TONER, TONER STORAGE UNIT, IMAGE FORMATION APPARATUS, AND IMAGE FORMATION METHOD

PROBLEM TO BE SOLVED: To provide toner which never forms an abnormal image due to filming with external additives on a photoreceptor and also has superior cleaning properties even when repeatedly used for a long time, specially, in a low-temperature, low-humidity environment.SOLUTION: The present invention relates to toner which contains base particles and external additives sticking on the base particles, the toner satisfying conditions 1 and 2 when a number distribution D of particle sizes of powder particles B produced one base particle A is calculated from a density "a" of base particles A sticking on an adhesion place and a density "b" of the powder particles B sticking on mica after the toner is thrown in a pressure-reduced space from a throw-in opening and caused to strike on a substrate surface having the adhesion place composed of a carbon tape and the mica, the surface being arranged orthogonally to a direction connecting the center of the pressure-reduced space and the center of the throw-in opening. In the condition 1, the powder particles are particles released from the base particle, where the number distribution D has a maximum of the number of the powder particles B in a range of every 25nm of larger than 125 nm to 150 nm, larger than 150 nm to 175 nm, or larger than 175 nm to 200 nm in a graph having a lateral axis representing a range of every 25 nm in particle diameter and a longitudinal axis representing the numbers of the powder particles B. In the condition 2, the number distribution D shows 30% or less of the number of particles of 125 nm or les sin particle size.SELECTED DRAWING: None 【課題】特に低温低湿環境下において長期に渡って繰り返し使用しても、感光体上の外添剤によるフィルミングに起因する異常画像が発生せず、かつクリーニング性にも優れるトナーの提供。【解決手段】 母体粒子と、前記母体粒子に付着した外添剤とを含有するトナーであって、前記トナーを、減圧空間内に投入口より投入し、前記減圧空間の中心と前記投入口の中心とを結ぶ方向に対して直交するように表面を配置された、カーボンテープで構成される粘着箇所とマイカとを有する基板表面に衝突させて、前記粘着箇所に付着した母体粒子Ａの密度ａと、前記マイカに付着した下記粉体粒子Ｂの密度ｂとから、前記母体粒子Ａの１個から発生した前記粉体粒子Ｂの粒子径の個数分布Ｄを算出した際に、下記条件１及び２を満たすトナーである。粉体粒子Ｂ：前記母体粒子から離脱した粒子条件１：前記個数分布Ｄについて、横軸を２５ｎｍ毎の粒子径の範囲とし、縦軸を前記粉体粒子Ｂの個数として、グラフ化した際に、１２５ｎｍ超１５０ｎｍ以下、１５０ｎｍ超１７５ｎｍ以下、及び１７５ｎｍ超２００ｎｍ以下の２５ｎｍ毎の範囲のいずれかに前記粉体粒子Ｂの個数が最大値を有する。条件２：前記個数分布Ｄにおいて、粒子径１２５ｎｍ以下の粒子の個数が３０％以下。【選択図】なし