Binding resin for toner, toner and electrophotographic apparatus
In an electrophotographic apparatus, which forms a color image by transferring a plurality of toner images having different colors onto an image-receiving sheet so as to be stacked and fixed thereon, even in the case of carrying out an oil-less fixing process and allowing the process speed to vary within wide range, the present invention provides a binder resin, toner and an electrophotographic apparatus which make it possible to achieve both superior fixing property and anti-offset property, and consequently to form a color image with high color reproducibility and high quality. In the present invention, a toner comprising a molecular weight maximum peak in a range of molecular weights from 2×10 3 to 3×10 4 in molecular weight distribution of GPC chromatogram, and a molecular weight maximum peak or shoulder in a range from 3×10 4 to 1×10 6 , wherein said molecular weight maximum peak or shoulder located on a range of molecular weights from 3×10 4 to 1×10 6 is obtained by kneading a toner composition containing a specific binder resin containing a high molecular weight component at not less than a specific amount so that the high molecular weight component of the binder is converted into a low molecular weight component by thermal or mechanical energy exerted at the time of kneading, is provided.
1. A method for preparing a toner comprising the steps of:
preparing a toner composition containing a binder resin; and
kneading the toner composition through processes in which two opposing rolls capable of heating or cooling that are rotated in different directions are used, a temperature difference being provided between roll temperature of one of the rolls (RL 1 ) and roll temperature of the other roll (RL 2 ), and the roll (RL 1 ) and the roll (RL 2 ) are rotated at mutually different peripheral speeds, wherein said one of the rolls (RL 1 ) is provided with a temperature difference between the front-half portion and the rear-half portion thereof, and being conducted in a manner so as to satisfy the relationship:
Tg/ 2≦ Trj 1− Tr 2
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), and Tr 2 represents roll temperature of the roll (RL 2 ), and Tg represents glass transition temperature of the binder resin.
2. A method for preparing a toner comprising the steps of:
preparing a toner composition containing the binder resin which has,
a molecular weight maximum peak in a range of molecular weights from 2×10 3 to 3×10 4 in molecular weight distribution of GPC chromatogram, and
a component having a molecular weight of not less than 3×10 4 , as a component located in high molecular weight range, in an amount of not less than 5% based on the entire binder resin; and
kneading the toner composition so that a high molecular weight component of the binder is converted into a low molecular weight component by thermal or mechanical energy exerted at the time of kneading.
3. The method according to claim 2 , wherein said kneading is conducted through processes in which two opposing rolls capable of heating or cooling that are rotated in different directions are used, a temperature difference being provided between roll temperature of one of the rolls (RL 1 ) and roll temperature of the other roll (RL 2 ), and the roll (RL 1 ) and the roll (RL 2 ) are rotated at mutually different peripheral speeds.
4. The method according to claim 3 , wherein said one of the rolls (RL 1 ) is further provided with a temperature difference between the front-half portion and the rear-half portion thereof.
5. The method according to claim 1 or 3 which is conducted in a manner so as to satisfy the relationship:
1.1≦ Rw 1/ Rw 2≦2.5
wherein Rw 1 represents peripheral speed of the roll (RL 1 ), and Rw 2 represents peripheral speed of the roll (RL 2 ).
6. The method according to claim 1 or 3 which is conducted in a manner so as to satisfy the relationship:
1.25≦ Dr 1/ Dr 2≦10,
wherein Dr 1 represents a load current value of the roll (RL 1 ) at the time of rotation, Dr 2 represents a load current value of the roll (RL 2 ).
7. The method according to claim 4 which is conducted in a manner so as to satisfy the relationship:
Tm− 70≦ Trj 1≦ Tm− 10
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), and Tm represents softening point of the binder resin (a melting temperature in the ½ method).
8. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Tfb− 50° C.≦ Trj 1≦ Tfb+ 20° C.
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), and Tfb represents flow-beginning temperature of the binder resin.
9. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Tm− 90° C.≦ Trj 1− Trk 1≦ Tm− 20° C.
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), and Tm represents softening point of the binder resin (a melting temperature in the ½ method).
10. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Tfb− 70° C.≦ Trj 1− Trk 1≦ Tfb
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), and Tfb represents flow-beginning temperature of the binder resin.
11. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Tg≦Trj 1− Tr 2
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), Tr 2 represents roll temperature of the roll (RL 2 ), and Tg represents glass transition temperature of the binder resin.
12. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Tg− 20° C.≦ Trj 1− Trk 1≦ Tg+ 30° C.
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), Tr 2 represents roll temperature of the roll (RL 2 ), and Tg represents glass transition temperature of the binder resin.
13. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Tg− 40° C.≦ Trj 1− Trk 1≦ Tg+ 30° C.
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), Tr 2 represents roll temperature of the roll (RL 2 ), and Tg represents glass transition temperature of the binder resin.
14. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Trj 1≦ Hrt 1≦ Trj 1+60° C.
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), and Hrt 1 represents surface temperature of melted toner film that has been formed on a surface of the roll (RL 1 ) by a melted toner material.
15. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Trj 1+5° C.≦ Hrt 1≦ Trj 1+60° C.
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), and Hrt 1 represents surface temperature of melted toner film that has been formed on a surface of the roll (RL 1 ) by a melted toner material.
16. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
Trj 1+20° C.≦ Hrt 1≦ Trj 1+60° C.
wherein Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), Trk 1 represents roll temperature of the rear-half of the roll (RL 1 ), and Hrt 1 represents surface temperature of melted toner film that has been formed on a surface of the roll (RL 1 ) by a melted toner material.
17. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
10≦ Trj 1− Trj 2≦ Tg
wherein Tg represents glass transition point, Tm represents softening point, and Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), after melted toner film has been formed on the roll (RL 1 ), the roll temperature of the front-half of the roll (RL 1 ) is changed to Trj 2 .
18. The method for preparing a toner according to claim 1 which is conducted in a manner so as to satisfy the following relationship:
10≦ Trj 1− Trj 2≦ Tm− 50° C.
wherein Tg represents glass transition point, Tm represents softening point, and Trj 1 represents roll temperature of the front-half of the roll (RL 1 ), after melted toner film has been formed on the roll (RL 1 ), the roll temperature of the front-half of the roll (RL 1 ) is changed to Trj 2 .
19. A method for preparing a toner comprising the steps in which:
two opposing rolls capable of heating or cooling that are rotated in different directions is employed, a temperature difference is provided between the roll temperature of one of the rolls (RL 1 ) and the temperature of the other roll (RL 2 ), and the roll (RL 1 ) and the roll (RL 2 ) are rotated at mutually different peripheral speeds; and
a toner composition containing at least a binder resin and colorant is supplied from a material supply feeder to a gap between said two rolls so that said binder resin is melted with an internal additive agent being dispersed therein,
wherein the material feeder is inserted from the roll (RL 2 ) side so that said toner composition is allowed to drop on a surface of said roll (RL 1 ) within in a range from 20° to 80° from a position at which said roll (RL 1 ) and said roll (RL 2 ) are most closely located, in a direction opposite to the rotation direction of said roll (RL 1 ).