U.S. patent application number 14/946768 was filed with the patent office on 2016-06-02 for member for electrophotography, process cartridge and image forming apparatus.
The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Hiroki Masu, Satoru Nishioka, Noriko Suzumura, Kazuhiro Yamauchi, Kenichi Yamauchi.
Application Number | 20160154336 14/946768 |
Document ID | / |
Family ID | 56079153 |
Filed Date | 2016-06-02 |
United States Patent
Application |
20160154336 |
Kind Code |
A1 |
Masu; Hiroki ; et
al. |
June 2, 2016 |
MEMBER FOR ELECTROPHOTOGRAPHY, PROCESS CARTRIDGE AND IMAGE FORMING
APPARATUS
Abstract
It is intended to provide a member for electrophotography that
can inhibit the adhesion of dirt to the outer surface. The member
for electrophotography has a substrate, an elastic layer on the
substrate, and a surface layer on the elastic layer. The surface
layer contains a binder resin and first particles, the surface of
the surface layer has first convexes derived from the first
particles, the first particles resulting in the first convex has an
average inter-particle surface distance of 50 nm or less, the first
particles have a number-average particle diameter of 200 nm or more
and 1000 nm or less, and the surface of the surface layer has a
universal hardness of 1.0 N/mm.sup.2 or more and 7.0 N/mm.sup.2 or
less.
Inventors: |
Masu; Hiroki; (Tokyo,
JP) ; Yamauchi; Kazuhiro; (Suntou-gun, JP) ;
Nishioka; Satoru; (Suntou-gun, JP) ; Yamauchi;
Kenichi; (Mishima-shi, JP) ; Suzumura; Noriko;
(Mishima-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Family ID: |
56079153 |
Appl. No.: |
14/946768 |
Filed: |
November 19, 2015 |
Current U.S.
Class: |
399/176 ;
428/143; 428/147 |
Current CPC
Class: |
B32B 2264/0292 20130101;
B32B 2255/10 20130101; B32B 2559/00 20130101; B32B 15/18 20130101;
B32B 2274/00 20130101; B32B 1/08 20130101; B32B 15/082 20130101;
B32B 15/06 20130101; B32B 25/14 20130101; B32B 2307/51 20130101;
B32B 15/20 20130101; B32B 2307/202 20130101; B32B 2255/205
20130101; B32B 2264/0207 20130101; G11B 7/00 20130101; B32B 1/00
20130101; B32B 2307/546 20130101; B32B 2255/06 20130101; B32B
27/302 20130101; B32B 2264/10 20130101; G03G 15/0233 20130101; B32B
2307/20 20130101; G03G 8/00 20130101; B32B 2307/536 20130101; B32B
2307/538 20130101; B32B 2255/26 20130101 |
International
Class: |
G03G 15/02 20060101
G03G015/02; B32B 25/14 20060101 B32B025/14; B32B 15/18 20060101
B32B015/18; B32B 1/08 20060101 B32B001/08; B32B 15/06 20060101
B32B015/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2014 |
JP |
2014-241883 |
Claims
1. A member for electrophotography comprising: a substrate, an
elastic layer on the substrate, and a surface layer on the elastic
layer, wherein, the surface layer comprises a binder resin and
first particles, the surface of the surface layer has first
convexes derived from the first particles, the first particles
resulting in the first convex have an average inter-particle
surface distance of 50 nm or less, the first particles have a
number-average particle diameter of 200 nm or more and 1000 nm or
less, and the surface of the surface layer has a universal hardness
of 1.0 N/mm.sup.2 or more and 7.0 N/mm.sup.2 or less.
2. The member for electrophotography according to claim 1, wherein
the first particles are rubber particles.
3. The member for electrophotography according to claim 1, wherein
the surface layer has a volume resistivity of 1.0.times.10.sup.10
.OMEGA.cm or more and 1.0.times.10.sup.16 .OMEGA.cm or less.
4. The member for electrophotography according to claim 1, wherein
the surface layer further comprises a second particle, the surface
of the surface layer has a second convex derived from the second
particle, and the second particle has a number-average particle
diameter of 3 .mu.m or more and 30 .mu.m or less.
5. The member for electrophotography according to claim 4, wherein
the second convex of the surface layer has a Martens hardness of
1.0 N/mm.sup.2 or more and 10.0 N/mm.sup.2 or less.
6. The member for electrophotography according to claim 4, wherein
the second particle is a urethane resin particle.
7. A process cartridge which is configured to be detachably
attachable to the body of an image forming apparatus, the process
cartridge comprising an image bearing member and a charging member
disposed in contact with the image bearing member, wherein the
charging member comprises a substrate, an elastic layer on the
substrate, and a surface layer on the elastic layer, the surface
layer comprises a binder resin and first particles, the surface of
the surface layer has first convexes derived from the first
particles, the first particles resulting in the first convex have
an average inter-particle surface distance of 50 nm or less, the
first particles have a number-average particle diameter of 200 nm
or more and 1000 nm or less, and the surface of the surface layer
has a universal hardness of 1.0 N/mm.sup.2 or more and 7.0
N/mm.sup.2 or less.
8. An image forming apparatus comprising an image bearing member, a
charging apparatus which charges the image bearing member, a
developing apparatus which develops an electrostatic latent image
formed on the image bearing member by use of a developer, and a
transfer member which transfers the developer supported by the
image bearing member to a transfer medium, wherein the charging
apparatus comprises a charging member, the charging member
comprises a substrate, an elastic layer on the substrate, and a
surface layer on the elastic layer, the surface layer comprises a
binder resin and first particles, the surface of the surface layer
has first convexes derived from the first particles, the first
particles resulting in the first convex have an average
inter-particle surface distance of 50 nm or less, the first
particles have a number-average particle diameter of 200 nm or more
and 1000 nm or less, and the surface of the surface layer has a
universal hardness of 1.0 N/mm.sup.2 or more and 7.0 N/mm.sup.2 or
less.
9. The image forming apparatus according to claim 8, wherein the
charging member is moved with a difference in speed from the image
bearing member.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a member for
electrophotography, a process cartridge and an image forming
apparatus.
[0003] 2. Description of the Related Art
[0004] In image forming apparatuses based on an electrophotographic
method, a member for electrophotography is employed in various
uses, for example, a charging member, a developing member and a
transfer member. In the case of employing the member for
electrophotography in these uses for a long period, powders such as
external additives or toner remaining on an image bearing member
adhere as dirty substances to the surface of the member for
electrophotography. For example, as for a charging member, when
such dirty substances adhere to the surface of the charging member,
this area with the dirty substances adhering thereto partially has
higher resistance resulting in poor charging. As a result, image
density unevenness may occur due to the dirt.
[0005] In recent years, higher image quality, higher speed and
higher durability have been demanded for image forming apparatuses.
In response to these requirements, there is a tendency to reduce
the particle diameter of toner and use various types of external
additives. As a result, the dirty substances are deposited in
larger amounts on the charging member.
[0006] A cleaner-less system (toner recycle system) has been
proposed from the viewpoint of simplifying image forming
apparatuses or eliminating wastes. This method does without a
cleaner, which is a cleaning unit on an image bearing member, after
a transfer step. The method removes residual toner on the image
bearing member after transfer, from the image bearing member by
"cleaning simultaneous with development" using a developing
apparatus and recovers the toner into the developing apparatus for
recycling. The cleaning simultaneous with development is a method
which recovers residual toner remaining on the image bearing member
after transfer, by use of a fog removing bias (fog removing
potential difference Vback which is a potential difference between
direct-current voltage applied to the developing apparatus and the
surface potential of the image bearing member) during development
in the subsequent step or later. In the case of applying a charging
member of a contact charging method to the cleaner-less system, the
amount of dirty substances, particularly, toner, remaining on the
image bearing member is increased as compared with a case having a
cleaner. Thus, the adhesion of dirty substances to the charging
member is a more significant problem.
[0007] As a unit for reducing the adhesion of dirty substances such
as external additives or toner, Japanese Patent No. 5455336 and
Japanese Patent Application Laid-Open No. 2008-083404 disclose a
charging member for which the amount of dirty substances adhering
is reduced by the control of surface roughness through a particle
contained in a surface layer.
[0008] The present invention is directed to providing a member for
electrophotography that can more highly inhibit the adhesion of
dirty substances to the surface.
[0009] The present invention is also directed to providing a
process cartridge and an image forming apparatus that can form a
high-quality image.
SUMMARY OF THE INVENTION
[0010] According to one aspect of the present invention, there is
provided a member for electrophotography having a substrate, an
elastic layer on the substrate, and a surface layer on the elastic
layer, wherein the surface layer contains a binder resin and first
particles, the surface of the surface layer has first convexes
derived from the first particles, the first particles resulting in
the first convex have an average inter-particle surface distance of
50 nm or less, the first particles have a number-average particle
diameter of 200 nm or more and 1000 nm or less, and the surface of
the surface layer has a universal hardness of 1.0 N/mm.sup.2 or
more and 7.0 N/mm.sup.2 or less.
[0011] According to an alternative aspect of the present invention,
there is provided a process cartridge which is configured to be
detachably attachable to the body of an image forming apparatus, in
which the process cartridge includes an image bearing member and a
charging member disposed in contact with the image bearing member,
the charging member being the member for electrophotography.
[0012] According to a further alternative aspect of the present
invention, there is provided an image forming apparatus having an
image bearing member, a charging apparatus which charges the image
bearing member, a developing apparatus which develops an
electrostatic latent image formed on the image bearing member by
use of a developer, and a transfer member which transfers the
developer supported by the image bearing member to a transfer
medium, in which the charging apparatus has a charging member which
is the member for electrophotography.
[0013] 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
[0014] FIG. 1 is a cross-sectional view illustrating one example of
the image forming apparatus according to the present invention.
[0015] FIG. 2 is a scanning electron microscope (SEM) photograph of
one example of a surface layer in the member for electrophotography
according to the present invention.
[0016] FIG. 3 is a cross-sectional view of the member for
electrophotography according to the present invention in an
embodiment having a roller shape.
[0017] FIG. 4 is a schematic cross-sectional view in proximity to
the surface of one example of the member for electrophotography
according to the present invention.
[0018] FIG. 5 is a diagram for illustrating a halftone image used
for evaluation.
DESCRIPTION OF THE EMBODIMENTS
[0019] Preferred embodiments of the present invention will now be
described in detail in accordance with the accompanying
drawings.
[0020] Hereinafter, the present invention will be described in
detail by taking a charging member having a roller shape
(hereinafter, also referred to as a "charging roller") as a typical
example of a use of the member for electrophotography according to
the present invention. However, the present invention is not
intended to be limited by this embodiment. The member for
electrophotography according to the present invention can also be
used as any of other members or as a charging member having any of
other shapes.
[0021] According to the studies of the present inventors, use of a
charging member whose surface roughness is controlled through a
particle-derived convex disposed on the surface, as disclosed in
Japanese Patent No. 5455336 and Japanese Patent Application
Laid-Open No. 2008-083404, has been confirmed to have an effect of
reducing the amount of dirty substances adhering by decreasing the
friction coefficient of the surface layer. However, the inhibitory
effect on the adhesion of dirty substances has been reduced in some
cases with increase in the number of output images.
[0022] The present inventors have observed the surface of this
charging member having a reduced inhibitory effect on the adhesion
of dirty substances and consequently confirmed that dirty
substances are deposited on a valley part between particle-derived
convexes.
[0023] Particularly, in the case of using such a charging member in
an electrophotographic apparatus based on a cleaner-less system,
dirty substances have been particularly prominently deposited on
the valley part because residual toner on an image bearing member
is contacted with the charging member.
[0024] The present invention has been made in light of such
conventional configuration and relates to a member for
electrophotography capable of further inhibiting the adhesion of
dirt to the outer surface.
[0025] FIG. 3 illustrates a cross section in a direction orthogonal
to the axial direction of a charging roller according to one
embodiment of the member for electrophotography of the present
invention. The charging roller 300 illustrated in FIG. 3 has a
substrate 301, an elastic layer 303 disposed on the outer
peripheral surface of the substrate 301, and a surface layer 305
disposed on the outer peripheral surface of the elastic layer 303.
The surface of the surface layer 305 on an opposite side of its
surface facing the elastic layer 303 constitutes the outer surface
of the charging roller 300. In the present invention, the "surface"
of the surface layer refers to the surface constituting the outer
surface of the member for electrophotography, unless otherwise
specified.
[0026] <Surface Layer>
[0027] FIG. 4 is a schematic cross-sectional view in proximity to
the surface of the surface layer 305 in the member 300 for
electrophotography according to one embodiment of the present
invention. In FIG. 4, the surface layer 305 contains a binder resin
307 and first particles 309. The first particles 309 result in
first convexes 311 on the surface of the surface layer 305, i.e.,
the outer surface of the member 300 for electrophotography.
[0028] The first particles 309 viewed from a position opposed to
the member 300 for electrophotography have inter-particle surface
distances on average (hereinafter, referred to as an average
inter-particle surface distance) of 50 nm or less. Specifically,
the surface of the member 300 for electrophotography viewed from a
position opposed to the member 300 for electrophotography is filled
with the first particles 309 disposed close to each other such that
the first particles 309 have an average inter-particle surface
distance of 50 nm or less.
[0029] FIG. 2 is a scanning electron microscope (SEM) photograph of
the outer surface of the member 300 for electrophotography.
[0030] In the present invention, the state where the outer surface
of the member for electrophotography viewed from a position opposed
to the member for electrophotography is substantially filled with
the first particles is indicated by a parameter which is the
average inter-particle surface distance of the first particles. The
way to determine the average inter-particle surface distance will
be described later in detail.
[0031] The member for electrophotography whose surface is
substantially filled with the first particle resulting in the first
convex on the outer surface effectively inhibits the adhesion of
dirt to a valley part between first convexes in a conventional
member for electrophotography having convexes on the surface. This
is probably because the valley part between a plurality of first
convexes according to the present invention is smaller in size than
the general dirty substances. The average inter-particle surface
distance is particularly preferably 45 nm or less, further
preferably 40 nm or less. The lower limit of the average
inter-particle surface distance is not particularly limited and can
be, for example, 10 nm or more.
[0032] The main dirty substances adhering to the surface of the
charging member subjected to the output of electrophotographic
images over a long period are particularly toner-derived substances
such as deformed toner or pulverized toner. From this, the present
inventors have considered that, particularly, the prevention of
deformation and pulverization of toner is effective for reducing
the adhesion of dirty substances to the surface of the charging
member. For this purpose, the charging member needs to satisfy the
following condition 1.
[0033] <Condition 1> The surface of the surface layer has a
universal hardness of 1.0 N/mm.sup.2 or more and 7.0 N/mm.sup.2 or
less.
[0034] The amount of toner-derived dirty substances is increased
when the charging member has a high hardness. This is probably
because, when the surface of the charging member has a high
hardness, toner (residual toner) passing through the nip between
the charging member and an image bearing member
(electrophotographic photosensitive member) tends to be cracked or
chipped. This phenomenon is more prominent for a cleaner-less
system. However, the surface layer that satisfies the condition 1
inhibits the cracking or chipping of toner by the charging
member.
[0035] The surface of the surface layer has a universal hardness of
1.0 N/mm.sup.2 or more and 7.0 N/mm.sup.2 or less. The universal
hardness is preferably 6.0 N/mm.sup.2 or less, more preferably 5.0
N/mm.sup.2 or less. Since external additives and toner as targeted
dirty substances are of the order of submicron to several microns
in size, it is required to control the hardness of the topmost
surface of the surface layer. The universal hardness can be set to
1.0 N/mm.sup.2 or more to thereby inhibit the occurrence of image
density unevenness derived from the deformation of the charging
member caused by the contact between the charging member and the
image bearing member in a resting state for a long period. Also,
the universal hardness can be set to 7.0 N/mm.sup.2 or less to
thereby inhibit the deformation and cracking of toner so that the
absolute amount of deformed toner and pulverized toner remaining on
the image bearing member can be reduced. Particularly, the
universal hardness can be set to 5.0 N/mm.sup.2 or less to thereby
sufficiently maintain the effect of inhibiting the deformation and
cracking of toner even if the number of formed images is
increased.
[0036] The universal hardness is a physical property value that is
determined by indentation of a indenter into a measurement object
under a load, and is determined according to (Test load)/(Surface
area of the indenter under the test load) (N/mm.sup.2). An indenter
such as a quadrangular pyramid is pressed into an object to be
measured under a predetermined relatively small test load. When the
indenter reaches a predetermined indentation depth, the surface
area contacted with the indenter is determined from the indentation
depth to determine the universal hardness. In the present
invention, the universal hardness of the surface of the surface
layer is a value measured by a method mentioned later.
[0037] <First Particle>
[0038] The presence of the first convex inhibits the physical
adhesion of dirty substance to the outer surface of the member for
electrophotography. As the size of the first particle resulting in
the first convex, their number-average particle diameter is 200 nm
or more and 1000 nm or less such that the interval between the
convexes derived from the first particles is smaller in size than
dirty substances when the first particles reside in the surface
layer so as to have an average inter-particle surface distance of
50 nm or less.
[0039] External additives as dirty substances adhere thereto in an
aggregated form rather than each individually. Therefore, the
number-average particle diameter can be set to 200 nm or more to
thereby form first convex serving as a starting point to inhibit
the physical adhesion of the external additives. If the
number-average particle diameter is larger than 1000 nm, the
physical adhesion of the external additives cannot be inhibited,
though the physical adhesion of toner can be inhibited. The
number-average particle diameter is preferably 900 nm or less, more
preferably 800 nm or less.
[0040] The number-average particle diameter is an arithmetic
average particle diameter that is obtained by taking the image of
an arbitrary region of 3.0 .mu.m square at a magnification of
.times.40000 using a scanning electron microscope (SEM) and
measuring the unidirectional diameters of 30 first particles
randomly selected from the obtained image.
[0041] One important factor for the surface layer to satisfy the
numerical range of the universal hardness related to <condition
1> mentioned above is the first particle.
[0042] Specifically, a flexible particle can be used as the first
particle for adjusting the universal hardness of the surface layer
to 1.0 N/mm.sup.2 or more and 7.0 N/mm.sup.2 or less.
[0043] Specifically, a particle containing a rubber such as a
natural rubber, a vulcanized form of the natural rubber or a
synthetic rubber, and a particle containing a resin can be suitably
used as the first particle.
[0044] Among others, a rubber particle can be used from the
viewpoint of, for example, securing the uniform contact between the
surface layer and the image bearing member and inhibiting the
deformation and cracking of toner.
[0045] The material for the rubber particle is not particularly
limited as long as the material exhibits rubber-like physical
properties at an operating temperature, specifically, has a glass
transition temperature of 0.degree. C. or less. Examples thereof
include silicone rubber, butadiene rubber, styrene-butadiene
rubber, nitrile rubber and acrylic rubber. One type of these rubber
particles may be used, or two or more types thereof may be used in
combination. The rubber particle can have a core-shell structure. A
resin having affinity for a solvent in a coating liquid for use in
the formation of the surface layer can be used as a material
constituting the shell to thereby efficiently move the rubber
particle to the surface side of a coating film during the process
of evaporating the solvent from the coating film formed from the
coating liquid on the elastic layer.
[0046] Examples of such a material constituting the shell include
methyl polymethacrylate, polystyrene and mixtures thereof, and
acrylonitrile. One of these materials may be used, or two or more
thereof may be used in combination.
[0047] Examples of commercially available rubber-containing a
particle that can be suitably used as the first particle include a
butadiene rubber-containing particle "Metablen C-223A", a silicone
rubber-containing particle "Metablen S-2001", and an acrylic
rubber-containing particle "Metablen W-450A" (all are trade names,
manufactured by Mitsubishi Rayon Co., Ltd.), Staphyloid (trade
name, manufactured by Aica Kogyo Co., Ltd. (formerly Ganz Chemical
Co., Ltd.)) and Paraloid (trade name, manufactured by the Dow
Chemical Company (formerly Rohm and Haas Company)). The particle
diameter distribution of a generally available first particle is
generally a normal distribution.
[0048] <Binder Resin>
[0049] A binder resin known in the art can be used as the binder
resin. Examples thereof can include resins and rubbers such as
natural rubbers, vulcanized natural rubbers and synthetic rubbers.
For example, fluorine resin, polyamide resin, acrylic resin,
polyurethane resin, silicone resin, butyral resin,
styrene-ethylene/butylene-olefin copolymer and
olefin-ethylene/butylene-olefin copolymer can be used as the
resins. These binder resins may each be used alone, or two or more
thereof may be used as a mixture. Alternatively, a copolymer may be
used. Among these resins, polyurethane resin can be used from the
viewpoint of controlling the universal hardness of the surface of
the surface layer and the volume resistivity of the surface layer.
The polyurethane resin can be polycarbonate polyurethane, polyester
polyurethane or polyolefin polyurethane from the viewpoint of the
dispersibility or surface convex formation of the first particle
such as a rubber particle mentioned above.
[0050] The binder resin is one important factor for the surface
layer to have the universal hardness related to the condition
1.
[0051] Specifically, for adjusting the universal hardness of the
surface layer to 1.0 N/mm.sup.2 or more and 7.0 N/mm.sup.2 or less,
it is required to use a flexible binder resin.
[0052] Specific examples of the polyurethane resin include
polyurethane resin obtained by reacting polyester polyol (trade
name: P-3010, manufactured by Kuraray Co., Ltd.) with
isocyanate-terminated prepolymer (isocyanate group content: 4.3%)
obtained through the reaction between polymeric MDI (trade name:
Millionate MR200, manufactured by Tosoh Corporation (formerly
Nippon Polyurethane Industry Co., Ltd.)) and polyester polyol
(trade name: P-3010, manufactured by Kuraray Co., Ltd.), as
described in Examples mentioned later.
[0053] Alternative examples thereof include polyurethane resin
obtained by reacting polyester polyol (trade name: P-3010,
manufactured by Kuraray Co., Ltd.) with isocyanate-terminated
prepolymer (isocyanate group content: 4.3%) obtained through the
reaction between polymeric MDI (trade name: Millionate MR200,
manufactured by Tosoh Corporation) and polycarbonate polyol (trade
name: T-5652, manufactured by Asahi Kasei Chemicals Corp.).
[0054] Further alternative examples thereof include polyurethane
resin obtained by reacting castor oil polyol (trade name: URIC-H
1823, manufactured by Itoh Oil Chemicals Co., Ltd.) with
isocyanate-terminated prepolymer (isocyanate group content: 4.3%)
obtained through the reaction between polymeric MDI (trade name:
Millionate MR200, manufactured by Tosoh Corporation) and polyester
polyol (trade name: P-2050, manufactured by Kuraray Co., Ltd.).
[0055] Further alternative examples thereof include polyurethane
resin obtained by reacting polyolefin polyol (trade name: G2000,
manufactured by Nippon Soda Co., Ltd.) with isocyanate-terminated
prepolymer (isocyanate group content: 4.3%) obtained through the
reaction between polymeric MDI (trade name: Millionate MR200,
manufactured by Tosoh Corporation) and polyolefin polyol (trade
name: G2000, manufactured by Nippon Soda Co., Ltd.).
[0056] Further alternative examples thereof include polyurethane
resin obtained by reacting polyether polyol (trade name: Exenol
3020, manufactured by Asahi Glass Co., Ltd.) with
isocyanate-terminated prepolymer (isocyanate group content: 4.3%)
obtained through the reaction between polymeric MDI (trade name:
Millionate MR200, manufactured by Tosoh Corporation) and
polypropylene glycol polyol (trade name: Exenol 1030, manufactured
by Asahi Glass Co., Ltd.).
[0057] As the hardness of the surface layer is decreased, the
surface generally tends to have higher tackiness. Nonetheless, the
member for electrophotography according to the present invention is
substantially free from such increase in tackiness attributed to
the reduced hardness of the surface layer, because the first
particle resulting in the first convex on the outer surface reside
with almost no gaps in proximity to the surface of the surface
layer as described above.
[0058] The surface layer can also satisfy the following condition
2.
[0059] <Condition 2> The surface layer has a volume
resistivity of 1.0.times.10.sup.10 .OMEGA.cm or more and
1.0.times.10.sup.16 .OMEGA.cm or less.
[0060] According to the studies of the present inventors, the
charging member that satisfies the condition 1 has been confirmed
in some cases to cause very small white spots in solid images,
particularly, in an environment of high temperature and high
humidity, for example, a temperature of 30.degree. C. and a
relative humidity of 80%. This is because the direct injection of
electric charge without discharge (hereinafter, also referred to as
"injection charging") occurs upon contact between the charging
member and the image bearing member so that the image bearing
member is charged beyond a predetermined amount of charge.
[0061] Accordingly, the present inventors have conducted studies on
the characteristics of the surface layer for preventing such a
phenomenon even in a high-temperature and high-humidity
environment. As a result, it has been found that the volume
resistivity of the surface layer can be set to 1.0.times.10.sup.10
.OMEGA.cm or more and 1.0.times.10.sup.16 .OMEGA.cm or less to
thereby inhibit image defects caused by injection charging to an
undetectable level.
[0062] In this context, the volume resistivity of the surface layer
can fall within the aforementioned numerical range even in a
high-temperature and high-humidity environment most prone to
causing injection charging.
[0063] The volume resistivity of the surface layer is particularly
preferably 2.0.times.10.sup.10 .OMEGA.cm or more and
1.0.times.10.sup.15 .OMEGA.cm or less, further preferably
3.0.times.10.sup.10 .OMEGA.cm or more and 1.0.times.10.sup.14
.OMEGA.cm or less. The measurement of the volume resistivity of the
surface layer and the evaluation of the amount of injection charge
are carried out by methods mentioned later.
[0064] The surface layer may contain a second particle having a
larger particle diameter than that of the first particle such that
the outer surface of the member for electrophotography has a convex
derived from the second particle.
[0065] Specifically, the surface layer 305 illustrated in FIG. 4
contains a second particle 409 and has a second convex 411 derived
from the second particle. As illustrated in FIG. 4, the second
convex 411 has the first convex 311 on the surface.
[0066] Such configuration can prevent the flexible particle used as
the first particle from increasing the contact area between the
charging member and the image bearing member at the nip, and
inhibit the collapse of the first convex at the nip between the
charging member and the image bearing member. As a result, the
deformation of the first convex can be inhibited in long-term
use.
[0067] In addition, this configuration having the second convex
having the first convex on its surface can stabilize discharge from
the surface of the charging member to the surface of the image
bearing member before and after the nip between the charging member
and the image bearing member and thus contributes to the higher
stabilization of charging performance.
[0068] <Second Particle>
[0069] The number-average particle diameter of the second particle
needs to be larger than that of the first particle. Specifically,
the number-average particle diameter can be 3 .mu.m or more and 30
.mu.m or less. This can easily render the second convex higher than
the first convex. This can also prevent the second convex from
roughening too much the outer surface of the member for
electrophotography. The number-average particle diameter of the
second particle is particularly preferably 5 .mu.m or more and 20
.mu.m or less, further preferably 7 .mu.m or more and 15 .mu.m or
less. The number-average particle diameter of the second particle
is measured by using FIB-SEM (Focused Ion-Beam Scanning Electron
Microscope). The concrete measuring method is shown below.
[0070] A blade of cutter is contacted against a surface layer, and
a section is cut out so that a length in an x-axis direction (a
longitude direction of a roller) and a y-axis direction (a
tangential direction of a circular section in a cross section of
the roller perpendicular to the x-axis) is 5 mm respectively. The
cut out section is observed from a z-direction (a diametrical
direction in a cross section of the roller perpendicular to the
x-axis) through the use of the FIB-SEM apparatus under the
conditions that acceleration voltage is 10 kV and magnification is
1,000 times. Then, a total of 100 pieces of cross-sectional images
from the surface to a depth of 20 .mu.m at 200 nm intervals in the
z-direction is taken with an ion beam current of 20 nA using
gallium ion beam. With respect to each of second particles observed
in a cross-sectional image, the maximum diameter of the particle is
defined as a diameter of the particle, and the average value of
diameters of 20 particles is defined as the average particle
diameter.
[0071] In order to set the universal hardness of the surface layer
within the range related to the condition 1, high-hardness particle
such as a metal particle should not be used as the second particle.
Specifically, a particle of a resin such as acrylic resin,
polycarbonate resin, styrene resin, urethane resin, fluorine resin
or silicone resin can be used as the second particle. One type of
these second particles may be used, or two or more types thereof
may be used in combination. A urethane resin particle excellent in
flexibility is particularly preferred as the second particle.
[0072] When the surface layer contains the second particle, the
second convex derived from the second particle in the surface layer
can have a Martens hardness of 1.0 N/mm.sup.2 or more and 10.0
N/mm.sup.2 or less. The Martens hardness is more preferably 8.0
N/mm.sup.2 or less, further preferably 5.0 N/mm.sup.2 or less. The
Martens hardness can be set to 1.0 N/mm.sup.2 or more to thereby
inhibit the occurrence of image density unevenness derived from the
deformation of the charging member caused by the contact between
the charging member and the image bearing member in a resting state
for a long period. Also, the Martens hardness can be set to 10.0
N/mm.sup.2 or less to thereby inhibit the deformation of toner by
the second convex. The Martens hardness is a value measured by a
method mentioned later.
[0073] <Electro-Conductive Agent>
[0074] The surface layer can contain an electro-conductive agent
and thereby have electro-conductivity. However, the volume
resistivity of the surface layer can be adjusted within the range
related to the condition 2.
[0075] Examples of the electro-conductive agent include ion
conductive agents and an electro-conductive particle. An
electro-conductive particle can be used from the viewpoint of being
inexpensive and having few environmental variations in resistance.
Examples of the electro-conductive particle can include carbon
black, electro-conductive particle of metal oxides such as titanium
oxide, tin oxide and zinc oxide, and an electro-conductive particle
of metals such as aluminum, iron, copper and silver. These
electro-conductive particles can be used alone or in combination of
two or more thereof. A composite particle having a silica particle
covered with an electro-conductive particle can also be used as the
electro-conductive particle. The electro-conductive particle can be
carbon black. Carbon black has low specific gravity and high
conductivity and can therefore secure sufficient conductivity for
the surface layer by addition in a small amount to the binder
resin. Also, carbon black can keep the hardness of the surface
layer low.
[0076] <Other Additives>
[0077] The surface layer can contain other additives in addition to
the aforementioned components. The surface layer can contain a
silicone additive as an additional additive from the viewpoint of
improving the surface resistance of the surface layer. The surface
layer may be subjected to, for example, modification, introduction
of a functional group or a molecular chain, coating or surface
treatment with a releasing agent or the like without impairing the
effects of the present invention.
[0078] The surface layer can be formed by a coating method such as
electrostatic spray coating, dipping or ring coating.
Alternatively, the surface layer may be formed by adhesion of or
covering with a surface layer having a sheet or tube shape formed
in advance with a predetermined film thickness. A method of curing
and molding materials into a predetermined shape in a mold may also
be used. Among others, the surface layer can be formed by the
application of a coating liquid containing materials for the
surface layer by a coating method, followed by drying.
[0079] The physical properties such as dynamic friction coefficient
and surface free energy of the surface layer can be adjusted by the
surface treatment of the surface layer. Specific examples thereof
include a method for irradiating the surface layer with active
energy beams. Examples of the active energy beams include
ultraviolet rays, infrared rays and electron beams.
[0080] <Thickness of Surface Layer>
[0081] 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
50 .mu.m or less. The thickness of the surface layer is a value
measured by a method mentioned later.
[0082] <Method for Producing Surface Layer>
[0083] For the production of the surface layer, for example, a
coating film is formed on the surface of the elastic layer from a
coating liquid containing the binder resin or a starting material
for the binder resin and the first particle dissolved or dispersed
or dissolved and dispersed in a solvent. Then, the formed coating
film is dried so that the surface layer is formed on the elastic
layer.
[0084] In this context, methyl ethyl ketone can be used as the
solvent, and a core-shell structure rubber particle ("Metablen
C-223A", trade name, manufactured by Mitsubishi Rayon Co., Ltd.)
that has a core made of butadiene rubber and a graft layer covering
the core can be used as the first particle to thereby move the
rubber particle to the surface side of the coating film during the
drying of the solvent from the coating film. As a result, the
member for electrophotography can be formed such that the first
particles 309 viewed from a position opposed to the member for
electrography have their respective inter-particle surface
distances on average (hereinafter, referred to as an average
inter-particle surface distance) of 50 nm or less. In this context,
the average inter-particle surface distance can be controlled by
the content of the first particle in the coating liquid.
[0085] The drying time of the coating film can be 5 (five) minutes
or longer in order to secure the time necessary for the first
particle to be moved to the surface side of the coating film.
[0086] <Other Components of Member for
Electrophotography>
[0087] <Substrate>
[0088] An electro-conductive substrate can be used as the
substrate, and, for example, a metallic (alloy) support (e.g., a
cylindrical metal) made of iron, copper, stainless, aluminum,
aluminum alloy or nickel can be used.
[0089] <Elastic Layer>
[0090] An electro-conductive elastic layer can be used as the
elastic layer. The electro-conductive elastic layer can contain,
for example, a polymer elastomer and an electro-conductive agent.
Examples of the polymer elastomer include: synthetic rubbers such
as epichlorohydrin rubber, acrylonitrile-butadiene rubber,
chloroprene rubber, urethane rubber and silicone rubber; and
thermoplastic elastomers such as styrene-butadiene-styrene block
copolymer and styrene-ethylene/butylene-styrene block copolymer.
One of these polymer elastomers may be used, or two or more thereof
may be used in combination. The elastic layer can have ion
conductivity. Therefore, epichlorohydrin rubber can be used as the
polymer elastomer. The epichlorohydrin rubber can exert favorable
conductivity, even when supplemented with the electro-conductive
agent in a small amount, because the polymer itself has
conductivity in a medium-resistance region. In addition, the
epichlorohydrin rubber is suitably used as the polymer elastomer
because positional variations in electric resistance can also be
decreased.
[0091] Examples of the epichlorohydrin rubber include
epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide
copolymer, epichlorohydrin-allyl glycidyl ether copolymer and
epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary
copolymer. One of these epichlorohydrin rubbers may be used, or two
or more thereof may be used in combination. Among these rubbers,
epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary
copolymer can be used because of exhibiting stable conductivity in
a medium-resistance region. The electro-conductivity or
processability of the epichlorohydrin-ethylene oxide-allyl glycidyl
ether ternary copolymer can be controlled by arbitrarily adjusting
the degree of polymerization or compositional ratio.
[0092] The elastic layer may contain, for example, epichlorohydrin
rubber alone as the polymer elastomer or may contain
epichlorohydrin rubber as a main component and, optionally, an
additional rubber. Examples of the additional rubber include EPM
(ethylene-propylene rubber), EPDM (ethylene-propylene-diene
rubber), NBR (nitrile rubber), chloroprene rubber, natural rubbers,
isoprene rubber, butadiene rubber, styrene-butadiene rubber,
urethane rubber and silicone rubber. Alternatively, the elastic
layer may contain a thermoplastic elastomer such as SBS
(styrene-butadiene-styrene block copolymer) or SEBS
(styrene-ethylene/butylene-styrene block copolymer). One of these
additional rubbers may be used, or two or more thereof may be used
in combination. In the case of containing the additional rubber,
the content of the additional rubber can be 1 to 50 parts by mass
with respect to 100 parts by mass of the elastic layer.
[0093] An ion conductive agent or an electron conductive agent can
be used as the electro-conductive agent. An ion conductive agent
can be used as the electro-conductive agent from the viewpoint of
decreasing the electric resistivity unevenness of the elastic
layer. The ion conductive agent can be uniformly dispersed in the
polymer elastomer to achieve the even electric resistance of the
elastic layer. Also in the case of using the ion conductive agent
for applying only direct-current voltage to the member for
electrophotography used as the charging member, the image bearing
member can be uniformly charged.
[0094] The ion conductive agent is not particularly limited as long
as the ion conductive agent exhibits ion conductivity. Examples of
the ion conductive agent include: inorganic ionic substances such
as lithium perchlorate, sodium perchlorate and calcium perchlorate;
quaternary ammonium salts such as lauryl trimethylammonium
chloride, stearyl trimethylammonium chloride and tetrabutylammonium
perchlorate; and inorganic salts of organic acids such as lithium
trifluoromethanesulfonate and potassium perfluorobutanesulfonate.
These ion conductive agents can be used alone or in combination of
two or more types thereof. Among these ion conductive agents,
perchloric acid quaternary ammonium salt can be used because of
having stable resistance against environmental change.
[0095] The electron conductive agent is not particularly limited as
long as the electron conductive agent is an electro-conductive
particle that exhibits electron conductivity. Examples thereof can
include: carbon black such as furnace black, thermal black,
acetylene black and ketjen black; an electro-conductive particle of
metal oxides such as titanium oxide, tin oxide and zinc oxide; and
an electro-conductive particle of metals such as aluminum, iron,
copper and silver. These electron conductive agents can be used
alone or in combination of two or more types thereof.
[0096] The content of the electro-conductive agent can be an amount
in which the volume resistivity of the elastic layer is
1.times.10.sup.3 to 1.times.10.sup.9 .OMEGA.cm in a low-temperature
and low-humidity environment (15.degree. C. and 10% RH), a
normal-temperature and normal-humidity environment (23.degree. C.
and 50% RH) and a high-temperature and high-humidity environment
(30.degree. C. and 80% RH). This is because the resulting member
for electrophotography exerts favorable charging performance. In
addition, the elastic layer can optionally contain ingredients such
as a plasticizer, a filler, a vulcanizing agent, a vulcanization
promoter, an antioxidant, an antiscorching agent, a dispersant and
a releasing agent. The volume resistivity of the elastic layer is a
value measured in the same way as a method for measuring the volume
resistivity of the surface layer mentioned later using a volume
resistivity measurement sample obtained by molding materials for
use in the elastic layer into a sheet having a thickness of 1 mm
and depositing a metal onto both surfaces of the sheet to form an
electrode and a guard electrode.
[0097] The hardness of the elastic layer is preferably 50.degree.
or more and 70.degree. or less, more preferably 50.degree. or more
and 60.degree. or less, in terms of microhardness (MD-1 type). The
microhardness (MD-1 type) can be set to 50.degree. or more to
thereby inhibit the occurrence of image density unevenness derived
from the deformation of the charging member caused by the contact
between the charging member and the image bearing member in a
resting state for a long period. The microhardness (MD-1 type) can
be set to 70.degree. or less to thereby sufficiently secure the
width of the nip between the charging member and the image bearing
member and prevent toner from being deformed or cracked due to an
increased contact pressure.
[0098] The "microhardness (MD-1 type)" is a hardness measured using
ASKER microrubber hardness tester model MD-1 (trade name,
manufactured by Kobunshi Keiki Co., Ltd.). Specifically, the
microhardness (MD-1 type) is a value measured for a sample left for
12 hours or longer in a normal-temperature and normal-humidity
(23.degree. C. ad 50% RH) environment using the hardness tester at
the 10 N peak hold mode.
[0099] The elastic layer can be prepared by mixing starting
materials for the elastic layer in a hermetical mixer and molding
the mixture by a method, for example, extrusion molding, injection
molding or compression molding. Alternatively, the elastic layer
may be molded directly on the substrate, or the substrate may be
covered with the elastic layer molded in advance into a tube shape.
The surface of the elastic layer thus prepared may be polished to
arrange its shape.
[0100] <Process Cartridge and Image Forming Apparatus>
[0101] The process cartridge has an image bearing member and a
charging member disposed in contact with the image bearing member.
The process cartridge is also configured to be detachably
attachable to the body of an image forming apparatus. The charging
member is the member for electrophotography according to the
present invention.
[0102] The image forming apparatus has an image bearing member, a
charging apparatus which charges the image bearing member, a
developing apparatus which develops an electrostatic latent image
formed on the image bearing member by use of a developer, and a
transfer member which transfers the developer supported by the
image bearing member to a transfer medium. The charging apparatus
has a charging member which is the member for electrophotography
according to the present invention. The charging apparatus can also
have a voltage application device which applies voltage to the
charging member. The charging apparatus can charge the surface of
the image bearing member upon contact with the image bearing
member, while recovering the developer remaining on the image
bearing member after a transfer step of transferring the developer
supported by the image bearing member to the transfer medium. One
example of the image forming apparatus according to the present
invention is illustrated in FIG. 1.
[0103] The image forming apparatus illustrated in FIG. 1 includes
an image bearing member 5 which rotates clockwise in FIG. 1, a
charging member 6 which is the member for electrophotography
according to the present invention, a transfer member 10, a cleaner
container 11, a cleaning blade 12, a fixing device 13, a pickup
roller 14, and the like. The image bearing member 5 is charged by
the charging member 6 through the application of voltage thereto by
a voltage application device (not shown). Then, the image bearing
member 5 is irradiated with laser beams by a laser generation
device 16 for light exposure to form an electrostatic latent image
corresponding to the desired image on the charged surface of the
image bearing member 5. The electrostatic latent image on the image
bearing member 5 is developed via a toner bearing member 7 and a
toner supplying member 8 by toner, which is the developer in a
developing apparatus 9, to obtain a toner image. The toner image is
transferred onto a transfer medium 15 such as paper by the transfer
member 10 which is in contact with the image bearing member 5 via
the transfer medium 15 and to which voltage having reversed
polarity of the polarity of the toner has been applied. The
transfer medium 15 carrying the toner image is delivered to the
fixing device 13 so that the toner image is fixed on the transfer
medium 15. Toner partially remaining on the image bearing member 5
is scraped off by the cleaning blade 12 and housed in the cleaner
container 11.
[0104] The charging apparatus according to the present invention
can be a contact charging apparatus which applies a predetermined
charging bias to the charging member 6 that has formed a contact
part by contact with the image bearing member 5, to charge the
surface of the image bearing member 5 into a predetermined polarity
and potential. The contact charging using the apparatus achieves
stable and uniform charging and can further reduce the generation
of ozone. The charging member 6 that rotates in the opposite
direction as in the image bearing member 5 can be used for keeping
the contact with the image bearing member 5 uniform and carrying
out even charging. That is, in the case that the
electrophotographic photosensitive member 5 is rotated in the
clockwise direction, the charging member is preferably rotated in
the counterclockwise direction. Also, the charging member 6 can be
moved with a difference in speed from the image bearing member 5.
The charging member 6 can be configured to be moved with a
difference in speed kept in the forward direction with respect to
the moving direction of the image bearing member 5. This
configuration adopted in the cleaner-less image forming apparatus
can prevent residual toner on the image bearing member 5 from being
moved onto the surface of the charging member 6.
[0105] According to one aspect, the present invention can provide a
member for electrophotography. The member for electrophotography
can be used as, for example, a charging member, a developing member
or a transfer member. The present invention can also provide a
process cartridge and an image forming apparatus that can form a
high-quality image.
EXAMPLES
[0106] Hereinafter, the present invention will be described in more
detail with reference to Examples. However, the present invention
is not intended to be limited by these Examples by any means. The
unit "part" means "part by mass".
Example 1
1. Preparation of Unvulcanized Rubber Composition
[0107] Each material of type and amount shown in Table 1 was mixed
using a pressurization-type kneader to obtain kneaded rubber
composition A. Further, 183.0 parts by mass of the kneaded rubber
composition A were mixed with each material of type and amount
shown in Table 2 below using an open roll to obtain an unvulcanized
rubber composition.
TABLE-US-00001 TABLE 1 Parts Material by mass
Epichlorohydrin-ethylene oxide-allyl glycidyl 100.0 ether ternary
copolymer (GECO) (trade name: Epichlomer CG-102, manufactured by
Osaka Soda Co., Ltd. (formally Daiso Co., Ltd.)) Zinc oxide (Zinc
Oxide Two, manufactured by 5.0 Seido Chemical Industry Co., Ltd.)
Calcium carbonate 60.0 (trade name: Silver W, manufactured by
Shiraishi Calcium Kaisha, Ltd.) Carbon black 5.0 (trade name:
Thermax Flow Form N990, manufactured by Cancarb Limited) Stearic
acid 1.0 Aliphatic polyester plasticizer 10.0 (trade name:
Polycizer P202, manufactured by DIC Corporation (formerly,
Dainippon Ink and Chemicals, Inc.)) Ion conductive agent:
perchloric acid 2.0 quaternary ammonium salt (trade name:
Adekacizer LV70, manufactured by ADEKA Corporation)
TABLE-US-00002 TABLE 2 Parts Material by mass Sulfur (trade name:
Sulfax PMC, 0.8 manufactured by Tsurumi Chemical Industry Co.,
Ltd.) Dibenzothiazolyl disulfide 1.0 (trade name: Nocceler DM,
manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.)
Tetramethylthiuram monosulfide 0.5 (trade name: Nocceler TS,
manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.)
2. Preparation of Elastic Member
[0108] A steel substrate (having nickel-plated surface) in a
cylindrical shape of 6 mm in diameter and 252.5 mm in length was
coated with a thermosetting adhesive (Metalock N-33, manufactured
by ToyoKagaku Kenkyusho Co., Ltd.). The resulting product was dried
at 80.degree. C. for 30 minutes and then further dried at
120.degree. C. for 1 hour.
[0109] Next, the unvulcanized rubber composition was coaxially
extruded in a cylindrical form of 8.75 to 8.90 mm in outer diameter
onto the substrate using a crosshead extruder to obtain an
unvulcanized rubber member. Subsequently, the unvulcanized rubber
member was charged into a hot-air vulcanization furnace of
160.degree. C. and heated for 60 minutes for the vulcanization of
the unvulcanized rubber composition layer to obtain an unpolished
elastic member. Then, both ends of the rubber were cut off to
adjust the length of the elastic layer to 232 mm. Then, the surface
of the elastic layer was polished with a grindstone into a roller
shape having an outer diameter of 8.5 mm to obtain an elastic
member having the elastic layer on the substrate. The crown
quantity (difference in outer diameter between the central portion
and a position 90 mm distant from the central portion) of the
elastic member was 110 .mu.m.
3. Preparation of Coating Liquid 1
[0110] Coating liquid 1 for use in the formation of a surface layer
was prepared by the following approach: in a nitrogen atmosphere,
100 parts by mass of polyester polyol (trade name: P3010,
manufactured by Kuraray Co., Ltd.) were gradually added dropwise to
27 parts by mass of polymeric MDI (polymethylene polyphenyl
polyisocyanate) (trade name: Millionate MR200, manufactured by
Tosoh Corporation) in a reaction vessel, while the internal
temperature of the reaction vessel was kept at 65.degree. C. After
the completion of the dropwise addition, the mixture was reacted at
65.degree. C. for 2 hours. The obtained reaction mixture was cooled
to room temperature to obtain isocyanate-terminated prepolymer 1
having an isocyanate group content of 4.3% by mass.
[0111] 54.9 parts by mass of the isocyanate-terminated prepolymer
1, 41.52 parts by mass of polyester polyol (trade name: P2010,
manufactured by Kuraray Co., Ltd.) and 23 parts by mass of carbon
black (MA230, manufactured by Mitsubishi Chemical Corp.) were added
to methyl ethyl ketone (MEK). The solid content of this mixture was
adjusted to 27% by mass to prepare mixed solution 1. 270 parts by
mass of the mixed solution 1, 15 parts by mass of rubber particle
(trade name: Metablen C-223A, manufactured by Mitsubishi Rayon Co.,
Ltd.) having a number-average particle diameter of 200 nm as the
first particle, and 200 parts by mass of glass beads having an
average particle diameter of 0.8 mm were placed in a 450 mL glass
vial. This mixture was dispersed for 12 hours using a paint shaker
dispersing machine. Then, 30 parts by mass of urethane resin
particle (trade name: DAIMICBEAZ UCN-5070D, manufactured by
Dainichi Seika Color & Chemical Mfg. Co., Ltd.) having a
number-average particle diameter of 7.0 .mu.m were added thereto as
the second particle. Then, the mixture was further dispersed for 15
minutes, and the glass beads were removed to obtain coating liquid
1.
4. Preparation of Member 1 for Electrophotography
[0112] The elastic member was dipped once in the coating liquid 1
and then dried in air at 23.degree. C. for 30 minutes.
Subsequently, the resulting product was dried for 1 hour in a
hot-air circulation dryer set to 80.degree. C., and further dried
for 1 hour in a hot-air circulation dryer set to 160.degree. C. to
form a surface layer on the outer peripheral surface of the elastic
member. The dipping time for the dip coating was 9 seconds. The
pulling rate for the dip coating was adjusted to 20 mm/sec as an
initial speed and 2 mm/sec as a final speed and changed linearly
with respect to the time from 20 mm/sec to 2 mm/sec. In this way,
the member 1 for electrophotography having the surface layer formed
on the elastic layer was obtained.
5. Physical Property Evaluation
[0113] Next, the obtained member 1 for electrophotography was
evaluated for the following physical properties.
[0114] <Evaluation 5-1. Thickness of Surface Layer>
[0115] A total of 9 cross sections (3 areas in the axial
direction.times.3 areas in the circumferential directions) of the
surface layer were cut out with a sharp knife. The respective
thicknesses of these areas were measured by observation under an
optical microscope or an electron microscope, and an average
thereof was adopted. The measurement results are shown in Tables
9-1 to 9-6.
[0116] <Evaluation 5-2. Universal Hardness of Surface of Surface
layer>
[0117] The universal hardness at a position 1 .mu.m deep from the
surface of the surface layer was measured using a universal
hardness tester. The measurement results are shown in Tables 9-1 to
9-6.
[0118] In this measurement, a microhardness tester (trade name:
FISCHERSCOPE HM-2000, manufactured by Helmut Fischer GmbH) was
used. The specific measurement conditions are given below.
Measurement indenter: Vickers indenter, interfacial angle
136.degree., Young's modulus of 1140 GPa, Poisson's ratio of 0.07;
Measurement environment: temperature: 23.degree. C., relative
humidity: 50% Maximum test load: 1.0 mN Load conditions: A load was
applied in proportion to time at a rate where the load reached the
maximum test load in 30 seconds.
[0119] In this evaluation, the universal hardness is calculated
according to the following expression (1) using a load F at the
point in time when the indenter was pressed into the depth of 1
.mu.m from the surface of the surface layer, and a contact area A
between the indenter and the surface layer, at the time.
Universal hardness (N/mm.sup.2)=F/A Expression (1)
[0120] <Evaluation 5-3. Martens Hardness of Second Convex of
Surface Layer>
[0121] The Martens hardness of the second convex derived from the
second particle (urethane resin particle) in the surface layer was
measured using a microhardness tester (trade name: PICODENTOR
HM-500, manufactured by Helmut Fischer GmbH). The measurement
results are shown in Tables 9-1 to 9-6.
[0122] The measurement conditions are given below.
Measurement indenter: Vickers indenter, interfacial angle
136.degree., Young's modulus of 1140 GPa, Poisson's ratio of 0.07;
Indenter material: diamond Measurement environment: temperature:
23.degree. C., relative humidity: 50% Loading rate and unloading
rate: 1 mN/50 seconds
[0123] In this evaluation, the tip of the indenter was contacted
with the second convex on the surface of the member for
electrophotography, and a load was applied thereto at the rate
described in the aforementioned conditions. When the load reached
0.04 mN, the load was kept for the time described in the
aforementioned conditions. Then, an indentation depth h was
determined, and the Martens hardness was calculated according to
the following expression (2).
Martens hardness HM (N/mm.sup.2)=F(N)/Surface area (mm.sup.2) of
the indenter under the test load Expression (2)
[0124] <Evaluation 5-4. Arithmetic average roughness (Ra) of
Surface>
[0125] The arithmetic average roughness (Ra) of the surface was
measured based on JIS B0601:1982 using a surface roughness tester
(trade name: Surfcorder SE3400, manufactured by Kosaka Laboratory
Ltd.). In this measurement, a diamond contact probe having a tip
radius of 2 .mu.m was used. The measurement speed was 0.5 mm/s; the
cutoff frequency .lamda.c was 0.8 mm; the reference length was 0.8
mm; and the evaluation length was 8.0 mm. The respective roughness
curves were measured for a total of 9 points (3 points in the axial
direction.times.3 points in the circumferential direction) in the
surface of the member 1 for electrophotography to calculate Ra.
Average Ra of these 9 points was determined. This average value was
used as the Ra value of the member 1 for electrophotography. The
measurement results are shown in Tables 9-1 to 9-6.
[0126] <Evaluation 5-5. Volume Resistivity of Surface
Layer>
[0127] The volume resistivity of the surface layer was measured
using an atomic force microscope (AFM) (trade name: Q-scope 250,
manufactured by Quesant Instrument Corp.) at the electro-conductive
mode. Specifically, the surface layer was cut into a sheet of 2 mm
in width and 2 mm in length using a manipulator, and platinum was
deposited on one surface thereof. Next, a direct-current power
supply (trade name: 6614C, manufactured by Agilent Technologies,
Inc.) was connected to the platinum-deposited surface and allowed
to apply 10 V thereto. A free end of a cantilever was contacted
with the other surface to obtain a current image through the body
of AFM. 100 areas in the surface layer were randomly measured, and
the volume resistivity was calculated from the average current
value of top 10 areas of low current values, and the thickness. The
measurement conditions are given below. The measurement results are
shown in Tables 9-1 to 9-6.
[0128] [Measurement Conditions]
Measurement mode: contact
Cantilever: CSC17
[0129] Measurement range: 10 nm.times.10 nm Scan rate: 4 Hz Applied
voltage: 10 V
[0130] <Evaluation 5-6. Average Inter-Particle Surface Distance
of First Particles Resulting in a First Convex>
[0131] The average inter-particle surface distance of the first
particles (rubber particles) resulting in the first convex on the
surface of the surface layer of the member for electrophotography
was measured by the following method.
[0132] First, a sample (size: 10 mm long, 10 mm wide and 3 mm
thick) containing the surface of the surface layer was cut out of
the member for electrophotography. Platinum was deposited at a
thickness of 10 nm onto the surface (which corresponded to the
surface of the surface layer) of the sample. Subsequently, the
platinum-deposited surface of the sample was exposed to electron
beams using a scanning electron microscope (trade name: S-4800,
manufactured by Hitachi High-Technologies Corp.). A region of 3.0
.mu.m long.times.3.0 .mu.m wide was observed at a magnification of
.times.40000 and photographed.
[0133] The obtained image was analyzed using image analysis
software (trade name: Image-Pro Plus, manufactured by Roper
Technologies, Inc. (formerly PlanEtron)). Specifically, the number
of pixels per unit length was calibrated from the micron bar during
the photographing. 20 first particles in the photograph were
randomly selected, and the inter-particle surface distances of each
particle from its neighboring particles were measured. Then, the
largest inter-particle surface distance among the inter-particle
surface distances of each particle from its neighboring particles
was defined as the inter-particle surface distance of this
particle. An arithmetic average thereof was used as the average
inter-particle surface distance.
[0134] If 20 first particles cannot be observed in the region of
3.0 .mu.m long.times.3.0 .mu.m wide, the inter-particle surface
distances are measured by sequentially moving the region until the
20 first particles to be measured and their neighboring first
particles can be recognized.
6. Image Evaluation
[0135] Next, the obtained member 1 for electrophotography was used
in the following image evaluation.
[0136] <Evaluation 6-1. Dirt Evaluation>
[0137] A laser beam printer (trade name: HP LaserJet P1505 Printer,
manufactured by HP Inc.) was prepared as an image forming
apparatus. The laser beam printer is capable of outputting A4 size
paper in the longitudinal direction. The laser printer has a
printing speed of 23 sheets/min. and an image resolution of 600
dpi. The member 1 for electrophotography was incorporated as a
charging member into a process cartridge (trade name: "HP 36A
(CB436A)", manufactured by HP Inc.) for the laser beam printer. The
resulting process cartridge was loaded in the laser beam
printer.
[0138] The laser beam printer was used to form 2000 images with a
4-point letter of alphabet "E" printed at a coverage rate of 1% on
A4 size paper in a low-temperature and low-humidity (temperature:
15.degree. C., relative humidity: 10%) environment. This image
formation was carried out at the so-called intermittent mode
involving stopping the rotation of the image bearing member over 7
seconds after each output of one sheet. The image formation at the
intermittent mode increases the number of rubs between the charging
member and the image bearing member as compared with continuous
image formation, and thus serves as more stringent evaluation
conditions for the charging member. After the completion of the
output of 2000 images in this way, halftone images in which lines
having a width of 1 dot were drawn in a direction perpendicular to
the rotational direction of the image bearing member at 2 dots
interval, as shown in FIG. 5, were output. The obtained images were
evaluated according to criteria given below. The evaluation results
are shown in Tables 9-1 to 9-6.
A: Charging unevenness caused by the adhesion of toner or external
additives to the surface of the charging member was not found on
the output image. B: Charging unevenness caused by the adhesion of
toner or external additives to unevenly coated or streak portions
on the surface of the charging member was hardly found on the
output image. C: Charging unevenness caused by the adhesion of
toner or external additives to unevenly coated or streak portions
on the surface of the charging member was found on the output
image. D: Charging unevenness caused by the adhesion of toner or
external additives to unevenly coated or streak portions on the
surface of the charging member was found on the output image, and
the degree of this charging unevenness was large, specifically, the
charging unevenness was found as white longitudinal streaks.
[0139] <Evaluation 6-2. Discharge Characterization>
[0140] Images were output in the same way as in the evaluation 6-1
and evaluated according to criteria given below. The evaluation
results are shown in Tables 9-1 to 9-6.
A: White spots were not visually observed on the output image. B:
White spots were slightly observed on the output image. C: White
spots were observed throughout the output image.
[0141] <Evaluation 6-3. Evaluation of the Amount of Injection
Charge>
[0142] The member 1 for electrophotography was incorporated as a
charging member into a process cartridge (trade name: "HP 36A
(CB436A)", manufactured by HP Inc.). A surface potential tester
probe (trade name: MODEL 555P-1, manufactured by TREK Japan K.K.)
was placed at a position that was a position rotated by 90 degrees
from the position of the charging member in the circumferential
direction to the developing apparatus side of the image bearing
member and was 2 mm distant from the image bearing member. The
process cartridge was inserted to a laser beam printer (trade name:
HP LaserJet P1505 Printer, manufactured by HP Inc.). In a
high-temperature and high-humidity (temperature: 30.degree. C.,
relative humidity: 80%) environment, the surface potential (amount
of injection charge) of the position 90 mm distant from the central
portion of the image bearing member was measured upon application
of DC -500 V voltage to the charging member at half the rotational
speed of the image bearing member. The average waveform in the
first round of the measured image bearing member was defined as the
amount of injection charge. The evaluation results are shown in
Tables 9-1 to 9-6.
[0143] The amount of injection charge is a value measured under the
condition of DC -500 V without the discharge of the charging
member. The amount of injection charge evaluated here is an amount
of injection charge added to the image bearing member due to a
factor other than the discharge. Therefore, a larger value of the
amount of injection charge means that the surface potential of the
image bearing member is more difficult to control in actual image
output. This phenomenon is particularly prominent in a
high-temperature and high-humidity environment. As a guide, the
amount of injection charge in which image output with a stable
density can be maintained is 50 [-V] or less.
[0144] <Evaluation 6-4. Dirt Evaluation (Cleaner-Less)>
[0145] Next, dirt evaluation was conducted using a cleaner-less
mechanism. A gear was installed on the member 1 for
electrophotography such that the member for electrophotography
rotates at a circumferential speed with a difference of 5% in the
forward direction relative to the rotation of the image bearing
member. The gear-attached member 1 for electrophotography was
incorporated as a charging member into a process cartridge (trade
name: "HP 36A (CB436A)", manufactured by HP Inc.) from which a
cleaning blade was removed. The process cartridge and a laser beam
printer (trade name: HP LaserJet P1505 Printer, manufactured by HP
Inc.) were used to output 100 images, in each of the images, lines
having a width of 2 dots were drawn in a direction perpendicular to
the rotational direction of the image bearing member at 100 dots
interval on A4 size paper in a low-temperature and low-humidity
(temperature: 15.degree. C., relative humidity: 10%) environment.
Then, the member 1 for electrophotography was removed from the
process cartridge. The "dirt evaluation (cleaner-less) 105%" was
conducted by the following tape coloring evaluation.
[0146] The tape coloring evaluation was conducted as follows:
adhesive polyester tape (trade name: No. 31B, manufactured by Nitto
Denko Corp.) was attached to the surface of the member 1 for
electrophotography. Then, the adhesive tape was peeled off together
with toner adhering to the surface of the member 1 for
electrophotography and attached to white paper. This operation was
carried out as to the whole image printing region on the surface of
the member 1 for electrophotography. Then, the reflection density
of the adhesive tape was measured using a photovoltaic reflection
densitometer (trade name: TC-6DS/A, manufactured by Tokyo Denshoku
Co., Ltd.) to determine the maximum value (A) thereof. Next, the
reflection density of the fresh polyester adhesive tape attached to
white paper was measured in the same way as above to determine the
minimum value (B) thereof. The difference between the minimum value
(B) and the maximum value (A) was used as a value of the coloring
density. A smaller value of the coloring density means favorable
results about the member for electrophotography having a smaller
amount of dirt. Therefore, the value was used as an index for the
degree of dirt on the member for electrophotography. The evaluation
results are shown in Tables 9-1 to 9-6.
[0147] Next, a gear was installed on the member for
electrophotography such that the member 1 for electrophotography
rotates at a circumferential speed with a difference of 10% in the
forward direction relative to the rotation of the image bearing
member. Images were output in the same way as in the "dirt
evaluation (cleaner-less) 105%". The "dirt evaluation
(cleaner-less) 110%" of the member 1 for electrophotography was
conducted by the tape coloring evaluation. The evaluation results
are shown in Tables 9-1 to 9-6.
[0148] <Evaluation 6-5. Evaluation of Amount of Injection Charge
(Cleaner-Less)>
[0149] The member 1 for electrophotography provided with a 5%
difference in peripheral speed in the forward direction with
respect to the rotation of the image bearing member in the same way
as in the evaluation 6-4 was incorporated as a charging member into
a process cartridge (trade name: "HP 36A (CB436A)", manufactured by
HP Inc.) from which a cleaning blade was removed. A surface
potential tester probe (trade name: MODEL 555P-1, manufactured by
TREK Japan K.K.) was placed at a position that was a position
rotated by 90 degrees from the position of the charging member in
the circumferential direction to the developing apparatus side of
the image bearing member and was 2 mm distant from the image
bearing member. The process cartridge was inserted to a laser beam
printer (trade name: HP LaserJet P1505 Printer, manufactured by HP
Inc.). In the same way as in the evaluation 6-3, the surface
potential (amount of injection charge) of the position 90 mm
distant from the central portion of the image bearing member was
measured upon application of DC -500 V voltage to the charging
member. The average waveform in the first round of the measured
image bearing member was defined as the "amount of injection charge
(cleaner-less) 105%". The evaluation results are shown in Tables
9-1 to 9-6.
[0150] Next, the member 1 for electrophotography provided with a
10% difference in peripheral speed in the forward direction with
respect to the rotation of the image bearing member was
incorporated as a charging member into the process cartridge from
which a cleaning blade was removed. The "amount of injection charge
(cleaner-less) 110%" was measured in the same way as in the
measurement of the "amount of injection charge (cleaner-less)
105%". The evaluation results are shown in Tables 9-1 to 9-6.
Examples 2 to 37
Preparation of Coating Liquids 2 to 33
[0151] Coating liquids 2 to 33 were prepared in the same way as in
the coating liquid 1 except that the composition was changed as
shown in Tables 3-1 to 3-4. The types of the following components
(A) to (E) described in Tables 3-1 to 3-4 are shown in Table 4.
(A) Polyol (hydroxy-terminated prepolymer), (B) Isocyanate
(isocyanate-terminated prepolymer), (C) Second particle, (D)
Silicone additive and (E) First particle
[0152] Some part of isocyanate-terminated prepolymers used were
prepared in the same way as in Example 1 by adjusting the
isocyanate group content to 4.3% by mass through the preliminary
reaction between polyol and polymeric MDI (trade name: Millionate
MR200, manufactured by Tosoh Corporation).
[0153] <Preparation of Members 2 to 37 for
Electrophotography>
[0154] Members 2 to 37 for electrophotography were produced and
evaluated in the same way as in Example 1 except that the coating
liquid for use in the formation of a surface layer was changed as
described in Tables 9-1 to 9-6.
[0155] As for Examples 35, 36 and 37, the members for
electrophotography were produced in the same way as in Examples 1,
18 and 31, respectively, followed by the ultraviolet treatment of
their surface layers. The ultraviolet treatment was carried out by
irradiation with ultraviolet rays with a wavelength of 254 nm at a
cumulative light quantity of 9000 mJ/cm.sup.2 using a low-pressure
mercury lamp (manufactured by Toshiba Lighting & Technology
Corp. (formerly HARISON TOSHIBA LIGHTING Corp.)). The evaluation
results are shown in Tables 9-1 to 9-6.
TABLE-US-00003 TABLE 3-1 Coating Coating Coating Coating Coating
Coating Coating Coating Coating Coating liquid 1 liquid 2 liquid 3
liquid 4 liquid 5 liquid 6 liquid 7 liquid 8 liquid 9 liquid 10
Polyol A-1 A-1 A-1 A-1 A-1 A-1 A-1 A-1 A-1 A-1 (A) Isocyanate B-1
B-1 B-1 B-1 B-1 B-1 B-1 B-1 B-1 B-1 (B) Amount of A/B 41.5/54.9
41.5/54.9 41.5/54.9 41.5/54.9 41.5/54.9 41.5/54.9 41.5/54.9
41.5/54.9 41.5/54.9 41.5/54.9 added (parts) Second particle C-1 C-1
C-1 -- -- -- -- C-1 C-1 C-2 (C) Amount of C 30 15 45 -- -- -- -- 30
30 30 added (parts) Silicone additive -- -- -- -- -- -- -- -- -- --
(D) Amount of D -- -- -- -- -- -- -- -- -- -- added (parts) First
particle E-1 E-1 E-1 E-1 E-1 E-1 E-1 E-2 E-3 E-1 (E) Amount of E 15
15 15 15 30 45 60 15 15 15 added (parts)
TABLE-US-00004 TABLE 3-2 Coating Coating Coating Coating Coating
Coating Coating Coating Coating Coating liquid 11 liquid 12 liquid
13 liquid 14 liquid 15 liquid 16 liquid 17 liquid 18 liquid 19
liquid 20 Polyol A-1 A-1 A-1 A-1 A-2 A-2 A-2 A-2 A-2 A-2 (A)
Isocyanate B-1 B-1 B-1 B-1 B-2 B-2 B-2 B-2 B-2 B-2 (B) Amount of
A/B 41.5/54.9 41.5/54.9 41.5/54.9 41.5/54.9 46/54 46/54 46/54 46/54
46/54 46/54 added (parts) Second particle C-3 C-4 C-1 C-1 C-1 C-1
C-1 -- -- -- (C) Amount of C 30 30 30 30 15 30 45 -- -- -- added
(parts) Silicone additive -- -- D-1 D-2 -- -- -- -- -- -- (D)
Amount of D -- -- 0.1 0.1 -- -- -- -- -- -- added (parts) First
particle E-1 E-1 E-1 E-1 E-1 E-1 E-1 E-1 E-1 E-1 (E) Amount of E 15
15 15 15 15 15 15 15 30 45 added (parts)
TABLE-US-00005 TABLE 3-3 Coating Coating Coating Coating Coating
Coating Coating Coating Coating Coating liquid 21 liquid 22 liquid
23 liquid 24 liquid 25 liquid 26 liquid 27 liquid 28 liquid 29
liquid 30 Polyol (A) A-2 A-2 A-2 A-2 A-2 A-3 A-3 A-3 A-4 A-4
Isocyanate (B) B-2 B-2 B-2 B-2 B-2 B-3 B-3 B-3 B-4 B-4 Amount of
A/B added 46/54 46/54 46/54 46/54 46/54 52/48 52/48 52/48 43/57
43/57 (parts) Second particle (C) -- C-1 C-1 C-4 C-1 C-1 -- C-4 C-1
-- Amount of C added (parts) -- 30 30 30 30 30 -- 30 30 -- Silicone
additive (D) -- -- -- -- D-1 -- -- -- -- -- Amount of D added
(parts) -- -- -- -- 0.1 -- -- -- -- -- First particle (E) E-1 E-2
E-3 E-1 E-1 E-1 E-1 E-1 E-1 E-1 Amount of E added (parts) 60 15 15
15 15 15 15 15 15 15
TABLE-US-00006 TABLE 3-4 Coating Coating Coating liquid 31 liquid
32 liquid 33 Polyol (A) A-4 A-5 A-6 Isocyanate (B) B-4 B-5 B-6
Amount of A/B added (parts) 43/57 59/41 41/59 Second particle (C)
C-4 C-1 C-1 Amount of C added (parts) 30 30 30 Silicone additive
(D) -- -- -- Amount of D added (parts) -- -- -- First particle (E)
E-1 E-1 E-1 Amount of E added (parts) 15 15 15
TABLE-US-00007 TABLE 4 A-1 Polyester polyol (trade name: P2010,
manufactured by Kuraray Co., Ltd.) A-2 Polycarbonate polyol (trade
name: T5652, manufactured by Asahi Kasei Chemicals Corporation) A-3
Castor oil (trade name: URIC-H 1823, manufactured by Itoh Oil
Chemicals Co., Ltd.) A-4 Polyolefin polyol (trade name: G2000,
manufactured by Nippon Soda Co., Ltd.) A-5 Acrylic polyol (trade
name: DC2016, manufactured by Daicel Corporation (formerly Daicel
Chemical Industries, Ltd.) A-6 Polyether polyol (trade name: Exenol
3020, manufactured by Asahi Glass Co., Ltd.) B-1 Polyester
polyol/polymeric MDI (trade name: P3010, manufactured by Kuraray
Co., Ltd./trade name: Millionate MR200, manufactured by Tosoh
Corporation) B-2 Polycarbonate polyol/polymeric MDI (trade name:
T5652, manufactured by Asahi Kasei Chemicals Corporation/trade
name: Millionate MR200, manufactured by Tosoh Corporation) B-3
Polyester polyol/polymeric MDI (trade name: P2050, manufactured by
Kuraray Co., Ltd./trade name: Millionate MR200, manufactured by
Tosoh Corporation) B-4 Polyolefin polyol/polymeric MDI (trade name:
G2000, manufactured by Nippon Soda Co., Ltd./trade name: Millionate
MR200, manufactured by Tosoh Corporation) B-5 Isocyanate
A/isocyanate B = 4/3 (trade name: Vestanat B1370, manufactured by
Evonik Industries AG (formerly Degussa AG)/trade name: Duranate
TPA-B80E, manufactured by Asahi Kasei Chemicals Corporation) B-6
Polypropylene glycol polyol/polymeric MDI (trade name: Exenol 1030,
manufactured by Asahi Glass Co., Ltd./trade name: Millionate MR200,
manufactured by Tosoh Corporation) C-1 DAIMICBEAZ UCN-5070D (trade
name, number-average particle diameter: 7.0 .mu.m, manufactured by
Dainichi Seika Color & Chemical Mfg. Co., Ltd.) C-2 DAIMICBEAZ
UCN-5150D (trade name, number-average particle diameter: 7.0 .mu.m,
manufactured by Dainichi Seika Color & Chemical Mfg. Co., Ltd.)
C-3 Art Pearl JB-600T (trade name, number-average particle
diameter: 10.0 .mu.m, manufactured by Negami Chemical Industrial
Co., Ltd.) C-4 Techpolymer MBX-8 (trade name, number-average
particle diameter: 8.0 .mu.m, manufactured by Sekisui Plastics Co.,
Ltd.) D-1 Modified dimethylsilicone oil (trade name: SH-28PA,
manufactured by Dow Corning Toray Co., Ltd. (formerly Dow Corning
Toray Silicone Co., Ltd.)) D-2 Silicone-modified acrylic resin
(trade name: SQ-100, manufactured by Tokushiki Co., Ltd. E-1
Metablen C-223A (trade name, number-average particle diameter: 200
nm, butadiene rubber type, manufactured by Mitsubishi Rayon Co.,
Ltd.) E-2 Metablen S-2001 (trade name, number-average particle
diameter: 800 nm, silicone rubber type, manufactured by Mitsubishi
Rayon Co., Ltd.) E-3 Metablen W-450A (trade name, number-average
particle diameter: 400 nm, acrylic rubber type, manufactured by
Mitsubishi Rayon Co., Ltd.)
Example 38
[0156] Member 38 for electrophotography was produced and evaluated
in the same way as in Example 1 except that a material described in
Table 5 was used instead of Epichlomer CG-102 (also referred to as
CG102) in the preparation of kneaded rubber composition A. The
evaluation results are shown in Table 9-6.
TABLE-US-00008 TABLE 5 Parts Material by mass
Epichlorohydrin-ethylene oxide-allyl glycidyl 100.0 ether ternary
copolymer (GECO) (trade name: EPION 301, manufactured by Osaka Soda
Co., Ltd. (formally Daiso Co., Ltd.))
Example 39
[0157] Each material of type and amount shown in Table 6 was mixed
using a pressurization-type kneader to obtain kneaded rubber
composition A. Further, the kneaded rubber composition A was mixed
with each material of type and amount shown in Table 7 using an
open roll to obtain an unvulcanized rubber composition. Member 39
for electrophotography was produced and evaluated in the same way
as in Example 1 except that the unvulcanized rubber composition was
used. The evaluation results are shown in Table 9-6.
TABLE-US-00009 TABLE 6 Parts Material by mass NBR (trade name:
Nipol DN219, 100 manufactured by Zeon Corporation) Carbon black 40
(trade name: Toka Black #7360SB, manufactured by Tokai Carbon Co.,
Ltd.) Calcium carboate 20 (trade name: Nanox #30, manufactured by
Maruo Calcium Co., Ltd.) Zinc oxide 5 Stearic acid 1
TABLE-US-00010 TABLE 7 Parts Material by mass Sulfur 1.2
Tetrabenzylthiuram disulfide 4.5 (trade name: TBZTD, manufactured
by Sanshin Chemical Industry Co., Ltd.)
Example 40
[0158] The same substrate as that used in Example 1 was coated with
a primer (trade name: DY35-051, manufactured by Dow Corning Toray
Co., Ltd.) and baked at a temperature of 150.degree. C. for 30
minutes. The obtained product was used as a substrate. This
substrate was placed in a die, and an addition-type silicone rubber
composition having a mixture of materials described in Table 8 was
injected to a cavity formed in the die.
TABLE-US-00011 TABLE 8 Parts Material by mass Liquid silicons
rubber 100 (trade name: SE6724A/B, manufactured by Dow Corning
Toray Co., Ltd.) Carbo black 28 (trade name: Toka Black #7360SB,
manufactured by Tokai Carbon Co., Ltd.) Silica powder 0.2 Platinum
catalyst 0.1
[0159] Next, the die was heated at 120.degree. C. for 8 minutes and
then cooled to room temperature, followed by demolding. Then, the
obtained product was heated at 200.degree. C. for 60 minutes,
vulcanized and cured to obtain an elastic layer having a thickness
of 2.5 mm on the outer peripheral surface of the substrate. Member
40 for electrophotography was produced and evaluated by the same
subsequent procedures as in Example 1. The evaluation results are
shown in Table 9-6.
TABLE-US-00012 TABLE 9-1 Example 1 Example 2 Example 3 Example 4
Example 5 Example 6 Example 7 Example 8 No. of member for 1 2 3 4 5
6 7 8 electrophotography Rubber material of elastic layer CG102
CG102 CG102 CG102 CG102 CG102 CG102 CG102 Surface layer material
Coating Coating Coating Coating Coating Coating Coating Coating
liquid 1 liquid 2 liquid 3 liquid 4 liquid 5 liquid 6 liquid 7
liquid 1 Surface layer thickness (.mu.m) 20 20 20 20 20 20 20 10
Ultraviolet treatment -- -- -- -- -- -- -- -- Physical property
evaluation Ra (.mu.m) 1.75 1.51 1.93 1.11 1.18 1.23 1.25 1.86
Universal hardness of surface 3.3 3.2 3.2 2.8 3.1 2.9 5.8 2.6 of
surface layer (N/mm.sup.2) Martens hardness of second convex 3.4
3.4 3.3 -- -- -- -- 3.1 of surface layer (N/mm.sup.2) Volume
resistivity of surface 6.00 .times. 10.sup.10 4.90 .times.
10.sup.10 7.80 .times. 10.sup.10 3.80 .times. 10.sup.10 4.80
.times. 10.sup.10 5.30 .times. 10.sup.10 7.20 .times. 10.sup.10
5.90 .times. 10.sup.10 layer (.OMEGA. cm) Average inter-particle
surface 38 40 41 44 38 29 21 37 distance of first particles
resulting in a first convex (nm) Image evaluation Dirt evaluation A
A B A A A A A Evaluation of amount of injection 5 7 4 9 8 8 6 9
charge (-V) Discharge property evaluation A A A B A A A A Dirt
evaluation 105% 11.3 10.4 15.2 8.3 8.5 8.6 8.5 11.5 (cleaner-less)
110% 5.9 5.4 7.8 5.1 4.8 4.8 4.7 6 Evaluation of amount of 105% 20
19 19 24 24 22 23 24 injection charge (cleaner-less) (-V) 110% 39
42 36 50 49 48 48 47
TABLE-US-00013 TABLE 9-2 Example 9 Example 10 Example 11 Example 12
Example 13 Example 14 Example 15 Example 16 No. of member for 9 10
11 12 13 14 15 16 electrophotography Rubber material of elastic
layer CG102 CG102 CG102 CG102 CG102 CG102 CG102 CG102 Surface layer
material Coating Coating Coating Coating Coating Coating Coating
Coating liquid 1 liquid 8 liquid 9 liquid 10 liquid 11 liquid 12
liquid 13 liquid 14 Surface layer thickness (.mu.m) 40 20 20 20 20
20 20 20 Ultraviolet treatment -- -- -- -- -- -- -- -- Physical
property evaluation Ra (.mu.m) 1.62 1.75 1.73 2.53 1.87 2.01 1.78
1.80 Universal hardness of surface of 4.3 3.1 3.4 3.1 2.9 5.8 3.4
3.5 surface layer (N/mm.sup.2) Martens hardness of second convex
4.4 3.3 3.5 3.5 2.9 12.3 3.5 3.6 of surface layer (N/mm.sup.2)
Volume resistivity of surface 6.30 .times. 10.sup.10 7.30 .times.
10.sup.10 7.10 .times. 10.sup.10 6.60 .times. 10.sup.10 6.50
.times. 10.sup.10 7.20 .times. 10.sup.10 7.70 .times. 10.sup.10
7.60 .times. 10.sup.10 layer (.OMEGA. cm) Average inter-particle
surface 41 38 39 41 39 40 37 38 distance of first particles
resulting in a first convex (nm) Image evaluation Dirt evaluation A
A A B A B A A Evaluation of amount of injection 3 5 5 6 5 3 5 4
charge (-V) Discharge property evaluation A A A A A A A A Dirt
evaluation 105% 12 12 11.1 14.4 11.8 23 12.1 12.2 (cleaner-less)
110% 6.1 6.4 6.3 8.1 7.6 14.3 6.2 6.1 Evaluation of amount of 105%
15 20 19 21 21 13 21 20 injection charge (cleaner-less) (-V) 110%
38 39 41 43 44 39 44 45
TABLE-US-00014 TABLE 9-3 Example 17 Example 18 Example 19 Example
20 Example 21 Example 22 Example 23 Example 24 Member for
electrophotography 17 18 19 20 21 22 23 24 Rubber material of
elastic layer CG102 CG102 CG102 CG102 CG102 CG102 CG102 CG102
Surface layer material Coating Coating Coating Coating Coating
Coating Coating Coating liquid 15 liquid 16 liquid 17 liquid 18
liquid 19 liquid 20 liquid 21 liquid 22 Surface layer thickness
(.mu.m) 20 20 20 20 20 20 20 20 Ultraviolet treatment -- -- -- --
-- -- -- -- Physical property evaluation Ra (.mu.m) 1.59 1.80 2.01
1.12 1.20 1.25 1.27 1.79 Universal hardness of surface of 3.3 3.4
3.5 3.1 3.2 3.1 3.4 3.4 surface layer (N/mm.sup.2) Martens hardness
of second convex 3.5 3.5 3.5 -- -- -- -- 3.5 of surface layer
(N/mm.sup.2) Volume resistivity of surface 2.50 .times. 10.sup.12
3.70 .times. 10.sup.12 5.20 .times. 10.sup.12 1.20 .times.
10.sup.12 1.90 .times. 10.sup.12 2.70 .times. 10.sup.12 4.30
.times. 10.sup.12 3.50 .times. 10.sup.12 layer (.OMEGA. cm) Average
inter-particle surface 39 38 37 36 35 29 24 39 distance of first
particles resulting in a first convex (nm) Image evaluation Dirt
evaluation A A B A A A A A Evaluation of amount of injection 6 5 4
8 7 5 4 6 charge (-V) Discharge property evaluation A A A B A A A A
Dirt evaluation 105% 8.8 9.2 10.5 8.3 8.5 8.8 8.7 10.6
(cleaner-less) 110% 4.9 4.8 5.3 4.9 4.7 4.8 4.6 5.2 Evaluation of
amount of 105% 18 17 14 19 20 19 19 14 injection charge
(cleaner-less) (-V) 110% 39 34 30 41 42 41 40 36
TABLE-US-00015 TABLE 9-4 Example 25 Example 26 Example 27 Example
28 Example 29 Example 30 No. of member for electrophotography 25 26
27 28 29 30 Rubber material of elastic layer CG102 CG102 CG102
CG102 CG102 CG102 Surface layer material Coating Coating liquid 24
Coating Coating liquid 26 Coating Coating liquid 28 liquid 23
liquid 25 liquid 27 Surface layer thickness (.mu.m) 20 20 20 20 20
20 Ultraviolet treatment -- -- -- -- -- -- Physical property
evaluation Ra (.mu.m) 1.80 2.10 1.81 1.81 1.27 2.33 Universal
hardness of surface of surface layer 3.5 6.1 3.4 4.8 4.7 6.8
(N/mm.sup.2) Martens hardness of second convex of surface 3.6 12.6
3.5 4.9 -- 15.1 layer (N/mm.sup.2) Volume resistivity of surface
layer (.OMEGA. cm) 4.30 .times. 10.sup.12 4.70 .times. 10.sup.12
5.20 .times. 10.sup.12 9.20 .times. 10.sup.13 6.80 .times.
10.sup.13 9.70 .times. 10.sup.13 Average inter-particle surface
distance of first 40 39 36 37 38 40 particles resulting in a first
convex (nm) Image evaluation Dirt evaluation A B A A A B Evaluation
of amount of injection charge (-V) 5 3 5 4 8 3 Discharge property
evaluation A A A A B A Dirt evaluation (cleaner-less) 105% 9.9 22.6
10.1 14.7 8.2 26.5 110% 5.2 13.8 4.8 8.2 5.2 19.1 Evaluation of
amount of injection charge 105% 16 12 15 18 18 14 (cleaner-less)
(-V) 110% 37 30 36 40 41 35
TABLE-US-00016 TABLE 9-5 Example 31 Example 32 Example 33 Example
34 Example 35 No. of member for electrophotography 31 32 33 34 35
Rubber material of elastic layer CG102 CG102 CG102 CG102 CG102
Surface layer material Coating liquid 29 Coating liquid 30 Coating
liquid 31 Coating liquid 33 Coating liquid 1 Surface layer
thickness (.mu.m) 20 20 20 20 20 Ultraviolet treatment -- -- -- --
Present Physical property evaluation Ra (.mu.m) 1.79 1.22 2.30 1.77
1.74 Universal hardness of surface of surface 3.1 4.0 6.3 2.4 3.4
layer (N/mm.sup.2) Martens hardness of second convex of 3.3 4.2
14.1 2.9 3.5 surface layer (N/mm.sup.2) Volume resistivity of
surface layer 3.40 .times. 10.sup.14 1.50 .times. 10.sup.14 3.30
.times. 10.sup.14 8.70 .times. 10.sup.8 5.80 .times. 10.sup.10
(.OMEGA. cm) Average inter-particle surface distance of 36 39 37 37
39 first particles resulting in a first convex (nm) Image
evaluation Dirt evaluation A A B B A Evaluation of amount of
injection charge 3 5 1 15 8 (-V) Discharge property evaluation A B
A A A Dirt evaluation (cleaner-less) 105% 8.8 8.7 24.5 29.5 6.9
110% 5.4 5.1 18.7 16.8 4.1 Evaluation of amount of injection 105%
11 9 9 48 18 charge (cleaner-less) (-V) 110% 33 26 30 121 41
TABLE-US-00017 TABLE 9-6 Example 36 Example 37 Example 38 Example
39 Example 40 No. of member for electrophotography 36 37 38 39 40
Rubber material of elastic layer CG102 CG102 Epion301 NBR Silicone
Surface layer material Coating liquid 16 Coating liquid 29 Coating
liquid 1 Coating liquid 1 Coating liquid 1 Surface layer thickness
(.mu.m) 20 20 20 20 20 Ultraviolet treatment Present Present -- --
-- Physical property evaluation Ra (.mu.m) 1.79 1.81 1.74 1.82 1.69
Universal hardness of surface of surface 3.5 3.1 3.1 6.3 2.1 layer
(N/mm.sup.2) Martens hardness of second convex of 3.6 3.2 3.3 6.5
2.6 surface layer (N/mm.sup.2) Volume resistivity of surface layer
3.50 .times. 10.sup.12 3.10 .times. 10.sup.14 4.90 .times.
10.sup.10 5.10 .times. 10.sup.10 5.30 .times. 10.sup.10 (.OMEGA.
cm) Average inter-particle surface distance of 36 36 36 40 39 first
particles resulting in a first convex (nm) Image evaluation Dirt
evaluation A A A B B Evaluation of amount of injection charge 6 4
12 2 4 (-V) Discharge property evaluation A A A B B Dirt evaluation
(cleaner-less) 105% 7.1 7.1 12.5 28.3 14.7 110% 3.9 4.3 6.8 20.2
9.9 Evaluation of amount of injection 105% 12 9 22 12 13 charge
(cleaner-less) (-V) 110% 38 24 48 38 35
Comparative Example 1
[0160] Member 41 for electrophotography was produced and evaluated
in the same way as in Example 1 except that the rubber particle as
the first particle were not added in the preparation of coating
liquid 1. The evaluation results are shown in Table 10.
Comparative Example 2
[0161] Member 42 for electrophotography was produced and evaluated
in the same way as in Example 1 except that coating liquid 32 was
used as the coating liquid. The evaluation results are shown in
Table 10.
Comparative Example 3
[0162] Member 43 for electrophotography was produced and evaluated
in the same way as in Example 1 except that 15 parts by mass of
titanium oxide (trade name: JR301, manufactured by TAYCA Corp.)
having a number-average particle diameter of 300 nm were added as
the first particle instead of the rubber particle in the
preparation of coating liquid 1. The evaluation results are shown
in Table 10. Fine asperities derived from filling with titanium
oxide were not formed on the surface of the member 43 for
electrophotography.
Comparative Example 4
[0163] Member 44 for electrophotography was produced and evaluated
in the same way as in Example 1 except that 60 parts by mass of
titanium oxide (trade name: JR301, manufactured by TAYCA Corp.)
having a number-average particle diameter of 300 nm were added as
the first particle instead of the rubber particle in the
preparation of coating liquid 1. The evaluation results are shown
in Table 10.
TABLE-US-00018 TABLE 10 Comparative Comparative Comparative
Comparative Example 1 Example 2 Example 3 Example 4 No. of member
for electrophotography 41 42 43 44 Rubber material of elastic layer
CG102 CG102 CG102 CG102 Surface layer material Coating Coating
Coating Coating liquid 1 liquid 32 liquid 1 liquid 1 Surface layer
thickness (.mu.m) 20 20 20 20 Ultraviolet treatment -- -- -- --
Physical property evaluation Ra (.mu.m) 1.75 1.92 1.82 1.91
Universal hardness of surface of surface layer 3.3 18.6 10.4 12.4
(N/mm.sup.2) Martens hardness of second convex of surface 3.4 16.1
8.2 10.9 layer (N/mm.sup.2) Volume resistivity of surface layer
(.OMEGA. cm) 6.00 .times. 10.sup.10 4.70 .times. 10.sup.12 6.50
.times. 10.sup.10 8.90 .times. 10.sup.10 Average inter-particle
surface distance of first -- 44 7699 576 particles resulting in a
first convex (nm) Image evaluation Dirt evaluation D C C C
Evaluation of amount of injection 5 2 8 7 charge (-V) Discharge
property evaluation A A A A Dirt evaluation (cleaner-less) 105%
42.3 62.5 52.6 61.5 110% 28.5 55.3 46.5 56.7 Evaluation of amount
of 105% 24 18 33 19 injection charge (cleaner- 110% 48 38 69 44
less) (-V)
[0164] 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.
[0165] This application claims the benefit of Japanese Patent
Application No. 2014-241883, filed Nov. 28, 2014, which is hereby
incorporated by reference herein in its entirety.
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