Note: Descriptions are shown in the official language in which they were submitted.
11;~ 9~26
r
PHOTOCONDUCTIVE C MPOSITIONS
This invention relates to electrophotography
and particularly to light sensitive materials for photo-
- conductive compositions.
BACKGROUND OF THE INVENTION
Electrophotographic imaging processes and
techniques have been extensively described in the prior
art. Generally~ such processes have in common the
steps of employing a photoconductive element which is
prepared to respond to image-wise exposure to electro-
magnetic radiation thereby forming a latent-electrostatic-
charge image. A variety of subsequent operations, nowwell-known in the art, can then be employed to produce
a permanent record of the image.
One type of photoconductive element particu-
; larly useful in electrophotography employs a composition
23 containing a photoconductive material and optionally an
electrlcally insulating, film-forming, resinous binding
material. An lntegrated electrophotographic element
incorporating such a compositlon is generally produced
in a multi-layer type Or structure by coating a layer
of the above described composition onto a support
previously overcoated with a layer of an electrically
conducting material. Alternatively, the above-descrlbed
composltion can be coated dlrectly onto a conductlve
support made of metal or other sultable conductlve
3 materials.
Usually, the desired electrophotographic
properties are dictated by the end use contemplated for
the photoconductive element. In many such applications,
it is desirable for the photoconductive element to
exhibit high speed, as measured by an electrical speed
; or characteristic curve, a low residual potential after
exposure and resistance to electrical fatigue. Various
. other applications specifically require that the
B 4
1~294;~
--2--
photoconductive element be capable of accepting a high
surface potential with a low dark decay rate.
In many other applications, it is desirable
that the photoconductive element be capable of high
speeds and relatively high resolution as measured in
terms o~ lines per millimeter. Typical applications
where high resolution images are necessary are one to
one microfilm reproductions, and the production of
microimages from regular sized images. Ideally, a
microfilm duplicating system should provide exact
micro-duplicates of existing microfilm frames or micro-
images of normal-sized copy with no loss in resolution
from the original.
High speed "heterogeneous" or "aggregate"
15 photoconductive systems have been developed which
exhibit many of the desirable qualities mentioned
above. I'hese aggregate compositions are the sub~ect
matter of William A. Light, U.S. Patent 3,615,414
issued October 26, 1971 and Gramza et al., U.S. Patent
3,732,180 issued May 8, 1973. These heterogeneous or
aggregate photoconductive elements comprise photocon-
ductive compositions containing a continuous polymer
phase having dispersed therein co-crystalline particles
composed of a pyrylium or thiopyrylium salt and a
25 polymer. However, the resolutlon obtainable with
heterogeneous or aggregate photoconductive elements is
not as hlgh as the resolution obtainable with some
other types of photoconductive elements having much
lower speeds such as the elements disclosed in U.S.
Patent 3,542,547.
The use of thiopyrylium dye salts in photo-
conductive compositions is also disclosed in Contois et al.,
U.s. 3,973,962, issued August 10, 1976, and Van Allan
et al., U.S. 3,250,615 issued May 10, 1966. Certain
35 monomethine thiopyrylium dye salts are also disclosed
as sensitizers for photoconductive compositions in
Reynolds et al., U.S. 3,938,994 issued February 17,
1976.
1129426
--3--
SUMMARY OF THE INVENTION
The present invention provides photoconductive
compositions and elements which comprise a film forming
electrically insulating polymer, a dye material having
an absorption spectrum which changes when a binderless
coating of said dye material is treated with a solvent
vapor and, if desired, an organic photoconductor mater-
ial; wherein said composition has an absorption spectrum
which is substantially similar to the changed absorption
spectrum of said binderless coated dye material.
The present invention also provides a method
of making the photoconductive compositions of the
present invention.
The photoconductive compositions of the present
invention are obtained by treating a composition com-
prising a dye material of the type described above and
an electrically insulating polymer with solvent vapors
of the type described hereinafter. The vapor treatment
causes a transformation of the photoconductive composi-
tion that is evidenced by a speed increase and a changein the absorption spectrum of said photoconductive
composition. As stated above the changed absorption
spectrum of the photoconductive composition is substan-
tially similar to the absorption spectrum of the dye
material used therein when a binderless coating of said
dye material is treated with solvent vapors.
Any dye material which has (1) an absorption
spectrum which changes when a binderless coating of the
dye is treated with a solvent vapor and (2) exhibits an
absorptlon spectrum substantially similar to said
changed absorption spectrum in a solvent vapor treated
photoconductive composition comprising said dye material
and an electrically insulating polymer will be useful
in forming the compositions of the invention. Thus,
useful dye materials can be easily identified by first
combining the dye material being considered with a
coating solvent of the type disclosed hereinafter and
secondly, incorporating said dye material in a photo-
conductive composition which includes an electrically
insulating polymer. The resulting mixtures are then
llZ94Z6
--4--
coated on separate transparent supports of the type
disclosed hereinafter. After the coatings dry, the
abæorption spec~rum of each coating is determined in
a conventional manner, one being tested before sol-
S vent vapor treatment of the coating and the othertested during such treatment. If the dye material
being tested is suitable for use in forming the com-
positions of the present invention, (1) the absorp-
tion spectrum of the binderless coating during sol-
vent vapor treatment will be different from theabsorption spectrum of the same coating before sol-
vent treatment and (2) the absorption spectrum of a
solvent vapor-treated photoconductive composition
comprising said dye material and an electrically
insulating polymer will be sub6tantially similar to
the changed absorption spectrum of the binderless
coated dye material.
The foregoing test also serves to distin-
guish the photoconductive compositions of the present
invention from the aggregate photoconductive composi-
tions disclosed and claimed in the aforementioned
Light and Gramza patents. The latter aggregate pho-
toconductive compositions appear to result from
dye-polymer co-crystallization induced by solvent
treatment. This dye-polymer co-crystallization is
evidenced by the co-crystals of dye and polymer which
are present in aggregate photoconductive compositions.
It is believed that the change in absorption
spectrum exhibited by vapor-treated binderless coat-
ings of the dye materials useful in the presentinvention results from dye-dye interaction rather
than dye-polymer co-crystallization. Dye-dye inter-
action refers to interaction between individual mole-
cules or groups of molecules of the same or similar
dye materials. The absorption spectra of the pyr-
ylium dye salts used to form the aforementioned
aggregate photoconductive compositions also change
when a binderless coating of such dye salts is
treated with solvent vapors. However, the absorption
spectra of vapor-treated compositions comprising an
electrically insulating polymer and the aforemen-
tioned pyrylium dyes are different from that of a
vapor-treated binderless coating of the pyrylium dye.
~29426
--5--
Figure 1 shows the absorption spectrum of one
of the photoconductive compositions of the present
invention before and after transformation.
Preferred Embodiments
.. ...
In a preferred embodiment of the present
invention there are provided photoconductive compositions
and elements comprising a film forming electrically
insulating polymer and a dye material which has (a) an
absorption spectrum which changes when a binderless
coating of said dye material is treated with a solvent
and (b) a structure according to the formula
\ ~ C\ /; ~c6H5 (I)
. C H C6H5
wherein Z and zl may be the same or different, repre-
~r~ sent 0, Se and S and X represents an anion such as
O~ 15 perchlorate or fluoroborate; wherein said compositions
have after transformation an absorption spectrum which
is similar to the changed absorption spectrum of said
binderless coated dye material.
According to another embodiment of the present
invention photoconductive compositions are provided as
~ust described which also contain an organic photocon-
ductive material.
Useful materials included within the scope of
general Formula I lnclude the materials shown in Table I.
T_A B L E
~Z ~ ~ Dye MateriaI Name
v~
1. 4-[(2,6-diphenyl-4H-thiopyran-4-ylidene)-
I ~ methyl]-2,6-diphenylthiopyrylium per-
chlorate
2. 4-[(2,6-diphenyl-4H-thiopyran-4-ylidene)-
methyl]-2,6-diphenylselenopyrylium per-
chlorate
3. 4-[(2,6-diphenyl-4H-thiopyran-4-ylidene)-
methyl]-2,6-diphenylthiopyrylium fluoro-
borate
!
~ llZ94Z6
--6--
~~ T A B L E I Cont'd.
4. 4-[(2 ,6-diphenyl-4H-pyran-4-ylidene)-
methyl]-2,6-diphenylthiopyrylium per-
chlorate
5 ~ 5. 4-[(2,6-diphenyl-4H-pyran-4-ylidene)-
,~p methyl~-2,6-diphenylselenopyrylium per-
chlorate
6. 4-[(2,6-diphenyl-4H-pyran-4-ylidene)-
methyl~-2,6-diphenylpyrylium perchlo-
rate
The symetrical pyrylium and thiopyrylium
monomethine dyes of Formula I may be prepared
according to the procedure described in U.S. Patent
3,938 ,994. The prep~ration of the sulfur-oxygen
unsymetrical monomethine pyrylium dyes is taught by
G. A. Reynolds and J. A. VanAllan, J. Heterocyclic
Chem., 9, 1105 (1972). The preparation of symetrical
monomethine selenopyrylium, as well as thiopyrylium
dyes, iB taught by A. J. Tolmachev and M. A.
Kudinova, Khimiya Geterotsiklicheskikh Soedinenii, 49
(1974)-
The unsymetricsl selenopyrylium dyes are new
_ compoæitions of matter prepared a8 follows: In
Structures III and IV, Z represents 0 or S.
Z 0 CH
25H C~0~5~ ~C HH C~ ~ \C~H~
(II) (III)
. 3( ~
~ F o ~ Z C l o~
~o H~C ~ C H
(IY)
f A mixture of 0.31 B of (II) and 0.35 g of (III) in 10
ml of acetic anhydride was refluxed for 30 minutes
and cooled to room temperature, during which time
glistening needles of the desired material formed.
9426
--7--
As stated above, the photoconductive composi-
tions of the present invention are obtained by treating
compositions comprising a dye material as previously
described and an electrically insulating polymer with a
solvent vapor. The treatment can be carried out in
several ways. For example, a solution containing the
selected dye material, the electrically insulating
polymer and, if desired, a material which is an organic
photoconductor can be coated in the form of a layer in
a conventional manner onto a suitable support. Treat-
ment is then achieved in situ by contact of the coating
with the vapors of a solvent until a color change is
noted in the coating. Also treatment can be achieved
by inhibition of solvent removal in an otherwise normal
coating operation of a solvent dope containing the dye
and polymer and when desired, an organic photoconductor
Similarly, coating such a layer from a solvent mixture
which also contains a higher boiling solvent which per-
sists in the coating during drying is among the methods
for the desired treatment.
In general, the photoconductive compositions
of the examples have been prepared by mixing together
separate solutions of the selected dye material and the
electrically insulating polymer and then, if desired,
adding an organic photoconductor. The solution is then
coated on a conductive support, such as a nickel-coated
poly(ethylene terephthalate) film support, and dried in
air or under vacuum at about 60C for about one hour.
The coated composition is then treated with a solvent
3 vapor ~or a few minutes and then redried under vacuum
for about one hour at about 60C.
The organic coating solvents useful for
preparing coating dopes can be selected from a variety
of materials. Useful liquids include substituted
hydrocarbon solvents, wlth preferred materials being
halogenated hydrocarbon solvents. The requisite pro-
perties of the solvent are that it be capable of dis-
solving the selected dye material and be capable of
dissolving or at least highly swelling or solubilizing
4 the polymeric ingredient of the composition. In
11~9426
--8--
addition, it is helpful if the solvent is volatile,
preferably having A bo~ling point of less than about
200 C. Particularly useful solvent6 include
halogenated lower alkanes having from about 1 to
about 3 carbon atoms.
The solvents useful in obtaining the photo-
conductive compositions of the invention include,among others, dichloromethane, toluene, tetrahydro-
furan, ~-dioxane, chloroform and l,l,l-trichloroeth-
ane. Such solvents may be used alone or in combina-
tion, in which case each component of the combina-
tion need not be a solvent for the particular dye
material used. The particular solvent(s) used will,
in some cases, be determined by the particular com-
bination of electrically insulating polymer, dyematerial and the material used as the organic photo-
conductor. For example, in some cases one solventmay cause ~ particular polymer, organic photoconduc-
tor or dye material to precipitate out of the coated
composition while other solvents will result in the
desired photoconductive compo6itions.
After treatment according to one of the
above procedures, a transformation occurs in thecomposition being treated. The desired transforma-
tion is indicated by increased speed and a change inthe absorption spectrum of the solvent treated
coated composition. In other words, the now trans-
formed composition possesse6 increased speed and an
absorption spectrum that is different from that of
the same composition before transformation. In
general, one observes a new absorption spectrum in
the now transformed composition. In one embodiment
of the present invention, an absorption peak appears
in the treated composition in the region of 560 nm,
while such peak is not present in the same composi-
tion which has not been treated. In th~ embodi-
ment, the color of the layers shifts from a blue-
green to a blue, which is consistent with the change
in the absorption spectrum.
~0
1129~26
g
The amount of the selected dye material
incorporated into photoconductive compositions and
elements of the present invention can be varied over
a relatively wide range. When such compositions do
not include an organic photoconduct~ve material, the
selected dye material may be present in an amount of
about 0.1 to about 50.0 percent by weight of the
coating composition on a dry basis. Larger or
smaller amounts of the selected dye material, such
as monomethine pyrylium dye salts, may also be
employed, although best results are generally
obtained when using an amount within the aforemen-
tioned range. When the compositions include anorganic photoconductive material, useful results are
obtained by using the selected dye material in
amounts of about 0.1 to about 30 percent by weight
of the photoconductive coating composition. The
upper limit in the amount of dye material present in
a sensitized layer is determined as a matter of
choice and the total amount of any dye msterial used
will vary widely depending on the material selected,
the electrophotographic response desired, the pro-
posed structure of the photoconductive element and
the mechanical properties desired in the element.
Most electrically insulating film-forming
polymers are useful in the present invention. Such
polymers include polystyrene, polyvinylethers, poly-
olefins, polythiocarbonates, polycarbonates and phe-
nolic resins such as those disclosed in U.S. Patent
3,615,414. Mixtures of such polymers are also use-
ful.
P~rticularly useful polymers have recurringunits as shown in Table II.
B~
1~2~2~
--10--
TABLE II
Polymers
O O
(1) ~C--\ O \--C-O--~ O ~ ' 0 ,--o~
t~
Poly[4,4'-(hexahydro-4,7-methanolndan-5-ylidene)-
diphenylene terephthalate]
O O CH
(2) ~C-.\ 0 \~-O-~ O ~-C-O-~ o ~-t-~ ~-~~
Poly[4,4'-(lsopropylldene)dlphenylene
4,4'-oxydlbenzoate]
Cl\ ~CI O
cl t~; cl
Poly~4,4'-(2-norbornylldene)bls(2,6-dlchloro-
phenylene)carbonate]
.j O
(4) ~0-~ 0 ~ O \~-O-C~
t~ ,l-.
Poly~4,4'-(he~ahydro-4,7-methanolndan-5-ylldene)-
diphenylene carbonate~
O _
15 (5) ~o--~OO ~ O ~--O-C~
1~ ,!
Poly~4,4'-(2-norbornylldene)dlphenylene carbonate]
~1 '
~2~6
( 6 ) ~CH--Cl 12~
I~O,I
P~lystyrene
CH O
(7) ~o--~ 0 \-- C --~ 0 \--o-C~
CH
Poly(4,4'-lsopropylldenedlp~enylene carbonate)
U6eful orgsnic photoconductive material6
sre generally electron acceptor or electron donor~
for the dye materials. Such material6 may be
selected from materials de6ignated as organic photo-
conductors in the patent literature 6uch a6 those
di6clo6ed in U.S. Patent6 3,615,414, 3,873,311 and
3,873,312 and Research Disclosure, item 10938, Vol-
ume 109, May, 1973. Typical materials include aro-
matic amines such as tri-p-tolylamine and (di-~tol-
ylaminophenyl)cyclohexane.
In general, organic photoconductive materi-
al6, when used, are present in the composition in an
amount equal to at lea6t about 1 weight percent of
the coating composition on a dry ba6e. The upper
limit in the amount of photoconductor substance
pre5ent can be widely varied in accordance with
u6ual practice. It is normally required that the
organic photoconductor materisl be present, on a dry
basis, in an amount of from about 1 weight percent
of the coating composition to the limit of its solu-
bility in the polymeric binder. A polymeric organlcphotoconductor may also be employed. A preferred
weight range for the organic photoconductor in the
coating composition ~8 from about 10 weight percent
to about 40 weight percent on a dry basis.
B,
1~2942~
-12-
Suitable supporting materials for the photo-
conductive compositions of this invention may include
any of a wide variety of electrically conducting supports,
for example, paper (at a relative humidity above 20
percent); aluminum-paper laminates; metal foils such as
aluminum foil, zinc foil, etc; metal plates such as
aluminum, copper, zinc, brass and galvanized plates,
vapor-deposited metal layers such as silver, chromium,
nickel, aluminum, cermet materials and the like coated
on paper or conventional photographic film bases such
as cellulose acetate, polystyrene. Such conducting
materials as nickel can be vacuum deposited on transparent
film supports in sufficiently thin layers to allow
electrophotographic elements prepared therewith to be
exposed from either side of such elements. An espe-
cially useful conducting support can be prepared by
coating a support material such as poly(ethylene tere-
phthalate) with a conducting layer containing a semi-
conductor dispersed in a resin. Such conducting layers
20 both with and without insulating barrier layers are
described in U.S. Patent 3,245,833 and U.S. Patent
3,880,657. Likewise, a suitable conducting coating can
be prepared from the sodium salt of a carboxyester
lactone of maleic anhydride and a vinyl acetate polymer.
25 Such kinds of conducting layers and methods for their
optimum preparation and use are disclosed in U.S.
Patent 3,007,901 and 3,262,807.
The photoconductive compositions of this
invention can be coated, if desired, directly on a
30 conducting substrate. In some cases, it may be desir-
able to use one or- more intermediate subbing layers
between the conducting substrate to improve adhesion to
the conducting substrate and/or to act as an electrical
barrier layer between the coated composition and the
35 conducting substrate. Such subbing layers, if used,
typically have a dry thickness in the range of about
0.1 to about 5 microns. Typical subbing layer materials
which may be used are described, for example, in U.S.
Patents 3,143,421; U.s. Patent 3,640,708 and U.S.
40 Patent 3,501,301.
4Z6
-13 -
Optional overcoat layers may be used in the
present invention if desired. For example, to
improve surface hardness and resistance to abrasion,
the surface layer of the element of the invention may
be overcoa~ed with one or more electrically insula-
ting, organic polymer coatings or electrically insu-
lating, inorganic coatings. A number of such coat-
ings are well known in the art and, accordingly,
extended discussion thereof is unnecessary. Typical
useful such overcoats are disclosed, for example, in
Research Disclosure, "Electrophotographic Elements,
Materials, and Processes", Volume 109, page 63,
Paragraph V, May, 1973.
Coating thicknesses of the photoconductive
composition on the support can vary widely. Nor-
mally, a coating in the range of about 0.5 micron to
about 300 microns before drying is useful for the
practice of this invention. The preferred range of
coating thickness is found to be in the range from
about 1.0 micron to about 150 microns before drying,
although useful results can be obtained outside of
this range. The resultant dry thickness of the coat-
ing is preferably between about 2 microns and about
50 microns, although useful results can be obtsined
with a dry coating thickness between about 1 andabout 200 microns.
The elements of the present invention can be
employed in any of the well-known electrophotographic
processes which require photoconductive layers. One
such process is the xerographic process. In a pro-
cess of this type, an electrophotographic element is
held in the dark and given a blanket electrostatic
charge by treatin8 it with a corona discharge. This
uniform charge is retained by the layer because of
the substantial dark insulating property of the
layer, i.e., the low electrical conductivity of the
layer in the dark. The electrostatic charge formed
on the surface of the photoconductive layer is then
selectively dissip$ted from the surface of the layer
by imagewise exposure to light by means of a conven-
tional exposure operation such as, for example, by a
contact-printing
~'
9~26
- 14 -
technique, or by pro~ection of an image, and the like,
to thereby form a latent electrostatic image in the
photoconductive layer.
The latent electrostatic image produced by
exposure is then developed or transferred to another
surface and developed there, i.e., either the charged
or uncharged areas are rendered visible, by treatment
with a medium comprising electrostatically responsive
particles having optical density. The developing
electrostatically responsive particles can be in the
form of dust, i.e., powder, or a pigment in a resinous
carrier, i.e., toner. A preferred method of applying
such toner to a latent electrostatic image for solid
area development is by the use of a magnetic brush.
Methods of forming and u~ing a magnetic brush toner
applicator are described in the following U.S. Patents:
Young, U.S. 2,786,439 issued March 26, 1957; Giaimo,
u.S. 2,786,440 issued March 26, 1957; Young, U.S.
2,786,441 issued March 26, 1957; Greig, U.S. 2,874,063
issued February 17, 1959. Liquid development of the
latent electrostatic image may also be used. In liquid
development, the developing particles are carried to
the image-bearing surface in an electrically insulating
liquid carrier. Methods of development of this type
are widely known and have been described in the patent
literature, for example, Metcalfe et al., U.S. Patent
2,907,674 issued October 6, 1959. In dry developing
processes, the most widely used method of obtaining a
permanent record utilizes a developing partlcle which
has as one of its components a thermoplastic resin.
Heating the powder image then causes the resin to melt
or fuse into or on the element. The powder is, thus
caused to adhere permanently to the surface of the
photoconductive layer.
The following examples are included for a
further understanding of the invention. Each of the
exemplified dye materials exhibits (1) a change in
absorption spectrum when a binderless coating thereof
is treated with a solvent vapor and (2) substantially
4 the same changed absorption spectrum in a solvent vapor
4 2 6
-15-
treated photoconductive composition which includes said
dye material and an electrically insulating polymer.
Example 1
24.2 mg of dye material 5 were dissolved in 4
ml of dichloromethane and 0.1 ml 1,1,1,3,3,3-hexafluoro-
isopropanol (HFIP). This solution was coated on poly-
(ethylene terephthalate) at 50C. The visible spectrum
of the film, as coated, has absorption maxima at 630
nm, and at 600 nm and another band at 415 nm.
Transformation of dye material 5 to the
enhanced photoconductive state was spectrally observed
in the presence of tetrahydrofuran vapor. The prepared
film was fumed by suspending it in a Dewar flask which
was saturated with the vapors. The flask, fitted for
optical access, was placed into a conventional Cary 14
spectrometer and the film's optical spectrum was re-
corded. ~he amount of time required to form the en-
hanced photoconductive state of the dye is dependent on
the concentration of solvent fumes in contact with the
film surface.
The spectrum recorded during the fuming of a
binderless coating of dye material 5, Table I, has an
absorption maximum at 615 nm, a shoulder at 550 nm and
a band at 415 nm. The spectrum of the enhanced photo-
conductive state in a polymer matrix was substantially
the same as the spectrum of the vapor treated binderless
coating.
Example 2 - Preparation and testing of photoconductive
films containing dye material 1, Table I.
3 To 12.8 mg of dye material 1, Table I, was
added 1 ml of dichloromethane, 0.1 ml of HFIP and 5 ml
dichloromethane containing Lexan 145 (0.1 g/ml). Lexan
145 is a polycarbonate polymer supplied by General
Electric Co., having structure 7 in Table II. The
solution was stirred and heated for 5 minutes and then
327 mg of tri-p-tolylamine was added. The final solu-
tion was coated on an unsubbed nickel coated poly-
(ethylene terephthalate) support and air-dried at 55C
for 5 minutes. The film was then dried in a vacuum
oven at 60C for one hour after vapor treatment. Dry
film thickness was 6.o~.
~i~9426
-16-
The untreated film appeared blue-green by
transmitted light. Upon solvent treatment for one
minute with the vapors of methylene chloride, the films
turned blue. The optical absorption spectrum for this
film before and after vapor treatment is shown in Fig.
1. The spectrum was determined in a conventional
manner using for example a Cary 14 spectrophotometer.
The spectrum 1 for the untreated film has a peak at
about 650 nm and a shoulder at 60o nm. The spectrum 2
for the methylene chloride treated film 2 is shifted
with narrow band peaks at 635 nm and 560 nm. The peak
at about 560 nm is absent from the untreated film.
The photosensitivity and the electrical speed
of each coating was determined as follows: the front
surface of the coating was electrostatically charged
negatively under a corona source until the surface
potential as measured by a capacitively coupled probe
attached to an electrometer attained an initial dark
value, VO of -500 volts. The rear surface of the
charged coating was then exposed to monochromatic
visible radiation at a wavelength equivalent to a peak
in the optical absorption maximum of the dye material.
The exposure caused reduction of the surface potential
of the element from -500 volts to -100 volts. The
photosensitivity of the element can be considered
equivalent to the exposure in ergs/cm2 necessary to
discharge the element from -500 to -100 volts, after
correction for light absorption and reflection by the
film support.
3 The photosensitivities (at 640 nm) of control
and fumed films of the above composition are listed in
the following table.
Photosensitivity Photosensitivity
Exposureof Fumed Film of Control
35 Configuration(ergs/cm ) (ergs/cm2)
Negative Charge 8 189
Rear Exposure
Example 3
A photoconductive film containing dye material
4 3, Table I was tested as in Example 2. Upon vapor
426
-17-
treatment the films changed from blue-green to blue and
exhibited the same absorption and speed characteristics
as material 1.
Example 4
15.5 mg of dye material 2 was dissolved in 2
ml CH2C12 and 0.2 ml HFIP. To this was added 5 ml of
poly[4,4'-(2-norbornylidene)diphenylene carbonate]
(polymer material 5, Table II) solution(0.075 g of
polymer/ml CH2C12) and 297.8 mg of tri-p-tolylamine.
This solution was warmed, coated on nickel coated
poly(ethylene terephthalate) at 25C, and allowed to
air dry 2-3 minutes at 50C. The film was then vapor
treated for 5 minutes with toluene and oven dried at
55C for 1-1/2 hours. The control was an untreated
film of dye material 2. It had maximum absorption at
660 nm and a shoulder at 620 nm. The transformed films
(i.e., vapor treated to form the enhanced photoconductive
state) had maximum absorption at 655 nm and a smaller
peak at 580 nm.
The photosensitivity values shown in Table
III of the control and the vapor treated film was
determined as in Example 2 for negative charging, front
and rear exposures.
TABLE III
PhotosensitivitylPhotosensitivity
of the of the
ExposureTransformed Film Control
Confi~ tlon(ergs/cm2) (ergs/cm2)
Negative Charge 30 498
3 Front Exposure
Negative Charge 20 145
Rear Exposure
y
Photosensitivity was calculated for a discharge
from -308V to -58V at A = 650 nm.
Exa_ple 5
16.1 mg of dye material 2 was dissolved in 2
I ml dichloromethane and 0.2 ml HFIP. To this 5 ml of a
Lexan 145 solution (0.1 ~ Lexan/ml CH2C12) and 299.0 mg
tri-p-tolylamine were added. The solution was heated,
coated on Ni/Estar at 25C, and allowed to air dry at
1~94Z6
--18--
50C. The rilm was then vapor treated wlth tetrahy-
drofuran for 2 mlnutes and oven drled at 55C ror 1-1/2
hours.
The photosensltlvlty Or the treated rilm and
5 untreated control ~llm was determlned as ln Example 2
for negative charglng front and rear exposure. Results
are shown ln Table IY.
TABLE IV
Photosensitlvltyl Photosensltlvity
of the of the
ExposureTransrormed Fllm Control
Configuratlon(ergs/cm2) _(er~s/cm2)
Negatlve Charge 22 975
Front Exposure
Negatlve Charge 35 220
Rear Exposure
lThe ph~tosensltlvlty was calculated for -500V to -lOOV
dlgcharge at A ~ 650 nm.
ExamPle 6
Thls example was prepared to show the comblna-
tion Or hlgh speed and good resolutlon possessed by
photoconductlve rllms of the present lnventlon compared
to the speed and resolutlon of typlcal homogenous
photoconductlve rllms such as those descrlbed ln U.S.
Patent 3,542,547 and conventlonal aggregate photoconduc-
tive ~llms such as those descrlbed ln ~.S. Patent
3,615,414 and U.S. Patent 3,873,311.
Three photoconductlve ~llms were prepared.
3 Fllm A was a homogenous rllm Or the type descrlbed ln
U.S. Patent 3,542,547. Fllm B was an aggregate rllm Or
the type descrlbed in V.S. Patent 3,873,311. Fllms C
and D lnclude dye materlal 1, Table I. Each rllm
lncluded the rollowln~ llsted materlals.
Fllm A
(a) CH2C12 17.6 g
(b) 2,4-bls(4-ethoxyphenyl)-6- 0.04 g
(4-pentyloxystyryl)pyrylium
tetra~luoroborate
(c) 2,6-blst4-amyloxyphenyl)-4~2-(4 0.01 g
amyloxyphenyl)-~-phenyl-4H-pyran-
4-yllden~lmethy~ pYrylium-per
chlorate'
~2 -
D~
1~9426
--19--
Fllm A Cont'd.
(d) Vltel PE 101~ (Goodyear) 1.8 g
(e) 4,4'-bis(dlethylamlno)-2,2'- o.6 g
dimethyltrlphenyl methane
~llm B
(a) CH2C12 10.2 g
(b) 1,1,2-tr~chloroethane ~.8 g
(c) Lexan 145 polycarbonate 1.8 g
(d) 4-(p-dimethylamlnophenyl)- 0.09 g
lG 2,6-dlphenylthlopyryllum
tetra~luoroborate
(e) 4,4'-bls(dlethylamlno)-2,2'- 1.2 g
dlmethyltrlphenylmethane
Fllm C
; 15 (a) CH2C12 3~:32 g
(b) Hexafluorolsopropanol o.84 g
(c) 4-~2,6-Dlphenyl-4H-thlopyran-4- 0.126g
ylldene)methyl]-2,6-dlphenyl-
thlopyryllum perchlorate
(d) Lexan 145 polycarbonate 3.0 g
(e) Trl-p-tolylamlne l.BB g
(f) Poly[(oxycarbonylethylene-1,4- 0.15 g
phenylene-2-cyanovlnylene-1,4-
phenylene-l-cyanovlnylene-1,4-
phenylene(phenylamlno)-1,4-
phenylene ethylenecarbonyl-
oxydecamethylene]
(g) Toluene 5.64 g
Fllm D
(a) CH2C12 34.32 g
(b) Hexa~luoro~sopropanol 0.84 g
(c) 4-t2,6-Dlphenyl-4H-thlopyran-4- 0.126g
ylldene)methyl]-2,6-dlphenyl-
thlopyrylium perchlorate
(d) Lexan 145 polycarbonate 3.0 g
(e) 4,4'-dlethylamlno-2,2'- l.B8 g
dlmethyltrlphenylmethane
(g) Toluene 5.64 g
~ Each coating composltlon was made 24 hours prlor to
coatlng by dlssolvlng the components ln the order
llsted, allowlng surrlclent time between addltlons ror
complete solvatlon. Each composltlon was coated on a
transparent nlckel or cuprous lodlde conductive support.
1~2~4Z~
-20-
Coating A was made at a coverage of 7.5 gms/m2. Coating
B was made at a coverage of 11.3 gms/m2. Coatings C
and D were made at a coverage of 7.5 gms/m2. The
coatings were then dried.
Photosensitivity and resolution data are
presented in Table V. Photosensitivity was determined
as in Example 2 for negative charging at a wavelength
where the optical density of the film equals l.O.
Discharge was from -600V to -lOOV. The data in this
table shows that photoconductive elements comprising
the composition of the present invention have a better
speed resolution product than the photoconductive
elements A and B which are representative of the prior
art.
-21- 11;294Z6
C
C o
o C~ 0 ~ U~ o
0 ~ ~ t~
1~ 0 Cl 0 5
I ~ ~e ~ ~ ,~
~ _
bO
C~
J~ ~
OCC
O
~a ~ ~ I a: o , co ~ ~ 'I
¦ E ~'¦ I 11' " ~ o ~ C
~ o
b~
I I I I
O~ O o o O
S ~.
~ e , ~ ~ 5 o C
~ a~ ~ ~ ~ 4 E
S C~
~ C~ ~
a) ~ o o o o ~ ~ c
,1 ~ a~ o o ~ s~ o
~ ~n ` ~ ~ 0
~ o o
3,
U~
v
o '' e~ a
o~ .
B ~ I
1~2942~
-22-
Examples 7-12
Six different polymers having the recurring
units 1, 2, 3, 4~ 5 and 6 from Table II were used to
ma~e six photoconductive films, each containing a
different polymer. Each film contained the dye material
1, Table I. The films were prepared substantially in
accordance with Example 2. Each film was found to have
greater photosensitivity after vapor treatment than
before such treatment. Each vapor treated film also
10 had a spectral peak at about 560 nm which did not
appear in the film before vapor treatment. These Examples
7-12 also show that the change in absorption spectrum
and enhanced speed is independent of the polymer material .
Hence, the transformation probably results from dye-dye
15 interaction instead of dye-polymer co-crystallization.
Example 13
To 12.8 mg of dye material 4 was added 1 ml
of dlchloromethane, 0.1 ml of hexafluoroisopropanol and
~ 5 ml dichloromethane containlng Lexan 145 (0.1 g/ml).
O 20 The solution was stirred and heated for 5 minutes and
2 then 327 mg of tri-p-tolylamine was added. The final
solution was coated on an unsubbed nickel coated poly-
(ethylene terephthalate) support and air-dried at 55C
for 5 minutes. Transformation occurred upon vapor
25 treatment with warmed dioxane. The film was dried in
a vacuum oven at 60C for one hour after vapor treatment.
The absorption spectrum of this film after vapor treat~
ment had a shoulder at 578 nm and a peak at 605 nm.
The spectrum of the untreated film was different from
30 that of the treated film.
Q Photosensitivity measurements were made as in
Example 2 for rear exposure discharge from -500V to -lOOV.
The photosensitivity was 13 erg/cm2.
'_ xample 14
17.0 mg of dye material 5 was dissolved in 2
I ml CH2C12 and 0.2 ml HFIP. To this was added 5 ml of
Y Lexan solution (0.1 g of polymer/ml of CH2C12) and
_ 302.1 mg tri-_-tolylamine. This solution was heated to
drive off excess HFIP, coated on nickel coated poly-
4 (ethylene terephthalate) at 25C and allowed to air dry
~1~94Z6
-23-
2-3 minutes at 5OC. The film was then fumed for one
minute with tetrahydrofuran and oven dryed 1/2 hour at
58C. Photosensitivity measurements were made according
to Example 2. The results are presented in Table VI.
TABLE VI
PhotosensitivityPhotosensitivity
Exposure of the fumed filmof the control
Configuration (ergs/cm2) (ergs/cm2)
Front 19.2 3O9
Rear 13.6 83
Photosensitivity in this example is the energy required
to discharge the film from -500V to -lOOV at 610 nm.
The invention has been described in detail
with particular reference to certain preferred embodi-
ments thereof, but it will be understood that variationsand modifications can be effected within the spirit and
scope of the invention.
