U.S. patent application number 14/257990 was filed with the patent office on 2014-08-07 for charging member, process cartridge, and electrophotographic image forming apparatus.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Hidekazu Matsuda, Noboru Miyagawa.
Application Number | 20140221183 14/257990 |
Document ID | / |
Family ID | 51020403 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140221183 |
Kind Code |
A1 |
Miyagawa; Noboru ; et
al. |
August 7, 2014 |
CHARGING MEMBER, PROCESS CARTRIDGE, AND ELECTROPHOTOGRAPHIC IMAGE
FORMING APPARATUS
Abstract
In order to maintain the image quality of a recent high-speed
electrophotographic apparatus, a charging member is provided which
hardly causes charging unevenness of a photosensitive member even
when vibration of the photosensitive member occurs. The charging
member includes an electro-conductive support, an
electro-conductive elastic layer, and a surface layer. The elastic
layer contains a resin having an epichlorohydrin chain in the
molecular structure and a specific flavonoid compound having two or
more hydroxyl groups in the molecular structure.
Inventors: |
Miyagawa; Noboru;
(Suntou-gun, JP) ; Matsuda; Hidekazu; (Susono-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
51020403 |
Appl. No.: |
14/257990 |
Filed: |
April 21, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2013/007550 |
Dec 24, 2013 |
|
|
|
14257990 |
|
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Current U.S.
Class: |
492/18 ; 399/176;
428/383 |
Current CPC
Class: |
G03G 15/0233 20130101;
G03G 21/18 20130101; C08K 5/053 20130101; G03G 15/02 20130101; C08K
5/132 20130101; Y10T 428/2947 20150115 |
Class at
Publication: |
492/18 ; 428/383;
399/176 |
International
Class: |
B05C 1/08 20060101
B05C001/08; B32B 27/00 20060101 B32B027/00; G03G 15/02 20060101
G03G015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2012 |
JP |
2012-285241 |
Claims
1. A charging member comprising: an electro-conductive support, an
electro-conductive elastic layer, and a surface layer, wherein: the
elastic layer comprises a resin having an epichlorohydrin chain in
the molecular structure, and at least one compound selected from
the group consisting of a compound represented by the following
formula (1), a compound represented by the following formula (3),
and a compound represented by the following formula (4):
##STR00035## wherein R.sub.1 represents a hydroxyl group or a
substituent represented by the following formula (2), and R.sub.2
to R.sub.10 each independently represent a hydrogen atom or a
hydroxyl group, wherein at least two of R.sub.1 to R.sub.10 are
hydroxyl groups; ##STR00036## wherein * represents a bonding
portion with the 3-position carbon atom of a compound represented
by the formula (1); ##STR00037## wherein R.sub.11 to R.sub.20 each
independently represent an atom or a group selected from the group
consisting of a hydrogen atom, a hydroxyl group, and a methoxy
group, wherein at least two of R.sub.11 to R.sub.20 are hydroxyl
groups; ##STR00038## wherein R.sub.21 to R.sub.30 each
independently represent an atom or a group selected from the group
consisting of a hydrogen atom, a hydroxyl group, and a methoxy
group, wherein at least two of R.sub.21 to R.sub.30 are hydroxyl
groups.
2. The charging member according to claim 1, wherein the elastic
layer comprises a compound represented by the formula (1), wherein
the compound represented by the formula (1) being at least one
compound selected from the group consisting of a compound
represented by the following formula (5), a compound represented by
the following formula (6), a compound represented by the following
formula (7), and a compound represented by the following formula
(8): ##STR00039##
3. The charging member according to claim 1, wherein the elastic
layer comprises a compound represented by the formula (4), wherein
the compound represented by the formula (4) being at least one
compound selected from the group consisting of a compound
represented by the following formula (9) and a compound represented
by the following formula (10): ##STR00040##
4. The charging member according to claim 1, wherein the resin is a
copolymer having an epichlorohydrin chain, an ethylene oxide chain,
and an allyl glycidyl ether chain in the molecular structure.
5. An electrophotographic image forming apparatus comprising an
electrophotographic photosensitive member and a charging member
according to claim 1 arranged for charging the electrophotographic
photosensitive member.
6. A process cartridge integrally having a charging member
according to claim 1 and at least one selected from the group
consisting of an electrophotographic photosensitive member, a
developing unit, a transferring unit and a cleaning unit, wherein
the process cartridge is detachably mountable to an
electrophotographic image forming apparatus.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International
Application No. PCT/JP2013/007550, filed Dec. 24, 2013, which
claims the benefit of Japanese Patent Application No. 2012-285241,
filed Dec. 27, 2012.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a charging member, a
process cartridge, and an electrophotographic image forming
apparatus.
[0004] 2. Description of the Related Art
[0005] An electrophotographic image forming apparatus (hereinafter
also referred to as electrophotographic apparatus) using an
electrophotographic method mainly includes an electrophotographic
photosensitive member (hereinafter also referred to as
"photosensitive member"), a charging device, an exposure device, a
developing device, a transferring device, and a fixing device. The
charging device allows the surface of a photosensitive member to be
charged to a predetermined potential through application of a
voltage. A method for charging the surface of a photosensitive
member by application of a voltage to a charging member arranged in
contact with or adjacent to the surface of a photosensitive member
is commonly used (herein after also referred to "contact charging
method").
[0006] In a contact charging method, vibration of the
photosensitive member in an electrophotographic apparatus may cause
unstable contact between the charging member and the photosensitive
member, resulting in uneven charging to the surface of a
photosensitive member in some cases.
[0007] In particular with the improved process speed of the recent
electrophotographic apparatus, vibration of the photosensitive
member tends to increase. In order to solve the problem, Japanese
Patent Application Laid-Open No. 2001-209236 discloses a charging
member with enhanced vibration absorbability which has an elastic
layer with a controlled hardness and a controlled specific
gravity.
SUMMARY OF THE INVENTION
[0008] As a result of investigation by the present inventors,
however, it was found that there is a room for improvement in the
charging member in Japanese Patent Application Laid-Open No.
2001-209236 for eliminating charging unevenness of a photosensitive
member caused by vibration of the photosensitive member.
[0009] The present invention is, therefore, directed to providing a
charging member which hardly causes charging unevenness of a
photosensitive member even when vibration of the photosensitive
member occurs.
[0010] Further, the present invention is directed to providing a
process cartridge and an electrophotographic apparatus, capable of
stably forming a high-quality electrophotographic image.
[0011] According to one aspect of the present invention, there is
provided a charging member having an electro-conductive support, an
electro-conductive elastic layer, and a surface layer. The elastic
layer contains a resin having an epichlorohydrin chain in the
molecular structure and at least one compound selected from the
group consisting of a compound represented by the following formula
(1), a compound represented by the following formula (3), and a
compound represented by the following formula (4).
##STR00001##
[0012] In the formula (1), R.sub.1 represents a hydroxyl group or a
substituent represented by the following formula (2), and R.sub.2
to R.sub.10 each independently represent a hydrogen atom or a
hydroxyl group, wherein at least two of R.sub.1 to R.sub.10 are
hydroxyl groups.
##STR00002##
[0013] In the formula (2), * represents a bonding portion with the
3-position carbon atom of a compound represented by the formula
(1).
##STR00003##
[0014] In the formula (3), R.sub.11 to R.sub.20 each independently
represent an atom or a group selected from the group consisting of
a hydrogen atom, a hydroxyl group, and a methoxy group, wherein at
least two of R.sub.11 to R.sub.20 are hydroxyl groups.
##STR00004##
[0015] In the formula (4), R.sub.21 to R.sub.30 each independently
represent an atom or a group selected from the group consisting of
a hydrogen atom, a hydroxyl group, and a methoxy group, wherein at
least two of R.sub.21 to R.sub.30 are hydroxyl groups.
[0016] According to another aspect of the present invention, there
is provided an electrophotographic image forming apparatus having
an electrophotographic photosensitive member and a charging member
arranged to charge the electrophotographic photosensitive member,
wherein the charging member is the above-described charging
member.
[0017] According to further aspect of the present invention, there
is provided a process cartridge which integrally supports the
charging member and at least one selected from the group consisting
of an electrophotographic photosensitive member, a developing unit,
a transferring unit, and a cleaning unit, and is detachably
mountable to an electrophotographic image forming apparatus.
[0018] The present invention provides a charging member which
hardly causes charging unevenness of a photosensitive member even
when vibration of the photosensitive member occurs.
[0019] The present invention also provides a process cartridge and
an electrophotographic apparatus, capable of stably forming a
high-quality electrophotographic image.
[0020] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1A is a diagram of a charging member according to an
example of the present invention, illustrating a schematic
cross-sectional view of a charging roller in the direction
orthogonal to the axis of the charging roller.
[0022] FIG. 1B is a diagram of a charging member according to an
embodiment of the present invention, illustrating a schematic side
view of a charging roller.
[0023] FIG. 2 is a diagram illustrating a mechanism by which the
tan .delta. of the elastic layer of a charging member of the
present invention increases.
[0024] FIG. 3 is a diagram illustrating a measurement method of the
electric resistance of a charging member of the present
invention.
[0025] FIG. 4 is a schematic constitution diagram of an
electrophotographic apparatus according to an embodiment of the
present invention.
[0026] FIG. 5 is a schematic constitution diagram of a process
cartridge according to an embodiment of the present invention.
[0027] FIG. 6 is a diagram illustrating a measurement method of the
tan .delta. of the elastic layer of a charging member.
DESCRIPTION OF THE EMBODIMENTS
[0028] Preferred embodiments of the present invention will now be
described in detail in accordance with the accompanying
drawings.
[0029] <<Banding Image>>
[0030] To begin with, a banding image is described in the
following. A banding image is a streak-like image unevenness
existing on an outputted half tone image (image drawn with
horizontal lines with a 1-dot width and 2-dot space in the
direction vertical to the rotation direction of a photosensitive
member). The streak-like image is an image having streaks vertical
to the rotation direction of a photosensitive member (discharge
direction of a medium of paper). As a banding image, a streak-like
image corresponding to the cycle of a charging member may be
typically identified. A charging member with the configuration of
the present invention suppresses the occurrence of the banding
image due to charging unevenness of a photosensitive member caused
by vibration of a photosensitive member.
[0031] <<Charging Member>>
[0032] The shape of a charging member of the present invention is
not specifically limited, including, for example, a roller shape, a
flat-plate shape, or a belt shape. Although the description is
focused on a charging roller in the following, the present
invention is not limited thereto. Firstly, as an aspect of a
charging member of the present invention, a specific configuration
example of a charging roller is shown in FIG. 1A and FIG. 1B.
[0033] FIG. 1A is a schematic cross-sectional view in the direction
orthogonal to the axis of a charging roller. FIG. 1B is a schematic
side view of a charging roller. The charging roller shown in FIG.
1A and FIG. 1B includes an electro-conductive support 1, an
electro-conductive elastic layer 2 formed on the support, and a
surface layer 3 formed on the elastic layer. In the present
invention, another layer (e.g. adhesion layer) may be arranged
between the support and the elastic layer, or between the elastic
layer and the surface layer.
[0034] <Electro-Conductive Support>
[0035] As an electro-conductive support (substrate), conductivity
(volume resistivity: 1.times.10.sup.-6 .OMEGA.cm to
1.times.10.sup.2 .OMEGA.cm) and function for supporting an elastic
layer, a surface layer and the like to be arranged thereon are
required. Examples of the material include a metal such as iron,
copper, stainless steel, aluminum, and nickel and an alloy thereof.
Plating or the like may be applied to these surfaces so as to
impart scratch resistance within a range not to impair the
conductivity. An electro-conductive support having surface
conductivity produced by coating the surface of a resin substrate
with metals or the like, or an electro-conductive support produced
from an electro-conductive resin composition can be also used as
the electro-conductive support. The shape of the electro-conductive
support can be selected according the shape of a charging member to
be produced, examples of which include, for example, a hollow
cylinder shape, a solid cylindrical shape and a belt shape.
[0036] <Elastic Layer>
[0037] The elastic layer 2 of the present invention has the same
degree of conductivity which the elastic layer of a charging member
typically has. More specifically, the layer has conductivity with a
volume resistivity approximately ranging from 1.times.10.sup.2
.OMEGA.cm to 1.times.10.sup.6 .OMEGA.cm. The elastic layer 2
contains a resin having an epichlorohydrin chain in the molecular
structure and a specific flavonoid compound having two or more
hydroxyl groups in the molecular structure. The elastic layer may
also contain a conducting agent for imparting conductivity and
other additives.
[0038] Since the elastic layer contains a resin having an
epichlorohydrin chain in the molecular structure and a specific
flavonoid compound having two or more hydroxyl groups in the
molecular structure, the loss tangent (tan .delta.) of the elastic
layer may be increased. Even when the photosensitive member in
contact the charging member having such an elastic layer vibrates,
the vibration attenuates in the elastic layer of the charging
member. Consequently, the contact state between the photosensitive
member and the charging member may be stabilized and the occurrence
of a banding image caused by vibration of the photosensitive member
may be suppressed.
[0039] The present inventors suppose the mechanism by which the tan
.delta. of the elastic layer in the configuration increases as
follows.
[0040] As shown in FIG. 2, the epichlorohydrin chain of a resin 4
having the epichlorohydrin chain in the molecular structure forms a
hydrogen bond 6 with a hydroxyl group of a specific flavonoid
compound 5 having two or more hydroxyl groups in the molecular
structure (a flavan compound described in FIG. 2). The .alpha.
hydrogen of the epichlorohydrin chain has acid properties under the
influence of a Cl group which is an electron withdrawing group. The
specific flavonoid compound having two or more hydroxyl groups in
the molecule has a high dissociation degree of the proton of a
hydroxyl group due to the appropriate positions of a benzopyran
ring and a benzene ring. Consequently, the hydrogen bond shown in
FIG. 2 may be formed. It is believed that the hydrogen bonds thus
formed among the molecules convert the vibration energy to the
thermal energy, resulting in the increase of the tan .delta..
[0041] In the present invention, the resin having an
epichlorohydrin chain in the molecular structure and the specific
flavonoid compound which are in a hydrogen-bonded state may be
contained in an elastic layer.
[0042] (Flavonoid Compound)
[0043] The flavonoid compound contained in an elastic layer is at
least one compound selected from the group consisting of a compound
represented by the formula (1) (hereinafter also referred to as
"flavan compound"), a compound represented by the formula (3)
(hereinafter also referred to as "flavanone compound"), and a
compound represented by the formula (4) (hereinafter also referred
to as "flavone compound").
[0044] The total content of these flavonoid compound contained in
an elastic layer is preferably 2.0 mass % or more from the view
point of the tan .delta., and preferably 20 mass % or less from the
view point of C-set. On this occasion, preferably a total content
of 5.0 parts by mass or more and 30 parts by mass or less of the
flavonoid compounds relative to 100 parts by mass of a resin having
an epichlorohydrin chain in the molecular structure to be described
are blended. The C-set means the so-called permanent compression
strain (compression set), which is a deformation to be hardly
restored at the part in contact with the photosensitive member of a
charging roller.
[0045] In the case of combination use of a flavan compound, a
flavanone compound, and a flavone compound, the blending ratios may
be appropriately set without specific limitations.
[0046] Flavan Compound
[0047] The flavan compound (also including a flavanol compound) for
use in the present invention is a compound represented by the
formula (1).
##STR00005##
[0048] In the formula (1), R.sub.1 represents a hydroxyl group or a
substituent represented by the following formula (2), and R.sub.2
to R.sub.10 each independently represent a hydrogen atom or a
hydroxyl group, wherein at least two of R.sub.1 to R.sub.10 are
hydroxyl groups. As described above, so long as the flavan compound
has two or more hydroxyl groups, all of the R.sub.1 to R.sub.10 may
be hydroxyl groups.
##STR00006##
[0049] In the formula (2), * represents the bonding portion with
the 3-position carbon atom of a compound represented by the formula
(1).
[0050] Examples of the flavan compound having two or more hydroxyl
groups in the molecular structure include epicatechin,
epigallocatechin, epicatechin gallate, epigallocatechin gallate,
6,4'-dihydroxyflavan, and 3,6,4'-trihydroxyflavan.
[0051] Among them, at least one of epicatechin, epigallocatechin,
epicatechin gallate, and epigallocatechin gallate can be used as
the flavan compound from the view point of the dispersibility in an
elastic layer.
[0052] Flavanone Compound
[0053] The flavanone compound (also including a flavanonol
compound) for use in the present invention is a compound
represented by the formula (3).
##STR00007##
[0054] In the formula (3), R.sub.11 to R.sub.20 each independently
represent an atom or a group selected from the group consisting of
a hydrogen atom, a hydroxyl group, and a methoxy group, wherein at
least two of R.sub.11 to R.sub.20 are hydroxyl groups. As described
above, so long as the flavanone compound has two or more hydroxyl
groups, all of the R.sub.11 to R.sub.20 may be hydroxyl groups.
[0055] Examples of the flavanone compound having two or more
hydroxyl groups in the molecular structure include naringenin,
hesperetin, alpinon, eriodictyol, sakuranetin, citronetin,
taxifolin, and liquiritigenin.
[0056] Among them, at least one of naringenin and hesperetin can be
used as the flavanone compound, from the view point of the
dispersibility in an elastic layer.
[0057] Flavone Compound
[0058] The flavone compound (also including a flavonol compound)
for use in the present invention is a compound represented by the
formula (4).
##STR00008##
[0059] In the formula (4), R.sub.21 to R.sub.30 each independently
represent an atom or a group selected from the group consisting of
a hydrogen atom, a hydroxyl group, and a methoxy group, wherein at
least two of R.sub.21 to R.sub.30 are hydroxyl groups. As described
above, so long as the flavone compound has two or more hydroxyl
groups, all of the R.sub.21 to R.sub.30 may be hydroxyl groups.
[0060] Examples of the flavone compound having two or more hydroxyl
groups in the molecular structure include
3,5,6,7,3',4'-hexahydroxyflavone,
3,5,7,3',4',5'-hexahydroxyflavone, 5,7,4'-trihydroxyflavone,
3,7,3',4'-tetrahydroxyflavone, 5,7,3',4'-tetrahydroxyflavone,
3,5,7,4'-tetrahydroxyflavone, 3,5,7,3',4'-pentahydroxyflavone,
3,5,7,2',4'-pentahydroxyflavone, 7,8-dihydroxyflavone,
5,7-dihydroxyflavone, 5,7-dihydroxy-4'-methoxyflavone,
4'-methoxy-3,5,7-trihydroxyflavone, and
3-methoxy-5,7,3',4'-tetrahydroxyflavone.
[0061] Among them, at least one of 3,5,6,7,3',4'-hexahydroxyflavone
and 3,5,7,3',4',5'-hexahydroxyflavone can be used as the flavone
compound, from the view point of the dispersibility in an elastic
layer.
[0062] (Resin Having an Epichlorohydrin Chain in the Molecular
Structure)
[0063] The resin (rubber) having an epichlorohydrin chain in the
molecular structure for use in the present invention is a resin
having a unit (epichlorohydrin unit) by ring-opening polymerization
of epichlorohydrin in the molecular structure. The resin may
include other monomer units such as an alkylene oxide unit and an
allyl glycidyl ether unit besides the epichlorohydrin unit in the
molecular unit.
[0064] Examples of the resin (epichlorohydrin rubber) include an
epichlorohydrin homopolymer, an epichlorohydrin-alkylene oxide
copolymer, an epichlorohydrin-allyl glycidyl ether copolymer, and
an epichlorohydrin-alkylene oxide-allyl glycidyl ether ternary
copolymer. In particular, an epichlorohydrin-alkylene oxide-allyl
glycidyl ether ternary copolymer may be suitably used as the resin
among them, having stable conductivity in the medium resistance
range. The degree of polymerization and the composition ratio of
the epichlorohydrin-alkylene oxide-allyl glycidyl ether ternary
copolymer are arbitrarily adjusted, so that the conductivity and
the workability may be controlled.
[0065] The content of the epichlorohydrin chain in the resin is
preferably 10 mol % or more and 60 mol % or less relative to 100
mol % of the resin. In the case of the resin having an allyl
glycidyl ether chain in the molecular structure, the content of the
allyl glycidyl ether chain in the resin is preferably 1 mol % or
more and 15 mol % or less relative to 100 mol % of the resin.
[0066] Examples of the alkylene oxide chain include an ethylene
oxide chain and a propylene oxide chain. Among them, an ethylene
oxide chain can be used for achieving high conductivity. The
content of the ethylene oxide chain in the resin can be 40 mol % or
more and 80 mol % or less.
[0067] The content of the resin having an epichlorohydrin chain in
the molecular structure in an elastic layer can be 30 mass % or
more from the view point of the tan .delta. and 90 mass % or less
from the view point of the electric resistance value (due to the
tendency to cause high resistance with a high content).
[0068] The elastic layer for use in the present invention may
contain other common rubber (resin) on an as needed basis besides
the resin having an epichlorohydrin chain in the molecular
structure. Examples of the other common rubber include
acrylonitrile butadiene rubber, acrylic rubber, urethane rubber,
ethylene-propylene rubber, styrene-butadiene rubber, silicone
rubber, and acrylic rubber. The content of the common rubber can be
40 parts by mass or less relative to 100 parts by mass of the resin
having an epichlorohydrin chain in the molecular structure in the
case of containing the common rubber.
[0069] (Conducting Agent)
[0070] The general classification of conductive agents includes an
electron conductive agent and an ionic conductive agent, either of
which may be used in the present invention.
[0071] Examples of the electron conductive agent include carbon
black, graphite, and a metal oxide (e.g. conductive zinc oxide and
conductive tin oxide). These conductive agents may be used singly
or in combinations of two or more. The amount of the electron
conductive agent contained in an elastic layer can be 5.0 parts by
mass or more and 60 parts by mass or less relative to 100 parts by
mass of the resin having an epichlorohydrin chain in the molecular
structure.
[0072] Examples of the ionic conductive agent include an inorganic
ionic material such as lithium perchlorate, a cationic surfactant
such as a modified aliphatic dimethyl ethyl ammonium ethosulfate, a
zwitterionic surfactant such as dimethyl alkyl lauryl betaine, a
quaternary ammonium salt such as trimethyl octadecyl ammonium
perchlorate, and an organic lithium salt such as lithium
trifluoromethanesulfonate. These conductive agents may be used
singly or in combinations of two or more. Among the ionic
conductive agents, a perchloric acid quaternary ammonium salt in
particular is suitably used, having stable resistance to changes in
environment. The amount of the ionic conductive agent contained in
an elastic layer is preferably 0.01 parts by mass or more and 5
parts by mass or less, more preferably 0.1 parts by mass or more
and 2 parts by mass or less, relative to 100 parts by mass of the
resin having an epichlorohydrin chain in the molecular
structure.
[0073] (Other Additives)
[0074] Furthermore, the elastic layer may appropriately include
other additives such as a plasticizer, an extender, a vulcanizing
agent, a vulcanizing accelerator, an antiaging agent, and a foaming
agent.
[0075] <Surface Layer>
[0076] The surface layer for use in the present invention has
conductivity with a volume resistivity of 1.times.10.sup.4
.OMEGA.cm to 1.times.10.sup.10 .OMEGA.cm, and may contain a binder
and fine particles.
[0077] As the binder for use in the surface layer, a resin can be
used from the view point of high release properties without causing
contamination of a photosensitive member or other members.
[0078] As the binder resin, a known binder resin in the field of
electrophotographic apparatus such as a thermosetting resin and a
thermoplastic resin may be used. Among them, a fluororesin, a
polyamide resin, an acrylic resin, a polyurethane resin, an acrylic
urethane resin, a silicone resin, a butyral resin and the like are
more preferred. These binder resins may be used singly, or two or
more kinds of these may be used in combination. Alternatively, the
raw material monomers of these resins may be copolymerized to be
used as a copolymer.
[0079] Three types of fine particles can be used, including
conductive fine particles, metal oxide fine particles, and resin
fine particles.
[0080] The electro-conductive fine particles are used for the
purpose of adjusting the electric resistance of the surface layer.
Examples of the electro-conductive fine particles include carbon
black, graphite, and carbon black-silica composite particles. Among
them, carbon black-silica composite particles can be used from the
view point of dispersibility. The volume average particle diameter
of conductive fine particles can be 10 nm or more from the view
point of dispersibility and 500 nm or less from the view point of
conductivity to be achieved.
[0081] The metal oxide particles are used for the purposes of
adjusting the electric resistance of the surface layer and
enhancing dispersibility of the electro-conductive particles.
Examples of the metal oxide particles include titanium oxide, zinc
oxide, tin oxide, and indium oxide. Among them, titanium oxide can
be used in the view point of dispersibility enhancement. The volume
average particle diameter of metal oxide fine particles can be 10
nm or more and 500 nm or less from the view point of dispersibility
enhancement.
[0082] The resin fine particles are used for the purpose of
controlling the surface roughness of a charging member. Examples of
the resin fine particles include acrylic resin fine particles,
polymethylmethacrylate resin fine particles, phenol resin fine
particles, silicone resin fine particles, ABS resin fine particles,
melamine resin fine particles, and styrene resin fine particles.
Among them, polymethylmethacrylate resin fine particles can be used
in the view point of dispersibility in the surface layer. The
volume average particle diameter of the resin fine particles can be
5 .mu.m or more and 50 .mu.m or less in the view point of surface
roughness formation.
[0083] <Volume Average Particle Diameter of Fine
Particles>
[0084] The volume average particle diameter of fine particles may
be measured with a laser diffraction particle size distribution
analyzer (trade name: "COULTER LS-230 PARTICLE SIZE ANALYZER" made
by Beckman Coulter, Inc.). In the measurement, a small amount of
module is used with a measurement solvent of isopropyl alcohol
(IPA). Firstly, the inner part of the measurement system of a
measurement apparatus is cleaned with IPA for about 5 minutes, and
a background function is performed after the cleaning.
Approximately 10 mg of fine particles are then added to 50 ml of
IPA. A solution having a suspended sample is subject to a
dispersion treatment for about 2 minutes with an ultrasonic
disperser so as to produce a sample liquid. The sample liquid is
gradually added to the measurement system of the measurement
apparatus, such that the PIDS on the apparatus screen becomes 45%
or more and 55% or less through adjustment of the sample
concentration in the measurement system. Subsequently, the
measurement is performed to obtain the volume average particle
diameter based on the calculation from the volume distribution.
[0085] <Volume Resistivity of Fine Particles>
[0086] The volume resistivity of fine particles is measured under
an environment at 23.degree. C., 55% RH (relative humidity), and
normal pressure (10.sup.5 Pa), using an apparatus having
cylindrical electrodes made of stainless steel (SUS 316) arranged
above and below a hollow cylinder made of polytetrafluoroethylene
(PTFE) having an inner diameter 1 cm.
[0087] More specifically, a measurement sample (fine particles) and
electrodes are firstly left standing under the environment for 12
hours or more so as to have affinity with the environment.
Subsequently, the lower electrode made of SUS is arranged below the
PTFE cylinder, and approximately 2 g of fine particles are evenly
set in. The cylindrical electrode made of SUS is then placed from
above, so that the fine particles are held with the PTFE cylinder
and the upper and lower electrodes. The apparatus is left standing
in a state under a pressure of 10 MPa for 1 minute or more.
Subsequently, a voltage of 200 V is applied to the electrodes, with
a minute electric current meter (trade name: ADVANTEST R8340A ULTRA
HIGH RESISTANCE METER, made by Advantest Corporation). The electric
current is measured after 30 seconds so as to obtain the volume
resistivity based on the calculation from the space between the
electrodes and the electrode area.
[0088] <<Manufacturing Method Of Charging Member>>
[0089] The charging member of the present invention may be
manufactured by a manufacturing method including the following
steps:
[0090] (a) a step of forming an electro-conductive elastic layer on
an electro-conductive support by applying a raw material rubber
composition (material for forming an elastic layer) containing a
resin having an epichlorohydrin chain in the molecular structure
and a specific flavonoid compound having two or more hydroxyl
groups in the molecular structure thereto; and
[0091] (b) a step of forming a surface layer on the elastic
layer.
[0092] Alternatively the manufacturing method may include the
following step between the steps (a) and (b):
[0093] (c) a step of grinding the surface of the elastic layer.
[0094] Each step is described in detail in the following.
[0095] <Elastic Layer Forming Step: Step a>
[0096] Firstly, a resin having an epichlorohydrin chain in the
molecular structure, a specific flavonoid compound having two or
more hydroxyl groups in the molecular structure, and other various
additives as needed are, for example, kneaded with a kneader so as
to produce a raw material rubber composition for forming an elastic
layer. Examples of the kneader include a ribbon blender, a Nauta
mixer, a Henschel mixer, a super mixer, a Bambury mixer, and a
pressure kneader.
[0097] Subsequently, the raw material rubber composition is applied
onto the electro-conductive support so as to form an
electro-conductive elastic layer. More specifically, the following
method may be employed. For example, using an extrusion forming
device having a cross head, a raw material rubber composition is
coaxially applied in a cylindrical shape onto an electro-conductive
support as central shaft coated with an adhesive, and the
electro-conductive support and the material for an elastic layer
are integrally extruded to form an elastic roller. The cross head
is a device commonly used for covering electrical cables and wires,
being attached for use to a rubber discharge part of the cylinder
of an extruder.
[0098] In an alternative method, a rubber tube made of the raw
material rubber composition is formed, to which an
electro-conductive support coated with an adhesive is inserted in
the tube to be bonded. In another alternative method, an
electro-conductive support coated with an adhesive is covered with
an unvulcanized rubber sheet made of the raw material rubber
composition so as to be vulcanized in a mold. As described above,
the heating operation (vulcanizing operation) may be performed
during formation of an elastic layer, according to the material for
use in the raw material rubber composition.
[0099] The thickness of the elastic layer can be 0.3 mm or more and
9.0 mm or less in the view point of the contact stability with a
photosensitive member.
[0100] <Grinding Step: Step c>
[0101] Subsequently, the surface of the produced elastic layer may
be polished on an as needed basis. As a grinding device, a
cylindrical grinding machine for forming a predetermined outer
diameter may be used. Examples of the cylindrical grinding machine
include a traverse-type NC cylindrical grinding machine and a
plunge-cut type NC cylindrical grinding machine. A plunge-cut type
NC cylindrical grinding machine is preferred, capable of reducing
the processing time through use of a wider grinding stone compared
to a traverse-type machine, with a smaller change in diameter of
the grinding stone.
[0102] <Surface Layer Forming Step: Step b>
[0103] Subsequently, for example, a coating liquid of a raw
material (material for forming a surface layer) is applied onto the
produced elastic layer so as to form a surface layer. Examples of
the coating method include a vertical ring coating method, a dip
coating method, an immersion coating method, a spray coating
method, a roll coating method, a curtain coating method, and a
gravure printing method. Among them, a vertical ring coating method
and a dip coating method are most commonly used.
[0104] The thickness of the surface layer is preferably 0.1 .mu.m
or more and 100 .mu.m or less, more preferably 1 .mu.m or more and
30 .mu.m or less.
[0105] <<Physical Properties of Charging Member and
Measurement Methods Thereof>>
[0106] The electric resistance, surface roughness, hardness and tan
.delta. of the charging member of the present invention are not
particularly limited, but can be within the ranges specified
below.
[0107] The electric resistance of a charging member (more
specifically, the electric resistance of the part composed of an
elastic layer and a surface layer) can be 1.0.times.10.sup.4.OMEGA.
or more and 9.9.times.10.sup.7.OMEGA. or less. The electric
resistance of the charging member may be measured with a
measurement device as shown in FIG. 3. More specifically the
measurement is performed by applying a load of 300 g to each of
both ends of the electro-conductive support such that an aluminum
drum 8 comes in contact with the charging member (a charging roller
7), and applying a voltage of 200 V thereto.
[0108] The surface roughness of the charging member is represented
by Rz measured by a contact surface roughness meter. The Rz can be
0.1 .mu.m or more and 50 .mu.m or less.
[0109] The hardness of the charging member (more specifically, the
hardness of the part composed of an elastic layer and a surface
layer) measured with an Asker C hardness meter can be 20 or more
and 80 or less.
[0110] The tan .delta. of the charging member (more specifically,
the tan .delta. of an elastic layer including the surface layer
part) may be obtained by measuring a partially cutout sample taken
from the charging member with a viscoelasticity measurement device
(e.g. a viscoelasticity spectrometer, trade name: EXSTAR 6000DMS,
made by Eko instruments). More specifically, a charging roller is
partially cut out to form a mini roller 16 as shown in FIG. 6.
Subsequently, a shaft bearing 17 is prepared, on which the mini
roller 16 is placed. Subsequently, a sensor 18 of the
viscoelasticity measurement device comes in contact with the rubber
face (surface) of the mini roller 16, for the measurement of the
storage elastic modulus E' and the loss elastic modulus E'' of the
charging roller in a compression mode, so that the tan .delta. can
be calculated.
[0111] The tan .delta. of the charging member can be 0.10 or more
and 0.40 or less. With a tan .delta. of 0.10 or more, the banding
image may be easily inhibited. With a tan .delta. of 0.40 or less,
the occurrence of a banding image may be suppressed, the C-set
image is inhibited, and furthermore a stable charging state may be
easily achieved.
[0112] <Electrophotographic Apparatus>
[0113] The electrophotographic image forming apparatus
(electrophotographic apparatus) may include an electrophotographic
photosensitive member, a charging device which charges the
electrophotographic photosensitive member, a latent image forming
device which performs exposure, a developing device for developing
a toner image, a transferring device for transferring to a transfer
material, a cleaning device for collecting transfer toner on a
photosensitive member, and a fixing device for fixing a toner
image. A schematic diagram of the electrophotographic apparatus in
an embodiment is shown in FIG. 4.
[0114] In the electrophotographic apparatus, a photosensitive
member 9 is a rotary drum type, having a photosensitive layer on an
electro-conductive substrate. The photosensitive member 9 is
rotary-driven in the arrow direction at a predetermined
circumferential velocity (process speed).
[0115] The charging device includes a contact type charging roller
7 to be arranged in contact with the photosensitive member 9 with a
predetermined pressing force. The charging roller 7 is
rotary-driven, following the rotation of the photosensitive member
9. The photosensitive member 9 is chargeable to a predetermined
potential by applying a predetermined DC voltage to the charging
roller 7 from a power supply for charging. A charging member of the
present invention may be used as the charging roller.
[0116] As the latent image forming device 10 for forming an
electrostatic latent image on the photosensitive member 9, for
example, an exposure device such as a laser beam scanner is used.
The evenly charged photosensitive member 9 is subject to exposure
corresponding to the image information so as to form the
electrostatic latent image.
[0117] The developing device includes a developing roller 11
arranged adjacent to or in contact with the photosensitive member.
The toner electrostatically treated in the same polarity as the
charged polarity of the photosensitive member 9 develops a visible
toner image from the electrostatic latent image through reversal
development.
[0118] The transferring device includes a contact-type transferring
roller 12. The toner image is transferred from the photosensitive
member 9 to a transfer material 13 such as plain paper. The
transfer material 13 is conveyed by a paper supply system (not
shown in drawing) having a conveying member.
[0119] The cleaning device including a blade-type cleaning member
14 and a collection container mechanically scrapes off the toner
remaining after transferring on the photosensitive member for
collection after transferring. In the case of using a simultaneous
development and cleaning method in which the toner remaining after
transferring is collected by a developing device, the cleaning
device may be omitted.
[0120] The fixing device 15 including a heated roll and the like
fixes a transferred toner image on the transfer material 13, which
is discharged outside the machine.
[0121] The electrophotographic apparatus of the present invention
may also include, for example, the following electrophotographic
process cartridge, an exposure device, and a developing device.
[0122] <Electrophotographic Process Cartridge>
[0123] The electrophotographic apparatus of the present invention
may also use an electrophotographic process cartridge of the
present invention which integrates (integrally supports) the
charging member and at least one selected from the group consisting
of a photosensitive member, a developing device (developing unit),
a transferring device (transferring unit), and a cleaning device
(cleaning unit), being designed to be detachably mountable to the
electrophotographic apparatus. The process cartridge in an
embodiment is shown in FIG. 5. In the process cartridge, the
charging member (charging roller 7) is at least integrated with a
member to be charged (photosensitive member 9) and detachably
mountable to a main body of the electrophotographic apparatus. As
the charging member, the charging member of the present invention
is used.
EXAMPLES
[0124] The following specific examples further illustrate the
present invention in details, but the scope of the present
invention is not limited thereto.
Manufacturing Example A
Manufacturing of Fine Particles 1 (Conductive Fine Particles))
[0125] To 7.0 kg of silica particles (volume average particle
diameter: 12.5 nm; volume resistivity: 1.8.times.10.sup.12
.OMEGA.cm), 140 g of methyl hydrogen polysiloxane was added with an
edge runner operating, so that mixing/stirring was performed for 30
minutes with a line load of 588 N/cm (60 kg/cm). On this occasion,
the stirring rate was 22 rpm. Carbon black particles (volume
average particle diameter: 28 nm; volume resistivity:
1.2.times.10.sup.2 .OMEGA.cm) with an amount of 7.0 kg was added
thereto for a time period of 10 minutes with an edge runner
operating, and mixing/stirring was further performed for 60 minutes
with a line load of 588 N/cm (60 kg/cm). As described above, the
carbon black was attached to the surface of silica particles coated
with methyl hydrogen polysiloxane, which was then dried at
80.degree. C. for 60 minutes with a drying machine. Consequently,
fine particles 1 were manufactured.
[0126] On this occasion, the stirring rate was 22 rpm. The produced
fine particles 1 had a volume average particle diameter of 15 nm
and a volume resistivity of 2.3.times.10.sup.2 .OMEGA.cm.
Manufacturing Example B
Manufacturing of Fine Particles 2 (Metal Oxide Fine Particles))
[0127] Needle-shaped rutile type titanium oxide particles (volume
average particle diameter: 15 nm; aspect ratio
(vertical:horizontal)=3:1; volume resistivity: 2.3.times.10.sup.10
.OMEGA.cm) in an amount of 1,000 g was blended with 110 g of
isobutyl trimethoxysilane as finishing agent and 3,000 g of toluene
as solvent so as to prepare a slurry. The slurry was agitated with
a stirrer for 30 minutes and then supplied to a visco mill filled
with glass beads (trade name: "GB200M", made by Potters-Ballotini
Co., Ltd.) up to 80% of the effective capacity for wet crushing at
a temperature of 35.+-.5.degree. C. Toluene was removed from the
slurry produced by the wet crushing by distillation under reduced
pressure (bath temperature: 110.degree. C.; product temperature: 30
to 60.degree. C.; pressure reduction degree: approximately 100 Torr
(approximately 13.3 kPa)) with a kneader, and the finishing agent
was baked at 120.degree. C. for 2 hours. The baked particles were
cooled down to room temperature (25.degree. C.), and then crushed
into fine particles 2 with a pin mill. The produced fine particles
2 had a volume average particle diameter of 16 nm and a volume
resistivity of 5.6.times.10.sup.10 .OMEGA.cm.
Example 1
Manufacturing of Charging Roller 1
[0128] To a stainless steel rod having a diameter of 6 mm and a
length of 252 mm was coated with a thermosetting adhesive (trade
name: METALOC U-20, made by Toyokagaku Kenkyusho Co., Ltd.), which
was then left standing in a hot-air oven at 200.degree. C. for 30
minutes. An electro-conductive support was thus obtained.
[0129] In manufacturing a compound for the elastic layer, the
materials shown in the following Table 1 were kneaded for 15
minutes with a closed type mixer which is adjusted at 50.degree. C.
for preparation of a rubber compound A.
TABLE-US-00001 TABLE 1 Parts by Material for rubber compound A mass
Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer 100
(EP:EO:AGE = 37:55:7.5) Tetrabutyl ammonium perchlorate 3
Epicatechin (compound represented by formula (5)) 15 Zinc stearate
1 (trade name: SZ-2000, made by Sakai Chemical Industry Co., Ltd.)
Zinc oxide 5 (trade name: FLOWERS OF ZINC, 2 grade, made by Sakai
Chemical Industry Co., Ltd.) Calcium carbonate 50 (trade name:
NANOX #30, made by Maruo Calcium Co., Ltd.) Polyadipate 10 (trade
name: POLYCIZER P-202, made by DIC Corporation) ##STR00009##
[0130] Subsequently, the rubber compound A and the materials shown
in the following Table 2 were kneaded for 15 minutes with a
two-roll mill cooled at 20.degree. C. so as to prepare a rubber
compound B. The parts by mass shown in Table 2 is relative to 100
parts by mass of epichlorohydrin-ethylene oxide-allyl glycidyl
ether copolymer (EP:EO:AGE=37:55:7.5) in the rubber compound A.
TABLE-US-00002 TABLE 2 Material for rubber compound B Parts by mass
Sulfur 1 Di-2-benzothiazolyl disulfide (MBTS) 2 Tetramethylthiuram
monosulfide (TMTM) 0.5
[0131] Subsequently, the electro-conductive support as central
shaft was coated with the rubber compound B in a cylindrical form
with a cross head extruder and heated for vulcanization in a
hot-air oven at 160.degree. C. Consequently, an elastic roller
precursor having an outer diameter of 9 mm was obtained (Step a).
On this occasion, the temperature of the cross head extruder was
set to 80.degree. C. The ends of the elastic layer of the produced
elastic roller precursor were cut off and ground with a plunge-cut
type cylindrical grinding machine. Consequently, an elastic roller
was obtained (Step c). The outer diameter .phi. of the elastic
roller was set to 8.50 mm at the center of the roller, and 8.35 mm
at the position 90 mm away from the center toward the end.
[0132] Subsequently, methyl isobutyl ketone was added to
caprolactone modified acrylic polyol solution (trade name: "Placcel
DC2016", made by Dicel Corporation), so as to prepare 10 mass % of
solid content. To 1,000 parts by mass of the solution (100 parts by
mass of acrylic polyol solid content), the materials shown in the
following Table 3 were added to prepare a mixed solution.
TABLE-US-00003 TABLE 3 Material Parts by mass Fine particles 1
(conductive fine particles) 45 (manufactured in Manufacturing
Example A) Fine particles 2 (metal oxide fine particles) 20
(manufactured in Manufacturing Example B) Fine particles 3 (resin
fine particles) 5 (trade name: ''MBX-8'', made by Sekisui Chemical
Co., Ltd.) Modified dimethyl silicone oil (*1) 0.08 Blocked
isocyanate mixture (*2) 80.14 (*1) trade name: ''SH28PA'', made by
Dow Corning Toray Co., Ltd. (*2) a 7:3 mixture of the respective
butanone oxime block products of hexamethylene diisocyanate (HDI)
and isophorone diisocyanate (IPDI) . The blocked isocyanate mixture
had an isocyanate amount of ''NCO/OH = 1.0''.
[0133] Subsequently, 200 g of the mixed solution and 200 g of glass
beads as a medium ("GB200M", made by Potters-Ballotini Co., Ltd.)
were placed in a glass bottle having a capacity of 450 mL, so as to
be dispersed for 24 hours with a paint shaker. The glass beads were
then removed to produce an electro-conductive resin coating
liquid.
[0134] Using the electro-conductive resin coating liquid, the
produced elastic roller was coated by one-time dipping. The coated
roller was air-dried at room temperature (25.degree. C.) for 30
minutes, and further dried at 80.degree. C. for 1 hour and
160.degree. C. for 1 hour with a hot-air circulation dryer so as to
produce a charging roller 1.
[0135] On this occasion, the dip coating was performed under the
following conditions. The dipping time was 9 seconds. The
pulling-up rate of the dip coat was changed linearly with time from
an initial rate of 20 mm/s to an final rate of 2 mm/s.
Example 2
Manufacturing of Charging Roller 2
[0136] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 10 parts by mass
of epigallocatechin (a compound represented by formula (6)), a
charging roller 2 was obtained by the same method as in Example
1.
##STR00010##
Example 3
Manufacturing of Charging Roller 3
[0137] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 12 parts by mass
of epicatechin gallate (a compound represented by formula (7)), a
charging roller 3 was obtained by the same method as in Example
1.
##STR00011##
Example 4
Manufacturing of Charging Roller 4
[0138] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 15 parts by mass
of epigallocatechin gallate (a compound represented by formula
(8)), a charging roller 4 was obtained by the same method as in
Example 1.
##STR00012##
Example 5
Manufacturing of Charging Roller 5
[0139] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 9 parts by mass
of naringenin (a compound represented by formula (11)), a charging
roller 5 was obtained by the same method as in Example 1.
##STR00013##
Example 6
Manufacturing of Charging Roller 6
[0140] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 14 parts by mass
of hesperetin (a compound represented by formula (12)), a charging
roller 6 was obtained by the same method as in Example 1.
##STR00014##
Example 7
Manufacturing of Charging Roller 7
[0141] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 8 parts by mass
of 3,5,6,7,3',4'-hexahydroxyflavone (a compound represented by
formula (9)), a charging roller 7 was obtained by the same method
as in Example 1.
##STR00015##
Example 8
Manufacturing of Charging Roller 8
[0142] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 16 parts by mass
of 3,5,7,3',4',5'-hexahydroxyflavone (a compound represented by
formula (10)), a charging roller 8 was obtained by the same method
as in Example 1.
##STR00016##
Example 9
Manufacturing of Charging Roller 9
[0143] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 11 parts by mass
of 5,7,4'-trihydroxyflavone (a compound represented by formula
(13)), a charging roller 9 was obtained by the same method as in
Example 1.
##STR00017##
Example 10
Manufacturing of Charging Roller 10
[0144] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 7 parts by mass
of 3,7,3',4'-tetrahydroxyflavone (a compound represented by formula
(14)), a charging roller 10 was obtained by the same method as in
Example 1.
##STR00018##
Example 11
Manufacturing of Charging Roller 11
[0145] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 18 parts by mass
of 5,7,3',4'-tetrahydroxyflavone (a compound represented by formula
(15)), a charging roller 11 was obtained by the same method as in
Example 1.
##STR00019##
Example 12
Manufacturing of Charging Roller 12
[0146] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 14 parts by mass
of 3,5,7,4'-tetrahydroxyflavone (a compound represented by formula
(16)), a charging roller 12 was obtained by the same method as in
Example 1.
##STR00020##
Example 13
Manufacturing of Charging Roller 13
[0147] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 15 parts by mass
of 3,5,7,3',4'-pentahydroxyflavone (a compound represented by
formula (17)), a charging roller 13 was obtained by the same method
as in Example 1.
##STR00021##
Example 14
Manufacturing of Charging Roller 14
[0148] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 8 parts by mass
of 3,5,7,2',4'-pentahydroxyflavone (a compound represented by
formula (18)), a charging roller 14 was obtained by the same method
as in Example 1.
##STR00022##
Example 15
Manufacturing of Charging Roller 15
[0149] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 13 parts by mass
of 7,8-dihydroxyflavone (a compound represented by formula (19)), a
charging roller 15 was obtained by the same method as in Example
1.
##STR00023##
Example 16
Manufacturing of Charging Roller 16
[0150] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 17 parts by mass
of 5,7-dihydroxyflavone (a compound represented by formula (20)), a
charging roller 16 was obtained by the same method as in Example
1.
##STR00024##
Example 17
Manufacturing of Charging Roller 17
[0151] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 19 parts by mass
of 5,7-dihydroxy-4'-methoxyflavone (a compound represented by
formula (21)), a charging roller 17 was obtained by the same method
as in Example 1.
##STR00025##
Example 18
Manufacturing of Charging Roller 18
[0152] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 14 parts by mass
of 4'-methoxy-3,5,7-trihydroxyflavone (a compound represented by
formula (22)), a charging roller 18 was obtained by the same method
as in Example 1.
##STR00026##
Example 19
Manufacturing of Charging Roller 19
[0153] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 10 parts by mass
of 3-methoxy-5,7,3',4'-tetrahydroxyflavone (a compound represented
by formula (23)), a charging roller 19 was obtained by the same
method as in Example 1.
##STR00027##
Example 20
Manufacturing of Charging Roller 20
[0154] The epichlorohydrin-ethylene oxide-allyl glycidyl ether
copolymer (EP:EO:AGE=37:55:7.5) in an amount of 100 parts by mass
for use in manufacturing the rubber compound A was changed to 100
parts by mass of an epichlorohydrin polymer. Furthermore, in
manufacturing the rubber compound A, 20 parts by mass of carbon
black (trade name: 7360SB) was used instead of tetrabutyl ammonium
perchlorate and polyadipate. And in manufacturing the rubber
compound B, 1 part by mass of dicumyl peroxide as replacement of
the materials shown in Table 2 was kneaded with the rubber compound
A. Except for these, a charging roller 20 was obtained by the same
method as in Example 1.
Example 21
Manufacturing of Charging Roller 21
[0155] The epichlorohydrin-ethylene oxide-allyl glycidyl ether
copolymer (EP:EO:AGE=37:55:7.5) in an amount of 100 parts by mass
for use in manufacturing the rubber compound A was changed to 100
parts by mass of an epichlorohydrin-ethylene oxide copolymer
(EP:EO=60:40). Furthermore, in manufacturing the rubber compound B,
1 part by mass of dicumyl peroxide as replacement of the materials
shown in Table 2 was kneaded with the rubber compound A. Except for
these, a charging roller 21 was obtained by the same method as in
Example 1.
Comparative Example 1
Manufacturing of Charging Roller 22
[0156] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 15 parts by mass
of 3-hydroxyflavone (a compound represented by formula (24)), a
charging roller 22 was obtained by the same method as in Example
1.
##STR00028##
Comparative Example 2
Manufacturing of Charging Roller 23
[0157] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 9 parts by mass
of 5-hydroxyflavone (a compound represented by formula (25)), a
charging roller 23 was obtained by the same method as in Example
1.
##STR00029##
Comparative Example 3
Manufacturing of Charging Roller 24
[0158] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 8 parts by mass
of 6-hydroxyflavone (a compound represented by formula (26)), a
charging roller 24 was obtained by the same method as in Example
1.
##STR00030##
Comparative Example 4
Manufacturing of Charging Roller 25
[0159] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 12 parts by mass
of 6-methoxyflavone (a compound represented by formula (27)), a
charging roller 25 was obtained by the same method as in Example
1.
##STR00031##
Comparative Example 5
Manufacturing of Charging Roller 26
[0160] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 13 parts by mass
of flavone (a compound represented by formula (28)), a charging
roller 26 was obtained by the same method as in Example 1.
##STR00032##
Comparative Example 6
Manufacturing of Charging Roller 27
[0161] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 15 parts by mass
of flavan (a compound represented by formula (29)), a charging
roller 27 was obtained by the same method as in Example 1.
##STR00033##
Comparative Example 7
Manufacturing of Charging Roller 28
[0162] Except that 15 parts by mass of epicatechin for use in
manufacturing the rubber compound A was changed to 10 parts by mass
of 5-hydroxyflavan (a compound represented by formula (30)), a
charging roller 28 was obtained by the same method as in Example
1.
##STR00034##
[0163] <Evaluation Method>
[0164] (Evaluation of Banding Image)
[0165] The produced charging roller assembled into an
electrophotographic apparatus was subject to a durability test
under a low-temperature and low-humidity environment (15.degree.
C./10% RH (relative humidity)). For use as the electrophotographic
apparatus, a color laser jet printer made by Canon (trade name:
SATERA LBP 5400) was modified to have a recording medium output
speed of 200 mm/sec (A4 vertical output). The image resolution was
600 dpi, and the output DC voltage of primary charging was -1,100
V. As the electrophotographic process cartridge, the
electrophotographic process cartridge for the printer was used. A
half tone image was outputted for the evaluation of the unevenness
of streak-like image existing on the halftone image. As the image
evaluation, after 10 sheets of paper were initially fed through, a
banding image was evaluated using the image of the 10th sheet
according to the following criteria:
[0166] Rank 1: no occurrence of streak-like image;
[0167] Rank 2: occurrence of only a slightly streak-like image;
and
[0168] Rank 3: highly visible streak-like image with reduced image
quality.
[0169] <Measurement of Tan .delta. of Charging Member (Tan
.delta. of Elastic Layer Including Surface Layer Part)>
[0170] The tan .delta. of the produced charging roller was measured
with a viscoelasticity measurement device (viscoelasticity
spectrometer, trade name: EXSTAR 6000DMS, made by Eko instruments).
More specifically, the charging roller was partially cut out to
form a mini roller for the measurement, as shown in FIG. 6. The
measurement conditions were set to a compression mode, a frequency
of 100 Hz, and a dynamic strain of 0.2%.
[0171] For each of the produced charging rollers in Examples 1 to
21 and Comparative Examples 1 to 7, the evaluation of the banding
image and the measurement of tan 8 of the charging roller were
performed as described above.
[0172] The evaluation results are shown in Table 4. In Table 4,
"phr" means the addition amount (parts by mass) relative to 100
parts by mass of a resin having an epichlorohydrin chain in the
molecular structure.
TABLE-US-00004 TABLE 4 Flavonoid compound Charging Addition Image
Example roller Material name amount (phr) rank tan .delta. 1 1
Epicatechin 15 1 0.25 2 2 Epigallocatechin 10 1 0.24 3 3
Epicatechin gallate 12 1 0.23 4 4 Epigallocatechin gallate 15 1
0.24 5 5 Naringenin 9 1 0.25 6 6 Hesperetin 14 1 0.23 7 7
3,5,6,7,3',4'-Hexahydroxyflavone 8 1 0.26 8 8
3,5,7,3',4',5'-Hexahydroxyflavone 16 1 0.21 9 9
5,7,4'-Trihydroxyflavone 11 1 0.20 10 10
3,7,3',4'-Tetrahydroxyflavone 7 1 0.19 11 11
5,7,3',4'-Tetrahydroxyflavone 18 1 0.18 12 12
3,5,7,4'-Tetrahydroxyflavone 14 1 0.17 13 13
3,5,7,3',4'-Pentahydroxyflavone 15 1 0.18 14 14
3,5,7,2',4'-Pentahydroxyflavone 8 1 0.15 15 15 7,8-Dihydroxyflavone
13 2 0.14 16 16 5,7-Dihydroxyflavone 17 2 0.13 17 17
5,7-Dihydroxy-4'-methoxyflavone 19 2 0.12 18 18 4'-Methoxy-3,5,7-
14 2 0.13 trihydroxyflavone 19 19 3-Methoxy-5,7,3',4'- 10 2 0.11
tetrahydroxyflavone 20 20 Epicatechin 15 2 0.14 21 21 Epicatechin
15 2 0.13 Flavonoid compound Comparative Charging Addition Image
Example roller Material name amount (phr) rank tan .delta. 1 22
3-Hydroxyflavone 15 3 0.08 2 23 5-Hydroxyflavone 9 3 0.07 3 24
6-Hydroxyflavone 8 3 0.09 4 25 6-Methoxyflavone 12 3 0.07 5 26
Flavone 13 3 0.06 6 27 Flavane 15 3 0.07 7 28 5-Hydroxyflavane 10 3
0.08
[0173] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0174] This application claims a priority from Japanese Patent
Application No. 2012-285241 filed on Dec. 27, 2012, of which
content is incorporated into a part of this application by
reference.
REFERENCE SIGNS LIST
[0175] 1 CONDUCTIVE SUPPORT [0176] 2 CONDUCTIVE ELASTIC LAYER
[0177] 3 SURFACE LAYER [0178] 4 RESIN HAVING EPICHLOROHYDRIN CHAIN
IN MOLECULAR STRUCTURE [0179] 5 SPECIFIC FLAVONOID COMPOUND HAVING
TWO OR MORE HYDROXYL GROUPS IN MOLECULAR STRUCTURE [0180] 6
HYDROGEN BOND [0181] 7 CHARGING ROLLER [0182] 8 ALUMINUM DRUM
[0183] 9 PHOTOSENSITIVE MEMBER LATENT IMAGE FORMING DEVICE [0184]
11 DEVELOPING ROLLER [0185] 12 TRANSFERRING ROLLER [0186] 13
TRANSFER MATERIAL [0187] 14 CLEANING MEMBER FIXING DEVICE [0188] 16
MINI ROLLER [0189] 17 SHAFT BEARING [0190] 18 SENSOR OF
VISCOELASTICITY MEASUREMENT DEVICE
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