Claims
- 1. A toner for developing an electrostatic image characterized in that it comprises toner particles containing a binder resin (A), a polymer (B) and a colorant, the polymer (B) having weight-average molecular weight of 1000-3000 and having a ratio of weight-average molecular weight/number-average molecular weight being not more than 2, wherein the polymer (B) particles exist on surfaces of the toner particles.
- 2. A toner of claim 1, wherein more polymer (B) particles exist on the surfaces of the toner particles in comparison with central parts of the toner particles.
- 3. A toner of claim 2, wherein a dispersion density of the polymer (B) particles on the surfaces of the toner particles is higher than that in the central parts of the toner particles.
- 4. A toner of claim 1, wherein a dispersion particle size of the polymer (B) particles is 0.05-2.5 μm.
- 5. A toner of claim 1, wherein the polymer (B) is incompatible with the binder resin (A).
- 6. A toner of claim 5, wherein the polymer (B) is a homopolymer or a copolymer of an aromatic monomer and/or an aliphatic monomer.
- 7. A toner of claim 6, wherein (i) the aromatic monomer is a monomer selected from a class consisting of styrene, vinyltoluene, α-methylstyrene, isopropenyltoluene and indene, and (ii) the aliphatic monomer is a monomer selected from a class consisting of isoprene, piperylene, 2-methyl butene-1 and 2-methyl butene-2.
- 8. A toner of claim 6, wherein the polymer (B) is polystyrene having weight-average molecular weight of 1000-2000.
- 9. A toner of claim 6, wherein the polymer (B) is poly-α-methylstyrene having weight-average molecular weight of 2000-2800.
- 10. A toner of claim 1, wherein the polymer (B) has a glass transition point of 55-85° C. and a softening point of 110-150° C.
- 11. A toner of claim 1, wherein the binder resin (A) is polyester resin.
- 12. A toner of claim 1, wherein the polymer (B) has a grindability index of 0.1-1.0, said grindability index being defined as follows:
- 13. A toner for developing an electrostatic image characterized in that it comprises toner particles containing a binder resin (A), a polymer (B) and a colorant, polymer (B) having weight-average molecular weight of 1000-3000 and having a ratio of weight-average molecular weight/number-average molecular weight being not more than 2, wherein a content of the polymer (B) is 2-15 parts by weight in relations to 100 parts by weight of the binder resin (A), and polymer (B) particles having average dispersion particle size of 0.08-1.5 μm are dispersed in the toner particles having volume-average particle size of 5-8 μm.
- 14. A toner of claim 13, wherein the average dispersion particle size of the polymer (B) is 0.1-1.5 μm.
- 15. A toner of claim 13, wherein the content of the polymer (B) is 2.5-10 parts by weight in relations to 100 parts by weight of the binder resin (A).
- 16. A toner of claim 13, wherein it comprises a releasant, and a content of the releasant is 2-20 parts by weight in relations to 100 parts by weight of the binder resin (A).
- 17. A toner of claim 13, the binder resin (A) is polyester resin.
- 18. A toner of claim 13, wherein the polymer (B) is a homopolymer or a copolymer of an aromatic monomer and/or an aliphatic monomer.
- 19. A toner of claim 18, wherein (i) the aromatic monomer is a monomer selected from a class consisting of styrene, vinyltoluene, α-methylstyrene, isopropenyltoluene and indene, and (ii) the aliphatic monomer is a monomer selected from a class consisting of isoprene, piperylene, 2-methyl butene-1 and 2-methyl butene-2.
- 20. A toner of claim 13, wherein the polymer (B) has a grindability index of 0.1-1.0, said grindability index being defined as follows:
Priority Claims (1)
Number |
Date |
Country |
Kind |
241109/2000 |
Aug 2000 |
JP |
|
Parent Case Info
[0001] This application is based on an application No. 241109/2000 filed in Japan, the contents of which are hereby incorporated by reference.