CA1054422A - Charge transfer complex and photoconductive insulating films incorporating same - Google Patents
Charge transfer complex and photoconductive insulating films incorporating sameInfo
- Publication number
- CA1054422A CA1054422A CA250958A CA250958A CA1054422A CA 1054422 A CA1054422 A CA 1054422A CA 250958 A CA250958 A CA 250958A CA 250958 A CA250958 A CA 250958A CA 1054422 A CA1054422 A CA 1054422A
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- CA
- Canada
- Prior art keywords
- electron donor
- invention according
- photoconductive layer
- donor material
- monomeric
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
- G03G5/02—Charge-receiving layers
- G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
- G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
- G03G5/07—Polymeric photoconductive materials
- G03G5/075—Polymeric photoconductive materials obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- G03G5/076—Polymeric photoconductive materials obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds having a photoconductive moiety in the polymer backbone
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/16—Dicarboxylic acids and dihydroxy compounds
- C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
- C08G63/181—Acids containing aromatic rings
- C08G63/185—Acids containing aromatic rings containing two or more aromatic rings
- C08G63/187—Acids containing aromatic rings containing two or more aromatic rings containing condensed aromatic rings
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/68—Polyesters containing atoms other than carbon, hydrogen and oxygen
- C08G63/682—Polyesters containing atoms other than carbon, hydrogen and oxygen containing halogens
- C08G63/6824—Polyesters containing atoms other than carbon, hydrogen and oxygen containing halogens derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/6826—Dicarboxylic acids and dihydroxy compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/68—Polyesters containing atoms other than carbon, hydrogen and oxygen
- C08G63/685—Polyesters containing atoms other than carbon, hydrogen and oxygen containing nitrogen
- C08G63/6854—Polyesters containing atoms other than carbon, hydrogen and oxygen containing nitrogen derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/6856—Dicarboxylic acids and dihydroxy compounds
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Photoreceptors In Electrophotography (AREA)
Abstract
PHOTOCONDUCTIVE INSULATING FILMS
ABSTRACT OF THE DISCLOSURE
Photoconductive insulating films comprising a solid solution of a monomeric electron donor dissolved in a solid linear polyester matrix wherein said linear polyester has recurring structural units of the formula wherein X is oxygen or dicyanomethylene Y and Z are independently selected from the group consisting of NO2, halogen R is a hydrocarbolene radical having from 1 to 10 carbon atoms;
R' is oxygen or sulfur;
m is 0 or 1;
a and a' can range from 0-3; and b is at least 5.
These photoconductive insulating films are especially suitable for use in electrophotographic imaging members and methods.
ABSTRACT OF THE DISCLOSURE
Photoconductive insulating films comprising a solid solution of a monomeric electron donor dissolved in a solid linear polyester matrix wherein said linear polyester has recurring structural units of the formula wherein X is oxygen or dicyanomethylene Y and Z are independently selected from the group consisting of NO2, halogen R is a hydrocarbolene radical having from 1 to 10 carbon atoms;
R' is oxygen or sulfur;
m is 0 or 1;
a and a' can range from 0-3; and b is at least 5.
These photoconductive insulating films are especially suitable for use in electrophotographic imaging members and methods.
Description
1054~2Z
BACKGROUND OF TEIE INVENTION ~.
Field of the Invention - The invention relates to photoconductive insulating films and articles incorporating said films. More specifically, this invention relates to photoconductive insulating films comprising a solid solution wherein the individual components of said solid solution form a charge transfer complex which is highly sensitive to light within the visible band of the electromagnetic spectrum.
Description of the Prior Art - The formation and 0 development of images on the imaging surfaces of photoconductive materials by electrostatic means is well~known. The best known of the commercial processes, more commonly known as xerography, involves forming a latent electrostatic image on the imaging surface of an imaging member by first uniformly, electrostatically charging the surface of the Lmaging layer o~ said member in the dark and then exposing the electrostatically charged surface to a r~ .
light and shadow image. The light-struck areas of the imaging layer thus rendered relatively conductive and the electrostatic charge selectively dissipated in these irradiated areas. After the photoconductor is exposed, the latent electrostatic image on this image bearing surface is rendered visible by development ; with a finely divided colored marking material known in the art as "toner". This toner will be principally attracted to those - areas on the image bearing surface which have a polarity ~f charge ~;
opposite to the charge on the toner particles and thus form a visible powder image.
The developed image can then be read or permanently affixed tn the photoconductor where the imaging layer is not to be reused. This latter practice is usually followed with respect ~o the binder-type photoconductive films ~e.g. zinc oxide/insulating resin binder) where the photoconductive imaging layer is also an `' 3 ;, ~ . .~' , .
.~
i `- 10544ZZ
- ~ntegral part of the finished copy, U. S. Patents 3,121,006 and 3,121,007.
In so called "plain paper" copying systems, the latent - image can be developed on the imaging surface of a reusable photo-conductor or transferred to another surface, such as a sheet of ` paper, and thereafter developed~ When the latent image is developed ~ on the imaging surface of a reusable photoconductor, it is - subsequently transferred to another substrate and then permanently affixed thereto. Anyone of a variety of well-known techniques can be used to permanently affix the toner image to the copy sheet, ` including overcoating with transparent films, and solvent or ;~
thermal fusion of the toner particles to the supportive substrate.
In the above "plain paper" copying systems, the materials used in the photoconduc-tive insulating layer should be preferably ~ ~ ;
capable of rapid switching from insulating to conductive to insulating state in order to permit cyclic use of the imaging surface. ~ I
~he failure of the material to return to its relatively insulating state prior to the succeeding ch æ ging/imaging sequence will result in a decrease in the maximum charge acceptance of the photoconductor.
~ 20 This phenomenon, commonly referred to as "fatigue" in the art~- has in the past been aqoided by the selection-of photoconductive ~ . materials possessing rapid switching capacity_ Typical of the i -., i .
- materials suitable for use in such a rapidly cycling imaging ' system include anthracene, sulfur, selenium and mixtures thereof ~- 25 tU. S. Patent 2,297,691): selenium being preferred because of its - -ruperior photosensitivity. The materials from which such photo-~onductive insulating layers are formed have a bulk resistivity in excess of about 101 ohm-cm (this ievel being the empirical dividing line between insulators and semi-conductors.) Genera most photoconductive insulating materials in present commercial use have bulk resistivities in excess of lOI2 ana preferably, , .,`"~ ' ~
.- . , ~ , .
.. .
'.. ' ~ . - , ' -: ,~
.; ' ' ' . :'. , ~ . - ' ::
~544zz t in excess of lol3 ohm-cm. The bulk resistivity of such photo-conductive insulating layers determines its rate of dark decayO
Under ideal conditions, dark decay of the sensitizing charge on the surface o~ a photoconductive insulating layer should be ~irtually nil, however, in the more modern rapid electrophotographic imaging systems some dark decay can be tolerated. This is not to suggest that materials commonly classified as semi-conductors can be used in electrophotographic imaging systems and apparatus.
In more recent times, the shi~t in emphasis in photo-o conductive materials has been away from inorganic systems toward organic polymeric photoconductors, such as poly~N-vinylcarbazole), U. S. Patent 3,037,861. Until relatively recently this polymeric material has not received serious consideration as an alternatîve to selenium and its alloys due to its relative lack of speed and ;~
photosensitivity. The discovery that high loadings o~ 2,4,7-trinitro-9-fluorenone in poly(vinylcarbazoles) dramatically improves the photoresponsiveness of these polymers has lead to `~-~
a resurgence in interest in organic photoconductive materials, U.S. Patent 3,484,237. Ihe photoconductive compositions 0 described in '?37 are capable of transport of holes and electrons photogenerated within its bulk. Such charge carrier transport is believed to be a function of the Z extent of overlap of the~r orbitals of the heterocyclic molecules and pendant polymer substituents and the relative distances therebetween. Thus, modification of the steric relationships of these molecules and pendant groups and/or increasing the relative distance between the molecules and ~ pendant groups can be expected to change and in most --~ instances, impair charge carrier transport. It is kno~n, `~0 ~or example, that uniaxial orientation o films of poly-(N-vinylcarbazole~ have hole transport properties which .'5 _ . --5 .` ' '~' .
are inferior to nonoriented films prepared from the same materialsO During similar orientation of nonphotoconductive polymer films wherein aromatic groups are pendant from the polymer bac~bone, the conformation of the pendant groups is different from that of nonoriented polymeric material.
It is h~pothesized that these differences in the steric relationship of overlapping carbazyl substituents is respon-sible for the observed deterioration in hole transport properties. Presumably, modification of the steric rela-tionship of the nitro-fluorenone molecules will result in - an analogous impairment in electron acceptor properties.
Thus, nitro-fluorenone containing polymers would not be expected to have electron transport properties equivalent to the nonpolymer c dispersions of this electronically ~-15 active material unless the conformation and relative distance between adjacent nitro-fluorenone groups were ` also equivalent.
' In addition to the compositions referred to hereinabove, charge transfer polymer blends have also been prepared from mlxtures of linear polyesters having incorporated directly in their respective backbones an electron withdrawlng or an electron releasing moiety, ~.S~ Patent 3,536,781. These blends are not suitable : for use as photoconductive insulators due to their
BACKGROUND OF TEIE INVENTION ~.
Field of the Invention - The invention relates to photoconductive insulating films and articles incorporating said films. More specifically, this invention relates to photoconductive insulating films comprising a solid solution wherein the individual components of said solid solution form a charge transfer complex which is highly sensitive to light within the visible band of the electromagnetic spectrum.
Description of the Prior Art - The formation and 0 development of images on the imaging surfaces of photoconductive materials by electrostatic means is well~known. The best known of the commercial processes, more commonly known as xerography, involves forming a latent electrostatic image on the imaging surface of an imaging member by first uniformly, electrostatically charging the surface of the Lmaging layer o~ said member in the dark and then exposing the electrostatically charged surface to a r~ .
light and shadow image. The light-struck areas of the imaging layer thus rendered relatively conductive and the electrostatic charge selectively dissipated in these irradiated areas. After the photoconductor is exposed, the latent electrostatic image on this image bearing surface is rendered visible by development ; with a finely divided colored marking material known in the art as "toner". This toner will be principally attracted to those - areas on the image bearing surface which have a polarity ~f charge ~;
opposite to the charge on the toner particles and thus form a visible powder image.
The developed image can then be read or permanently affixed tn the photoconductor where the imaging layer is not to be reused. This latter practice is usually followed with respect ~o the binder-type photoconductive films ~e.g. zinc oxide/insulating resin binder) where the photoconductive imaging layer is also an `' 3 ;, ~ . .~' , .
.~
i `- 10544ZZ
- ~ntegral part of the finished copy, U. S. Patents 3,121,006 and 3,121,007.
In so called "plain paper" copying systems, the latent - image can be developed on the imaging surface of a reusable photo-conductor or transferred to another surface, such as a sheet of ` paper, and thereafter developed~ When the latent image is developed ~ on the imaging surface of a reusable photoconductor, it is - subsequently transferred to another substrate and then permanently affixed thereto. Anyone of a variety of well-known techniques can be used to permanently affix the toner image to the copy sheet, ` including overcoating with transparent films, and solvent or ;~
thermal fusion of the toner particles to the supportive substrate.
In the above "plain paper" copying systems, the materials used in the photoconduc-tive insulating layer should be preferably ~ ~ ;
capable of rapid switching from insulating to conductive to insulating state in order to permit cyclic use of the imaging surface. ~ I
~he failure of the material to return to its relatively insulating state prior to the succeeding ch æ ging/imaging sequence will result in a decrease in the maximum charge acceptance of the photoconductor.
~ 20 This phenomenon, commonly referred to as "fatigue" in the art~- has in the past been aqoided by the selection-of photoconductive ~ . materials possessing rapid switching capacity_ Typical of the i -., i .
- materials suitable for use in such a rapidly cycling imaging ' system include anthracene, sulfur, selenium and mixtures thereof ~- 25 tU. S. Patent 2,297,691): selenium being preferred because of its - -ruperior photosensitivity. The materials from which such photo-~onductive insulating layers are formed have a bulk resistivity in excess of about 101 ohm-cm (this ievel being the empirical dividing line between insulators and semi-conductors.) Genera most photoconductive insulating materials in present commercial use have bulk resistivities in excess of lOI2 ana preferably, , .,`"~ ' ~
.- . , ~ , .
.. .
'.. ' ~ . - , ' -: ,~
.; ' ' ' . :'. , ~ . - ' ::
~544zz t in excess of lol3 ohm-cm. The bulk resistivity of such photo-conductive insulating layers determines its rate of dark decayO
Under ideal conditions, dark decay of the sensitizing charge on the surface o~ a photoconductive insulating layer should be ~irtually nil, however, in the more modern rapid electrophotographic imaging systems some dark decay can be tolerated. This is not to suggest that materials commonly classified as semi-conductors can be used in electrophotographic imaging systems and apparatus.
In more recent times, the shi~t in emphasis in photo-o conductive materials has been away from inorganic systems toward organic polymeric photoconductors, such as poly~N-vinylcarbazole), U. S. Patent 3,037,861. Until relatively recently this polymeric material has not received serious consideration as an alternatîve to selenium and its alloys due to its relative lack of speed and ;~
photosensitivity. The discovery that high loadings o~ 2,4,7-trinitro-9-fluorenone in poly(vinylcarbazoles) dramatically improves the photoresponsiveness of these polymers has lead to `~-~
a resurgence in interest in organic photoconductive materials, U.S. Patent 3,484,237. Ihe photoconductive compositions 0 described in '?37 are capable of transport of holes and electrons photogenerated within its bulk. Such charge carrier transport is believed to be a function of the Z extent of overlap of the~r orbitals of the heterocyclic molecules and pendant polymer substituents and the relative distances therebetween. Thus, modification of the steric relationships of these molecules and pendant groups and/or increasing the relative distance between the molecules and ~ pendant groups can be expected to change and in most --~ instances, impair charge carrier transport. It is kno~n, `~0 ~or example, that uniaxial orientation o films of poly-(N-vinylcarbazole~ have hole transport properties which .'5 _ . --5 .` ' '~' .
are inferior to nonoriented films prepared from the same materialsO During similar orientation of nonphotoconductive polymer films wherein aromatic groups are pendant from the polymer bac~bone, the conformation of the pendant groups is different from that of nonoriented polymeric material.
It is h~pothesized that these differences in the steric relationship of overlapping carbazyl substituents is respon-sible for the observed deterioration in hole transport properties. Presumably, modification of the steric rela-tionship of the nitro-fluorenone molecules will result in - an analogous impairment in electron acceptor properties.
Thus, nitro-fluorenone containing polymers would not be expected to have electron transport properties equivalent to the nonpolymer c dispersions of this electronically ~-15 active material unless the conformation and relative distance between adjacent nitro-fluorenone groups were ` also equivalent.
' In addition to the compositions referred to hereinabove, charge transfer polymer blends have also been prepared from mlxtures of linear polyesters having incorporated directly in their respective backbones an electron withdrawlng or an electron releasing moiety, ~.S~ Patent 3,536,781. These blends are not suitable : for use as photoconductive insulators due to their
2~ unacceptably high dark -conductivity. The '781 patent does not indicate whether or not c~arge carrier transport is adversely affected because of the steric constraints placed upon the donor and acceptor groups of the polymers .~ o~ the blend.
., .
;. . ...
"
, . . . . . . .
... , . ~ . , ~ ~
- 1~54~22 Accordingly, it is the object of an aspect of the -~ present invention to remedy the above as well as related deficiencies in the prior art.
It is an object of an aspect of this invention to provide a solid solution comprising a photoconductive polymer capable of an electron acceptor function sensitized with a - monomer capable of an electron donor function.
; It is an object of an aspect of the invention to ~- provide a solid solution suitable for use as a photoconductive insulating layer.
- - It is an object of an aspect of this invention to provide an electrophotographic imaging member wherein the photoconductive insulating layer comprises a solid solution of an electron acceptor polymer which is sensitized with a molecule capable of an electron donor function. `
SU~ARY OF THE INVENTION
In accordance with one aspect of this invention ~ , there is provided an article comprising an electrostatographic imaging member having a photoconductive layer of a bulk resistivity in excess of 101 ohm-centimeters which comprises ; a charge transfer complex formed between a monomeric electron donor material and a solid linear matrix polymer having ^ recurring structural units of the formula O--~R-Rm-R~-- O - C ~ C
"' (Y) ~ Z) a a wherein X is oxygen or dicyanornethylene Y and Z are inde~endently selected from ., -:,;
: . ~ . . . ..
11~5442Z ~ ~
~ ~~the group consisting of NO2, halogen ; R is a hydrocarbolene radical having from .,,' - .
; 1 to 10 carbon aloms;
R' is oxygen or sulfur;
m is 0 or 1;
- a and a' can ral~ge from 0-3; and ~ca, a c~nd b bei~q i~lte~ers;
b is at least 5; ~ J
the relative molar concentration of monomeric electron donor ~ per recurring structural unit of linear matrix polymer ranging - 10 from about 30:7~ to about 70:30.
In accordance with another aspect of this invention there is provided an electrostatographic imaging process com-prising the steps of sensi~izing followed by imagewise exposure to activating electromagnetic radiation of an electrostato-graphic plate comprising a conductive substrate and a layer of - photoconductive material of the type set out in the preceding paragraph.
In accordance with another aspect of this invention there is provided a charge transfer complex of the type set out hereinab~ve. ~ , DESCP~IPTION OF THE INUENTION INCLUDING
, ~ PREE'ERRED E~D3ODIMENTS
The solid solutions of this invention can be prepared by simply combining the monomeric electron donor and the solia linear polyester in a common solvent`and thereafter casting or coating the resulting solution on a supportive (preferabl~ conductive) substrate. me amount of such solution transferred to the substrate can vary with the desired thic}cness of the insulating film. In conventional ` 30 electrophotographic imaging members, film thickness can range 7: from as little as 0.5 up to about 200 microns depending upon ~
the ultimate end use of the imaging member. Of course, such --thicker films can be formed as a result of multiple applications , of the coating solution.
. ~. ;
. ~
5~4Z2 The electron donor materials ~hich are suitable for use in the solid solutions of this invention can be simple organic molecules, simple inorganic molecules or organo-metallic molecules. These materials must be capable of charge trans~er interaction with the electron ~ 8a ~ .`
~5~4~2 acceptor groups incorporated within the backbone of the linear polyester matrix polymers, soluble in such matrix polymers and incapable of substant:ial absorption of incident radiation; to the extent that such absorption would compete with absorption of imaging energies by the charge transfer complex formed between these donor molecules and the poly-ester matrix polymers. Representative of monomeric donor materials which can be used in the solid solutions of this invention include carbazole, lower alkyl substituted carbazoles, anthracene, lower alkyl substituted anthracenes, oxadiazoles and arylalkanes (of the type described in U.S.
Patent 3,542,544).
The polyester matrix polymers, (of the structural formula set forth hereinabove), which are suitable for use in the solid solutions of this invention, can be prepared by the techniques described in the patent literature; namely, U.S. Patent 3,536,781 - (Examples XI, XVI, XVII, XVIII and XIX), These polymers must be capable of dissolving the monomeric electron donor materials in sufficient quantities to enable formation of a charge transfer complex having an optical density of at least 0.3. In addition, the polymers of the solid solution should not effectively compete for ~-absorption of imaging energies with the charge transfer com-plex formed upon interaction of these polymers with the monomeric donor materials. These linear polyesters, which provide the polymeric matrix of the photoconductive insulating layer, should have a sufficient molecular weight to form self-supporting polymeric films. Generally, polyesters, having a degree of polymerization in 1~544ZZ
excess of about 5, will prove suitable for use as the polymer matrix of the photoconductive insulating layers of this invention.
The solid solutions of this invention can also contain certain optional ingredients to further extend their range of spectral response and~or improve their mechanical - properties, The inclusion of such other optional ingredients is, of course, qualified in that such other optional ingredients cannot cause destabilization of the solution to the extent that crystallization occurs or otherwise impair the rate and/or efficiency of transport of charge carriers through a layer of such materials.
The solid solutions of this invention can be employed as a photoconductive insulating layer either alone or in com-~, 15 bination with other layers in the fabrication of an electro-; photographic imaging member. Such other layers may be photo-responsive or nonphotoresponsive and/or be capable or incapable ;` of rapid and efficient transport of charge carriers, Where other layers are ~sed in conjunction with layers of the solid -20 solution of this invention,the photoresponsiveness of these ~ other layers should not preclude effective photoresponse of ,` this solid solution layer.
The Examples which follow further define, describe and illustrate the preparation and use of the solid solutions -~25 of this invention. Apparatus and techniques used in both the preparation and evaluation of the photoconductive insulating layers prepared from such solid solutions are standard or as hereinbefore described. Parts and percentages appearing in such Examples are by weight unless otherwise stipulated.
;i. .
'~ -10-: .-. .
.. : . . , ~ . :.: - , . . ..
;:
!' . _ ;'`" ''~
" 1~5442Z
. .
- EXAMPLE I
A solution containing 11.82 grams of 1,6-hexane diol and 39.21 grams of 4,5-dinitrofluorenone-2,7-dicar-boxylic acid chloride in 300 mil:Liliters of 1,2-dichloro-ethane is heated to reflux under an argon atmosphere in a
., .
;. . ...
"
, . . . . . . .
... , . ~ . , ~ ~
- 1~54~22 Accordingly, it is the object of an aspect of the -~ present invention to remedy the above as well as related deficiencies in the prior art.
It is an object of an aspect of this invention to provide a solid solution comprising a photoconductive polymer capable of an electron acceptor function sensitized with a - monomer capable of an electron donor function.
; It is an object of an aspect of the invention to ~- provide a solid solution suitable for use as a photoconductive insulating layer.
- - It is an object of an aspect of this invention to provide an electrophotographic imaging member wherein the photoconductive insulating layer comprises a solid solution of an electron acceptor polymer which is sensitized with a molecule capable of an electron donor function. `
SU~ARY OF THE INVENTION
In accordance with one aspect of this invention ~ , there is provided an article comprising an electrostatographic imaging member having a photoconductive layer of a bulk resistivity in excess of 101 ohm-centimeters which comprises ; a charge transfer complex formed between a monomeric electron donor material and a solid linear matrix polymer having ^ recurring structural units of the formula O--~R-Rm-R~-- O - C ~ C
"' (Y) ~ Z) a a wherein X is oxygen or dicyanornethylene Y and Z are inde~endently selected from ., -:,;
: . ~ . . . ..
11~5442Z ~ ~
~ ~~the group consisting of NO2, halogen ; R is a hydrocarbolene radical having from .,,' - .
; 1 to 10 carbon aloms;
R' is oxygen or sulfur;
m is 0 or 1;
- a and a' can ral~ge from 0-3; and ~ca, a c~nd b bei~q i~lte~ers;
b is at least 5; ~ J
the relative molar concentration of monomeric electron donor ~ per recurring structural unit of linear matrix polymer ranging - 10 from about 30:7~ to about 70:30.
In accordance with another aspect of this invention there is provided an electrostatographic imaging process com-prising the steps of sensi~izing followed by imagewise exposure to activating electromagnetic radiation of an electrostato-graphic plate comprising a conductive substrate and a layer of - photoconductive material of the type set out in the preceding paragraph.
In accordance with another aspect of this invention there is provided a charge transfer complex of the type set out hereinab~ve. ~ , DESCP~IPTION OF THE INUENTION INCLUDING
, ~ PREE'ERRED E~D3ODIMENTS
The solid solutions of this invention can be prepared by simply combining the monomeric electron donor and the solia linear polyester in a common solvent`and thereafter casting or coating the resulting solution on a supportive (preferabl~ conductive) substrate. me amount of such solution transferred to the substrate can vary with the desired thic}cness of the insulating film. In conventional ` 30 electrophotographic imaging members, film thickness can range 7: from as little as 0.5 up to about 200 microns depending upon ~
the ultimate end use of the imaging member. Of course, such --thicker films can be formed as a result of multiple applications , of the coating solution.
. ~. ;
. ~
5~4Z2 The electron donor materials ~hich are suitable for use in the solid solutions of this invention can be simple organic molecules, simple inorganic molecules or organo-metallic molecules. These materials must be capable of charge trans~er interaction with the electron ~ 8a ~ .`
~5~4~2 acceptor groups incorporated within the backbone of the linear polyester matrix polymers, soluble in such matrix polymers and incapable of substant:ial absorption of incident radiation; to the extent that such absorption would compete with absorption of imaging energies by the charge transfer complex formed between these donor molecules and the poly-ester matrix polymers. Representative of monomeric donor materials which can be used in the solid solutions of this invention include carbazole, lower alkyl substituted carbazoles, anthracene, lower alkyl substituted anthracenes, oxadiazoles and arylalkanes (of the type described in U.S.
Patent 3,542,544).
The polyester matrix polymers, (of the structural formula set forth hereinabove), which are suitable for use in the solid solutions of this invention, can be prepared by the techniques described in the patent literature; namely, U.S. Patent 3,536,781 - (Examples XI, XVI, XVII, XVIII and XIX), These polymers must be capable of dissolving the monomeric electron donor materials in sufficient quantities to enable formation of a charge transfer complex having an optical density of at least 0.3. In addition, the polymers of the solid solution should not effectively compete for ~-absorption of imaging energies with the charge transfer com-plex formed upon interaction of these polymers with the monomeric donor materials. These linear polyesters, which provide the polymeric matrix of the photoconductive insulating layer, should have a sufficient molecular weight to form self-supporting polymeric films. Generally, polyesters, having a degree of polymerization in 1~544ZZ
excess of about 5, will prove suitable for use as the polymer matrix of the photoconductive insulating layers of this invention.
The solid solutions of this invention can also contain certain optional ingredients to further extend their range of spectral response and~or improve their mechanical - properties, The inclusion of such other optional ingredients is, of course, qualified in that such other optional ingredients cannot cause destabilization of the solution to the extent that crystallization occurs or otherwise impair the rate and/or efficiency of transport of charge carriers through a layer of such materials.
The solid solutions of this invention can be employed as a photoconductive insulating layer either alone or in com-~, 15 bination with other layers in the fabrication of an electro-; photographic imaging member. Such other layers may be photo-responsive or nonphotoresponsive and/or be capable or incapable ;` of rapid and efficient transport of charge carriers, Where other layers are ~sed in conjunction with layers of the solid -20 solution of this invention,the photoresponsiveness of these ~ other layers should not preclude effective photoresponse of ,` this solid solution layer.
The Examples which follow further define, describe and illustrate the preparation and use of the solid solutions -~25 of this invention. Apparatus and techniques used in both the preparation and evaluation of the photoconductive insulating layers prepared from such solid solutions are standard or as hereinbefore described. Parts and percentages appearing in such Examples are by weight unless otherwise stipulated.
;i. .
'~ -10-: .-. .
.. : . . , ~ . :.: - , . . ..
;:
!' . _ ;'`" ''~
" 1~5442Z
. .
- EXAMPLE I
A solution containing 11.82 grams of 1,6-hexane diol and 39.21 grams of 4,5-dinitrofluorenone-2,7-dicar-boxylic acid chloride in 300 mil:Liliters of 1,2-dichloro-ethane is heated to reflux under an argon atmosphere in a
3 necked, round bottom flask equipped with a thermometer, reflux condenser, magnetic stirrer and an addition funnel.
About 30 milliliters of pyridine is then added through the . addition funnel as rapidly as possible and the resulting ~ ,, ~;10 solution refluxed for four hours. At the end of this four r,'` hour period the solution is allowed to cool and the - polymeric products contained therein precipitated by - emptying the contents of the round bottom flask into a beaker containing 1:000 milliliters of methanol, The 15 polymeric precipitate which forms is thereafter separated from the methanol by filtration. The polymeric solids which are recovered are washed several times with water and ~hen dried at 50C in a vacuum oven.
i; About 5 grams of a mixture containing equal molar V20 amounts of the above polymer and N-ethylcarbazole is dissolved in 25 milliliters of hexafluoroisopropanol and the resulting solution drawbar coated on a ball-grained aluminum plate.
Sufficient polymer solids are deposited on the aluminum plate to form a dry film having a thickness of approximately '5 20 microns. After allowing sufficient opportunity for the ; removal of solvent residues, the free surface of this polymeric film is charged to a positive potential of about 1200 volts and its rate of photodischarge determined by , -~
blanket exposure to monochromatic light at a wavelength of 5000 Angstrom Units, The rate of photodischarge of this : ~ .
.,,, '~
."; :~.
.
; ~:
.
:. ~ . - . -. .
1~5~4;Z2 plate is about 75 volts per second at fields of 60 volts per micron.
This plate is rechargecl to a positive potential of about 600 volts and thereafter exposed throuyh a resolution ; 5 target to white light. The latent image,which is formed on the surface of this photoconductive laye~ is developed with negatively charged toner particles. The resolution of the developed image is of acceptable quality.
EXAMPLE II
. . .
The procedures of Example I are repeated except for the substitution of a polyester derived from 4,5-dinitro-9-dicyanomethylene fluorene-2,7-dicarboxylic acid chloride.
; - The rate of photodischarge of a plate prepared from equal molar amounts of th:s polymer and ~-ethylcarbazole at fields L5 of 50 volts per micron is about 20 volts per second (photo-.` discharge with monochromatic light at a wavelength of 6000 Angstrom Units).
EX~MPLE III
he procedures of Example I are repeated except '0 for the substitution of one of the following monomeric electron donor materials for N-ethylcarbazole.
Examples III-VIII Electron Donor Material III bist4-diethyl-amino-2-methylphenyl) phenylmethane IV ` julolidine ~'5 V bis-2,5,-(p-diethylaminophenyl)-1,3,
About 30 milliliters of pyridine is then added through the . addition funnel as rapidly as possible and the resulting ~ ,, ~;10 solution refluxed for four hours. At the end of this four r,'` hour period the solution is allowed to cool and the - polymeric products contained therein precipitated by - emptying the contents of the round bottom flask into a beaker containing 1:000 milliliters of methanol, The 15 polymeric precipitate which forms is thereafter separated from the methanol by filtration. The polymeric solids which are recovered are washed several times with water and ~hen dried at 50C in a vacuum oven.
i; About 5 grams of a mixture containing equal molar V20 amounts of the above polymer and N-ethylcarbazole is dissolved in 25 milliliters of hexafluoroisopropanol and the resulting solution drawbar coated on a ball-grained aluminum plate.
Sufficient polymer solids are deposited on the aluminum plate to form a dry film having a thickness of approximately '5 20 microns. After allowing sufficient opportunity for the ; removal of solvent residues, the free surface of this polymeric film is charged to a positive potential of about 1200 volts and its rate of photodischarge determined by , -~
blanket exposure to monochromatic light at a wavelength of 5000 Angstrom Units, The rate of photodischarge of this : ~ .
.,,, '~
."; :~.
.
; ~:
.
:. ~ . - . -. .
1~5~4;Z2 plate is about 75 volts per second at fields of 60 volts per micron.
This plate is rechargecl to a positive potential of about 600 volts and thereafter exposed throuyh a resolution ; 5 target to white light. The latent image,which is formed on the surface of this photoconductive laye~ is developed with negatively charged toner particles. The resolution of the developed image is of acceptable quality.
EXAMPLE II
. . .
The procedures of Example I are repeated except for the substitution of a polyester derived from 4,5-dinitro-9-dicyanomethylene fluorene-2,7-dicarboxylic acid chloride.
; - The rate of photodischarge of a plate prepared from equal molar amounts of th:s polymer and ~-ethylcarbazole at fields L5 of 50 volts per micron is about 20 volts per second (photo-.` discharge with monochromatic light at a wavelength of 6000 Angstrom Units).
EX~MPLE III
he procedures of Example I are repeated except '0 for the substitution of one of the following monomeric electron donor materials for N-ethylcarbazole.
Examples III-VIII Electron Donor Material III bist4-diethyl-amino-2-methylphenyl) phenylmethane IV ` julolidine ~'5 V bis-2,5,-(p-diethylaminophenyl)-1,3,
4-oxidiazole ~ Vl pyrene ; VII anthracene VIII perylene `::
.... .
-12- ~ ~
: . .
... .
. , .. . . .: ; ~ . . . ..
.. : . . . , . . . , .:
.. . ~ . . . . .
"~.. : .. .. , .. . :- .
.... .
-12- ~ ~
: . .
... .
. , .. . . .: ; ~ . . . ..
.. : . . . , . . . , .:
.. . ~ . . . . .
"~.. : .. .. , .. . :- .
Claims (10)
1. A charge transfer complex formed between a monomeric electron donor material and a solid linear matrix polymer having recurring structural units of the formula wherein X is oxygen or dicyanomethylene Y and Z are independently selected from the group consisting of NO2, halogen R is a hydrocarbolene radical having from 1 to 10 carbon atoms;
R' is oxygen or sulfur;
m is 0 or 1;
a and a' can range from 0-3; and b is at least 5; a, a' and b being integers;
the relative molar concentration of monomeric electron donor per recurring structural unit of linear matrix polymer ranging from about 30:70 to about 70:30.
R' is oxygen or sulfur;
m is 0 or 1;
a and a' can range from 0-3; and b is at least 5; a, a' and b being integers;
the relative molar concentration of monomeric electron donor per recurring structural unit of linear matrix polymer ranging from about 30:70 to about 70:30.
2.. An article comprising an electrostatographic imaging member having a photoconductive layer of a bulk resistivity in excess of 1010 ohm-centimeters which comprises a charge transfer complex according to claim 1.
3. The invention according to claim 1 or claim 2 wherein the molar concentration of monomeric electron donor per recurring structural unit of linear matrix polymer being about 50:50.
4. The invention according to claim 1 or claim 2 wherein the electron donor material of the photoconductive layer is a carbazole.
5. The invention according to claim 1 or claim 2 wherein the electron donor material of the photoconductive layer is a lower alkyl substituted carbazole.
6. The invention according to claim 1 or claim 2 wherein the electron donor material of the photoconductive layer is an oxadiazole.
7. The invention according to claim 1 or claim 2 wherein the electron donor material of the photoconductive layer is an arylalkane.
8. The invention according to claim 1 or claim 2 wherein the electron donor material of the photoconductive layer is anthracene.
9. The invention according to claim 1 or claim 2 wherein the electron donor material of the photoconductive layer is a low alkyl substituted anthracene.
10. An electrostatographic imaging process comprising the steps of sensitizing followed by imagewise exposure to activating electromagnetic radiation of an electrostatographic plate comprising a conductive substrate and a layer of photoconductive material having a bulk resistivity of at least 1010 ohm-centimeters comprising a charge transfer complex formed between a monomeric electron donor material and a solid linear matrix polymer having recurring structural units of the formula wherein X is oxygen or dicyanomethylene Y and Z are independently selected from the group consisting of NO2, halogen R is a hydrocarbolene radical having from 1 to 10 carbon atoms;
R' is oxygen or sulfur;
m is 0 or 1;
a and a' can range from 0-3; and b is at least 5; a,a' and b being integers;
the relative molar concentration of monomeric electron donor per recurring structural unit of linear matrix polymer ranging from about 30:70 to about 70:30.
R' is oxygen or sulfur;
m is 0 or 1;
a and a' can range from 0-3; and b is at least 5; a,a' and b being integers;
the relative molar concentration of monomeric electron donor per recurring structural unit of linear matrix polymer ranging from about 30:70 to about 70:30.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58201575A | 1975-05-29 | 1975-05-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1054422A true CA1054422A (en) | 1979-05-15 |
Family
ID=24327496
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA250958A Expired CA1054422A (en) | 1975-05-29 | 1976-04-23 | Charge transfer complex and photoconductive insulating films incorporating same |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1054422A (en) |
| FR (1) | FR2312803A1 (en) |
| GB (1) | GB1541101A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019515090A (en) * | 2016-04-27 | 2019-06-06 | ニュードライブ リミテッド | Semiconductor composition |
-
1976
- 1976-04-23 CA CA250958A patent/CA1054422A/en not_active Expired
- 1976-05-28 GB GB22288/76A patent/GB1541101A/en not_active Expired
- 1976-05-28 FR FR7616148A patent/FR2312803A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2312803B1 (en) | 1979-05-18 |
| GB1541101A (en) | 1979-02-21 |
| FR2312803A1 (en) | 1976-12-24 |
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