JP3862200B2 - Positively chargeable toner - Google Patents

Description

【００１２】
（式中、Ｒは炭素数２又は３のアルキレン基、ｘ及びｙは正の数を示し、ｘとｙの和は１〜１６、好ましくは１．５〜５．０である）で表される化合物が含有されていることが好ましい。
【００１３】
式（Ｉ）で表される化合物としては、ポリオキシプロピレン（２．２）−２，２−ビス (４−ヒドロキシフェニル) プロパン、ポリオキシエチレン（２．２）−２，２−ビス（４−ヒドロキシフェニル）プロパン等のビスフェノールＡのアルキレン（炭素数２〜３）オキサイド（平均付加モル数１〜１６）付加物等が挙げられる。また、他のアルコール成分としては、エチレングリコール、プロピレングリコール、グリセリン、ペンタエリスリトール、トリメチロールプロパン、水素添加ビスフェノールＡ、ソルビトール、又はそれらのアルキレン（炭素数２〜４）オキサイド（平均付加モル数１〜１６）付加物等が挙げられ、これらの１種以上を含有することが好ましい。
【００１４】
式（Ｉ）で表される化合物のアルコール成分中の含有量は、５モル％以上、好ましくは５０モル％以上、より好ましくは１００モル％が望ましい。
【００１５】
また、カルボン酸成分としては、フタル酸、イソフタル酸、テレフタル酸、フマル酸、マレイン酸等のジカルボン酸、ドデセニルコハク酸、オクチルコハク酸等の炭素数１〜２０のアルキル基又は炭素数２〜２０のアルケニル基で置換されたコハク酸、トリメリット酸、ピロメリット酸、それらの酸の無水物及びそれらの酸のアルキル（炭素数１〜８）エステル等が挙げられ、これらの１種以上を含有するものが好ましい。
【００１６】
ポリエステルは、例えば、アルコール成分とカルボン酸成分とを不活性ガス雰囲気中にて、要すればエステル化触媒を用いて、１８０〜２５０℃の温度で縮重合することにより製造することができる。
【００１７】
ポリエステルの酸価は、正帯電性トナーとして十分な帯電量を得るために、１０ｍｇＫＯＨ／ｇ以下、好ましくは７ｍｇＫＯＨ／ｇ以下である。また、ポリエステルの水酸基価は２０〜４０ｍｇＫＯＨ／ｇ、軟化点は１１０〜１６０℃、ガラス転移点は５０〜７０℃であることが、それぞれ好ましい。
【００１８】
着色剤としては、トナー用着色剤として用いられている染料、顔料等のすべてを使用することができ、カーボンブラック、フタロシアニンブルー、パーマネントブラウンFG、ブリリアントファーストスカーレット、ピグメントグリーンＢ、ローダミン−Ｂベース、ソルベントレッド49、ソルベントレッド146 、ソルベントブルー35、キナクリドン、カーミン６Ｂ、ジスアゾエロー等が挙げられ、これらは単独で又は２種以上を混合して用いることができる。着色剤の含有量は、結着樹脂１００重量部に対して、１〜１０重量部が好ましい。
【００１９】
ニグロシン染料としては、「ニグロシンベースＥＸ」、「オイルブラックＢＳ」、「オイルブラックＳＯ」、「ボントロンＮ−０１」、「ボントロンＮ−０４」、「ボントロンＮ−０７」、「ボントロンＮ−０９」、「ボントロンＮ−１１」（以上、オリエント化学工業社製）等が挙げられる。ニグロシン染料の含有量は、結着樹脂１００重量部に対して、１．５〜３．５重量部が好ましく、２．０〜３．０重量部がより好ましい。
【００２０】
なお、本発明では、必要に応じてニグロシン染料以外の他の荷電制御剤が適量配合されていてもよい。
【００２１】
本発明においては、離型剤、導電性調整剤、体質顔料、繊維状物質等の補強充填剤、酸化防止剤、老化防止剤、流動性向上剤、クリーニング性向上剤等の添加剤が、トナー中に適宜添加されていてもよい。
【００２２】
本発明のトナーは、混練粉砕法等により得られる粉砕トナーが好ましく、例えば、結着樹脂、着色剤、ニグロシン染料等をボールミル等の混合機で均一に混合した後、密閉式ニーダー又は１軸もしくは２軸の押出機等で溶融混練し、冷却、粉砕、分級して製造することができる。さらに、トナーの表面には、必要に応じて流動性向上剤等を添加してもよい。このようにして得られるトナーの重量平均粒子径は３〜１５μｍが好ましい。
【００２３】
本発明の正帯電性トナーは、帯電量の立ち上がり性等の帯電特性や、耐久性に優れるため、周速が４００ｍｍ／ｓｅｃ以上、特には５００ｍｍ／ｓｅｃ以上の感光体を有する高速機にも好適に用いることができる。
【００２４】
本発明のトナーは、磁性体微粉末を含有するときは単独で現像剤として、また磁性体微粉末を含有しないときは非磁性一成分系現像剤として、もしくはキャリアと混合して二成分系現像剤として使用される。前記高速機対応の点からは二成分系現像剤としての使用が好ましい。
【００２５】
【実施例】
〔酸価及び水酸基価〕
ＪＩＳ Ｋ００７０の方法により測定する。
【００２６】
〔軟化点〕
高化式フローテスター（島津製作所製、ＣＦＴ−５００Ｄ）を用い、樹脂の半分が流出する温度を軟化点とする（試料：１ｇ、昇温速度：６℃／分、荷重：１．９６ＭＰａ、ノズル：１ｍｍφ×１ｍｍ）。
【００２７】
〔ガラス転移点〕
示差走査熱量計「ＤＳＣ２１０」（セイコー電子工業（株）製）を用いて昇温速度１０℃／分で測定する。
【００２８】
〔紫外線吸収スペクトル〕
トナー０．５０ｇを５００ｍｌ容のガラス瓶に計量し、エタノール２０ｍｌを注ぎ、ボールミル攪拌機により２５０ｒ／ｍｉｎで２０分間攪拌する。攪拌後、さらにエタノール２０ｍｌを注ぎ、一時間放置した後、上澄み液を用いて以下の測定装置により５７０ｎｍと６００ｎｍでの紫外線吸収スペクトルを測定する。本発明で溶媒として用いるエタノールは、トナー自身を溶解せず、トナー表面に存在するニグロシン染料のみが溶解するため、そのＵＶスペクトルを検討することで、トナー表面に存在するニグロシン染料の状態を推定することができるものと考えられる。
【００２９】
＜測定装置＞
測定器：島津紫外可視分光光度計ＵＶ−１６０Ａ（島津製作所製）
（ベースとしてエタノールを使用）
セル：石英性光路１ｃｍセル
【００３０】
樹脂製造例１
ポリオキシプロピレン（２．２）−２，２−ビス (４−ヒドロキシフェニル) プロパン７３５ｇ、ポリオキシエチレン（２．２）−２，２−ビス (４−ヒドロキシフェニル) プロパン２９３ｇ、イソフタル酸２８０ｇ、イソオクテニルコハク酸６０ｇ、トリメリット酸７２ｇ及び酸化ジブチル錫（エステル化触媒）２ｇを、窒素雰囲気下、真空下で２３０℃で攪拌しつつ、ＡＳＴＭ Ｅ２８−５１Ｔにより測定した軟化点が１３６℃に達するまで反応させて、樹脂Ａを得た。樹脂Ａは淡黄色の固体であり、酸価は３．１ｍｇＫＯＨ／ｇ、水酸基価は３５．２ｍｇＫＯＨ／ｇ、ガラス転移点は６３℃であった。
【００３１】
樹脂製造例２
イソオクテニルコハク酸の使用量を７２ｇ、トリメリット酸の使用量を６６ｇに、それぞれ変更した以外は、樹脂製造例１と同様にして、樹脂Ｂを得た。樹脂Ｂの酸価は６．２ｍｇＫＯＨ／ｇ、水酸基価は３０．９ｍｇＫＯＨ／ｇ、ガラス転移点は６３℃であった。
【００３２】
樹脂製造例３
イソオクテニルコハク酸の使用量を７２ｇ、トリメリット酸の使用量を７０ｇに、それぞれ変更し、反応終了の目安を、軟化点の追跡ではなく、酸価が１２．５ｍｇＫＯＨ／ｇに達した時点とした以外は、樹脂製造例１と同様にして、樹脂Ｃを得た。樹脂Ｃの酸価は１２．５ｍｇＫＯＨ／ｇ、水酸基価は３１．２ｍｇＫＯＨ／ｇ、軟化点は１４５℃、ガラス転移点は６４℃であった。
【００３３】
樹脂製造例４
イソフタル酸の使用量を１９９ｇ、イソオクテニルコハク酸の使用量を２１４ｇ、トリメリット酸の使用量を１２８ｇに、それぞれ変更し、反応終了の目安を、軟化点の追跡ではなく、酸価が２３．０ｍｇＫＯＨ／ｇに達した時点とした以外は、樹脂製造例１と同様にして、樹脂Ｄを得た。樹脂Ｄの酸価は２３．０ｍｇＫＯＨ／ｇ、水酸基価は３１．２ｍｇＫＯＨ／ｇ、軟化点は１４５℃、ガラス転移点は６４℃であった。
【００３４】
実施例１〜４、比較例１〜５
表１に示す結着樹脂１００重量部、カーボンブラック「Ｒ３３０Ｒ」（キャボット社製）５重量部、ニグロシン染料「ボントロンＮ−０１」（オリエント化学工業社製）２重量部及び離型剤「ＮＰ−０５５」２重量部を、押出機「ＰＣＭ−３０」（池貝社製）により表１に示す混練条件で予備混合及び溶融混練し、ジェットミルで微粉砕し、気流分級機で分級して、重量平均粒子径１０μｍの粉体を得た。得られた粉体１００重量部に対して、疎水性シリカ「ＨＶＫ−２１５０」（ワッカーケミカルズ社製）０．３重量部をヘンシェルミキサーを用いて混合付着させ、トナーを得た。
【００３５】
実施例５
樹脂Ｂ２０重量部とニグロシン染料「ボントロンＮ−０１」（オリエント化学工業社製）２重量部とを予め混合、混練し、ロートプレックスで粗粉砕した。得られた粗粉砕物と、樹脂Ｂ８０重量部、カーボンブラック「Ｒ３３０Ｒ」（キャボット社製）５重量部及び離型剤「ＮＰ−０５５」２重量部とを表１に示す混練条件で予備混合及び溶融混練した後、実施例１と同様にしてトナーを得た。
【００３６】
比較例６、７
「ボントロンＮ−０１」の使用量を、比較例６では１重量部に、比較例７では４重量部にそれぞれ変更した以外は、実施例１と同様にしてトナーを得た。
【００３７】
実施例１〜５及び比較例１〜７で得られたトナーの重量平均粒子径、５７０ｎｍと６００ｎｍにおけるトナーの紫外線吸収スペクトル及びその差を表１に示す。
【００３８】
【表１】

【００３９】
試験例１
トナー４重量部と平均粒子径１００μｍのシリコンフェライトキャリア９６重量部をＶブレンダーで１５分間攪拌して、現像剤を調製した。
得られた現像剤を正帯電性の静電荷像を形成するセレン感光体（周速：６００ｍｍ／ｓｅｃ）を具備するプリンタに実装し、５００，０００枚の画像を連続して印字した。連続印刷の際、２０００枚印刷後（印刷初期）と印刷終了後（耐刷後）に少量の現像剤をサンプリングし、「ｑ／ｍメーター」（エッピング社製）にてトナーの帯電量を測定するとともに、画質、感光体汚染の程度を評価した。結果を表２に示す。
【００４０】
【表２】

【００４１】
以上の結果から、実施例１〜５のトナーはニグロシン染料が適度に分散しているため、耐刷後も安定した帯電特性を有し、感光体汚染もなく優れた画像が得られることが分かる。これに対し、比較例１〜６のトナーはニグロシン染料が分散しすぎてトナー表面量が少ないため、帯電量の立ち上がりが遅く、帯電安定性にも欠けており、比較例７のトナーはニグロシン染料の分散径が大きく、帯電特性は良好であるものの、ニグロシン染料が脱離したり、トナーの帯電分布が不均一となるため、ベタ部の画像に白抜けが生じ、感光体汚染が生じる。
【００４２】
【発明の効果】
本発明により、荷電制御剤がポリエステル中に適度に分散しているため、立ち上がり性、帯電安定性等の帯電特性に優れ、高速機に用いた場合であっても、感光体汚染や画質劣化を生じることなく、連続して優れた画像が得られる正帯電性トナーを提供することが可能となった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positively chargeable toner used for developing an electrostatic latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.
[0002]
[Prior art]
In a high-speed machine having a photoreceptor having a peripheral speed of 400 mm / sec or more, the rising property of the toner charge amount is important. If sufficient start-up property is not obtained when the toner is replenished, image deterioration due to toner having a poor charge amount is caused. Furthermore, since high-speed machines require long-term printing durability, how to maintain the toner charge amount stably is an important issue.
[0003]
Therefore, a method of adding a large amount of a charge control agent to the toner is taken in order to improve the rising property of the charge amount. In particular, a toner containing polyester is excellent in fixability and durability. In order to use the resin itself from the negatively chargeable to positively chargeable toner, it is necessary to add a larger amount of charge control agent. However, when a large amount of the internal additive is added, various problems such as poor dispersion, cost increase, photoconductor contamination, and carrier contamination can occur.
[0004]
[Problems to be solved by the invention]
An object of the present invention is excellent in charging characteristics such as start-up property and charging stability, and even when used in a high-speed machine, excellent images can be obtained continuously without causing photoconductor contamination and image quality deterioration. The object is to provide a positively chargeable toner.
[0005]
[Means for Solving the Problems]
The present invention contains a binder resin containing a polyester having an acid value of 10 mgKOH / g or less (however, a polyester containing a divalent or higher epoxy compound as a constituent component), a colorant and a nigrosine dye. A polyester obtained by polycondensation of an alcohol component and a carboxylic acid component containing 50 mol% or more of the compound represented by the formula (I), at 570 nm and 600 nm. The present invention relates to a positively chargeable toner having a difference in ultraviolet absorption spectrum of the toner of 0.08 to 0.18.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The positively chargeable toner of the present invention is characterized in that a specific polyester is used as a binder resin, and the dispersion state of the nigrosine dye contained as a charge control agent on the toner surface is adjusted to a specific range. That is, the problem of the present invention can be solved only by using a specific polyester as a binder resin and appropriately dispersing the nigrosine dye therein. The toner surface of absorbing nigrosine dye 570 nm, is considered to 600nm absorption correlates to the dispersion diameter of the nigrosine dye, 570 nm and the difference in the ultraviolet absorption spectrum of the toner of the present invention in the 600nm (hereinafter, Δ _570- by adjusting the to) _600, it is possible to adjust the state of dispersion of nigrosine dye. In the present invention, Δ _570-600 is 0.08 to 0.18, preferably 0.10 to 0.16, more preferably 0.12 to 0.15. If _Δ570-600 is less than 0.08, the nigrosine dye will be dispersed too much and will be present not only in the toner surface but also in the toner in a large amount. The amount of effective surface nigrosine dye present is relatively low. On the other hand, when Δ _570-600 exceeds 0.18, the nigrosine dye is not sufficiently dispersed, and the nigrosine dye is detached from the toner surface during the pulverization and classification in the toner production process, or the toner surface distribution is uneven. As a result, the photosensitive member is contaminated and the image is defective. Although the details of the interaction between the specific polyester and the nigrosine dye are unknown, it is considered that the compatibility of the both is within an appropriate range, so that the nigrosine dye can take an optimum dispersed state.
[0007]
The ultraviolet absorption spectrum of the toner at 570 nm and 600 nm can be measured by the method described in Examples. In addition, _since the adjustment of Δ _570-600 varies depending on the toner production equipment, scale, etc., it cannot be determined unconditionally. For example, the preliminary mixing time of the raw material composition, the supply amount of the raw material composition to the extruder, the melting Examples thereof include a method of adjusting the barrel temperature at the time of kneading, and a method in which a part of the binder resin and nigrosine dye are preliminarily kneaded and then melt kneaded together with the remaining raw material composition. Specifically, in order to increase the dispersion of the nigrosine dye, methods such as increasing the premixing time, reducing the amount supplied to the extruder, and lowering the barrel temperature are effective. It is preferable to obtain a desired dispersion state by appropriately combining.
[0008]
The toner of the present invention contains a binder resin, a colorant and a nigrosine dye, and the binder resin contains a polyester. The content of the polyester is preferably 50 to 100% by weight, more preferably 90 to 100% by weight, and particularly preferably 100% by weight in the binder resin from the viewpoint of dispersibility, fixing property and chargeability of the colorant. is there. Examples of resins that can be used other than polyester include styrene-acrylic resins, epoxy resins, polycarbonates, polyurethanes, and the like.
[0009]
There is no restriction | limiting in particular as a raw material monomer of the polyester in this invention, Well-known alcohol components and well-known carboxylic acid components, such as carboxylic acid, carboxylic acid anhydride, and carboxylic acid ester, are used.
[0010]
As the alcohol component, the formula (I):
[0011]
[Chemical 1]

[0012]
(Wherein R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16, preferably 1.5 to 5.0). It is preferable that the compound is contained.
[0013]
Examples of the compound represented by the formula (I) include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4 -Alkylene (2 to 3 carbon atoms) oxide (average number of added moles 1 to 16) adduct of bisphenol A such as -hydroxyphenyl) propane. Other alcohol components include ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or alkylene (2 to 4 carbon atoms) oxide (average added mole number 1 to 1). 16) Additives and the like are mentioned, and it is preferable to contain one or more of these.
[0014]
The content of the compound represented by the formula (I) in the alcohol component is 5 mol% or more, preferably 50 mol% or more, more preferably 100 mol%.
[0015]
The carboxylic acid component includes dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid and maleic acid, alkyl groups having 1 to 20 carbon atoms such as dodecenyl succinic acid and octyl succinic acid, or those having 2 to 20 carbon atoms. Examples thereof include succinic acid, trimellitic acid, pyromellitic acid substituted with an alkenyl group, anhydrides of these acids, and alkyl (carbon number 1 to 8) esters of those acids, which contain one or more of these. Those are preferred.
[0016]
The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of 180 to 250 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst.
[0017]
The acid value of the polyester is 10 mgKOH / g or less, preferably 7 mgKOH / g or less in order to obtain a sufficient charge amount as a positively chargeable toner. Moreover, it is preferable that the hydroxyl value of polyester is 20-40 mgKOH / g, the softening point is 110-160 degreeC, and a glass transition point is 50-70 degreeC, respectively.
[0018]
As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow and the like can be mentioned, and these can be used alone or in admixture of two or more. The content of the colorant is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.
[0019]
Nigrosine dyes include “Nigrosine Base EX”, “Oil Black BS”, “Oil Black SO”, “Bontron N-01”, “Bontron N-04”, “Bontron N-07”, “Bontron N-09” , “Bontron N-11” (manufactured by Orient Chemical Industry Co., Ltd.) and the like. The content of the nigrosine dye is preferably 1.5 to 3.5 parts by weight and more preferably 2.0 to 3.0 parts by weight with respect to 100 parts by weight of the binder resin.
[0020]
In the present invention, an appropriate amount of a charge control agent other than the nigrosine dye may be blended as necessary.
[0021]
In the present invention, additives such as mold release agents, conductivity modifiers, extender pigments, fibrous fillers, antioxidants, anti-aging agents, fluidity improvers, cleaning improvers, and the like are added to the toner. It may be added as appropriate.
[0022]
The toner of the present invention is preferably a pulverized toner obtained by a kneading pulverization method. For example, a binder resin, a colorant, a nigrosine dye and the like are uniformly mixed with a mixer such as a ball mill, and then a sealed kneader or a single screw or It can be produced by melt-kneading with a twin-screw extruder or the like, cooling, pulverizing, and classifying. Furthermore, a fluidity improver or the like may be added to the toner surface as necessary. The toner thus obtained preferably has a weight average particle diameter of 3 to 15 μm.
[0023]
Since the positively chargeable toner of the present invention is excellent in charging characteristics such as rising property of charge amount and durability, it is also suitable for a high speed machine having a photoreceptor having a peripheral speed of 400 mm / sec or more, particularly 500 mm / sec or more. Can be used.
[0024]
When the toner of the present invention contains magnetic fine powder, it is used alone as a developer, and when it does not contain magnetic fine powder, it is used as a non-magnetic one-component developer or mixed with a carrier to develop two-component development. Used as an agent. From the viewpoint of compatibility with the high speed machine, the use as a two-component developer is preferable.
[0025]
【Example】
[Acid value and hydroxyl value]
It is measured by the method of JIS K0070.
[0026]
[Softening point]
Using a Koka type flow tester (manufactured by Shimadzu Corporation, CFT-500D), the temperature at which half of the resin flows out is defined as the softening point (sample: 1 g, heating rate: 6 ° C./min, load: 1.96 MPa, nozzle : 1 mmφ × 1 mm).
[0027]
[Glass transition point]
A differential scanning calorimeter “DSC210” (manufactured by Seiko Denshi Kogyo Co., Ltd.) is used to measure at a heating rate of 10 ° C./min.
[0028]
[UV absorption spectrum]
0.50 g of toner is weighed into a 500 ml glass bottle, 20 ml of ethanol is poured, and the mixture is stirred with a ball mill stirrer at 250 r / min for 20 minutes. After stirring, 20 ml of ethanol is further poured and left for one hour, and then the ultraviolet absorption spectra at 570 nm and 600 nm are measured using the supernatant with the following measuring apparatus. Ethanol used as a solvent in the present invention does not dissolve the toner itself, but only the nigrosine dye present on the toner surface, so that the state of the nigrosine dye present on the toner surface is estimated by examining its UV spectrum. Can be considered.
[0029]
<Measurement device>
Measuring instrument: Shimadzu UV-visible spectrophotometer UV-160A (manufactured by Shimadzu Corporation)
(Use ethanol as base)
Cell: Silica optical path 1cm cell
Resin production example 1
735 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 293 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 280 g of isophthalic acid, While stirring 60 g of isooctenyl succinic acid, 72 g of trimellitic acid and 2 g of dibutyltin oxide (esterification catalyst) at 230 ° C. under vacuum in a nitrogen atmosphere, until the softening point measured by ASTM E28-51T reaches 136 ° C. Reaction was performed to obtain Resin A. Resin A was a pale yellow solid having an acid value of 3.1 mgKOH / g, a hydroxyl value of 35.2 mgKOH / g, and a glass transition point of 63 ° C.
[0031]
Resin production example 2
Resin B was obtained in the same manner as in Resin Production Example 1, except that the amount of isooctenyl succinic acid used was changed to 72 g and the amount of trimellitic acid used was changed to 66 g. Resin B had an acid value of 6.2 mgKOH / g, a hydroxyl value of 30.9 mgKOH / g, and a glass transition point of 63 ° C.
[0032]
Resin production example 3
The amount of isooctenyl succinic acid used was changed to 72 g and the amount of trimellitic acid used was changed to 70 g, respectively, and the end of the reaction was not the tracking of the softening point, but the time when the acid value reached 12.5 mgKOH / g. Except that, Resin C was obtained in the same manner as in Resin Production Example 1. Resin C had an acid value of 12.5 mgKOH / g, a hydroxyl value of 31.2 mgKOH / g, a softening point of 145 ° C., and a glass transition point of 64 ° C.
[0033]
Resin production example 4
The amount of isophthalic acid used was changed to 199 g, the amount of isooctenyl succinic acid used was 214 g, and the amount of trimellitic acid used was 128 g. The reaction end was not traced at the softening point, but the acid value was 23.0 mgKOH. Resin D was obtained in the same manner as in Resin Production Example 1 except that the time point reached / g. Resin D had an acid value of 23.0 mgKOH / g, a hydroxyl value of 31.2 mgKOH / g, a softening point of 145 ° C., and a glass transition point of 64 ° C.
[0034]
Examples 1-4, Comparative Examples 1-5
100 parts by weight of binder resin shown in Table 1, 5 parts by weight of carbon black “R330R” (Cabot), 2 parts by weight of nigrosine dye “Bontron N-01” (manufactured by Orient Chemical Industries) and a release agent “NP-” 055 "2 parts by weight was premixed and melt-kneaded under the kneading conditions shown in Table 1 with an extruder" PCM-30 "(manufactured by Ikegai Co., Ltd.), finely pulverized with a jet mill, and classified with an airflow classifier. A powder having an average particle size of 10 μm was obtained. To 100 parts by weight of the obtained powder, 0.3 part by weight of hydrophobic silica “HVK-2150” (manufactured by Wacker Chemicals) was mixed and adhered using a Henschel mixer to obtain a toner.
[0035]
Example 5
20 parts by weight of resin B and 2 parts by weight of nigrosine dye “Bontron N-01” (manufactured by Orient Chemical Co., Ltd.) were mixed and kneaded in advance, and coarsely pulverized with a rotoplex. The obtained coarsely pulverized product, 80 parts by weight of resin B, 5 parts by weight of carbon black “R330R” (manufactured by Cabot) and 2 parts by weight of release agent “NP-055” were premixed under the kneading conditions shown in Table 1. After melt-kneading, a toner was obtained in the same manner as in Example 1.
[0036]
Comparative Examples 6 and 7
A toner was obtained in the same manner as in Example 1 except that the amount of “Bontron N-01” was changed to 1 part by weight in Comparative Example 6 and 4 parts by weight in Comparative Example 7.
[0037]
The weight average particle diameters of the toners obtained in Examples 1 to 5 and Comparative Examples 1 to 7 and the ultraviolet absorption spectra of the toners at 570 nm and 600 nm and the difference are shown in Table 1.
[0038]
[Table 1]

[0039]
Test example 1
A developer was prepared by stirring 4 parts by weight of toner and 96 parts by weight of a silicon ferrite carrier having an average particle diameter of 100 μm with a V blender for 15 minutes.
The resulting developer was mounted on a printer having a selenium photoreceptor (peripheral speed: 600 mm / sec) that forms a positively charged electrostatic image, and 500,000 images were printed continuously. During continuous printing, a small amount of developer is sampled after printing 2000 sheets (initial printing) and after printing (after printing), and the charge amount of the toner is measured with a “q / m meter” (Epping). In addition, the degree of image quality and photoconductor contamination were evaluated. The results are shown in Table 2.
[0040]
[Table 2]

[0041]
From the above results, it can be seen that the toners of Examples 1 to 5 have the nigrosine dye appropriately dispersed, so that they have stable charging characteristics even after printing and can obtain excellent images without being contaminated with the photoreceptor. . On the other hand, in the toners of Comparative Examples 1 to 6, since the nigrosine dye is excessively dispersed and the amount of the toner surface is small, the rise of the charge amount is slow and the charging stability is lacking. The toner of Comparative Example 7 is a nigrosine dye. Although the dispersion diameter is large and the charging characteristics are good, the nigrosine dye is desorbed and the charge distribution of the toner becomes non-uniform, resulting in white spots in the solid image and contamination of the photoreceptor.
[0042]
【The invention's effect】
According to the present invention, since the charge control agent is appropriately dispersed in the polyester, it has excellent charging characteristics such as start-up property and charging stability, and even when used in a high-speed machine, it can cause contamination of the photoreceptor and image quality deterioration. It has become possible to provide a positively chargeable toner capable of continuously obtaining excellent images without being generated.

Claims (2)

A positively chargeable resin containing a binder resin containing a polyester having an acid value of 10 mgKOH / g or less (but not a polyester containing a divalent or higher epoxy compound), a colorant and a nigrosine dye. A toner wherein the polyester is of the formula (I):

(In the formula, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16)
A polyester obtained by polycondensation of an alcohol component and a carboxylic acid component containing 50 mol% or more of the compound represented by the formula, wherein the difference in the ultraviolet absorption spectrum of the toner at 570 nm and 600 nm is 0.08 to 0.18 Some positively charged toner.   2. The positively chargeable toner according to claim 1, which is used in a high speed machine having a photoreceptor having a peripheral speed of 400 mm / sec or more.