Polyester resin for toner, toner, developer, and image formation device
A polyester resin for a toner, the polyester resin including: a segment derived from an alcohol component; and a segment derived from a carboxylic acid component, wherein the alcohol component includes a trivalent or higher aliphatic alcohol, and wherein the polyester resin satisfies Expressions (1) to (3) below: 500 ≤ Weight average molecular weight ( Mw ) ( Valence of the trivalent or higher aliphatic alcohol ) × ( Amount of the trivalent or higher aliphatic alcohol ) ≤ 4 , 000 ; Expression ( 1 ) 4,000≦Weight average molecular weight (Mw)≦25,000 Expression (2); and 0.5≦(Amount of the trivalent or higher aliphatic alcohol)≦6.5 Expression (3), where, in the Expressions (1) and (3), the Amount of the trivalent or higher aliphatic alcohol denotes a percent by mole of the trivalent or higher aliphatic alcohol relative to the alcohol component.
1. A polyester resin for a toner, the polyester resin comprising:
a segment derived from an alcohol component; and
a segment derived from a carboxylic acid component,
wherein the alcohol component comprises a trivalent or higher aliphatic alcohol, and
wherein the polyester resin satisfies Expressions (1) to (3) below:
500
≤
Weight
average
molecular
weight
(
Mw
)
(
Valence
of
the
trivalent
or
higher
aliphatic
alcohol
)
×
(
Amount
of
the
trivalent
or
higher
aliphatic
alcohol
)
≤
4
,
000
;
Expression
(
1
)
4,000<weight average molecular weight (Mw)<25,000 Expression (2);
and
0.5≦(amount of the trivalent or higher aliphatic alcohol)≦6.5 Expression (3),
where, in the Expressions (1) and (3), the amount of the trivalent or higher aliphatic alcohol denotes a percent by mole of the trivalent or higher aliphatic alcohol relative to the alcohol component.
2. The polyester resin according to claim 1 ,
wherein the polyester resin satisfies Expression (1-1) below:
800
≤
Weight
average
molecular
weight
(
Mw
)
(
Valence
of
the
trivalent
or
higher
aliphatic
alcohol
)
×
(
Amount
of
the
trivalent
or
higher
aliphatic
alcohol
)
≤
2
,
000
Expression
(
1
-
1
)
where, in the Expression (1-1), the amount of the trivalent or higher aliphatic alcohol denotes a percent by mole of the trivalent or higher aliphatic alcohol relative to the alcohol component.
3. The polyester resin according to claim 1 , wherein the trivalent or higher aliphatic alcohol is a trivalent or tetravalent aliphatic alcohol.
4. The polyester resin according to claim 1 , wherein the polyester resin satisfies Expression (3-1) below:
2.0≦(amount of the trivalent or higher aliphatic alcohol)≦4.0 Expression (3-1)
where, in the Expression (3-1), the amount of the trivalent or higher aliphatic alcohol denotes a percent by mole of the trivalent or higher aliphatic alcohol relative to the alcohol component.
5. The polyester resin according to claim 1 , wherein the polyester resin satisfies Expression (2-1) below:
8,000≦Weight average molecular weight (Mw)≦20,000 Expression (2-1).
6. A toner, comprising the polyester resin according to claim 1 .
7. The toner according to claim 6 , wherein the toner has glass transition temperature [Tg1st (toner)] of 20° C. or more but 50° C. or less, the glass transition temperature [Tg1st (toner)] being a glass transition temperature at first heating in differential scanning calorimetry (DSC).
8. The toner according to claim 6 , wherein the toner has glass transition temperature [Tg2nd (toner)] of 5° C. or more but 35° C. or less, the glass transition temperature [Tg2nd (toner)] being a glass transition temperature at second heating in differential scanning calorimetry (DSC).
9. The toner according to claim 6 ,
wherein the toner comprises a tetrahydrofuran (THF) insoluble matter,
wherein the THF insoluble matter comprises a second polyester resin,
wherein components constituting the second polyester resin comprise a diol component and a cross-linking component,
wherein the diol component comprises 50 mol % or more of an aliphatic diol having from 3 through 10 carbon atoms, and
wherein the cross-linking component comprises the trivalent or higher aliphatic alcohol.
10. The toner according to claim 9 , wherein the second polyester resin comprises at least one of a urethane bond and a urea bond.
11. A developer comprising:
the toner according to claim 6 ; and
a carrier.
12. An image forming apparatus comprising:
an electrostatic latent image bearer;
an electrostatic-latent-image-forming means configured to form an electrostatic latent image on the electrostatic latent image bearer; and
a developing means comprising a toner and configured to develop the electrostatic latent image formed on the electrostatic latent image bearer to form a visible image,
wherein the toner is the toner according to claim 6 .