Polyester resin for toner, toner, developer, toner cartridge, process cartridge, and image forming apparatus

1. A polyester resin for a toner comprising:

a repeating unit derived from a dicarboxylic acid component; and

a repeating unit derived from a diol component represented by Formula (1):

wherein each of R 1 and R 2 independently represents a hydrogen atom or a methyl group,

each of L 1 , L 2 and L 3 independently represents a divalent linking group selected from the group consisting of carbonyl groups, ester groups, ether groups, sulfonyl groups, substituted or unsubstituted chained alkylene groups, substituted or unsubstituted cyclic alkylene groups, substituted or unsubstituted arylene groups, and combinations thereof,

L 1 and L 2 or L 1 and L 3 optionally forms a ring, and

each of A 1 and A 2 independently represents a rosin ester group.

2. The polyester resin according to claim 1 ,

wherein the dial component represented by Formula (1) is a reaction product of a difunctional epoxy compound and a rosin.

3. The polyester resin according to claim 2 ,

wherein the rosin is selected from the group consisting of a purified rosin, a disproportionated rosin and a hydrogenated rosin.

4. The polyester resin according to claim 1 ,

wherein the substituted or unsubstituted chained alkylene groups represented by L 1 , L 2 and L 3 have a total carbon number is 1 to 10.

5. The polyester resin according to claim 1 ,

wherein the substituted or unsubstituted cyclic alkylene groups represented by L 1 , L 2 and L 3 have a total carbon number is 3 to 7.

6. The polyester resin according to claim 1 , having a softening temperature of 80° C. to 160° C.

7. The polyester resin according to claim 1 , having an acid value of 1 mgKOH/g to 50 mgKOH/g.

8. A toner comprising the polyester resin according to claim 1 .

9. The toner according to claim 8 ,

wherein the diol component represented by Formula (1) is a reaction product of a difunctional epoxy compound and a rosin.

10. A developer comprising the toner according to claim 8 .

11. The developer according to claim 10 ,

wherein the diol component represented by Formula (1) is a reaction product of a difunctional epoxy compound and a rosin.

12. A toner cartridge accommodating the toner according to claim 8 .

13. A process cartridge accommodating the developer according to claim 10 , comprising a unit for developing an electrostatic latent image formed on a latent image holding member with the developer to form a toner image.

14. An image forming apparatus comprising:

a latent image holding member;

a charging unit configured to electrically charge the surface of the latent image holding member;

a forming unit configured to form an electrostatic latent image on a surface of the latent image holding member;

a developing unit configured to develop the electrostatic latent image with the developer according to claim 10 to form a toner image;

a transferring unit configured to transfer the toner image to a recording medium; and

a fixing unit configured to fix the toner image on the recording medium.

15. An image forming method comprising:

forming an electrostatic latent image on a surface of a latent image holding member;

developing the electrostatic latent image with the developer according to claim 10 to form a toner image;

transferring the toner image to a recording medium; and

fixing the toner image on the recording medium.

16. The image forming method according to claim 15 ,

the diol component represented by Formula (1) is a reaction product of a difunctional epoxy compound and a rosin.