US3616398A - A photoelectrophoretic imaging composition containing b-carotene - Google Patents

A photoelectrophoretic imaging composition containing b-carotene Download PDF

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US3616398A
US3616398A US887878A US3616398DA US3616398A US 3616398 A US3616398 A US 3616398A US 887878 A US887878 A US 887878A US 3616398D A US3616398D A US 3616398DA US 3616398 A US3616398 A US 3616398A
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electrode
imaging
suspension
particles
positive
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Raymond L Jelfo
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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
    • G03G17/00—Electrographic processes using patterns other than charge patterns, e.g. an electric conductivity pattern; Processes involving a migration, e.g. photoelectrophoresis, photoelectrosolography; Processes involving a selective transfer, e.g. electrophoto-adhesive processes; Apparatus essentially involving a single such process
    • G03G17/04—Electrographic processes using patterns other than charge patterns, e.g. an electric conductivity pattern; Processes involving a migration, e.g. photoelectrophoresis, photoelectrosolography; Processes involving a selective transfer, e.g. electrophoto-adhesive processes; Apparatus essentially involving a single such process using photoelectrophoresis
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/14—Transferring a pattern to a second base

Definitions

  • BACKGROUND 0? THE iNVENTiON in photoelectrophoretic imaging colored photosensitive particles are suspended in an insulating carrier liquid. This suspension is then placed between at least two electrodes, subjected to a potential difference and exposed to a light image. Ordinarily, in carrying out the process, the suspension is placed on a transparent electrically conductive member in the form of a thin film, and exposure is made through this member while a second generally cylindrically shaped biased electrode is rolled across the suspension. The particles are believed to bear an initial charge when suspended in the liquid which causes them to be attracted to the transparent base electrode and upon exposure, to change polarity so that the exposed particles migrate to the second or roller electrode thereby forming complementary images on each of the electrodes by particle subtraction.
  • the process may be used to produce both poiychromatic and monochromatic images. in the latter instance a single color photoresponsive particle may be used in the suspension or a number of differently colored particles may be used all of which respond to the exposure radiation.
  • An extensive and detailed description of the photoelectrophoretic imaging techniques as described above may be found in US. Pat. Nos. 3,383,993; 3,384,488; 3,384,565; and 3,3 84,566, and are hereby incroporated by reference.
  • Another object of this invention is to provide a novel imaging system capable of producing high-contrast, backgroundfree images in a one step process.
  • Still a further object of this invention is to provide a novel photoelectrophoretic monochromatic imaging system.
  • Still a further object of the present invention is to provide a novel monochromatic imaging composition.
  • Still another object of the present invention is to provide a one-step imaging system capable of producing highcontrast images of either optical sense regardless of the sense of the input information.
  • the foregoing objects and others are accomplished in accordance with this invention, generaliy speaking, by providing a suspension of photoelectrophoretic imaging particles in an insulating carrier liquid.
  • the suspension utilized in the process of the present invention contains ,B-carotene, a vitamin precursor additive, which makes it possible upon proper orientation of the electrode polarities to readily produce high contrast, background-free images in both a positive and negative imaging sense.
  • the suspension is interpositioned between at least two electrodes and subjected to an electrical field.
  • the suspension is selectively exposed to a reproducible image by a source of electromagnetic radiation.
  • the imaging suspension is placed on a transparent electrically conductive member of first electrode in the form of a thin film,
  • the photomigratory particles present in this suspension respond to the electromagnetic radiation to form a visible image pattern at one or both of the electrodes, the images being complementary in nature.
  • the imaging suspension employs intensely colored pigment particles the photosensitive pigment portion of which serves both as the colorant and as the photosensitive material. Additional photosensitive materials are not required thus providing a very expedient imaging process.
  • a transparent electrode generally designated l which, in this instance, is made up of a layer of optically transparent glass 2 overcoated with a thin optically transparent layer 3 of tin oxide. Tin oxide coated glass of this nature is commercially available under the trade name NESA glass.” This electrode shall hereafter be referred to as the injecting electrode.
  • a thin layer 4 of finely divided photosensitive pigment particles dispersed in an insulating carrier liquid is Coated on the surface of the injecting electrode E.
  • pliotosensitive refers to the properties of a particle which, once attracted to the injecting electrode, will migrate away from this electrode under the influence of an applied electric filed when it is exposed to actinic radiation.
  • the imaging suspension will consist of specifically colored, finely divided photosensitive particles dispersed in an insulating carrier liquid or vehicle.
  • Any suitable photosensitive pigment particle may be used such as disclosed in US. Pat. Nos. 3,384,565 and 3,384,566. As above stated, the pigment portion of the photomigratory particle provides both the photosensitivity and coloration for the respective particle.
  • Any suitable insulating carrier liquid may be used in the course of the present invention. Typical insulating carrier liquids include long chain saturated aliphatic hydrocarbons such as decane, dodecane and tetradecane, kerosene fractions such as Sohio Odorless Solvents available from Standard Oil Co. of Ohio, lsopar G commercially available from Humble Oil Co.
  • the imaging suspension may also contain a sensitizer and/or binder for the pigment particles.
  • a vitamin precursor ingredient, beta carotene generally in amounts ranging from about 0.0025 to about 1.0 gram per gram of photoresponsive or photomigratory pigment. Preferred amounts fall in the range of from about 0.0125 to 0.5 grams with op timum results being obtained in a range of from about 0.02 to about 0.1 gram.
  • a second or imaging electrode 5 which, in this illustration is represented as a roller having a conductive central core 11 connected to a power source 6.
  • the core in this instance is covered with a layer 12 of blocking material which may, for example, be polyurethane, capable of blocking DC current and referred to as a blocking layer.
  • a transfer sheet 13 or ordinary bond paper is attached to the outer surface of the roller.
  • the blocking or imaging electrode is connected to one side of potential source 6 through switch 7.
  • the opposite side of potential source 6 is connected to the injecting electrode 1 so that when switch 7 is closed an electric filed is applied across the liquid suspension 4 between electrode 1 and 5.
  • the pigment suspension is exposed by way of the projector mechanism made up of a light source 8, a transparency 9, and a lens system 10.
  • a microfilm positive is used during the process.
  • the blocking electrode 5 having a cylindrical configuration in the present illustration, is rolled across the top surface of the injecting electrode 1 supporting the suspension 4 containing the photornigratory particles.
  • Switch 7 is closed during the period of image exposure.
  • the light exposure causes the exposed pigment particles suspended in the carrier to migrate to the surface of electrode leaving behind a complementary image on the surface of the injecting electrode 1 of the unexposed particles.
  • the image sense is reversed while maintaining the same input information.
  • the blocking electrode in the present illustration is represented as a cylinder it may also take the form of a flat-plate electrode, as in the case of the illustrated injecting electrode, and the blocking electrode could be the optically transparent electrode and exposure made through it.
  • the structural arrangement of the apparatus represented by the illustration be restricted to the design as set out herein and all similar configurations which will satisfy the requirements of the present invention are contemplated.
  • all electrodes utilized may be cylindrically shaped thus providing for an expedient continuous process.
  • the pigment image produced need not necessarily be formed on the surface of an electrode but may in fact be formed on a removable paper substrate or sleeve superimposed on or wrapped around the blocking electrode or otherwise interpositioned between the electrodes at the site of imaging.
  • the pigment image may then be fixed in place as for example by placing a lamination over its top surface such as by spraying with a thermoplastic composition, or by solvent evaporation.
  • the image may also be transferred to the surface of a receiver substrate to which it may in turn be fixed. This would especially be desirable in the case where the image is formed directly on the electrode surface.
  • Such a transfer step may be carried out by adhesive pickoff techniques or preferably by electrostatic filed transfer while the image is still wet.
  • the blocking layer itself may be in the form of a removable sleeve in which instance it is simply replaced following imaging with a similar material.
  • the system herein described produces a high-contrast monochromatic image with little or no background degradation in either a positive or negative or positive to positive imaging mode by a simple reversing of the polarities within the system.
  • any suitable material may be used as the receiving or transfer substrate for the image produced such as paper or various transparent plastics such as Mylar (polyethylene terephthalatc), Tedlar (polyvinylfluoride) or cellulose acetate sheets, the latter particularly if it is desirable to produce a transparency suitable for image projection.
  • paper or various transparent plastics such as Mylar (polyethylene terephthalatc), Tedlar (polyvinylfluoride) or cellulose acetate sheets, the latter particularly if it is desirable to produce a transparency suitable for image projection.
  • injecting electrode should be understood to mean that it is an electrode which will preferably be capable of exchanging charge with the photosensitive particles of the imaging suspension hen the suspension is exposed to light so as to allow for a net change in the charge polarity on the particle.
  • blocking electrode is meant one which is substantially incapable of injecting charge carriers into the above mentioned photosensitive particles thus substantially blocking DC current. The use of the blocking electrode serves to minimize particle oscillation in the system.
  • the injecting electrode be composed of an optically transparent material, such as glass, overcoated with a conductive material such as tin oxide, copper, copper iodide, gold or the like; however, other suitable materials including many semiconductive materials such as raw cel-,
  • lophane which are ordinarily not thought of as being conductors but which are still capable of accepting injected charge carriers of the proper polarity under the influence of an applied electric field may be used within the course of the present invention.
  • the use of more conductive materials allows for cleaner charge separation and prevents posible charge buildup on the respective electrode, the latter tending to diminish the interior electrode field.
  • the blocking layer of the imaging electrode is selected so as to prevent or greatly retard the injection of charge carrier into the photosensitive pigment particles when the particles reach the surface of this electrode. Although a blocking electrode material need not necessarily be used in the system, the use of such a layer is preferred because of the markedly improved results which it is capable of producing.
  • the blocking layer when used, be either an insulator or a semiconductor which will not allow for the passage of sufficient charge carriers, under the influence of the applied field, to discharge the particles finely bound to its surface thereby preventing particle oscillation in the system.
  • the result is enchanced image density and resolution. Even if the blocking layer does allow for the passage of some charge carriers to the photosensitive particles it still will be considered to fall within the class of preferred materials if it does not allow for the passage of sufficient charge so as to recharge the particles to the opposite polarity.
  • Exemplary of the preferred blocking materials used are baryta paper, Tedlar, Mylar and polyurethane. Any other suitable materials having a resistivity of from about 10 ohmcm. or greater may be employed.
  • the core of the blocking electrode generally will consist of a material which is fairly high in electrical conductivity. Typical conductive materials including conductive rubber, and metal foils of steel, aluminum, copper and brass have been found suitable. Preferably, the core of the electrode will have a high electrical conductivity in order to establish the required field differential in the system; however, if a material having a low conductivity is used a separate electrical connection may be made to the back of the blocking layer of the blocking electrode.
  • the blocking layer or sleeve may be semiconductive polyurethane material having a conductivity of from about 10 to 10" ohms-cm. lf a hard rubber nonconductive core is used then a metal foil may be employed as a backing for the blocking sleeve.
  • Other materials that may be used in conjunction with the injecting and blocking electrodes and other photosensitive particles which may be used as the photomigratory pigments and the various conditions under which the process operates may be found in the above-cited issued patents U.S. Pat. Nos. 3,384,565 and 3,384,566 as well as U.S. Pat. Nos. 3,384,488 and 3,383,993.
  • Typical photoresponsive organic materials include substituted and unsubstituted organic pigments such as phthalocyanines, for example, copper phthalocyanine; beta form of metal-free phthalocyanine; tetrachlorophthalocyanine; and x-form of metal-free phthalocyanine; quinacridones as for example 2,9-demethyl quinacridone; 4,1 l-dimethyl quinacridone; 3,l0-dichloro-6,l3- dihydro-quinacridone; 2,9-dimethoxy-6, l 3-dihydro-quinacridone and 2,4,9,l ltetrachloro-quinacridone; anthraquinones such as l,5-bis-(betaphenylethylamino) anthra
  • organic pigments include polyvinylcarbazole; tri-sodium salt of 2-carboxyl phenyl azo (2-naphthiol-3,6-disulfonic acid; N-isopropylcarbazole; 3-benzylidene aminocarbazole; 3-aminocarbazole; l-(4-methyl-5-chloro-2'-sulfonic acid) azobenzene-2- hydroxy-3-naphthoic acid; N-2 pyridyl-8, l 3-dioxodinaphtho-( 2,1-b; 2, 3-d)furan-6-carboxamide; 2-amino-5- chloro-p-toluene sulfonic acid and the like.
  • Typical inorganic photosensitive compositions include cadmium sulfide, cadmium selenide, cadmium sulfoselenide, zinc oxide, zinc sulfide, sulfur, selenium, antimony sulfide, lead oxide lead sulfide, arsenic sulfide, arsenic-selenium, sulfurselenium and mixtures thereof.
  • the imaging suspension may contain one or more different photosensitive particles each having various ranges of spectral response.
  • a wide range of voltages may be applied between the electrodes in the system.
  • the potential applied to such as to create an electric filed of at least about 300 volts per mil across the imaging suspension.
  • the electrode spacing will be such that an applied potential of about 300 volts produces a field across the suspension of about 300 volts per mil.
  • Potentials as high as 8,000 volts have been applied to produce images of high quality.
  • the upper limit of the field strength appears to be limited primarily by the breakdown potential of the suspension.
  • the imaging suspension is generally coated to a thickness of up to about I mil or 25 microns, with a preferred operational thickness being in the range of from about 3-5 microns.
  • the injecting first electrode consists of NESA glass as described above.
  • the imaging or blocking electrode consists of a conductive steel core coated with a layer of polyurethane, unless otherwise indicated. A potential of about 7,000 volts is applied across the imaging suspension.
  • EXAMPLE I A commercial, metal-free phthalocyanine is purified by acetone extraction to remove organic impurities. Since this extraction step yields the less sensitive beta crystalline form, the desired alpha form is obtained by dissolving lOO grams of the beta form in 600 cc. of sulfuric acid. precipitating it by pouring the solution into 3,000 cc. of ice water and washing with water to neutrality. The thus purified alpha phthalocyanine is then salt milled for 6 days and desalted by slurrying in distilled water, vacuum filtering, water washing, and finally, methanol washing until the the initial filtrate is clear, thus, producing x-form phthalocyanine. After vacuum drying to remove residual methanol, the x-form phthalocyanine produced is used to prepare an imaging suspension according to the following formulation:
  • phthalocyanine 10 g. beta carotene (fl) 0.3 3.
  • sperm oil 250 cc. tricresyl phosphate 18 g.
  • the phthalocyanine is ground in a mortar, placed in a Waring blender with the other ingredients and dispersed for about 10 minutes at high speed.
  • the resulting suspension is coated on the surface of a NESA glass electrode.
  • the blocking electrode with paper sleeve is passed across the surface of the suspension liquid at a rate of about 4 inches per second, the potential is established as stated above and the suspension is selectively exposed to a light intensity of about [2 foot-candles through a positive transparency with a General Electric visible light source.
  • the blocking electrode is maintained as the positive pole and the NESA glass electrode the negative pole.
  • EXAMPLE ll The process of example I is repeated with the exception that the polarities on the blocking electrode and the N ESA glass electrode are reversed. There results a high-quality positive image on the surface of the paper sleeve thereby demonstrating the capability of the present system to image in a direct manner in a positive to positive imaging mode. Comparing the results of example 1 and example ll, there is demonstrated the claimed capabilities of the present invention, that is, the capability of imaging in either a positive to negative or positive to positive imaging mode, obtaining images in a single-pass system of high-quality, high-contrast, low-background characteristics.
  • phthalocyanine (x-form) 4 g. olive oil 20 cc. mineral oil 56 cc. tricresyl phosphate 4 3. beta carotene 0.1 g.
  • the phthalocyanine prepared according to the process of example I, is ground in a mortar, placed in a Waring blender with the other ingredients and dispersed for about 10 minutes at high speed.
  • the resulting suspension is coated on the surface of the NESA glass electrode and imaged through a positive transparency as in example l with the blocking electrode with paper sleeve having a positive polarity and the NESA glass injecting electrode a negative polarity.
  • the resulting image produced on the paper sleeve is similar to that obtained in example I.
  • EXAMPLE IV The process of example Ill is repeated with the exception that the polarities on the two electrodes are reversed. The resulting high-quality positive image obtained on the paper sleeve further demonstrates the high-quality positive to positive image capable of the present system.
  • Two separate imaging suspensions are prepared according to the process of example i.
  • the beta carotene component is excluded from each formulation.
  • the imaging suspension prepared is coated on the NESA electrode.
  • the polarity of the blocking electrode is made positive and the polarity on the injecting electrode negative.
  • the resulting image produced on the paper sleeve of example V according to the process described in example I is of a highquality, low-background nature.
  • the polarities of the two electrodes are reversed with the blocking electrodes made negative and the injecting electrode positive.
  • the resulting image produced from this arrangement, example Vi is of a low-quality, low-contrast nature. in comparing these two examples, that is, examples V and VI, it is evident that the elimination of the beta carotene component from the imaging formulation restricts the image capability of the system, to a positive to negative or negative to positive imaging system.
  • any of the above-listed typical materials may be substituted when suitable in the above examples with similar results.
  • steps used to carry out the process of the present invention other steps or modifications may be used, if desirable.
  • the process may be readily adapted to be used in a continuous imaging system.
  • other materials may be incorporated in the imaging suspension, injecting electrode or blocking electrode to enhance, synergize or otherwise desirably effect the properties of this system for their present use.
  • the imaging suspension may contain sensitizers for the photoconductive particles which are dissolved or suspended in the carrier liquid.
  • a photoelectrophoretic imaging composition comprising a vitamin precursor, beta carotene, and a plurality of photoelectrophoretic imaging particles dispersed in an insulatin carrier liquid each of said particles comprising an electrica ly photosensitive pigment w lch is both the primary electrically photosensitive ingredient and the primary colorant for said particle.
  • a photoelectrophoretic imaging composition comprising a plurality of photoelectrophoretic imaging particles and beta carotene dispersed in an insulating carrier liquid, each of said particles comprising an electrically photosensitive pigment which is both the primary electrically photosensitive ingredient and the primary colorant for said particle, said carrier liquid comprising at least one member of the group consisting of mineral oil, olive oil, sperm oil, and linseed oil.

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  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
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  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
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US887878A 1967-05-29 1969-12-24 A photoelectrophoretic imaging composition containing b-carotene Expired - Lifetime US3616398A (en)

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US88787869A 1969-12-24 1969-12-24

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BE (1) BE715671A (OSRAM)
DE (1) DE1772524C3 (OSRAM)
FR (1) FR1563584A (OSRAM)
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3976485A (en) * 1974-09-30 1976-08-24 Eastman Kodak Company Photoimmobilized electrophoretic recording process

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3976485A (en) * 1974-09-30 1976-08-24 Eastman Kodak Company Photoimmobilized electrophoretic recording process

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DE1772524C3 (de) 1974-07-18
FR1563584A (OSRAM) 1969-04-11
DE1772524B2 (de) 1974-01-03
NL6807558A (OSRAM) 1968-12-02
BE715671A (OSRAM) 1968-11-25
GB1227629A (OSRAM) 1971-04-07
DE1772524A1 (de) 1970-10-22

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