TONER, TONER SET, TONER ACCOMMODATING UNIT, IMAGE FORMING METHOD, AND IMAGE FORMING APPARATUS
FIG2 is a graph showing the L*a*b* color space for solid images formed of respective toners of Example 1 and Comparative Example 3 with a toner deposition amount of 0 6 mg/cm2  FIG1 is a graph showing spectral reflectance curves of solid images formed of respective toners of Example 1 and Comparative Example 3 with a toner deposition amount of 0 6 mg/cm2
As near-infrared light absorbing materials, phthalocyanines such as naphthalocyanine have been mainstream so far. A phthalocyanine-based near-infrared light absorbing material has a greenish or bluish color in the L*a*b* color space, as indicated by toner of Comparative Example 3 in FIG2. When the conventional invisible toner is recorded on a recording medium such as paper and stored for a long time, the recording medium gets deteriorated and discolored to be reddish over time as illustrated in FIG2, thus lowering invisibility of the invisible toner that has a greenish or bluish color on the recording medium. Here, FIG2 illustrates the L*a*b* color space for solid images formed of respective toners of Example 1 and Comparative Example 3 with a toner deposition amount of 0.6 mg/cm2.  That is, an invisible toner is required to absorb near-infrared light having a wavelength of 700 to 900 nm and to reflect visible light having a wavelength of 400 nm to 700 nm for their invisibility under visible light, as indicated by a spectral reflectance curve of a solid image formed of toner of Example 1, with a toner deposition amount of 0.6 mg/cm2, illustrated in FIG1.
graph
80
fixing device
1
Example Examples
100
in process cartridge
2
developer container Example
600
minute dots with
20
is from less than
40
less than
500
1H
10
less than regulation blade
3
Example
800
from
32
less than
['1. A toner comprising: a binder resin; and a near-infrared light absorbing material, wherein the toner in the form of a pellet has: a chroma C* of 20 or less in the L*C*h color space; a hue angle h of from 50 to 90 degrees in the L*C*h color space; and a spectral reflectance of 5% or less at a wavelength of from 800 to 900 nm.', '11. An image forming apparatus (A; B; C) comprising: an electrostatic latent image bearer (21; 1; 20); an electrostatic latent image forming device (15; 51; 132) configured to form an electrostatic latent image on the electrostatic latent image bearer (21; 1; 20); a developing device (31; 4; 140) containing the toner according to any one of claims 1 to 3, configured to develop the electrostatic latent image formed on the electrostatic latent image bearer (21; 1; 20) with the toner to form an invisible toner image; a transfer device (61; 66) configured to transfer the invisible toner image formed on the electrostatic latent image bearer (21; 1; 20) onto a surface of a recording medium; and a fixing device (80) configured to fix the invisible toner image on the surface of the recording medium.']