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
  • G03G5/09—Sensitisors or activators, e.g. dyestuffs
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
  • Y10S430/10—Donor-acceptor complex photoconductor

Definitions

• a stable photoconductor may be enhanced in light sensitivity while obtaining the advantages of unstable solvent levels by milling the sensitizing disazo pigment in an alkyl substituted benzene or a blend thereof with another solvent, prior to adding it to the photoconductor matrix material. This procedure eliminates the need to retain unstable residual solvent levels in the. final photoconductor structure.
• the temperature of a photoconductor rises due to the normal operating temperatures of an electrophotographic copying machine or apparatus, and thus the residual solvent is driven off with time.
• the residual solvent is evaporated to below about 1 percent, most of the speed advantage observed as a result of the high solvent level, is dissipated.
• Some of the benefits of the high residual solvent level may be obtained by using a solvent blend where one of the solvents is tetrahydrofuran and the second solvent is an alkyl substituted benzene.
• the best results are obtained when the chlorodiane blue pigment is milled to a submicron particle size in the alkyl substituted benzene alone and slightly less effectively in a tetrahydrofuran/toluene blend.
• alkyl substituted benzene eliminates or at least minimizes any undesirable effects on the disazo pigment when the alkyl substituted benzenes are used either in a blend with tetrahydrofuran or by themselves, during the step of milling the pigment paste for addition to the photoconductive organic solution.
• EXAMPLE 1 To an abrasion resistant container is added a quantity of well cleaned steel shot. To the container and the shot is added chlorodiane blue pigment and toluene, in the proportion of 6 grams of pigment to 94 grams of tolu ene. The mixture of pigment, toluene and shot is agitated on a Red Devil paint shaker for about minutes to mill the pigment to a submicron size and wet the particles with solvent. The agitation results in a pigment paste which is removed from the steel shot and container. A quantity of pigment paste is added to 250 grams of a 1:1 molar weight ratio of PVCz:TNF charge transfer complex solution containing approximately 8 percent DuPont 49000 adhesive to yield a 6 weight percent pigment concentration based on total solids.
• the 1:1 molar ratio PVCz:TNF and 49000 adhesive are dissolved in tetrahydrofuran.
• the amount of pigment paste added depends upon the percent solids of the charge transfer complex solution.
• the above blend is then placed on the Red Devil paint shaker and vigorously agitated for about minutes.
• the blended mixture is then allowed to cool to approximately 78 F. and the viscosity of the blended solution is adjusted with tetrahydrofuran to 60 centipoise seconds at 75 F.
• the solution/dispersion is then coated onto a conductive substrate within 1 hour after the pigment paste has been added to the organic photoconductive charge transfer complex solution.
• the above procedure will result in a solvent ratio of about 83 percent tetrahydrofuran and 17 percent toluene prior to adjusting the viscosity. After viscosity adjustment, the solvent ratio will generally be in the range of 84 to 88 percent tetrahydrofuran and approximately 16 to 12 percent toluene. The toluene content of the final blend may be up to about 30 percent of the solvent and still produce improved results.
• the above procedure was performed with a polyvinylcarbazole designated Luvican M170 acquired from Badische Analin & Soda-Fabrik AG.
• a photoconductive structure was made by coating a substrate with at least one electrically conductive face with a layer of the above formulation. This structure was negatively charged by a corona and the quantity of light necessary to discharge the charged photoconductive structure to a 200 volt charge level was measured. The exposure was the converted to a relative sensitivity advantage expression resulting in a sensitivity advantage of from 2.31: to 2.5x, this figure being a relative measure of sensitivity as compared to a photoconductor without chlorodiane blue pigment and using only a tetrahydrofuran solvent, meaning that the sensitivity was 2.3 to 2.5 times that of the standard which has a value of 1.0x.
• a photoconductor coating liquid was prepared by adding to an abrasion resistant container 200 grams of clean steel shot, 57.81 grams of tetrahydrofuran and 57.81 grams of toluene.
• To this solvent blend 9.38 grams of Formvar 15/95S, a polyvinylformaldehyde resin from Monsanto Chemical Company, is added to the solvent blend and the container is agitated on a Red Devil paint shaker for approximately 20 minutes. After a 20 minute agitation on the Red Devil paint shaker, 7.37 grams of chlorodiane blue pigment is added to the container and the container is again agitated on the Red Devil paint shaker for approximately 75 minutes.
• the container is removed from the shaker and immediately 63.6 grams of the solvent/adhesive/pigment paste is added to 250 grams of a 1:1 molar ratio PVCz/T NF solution having 28 percent solids.
• This mixture is placed on the Red Devil paint shaker for 15 minutes and the solution is then allowed to cool to approximately 78 F.
• This mixture is then adjusted in viscosity with tetrahydrofuran solvent to 41 centipoise seconds at 75 F.
• This solution is then coated onto a conductive substrate within 1 hour after the paste has been added to the organic photoconductive charge transfer complex solution.
• Example 1 The polyvinylcarbazole used in this example was secured from the DeSoto Chemical Company.
• Example 2 The differences between Example 1 and Example 2 are primarily the stage at which the adhesive is added and the viscosity to which the solution is adjusted. The above procedure will result in a solvent ratio of approximately 87 percent THF and 13 percent toluene prior to viscosity adjustment and approximately 90 to 94 percent THF and 10 to 6 percent toluene after the viscosity has been adjusted.
• the pigment concentration will be 4.5 weight per cent and the adhesive concentration will be 6.0 weight percent.
• the solution is coated onto an electrically conductive substrate, negatively charged by a corona, and the quantity of light necessary to discharge the charged photoconductive structure to a 200 volt charge level, measured.
• This exposure is converted into a relative sensitivity advantage, which is based upon a photoconductive structure as discussed in FIG. 1.
• the relative speed advantage is from about 1.98x to about 2.24x.
• Photoconductive structures were formulated and constructed according to the procedure of Example 2, using the polyvinylcarbazole acquired from DeSoto Chemical Company and the Formvar 15/95S adhesive.
• the only deviation from the procedure of Example 2 was the substitution of various alkyl substituted benzene solvents to illustrate that results approximately equal to or better than that secured by the use of pure tetrahydrofuran can be secured in the case of all alkyl substituted benzene solvents tested which have a melting point less than 20 C. and a boiling point of less than approximately 250 C.
• the results of the formulations are tabularly set forth in Table 1, together with repetitive results of Examples 1 and 2.
• Examples la and 1b, and 2a through 2e are repetitive tests using the procedures of Examples 1 and 2 respectively.
• Table 11 illustrates the results using only THF in the two procedures of Examples 1 and 2, for comparative purposes.
• the residual solvent levels indicated in the table above are the residual solvent levels for the solvent indicated in the leftmost column of Table I and tetrahydrofuran in Table II.
• the tests showed no detectable tetrahydrofuran residual solvent in any of the samples tabulated in Table I. It appears that when a solvent blend of tetrahydrofuran and an alkyl substituted benzene is used and the alkyl substituted benzene is used in a range of up to about percent and preferably between about 6 to about 16 percent, any residual alkyl substituted benzene solvent level below about 1.4 percent is insufficient to exhibit a correlation between that and enhanced photoconductive properties.
• an alkyl substituted benzene solvent in a proportion of approximately 50 percent to 100 percent of the solvent used in milling the disazo pigment and particularly chlorodiane blue pigment into a paste is advantageous.
• This improvement yields an ultimate solvent blend of from 6 to about 16 percent alkyl substituted benzene and from about 84 to 94 percent tetrahydrofuran.
• This photoconductor results in most cases in improved light sensitivity over the similar type structure which was constructed using only a tetrahydrofuran solvent.
• Example 1 and Example 2 The differences between Example 1 and Example 2 above, particularly in the formulating technique and the viscosity adjustment is due, it is believed, to the difference in the molecular weights between the Luvican M170 and the DeSoto Chemical Company polyvinylcarbazole.
• the Formvar will dissolve in the THF but is partially incompatible with the PVCzzTNF complex. Therefore, it is formed as part of the pigment paste necessitating the use of a solvent blend to adequately dissolve the material and accomplish the objects of this invention.
• An electric photoconductive member comprising:
• said photoconductive matrix medium together with said disazo pigment particles,-bei'ng the residue of a coating solution/dispersion comprising a charge transfer complex of polyvinyl-carbazole and trinitrofluorenone dissolved in tetrahydrofuran;
• said pigment having been milled to submicron size particles in a solvent comprising an alkyl substituted benzene, said alkyl substituted benzene being liquid at below about 20 C. and having a boiling point of less than about 250 C.
• alkyl substituted benzenes are selected from the group consisting of benzene, toluene, ethylbenzene, xylene, propylbenzene, mesitylene, tertiary butylbenzene, and cumene.
• said alkyl substituted benzene is ethylbenzene.

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Cited By (27)

Citations (8)

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• 1972
  • 1972-12-26 US US00317893A patent/US3775105A/en not_active Expired - Lifetime
• 1973
  • 1973-10-16 AR AR250553A patent/AR198329A1/es active
  • 1973-10-17 IT IT30204/73A patent/IT995928B/it active
  • 1973-10-17 BR BR8123/73A patent/BR7308123D0/pt unknown
  • 1973-11-06 FR FR7340558A patent/FR2211680B1/fr not_active Expired
  • 1973-11-12 NL NL7315422A patent/NL7315422A/xx not_active Application Discontinuation
  • 1973-11-13 JP JP48126852A patent/JPS5122381B2/ja not_active Expired
  • 1973-11-15 GB GB5295973A patent/GB1412318A/en not_active Expired
  • 1973-11-20 CA CA186,248A patent/CA997196A/en not_active Expired
  • 1973-12-12 CH CH1739473A patent/CH588722A5/xx not_active IP Right Cessation
  • 1973-12-15 ES ES421509A patent/ES421509A1/es not_active Expired
  • 1973-12-19 DE DE2363322A patent/DE2363322C2/de not_active Expired

Patent Citations (8)

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