US2940848A - Photoconductive layer for recording element and method of producing same - Google Patents

Photoconductive layer for recording element and method of producing same Download PDF

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Publication number
US2940848A
US2940848A US798679A US79867959A US2940848A US 2940848 A US2940848 A US 2940848A US 798679 A US798679 A US 798679A US 79867959 A US79867959 A US 79867959A US 2940848 A US2940848 A US 2940848A
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US
United States
Prior art keywords
layer
electrophotographic
photoconductor
base
photoconductive
Prior art date
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Expired - Lifetime
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US798679A
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English (en)
Inventor
Kostelec Joze
Heinz F Nitka
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GAF Chemicals Corp
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General Aniline and Film Corp
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Filing date
Publication date
Priority to BE588534D priority Critical patent/BE588534A/xx
Application filed by General Aniline and Film Corp filed Critical General Aniline and Film Corp
Priority to US798679A priority patent/US2940848A/en
Priority to GB8180/60A priority patent/GB937489A/en
Priority to DEG29184A priority patent/DE1234527B/de
Application granted granted Critical
Publication of US2940848A publication Critical patent/US2940848A/en
Anticipated expiration legal-status Critical
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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
    • G03G5/043—Photoconductive layers characterised by having two or more layers or characterised by their composite structure
    • G03G5/0436—Photoconductive layers characterised by having two or more layers or characterised by their composite structure combining organic and inorganic layers
    • 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
    • G03G5/043—Photoconductive layers characterised by having two or more layers or characterised by their composite structure
    • 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
    • G03G5/0622—Heterocyclic compounds
    • G03G5/0624—Heterocyclic compounds containing one hetero ring
    • G03G5/0627—Heterocyclic compounds containing one hetero ring being five-membered
    • G03G5/0631—Heterocyclic compounds containing one hetero ring being five-membered containing two hetero atoms
    • 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
    • G03G5/10—Bases for charge-receiving or other layers
    • G03G5/101—Paper bases

Definitions

  • a base plate or support is coated with a layer of photoconducting material which is then electrostatically charged in the dark.
  • the charged layer is next exposed to light beneath a pattern such as a negative photographic film, positive film or a mask or other suitable light image whereupon a latent electrostatic image is formed upon the photoconductive surface.
  • a latent image is produced by the dissipation of the electric charges in proportion to the intensity of light to which any given area of the photoconductive layer is exposed.
  • Development consists in dusting an electrically charged powder on the coating in the dark which adheres to the areas of high electrostatic charge'(corresponding to low exposure) While the powder clings only slightly or not at all in the neutralized or discharged areas (corresponding to high exposure).
  • the image can then be transferred to a suitable receiving material in order to obtain a positive or negative print as the case may be.
  • the recording element is commonly constructed in two dilferent ways.
  • a layer or film of the photoconductive material is applied directly to a conductive metal baekingmember as exemplified by the type of construction known in the art as a xerographic plate.
  • the photoconductor may be employed in the form of minute particles dispersed in an electrically insulating binder and applied to a suitable backing member.
  • xerographic plates is attendant with several disadvantages, chief among which is the need for making a transfer copy since the original electrophotographic recording element would be too bulky and expensive and generally'unsuitable as a material for permanent prints.
  • the selenium photoconducting layer is very thin and also very soft, it is easily abraded or scratched duringordinary service and such defects are transferred to the final prints produced therefrom.
  • such plates exhibit a fatigue effect after continued usage. This property or characteristic can be attributed to incomplete neutralization of the electrostatic charge on exposure to light resulting in a certain amount of permanent residual background charge. As a consequence, the residualpcharge attracts some of the developing powder giving rise to images and prints displaying darkened or foggy backgrounds.
  • the plates may be rejuvenated by subjecting them to an electrostatic charge opposite in sign to the original charge so as to neutralize the residual background charge, this requires extra time and steps which are undesirable in commercial installations.
  • electrophotographic' plates wherein the photoconductor is dispersed in an electrically insulating binder can be produced which do not possess the disadvantages associated with the aforementioned .xerographic plates.
  • the light-sensitive layer containing the dispersed photoconductor may be coated directly on a con: venient base material such as paper, exposed to light through a pattern and the resulting electrostatic image developed to yield a print immediately usable without resorting to a transfer process at any time.
  • Such electrostatic recording elements are easy to manufacture and do not require expensive and elaborate processing equipment. Furthermore, since the original recording material becomes the final'pn'nt, all the disadvantages attendant to the use and manipulation of intermediate plates are automatically eliminated.
  • an object of this invention to provide an electrophotographic recording element wherein the photoconductive material is coated on a non-metallic conductive backing.
  • Another object of the invention is to provide a method for coating the base of an electrophotographic recording element with a composition which will increase thegelec-l trical conductivity of said base plate. 1 p
  • a further object of the invention is to provide a method for the production of electrostatic images directly on a suitable recording material without having to subsequent; ly transfer the firstimage'to a. receiving material.
  • the high molecular weight imidazoline of the type suitable for practicing the invention can be represented 7 V lav-the followinggeneral formula:
  • R represents an alkyl or alkenyl group of from 1 to' 5 carbon atoms and R represents an organic groupjof at least 10 carbon atoms, i.e., an alkyl radical, e.g., decyl, undecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, etc.; an alkyl radical, e.g., decyl, undecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, etc.; an alkyl radical, e.g., decyl, undecyl, tridecyl, tetradecyl, pentadecyl, he
  • alkenyl radical e.g., decenyl, undecenyl, tridecenyl,tetradece'nyl, pentadecenyl, hexadecenyl, heptadecenyl, octadccenyhjnonadecenyl, etc.
  • 1,2-disubstitttted' imidazolines as depicted formulistically above can be prepared by re acting ethylenediamine with a long chain acylating agent and trea-ting the resulting N'-acylethylenedi-amine with calcium oxide 'in orderto effect ring closure tov the 2- 'substituted ,imidazoline, The latter product is then alkylatedwith an alkylating agent offrom 1 to 5 carbon atoms to yield a LZ-disubstituted imi'clazoline.
  • pical 1,2- disubstituted imidazolincs which can be used in practicing the invention include: e
  • Typicalbacking or plate materials whose conductivity can be increased according'to the present invention include paper, cloth, wood, plastic, leather and the like. We prefer to use paper as a support for our electrophotographic images since it is economical, readily obtainable as well as convenient to handle, store and file.
  • the invention comprises precoating a nonmetallic support such as paper with the aforesaid high 2,663,636.
  • a process comprises mixing and grinding together, in a bal1mill or other suitable comminuting equipment, a photoconducting material together with a solvent and a binder material having an electrical volume resistivity of about 10 to 10 ohms centimeter for a period of time suflicient to efiect reduction to the desired particle size.
  • An electrophotographic element of the latter type comprises a paper support having coated thereon a fluorescent intensifying layer or screen which is then overcoated by a second layerof a photoconduotor dispersed in an electrically insulating binder.
  • a multiple coating tends to yield images having a fairly high fog background since the neutralized electric charges in the light exposed areas do not conduct away as easily as in the electrophotographic' elements which do not contain the fluorescent layer.
  • a double layer coating can be made to yield images with little or no fogforming background by dispersing particles of the fluorescent material in the-above described high molecular molecular weight imidazolines.
  • FIG. 1 andZ represent sectional views of an electrophotographic member con structed in accordance with our invention.
  • a base plate 1 of paper has precoated thereon a layer'Z of a high molecular weight imidazoline described above which, in turn, is overlaid with a photoconductive insulating layer 3 comprising an electrical insulating binder 4 having dispersed therein particles of a photoconducting material 5.
  • Fig. 2 1 is a base orbacking support; 6 represents a, fluorescent layer comprising a high molecular weight imidazoline matrix 2 having imbedded or dispersed therein particles of a fluorescent material]; and 3 is a photoconduotive layer in'which the'photoconducting material 5 is dispersed or distributed throughout an electrically insulating binder 4.
  • photoconductors which we can employ for the purpose described herein include zinc oxide, sulfur, anthracene, anthraquinone, lead oxide, lead iodide, cadmium sulfide, cadmium selenide and the like.
  • sensitizing dyes in electrostatic recording elements in order to. alter the spectral response of a particular photoconductive material.
  • a sensitizing dye may be selected for the purpose of increasing the speed of the spectral response of a photoconductive material by extending or increasing the characteristic or inherent absorption of the photoconducting material itself.
  • the dye may be selected for the purpose of sensitizing the photoconducting material to a difierent portion of the, spectrum and thus extend the band of frequencies to which the photoconducting material will respond,
  • the phthaleintype dyes such as Rose Bengal
  • the triphenylmethane dyes such as, malachite green and methyl green
  • the cyanine dyes such as kryptocyanine, acridine orange, as well as many others.
  • the coating compositions containing a high molecular weight imidazoline are prepared by dissolving the appropriate imidazoline in an appropriate solvent and the resulting mixture coated on a non-metallic base of the type previously described.
  • various adjuncts may be desirable to add various adjuncts to the composition in order to facilitate the coating operation.
  • Example 1 A paper base was coated with the following composition:
  • the resistivity of the paper base coated in such a manner was 2.61 X or less ohms centimeter. This compares to 1.5)(10 ohms centimeter for the untreated paper.
  • a second coating consisting of a dispersion of a photoconductor in a binder was prepared as follows: 20 g. of zinc oxide, 16 g. of silicone resin and 20 g. of toluene were placed in a porcelain ball-mill of one quart capacity half filled with 0.5 in. porcelain balls and milled for about two hours. The mixture was then coated by applicator roller method on the above subbed paper base and allowed to dry. The thickness of the photoconductive layer was about 10 microns. An electrostatic charge was placed on the plate and exposed to radiation to effect discharge of the plate. The residual surface charge was then measured using a dynamic electrometer. A second electrophotographic plate was prepared as above except the paper base was not treated with the high molecular weight imidazoline. On charging and exposing, the residual surface charge on the second plate was much higher than in the case of the first plate. 7
  • the silicone resin was obtained on the commercial market as GE Silicone Resin SR-82, a product of the General Electric Company, Pittsfield, Mass.
  • the zinc oxide photoconductor was purchased commercially as French Process Florence Green Seal Pigment Grade, a product of the New Jersey Zinc Sales Company, Inc., New York, New York.
  • the 1-isopropyl-Z-undecylimidazoline was prepared by acylating ethylenediamine with lauroyl chloride and the resulting N-lauroylethylenediamine cyclized to Z-undecylimidazoline using calcium oxide. The latter product was then alkylated with isopropyl halide to yield the desired l-isopropyl-Z-undecylimidazoline.
  • isopropyl halide for more detailed directions concerning the synthesis of such compounds, reference is made to the previously cited U.S.P. 2,404,300.
  • Example 2 The same procedure was followed as given in Example Example 3 15 grams of zinc sulfide (copper and cobalt activated) and 20 g. of the 1-isopropyl-2-undecylimidazoline solution of Example 1 was ball-milled for two hours. The resulting dispersion of fluorescent agent was then coated on a metal base using the applicator roller method. The thickness of the layer amounted to about 10 microns. A photoconductive layer of the type described in Example 2 was next applied over the first layer and allowed to dry.
  • the resulting electrophotographic recording element containing an intermediate fluorescent layer interposed between the base and photoconductive layer is particularly valuable in the field of radiography wherein the exciting radiation are X-rays.
  • the element is first electrostatically charged in the usual manner and then-exposed to an X-ray pattern or image. At the exposed areas, the electrostatic charges comprising the latent image are neutralized.
  • the X-rays causes the fluorescent layer to emit light which neutralizes more of the electrostatic charges.
  • the combination of a fluorescent substance and photoconductor operate in a synergistic manner to increase the efliciency of the system.
  • Example 4 The same procedure was employed as given in Example 3 excepting that the metal base was replaced by a paper base coated with the 1-isopropyl-2-undecylimidazoline of Example 1.
  • An electrophotographic member comprising a base having applied thereon a pretreatment of a surface active high molecular weight imidazoline of the following formula:
  • R represents an organic grouping of at least 10 carbon atoms and being selected from the class consisting of alkyl and alkenyl radicals and R represents an organic grouping of from 1 to 5 carbon atoms and beingselected from the class consisting of alkyl and alkenyl radicals and a photoconductive insulating layer thereover comprising a photoconductor uniformly dispersed in an electrically insulating binder having an electrical resistance higher than that of the base plate and photoconductor.
  • An electrophotographic member comprising a base plate, an intermediate fluorescent layer bonded thereto, said layer comprising a fluorescent material dispersed uniformly throughout a surface active high molecular weight imidazoline of the following formula:
  • R represents an organic grouping of at least 10 carbon atoms and being selected from the class consisting of alkyl and alkenyl radicals and R represents an organic grouping of from 1 to 5 carbon atoms and being selected from the class consisting of alkyl and alkenyl radicals and a photoconductive insulating layer thereover comprising a photoconductor uniformly dispersed in an electrically insulating binder having an electrical ret '4.
  • the fluorescent material is selected from the class consisting of copper activated zinc sulfide, copper and cobalt activated zinc sulfide, silver activated zinc sulfide, zinc'cadmium sulfide, magnesium titanium dioxide, calcium tungstatte and cesium halide.
  • R represents an organic grouping of at least 10 'carbon atoms and being selected from the class consistingof alkyl and alkenyl radicals and R represents an organic grouping of from 1 to 5 carbon atoms and being selected from the class-consisting of alkyl and alkenyl radicals and a photoconductive insulating layer thereover comprising a photoconductor uniformly dispersed in an electrically insulating binder having an electrical resistance higher than that of the base plate and photoconductor, selectively neutralizing the electrostatic charge from the surface of the charged photoconductive insulating layer by exposing said charged layer to radiation of a wave length ranging from 10- centimeters to 10 'centimeters thereby creating; an electrostatic latent image on the surface of the photoconductiveinsulating layer and developing said electrostatic latent image with electricallly charged powder particles.
  • An electrophotographic process comprising placing an electrostatic charge on the surface of an'electrophotographic member comprising a base having applied thereon a pretreatment of a surface active high molecular weight imidazoline of the following formula:
  • RFC cm CHr carbon atoms and being selected from the class consisting of alkyl and alkenyl radicals and R represents an organic grouping of from 1 to 5 carbon atomsand being selected from the class consisting of alkyl and alkenyl radicals and a photoconductive insulating layer thereover comprising a photoconductor uniformly dispersed in an electrically insulating binder having an electrical resistance higher than that of the base plate and photoconductor, selectively neutralizing the electrostatic'charge from the surface of the, charged photoconductive insulating layer by exposing said chargedlayer to radiation of a wave length ranging from 10- centimeters to l0- centimeters thereby'creating an electrostatic latent image on the surface of the photoconductive insulating layer and developing said' electrostatic latent image with electrically charged powder particles.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Nitrogen Condensed Heterocyclic Rings (AREA)
US798679A 1959-03-11 1959-03-11 Photoconductive layer for recording element and method of producing same Expired - Lifetime US2940848A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE588534D BE588534A (ja) 1959-03-11
US798679A US2940848A (en) 1959-03-11 1959-03-11 Photoconductive layer for recording element and method of producing same
GB8180/60A GB937489A (en) 1959-03-11 1960-03-08 Photoconductive recording element and method of producing same
DEG29184A DE1234527B (de) 1959-03-11 1960-03-08 Elektrophotographisches Aufzeichnungsmaterial

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US798679A US2940848A (en) 1959-03-11 1959-03-11 Photoconductive layer for recording element and method of producing same

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3114633A (en) * 1959-04-18 1963-12-17 Azoplate Corp Material for electrophotographic and electroradiographic purposes
US3139338A (en) * 1959-03-18 1964-06-30 Azoplate Corp Electrophotographic material and process
US3159483A (en) * 1959-07-14 1964-12-01 Azoplate Corp Process for the preparation of electrophotographic reversed images
US3163530A (en) * 1959-05-05 1964-12-29 Azoplate Corp Material for electrophotographic purposes
US3226227A (en) * 1960-09-02 1965-12-28 Rca Corp Method of producing a solvent-resistant pattern using developed electrostatic image formation techniques
US3236640A (en) * 1959-12-29 1966-02-22 Azoplate Corp Process for the preparation of printing plates using particularly a photoconductivemultilayer structure
US3403019A (en) * 1965-02-15 1968-09-24 Eastman Kodak Co Photoconductive electrostatic elements containing polyurethanes in the photoconductive layer
US3652270A (en) * 1969-01-10 1972-03-28 Matsushita Electric Ind Co Ltd Recording devices
US4070577A (en) * 1976-09-10 1978-01-24 Xonics, Inc. Imaging systems with fluorescent and phosphorescent toner

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3139338A (en) * 1959-03-18 1964-06-30 Azoplate Corp Electrophotographic material and process
US3114633A (en) * 1959-04-18 1963-12-17 Azoplate Corp Material for electrophotographic and electroradiographic purposes
US3163530A (en) * 1959-05-05 1964-12-29 Azoplate Corp Material for electrophotographic purposes
US3159483A (en) * 1959-07-14 1964-12-01 Azoplate Corp Process for the preparation of electrophotographic reversed images
US3236640A (en) * 1959-12-29 1966-02-22 Azoplate Corp Process for the preparation of printing plates using particularly a photoconductivemultilayer structure
US3226227A (en) * 1960-09-02 1965-12-28 Rca Corp Method of producing a solvent-resistant pattern using developed electrostatic image formation techniques
US3403019A (en) * 1965-02-15 1968-09-24 Eastman Kodak Co Photoconductive electrostatic elements containing polyurethanes in the photoconductive layer
US3652270A (en) * 1969-01-10 1972-03-28 Matsushita Electric Ind Co Ltd Recording devices
US4070577A (en) * 1976-09-10 1978-01-24 Xonics, Inc. Imaging systems with fluorescent and phosphorescent toner

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GB937489A (en) 1963-09-18
DE1234527B (de) 1967-02-16
BE588534A (ja)

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