US3694201A - Method for photoconductive powder - Google Patents

Method for photoconductive powder Download PDF

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Publication number
US3694201A
US3694201A US104335A US3694201DA US3694201A US 3694201 A US3694201 A US 3694201A US 104335 A US104335 A US 104335A US 3694201D A US3694201D A US 3694201DA US 3694201 A US3694201 A US 3694201A
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United States
Prior art keywords
cadmium
powder
photoconductive
chloride
cadmium sulfide
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Expired - Lifetime
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US104335A
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English (en)
Inventor
Arthur J Behringer
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Xerox Corp
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Xerox Corp
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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 or 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 in general to a method of preparing photoconductive cadmium sulfide, cadmium selenide and cadmium sulfoselenide, particularly to such powders with improved properties.
  • the ideal photoconductive device is one which is a perfect insulator when it is not subjected to activating radiation such as light and is a perfect conductor when it is subjected to a high intensity of activating radiation.
  • activating radiation such as light
  • a photoconductive device may have a high or low resistivity. It is the signal to noise ratio which is significant. Relatively low dark resistivities on the order of to 10 ohm-cm.
  • binder layers it is possible to use photoconductive pigments with relatively low resistivities when the matrix material intercedes between the pigment particles.
  • the layer will not give effective cycling characteristics but can be used in the single mode q.v. phthalocyanine paper.
  • This latent electrostatic image is then developed or made visible by the deposition of finely divided electroscopic marking material on the surface of the photoconductor which conforms to the pattern of the latent electrostatic image.
  • the visible image may then be viewed or used in situ on the photoconductor or it may be transferred to a second surface, e.g. a copy paper.
  • the photoconductive film must have a sufficiently high dark resistivity to hold its initial charge in areas which are not exposed for at least as long a time as is required to expose and develop the photoconductor.
  • photoreceptors having minimum dark resistivities on the order of 10 ohm-cm. are required for this purpose.
  • vitreous selenium photoconductive insulators have been used with highly satisfactory results in the xerographic process, a constant search has gone on for improved materials which have the requisite dark resistivity along with increased sensitivity, wider spectral response and other desirable properties.
  • Cadmium sulfide, cadmium selenide and cadmium sulfoselenides are materials which have been investigated for use in photocells, e.g. meters, relays, etc. and also as practical alternatives for vitreous selenium.
  • the patentees describe a three step process whtich yields cadmium sulfide powder having a particulate size range of between 5 and 40 ,uIIl.
  • the cadmium sulfide particles For use in a xerographic mode, the cadmium sulfide particles must be dispersed in a transparent hinder or matrix with very high electrical resistivity in the order of 10 ohm-cm. It has been determined that particles in this size range present inherent obstacles to the fabrication of smooth surface layers having optimum xerographic development qualities. Particles in this size range necessarily have poor packing density with limitations on layer thickness which leads to inefiicient utilization of light and an increased weight quantity of photoconductor per unit area of photoreceptor. Mechanically subdividing the particles to a micron and submicron size range, e.g. by grinding, does not solve the problem because grinding drastically reduces the photoconductivity of the material.
  • Another object is to provide improved methods for preparing photoconducting powders of a particle size adapted for use in a xerographic mode.
  • Yet another object is to provide improved methods for preparing photoconducting powders having a surface mean diameter of less than 5 p.111.
  • This invention is directed to a method of preparing a photoconductive powder comprising firing at a temperature between 500 C.700 C. a member of the group consisting of cadmium sulfide, cadmium selenide and cadmium sulfoselenide with an activator proportion of a precursor containing a member of the group consisting of copper and silver, and with from 0.01 to 1 percent by weight of the composition of a member of the group consisting of cadmium chloride and zinc chloride.
  • the sole figure represents a curve showing the spectral response analysis of a material formed by the instant process.
  • EXAMPLES 1-5 A cadmium sulfide powder, commercially available from General Electric Phosphor Division (Cleveland, Ohio) as Electronic Grade 1188-2, and having a surface mean diameter,
  • m m) of 2.6 is blended with an aqueous CuCl solution so as to introduce about 0.01% Cu by weight of CdS.
  • the slurry is dried and the system reduced to a fine powder.
  • the powder is divided into five equal portions and each is moistened with a separate aqueous soluton of CdCl so as to introduce 0.03, 0.09, 0.16, 0.28 and 0.53 percent by Weight CdCl into the respective portions.
  • Each portion is dried at 140 C. for three hours and broken into small chunks.
  • a 45 gm. quantity of each portion is calcined at 600 C. for five minutes in quartz tubes.
  • Each portion is quenched in 600 cc. of deionized water and the disintegrated charges washed free of chloride ions.
  • Each portion is filtered and dried at 140 C.
  • the resulting powder is subjected to particle size and electrical analyses without further treatment.
  • a mixture of 90% by weight CdS, (same source as CdS of Examples 1-5) 9% by weight CdCl 0.9% by weight NH Cl and 0.02% by weight CuCl is heated at 600 C. in air 'for 20 minutes.
  • the resulting powder is washed free of water soluble salts, filtered and moistened with aqueous 1.0 M NH Cl and aqueous 0.1 M CdCl
  • the dried powder is sieved through a 325 mesh screen and calcined at 600 C. for twenty minutes.
  • the powder from the second calcination is treated with 0.080.3% by weight sulfur at 500 C. for ten minutes under atmospheric conditions and then under reduced pressure in the order of 10 m. Hg.
  • the resulting powder is subjected to particle size and electrical analyses.
  • a xerographic plate is prepared as follows: a mixture of the photoconductive powder of Example 2 and polyurethane, a thermosetting resin product commercially available as Zar from United Gilsonite Laboratory, Scranton, Pa., is prepared in a 1:1 volume ratio. A suitable organic solvent is used as the vehicle for the polyurethane. A layer 25-35 microns thick of this composition is silk screened onto a Nesa glass substrate, (glass coated with a thin transparent conductive tin oxide layer) providing visual inspection of the powder distribution in the organic plastic. The film is extremely smooth and the particles evenly distributed in good packing order throughout the plastic.
  • This plate was corona charged to -300 volts and then dark discharged. The rate was determined to be approximately 5 volts/second. On exposure to spectral light of 2x10 hv./cm. -sec. flux intensity, its spectral response is that represented by the curve of the drawing. This curve shows the initial photo-induced discharge rates and indicates that the plate has the appropriate photoelectrical characteristics necessary for xerographic use. The residual plate voltage on light exposure varied from a few volts to zero potential.
  • cadmium sulfide in place of cadmium sulfide, cadmium selenide and mixtures of cadmium sulfide and cadmium selenide may be employed as the host crystal.
  • cadmium chloride zinc chloride may be employed. While these materials can be employed in the range of from 0.011% by weight of the photoconductive powder, a preferred range is from 0.03-0.5%.
  • a silver activator may be employed as the equivalent of copper. These may be introduced in the form of their salts, e.g. copper chloride, copper nitrate, silver nitrate, silver chloride, etc. The activator proportion of copper or silver and chlorine is introduced into the host crystal during firing. This amount is extremely small and generally is in the order of 10 to about 10 parts per million of the activator with respect to the weight of the host crystal.
  • the firing temperature while broadly in the range of from 500700 is preferably about 600 C.
  • the time of firing should be at least long enough to incorporate the activator ions into the host crystal. At 600 C. this can usually be accomplished in from 1 to 10 minutes. Thus, by starting with photoconductive powder of less than 5 ,um. particle size, it can be activated by the present method without any meaningful grain growth.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
US104335A 1971-01-06 1971-01-06 Method for photoconductive powder Expired - Lifetime US3694201A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US10433571A 1971-01-06 1971-01-06

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US3694201A true US3694201A (en) 1972-09-26

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US104335A Expired - Lifetime US3694201A (en) 1971-01-06 1971-01-06 Method for photoconductive powder

Country Status (8)

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US (1) US3694201A (fr)
BE (1) BE777717A (fr)
CA (1) CA982808A (fr)
DE (1) DE2200061C3 (fr)
FR (1) FR2121327A5 (fr)
GB (1) GB1381162A (fr)
IT (1) IT946352B (fr)
NL (1) NL7200165A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4090983A (en) * 1975-11-06 1978-05-23 Kip Corporation Photoconductive cadmium sulfide and process for producing same
US4356246A (en) * 1979-06-15 1982-10-26 Fuji Photo Film Co., Ltd. Method of making α-silicon powder, and electrophotographic materials incorporating said powder
US4495265A (en) * 1980-03-07 1985-01-22 Gte Products Corporation Electrophotographic copper doped cadmium sulfide material and method of making

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5120276B2 (fr) * 1972-07-29 1976-06-23
JPS571151B2 (fr) * 1974-11-06 1982-01-09

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4090983A (en) * 1975-11-06 1978-05-23 Kip Corporation Photoconductive cadmium sulfide and process for producing same
US4356246A (en) * 1979-06-15 1982-10-26 Fuji Photo Film Co., Ltd. Method of making α-silicon powder, and electrophotographic materials incorporating said powder
US4495265A (en) * 1980-03-07 1985-01-22 Gte Products Corporation Electrophotographic copper doped cadmium sulfide material and method of making

Also Published As

Publication number Publication date
DE2200061C3 (de) 1978-09-21
GB1381162A (en) 1975-01-22
BE777717A (fr) 1972-07-05
CA982808A (en) 1976-02-03
IT946352B (it) 1973-05-21
NL7200165A (fr) 1972-07-10
DE2200061A1 (de) 1972-07-27
FR2121327A5 (fr) 1972-08-18
DE2200061B2 (de) 1978-01-26

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