| 摘要 |
PROBLEM TO BE SOLVED: To provide an external additive for toner which improves the flowability, electric characteristics and cleaning ability of a developer and gives an excellent picture without fogging. SOLUTION: The external additive for toner comprises calcium carbonate particles which satisfy the following conditions (a)-(d): (a) 0.1μm≤dx1≤20μm, (b) 1≤α≤5 whereα=d<SB>50</SB>/dx1, (c) 0≤β≤2 whereβ=(d<SB>90</SB>-d<SB>10</SB>)/d<SB>50</SB>and (d) 0.1≤Sw≤15. Therein, dx1 is the average grain size (μm) according to electron microscope photography,αis the coefficient of dispersion,βis the sharpness, d<SB>50</SB>, d<SB>90</SB>and d<SB>10</SB>are respectively the 50%-average grain size (μm), the minus sieve side accumulation 90% and 10% grain sizes (μm) by the use of a microtrac FRA laser particle size distribution analyzer and Sw is the BET relative surface according to a nitrogen adsorption method. COPYRIGHT: (C)2004,JPO |
