Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
13167~
1ELECTROPHOTOGRAPHIC PHOTORECEPTOR
5BACKGROUND OF THE INVENTION
(a) Industrlal Field oY the Inventlon
The present invention relates to an
electrophotographic photoreceptor. More speci~ically, the
present invention relates to an electrophotographic
photoreceptor which due to its ability o~ maintaining its
superior mechanical strength and outstanding
electrophotographic properties, i.e., characteristics
requlred in electrophotography, over a long period, can be
sultably utilized in a variety of application ~ields of
electrophotography.
, .
(b) Description of the Related Art
In recent Pields of electrophotography, the main
current of photoreceptors has been layered-type of organic
electrophotographic photoreceptors o~ which the
photosensitive layer contains at least two elementary
layers, a charge generation layer where charges are
generated by exposure and a charge transport layer where
transport o~ the potential occurs. In this sort o~
~.
.
1 3 1 674~
1 layered-type organic photoreceptors, a binder-resin is used
as a component o~ its charge transport layer and a
polycarbonate resin obtained by using bisphenol-A as a
starting monomer has been widely used as the binder-resin.
Polycarbonate resins made from blsphenol-A
generally have such advantageous characteristics that
because o~ their good compatlbility with charge
transporting materlals, they render the resulting
photoreceptors good electrical properties and high
mechanical strength.
However, it has been ~ound that problems,
including the ~ollowing problems (1)-(3), arise in the case
that the charge transport layer o~ a photoreceptor is
~ormed by using a polycarbonate resin made ~rom bisphenol-A
as the binder-resin.
(1) In preparatlon o~ a photQreceptor, whitening
(gelatlon) o~ a coating solution applied ~or ~orming the
charge transport layer tends to occur depending on the kind
of the solvent used ~or preparing the coatlng solution to
be applied, and the ~ormed charge transport layer tends to
crystallize easily. This crystallization causes quality
de~ects o~ the developed image since photo-induced
discharge hardly occurs on the crystallized regions of the
charge transport layer, leaving the residual charges which
cause an undesirable electric potentlal on the regions.
1 3 1 6744
1 (Z) Solvent-crack o~ the polYcarbonate resin derived
~rom bisphenol-A is o~ten caused ln the charge transport
layer by another solvent used ~or applying another layer
onto the charge transport layer. In other words, exposing
the once prepared charge transport layer with another
solvent greatly decreases the mechanical strength o~ the
charge transport layer. I~ the resulting photoreceptor ls
used by rotating ~or long time in a copying machine, the ?
charge transport layer will get cracked causing the
appearance o~ some crack-patterns on the resulting copied
articles.
(3) A charge transport layer ~ormed by uslng a
polycarbonate resin made ~rom bisphenol-A as its binder-
resin tends to be peeled o~ ~rom the base layer because o~
lts poor adhesion to the base layer. Consequently, the
resulting photoreceptor o~ten meets such a disadvantage
that lts li~e in practical use ~or copying ls short. The
base layer described above usually lndicates a charge
generation layer. However, it may indicate an electric
conductor in the case o~ a positively-charged-type
electrophotographic photoreceptor where a charge transport
layer and a charge generation layer are successively
laminated on an electric conductor in that order, or it may
be an intermedlate layer (such as a blocking layer, etc.)
in the case that the lntermediate layer is ~ormed between
131674~
1 an electric conductor and a charge transport layer or
between a charge generation layer and a charge transport
layer wlth aiming at lmprovlng electrophotographlc
propertles.
.
SUMMARY OF T~E INVENTION
The present invention has been per~ormed in view
o~ the above described situation, particularly ln pursuit
o~ means to remove the above described problems that may be
round ln the conventional electrophotographic
photoreceptors prepared by uslng a polycarbonate resin made
~rom bisphenol A as a binder-resin.
It is accordingly sn obJect o~ the present
invention to provide an electrophotographic photoreceptor
whlch~can be prepared without accompanying whitening o~
coating solutions comprising binder-reslns nor solvent-
crack o~ the layer ~ormed. and maintalns a superior
mechanical strength and outstanding electrophotographic
properties ~or a long period in practical use.
As the result o~ our researches, we have ~ound
that use oi a polycarbonate resin havlng a speci~ic
structure as a binder-resin in the photosensitive laYer~
especially the charge transport layer in the photosensitive
1 3 1 6 7 4 ~-r
1 layer, of an electrophotographic photoreceptor makes the
resulting photoreceptor ~ree ~rom the whltenlng (gelatlon)
o~ coating solutions or solvent-crack in preparation o~ the
photoreceptor, which maY be ~ound in the conventional
electrophotographlc photoreceptors prepared by using a
polycarbonate resin made ~rom bisphenol-A as a binder-
resln, and as well, enables the resulting photoreceptor to
malntaln lts superior mechanical strength and outstanding
electrophotographlc properties over a long perlod ln
practical use.
On the basis o~ the above descrlbed ~lndlngs, we
have completed the present invention.
Accordingly, the present invention provides an
electrophotographic photoreceptor comprising an
electroconductive substrate and a photosensltlve layer
disposed on one sur~ace o~ sald electroconductlve
substrate, wherein said photosensitive layer contalns a
blnder-resin comprising (A) a polycarbonate having the
repeating unit represented by the ~ollowlng general ~ormula
~ tI):
~ ,o
( ~ Xl ~ oc-t-- (I)
131674'-~
1 wherein IRl
Xl in the ~ormula [I~ is -C- , Rl and R~ each
R~
independently being hydrogen atom, an alkyl group
-- 5 having a carbon number of 1 to 6 or an aryl group
having a carbon number o~ 6 to 12,
C ~ , n being an integer o~ 4 to 10,
CH2 ~
-~C~ztff- , p being an lnteger o~ 2 to lO,
a single bond, -0-, -S-, -S0-, or -S02-;
or (B) a polycarbonate copolymer comprising both the
repeating unit represented by the general ~ormula (1) and
the repeating unit represented by the ~ollowing general
~ormula (II):
O
~ 11
-~--o ~ ~2 ~ oc-t-- (II)
(R3)~ (R~)m
wherein
R3 and R~ in the general ~ormula (II) each are
independently a halogen atom, an alkyl group having a
carbon number o~ 1 to 6 or cyclohexyl group;
k and m are each independently an integer o~ 0 to 4; and
the de~inition o~ X2 is the same as the definition of Xl
1 31 674 -,
1 in the general ~ormula (I) as described above, with
the proviso that Xl and X2 are ldentical with or
di~erent ~rom each other.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Some illustrative examples oY Rl and R2 ln the
R
lo -C- described above include hydrogen atom, methyl group,
R~
ethyl group, n-propyl group, isopropyl group, n-butyl
group, 1-methylpropyl group, 2-methylpropyl group, tert-
butyl group, n-pentyl group, isopentyl group, n-hexyl
group, isohexyl group, phenyl group, tolyl group, xylyl
group, trimethylphenyl group, ethylphenyl group, naphthyl
group, methylnaphthyl group, and biphenylyl group. Among
them, the especially pre~erred are methyl group, and phenyl
group. Where, Rl and R2 may be ldentical with or di~erent
~rom each other.
Examples o~ the especially pre~erred groups among
R CH3 H CH3
the -C- groups include -C-, -C-, and -C-.
~ 2 CH9 CH3
1 31 674 '-~
1 Some illustratlve examples o~ the ~ C ~ group
~ CHz ~
described above lnclude 1,1-cyclopentylidene group, 1,1-
cyclohexylidene group, and 1,1-cyclooctylidene group.
Among them, the especially pre~erred examples include 1,1-
cyclohexylldene group.
Some illustratlve examples o~ the -tCH2ts- group
include methylene group, dimethylene group, trimethylene ,
group, tetramethylene group, hexamethylene group,
octamethylene group, and decamethylene group. Among them,
the especially preferred examples lnclude dimethylene
~roup.
Some lllustratlve examples Or R and R~ include a
halogen atom, such as ~luorine atom, chlorine atom, and
bromine atom, methyl group, ethyl group, n-propyl group,
isopropyl group, n-butyl group, 1-methylpropyl ~roup, 2-
methylpropyl group, tert-butyl group, n-pentyl group,
isopentyl group, neopentyl group, n-hexyl group, and
isohexyl group. Where, R3 and R~ may be identical with or
di~erent ~rom each other. In addition, in the case that
the repeating unit represented by the ~ormula (II) has two
or more Rs ~roups, they can be the same or di~erent ~rom
one another, and i~ it has two or more R~ groups, they can
be the same or di~erent ~rom one another.
The above-described k and m each independently
131674~
1 are an integer o~ O to 4, and the especially pre~erred
example is k=m=O.
The polycarbonate (A) having the repeating unit
represented by the general formula (I) can be prepared, ~or
5 example, by the condensatlon polymerlzatlon o~ one or more
kinds o~ dihydric phenols represented by the ~ollowing
general ~ormula:
HO ~ X ~ H (I' )
wherein X1 is as de~ined above in the ~ormula (I);
with a carbonate precursor, such as phosgene, etc., in a
proper neutral polar solvent in the presence o~ a proper
acid acceptor.
Polycarbonate (A) can also be prepared by
transesteri~ication o~ a bisaryl carbonate with a dihydric
phenol (I' ).
On the other hand, the polycarbonate copolymer
(B) comprislng the repeating unit represented by the
general ~ormula (I) and the repeating unit represented by
the general ~ormula (II) can be prepared by condensation
polymerization of one or more kinds o~ the dihydric phenols
(I' ~ described above and one or more klnds o~ dihydric
131674~
1 phenols represented by the following general ~ormula:
H0 ~ X2 ~ OH (II' )
(R3)~ (R~)~
wherein X~, R3, R~, k, and m in the ~ormula (II' ) are
as de~ined above;
with a carbonate precursor, such as phosgene, etc., in a
proper neutral polar solvent in the presen¢e o~ a proper
acid acceptor.
Polycarbonate copolymer (B) can al~o be prep~red
by the transesteri~ication o~ a bisaryl carbonate with a
mixture o~ a dihydric phenol (I' ) and a dihydric phenol
(II' ).
Some illustrative examples o~ the dihydrlc phenol
(I' ) described above include
2,2-bis(3-phenyl-4-hydroxyphenylj propane,
1-phenyl-1,1-bis(3-phenyl-4-hydroxyphenyl)ethane,
1,1-bis(3-phenyl-4-hydroxyphenyl~cyclohexane,
3,3-bis(3-phenyl-4-hydroxyphenyl)pentane,
bis(3-phenyl-4-hydroxyphenyl)sul~one,
3,3' -diphenyl-4,4' -dihydroxybiphenyl,
bis(3-phenyl-4-hydroxyphenyl)methane,
1-phenyl-1,1-bis(3-phenyl-4-hydroxyphenyl)methane,
13167f~
11
bis(3-pheny1-4-hYdroxYphenYl)ethane.
1,2-bis(3-phenyl-4-hydroxyphenyl)ethane,
1,3-bis(3-phenyl-4-hYdroxyphenyl)propane,
2,2-bls(3-phenyl-4-hydroxyphenyl)butane,
1,4-bis(3-phenyl-4-hydroxyphenyl)butane,
1,1-bis(3-phenyl-4-hydroxyphenyl)-1-phenylbutane,
2,2-bls(3-phenyl-4-hydroxyphenyl)octane,
1,8-bis(3-phenyl-4-hydroxyphenyl)octane,
bis(3-phenyl-4-hydroxyphenyl~ether,
bis(3-phenyl-4-hydroxyphenyl)sul~lde, and
1,1-bis(3-phenyl-4-hydroxyphenyl)cyclopentane.
Among them, the especlally pre~erred examples
lnclude
2,2-bls(3-phenyl-4-hydroxyphenyl)propane,
lS 1-phenyl-1,1-bls(3-phenyl-4-hydroxyphenyl)ethane,
1,1-bis(3-phenyl-4-hydroxyphenyl)cyclohexane, and
bls(3-phenyl-4-hydroxyphenyl)sul~one.
Some lllustrative examples o~ the dlhydrlc phenol
(II' ) described above include
bis(4-hydroxyphenyl)methane,
1,1-bis(4-hydroxyphenyl)ethane,
1,2-bis(4-hydroxyphenyl)ethane,
2,2-bis(4-hydroxyphenyl)propane,
2,2-bis(3-methyl-4-hydroxyphenyl)butane,
2,2-bis(4-hydroxyphenyl)butane,
1 31 674~
12
1 2,2-bis(4-hydroxyphenYl)octane,
4,4-bls~4-hydroxyphenyl)heptane,
4,4' -dlhydroxytetraphenylmethane,
1,1-bis(4-hydroxyphenyl)-1-phenylethane,
~: 5 1,1-bis(4-hydroxyphenyl)-1-phenylmethane,
bls(4-hydroxyphenyl)ether,
bls(4-hydroxyphenyl)sul~ide,
bls(4-hydroxyphenyl)sul~one,
1,1-bis(4-hydroxyphenyl)cyclopentane,
1,1-bis(4-hydroxyphenyl)cyclohexane,
2,2-bis(3-methyl-4-hydroxyphenyl)propane,
2-(3-methyl-4-hydroxyphenyl)-2-~4-hydroxyphenyl)-1-
phenylethane,
bis(3-methyl-4-hydroxyphenyl)sul~lde,
bis(3-methYl-4-hYdroxYPhenyl)sulione~
bis(3-methyl-4-hydroxyphenyl)methane~
1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane,
4,4' -dlhydroxybiphenyl,
2,2-bis(2-methyl-4-hydroxyphenyl)propane,
1,1-bis(2-butyl-4-hydroxy-5-methylphenyl)butane,
1,1-bis(2-tert-butyl-4-hydroxy-3-methylphenyl)ethane,
1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)prop~ne,
1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)butane,
1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)lsobutane,
1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl~heptane,
1 3 1 67 4'~
1 1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)-1-
phenylmethane,
1,1-bis(2-tert-amyl-4-hydroxy-5-methylphenyl)butane,
bis(3-chloro-4-hydroxyphenyl)methane,
bls(3,5-dibromo-4-hydroxyphenyl)methane,
2,2-bls(3-chloro-4-hydroxyphenyl)propane,
2,2-bis(3-~luoro-4-hydroxyphenyl)propane,
2,2-bis(3-bromo-4-hydroxyphenyl)propane,
2,2-bis(3,5-di~luoro-4-hydroxyphenyl)propane,
2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane,
2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane,
2,2-bis(3-bromo-4-hydroxy-5-chlorophenyl)propane,
2,2-bis(3,5-dichloro-4-hydroxyphenyl)butane,
2,2-bis(3,5-dibromo-4-hydroxyphenyl)butane,
1,1-bis(3-~luoro-4-hydroxyphenyl)-1-phenylethane.
bls(3-~luoro-4-hydroxyphenyl)ether,
3,3' -di~luoro-4,4' -dihydroxybiphenyl, and
1,1-bis(3-cyclohexyl-4-hydroxyphenyl)cyclohexane. Among
them, the especially preferred examples include 2,2-bis(4-
hydroxyphenyl)propane.
The abo~e-described acid acceptor can be selected
~rom various kinds o~ acld acceptors including known ones.
Examples of the acid acceptor which may be used include an
alkaline metal hydroxlde, such as sodium hydroxide and
potassium hydroxide, an organic base, such as pyridine, and
1 31 614~
1 a mixture thereo~.
Examples o~ the solvent which may be used include
methylene chloride, chlorobenzene, and xylenes.
It is desirable to carry out the reaction in the
presence o~ a catslyst and a molecular welght regulator ln
order to accelerate the condensation polymerization and to
adJust the degree of polymerlzatlon.
Examples o~ the catalyst which may be used
include a tertlary amlne, such as triethyl amine and a
quarternary ammonium salt.
Examples o~ the molecular weight regulator which
may be used include p-t-butyl phenol and phenyl phenol.
A small amount Or an antioxldant, such.as sodium
sulfite and sodium hydrosul~ite, may be added to the
polycarbonate or the polycarbonate copolymer used in the
present lnvention, as occasion demands.
The reaction ti.e., the condensation
polymerization) is conducted at a temperature in the range
usually of O to 150 C , pre~erably o~ 5 to 40 C . The
reaction is carried out usually for 0.5 min to 10 hr,
pre~erably ~or 1 min to 2 hr, although the period o~ the
reactlon depends on the reaction temperature employed. In
addition, it is desirable to keep the pH value of the
reaction system at not less than 10 during the reaction.
On the other hand, i~ the transesteri~ication
131674~
1 descrlbed above is employed ln the preparation oi the
polycarbonate or the polycarbonate copolymer, the above
descr1bed dihydric phenol compound(s) and a bisaryl
carbonate will be mlxed, and allowed to react one another
at an elevated temperature under a reduced pressure. This
reaction is conducted at a temperature in the range usually
o~ 150 ~o 350 C , pre~erably o~ 200 to 300 ~C . It ls
pre~erable to reduce the reaction pressure ~inally to not
higher than 1 mmHg, so that the phenolts) derived by the
transesterlfication from the bisaryl carbonate can be
removed out ~rom the reaction system. The reaction (the
transesteriflcation) is carrled out usually ~or about 1 to
4 hr, although the period of the reaction depends on the
reaction conditions employed, lncludlng the reaction
temperature and the degree o~ the reduction o~ the
pressure, and the like. It is pre~erred that this reaction
is conducted under an atmosphere o~ an inert gas, such as
nitrogen, and argon. It ls posqible to carry out the
reactlon in the presence o~ additives, such as the
molecular weight regulator, the antioxidant, etc.,
described above.
The polycarbonate (A~ and the polycarbonate
copolymer (~) which may be suitably used in the
photosensitive layer o~ the electrophotographic
photoreceptor oi the present lnvention are those havin~ a
1 3 1 6 7 4 ~
16
1 reduced viscosity [~ ,v/C~ o~ usually not less than 0.25
dl/g, pre~erably 0.3 to 4.0 dl/~ as measured ln methylene
chloride at a concentratlon o~ 0.5 g/dl at 20 C .
The polycarbonate (A) to be used in the present
invention may be a homopolymer comprising a slngle kind of
the repeatlng unit represented by the above described
~ormula (I), or a copolymer comprising two or more kinds o~
(I) at any ratio. These polycarbonates (A) may be used
individually or in an any ratio of combination o~ two or
more kinds o~ them, such as in a ~orm o~ a mixture thereo~.
The polycarbonate copolymer (B) to be used in the
present invention is a copolymer comprising one or more
kinds o~ the repeatlng unit represented by the ~ormula (I)
and one or more kinds o~ the repeating unit represented by
the ~ormula ~II). The ratio o~ the repeatlng units, (I) to
(II), in the polycarbonate copolymer (B) is not necessarily
speci~ied in the present invention. However, it is
suitable that the polycarbonate copolymer (II) has a
content o~ the repeating unit (I) o~ not less than 1 mol%,
pre~erably not less than 5 mol% based on the total content
o~ the repeating units (I) and (II). These polycarbonate
copolymers (B) may be used individually or ln an any ratio
o~ combination of two or more kinds of them, such as in a
~orm o~ a mixture thereof.
In addition, it is also possible to use one or
1 -~ 1 h -14 l~r
1 more klnds o~ the polycarbonates (A) together with one or
more kinds o~ the polycarbonate copolymers (B) as a mixture
thereo~ or the llke.
Furthermore, the polycarbonate (A) and/or the
polycarbonate copolymer (B) may also be used together wi~h
known blnder-resins, including other known polycarbonates,
and the like, wlth or wlthout mixing them, as ~ar as the
ob~ect o~ the present invention is stlll su~lciently
attained.
The pre~erred embodiment o~ the
electrophotographic photoreceptor o~ the present invention
comprises a photosensitive layer disposed on one sur~ac'e o~
an electroconductive substrate, wherein the photosensitive
layer is a laminated layer comprising a charge generation
layer and a charge transport layer. The charge transport
layer may be disposed on the charge generation layer with
the charge generation layer sandwlched between the charge
transport layer and the electroconductive substrate, or the
charge generation layer may be disposed on the charge
transport layer with the charge transport layer sandwiched
between the charge generation layer and the
electroconductive substrate. The electrophotographic
photoreceptor o~ the present invention may ~urther have an
electroconductive or insulating protective ~ilm ~ormed on
its sur~ace at need. Furthermore, it may have one or more
13167~l~
18
1 intermediate laYers~ such as a blocking layer whlch is
e~ective ~or blockin~ the recombination o~ the charges
generated, or one or more adhe~lon layers ~or improving the
adhesive force between the layers therein, or the like.
The electrophotographic photoreceptor o~ the
present invention contains a binder-resln comprlslng at
least the polycarbonate (A) or the polycarbonate copolymer
(B), ln the photosensitlve layer, pre~erably in the charge
transport layer of the photosensitive layer.
The electroconductive substrate to be used in the
electrophotographic photoreceptor o~ the present invention
may be selected ~rom a various kinds o~ electroconductive
substrates, including known ones and the like. Some
illustrative examples o~ the electroconductlve substrate
which may be used ln the present inventlon include a plate .
or sheet made o~ a metal, such as aluminum, brass, copper,
nickel, steel, etc., a coductivity-introduced or
conductive-layer-containing substrate obtained by giving a
treatment ~or introduclng electric conductivity or by
laminating an electroconductive layer to a non or poor-
conductive substrate, such as a glass plate, plastic sheet,
cloth, paper, a black-sheet, etc.,; e~g., an
electroconductive substrate prepared by depositing,
spattering or applying a conductive material, such as
aluminum, nickel, chromium, palladium or graphite, to the
1 31 674~
19
1 non or poor-conductlve substrate described above.
The charge generatlon layer to be used in the
present invention comprises at least a charge generatin~
material. The charge generation layer in the
electrophotographic photoreceptor of the present invention
can be prepared by mlxing and blndlng a charge genarating
material with a binder-resin to ~orm a layer on a base
layer, such as the electroconductive layer. Various kinds
of methods ~or forming a charge generation layer including
known methods may be employed in the present invention.
For instance, the charge generation layer may pre~erably be
~ormed by applying a coatlng liquid obtained by dissolving
or suspending a charge generating material together with a
binder-resin ln a suitable solvent onto a base layer,
~ollowed by drying.
The charge generating materlal which maY be used
ln the charge generation layer can be selected ~rom a
various kinds o~ organlc or inorganic charge generating
materials, includlng known ones and the like. Examples o~
the charge generating material which may be used include a
simple substance o~ selenium, such as non-crystalline
selenium and crystalllne selenlum o~ a trlgonal system, a
selenium-based alloy, such as a selenium-tellurium alloy, a
selenide, such as As2Se3, a selenium-containing
composltion, zinc oxide, an lnorganic material comprlsing
1 3 1 6 1 4 ~
1 an element o~ the group II and tha~ o~ the group IV ln the
periodic table, such as CdS-Se, and oxide semiconductor,
such as titanium oxide, a silicon-based material, such as
amorphous silicon, a phthalocyanine, a metal complex o~ a
phthalocyanine, cyanine, anthracene, pyrene, perylene, a
pyrylium salt, a thiapyrylium salt, polyvinyl carbazole, a
squarelium pigment, and the like.
They may be used individually or in a combination
o~ two or more kinds thereo~, ~or example in a ~orm o~ a
mixture thereo~.
The binder-resln which may be used in the charge-
generatlon layer is not especially speci~ied in the present
invention. This can be selected ~rom a various kinds o~
binder-resins, including known ones. Examples o~ the
binder-resln which may be used in the charge generation
layer include thermoplastic resins, such as polystyrene,
polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl
acetate copolymer, polyvinyl acetal, alkyd resins, acrylic
resins, polyacrylonitrlle, polycarbonates, polyamides,
polyketones, polyacrylamides, polybutyral resins, and
polyesters, thermosetting reslns, such as polyurethanes,
epoxy resins, and phenol resins.
The above described polycarbonates lA) andtor
polycarbonate copolymers (B) can also be used ~or the
blnder-resin in the charge generation layer.
1 3 1 674 ~
21
1 These binder-resins can be used individually or
ln a combination o~ two or more klnds thereo~ with or
without mixing them, ~or example, in a ~orm o~ a mixture
thereo~, in the charge generation layer.
The charge transport layer in the
electrophotographic photoreceptor o~ the present invention
may be prepared by mlxing and blnding a charge transporting
materlal with a binder-resin to ~orm into a layer on a base
layer. The char~e transport layer can be ~ormed by using
various techniques, including known ones. For in~tance, it
can pre~erably be iormed by applyin~ a coating liquld
obtained by dissolving or suspending a charge transporting
material together with a binder-resin in a suitable solvent
onto a base layer, ~ollowed by drying.
Wherein, at least the above described
polycarbonate (~) or polycarbonate copolymer (B) should be
used as a binder-resin in the photosensitive layer o~ the
electrophotographic photoreceptor o~ the present invention.
As ~ar as the polycarbonate (A) or polycarbonate copolymer
(B) is used as a blnder-resin ln the photosensitive layer,
it is not necessary to use the above described
polycarbonate (A) or polycarbonate copolymer (B) as the
binder-resin ln the charge transport layer o~ the
photosensitive layer ln the present lnventlon. Howeverl lt
is desirable to use the polycarbonate (A) and/or
131674~
1 polycarbonate copolymer (B) as a binder-resin in the charge
transport layer in the present invention.
The charge transporting material to be used in
the charge transport layer can be selected ~rom
- 5 conventionally used ones, including electron transporting
materials and positive hole transporting materials.
Examples o* the electron transporting material
include electron withdra~ing compounds, such as chloranil,
bromanil, tetracyanoethylene, tetracyanoquinodimethane,
2,4,7-trinitro-9-~luorenone, 2,4,5,7-tetranitro-9-
~luorenone, 2,4,7-trinitro-9-dicyanomethylene~luorenone,
2,4,5,7-tetranltroxanthone, and 2,4,9-trinitrothioxanthone,
and high molecular materials prepared there~rom. These
electron transporting materials can be used lndlvidually or
in a combination o~ two or more kinds thereo~, ~or examples
ln a ~orm o~ a mixture thereo~.
Examples o~ the po~itive hole transporting
material include pyrenes, N-ethylcarbazole, N-
isopropylcarbazole,
N-methyl N-phenylhydrazino-3-methylidene-9-ethylcarbazole,
N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole,
N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine,
N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine,
hydrazones, such as
~5 p-diethylaminobenzaldehyde-N,N-diphenylhydrazone,
1 31 674~-r
1 p~diethylaminobenzaldehyde-N-a -naphthyl-N-phenylhYdrazone,
p-pyrrolizinobenzaldehyde-N,N-diphenylhydrazone,
1,3,3-trimethylindolenine-~ -aldehyde-N,N-
diphenylhydrazone, and
p-dimethylbenzaldehyde-3-methylbenzthiazolinone-2-
hydrazone,
2,5-bis(p-diethylaminophenyl)-1,3,4-oxaziazole,
pyrazollnes, such as
1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-
pyrazoline,
l-[qulnoryl(2)]-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline,
1-[lepidyl(2)]-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazollne,
1-[6-methoxy-pyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazollne,
1-[pyridyl(5)]-3-(p-diethylaminophenyl)pyrazoline,
1-[pyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline,
1-[pyridyl(2)]-3-(p-diethylaminostyryl)-4-methyl-5-(p-
diethylaminophenyl)pyrazoline,
1-[pyridyl(2)]-3-(a -methyl-p-diethylaminostyryl)-4-methyl-
5-(p-diethylaminophenyl)pyrazoline,
1-phenyl-3-(p-diethylaminostyryl~-4-methyl-5-(p-
diethylaminophenyl)pyrazoline,
1 31 674~
24
1 1-phenyl-3-(a -benzyl p-diethylaminostYryl)-5-(p-
diethylaminophenyl)pyrazollne, and
spiropyrazoline,
oxazoles, such as
2-(p-dlethylaminostyryl)-~ -diethylaminobenzoxazole and
2-(p-diethylaminophenyl)-4-(p-dlmethylamlnophenyl)-5-(2-
chlorophenyl)oxazole,
thiazole compounds, such as
2-(p-diethy].aminostyryll-6-diethylaminobenzthiazole,
triarylmethane derivatives, such as
bis(4-diethylamino-2-methylphenyl)phenylmethane,
(polyaryl)amines, such as
1,1-bis(4-N,N-diethylamino-2-methylphenyl)heptane and
1,1,2,2-tetrakis~4-N,N-dimethylamlno-2-methylphenyl)ethane,
benzidine.compounds. such as
N,N' -diphenyl-N,N' -bis(methylphenyl)benzldine,
N,N' -diphenyl-N,N' -bis(ethylphenyl)benzidine,
N,N' diphenyl-N,N' -bis(propylphenyl)benzidine,
N,N' -diphenyl-N,N' -bis(butylphenyl)benzidine,
N,N' -diphenyl-N,N' -bis(isopropylphenyl)benzidine,
N,N' -diphenyl-N,N' -bis(sec-butylphenyl)benzidine,
N,N' -diphenyl-N,N' -bis(tert-butylphenyl)benzidine, and
N,N' -diphenyl-N,N' -bis(chlorophenyl)benzidine,
triphenylamine, poly(N-vinyl carbazole), poly(vlnylpyrene),
poly(vinylanth~acene), poly(vinylacridine),
1 31 67~4
poly(9-vinylphenylanthracene), pyrene-~ormaldehyde resins
and ethylcarbazole-~ormaldehyde resins.
These materials may be used individually or in a
combination o~ two or more klnds thereo~, ~or examples, in
a ~orm o~ a mlxture thereo~.
Examples o~ the solvent which may be used in
~orming the charge generation layer or the charge transport
layer include aromatlc solvents, such as benzene, toluene,
xylenes, and chlorobenzene, ketones, such as acetone,
methyl ethyl ketone and cyclohexanone, alcohols, such as
methanol, ethanol, and lsopropyl alcohol, esters, such as
ethyl acetate and ethyl cellosolves, halogenated
hydrocarbons, such as tetrachloromethane,
tetrabromomethane, chloro~orm, dlchloromethane, and
tetrachloroethane, ethers such as tetrahydro~uran and
dioxane, dimethyl~ormamide, dimethyl sul~oxide,
diethyl~ormamide, and the like.
These solvents may be used individually or in a
~orm o~ a mixed solvent in combination of two or more kinds
thereo~.
In preparatlon o~ the electrophotographic
photoreceptor o~ the present inventlon, the applications o~
the coating llquids in ~orming the respective layers may be
performed by using a variety o~ application devices,
including known ones. Examples o~ the application devices
1 31 674~,
1 whlch may be used include applicators, spray coaters, bar
coaters, dip coaters, roll coaters, and doctor blade.
The ~ollowing examples are set ~orth to more
~ully and clearly illustrate the present invention and are
intended to be, and should be construed as being. exemplary
and not limitatlve of the lnvention.
EXAMPLES 1 T0 9 AND COMPARATIVE EXAMPLES 1
EXAMPLE 1
To a 1-llter ~lask introduced were a solutlon
obtalned by dissolvlng 95 g (0.25 mol) o~ 2,2-bls(3-phenyl-
4-hydroxyphenyl)propane in 600 ml o~ 3 N-aqueous solution
o~ potassium hydroxide and 250 ml o~ methylene chlorlde,
and phosgene was charged into the ~lask by bubbling lt into
the resulting mixture at a ~eed rate o~ 340 ml/min. ~or 30
min. while the temperature o~ the mixture being maintained
around 10 C by cooling ~rom the outside o~ the ~lask.
Polymerization was started by adding 0.7 g o~ p-
tert-butylphenol and 2 ml of 0.5 M-aqueous solution o~
triethylamine, and was continued ~or 1 hr. with good
stlrring. A~ter concluslon o~ the reaction, the organic
phase was separated ~rom the resulting reactlon mixture and
was diluted with 50~ ml o~ methylene chloride. The diluted
131674~
1 organic phase was successively washed with water. dlluted
hydrochlorlc acid, and water in that order and then was
introduced into methanol to obtaln an intsnded
polycarbonate. Thus obtained polymer had a reduced
vlscosity [~ .~/C] o~ 0.61 dl/g as measured in methylene
chloride at a concentratlon o~ o~ 0.5 g/dl at 20 C , and
had a Tg o~ 145 C . From the result o~ lH-NMR spectrum
analysis, lt was con~irmed that the polymer is a
polycarbonate comprising the ~ollowing repeating unit. ;r
~ CH3 0
~0~ 1 ~OC~
CH3 ~
A solution o~ a mixture comprlsing 50 % by weight
o~ the above prepared polycarbonate and 50 % b,y welght o~
the hydrazone compound as the charge transportlng material
represented by the ~ollowin~ ~ormula:
hydrazone compound:
- CH=N-N
C~H~
1 3 1 674~
1 ln tetrahydro~uran was prepared, wherein the content o~ the
mixture o~ the polycarbonate and hydrazon compound ln the
solution was 10 % by welght.
Neither whitening nor gelation o-~ the above
prepared solutlon (coating liquid) occurred and no other
problems arouse even when thls coating liquid was allowed
to stand ~or ten months.
A laminated-type electrophotographic
photoreceptor was prepared by applying the coating liquid
by a dip coating method to a charge generation layer
containing the dis-azo pigment compound represented by the
~ollowing ~ormula:
dis-azo compound
NHCO OH HO CONH
Cl ~ N3N ~ N-N ~ Cl
O
and having a thickness o~ about 0.5 ~ m which had been
~ormed on a electroconductive substrate made o~ aluminum,
~ollowed by drying to ~orm a charge transport layer having
a thickness o~ 20 ~ m on the charge generation layer. No
crystalliæation of the materials of the charge transport
131674~3,
29
1 layer was ~ound in this application course. In addition,
evaluation o~ the electrophotographic propertie~ o~ the
obtained electrophotographlc photoreceptor was conducted by
uslng a static charging testing device produced by
Kawaguchi Denki Selsaku-sho Co., Ltd. A~ter per~ormlng a
corona electrical charging at - 6 kV, the lnltial sur~ace
potentlal, the resldual potential a~ter llgh~ lrradlation
o~ 10 Lux, the hal~ decay exposure were measured. The
results are shown in Table 1. Furthermore, the sur~ace
hardness o~ the charge transport layer was the degree o~ H
(as measured by the pencil hardness test according ~o JIS-
K-5400).
EXAMPLE 2
The procedure o~ the preparation o~ the polymer
in Example 1 was exactly repeated, except that 95 g (0.25 ,
mol) o~ 2,2-bls(3-phenyl-4-hydroxyphenyl)propane was
replaced by a mixture o~ 76 g tO.2 mol) o~ 2,2-bis(3-
phenyl-4-hydroxyphenyl)propane and 11.4 g (0.05 mol) o~
2,2-bis(4-hydroxyphenyl)propane. There was obtained a
polycarbonate copolymer ([~ ,~/C] = 0.58 dl/g, Tg = 146 C )
comprising the ~ollowing repeating unit~:
131674~
1 ~ CH3 0 CH3 0
I ~ 0 . 8 ~~~1 ~0 i ~
CH3 ~ CH3
A laminated-type electrophotographlc
photoreceptor was prepared by the same procedure as
described in Example 1. except that the obtained
polycarbonate copolymer was replaced by the above prepared -
polycarbonate copolymer. The electrophotographic
properties o~ the obtained electrophotographic
photoreceptor are shown in Table 1. The evaluation results
wlth regard to the stability o~ the coating liquid,
crystallization at the time o~ appllcation, and sur~ace
hardness were similar to those Or Example 1.
EXAMPLE 3
The procedure oi the preparation o~ the polymer
ln Example 1 was exactly repeated, except that the 2,2-
bis(3-phenyl-4-hydroxyphenyl)propane was replaced by a
mixture of 77 g tO.174 mol) o~ 1-phenyl-1,1-bis(3-phenyl-4-
hydroxyphenyl)ethane and 16.5 g (0.076 mol) o~ bis(4-
hydroxyphenyl)sul~one~ There was obtained a polycarbonate
copolymer ([~ .p/C] = 0.53 dl~, Tg = 172 C ) comprising
the ~ollowing repeating units:
1 31 67~ 1~
1 ~ CH3 0
_~_o ~ ~ ~ C-t-0.7 _~_o ~ SZ ~ oc-t-o 3
A laminated-type electrophotographic
-~- S photoreceptor was prepared by the same procedure as
described in Example 1, except that the obtalned
polycarbonate copolymer was replaced by the above prepared
polycarbonate copolymer. The electrophotographic
properties of the obtained electrophotographic
photoreceptor are shown in Table 1. The evaluation results
with regard to the stability o~ the costing liquid,
crystallization at the time o~ application, and sur~ace
hardness were similar to those o~ Example 1.
EXAMPLE 4
The procedure o~ the preparation o~ the polymer
in Example 1 was exactly repeated, except that the 2,2-
bis(3-phenyl-4-hydroxyphenyl)propane was replaced by a
mixture o~ 76 g (0.2 mol) o~ 2,2-bis(3-phenyl-4-
hydroxyphenyl)propane and 21.6 g (0.05 mol) of 1,1-bis(3-
cyclohexyl-4-hydroxyphenyl)cyclohexane. There was obtained
a polycarbonate copolymer ([n ~/C] = 0.59 dl/g, Tg = 156
C ) comprising the ~ollowing repeating units:
13167~
1 ~ CH3 0 ~ ~ 0
-t-O I ~ OC-t- ~~~ ~ o.2
CH3 ~ ~
A lamina~ed-type electropho~ographic
photoreceptor was prepared by the same procedure as
descrlbed ln Example 1. except that the obtained
polycarbonate copolymer was replaced by the above prepared
polycarbonate copolymer. The electrophotographic
properties o~ the obtained electrophotographic
photoreceptor are shown ln Table 1. The evaluation results
with regard to the stability o~ the coating liquid,
crystallizatlon at the tlme o~ application, and sur~ace
hardness were similar to those o~ Example 1.
EXAMPLE 5
The procedure o~ the preparatlon o~ the polymer
in Example 1 was exactly repeated, except that the 2,2-
bis(3-phenyl-4-hydroxYphenYl)propane was replaced by 105 g
(0.25 mol) of 1,1-bls(3-phenyl-4-hydroxyphenyl)cyclohexane.
There was obtained a polycarbonate ([~ ~p/C] = 0.59 dl/g,
Tg - 156 C ) comprising the ~ollowing repeatlng unit:
13167~
33
o
~0~0~
A laminated-type electrophotographic
photoreceptor was prepared by the same procedure as
described in Example 1, except that the obtained
polycarbonate copolymer was replaced by the above prepared.
polycarbonate copolymer. The electrophotographic
properties o~ the obtained electrophotographic
photoreceptor are shown in Table 1. The evaluation results
with regard to the stability o~ the coating liquid,
crystalllzation at the time o~ applicatlon, and surface
hardness were similar to those o~ Example 1.
EXAMPLE 6
The procedure o~ the preparation o~ the polymer
in Example 1 was exactly repeated, except that the 2,2-
bis(3-phenyl-4-hydroxyphenyl)propane was replaced by a
mixture o~ 84 g (0.2 mol) o~ 1,1-bis(3-phenyl-4-
hydroxyphenyl)cyclohexane and 18 g (0.05 mol) of 4,4' -
dihydroxytetraphenylmethane. There was obtained a
polycarbonate copolymer l[n Op/C] = 0.62 dl/g, Tg = 167 C )
comprising the ~ollowlng repeating units:
1316741l~
34
~3~ ~o~(c~oll~
A laminated-type electrophotographic
photoreceptor was prepared by the same procedure as
described In Example 1, except that the obtained
polycarbonate copolymer was replaced by the above prepared
polycarbonate copolymer. The electrophotographlc
properties of the obtained electrophotographic
photoreceptor are shown ln Table 1. The evaluation results
with regard to the stability o~ the coating liquid,
crystall~zation at the time o~ application, and sur~ace
hardness were similar to those o~ Example 1.
EXAMPLE 7
The procedure o~ the preparation o~ the polymer
in Example 1 was exactly repeated, except that the 2,2-
bis(3-phenyl-4-hydroxyphenyl)propane was replaced by a
mixture o~ 50 g (0.125 mol) o~ bis(3-phenyl-4-
hydroxyphenyl)sul~one and 32 g (0.125 mol) o~ 2,2-bis~3-
methyl-4-hydroxyphenyl)propane. There was obtained a
polycarbonate copolymer ([~ ~D/C] = 0.83 dltg. Tg = 148 C )
comprising the ~ollowing repeating units:
1 31 ~7~t
<~ OCH3 CH3 0
~,5 t-O~I~OC~.5
~> CHa CH3
~ lamlnated-type electrophotographic
photoreceptor was prepared by the same procedure as
descrlbed in Example l, except that the obtained
polycarbonate copolymer was rePlaced bY the above prepared
polycarbonate copolymer. The electrophotographic
properties o~ the obtained electrophotographic
photoreceptor are shown in Table 1. The evaluation results
with regard to the stability oi the coating liquld,
crystallization at the tlme oi appllcatlon, and surface
hardness were similar to those o~ Example 1.
EXAMPLE 8
The procedure o~ the preparation of the polymer
in Example 1 was exactly repeated, except that the 2,2-
bls(3-phenyl-4-hydroxyphenyl)propane was replaced by a
mixture o~ 32g (0.076 mol) oY 1,1-bis(3-phenyl-4-
hydroxyphenyl)cyclohexane and 40 g (Q.174 mol) o~ 2,2
bis(4-hydroxyphenyl)propane. There was obtalned a
polycarbonate copolymer ([~ ,p/C] = 1.13 dl/g, Tg - 150 ~ )
comprising the ~ollowlng repeating units:
131674ll,
36
~) O CHa O
(--0~0~ ~O~C~OII~
~ ~ CH3
A laminated-type electrophotographic
- photoreceptor was prepared by the same procedure as
described in Example 1, except that the obtained
polycarbonate copolymer was replaced by the above prepared
polycarbonate copolymer. The electrophotographic
propertles o~ the obtalned electrophotographic
photoreceptor are shown in Table 1. The evaluatlon results
with reFard to the stabillty o~ the coating liquid,
crystallization at the tlme o~ application, and sur~ace
hardness were similar to those o~ Example 1.
EXAMPLE 9
The procedure o~ the preparation o~ the polymer
in Example 1 was exactly repeated, except that the 2,2-
bis(3-phenyl-4-hYdroxYphenYl)PrOPane was replaced by a
mixture o~ 4.8 g (0.0125 mol) o~ 2,2-bis(3-phenyl-4-
hydroxyphenyl)propane and 54 g t0.238 mol) o~ 2,2-bis(4-
hydroxyphenyl)propane. There was obtained a polycarbonate
copolymer t[~ ~p/C] = 1.47 dl/g, Tg = 148 C ) comprising
the ~ollowing repeating units:
1 3 1 6 7 4 ir
<~> CH3 CH3 0
. 05 ~~
C:EI9 ~> CH3
A laminated-type electrophotographic
photoreceptor was prepared by the same procedure as
described in Example 1, except that the obtalned
polycarbonate copolymer was replaced by the above prepared
polycarbonate copolymer. The electrophotographic .
properties o~ the obtained electrophotographic
photoreceptor are shown in Table 1. The evaluation results
wlth regard to the stability o~ the coating liquid,
crystallization at the tlme o~ application, and sur~ace
hardness wère similar to those o~ Example 1.
COMPARATIVE EXAMPLE 1
The procedure o~ the preparation o~ the polymer
in Example 1 was exactly repeated, except that the 2,2-
bis(3-phenyl-4-hydroxyphenyl)propane was replaced by 57 g
(0.25 mol) o~ 2,2-bis(4-hydroxyphenyl)propane. There was
obtained a polycarbonate ([~ ~/C] = 0.62 dl/g, Tg = 148 C
) comprising the following repeating unit:
1 31 6744
38
1 CH3 0
~0~1 ~0~
CH3
It was tried to prepare a laminated-type
electrophotographlc photoreceptor by using the same
procedure as described in Example 1, except that the
polycarbonate used in Example 1 was replaced by the above
polycarbonate. ~ ,
As the result, the prepared coating liquid was
whitened with the occurrence o~ its gelation in two days.
In additlon, at the time o~ application o~ the coating
liquid, crystallization (whitening) o~ some parts o~ the
~ormed charge transport layer was observed. Furthermore,
the sur~ace hardness o~ the ~ormed charge transport layer
was the degree o~ B in the pencil hardness scale.
1 31 674 ~
39
; = O O ~ o O D r- c-- C 1 ~
~,
C~
_.~ D~
. ~
, . . ..
. .
~ c~ X a~ ~ -
a~
. ~ ~ ~ X $ X X X ~ ~ X
