Toner for electrostatic charge development
To provide a toner, which contains a binder resin, a colorant, and a releasing agent, wherein the binder resin contains a low molecular weight resin component, where the low molecular weight resin component has a resin softening coefficient (A), represented by the following formula (1), satisfying A>0.165, and has storage elastic modulus (dyne/cm 2 ) G′(Tfb) satisfying G′(Tfb)≦1×10 4 where Tfb is a flow onset temperature (° C.) of the low molecular weight resin component as measured by a capillary rheometer: A =|[( r 1)−ln G ′( r 2)]/( T 1− T 2)| Formula (1) (where T1 is temperature (° C.) at which storage elastic modulus G′(r1) is 1×10 5 (dyne/cm 2 ) and T2 is temperature (° C.) at which storage elastic modulus G′(r2) is 1×10 3 (dyne/cm 2 ) as measured by means of a viscoelasticity measuring device with measuring frequency of 1 Hz, and measuring distortion of 1 deg; and | | represents an absolute value.).
1. A toner, comprising:
a binder resin;
a colorant; and
a releasing agent,
wherein:
the binder resin comprises a low molecular weight resin component having a resin softening coefficient (A), represented by formula (1);
A=|[lnG′(r1)−lnG′(r2)]/(T1−T2)| (1),
and has storage elastic modulus (dyne/cm 2 ) G′(Tfb) satisfying G′(Tfb)≦1×10 4 where Tfb is a flow onset temperature (° C.) of the low molecular weight resin component as measured by a capillary rheometer;
A>0.165;
T1 is temperature (° C.) at which storage elastic modulus G′(r1) is 1×10 5 (dyne/cm 2 );
T2 is temperature (° C.) at which storage elastic modulus G′(r2) is 1×10 3 (dyne/cm 2 ) as measured by a viscoelasticity measuring device with measuring frequency of 1 Hz, and measuring distortion of 1 deg; and
∥ represents an absolute value.
2. The toner according to claim 1 , wherein the low molecular weight resin component is low molecular weight polyester.
3. A two-component developer, comprising:
the toner of claim 2 ; and
a carrier.
4. The toner according to claim 2 , wherein the low molecular weight polyester has a weight average molecular weight of 2,000 to 10,000.
5. The toner according to claim 4 , wherein the low molecular weight polyester has an acid value of 1.0 mgKOH to 50.0 mgKOH/g.
6. The toner according to claim 4 , wherein the low molecular weight polyester has glass transition temperature of 35° C. to 65° C.
7. The toner according to claim 4 , wherein the binder resin further comprises a crystalline polyester resin comprising a polyhydric alcohol and a carboxylic acid.
8. The toner according to claim 2 , wherein the low molecular weight polyester has an acid value of 1.0 mgKOH to 50.0 mgKOH/g.
9. The toner according to claim 8 , wherein a mass ratio of the low molecular weight polyester to the crystalline polyester, which is represented by (low molecular weight polyester/crystalline polyester), is 1.5 to 2.
10. The toner according to claim 2 , wherein the low molecular weight polyester has glass transition temperature of 35° C. to 65° C.
11. The toner according to claim 2 , wherein the binder resin further comprises a crystalline polyester resin comprising a polyhydric alcohol and a carboxylic acid.
12. The toner according to claim 11 , wherein the crystalline polyester resin comprises an aromatic component in an amount larger than an amount of an aromatic component contained in the low molecular weight polyester.
13. The toner according to claim 12 , wherein:
the binder resin satisfies formula (2):
1.80≧|SP( b )−SP( a )|≧1.05 (2);
SP( a ) is a solubility parameter (SP) value of the crystalline polyester; and
SP( b ) is a solubility parameter (SP) value of the low molecular weight polyester.
14. The toner according to claim 11 , wherein a mass ratio of the low molecular weight polyester to the crystalline polyester, which is represented by (low molecular weight polyester/crystalline polyester), is 1.5 to 2.
15. The toner according to claim 11 , wherein:
the binder resin satisfies formula (2):
1.80≧|SP( b )−SP( a )|≧1.05 (2);
SP(a) is a solubility parameter (SP) value of the crystalline polyester; and
SP(b) is a solubility parameter (SP) value of the low molecular weight polyester.
16. A two-component developer, comprising:
the toner of claim 1 ; and
a carrier.
17. An image forming apparatus, comprising:
an image bearing member;
an electrostatic image forming unit configured to form an electrostatic image on the image bearing member; and
a developing unit configured to develop the electrostatic image with a toner to form a visible image,
wherein:
the developing unit is equipped with a toner supplying device, where the toner supplying device comprises:
a toner container housing the toner therein;
an air inflow unit configured to flow air into the toner container;
a pump unit configured to supply the toner as a fluid with the flown air; and
a toner feeding tube configured to feed the toner from the toner container to the developing unit;
the toner container comprises:
a flexible member capable of reducing a volume thereof by 60% or greater; and
the toner housed in the flexible member,
the toner comprises:
a binder resin;
a colorant; and
a releasing agent
the binder resin comprises a low molecular weight resin component having a resin softening coefficient (A) represented by formula (1):
A =|[lnG′(r1)−lnG′(r2)](T1−T2)| (1),
and has storage elastic modulus (dyne/cm 2 ) G′(Tfb) satisfying G′(Tfb)≦1×10 4 where Tfb is a flow onset temperature (° C.) of the low molecular weight resin component as measured by a capillary rheometer;
A>0.165;
T1 is temperature (° C.) at which storage elastic modulus G′(r1) is 1×10 5 (dyne/cm 2 );
T2 is temperature (° C.) at which storage elastic modulus G′(r2) is 1×10 3 (dyne/cm 2 ) as measured by a viscoelasticity measuring device with measuring frequency of 1 Hz, and measuring distortion of 1 deg; and
∥ represents an absolute value.