Electrophotographic member with surface layer having fluorine resin powder and fluorine graft polymer

An electrophotographic photosensitive member having a photosensitive layer on an electroconductive substrate comprises a surface layer containing a fluorine type resin powder and a fluorine type graft polymer.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an electrophotographic photosensitive member, 
more particularly to an electrophotographic photosensitive member of high 
durability excellent in humidity resistance and mechanical strength. 
2. Related Background Art 
An electrophotographic photosensitive member is required to have prescribed 
sensitivity, electrical characterictics and optical characteristics 
corresponding to the electrophotographic process to be applied. Further, 
in a photosensitive member which is used repeatedly, since electrical and 
mechanical external force such as corona charging, toner development, 
transfer onto paper, cleaning treatment, etc., is directly applied onto 
the surface layer of the photosensitive member, namely the layer which is 
the remotest from the substrate, durability to those forces is required. 
More specifically, durability to generation of abrasion or damage by the 
friction of the surface or to deterioration of the surface by ozone 
generated during corona charging under humid conditions is required. 
On the other hand, there is also the problem of toner attachment onto the 
surface layer by repeated development of toner and cleaning, and to cope 
with this problem, improvement of the cleaning characteristic of the 
surface layer has been demanded. 
In order to satisfy the characteristics required for the surface layer as 
mentioned above, various methods have been investigated. Among them, the 
means of dispersing fluorine type resin powder into the surface layer is 
effective. By dispersion of fluorine type resin powder, the frictional 
coefficient of the surface layer is lowered to act on improvement of the 
cleaning characteristic as well as improvement of durability to abrasion 
damage. 
Also, since water-repellent property and mold-release property of the 
suface layer can be improved, it is also effective against prevention of 
the surface deterioration and highly humidity conditions. 
However, in fluorine resin powder dispersion, problems are involved in its 
dispersibility and agglomerating tendency, and since it is difficult to 
form a uniform and smooth film, the surface layer obtained could not avoid 
having image defects such as image irregularities or pinholes. 
Also, although some binder resins or dispersing aids can disperse uniformly 
fluorine type resin powder to form a smooth film, in most cases, due to 
having hydroxyl groups, carboxyl groups, ether bonds, etc., carrier traps 
are formed particularly under high temperature and highly humid conditions 
to cause deterioration in electrophotographic characteristics. Thus, under 
the present situation, no practically available binder resin or dispersing 
aid can be found. 
SUMMARY OF THE INVENTION 
The present invention is intended to provide an electrophotographic 
photosensitive member which should respond to the requirements as 
mentioned above. 
That is, a first object of the present invention is to provide an 
electrophotographic photosensitive member having durability to abrasion of 
the surface or generation of scraper by friction. 
A second object is to provide an electrophotographic photosensitive member 
capable of obtaining an image which is stable and of high quality even 
under highly humid conditions. 
A third object is to provide an electrophotographic photosensitive member 
which is good in cleaning characteristic and without adhesion of toner 
onto the surface layer. 
A fourth object of the present invention is to provide an 
electrophotographic photosensitive member capable of obtaining always an 
image of high quality without coating irregularity or pinhole on the 
surface, and also without accumulation of residual potential in the 
repeated electrophotographic process. 
According to the present invention, there is provided an 
electrophotographic photosensitive member having a photosensitive layer on 
an electroconductive substrate, which comprises a surface layer containing 
a fluorine type resin powder and a fluorine type graft polymer. 
The present inventors have investigated along the above objects, and 
consequently found that an electrophotographic photosensitive member 
having a surface layer containing fluorine type resin powder dispersed in 
the presence of a fluorine type graft polymer can respond to the 
requirements as described above to accomplish the present invention. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
That is, the present invention is constituted of an electrophotographic 
photosensitive member having a photosensitive layer on an 
electroconductive substrate, which comprises a surface layer containing a 
fluorine type resin powder and a fluorine type graft polymer. 
The fluorine type resin powder to be applied in the present invention may 
be selected from at least one of tetrafluoroethylene resins, 
trifluorochloroethylene resins, tetrafluoroethylene-hexafluoropropylene 
resins, vinyl fluoride resins, vinylidene fluoride resins, 
difluorochloroethylene resins and copolymers thereof, preferably 
tetrafluoroethylene resins and vinylidene fluoride resins. The molecular 
weight of the resin and the size of the powder may be optionaly selected 
from the commercial grades, but those of lower molecular weight grades and 
having primary particles of 1 .mu. or less are preferred. 
The content of the fluorine type resin powder dispersed in the surface 
layer may be suitably 1 to 50 wt. %, particularly preferably 2 to 30 wt. % 
based on the solid weight in the surface layer. With a content less than 1 
wt. %, the effect of improving the surface layer with the fluorine type 
resin powder is not sufficient, while a content over 50 wt. % will lower 
light transmittance and also lower mobility of carriers. 
The fluorine type graft polymer to be applied in the present invention can 
be obtained by copolymerization of an oligomer containing a polymerizable 
functional group at one terminal end a molecular weight of about 1000 to 
10000 and also having certain repeating units (hereinafter called 
macromer) with a polymerizable monomer. 
The fluorine type graft polymer has a structure comprising: 
(i) a trunk of a fluorine type segment and a branch of a non-fluorine type 
segment in the case of copolymerization of a non-fluorine type macromer 
synthesized from a non-fluorine type polymerizable monomer with a fluorine 
type polymerizable monomer, or 
(ii) a trunk of a non-fluorine type segment and a branch of a fluorine type 
segment in the case of copolymerization of a fluorine type macromer 
synthesized from a fluorine type polymerizable monomer and a non-fluorine 
type polymerizable monomer. 
The fluorine type graft polymer has fluorine type segments and non-fluorine 
type segments localized respectively as described above, and takes the 
function separation form in which the fluorine type segments are oriented 
toward the fluorine type resin powder, and the non-fluorine type segments 
toward the resin layer added, respectively. Particularly, since the 
fluorine type segments are arranged continuously, the fluorine type 
segments can be adsorbed at high density and with good efficiency onto the 
fluorine type resin powder, and further the non-fluorine type segments are 
oriented toward the resin layer, whereby the improvement effect of 
dispersion stability of the fluorine type resin powder not found in the 
dispersing agent of the prior art can b exhibited. Also, fluorine type 
resin powder generally exists as agglomerated masses of several .mu. 
order, but by use of the fluorine type graft polymer of the present 
invention as the dispersing agent, the powder can be dispersed uniformly 
to primary particles of 1 .mu. or less. For making available such function 
separation effect to the full extent, the molecular weight of the macromer 
is required to be controlled to about 1000 to 10,000 as described above. 
That is, if the molecular weight is less than 1000, because the length of 
the segments is too short, adsorption efficiency to the fluorine type 
resin powder is reduced in the case of fluorine segments, while 
orientation toward the surface layer resin layer is weakened in the case 
of non-fluorine type segments, whereby dispersion stability of the 
fluorine type resin powder is inhibited in either case. On the other hand, 
if the molecular weight exceeds 10,000, compatibility with the resin layer 
of the surface layer added will be reduced. Particularly, this phenomenon 
is marked in the fluorine type segments, and because the segment will take 
a shrinked coil-like form in the resin layer, the number of active 
adsorption points onto the fluorine type resin powder will be reduced, 
whereby dispersion stability is inhibited. 
Also, the molecular weight of the fluorine type graft polymer itself gives 
a great influence, and the preferable range is from 10,000 to 100,000. If 
the molecular weight is less than 10,000, the function of dispersion 
stability can be insufficiently exhibited, while if it is in excess of 
100,000, compatibility with the surface resin layer added will be reduced, 
whereby similarly the function of dispersion stability cannot be 
exhibited. 
The ratio of the fluorine type segments in the fluorine type graft polymer 
should be preferably 5 to 90 wt/%, more preferably 10 to 70 wt. %. With a 
ratio of the fluorine type segments less than 5 wt. %, the function of 
dispersion stability of the fluorine type resin powder cannot be fully 
exhibited, while with a ratio exceeding 90 wt. %, compatibility with the 
surface layer resin added will be worsened. 
The fluorine type graft polymer added may be appropriately 0.1 to 30 % by 
weight of the fluorine type resin powder, particularly preferably 1 to 20 
%. With an amount added of less than 0.1 %, the effect of dispersion 
stability of the fluorine type resin powder is not sufficient. At a level 
in excess of 30 %, the fluorine type graft polymer will exist internally 
of the surface resin in the free state in addition to the polymer existing 
adsorbed onto the fluorine type resin. Accumulation of residual potential 
will occur when electrophotographic process is performed repeatedly when 
such excess of graft polymer is employed. 
In the following, preferable examples of the fluorine type graft polymer to 
be used in the present invention are shown. 
A-1 : the fluorine type graft polymer is a copolymer of a non-fluorine type 
oligomer of the general formula (I) having a polymerizable functional 
group at one terminal end and also having certain repeating units and a 
fluorine type polymerizable monomer selected from the compounds (II): 
##STR1## 
R.sub.1 : hydrogen atom, alkyl group, halogen atom, halo-substituted alkyl 
group, aryl group; 
A.sub.1 : alkylene chain, halo-substituted alkylene chain; 
A.sub.2 : 
##STR2## 
R.sub.2 -R.sub.11 : hydrogen atom, alkyl group, halo-substituted alkyl 
group; 
A.sub.3 : alkylene chain, halo-substituted alkylene chain; 
A.sub.4 repeating unit comprising a polymer of at least one polymerizable 
monomer selected from low molecular weight straight chain unsaturated 
hydrocarbons, vinyl halides, vinyl esters of organic acids, vinylaromatic 
compounds, acrylic acid and methacrylic acid esters, N-vinyl compounds, 
vinylsilicon compounds, maleic anhydride, esters of maleic acid and 
fumaric acid; 
a: positive integer; 
Compounds (II): fluorine-substituted low molecular weight straight chain 
unsaturated hydrocarbons, fluorine-substituted vinyl halides, 
fluorine-substituted vinyl esters of organic acid vinyl esters, 
fluorine-substituted alkyl vinyl ethers, fluorine-substituted alkyl esters 
and amides of acrylic acid and methacrylic acid, fluorine-substituted 
aromatic containing esters and amides of acrylic acid and methacrylic 
acid, fluorinated maleic anhydride, fluorine-substituted alkyl esters of 
maleic acid and fumaric acid, .alpha.-fluorinated styrene and 
.alpha.,.beta.,.beta.-fluorinated styrene. 
A-2 the fluorine type graft polymer is a copolymer of a fluorine type 
oligomer of the formula (III) having a polymerizable functional group at 
one terminal end and also having certain repeating units and a 
non-fluorine type polymerizable monomer selected from the compounds (IV). 
##STR3## 
A.sub.5 : repeating unit comprising a polymer of at least one 
polymerizable monomer selected from fluorine-substituted low molecular 
weight straight chain unsaturated hydrocarbons, fluorine-substituted vinyl 
halides, fluorine-substituted organic acid vinyl esters, 
fluorine-substituted alkyl vinyl ethers, fluorine-substituted alkyl esters 
and amides of acrylic acid and methacrylic acid, fluorine-substituted 
aromatic containing esters and amides of acrylic acid and methacrylic 
acid, fluorinated maleic anhydride, fluorine-substituted alkyl esters of 
maleic acid and fumaric acid, .alpha.-fluorinated styrene and .alpha., 
.beta.,.beta.-fluorinated styrene; 
R.sub.1, A.sub.1, A.sub.2, A.sub.3 and a have the same meanings as defined 
above; 
Compounds (IV): low molecular weight straight chain unsaturated 
hydrocarbons, vinyl halides, vinyl esters of organic acids, vinyl aromatic 
compounds, acrylic acid and methacrylic acid esters, N-vinyl compounds, 
vinylsilicon compounds, maleic anhydride, esters of maleic acid and 
fumaric acid. 
Synthesis of the macromer in A-1 can be accomplished according to the 
method as disclosed in U.K. Patent No. 1,096,912 in which a prepolymer 
such as carboxylic acid, alcohol and the like at the terminal end is 
synthesized by radical polymerization with the use of a continuous chain 
transfer agent, and double bonds are introduced with the reaction of an 
epoxy group. A synthesis example of a macromer of methyl mechacrylate is 
shown by the synthesis scheme (1). 
##STR4## 
By copolymerization of the thus synthesized methyl methacrylate macromer 
with a fluorine type polymerizable monomer, a fluorine type graft polymer 
having fluorine type segment in the trunk and nonfluorine type segments 
(methyl methacrylate oligomer) in the branch can be obtained. 
The fluorine type polymerizable monomer may be a compound having fluorine 
atoms in the molecule and also having a polymerizable functional group, 
and can be polymerized according to the reaction mode corresponding to its 
functional group. 
Preferable specific examples of the fluorine type polymerizable monomer are 
shown below, but the scope of available compounds is not limited at those 
to those mentioned here. Specific examples of fluorine type polymerizable 
monomer: 
______________________________________ 
Compound No. 
______________________________________ 
(1) CH.sub.2CHF 
(2) CH.sub.2CF.sub.2 
(3) CHFCF.sub.2 
(4) CF.sub.2CF.sub.2 
(5) CF.sub.2CFCl 
(6) CF.sub.2CFCF.sub.3 
(7) CF.sub.2CFRf 
(8) CF.sub.2CFORf 
(9) CH.sub.2CHRf 
(10) CH.sub.2CHORf 
(11) 
##STR5## 
(12) 
##STR6## 
(13) 
##STR7## 
(14) 
##STR8## 
(15) 
##STR9## 
(16) 
##STR10## 
______________________________________ 
(in the above compound, R.sub.1 represents hydrogen atom, halogen atom or 
methyl group; R.sub.2 represents hydrogen atom, halogen atom, alkyl group, 
alkoxy group or nitrile group or a combination of several kinds thereof; k 
is an integer of 1 to 4, m is an integer of 1 to 5 and k+m=5; R.sub.f 
represents an alkyl group which is substituted with one or more fluorine 
atoms.) 
As the non-fluorinetype polymerizable monomer, there may be employed at 
least one of low molecular weight straight chain unsaturated hydrocarbons, 
vinyl halides, vinyl esters of organic acids, vinylaromatic compounds, 
acrylic acid and methacrylic acid esters, N-vinyl compounds, vinylsilicon 
compounds, maleic anhydride, esters of maleic acid and fumaric acid, but 
it is necessary to select one which is compatible with the resin layer of 
the surface layer in which the fluorine type graft polymer formed is added 
or, even if not completely compatible therewith, has a similar structure, 
thus having affinity even to a small extent between the both. For example, 
when the surface resin layer is a poly(meth)acrylic acid ester, it is 
preferable to select a (meth)acrylic acid ester as the non-fluorine type 
polymerizable monomer, while a styrene type compound should preferably 
selected in the case of polystyrene or polycarbonate. In the macromer 
synthesis of methyl methacrylate as described above, by use of a fluorine 
type polymerizable monomer in place of methyl methacrylate, a fluorine 
type macromer can be obtained and from copolymerization of the macromer 
with a non-fluorine type polymerizable monomer, a fluorine type graft 
polymer containing branches of a fluorine type segment and trunks of 
non-fluorine type segments can be obtained. 
B-1: the fluorine type graft polymer is a copolymer of a non-fluorine type 
oligomer of the formula (V) having a polymerizable functional group at one 
terminal end and also having certain repeating units and a fluorine type 
polymerizable monomer selected from the compound (II). 
##STR11## 
R.sub.12 : hydrogen atom, alkyl group, halogen atom, halo-substituted 
alkyl group; 
A.sub.6 : alkylene chain; 
X: 
##STR12## 
R.sub.13 : hydrogen atom or alkyl group; b: 0 or positive integer; 
A.sub.7 : 
##STR13## 
R14: hydrogen atom, alkyl group; A.sub.8, A.sub.9, A.sub.10 : alkylene 
chain, cycloalkylene chain, substituted or unsubstituted arylene chain, 
##STR14## 
R.sub.15, R.sub.16, R.sub.17, R.sub.18 : hydrogen atom, alkyl group, or 
R.sub.15 and R.sub.16 or R.sub.17 and R.sub.18 may form a ring through an 
alkylene chain; 
A.sub.3, A.sub.4, a and the compounds (II) have the same meanings as 
defined above. 
B-2: the fluorine type graft polymer is a copolymer of a fluorine type 
oligomer of the formula (VI) having a polymerizable functional group at 
one terminal end and also having certain repeating units and a 
non-fluorine type polymerizable monomer selected from the compounds (IV). 
##STR15## 
wherein R.sub.12, x, A.sub.3, A.sub.5, A.sub.6, A.sub.7, a, b and the 
compounds (IV) have the same meanings as defined above. 
Synthesis of the macromer in B-1 can be accomplished by the method as 
disclosed in USP 3,689,593 wherein a prepolymer with carboxylic acid or 
alcohol at the terminal end is synthesized by radical polymerization with 
the use of a continuous chain transfer agent and double bonds are 
introduced by the reaction with isocyanate groups. A synthesis example of 
the macromer of methyl methacrylate is shown by the synthesis scheme (2): 
##STR16## 
Also by copolymerization of the thus synthesized methyl methacrylate 
macromer with a fluorine type polymerizable monomer, a fluorine type graft 
polymer having fluorine type segments in the trunk and non-fluorine type 
segments (methyl methacrylate oligomer) in the branch can be obtained 
similarly as described above. 
In the macromer synthesis of methyl methacrylate as described above, by use 
of a fluorine type polymerizable monomer in place of methyl methacrylate, 
a fluorine type macromer can be obtained and from copolymerization of the 
macromer with a non-fluorine type polymerizable monomer, fluorine type 
graft polymer having fluorine type segments in the branch and non-fluorine 
type segments in the trunk can be obtained. C-1: the fluorine type graft 
polymer is a copolymer of a non-fluorine type oligomer formed by the 
reaction of a living polymer intermediate of the formula (VII) having a 
polymerizable functional group at one terminal end and having certain 
repeating units with compounds represented by the formula (VIII) and a 
fluorine type polymerizable monomer selected from the compounds (II). 
EQU (R.sub.19 A.sub.11n R.sub.20 -O].sub.m).sup..crclbar. +M.sup..sym.(VII) 
R.sub.19 : hydrogen atom, alkyl group, aryl group; 
A.sub.11 : repeating unit comprising a polymer of at least one selected 
from styrene, .alpha.-alkylstyrene, .alpha.-olefin, (meth)acrylic acid 
ester, a-cyano(meth)acrylic acid ester; 
n: positive integer; 
R.sub.20 : alkylene chain; 
m: 0 or positive integer; 
##STR17## 
R.sub.21 : hydrogen atom, alkyl group, aryl group; A.sub.12 : 
##STR18## 
C: 0 ro 1; A.sub.13 : substituted or unsubstituted alkylene chain; d; 0 or 
1; 
Y: halogen atom. 
Synthesis of the macromer in C-1 can be accomplished by use of the anion 
polymerization method as disclosed in U.S. Pat. No. 3,786,116 and U.S. 
Pat. No. 3,928,255 in which a compound having unsaturated double bond is 
used as the stopping agent. A macromer synthesis example of styrene is 
shown by the synthesis scheme (3): 
##STR19## 
By copolymerization of the thus synthesized styrene macromer with a 
fluorine type polymerizable monomer, a fluorine type graft polymer having 
fluorine type segments in the trunk and non-fluorine type segment (styrene 
oligomer) in the branch can be obtained. 
In this case, the polymerizing component of the macromer is required to be 
selected from those having compatibility with the resin layer of the 
surface layer in which the fluorine type graft polymer formed is added or, 
even if not completely compatible, having similar structures, thus having 
affinity even to a small extent between the both. 
For example, when the surface resin layer is a poly(meth)acrylic acid 
ester, the macromer polymerizing component may be also preferably a 
(meth)acrylic acid ester, while a styrene type compound should preferably 
selected in the case of polystyrene or polycarbonate. 
The binder resin for forming the surface layer may be a polymer having film 
forming property, but it may be preferably polymethacrylate, polystyrene, 
methacrylic acid ester/styrene copolyme, polycarbonate, polyallylate, 
polyester, polysulfone, etc., from and the like The binder should have 
sufficient hardness and should not interfere with transport of carriers. 
In preparation of the electrophotographic photosensitive member of the 
present invention, the electroconductive substrate used may be a 
cylindrical cylinder or a film having an electroconductive layer 
containing electroconductive particles dispersed in an appropriate binder 
resin provided on a support made of a metal such as aluminum, stainless 
steel, etc., or paper, plastic, etc. However, when the support itself is 
electroconductive, no electroconductive layer may be provided on the 
electroconductive substrate. 
On these substrate, a subbing layer (adhesion layer) having the barrier 
function and the subbing function can be provided. 
The subbing layer is provided for the purpose of improving adhesiveness of 
the photosensitive layer, improving coatability, protecting the substrate, 
covering the defects on the substrate, improving charge injectability from 
the substrate, protecting the photosensitive layer against electrical 
destruction, etc. As the material for the subbing layer, there have been 
known polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl 
cellulose, methyl cellulose, ethylene-acrylic acid copolymer, casein, 
polyamide, copolymerized nylon, glue, gelatin, etc. 
These are applied as solutions dissolved in respective appropriate solvent, 
the film thickness may be about 0.2 to 2.mu.. 
As the charge generating substance, there may be employed cyanine type 
dyes, azulene type dyes, squarium type dyes, pyrylium type dyes, 
thiapyrylium type dyes, phthalocyanine type pigments, anthanthrone type 
pigments, dibenzpyrenequinone type pigments, pyranthorone type pigments, 
azo type pigments such as monoazo pigments, disazo pigments, trisazo 
pigments, etc., indigo type pigments, quinacridone type pigments, 
nonasymmetric quinocyanine, quinocyanine, etc. 
Examples of the charge transporting substance may include pylene; 
carbazoles such as N-ethylcarbazole, N-isopropylcarbazole, 
N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, 
N,N-diphenylhydrazino-3-methylidene- 9-ethylcarbazole; 
N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine; 
N,N-diphenylhydrazino-3-ethylidene-10-ethylphenoxazine; hydrazones such as 
p-diethylaminobenzaldehyde-N,N-diphenylhydrazone, 
p-diethylaminobenzaldehyde-N-.alpha.-naphthyl-N-phenylhydrazone, 
p-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 
1,3,3-trimethylindolenine-.omega.-aldehyde-N,N-diphenylhydrazone, 
p-diethylbenzaldehyde-3-methylbenzthiazolinone2-hydrazone, etc.; 
pyrazolines such as 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 
1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 
1-[quinolyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazolin 
e, 
1-[pyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline 
, 1-[6-methoxypyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenylp 
yrazoline, 
1-[pyridyl(3)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline 
, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)5-(p-diethylaminophenyl)pyrazoline 
, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl) 
pyrazoline, 
1-[pyridyl(2)]-3-(.alpha.-methyl-p-diethyl-aminostyryl)-5-(p-diethylaminop 
henyl)pyrazoline, 
1-phenyl-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazol 
ine, 
1-phenyl-3-(.alpha.-benzyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)p 
yrazoline, spiropyrazoline, etc.; oxazole type compounds such as 
2-(p-diethylaminostyryl)-6-diethylaminobenzoxazole, 
2-(p-diethylaminophenyl)-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazo 
le, etc.; thiazole type compounds such as 
2-(p-diethylaminostyryl)-6-diethylaminobenzthiazole, etc.; triarylmethane 
type compounds such as bis(4-diethylamino-2-methylphenyl)phenylmethane, 
etc.; polyarylalkanes such as 
1,1-bis(4-N,N-diethylamino-2-methylphenyl)heptane, 
1,1,2,2-tetrakis(4-N,N-diethylamino-2-methylphenyl)ethane, etc.; stilbene 
compounds such as 5-(4-diphenylaminobenzylidene)-5H 
dibenzo[a,d]cycloheptene, 1,2-benzo-3-(d-phenylstyryl)-9-n-butylcarbazole, 
etc. 
The method for preparing the electrophotographic photosensitive member of 
the present invention is described below by referring to an example of the 
case of the function separation type photosensitive member in which a 
charge transport layer is laminated on a charge generation layer. 
The above charge generating substance is well dispersed together with a 0.3 
to 10-fold amount of a binder resin and solvent according to the method by 
means of homogenizer, sonication, ball mill, vibrating ball mill, sand 
mill, attritor, roll mill, etc. The dispersion is applied on the above 
substrate coated with a subbing layer and dried to form a coating with a 
thickness of 0.1 to 1.mu.. 
In this example, the surface layer is a charge transport layer and 
therefore fluorine type resin powder is dispersed herein. 
That is, a binder resin, fluorine type resin powder and a fluorine type 
graft polymer are dispersed together with a solvent by a homogenizer, a 
sonication, ball mill, sand mill, attritor, roll mill, etc., and a 
solution of the charge transporting substance and a binder resin is added 
to the dispersion to make up a desired charge transport layer solution. 
The fluorine type graft polymer may be added during dispersion of the 
fluorine type resin powder to give the best effect in contributing to 
stability of the fluorine type resin powder. However, the fluorine type 
resin powder may be previously dispersed, followed by addition of the 
fluorine type graft polymer. 
The mixing ratio of the charge transporting substance and the binder resin 
may be about 2:1 to 1:4. 
As the solvent, aromatic hydrocarbons such as toluene, xylene, etc., 
chlorine type hydrocarbons such as dichloromethane, chlorobenzene, 
chloroform, carbon tetrachloride, etc., may be used. This solution may be 
coated according to, for example, dip coating, spray coating, spinner 
coating, bead coating, blade coating, curtain coating and other coating 
methods, and drying can be conducted at 10.degree. to 200.degree. C., 
preferably 20.degree. to 150.degree. C., for 5 minutes to 5 hours, 
preferably for 10 minutes to 2 hours, either under air stream or 
stationary conditions. The charge transport layer formed has a film 
thickness of about 10 to 30.mu.. 
On the other hand, in the case of a photosensitive member having a charge 
generation layer provided by coating on a charge transport layer, the 
charge generation layer becomes the surface layer and therefore the 
fluorine resin powder stabilized in dispersion with the fluorine type 
graft polymer is contained herein. The charge generation layer dispersion 
can be prepared by adding and mixing a dispersion having the fluorine type 
resin powder dispersed in a binder resin to be used for the charge 
generation layer with the use of the fluorine type graft polymer as the 
dispersing agent into a dispersion of the charge generating substance 
prepared as described above, and a photosensitive member of the present 
invention can be obtained by applying the dispersion on the charge 
transport layer. 
When the photosensitive layer has a protective layer, the protective layer 
becomes the surface layer of the photosensitive member and the fluorine 
type resin powder is stabilized in dispersion with the fluorine type graft 
polymer is contained in this protective layer. This protective layer can 
be obtained by applying a dispersion of the fluorine type resin powder 
stabilized in dispersion with the fluorine type graft polymer in a resin 
for forming the protective layer on the photosensitive layer. 
According to the present invention, since the electrophotographic 
photosensitive member containing fluorine type resin powder and fluorine 
type graft polymer contains the fluorine type resin powder dispersed 
uniformly to be improved in its dispersion stability, a constantly uniform 
surface layer can be obtained to give the results that no damage or image 
flow will be generated in the initial image as a matter of course and even 
after repeated successive copying, whereby images of high quality can be 
always obtained.

The present invention is described in more detail by referring to Examples. 
[EXAMPLES] 
Synthesis of fluorine type graft polymers (A-1 and A-2) 
Fluorine type graft polymers were synthesized on the basis of the macromer 
synthetic method disclosed in Japanese Laid-open Patent Publication No. 
164656/1983 in which the terminal double bond is introduced with glycidyl 
methacrylate by use of thioglycolic acid as the chain transfer agent. When 
this macromer is a non-fluorine type segment, copolymerization with a 
fluorine type polymerizable monomer was conducted, while when the macromer 
is fluorine type segment, copolymerization with a non-fluorine type 
polymerizable monomer was conducted to synthesize a fluorine type graft 
polymer. 
(i) Fluorine type graft polymer No. 1 
a. Synthesis of terminal methacrylate type methyl methacrylate macromer 
A glass flask equipped with an agitator, a reflux condenser, a dropping 
funnel, thermometer and a gas blowing inlet was charged with 10 parts of 
methyl methacrylate (hereinafter abbreviated as MMA) and 90 parts of a 
solvent mixture of acetone (17.5%)toluene and, after introduction of 
N.sub.2, polymerization was initiated under reflux by adding 0.5 parts of 
azobisisobutylonitrile (hereinafter abbreviated as AIBN) as the 
polymerization initiator and 0.35 parts of thioglycolic acid as the chain 
transfer agent. Then, within 5 hours, 90 parts of MMA were added dropwise 
continuously, and a solution of 2.9 parts of thioglycolic acid dissolved 
in 10 parts of toluene was added in 9 divided portions every 30 minutes, 
and similarly 1.5 parts of AIBN was added similarly in 4 divided portions 
every one hour to carry out polymerization. Further, the mixture was 
thereafter refluxed for 2 hours to complete polymerization and give a 
polymer solution of the following structural formula [I]. The reaction 
temperature was 77 to 87.degree. C. A part of the reaction mixture was 
reprecipitated with n-hexane and dried. The acid value of the polymer was 
measured to b 0.350 mg equivalent/g. 
##STR20## 
Next, after a part of acetone was evaporated from the above reaction 
mixture, 0.5 % of triethylamine as the catalyst and 250 ppm of 
hydroquinone monomethyl ether as the polymerization inhibitor were added, 
and a glycidyl methacrylate in an amount of 1.2-fold mols relative to the 
acid value was added, followed by the reaction under reflux (about 
110.degree. C.) for 12 hours. The conversion determined from reduction in 
acid value was 96 %. The reaction mixture was thrown into 10-fold amount 
of n-hexane to be precipitated, and then dried under reduced pressure at 
80.degree. C. to give 85 parts of a macromonomer of the following 
structural formula [II]. Molecular weights calculated on polystyrene by 
gel permeation chromatography (hereinafter called GPC) were found to be 
2780 (number average) and 6350 (weight average). 
##STR21## 
b. Synthesis of fluoroalkyl acrylate (trunk)/methyl mechacrylate 
(branch)-graft polymer 
The same device as in a was charged with 70 parts of the macromonomer of 
the above structural formula [II], 30 parts of a fluoroalkyl acrylate of 
the following structural formula [III], 300 parts of trifluorotoluene 
(C.sub.6 H.sub.5 CF.sub.3) and 0.35 parts of AIBN, and after introduction 
of N.sub.2, the reaction was carried out under reflux (about 100.degree. 
C) for 5 hours. 
##STR22## 
(mixture of n=4-12; average value of n is about 7) 
The reaction mixture was thrown into 10-fold amount of methanol to be 
precipitated and dried under reduced pressure at 80.degree. C. to obtain 
65 parts of a graft polymer. 
This polymer exhibited a single peak by GPC and the molecular weights 
calculated on polystyrene were found to be 18500 (number average) and 
29400 (weight average). 
Also, with addition of trifluorotoluene as the internal standard substance, 
.sup.1 H-NMR spectrum was measured in CDCl.sub.3 solvent, and the content 
of MMA units in the graft polymer was determined from the peak area ratio 
of H in trifluorotoluene to --O--CH.sub.3 in the MMA unit in the polymer 
to be 60%. The remaining 40% was attributed to fluoroalkyl acrylate. Thus, 
a fluorine type graft polymer with a content of the fluorine type segment 
of 40% was obtained. 
(ii) Fluorine type graft polymer No. 2, 3 
By changing the amount of fluoroalkyl acrylate charged, following otherwise 
the same operation as in the above (i), fluorine type graft polymers with 
fluorine type segment contents of 21% (No. 2) and 61% (No. 3), having 
molecular weights of 24,000 and 18,000 (number average), respectively, 
were synthesized. 
(iii) Fluorine type graft polymer NO. 4 
By use of the same device and the operation as in the above (i) except for 
changing methyl methacrylate to styrene, fluoroalkyl acrylate to 
2,3,5,6-tetrafluorophenylmethacrylamide of the following structural 
formula [IV](the amount charged was controlled to the same concentration 
of double bonds), a fluorine type graft polymer with a fluorine type 
segment content of 25% and a number average molecular weight of 36,000 was 
synthesized. The molecular weight of the styrene macromer was 7000. 
##STR23## 
(iv) Fluorine type graft polymer No. 5 
Under the same reaction conditions as in the above (i)-a except for 
changing methyl methacrylate to the fluoroalkyl acrylate in (i)-b, a 
fluorine type macromer with a number average molecular weight of 6600 was 
synthesized. Further, under the same conditions as in (i)-b except for 
using methyl methyacrylate in place of the fluoroalkyl acrylate in the 
above (i)-b, a fluorine type graft polymer comprising a branch of a 
fluorine type segment was synthesized. 
The content of the fluorine type segment was 25%, and the number average 
molecular weight was 42000. 
(v) Fluorine type graft polymer No. 6 
According to the same procedure as in (i)-a except for using 2.4 parts of 
2-mercaptoethanol in place of thioglycolic acid, a polymer solution of the 
following formula [V]was obtained. 
##STR24## 
Further, glycidyl methacrylate was reacted with the polymer in the same 
manner as in (i)-a to synthesize a macromer. The molecular weights 
calculated on polystyrene by GPC were found to be 3250 (number average) 
and 7800 (weight average). 
Next, in the same manner as in (i)-b, a graft polymer comprising a trunk of 
the fluoroalkyl acrylate and a branch of methyl methacrylate was 
synthesized. 
The fluorine type segment content was 30%, and the number average molecular 
weight was 32000. 
(vi) Fluorine type graft polymer No. 7 
According to the same procedure as in (i)-a except for using 2.4 parts of 
2-aminoethylmercaptan in place of thioglycolic acid and styrene in place 
of methyl methacrylate, a polymer solution of the following structural 
formula [VI]was obtained. 
##STR25## 
Further, glycidyl methacrylate was reacted with the polymer in the same 
manner as in (i)-a to synthesize a macromer. The molecular weights 
calculated on polystyrene by GPC were found to be 3450 (number average) 
and 7700 (weight average). 
Next, in the same manner as in (i)-b, a graft polymer comprising a trunk of 
the fluoroalkyl acrylate and a branch of methyl methacrylate was 
synthesized. The fluorine type segment content was 32%, and the average 
molecular weight was 46,000. 
Synthesis of fluorine type graft polymer (B-1 and B-2) 
Fluorine type graft polymers were synthesized on the basis of the macromer 
synthetic method disclosed in Japanese Laid-open Patent Publication No. 
164656/1983 or the macromer synthetic method disclosed in U.S. Pat. No. 
3,689,593 in which terminal double bonds are introduced with tolylene 
diisocyanate and 2-hydroxyethyl methacrylate by use of 2-mercaptoethanol 
as the chain transfer agent. 
When this macromer was a non-fluorine type segment, copolymerization with a 
fluorine type monomer was conducted, while when the macromer was a 
fluorine type segment, copolymerization with a non-fluorine type 
polymerizable monomer was conducted to obtain a fluorine type graft 
polymer. 
(vii) Fluorine type graft polymer No. 8 
a. Synthesis of terminal methacrylate type methyl methacrylate macromer 
A glass flask equipped with an agitator, a reflux condenser, a dropping 
funnel, thermometer and a gas blowing inlet was charged with 10 parts of 
MMA and 85 parts of a solvent mixture of acetone (17.5%)toluene and, after 
introduction of N.sub.2, polymerization was initiated under reflux by 
adding 0.5 parts of AIBN as the polymerization initiator and 0.27 parts of 
2-mercaptoethanol as the chain transfer agent. Then, within 5 hours, 90 
parts of MMA were added dropwise continuously, and a solution of 2.4 parts 
of 2-mercaptoethanol dissolved in 8 parts of toluene was added in 9 
divided portions every 30 minutes, and similarly 1.5 parts of AIBN was 
added similarly in divided portions every 1.5 hours to carry out 
polymerization. Further the mixture was thereafter refluxed for 2 hours to 
complete polymerization and give a polymer solution of the above 
structural formula [V]. The reaction temperature was 78.degree. to 
88.degree. C. 
Next, to the above polymer solution were added 6.0 parts of 
2,4-tolylenediisocyanate and 0.35 parts of dibutyl tin dilaurate, and the 
reaction was carried out at 78.degree. to 82.degree. C. for 30 minutes to 
obtain an isocyanate terminated polymer solution of the following 
structural formula [VII]. 
##STR26## 
Further, with addition of 4.45 parts of 2-hydroxyethyl methacrylate, the 
reaction was carried out at 78.degree. to 82.degree. C. for 60 minutes. 
Then, the reaction mixture was thrown into 10-fold amount of n-hexane to 
be precipitated, followed by drying under reduced pressure at 80.degree. 
C. to obtain 94 parts of a macromer of the following structural formula 
[VIII]: 
##STR27## 
The molecular weights calculated on polystyrene by GPC were found to be 
3040 (number average) and (weight average). 
b. Synthesis of graft polymer of fluoroalkyl acrylate (trunk)/methyl 
methacrylate (branch) 
The same device as in a was charged with 70 parts of the macromer of the 
above formula [VIII], 30 parts of a fluoroalkyl acrylate of the above 
formula III], 300 parts of trifluorotoluene (C.sub.6 H.sub.5 CF.sub.3) and 
0.35 parts of AIBN and, after introduction of N.sub.2, the reaction was 
carried out under reflux (about 100.degree. C.) for 5 hours. 
The reaction mixture was thrown into 10-fold amount of methanol to be 
reprecipitated, followed by drying under reduced pressure at 80.degree. C. 
to obtain 62 parts of a graft polymer. 
This polymer exhibited at single peak by GPC, and the molecular weights 
calculated on polystyrene were found to be 20500 (number average) and 
32000 (weight average). Also, with addition of trifluorotoluene as the 
internal standard substance, .sup.1 H-NMR spectrum was measured in 
CDCl.sub.3 solvent, and the content of MMA units in the graft polymer was 
determined from the peak area ratio of H in trifluorotoluene and H in 
--O--CH.sub.3 in MMA units of the polymer to be 72%. The remaining 28% was 
attributed to the fluoroalkyl acrylate. Thus, a fluorine type graft 
polymer No. 8 with a fluorine type segment content of 28% was obtained. 
(ii) Other fluorine type graft polymers 
By use of the starting materials shown in Table 1, various fluorine type 
graft polymers were synthesized according to the same synthetic method as 
described above. 
TABLE 1 
__________________________________________________________________________ 
Various fluorine type graft polymers 
Fluorine type graft 
Macromer constituents polymer properties 
Number Number 
Fluorine 
Chain Vinyl average 
Trunk segment 
average 
type 
Vinyl transfer 
Isocyanate 
terminated 
molecular 
Vinyl monomer 
molecular 
segment 
No. 
monomer 
agent compound 
monomer weight 
constituting trunk 
weightt 
content 
__________________________________________________________________________ 
9 Styrene 
2-mercapto- 
1,6-hexa- 
2-hydroxy- 
2130 Fluoroalkyl acrylate 
44200 22 wt. % 
aminoethane 
methylene- 
ethyl- (the same as No. 1) 
diisocyanate 
methacrylate 
10 Methyl- 
3-mercapto- 
2.4. TDI 
Methacrylic 
3170 2,3,5,6-tetrachlorophenyl 
60800 10 wt. % 
methacrylate/ 
propionic acid methacrylate*.sup.1 
styrene 
acid 
(weight ratio: 
20/80) 
11 Styrene 
2-mercapto- 
4,4-diphenyl- 
2-aminoethyl 
6620 Fluoroalkyl acrylamide 
84600.2 
28 wt. % 
ethanol 
methane- 
methacrylate 
diisocyanate 
12 Fluoroalkyl- 
2-mercapto- 
4,4-dicyclo- 
2-aminoethyl 
3920 Styrene 57300 15 wt. % 
acrylate 
ethanol 
hexylmethane- 
methacrylate 
diisocyanate 
13 Fluoroalkyl- 
3-mercapto- 
isophorone- 
3-hydroxy- 
1860 Methyl methacrylate 
19400 43 wt. % 
acrylate 
propionic 
diisocyanate 
propyl- 
acid methacrylate 
__________________________________________________________________________ 
##STR28## 
*.sup.2 Fluoroalkyl acrylamide 
##STR29## 
(n: mixture of 4-12, average of n: about 7) 
Synthesis of fluorine type graft polymer (C-1) 
Fluorine type graft polymers were synthesized on the basis of the macromer 
synthetic method according to the anion polymerization method disclosed in 
U.S. Pat. No. 3,786,116 or U.S. Pat. No. 3,928,255 in which a compound 
having unsaturated double bond is used as the stopping agent. By 
copolymerization of these macromers with a fluorine type polymerizable 
monomer, fluorine type graft polymers can be obtained. 
(viii) Fluorine type graft polymer No. 14 
a. Synthesis of vinyl terminated styrene macromer 
A stainless steel reactor was charged with 80 parts of dehydrated benzene, 
which was raised in temperature to 40.degree. C. and one drop of 
diphenylethylene was added thereto. With addition of 30 ml of 12% pentane 
solution of t-butyllithium and further 321 parts of styrene, the reaction 
was carried out at 40.degree. C. for 30 minutes. Next, 8 ml of 
vinyl-2-chloroethyl ether was added to stop the reaction. The reaction 
mixture was added dropwise into methanol to reprecipitate the polymer. The 
polymer was separated by filtration and dried under reduced pressure at 
80.degree. C. to obtain a styrene macromer of the following formula [IX]. 
##STR30## 
The molecular weights calculated on polystyrene by GPC was 6400 (number 
average). 
b. Synthesis of a graft polymer of fluoroacrylate (trunk)/styrene (branch) 
A glass flask equipped with an agitator, a reflux condenser, a dropping 
funnel, a thermometer and a gas blowing inlet was charged with 70 parts of 
the styrene macromer of the above structural formula [IX], 30 parts of the 
fluoroacrylate of the above structural formula [III], 280 parts of 
trifluorotoluene (C.sub.6 H.sub.5 CF.sub.3), and 0.35 parts of AIBN, and 
after introduction of N.sub.2, the reaction was carried out under reflux 
(about 100.degree. C.) for 5 hours. 
The reaction mixture was thrown into 10-fold amount of methanol to be 
reprecipitated, followed by drying under reduced pressure at 80.degree. C. 
to obtain a graft polymer. This polymer was found to have a number average 
molecular weight of 48,300 as measured by GPC. 
Also, with addition of trifluorotoluene as the internal standards 
substance, .sup.1 H-NMR spectrum was measured in CDCl.sub.3 solvent, and 
the content of units in the graft polymer was determined from the peak 
area ratio of H in trifluorotoluene to the aromatic ring H in styrene 
units in the polymer to be 72%. The remaining 28% was attributed to the 
fluoroalkyl acrylate. Thus, fluorine type graft polymer number 14 with a 
content of the fluorine type segment of 28% was obtained. 
(ii) Other fluorine type graft polymers 
By use of the starting materials shown in Table 2, various fluorine type 
graft polymers were synthesized according to the same synthetic method as 
described above. 
TABLE 2 
__________________________________________________________________________ 
Various fluorine graft polymer 
Fluorine type 
Fluorine type graft 
Macromer constituent vinyl monomer 
polymer properties 
Number average 
constituting 
Number average 
Fluorine type 
No. 
Vinyl monomer 
Stopping agent molecular weight 
trunk segment 
molecular 
segment 
__________________________________________________________________________ 
content 
15 .alpha.-methyl- 
CH.sub.2CHOCH.sub.2 CH.sub.2 Cl 
4370 Fluoroalkyl 
56300 24 wt % 
styrene acrylate 
16 .alpha.-cyanoethyl acrylate 
##STR31## 6480 Fluoroalkyl acrylate (the same as No. 
1) 72500 41 
17 Styrene 
##STR32## 2410 2,3,5,6-tetra*.sup.1 chlorophenyl 
methacrylate 
28600 18 
18 .alpha.-methyl- styrene 
##STR33## 3850 Fluoroalkyl*.sup.2 acrylamide 
49400 12 
19 Methyl methacrylate 
##STR34## 2870 Fluoroalkyl*.sup.3 vinyl 
38600 37 
##STR35## 
__________________________________________________________________________ 
##STR36## 
- - 
##STR37## 
n: mixture of 4-12 - 
##STR38## 
n: mixture of 4-12 (average of n = 7) 
EXAMPLE 1 
A substrate of aluminum cylinder with 80 mm diameter and 300 mm length was 
coated by dipping with a 5% methanolic solution of a polyamide (trade 
name, Amilane CM-4000, produced by Toray K.K.) to provide a subbing layer 
with a thickness of 1.mu.. 
Next, 10 parts (parts by weight, hereinafter the same) of a disazo pigment 
having the following structural formula: 
##STR39## 
5 parts of polyvinylbutyral (tradename S-Lec BM-2, produced by Sekisui 
Kagaku K.K.) and 50 parts of cyclohexanone were dispersed in sand mill by 
use of glass beads of 1 mm diameter for 20 hours. To this dispersion were 
added 70 to 120 (as desired) parts of methyl ethyl ketone, and the 
dispersion was applied on the subbing layer to form a charge generation 
layer with a thickness of 0.20.mu.. 
Next, 10 parts of a polymethyl methacrylate (trade name: Dianal BR-85, 
produced by Mitsubishi Rayon K.K.), 10 parts of a polytetrafluoroethylene 
(trade name: Lubron L-2, produced by Daikin Kogyo K.K.) and 0.5 parts of 
the above No. 1 fluorine type graft polymer were dissolved in 40 parts of 
monochlorobenzene and 30 parts of tetrahydrofuran, and the mixture was 
dispersed in a stainless steel ball mill for 48 hours. With 10 parts of 
the dispersion obtained were mixed 70 parts of a resin solution containing 
10 parts of a hydrazone compound having the structural formula shown 
below: 
##STR40## 
and 10 parts of the above polymethyl methacrylate dissolved in 60 parts of 
monochlorobenzene to prepare a charge transport layer solution. Also, by 
use of the fluorine type graft polymers of Nos. 8 and 14, charge transport 
layer solutions were prepared similarly. The mean particle sizes of the 
polytetrafluoroethylene powder in the charge transport layer solutions 
were measured to be 0.45.mu., 0.46.mu. and 0.48.mu., respectively by a 
particle size distribution measuring machine (CAPA-500, produced by Horiba 
Seisakusho). 
Each of these solutions was applied on the above charge generation layer, 
followed by drying in hot air at 110.degree. C. for 90 minutes to form a 
charge transport layer with a thickness of 18.mu.. These are called 
samples 1, 2 and 3, respectively. The surface of the charge transport 
layer obtained was found to be uniform and smooth. The average surface 
roughness of this surface layer was 0.2.mu. or less, which was equal to 
the average surface roughness of the charge transport layer surface formed 
of a charge transport material containing no fluorine type resin powder 
and a binder resin. 
For comparison, by use of a material in which no fluorine type graft 
polymer was added, a photosensitive member was prepared in the same manner 
as described above. This is called comparative sample 4. 
The comparative sample 4 exhibited excessive agglomeration of the 
polytetrafluoroethylene powder in the surface layer to give a state which 
is unsatisfactory for evaluating images. 
On the other hand, a photosensitive member in which no 
polytetrafluoroethylene and fluorine type graft polymer was added was 
prepared in the same manner as described above. This is called comparative 
sample 5. 
For these respective samples, successive copying characteristic of 30,000 
sheets was evaluated by an electrophotographic process comprising -5.5 KV 
corona charging, image exposure, dry toner development, transfer onto 
plane paper, cleaning with silicon rubber cleaning roller, urethane rubber 
blade and pre-exposure. The results are shown in Table 3. 
TABLE 3 
__________________________________________________________________________ 
Fluorine 
type graft 
Initial 
Successive copying at 
Successive copying at 
polymer No. 
image 23.degree. C., 55% RH 
32.5.degree. C., 90% RH 
__________________________________________________________________________ 
Sample 1 
1 Good Stable image of high 
Stable image of high 
quality up to 30000 
quality up to 30000 
sheets sheets 
Sample 2 
8 Good Stable image of high 
Stable image of high 
quality up to 30000 
quality up to 30000 
sheets sheets 
Sample 3 
14 Good Stable image of high 
Stable image of high 
quality up to 30000 
quality up to 30000 
sheets sheets 
Comparative 
-- Black dots 
Not worthwhile succes- 
Not worthwhile succes- 
sample 4 on whole 
sive copying 
sive copying 
surface 
Comparative 
-- Good Friction damage after 
Image flow generated 
sample 5 10000 sheets, toner 
after 8000 sheets 
fusion on the surface 
after 20000 sheets 
__________________________________________________________________________ 
EXAMPLE 2 
A substrate of aluminum cylinder with 80 mm diameter and 300 mm length was 
coated by dipping with a 5% methanolic solution of a polyamide (trade 
name, Amilane CM-4000, produced by Toray K.K.) to provide a subbing layer 
with a thickness of 1.mu.. 
Next, a charge generation layer was formed with the same material and 
according to the same method as in Example 1. 
Next, 10 parts of a bisphenol Z type polycarbonate (produced by Mitsubishi 
Gas Kagaku K.K.), 20 parts of a polyvinylidene fluoride (trade name Kynar 
K-301F, produced by Penwald Co.) and 3 parts of the above fluorine type 
graft polymer of No. 4 were dissolved in 50 parts of cyclohexanone and 20 
parts of tetrahydrofuran, and the mixture was dispersed in a sand mill 
device by use of 1 mm diameter glass beam for 20 hours. With 10 parts of 
the resultant dispersion were mixed 70 parts of a resin solution 
containing 12 parts of a pyrazoline compound of the following structural 
formula: 
##STR41## 
and 10 parts of the above polycarbonate resin dissolved in 40 parts of 
cyclohexanone and 20 parts of tetrahydrofuran to prepare a charge 
transport layer solution. Also, by use of the fluorine type graft polymers 
of No. 9 and 15, charge transport layer solutions were prepared similarly 
as described above, respectively. The mean particle sizes of the 
polyvinylidene fluoride were found to be 0.42.mu., 0.45.mu. and 0.48.mu., 
respectively. Each of these solutions was applied on the above charge 
generation layer, followed by drying in hot air at 110.degree. C. for 90 
minutes to form a charge transport layer with a thickness of 20.mu.. These 
are called samples 6, and 8. The surface roughness was found to be 0.2.mu. 
or less. 
For comparison, a photosensitive member was prepared in the same manner as 
described above by use of a material containing no fluorine type graft 
polymer added. This is called comparative sample 9. 
The comparative sample 9 exhibited excessive agglomeration of the 
polyvinylidene fluoride powder in the surface layer to give a state which 
is unsatisfactory for evaluating images. 
On the other hand, a photosensitive member was prepared in the same manner 
as described above by use of a material containing no polyvinylidene 
fluoride and no fluorine type graft polymer added. This is called 
comparative sample 10. 
For these respective samples, successive copying characteristics of 30,000 
sheets were evaluated by an electrophotographic process comprising -5.5 KV 
corona charging, image exposure, dry process toner development, transfer 
onto plane paper, cleaning with urethane rubber blade and silicon rubber 
cleaning roller and pre-exposure. The results are shown in Table 4. 
TABLE 4 
__________________________________________________________________________ 
Fluorine 
type graft 
Initial 
Successive copying at 
Successive copying at 
polymer No. 
image 23.degree. C., 55% RH 
32.5.degree. C., 90% RH 
__________________________________________________________________________ 
Sample 6 
4 Good Stable image of high 
Stable image of high 
quality up to 30000 
quality up to 30000 
sheets sheets 
Sample 7 
9 Good Stable image of high 
Stable image of high 
quality up to 30000 
quality up to 30000 
sheets sheets 
Sample 8 
15 Good Stable image of high 
Stable image of high 
quality up to 30000 
quality up to 30000 
sheets sheets 
Comparative 
-- Black dots 
Not worthwhile 
Not worthwhile 
sample 9 on whole 
evaluation evaluation 
surface 
Comparative 
-- Good Toner fusion after 
Image flow generated 
sample 10 6000 sheets 
after 5000 sheets 
__________________________________________________________________________ 
EXAMPLE 3 
10 parts of the hydrazone compound used in Example 1 and 10 parts of a 
styrene-methyl methacrylate copolymer (trade name: Estyrene MS-200, 
produced by Shinnippon Seitetsu K.K.) were dissolved in 60 parts of 
monochlorobenzene. This solution was applied by coating on the aluminum 
cylinder of 80 mm diameter.times.300 mm length coated with a subbing layer 
similarly as in Example 1, followed by drying at 100.degree. C. for 1 hour 
to form a charge transport layer of 12 .mu.. 
Next, 10 parts of a disazo pigment of the following structural formula: 
##STR42## 
5 parts of a polytrifluorochloroethylene powder (produced by Daikin Kogyo 
K.K.) and 1 part of the above fluorine type graft polymer of NO. 2 were 
added into 100 parts of a 10 wt.% cyclohexanone solution of the above 
styrene/methyl methacrylate copolymer and dispersed in a stainless steel 
ball mill for 50 hours. This solution was thrust coated on the above 
charge transport layer, followed by drying at 100.degree. C. for 20 
minutes to form a charge generation layer with a thickness of 2.mu.. Also, 
by use of the fluorine type graft polymer of Nos. 10 and 16, charge 
generation layers were formed in the same manner as described above, 
respectively. The mean particle sizes of the polytrifluorochloroethylene 
powder in the charge generation layer solution were found to be 0.52.mu., 
0.50.mu. and 0.54.mu., respectively. The photosensitive members prepared 
are called samples 11, 12 and 13. The surface roughness for each sample 
was 0.2.mu. or less. 
For comparison, by use of a material containing no fluorine type graft 
polymer added, a photosensitive member was prepared in the same manner as 
described above. This is called comparative sample 14. 
The comparative sample 14 exhibited excessive agglomeration of the 
polytrifluorochloroethylene powder in the surface layer to give a state 
unsatisfactory for evaluating images. 
On the other hand, by use of a material containing no 
polytrifluorochloroethylene and no fluorine type graft polymer added, a 
photosensitive member was prepared in the same manner as described above. 
This is called comparative sample 15. Each of these samples was mounted on 
an electrophotographic copying machine having the steps of +5.6 KV corona 
charging, image exposure, drying process toner development, transfer onto 
plain paper, cleaning with urethane rubber blade and pre-exposure and 
successive copying characteristic of 10,000 sheets was evaluated. The 
results are shown in Table 5. 
TABLE 5 
__________________________________________________________________________ 
Fluorine 
type graft 
Initial 
Successive copying at 
Successive copying at 
polymer No. 
image 23.degree. C., 55% RH 
32.5.degree. C., 90% RH 
__________________________________________________________________________ 
Sample 11 
2 Good Stable image of high 
Stable image of high 
quality up to 10000 
quality up to 10000 
sheets sheets 
Sample 12 
10 Good Stable image of high 
Stable image of high 
quality up to 10000 
quality up to 10000 
sheets sheets 
Sample 13 
16 Good Stable image of high 
Stable image of high 
quality up to 10000 
quality up to 10000 
sheets sheets 
Comparative 
-- Black dots 
Not worthwhile 
Not worthwhile 
sample 14 on whole 
evaluation evaluation 
surface 
Comparative 
-- Good Friction damage after 
Image flow generated 
sample 15 3000 sheets 
after 2000 sheets 
__________________________________________________________________________ 
EXAMPLE 4 
One part of aluminum chloride phthalocyanine, 10 parts of a polysulfone 
resin (trade name: Udel Polysulfone P-3500, produced by Nissan Kagaku 
K.K.), 7 parts of polytetrafluoroethylene-hexafluoropropylene copolymer 
powder (produced by Daikin Kogyo K.K.) and 2 parts of the above fluorine 
type graft polymer of No. 3 were dispersed together with 40 parts of 
monochlorobenzene and 10 parts of tetrahydrofuran in a sand mill by use of 
1 mm diameter glass beads for 20 hours, and to the resultant dispersion 
were added 6 parts of the pyrazoline compound used in Example 2. Also, by 
use of the fluorine type graft polymers of Nos. 11 and 17, solutions were 
prepared similarly as described above. The mean particle sizes of the 
polytetrafluoroethylene-hexafluoropropylene copolymer powders in these 
solutions were found to be 0.38.mu., 0.46.mu. and 0.48.mu., respectively. 
Each of these solutions was applied by coating on the 80 mm 
diameter.times.300 mm length aluminum cylinder coated with the subbing 
layer similarly as in Example 2 to provide a photosensitive layer of 
14.mu.. The surface roughness was found to be 0.2.mu. or less. The 
photosensitive members prepared are called samples 16, 17 and 18, 
respectively. 
For comparison, by use of a material containing no fluorine type graft 
polymer added, a photosensitive member was prepared similarly as described 
above. This is called comparative sample 19. The comparative sample 19 
exhibited excessive agglomeration of the 
polytetrafluoroethylene-hexafluoropropylene copolymer powder in the 
surface layer to give a state unsatisfactory for evaluating images. 
On the other hand, by use of a material containing no 
polytetrafluoroethylene-hexafluoropropylene copolymer and no fluorine type 
graft polymer, a photosensitive member was prepared similarly as described 
above. This is called comparative sample 20. 
For these respective samples, successive copying characteristics of 10,000 
sheets were evaluated by an electrophotographic process comprising -5.5 KV 
corona charging, image exposure, dry type toner development, transfer onto 
plain paper, cleaning with urethane rubber blade and pre-exposure. The 
results are shown in Table 6. 
TABLE 5 
__________________________________________________________________________ 
Fluorine 
type graft 
Initial 
Successive copying at 
Successive copying at 
polymer No. 
image 23.degree. C., 55% RH 
32.5.degree. C., 90% RH 
__________________________________________________________________________ 
Sample 16 
3 Good Stable image of high 
Stable image of high 
quality up to 10000 
quality up to 10000 
sheets sheets 
Sample 17 
11 Good Stable image of high 
Stable image of high 
quality up to 10000 
quality up to 10000 
sheets sheets 
Sample 18 
17 Good Stable image of high 
Stable image of high 
quality up to 10000 
quality up to 10000 
sheets sheets 
Comparative 
-- Black dots 
Not worthwhile 
Not worthwhile 
sample 19 on whole 
evaluation evaluation 
surface 
Comparative 
-- Good Toner fusion after 
Image flow generated 
sample 20 2000 sheets 
after 1500 sheets 
__________________________________________________________________________ 
EXAMPLE 5 
By use of 10 parts of the bisphenol Z type polycarbonate used in Example 2, 
20 parts of a polyvinyl fluoride (produced by Daikin Kogyo K.K.) and 3 
parts of the above fluorine type graft polymer of No. 5, a dispersion was 
prepared in the same manner as in Example 2. With 90 parts of the 
resultant dispersion were mixed 70 parts of a resin solution containing 20 
parts of the above polycarbonate resin dissolved in 40 parts of 
cyclohexanone and 20 parts of THF to prepare a protective layer solution. 
Also, by use of the fluorine type graft polymers of Nos. 12 and 18, 
protective layer solutions were prepared similarly as described above. The 
mean particle sizes of the polyvinyl fluoride powder in these solutions 
were found to be 0.45.mu., 0.47.mu. and 0.48.mu., respectively. Each of 
these protective layer solutions was thrust coated on the surface layer of 
the comparative sample 10 prepared in Example 2, followed by drying in hot 
air at 100.degree. C. for 30 minutes to form a protective layer of 3.mu.. 
The surface roughness was found to be 0.2.mu. or less. These are called 
samples 21, 22 and 23, respectively. Each of these samples was subjected 
to successive copying tests of 30,000 sheets similarly as described in 
Example 2. As the result, stable images of high quality were obtained up 
to 30,000 sheets both under the conditions of 23.degree. C. and 55% RH and 
32.5.degree. C. and 90% RH . 
EXAMPLE 6 
A solutions of 6 parts of a polymethyl methacrylate (trade name: Dianal 
BR-85, produced by Mitsubishi Rayon K.K.), 10 parts of a 
difluorochloroethylene (produced by Daikin Kogyo K.K.) and 0.5 parts of 
the above fluorine type graft polymer of No. 6 dissolved in 40 parts of 
monochlorobenzene and 30 parts of tetrahydrofuran was dispersed in a 
stainless steel ball mill for 48 hours in the resultant dispersion and 6 
parts of the hydrazone compound used in Example 1 was dissolved in the 
resulting dispersion to prepare a charge transport layer solution. The 
charge transport layer solution was applied on the charge generation layer 
prepared in the same manner as in Example 1 to prepare an 
electrophotographic photosensitive member. The mean particle size of the 
polydifluorochloroethylene powder in the charge transport layer solution 
was found to be 0.48.mu., and the charge transport layer surface obtained 
was found to be uniform and smooth, with the average surface roughness 
being 0.2.mu. or less. This is called sample 24. When this sample was 
subjected to successive copying test of 30,000 sheets similarly as in 
Example 1, stable images of high quality were obtained up to 30,000 sheets 
both under the conditions of 23.degree. C. and 55% RH, 32.5.degree. C. and 
90% RH. 
EXAMPLE 7 
An electrophotographic photosensitive member was prepared according to 
entirely the same procedure as in Example 2 except for using the fluorine 
type graft polymer of No. 7 in place of the fluorine type graft polymer 
No. 4 and a vinylidene fluoride-hexafluoro propylene copolymer in place of 
the polyvinylidene fluoride. The mean particle size of the vinylidene 
fluoride-hexafluoropropylene copolymer powder in the charge transport 
layer solution was found to be 0.49.mu., and the charge transport layer 
surface obtained was uniform and smooth, with the surface roughness being 
0.2.mu. or less. This is called sample 25. When this sample was subjected 
to successive copying test of 30,000 sheets similarly as in Example 2, 
stable images of high quality were obtained up to 30,000 sheets both under 
the conditions of 23.degree. C., 55% RH and 32.5.degree. C., 90% RH. 
Next, by use of the same material, charge transport solutions with contents 
of the vinylidene fluoride-hexafluoropropylene copolymer of 0.5 wt. % and 
60 wt. % were prepared and electrophotographic photosensitive members were 
prepared similarly as described above and successive copying evaluations 
were conducted. As the result, for the sample containing 0.5 wt. % of the 
vinylidene fluoride-hexafluoropropylene copolymer, toner fusion was 
generated at a successive copying of 6,500 sheets under the conditions of 
23.degree. C. and 55% RH, and image flow was generated after successive 
copying of 5,000 sheets under the conditions of 32.5.degree. C. and 90% 
RH. On the other hand, for the sample containing 60 wt. % of the 
copolymer, no toner fusion or image flow was generated after 30,000 sheets 
under both environments, but black fog accompanied with increase of the 
light portion potential by lowering the mobility of carriers was generated 
after about 10,000 sheets.