US3352670A - Supersensitizers for optically sensitized photoconductive layers - Google Patents

Supersensitizers for optically sensitized photoconductive layers Download PDF

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US3352670A
US3352670A US344811A US34481164A US3352670A US 3352670 A US3352670 A US 3352670A US 344811 A US344811 A US 344811A US 34481164 A US34481164 A US 34481164A US 3352670 A US3352670 A US 3352670A
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photoconductive
supersensitizers
zinc oxide
optically sensitized
photoconductive layers
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US344811A
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Robert F Coles
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3M Co
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Minnesota Mining and Manufacturing Co
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Priority to US344811A priority Critical patent/US3352670A/en
Priority to GB2811/65A priority patent/GB1087273A/en
Priority to DE19651497177 priority patent/DE1497177A1/en
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Publication of US3352670A publication Critical patent/US3352670A/en
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    • 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
    • G03G5/0601—Acyclic or carbocyclic compounds
    • G03G5/062—Acyclic or carbocyclic compounds containing non-metal elements other than hydrogen, halogen, oxygen or nitrogen
    • 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
    • G03G5/0601—Acyclic or carbocyclic compounds
    • G03G5/0612—Acyclic or carbocyclic compounds containing nitrogen
    • 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
    • G03G5/0601—Acyclic or carbocyclic compounds
    • G03G5/0612—Acyclic or carbocyclic compounds containing nitrogen
    • G03G5/0614—Amines
    • G03G5/06142—Amines arylamine
    • 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
    • G03G5/0601—Acyclic or carbocyclic compounds
    • G03G5/0612—Acyclic or carbocyclic compounds containing nitrogen
    • G03G5/0614—Amines
    • G03G5/06142—Amines arylamine
    • G03G5/06144—Amines arylamine diamine

Definitions

  • R is selected from the group consisting of hydrogen, alkyl, alkaryl and aryl; and n is selected from Oand 1.
  • This invention relates to the optical sensitization of photoconductive materials and to methods of increasing the effectiveness of optical sensitizing dyes in photoconductive compositions useful injmage recording.
  • this'invention relates to additives which may be incorporated into photoconductive zinc oxide systems with optical sensitizers to produce a supersensitizing effect.
  • Photoconductive copysheets used in electrolytic electrophotography such as those described in US. Patent'Nos. 3,010,883 and 3,010,884, are desirably sensitized to improve and extend their spectral response and efficiency.
  • electrostatic printing such as described in U.S. Patent Nos. 3,052,539 and 3,052,540
  • the photoconductive sheets or coatings can also be dye sensitized. Because of the desirability of obtaining a white sheet color, the concentration of sensitizing dye is nor- .mallymaintained at minimum levels consistent with im 'proved spectral response.
  • supersensitization may be considered as the increase in sensitivity which is obtained by the addition of certain materials, not necessarily sensitizers per se, to a sensitized system and which is not the result of a mere additive effect.
  • supersensitization may be considered to be an exception to the general rule that the admixture of sensitizing dyes tends to reduce the overall sensitivity below that level provided by the respective components used individually.
  • Another object of this invention is to provide increased speed of response in a photoconductive zinc oxide copysheet without objectionable sheet coloration.
  • Still another object of this invention is to provide photoconductive copysheets suitable for use in electrolytic electrophotography having increased speed and sensitivity Without substantial increase in overall dark conductivity.
  • a dye sensitized photoconductive layer of a photoconductive copysheet an organic compound which is a complexing agent for zinc ion and which contains the radical form a 5 or 6 membered heterocyclic ring (e.g. morpholino, piperidino, piperazino, etc, and Y is where R is hydrogen, alkyl, alkaryl or aryl (including the substituted derivatives thereof) and n is 0 or 1.
  • an organic compound which is a complexing agent for zinc ion and which contains the radical form a 5 or 6 membered heterocyclic ring (e.g. morpholino, piperidino, piperazino, etc, and Y is where R is hydrogen, alkyl, alkaryl or aryl (including the substituted derivatives thereof) and n is 0 or 1.
  • N,N-dimethylaniline have essentially no supersensitizing value when used in conjunction with inorganic photoconductive materials (e.g., zinc oxide, cadmium sulfide, indium oxide, etc), particularly as compared to the highly eifective ring substituted anilines such as p-dimethylaminobenzaldehyde and p-dimethylaminobenzoic acid.
  • the s-upersensitizers of this invention may generally be used in amounts ranging from about 0.000l% to about 1.5% by weight of the photoconductive material, preferably from 0.0001% to about 1.5% by weight.
  • the preferred supersensitizers are not optical sensitizers per se for photoconductive zinc oxide.
  • a dispersion is prepared by ball milling for several hours a mixture of 2867 grams of powdered zinc oxide (U.S.P. 12), 2821 grams of toluene, milliliters of methanol and 2026 grams of a 30 weight percent solution of styrene-butadiene copolymer (30/70 mol ratio respectively) in toluene.
  • the test compound is dissolved in a suitable solvent, e.g. methanol, to make a 2 weight percent solution, and 3.1 cubic centimeters of the resulting solution is added to 200 grams of the dispersion. After thorough mixing the sample is allowed to stand at room conditions for about 24 hours.
  • a 3.5 milliliter quantity of the following sensitizing dye mixture is then added 'before coating:
  • optical sensitizing dyes eig. cyanines, xanthenes, merocyanines, diand tri-phenyl methanes
  • cyanines, xanthenes, merocyanines, diand tri-phenyl methanes can be used, since the supersensitizers of this invention have not been paper laminate, to provide a dry coating thickness of about 0.7 mil.
  • the coated substrate is then exposed with a standard light spectrogram source through a calibrated step wedge or a continuous grey wedge. and electroiytically developed in a known manner.
  • a control sample in which the test compound is omitted is prepared, exposed and electrolytically developed with the same procedure and under the same conditions. Visual examination and comparison of the developed samples will indicate whether the test compound performs, a supersensitizin'g function in the photoconductive layer.
  • the amount of optical dye sensitizers included in the photoconductive layer along with the organic binder and photoconductor powder can be reduced, thereby improving sheet color.
  • Essentially white or otf-white copysheets are most desired in electrolytic electrophotography.
  • photoconductive material of r a supersensitizer in said layer comprising a organic compound which is a complexing agent for zinc ion and which contains the radical where R and R tare selected from the group consisting of hydrogen, alkyl, alkaryl, and atoms necessary to form a heterocyclic ring having from 5 to 6 members;
  • Y is a radical selected from the group consisting of where R is selected from the group consisting of hydrogen, alkyl, alkaryl and aryl; and n is selected from and 1.
  • a light sensitive recording element having an optically sensitized photoconductive zinc oxide layer and being suitable for use in electrolytic electrophotography, the improvement which comprises from about 0.0001% to about 1.5% by weight of zinc oxide of a supersensitizer in said layer comprising an organic compound which is a complexing agent for zinc ion and which contains the radical Ra Y- where R and R are selected from the group consisting of hydrogen, alkyl, alkaryl, and atoms necessary to form a heterocyclic ring having from 5 to 6 members; Y is a radical selected from the group consisting of s II c.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Indole Compounds (AREA)

Description

United States Patent Ofiice 3,352,670 Patented Nov. 14, 1967 3,352,670 SUPERSENSITIZERS FOR OPTICALLY SENSI- TEZED PHQTOCONDUflTIVE LAYERS Robert F. Coles, North St. Paul, Minn, assignor to Minnesota Mining and Manufacturing Company, St. Paul,
Minn, a corporation of Delaware No Drawing. Filed Feb. 14, 1964, Ser. No. 344,811
7 Claims. (Cl. 96-15) -CRa= (N=CH),,
CHR3NH- where R is selected from the group consisting of hydrogen, alkyl, alkaryl and aryl; and n is selected from Oand 1.
This invention relates to the optical sensitization of photoconductive materials and to methods of increasing the effectiveness of optical sensitizing dyes in photoconductive compositions useful injmage recording. In one aspect this'invention relates to additives which may be incorporated into photoconductive zinc oxide systems with optical sensitizers to produce a supersensitizing effect.
The optical sensitization of photoconductive materials has been described in the literature. Photoconductive copysheets used in electrolytic electrophotography, such as those described in US. Patent'Nos. 3,010,883 and 3,010,884, are desirably sensitized to improve and extend their spectral response and efficiency. In another image recording process, i.e., electrostatic printing, such as described in U.S. Patent Nos. 3,052,539 and 3,052,540, the photoconductive sheets or coatings can also be dye sensitized. Because of the desirability of obtaining a white sheet color, the concentration of sensitizing dye is nor- .mallymaintained at minimum levels consistent with im 'proved spectral response.
Although the concept of supersensitization has been known in silver halide photography, it has not been possible merely to transfer such information, and materials over to photoconductive copysheets. Supersensitization may be considered as the increase in sensitivity which is obtained by the addition of certain materials, not necessarily sensitizers per se, to a sensitized system and which is not the result of a mere additive effect. In fact, supersensitization may be considered to be an exception to the general rule that the admixture of sensitizing dyes tends to reduce the overall sensitivity below that level provided by the respective components used individually. Though it is believed that supersensitization results from a mere efiicient transfer of energy, in the form of excited electrons, from the sensitizing dye to the zinc oxide conduction band, the actual mechanism is still not fully understood.
It is an object of this invention to provide supersensitizers for use in photoconductive systems, particularly in photoconductive recording elements.
Another object of this invention is to provide increased speed of response in a photoconductive zinc oxide copysheet without objectionable sheet coloration.
Still another object of this invention is to provide photoconductive copysheets suitable for use in electrolytic electrophotography having increased speed and sensitivity Without substantial increase in overall dark conductivity.
In accordance with this invention the above and other objects are achieved by incorporating into a dye sensitized photoconductive layer of a photoconductive copysheet an organic compound which is a complexing agent for zinc ion and which contains the radical form a 5 or 6 membered heterocyclic ring (e.g. morpholino, piperidino, piperazino, etc, and Y is where R is hydrogen, alkyl, alkaryl or aryl (including the substituted derivatives thereof) and n is 0 or 1.
Compounds such as N,N-dimethylaniline have essentially no supersensitizing value when used in conjunction with inorganic photoconductive materials (e.g., zinc oxide, cadmium sulfide, indium oxide, etc), particularly as compared to the highly eifective ring substituted anilines such as p-dimethylaminobenzaldehyde and p-dimethylaminobenzoic acid. The s-upersensitizers of this invention may generally be used in amounts ranging from about 0.000l% to about 1.5% by weight of the photoconductive material, preferably from 0.0001% to about 1.5% by weight. The preferred supersensitizers are not optical sensitizers per se for photoconductive zinc oxide.
The qualitative determination of the relative. effectiveness of a compound as a supersensitizer can readily be accomplished by the following method. A dispersion is prepared by ball milling for several hours a mixture of 2867 grams of powdered zinc oxide (U.S.P. 12), 2821 grams of toluene, milliliters of methanol and 2026 grams of a 30 weight percent solution of styrene-butadiene copolymer (30/70 mol ratio respectively) in toluene. The test compound is dissolved in a suitable solvent, e.g. methanol, to make a 2 weight percent solution, and 3.1 cubic centimeters of the resulting solution is added to 200 grams of the dispersion. After thorough mixing the sample is allowed to stand at room conditions for about 24 hours. A 3.5 milliliter quantity of the following sensitizing dye mixture is then added 'before coating:
54 milliliters of 0.2 weight percent Sul-fofiavine in methanol- 1 a 27 milliliters of 0.2 weight percent Phloxine B (CI.
42410) in methanol 19 milliliters of 0.5 weight percent Alphazurine 2G (CI.
42045) in methanol Other optical sensitizing dyes (eig. cyanines, xanthenes, merocyanines, diand tri-phenyl methanes) can be used, since the supersensitizers of this invention have not been paper laminate, to provide a dry coating thickness of about 0.7 mil. The coated substrate is then exposed with a standard light spectrogram source through a calibrated step wedge or a continuous grey wedge. and electroiytically developed in a known manner. A control sample in which the test compound is omitted is prepared, exposed and electrolytically developed with the same procedure and under the same conditions. Visual examination and comparison of the developed samples will indicate whether the test compound performs, a supersensitizin'g function in the photoconductive layer.
Illustrative examples of such ring substituted analine compounds, all of which exhibit at least a two-fold increase in sensitivity, are set forth in Table 1. Using the testing method given above, sensitivity measurements were made at 4450, 55 and 6500 angstroms. In general, the metaand para-substituted anilines, particularly nonionic para-substituted anilines are preferred. When acids are used, the corresponding salts, preferably the alkali or alkaline earth salts, may also be employed. The ability of the compound to form a complex with zinc ion can be determined in a conventional manner. Because of the enhanced sensitivity resulting from the use of such ring substituted analines, the amount of optical dye sensitizers included in the photoconductive layer along with the organic binder and photoconductor powder can be reduced, thereby improving sheet color. Essentially white or otf-white copysheets are most desired in electrolytic electrophotography.
TABLE I ii cnzmmorr SOQN;
to about 1.5% by weight of photoconductive material of r a supersensitizer in said layer comprising a organic compound which is a complexing agent for zinc ion and which contains the radical where R and R tare selected from the group consisting of hydrogen, alkyl, alkaryl, and atoms necessary to form a heterocyclic ring having from 5 to 6 members; Y is a radical selected from the group consisting of where R is selected from the group consisting of hydrogen, alkyl, alkaryl and aryl; and n is selected from and 1.
2. In a light sensitive recording element having an optically sensitized photoconductive zinc oxide layer and being suitable for use in electrolytic electrophotography, the improvement which comprises from about 0.0001% to about 1.5% by weight of zinc oxide of a supersensitizer in said layer comprising an organic compound which is a complexing agent for zinc ion and which contains the radical Ra Y- where R and R are selected from the group consisting of hydrogen, alkyl, alkaryl, and atoms necessary to form a heterocyclic ring having from 5 to 6 members; Y is a radical selected from the group consisting of s II c.
-CR3= (N=CH)n- CHR3NH where R is selected from the group consisting of hydro- 6 gen, alkyl, alkaryl and aryl; and n is selected from 0 and 1. 3. The light sensitive recording element of claim 2 in which said supersensitizer is wherein R and R are as defined in claim 2. I
4. The light sensitive recording sheet of claim 2 in which said supersensitizer is Q /N R: SOaH or a salt thereof, where R and R are as defined in claim 2.
References Cited UNITED STATES PATENTS 3,197,307 7/1965 Blake et a1 961.8 3,265,497 8/1966 Kosche 96-1.5 3,271,143 9/1966 Sorensen 961.7 3,271,144 9/ 1966 Clausen et a1. 96-1 NORMAN G. TORCHIN, Primary Examiner.
C. E. VAN HORN, Assistant Examiner.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,352,670 November 14, 1967 Robert F. Coles It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.
Column 2, line 43, for "0.001%" read 0.00015,
Signed and sealed this 3rd day of December 1968.
(SEAL) Attest:
EDWARD J. BRENNER Edward M. Fletcher, Jr.
Commissioner of Patents Attesting Officer

Claims (1)

  1. 2. IN A LIGHT SENSITIVE RECORDING ELEMENT HAVING AN OPTICALLY SENSITIZED PHOTOCONDUCTIVE ZINC OXIDE LAYER AND BEING SUITABLE FOR USE IN ELECTROLYTIC ELECTROPHOTOGRAPHY, THE IMPROVEMENT WHICH COMPRISES FROM ABOUT 0.0001% TO ABOUT 1.5% BY WEIGHT OF ZINC OXIDE OF A SUPERSENSITIZER IN SAID LAYER COMPRISING AN ORGANIC COMPOUND WHICH IS A COMPLEXING AGENT FOR ZINC ION AND WHICH CONTAINS THE RADICAL
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GB2811/65A GB1087273A (en) 1964-02-14 1965-01-21 Electrophotography
DE19651497177 DE1497177A1 (en) 1964-02-14 1965-02-12 Supersensitized photosensitive display material

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3469979A (en) * 1965-11-26 1969-09-30 Dennison Mfg Co Electrophotographic recording element with increased speed
US3635706A (en) * 1965-05-29 1972-01-18 Agfa Gevaert Ag Sensitized electrophotographic layers
US3844782A (en) * 1965-10-15 1974-10-29 Agfa Gevaert Ag Heterocyclic dye sensitised electrophotographic material
US4043813A (en) * 1973-06-06 1977-08-23 Bell & Howell Company Photoconductive particles of zinc oxide
EP0058839A1 (en) * 1981-02-23 1982-09-01 Minnesota Mining And Manufacturing Company Sensitized organic electron donor compounds

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3197307A (en) * 1964-09-22 1965-07-27 Eastman Kodak Co Surface modification of zinc oxide and electrophotographic member therefrom
US3265497A (en) * 1961-04-29 1966-08-09 Renker Belipa G M B H Fa Electrophotographic material
US3271143A (en) * 1964-01-06 1966-09-06 Minnesota Mining & Mfg Photoconductor sheet material
US3271144A (en) * 1964-09-08 1966-09-06 Minnesota Mining & Mfg Supersensitized zinc oxide

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3265497A (en) * 1961-04-29 1966-08-09 Renker Belipa G M B H Fa Electrophotographic material
US3271143A (en) * 1964-01-06 1966-09-06 Minnesota Mining & Mfg Photoconductor sheet material
US3271144A (en) * 1964-09-08 1966-09-06 Minnesota Mining & Mfg Supersensitized zinc oxide
US3197307A (en) * 1964-09-22 1965-07-27 Eastman Kodak Co Surface modification of zinc oxide and electrophotographic member therefrom

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3635706A (en) * 1965-05-29 1972-01-18 Agfa Gevaert Ag Sensitized electrophotographic layers
US3844782A (en) * 1965-10-15 1974-10-29 Agfa Gevaert Ag Heterocyclic dye sensitised electrophotographic material
US3469979A (en) * 1965-11-26 1969-09-30 Dennison Mfg Co Electrophotographic recording element with increased speed
US4043813A (en) * 1973-06-06 1977-08-23 Bell & Howell Company Photoconductive particles of zinc oxide
EP0058839A1 (en) * 1981-02-23 1982-09-01 Minnesota Mining And Manufacturing Company Sensitized organic electron donor compounds

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DE1497177B2 (en) 1970-01-08
GB1087273A (en) 1967-10-18
DE1497177A1 (en) 1969-03-27

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