US3155504A - Electrophotographic materials - Google Patents

Electrophotographic materials Download PDF

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Publication number
US3155504A
US3155504A US212309A US21230962A US3155504A US 3155504 A US3155504 A US 3155504A US 212309 A US212309 A US 212309A US 21230962 A US21230962 A US 21230962A US 3155504 A US3155504 A US 3155504A
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United States
Prior art keywords
zinc oxide
electrophotographic
layer
organosilicon compound
integer
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Expired - Lifetime
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US212309A
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English (en)
Inventor
Damm Klaus
Gesierich Wolf
Heyl Gerhard
Nissl Franz
Schnurrbusch Karl
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Agfa Gevaert NV
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Agfa AG
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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
    • G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
    • G03G5/087—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic and being incorporated in an organic bonding material
    • 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
    • G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic

Definitions

  • This invention relates to improved electrophotographic materials, comprising a photoconductive layer of an insulating binding agent and zinc oxide dispersed therein, said zinc oxide has improved photoelectric properties.
  • Suitable eleetrophotographic materials comprise a photoconductive layer consisting of zinc oxide as the photoconductive compound dispersed in an insulating binding agent.
  • the said photoconductive layer is arranged on a support being sufliciently conductive.
  • the photoconduotive layer is charged electrically and image-wise exposed, the charging being dissipated at the exposed areas, corresponding to the light exposure.
  • the latent charged images thus formed can then be made visible by the aid of powder, liquid or aerosol developers, which are known per se.
  • Zinc oxide-types which are used for the production of such layers should have a highest possible light sensitivity and a lowest possible dark conductivity.
  • the high light sensitivity is desirable, so that light sources of low light intensity and short exposure times can be used.
  • the dark conductivity should be so low that no appreciable decrease in charging occurs during the period of time which is necessary for making the latent charging image visible.
  • the photoconductive layer maintains its charging for several hours or even days.
  • the most suitable Zinc oxide pigments for electrophotographic purposes are those which are prepared by the so-called French or indirect process in a high degree of purity.
  • n is an integer from 1 to 3
  • p an integer from 2 to 6
  • R represents hydrogen, an alkyl radical having up to carbon atoms, preferably methyl, an olefinically unsaturated alkyl radical, such as vinyl or an aryl radical, e.g., phenyl.
  • R stands for a hydrogen atom or an alkyl having up to 5 carbon atoms preferably methyl, or olefinically unsaturated alkyl such as vinyl, aryl such as phenyl, alkaryl or cycloalkyl radical and R" represents a lower alkyl radical having up to 5 carbon atoms, preferably methyl or ethyl.
  • Suitable compounds of Formula I are for example, octamethyl cyclotetrasiloxane, hexamethyl disiloxane, tetramethyl disiloxane, tetramethyl cyclotetrasiloxane, pentamethyl cyclotetrasiloxane or tetravinyl tetramethyl cyclotetrasiloxane.
  • Formula II includes for example the following compounds: triisopropoxysilane, tributoxysilane, methyltrimethoxysilane, phenyldimethoxysilane, dimethyldiethoxysilane, methyldipropoxysilane, trimethylethoxysilane, vinyltriethoxysilane or the like.
  • the question is not settled whether or not the improvement of the zinc oxide is due to a chemical reaction between the zinc oxide and the organo silicon compounds. It is however not essential which reasons are responsible for the improvement of the zinc oxide.
  • the organo silicon compounds may only be physically absorbed at the surface of the zinc oxide grain; in others a chemical surface reaction may occur on the zinc oxide gnain. Due to this uncertainty we want to define that where the terms reaction products or superficial reaction products are employed, we mean the zinc oxide grain con taining the 'organo silicon compound physically absorbed as well as the zinc oxide grain the surface of which has chemically reacted with the organo silicon compound.
  • the reaction vessel containing the Zinc oxide is brought to a temperature which is above the boiling point of the organosilicon compound and then the vaporized 'organosilicon compound is introduced while stirring.
  • organosilicon compounds to be used is not critical and can lie between 1 and 40% by weight, calculated on zinc oxide. No adequate water-repellent eifect is produced below 1% and more than 40% does not provide any decisive advantages.
  • the light sensitivity and the dark resistance of photoconducting zinc oxides is substantially improved.
  • the products of the process can therefore be used with advantage for the production of electrophotographic layers, for other semi-conductor layers and also for the production of toners for making latent charging images visible.
  • the follwing methods have been employed for measuring the photoelectric properties.
  • the electrophotographic material was charged by means of a corona discharge of 6 kv. and, by means of an instrument according to Schwenkhagen for measuring electrostatic field intensities, the change in the surface charging as a function of time was recorded.
  • the measurement values obtained by this method are shown in diagrams (see FIGURES 1a and 1b).
  • the photoconductor layer was exposed to light at an interval of 15 seconds with light pulses of lux-sec. and also in this case the extent of the charging was recorded (see FIGURES 2a and 217).
  • Example 1 1000 g. of zinc oxide p.a. (product of the firm Merck) were contacted at C. with 100 g, of hexamethyl disiloxane.
  • the zinc oxide was located in a heated roundbottom flask, which was equipped with a stirrer device. During the introduction of the organosilicon compound in vapour form into the reaction vessel, the zinc oxide was constantly circulated. After this treatment which was completed after about 3 hours, the reaction mixture was stirred for another 3 hours.
  • Example 2 The reaction was carried out with 1000 g. of the zinc oxide described in Example 1 and 100 g. of octamethyl cyclotetrasiloxane at 190 C.
  • the photoelectric properties of the product obtained by the process are likewise shown in FIGURES 1a and 2a. Curves designated 2 in these figures refer to this product.
  • Example 3 1000 g. of the zinc oxide described in Example 1 and 100 g. of triisopropoxysilane were used and the reaction temperature was 160 C.
  • the effect of the organosilicon compound used in this example is shown in FIGURES 1a and 2a. Curves designated 3 in these figures refer to this product.
  • Example 4 2200 g. of ZnO (as described in Example 1) and 220 g. of methyltriethoxysilane were used and the reaction temperature was 160 C.
  • FIGURES 1b and 2b again show the photoelectric effect by comparison with untreated zinc oxide. Curves designated 0 refer to products made with untreated zinc oxide while those designated 4 refer to the product of this example.
  • Example 5 1000 g. of ZnO (according to Example 1) were reacted at 150 C. with 100 g. of methyl hydrogen diisopropoxysilane.
  • FIGURES lb and 2b show the photoelectric eifect.
  • the curves designated 5 refer to the product of this example.
  • Example 6 A temperature of 130 C. was used for the treating 2200 g. of ZnO (according to Example 1) with 220 g. of dimethyl diethoxysilane. The resulting layer shows the photoelectric properties which are set out in FIGURES 1b and 2b. Curves designated 6 refer to the product of this example.
  • sensitizers By adding sensitizers to the photoconducting layer, the spectral sensitivity thereof can be increased. All dyestuffs usual for this purpose in electrophotographic practice are suitable as sensitizers in conjunction with the process according to the invention.
  • Example 7 An electrophotographic material is produced according to Example 1 and electrostatically charged by means of the corona discharge device and imagewisely exposed.
  • a filtered solution of 500 mg. of Crystal Violet (Colour Index 42555 Basic Violet 3) in 10 ml. of water is used.
  • the electrophotographic image support is for this purpose tensioned on a roller with a thickness of about 10 cm. and rolled over a sand surface which is formed into a paste with the dyestutf solution and which is spread out fiat and doctored.
  • the grain size of the sand is between and 50a. A sharp, practically grainless, violet colour image is obtained.
  • Example 8 An electrophotographic material according to the British patent specification 896,610 is produced as follows:
  • An electrophotographic image is produced as follows:
  • the electrophotographic material is charged by means of the corona discharge and thereafter exposed through the original to be reproduced.
  • the latent image obtained thereby is developed by applying the pigment an usual developer powder carrying an electrostatic charge which is opposite to that of the photoconductive layer.
  • the resulting powder image is fixed by melting the powder which is image-wisely distributed.
  • the electrophotographic layers according to the invention may be sensitized by any suitable sensitizing dye known per se, e.g., dyestuffs of the triphenylmethane, cyanine or phenol sulphon phthalein series such as Fluorescein (C.I. 45350 Acid Yellow 73), Bengal Rose GTO (CI. 45435 Acid Red 93), Thioflavine T (CI. 49005 Basic Yellow 1), Acridine Orange NO (CI. 46005 Basic Orange 14), Brilliant Green (CI. 42040 Basic Green 1) or the sensitizers described in British Patent No. 874,133.
  • the CI. numbers and the dye names in the parentheses refer to the number and name appearing in the Colour Index of The Society of Dyers and Colourists, Second Edition, London, 1958.
  • a process for improving the photoelectric properties of zinc oxide which comprises adding zinc oxide the vapors of an organosilicon compound selected from those having the following formulae:
  • R represents a member selected from the class consisting of hydrogen, alkyl having up to 5 carbon atoms, olefinically unsaturated alkyl and aryl
  • R stands for a radical selected from the group consisting of hydrogen, alkyl having up to 5 carbon atoms, olefinically unsaturated alkyl, aryl, alkaryl and cycloalkyl
  • R" represents a lower alkyl radical having up to 5 carbon atoms.
  • organosilicon compound is octamethyl cyclotetrasiloxane.
  • organosilicon compound is triisopropoxysilane.
  • organosilicon compound is methyltriethoxysilane.
  • organo silicon compound is methyl hydrogen diisopropoxysilane.
  • organosilicon compound is dimethyl diethoxysilane.
  • R represents a member selected from the class consisting of hydrogen, alkyl having up to carbon atoms, olefinically unsaturated alkyl and aryl
  • R stands for a radical selected from the group consisting of hydrogen, alkyl having up to 5 carbon atoms, olefinically unsaturated alkyl, aryl and cycloalkyl
  • R" represents a lower alkyl radical having up to 5 carbon atoms.
  • R represents a member selected from the class consisting of hydrogen, alkyl having up to 5 carbon atoms, olefinically unsaturated alkyl and aryl
  • R' stands for a radical selected from the group consisting of hydrogen, alkyl having up to 5 carbon atoms, olefinically unsaturated alkyl, aryl, alkaryl and cycloalkyl
  • R" represents a lower alkyl radical having up to 5 carbon atoms.
  • organosilicon compound is triisopropoxysilane.
  • organosilicon compound is methyltriethoxysilane.
  • organosilicon compound is dimethyl diethoxysilane.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Developing Agents For Electrophotography (AREA)
US212309A 1961-08-17 1962-07-25 Electrophotographic materials Expired - Lifetime US3155504A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEA38144A DE1157916B (de) 1961-08-17 1961-08-17 Verfahren zur Erhoehung der Lichtempfindlichkeit und Erniedrigung der Dunkelleitfaehigkeit von Zinkoxyd

Publications (1)

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US3155504A true US3155504A (en) 1964-11-03

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US212309A Expired - Lifetime US3155504A (en) 1961-08-17 1962-07-25 Electrophotographic materials

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US (1) US3155504A (xx)
BE (1) BE621481A (xx)
CH (1) CH436989A (xx)
DE (1) DE1157916B (xx)
GB (1) GB967978A (xx)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3346381A (en) * 1964-07-30 1967-10-10 Rca Corp Electrostatic recording element
US3348944A (en) * 1963-07-17 1967-10-24 Fairchild Camera Instr Co Photoengraving resist
US3453106A (en) * 1965-06-21 1969-07-01 Owens Illinois Inc Compositions exhibiting persistent internal polarization where a photoconductive material is dispersed in a polysiloxane resin derived from trifunctional monomers
US3460963A (en) * 1964-05-25 1969-08-12 Lumiere Soc Process for the manufacture of an electrophotographic material
US3475351A (en) * 1966-01-14 1969-10-28 St Joseph Lead Co Electrically conductive zinc oxide
US3509073A (en) * 1966-07-27 1970-04-28 St Joseph Lead Co Electrically conductive zinc oxide
US3867139A (en) * 1971-04-20 1975-02-18 Fuji Photo Film Co Ltd Process of making a photoconductive material of cadmium sulfide and cadmium carbonate
US4639402A (en) * 1985-08-02 1987-01-27 Xerox Corporation Photoreceptor containing selenium particles coated with a reaction product of a hydrolyzed silane

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5557203A (en) * 1978-10-25 1980-04-26 Toray Silicone Co Electric insulation modifier and method of producing same

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2494920A (en) * 1945-07-25 1950-01-17 Corning Glass Works Method of coating with organopolysiloxanes
US2579332A (en) * 1950-02-11 1951-12-18 Gen Electric Method for increasing the viscosity of liquid resinous organopolysiloxanes
US2610167A (en) * 1946-12-07 1952-09-09 Grotenhuis Theodore A Te Pigmented silicone elastomers
US2615006A (en) * 1948-04-05 1952-10-21 Du Pont Pigmentary materials
US3052540A (en) * 1954-06-02 1962-09-04 Rca Corp Dye sensitization of electrophotographic materials
US3052539A (en) * 1953-10-01 1962-09-04 Rca Corp Electrostatic printing

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2494920A (en) * 1945-07-25 1950-01-17 Corning Glass Works Method of coating with organopolysiloxanes
US2610167A (en) * 1946-12-07 1952-09-09 Grotenhuis Theodore A Te Pigmented silicone elastomers
US2615006A (en) * 1948-04-05 1952-10-21 Du Pont Pigmentary materials
US2579332A (en) * 1950-02-11 1951-12-18 Gen Electric Method for increasing the viscosity of liquid resinous organopolysiloxanes
US3052539A (en) * 1953-10-01 1962-09-04 Rca Corp Electrostatic printing
US3052540A (en) * 1954-06-02 1962-09-04 Rca Corp Dye sensitization of electrophotographic materials

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3348944A (en) * 1963-07-17 1967-10-24 Fairchild Camera Instr Co Photoengraving resist
US3460963A (en) * 1964-05-25 1969-08-12 Lumiere Soc Process for the manufacture of an electrophotographic material
US3346381A (en) * 1964-07-30 1967-10-10 Rca Corp Electrostatic recording element
US3453106A (en) * 1965-06-21 1969-07-01 Owens Illinois Inc Compositions exhibiting persistent internal polarization where a photoconductive material is dispersed in a polysiloxane resin derived from trifunctional monomers
US3475351A (en) * 1966-01-14 1969-10-28 St Joseph Lead Co Electrically conductive zinc oxide
US3509073A (en) * 1966-07-27 1970-04-28 St Joseph Lead Co Electrically conductive zinc oxide
US3867139A (en) * 1971-04-20 1975-02-18 Fuji Photo Film Co Ltd Process of making a photoconductive material of cadmium sulfide and cadmium carbonate
US4639402A (en) * 1985-08-02 1987-01-27 Xerox Corporation Photoreceptor containing selenium particles coated with a reaction product of a hydrolyzed silane

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Publication number Publication date
CH436989A (de) 1967-05-31
GB967978A (en) 1964-08-26
DE1157916B (de) 1963-11-21
BE621481A (xx)

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