Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
(1) Field of the Invention:
The present invention relates to a photoconductive
composition for electrophotography. More specifically,
the invention relates to a photoconductive composition
which is suitable for the electrophotographic process
of the type where the surface of a photoconductive layer
is charged and exposed imagewise to actinic radiation
to form a charged electrostatic latent image, the so
formed latent image is developed with toner particles,
the resulting toner image is transferred on a transfer
sheet and these photocopying steps are conducted
repeatedly.
The present invention provides a photoconductive
composition for electrophotography, which comprises an
organic polymeric photoconductor having an electron-
donating property, an electron-accepting aromatic
polycyclic compound having at least one nitro-nuclear
substituent, in an amount of 0.15 to 0.45 mole per mole
of the constituent monomer of said organic polymeric
photoconductor and phthalocyanine or a derivative thereof
in an amount of 0.2 to 4% by weight based on said organic
polymeric photoconductor,
(2) Description of the Prior Art:
In the art of electrophotography, there i5 ~roadly
adopted ~ process in which a photosensitive material
having a photoconductive layer i~ electrically charged
~y corona discharge or the li~e n~eans, the photosensi-
tive material is then expDsed imagewise to actinic
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radiation to for~n an electrostatic late.nt image on the
surface of the phot ~ onductive layer9 a developer is
applied to the surface of the photoconductive la-~er to
form a toner image corresponding to the electrostatic
latent image and the toner image on the surface of the
photoconductive layer is transferred to a copy sheet.
In this process9 after transfer of the toner image,
the photose.nsitive material. is subjected to the cleaning
step for removing the residual toner therefrom9 a.nd the
photOsensitive material ~s then fed to the series of
the above-me.ntioned steps a~ain.
In order to form an image having high density a.nd
contrast, the photoconductive layer of a photosensit-ve
material to be used for this eLectrophotogr~phic process
is required to haYe the following characteristics in
pri.nciple. Namely9 the photoconductive layer ca.n be
charged at a sufficiently high potential by the above-
mentioned corona discharge ( i.n other words9 the
photoco.nductive layer should have a high saturation
charge voltage ). Further~ abrupt decrease of the
potential is caused when the photoconductive layer is
exposed tv actinic radiation after the above charging
treatment ( in other words9 the photoconductiVe layer
should h~Ve a high Ligh~-decay speed ~f the potential9
i e.9 a high se~sitivity ).
A ph~tosensltlve material to be used repeatedly
i,n the above-men~ioned e~ectrophotographio process 7 5
re~uired to have several ohara~te~istios ~hat are not
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required of a photosensitive material of the type where
a toner is directly fixed to a photosensitive layer. In
order to prevent fogging in repeati.ng the copying
operation and prolong the life of the photosensitive
material9 the former photosensitive material should
have a relatively quick dark decay characteristic ( the
property th~t the surface pote,n+ial in the unexposed
area of the photosensitive layer ~uickly decays in the
dark ) and have such a small residual pote.ntial as can
be neglected ( the property that the potential left in
the exposed area of the photose.nsitive layer is small ).
When the residllal potential of the photosensitive material
s large~ foggi.ng is already caused at the tra,nsfer
step, and in this case or whe,n the dark decay speed of
the photosensitive materi~l is low9 the static charge
of the electrostatic latent image formed on the surface
of the photosensitive m~terial is left after the transfer
.nd clea.ning step, a.nd the static charge is gradually
~.ccumulated to cause foggi,ng ln the copying operatiOn
of the suksequent cycle or cause electric degradatiOn
of the photoconductive Layer, Moreover~ whe,n the dark
decay speed is low9 eve,n after the tra.nsfer step the
toner particles are electrostatically attracted to the
sur~ce of the photosensitive material by a relatively
2~ strong attracting force and therefore~ the effiCie~Cy
o~` the transfer of the ~oner on a copy sheet is relatively
low a.nd a stro.ng wi.pi.ng operati,on should be conducted
to remove the residual toner from the surface o~ the
~2 7900
photosensitive material, resulting in a disadva.ntage
that the surface of the photosensitive material is
readily damaged.
In the photosensitive material of the repeated use
type9 it is required. to further improve mechanical,
electric a.nd chemical durabilities. Since this
photose.nsitive material is subjected to the discharge
a.nd irradiation treatment repeatedly and it is caused
to have frictional contact with a magnetic brush or
cleaning member repeatedly9 the photoconductive layer
of the photosensitive material undergoes mechanical
damages or is readily electrically or chemically
degraded. Further, such troubles as peeling of the
photoconductive layer from a conductive substrate are
readily caused while the photose.nsitive material is
being used.
Various inorganic and organic photoconductors ha~e
heretofore bee.n used for formatio.n of photoconductive
layers of photosensitive materials. Amor~ these know.n
photoconductors9 an organic polymeric photoconductor
such as polyvinyl carbazole is characterized by high
mechanical9 chemical and electric durabili-ties. Ho~ever~
since a photoconductor of this type has no sensitivity
to rays o~ the visible region Accordir~ly~ it ha5
2~ been proposed to use the photoconductor in com~ination
.~ith a sensitizer or other photoconductor
~ or example, there has been proposed a method in
which a substance acti.ng as a.n electron acceptory such
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as tri- or tetra-fluorenone ( hereinafter referred to
as ~' TNF ~ ) 9 iS incorporated into an electron-donati.ng
organic polymeric photoconductor such as polyvi.nyl
carbazole ( hereinafter refel~red to as " PVK " ) and
the organic polymeric photoconductor is sensitized by
thus conYerti.ng it to a charge-tra.nsfer complex ( see
USP ~4~9237 ~. This photoconductive composi.tion is
advantageous i.n that it is excellent in the abo~e-
mentioned photo-electric characteristics, However,
in order to attain the intended effect. expensive TNF
should be incorporated in such a large amount as 0~49
to 1.23 moles per mole of the constituent monomer of
PVK9 and therefore9 a defect that the cost of a photo-
sensitive plate is increased Ca.nnOt be avoided. When
the amount used of TNF is reduced below 0.49 mole per
mole of the constituent monomer so as to lower the
manufacturing cost of a photosensitive plate9 the
sensitivlty is decreased to such a low level as not
practically applicable.
Japanese Patent Application Laid-Ope.n Specification
No. 18545/72 proposes a photoconductive composition
com~rising PVK and phthalocyanine or its derivative
( hereinafter re~erred to as " Pc " ~. This PVK-Pc
composition has a relatively good sensitivity to a
positi~e cha~ge9 but this composi~ion does not show a
sensitivity to a negative charge to such an extent that
a photosensiti~e material fo~med ~y using this compo-
sition can be used ~or ordinary commercial e~ectrophoto-
liZ7900
graphic copying machines. Especially in a photosensitive
plate formed by using this composition9 the residual
potential a ter the transfer is at such a high level
as cannot be neglected, a.nd fogging is caused while the
copying operation is repeated or the life of the photo-
sensitive material is drastically shortened.
In Example 2 of USP 3,8163118~ it is disclosed
that a composition formed by incorporating i.n polyvinyl
carbazole a relatively small amount of 2~4,7-tri.nitro-9-
fluore:ne and a relatively large amount of phthalocyanineis used for formation of a photoconductive layer, the
red se.nsitivity is increased. However, as illustrated
in Comparative ~xample ~ given hereinafter7 this known
PVK-TNF-Pc composition has a low initial pote.ntial and
15 a low se.nsitivity9 and it has not electrophotographiC
characteristics sufficient for the resulting photosensi-
tive material to be applicable to the copying OperatiOn
usi.ng a commercial electrophotographic copyi:ng machi.ne
Further9 this known composition is poor in adherence
20 to a co.nductive substrate and the durability of the
resulting photoconductive layer is insufficient.
Brie~ Sun~.ar~; of the Invention
We foun~ that a photoconductive cornposition forme~
by inco~porating specific amounts of a.n electron-accepting
~ror~atic polycyclic nitro cornpound such as TNF and
phthalocy~..nine or its ~eriYative lnto ~n electron-
dvnating organic polymeric photocon~uctor such as P~K
has a high saturatio.n cha~ge voltage and a quick light
~79w
decay spee~ ( a ~ligh sensitivity ) i.n combinaticn~ a.nd
that in a photosensitive material formed by using this
composition9 the dark decay A~peed can be controlled
within a ra.nge suitable for repeated copying and the
residual potenti~l can be reduced to such a level as
can be .neglected9 whereby occurrence of foggi.ng can ~e
prevented9 the toner transfer ef~iciency can be improved
a.nd the llfe of the photosensitive material can be
remarkabl~, ~rolo.nged. It also was fou.nd th~t thè
above-mentio.ned photoconducti~e compositio.n is promi-
ne.ntly excellent i.n the mechanical~ chemical a.nd electric
durabi.lities. Based on these fi.ndings, we have .now
completed the present in~ention.
More specifically, in accorda.nce with the present
irlve:ntio.n~ there is provided a photoconductive composi-
tion for electrophotography9 which comprises an organic
pol.ymeric photoconductor having an donating activity,
an electron-accepting aromatic polycyclic nitrO com-
pou.nd in an amount of 0.15 to 0.4~ mole per mole of the
constituent monomer of said Grganic polymeric photo-
conductor and phtha~locyanine or its derivative in an
amount of 0.2 to 4 /0 by weight ba.sed on said orga.nic
polyrneric photoconductor.
Brief ~escript ~
Fig. 1 is a diagrarn illustrati.ng t;he saturation
charge vol~,age ( ~s ).
Fig . 2 is a Aiagram illustrating the initia7
potential ~ VI ~ an~ the residual potential ( V~ ).
'1~0
Fig. 3 is a curve showi.ng electric a.nd photoco.nduc-
tive characteristics of photoconductive compositions
of the present invention and comparative photoconductive
compositions.
Detai.led Description of the Pre~rrea ~rbw~;meAt
Electrostatic a.nd photo-electric characteristic
referred to i.n ~he instant specification will .ncw be
descri~ed by reference to Figs. 1 and 2.
Saturatio.n Charge Voltage:
An electrostatic paper à.nalyzer ( ma.nufactured by
Kaw~guchi Denki ) is used under the dy.namic measurement
conditio.ns9 and coro.na discharge of - 5 KY or + 5 KV is
applied to a photocondu¢tive layer for 10 seco.nds and
the saturation voltage on the surface of the photocon-
ductive layer is determi.ned ( Vs in Fig~ 1 ). This
saturation voltage mea.ns the saturatio.n charge voltage
of the photoconductive layer.
Dark Decay:
Under the same conditions as me.ntioned above, the
corona discharge is co.nducted. When 10 seconds have
passed at the poi.nt of terminatiOn of the coro.na dis-
charge9 the average decay DD f the surface potential
of the photoco.nducti~e layer is calculated accordi.ng
to the followi.ng formula:
2~
D 10
wherei.n Vs stands ~or the saturation charge Yoltage
~lZ79QO
defined above a.nd V10 sta.nds for the surface pcten-
tial of the photoconductive layer measured when 10
seconds have passed from the point of termi.nation
of the corona discharge.
The dark decay means this average decay DD.
Initial Pote.ntial:
The above-mentioned electrostatic paper a.nalyzer
is used under static measurement conditions a.nd a
photocoductive layer is subjected to corona discharge
of - 5 KV or + 5 KV. The initial pote.ntial means the
surface pote.ntial of the photoco.nductive layer measured
JUSt before irradiation ( VI in ~ig. 2 ).
Residual Pote.ntial:
The residual pote.ntial means a surface pote.ntial
f a photoconductive layer subjected to the above-mentioned
corona discharge ? which is measured at a point when
irradiation has been conducted at 40 luxes for 1 second
( ~R in ~ig- 2 )-
Sensitivity:
The sensitivity means a relati~e ~alue of the quan-
tity of exposure necessary for the surface potential
of t;he photoconductive layer to be reduced to 1/2 of
the initial potential ( VI )g namely the half-deca.y
exposure qua.ntity represented by the fcllowi~g formula:
S - t X T~
wherein ~; st~nds Ior the h~lf-decay exposure
~ua.ntity~ i,e,, the sensitivlty, t stands ~or a
time ( second 3 necessary for the surface potential
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to be reduced to 1/2 of the i.nitial pote.ntial VI
after i.nitiation of irradiation9 and L sta.nds for
a.n average illumina.nce t lux ) of irradiation.
A smaller value indicates a higher sensitivity.
The photoconductive composition of the prese.nt
i.nvention comprises a.n electron-donating orga.nic poly-
meric photoconductor~ an electron-accepting aromatic
polycyclic .nitro compound and phthalocyanine or its
derivative at a specific ratio, and the present
inve.ntion is based on the findi.ng that this photoconduc-
tive compositio.n is promine.ntly e~sellent over co.nven-
tio.nal photoconductive compositions lacki.ng a.ny of the
foregoing three components in the above-mentioned
electrostatic and photo-electric characteristics. More
illustratively7 a photoconductive composition of the two
compone.nt type comprisi.ng a.n electron-donati.ng organic
polymeric photoconductor and an electron-accepti.ng
aromatic polycyclic .nitro compound at a ratio falling
i.n the mixing ratio specified i.n the prese.nt invention
2C ( see the specifications of U. S. Pate.nts No. 3,159,483
a.nd No. 3~232~755 ) is defective in that the sensitivity
to light is low a.nd the residual potential a~ter exposure
is high~ as sh~w.n in Comparative Example 1 gi~en
hereina~ter. There~ore~ a photoconductive composition
f this type can hardly be used for electrophotography
of the type where the photoconduotive layer is used
repeatedly after the copying operation. Further, a
photoconductive composition comprising a.n electron-
~o ~
donating organic polymeric photoco.nductor and
phthalocyanine or its derivati~e at a ratio falling
within the mixing ratio speclfied i.n the present i.nve.n-
tion ( see Japanese Pate.nt Application Laid-Open
Specification No. 18545/72 ) is defective in that the
sensitivity to light is low a.nd the residual potential
after exposure is high, as shown i.n Comparative
Example 2 given hereinafter. Therefore, a photoconduc-
tive compositio.n of this type can hardly be used for
~lectrophotography of the type where the photoconductive
layer is used repeatedly. ~urther, a photoconduc+ive
composi'ion of the two compone.nt type comprising
phthalocya.ninè or its derivative and an electron-
do.nating aromatic polycyclic nitro compou.nd such as T~F
1~ ( see USP 3,~949868 ) is defective in that the formed
photoconductive layer is extremely poor i.n the mechanical,
chèmical a.nd electric durabilities9 the saturation
charge voltage is very l.ow and an image havi.ng a high
de.nsity ca.n. hardl.y be Gbtai.ned, as shown in Comparative
~xample 3 given hereinafter. Therefore, a photoconduc-
tive composition of this type can hardly be applied to
electrophotography o~ the type where the photoconducti~e
layer is used repeatedly.
In contrast, when an electron-donating organic
polymeric p~otoconductor~ an electron-accepting aromatic
polycyclic .nitro compoun~ a.nd phthalocyanine or its
derivative are combined l.n spec3.fic amou.nts according
to the present in~ention~ ~ecause of the synergistic
li2790~
actions of these components9 both the saturation charge
voltage a.nd the sensitivity to light can be remarkably
elevated9 the residual pote.ntial after exposure can be
reduced tG zero or such a low level as ca.n be neglected
and the mecha.nical9 chemical a.nd electric durabilities
of the photoco.nductive layer can be remarka~ly improved.
Therefore9 when the composition of the present i.nvention
is used for formation of a photoconductive layer, in
electrophotography of the type where the photoconductive
layer is used repeatedly9 it becomes possible to i.ncrease
the toner tra.nsfer ef.ficiency a:nd obtai.n a clear copied
image while preventing occurrence of fogging and a gre~t
number of prints can be obtai.ned from one photoconduc-
tive layer. Further, accordi.ng to the prese.nt inve.ntion,
there can be attained a prominent advanta~e that the
excellent effects of improvi.ng the saturatio.n charge
voltage and the sensitivity and reduci.ng the residual
pote.ntial after exposure can be obtained by using much
smaller amou.nts of the above-mentioned nitro compound
and phthalocyanine or its derivative than in the ConYen-
tio.nal known photoconductive compositions9 because of
the synergistic actions of the two components.
ln the photoconductive compGsition of the present
inve.ntion~ phthalocyanine or its derivative is unlformly
dispersed in a cOntinuous ph~se of the org~nic polymeric
photoconductor and this disperse phase is ~ery ~ine,
and it is believed that the conti.nuous phase of the
electron-donating organic pol~meric photoconductor forms
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a charge-transfer complex with the electron-accepti.r~
aromatic polycyclic nitro compound. A system comprising
phthalocyanine or its deri~ative dispersed i.n a conti-
.nuous phase of the orga.nic polymeric photoco.nductor
shows a relatively good sensitivity to light whenpOSitiVe charges are applied9 but whe.n this system is
.negatively charged a.nd then exposed to actinic radiation,
no practically satisfactory sensitivity is obtained.
In co.ntrast, when the organic polymeric photoconductor
of the co.nti.nuous phase is co.nverted to a complex with
the electron~accepti.ng aromatic polycyclic nitro com-
pound accordi.ng to the present i.nve.ntion, also when the
photoco.nductive layer is negatively charged9 a very
excelle.nt se.nsitivity is obtained and this sensitizing
effect can be attained by usi.r~ the aromatic polycyclic
nitro compound in an amount much smaller than the minimum
amount .necessary for sensitizi.ng the organic polymeric
photoconductor to charges of the negative polarity by
the aromatic polycyclic nitro compound alone. This is
~uite a surprisi.ng fi.nding.
Any of known po]ymeric substances havir~ electro.n-
donating and photoconductive properties can be u~ed as
the organic polymeric photoconductor in the present
i.nvention. For example, there can be used poly-N-
vinylcarbazole~ poly-N-acrylphenothiazi.ne~ poly-N-
(~-acryloxyethy])-phenothiazine, poly-N-~2-acryloxypropyl)-
phenothiazine9 poly-N-allylcarbazole, poly-N-2-acryloxy-
2-methyl-N-ethylcarbazole9 poly-N-(2-p-vinylbenzoylethyl)-
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1127900
carbazole9 poly-N-propenylcarbazole9 poly-N-2-methylacryl-
oxapropylcarbazole, poly-N-acrylcarbazole9 poly-4-vi.nyl-
p-(N-carbazyl)-toluene, poly(vi.nylanizalacetophenone39
polyinde.ne and other known photoco.nductive polymers.
Polymeric photOconductors that are easily available
a.nd suitable for attaini.ng the objects of the present
invention are poly-N-vi.nylcarbazole and nuclear substi-
tution products such as haloge.n- and alkyl-substituted
derivatives thereof,
Any of known aromatic polycyclic compounds havi.ng
at least one nitro group as the nuclear substituent
a.nd having an electro.n-accepti.ng property can be used as
the electron-accepting aromatic polycyclic nitro com-
pound. For example9 there can be used 294-di.nitro-l-
chloronaphthalene, 1,4-dinitro.naphthalene, 1,5-
di.nitronaphthalene9 3-nitro-N-butyl-carbazole, 4-nitro-
biphe:nyl7 4,4'-di.nitrobiphenyl9 1-chloro-4-nitroanthra-
quinone) 2,7-dinitroanthraquinone9 294,7-trinitrofluore-
none, 2~49 59 7-tetranitrofluorenone? 9-dicyanomethyle.ne-
29497-trinitrofluore.none and 4-nitroacenaphthe.ne
Trinitro- a.nd tetranitro-fluorenones are especially
suitable for attaining the objects of the present inven-
tion.
Any of know.n phthalocyanine a.nd phthalocyanine
derivatives having a photoconductive property can be
used as phthalocyanine or its derivative. Suitable
examples are aluminum phthalocyani.ne9 alumi.num poly-
chlorophthalocyanine9 antimony phthalccyani.ne, barium
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11279QO
phthalocya.nine9 beryllium phthalocyani.ne, cadmium
hexadecachlorophthalocyanine7 cadmium phthalocyanine,
cerium phthalocyanine9 chromium phthalocyani.ne9 cobalt
phthalocya.ni.ne9 cobalt chlorophthalocyanine9 copper
4-ami.nophthalocyanine, copper bromochlorophthalocyanine,
copper 4-chlorophthalocyanine9 copper phthalocya.nine
sulfonate9 copper polychlorophthalocyanine9 dysprosium
phthalocyanine9 erbium phthalocyanine, europium phthalo-
cyani.ne9 gadolinium phthalocya.ni.ne, ~allium phthalocya-
nine9 germa.nium phthalocyanine, holmium phthalocya.ni.ne,indium ph~halocya.nine9 iron phthalocyanine9 iron
polyhalophthalocyanine9 la.nthanum phthalocyanine9 lead
phthalocyani.ne9 lead polychlorophthalocyanine9 cobalt
hex2phe.nylphthalocyanine9 copper pentaphenylphthalocya.nine,
lithium phthalocyani.ne9 lutetium phthalocyanine9
magnesium phthalocya.ni.ne7 ma.nganese phthalocyanine,
mercury phthalocyanine9 molybde.num phthalocyanine,
neodium phth~locyanine9 nickel phthalocyani.ne, nickel-
polyhalophthalocy~nine7 osmium phthalocyanine9 palladium
phth~locyanine9 palladium chlorophthalocyani.ne9
alkoxyphthalocyanine9 alkylaminophthalocyanine9
alkylmercPptophthalocyani.ne9 arylmercaptophthalocyanine,
copper phthalocya.nine-piperidine9 cycloalkylami.nophthalo-
cyanine, dialkylaminophthalocyanine, diaralkylami.noph-
thalocyani.ne9 dicycloalkylaminophthalocya.nine9 hexade-
cahydrophthalocyanine9 imidomethylphthalocyanine, octa-
azophthalocyanine7 sulfur phthalocyanine, tetra-azophtha-
locyanine7 tetra-4-aminobenzoylphthalocyanine9 tetra-4-
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acetylaminophthalocyanine, tetra-4-aminophthalocyanine,
tetrachloromethylphthalocyanine, tetradiazophthalocya-
nine9 tetra-494-dimethylocta-azophthalocyanine9 tetra-
495-diphenylene-dioxide-phthalocyani.ne9 tetra-49 ~
diphe:nylocta-azophthalocya.nine9 tetra-(6-methyl-be.nzo-
thiazoyl)phthalocya.nine9 tetra-p-methylphenylaminoph-
thalocyani.ne9 tetramethylphthalocyanine9 tetra-4-
naphthotriazolphthalocyanine9 tetra-4-naphthylphtha-
locyanine9 tetra-L.-.nitrophthalocyani.ne9 tetraperinaph-
thylene-4,5-octa-azophthalocyani.ne9 tetra-2,3-
phe.nylene-oxide-phthalocyanine9 tetra-4-phenylocta-
azophthalocya.ni.ne9 tetraphenylphthalocyanine9 tetra-
phe.nylphthalocyani.ne-tetracarboxylic acid, tetraphenyl-
phthalocyan:ine tetrabarium carboxylate9 tetra-4-trifluro-
methylmercaptophth~locya.nine9 tetrapyridylphthalocyanine,
tetra-4-trifluoromethylmercaptophthalocyanine, tetra-4-
trifluoromethylphth~locyanine-4,5-thio.n2phthene-octa-
azophthalocyanine, platinum phthalocyanine9 potassium
phthalocya.nine9 thodium phthalocyanine9 samarium phthalo-
cyanine, silver phthalocyanine9 silicon phthalocyanine,sodium phthalocyanine9 sulfonated phthalocyanine,
thorium phthalocya.ni.ne9 thulium phthalocyanine9 tin
chlorophthalocyanine9 tin phthalocyanine, titanium
phthalocya.ni.ne9 uranium phthalocyanine9 vanadium phtha-
locya.nine9 zi.nc chlorophthalocyanine9 zinc phthalocyanine,and dimers9 trimers9 oligomers9 homopolymers and
copolymers thereof Metal-free phthalocya.nines and
nuclear substitution products thereof9 for example,
0
haloge.n .nuclear substitution products thereof, are
easily available and especially suitable for attaining
the objects of the present invention.
I.n the prese.nt inve.ntion9 it is very important that
the electron-accepti.ng aromatic polycyclic .nitro compound
should be used in an amou.nt of 0.15 to 0.45 mole per
mole of the constituent monomer of the electro.n-do.nati.ng
organic polymeric photoco.nductor and that pm halocyanine
or its derivative should be used in an amount of 0.2 to
4 % by weight based on the organic polymeric photoconduc-
tor.
Whe.n the amount of the phthalocyanine is below the
above range9 the sensitivity to light is reduced and the
residual pote.ntial after exposure is readily i.ncreased.
When the amou.nt of the phthalocya.nine exceeds the above
range9 the saturation charge voltage is lowered a.nd also
the sensitivity to light is reduced. Further9 a composi-
tio.n comprisi.ng the phthalocya.ni.ne i.n too large an amount
is poor i.n th@ coating-forming property a.nd i.n this
composition9 there is observed a te.nde.ncy that the
mechanical strength or ~dhesion of the coating is
insufficient.
When the amou.nt of the aromatic polycyclic nitro
compound is below the above range9 the sensitivity to
light is reduced and increase of the residual potential
after exposure is conspicuous. When the amount of the
aromatic polycyclic nitro compound exceeds the above
range9 the saturation charge voltage is drastically
~Z7XIV
reduced.
As will be apparent from the foregoing, whe.n TNF
or Pc is incorporated i.nto an organic polymeric photo-
conductor9 if the amount i.ncorporated is small, the
se.nsitivity is low a.nd the residual pote.ntial is
increased. On the other hand9 if the amount i.ncorpora
ted is increasedg the saturation charge voltage te.nds to
decrease~
I.n co.ntrast9 if both the aromatic polycyclic nitro
compound a.nd phthalocyani.ne or its derivative are
incorporated in combi.nation in specific small amounts
accordi.ng to the present i.nvention, it is made possible
to satisfy two co.ntradictory requirements, namely increase
of the saturation charge voltage a.nd reduction of the
residual pote.ntial.
I.n additio.n to the above-me.ntio.ned three indis-
pe.nsable compone.nts9 the photoconductive composition of
the prese.nt invention may further comprise known
additives according to need. As such additives9 there
2~ can be me.ntioned9 for example9 a bi.nder9 a thickener9 a
viscosity reduci.ng agent, a saggi.ng preventi.ng age.nt9 a
leveling age.nt9 a defoaming age.nt a.nd a dye sensitizer.
The photoconductive composition of the prese.nt inve.n-
tion is dissolved or dispersed i.n an organic solvent to
form a coati.ng composition9 and the coating composition
is applied to a conductive substrate and dried thereon
to form a photosensitive plate for electrophotography.
As the solve.nt that is used for formi.ng a coati.ng
co~.position9 there can be mentioned9 for example, aro~atic
hydrocarbon solve.nts such as benzene, toluene a.nd xylene,
cyclic ethers such as dioxa.ne a.r,d tetrahydrofuran9
ketones such as methylethyl ketone9 methylisobutyl
ketone and cyclohexa.none, alcohols such as diacetone
alcohol9 ethylene glycol a.nd isobutyl ether9 and ali-
cyclic hydrocarbons such as cyclohexa.ne. These solve.nts
may be used ~ngly or i.n the form of mixtures of two or
more of them.
This coating composition ca.n easily be prepared by
forming a solution of the organic polymeric photo-
conductor in an organic solvent a-nd a dispersion of
phthalocyanine or its derivative in an organic solve.nt,
mixi.ng the solution and dispersi~n a.nd addi.ng the aromatic
polycyclic nitro compound into the resulting mixture or
the above-me.ntio.ned solution or dispersion. From the
viewpoi.nt of the adaptability to the coati.ng operation9
it is preferred that the solid content of the so formed
coating composition be 1 to 50 %9 especially 5 to 30 %.
As the conductive substrate9 a foil or plate of
copper, aluminum, silver, tin~ iron or the like is used
i.n the form of a sheet or drum. Alternately9 a product
formed by applying such metal in the form of a film to
a plastic film or the like by vacuum deposition or
nonelectrolytic plating can be used as the co.nductive
substrate.
The photoconductive composition of the present
inve.ntio:n can be coated on the conductive substrate in
- 20 -
~900
the form of a layer ha~ing a thic~ness of 2 to 20 ~,
especially 3 to 10 ~9 as measured as the solid.
In a photosensitive material formed by usi.ng the
photoconductive composition of the prese.nt invention~
the electric a.nd photoco.nductive characteristics in
electrophotography of the type where the photosensitive
material is repeatedly used are remarkably improved and
simultaneously, the mechanical properties of the photo-
sensitive material, such as the peel resistance can also
be remar~ably improved. More specifically, in case of a
photosensitive material comprising a single photoco.nduc-
tive layer composed of phthalocyanine or its derivative,
the aromatic polycyclic nitro compound and the polymeric
photocanductor, peeling of the photoconductive layer is
not caused at all at the pressure-se.nsitive tape peel test
described hereinafter, and a high abrasio.n resistance
can be attained. Thus, it is evident that the mechanical
properties of the photosensitive material can be promine.ntly
improved by usi.ng the photoconductive composition of the
prese.nt i.nve.ntion.
The photoconductive composition o~ the prese.nt
inve.ntio.n is especially suitable for formation of a
photosensitive material to be used in an electrophoto-
graphic copying machine of the type where the surface of
the photose.nsitive material is negatively charged a.nd
reproductio.n is carried out by using the photosensitive
material repeatedly while utilizing all the rays of the
visible region.
llZ7900
A photoconductive layer formed by using the
photoconductive composition of the prese.nt in~ention
shows excellent electrophotographic and electric
characteristics as shown in Table 1 given herei.nafter9
also whe.n it is positively charged. Accordi:ngly9 the
photoco.nductive composition of the prese.nt i.nve.ntio.n
can be advantageously applied to formation of a photo-
sensitive material to be used in electrophotographic
reproductio.n in wllich the photoco.nductive layer is
positively charged.
Known two-component type developers and known one-
compo.ne.nt type magnetic developers can be used for
developing a late.nt image formed on the photoconductive
layer.
The present inventio.n will now be described i.n
detail by refere.nce to the following Examples that by
no mea.ns limit the ~ ope of the inve.ntion.
In the Examples9 all of 1I parts " and " % " are
by weight unless otherwise i.ndicated.
Example 1
To 10 parts of polyvinyl carbazole ( Luvican~M-170
manufactured by BASF9 herei.nafter referred to as " PVK " )
was added 90 parts of tetrahydrofuran to form a solution
contai.ni.ng 10 % of PVK in tetrahydrofuran.
The.n9 99 parts of tolue:ne was added to 1 part of
metal-free phthalocyanine ( Heliogen Blue 7800 ma.nufac-
tured by B~SF )9 and the phthalocya:nine was sufficiently
dispersed in toluene by an ultrasonic vibrating dis-
persing machine to form a 1 % dispersion of the
~-trc~d~na~ _ 22 -
1127900
phthalocyani.ne.
To 10 parts of the above-me.ntio.ned 10 % PVK solu-
tion were added 0.6 part of 274,7-trinitro-9-fluorenone,
1.0 part of the 1 % phthalocya:ni:ne dispersion and 2.0
parts of tetrahydrofuran. The mixture was sufficie.ntly
treated by an ultraso.nic vibrati.ng dispersi.ng machine
to form a coating compositio.n.
The so formed coating composition was coated o.n
an aluminum plate having a thickness of 50 ~ by means of
a wire bar9 a.nd dried at 50 C. for 3 minutes and forcibly
dried at 120C for 2 mi.nutes, to obtain a photose.nsitive
plate comprising a photoconductive layer havi.ng a thick-
ness of 4 ~ after drying.
The charge characteristics of the so prepared
photosensitive plate were examined by usi.ng a.n electro-
static paper analyzer ( manufactured by Kawaguchi Denki )
to obtai.n results show.n in Table 1 a.nd Fig. 3.
The so prepared photosensitive plate was set at an
electrophotographic copying machine ( Denshi Copystar~
251-R manufactured by Mita I.ndustrial Company ) a.nd was
charged at an applied voltage of - 7 KV, and development
was carried out accordi.ng to the magnetic brush method.
A clear image having a high density a.nd being free from
foggi.ng can be obtained. When this photose.nsitive
plate was subjected to the durability test9 it was found
that scores of thousands of prints could be obtained by
usi.ng this photose.nsitive plate repeatedly.
ExamPle 2
-
aclernc~k
- 23 -
1~
To 1 part of copper phthalocyani.ne ( Cyanine Blue
BB manufactured by Dai.nippon I.nk Kagaku Kogyo ) was
added 99 parts of tolue.ne, and the phthalocya:nine was
sufficie.ntly dispersed i.n toluene by an ultrasonic
vibrati,ng dispersing machine9 to form a 1 % dispersion
of copper phthalocyani.ne.
To 10 parts of a 10 % PVK solution prepared in the
same manner as described in Example 19 0.4 part of
294~7-trinitro~9-fluorenone9 1.0 part of the above 1 %
dispersion of copper phthalocyani,ne and 2.0 parts of
tetrahydrofura:n were added to form a coati.ng composi-
tion, Then~ a sample was prepared by usi.ng this coati.ng
composition in the same ma.n.ner as described in Example 1.
The so prepared sample was set at an electrophoto-
graphic copyi.ng machine ( De.nshi Copystar 251-R ma.nufac-
tured hy Mi,ta I.ndustrial Company )9 a.nd it was charged
at an applied voltage of - 7 KV and exposed to light a.nd
developme.nt was carried out accordi,ng to the magnetic
brush method. A clear and sharp image free from fogging
was obtained.
Exam~le 3
To 10 parts of poly-N-acrylphenothiazine was added
90 parts of tetrahydrofuran to form a solutio.n containing
10 /0 of poly-N-acrylphe,nothiazine in tetrahydrofuran.
To 10 parts of the so prepared solution were added
0.5 part of 2~497-trinitro-9-fluore.no.ne9 O.g part of a
1 /0 phthalocyanine dispersion prepared in the same
man.ner as described in Exa.mple 1 and 3.0 parts of
- 24 -
` ~79QO ,
tetrahydrofuran to form a coati:ng composition9 and by
using this coating compositio.n9 a sample was prepared
in the same manner as described i.n Example 1.
The sample was set at an electrophotographic
copyi.ng machine ( De.nshi Copystar 251-R manufactured by
Mita I.ndustrial Co. )9 and it was charged at an applied
voltage of - 7.5 KV and developme.nt was carried out
accordi.ng to the magnetic brush method after exposure
to light. A clear and sharp image free from fogging was
obtai.ned.
ExamPle 4
To 10 parts of a 10 % PVK solution prepared in the
same ma.nner as described i.n Example 1, 0.4 part of
2~49597-tetranitro-9-fluorenone, 1.5 parts of a phthalo-
cyanine dispersion prepared i.n the same manner as des-
cribed i.n Example 1 ~nd 2.0 parts of tetrahydrofuran
were added to form a coati.ng composition. By using this
coating composition9 a sample was prepared in the same
ma.n.ner as described i.n Example 1.
The sample was set at a.n electrophotographic
copyi.ng machine ( Denshi Copystar 251-R manufactured by
Mita Industrial Company ) 9 a.nd it was charged at a.n
applied voltage of - 7~5 KV and exposed to light a.nd
development was carried out accordi.ng to the magnetic
brush method. A clear and sharp image free from fogging
was obtained.
Example 5
A photosensitive plate was prepared in the same
~Z7900
ma.nner as described in Ex~mple 1 except that chlorinated
polyvinyl carbazole ( manufactured by Takasago Koryo
Compa.ny ) was used instead of tne polyvi.nyl carbazole
used in Example 1 ( Luvican M-170 ma.nufactured by
BASF )9 a.nd this photosensitive plate was tested in the
same ma:nner as described i.n Example 1. Good results
similar to those obtained i.n Example 1 were obtai.ned.
Example 6
A photosensitive plate was prepared i.n the same
ma.nner as described in Example 1 except that poly-N-
vi.nyl-396-dibroms carbazole was used i.nstead of the poly-
vi.nyl carbazole used in Example 1 ( Luvica.n M-170
manufactured by BASF ). The photosensitive plate was
tested in the same ma.nner as described i.n Example 1.
An excellent image similar to that obtained in Example
1 was obtained3 and it was found that the photosensitive
plate was excellent i.n the durability ( the resista.nce
to the repeated copying operation ).
Example 7
A photosensitive plate was prepared in the same
ma~ner as described in Example 1 except that poly-N-
allylcarbazole was used instead of the polyvinyl carba-
zole used in Example 1 ( Luvican M-170 manufactured by
BASF ) and Sumitone~Cyani.ne Blue LG ( manufactured by
Sumitomo Kagaku Kogyo ) was used as the metal-free
phthalocyanine instead of Heliogen Blue 7800 used in
Example 1. When the characteristics of the photosensi-
tive plate were tested in the same manner as described
in Example 1~ good results were obtained.
~a c~ e ~
- 26 -
`~79~
Example 8
A photosensitive plate was prepared in the same
ma.nner as described in Example 1 except that chlori.nated
polyvinyl carbazole was used i.nstead of polyvinyl
carbazole ( Luvican M-170 ) and 494'-dinitrobiphe.nyl
was used instead of 29497-trinitro-9-fluorenone.
Properties of the so prepared photosensitive plate were
tested in the same manner as described in Example 1.
Good results similar to those obtained in Example 1 were
obtained.
Comparative Example 1
To 10 parts of a 10 % PVK solution prepared in the
same manner as described i.n Example 19 0.6 part of 2,4,7-
trinitro-9-fluorenone a.nd 2.0 parts of tetrahydrofura.n
were added a.nd they were sufficiently dispersed by an
ultrasonic vibration dispersi.ng machine to form a coati.ng
composition.
A sample was prepared by using this coating compo-
sition i.n the same manner as described in Example 1.
Charge characteristics of the sample were tested
in the same manner as described in Example 1 to obtain
results shown in Table 1 and Fig. 3.
The sample W2S set at a:n electrophotographic copying
machine ( De.nshi Copystar 251-R manufactured by Mita
Industrial Company ), and it was charged at an applied
voltage of - 5.5 KV9 exposed and developed according to
the magnetic brush method. The obtained image was full
of foggi.ng9 and appearance of foggi.ng could not be avoided
~9oo
even if the exposure quantity was elevated to a maximum
level.
Com~rative Example 2
To a 10 % PVK solution prepared i.n the same ma.nner
as described i.n Example 1, 4 parts of a 1 ~ phthalocyanine
dispersio.n prepared in the same man.ner as described in
Example 1 and 2 parts of tetrahydrofuran were added and
they were sufficie.ntly dispersed by a:n ultrasonic vibra-
ting machine to form a coating composition.
By usi.ng the so prepared coati.ng composition, a
sample was prepared in the same manner as described in
Example 1.
Charge characteristics of the sample were tested in
the same man.ner as described in Example 1 to obtain
results shown in Table 1 a.nd Fig. 3.
The sample was set at a.n electrophotographic
copying ~chine ( Denshi Copystar 251-R rna.nufactured
by Mita I.ndustrial Company )9 and it was charged at an
applied voltage of - 6.0 KV, exposed to light a.nd develo-
ped accordi.ng to the magnetic brush method. The obtained
image was not clear a.nd was full of fogging9 and .no
definite disti:nction was observed betwee.n the image
area and the :non-image area ( the contrast was very low ).
Comparative Example ~
To 10 parts of 29497-trinitro-9-fluorenone was
added 40 parts of tetrahydrofura.n9 a.nd the fluorenone
was sufficiently dissolved in tetrahydrofuran. Then,
a solution of 0.5 part of copper phthalocyanine in 20
- 28 -
~7900
parts of toluene was added to the above solution. The
resulting mixture was pulverized in a ball mill for 1
hour to form a fine suspensiOn. In the same ma.nner as
described in Example 19 the suspe.nsion was coated on
alumi.num and dried i.n air at 110C. for 12 hours to form
a coating layer havi.ng a thickness of 5 ~ after drying.
Charge characteristics of the so prepared sample
were measured in the same ma.nner as described in Example
1 to obtain results shown in Table 1 a.nd Fig, 3.
The sample was set at an electrophotographic
copyi.ng machine ( Denshi Copystar 251-R manufactured by
Mita Industrial Compa.ny ) 9 and it was charged at an
applied voltage of - 7.0 KV, exposed to light and developed
according to the magnetic brush method. The obtai.ned
image had a low density and was full of foggi.ng. Further9
the resolving power was insufficie.nt and the disorder of
the image owi.ng to peeling of the photoconductive layer
was observed.
Comparative ExamPle 4
To a 10 % PVK solution prepared in the same ma.nner
as de.scribed in Example 19 0.6 part of 29497-trinitro-
9-fluoreno:ne a.nd 7 parts of a 1 % phthalocyanine disper-
sion prepared in the same ma~ner as described i.n Example
1 were added and they were sufficie.ntly dispersed by an
ultrasonic vibrati.ng dispersi.ng machine to form a
homogeneous coati.ng composition.
By usi.ng the so prepared C02ti~g composition9 a
sample ( photosensitive plate ) was prepared in the same
- 29 -
~27~00
manner as described in Example 1.
Charge characteristics of the so prepared sample
were tested in the same ma.nner as described in Example 1
to obtain results shown i.n Table 1 and Fig. 3.
The sample was set at an electrophotcgraphic copying
machine ( Denshi Copystar 251-R manufactured by Mita
Industrial Company )9 a.nd it was charged at an applied
voltage of - 8.0 KV9 exposed to light and developed
according to the magn~tic brush method. An image could
:not be formed because of insufficient chargin~.
Comparative Example 5
To a 10 % PVK solution prepared i.n the same
ma:nner as described in Example 19 o.6 part of 2,4,7-
trinitro-9-fluoreno.ne, 0.1 part of a 1 % pm halocyanine
dispersion prepared in the same ma.~ner as described in
Example 1 a.nd 3,0 parts of tetrahydrofuran were added
a.nd they were sufficie.ntly dispersed by an ultrasonic
vibrating dispersing machine to form a coating compo-
sition.
By using the so prepared coating composition, a
sample (-photosensitive plate ) was prepared in the same
manner as described in Example 1.. Charge characteristics
of the sample were measured in the same mA.nner as des-
cribed in Example 1 to obtain results show.n in Table 1
a.nd Fig. 3.
The sample was set at an electrophotographic copying
machi.ne ( Denshi Copystar 251-R manufactured by Mita
Industrial Company )g and it was charged at an applied
- 30 -
~7go0
voltage of - 6.7 KVg exposed to light and developed
according to the magnetic brush method. The resulti.ng
image was not clear a.nd was full of fogging, a.nd .no
definite distinction was observed betwee.n the image area
and the .nonimage area.
Comparative Example 6
To 10 parts of a 10 ~ P.VK solution prepared in the
same manner as described in Example 19 1.4 parts of
2,4~7-tri.nitro-9-fluorenone9 1.0 part of a 1 % phthalo-
cyanine dispersion prepared in the same manner as des-
cribed in Example 1 and 2 parts of tetrahydrofuran were
added and they were sufficie.ntly dispersed by an ultra-
so.nic vibrati.ng dispersing machine to form a coati.ng
composition.
By usi.ng the so prepared coati.ng compositio.n, a
sample was prepared in the same manner as described i.n
Example 1 Charge characteristics of the sample were
measured in the same ma.nner as described in Example 1
to obtain results shown in Table 1 and Fig. 3.
The sample was set at an electrophotographic copy-
ing machine ( Denshi Copystar 251-R manufactured by Mita
Industrial Company )g and it was charged at an applied
voltage of - 7.0 KV9 exposed to light and developed
according to the magnetic brush method. The image den-
sity was low and the image was not clear a.nd was full of
foggi.ng.
Comparative ExamPle 7
To 10 parts of a 10 % PVK solution prepared in the
~moo
same manner as described in Example 19 0.1 part of 2~4,7-
tri.nitro-9-fluore.none, 1.0 part of a phthalocya.nine
dispersion prepared i.n the same ma.nner as described i.n
Example 1 and 2 parts of tetrahydrofuran were added a.nd
they were sufficiently dispersed by an ultrasonic
vibrating dispersi.ng machi.ne to from a coati.ng composi-
tion.
By using the so prepared coating composition9 a
sample was prepared i.n the same ma.nner as described in
Exa.mple 1. The sample was set at an electrophotographic
copying machine ( Denshi Copystar 251-R ma.nufactured by
Mita Industrial Company )~ and it was charged at an
applied voltage of - 6.5 KV9 exposed to light and
developed according to the magnetic brush method. The
obtained image was not clear and was full of fogging,
a.nd no definite distinction was observed between the image
area and the nonimage ~rea.
ComE~_ative Example 8
To 85 parts of a 10 % PVK solution prepared in the
same manner as described in Example 1, 0.5 part of
29 /~9 7-trinitro-fluorenone and 21 parts of ~ 10 % phtha-
:locya.nine dispersion ( the solve.nt bei.ng tolue.ne )
prepared i.n -the same manner as described in Example 1,
a.nd 20 parts of tetrahydrofura.n was further added
thereto, The mixture was treated by an ultrasonic
vibrating dispersing m~chine to form a homoge.neous coat-
ing composition.
A sample ( photosensitive plate ) was prepared by
- ,2 -
~27900
using the so prepared coating composition in the same
ma.nner as described i.n Example 1. Charge characteristics
of the sample were measured in the same manner as
described in Example 1 to obtain results shown in Table
1 and Fig. 3.
This sample was set at a.n electrophotographic
copyi.ng machi.ne ( Denshi Copystar 251-R manufactured by
Mita T:ndustrial Compa.ny ), and it was charged at an
applied voltage of - 8.0 KY9 exposed to light a-nd
developed according to the mag.netic brush method. The
charging failed to provide a pote.ntial e-.nabling deve-
lopment, and the se.nsitivity was ver~ poor and a copy
havi.ng slight fogs alone was obtained~ ~urther, the
peel stre.ngth of the photoconductive layer in the
photosensitive plate was very low and great care had to
be taken in ha:ndling the photosensitive plate.
Comparative E~ e 9
A coating composition was prepared i:n the same
manner as described in Comparative Example 8 except that
the amount of the phthalocya.nine dispersio.n was cha.nged
to 1 part a.nd the amount of tetrahydrofuran was changed
to 30 parts. A sample ( photosensitive plate ) was
prepared by using the so prepared coati.~g composition
in the same manner as in Comparative Example 8. Charge
characteristics of the sample were me~sured in the same
ma:n:ner as described in Example 1 to obtain results shown
in Table 1 and Fig. 3.
The so prepared sample was set at an electrophoto-
graphic copying machine ( De.nshi Copystar 251-R manufac-
tured by Mita Industrial Company )9 a-.nd it was charged
at an applied voltage of - 7.0 KV9 exposed to light and
developed accordi.ng to the mag.netic brush method. The
obtained image was full of foggi.ng a.nd no definite
disti.nction was observed between the image area a.nd
the nonimage area ( the contrast was very low ).
- 34 -
~Z7900
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- 35 -
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- 36 --
~goo
Note
The image quality and adhesion referred to in
Table 1 were evaluated according to the followi:ng standards.
Sharpness:
The sharpness was evaluated based on reproducibility
of fine lines9 mesh, halft.one a.nd small letters in the
image according to the followi.ng scale:
0: good
~: slightly bad
X o bad
Density:
The density was evaluated based on the degree of
the density or light.ness i.n the image area ( unexposed
area ) according to the following scale:
O o de.nse
~: slightly light
X 0 light
Fogg ing ~
The foggi.ng was evaluated based on the degree of
contami:natio.n of the backgrou:nd in the nonimage area
( exposed area ) accordi.ng to the following scale:
O ~ no contami.nation
/\: slight contami.nation
X : apparent contamination
AdhesionO
The adhesion was evaluated accordi.ng to the
pressure_sensitive tape peeling test.
O 0 not peeled
- 37 -
1~9~0
~: slightly peeled
X : readily peeled
ExamPle 9
A photosensitive plate prepared in the same manner
as described in Example 1 was charged at an applied
voltage of + 6.5 KV by corona discharge, and it was
the.n exposed to light through a.n original and develop-
me.nt was carried out by usi.ng a one-compone.nt type
magnetic toner. The toner image was transferred at an
applied voltage of + 5.4 KV and the transferred toner
image was fixed under application of pressure. A clear
and sharp image having a high density and bei-.ng free
from fogging was obtained.
E _ ple 10
A copied image was formed in the same manner as
described in Example 9 except that the fixation of the
tra.nsferred image was carried out by usi.ng a heated roll
and the to.ner was ch~nged to a one-component type
mag.netic toner for heated roll fixation The obtained
image had a high density a.nd was very clear and sharp,
a.nd occurrence of foggi.ng was not observed at all.
- 38 -
