Image fixing apparatus and image fixing method for a crystalline resin-containing toner
View Patent ↗An image fixing method capable of favorably fixing a toner containing a crystalline resin is provided. A transfer medium having unfixed images formed of a color toner containing a binder resin that contains a crystalline resin and a colorant is passed between a heating member heated by way of an external heating unit and a pressurizing member, thereby fixing the unfixed images.
1. An image fixing apparatus comprising a heating member and a pressurizing member, thereby fixing an unfixed image on a transfer medium, wherein
the heating member has a heating unit outside the heating member, and the unfixed image is formed of a color toner containing a binder resin that contains a crystalline resin and a colorant; and
a surface temperature of the pressurizing member is controlled so as to be at a melting point of the crystalline resin +30° C. or lower.
2. An image fixing apparatus according to claim 1 , wherein the heating unit is a heating roll.
3. An image fixing apparatus according to claim 1 , further comprising a unit that applies a releasing agent on surfaces of the heating member and the pressurizing member.
4. An image fixing apparatus according to claim 3 , wherein an application amount of the releasing agent is from 1.6×10 −5 to 8.0×10 −4 mg/cm 2 .
5. An image fixing apparatus according to claim 1 , wherein a melting point of the crystalline resin is within a range from 40° C. to 120 C.
6. An image fixing apparatus according to claim 1 , wherein a content of the crystalline resin in the binder resin is from 20 to 50 wt %.
7. An image fixing apparatus according to claim 1 , wherein the binder resin contains an amorphous resin.
8. An image fixing apparatus according to claim 1 , further comprising a cooling unit that controls a surface temperature of the pressurizing member.
9. An image fixing apparatus according to claim 8 , wherein the cooling unit is a cooling roll.
10. An image fixing apparatus according to claim 8 , wherein the cooling unit is a cooling belt.
11. A method of fixing an image, comprising of fixing an unfixed image formed of a color toner containing a binder resin that contains a crystalline resin and a colorant using an apparatus having a heating member and a pressurizing member, wherein the heating member is heated by way of an external heating unit and a surface temperature of the pressurizing member is controlled so as to be at a melting point of the crystalline resin +30° C. or lower.
12. An image fixing method according to claim 11 , wherein the external heating unit is an external heating roll.
13. An image fixing method according to claim 11 , wherein the surface temperature of the pressurizing member is at a melting point of the crystalline resin in the color toner +Y ° C. or lower in which Y is represented by the following formula:
Y =0.3 X −18
where X represents a transportation speed (mm/sec) of the transfer medium in an image fixing apparatus, which is less than 160 (mm/sec).
14. An image fixing method according to claim 13 , wherein the surface temperature of the pressurizing member is controlled by a cooling belt.
15. An image fixing method according to claim 11 , wherein the surface temperature of the pressurizing member is controlled by a cooling roll.
16. An image fixing method according to claim 11 , further comprising a unit that applies a releasing agent on surfaces of the heating member and the pressurizing member.
17. An image fixing method according to claim 11 , wherein a melting point of the crystalline resin is within a range from 40° C. to 120° C.
18. An image fixing method according to claim 11 , wherein a content of the crystalline resin in the binder resin is from 20 to 50 wt %.
19. An image fixing method according to claim 11 , wherein the binder resin contains an amorphous resin.