Electrophotographic photosensitive material containing hydrazone compound

An electrophotographic photosensitive material is disclosed, wherein the electrophotographic photosensitive material comprises a photosensitive layer containing at least one hydrazone compound selected from the group consisting of compounds having the general formulae (I) and (II): ##STR1## wherein R.sup.1 is a hydrogen or halogen atom or an alkyl group, an alkoxy group, a nitro group, an acyl group or an amino group and R2 and R3 each represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group; ##STR2## wherein R.sup.4 and R.sup.5 each represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group and X is a group of the formula ##STR3## in which R.sup.6 to R.sup.18 each represents a hydrogen or halogen atom or a hydroxy group, an alkyl group, an alkoxy group, an allyl group, an acyl group, an acyloxy group, an alkoxycarbonyl group, an aryl group, a cyano group, a nitro group, an amino group, an alkylamino group or an arylamino group and n is an integer of 1, 2, 3, 4 or 5.

FIELD OF THE INVENTION 
This invention relates to an electrophotogrpahic photosensitive material. 
More particularly, it relates to an electrophotographic photosensitive 
material which contains a specific hydrazone compound in the 
photosensitive layer formed on an electroconductive substrate. 
BACKGROUND OF THE INVENTION 
Photosensitive materials so far used in electrophotographic photosensitive 
materials (hereinafter also referred to as photosensitive materials) 
include inorganic photoconductive substances, such as selenium and 
selenium alloys, dispersions of inorganic photoconductive substances, such 
as zinc oxide and cadmium sulfide, in resin binders, organic 
photoconductive substances, such as poly-N-vinylcarbazole and 
polyvinyl-anthracene, organic photoconductive substances, such as 
phthalocyanine compounds and bisazo compounds, and dispersions of such 
organic photoconductive substances in resin binders. 
Photosensitive materials are required to have the function of holding 
surface charges in the dark, the functon of receiving light and generating 
charges and the function of receiving light and transporting charges. 
There are two kinds of photosensitive materials, namely the so-called 
monolayer type photosensitive material consisting of one single layer 
having all the three functions and the so-called laminate type 
photosensitive material composed of functionally distinguishable layers, 
namely a layer which contributes mainly to charge generation and a layer 
which contributes mainly to retention of surface charges in the dark and 
charge transport upon receiving light. In electrophotographic image 
formation using these photosensitive materials, the technique of Carlson, 
for example, is applied. Image formation by this technique includes 
charging of the photosensitive material by corona discharge in the dark, 
formation of latent electrostatic images (e.g. letters, pictures) by 
illumination of the charged photosensitive material surface, development 
of the latent electrostatic images thus formed with a toner and fixation 
of the developed toner images on a supporting material, such as a paper 
sheet, following transfer thereto. After toner image transfer, the 
photosensitive material is subjected to the steps of charge removal, 
removal of remaining toner (cleaning), neutralization of residual charge 
by means of light (erasure), and so on, and then submitted to reuse. 
In recent years, electrophotographic photosensitive materials in which 
organic materials are used have been put to practical use because of their 
advantageous features such as flexibility, thermal stability and film 
forming property. Thus, for example, there may be mentioned photosensitive 
materials comprising poly-N-vinylcarbazole and 2,4,7-trinitrofluoren-9-one 
(described in U.S. Pat. No. 3,484,237), photosensitive materials in which 
an organic pigment is used as the main component (described in Japanese 
Patent Application (OPI) No. 37543/1972) (the term "OPI" as used herein 
means "unexamined published Japanese Patent Application") and 
photosensitive materials in which a eutectic complex is used as the main 
component (Japanese Patent Application (OPI) No. 10735/1972). A number of 
novel hydrazone compounds have also been put to practical use. 
However, although organic materials have a number of advantageous features 
as compared with inorganic materials, none of organic materials can fully 
meet all requirements set forth with respect to the characteristic 
properties of photosensitive materials for electrophotography. Organic 
materials are still unsatisfactory particularly in respect of 
photosensitivity and of characteristics at the time of continuous repeated 
use. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the invention, which has been made in view 
of the foregoing, to provide a photosensitive material for use in 
electrophotographic copies and printers, which has high sensitivity and 
shows good characteristics in repeated use, through the use, as a charge 
transporting substance in the photosensitive layer, of a novel organic 
material that has not yet been used. 
In accordance with the invention, the above object is achieved by using an 
electrophotographic photosensitive material which has a photosensitive 
layer containing at least one hydrazone compound selected from the group 
consisting of the following structural formulas (I) and (II): 
##STR4## 
wherein R.sup.1 is a hydrogen or halogen atom or an alkyl group, an alkoxy 
group, a nitro group, an acyl group or an amino group and R.sup.2 and 
R.sup.3 each represents a substituted or unsubstituted alkyl group or a 
substituted or unsubstituted aryl group; 
##STR5## 
wherein R.sup.4 and R.sup.5 each represents a substituted or unsubstituted 
alkyl group or a substituted or unsubstituted aryl group and X is a group 
of the formula 
##STR6## 
wherein R.sup.6 to R.sup.18 each represents a hydrogen or halogen atom or 
a hydroxy group, an alkyl group, an alkoxy group, an allyl group, an acyl 
group, an acyloxy group, an alkoxycarbonyl group, an aryl group, a cyano 
group, a nitro group, an amino group, an alkylamino group or an arylamino 
group and n is an integer of 1, 2, 3, 4 or 5.

The three embodiments shown differ in mode from one another. In the 
figures, an electroconductive substrate is indicated by reference number 
1, a charge generating substance by 3, a charge generating layer by 4, a 
charge transporting substance by 5, a charge transporting layer by 6, a 
covering layer by 7, and a photosensitive layer by 20, 21 or 22. 
DETAILED DESCRIPTION OF THE INVENTION 
the formula (I), the alkyl group represented by R.sup.1 is preferably an 
alkyl group having from 1 to 10 carbon atoms, and more preferably from 1 
to 5 carbon atoms, for example, a methyl group, an ethyl group, a propyl 
group, or a butyl group, etc.; the alkoxy group represented by R.sup.1 is 
preferably an alkoxy group having from 1 to 10 carbon atoms, and more 
preferably from 1 to 5 carbon atoms, for example, a methoxy group, an 
ethoxy group, a propoxy group, etc.; the amino group represented by 
R.sup.1 is an amino group having from 0 to 10 carbon atoms, and more 
preferably from 0 to 6 carbon atoms, for example, an amino group, a 
diethylamino group, etc.; and the acyl group represented by R.sup.1 is 
preferably an acyl group having from 1 to 6 carbon atoms, and more 
preferably from 1 to 3 carbon atoms, for example, a formyl group, an 
actetyl group, a propionyl group, etc.; the halogen atom represented by 
R.sup.1 is preferably a chlorine atom; bromine atom, etc. 
The alkyl group represented by R.sup.2 and R.sup.3 is preferably an alkyl 
group having from 1 to 10 carbon atoms, and more preferably from 1 to 5 
carbon atoms, for exmaple, a methyl group, an ethyl group, a propyl group, 
etc.; the aryl group represented by R.sup.2 and R.sup.3 is preferably an 
aryl group having from 6 to 12 carbon atoms, for example, a phenyl group, 
a naphthyl group, etc. 
Examples of preferred substituent of the substituted alkyl group 
represented by R.sup.2 and R.sup.3 include an aryl group preferably having 
from 6 to 12 carbon atoms; an alkoxy group preferably having from 1 to 5 
carbon atoms; and a halogen atom, such as a chlorine atom, a bromine atom, 
etc. 
Examples of preferred substituent of the substituted aryl group represented 
by R.sup.2 and R.sup.3 include an alkyl group preferably having from 1 to 
5 carbon atoms; an alkoxy group preferably having from 1 to 5 carbon 
atoms; and a halogen atom such as a chlorine atom, a bromine atom, etc. 
R.sup.2 and R.sup.3 may be the same or different. 
In the formula (II), the alkyl group represented by R.sup.4 and R.sup.5 is 
preferably an alkyl group having from 1 to 10 carbon atoms, and more 
preferably having from 1 to 5 carbon atoms, for example, a methyl group, 
an ethyl group, a propyl group, etc. The aryl group represented by R.sup.4 
and R.sup.5 is preferably an aryl group having from 6 to 12 carbon atoms, 
for example, a phenyl group, a naphthyl group, etc. 
Examples of the substituents of the substituted alkyl group and the 
substituted aryl group represented by R.sup.4 and R.sup.5 include the same 
as those represented by R.sup.2 and R.sup.3. 
The alkyl group represented by R.sup.6 to R.sup.8 is preferably an alkyl 
group having from 1 to 10 carbon atoms, and more preferably having from 1 
to 5 carbon atoms, for example, a methyl group, an ethyl group, a propyl 
group, etc.; the halogen atom represented by R.sup.6 to R.sup.18 is 
preferably a chlorine atom, a bromine atom, etc.; the alkoxy group 
represented by R.sup.6 to R.sup.18 is preferably an alkoxy group having 
from 1 to 10 carbon atoms and more preferably having from 1 to 5 carbon 
atoms, for example, a methoxy group, an ethoxy group, a propoxy group, 
etc.; the acyl group represented by R.sup.6 to R.sup.18 is preferably an 
acyl group having from 1 to 10 carbon atoms, and more preferably from 1 to 
5 carbon atoms, for example, a formyl group, an acetyl group, a propionyl 
group, etc.; the acyloxy group represented by R.sup.6 to R.sup.18 is 
preferably an acyloxy group having from 1 to 10 carbon atoms, and more 
preferably from 1 to 5 carbon atoms, for example, a carboxy group, an 
acetoxy group, a propionyloxy group, etc.; the alkoxycarbonyl group 
represented by R.sup.6 to R.sup.18 is preferably an alkoxycarbonyl group 
having from 2 to 10 carbon atoms, and more preferably from 2 to 5 carbon 
atoms, for example, a methoxycarbonyl group, an ethoxycarbonyl group, 
etc.; the aryl group represented by R.sup.6 to R.sup.18 is preferably an 
aryl group having from 6 to 12 carbon atoms, for example, a phenyl group, 
a naphthyl group, etc.; the alkylamino group is preferably a dialkyl amino 
group wherein the alkyl moiety has from 1 to 5 catbon atoms, for example, 
dimethyl amino group, diethylamino group, etc.; the arylamino group is 
preferably a diarylamino group having from 6 to 12 carbon atoms, for 
example, diphenylamino group, etc. 
Further, R.sup.6 to R.sup.18 in the formula (II) each may be substituted by 
an alkoxy group having from 1 to 5 carbon atoms, an alkyl group having 
from 1 to 5 carbon atoms, an aryl group having from 6 to 12 carbon atoms, 
and a halogen atom such as a chlorine atom and a bromine atom. 
As for the use of the hydrazone compounds represented by the general 
formulas (I) and (II) in photosensitive layers, there has been no 
precedent before. 
In the course of their intensive study of various organic materals as made 
in an attempt to achieve the above object, the present inventors conducted 
a number of experiments with those hydrazone compounds and, as a result, 
found that the use of such specific hydrazone compounds represented by the 
above general formulas (I) and (II) as charge transporting substances is 
very effective in improving electrophotographic characteristics, although 
the fact has not been given a satisfactory technical explanation as yet. 
Based on this finding, they obtained photosensitive materials having high 
sensitivity and good repeated-use characteristics. 
The hydrazone compounds of general formulas (I) and (II) to be used in 
accordance with the invention can be synthesized in the conventional 
manner by reacting the corresponding aldehyde and hydrazine in an 
appropriate organic solvent, such as an alcohol, if necessary in the 
presence of an acid (condensing agent). 
Typical examples of the thus-obtainable hydrazone compounds of general 
formulas (I) and (II) are given below. 
The following compounds No. I-1 to No. I-32 are typical examples of the 
compound of general formula (I): 
##STR7## 
The following compounds No. II-1 to No. II-42 are typical examples of the 
compound of general formula (II); 
##STR8## 
The example of the synthesis of such hydrazone compounds is specifically 
given below. 
SYNTHESIS EXAMPLE 
50 ml of ethanol, there were added 2.68 g of 5-formyl-(2,2'-bithiophene) 
and 1.68 g of 11-methyl-1-phenylhydrazine, followed by further addition of 
3 drops of 1N hydrochloric acid. The mixture was refluxed for 1 hour and 
then cooled to room temperature. The precipitate was collected by 
filtration and recrystalized from ethanol to give 3.1 g of the hydrazone, 
i.e. the compound No. I-1 (light yellow needle-like crystal, melting point 
111.degree.-112.degree. C.). 
The compounds No. I-2 to No. I-4 were synthesized in the same manner. 
The photosensitive material of the invention contains, as a charge 
transporting substance, a compound of general formula (I) or (II) such as 
mentioned above in the photosensitive layer thereof. According to the mode 
of use of the hydrazone compound, three embodiments of the photosensitive 
material a shown in FIGS. 1 to 3 are possible. 
FIGS. 1 to 3 are schematic cross-sectional views of different embodiments 
of the photosensitive material of this invention. In the figures, the 
reference number 1 indicates an electroconductive substrate, 20, 21 and 22 
each a photosensitive layer, 3 a charge generating substance, 4 a charge 
generating layer, 5 a charge transporting substance, 6 a charge transport 
layer, and 7 a covering layer. 
In the embodiment shown in FIG. 1, a photosensitive layer 20 consisting of 
a dispersion of a charge generating substance 3 and a charge transporting 
substance 5, i.e. the hydrazone compound, in a binder resin is disposed on 
an electroconductive substrate 1. Such a construction is generally 
referred to as an integrated layer type photosensitive material. 
In the emboidment shown in FIG. 2, a photosensitive layer 21 which is a 
laminate of a charge generating layer 4 mainly composed of a charge 
generating substance 3 and a charge transporting substance 5 (i.e. the 
hydrazone compound) is disposed on an electroconductive substrate 1. Such 
a construction is generally referred to as an integrated layer type 
photosenstive material. 
In the embodiment shown in FIG. 3, the layer construction is reversed as 
compared with that shown in FIG. 2. In the case of this construction, a 
covering layer 7 is generally disposed for the protection of the charge 
generating layer 4. The photosensitive layer 22 is composed of the charge 
transport layer 6, charge generating layer 4 and the covering layer 7. 
The two kinds of layer construction as shown in FIG. 2 and FIG. 3 are used 
because the photosensitive material is used in the positive or negative 
charge mode. Generally, however, the layer construction shown in FIG. 2 is 
used in the negative charge mode. Even if it is desired to use the layer 
construction shown in FIG. 2 in the positive charge mode, no appropriate 
charge transporting substance is available at present. Therefore, for use 
in the positive charge mode, the layer construction shown in FIG. 3 should 
be employed as an effective one, as already proposed by the present 
inventors. 
The photosensitive material shown in FIG. 1 can be prepared by dispersing a 
charge generating substance in a solution containing a charge transporting 
substance and a binder resin and applying the dispersion to an 
electroconductive substrate. 
The photosensitive material shown in FIG. 2 can be prepared by 
vacuum-depositing a charge generating substance on an electroconductive 
substrate or by applying a dispersion of a charge generating substance in 
particle form in a solvent or a binder resin to an electroconductive 
substrate, drying the coat layer and further applying a solution 
containing a charge transporting substance and a binder resin onto said 
coat layer, followed by drying. 
The photosensitive material shown in FIG. 3 can be prepared by applying a 
solution containing a charge transporting substance and a binder resin to 
an electroconductive substrate and drying, then vacuum-depositing a charge 
generating substance thereon or by applying a dispersion of a charge 
generating substance in particle form in a solvent or a binder resin and 
drying, and further providing a covering layer 7. 
The electroconductive substrate 1 serves as an electrode of the 
photosensitive material and at the same time as the substrate for each 
layer. It may be in the form of cylinder, sheet or film and may be made of 
a metal such as aluminum, stainless steel or nickel or of glass, a resin 
or the like as electroconductively surface-treated. 
As mentioned above, the charge generating layer 4 is formed by applying a 
dispersion of a charge generating substance 3 in particle form, in a 
binder resin or by the technique of vacuum vapor phase deposition or the 
like. Said layer 4 accepts light and generates charges. It is important 
that said layer have high charge generating efficiency and, at the same 
time, that the charges generated be injected into the charge transport 
layer 6 and covering layer 7. It is desirable that the injection be as 
little dependents as possible on the electric field and be sufficient even 
in low intensity electric fields Useful as the charge generating substance 
are metal-free phthalocyanine, titanylphthalocyanine, other phthalocyanine 
compounds, various azo, quinone, and indigo pigments, selenium, and 
selenium compounds, among others. Appropriate substances can be selected 
depending on the light wavelength region of the exposure light source used 
for image formation. The charge generating layer is only required to be 
capable of generating charges and, therefore, the layer thickness depends 
on the light absorption coefficient of the charge generating substance and 
generally is not more than 5 .mu.m, preferably not more than 1 .mu.m. 
An amount of the charge generating-substance used in the present invention 
is selected according to a desired characteristic of the 
electrophotographic material, and is preferably 10 wt % or more, more 
preferably 20 to 100 wt %, in a charge generating layer. 
It is also possible to form the charge generating layer using the charge 
generating substance in admixture with a minor proportion of a charge 
transporting substance such as hydrazones used in the present invention, 
oxazoles, oxadiazoles and stilbene compounds etc. and so forth. A ratio of 
the charge transporting substance to the charge generating substance is 
preferably from 0.1 to 0.8 by weight. Usable resin as the binder are 
polycarbonates, polyesters, polyamides, polyurethane, epoxy resins, 
methacrylic ester homopolymers and copolymers produced by copolymerizing a 
monomer derived from the above polymers with a comonomer such as stylene, 
methacrylate, etc., for instance, either alone or in appropriate 
combinations. 
In the monolayer type photosensitive material, the photosensitive layer 
contains at least one charge generating substance in an amount of from 10 
to 60 wt % based on a binder and at least one hydrazone compound in an 
amount of from 10 to 60 wt % based on a binder 
The charge transport layer 6 is a layer produced by coating on an 
electroconductive substrate a dispersion of the hydrazone compound of 
general formula (I) or (II) in a binder resin, which is to serve as a 
charge transporting substance. A preferable thickness of the charge 
transporting layer is preferably from 5 to 30 .mu.m, and more preferably 
10 to 20 .mu.m. An amount of the charge transporting substance used in the 
present invention is selected according to a desired characteristic of the 
electrophotographic photosensitive material, and is preferably from 20 to 
80 wt % in a charge transporting layer. In the dark, said layer serves as 
an insulator layer and retains electrostatic charges on the photosensitive 
material and, upon acceptance of light, transport the charges injected 
from the charge generating layer. Usable as the binder resin are 
polycarbonates, polyesters, polyamides, polyurethanes, epoxy resins, 
silicone resins, methacrylic ester homopolymers and copolymers, among 
others. 
The covering layer 7, in the dark, accepts charges generated by corona 
discharge and retains them. It is necessary that said layer be capable of 
transmitting light to which the charge generating layer should respond and 
that said layer be capable of transmitting light at the time of exposure 
to thereby allow the light to reach the charge generating layer so that 
the surface charges can be neutralized and disappear upon injection of 
charges generated in the charge generating layer. Usable as the covering 
material are film-forming insulator materials such as polyesters and 
polyamides. Furthermore, such organic materials can be used in admixture 
with inorganic materials such as glass resins and SiO.sub.2 or, further, 
materials which reduce the electric resistance, such as metals and metal 
oxides. The covering material is not limited to organic film-forming 
insulator materials but it is also possible to form the covering layer by 
using an inorganic material such as SiO.sub.2 or by applying a metal, 
metal oxide such as Zn, Sn Ti, ZnO, SnO.sub.2, TiO.sub.2, etc. or the like 
by the technique of vapor phase deposition or sputtering, for instance. 
The covering material should desirably be as transparent as possible in 
the wavelength region corresponding to the absorption maximum of the 
charge generating substance. 
The thickness of the covering layer may vary depending on the composition 
thereof but generally is optional unless the covering layer produces an 
adverse effect, for example causes an increase in residual potential in 
repeated continuous use. 
The following examples are further illustrative of the present invention. 
EXAMPLE I-1 
A coating liquid was prepared by kneading in a mixer 50 weight parts of 50 
weight parts of metal-free phthalocyanine (available from Tokyo Kasei 
Kogyo) pulverized beforehand in a ball mill for 150 hours, 100 weight 
parts of the hydrazone compound No. I-1 synthesized in the above manner, a 
polyester resin (Vylon; available from Toyobo Co., Ltd.) and the solvent 
tetrahydrofuran (THF) for 3 hours. A photosensitive layer was formed, in a 
dry thickness of 15 .mu.m, on an aluminum-deposited polyester film 
(Al-PET) (electroconductive substrate) by applying the coating liquid to 
the substrate by the wire bar technique. Thus was prepared a 
photosensitive material. 
EXAMPLE I-2 
First, .alpha.-form metal-free phthalocyanine (starting material) was 
micropulverized in a LIMMAC (linear induction motor mixing and crushing) 
apparatus (Fuji Electric Co., Ltd.), where the .alpha.-form metal-free 
phthalocyanine was crushed in a nonmagnetic can containing Teflon pieces 
as working bodies, with said can disposed between two opposing linear 
motors, for 20 minutes. One weight parts of the thus-micropulverized 
samples was dispersed in 50 weight parts of the solvent DMF 
(N,N-dimethylformamide) by ultrasonic treatment. The metal-free 
phthalocyanine sample was separated from the solvent by filtration and 
dried. 
Then, a coating solution was prepared by mixing a solution of 100 weight 
parts of the hydrazone compound No. I-1 synthesized in the above manner in 
700 weight parts of tetrahydrofuran (THF) and a solution of 100 weight 
parts of polymethyl methacrylate polymer (PMMA; available from Tokyo Kasei 
Kogyo) in 700 weight parts of toluene. A charge transport layer was 
formed, in a dry thickness of 15 .mu.m, on an aluminum-deposited polyester 
film substrate by applying the coating solution to said substrate using a 
wire bar. On the thus-obtained charge transport layer, there was formed a 
charge generating layer in a dry thickness of 1 .mu.m by applying, with a 
wire bar, a coating liquid prepared by kneading in a mixer 50 weight part 
of the metal-free phthalocyanine treated in the above manner, 50 weight 
parts of a polyester resin (Vylon-200.RTM.; available from Toyobo Co., 
Ltd.), and the solvent THF for 3 hours. Thus was prepared a photosensitive 
material. 
EXAMPLE I-3 
A photosensitive material was prepared by forming a photosensitive layer in 
the same manner as in Example I-1 except that the composition of the 
charge generating layer was as follows: 50 weight parts of metal-free 
phthalocyanine, 100 weight parts of the hydrazone compound No.I-1, and 50 
weight parts of a polyester resin (Vylon 200; Toyobo Co., Ltd.), 
EXAMPLE I-4 
photosensitive material was prepared by forming a photosensitive layer in 
the same manner as in Example I-3 except that Chlorodiane Blue, a bisazo 
pigment, as described in Japanese Patent Application (OPI) No. 37543/1972, 
was used in lieu of metal-free phthalocyanine. 
The thus-obtained photosensitive materials were measured for their 
electrophotographic characteristics using an electrostatic recording paper 
testing apparatus (Kawaguchi Denki model SP-428). 
The surface potential V.sub.s (volts) of each photosensitive material is 
the initial surface potential attained upon positively charging the 
photosensitive material surface by +6.0 kV corona discharging in the dark 
for 10 seconds. After allowing the material to stand in the dark- for 2 
seconds following discontinuation of the corona discharge, the surface 
potential V.sub.d (volts) was measured. The photosensitive material 
surface was then further irradiated with white light at an illuminance of 
2 lux, and the time (in seconds) required for the illumination to 
discharge the material surface to half of V.sub.d was measured and the 
half decay exposure amount E.sub.1/2 (lux.Sec) was calculated. The 
residual potential V.sub.r (volts) is the surface potential after 10 
seconds of irradiation with white light at an illuminance of 2 lux. Since 
the use of the phthalocyanine compound as the charge generating substance 
was expected to give high sensitivity to long wavelength light, the 
electrophotographic characteristics obtainable by the use of monochromatic 
light of the wavelength 780 nm were also measured. Thus, the same 
procedure as above was followed until Vd measurement, then 1 .mu.W 
monochromatic light (780 nm) was used in lieu of white light for 
irradiation, and the half decay exposure amount (.mu.J/cm.sup.2) was 
determined. Further, after irradiation of the photosensitive material 
surface with said light for 10 seconds, the residual potential Vr 
was measured. The results of the measurements are 
in Table I-1. 
TABLE I-1 
______________________________________ 
White light Light of wavelength 780 nm 
Exam- V.sub.s V.sub.r E.sub.1/2 
V.sub.s 
V.sub.r 
E.sub.1/2 
ple Volts Volts Lux .multidot. sec 
Volts Volts .mu.J/cm.sup.2 
______________________________________ 
I-1 480 30 3.5 450 25 1.3 
I-2 650 70 3.8 650 50 0.9 
I-3 600 65 3.5 600 45 0.85 
I-4 630 68 3.7 -- -- -- 
______________________________________ 
As can be seen in Table I-1, the photosensitive 
s of Examples I-1, I-2, I-3 and I-4 were comparable to one another with 
respect to half decay exposure and residual potential and were good also 
with respect to surface potential. 
EXAMPLE I-5 
A charge generating layer was formed on an aluminum plate having a 
thickness of 500 .mu.m by vacuum deposition of selenium to a thickness of 
1.5 .mu.m. Thereon was then formed a charge transport layer by applying, 
with a wire bar, a coating solution prepared by mixing a solution of 100 
weight parts of the hydrazone compound No. I-2 in 700 weight parts of 
tetrahydrofuran (THF) and a solution of 100 weight parts of polymethyl 
methacrylate (PMMA; Tokyo Kasei Kogyo) in 700 weight parts of toluene of 
give a dry layer thickness of 20 .mu.m. When subjected to -6.0 kV corona 
discharge for 0.2 second, the photosensitive material obtained gave good 
results as follows: V.sub.s =-850 V, V.sub.r =60 V, and E.sub.1/2 =5.1 
lux.SeC. 
EXAMPLE I-6 
A coating liquid was prepared by kneading in a mixer 50 weight parts of 
metal-free phthalocyanine treated in the same manner as in Example I-1, 50 
weight parts of a polyester resin (Vylon 200, Toyobo Co., Ltd.), 
and the solvent THF. A charge generating layer was formed, in a dry 
thickness of about 1 .mu.m, on an aluminum support by applying the coating 
liquid to said support. Then, a charge transport layer, about 15 .mu.m in 
thickness, was formed by applying a mixture of 100 weight parts of the 
hydrazone compound No. I-1, 100 weight parts of a polycarbonate resin 
(Panlite L-1250), 0.1 weight part of a silicone oil and 700 weight parts 
of THF onto the charge generating layer. 
When subjected to -6.0 kV corona discharge for 0.2 second in the same 
manner as in Example I-4, the photosensitive material obtained gave good 
results as follows: V.sub.s =-750 V, E.sub.1/2 =3.2 lux.sec. 
EXAMPLE 7 
A photosensitive material was prepared in the same manner as in Example I-2 
except that an aluminum drum, 60 mm in outside diameter and 320 mm in 
length, was used as the electroconductive substrate in place of the 
aluminum-deposited polyester film (Al-PEPT) and that the charge transport 
layer (15 .mu.m) and charge generating layer (2 .mu.m) were formed on the 
exterior surface of the drum by dip coating. 
The photosensitive material prepared in Example I-7 was mounted on a 
Carlson-system copier and evaluated by producing 100 copies successively. 
Good copies were obtained without image density decrease or paper sheet 
staining. The photosensitive material prepared in Example I-7 was mounted 
on the same copier, the developing section was removed, surface 
potentiometes were provided, and potential changes during the copying 
process were measured. The results thus obtained are shown in Table I-2. 
TABLE I-2 
______________________________________ 
Potential in the dark 
Potential in the illuminated 
(volts) portion (volts) 
1st copying 
100th copying 
1st copying 
100th copying 
Example 
operation operation operation 
operation 
______________________________________ 
I-7 650 625 100 110 
______________________________________ 
both the potentials, the repeated-use characteristics were satisfactory. 
EXAMPLE II-1 
A coating liquid was prepared by kneading in a weight parts of 50 weight 
parts of metal free phthalocyanine (available from Tokyo Kasei Kogyo) 
pulverized beforehand in a ball mill for 150 hours, 100 weight parts of 
the hydrazone compound No. I-5 specified above, a polyester resin (Vylon; 
available from Toyobo Co., Ltd.) and the solvent tetrahydrofuran (THF) for 
3 hours. A photosensitive layer was formed, in a dry thickness of 15 
.mu.m, on an aluminum-deposited polyester film (Al-PET) (electroconductive 
substrate) by applying the coating liquid to the substrate by the wire bar 
technique. Thus was prepared a photosensitive material. 
EXAMPLE II-2 
First, .alpha.-form metal-free phthalocyanine (starting material) was 
micropulverized in a LIMMAC (linear induction motor mixing and crushing) 
apparatus (Fuji Electric Co., Ltd.), where the u-form metal-free 
phthalocyanine was crushed in a nonmagnetic can containing Teflon pieces 
as working bodies, with said can disposed between two opposing linear 
motors, for 20 minutes. One weight part of the thus-micropulverized 
samples was dispersed in 50 weight parts of the solvent DMF 
(N,N-dimethylformamide) by ultrasonic treatment. The metal-free 
phthalocyanine sample was separated from the solvent by filtration and 
dried. 
Then, a coating solution was prepared by mixing a solution of 100 weight 
parts of the hydrazone compound No. I-5 mentioned above in 700 weight 
parts of tetrahydrofuran (THF) and a solution of 100 weight parts of 
polymethyl methacrylate polymer (PMMA; available from Tokyo Kasei Kogyo) 
in 700 weight parts of toluene. A charge transport layer was formed, in a 
dry thickness of 15 .mu.m, on an aluminum-deposited polyester film 
substrate by applying the coating solution to said substrate using a wire 
bar. On the thus-obtained charge transport layer, there was formed a 
charge generating layer in a dry thickness of 1 .mu.m by applying, with a 
wire bar, a coating liquid prepared by kneading in a mixer 50 weight parts 
of the metal-free phthalocyanine treated in the above manner, 50 weight 
parts of a polyester resin (Vylon 200; available from Toyobo Co., Ltd.), 
and the solvent THF for 3 hours. After drying, there was obtained a 
photosensitive material. 
EXAMPLE II-3 
A photosensitive material was prepared by forming a photosensitive layer in 
the same manner as in Example II-1 except that the composition of the 
charge generating layer was as follows 50 weight parts of metal-free 
phthalocyanine, 100 weight parts of the hydrazone compound No. I-5, 50 
weight parts of a polyester resin (Vylon 200; Toyobo Co., Ltd.) and 50 
weight parts of PMMA. 
EXAMPLE II-4 
A photosensitive material was prepared by forming a photosensitive layer in 
the same manner as in Example II-3 except that Chlorodiane Blue, a bisazo 
pigment, was used in lieu of metal-free phthalocyanine. 
The thus-obtained photosensitive materials were measured for their 
electrophotographic characteristics using an electrostatic recording paper 
testing apparatus (Kawaguchi Denki model SP-428) according to the 
procedure of Example I-4. The results of the measurements are shown in 
Table II-1. 
TABLE II-1 
______________________________________ 
White light Light of wavelength 780 nm 
Exam- V.sub.s V.sub.r E.sub.1/2 
V.sub.s 
V.sub.r 
E.sub.1/2 
ple Volts Volts Lux .multidot. sec 
Volts Volts .mu.J/cm.sup.2 
______________________________________ 
II-1 475 25 3.1 460 40 1.1 
II-2 680 50 3.5 660 35 1.0 
II-3 620 65 3.8 600 30 0.8 
II-4 640 60 3.5 -- -- -- 
______________________________________ 
As can be seen in Table II-1, the photosensitive materials of Examples 
II-1, II-2, II-3 and II-4 were comparable to one another with respect to 
half decay exposure and residual potential and were good also with respect 
to surface potential. 
EXAMPLE II-5 
A charge generating layer was formed on an aluminum plate having a 
thickness of 500 .mu.m by vacuum vapor deposition of selenium to a 
thickness of 1.5 .mu.m. Thereon was then formed a charge transport layer 
by applying, with a wire bar, a coating solution prepared by mixing a 
solution of 100 weight parts of the hydrazone compound No. I-19 in 700 
weight parts of tetrahydrofuran (THF) and a solution of 100 weight parts 
of polymethyl methacrylate (PMMA; Tokyo Kasei Kogyo) in 700 weight parts 
of toluene to give a dry layer thickness of 20 .mu.m. When subjected to 
-6.0 kV corona discharge for 0.2 second, the photosensitive material 
obtained gave good results as follows: V.sub.S =-830 V, V.sub.r =50 V, and 
E.sub.1/2 =4.5 lux.sec. 
EXAMPLE II-6 
A coating Iiquid was prepared by kneading in a mixer 50 weight parts of 
metal-free phthalocyanine treated in the same manner as in Example II-1, 
50 weight parts of a polyester resin (Vylon 200, Toyobo Co., Ltd.), 
and the solvent THF. A charge generating layer was formed, in a dry 
thickness of about 1 .mu.m, on an aluminum support by applying the coating 
liquid to said support. Then, a charge transport layer, about 15 .mu.m in 
thickness, was formed by applying a mixture of 100 weight parts of the 
hydrazone compound No. I-24, 100 weight parts of a polycarbonate resin 
(Panlite L-1250), 0.1 weight part of a silicone oil, 700 weight parts of 
THF and 700 weight parts of toluene onto the charge generating layer. 
When subjected to -6.0 kV corona discharge for 0.2 second in the same 
manner as in Example II-4, the photosensitive material obtained gave good 
results as follows: V.sub.s =-740 V, E.sub.1/2 =2.5 lux.sec. 
EXAMPLE II-7 
photosensitive material was prepared in the same manner as in Example II-2 
except that an aluminum drum, 60 mm in outside diameter and 320 mm in 
length, was used as the electroconductive substrate in place of th 
aluminum-deposited polyester film (Al-PET) and that the charge transport 
layer (15 .mu.m) and charge generating layer (2 .mu.m) were formed on the 
exterior surface of the drum by dip coating. 
The photosensitive material prepared in Example II-7 was mounted on a 
Carlson-system copier and evaluated by producing 100 copies successively. 
Good copies were obtained without image density decrease or paper sheet 
staining. The photosensitive material prepared in Example II-7 was mounted 
on the same copier, the developing section was removed, surface 
potentiometers were provided, and potential changes during the copying 
process were measured. The results thus obtained are shown in Table II-2. 
TABLE II-2 
______________________________________ 
Potential in the 
Potential in the illuminated 
dark (volts) portion (volts) 
100th 100th 
1st copying 
copying 1st copying 
copying 
Example operation operation 
operation 
operation 
______________________________________ 
II-7 640 620 100 110 
______________________________________ 
As can be seen in Table II-2, the above photosensitive materials showed 
good repeated-use characteristics. 
EXAMPLE III-1 
A photosensitive material was prepared in the same way as Example I-1 
except that hydrazone compound No. II-1 was used instead of the hydrazone 
compound No. I-5 in Example I-1. 
EXAMPLE III-2 
A photosensitive material was prepared in the same manner as in Example 
III-1 except that hydrazone compound No. II-15 was used in lieu of 
hydrazone compound No. II-1. 
EXAMPLE III-3 
A photosensitive material as is shown in FIG. 3 was prepared in the same 
manner as in Example II-2 except that hydrazone compound II-1 was used in 
lieu of hydrazone compound I-5, and the coating layer was not applied. 
EXAMPLE III-4 
A photosensitive material was prepared in the same manner as in Example 
III-3 except that the hydrazone compound No. II-15 shown hereinabove was 
used in place of the compound No. II-1. 
EXAMPLE III-5 
A photosensitive material was prepared in the same manner as in Example 
III-1 except that the photosensitive layer composition was as follows: 50 
weight parts of metal-free phthalocyanine, 100 weight parts of the 
hydrazone compound No. II-1, 50 weight parts of a polyester resin (Vylon 
200, Toyobo Co., Ltd.) and 50 weight parts of PMMA. 
EXAMPLE III-6 
A photosensitive material was prepared in the same manner as in Example 
III-5 except that the hydrazone compound No. II-15 was used in lieu of the 
compound No. II-1. 
EXAMPLE III-7 
A photosensitive material was prepared in the same manner as in Example 
III-5 except that Chlorodiane Blue, a bisazo pigment, as described in 
Japanese Patent Application (OPI) No. 37543/1972, was used in lieu of 
metal-free phthalocyanine. 
EXAMPLE III-8 
A photosensitive materials was prepared in the same manner as in Example 
III-7 except that the hydrazone compound No. II-15 was used in lieu of the 
copound No. II-1. 
The thus-obtained photosensitive materials were measured for their 
electrophotographic characteristics using an electrostatic recording paper 
testing apparatus used in Example I-4. 
The results of the measurements are shown in Table III-1. 
TABLE III-1 
______________________________________ 
White light Light of wavelength 780 nm 
Exam- V.sub.s V.sub.r E.sub.1/2 
V.sub.s 
V.sub.r 
E.sub.1/2 
ple Volts Volts Lux .multidot. sec 
Volts Volts .mu.J/cm.sup.2 
______________________________________ 
III-1 650 90 4.3 680 100 4.9 
III-2 700 100 5.1 710 80 3.8 
III-3 720 100 4.8 730 80 4.1 
III-4 780 80 4.3 740 60 4.5 
III-5 750 50 4.2 720 70 4.5 
III-6 730 70 4.8 750 70 4.6 
III-7 680 100 5.3 -- -- -- 
III-8 750 80 5.0 -- -- -- 
______________________________________ 
As can be seen in Table III-1, the photosensitive materials of Examples 
III-1 to III-8 in which the hydrazone compound No. II-1 or II-15 was used 
as the charge transporting substance were satisfactory with respect to 
surface potential V.sub.s, half decay exposure amount E.sub.1/2 and 
residual potential V.sub.r. The photosensitive materials of Examples III-1 
to III-6 in which the phthalocyanine compound was used as the charge 
generating substance showed good electrophotographic characteristics also 
against the long wavelength (780 nm) light. 
EXAMPLE III-9 
A photosensitive material as is shown in FIG. 2 was prepared in the same 
manner as in Example I-5 except that the hydrazone compound No. II-2 
instead of the hydrazone compound No. I-2. 
The photosensitive material was subjected to -6.0 KV corona discharge in 
for 2 seconds and then electrophotographic characteristics were measured 
to oprov good results as follows: 
EQU V.sub.s =-880 V, V.sub.r =-100V, E.sub.1/2 =5.1 lux. sec. 
EXAMPLE III-10 
A photosensitive material was prepared in the same manner as in Example 
III-9 except that the hydrazone compound No. II-16 was used in stead of 
the compound No. II-2. The photosensitive material was measured for its 
characteristics and gave good results as follows: 
EQU V.sub.s =-780 V, V.sub.r =-60 V, E.sub.1/2 =3.8 lux. sec. 
EXAMPLE III-11 
A coating liquid was prepared by kneading in a mixer 50 weight parts of 
metal-free phthalocyanine treated in the same manner as in Example II-1, 
50 weight parts of a polyester resin (Vylon 200, Toyobo Co., Ltd.), 
and the solvent THF. A charge generating layer was formed, in a dry 
thickness of about 1 .mu.m, on an aluminum support by applying the coating 
liquid to said support. Then, a charge transport layer, about 15 .mu.m in 
thickness, was formed by applying a mixture of 100 weight parts of the 
hydrazone compound No. II-3, 100 weight parts of a polycarbonate resin 
(Panlite L-1250), 0.1 weight part of a silicone oil, 700 weight parts of 
THF and 700 weight parts of toluene onto the charge generating layer. 
When subjected to -6.0 kV corona discharge for 0.2 second in the same 
manner as in Example III-9, the photosensitive material obtained gave good 
results as follows: V.sub.s =-850 V, E.sub.1/2 =5.5 lux.sec. 
EXAMPLE III-12 
A photosensitive material was prepared in the same manner as in Example 
III-11 except that the hydrazone compound No. II-17 was used in lieu of 
the compound No. II-3. The photosensitive material was measured for its 
characteristics and gave good results as follows: 
EQU V.sub.s =-800 V, E.sub.1/2 =4.2 lux.sec. 
EXAMPLE III-13 
Photosensitive materials having the construction shown in FIG. 1 were 
prepared by forming a photosensitive layer in the same manner as in 
Example III-7 except that the hydrazone compounds Nos. II-4 to II-14 were 
used in lieu of the compound No. II-1. They were measured for 
electrophotographic characteristics in the same manner as in Example 
III-8. The photosensitive materials were subjected to +6.0 kV corona 
discharge in the dark for 10 seconds and then illuminated with white 
light at an illuminance of 2 lux. The half decay exposure data (E.sub.1/2) 
thus obtained are shown in Table III-2. 
TABLE III-2 
______________________________________ 
Compound No. E.sub.1/2 (lux .multidot. sec) 
______________________________________ 
II-4 4.8 
II-5 3.9 
II-6 4.5 
II-7 5.0 
II-8 5.3 
II-9 4.8 
II-10 4.3 
II-11 4.1 
II-12 5.3 
II-13 5.1 
II-14 4.9 
______________________________________ 
As can be seen in Table III-2, also the photosensitive materials with the 
hydrazone compounds Nos. III-4 to III-14 each as the charge transporting 
substance were found to be highly sensitive, giving good half decay 
exposure data. 
EXAMPLE III-14 
Photosensitive materials were prepared in the same manner as in Example 
III-7 except that the hydrazone compounds. Nos. II-18 to II-42 
specifically shown hereinabove were used in lieu of the hydrazone compound 
No. II-1. They were measured for electrophotographic characteristics in 
the same manner as in Example III-13. Among the measurement results, the 
half decay exposure data alone are shown in Table III-3. 
TABLE III-3 
______________________________________ 
Compound No. E.sub.1/2 (lux .multidot. sec) 
______________________________________ 
II-18 4.5 
II-19 5.2 
II-20 3.8 
II-21 5.5 
II-22 4.8 
II-23 4.7 
II-24 4.2 
II-25 4.6 
II-26 5.0 
II-27 5.5 
II-28 6.0 
II-29 3.9 
II-30 4.3 
II-31 4.1 
II-32 4.3 
II-33 5.0 
II-34 4.2 
II-35 4.8 
II-36 4.7 
II-37 4.1 
II-38 4.5 
II-39 5.0 
II-40 5.3 
II-41 4.9 
II-42 5.2 
______________________________________ 
As can be seen in Table III-3, the photosensitive materials obtained by 
using the hydrazone compounds Nos. II-18 to II-42 each as the charge 
transporting substance gave good half decay exposure data and were found 
to be highly sensitive. 
As mentioned hereinabove, the use, in accordance with the invention, of the 
above-mentioned hydrazone compounds of general formulas (I) and (II) 
results in photosensitive materials having high sensitivity in the 
positive as well as in the negative charge mode of use and having 
excellent repeated-use characteristics. The charge generating substance 
can be selected so that it can fit to the exposure light source to be 
used. Thus, for instance, it is possible to obtain photosensitive 
materials usable in semiconductor laser printers by using phthalocyanine 
and/or a certain kind of bisazo compound. The durability of said materials 
can be improved by providing a covering layer on the surface thereof. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modification can be made therein without 
departing from the spirit and scope thereof.