JP3697284B2 - Full color toner for electrostatic image development - Google Patents

Description

で表されるジメチルポリシロキサンタイプ、一般式
【化２】

で表されるメチルハイドロジエンポリシロキサンタイプ、一般式
【化３】

で表されるメチルフェニルポリシロキサンタイプ等が使用できる。さらに必要に応じて、アルキル変性、アミノ変性、エポキシ変性、エポキシ・ポリエーテル変性、カルボキシル変性、メルカプト変性、アルコール変性、フッ素変性等を行ってもよい。
【００２１】
本発明において水系中で処理したチタンを気相中で処理するのに用いられるシランカップリング剤は一般式Ｒ₄ｍ₃ＳｉＹ₂ｎ₅［式中、Ｒ₄はアルコキシ基又は、塩素原子、ｍ₃は１〜３の整数、Ｙ₂はアルキル基、ビニル基、グリシドキシ基、メタクリル基を含む炭化水素基、ｎ₅は３〜１の整数］で表されるもので、例えば代表的にはジメチルジクロルシラン、トリメチルクロルシラン、アルリジメチルクロルシラン、ヘキサメチルジシラザン、アリルフェニルジクロルシラン、ベンジルジメチルクロルシラン、ビニルトリエトキシシラン、γ−メタクリルオキシプロピルトリメトキシシラン、ビニルトリアセトキシシラン、ジビニルクロルシラン、ジメチルビニルクロルシラン等を挙げることができる。
【００２２】
上記微粉体のシランカップリング剤処理は、微粉体を撹拌等によりクラウド状としたものに気化したシランカップリング剤を反応させる乾式処理を採用することができる。
【００２３】
通常、フルカラートナーはバインダー樹脂中に、シアン、マゼンタあるいはイエロー等の着色剤、その他所望の流動化剤が分散してなる粒子として調製される。本発明においては流動化剤として上記した薄片状チタニアを使用する。
【００２４】
通常フルカラートナーのバインダーとして使用する樹脂は、エポキシ系樹脂あるいはポリエステル系樹脂であり、その中でも負帯電性が強く定着性に優れるポリエステル系樹脂が好ましい。特に、シャープな溶融特性を有するものが好ましく、ビスフェノール誘導体もしくは置換体をジオール成分とし、２価以上のカルボン酸又はその酸無水物又はその低級アルキルエステルとからなる、フマル酸、マレイン酸、無水マレイン酸、フタル酸、テレフタル酸、トリメリット酸などのカルボン酸成分とを共縮重合したポリエステル樹脂が最適である。
【００２５】
さらに好ましくは、ゲルパーミエーションクロマトグラフィ(ＧＰＣ)による分子量分布測定で数平均分子量(Ｍn)が３０００〜１００００、好ましくは３０００〜７０００、重量平均分子量(Ｍw)が７０００〜５００００、好ましくは７０００〜１５０００、分子量分布(Ｍw／Ｍn)が１．５〜５．０、好ましくは２．０〜４．０、ＤＳＣによる吸熱ピーク値(Ｔg)が５０〜７０℃、フローテスターによる軟化温度(Ｔm)が９０〜１１０℃である線状ポリエステル樹脂が好ましい。これらの諸特性を満足しない場合には、トナーの透光性、着色剤や荷電制御剤等の分散性、定着性および耐熱性を十分に満足させることができなくなる。具体的には、分子量分布を上記範囲とすることにより、定着時にトナーのシャープメルト特性を向上させることができ透光性を向上させることができる。また、ガラス転移点および軟化点を上記範囲とすることによりトナーに十分な耐熱性および定着性を付与することができる。
【００２６】
また、ポリエステル樹脂は、テトラヒドロフラン不溶成分を実質含有しておらず、テトラヒドロフランに溶解するものである。テトラヒドロフラン不溶成分を含有していると、トナーの透光性を阻害する原因となるため好ましくない。
【００２７】
本発明のトナーは従来から知られている方法、例えば上記結着樹脂、着色剤に加え、荷電制御剤およびその他の所望の添加剤を所定量添加して混合、混練したあと、粉砕、分級することにより平均粒径６〜１０μｍの粒子として得られる。
【００２８】
着色剤としてはフルカラートナー用着色剤として知られる各種着色剤を使用可能である。例えば青色染顔料として: Ｃ．Ｉ．７４１００(無金属フタロシアニンブルー)、Ｃ．Ｉ．７４１６０(フタロシアニンブルー)、Ｃ．Ｉ．７４１８０(ファストスカイブルー)等;
赤色染顔料として: Ｃ．Ｉ．１２０５５(スターリンＩ)、Ｃ．Ｉ．１２０７５(パーマネントオレンジ)、Ｃ．Ｉ．１２１７５(リソールファストオレンジ３ＧＬ)、Ｃ．Ｉ．１２３０５(パーマネントオレンジＧＴＲ)、Ｃ．Ｉ．１１７２５(ハンザイエロー３Ｒ)、Ｃ．Ｉ．２１１６５(バルカンファストオレンジＧＧ)、Ｃ．Ｉ．２１１１０(ベンジジンオレンジＧ)、Ｃ．Ｉ．１２１２０(パーマネントレッド４Ｒ)、Ｃ．Ｉ．１２７０(パラレッド)、Ｃ．Ｉ．１２０８５(ファイヤーレッド)、Ｃ．Ｉ．１２３１５(ブリリアントファストスカーレット)、Ｃ．Ｉ．１２３１０(パーマネントレッドＦ２Ｒ)、Ｃ．Ｉ．１２３３５(パーマネントレッドＦ４Ｒ)、Ｃ．Ｉ．１２４４０(パーマネントエントレッドＦＲＬ)、Ｃ．Ｉ．１２４６０(パーマネントレッドＦＲＬＬ)、Ｃ．Ｉ．１２４２０(パーマネントレッドＦ４ＲＨ)、Ｃ．Ｉ．１２４５０(ライトファストレッドトーナーＢ)、Ｃ．Ｉ．１２４９０(パーマネントカーミンＦＢ)、Ｃ．Ｉ．１５８５０(ブリリアントカーミン６Ｂ)等;
黄色染顔料として: Ｃ．Ｉ．１０３１６(ナフトールイエローＳ)、Ｃ．Ｉ．１１７１０(ハンザイエロー１０Ｇ)、Ｃ．Ｉ．１１６６０(ハンザイエロー５Ｇ)、Ｃ．Ｉ．１１６７０(ハンザイエロー３Ｇ)、Ｃ．Ｉ．１１６８０(ハンザイエローＧ)、Ｃ．Ｉ．１１７３０(ハンザイエローＧＲ)、Ｃ．Ｉ．１１７３５(ハンザイエローＡ)、Ｃ．Ｉ．１１７４０(ハンザイエローＲＮ)、Ｃ．Ｉ．１２７１０(ハンザイエローＲ)、Ｃ．Ｉ．１２７２０(ピグメントイエローＬ)、Ｃ．Ｉ．２１０９０(ベンジジンイエロー)、Ｃ．Ｉ．２１０９５(ベンジジンイエローＧ)、Ｃ．Ｉ．２１１００(ベンジジンイエローＧＲ)、Ｃ．Ｉ．２００４０(パーマネントイエローＮＣＧ)、Ｃ．Ｉ．２１２２０(バルカンファストイエロー５)、Ｃ．Ｉ．２１１３５(バルカンファストイエローＲ)などを代表的なものとして例示できる。
【００２９】
これら着色剤は単独あるいは複数組み合わせて用いることができるが、トナー粒子中に含まれる結着樹脂１００重量部に対して、１〜１０重量部、より好ましくは２〜５重量部使用することが望ましい。すなわち、１０重量部より多いとトナーの定着性および透光性が低下し、一方、１重量部より少ないと所望の画像濃度が得られないおそれがある。
【００３０】
荷電制御剤としては例えば、Ｅ−８１(オリエント化学工業社製)などのクロム錯塩、Ｅ−８４(オリエント化学工業社製)などの亜鉛錯塩、Ｅ−８６(オリエント化学工業社製)などのアルミニウム錯塩、Ｅ−８９(オリエント化学工業社製)などのカリックスアレン系化合物が使用できる。
これらの荷電制御剤の量はトナー中における樹脂１００重量部にたいして、０．１〜１０重量部、好ましくは０．５〜５重量部になるようにする。
【００３１】
本発明のトナーには、その他必要に応じて、シリカ等の流動化剤、樹脂ビーズ等のクリーニング助剤、転写性向上のための大径シリカ等を添加してもよい。
【００３２】
本発明においては上記結着樹脂、着色剤を混練り、粉砕そして分級して得られたトナー粒子に薄片状チタニアを混合し(外添)、トナーを得る。混合を行いうる方法としては、機械式粉砕混合方法等従来の方法、条件でよく、例えばヘンシェルミキサー、スーパーミキサー、パウダーミキサー、ホモジナイザー等の混合機を使用可能である。
【００３３】
薄片状チタニアは、通常トナーに対して０．５〜２．０重量％、好ましくは０．５〜１．５重量％添加混合される。添加量が少なすぎると、所望の流動性および環境性が得られず画像の劣化を招く。多すぎると、帯電量の低下を招きカブリ等の原因となる。
【００３４】
以上のようにして得られる薄片状チタニアを外添したトナーはキャリアとともに２成分現像剤として使用される。
【００３５】
キャリアとしては、樹脂被覆キャリアを使用するのが好ましい。
キャリア芯材としては、静電潜像担持体へのキャリア付着(飛散)防止の点から、少なくとも２０μm(平均粒径)の大きさのものを使用し、キャリアスジ等の発生防止等画質の低下防止の点から大きくとも１００μmのものを使用する。具体的材料としては、電子写真用二成分キャリアとして公知のもの、例えばフェライト、マグネタイト、鉄、ニッケル、コバルト等の金属、これらの金属と亜鉛、アンチモン、アルミニウム、鉛、スズ、ビスマス、ベリリウム、マンガン、セレン、タングステン、ジルコニウム、バナジウム等の金属との合金あるいは混合物、酸化鉄、酸化チタン、酸化マグネシウム等の金属酸化物、窒化クロム、窒化バナジウム等の窒化物、炭化ケイ素、炭化タングステン等の炭化物との混合物および強磁性フェライト、ならびにこれらの混合物を適用することができる。
【００３６】
また、キャリア芯材の被覆樹脂(導電層、接着層、表面保護層)としては、例えば、ポリスチレン系樹脂、ポリ(メタ)アクリル系樹脂、ポリオレフィン系樹脂、ポリアミド系樹脂、ポリカーボネート系樹脂、ポリエーテル系樹脂、ポリスルホン酸系樹脂、ポリエステル系樹脂、エポキシ系樹脂、ポリブチラール系樹脂、尿素系樹脂、ウレタン／ウレア系樹脂、シリコン系樹脂、テフロン系樹脂等の各種熱可塑性樹脂および熱硬化性樹脂およびその混合物、並びに、これらの樹脂の共重合体、ブロック重合体、グラフト重合体およびポリマーブレンド等が使用できる。
【００３７】
以下実施例を挙げてさらに説明するが、実施例中、「部」と表現されているのは特に断らなければ「重量部」をいうものとする。
【００３８】
【実施例】
トナーの製造例
・ポリエステル樹脂 １００部
（数平均分子量(Mn):5,000、 重量平均分子量(Mw):10,000、 Mw/Mn:2.0、 軟化点(Tm):105℃、 ガラス転移点:60℃、THF不溶成分:0%）
・帯電制御剤(ボントロンＥ−８４（オリエント化学工業社製）） １部
・ブリリアントカーミン６Ｂ ４部
【００３９】
上記混合物をヘンシェルミキサーにより十分混合し、２軸押出機を用いて溶融混練した。混練物を冷却後、粗粉砕した。粗粉砕物をエアージェット方式による粉砕機で微粉砕した。さらに得られた微粉砕物を気流式粉砕機により分級して、体積平均粒径（Ｄ₅₀）８．０μｍのトナー粒子を得た。
【００４０】
キャリアの製造例
スチレン、メチルメタクリレート、２−ヒドロキシエチルアクリレート、メタクリル酸からなるスチレン−アクリル系共重合体（１．５：７．０：１．０：０．５）８０重量部とブチル化メラミン樹脂２０重量部をトルエンで希釈し、固形比２％のスチレン−アクリル樹脂溶液を調合した。
【００４１】
芯材として焼成フェライト粉（Ｆ−３００、平均粒径：５０μｍ、パウダーテック社製）を用い、上記スチレン−アクリル樹脂溶液をスピラーコーター（岡田精工社製）により塗布し乾燥した。塗布されたフェライト粉を熱風循環式オーブン中に１４０℃で２時間放置して焼成した。
【００４２】
冷却後フェライト粉バルクを目開き２１０μｍと９０μｍのスクリーンメッシュを取り付けたフルイ震盪器を用いて解砕し、樹脂被覆フェライト粉を得た。
【００４３】
このフェライト粉に対し上記塗布、焼成、解砕をさらに３回繰り返し樹脂被覆キャリアを得た。得られたキャリアの平均粒径は５２μｍであった。
【００４４】
実施例１
上記トナーの製造例で得られた粒子１００部に対し疎水性の薄片状チタニア微粒子（粒径：０．０１５〜０．０２μｍ、ＳＴＴ−３０Ａ；チタン工業社製）１．０部を添加しヘンシェルミキサーにて混合しトナーを得た。
【００４５】
得られたトナー５部に対して、キャリアの製造例で得られたキャリアを総量１００部になるように混合し現像剤とした。
【００４６】
得られた現像剤を用いて市販のフルカラー複写機（ＣＦ−８０；ミノルタ社製）にて画出しおよび下記各環境下５０００枚(５Ｋ枚)の耐久試験を行った。

【００４７】
各環境下、耐久後の画像は、カブリ、鮮明さ、画像濃度も初期と同等の良好なものが得られた。画出し、および耐久試験の結果を表１にまとめた。
【００４８】
表１中の各評価は以下のようにして行った。
・画像濃度
小数第３位を四捨五入して画像濃度（Ｉ．Ｄ．）値とした。
【００４９】
・カブリ
ミノルタ限界見本サンプルとを比較評価し以下のようにランク付した。
◎：ランク５（カブリ全くなし）。
○：ランク４（カブリほとんどなし）。
△：ランク３（カブリが若干認められるが実用上問題がない）。
×：ランク１〜２（カブリが多く、実用上問題あり）。
【００５０】
・耐久特性
各環境下で測定後(５Ｋ後)、総合評価し以下のようにランク付けを行った。
◎：全く問題なし。
○：一部の特性に変化はあるものの実用上問題なし。
×：実用上問題がある。
【００５１】
ＯＨＰ透光性
ＯＨＰ透光性を目視観察し以下のようにランク付けを行った。
○：実用上問題がない。
【００５２】
実施例２
疎水性の薄片状チタニア微粒子（ＳＴＴ−３０Ａ；チタン工業社製）の添加量を０．６部とした以外実施例１におけると同様に現像剤を調製し試験した。結果を表１にまとめた。
【００５３】
実施例３
疎水性の薄片状チタニア微粒子（ＳＴＴ−３０Ａ；チタン工業社製）の添加量を１．５部とした以外実施例１におけると同様に現像剤を調製し試験した。結果を表１にまとめた。
【００５４】
比較例１
実施例１において薄片状チタニア微粒子にかえて疎水性の不定形粒状チタニア微粒子（Ｔ−８０５；デグサ社製）を１．０部添加した以外実施例１におけると同様に現像剤を調製し試験した。結果を表１にまとめた。
【００５５】
比較例２
実施例１において薄片状チタニア微粒子にかえて疎水性の不定形粒状チタニア微粒子（ＴＴＯ−５１Ｃ；石原産業社製）を１．０部添加した以外実施例１におけると同様に現像剤を調製し試験した。結果を表１にまとめた。
【００５６】
比較例３
実施例１において薄片状チタニア微粒子にかえて下記により得られた疎水性の球状チタニア微粒子を１．０部添加した以外実施例１におけると同様に現像剤を調製し試験した。結果を表１にまとめた。
【００５７】
球状チタニア微粒子の調製：
イルメナイト鉱を硫酸により溶解し、冷却した後、遠心分離した。遠心分離した原液を加熱加水分解し、得られた水酸化チタンを回転炉で焼成（３５０〜４００℃）し、球状の親水性酸化チタン（粒径：０．０４〜０．０５μｍ）を得た。
得られた酸化チタンを水系中で撹拌混合しながらカップリング剤（n-Ｃ₅Ｈ₁₁Ｓｉ(ＯＣＨ₃)₃）を酸化チタン微粒子に対し２０％となるように添加混合した。
混合物を乾燥、解砕して疎水化度５０％の酸化チタンを得た。
【００５８】
【表１】

【００５９】
【発明の効果】
本発明に従い薄片状の微粒子を添加したフルカラートナーは環境変動に対し極めて安定で、耐久性にも優れ、長期にわたって安定した高画質の画像を提供することが可能である。[0001]
[Industrial application fields]
The present invention relates to a full-color toner for developing an electrostatic image for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like.
[0002]
[Prior art]
In the method of forming an electrostatic latent image on the surface of the photoconductive material by electrostatic means and developing the electrostatic latent image, the storage stability (blocking resistance) of the developer used, transportability, developability, transfer Properties such as property, chargeability and fixability are important. Since full-color toners are required to have translucency and the like, polyester resins are generally used as toner binder resins. Polyester resins have an ester group, a hydroxyl group, and a carboxyl group in the main chain, and thus are easily affected by humidity and have poor durability. For this reason, a toner composed of a polyester resin is inherently poor in environmental stability, and the amount of charge varies greatly depending on the humidity level.
[0003]
In addition, since a full color toner requires good flow characteristics in order to improve development efficiency, a large amount of a fluidizing agent is externally added.
[0004]
In Japanese Patent Application Laid-Open No. 62-113158, hydrophobic silica fine powder is used, in Japanese Patent Application Laid-Open No. 64-62667, titanium oxide fine powder is used, and in Japanese Patent Application Laid-Open No. 3-45978, fluororesin fine powder is used as a developer. The technique of adding is proposed. Japanese Patent Application Laid-Open No. 6-208241 proposes a technique using needle-like titanium oxide, which is different from a normal spherical or irregular shape.
[0005]
In the conventional addition system of hydrophobic silica, the silica fine particles themselves exhibit a strong negative chargeability, and therefore, the increase in charge of the toner under low temperature and low humidity becomes a problem. As the demand for high definition and high image quality in recent years increases in the market, it is indispensable to cope with the reduction in toner diameter. When the particle size is reduced, the surface area per unit weight is increased and the charge amount is increased, which may cause a decrease in image density and deterioration in durability.
[0006]
In the case of titanium oxide fine particles, the surface activity is originally small compared to silica etc., and hydrophobicity is not always sufficient, and the fluidity of the toner changes greatly due to environmental fluctuations, so stable charging, transportability, and developability can be obtained. There is a problem that the image disappears and causes deterioration of the image. It is possible to increase the hydrophobization rate by using a large amount of hydrophobizing agent or using a highly viscous treating agent, etc., but it causes aggregation of particles, etc. There are problems such as lowering.
[0007]
Full-color development is obtained by developing multiple color toners of red, blue, and yellow, and it is necessary for each color toner to be charged to a predetermined value without being affected by the environment. Properties are particularly demanding. Such a request cannot be met by the conventional additives described above.
[0008]
In addition to hydrophobized titanium, hydrophobized silica and resin fine particles, including additives, are generally added to the toner particles by the electrostatic force or van der Waals force of the toner particles and additives. Stirring and mixing machines are often used.
[0009]
However, it is not easy to uniformly disperse such conventionally known additives on the toner surface, but the unadhered additives aggregate on the toner surface. It is difficult to prevent the agglomerates from liberating, so that the triboelectric charge amount of the toner becomes unstable, the image density is not constant, the image has a lot of fog, and the image quality after continuous copying becomes poor. Had problems such as. In addition, carrier spent due to the separation of aggregates is also generated. Although the adhesiveness to the toner can be improved to some extent by using the needle-shaped titanium oxide, the area of the contact surface with the toner is small and still has the above-mentioned problems.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and is to provide a full-color toner for developing an electrostatic image that is hardly affected by changes in temperature or environment and always has stable characteristics such as chargeability and developability. .
[0011]
Another object of the present invention is to provide a full-color toner for developing an electrostatic image that prevents carrier spent and the like, has clear image characteristics without fogging, and has excellent durability stability.
[0012]
[Means for Solving the Problems]
That is, the toner composed of the present invention at least a colorant and a binder resin, to an average particle size of the full-color toner for developing electrostatic images, wherein a. 5 to 40 nm flaky titanium oxide fine particles were externally added.
[0013]
Titanium oxide (titania) added to the toner of the present invention is in the form of flakes, in other words, flat, and due to its unique shape, the adhesion and dispersibility to the toner are compared with conventional fine particles. It is very good and the fine particles adhering to the toner are very difficult to separate. Therefore, the spent of the carrier is prevented, a stable charge can be obtained, and the durability performance is improved.
[0014]
In addition, because of good dispersibility, the surface modification effect of the toner is great, and good results are also obtained in improving fluidity and environmental stability of charging.
[0015]
The titanium oxide used in the present invention can be produced by a wet method, has an average particle diameter of 5 to 40 nm, preferably 5 to 30 nm, and preferably has a fine particle surface hydrophobized in an aqueous system, or further air. It is desirable to use a hydrophobized material in the phase. In addition, the average particle diameter of titanium oxide has shown the average value of the long diameter of the titanium oxide particle by an electron micrograph.
[0016]
In the hydrophobization treatment in the aqueous system, mechanical force is applied to disperse the titanium fine particles into the primary particles, so that the reactivity such as chlorosilanes and disilazanes is generated as a by-product of gas. There is no need to use an excellent coupling agent, and it is also possible to use a high-viscosity treatment agent in which the titanium oxide particles cannot be used together in the gas phase.
[0017]
Therefore, as the treating agent, any of coupling agents, oils, varnishes, organic compounds and the like can be used.
[0018]
Examples of the coupling agent preferably used include a silane coupling agent, a titanium coupling agent, and the like, and particularly preferably used is a silane coupling agent having a general formula:
R ₁ m ₁ SiY ₁ n ₁ [wherein R ₁ is an alkoxy group, m ₁ is an integer of ₁ to 3, Y ₁ is a hydrocarbon group containing an alkyl group, a vinyl group, a glycidoxy group or a methacryl group, n ₁ is 1 to 3], for example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, Examples include isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.
[0019]
The amount of use is 1 to 40 parts by weight, preferably 3 to 30 parts by weight, with respect to 100 parts by weight of titanium fine particles.
[0020]
The silicone oil used in the present invention is not particularly limited, but is represented by the general formula:

Dimethylpolysiloxane type represented by the general formula:

A methylhydropolysiloxane type represented by the general formula:

The methyl phenyl polysiloxane type etc. which are represented by these can be used. Further, if necessary, alkyl modification, amino modification, epoxy modification, epoxy / polyether modification, carboxyl modification, mercapto modification, alcohol modification, fluorine modification and the like may be performed.
[0021]
In the present invention, the silane coupling agent used for treating titanium treated in an aqueous system in the gas phase has a general formula R ₄ m ₃ SiY ₂ n ₅ [wherein R ₄ is an alkoxy group, a chlorine atom, m ₃ is an integer of 1 to 3, Y ₂ is an alkyl group, a vinyl group, a glycidoxy group, a hydrocarbon group containing a methacryl group, and n ₅ is an integer of 3 to 1, for example, typically dimethyl Dichlorosilane, trimethylchlorosilane, allidimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinyl Examples include chlorosilane and dimethylvinylchlorosilane.
[0022]
As the silane coupling agent treatment of the fine powder, a dry treatment in which the vaporized silane coupling agent is reacted with the fine powder made into a cloud by stirring or the like can be employed.
[0023]
Usually, a full color toner is prepared as particles in which a colorant such as cyan, magenta or yellow and other desired fluidizing agent are dispersed in a binder resin. In the present invention, the above-mentioned flaky titania is used as a fluidizing agent.
[0024]
The resin usually used as a binder for a full-color toner is an epoxy resin or a polyester resin, and among them, a polyester resin having a strong negative charge and excellent fixability is preferable. In particular, those having sharp melting characteristics are preferred, fumaric acid, maleic acid, maleic anhydride comprising a bisphenol derivative or substituted diol component and a divalent or higher carboxylic acid or acid anhydride or lower alkyl ester thereof. A polyester resin obtained by co-condensation polymerization with a carboxylic acid component such as acid, phthalic acid, terephthalic acid or trimellitic acid is most suitable.
[0025]
More preferably, the number average molecular weight (Mn) is 3000 to 10000, preferably 3000 to 7000, and the weight average molecular weight (Mw) is 7000 to 50000, preferably 7000 to 15000 by molecular weight distribution measurement by gel permeation chromatography (GPC). Molecular weight distribution (Mw / Mn) is 1.5 to 5.0, preferably 2.0 to 4.0, endothermic peak value (Tg) by DSC is 50 to 70 ° C., softening temperature (Tm) by flow tester is 90 A linear polyester resin having a temperature of ˜110 ° C. is preferred. If these various characteristics are not satisfied, it becomes impossible to sufficiently satisfy the translucency of the toner, the dispersibility of the colorant or the charge control agent, the fixability and the heat resistance. Specifically, by setting the molecular weight distribution in the above range, it is possible to improve the sharp melt characteristics of the toner at the time of fixing, and to improve the translucency. Further, by setting the glass transition point and the softening point in the above ranges, sufficient heat resistance and fixability can be imparted to the toner.
[0026]
Further, the polyester resin does not substantially contain a tetrahydrofuran-insoluble component and is soluble in tetrahydrofuran. Containing a tetrahydrofuran-insoluble component is not preferable because it causes the light transmittance of the toner to be inhibited.
[0027]
The toner of the present invention is conventionally known, for example, in addition to the binder resin and colorant, a predetermined amount of a charge control agent and other desired additives are added, mixed, kneaded, pulverized and classified. As a result, particles having an average particle diameter of 6 to 10 μm are obtained.
[0028]
As the colorant, various colorants known as colorants for full-color toners can be used. For example, as a blue dyeing pigment: C.I. I. 74100 (metal-free phthalocyanine blue), C.I. I. 74160 (phthalocyanine blue), C.I. I. 74180 (Fast Sky Blue) etc .;
As a red dyeing pigment: C.I. I. 12055 (Starlin I), C.I. I. 12075 (permanent orange), C.I. I. 12175 (Risor Fast Orange 3GL), C.I. I. 12305 (Permanent Orange GTR), C.I. I. 11725 (Hansa Yellow 3R), C.I. I. 21165 (Vulcan Fast Orange GG), C.I. I. 21110 (Benzidine Orange G), C.I. I. 12120 (Permanent Red 4R), C.I. I. 1270 (Para Red), C.I. I. 12085 (Fire Red), C.I. I. 12315 (Brilliant Fast Scarlet), C.I. I. 12310 (Permanent Red F2R), C.I. I. 12335 (Permanent Red F4R), C.I. I. 12440 (Permanent Entred FRL), C.I. I. 12460 (Permanent Red FRLL), C.I. I. 12420 (Permanent Red F4RH), C.I. I. 12450 (Light Fast Red Toner B), C.I. I. 12490 (Permanent Carmine FB), C.I. I. 15850 (brilliant carmine 6B) etc .;
As yellow dyes: C.I. I. 10316 (Naphthol Yellow S), C.I. I. 11710 (Hansa Yellow 10G), C.I. I. 11660 (Hansa Yellow 5G), C.I. I. 11670 (Hanza Yellow 3G), C.I. I. 11680 (Hansa Yellow G), C.I. I. 11730 (Hansa Yellow GR), C.I. I. 11735 (Hansa Yellow A), C.I. I. 11740 (Hansa Yellow RN), C.I. I. 12710 (Hansa Yellow R), C.I. I. 12720 (Pigment Yellow L), C.I. I. 21090 (benzidine yellow), C.I. I. 21095 (Benzidine Yellow G), C.I. I. 21100 (benzidine yellow GR), C.I. I. 20040 (Permanent Yellow NCG), C.I. I. 21220 (Vulcan Fast Yellow 5), C.I. I. A typical example is 21135 (Vulcan Fast Yellow R).
[0029]
These colorants can be used singly or in combination, but it is desirable to use 1 to 10 parts by weight, more preferably 2 to 5 parts by weight with respect to 100 parts by weight of the binder resin contained in the toner particles. . That is, when the amount is more than 10 parts by weight, the fixing property and translucency of the toner are lowered. On the other hand, when the amount is less than 1 part by weight, a desired image density may not be obtained.
[0030]
Examples of the charge control agent include chromium complex salts such as E-81 (manufactured by Orient Chemical Industries), zinc complex salts such as E-84 (manufactured by Orient Chemical Industries), and aluminum such as E-86 (manufactured by Orient Chemical Industries). A calixarene compound such as a complex salt or E-89 (manufactured by Orient Chemical Co., Ltd.) can be used.
The amount of these charge control agents is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the resin in the toner.
[0031]
If necessary, the toner of the present invention may contain a fluidizing agent such as silica, a cleaning aid such as resin beads, large-diameter silica for improving transferability, and the like.
[0032]
In the present invention, the toner particles obtained by kneading, pulverizing and classifying the binder resin and the colorant are mixed (externally added) to obtain a toner. The mixing can be performed by conventional methods and conditions such as a mechanical pulverization mixing method. For example, a mixer such as a Henschel mixer, a super mixer, a powder mixer, or a homogenizer can be used.
[0033]
The flaky titania is usually added and mixed in an amount of 0.5 to 2.0% by weight, preferably 0.5 to 1.5% by weight, based on the toner. If the amount added is too small, the desired fluidity and environmental properties cannot be obtained, leading to image deterioration. If the amount is too large, the charge amount is reduced and fogging or the like is caused.
[0034]
The toner externally added with flaky titania obtained as described above is used as a two-component developer together with a carrier.
[0035]
As the carrier, it is preferable to use a resin-coated carrier.
As the carrier core material, one having a size of at least 20 μm (average particle diameter) is used from the viewpoint of prevention of carrier adhesion (scattering) to the electrostatic latent image carrier, and the image quality is lowered such as prevention of carrier streaks. From the viewpoint of prevention, use a thing of 100 μm at most. Specific materials include those known as two-component carriers for electrophotography, such as metals such as ferrite, magnetite, iron, nickel, and cobalt, and these metals and zinc, antimony, aluminum, lead, tin, bismuth, beryllium, manganese Alloys or mixtures with metals such as selenium, tungsten, zirconium and vanadium, metal oxides such as iron oxide, titanium oxide and magnesium oxide, nitrides such as chromium nitride and vanadium nitride, carbides such as silicon carbide and tungsten carbide Mixtures of these and ferromagnetic ferrites, and mixtures thereof can be applied.
[0036]
Examples of the carrier core coating resin (conductive layer, adhesive layer, surface protective layer) include, for example, polystyrene resins, poly (meth) acrylic resins, polyolefin resins, polyamide resins, polycarbonate resins, and polyethers. Resins, polysulfonic acid resins, polyester resins, epoxy resins, polybutyral resins, urea resins, urethane / urea resins, silicone resins, Teflon resins, and other thermoplastic resins and thermosetting resins, and Mixtures thereof, copolymers of these resins, block polymers, graft polymers, polymer blends, and the like can be used.
[0037]
Hereinafter, the present invention will be further described with reference to examples. In the examples, the expression “parts” means “parts by weight” unless otherwise specified.
[0038]
【Example】
Example of toner production : 100 parts of polyester resin (number average molecular weight (Mn): 5,000, weight average molecular weight (Mw): 10,000, Mw / Mn: 2.0, softening point (Tm): 105 ° C, glass transition point: 60 ° C, THF-insoluble component: 0%)
Charge control agent (Bontron E-84 (Orient Chemical Co., Ltd.)) 1 part Brilliant Carmine 6B 4 parts [0039]
The above mixture was sufficiently mixed with a Henschel mixer and melt kneaded using a twin screw extruder. The kneaded product was cooled and then coarsely pulverized. The coarsely pulverized product was finely pulverized with an air jet pulverizer. Further, the obtained finely pulverized product was classified by an airflow type pulverizer to obtain toner particles having a volume average particle size (D ₅₀ ) of 8.0 μm.
[0040]
Production example of carrier 80 parts by weight of styrene-acrylic copolymer (1.5: 7.0: 1.0: 0.5) composed of styrene, methyl methacrylate, 2-hydroxyethyl acrylate and methacrylic acid And 20 parts by weight of butylated melamine resin were diluted with toluene to prepare a styrene-acrylic resin solution having a solid ratio of 2%.
[0041]
Using the sintered ferrite powder (F-300, average particle size: 50 μm, manufactured by Powder Tech Co., Ltd.) as the core material, the styrene-acrylic resin solution was applied with a spiner coater (Okada Seiko Co., Ltd.) and dried. The applied ferrite powder was baked by leaving it in a hot air circulation oven at 140 ° C. for 2 hours.
[0042]
After cooling, the ferrite powder bulk was pulverized using a sieve shaker equipped with a screen mesh having openings of 210 μm and 90 μm to obtain resin-coated ferrite powder.
[0043]
The above coating, firing and crushing were further repeated three times for this ferrite powder to obtain a resin-coated carrier. The average particle size of the obtained carrier was 52 μm.
[0044]
Example 1
To 100 parts of the particles obtained in the above toner production example, 1.0 part of hydrophobic flaky titania fine particles (particle size: 0.015 to 0.02 μm, STT-30A; manufactured by Titanium Industry Co., Ltd.) was added and Henschel was added. The toner was obtained by mixing with a mixer.
[0045]
To 5 parts of the obtained toner, the carrier obtained in the carrier production example was mixed so that the total amount would be 100 parts to obtain a developer.
[0046]
Using the developer thus obtained, a commercially available full-color copying machine (CF-80; manufactured by Minolta Co., Ltd.) was used for image printing and a durability test for 5000 sheets (5K sheets) under the following environments.

[0047]
Under each environment, the images after the endurance were as good as those in the initial stage in terms of fog, sharpness and image density. The results of image drawing and durability test are summarized in Table 1.
[0048]
Each evaluation in Table 1 was performed as follows.
-The image density (ID) value was rounded off to the third decimal place.
[0049]
・ Comparison evaluation with Kabli Minolta limit sample sample and ranked as follows.
A: Rank 5 (no fogging at all).
○: Rank 4 (almost no fogging).
Δ: Rank 3 (slight fogging is observed, but there is no practical problem).
X: Ranks 1 to 2 (a lot of fogging and practical problems).
[0050]
-Durability characteristics After measurement under each environment (after 5K), they were comprehensively evaluated and ranked as follows.
A: No problem at all.
○: There is no problem in practical use although some characteristics are changed.
X: There is a problem in practical use.
[0051]
OHP translucency OHP translucency was visually observed and ranked as follows.
○: No problem in practical use.
[0052]
Example 2
A developer was prepared and tested in the same manner as in Example 1 except that the amount of hydrophobic flaky titania fine particles (STT-30A; manufactured by Titanium Industry Co., Ltd.) was 0.6 parts. The results are summarized in Table 1.
[0053]
Example 3
A developer was prepared and tested in the same manner as in Example 1 except that the amount of hydrophobic flaky titania fine particles (STT-30A; manufactured by Titanium Industry Co., Ltd.) was 1.5 parts. The results are summarized in Table 1.
[0054]
Comparative Example 1
A developer was prepared and tested in the same manner as in Example 1 except that 1.0 part of hydrophobic amorphous granular titania fine particles (T-805; manufactured by Degussa) was added in place of the flaky titania fine particles. . The results are summarized in Table 1.
[0055]
Comparative Example 2
A developer was prepared and tested in the same manner as in Example 1 except that 1.0 part of hydrophobic amorphous granular titania fine particles (TTO-51C; manufactured by Ishihara Sangyo Co., Ltd.) was added in place of the flaky titania fine particles. did. The results are summarized in Table 1.
[0056]
Comparative Example 3
A developer was prepared and tested in the same manner as in Example 1 except that 1.0 part of hydrophobic spherical titania fine particles obtained as described below was added in place of the flaky titania fine particles in Example 1. The results are summarized in Table 1.
[0057]
Preparation of spherical titania fine particles:
Ilmenite ore was dissolved in sulfuric acid, cooled, and then centrifuged. The centrifuged stock solution was hydrolyzed with heating, and the resulting titanium hydroxide was baked in a rotary furnace (350 to 400 ° C.) to obtain spherical hydrophilic titanium oxide (particle size: 0.04 to 0.05 μm). .
While the obtained titanium oxide was stirred and mixed in an aqueous system, a coupling agent (n-C ₅ H ₁₁ Si (OCH ₃ ) ₃ ) was added and mixed so as to be 20% with respect to the titanium oxide fine particles.
The mixture was dried and crushed to obtain titanium oxide having a hydrophobicity of 50%.
[0058]
[Table 1]

[0059]
【The invention's effect】
The full-color toner to which flaky fine particles are added according to the present invention is extremely stable against environmental fluctuations, is excellent in durability, and can provide a stable and high-quality image over a long period of time.

Claims (3)

The full-color toner comprised of at least a colorant and a binder resin, the average particle diameter. 5 to 40 nm of flaky titanium oxide fine particles externally added to the full-color toner for developing electrostatic images, characterized in that the. The titanium oxide fine particles have an average particle size of 5 to 5 30nm The full-color toner for developing electrostatic images according to claim 1, wherein the titanium oxide fine particles are subjected to a hydrophobic treatment. The number average molecular weight of the binder resin is 3000 ~ 10000 The weight average molecular weight is 7000 ~ 50000 , Weight average molecular weight / number average molecular weight is 1.5 ~ 5, glass transition point 50 ~ 70 ℃ and softening temperature 90 ~ 110 3. The full-color toner for developing an electrostatic image according to claim 1, wherein the toner is at a temperature of 0.degree.