US3135695A - Liquid developers for electrostatic photography - Google Patents

Liquid developers for electrostatic photography Download PDF

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Publication number
US3135695A
US3135695A US90404A US9040461A US3135695A US 3135695 A US3135695 A US 3135695A US 90404 A US90404 A US 90404A US 9040461 A US9040461 A US 9040461A US 3135695 A US3135695 A US 3135695A
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United States
Prior art keywords
toner
liquid
developer
pigment
present
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US90404A
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English (en)
Inventor
William C York
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Eastman Kodak Co
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Eastman Kodak Co
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Publication date
Priority to BE614048D priority Critical patent/BE614048A/xx
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Priority to US90404A priority patent/US3135695A/en
Priority to DEE22080A priority patent/DE1215524B/de
Priority to FR888181A priority patent/FR1322308A/fr
Priority to GB5770/62A priority patent/GB993150A/en
Application granted granted Critical
Publication of US3135695A publication Critical patent/US3135695A/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
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/12—Developers with toner particles in liquid developer mixtures
    • G03G9/125—Developers with toner particles in liquid developer mixtures characterised by the liquid
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S101/00—Printing
    • Y10S101/37—Printing employing electrostatic force

Definitions

  • This invention relates to Xerography and more par ticularly to a novel composition of matter for developing a visible image from a latent electrostatic image existing as a charged pattern on xerographic plates.
  • Liquid xerographic developers for the most part, however, have encountered a difiiculty in stability in that they tend to clump on standing and in many cases the charged pigment particle tends to lose charge, exhibits a charge reversal, or a change in pigment-tobinder ratio, etc.
  • the present invention overcomes, very unexpectedly, each of these persistent dir culties by a relatively simple process such that charged pigment-suspending liquid developers are stable beyond 800 hours.
  • Another object of the present invention will be to provide a process for preparing the stable liquid electrostatic developers of the present invention.
  • a further object is to provide a process for developing an electrostatic image to a visible image using an electrostatic developer of the present invention.
  • the objects of the present invention are accomplished by surrounding individual xerographic type pigment particles with a suitable resinous-binder envelope, treating the pigment-binder combination with a small amount of an alkyl-aryl compound before suspending the combination in a liquid aliphatic carrier.
  • the resin used to enclose the pigment particles of the present invention can be any of the well known resins which are soluble in aromatic solvents, but insoluble, or at least only slightly soluble, in aliphatic solvents.
  • the liquid aliphatic carrier according to the present invention must have a low dielectric constant and a resistivity of at least about ohm centimeters to preclude the possibility of discharging the latent electrostatic image.
  • the low dielectric constant is needed so that the energy in the image field is not dissipated in aligning and moving highly polar molecules. If the pigment-binder combination, i.e., toner, of the present invention is dispersed in the liquid aliphatic carrier without first treating it with an alkyl-aryl compound, the system coagulates badly. Where the pigment-binder combination is prepared, treated and suspended in an aliphatic carrier according to the present-invention, liquid electrostatic developers have been prepared which are stable beyond 800 hours without apparent deleterious efiect.
  • the alkyl-aryl compound used as a treating means for the pigment-binder combination becomes oriented so that the aryl group is directed inward towards the aromatic soluble binder and the aliphatic tail is directed outward forming a liquid bridge between the aromatic soluble binder and the aliphatic carrier.
  • the liquid electrostatic developers of the present invention remain stable over very long periods with the binder remaining as a discrete envelope surrounding the pi ment particle and without the binder diffusing into the carrier liquid. Where such stability of the binder in liquid developers of this type is not obtained there results a number of deleterious effects including an undesirable shift in the pigment to binder ratio with progressive use and age of the developer.
  • the single figure of the accompany ng drawing is shown a hypothetical orientation of an allryl-aryl compound, propyl benzene, to the aromatic soluble resin envelope surrounding a pigment particle having a positive charge.
  • the toner i.e., pigment particle-resinous envelope combination is, of course, according to the invention suspended in an aliphatic liquid carrier which is represented in the present drawing as a hypothetical diffuse negative layer surrounding the positively charged toner particle.
  • an electrostatic latent image can be produced by any of a number of procedures recognized in the art.
  • a sensitive element may be produced by coating a support with a suitable photoconductor, such as those described in the Carlson patents cited above, and imparting a uniform charge to said sensitive element by any of the known means such as corona discharge and by rubbing as also described in the Carlson patents.
  • the charged sensitive element is exposed to a pattern of light and shadow illumination whereby the illuminated areas are discharged and a charged image pattern remains which is developed to a visible image by flowing a developer of the present invention over the differentially charged surface.
  • the electrostatically attractable particles carried in the insulating liquid of the developer solution are brought into contact with the electrostatic image which results in the particles being deposited on the charged areas of the sensitive element so that the charged areas are immediately rendered visible because of the optical character istics of the toner particles. Because of the highly volatile nature of the aliphatic carriers of the developer composition, fast drying results and a visible, permanent image is rapidly obtained.
  • the preferred resinous binders should also be non-chalking, should'dry to a tough wear-resistant film and should have a refractive index conducive to enhance color or transparency.
  • suitable resinous materims should have no adverse effect on particle charge or on developer stability. Resinous materials which I have 'either negative or positive.
  • Suitable for use in the present stabilized liquid developers can be selected from a number of synthetic resins, modified resins, rosin esters, modified rosin esters, etc. Examples of suitable resins to which I refer are given in Table 1 below. i
  • Dymal XLM 110 aleie alkyd D0.
  • Dyrnal XLM 101.. d Do.
  • the pigments which can be used in preparing the toners of the present invention can vary Widely.
  • numerous organic and inorganic materials including talcum powder, aluminum bronze, carbon dust, gum copal, gum sandarac, ordinary rosin, and others.
  • the principal requirements of any of the pigments used in the present invention is that they are particulate and capable of carrying an electrostatic charge.
  • the solid particles When finely divided pigments are suspended or dispersed in a suitable liquid vehicle, as is shown, the solid particles usually acquire a charge.
  • an alkyl-aryl stabilized toner can be prepared by milling together a suitable pigment with a suitable solution of resin or mixture of such resins as set forth hereinabove.
  • Suitable carriers for dispersing the stabilized toners comprise liquids possessing a'high dielectric resistance. In order to avoid discharge of a latent electrostatic image, a liquid with a resistivity of about at least 10 ohm centimeters is necessary.
  • Liquids which I have found suitable include cyclohexane, carbon tetrachloride, mixed halides such as trichlorotrifluoroethane, sold under the trade name Freon 113 by E. I.
  • du Pont de Nemours and Co. cyclopentane, n-pentane, n-hexane, etc.
  • heavier oils can be used, such as kerosene, mineral oil, silicone oil, etc. When these latter mentioned liquids are used, however, they usually require heat to set the toner and drive off excess carrier.
  • the alkyl-aryl treating compound employed before dispersion of the pigmentbinder combination in a suitable carrier can be selected from the compounds represented by the following general formula 'wherein R represents at least one straight chain or branched-chain alkyl group having from 1 to about 12 carbon atoms and Z represents the non-metallic atoms necessary to complete an aromatic nucleus selected from the class comprising benzene, naphthalene, and anthracene.
  • solvents of the present type comprise xylene, mesitylene, ethylbenzene, n-propylbenzene, n-butylbenzene, isobutylbenzene, n-pentylbenzene, n-hexylbenzene, n-propyl naphthalene, butyl naphthalene, propyl anthracene, butyl anthracene, and the like.
  • Useful results were obtained using isomers as well as the normal aliphatic hydrocarbons and mixtures of each thereof.
  • the preferred alkyl-aryl compounds are those in which the aryl substituent is benzene.
  • aryl substituent is benzene and the alkyl group is selected from those having from 3 to 6 carbon atoms.
  • Preparation of any of the alkyl-aryl compounds of this invention can be by any of the well known methods.
  • the toner is first prepared by mixing a uniform dispersion of the pigment in an aromatic solution of the resinous material and thereafter mixing and milling the combination to produce a finely divided toner paste of desirable particle size.
  • the mixing and milling may be done by various means including a combination of the steps of blending, mixing, and milling wherein the preferred method for the milling step includes a rather extensive milling period to assure uniform and fine dispersion or" the pigment in the resin.
  • the toner is removed from the mill jar.
  • the toner is then treated with a small amount of an alkylaryl compound such as propylbenzene.
  • the treatment required is usually dispersing the toner in the propylbenzene and thoroughly mixing.
  • the dispersion is added to the aliphatic carrier of choice. Liquid electrostatic developers prepared in this manner have been checked periodically over a period beyond 800 hours without the developer showing signs of deleterious effects.
  • Example 1 Prior to addition in the above composition the Pentalyn M was digested in a 1:1 ratio in a hydrocarbon mixture sold commercially under the trade name Solvesso 100 by the Esso Standard Oil Co.
  • xnmple 2 An alkyl-aryl stabilized liquid developer was used to develop the latent electrostatic image on xerographic printing material after thermographic exposure according to the following procedure.
  • the xerographic printing material was prepared according to the disclosure of Dulmage et al. U.S. application Serial No. 25,109, filed April 27, 1960, and comprises coating a one-half mil thickness of polyethylene terephthalate taped onto a glass support with a 10 percent solution of a lower melting polyester dissolved in methylene chloride. The coating was placed on the plate at a 0.006- inch wet thickness. After drying for about 3 minutes a sheet of paper 1.5 mil thickness was rolled onto the tacky coating with a small hand roller and the combination was oven-dried at 75 C. The polyethylene terephthalate surface was then charged by passing under a negative corona wire at a potential of 10 kv.
  • a document was laid onto the charged surface and the sandwich was given a reflex exposure under a high intensity infrared source such as commonly used in thermography. After radiation exposure the xerothermographic sheet was developed by allowing a liquid developer of the following composition to flow over the surface of the plate.
  • the toner of negative charge adhered only to the areas from which the excellent chemical resistance) 20 Amberol 808 (a trade name of Rohm and Haas Co.
  • the xerothermographic sheet developed with a negative toner of the above composition was then placed in contact with a sheet of ordinary typewriter paper and passed again under the infra-red lamp which resulted in the image from the xerothermographic sheet being transferred to the typewriter paper to produce a permanent copy thereon.
  • Excellent well-defined images were obtained by the process of the present example with the images having a very clear background.
  • the alkyl-aryl stabilizing compound In preparing the stabilized electrostatic developers of the present invention it is usually required that only relatively small amounts of the alkyl-aryl stabilizing compound need be employed. Ordinarily the toner particles are treated with an alkyl-aryl compound in an amount by weight about equivalent in a ratio of from about 1:5 to 5:1 toner to alkyl-aryl compound.
  • the toner is usually contained in the final developer composition in concentrations in the range from about 1 percent to about 20 percent by weight. Accordingly, the aliphatic carrier can make up from about 60 percent to about 98 percent by weight of the total composition.
  • the wide range of resinous materials suitable for use in preparing the toner particles according to the present invention makes possible a wide range of processes with which stabilized developers of the present invention can be used.
  • One such process includes the making of color prints.
  • the instant-drying feature of the present invention with no smearing and without requiring fusion of xerographic elements developed with the liquid developers of this invention makes possible the multi-step processing necessary to achieve color prints.
  • the fastdrying highly volatile aliphatic carriers make possible an almost continuous process for preparing multi-color prints.
  • a resolution of about 40 lines per millimeter can be obtained on standard zinc oxide xerographic plates where a toner particle having a diametric size of about 1.0 micron is used.
  • various materials and compositions thereof can be used to encompass a wide variety of materials, for example, lithographic ink, gravure ink, silk screen ink, paints, artists colors, flash colors, etc.
  • liquid xerographic development can be used in preparing line copy, half-tone negatives or positive, continuous tone prints, etc.
  • the particle size of the pigment and the electroscopic toner should be in the range from about .1 micron to about 20 microns. Particle sizes in this range when used with standard xerographic printing plates gave the desired degree of resolution.
  • the particle size of the toners is usually the result of the time and methods used in the ball milling process. For example, the particle size of many of the pigments can be reduced to less than 20 microns by milling for about 6 to 8 hours. For purposes where the particle size should be 10 microns or less an extended ball-milling period was usually satisfactory to produce the desired particle size. Where continuous tone copy was to be developed using liquid developers it was usu ally desired for obtaining optimum resolution that particle sizes be reduced to about 1 micron. In this case a super ball mill was required.
  • a stabilized liquid developer for developing latent electrostatic images said developer consisting essentially- 8 wherein R represents at least one aliphatic- -group having from 1 to 12 carbon atoms, and the dispersion of toner in alkyl-aryl solvent being further dispersed in 4 (3) a liquid carrier phatic hydrocarbon having an electrical resistivity of at least 10 ohm centimeters and a low dielectric constant, said developer containing, said toner and said alkyl-aryl solvent in a range of ratios by weight from about 1:5 to about 5:1, said toner making up from about 1 percent to about 20 percent of said developer and said liquid carrier making up from about percent to about 98 percent by Weight of the said developer.
  • the stabilized liquid developer of claim 1 for developing latent electrostatic images in which the said alkyl -aryl solvent is propylbenzene.
  • the stabilized liquid deveolper of claim 1 for developing latent electrostatic images in which the resinous binder is a phenol modified pentaerythritol ester of rosin acid and the aliphatic hydrocarbon carrier is cyclohexane.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Liquid Developers In Electrophotography (AREA)
  • Developing Agents For Electrophotography (AREA)
US90404A 1961-02-20 1961-02-20 Liquid developers for electrostatic photography Expired - Lifetime US3135695A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE614048D BE614048A (en)van) 1961-02-20
US90404A US3135695A (en) 1961-02-20 1961-02-20 Liquid developers for electrostatic photography
DEE22080A DE1215524B (de) 1961-02-20 1961-12-07 Verfahren zur Herstellung eines fluessigen Entwicklers fuer Ladungsbilder
FR888181A FR1322308A (fr) 1961-02-20 1962-02-15 Nouveau révélateur liquide stabilisé utilisable en électrophotographie
GB5770/62A GB993150A (en) 1961-02-20 1962-02-15 Improvements in or relating to electrophotography

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Application Number Priority Date Filing Date Title
US90404A US3135695A (en) 1961-02-20 1961-02-20 Liquid developers for electrostatic photography

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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3296140A (en) * 1964-02-13 1967-01-03 Dick Co Ab Liquid developer for electrographic printing
US3300410A (en) * 1961-03-13 1967-01-24 Australia Res Lab Conductive liquid developer for xerographic images
US3507794A (en) * 1964-12-22 1970-04-21 Harris Intertype Corp Electrostatic photography systems
US3549361A (en) * 1966-08-01 1970-12-22 Eastman Kodak Co Electrophotographic compositions and elements
US3640863A (en) * 1968-06-05 1972-02-08 Ricoh Kk A liquid electrostatic having pigment particles coated with a cyclized rubber
US3668127A (en) * 1968-07-01 1972-06-06 Ricoh Kk Liquid developer for electrophotography
US3779924A (en) * 1971-04-01 1973-12-18 Eastman Kodak Co Process for preparing electrophotographic liquid developing compositions
FR2192329A1 (en)van) * 1972-07-12 1974-02-08 Agfa Gevaert
US3833369A (en) * 1972-12-29 1974-09-03 Polaroid Corp Color diffusion transfer films and processes with polymer encapsulated reflecting agents
FR2235403A1 (en)van) * 1973-06-29 1975-01-24 Kalle Ag
US3878120A (en) * 1966-11-28 1975-04-15 Shinichiro Nagashima Process for preparing liquid developer for electrostatic images
US4005022A (en) * 1974-02-25 1977-01-25 Pitney-Bowes, Inc. Electrostatic liquid toners
US4093534A (en) * 1974-02-12 1978-06-06 Plessey Handel Und Investments Ag Working fluids for electrophoretic image display devices
US4202785A (en) * 1978-05-15 1980-05-13 Eastman Kodak Company Polyesterionomers having utility in liquid electrographic developer compositions
US4252921A (en) * 1979-10-03 1981-02-24 Eastman Kodak Company Polyesterionomers having utility in liquid electrographic developer compositions
WO1984001442A1 (en) * 1982-09-27 1984-04-12 Eastman Kodak Co A method for developing a latent electrostatic image

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3542681A (en) * 1968-07-10 1970-11-24 Gaf Corp Negative working electrostatic toners

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2877133A (en) * 1956-10-22 1959-03-10 Gen Dynamics Corp Electrostatic photography
US2891911A (en) * 1955-06-06 1959-06-23 Gen Dynamics Corp Developer for electrostatic printing
US2899335A (en) * 1956-10-31 1959-08-11 Process for developing electrostatic
US2907674A (en) * 1955-12-29 1959-10-06 Commw Of Australia Process for developing electrostatic image with liquid developer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2891911A (en) * 1955-06-06 1959-06-23 Gen Dynamics Corp Developer for electrostatic printing
US2907674A (en) * 1955-12-29 1959-10-06 Commw Of Australia Process for developing electrostatic image with liquid developer
US2877133A (en) * 1956-10-22 1959-03-10 Gen Dynamics Corp Electrostatic photography
US2899335A (en) * 1956-10-31 1959-08-11 Process for developing electrostatic

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3300410A (en) * 1961-03-13 1967-01-24 Australia Res Lab Conductive liquid developer for xerographic images
US3296140A (en) * 1964-02-13 1967-01-03 Dick Co Ab Liquid developer for electrographic printing
US3507794A (en) * 1964-12-22 1970-04-21 Harris Intertype Corp Electrostatic photography systems
US3549361A (en) * 1966-08-01 1970-12-22 Eastman Kodak Co Electrophotographic compositions and elements
US3878120A (en) * 1966-11-28 1975-04-15 Shinichiro Nagashima Process for preparing liquid developer for electrostatic images
US3640863A (en) * 1968-06-05 1972-02-08 Ricoh Kk A liquid electrostatic having pigment particles coated with a cyclized rubber
US3668127A (en) * 1968-07-01 1972-06-06 Ricoh Kk Liquid developer for electrophotography
US3779924A (en) * 1971-04-01 1973-12-18 Eastman Kodak Co Process for preparing electrophotographic liquid developing compositions
FR2192329A1 (en)van) * 1972-07-12 1974-02-08 Agfa Gevaert
US3833369A (en) * 1972-12-29 1974-09-03 Polaroid Corp Color diffusion transfer films and processes with polymer encapsulated reflecting agents
FR2235403A1 (en)van) * 1973-06-29 1975-01-24 Kalle Ag
US4093534A (en) * 1974-02-12 1978-06-06 Plessey Handel Und Investments Ag Working fluids for electrophoretic image display devices
US4005022A (en) * 1974-02-25 1977-01-25 Pitney-Bowes, Inc. Electrostatic liquid toners
US4202785A (en) * 1978-05-15 1980-05-13 Eastman Kodak Company Polyesterionomers having utility in liquid electrographic developer compositions
US4252921A (en) * 1979-10-03 1981-02-24 Eastman Kodak Company Polyesterionomers having utility in liquid electrographic developer compositions
WO1984001442A1 (en) * 1982-09-27 1984-04-12 Eastman Kodak Co A method for developing a latent electrostatic image
US4480022A (en) * 1982-09-27 1984-10-30 Eastman Kodak Company Method for forming a self-fixed image on a nonporous surface at ambient temperature

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Publication number Publication date
GB993150A (en) 1965-05-26
BE614048A (en)van)
DE1215524B (de) 1966-04-28

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