cooled particles should be cooled with a chiller in order to suppress the heat generated by the piping system (particularly the R portion) and the cyclone normally used for collecting toner particles. It is preferable to do.
[0046]
As described above, the first toner of the present invention can be obtained by further adding inorganic fine particles to the toner particles to which the inorganic fine particles are strongly adhered by thermal energy and mixing them with a known mixing device. The addition amount of the inorganic fine particles after the heat treatment is not particularly limited as long as the total amount with the addition amount of the inorganic fine particles before the heat treatment is within the above range, and the adhesion strength ratio of the obtained toner is within the above range, Usually, it is 0.1 to 5.0 parts by weight, preferably 0.3 to 3.0 parts by weight, more preferably 0.3 to 2.0 parts by weight based on 100 parts by weight of the toner particles before the heat treatment. Two or more kinds of inorganic fine particles may be used as the inorganic fine particles added after the heat treatment, and in this case, the total amount of the fine particles may be within the above range.
[0047]
Mixing may be performed by a known mixing device, for example, a rotary blade type mixing device such as a Henschel mixer. The mixing conditions may be such that the inorganic fine particles added after the heat treatment are weakly attached to the surface of the heat-treated toner particles. For example, standard blades (ST / A ₀ ) Is processed using a 9L Henschel mixer equipped with a 9L Henschel mixer, the peripheral speed is 10 to 50 m / s, preferably 20 It is treated at -40 m / s for 0.5-5 minutes, preferably 1-3 minutes. In addition, when silica is added in this step, since silica has a relatively large amount of aggregated particles, it is preferable to set the mixing conditions slightly stronger within the above range.
[0048]
In such mixing, known additives such as abrasives, lubricants, carrier deterioration inhibiting functional particles may be added. As the abrasive, for example, known inorganic fine particles and organic fine particles having an average primary particle diameter of more than 100 nm, preferably 100 to 800 nm can be used. Examples of the inorganic fine particle material include magnesium titanate, strontium titanate, titanium oxide, large particle size silica, large particle size alumina and the like. Examples of the organic fine particle material include styrene resin, (meth) acrylic resin, styrene-acrylic resin, melamine resin, silicone resin, polyethylene, and polypropylene.
[0049]
Examples of the lubricant include fatty acid metal salts such as aluminum stearate, calcium stearate, zinc stearate, and magnesium stearate having an average particle size of not more than the toner size, preferably 1 to 10 μm.
[0050]
The first toner of the present invention obtained as described above preferably has an average circularity of 0.955 or more. This is because by having such an average circularity, the transferability of the toner is further improved, and problems such as a decrease in transfer efficiency and a dropout can be more effectively prevented. In this specification, the average circularity is the following formula:
[Expression 1]

Is the average of the values calculated by the "circumference of the circle equal to the projected area of the particle" and "perimeter of the projected particle image" is a flow type particle image analyzer (FPIA-1000 or FPIA-2000; Toa Medical) It shows with the value obtained by measuring with a water dispersion system using the electronic company). The closer to 1, the closer to a perfect circle. As described above, since the average circularity is obtained from “the circumference of a circle equal to the projected area of the particle” and “the circumference of the projected image of the particle”, the value accurately represents the shape of the toner particle, that is, the uneven state of the particle surface. It becomes an index reflected in Further, since the average circularity is a value obtained as an average value of 3000 toner particles, the reliability of the average circularity in the present invention is extremely high. In the present specification, the average circularity does not have to be measured by the above device, and may be measured by any device as long as it can be obtained based on the above equation in principle.
[0051]
In the first toner of the present invention, the toner particles may be any known toner particles, and usually contain at least a binder resin and a colorant. If desired, a charge control agent, a release agent (offset preventing agent), Further includes magnetic powder and the like.
[0052]
The toner particles may be produced by a known method, for example, a dry method such as a pulverization method, or a wet method such as an emulsion dispersion method, an emulsion polymerization method or a suspension polymerization method. It is preferable to be manufactured using. For example, when toner particles are produced by a pulverization method, for example, a binder resin and a colorant, and optionally a charge control agent, a release agent (offset prevention agent), magnetic powder are mixed, melt-kneaded, and cooled. , Coarsely and finely pulverized and classified to obtain toner particles. The volume average particle size of the toner particles is 3 to 8.5 μm, preferably 4 to 7 μm. If it is larger than that, it is not preferable because the texture and fine line reproducibility of the halftone image is deteriorated. If it is smaller than that, the toner powder handling property is remarkably deteriorated. Since there is a concern about the influence on the human body when released, it is not preferable.
[0053]
As the binder resin constituting the toner particles, known thermoplastic synthetic resins and natural resins used in the field of electrostatic latent image developing toners can be used. For example, synthetic resins such as styrene resins, acrylic resins, olefin resins, diene resins, polyester resins, polyamide resins, epoxy resins, silicone resins, phenol resins, petroleum resins, urethane resins, and natural resins Resin. In the present invention, it is preferable to use a resin having a glass transition temperature of 50 to 75 ° C., a softening point of 80 to 160 ° C., a number average molecular weight of 1000 to 30000, and a weight average molecular weight / number average molecular weight of 2 to 100.
[0054]
In particular, when a full color toner (including a black toner) is intended, a glass transition point of 50 to 75 ° C., a softening point of 80 to 120 ° C., a number average molecular weight of 2000 to 30000, and a weight average molecular weight / number average molecular weight of 2 to 20 It is good to use resin which is. In addition, when aiming at a monochrome toner or a magnetic toner, a first resin having a glass transition point of 50 to 75 ° C. and a softening point of 80 to 125 ° C., and a glass transition point of 50 to 75 ° C. and a softening point of 125 to 160 ° C. It is preferable to use a binder resin composed of the second resin.
[0055]
As the toner binder resin, it is more preferable to use a polyester resin having the above characteristics and an acid value of 2 to 50 KOHmg / g, preferably 3 to 30 KOHmg / g. By using a polyester resin having such an acid value, the dispersibility of various pigments including carbon black and a charge control agent can be improved, and a toner having a sufficient charge amount can be obtained.
[0056]
Known pigments and dyes are used as the colorant. For example, various carbon black, activated carbon, titanium black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, copper phthalocyanine, malachite green oxalate, lamp black, rose bengal, CI CI Pigment Red 48: 1, CI Pigment Red 122, CI Pigment Red 57: 1, CI Pigment Red 184, CI Pigment Yellow 97, CI Pigment Yellow 12, CI Pigment Yellow 17, CI Solvent Yellow 162 CI Pigment Yellow 180, CI Pigment Yellow 185, CI Pigment Blue 15: 1, CI Pigment Blue 15: 3, and the like. Further, in addition to various carbon black, activated carbon, and titanium black, a part or all of the colorant can be replaced with a magnetic material in the black toner particles. As such a magnetic material, for example, known magnetic fine particles such as ferrite, magnetite, iron, and nickel can be used. The average particle size of the magnetic particles is preferably 1 μm or less, particularly preferably 0.5 μm or less, from the viewpoint of obtaining dispersibility during production.
[0057]
The content of the colorant in the black toner particles is preferably 3 to 15 parts by weight with respect to 100 parts by weight of the binder resin. In the color toner particles (full color toner particles other than black toner particles), the content of the colorant is preferably 2 to 6 parts by weight with respect to 100 parts by weight of the binder resin. In the color toner particles, from the viewpoint of improving dispersibility in the toner particles, the colorant is previously melt-kneaded and pulverized with a resin having good compatibility with the binder resin used, preferably the binder resin used. It is preferably used as the resulting masterbatch. In this case, the amount of the master batch used may be such that the colorant content in the master batch is within the above range.
[0058]
When used as a magnetic toner, part or all of the colorant may be replaced with a magnetic material. As such a magnetic material, known magnetic fine particles exemplified in the description of the black toner particles can be used. The magnetic material may be added in an amount of 20 to 60 parts by weight with respect to 100 parts by weight of the binder resin.
[0059]
The charge control agent is not particularly limited. For example, a polymer such as a fluorosurfactant, a metal-containing dye such as a salicylic acid metal complex, an azo metal compound, or a copolymer containing maleic acid as a monomer component. Acids, quaternary ammonium salts, azine dyes such as nigrosine, carbon black and the like can be added.
[0060]
Furthermore, a wax may be contained as a release agent in order to improve characteristics such as offset resistance. Examples of such a wax include polyolefin wax, carnauba wax, rice wax, sazol wax, montan ester wax, Fischer-Tropsch wax, and polyolefin wax is preferably used. When the toner contains wax as described above, the content is not particularly limited, but the effect of addition without causing problems such as filming can be 0.5 to 5 parts by weight with respect to 100 parts by weight of the binder resin. It is preferable in obtaining. Two or more release agents may be used in combination, and in that case, the total amount of the release agents only needs to be within the above range.
[0061]
Examples of polyolefin waxes include oxidized polypropylene wax, oxidized polyethylene wax, polypropylene wax, and polyethylene wax. When using a polyester resin as the binder resin, it is particularly preferable to use an oxidized polypropylene wax from the viewpoint of the dispersibility of the wax.
[0062]
When using a polyolefin wax, particularly a low molecular weight polypropylene wax, it is preferable to use a wax modified with a carboxylic acid or an acid anhydride from the viewpoint of further improving the fluidity of the toner. In particular, modified polypropylene obtained by modifying low molecular weight polypropylene with one or more acid monomers selected from the group consisting of acrylic acid, methacrylic acid, maleic acid and maleic anhydride is preferably used. The modified polypropylene can be obtained, for example, by grafting or adding one or more acid monomers to polypropylene in the presence or absence of a peroxide catalyst. The modified polypropylene has an acid value of 0.5 to 30 KOHmg / g, preferably 1 to 20 KOHmg / g.
[0063]
As commercially available modified polypropylene wax, for example, Viscol 100TS (softening point 140 ° C., acid value 3.5), Biscol 110TS (softening point 140 ° C., acid value 3.5) manufactured by Sanyo Chemical Industries, Ltd. can be used.
[0064]
The first toner of the present invention obtained as described above was subjected to a full-color image forming method, preferably by pressing and transferring the toner image formed on the image carrier onto the intermediate transfer member for each color. Thereafter, the toner image transferred onto the intermediate transfer member can be effectively used in a full-color image forming method including press-transferring the toner image onto a recording member. That is, in the full-color image forming method using the first toner of the present invention, the void of the toner image during the primary and secondary transfer and the spent fine inorganic particles on the carrier and the photoreceptor are suppressed over a long period of time. High-quality full-color images excellent in transferability free from noise such as BS and fog can be obtained over a long period of time. In particular, when the one-component development method is applied, toner selection on the toner carrier (a phenomenon in which toner of a specific shape or particle size is consumed) does not occur, and a stable image can be obtained over a long period of time. It is done. In addition, the first toner obtained by instantaneous heat treatment has a uniform toner shape and high surface smoothness, so it is resistant to stress and reduced generation of fine particles due to the embedding of inorganic fine particles and cracking of the toner. obtain.
[0065]
The present invention also includes an electrostatic latent image obtained by externally adding inorganic fine particles to toner particles containing at least a binder resin and a colorant, and having two peaks of a strong adhesion peak and a weak adhesion peak in the adhesion strength distribution of the inorganic fine particles. The present invention also relates to a second toner that is a developing toner and in which two or more kinds of inorganic fine particles adhere strongly to the toner particles.
[0066]
The second toner is the same as the first toner except that the addition amount of inorganic fine particles and the adhesion strength ratio are not limited and two or more types of inorganic fine particles are strongly adhered to the toner particles. The inorganic fine particles adhering weakly in the second toner are not particularly limited as long as two or more types of inorganic fine particles are strongly adhered to the toner particles, and some of the two or more types of inorganic fine particles that are strongly adhering are used. Or it may be the same as the whole or different. Two or more types of inorganic fine particles mean two or more types of inorganic fine particles having different types of materials.
[0067]
By adopting such a configuration, excellent charging stability and charging environment characteristics of the toner can be obtained. In other words, it is possible to suppress fluctuations in the toner charge amount due to long-term use or environmental fluctuations, and it is possible to prevent a decrease in image density particularly when used in a high temperature and high humidity environment or a low temperature and low humidity environment. Even if one kind of inorganic fine particle is strongly adhered to the toner particle alone, the effect of improving the charging stability and charging environment characteristics cannot be obtained.
[0068]
Specifically, as the strongly adhered inorganic fine particles, two or more types of inorganic fine particles selected from known inorganic fine particles are used, and preferably two or more types of inorganic fine particles containing at least silica are used. More preferably, two or more kinds of inorganic fine particles selected from the group consisting of silica, titania and alumina and containing at least silica are used. In general, the combination of inorganic fine particles to be strongly adhered is preferably a combination of silica and titania or silica and alumina.
The weakly adhered inorganic fine particles are independently selected from the strongly adhered inorganic fine particles, and more specifically, one or more kinds of inorganic fine particles selected from known inorganic fine particles are used, preferably composed of silica, titania and alumina. One or more inorganic fine particles selected from the group are used.
The inorganic fine particles that are strongly adhered and the inorganic fine particles that are weakly adhered are preferably surface-treated with a hydrophobizing agent in the same manner as the inorganic fine particles in the first toner.
[0069]
The method for producing the second toner is substantially the same as the method for producing the first toner, except that two or more kinds of inorganic fine particles to be strongly adhered are used.
[0070]
The addition amount and average primary particle size of the inorganic fine particles to be strongly adhered and the inorganic fine particles to be weakly adhered and the adhesion strength ratio in the second toner are not particularly limited, but are the same as those in the first toner. It is preferable.
[0071]
In the present invention, the effect of the first toner and the effect of the second toner can be obtained simultaneously by applying the second invention (second toner) to the first toner. That is, in the first toner, two or more types of inorganic fine particles selected from known inorganic fine particles are used as the inorganic particles strongly adhered, and preferably two or more types of inorganic fine particles containing at least silica are used. More preferably, two or more kinds of inorganic fine particles selected from the group consisting of silica, titania and alumina and containing at least silica are used. In general, the combination of inorganic fine particles to be strongly adhered is preferably a combination of silica and titania or silica and alumina. By selecting the inorganic fine particles that adhere strongly in the first toner as described above, the spent fine particles on the carrier and the photoreceptor are suppressed, and excellent fluidity is maintained over a long period of time. A toner having excellent environmental characteristics can be obtained.
[0072]
At this time, the weakly adhering inorganic fine particles are independently selected from the strongly adhering inorganic fine particles, and more specifically, using one or more kinds of inorganic fine particles selected from known inorganic fine particles, preferably silica, titania and One or more inorganic fine particles selected from the group consisting of alumina are used. The inorganic fine particles that are strongly adhered and the inorganic fine particles that are weakly adhered are preferably surface-treated with a hydrophobizing agent in the same manner as the inorganic fine particles in the first toner.
[0073]
Such a toner is the same as the first toner except that the above-described materials are used as the inorganic fine particles to be strongly adhered and the inorganic fine particles to be weakly adhered. The production method is the same as that of the first toner production method except that two or more kinds of inorganic fine particles to be strongly adhered are used.
[0074]
【Example】
(Manufacture of polyester resin A)
Attach a reflux condenser, water separator, nitrogen gas inlet tube, thermometer, and stirrer to a 2 liter four-necked flask and place it in a mantle heater to add bisphenol A-ethylene oxide adduct and bisphenol A-propylene oxide. And terephthalic acid and fumaric acid in a flask with a molar ratio (bisphenol A-ethylene oxide adduct: bisphenol A-propylene oxide adduct: terephthalic acid: fumaric acid) of 5: 5: 4: 5 The reaction was conducted by heating and stirring while introducing nitrogen. The progress of the reaction was followed while measuring the acid value, and when the predetermined acid value was reached, the reaction was terminated, and the number average molecular weight Mn was 4,800, and the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn was A polyester resin A having a glass transition temperature of 61 ° C. and a softening temperature of 102 ° C. was obtained.
[0075]
(External additive used)
・ Silica A: Silica # 130 (particle size 15 nm) surface-treated with hexamethylene disilazane (HMDS) (hydrophobic degree 65%)
・ Silica B: Silica # 90 (particle size 30 nm) surface-treated with HMDS (hydrophobicity 70%)
・ Silica C: OX50 (particle size: 30-100 nm, manufactured by Aerosil) surface-treated with HMDS (hydrophobic degree 70%)
・ Titania A: Anatase-type titania particles with a particle size of 30 nm surface-treated with isobutyltrimethoxysilane (hydrophobic degree 65%)
・ Titania B; Anatase-type titania particles with a particle size of 50 nm surface-treated with isobutyltrimethoxysilane (hydrophobic degree 65%)
・ Titania C; Anatase-type titania particles with a particle size of 70 nm, surface-treated with isobutyltrimethoxysilane (hydrophobic degree 60%)
・ Alumina A: Alumina with a particle size of 20nm surface-treated with isobutyltrimethoxysilane (hydrophobicity 55%)
・ Alumina B: Alumina with a particle size of 60nm surface-treated with isobutyltrimethoxysilane (hydrophobic degree 60%)
・ Alumina C: 100 nm particle size alumina surface treated with isobutyltrimethoxysilane (hydrophobic degree 60%)
[0076]
(Conditions for heat treatment and mixing treatment)
・ Condition 1 (heat treatment): Maximum temperature: 200 ° C., residence time: 0.5 seconds, powder dispersion concentration: 100 g / m ^Three Cooling air temperature: 18 ° C, cooling water temperature 10 ° C.
・ Condition 2 (mixing treatment); peripheral speed 40m / s, mixing time 3 minutes, ST / Ao blade.
・ Condition 3 (mixing treatment); peripheral speed 20m / s, mixing time 1 minute, ST / Ao blade.
・ Condition 4 (mixing treatment); peripheral speed 40m / s, mixing time 6 minutes, ST / Ao blade.
[0077]
(Manufacture of toner mother particles)
70 parts by weight of polyester resin A (Tg: 61 ° C., Tm: 102 ° C.) and 30 parts by weight of magenta pigment (CI Pigment Red 184) were charged into a pressure kneader and kneaded. The obtained kneaded product was cooled and then pulverized by a feather mill to obtain a pigment master batch.
93 parts by weight of polyester resin A, 10 parts by weight of the above pigment master batch, 2 parts by weight of zinc salicylate metal complex (E84, manufactured by Orient Chemical Industries), 2 parts by weight of oxidized low molecular weight polypropylene (Biscol 100TS; manufactured by Sanyo Chemical Industries) After thorough mixing with a Henschel mixer, the mixture was melt-kneaded with a large-diameter discharge nozzle of a twin-screw extrusion kneader (PCM-30; manufactured by Ikegai Iron Works Co., Ltd.), and the resulting kneaded product was quickly cooled. Thereafter, coarse pulverization was performed with a feather mill. The coarsely pulverized product is pulverized and coarsely classified by a jet pulverizer (IDS; manufactured by Nippon Pneumatic Industrial Co., Ltd.), and then finely classified by a DS classifier (manufactured by Nippon Pneumatic Industrial Co., Ltd.). Mother particles were obtained.
[0078]
( Experimental example 1)
Heat treatment process
To 100 parts by weight of toner base particles, 0.8 part by weight of silica B and 0.8 part by weight of titania B were added and mixed with a Henschel mixer at a peripheral speed of 30 m / s for 1 minute. The mixture was heat-treated under condition 1 using a surface modification apparatus (surfing system; manufactured by Nippon Pneumatic Industry Co., Ltd.) shown in FIG.
Mixing process
0.4 parts by weight of silica B and 0.4 parts by weight of titania B were added to the obtained mixture, and the mixture was mixed under conditions 2 using a 9 L Henschel mixer with a charge of about 1 kg.
Sieve process
The obtained mixture was sieved with a circular vibrating screen (aperture 77 μm) to obtain a toner.
[0079]
(Example 1-4, Experimental Examples 1-16 And Reference Examples 1-9)
Except that the types and amounts of external additives added in the heat treatment step and the mixing treatment step and the treatment conditions were changed as shown in Tables 1 to 3, Experimental example A toner was obtained in the same manner as in 1.
In Reference Example 4, the mixing treatment step was not performed, and the mixture obtained in the heat treatment step was directly subjected to the sieving step.
In Reference Example 5, a mixing treatment step was performed instead of the heat treatment step. That is, without performing the heat treatment step, 100 parts by weight of the toner base particles were directly subjected to the mixing treatment step, and the obtained mixture was further subjected to the mixing treatment step.
Further, in Reference Example 6, the heat treatment step was not performed, and 100 parts by weight of the toner base particles were directly subjected to the mixing treatment step.
[0080]
(Evaluation item)
・ Adhesion strength distribution
Ten sets of 4 g of toner were prepared by wetting a 0.2% aqueous solution of polyoxyethyl phenyl ether in a beaker with a capacity of 100 ml. After the toner settled in the solvent of each container is swirled 10 to 20 times by hand stirring with a stirring rod, immediately, the ultrasonic homogenizer US-1200T (manufactured by Nippon Seiki Co., Ltd .; specification frequency 15 kHz) 30 seconds, 60 seconds, 90 seconds, ..., 270 seconds, 300 for each container while adjusting the sonic energy so that the value of the ammeter indicating the vibration indication value attached to the main unit shows 60μA (50w) The external additive was released from the toner into the solvent. After that, the toner particles are settled by decantation, the supernatant solution containing the release external additive is removed, 60 ml of pure water is added, the toner is manually stirred and washed, and a membrane filter with a 1 μm aperture is set. The washing solution was removed using a vessel. The toner obtained after repeating this washing again was dried in a vacuum dryer to obtain a dry toner from which the external additives detached by applying ultrasonic waves were removed.
[0081]
These toners and toners to which no ultrasonic waves have been applied are subjected to fluorescent X-ray analysis, and the amount of external additive (X) remaining on the toner after the ultrasonic waves are applied and the amount of external additives that have adhered to the toner before the ultrasonic waves are applied. By quantifying the amount (Y) of the additive, the amount of the external additive released was determined based on the following formula. The above X and Y can also be obtained by measuring the amount of residue obtained by roasting the toner.
External additive removal amount (% by weight) = (Y-X) / Y
[0082]
The relationship between the ultrasonic time and the amount of the external additive removed was made into a histogram to obtain an adhesion strength distribution graph. For example, Experimental example The adhesion strength distribution graph for 1 toner is shown in FIG. From the graph, the ultrasonic time showing the peak was read, and the peak that appeared when the ultrasonic time was 150 seconds or less was regarded as the weak adhesion peak, and the peak that appeared when the ultrasonic time exceeded 150 seconds was regarded as the strong adhesion peak.
[0083]
Further, the adhesion strength ratio (%) was determined from the graph. Specifically, the ratio of the “sum of the amount of the external additive that constitutes the peak of the weak adhesion peak” to the “sum of the amount of the external additive that constitutes the peak of the strong adhesion peak” was determined. Note that the amount of external additive detachment of the channel corresponding to the valley between the peak of the weak adhesion peak and the peak of the strong adhesion peak is not added to any sum.
[0084]
・ Circularity
The figure shows the values obtained by measuring in a water dispersion system using a flow type particle image analyzer (FPIA-1000 or FPIA-2000; manufactured by Toa Medical Electronics Co., Ltd.).
·Liquidity
Evaluation was made based on the AD value measured by a powder tester.
×; AD value was less than 0.30;
Δ: AD value was 0.30 or more and less than 0.35;
○: AD value was 0.35 or more and less than 0.40;
A: AD value was 0.40 or more and less than 0.45.
[0085]
Each toner and a carrier described later were mixed at a toner concentration of 6%, and the following evaluation was performed using a developer, a full-color copier (CF910; manufactured by Minolta) and CF paper.
・ Carrier degradation
The toner is electrolytically separated from the developer after the 30,000-sheet durability test by the above machine to obtain only the carrier. Charge the carrier with the toner type fixed, measure the charge level (Q / M) of the New carrier and the charge level (Q / M) of the carrier after durability, and determine the charge capacity of the carrier after durability. Calculation was based on the following formula.
Charging capacity = (Q / M of carrier after endurance) / (Q / M of new carrier) x 100
A: Charging ability was 90% or more;
○: Charging ability was 80% or more;
Δ: Charging ability was 70% or more;
X: The charging ability was less than 70%.
[0086]
・ BS (black spot)
The photoreceptor after the 30,000-sheet endurance test was observed with the above machine, and the state of the fixed substance (BS) of the external additive was evaluated.
◎; no sticking;
○: Slight adhesion was observed but not on the printed image;
Δ: Although there was sticking, it was not a problem in practical use;
X: Image noise (BS), which is a practical problem due to fixing, was generated.
[0087]
・ Blank
After the endurance test of 30,000 sheets using the above machine, the electrophotographic society chart was copied, and the hollowed out state of the character image was observed.
A: No void occurred at all;
○: Some characters have a void that is indistinguishable with the naked eye, but there was no practical problem at all;
Δ: Slight hollowness can be confirmed with the naked eye, but there was no practical problem;
X: A void in the level that clearly affects the character quality is generated.
[0088]
・ Toner adhesion amount
After 30,000 sheets endurance test with the above machine under LL environment (10 ° C, 20%) and HH environment (40 ° C, 80%), solid images were copied and the amount of adhered toner at any 5 points was measured. . If the charge is extremely high or too low, the amount of adhesion will be low in the LL and HH environments. The evaluation was carried out under each environment, and the worse results were shown in the table.
○: Average adhesion amount is 5 g / m ² Or more;
Δ: Average adhesion amount is 3.5 g / m ² More than 5g / m ² Less than practical, no problem in practical use;
×: Average amount of adhesion is 3.5 g / m ² There was a problem in practical use.
[0089]
・ Charging environment characteristics
The charge amount of the developer stored for 1 day or longer in the LL environment (10 ° C., 20%) and in the HH environment (40 ° C., 80%) was measured. The measured values were evaluated according to the following ranking. Of the evaluation results of the charge amount of the developer stored in the LL environment and the charge amount of the developer stored in the HH environment, the worse result is taken as the result of the toner.
○: 45 μC / g ≦ charge amount ≦ 55 μC / g;
Δ: 35 μC / g <charge amount <45 μC / g or 55 μC / g <charge amount <65 μC / g;
X: Charge amount ≦ 35 μC / g or 65 μC / g ≦ charge amount.
[0090]
[Table 1]

[0091]
[Table 2]

[0092]
[Table 3]

[0093]
(Carrier production)
100 parts by weight of methyl ethyl ketone was charged into a 500 ml flask equipped with a stirrer, a condenser, a thermometer, a nitrogen inlet tube, and a dropping device. In a nitrogen atmosphere at 80 ° C., 36.7 parts by weight of methyl methacrylate, 5.1 parts by weight of 2-hydroxyethyl methacrylate, 58.2 parts by weight of 3-methacryloxypropyltris (trimethylsiloxy) silane and 1,1′-azobis (cyclohexane-1-carbonitrile ) A solution obtained by dissolving 1 part by weight in 100 parts by weight of methyl ethyl ketone was dropped into the reactor over 2 hours and aged for 5 hours.
To the obtained resin, isophorone diisocyanate / trimethylolpropane adduct (IPDI / TMP system: NCO% = 6.1%) as a crosslinking agent was adjusted so that the OH / NCO molar ratio was 1/1, and then methyl ethyl ketone was used. A coated resin solution having a solid ratio of 3% by weight was prepared by dilution.
Firing ferrite powder F-300 (volume average particle size: 50 μm, manufactured by Powdertech Co., Ltd.) is used as a core material, and a Spira coater (Okada Seiko Co., Ltd.) is used so that the coating resin solution has a coating resin amount of 1.5% by weight relative to the core material. Applied and dried.
The obtained carrier was baked by being left at 160 ° C. for 1 hour in a hot air circulating oven. After cooling, the ferrite powder bulk was pulverized using a sieve shaker equipped with a screen mesh having openings of 106 μm and 75 μm to obtain a resin-coated carrier.
[0094]
【The invention's effect】
The toner of the present invention can suppress spent fine inorganic particles on the carrier and the photoreceptor, and can maintain excellent fluidity over a long period of time. Further, by selecting the inorganic fine particles to be strongly adhered, excellent charging stability and charging environment characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 shows the adhesion strength distribution of inorganic fine particles for the toner of the present invention.
FIGS. 2A and 2B show the adhesion strength distribution of inorganic fine particles for a conventional toner.
FIG. 3 shows a schematic configuration diagram of an apparatus for performing instantaneous heat treatment.
4 is a schematic cross-sectional view of the sample crushing chamber in the apparatus of FIG. 3 when cut in the horizontal direction.
[Explanation of symbols]
101; Hot air generator, 102; Introduction pipe, 103; Sample injection nozzle.

Claims (9)

It will be 1.5 to 8 parts by weight of externally added inorganic fine particles with respect to 100 parts by weight of the toner particles to the toner particles containing at least a binder resin and a colorant, strong adhesion peak and weak adhesion peak in adhesion strength distribution of the inorganic fine particles The toner for developing an electrostatic latent image having two peaks of “inorganic fine particles constituting the peak of weak adhesion peak” with respect to “the sum of the separation amounts of inorganic fine particles constituting the peak of strong adhesion peak” in the adhesion strength distribution the proportion of the sum of the withdrawal amount "(adhesion strength ratio) of Ri 10-100% der electrostatic latent image of two or more inorganic fine particles comprising silica and alumina, characterized in that it is strongly attached to the toner particles Development toner.   The electrostatic latent image developing toner according to claim 1, wherein the adhesion strength ratio is 10 to 50%.   3. The electrostatic latent image developing toner according to claim 1, wherein the volume average particle diameter is 3 to 8.5 μm and the average circularity is 0.955 or more.   The toner for developing an electrostatic latent image according to claim 1, wherein the average primary particle diameter of the inorganic fine particles is 10 to 100 nm.   1 or 2 wherein the inorganic fine particles are selected from the group consisting of hydrophobic silica having an average primary particle size of 10 to 100 nm, hydrophobic titania having an average primary particle size of 20 to 100 nm, and hydrophobic alumina having an average primary particle size of 20 to 100 nm The electrostatic latent image developing toner according to claim 1, wherein the toner is an inorganic fine particle larger than that. 2 or more kinds of inorganic fine particles toner for electrostatic latent image development according to any one of claims 1 to 5 which are strongly attached to the toner particles containing at least hydrophobic silica. 2. The toner according to claim 1, wherein after the inorganic fine particles are strongly adhered to the toner particle surfaces by thermal energy, the inorganic fine particles are weakly adhered to the toner particle surfaces by mixing the toner particles and the inorganic fine particles. The electrostatic latent image developing toner according to 1. The addition amount of the strongly attached inorganic fine particles is 1.0 to 3.0 parts by weight with respect to 100 parts by weight of the toner particles, and the addition amount of the weakly attached inorganic fine particles is with respect to 100 parts by weight of the toner particles. The toner for developing an electrostatic latent image according to claim 7, wherein the toner is 0.3 to 2.0 parts by weight. The toner for developing an electrostatic latent image according to claim 1, wherein an adhesion strength ratio is 10 to 35%.

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