4~
Background of the Invention
(1) Field of the Invention:
This invention relates to a ~lotosensitive mat~rial
~or electrophotography which has a novel laminate st~uc-
ture. More particularly, the invention relates to a
photosensitive material for electrophotography which
comprises an electrically conductive substrate, an
intermediate layer formed on said substrate and a top
layer laminated on said intermediate layer, wherein
said intermediate layer comprises ~A) an organic polymeric
photoconductor and (B) a polycyclic aromatic nitro
; compound at an (A)/~B) weight ratio of from 6~1 to
1/6 and said top layar comprises, incorporated in a
binderJ (C) phthalocyani.ne or a phthalocyanine derivative
and (B) said polycyclic aromatic nitro compound at a
(V)/(B~ weight ratio of from 10/5 to 10/25.
(2) Description of the Prior Art:
In the art of electrophotography, there is broadly
adopted a process comprising charging a photosensitive
material provided with a photoconductive lay~r by corona
discharge or the like, exposing the photosensitive
material imagewise to actinic rays to form an electro-
static latent image on the surface of the photoconductive
layer, applying a developer to the surface of the
photoconductive layer to form a toner image corresponding
to said electrostatic latent image and transferring said
toner image formed on the surface of the photoconductive
layer into a copying paper. In this conventional
process, a.~ter the transfer of -the toner image, the
photosensitive ma-terial i.5 fed to the cleaning step
where -the residual -toner is remaved, and it is -then
~ed to the above-men-tioned ch~rging s-tep and subse~uent
steps again.
An electrophotogr~phic photosensitive material
that is used repeatedly in the above-mentioned
electropho-tographic process is required to have some
special properties different from properties required
of a photosensitive material of the type where ~ toner
is directly ~ixed on the pho-tosensitive layer. More
speci~ically, in order to prevent fogging in the repeated
copying operation and prolong -the liie of the pho-tosen~-
sitive material, it is neces~ry that the photosensitive
material of the ~ormer type should have a relatively
~uick dark decay ( the property that the surface
potential o~ the non-exposed ~rea o~ the photosensitive
layer decays relatively quickly in the dark ) ~nd a
residu~1 potential as low ~s negligible ~ the property
2Q that the potentiQl left on the exposed ~rea of the
photosensitive layer is as low as negligible ~. When
the residu~l pot~ntial of the ph~tosen~itive ~terial
is high, it ~lready cau~es fog~ing at the tran~f~r ~step.
Further, in this case or in the c~e where the dark
decay speed o~ the photosensiti~e material is low,
electrostatic charges vn the electrostatic image for~ed
on the ~ur~ace of the photoBen~iti~a material or
electrostatlc ch~rge~ generated ~or other reason are
lef-t on the surface of the photosensitive material even
~fter the tran~fer ~nd cleaning s-teps and they cause
fo~ging at the next cycle of the copying operation.
Moreover, if the dar~s dec~y speed is low, everl after
the transfer s-tep, toner particles are electrostatiCally
~ttracted to the sur~ace o~ the photosensitive material
b~ a relatively strong ~ttrac-ting force and therefore,
the e~ficiency of transfer of the toner to ~ copying
paper is relatively low and the sur~ace of the
photosensitive material must be wiped strongly to remove
the residual toner from the sur~ace of -the photosensitive
- materLal. As a result9 the sur~ace of the photosensi-
tive material is readily and quickly damaged and the
life o~ the photosensitive material is shortened.
The photosensitive material of this repeatedly
used type is also required to have a highly enhanced
mech~nical, electric or chemic~l durability. Namelyv
since the photosensitive muterial of this type undergoes
repeatedly the discharge or irradiation treatment and
receives repeatedly friction with a magnetic brush or
cleaning member, the photoconductive layer o~ the
photo~ensitive material is readily mechanically dam4ged
or electircally or chemically deteriorated. Moreover,
such a trouble as peeling of the photoconductive la~er
~rom the electrically conductive substrate is readily
caused while the photosensitive material is being used.
As the substance for forming a photoconductive
layer of a photosensitive material, there aré known
. :
various orgQnic and inorg~nic photoconductors. Among
these known photoconductors, ph-th~locyani.ne and phthalo-
cyanine deriva-tives have been noted as substances
valuable for manuf~cture o1:` photosensitive material~ for
5 electrophotogrRphy bec~use their chemical and electric
durabilities are excellent ~nd they are ea~ily available
and oheap ~
Photosensitive materi~ls ~or electrophotography
includin~ phth~locyQnine or its deri~ative a~ a photo-
10 conductor, however, :~il to satis:E`y the ~oregoingrequirements sugf ciently. For example, a photo3en~itive
material comprising a photoconductive layer compo ed
of a dispersion of phthalocyanine or its derivatlve in
~n electrically insul~ting binder, which i~ ~ormed on
15 ~n elecl;ric~lly conductive substrate, i~ Still de~Gtiv~
in that the val~e o~ t~ sur~ace pot~ntial at the
ch~rging step is gener~lly low9 the ri~ing spe~d 0~ th~
surfac~ potenti~l 15 low, ~he residual pot~r~tlal at th~
expo~ure ~tep is still ~t P level that c~nnot b~
20 negle~ted ~nd the ~peed o~ r~ductlon oî ~he ~pote~t~:l
ln the no~-e~po~ed area9 n~mely the d~rk dec~y ~p~ed,
i3 low.
Bri~:~ Sunm~ o~ the Invention
We îound that when ~n in~ernl~di~te lay~r compri~sin~
25 ~A) an or~flnic polymerlc photoconduc~or and (B)
polycyclic arom~tic nitro compound ~t ~ ~peci~ic
rat$o i~ formed on ~n electrlcallr conductive substr~t~
~nd a top ~;ayer compri~ing, incorpor~ted in ~ binder,
o 5 _
(C) phth~locyanine or ~ phthalocy~nine deriva tive and
(~3) said polycyclic ~romatic nitro compound at a ~peci~ie
ratio is ~ormed on the intermediate layer, the d~rk
decay speed o~ the resulting photosensitive ~terlal
is controlled in a range sui.table for application to
the repe~ted copying oper~tion and the residual
potential c~n be reduced to a negligible le~el~ whereby
occurrence OI fogging can be prevented, the toner
trans~er efficiency can be improved and the li~e of the
10 ~otosensitive material c~n be prolonged. It ~lso wa~
~cund that a photosensitive m~terial having this
l~minate structure is excellent in mechanic~l~ che~ic~l
and e1ectric durabilities.
More specificallyi in accord~nce wit~ thi~ i~ven-
15 tiont t}~ere is provided a photosen~itive ma~eri~l ~for -- .
electrophotography which comprise~ an electrieally
eonductive substrate, an intermediate lay~r fc~rmed on
said sub~trate ~nd a top layer laminated on said
intermed~a~ layer. wh~erein said intermediate layer
comprises ~A) an org~nic polymeric photocondùctor and
(B) an elec~ron-accep~able polycyclic arQmatic nitro
compound at an (A)/~B) weight ratio of ~rom 6/~ to 1~6
and said top layer comprises, incorporated in a binder.
(C~ phthalocy~nine or a phth~310cy~nine derivative ~nd
25 (B) said elec~ron-acceptable polyc~rclic arom~tic nltro
compound ~t a (C)/(B) weight ratio of from 10/5 to 10/25.
L~L~ '
In this invention, a~ the or&anic polymeri c pho~o-
-- 6 --
conductor (~) con~tituting the inter~ediate l~yer,
there can be used any of organic polymeric subst~nc~3
having photoconductivity, for example, poly-N-vinyl--
carbazole, poly-N-acrylphe.nothiazine, poly-N~
acryloxyethyl)-phenothi~zine, poly-N-(2-acrylo~ypropyl~
phenothiazine, poly-N-allylcarbazQle) poly~N~2acrylo~y-
2~m~thyl-N~ethylcarbazole, poly-N-~2-p~Ylnyl~enzoyl~thyl~-
carbazolei poly-N-propenylc~rbazole, poly-N ~-~ethyl
acrylo~apropyloarbaæole, poly~N-acrylcar~zol~, poly-4-
10 vinyl~p-(N-carbazyl)toluene, poly(vl~ylanisolaceto-
phenone), polyindene and other known photoconducti~P
organlc polymeric substances. Polymerlc photo~o~ductor~
that are easily avail~ble ~nd ~re suit~ or attainin~
the ob~ect~ o~ thls inve~tion include poly-N vinylc~
ba~ole and ~uc~e~r ~ubstitution deriv~ti~e~ th~reo~
for ex~mple, h~logen- and al ~ l-substi~u~ed deriv~t~e~.
In this invention, as the phthalocy~ni~e or phth~loO
cyanine derivative constituting the top layer ~ the
lamin~ted photosen~itive material, there ~n be u~d
phthalocyanine and all o~ known ph~h~locya~ine deri~ati
havl~g photoconductivity, for e~mple7 alumi~m ~h~h~lo~
cy~nine, aluminu~ polychlorophthal~cy~nlne~ antim~ny
phthalocyanine, b~rium phth~locyanine, ~rylliu~
ph~halocyanine, cadmium he~decachlorophthaloc~y~in~9
cadmium phthalocyani~e, ceriUm phthalocy~nine, chro~iu~
phth~locyanine, cob~lt phth~locyanlne, cobQlt chloro-
phthalocy~nine, copper 4-aminophth~locy~nln~, Copper
bromochlorophthalocyanine, copper 4~hlorophth~10c~n~,
copper 4-nitrophthalocyarLine, copper ph-th~locy~?nine
phthalocy~nine sulfonate, cOpper polychloroph~alo-
cyanine, deuterio phth~locyanine~ dysprvsium pht~locya-
nine, erbium pht~halocyanine, europium pht:t~loc3r~nine,
5 ~3adolinium ph~alocyanine~ g~llium phth~locy~nin~,
germanium phthalocyanine, holmium phth~locyanine, i~dium
phthalocyanin~, iron phthalocyani~ ron polyhal~ph-
-th~locy~nine, lanthanLIm ph~alocy~ni~e, lead phth~lo~ya-
nine, lead polychlorophthaloc~rani~e~ cobalt h~ ph~yl-
10 phth~locyarllne, oopper perltpphenylphth~llocya~lne,lithlum phthQlocyanine9 ruthe~um phth~locyl~ni~e~
magnesium phthE~locyanin~g mQn~ane~ phth~locya~line~
marcury phthalooyanlne~ molybflenum phtl~lo~ya~i~e,
neodium phth~locyani~e~ nickel phthalocyanin~ nlck~l
polyh~lophthalo~yanine, osmium ph~locyanine, p~lladlu~
phthalocy~nine~ palladium chlorophthalocy~nine,
alkoxyphthalocy~nine, alkylaminophth~locyanlne,
lkylmercaptopht;halooyanine, aryloJ~yph th~locyel~n~
arylmercaptophthalocyanine, copper phthalocya~i~e
piperldine, cyclo~lkylaminophthalocyani.ne, dialkyl~ o-
phthalocyanine, diar~lkylaminopht~locy~nin~,
licyclo~lkyl~mi~oph~alocyanl~Le~ he~d~cahydroph~b~lo~
cyanine, imidomethylphth~locyPInins~ 1, 2-n~phthelloo3r~nis~,
2~-naphthalocyanine, octa-~zophthRlocyanine~ ~ul:eur
phthQlocyanine~ tetr~-~zoph~halocy~nine, tetra-4-
acetylaminophthalocyanine, tetra-4-amino~enz~ylphth~
; cyanine, tetra-4-~.mi~ophthalocyanlne, tetra~hlorcm~hyl~
phth~locyanine, tetr~-diazophth~locyanine, tetrA-4~ 4-
dimethylocta-azophthalocy-~nine, tetra-4~5~diphenylene-
oxide-phthalocyanine, -tetra-~!..5-diphenylocta-azoph-tha-
locyanine, te-tra-(6-methylbe.nzo-thiazoyl)phthalocyanine,
tetra-p-methylphenyl~minophth~locyanine, tetr~methyl-
phthalocynnine, -tetranaphthotri~zolylphth~locyanine,
tetr~-4-naph~thylph-th~locy~nine, tetra-4-ni-trophthalo-
cyanine, tetr~perin~phthylene-4,5-oc-ta-azophthalocyanine,
tetra-2,3~phenylene-oxide~phth~locyanine, tetra-4-
phenylocta-azophthalocyanine3 tetraphenylphthalocyanine,
te~tr~phenylphth~locyanine-tetracarbo~ylic acid,
tetraphenylphthalocyanine tetrabariumc~rboxylate,
tetraphenylphthalocyanine--tetra-4-trifluoromethylmer--
captoph-th.~locyanine9 tetr~pyridine-phthalocy~nine,
tetra~4--trif`luoromethylmerc~ptophthalocyanine9 tetra-4-
trifluorome-thylphthalocyarline-4~5-thionaphthene-octa-
azophthalocyanine, pl~tinum phthalocyanine, potassium
phthalocyanine9 rhodium phthalocy~ni.ne, s~marium
phth~locyanine, silver phthalocy~nine, silicon ph-thalo-
cyanine, sodium phthalocyanine, sulfonated phthalocyanine,
thorium phth~locyanine, thulium ph-thalocyanine, tin
chlorophthalocyanine, tin phthalocy~nine, titanium
phthalocyanine~ uranium phthalocyanine, v~nadium
phthalocyanine9 y-tteribium phth~locyanine, zinc
chlorophthalocya.nine~ zinc phthalocyanine, and dimers,
trimers9 oligomers, polymers ~nd copolymers thereof.
Phthalocyanine and phthalocyanine deriva-tives tha-t
are easily available and ~re especially suitable for
at-taining the objects of the present i.nvention include
me-tal-free phthalocyanines and the.ir nuclear substi-
-tution deriva-tives, for example, halogen-substituted deri-
vatives.
As the polycyclic aromatic nitro compound to be
corr.bined with the organic polymeric photoconductor (A)
and the phthalocyanine or phthalocyani.ne derivative (C)
in the intermediate layer ~nd top layer o~ the laminated
photosensi-tive mate.rial of this invention~ there can be
used any o~ polycyclic aromatic compounds having at
least one nitro group substituted on the nucleus, for
example, 2,4-dinitro-1-chloronaphthalene, 1,4-dinitro-
naphthalene9 1,5-dinitro.naphthalene, 3-nitro-N-butyl-
carbazole, 4-nitrobiphenyl, 4~4'-dinitrobiphenyl9
l-chloro-4-ni-troan-thraquinone, 2,7-dinitroanthra-
quinone, 2~4~7--trinitrofluorenone, 2,4~5,7-tetranitro-
~luorenone, 9 dicyan.omethylene-2,4,7-trinitrofluorenorle
and 4~nitroacenapht~lene.
Polycyclic aroma-tic nitro compounds that are
; suitable ~or attaining the objects of this invention
: 20 include trini-trofluorenone and tetrani-trofluorenone.
In -the lamina-ted photosensitive ma-terial o~ this
invention, it is impor-tant that -the phthalocyanine or
phthalocyanine derivative (C) and the polycyclic aroma-tic
nitro compound (B) should be incorporated in a binder
at a (C~/(B) weigh-t ra-tio of ~rom 10/5 to 10/25, prefer-
ably from ~.0/8 -to 10/20.
It is known that the phthalocyanine or phthalocya-
nine derivative (C) is used in combination wi-th the
polycyclic aroma-tic nitro compound (B) for a pho-tocon-
duc-ti~e layer. ~n known photosensi~tive materials,
howeverg ~the polycyclic arom~tic compound is used in
an amoun-t much sm~ller than the amoun-t specified in
this inven-tion. When the polycycli.c aromatic nltro
compound is used in an amount smalle.r than the amoun-t
specified in this invention, as will be apparent from
Compar~tive Example 1 and Table 1 given hereinafter9
the dark decay speed is -too low and the residual
potential is at a level -that cannot be neglected.
Therefore, in this photoconductive layer9 fogging is
readilv caused at the high-speed repeated copying
operation and since a large load is imposed on the
photoconductive layer at the clea~ing step9 the
resistance -to -the copying operation ( the frequency of
the repeated copying Operatiorl that the phot.osensitive
materi.al can resist ) is drastically lowered When -the
polycyclic arom~tic compound i~s used in an amount larger
than the ~mount specified in this invention, as will be
apparent from Comparative Example 2 and Table 1 given
hereinafter, the residual poten-tial ca.n be reduced
substantially to zerO, but -the dar~ decay speed is too
high and it is difficult to obtain a copied image having
high contras-t a.nd density. In con-trast9 if -the mixing
ratio of -the polycyclic aromatic nitro compound to the
ph-thalocyanine or phthalocy~nine derivative is adjusted
withi.n -the above men-tioned r~nge according -to this
invention, at -the high-speed repeated copying opera-tion,
4'~
the residual potential can be reduced to a negligible
level and the d~rk dec~y speed c~n be controlled so
tha-t the po-tential is ~bruptly lowered during a period
ranging from the toner transfer step -to -the point of
initiation of the cleaning operation. Therefore9 accor~
ding to -this inven-tion9 i-t is possible to attain ef~ec-ts
of improving the toner image -transfer efficiency,
facili-ta-ting -the cleaning operation, preventing occurrence
of fogging and improving the resis-tance to the copying
OperatiOn concurrently.
This functional effect tha-t when the polycyclic
aromatic nitro compound is combined with the phthalo-
cyanine or phthalocyanine drivative at the above-mentioned
specific mixing ratio9 the polycyclic aromatic nitro
compound ac-ts as a dark decay speed controlling agent
for the phthalocyanine or phthalocyanine deriva~tive is
a novel e~fect found by us for the first -time.
As the binder for dispersing -therein the phthalo-
cyanine or ph-thalocyanine derivative and the polycyclic
aroma-tic ni-tro compound9 there can be used any o~ known
polymeric binders, especially electrically insulating
binders. More specifically, there can be used~ for
example, acrylic resins such as polyacrylic acid esters,
polymethacrylic acid esters, acrylic acid/methacrylic
acid es-ter copolymers, acry].ic acidlstyrene copolymers
and mal.e.ic anhydride/s-tyrene/methacrylic acid ester
copolymers, vinyl aroma-tic polymers such as polystyrene
and poly-me-thylstyrene, vinyl chloride resins such as
- 12 -
34~
vinyl chloride/vinyl acetate copolymers9 partially
saponi~ied vinyl chloride/vinyl aceta-te copolymers9
partially saponified and ace-talized vinyl chloride/
vinyl acetate copolymers and vinyl chloride/vinyl
ace-tate/maleic anhydride copolymers, vinyl ester
polymers such as polyvinyl aceta-te9 butadiene copolymers
such as styrene/butadiene copolymers and acrylonitrile/
styrene/butadiene copolymers, olefin resins such as
ethylene/vinyl acetate copolymers9 ethylene/acrylic
~cid copolymers and ionomers, polyester resins such as
ethylene/butylene-terephthalate/isophthalate~ polyamide
and copolyamide resins9 polycQrbonate resins9 unsaturated
polyester resins9 urethane resins such as acrylic
: ure-thane9 epoxy resins7 phenol-formaldehyde resins~
xylene resins and melamine-formaldehyde resins. These
binders may be used singly or in the form of a mixture
of two or more of -them. It is preferred -that the
electric resistance ( volume resistivity ) of the
binder used be a-t least 1 x 1011 52 -cm. In order to
attain the objects of this invention, it is especially
preferred to use an acrylic resin as a binder.
: The amount used of the binder is not particularly
critical in this inven-tion9 but in general9 it is
preferred th~t the binder be used :in an amount of lO0
to lO00 parts by weight, especi~lly ~00 to 500 parts by
weight9 per lO0 parts by wei.ght of the phthalocyanine
or ph-thalocyanine derivative (C).
In -this invention9 it is preferred that a silicone
- 13 -
oil be incorporated in the -top lPyer comprising -the
ph-thalocyan:ine or phthalocya.nine derivative9 the poly-
cyclic aromatic nitro compound and the binder. We
found -th~t when a silicone oil is incorpora-ted in the
5 top layer, during the exposure and developing steps the
dar~ decay speed can be maintained at a relatively low
level and ~t the subsequent tr~nsfer or cleaning step
the dark decay speed can be elevated at an extremely
high level to thereby reduce drastically the residual
poten-tial on the non-exposed ~re~. According to this
preferred embodiment9 ~ccumulation o~ charges can be
effectively prevented and there can be at-tained
prominent effects of preventing occurrence of fogging,
i~lproving the toner transfer ef~iciency9 preventing
occurrence of insulation breakdown and improving
the ~d~ptability -to the cle~ni.ng oper~.tion. Still
further, in this preferred embodimentg the coating
OperQtion c~n be remarkably f~cilitated and the
smoothness of -the coating l~yer can be prominently
improved.
As the silicone oil that can be used in -this inven-
tion~ there can be mentioned, for examplel polydimethyl~
siloxane, polymethylphenylsiloxane, polyhydro~iene-
methylsilo.xalle, polyme-thyl~minopropylsiloxane, their
~5 copolymers, and dimethylsiloxane/ethyle.ne oxide block
copolymers. Polydimethy~.siloxa.ne is especially preferred
because it is easily avail~ble and is sui-table ~or
attaining the objec-ts of this invention.
4~
The arrlount incorporated of the silicone oil may
be changed in fl broad range9 but in general~ ln order
to a-ttain the objec-ts of this invention ad-vantageously,
it is preferrecl that the silicone oil be incorporated in
an amount of 5 to 150 parts by weight9 especially 25
to 85 parts by weight 9 per 100 parts by weight of the
: phthalocyani.ne or phthalocyanine derivative (C).
In -this invention, it is ~ery impor-t~nt that an
intermediate layer comprising the above-men-tioned
organic polymeric photocon~uctor (A) and polycyclic
aromatic nitro compound (B) ~t ~ specific mixing ratio
should be interposed be-tween the electrically conductive
substrate and the top layer ( first photoconduc-tive
layer ) comprising the above~mentioned phthalocyanine
or phthalocyanine derivative9 polycyclic aromatic
;~ nitro compound and binder. More specifically, in case
- of a photosensitive pla-te formed by laminatlng a
photoconductive layer comprising the above-mentioned
phthalocyanine or phthalocyanine derivative, pOlycyCliC
aromatic nitro compound and binder directly on an
elec-trically conductive substra-te, as will be apparent
from Comparative Example 5 ~nd Table 1 given hereinafter,
the primariy surface potential ( the surface potential
of -the pho-tosensitive m~terial af-ter charging but
be.~ore exposure ) is considerably low, the rising
speed of -the surface potential is low and the sensitivity
expresse~ by -the half li.fe ( seconds ) of light decay
is considerably low. Thus, -this comparative photosensi-
- 15 -
,
tive material is still insuffici~nt in various points.
In con~rastJ when a layer (second photoconduct;ve
layer) comprising the above-mentioned organic polymeric
photoconductor (A) and polycyclic aromatic nitro compound
(B) is disposed between the top layer ~fi.rst photo-
conductive layer) and the electrically conductive
substrste according to this invention, the foregoing
properties can be remarkably improved witllout any bad
: influence on dark decay characteristics, which will
readily be understood when results of Comparativ0 E~am-
ple 5 are compared with results of Example 1 o this
nventlon .
It also is very impor~ant that in the intermediate
layer of the photosensitive material of this invention,
.-: the organic polymeric photoconductor (A) should be
combined with the polycyclic aromatic nitro compound
(B) at an ~A)/(B) mixi.ng weight ratio of from 6/1 to
1/6, especially from 1/1.7 to 1/2.2.
; It is known that a polymeric photoconductor as
an electron donor and a polycyclic aromatic nitro
compound as an electron acceptor form a complex and a
sensitized photoconductlve layer can be formed from
these two compounds. In the intermediate layer of
this inventi.on, the palycyclic aromatic compo~md performs
a function of controlling the charge characteris~ic of
the surface of the photosensitive material, namely the
first photoconductive layer3 when incorporated in the
above-mentioned specific amount. When the amount of
- 16 -
g4'~
the polycyclic aromatic nitro compound incorporated
in the intermedia-te layer is smaller than the above
~mou.nt speclfied in -this invention, as ~.~ill be appQrent
from Comp~rative Example 3 and Table l given hereinafter,
during -the repeated copy.ing operation the residual
potentiaL is accumula-ted on -the sur~ace o~ the photo-
sensi-tive material9 causing fogging, electric deteriora-
:~ tion ol the photoconductive layer and dras-tic reduction
` o:f the resistance to the copying operation. When~the
amount of the polymeric photoconductor is larger tha:n;
the amount specified ln this invention, as will be
apparent from Comparative Ex~mple 4 and Table 1 given:
herel.~after9 the primary surface po~ential ls dra:stically
; reduced and the rising speed of the surface potential:~ :
is low. Accordingly9 i-t is di~icult to obtain satis~
: factory cop~ed;~1ma~g~es.~ In~contrast9 when -the:polymèrio
photoconductor is combined wi-th ~he polycyclic arom~tic;~
nitro compound~at the aboye-mentioned specl~ic walght : ;
1~,; : ~ :: :~
r~tio accord1ng to this inven-tion, -the charge charac~
:20 teristics of the surface of the photoconductivq layer
can be controlled so tha-t the residual potential~can ~ ~
be reduced to a: level -th~t can be~neglected;whlle ~ :
elevating the primary surfacej~potential a~d the speéd~
~:: of rising of the sur~ace potentlal by charging to ;
~ 25 sufficien~ly high LeveLs a.nd bad ln.fluenoes owing -~o ;~
accumu~a-tion o~ the residual potential can be effect-
~ ive].y eleimina-ted
:~ I.n -this inven-tion~ a foil or plate of copFer,~
~ 17 - :~ :
:
, .
, ~ . ,
aluminum~ si']ver9 tin or iron, which is ~ormed into a
sheet or druIll9 is used as -the elec-trically conduc-tive
substrate. Further9 a product formed by depositing such
me-tal in the form of a thin film on a plastic film or
the like by vacuum deposition, non-electrolytic plating
or like means can be used as -the electrically conductive
s~1bstra-te.
ln ~eneral9 the lamin~ted photosensi-tive material
: of -this inventioh is prepared by a process comprising
'~ 10 coati.ng a solution containing the organic polymeric
photoconduc-tor (A~ and the polycyclic aromatic nitro
compound (B) a-t the above-men-tioned specific ra-tio on
an electrically conductive subs-trate such as mentionecl
above -to form an in-termedia-te layerg d.rying the so coa-ted
: .
in-termediate layer9 coating a liquid composition
~; comprisi.. ng9 incorpora-ted in ~ binder such as mentioned
above9 the phthalocyanine or ph-thalocyanine derivative
(C) and -the polycyclic arom~tic nitro compound (B) at
the above-me.nt.ioned speci:Eic ratio on the intermedia-te
: 20 layer9 ~nd drying -the coa-ting according -to need.
As the solven-t for preparing a coating composition
for the intermediate layer9 there can be used, for
example~ aroma-tic hydrocarbon solvents such as benæene9
toluene and xy.l.ene9 cyclic e-thers such as dioxane and
tetrah~dro:~uran~ Ice-tones such as acetone9 methylethyl
~etone9 methylisobu-tyl ketone and cyclohexano.ne,
~¦~ohol.s such as d:Lacetone alcohol and ethylene glycol
iso'bu-tyl ether9 and alicyclic hydrocarbons such as
- 18 -
cyclohe-Yane. These solven-ts may be used singl.y or in
-the form oL a mixture of two or more of -them.
In gener~].9 it is preferred that -this co~-ting
composition be applied to the elec-trical~Ly conductive
5 subs-trate at a solid concentration of 1 to 80 % by
weight 9 especialLy 5 to 30 % by weigh-t The coated
c~Jmposi-tion is ordi.narily dried a-t a -temperature of
1(1 -to 200`C. -to form an intermediate layer.
In the above process, a complex is formed from the
~ 10 organic polymeric pho-toconductor (A) and -the polycyclic
; arom~tic nitro compound (B) in -the coating solution.
In -this i.rIvention9 i-t also is possible to adopt a process
: in which a solution of the organic polymeric pho-to-
; Gonductor (A) and a soIution of the polycyclic aroma-tic
nitro compound (B) are prepared separatel~, the respect-
ive solutions are co~ted on the electrically conduc~tive
: substra-te in this order or reverse orcler and a complex
is formed direc-tly OLl -the elec~trical~Ly conduc-tive
substra-te~ In -this case, even if -the complex layer is
no-t formed uniformly throughou-t -the in-termediate layer,
no particular disadvantage is brought about.
.. In general9 a coa-ting composition for f~rming the
top layer is prep~red by dissolving a binder such as
men-tioned above in one or more o.~ -the above-men-tionecl
orgarlic solvents, di.spersing or dissolving ~the
phthalocyanine or phthalocyanine derivative and ~the
po1ycycL:i.c aroma-tic .ni-tro compound into the binder
solution, ~nd homogenizing -the resulting dispersion or
- 19 -
. ,
.
~ . .
soli,ltion. I'~rom -the vi,ewpoint of the adap-tabili-ty to
the coa-ting Operat:iOn9 i-t is generally preferred that
the sol.id Co.nCen~tra~tiO!rl of this coating composi-tion
be 1 -to 80 ~0 by weight9 especial]y 5 -to 30 % by weight.
In forming -the top layer9 i-t is preferred that
the -~ol.lowirlg be -taken in-to considera~t.ion. Name'ly9
i.t is preferred -to selec-t as -the solven~t of the -top
; ]~yer-forming coati.ng composi-tion a solvent that does
: .no-t sw'bstant:ially dissolve ~ complex formed from the
]o organic polymeric pho-toconductor and polycycli.c
aromatic nitro compound constituting the intermedia~te
: ~ayer. Of course7 i-t is permissible -to use a solvent
capa'ble of subs-tantially dissolving the intermediate
l,ayer :~or the -top layer-forming coating composition.
In this case9 however9 it is preferred -tha-t the -top
layer~ormi.ng composition be so].idif'ied within 5 minutes,
especia'lly 1 minute.
ln the l.aminated photosensitive material o~ this
:inve.n-tion9 it, is preferred th~t the thickness of ~he
i.ntermediate l.ayer be 0.1 -to 10 ~9 especially 1 -to 8 ~9
and that the thickness of the -top layer be 0.1 -to 30 ~9
especially ~L to 15 ~. If the thickness of the inter-
mediate layer .Ls smaller than 0.1 ~9 -the primary
sur~a~.e po~ten~tia'l. or rising speed -thereo:f is of-te.n too
].ow~ and if ~I;he thickness of -the lntermedia-te layer is
]arger -than 10 ~9 -the residual po-tential is at a level
that cannot be neglected and occurrence of fogging or
reduc-tio.n of -the res:is-tflnce -to the copying oper~-tion
- 20 -
:
.
~9~
i5 readily caused. When -the -thic~ness of the top layer
is smaller -than 0.1 ~9 -the prirnary surface potential or
rising sp~ed -thereof is of'-ten too low9 ~nd when -the
thic'knes.-i o~ the -top layer is larger -than 30 ll9 ~the
sensitivl~ty, i.e~9 the light decay speed9 is reduced and
:insulation breakdo~/n is reaclily caused~
In the laminated photosensitive rnaterial of this
invention9 as described hereinbefore9 electric charac-
teristics and photoconductive characteristics at the
repeated copying oper~-tion can'be remarkably improved9
and further~lore9 mechanical properties such as the peel
reslstance can be prominently improved. More specifi-
cally9 al-though in case of a photosensitive material
formed by applying a pho-toconductive layer comprising
the above-mentioned phthalocyanine or phthalocyanine
derivative9po]ycyclic aromatic nitro compound and
binder direc-tly -to a me-tal substra-te9 the photoconductive
layer is read:ily peeled off at a pressure-sensitive tape
peel tes~t described hereinafter, in case of -the laminated
pho-tosensi-tive material of this :Lnvention, peeling of
-the photoconductive layer is not caused at all at the
same -tes-t. Thus~ it -~ill readily be understood that in
-the lalnina-ted photosensi-t,ive material of this inven-
-tlon9 also -the mechanic~1 proper-ties are remarkably
improvecl.
The laminated photosensi-tive materi.al of this in-
ven-tion i5 espeCia~lly va]u~ble and useful as a pho-to-
sen,si-tive ma-terial for ~n elec-tropho-tographic copying
- 21 -
..: .
~lg4(~
machine in which the surface of the photosensitive
material is positively charged and the photosensitive
material is used repeatedly for the copying operation.
This invention will now be described in detail
by reference to the following Examples that by no means
limit the scope of the invention.
Example 1
In tetrahydrofuran were homogeneously dissolved
10 g of polyvinylcarbazole (hereinafter referred to
as "PVX") (Luvican* M-170 manufactured by BASF AG.
and 20 g of 2,4,7-trinitrofluorenone (hereinafter
referred to as 'ITNF''), and the solution was coated
on an aluminum foil having a thickness of 40 ~ so that
t~e dry thickness was 4 ~, whereby an intermediate layer
was formed. Then, 3 g o~ Phthalocyanine Blue therein~
after referred *o as "PC") (Heliogen Blue 7800
manufactured by BASF AG.), 3 g of TNP and 35 g of an
acrylic resin~(FR-1112D manufactured by Mitsubishi
:
Rayon K. K., solid content = 40% by weight) were
homogeneously dispersed in 139 g of toluene, and the
dispersion was coated on the intermediate layer so
that the dry coating thickness was 10 ~ as a whole.
Then, the coating was dried at 100C. for 10 minutes.
Thusg a photosensitive plate of the present invention
was prepared.
Comparative photosensitive plates were prepared
for evaluating the properties of the photosensitive
plate o~ this invention.
~'
:
~ ~ *Trademark - 22 -
4'~
Comparative Example 1
_.
A photosensitive plate was prepared in the si~me
manner as described in Example 1 except that the amount
of TNF in the top layer-forming coating composition
was changed to 0.3 g.
Com~arative Example 2
A photosensitive plate was prepared in the same
manner as described in Example 1 except that the amount
of TNF in the top layer-forming coating composition
- 10 was changed to 10 g.
Comparative Example 3
A pho$osensitive plate was prepared in the same
manner as described in Example 1 except that the i~mount
of TNF in the intermediate layer-forming coating
composition was changed to 1 g.
Com~arative Example 4
A photosensitive pla~e was prepared in the same
manner as described in Example 1 except that the amount
of TNF in the intermediate layer-forming coating
composition was changed to 100 g.
Comparative Example_5
In 139 g of toluene were homogeneously dispersed
3 g of PC, 0.5 g of TNF and 35 g of an acrylic resin
(FR-1112D), and the dispersion was coated on an
aluminum foil having a thickness of 40 ~ so that the
dry thickness was the same as in F.xample I tlO ~).
Then, the coating was dried at 100C. for 10 minutes
to form a photosensitive plate.
- 23 -
..~"
'
The ~photosensitive pl~te obtained in Example 1
was tested by usi.ng a -tester of'-the posi-t.ive charging-
eA;:-oosure-developirlg-trans~er-fixirlg type. Clear images
having ~ h:igh resolving power were o'btained9 Several
: 5 thousarld prints coulcl be obtained when the copying
opera-tion was repea-ted by using -th.is pho~tosensi-tive
pl,a-te.
Electric c:haracteristics of the photosensitive
plate ob-tained in Example 1 were examined by using an
elec-trosta-tic paper arlalyzer manufactured'by Kawaguchi
De.nki. K. K~. -to obtai.n results shown in Table l r
The compara-ti~e pho-tosensitive pla-tes were similarly
sub~jected to the COpyi,Llg test and -their electric
properties were similarly examined. Obtai.ned results
; 15 are shown in Table 1.
, :
~;~ 20
- 24 -
:
<IMG>
- 25 -
Notes
Sharpness:
Reproducibility of fine lines, meshes, half-tones and small let-
ters, which was evaluated according to the following scale:
O : good
: slightly bad
X : bad
Density:
The density of the image area ~non-exposed area), which was evalu-
ated according to the following scale:
O : dense
A slightly thin
X : thin
Fo~ging:
Contamination of the background in the non-image area (exposure
area), whicll was evaluated according to the following scale:
: not observed
~ A slight
X : conspicuous
20: Cleaning~Property:
Easiness in removing the toner left on the photosensitiv~e plate
after transfer, which was evaluated according to the following scale:
: very easy
: slightly diffic.ul~
X : difficult
y~ Operation:
The number of good quality prints obtained at the repeated copying
operation, which was evaluated according to the following scale:
O : more than 1000 prints
~ : 500 - 1000 prints
6 -
3~9~
X: less than 500 prints
Transfer Efficiency:
The ratio of the toner transferred to copying paper after develop-
ment, which was evaluated according to the ollowing scale:
O : more than 80% of the toner was transferred
: 50 to 80% of the toner was transferred
X : less than 50% of the toner was transferred
Conditlons for Measurements bv Electrostatic PaPer Analyzer:
40 Lux
Char~e: 5 KV (positive)
Sensitivity: quantity of light tlux.sec) at which the potential
just before exposure decayed to 1/2, which was determined according to the
static method
Init al potential- saturation charge voltage (V) as determined ac-
cording to the static method
~ 3!~9~ Y~ saturation voltage (V) observed when charging was
effected for 10 seconds, which was determined according to the dynamic method
Residual potential: voltage ~V~ observed 3 seconds after exposure,
which was determined according to the static method
~ y average value of the potential decay ~V/sec) over a
period of 3 seconds from charge-off, which was determined according to the
static method
Adhesiveness:
The adhesion strength of the photosensitive layer to the aluminum
substrate (the peel resistance observed when a pressure-sensitive adhesive
tape was applied to the photosensitive layer and the tape was then peeled
off)~ which was evaluated according to the following scale:
O : strong
~ : ordinary
X : weak
- ~7 -
,
4~
Exam~e 2
In 80 g of a mixed solvent of toluene~cyclohexallone (3/1 weight
ratio) were homogeneously dissolved 10 g of PVK (Tuvical* 210 manufactured
by Takasago Koryo K. K.) and 10 g of TNF, and the solution was coated o,n
aluminum foil having a thickness of 40 ~ so ~hat the dry thickness was 5 ~,
whereby an intermediate layer was formed. Then~ 3 g of Phthalocyanine Blue
(Heliogen Blue 7800 manufactured by BASF AG.), 4 g of TNF and 30 g of an
acrylic resin tAcrydic* A-196 manufactured by Dai-Nippon Ink Kagaku Kogyo
K. K., solid content = 50%) were homogeneously dispersed in 100 g~o tol-
uene, and the dispersion was coa~ed on the intermediate layer so ~hat the
dry coating thickness was 10 ~ as a whole. The coating was then dried at
100C. for lO minutes to obtain a pho*osensitive plate.
When this photosensitive plate was tested in the same manner as
described in Example 1, good results similar to the results obtained in Ex-
' ample 1 were obtained.
Example 3
A photosensitive plate was prepared in the same manner as de-
scribed in Example 1 except that an epoxy resin ~Epikote* 1009 manufactured
by Shell Chemical Co.) was used instead of the acrylic resin in such an
amount that the amount of the solids was the same as in the acrylic resin
used in Example 1 and acetone was used as the solvent instead of toluene.
When this photosensitive plate was tested, good results similar to the re-
sults obtained in Example 1 were obtained.
A photosensitive plate was prepared in the same manner as de-
scribed in Example 1 except that a polyester resin tVylon* lI3 manufactured
by Toyo Boseki K. K.) was used instead of the acrylic resin used in Example
l. When this photosensitive plate was tested, good results similar to the
results obtained in Example 1 were obtained.
*Trademark - 28 -
:
9~
Exa~ple 5
When a curing agent (Epicure* manufactured by Shell Chemical Co.)was added in forming the top layer in Example 3 in an amount of 5% by weight
based on Epikote 1009~ -the durability was further impr~ved in the resulting
photosensitive plate.
Example 6
A photosensitive plate was prepared in the same manner as de-
scribed in Example 1 except that 1 g of a silicone oil (KF-96 manufactured
by Shinetsu Kagaku Kogyo K. K.) was added to the ~op layer-forming coating
composition. When ~his photosensitive plate was tes~ed in the same manner
as described in Example 1, it was found that the resistance to the copying
operation and the cleaning property of this photosensitive plate were fur-
ther improved over the photosensitive plate obtained in F.xample 1.
Example 7
A photosensitive plate was prepared in the same manner as de-
scribed in Example 1 except that in the intermediate layer-forming coating
composition, TN~ was replaced by the same amount of 2,4,5,7-tetranitro-
fluorenone. ~len this photosensitive plate was tested in the same manner as
described in Example 1, good results similar to the results obtained in Ex-
ample 1 were obtained.
A photosensitive plate was prepared in the same manner as de-
scribed in Example 1 except that in the intermediate coating-forming composi-
tion, poly~N-2-acrylcarbazole was used instead of PVK. When this photosensi-
tive plate was tested, good results similar to the results obtain0d in Ex-
ample 1 were obtained.
Example 9
A photosensitive plate was prepared in the same manner as de-
scribed in Example 1 except that Resino Blue RSP (copper phthalQcyanine
manufactured by Resino Color Kogyo K. K.) was used instead of Heliogen Blue
; *Trademark - 29 -
`?`J
~ 9~
7800. When this photosensitive plate was tested in the same manner as de~
scribed in Example 1, good results similar to the results obtained in Ex-
ample 1 were obtained.
: - 30 -
