Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L65/00—Compositions of macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain; Compositions of derivatives of such polymers
• • 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
  • C08G61/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
  • C08G61/02—Macromolecular compounds containing only carbon atoms in the main chain of the macromolecule, e.g. polyxylylenes
• • 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
  • C08G61/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
  • C08G61/12—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule
• • 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

Definitions

• Ar is a polyaromatic nucleus selected from the group consisting of diradicals of naphthalene, anthracene, pyrene and carbazole;
• X and Y are independently selected from the group consisting of halogen. N0 NH lower alkyl, phenyl. phenoxy. lower ulkoxy, carboxy. hydroxyl, lower alkyl esters and aryl esters;
• n can range from 0 to the total number of replaceable hydrogens on the polyaromatic nucleus
• This invention relates to a photoconductive composition, an imaging member provided with an imaging layer of the above photoconductive composition. and an imaging method. More specifically, this invention concerns a photoconductive composition possessing good ambipolar discharge characteristics which can be readily formed by standard fabricating techniques into photoconductive films useful in electrostatographic imaging.
• the developed image can then be read or permanently affixed to the photoconductor where the imaging layer is not to be reused.
• This latter practice is usually followed with respect to the binder-type photoconductive films (e.g. ZnO) where the photoconductive imaging layer is also an integral part of the finished copy.
• the latent image can be developed on the imaging surface of a reusable photoconductor or transferred to another surface, such as a sheet of paper, and thereafter developed.
• 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.
• Any one 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.
• the materials used in the photoconductive layer should preferably be capable of rapid switching from insulative to conductive to insulative state in order to permit cyclic use of the imaging surface.
• the failure of a material to return to its relatively insulative state prior to the succeeding charging sequence will result in an increase in the dark decay rate of the photoconductor.
• This phenomenon commonly referred to in the art as fatigue," has in the past been avoided by the selection of photoconductive materials possessing rapid switching capacity.
• Typical of the materials suitable for use in such a rapidly cycling system include anthracene, sulfur, selenium and mixtures thereof (U.S. Pat. No. 2,297,691); selenium being preferred because of its superior photosensitivity.
• Another of the objects of this invention is to provide a photoconductive composition having good ambipolar photodischarge characteristics.
• Still yet another of the objects of this invention is to provide an easily molded photoconductive composition from highly intractable photoconductive materials.
• Ar is a polyaromatic nucleus selected from the group consisting of diradicals of naphthalene, anthracene, pyrene and carbazole;
• X and Y are independently selected from the group consisting of halogen, N NH lower alkyl, phenyl, phenoxy, lower alkoxy, carboxy, hydroxyl, lower alkyl esters and aryl esters;
• n and n can range from 0 to the total number of replaceable hydrogens on the polyaromatic nucleus; in a host resin.
• the resulting polymeric product is preferably prepared by thermal initiation of polymerization of an intimate admixture of the above compound(s) in the host resin at temperatures in excess of 180C.
• the host polymer is heated until molten and the monomer then dispersed therein. After uniform dispersion of. the above cyclic compound(s) in the host polymer the temperature of the molten host matrix is increased above 180C and thus in situ polymerization initiated.
• the preferred cyclic compounds of this invention are cyclo bis(anthracene-9,l0-dimethylene) and cyclo bis(naphthalene- 1,4-dimethylene DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS
• the cyclic compound(s) and host polymer are initially intimately blended and then in situ polymerization initiated at temperatures in excess of 180C.
• the relative concentration of the cyclic compound(s) added to the charge will vary with the degree of photosensitivity and the mechanical properties desired.
• the charge comprises about 5 to about weight percent of the above cyclic compounds.
• cyclic compound(s) suitable for use in these photoconductive compositions are commercially available or can be prepared from relatively inexpensive starting materials by techniques fully disclosed in the literature, see, for example, Golden, J. Chem. Soc. 3741 (1961
• Representative of the cyclic compounds which can be employed in these photoconductive compositions include cyclo bis(anthracene- 9,10-dimethylene); cyclo bis(anthracenel -bromo- 9,10-dimethylene); cyclo bis( anthracene- 1 -chloro- 9, I O-dimethylene); cyclo bis( anthracene- 1 -aminoble at temperatures prevailing during in situ polymerization of these materials.
• These host resins are further characterized as being inherently inert, that is, being insulating materials and generally not regarded as photoconductive in and of themselves.
• these resins must be further compatible with the specific type of imaging mode in which the photoconductive compositions is to be ultimately used.
• the imaging layer of the photoconductive element is intended for use in a *Frost" or deformable imaging system, it must be thermoplastic and have a glass transition temperature (Tg) preferably only be somewhat above room temperature.
• Tg glass transition temperature
• thermoplastic host resins having Tgs in the range of from about 35 to about 50C are suitable for use in such deformable photoconductive imaging layers.
• Typical of the host resins which are suitable for use in photoconductive compositions of this invention include polyethylene; polystyrene; poly(l-vinylnaphthalene); polyvinylchloride; polypropylene; styrene-n-butylmethacrylate copolymers;
• the photoconductive compositions of this invention can be optionally doped with activators and dyestuff sensitizers in order to enhance the photodischarge characteristics and spectral response of the photoconductive composition.
• the activator incorporated into the photoconductive composition should be either an electron donor or an electron acceptor depending upon the relative electron affinity of the photoconductive material.
• both electron donor and electron acceptor materials can be used as sensitizers since the anthracene groups of a resulting photoconductive composition will form charge transfer complexes with both.
• electron donor sensitizers which can be incorporated into the photoconductive compositions of this invention include benzidine; N,N,N',N'- tetramethylbenzidine; 4,4'-methylenedianiline; 4,4- methylenebis( N,N-dimethylaniline 3 ,3 -dimethoxybenzidine; N,N-diphenylbenzidine; N-phenyl-ophenylenediamine; N-phenyl-p-phenylenediamine; anisole; o-anisidine; m-anisidine; p-anisidine; omethylanisole; m-methylanisole; bmethylanisole; 3-amino-N-ethylcarbazole; 2,3-diphenylindole; and mixtures thereof.
• Still yet another sensitizers which can be optionally added to the photoconductive compositions of this invention include electron acceptors such as 2,3- dichloro5 ,6-dicyano-p benzoquinone; tetracyanoethy- Iene; 2,o-dinitro-p-benzoquinone; tetracyano-pbenzoquinone; 2,3-dicyano-p-benzoquinone; 7,7,8,8- tetracyano-p-dimethylenequinone; o-bromanil; ochloranil; p-bromanil; p-chloranil; p-iodanil; trichlorop-benzoquinone; 2,6-dibromo-p-benzoquinone; 2,6-dichloro-p-benzoquinone; 2,5-dichloro-pbenzoquinone; and mixtures thereof.
• electron acceptors such as 2,3- dichloro5 ,6-
• the concentration of such activators which can be present in the above photoconductive compositions will vary widely depending upon the degree of sensitization required, and the mechanical and physical property specifications of the imaging layer.
• the upper concentration of such ingredients is generally limited by the adverse Poly styrene Host Re s in changes in physical properties accompanying such excessive additions.
• the inclusion of anywhere from about 0.1 to about weight percent, based upon the total weight of the composition, of activator to the charge during polymerization should provide the desired degree of enhancement of photosensitivity without adversely altering the compositions mechanical or physical properties and ease of thermoforming.
• dyestuff sensitizers can be used, the following being but a representative list: triarylmethane dyestuffs such as Malachite Green, Brilliant Green, Victoria Blue B, Methyl Violet, Crystal Violet, Acid Violet 6B; xanthene dyestuffs, namely rhodamines, such as Rhodamine B, Rhodamine 6G, Rhodamine G Extra, and Fast Acid Eosin G, as also phthaleins such as Eosin S, Eosin A, Erythrosin, Phloxin, Phloxin, Rose Bengal, and Fluorescein; thiazine dyestuffs such as Methylene Blue; acridine dyestuffs such as Acridine Yellow, Acridine Orange and Trypaflavine; and cyanine dyes
• the photoconductive product of this invention can be prepared in at least two ways: either, the individual components are initially blended into an intimate mixture and then heated sufficiently to initiate in situ polymerization; or alternatively, the host resin can be heated until molten and then the other individual components stirred into its fluid matrix.
• the temperature of the molten resin should be maintained below the thermal initiation temperature of the cyclic monomeric compound until the compound has been uniformly dispersed throughout its matrix. Once this preferred degree of dispersion has been attained, the temperature of the entire mass is raised sufficiently to crack the cyclic compound and thus initiate polymerization of this compound with itself and the host resin.
• the minimum temperature required to crack the cyclic compound(s) is about 180C, and most of the host resins are molten below this temperature.
• the upper limit on the temperature prevailing during polymerization is determined in large measure by the resistance of these host polymers to thermal and oxidative degradation.
• the temperature of the in situ polymerization of the cyclic compound(s) in the host resin will generally not exceed 350C and preferably not about 250C.
• Equation l Equation l where m is at least 4.
• cyclo bis(anthracene-9,l0- dimethylene) is polymerized in polystyrene in a high shear Brabender Mixer
• the probability of the interpolymerization of the above compound and host resin is enhanced due to the homogeneity of the dispersion and possibly the rupture of the polystyrene polymeric chains.
• the interpolymerization of the above compound and polystyrene is allowed to proceed for about 10 minutes and then the resultant product removed from the hopper and suspended in toluene. After being allowed to stand overnight, the suspension is contacted with methanol and vigorously agitated. The resulting yellow color developed is characteristic of precipitated polystyrene.
• polystyrene Upon recovery of this polymeric material, it is further evaluated with solvents known for their compatibility with polystyrene. In each instance, the polymeric product was soluble or capable of forming a colloidal dispersion in the solvent. Since poly(anthracene-9,l0-dimethylene) is known to be insoluble in many of the same solvents, especially toluene, it appears that the polymeric product is a complex formed by interpolymerization of the former cyclic compound and the host polymer and interpolymerization of poly(- anthracene-9,IO-dimethylene) and the host polymer.
• the photoconductive composition prepared under these high shear conditions possesses photoconduc tivity comparable to the materials prepared by routine melt polymerization techniques.
• the polymeric product thus obtained is believed to comprise a random interpretating network of photoconductive material throughout the host resin.
• the resultant polymeric products are applied in a substantially uniform coherent and adherent film to a conductive substrate.
• the method of application will vary with the method of preparation of the polymeric product.
• the polymeric products are usually east from the melt or allowed to cool and then subsequently molded on a conductive base member.
• the resultant gelatinous polymeric products are usually cast from a toluene suspension.
• the photoconductive films thus produced must be of a substantial uniform thickness and form a coherent and adherent photoconductive layer on the conductive base member. Film thickness of such photoconductive layers will generally range from about to about 50 microns; with photoconductive films in the range of about 15 to about 20 microns being preferred. Film thicknesses can be readily controlled. especially in solvent casting of the polymerization products, by merely adjusting the viscosity of the polymeric slurry or by mechanical means, such as with a doctor blade having an adjustable wet gap setting.
• the photoconductive characteristics of photoconductive films prepared from these polymeric products are evaluated on a Xerox Model D copier equipped with a 100 Watt tungsten lamp (and shutter) located at a distance of 25 centimeters from the surface of the photoconductive film.
• the Model D is also outfitted with an electrometer and a potentiometric pen recorder for graphic documentation of the voltage-time discharge behavior.
• a photoconductive composition is prepared from cyclo bis(anthracene-9,10-dimethylene) and a solid polystyrene resin.
• the polymeric product thus obtained is cast on aluminum plates. Film thickness of the polymeric overcoating is maintained within a range of about l520 microns by adjustment of the viscosity of the melt.
• the photoconductive film Once the photoconductive film has sufficiently cured, its charge acceptance and photodischarge properties are evaluated. Films prepared as described above were charged to a positive potential of 170 volts, illuminated by a 150 Watt high intensity lamp from a distance of 12 inches and the residual voltage recorded after 5 seconds. This procedure is repeated with the same films except that they are now charged to a negative potential of 280 volts. The rate of photodischarge for positively charged film is 600; and the negatively charged film 750.
• a series of photoconductive plates are prepared by compression molding polymeric products prepared from the following photoconductive compositions at 250C and 10,000 psi for 5 minutes on aluminum plates. The thickness of the films obtained averaged about 20 microns. In each of the films the cyclic compound is cyclo bis(anthracene-9,10-dimethylene).
• Example XXI The photoconductive imaging member prepared in Example I is corona charged to a positive potential of EXAMPLE XXII The imaging sequence of Example XXI is repeated except for the charging of the photoconductive surface to a negative potential of 800 volts and the development of a resulting latent electrostatic image with a relatively positive charged developer powder. Copy quality is equivalent to that attained in Example XXI.
• EXAMPLE XXVIII Example I is repeated except that in in situ polymerization of cyclo bis(anthracene-9,lO-dimethylene) in polystyrene is carried out in a high shear Brabender Mixer. Subsequent to termination of polymerization, the gelatinous polymerization products are suspended in toluene and cast on aluminum plates. The imaging members thus produced are evaluated as hereinbefore described and exhibit comparable photodischarge characteristics.
• An imaging member comprising an electrically conductive substrate having a substantially homogeneous, coherent and adherent polymeric photoconductive layer overlying and operatively associated with said electrically conductive substrate, said polymeric photoconductive layer comprising the product of the in situ polymerization of about 0.5 to about 50 weight percent, based upon the combined weight of essential components of said layer, of at least one cyclic compound of the formula:
• X and Y are independently selected from the group consisting of halogen, N0 NI-I- lower alkyl, phenyl, phenoxy, carboxy, hydroxyl, lower alkyl esters and aryl esters; and
• n and n range from O to the total number of replacable hydrogens on the polyaromatic nucleus
• a polymeric host resin said host resin being a solid at room temperature, substantially miscible with the above cyclic compound(s) and thermally stable at temperatures prevailing during in situ polymerization of the above cyclic compound(s),
• the product being (A) an interpolymer of said cyclic compound and the polymeric host resin, and (B) soluble or capable of forming a colloidal dispersion in solvents for the polymeric host resin.
• photoconductive layer is prepared from about 5 to about 20 weight percent cyclic compound(s) and about to about weight percent polymeric host resin.
• the imaging member of claim 1, wherein the cyclic compound used in preparation of the photoconductive layer is cyclo bis(anthracene-9,l0- dimethylene).
• the imaging member of claim 1 wherein the polymeric host resin used in preparation of the photoconductive layer is polystyrene.
• Ar is a polyaromatic nucleus selected from the group consisting of diradicals of naphthalene and anthracene;
• X and Y are independently selected from the group consisting of halogen, N NH- lower alkyl, phenyl, phenoxy, carboxy, hydroxyl, lower alkyl esters and aryl esters; and
• n and n range from 0 to the total number of replacable hydrogens on the polyaromatic nucleus
• a polymeric host resin said host resin being a solid at room temperature, substantially miscible with the above cyclic compounds and thermally stable at temperatures prevailing during in situ polymerization of the above cyclic compound(s),
• the product being (A) an interpolymer of said cyclic compound and the polymeric host resin, and (B) soluble or capable of forming a colloidal dispersion in solvents for the polymeric host resin;
• electrostatic image is made visible on the photoconductive surface of the imaging member by contacting said photoconductive surface with a colored developer powder, said powder being of a polarity opposite to that of the latent image.
• the imaging method of claim '9 wherein the photoconductive composition of the photoconductive layer of the imaging member is prepared from about to about weight percent cyclic compound(s) and about to about weight percent polymeric host resin.
• the photoconductive composition of the photoconductive layer of the imaging member is the product of the in situ polymerization of cyclo bis(anthracene-9,10- dimethylene) in a polymeric host resin.
• the imaging member of claim 9 wherein the photoconductive composition of the photoconductive layer of the imaging member is the product of the in situ polymerization of cyclo bis(naphthalene-l ,4- dimethylene) in a polymer host resin.
• the photoconductive composition of the photoconductive layer of the imaging member is the product of the in situ polymerization of at least one of the above cyclic compounds in polyethylene.
• the imaging method of claim 9, wherein the photoconductive composition of the photoconductive layer of the imaging member is the product of the in 18.
• the photoconductive composition of the photoconductive layer of the imaging member is prepared by the in situ polymerization of at least one of the above cyclic compounds in a polymeric resin at a temperature of from about 200 to 250C.
• An imaging member comprising an electrically conductive substrate having a substantially homogeneous, coherent and adherent polymeric photoconductive layer overlying an operatively associated with said conductive substrate, said polymeric photoconductive layer comprising the product of a thermally initiated in situ polymerization of about 0.5 to about 50 weight percent, based upon the combined weight of the essential components of said layer of at least one cyclic diameter of the formula:
• Ar is a polyaromatic nucleus selected from the group consisting of naphthalene and anthracene;
• X and Y are independently selected from the group consisting of halogen, N NH lower alkyl, phenyl, phenoxy, carboxy, hydroxyl, lower alkyl esters and aryl esters; and
• n and n range from 0 to the total number of replacable hydrogens on the polyaromatic nucleus
• a polymeric host resin said host resin being a solid at room temperature, substantially miscible with the above cyclic compound(s) and thermally stable at temperatures of from about 180 to 350C, the temperature prevailing during the in situ polymerization of the above cyclic compound(s),
• the product being (A) an interpolymer of said cyclic compound and the polymeric host resin, and (B) soluble or capable of forming a colloidal dispersion in solvents for the polymeric host resin.
• An imaging method comprising:
• an imaging member having an electrically conductive substrate having a substantially homogeneous, coherent and adherent polymeric photoconductive layer overlying an operatively associated with said substrate, said polymeric photoconductive layer being the product of the thermal initiation of the in situ polymerization of about 0.5 to about 50 weight percent, based upon the combined weight of the essential components of said layer, of at least one cyclic compound of the formula:
• Ar is a polyaromatic nucleus selected from the group consisting of diradicals of naphthalene and anthracene;
• X and Y are independently selected from the group consisting of halogen, N0 Nl-l lower alkyl, phenyl, phenoxy, carboxy, hydroxyl, lower alkyl esters and aryl esters; and
• n and n range from 0 to the total number of replacable hydrogens on the polyaromatic nucleus
• a polymeric host resin said host resin being a solid at room temperature, substantially miscible with the above cyclic compound(s) and thermally stable at temperatures of from about to 350C, the tempera ture prevailing during in situ polymerization of the above cyclic compound(s),
• the product being (A) an interpolymer of said cyclic compound and the polymeric host resin, and (B) soluble or capable of forming a colloidal dispersion in solvents for the polymeric host resin;

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Citations (3)

• 1973
  • 1973-02-20 US US333849A patent/US3879198A/en not_active Expired - Lifetime
• 1974
  • 1974-01-11 CA CA189,926A patent/CA1023189A/en not_active Expired
  • 1974-01-30 FR FR7403086A patent/FR2218583B1/fr not_active Expired
  • 1974-02-13 JP JP49017506A patent/JPS5230298B2/ja not_active Expired
  • 1974-02-20 BR BR741250A patent/BR7401250D0/pt unknown
  • 1974-02-20 DE DE2408175A patent/DE2408175C3/de not_active Expired
  • 1974-02-20 NL NL7402352A patent/NL7402352A/xx unknown
  • 1974-02-20 GB GB776274A patent/GB1446966A/en not_active Expired

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