JP4020802B2 - Toner and method for producing the same - Google Patents

Description

【００１６】
〔式中、Ｔｗは見掛けのずり応力［Ｐａ］を、Ｄｗは見掛けのずり速度［ｓ^-1］を、Ｒはノズルの半径［ｍ］を、Ｌはノズルの長さ［ｍ］を、Ｐは試験圧力［Ｐａ］を、Ｑは流れ値［ｍ^-3・ｓ^-1］を、πは円周率を、それぞれ示す。〕
【００１７】
本発明のトナーでは、バインダ樹脂の主成分として、ポリエステル樹脂と結晶性を有する樹脂とが用いられている。このバインダ樹脂中に結晶性を有する樹脂（例えば、結晶性ポリエステル樹脂等）が含まれていない場合には、トナーの流出開始温度Ｔｉが高くなって、軟化温度Ｔｓとの差Ｔｓ−Ｔｉが大きくなる傾向があることから、耐ブロッキング性は良好であるものの、低温定着性が低下するという問題が生じる。
また、バインダ樹脂中に結晶性を有する樹脂（例えば、結晶性ポリエステル樹脂等）が含まれており、かつ非晶質ポリエステル樹脂と結晶性ポリエステル樹脂との樹脂同士の相溶性が高い場合には、差Ｔｓ−Ｔｉが２０℃を超えるおそれがある。この場合、トナーの低温定着性は良好であったとしても、結晶性ポリエステル樹脂の一部が非晶質化することによって結晶性ポリエステル樹脂としての特性を維持できなくなることから、結果的にトナーの耐ブロッキング性が低くなるといった問題を生じることになる。なお、一般に、トナーのバインダ樹脂中に結晶性を有する樹脂が含まれるときは、トナーのガラス転移温度Ｔｇが低下して、耐ブロッキング性が低下する傾向にある。
【００１８】
これに対し、バインダ樹脂中に結晶性を有する樹脂を含んでおり、かつ差Ｔｓ−Ｔｉが小さいトナーは、融け始めてもすぐに固まることから低温定着性に優れており、なおかつ結晶性ポリエステル樹脂の特性も維持されることから、耐ブロッキング性にも優れたものとなる。
上記本発明のトナーは、前述のように、そのＶ_Ti／Ｖ_TsとＴｓ−Ｔｉとを上記範囲内に設定するためにも、バインダ樹脂中に結晶性を有するものを含んでいるのが好ましい。具体的には、バインダ樹脂として使用するポリエステル樹脂が結晶性ポリエステル樹脂を含むものであるのが好ましい。
【００１９】
本発明に係るトナーの製造方法は、少なくともポリエステル樹脂と、結晶性を有する樹脂と、着色剤と、ワックス成分とを溶融混練して得られる、流出開始温度Ｔｉにおける粘度Ｖ_Tiと軟化温度Ｔｓにおける粘度Ｖ_Tsとの比Ｖ_Ti／Ｖ_Tsが５〜２０で、かつ上記Ｔｉと上記Ｔｓとの差Ｔｓ−Ｔｉが１０〜２０℃である混練物を、冷却後に粉砕することを特徴とする。
かかる製造方法によれば、耐オフセット性、低温定着性および耐ブロッキング性のいずれについても良好なトナーを製造することができる。
【００２０】
【発明の実施の形態】
次に、本発明のトナーについて詳細に説明する。
〔バインダ樹脂〕
本発明のトナーにおけるバインダ樹脂は、ポリエステル樹脂を含むものであり、かつ当該バインダ樹脂を用いてトナーを作製した場合に、その流出開始温度Ｔｉと軟化温度Ｔｓとの差「Ｔｓ−Ｔｉ」や、Ｔｉにおける粘度Ｖ_TiとＴｓにおける粘度Ｖ_Tsとの比「Ｖ_Ti／Ｖ_Ts」を前述の範囲に設定し得るものであるほかは、特に限定されるものではない。従って、上記要件を満たし得るものであるほかは、従来公知の種々の樹脂から適宜選択することができる。
なかでも、バインダ樹脂の主成分として非晶質のポリエステル樹脂を使用し、かつ結晶性ポリエステル樹脂を含有させるのが、トナーについての上記要件を満足させる上で好ましい。
【００２１】
（非晶質ポリエステル樹脂）
本発明において、バインダ樹脂に用いられるポリエステル樹脂は、２価以上の多価アルコールからなるアルコール成分と、カルボン酸、カルボン酸無水物、カルボン酸エステル等のカルボン酸成分とを縮重合反応させることによって得られるものである。
このポリエステル樹脂のうち非晶質のものについて、その多価アルコール成分と多価カルボン酸成分とは特に限定されるものではなく、従来公知の種々のものを使用することができる。
【００２２】
本発明において、非晶質のポリエステル樹脂とは、その軟化温度Ｔｓと、ＤＳＣによる融解熱の最大ピーク温度Ｔｍ_MAX の比Ｔｓ／Ｔｍ_MAX が１．１〜４．０、好ましくは１．５〜３．０の範囲にあるものをいう。
非晶質ポリエステル樹脂の軟化温度Ｔｓは、特に限定されるものではないが、７０〜１８０℃であるのが好ましい。非晶質ポリエステル樹脂の融解熱最大ピーク温度Ｔｍ_MAX は、特に限定されるものではないが、５０〜８５℃であるのが好ましい。また、ガラス転移温度Ｔｇは、特に限定されるものではないが、４５〜８０℃であるのが好ましい。
【００２３】
（結晶性を有する樹脂）
本発明のトナーにおけるバインダ樹脂は、前述のように、非晶質のポリエステル樹脂をその主成分として含有し、かつ結晶性を有する樹脂を含有するものであるのが好ましい。
ここで、結晶性を有する樹脂としては特に限定されるものではなく、例えば結晶性ポリエステル樹脂、ビニル系樹脂、バインダ樹脂として好適な融点（８０〜１５０℃程度）を有する脂肪族結晶性ポリエステル樹脂等を用いることができる。
非晶質のポリエステル樹脂と、結晶性を有する樹脂との相溶性が高いと、非晶質のポリエステル樹脂中にて、結晶性を有する樹脂が非晶質化してしまい、その結晶性が損なわれるおそれがある。そこで、両樹脂には、結晶性樹脂の非晶質化を生じることがない程度に、その相溶性が低いことが求められる。具体的には、両樹脂間の溶解度定数（Solubility Parameter，ＳＰ値）の差が０．１〜１．５程度、好ましくは０．１〜１．０程度であることが望まれる。
【００２４】
（結晶性ポリエステル樹脂）
上記ポリエステル樹脂のうち結晶性のものについて、その多価アルコール成分と多価カルボン酸成分とは特に限定されるものではなく、従来公知の種々のものを使用することができる。
しかし、結晶性ポリエステル樹脂の軟化温度Ｔｓや、その結晶性の程度を適切な範囲に調節する上で、多価アルコール成分には炭素数２〜６のジオールを８０モル％以上、好ましくは９０〜１００モル％以上の割合で含有するものを使用するのが好ましく、多価カルボン酸成分にはフマル酸を８０モル％以上、好ましくは８５〜１００モル％以上の割合で含有するものを使用するのが好ましい。
【００２５】
本発明において、結晶性のポリエステル樹脂とは、その軟化温度Ｔｓと、示差走査熱量分析（ＤＳＣ）による融解熱の最大ピーク温度Ｔｍ_MAX の比Ｔｓ／Ｔｍ_MAX が０．９以上、１．１未満、好ましくは０．９８〜１．０５の範囲にあるものをいう。
結晶性ポリエステル樹脂の軟化温度Ｔｓは、特に限定されるものではないが、８５〜１５０℃であるのが好ましく、１００〜１４０℃であるのがより好ましい。また、結晶性ポリエステル樹脂の流出開始温度Ｔｉは、特に限定されるものではないが、１００〜１３０℃であるのが好ましく、１１０〜１３０℃であるのがより好ましい。
なお、結晶性ポリエステル樹脂の流出開始温度Ｔｉおよび軟化温度Ｔｓは、前述の、トナーについての「流出開始温度Ｔｉ」と「軟化温度Ｔｓ」の測定方法に準じて測定したものである。
【００２６】
結晶性ポリエステル樹脂の融解熱最大ピーク温度Ｔｍ_MAX は、特に限定されるものではないが、７７〜１５０℃であるのが好ましく、９０〜１４０℃であるのがより好ましい。
結晶性ポリエステル樹脂のテトラヒドロフラン（ＴＨＦ）可溶分の数平均分子量＜Ｍｎ＞は、トナーの耐ブロッキング性やその粘度を適切な範囲に設定するという観点から、５００〜６，０００であるのが好ましく、５００〜５，０００であるのがより好ましい。
【００２７】
（非晶質ポリエステル樹脂と、結晶性を有する樹脂との混合比率）
本発明に用いられるバインダ樹脂において、非晶質ポリエステル樹脂と結晶性を有する樹脂との含有割合は、トナーの流出開始温度Ｔｉと軟化温度Ｔｓとの差「Ｔｓ−Ｔｉ」や、Ｔｉにおける粘度Ｖ_TiとＴｓにおける粘度Ｖ_Tsとの比「Ｖ_Ti／Ｖ_Ts」を前述の範囲に設定するという観点から設定されるものである。
非晶質ポリエステル樹脂と結晶性を有する樹脂との含有割合は、個々の樹脂の物性値に応じて変動するものであって、それゆえこれに限定されるものではないが、通常、９５：５〜６０：４０（重量比）とするのが好ましく、８０：２０〜７０：３０（重量比）とするのがより好ましい。
【００２８】
〔着色剤〕
本発明のトナーに含まれる着色剤は特に限定されるものではなく、トナーに要求される色味等に応じて、従来公知の種々の着色剤から適宜選択して使用することができる。着色剤の含有量も特に限定されるものではなく、常法に応じて適宜設定すればよい。
【００２９】
〔ワックス〕
本発明のトナーに含まれるワックスは、当該ワックスと前述のバインダ樹脂とを用いてトナーを作製した場合に、その流出開始温度Ｔｉと軟化温度Ｔｓとの差「Ｔｓ−Ｔｉ」や、Ｔｉにおける粘度Ｖ_TiとＴｓにおける粘度Ｖ_Tsとの比「Ｖ_Ti／Ｖ_Ts」を前述の範囲に設定し得るものであるほかは、特に限定されるものではない。従って、上記要件を満たし得るものであるほかは、従来公知の種々のワックスから適宜選択して使用することができる。
本発明に用いられるワックスの具体例としては、例えばカルナウバワックス、ライスワックス等の天然ワックス；ポリプロピレンワックス、ポリエチレンワックス、エステル系ワックス、フィッシャートロプシュワックス等の合成ワックスなどが挙げられる。
【００３０】
〔その他の成分〕
本発明のトナーにおいて、着色剤やワックスとともにバインダ樹脂中に配合される他の成分としては、例えば電荷制御剤、各種安定剤等が挙げられる。
【００３１】
電荷制御剤としては、トナーの帯電極性に応じて正電荷制御用と負電荷制御用のいずれかが用いられる。これらの電荷制御剤は特に限定されるものではなく、トナー用として従来公知の種々の電荷制御剤が使用可能である。電荷制御剤の配合量も特に限定されるものではなく、常法に応じて適宜設定すればよい。通常、バインダ樹脂１００重量部に対して１０重量部以下、好ましくは０．１〜１０重量部、より好ましくは０．５〜５重量部の範囲で設定される。
【００３２】
〔トナーの製造方法等〕
本発明のトナーは、例えば、上記バインダ樹脂に、着色剤、ワックス、その他の成分を配合して、乾式ブレンダー、ヘンシェルミキサー、ボールミル等によって均質に予備混合した後、こうして得られた混合物を、バンバリミキサー、ロール、１軸または２軸の混練押出機等の混練装置を用いて均一に溶融、混練し、さらに混練物を冷却して粉砕し、必要に応じて分級する、いわゆる粉砕法によって製造することができる。
【００３３】
本発明のトナー（トナー粒子）は、必要に応じて、シリカ、アルミナ、酸化チタン等の無機系微粒子が外添（外部添加）されたトナーとして使用してもよい。外添剤としての無機系微粒子は特に限定されるものではなく、トナーに要求される滑性等の特性に応じて、従来公知の種々のものを適宜選択して使用することができる。
また、本発明のトナーは、磁性キャリアと混合して２成分系現像剤として使用することもできる。磁性キャリアについても特に限定されるものではなく、現像剤に要求される帯電特性や電気特性等に応じて、従来公知の種々のものを適宜選択して使用することができる。
【００３４】
トナー（トナー粒子）の粒径は特に限定されるものではないが、通常、３〜１２μｍの範囲で、好ましくは５〜１０μｍの範囲で設定される。形成画像の高画質化を目的とした小粒径のトナーの場合には、トナー粒子の粒径が４〜８μｍ程度であるのが好ましい。
【００３５】
【実施例】
次に、実施例および比較例を挙げて、本発明のトナーについて説明する。
〔トナーおよび２成分系現像剤の製造〕
実施例および比較例に使用した非晶質ポリエステル樹脂は、表１に示すとおりである。
多価アルコール成分としての「ビスフェノールＡ−ＰＯ付加物」と「ビスフェノールＡ−ＥＯ付加物」は、それぞれビスフェノールＡにプロピレンオキシド（ＰＯ）またはエチレンオキシド（ＥＯ）を付加してなるものである。
【００３６】
【表１】

【００３７】
表１中、非晶質ポリエステル樹脂の流出開始温度（Ｔｉ）と軟化温度（Ｔｓ）は、いずれもフローテスター〔（株）島津製作所製の型番「ＣＦＴ−５００Ａ」〕を使用して、前述の「トナーの軟化温度Ｔｓ」の測定方法と同様にして求めたものである。
実施例および比較例に使用した結晶性ポリエステル樹脂は、表２に示すとおりである。
【００３８】
【表２】

【００３９】
表２中、結晶性ポリエステル樹脂の流出開始温度（Ｔｉ）と軟化温度（Ｔｓ）は、いずれも非晶質ポリエステル樹脂の場合と同様にして求めたものである。
【００４０】
（実施例１）
バインダ樹脂として、表１にａで示す高分子量の非晶質ポリエステル樹脂６０重量部と、表１にｘで示す低分子量の非晶質ポリエステル樹脂２０重量部と、表２にＡで示す結晶性ポリエステル樹脂２０重量部との混合物を用いた。
上記樹脂混合物１００重量部に対して、着色剤としてのカーボンブラック〔デグッサ（Ｄｅｇｕｓｓａ）社製の商品名「Ｎｉｐｅｘ−６０」〕９重量部、正帯電型電荷制御剤〔スチレンアクリル系の第４級アンモニウム塩を主成分とするもの。藤倉化成（株）製の商品名「ＦＣＡ−２２２Ｐ」〕２重量部、ポリプロピレン系ワックス〔三洋化成（株）製の商品名「１００ＴＳ」、融点１３０℃〕１．５重量部およびエステル系ワックス〔日本油脂（株）製の商品名「ＷＥ−３」、融点７５℃〕３重量部を添加し、上記各成分を２軸押出機にて溶融混練した。次いで、この混練物をジェットミルで粉砕し、風力分級機で分級して、平均粒径８μｍのトナー粒子を得た。
【００４１】
さらに、このトナー粒子１００重量部に対して、平均粒径７ｎｍの疎水性シリカ微粒子を０．８重量部外添（外部添加）して、ヘンシェルミキサーで混合することにより、トナーを得た。
次いで、上記のトナーと、重量平均径が６０μｍであるフェライト粒子からなる磁性キャリアとを撹拌、混合して、トナー濃度（Ｔ／Ｄ）が５重量％の２成分系現像剤を得た。
【００４２】
（実施例２）
樹脂ｘに代えて、表１にｙで示す低分子量の非晶質ポリエステル樹脂２０重量部を使用し、カーボンブラックの配合量を１２重量部とし、電荷制御剤の配合量を４重量部とし、かつ、ポリプロピレン系ワックス〔前出の「１００ＴＳ」〕およびエステル系ワックス〔前出の「ＷＥ−３」〕に代えて、フィッシャートロプシュワックス〔日本精蝋（株）製の商品名「ＭＤＰ−７０００」、融点１０１℃〕４．５重量部を使用したほかは実施例１と同様にして、トナー粒子、トナーおよび２成分系現像剤の製造を行った。
（実施例３）
樹脂ａに代えて、表１にｂで示す高分子量の非晶質ポリエステル６０重量部を使用したほかは実施例１と同様にして、トナー粒子、トナーおよび２成分系現像剤の製造を行った。
【００４３】
（比較例１）
バインダ樹脂として、表１にｂで示す高分子量の非晶質ポリエステル樹脂７０重量部と、表１にｘで示す低分子量の非晶質ポリエステル樹脂１５重量部と、表２にＢで示す結晶性ポリエステル樹脂１５重量部との混合物を使用し、かつ、ポリプロピレン系ワックス〔前出の「１００ＴＳ」〕およびエステル系ワックス〔前出の「ＷＥ−３」〕に代えて、フィッシャートロプシュワックス〔前出の「ＭＤＰ−７０００」〕４．５重量部を使用したほかは実施例１と同様にして、トナー粒子、トナーおよび２成分系現像剤の製造を行った。
【００４４】
（比較例２〜４）
結晶性ポリエステル樹脂として、樹脂Ｂに代えて表２にＣで示す樹脂を使用し、かつ、低分子量の非晶質ポリエステル樹脂と結晶性ポリエステル樹脂の配合量をそれぞれ変更したほかは比較例１と同様にして、トナー粒子、トナーおよび２成分系現像剤の製造を行った。
（比較例５〜８）
結晶性ポリエステル樹脂の種類を変更したほかは比較例１と同様にして、トナー粒子、トナーおよび２成分系現像剤の製造を行った。
【００４５】
（比較例９）
低分子量の非晶質ポリエステル樹脂として樹脂ｘに代えて樹脂ｙを使用し、当該樹脂ｙの配合量を４０重量部とし、結晶性ポリエステル樹脂を配合（使用）せず、カーボンブラックの配合量を９重量部とし、かつ、電荷制御剤の配合量を２重量部としたほかは実施例２と同様にして、トナー粒子、トナーおよび２成分系現像剤の製造を行った。
【００４６】
（比較例１０）
低分子量の非晶質ポリエステル樹脂ｘの配合量を４０重量部とし、かつ、結晶性ポリエステル樹脂を配合（使用）しなかったほかは実施例１と同様にしてトナー粒子、トナーおよび２成分系現像剤の製造を行った。
（比較例１１）
高分子量の非晶質ポリエステル樹脂ｂ、低分子量の非晶質ポリエステル樹脂ｘおよび結晶性ポリエステル樹脂Ｃの配合量をそれぞれ変更したほかは比較例２と同様にしてトナー粒子、トナーおよび２成分系現像剤の製造を行った。
【００４７】
（比較例１２）
ワックスの配合量を、上記ポリプロピレン系ワックス（前出の商品名「１００ＴＳ」）１．５重量部と、上記エステル系ワックス（前出の商品名「ＷＥ−３」５重量部としたほかは（すなわち、バインダ樹脂１００重量部に対するワックスの総配合量を６．５重量部としたほかは）、実施例１と同様にして、トナー粒子、トナーおよび２成分系現像剤の製造を行った。
【００４８】
（比較例１３）
樹脂ａに代えて、表１にｂで示す高分子量の非晶質ポリエステル６０重量部を使用したほかは実施例２と同様にして、トナー粒子、トナーおよび２成分系現像剤の製造を行った。
上記実施例および比較例におけるトナー粒子の組成を表３に示す。
【００４９】
【表３】

【００５０】
＊１：実施例１、３および比較例１０、１２におけるワックスの配合量は、２種類のワックスの総量を示す。
＊２：比較例１１におけるワックスの配合量は、ワックス内添樹脂に含まれるワックスの量を示すものである。
実施例および比較例で得られたトナーの流出開始温度Ｔｉ（℃）、軟化温度Ｔｓ（℃）、ＴｉとＴｓとの差Ｔｓ−Ｔｉ（℃）、Ｔｉにおけるトナーの粘度Ｖ_Ti（Ｐａ・ｓ）、Ｔｓにおけるトナーの粘度Ｖ_Ts（Ｐａ・ｓ）およびＶ_TiとＶ_Tsとの比Ｖ_Ti／Ｖ_Tsの測定・算出結果については、下記表４に示す。
【００５１】
〔トナーの物性評価試験〕
（耐ブロッキング性の評価）
上記の実施例および比較例で得られたトナー（トナー粒子に外添剤を付加したもの）を５８℃で３時間放置し、放置後のトナーを用いて下記の試験を行うことによって、ブロッキング現象（トナーの融着）の有無を確認した。
パウダーテスターによる試験の方法は次のとおりである。メッシュの大きさが異なる三種の篩（メッシュサイズ１４０／２３５／３３０）を上からこの順に重ねて、正確に秤量したトナー５ｇを最上段の篩（メッシュサイズ１４０）上に載置した。次いで、ホソカワミクロン社製のパウダーテスターを用いて、目盛り６の振動数設定で３０秒間振動させた後、最上段の篩に残存したトナーを採取し、その重量を測定した。
最上段の篩に残存したトナーの重量が、最初に秤量したトナー（５ｇ）の３０重量％未満であれば、耐ブロッキング性が良好であるとし、逆に３０重量％以上であれば、耐ブロッキング性が不良であるとした。
【００５２】
（定着性の評価）
上記の実施例および比較例で得られた２成分系現像剤を用いて、電子写真複写機〔京セラミタ（株）製の型番「Ｃｒｅａｇｅ７３４０」の改造機〕で画像形成試験（複写処理）を行った。
試験は、Ａ４サイズの黒ベタ原稿を複写することによって行い、トナーの定着温度は、１４０℃を基準に５℃単位で昇温または降温させた。
【００５３】
(a) 耐オフセット性の評価
上記の複写処理において、トナーのオフセット現象が生じているか否かを、目視で確認した。
(b) 定着率の測定
上記の複写処理において、定着温度を１４０℃としたときの複写画像の画像濃度（Ａ）を測定した。一方、軟鋼製の分銅（直径５０ｍｍ、重量４００ｇ）の底面に晒を両面テープで固定してなる定着性測定用デバイスを用いて、当該複写画像の表面を自重で５往復させた後、複写画像の画像濃度（Ｂ）を測定した。次いで、両画像濃度（Ａ），（Ｂ）を用いて、下記式により定着率（％）を算出した。なお、画像濃度の測定には、反射濃度計（東京電色社製の型番「ＴＣ−６Ｄ」を使用した。
【００５４】
定着率＝〔画像濃度（Ｂ）／画像濃度（Ａ）〕×１００
定着率は９８％以上であることが求められ、９８％を下回るものについては、定着性が不十分であるとした。
【００５５】
(c) 最低定着温度の測定
定着温度を変えて複写処理を行い、かつ上記(b) の方法にて定着率を測定することにより、定着率を９８％とすることができるときの定着温度（℃）を求めて、これを最低定着温度とした。
最低定着温度は極力低いことが好ましく、具体的には１３０℃以下、好ましくは１２０℃以下である。
上記トナーの物性評価試験の結果を表４〜６に示す。
【００５６】
【表４】

【００５７】
【表５】

【００５８】
【表６】

【００５９】
表４〜６より明らかなように、トナーの流出開始温度Ｔｉと軟化温度Ｔｓとの差Ｔｓ−Ｔｉ（℃）と、トナーのＴｉにおける粘度Ｖ_TiとＴｓにおける粘度Ｖ_Tsとの比Ｖ_Ti／Ｖ_Tsと、の両方が本発明の範囲に設定されてなる実施例１および２のトナーを用いたときには、耐ブロッキング性、耐オフセット性および低温定着性のいずれについても良好な結果を得ることができた。
これに対し、差Ｔｓ−Ｔｉと比Ｖ_Ti／Ｖ_Tsのいずれかが本発明の範囲を外れる比較例のトナーを用いたときには、耐ブロッキング性、耐オフセット性および低温定着性のいずれかが不十分なものとなった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner used for developing an electrostatic latent image in an image forming method such as an electrophotographic method, an electrostatic recording method, and an electrostatic printing method, and a method for producing the same.
[0002]
[Prior art]
The heat roll fixing (contact heating type fixing) method widely used as a toner image fixing method is superior to other fixing methods in terms of toner fixability, enables high-speed fixing, and is energy efficient. In addition, it is advantageous in that it has a low environmental burden due to volatilization of solvents and the like. On the other hand, since the heat roll fixing method is a method in which the surface of the fixing roller (or fixing belt) and the toner image are in direct contact with each other, a so-called offset phenomenon occurs in which the toner image adheres to the surface of the fixing roller or the like. There is a problem that it is easy. Therefore, as one means for improving the offset resistance of the toner, an attempt has been made to change the material of the binder resin of the toner.
[0003]
In recent image forming apparatuses, from the viewpoint of energy saving and apparatus miniaturization, so-called low-temperature fixing, in which the fixing roller or the like is not heated as much as possible, has been promoted, and toner fixing can be achieved at a much lower temperature. It has been demanded. Therefore, in order to improve the low-temperature fixability of the toner, a resin having a low glass transition temperature or a resin having a high content of low molecular weight components is used as the binder resin, or a large amount of a low molecular weight substance such as wax is mixed in the toner. Attempts have been made. However, such a toner has a problem that it tends to cause a so-called blocking phenomenon that aggregates and solidifies over time.
[0004]
Various attempts have been made to improve the offset resistance, low-temperature fixability and blocking resistance of toner (Patent Documents 1 to 3). In the toner described in Patent Document 1, a crystalline polyester in which the type of polyhydric alcohol component or polycarboxylic acid component and the softening temperature are specified and an amorphous polyester resin are mixed at a predetermined ratio. Is used as a binder resin. The toner binder described in Patent Document 2 is composed of a mixture of a crystalline polyester whose melting point, melt viscosity, acid value and hydroxyl value are specified, and another binder resin whose glass transition temperature is specified. In Patent Document 3, in order to realize high-speed fixing at a low temperature, a polyester resin in which the content ratio of tetrahydron (THF) insoluble matter is limited, and its acid value, melt viscosity, and change rate thereof are specified. Is used as a binder resin. Patent Document 4 describes a toner containing magnetic powder and a non-linear polyester resin as main components. Regarding non-linear polyester, the melt viscosity and the viscosity gradient in a predetermined temperature range are described. Is limited.
[0005]
However, although the toners described in these patent documents all have the effect of improving the low-temperature fixability, they cannot be said to be sufficient in view of compatibility with blocking resistance.
[0006]
[Patent Document 1]
JP 2001-222138 A
[Patent Document 2]
JP 11-249339 A
[Patent Document 3]
JP 2002-91077 A
[Patent Document 4]
JP-A-5-313407
[0007]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a toner that is excellent in all of offset resistance, low-temperature fixability, and blocking resistance.
Another object of the present invention is to provide a method for producing a toner having good offset resistance, low-temperature fixability and blocking resistance.
[0008]
[Means for Solving the Problems and Effects of the Invention]
In order to solve the above-mentioned problems, the present inventor has intensively studied paying attention to toner melting characteristics. As a result, the viscosity V at the outflow start temperature Ti of the toner is adjusted by adjusting the type and composition of the resin used as the binder resin, or adjusting the combination of the wax components and the blending ratio thereof._TiViscosity V at softening temperature Ts_TsRatio V_Ti/ V_TsIn addition, when the difference Ts-Ti between the outflow start temperature Ti of the toner and the softening temperature Ts is adjusted as appropriate, a toner having good offset resistance, low-temperature fixability, and blocking resistance can be provided. The present inventors have found a completely new fact that it is possible to complete the present invention.
[0009]
That is, a toner according to the present invention for solving the above-described problem includes at least a polyester resin, a crystalline resin, a colorant, and a wax component, and the viscosity V at the outflow start temperature Ti of the toner._TiViscosity V at softening temperature Ts_TsRatio V_Ti/ V_TsIs 5 to 20, and the difference Ts−Ti between Ti and Ts is 10 to 20 ° C.
[0010]
Viscosity V at toner flow start temperature Ti_TiViscosity V at softening temperature Ts_TsAs the value increases, the low-temperature fixability of the toner tends to decrease. In particular, V_TiAnd V_TsRatio V_Ti/ V_Ts(Viscosity difference V between toner outflow start temperature and softening temperature V_Ti-V_TsIncreases the viscosity of the toner (particularly the viscosity V at the softening temperature Ts)._Ts) Is a general factor. In such a case, the mechanical strength of the binder resin becomes insufficient, and the non-offset region of fixing disappears (offset phenomenon is likely to occur). Problems arise.
On the other hand, the difference in viscosity V between the toner outflow start temperature and the softening temperature V_Ti-V_TsThe ratio V_Ti/ V_TsIf the value is made smaller, the occurrence of the offset phenomenon can be suppressed, and the difference Ts-Ti between the toner outflow start temperature Ti and the softening temperature Ts becomes smaller. As a result, the low temperature fixability of the toner can be improved. it can.
[0011]
Specifically, as found by the inventors' study, the ratio V_Ti/ V_TsIs adjusted to be 5 to 20, and the difference Ts-Ti between the toner outflow start temperature Ti and the softening temperature Ts is adjusted to be 10 to 20 ° C. Both the low-temperature fixability and the blocking resistance can be improved.
[0012]
Viscosity V_Ti, V_TsAnd the ratio V of both_Ti/ V_TsIn addition, the toner outflow start temperature Ti, the softening temperature Ts, and the difference Ts-Ti between them can be adjusted by adjusting the kind of resin used as the binder resin, its composition, the combination of wax components, and the blending ratio thereof. It can be set appropriately.
Toner viscosity V_TiAnd V_TsRatio V_Ti/ V_TsIs preferably 10 to 15 in the above range, and more preferably 12 to 15. Further, the difference Ts−Ti between the outflow start temperature Ti and the softening temperature Ts of the toner is preferably 10 to 18 ° C. and more preferably 15 to 18 ° C. in the above range.
[0013]
In the present invention, “outflow start temperature Ti” and “softening temperature Ts” of the toner are both physical property values obtained from the behavior exhibited when the toner is heated and softened using a flow tester.
The method for measuring the outflow start temperature Ti and the softening temperature Ts is as follows. First, 1.5 g of toner (measurement sample) is stored in a measurement container including a nozzle having a diameter (inner diameter) of 1 mm and a length of 1 mm. Next, the toner is heated at a temperature rising rate of 6 ° C. per minute, and a constant load (test pressure P) of 1.96 MPa is applied by the plunger, while the plunger is lowered when the toner is pushed out from the nozzle (flow value). Measure Q) and temperature. Here, the temperature when the plunger starts to descend (when the toner starts to flow out) is defined as “outflow start temperature Ti (° C.)”. Also, assuming that the height of the S-shaped curve obtained by plotting the measurement result is h, the temperature corresponding to the drop amount h / 2 (the temperature at which half of the toner has flowed out) is obtained, and this is expressed as “softening temperature Ts ( ° C) ”.
[0014]
Toner outflow start temperature T_iViscosity at_TiAnd softening temperature Ts Viscosity at_TsIs the viscoelastic flow state (apparent viscosity) V of the toner when it is recognized as the outflow start temperature Ti or the softening temperature Ts._I[Pa · s], which is calculated by the following equation based on the results of the above-mentioned flow tester constant temperature increase test.
[0015]
[Expression 1]

[0016]
[Where, Tw is the apparent shear stress [Pa], and Dw is the apparent shear rate [s.^-1], R is the nozzle radius [m], L is the nozzle length [m], P is the test pressure [Pa], and Q is the flow value [m].^-3・ S^-1], And π represents the circular ratio, respectively. ]
[0017]
In the toner of the present invention, a polyester resin and a crystalline resin are used as the main component of the binder resin. If the binder resin does not contain a resin having crystallinity (for example, a crystalline polyester resin), the outflow start temperature Ti of the toner becomes high and the difference Ts-Ti from the softening temperature Ts becomes large. Therefore, although the blocking resistance is good, there arises a problem that the low-temperature fixability is lowered.
In addition, when a resin having crystallinity (for example, a crystalline polyester resin) is included in the binder resin and the compatibility between the amorphous polyester resin and the crystalline polyester resin is high, There is a possibility that the difference Ts-Ti exceeds 20 ° C. In this case, even if the low-temperature fixability of the toner is good, the properties of the crystalline polyester resin cannot be maintained because part of the crystalline polyester resin becomes amorphous. This causes a problem that the blocking resistance is lowered. In general, when a resin having crystallinity is contained in the binder resin of the toner, the glass transition temperature Tg of the toner is lowered, and the blocking resistance tends to be lowered.
[0018]
In contrast, a toner containing a resin having crystallinity in the binder resin and having a small difference Ts-Ti is excellent in low-temperature fixability because it hardens immediately even when it starts to melt, and the crystalline polyester resin. Since the characteristics are also maintained, the blocking resistance is excellent.
As described above, the toner of the present invention has its V_Ti/ V_TsIn order to set T and Ts-Ti within the above range, it is preferable that the binder resin contains crystallinity. Specifically, it is preferable that the polyester resin used as the binder resin contains a crystalline polyester resin.
[0019]
The toner production method according to the present invention includes a viscosity V at an outflow start temperature Ti obtained by melt-kneading at least a polyester resin, a resin having crystallinity, a colorant, and a wax component._TiViscosity V at softening temperature Ts_TsRatio V_Ti/ V_Ts5 to 20 and a kneaded product having a difference Ts-Ti between Ti and Ts of 10 to 20 ° C is pulverized after cooling.
According to such a production method, a toner having good offset resistance, low-temperature fixability and blocking resistance can be produced.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Next, the toner of the present invention will be described in detail.
[Binder resin]
The binder resin in the toner of the present invention contains a polyester resin, and when the toner is produced using the binder resin, the difference “Ts−Ti” between the outflow start temperature Ti and the softening temperature Ts, Viscosity V in Ti_TiAnd viscosity at Ts V_TsThe ratio “V”_Ti/ V_Ts"Is not particularly limited except that it can be set within the above-mentioned range. Therefore, in addition to satisfying the above requirements, it can be appropriately selected from conventionally known various resins.
Among these, it is preferable to use an amorphous polyester resin as a main component of the binder resin and to contain a crystalline polyester resin in order to satisfy the above requirements for the toner.
[0021]
(Amorphous polyester resin)
In the present invention, the polyester resin used for the binder resin is a polycondensation reaction between an alcohol component composed of a dihydric or higher polyhydric alcohol and a carboxylic acid component such as carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester. It is obtained.
Of the polyester resins, the polyhydric alcohol component and the polycarboxylic acid component are not particularly limited, and various conventionally known ones can be used.
[0022]
In the present invention, the amorphous polyester resin means the softening temperature Ts and the maximum peak temperature Tm of heat of fusion by DSC._MAXRatio Ts / Tm_MAXIs in the range of 1.1 to 4.0, preferably 1.5 to 3.0.
Although the softening temperature Ts of an amorphous polyester resin is not specifically limited, It is preferable that it is 70-180 degreeC. Maximum heat of fusion peak temperature Tm of amorphous polyester resin_MAXAlthough it does not specifically limit, It is preferable that it is 50-85 degreeC. The glass transition temperature Tg is not particularly limited, but is preferably 45 to 80 ° C.
[0023]
(Resin having crystallinity)
As described above, the binder resin in the toner of the present invention preferably contains an amorphous polyester resin as a main component and a resin having crystallinity.
Here, the resin having crystallinity is not particularly limited. For example, an aliphatic crystalline polyester resin having a melting point (about 80 to 150 ° C.) suitable as a crystalline polyester resin, a vinyl resin, or a binder resin. Can be used.
If the compatibility between the amorphous polyester resin and the crystalline resin is high, the crystalline resin becomes amorphous in the amorphous polyester resin, and the crystallinity is impaired. There is a fear. Therefore, both resins are required to have low compatibility so that the crystalline resin does not become amorphous. Specifically, it is desired that the difference in solubility constant (Solubility Parameter, SP value) between the two resins is about 0.1 to 1.5, preferably about 0.1 to 1.0.
[0024]
(Crystalline polyester resin)
Of the polyester resins, crystalline ones are not particularly limited in terms of the polyhydric alcohol component and polyvalent carboxylic acid component, and various conventionally known ones can be used.
However, in adjusting the softening temperature Ts of the crystalline polyester resin and the degree of crystallinity to an appropriate range, the polyhydric alcohol component contains a diol having 2 to 6 carbon atoms in an amount of 80 mol% or more, preferably 90 to 90%. It is preferable to use one containing 100 mol% or more, and for the polycarboxylic acid component, use fumaric acid containing 80 mol% or more, preferably 85 to 100 mol% or more. Is preferred.
[0025]
In the present invention, the crystalline polyester resin means the softening temperature Ts and the maximum peak temperature Tm of heat of fusion by differential scanning calorimetry (DSC)._MAXRatio Ts / Tm_MAXIs 0.9 or more and less than 1.1, preferably 0.98 to 1.05.
Although the softening temperature Ts of crystalline polyester resin is not specifically limited, It is preferable that it is 85-150 degreeC, and it is more preferable that it is 100-140 degreeC. Moreover, although the outflow start temperature Ti of crystalline polyester resin is not specifically limited, It is preferable that it is 100-130 degreeC, and it is more preferable that it is 110-130 degreeC.
The outflow start temperature Ti and the softening temperature Ts of the crystalline polyester resin are measured according to the above-described measuring method of the “outflow start temperature Ti” and the “softening temperature Ts” of the toner.
[0026]
Maximum melting temperature Tm of crystalline polyester resin_MAXAlthough it is not specifically limited, It is preferable that it is 77-150 degreeC, and it is more preferable that it is 90-140 degreeC.
The number average molecular weight <Mn> of the tetrahydrofuran (THF) soluble part of the crystalline polyester resin is preferably 500 to 6,000 from the viewpoint of setting the blocking resistance of the toner and the viscosity thereof in an appropriate range. 500 to 5,000 is more preferable.
[0027]
(Mixing ratio of amorphous polyester resin and crystalline resin)
In the binder resin used in the present invention, the content ratio between the amorphous polyester resin and the resin having crystallinity depends on the difference “Ts−Ti” between the outflow start temperature Ti and the softening temperature Ts of the toner and the viscosity V in Ti._TiAnd viscosity at Ts V_TsThe ratio “V”_Ti/ V_Ts"Is set in the above-described range.
The content ratio of the amorphous polyester resin and the resin having crystallinity varies depending on the physical property value of each resin, and is not limited to this. -60: 40 (weight ratio) is preferable, and 80: 20-70: 30 (weight ratio) is more preferable.
[0028]
[Colorant]
The colorant contained in the toner of the present invention is not particularly limited, and can be appropriately selected from conventionally known various colorants according to the color required for the toner. The content of the colorant is not particularly limited, and may be appropriately set according to a conventional method.
[0029]
〔wax〕
The wax contained in the toner of the present invention includes a difference “Ts−Ti” between the outflow start temperature Ti and the softening temperature Ts when the toner is produced using the wax and the binder resin, and the viscosity in Ti. V_TiAnd viscosity at Ts V_TsThe ratio “V”_Ti/ V_Ts"Is not particularly limited except that it can be set within the above-mentioned range. Therefore, in addition to satisfying the above requirements, various conventionally known waxes can be appropriately selected and used.
Specific examples of the wax used in the present invention include natural waxes such as carnauba wax and rice wax; and synthetic waxes such as polypropylene wax, polyethylene wax, ester wax, and Fischer-Tropsch wax.
[0030]
[Other ingredients]
In the toner of the present invention, examples of other components blended in the binder resin together with the colorant and wax include a charge control agent and various stabilizers.
[0031]
As the charge control agent, either positive charge control or negative charge control is used according to the charging polarity of the toner. These charge control agents are not particularly limited, and various conventionally known charge control agents for toner can be used. The blending amount of the charge control agent is not particularly limited, and may be set as appropriate according to a conventional method. Usually, it is set in the range of 10 parts by weight or less, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the binder resin.
[0032]
[Toner production method, etc.]
The toner of the present invention is prepared by, for example, blending the binder resin with a colorant, wax, and other components and premixing them uniformly with a dry blender, a Henschel mixer, a ball mill or the like. Manufactured by a so-called pulverization method in which a kneading device such as a remixer, roll, uniaxial or biaxial kneading extruder is uniformly melted and kneaded, and the kneaded product is cooled and pulverized, and classified as necessary. be able to.
[0033]
The toner (toner particles) of the present invention may be used as a toner to which inorganic fine particles such as silica, alumina and titanium oxide are externally added (externally added), if necessary. The inorganic fine particles as the external additive are not particularly limited, and various conventionally known fine particles can be appropriately selected and used according to characteristics such as lubricity required for the toner.
The toner of the present invention can also be mixed with a magnetic carrier and used as a two-component developer. The magnetic carrier is not particularly limited, and various conventionally known ones can be appropriately selected and used according to the charging characteristics and electrical characteristics required for the developer.
[0034]
The particle size of the toner (toner particles) is not particularly limited, but is usually set in the range of 3 to 12 μm, preferably in the range of 5 to 10 μm. In the case of a toner having a small particle size for the purpose of improving the image quality of the formed image, the particle size of the toner particles is preferably about 4 to 8 μm.
[0035]
【Example】
Next, the toner of the present invention will be described with reference to examples and comparative examples.
[Production of toner and two-component developer]
The amorphous polyester resins used in Examples and Comparative Examples are as shown in Table 1.
“Bisphenol A-PO adduct” and “bisphenol A-EO adduct” as polyhydric alcohol components are obtained by adding propylene oxide (PO) or ethylene oxide (EO) to bisphenol A, respectively.
[0036]
[Table 1]

[0037]
In Table 1, the outflow start temperature (Ti) and softening temperature (Ts) of the amorphous polyester resin are both described above using a flow tester [model number “CFT-500A” manufactured by Shimadzu Corporation]. This is obtained in the same manner as the measuring method of “toner softening temperature Ts”.
The crystalline polyester resins used in Examples and Comparative Examples are as shown in Table 2.
[0038]
[Table 2]

[0039]
In Table 2, the outflow start temperature (Ti) and the softening temperature (Ts) of the crystalline polyester resin are both determined in the same manner as in the case of the amorphous polyester resin.
[0040]
Example 1
As binder resins, 60 parts by weight of a high molecular weight amorphous polyester resin indicated by a in Table 1, 20 parts by weight of a low molecular weight amorphous polyester resin indicated by x in Table 1, and crystallinity indicated by A in Table 2 A mixture with 20 parts by weight of a polyester resin was used.
Carbon black as a colorant (trade name “Nipex-60” manufactured by Degussa) 9 parts by weight with respect to 100 parts by weight of the resin mixture, a positively chargeable charge control agent [fourth grade of styrene acrylic type] The main component is an ammonium salt. Trade name “FCA-222P” manufactured by Fujikura Kasei Co., Ltd. 2 parts by weight, polypropylene wax [trade name “100TS” manufactured by Sanyo Kasei Co., Ltd., melting point 130 ° C.] 1.5 parts by weight and ester wax [ 3 parts by weight of a trade name “WE-3” manufactured by Nippon Oil & Fats Co., Ltd., melting point 75 ° C.] was added, and the above components were melt-kneaded with a twin-screw extruder. Next, the kneaded product was pulverized with a jet mill and classified with an air classifier to obtain toner particles having an average particle diameter of 8 μm.
[0041]
Further, 0.8 part by weight of hydrophobic silica fine particles having an average particle diameter of 7 nm was externally added (externally added) to 100 parts by weight of the toner particles, and mixed with a Henschel mixer to obtain a toner.
Next, the above toner and a magnetic carrier made of ferrite particles having a weight average diameter of 60 μm were stirred and mixed to obtain a two-component developer having a toner concentration (T / D) of 5% by weight.
[0042]
(Example 2)
Instead of resin x, 20 parts by weight of low molecular weight amorphous polyester resin indicated by y in Table 1 is used, the amount of carbon black is 12 parts by weight, the amount of charge control agent is 4 parts by weight, In addition, Fischer-Tropsch wax [trade name “MDP-7000” manufactured by Nippon Seiwa Co., Ltd.] can be used instead of polypropylene wax [100TS] and ester wax [WE-3]. , Melting point 101 ° C.] Toner particles, toner and a two-component developer were produced in the same manner as in Example 1 except that 4.5 parts by weight were used.
(Example 3)
In the same manner as in Example 1, except that 60 parts by weight of the high molecular weight amorphous polyester indicated by b in Table 1 was used instead of the resin a, toner particles, toner and a two-component developer were produced. .
[0043]
(Comparative Example 1)
As the binder resin, 70 parts by weight of a high molecular weight amorphous polyester resin indicated by b in Table 1, 15 parts by weight of a low molecular weight amorphous polyester resin indicated by x in Table 1, and crystallinity indicated by B in Table 2 A mixture of 15 parts by weight of a polyester resin is used, and a Fischer-Tropsch wax [above-mentioned] is used instead of the polypropylene-based wax [above-mentioned “100TS”] and the ester-based wax [above-mentioned “WE-3”]. [MDP-7000]] Toner particles, toner and a two-component developer were produced in the same manner as in Example 1 except that 4.5 parts by weight were used.
[0044]
(Comparative Examples 2 to 4)
Comparative Example 1 except that the resin represented by C in Table 2 was used as the crystalline polyester resin instead of the resin B, and the blending amounts of the low molecular weight amorphous polyester resin and the crystalline polyester resin were changed. Similarly, toner particles, toner and a two-component developer were produced.
(Comparative Examples 5 to 8)
Toner particles, toner and a two-component developer were produced in the same manner as in Comparative Example 1 except that the kind of the crystalline polyester resin was changed.
[0045]
(Comparative Example 9)
Resin y is used instead of resin x as a low molecular weight amorphous polyester resin, the amount of resin y is 40 parts by weight, the crystalline polyester resin is not compounded (used), and the amount of carbon black is Toner particles, toner, and a two-component developer were produced in the same manner as in Example 2 except that the amount was 9 parts by weight and the amount of the charge control agent was 2 parts by weight.
[0046]
(Comparative Example 10)
Toner particles, toner and two-component development in the same manner as in Example 1 except that the blending amount of the low molecular weight amorphous polyester resin x is 40 parts by weight and the crystalline polyester resin is not blended (used). The agent was manufactured.
(Comparative Example 11)
Toner particles, toner, and two-component development in the same manner as in Comparative Example 2 except that the blending amounts of the high molecular weight amorphous polyester resin b, the low molecular weight amorphous polyester resin x, and the crystalline polyester resin C were changed. The agent was manufactured.
[0047]
(Comparative Example 12)
The blending amount of the wax was 1.5 parts by weight of the above-mentioned polypropylene wax (the above-mentioned trade name “100TS”) and 5 parts by weight of the above-mentioned ester-based wax (the above-mentioned trade name “WE-3”) ( That is, toner particles, toner and a two-component developer were produced in the same manner as in Example 1 except that the total amount of wax was 6.5 parts by weight with respect to 100 parts by weight of the binder resin.
[0048]
(Comparative Example 13)
In the same manner as in Example 2 except that 60 parts by weight of the high molecular weight amorphous polyester represented by b in Table 1 was used instead of the resin a, toner particles, toner and a two-component developer were produced. .
Table 3 shows the composition of the toner particles in the above Examples and Comparative Examples.
[0049]
[Table 3]

[0050]
* 1: The blending amounts of the waxes in Examples 1 and 3 and Comparative Examples 10 and 12 indicate the total amount of two types of waxes.
* 2: The blending amount of the wax in Comparative Example 11 indicates the amount of wax contained in the wax-added resin.
The outflow start temperature Ti (° C.), the softening temperature Ts (° C.), the difference between Ti and Ts Ts−Ti (° C.), and the viscosity V of the toner in Ti obtained in the examples and comparative examples._TiViscosity of toner at (Pa · s), Ts_Ts(Pa · s) and V_TiAnd V_TsRatio V_Ti/ V_TsThe measurement / calculation results are shown in Table 4 below.
[0051]
[Toner physical property evaluation test]
(Evaluation of blocking resistance)
The toner obtained in the above Examples and Comparative Examples (the toner particles added with an external additive) is allowed to stand at 58 ° C. for 3 hours, and the following test is performed using the toner after the standing, thereby causing a blocking phenomenon. The presence or absence of (toner fusion) was confirmed.
The test method using a powder tester is as follows. Three types of sieves having different mesh sizes (mesh size 140/235/330) were stacked in this order from above, and 5 g of accurately weighed toner was placed on the uppermost sieve (mesh size 140). Next, using a powder tester manufactured by Hosokawa Micron Corporation, the toner was vibrated for 30 seconds with the frequency setting of the scale 6, and the toner remaining on the uppermost sieve was collected and its weight was measured.
If the weight of the toner remaining on the uppermost sieve is less than 30% by weight of the initially weighed toner (5 g), the blocking resistance is good, and conversely if it is 30% by weight or more, the blocking resistance is good. It was said that the property was poor.
[0052]
(Evaluation of fixability)
Using the two-component developers obtained in the above examples and comparative examples, an image forming test (copying process) was performed with an electrophotographic copying machine (model number “Creage 7340” manufactured by Kyocera Mita Co., Ltd.). It was.
The test was performed by copying an A4 size black solid document, and the toner fixing temperature was raised or lowered in increments of 5 ° C. on the basis of 140 ° C.
[0053]
(a) Evaluation of offset resistance
In the above copying process, it was visually confirmed whether or not a toner offset phenomenon occurred.
(b) Measurement of fixing rate
In the above copying process, the image density (A) of the copied image when the fixing temperature was 140 ° C. was measured. On the other hand, the surface of the copied image was reciprocated five times by its own weight using a fixing property measuring device in which the bottom surface of a mild steel weight (diameter 50 mm, weight 400 g) was fixed with double-sided tape. The image density (B) of was measured. Next, using both image densities (A) and (B), the fixing ratio (%) was calculated by the following formula. For the measurement of image density, a reflection densitometer (model number “TC-6D” manufactured by Tokyo Denshoku Co., Ltd.) was used.
[0054]
Fixing rate = [Image density (B) / Image density (A)] × 100
The fixing rate is required to be 98% or more, and those having a fixing ratio of less than 98% are considered to have insufficient fixing properties.
[0055]
(c) Measurement of minimum fixing temperature
By performing the copying process at different fixing temperatures and measuring the fixing rate by the method (b) above, the fixing temperature (° C.) when the fixing rate can be set to 98% is obtained. The minimum fixing temperature was used.
The minimum fixing temperature is preferably as low as possible, specifically 130 ° C. or lower, preferably 120 ° C. or lower.
The results of physical property evaluation tests of the toner are shown in Tables 4-6.
[0056]
[Table 4]

[0057]
[Table 5]

[0058]
[Table 6]

[0059]
As is apparent from Tables 4 to 6, the difference Ts−Ti (° C.) between the toner outflow start temperature Ti and the softening temperature Ts, and the viscosity V of the toner at Ti._TiAnd viscosity at Ts V_TsRatio V_Ti/ V_TsWhen both of the toners of Examples 1 and 2 in which both are set within the scope of the present invention were used, good results were obtained in all of blocking resistance, offset resistance, and low-temperature fixability. .
In contrast, the difference Ts-Ti and the ratio V_Ti/ V_TsWhen any of the toners of Comparative Examples out of the scope of the present invention was used, any of blocking resistance, offset resistance, and low-temperature fixability was insufficient.

Claims (3)

At least a polyester resin, a resin having crystallinity, a colorant, and a wax component, the ratio V _Ti / V _Ts of the viscosity V _Ts in viscosity V _Ti and softening temperature Ts in the flow starting temperature Ti of the toner A toner having 5 to 20 and a difference Ts−Ti between Ti and Ts of 10 to 20 ° C. The toner according to claim 1, wherein the resin having crystallinity is a crystalline polyester resin. At least a polyester resin, a resin having crystallinity, a colorant, and a wax component obtained by melt-kneading, the ratio V _Ti / V of the viscosity V _Ti in flow starting temperature Ti and the viscosity V _Ts in softening temperature Ts _A method for producing a toner, wherein a kneaded product having a _Ts of 5 to 20 and a difference Ts-Ti between Ti and Ts of 10 to 20 ° C is pulverized after cooling.