Toner kit, toner, method for forming an image, and image forming apparatus

An image forming apparatus of an electrophotographic system, which performs a color image formation using a plurality of toners, wherein the color image formation is configured, for at least one color, to:

• use a deep toner and a pale toner which have lightnesses different from each other at a point on a CIELAB color space, where a color saturation of the deep toner and a color saturation of the pale toner are equal to each other;
• form an image on a high lightness area using only the pale toner;
• and
• form an image on a halftone area using the deep toner and the pale toner in combination.

A toner kit comprising:

• a pale cyan toner comprising at least a binder resin and a colorant;
• and
• a deep cyan toner comprising at least a binder resin and a colorant,
• the pale cyan toner and the deep cyan toner being separated from each other, wherein when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• in a fixed image of the pale cyan toner, the pale cyan toner has a value of a* (a*C1) in a range of −19 to −30 when b* is −20 and a value of a* (a*C2) in a range of −29 to −45 when b* is −30;
• and
• in a fixed image of the deep cyan toner, the deep cyan toner has a value of a* (a*C3) in a range of −7 to −18 when b* is −20 and a value of a* (a*C4) in a range of −10 to −28 when b* is −30.

A deep cyan toner to be used in combination with a pale cyan toner, said pale cyan toner comprising at least a resin binder and a colorant;

• wherein when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• a value of a*(a*C1) in a range of −19 to −30 when b* is −20;
• and
• a value of a* (a*C2) in a range of −29 to −45 when b* is −30, and
• said deep cyan toner comprising at least a resin binder and a colorant,
• wherein when the toner image fixed on plain paper is expressed by the L*a*b* color coordinate system,
• a value of a* (a*C3) when b* is −20 is in a range of −7 to −18;
• and
• a value of a* (a*C4) when b* is −30 is in a range of −10 to −28.

A pale cyan toner to be used in combination with a deep cyan toner, said deep cyan toner comprising at least a resin binder and a colorant;

• wherein when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• a value of a* (a*C3) in a range of −7 to −18 when b* is −20;
• and
• a value of a* (a*C4) in a range of −10 to −28 when b* is −30, and
• said pale cyan toner comprising at least a resin binder an a colorant,
• wherein when the toner image fixed on plain paper is expressed by the L*a*b* color coordinate system,
• a value of a* (a*C1) when b* is −20 is in a range of −19 to −30;
• and
• a value of a* (a*C2) when b* is −30 is in a range of −29 to −45.

A method for forming an image comprising the steps of:

• forming an electrostatic charge image on an electrostatic charge image bearing member being charged;
• forming a toner image by developing the formed electrostatic charge image by a toner;
• transferring the formed toner image on a transfer material;
• and
• fixing the transferred toner image on the transfer material to obtain a fixed image,
• wherein the step of forming the electrostatic charge image comprises the steps of:
• forming a first electrostatic charge image to be developed by a first toner selected from a pale cyan toner and a deep cyan toner;
• and
• forming a second electrostatic charge image to be developed by a second toner selected from the pale cyan toner and the deep cyan toner, except of the first toner;
• wherein the step of forming the toner image comprises the steps of:
• forming a first cyan toner image by developing the first electrostatic charge image with the first toner;
• and
• forming a second cyan toner image by developing the second electrostatic charge image with the second toner;
• wherein the step of transferring comprises the step of transferring the first cyan toner image and the second cyan toner image to form a cyan toner image composed of the first cyan toner image and the second cyan toner image which are being overlapped one on another on the transfer material;
• wherein the pale cyan toner comprises at least a binder resin and a colorant and the deep cyan toner comprises at least a binder resin and a colorant;
• when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• in a fixed image of the pale cyan toner, the pale cyan toner has a value of a*(a*C1) in a range of −19 to −30 when b* is −20 and a value of a* (a*C2) in a range of −29 to −45 when b* is −30;
• and
• in a fixed image of the deep cyan toner, the deep cyan toner has a value of a* (a*C3) in a range of −7 to −18 when b* is −20 and a value of a* (a*C4) in a range of −10 to −28 when b* is −30.

A toner kit comprising:

• a pale magenta toner comprising at least a binder resin and a colorant;
• and
• a deep magenta toner comprising at least a binder resin and a colorant,
• the pale magenta toner and the deep magenta toner being separated from each other, wherein when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• in a fixed image of the pale magenta toner, the pale magenta toner has a value of b* (b*M1) in a range of −18 to 0 when a* is 20 and value of b* (b*M2) in a range of −26 to 0 when a* is 30;
• and
• in a fixed image of the deep magenta toner, the deep magenta toner has a value of b* (b*M3) in a range of −16 to 2 when a* is 20 a value of b* (b*M4) in a range of −24 to 3 when a* is 30, a difference between b*M1 and b*M3 (b*M1−b*M3) in a range of −8 to −1, and a difference between b*M2 and b*M4 (b*M2−b*M4) in a range of −12 to −1.

A deep magenta toner to be used in combination with a pale magenta toner, said pale magenta toner comprising at least a resin binder and a colorant;

• wherein when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• a value of b* (b*M1) in a range of −18 to 0 when a* is 20 in a fixed image;
• and
• a value of b* (b*M2) in a range of −26 to 0 when a* is 30, and
• said deep magenta toner comprising at least a resin binder and a colorant, wherein when the toner image fixed on plain paper is expressed by the L*a*b* color coordinate system,
• a value of b* (b*M3) when a* is 20 is in a range of −16 to 2;
• a value of b* (b*M4) when a* is 30 is in a range of −24 to 3;
• a difference between b*M1 and b*M3 (b*M1−b*M3) is in a range of −8 to −1;
• and
• a difference between b*M2 and b*M4 (b*M2−b*M4) is in a range of −12 to −1.

A pale magenta toner to be used in combination with a deep magenta toner, said deep magenta toner comprising at least a resin binder and a colorant;

• wherein when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• a value of b* (b*M3) in a range of −16 to 2 when a* is 20 in a fixed image;
• and
• a value of b* (b*M4) in a range of −24 to 3 when a* is 30, and
• said pale magenta toner comprising at least a resin binder and a colorant,
• wherein a value of b* (b*M1) when a* is 20 in a fixed image is in a range of −18 to 0;
• a value of b* (b*M2) when a* is 30 is in a range of −26 to 0;
• a difference between b*M1 and b*M3 (b*M1−b*M3) is in a range of −8 to −1;
• and
• a difference between b*M2 and b*M4 (b*M2−b*M4) is in a range of −12 to −1.

A method for forming an image comprising the steps of:

• forming an electrostatic charge image on an electrostatic charge image bearing member being charged;
• forming a toner image by developing the formed electrostatic charge image by a toner;
• transferring the formed toner image on a transfer material;
• and
• fixing the transferred toner image on the transfer material under heat and pressure to obtain a fixed image,
• wherein the step of forming the electrostatic charge image comprises the steps of:
• forming a first electrostatic charge image to be developed by a first toner selected from a pale magenta toner and a deep magenta toner;
• and
• forming a second electrostatic charge image to be developed by a second toner selected from the pale magenta toner and the deep magenta toner, except of the first toner;
• wherein the step of forming the toner image comprises the steps of:
• forming a first magenta toner image by developing the first electrostatic charge image with the first toner;
• and
• forming a second magenta toner image by developing the second electrostatic charge image with the second toner;
• wherein the step of transferring comprises the step of transferring the first magenta toner image and the second magenta toner image to form a magenta toner image composed of the first magenta toner image and the second magenta toner image which are being overlapped one on another on the transfer material;
• wherein the pale magenta toner comprises at least a binder resin and a colorant and a deep magenta toner comprises at least a binder resin and a colorant;
• when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• in a fixed image of the pale magenta toner, the pale magenta toner has a value of b* (b*M1) in a range of −18 to 0 when a* is 20 and a value of b* (b*M2) in a range of −26 to 0 when a is 30;
• and
• in a fixed image of the deep magenta toner, the deep magenta toner has a value of b* (b*M3) in a range of −16 to 2 when a* is 20 and a value of b* (b*M4) in a range of −24 to 3 when a* is 30, a difference between b*M1 and b*M3 (b*M2−b*M3) in a range of −8 to −1, and a difference between b*M2 and b*M4−(b*M2−b*M4) in a range of −12 to −1.

A toner kit comprising:

• a pale cyan toner comprising at least a binder resin and a colorant;
• and
• a deep cyan toner comprising at least a binder resin and a colorant,
• a pale magenta toner comprising at least a binder resin and a colorant;
• and
• a deep magenta toner comprising at least a binder resin and a colorant,
• the pale cyan toner, the deep cyan toner, the pale magenta toner, and the deep magenta toner being separated from each other,
• wherein when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• in a fixed image of the pale cyan toner, the pale cyan toner has a value of a* (a*C1) in a range of −19 to −30 when b* is −20 and a value of a* (a*C2) in a range of −29 to −45 when b* is −30;
• in a fixed image of the deep cyan toner, the deep cyan toner has a value of a* (a*C3) in a range of −7 to −18 when b* is −20 and a value of a* (a*C4) in a range of −10 to −28 when b* is −30;
• in a fixed image of the pale magenta toner, the pale magenta toner has a value of b* (b*M1) in a range of −18 to 0 when a* is 20 and value of b* (b*M2) in a range of −26 to 0 when a* is 30;
• and
• in a fixed image of the deep magenta toner, the deep magenta toner has a value of b* (b*M3) in a range of −16 to 2 when a* is 20 a value of b* (b*M4) in a range of −24 to 3 when a* is 30, a difference between b*M1 and b*M3 (b*M1−b*M3) in a range of −8 to −1, and a difference between b*M2 and b*M4 (b*M2−b*M4) in a range of −12 to −1.

A method for forming an image comprising the steps of:

• forming an electrostatic charge image on an electrostatic charge image bearing member being charged;
• forming a toner image by developing the formed electrostatic charge image by a toner;
• transferring the formed toner image on a transfer material;
• and
• fixing the transferred toner image on the transfer material to obtain a fixed image,
• wherein the step of forming the electrostatic charge image comprises the steps of:
• forming a first electrostatic charge image to be developed by a first toner selected from a group of toners consisting of a pale cyan toner and a deep cyan toner and a pale magenta toner and a deep magenta toner;
• forming a second electrostatic charge image to be developed by a second toner selected from the group of toners, except of the first toner;
• forming a third electrostatic charge image to be developed by a third toner selected from the group of toners, except of the first toner and the second toner;
• and
• forming a fourth electrostatic charge image to be developed by a fourth toner selected from the group of toners, except of the first toner, the second toner, and the third toner;
• wherein the step of forming the toner image comprises the steps of:
• forming a first toner image by developing the first electrostatic charge image with the first toner;
• forming a second toner image by developing the second electrostatic charge image with the second toner;
• forming a third toner image by developing the third electrostatic charge image with the third toner;
• and
• forming a fourth toner image by developing the fourth electrostatic charge image with the fourth toner;
• wherein the step of transferring comprises the step of transferring the first toner image, the second toner image, the third toner image, and the fourth toner image to form a color toner image composed of the first toner image, the second toner image, the third toner image, and the fourth toner image which are being overlapped one on another on the transfer material;
• wherein each of the pale cyan toner, the deep cyan toner, the pale magenta toner, and the deep magenta toner comprises at least a binder resin and a colorant;
• when a toner image fixed on plain paper is expressed by an L*a*b* color coordinate system where a* represents a hue in the red-green direction, b* represents a hue in the yellow-blue direction, and L* represents a lightness,
• in a fixed image of the pale cyan toner, the pale cyan toner has a value of a* (a*C1) in a range of −19 to −30 when b* is −20 and a value of a* (a*C2) in a range of −29 to −45 when b* is −30;
• in a fixed image of the deep cyan toner, the deep cyan toner has a value of a* (a*C3) in a range of −7 to −18 when b* is −20 and a value of a* (*C4) in a range of −10 to −28 when b* is −30;
• in a fixed image of the pale magenta toner, the pale magenta toner has a value of b* (b*M1) in a range of −18 to 0 when a* is 20 and value of b* (b*M2) in a range of −26 to 0 when a is 30;
• and
• in a fixed image of the deep magenta toner, the deep magenta toner has a value of b* (b*M3) in a range of −16 to 2 when a* is 20 a value of b* (b*M4) in a range of −24 to 3 when a* is 30, a difference between b*M1 and b*M3 (b*M1−b*M3) in a range of −8 to −1, and a difference between b*M2 and b*M4 (b*M2−b*M4) in a range of −12 to −1.