Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-08-30
2002-11-05
Rodee, Christopher (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S108400, C430S109300
Reexamination Certificate
active
06475688
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electrophotographic toner for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, and the like, and an image forming apparatus.
BACKGROUND OF THE INVENTION
In electrophotography, in order to fix toner images onto sheets such as paper or the like, toners are thermally melted and fixed. So-called heat melt fixing is frequently employed. The heat melt fixing is mainly divided into two types, i.e. flash fixing in non-contact, and heated roll or heated belt fixing in contact. Of these, the heated roll and heated belt fixing subjects toners to melt while allowing toner images to come into contact with a heat transfer member. As a result, it is possible to expect to obtain high thermal efficiency. Thus said fixing is effective particularly for electrophotographic copiers, as well as printers, which output images at a high speed.
However, since in such heated roll and heated belt fixing, the heat transfer member is brought into direct contact with melted toner images, offset phenomenon tends to occur, in which a part of the toner image is adhered and transferred onto the heat transfer member, and retransferred to the subsequent fixing sheet to stain the resulting images. Further, when the heat transfer member comes into contact with a toner image, contact charging phenomenon occurs and a phenomenon occurs in which said heat transfer member is charged. Electrostatic charge accumulated in said heat transfer member, prior to contact with the forthcoming heat transfer member, electrostatically repels or attracts an unfixed toner image and thus turbulence of images or so-called image dust tends to be caused. This phenomenon occurs markedly in an image forming apparatus which fixes said images at a high speed.
In order to minimize said offset phenomenon, the supply of releasing oil to the fixing roll or the incorporation of offset preventing agents (occasionally referred to as releasing agents) have been carried out. However, the supply of said releasing oil causes a fixing device to be relatively complex, as well as increasing its dimensions. In addition, it is difficult to conduct a stable supply of said oil. Thus, it is impossible to achieve sufficient minimization of the offset. Further, the incorporation of said offset preventing agents into the toner is relatively effective for minimizing the offset. On the other hand, however, problems are accompanied in which charging toner is hindered. As a result, the image dust tends to be caused and it is not always possible to obtain high quality images.
In order to minimize the retardation for charging toners, charge control agents have been tried. However, since the chargeability of said charge control agents is great, it is difficult to achieve uniform dispersion in the toners. In addition, the dispersion of said releasing agents is degraded due to the strength of its chargeability, and it is impossible to sufficiently obtain the expected offset preventing effects.
SUMMARY OF THE INVENTION
It is an object of the present invention to obtain a high quality fixed image which exhibits sufficient fixed strength in the broad fixable temperature range, as well as forms no image dust.
The present invention and its embodiments will now be described.
1. An electrophotographic toner which comprises a resinous composition for toners having at least two peaks, one at a lower molecular weight of 3,000 to 50,000 and the other at a higher molecular weight of 100,000 to 5,000,000 of the copolymer which is comprised of, as the main component, vinyl based copolymers comprised of styrene based monomers as well as acrylic or methacrylic acid ester based monomers as the structural units along with a fatty acid ester represented by the general formulas (1-1) through (1-4), and a carboxylic acid represented by the general formula (2).
R
1
RCOOR
2
General Formula (1-1)
(one or both of R
1
and R
2
represent an aliphatic group having at least 14 carbon atoms and when either R
1
or R
2
represents an aliphatic group having at least 14 carbon atoms, the other group may represent an alkyl group having no more than 14 carbon atoms, a cycloalkyl group, an alkenyl group, or an aralkyl group.)
[R
1
COO—(CH
2
)
n
]
a
—C—[(CH
2
)
m
—OCOR
2
]
b
General Formula (1-2)
(a and b each represents an integer of 0 to 4; a+b is 4; R
1
and R
2
each represents an organic group having from 1 to 40 carbon atoms; the difference in the number of carbon atoms between R
1
and R
2
is to be at least 3; m and n each represents an integer of 0 to 25; and m and n are not 0 at the same time.
[R
1
COO—(CH
2
)
n
]
a
—C—[(CH
2
)
m
—OH]
b
General Formula (1-3)
(a represents an integer of 0 to 4; b represents an integer of 1 to 4; a +b is 4; R
1
represents an organic group having from 1 to 40 carbon atoms; m and n each represents an integer of 0 to 25; and m and n are not 0 at the same time.)
[R
1
COO—(CH
2
)
n
]
a
—C(R
3
)
k
—[(CH
2
)
m
—OCOR
2
]
b
General Formula (1-4)
(a and b each represents an integer of 0 to 3; a+b is 1 to 3; R
1
and R
2
each represents an organic group having from 1 to 40 carbon atoms; the difference in the number of carbon atoms between R
1
and R
2
is at least 3; R
3
represents a hydrogen atom or an organic group having at least 1 carbon atom (however, when a+b is 2, either one of R3 represents an organic group having at least 1 carbon atom); k represents an integer of 1 to 3; m and n each represents an integer of 0 to 25; and m and n are not 0 at the same time.)
R
4
—COOH General Formula (2)
(R
4
represents a saturated or unsaturated aliphatic group having at least 13 carbon atoms.)
2. An electrophotographic toner comprising a compound represented by general formula (3), described below, along with a resinous composition for toners having at least two peaks, one at a lower molecular weight of 3,000 to 50,000 and the other at a higher molecular weight of 100,000 to 5,000,000 of the copolymer which is comprised of, as the main component, vinyl based copolymers comprised of styrene based monomers as well as acrylic or methacrylic acid ester based monomers as the structural units.
(R
4
through R
7
each represents a hydrogen atom or a univalent substituent; a plurality of these may be substituted or may have a ring structure including a condensed ring. Further, R
4
through R
7
may be the same or different. M represents a trivalent metal, and X represents a univalent or divalent positive ion which neutralizes the electrical charge.)
3. The electrophotographic toner described in 2. above comprising a fatty acid ester represented by said general formula (1) as well as a carboxylic acid represented by said general formula (2).
4. The electrophotographic toner described in 1., 2., or 3. above comprising a crystalline compound having a low melting point.
5. The electrophotographic toner described in 1., 2., 3. or
4. above comprising a polyolefin component.
6. An electrophotographic toner comprising a resinous composition for toners, which is comprised of a matrix phase along with a domain phase which is dispersed in said matrix phase, a fatty acid ester represented by said general formula (1), and a carboxylic acid represented by said general formula (2).
7. An electrophotographic toner comprising a resinous composition for toners, which is comprised of a matrix phase along with a domain phase which is dispersed in said matrix phase as well as a compound represented by said general formula (3).
8. The electrophotographic toner described in 7. above comprising a fatty acid ester represented by said general formula (1) as well as a carboxylic acid represented by said general formula (2).
9. The electrophotographic toner described in 6., 7., or 8. above, comprising a crystalline compound having a low melting point.
10. The electrophotographic toner described in 6., 7., 8., or 9, above, comprising a polyolefin component.
11
Shirose Meizo
Tamura Kishio
Cantor & Colburn LLP
Konica Corporation
Rodee Christopher
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