US3766072A - Edge and latitude developer - Google Patents

Edge and latitude developer Download PDF

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Publication number
US3766072A
US3766072A US00209858A US3766072DA US3766072A US 3766072 A US3766072 A US 3766072A US 00209858 A US00209858 A US 00209858A US 3766072D A US3766072D A US 3766072DA US 3766072 A US3766072 A US 3766072A
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United States
Prior art keywords
particles
conductive
developer
resin
insulating
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Expired - Lifetime
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US00209858A
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English (en)
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K Metcalfe
I Smith
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COMMONWEALTH OF AU AU
COMMW OF AU
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COMMW OF AU
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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
    • 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
    • G03G13/06—Developing
    • G03G13/10—Developing using a liquid developer, e.g. liquid suspension

Definitions

  • the developer contains at least two types of particles, one of which is an insulator and is preferably of finer size and the other of which is a more conductive particulate developer and preferably of coarser size with possibly a further particulate material which has one end insulating and the other relatively more conductive or polar whereby the more conductive particles tend to develop the edges of the image and the insulating particles the intermediate portions between the edges but wherein the insulator particles enable the relatively more conductive particles to be retained on a surface by a limiting charge transfer of the relatively more conductive particles to the surface containing the electrostatic image, and the third type of particle can rotate as a stirrer.
  • This invention relates to electrostatic printing and in particular to the development of electrostatic images by the deposition of particles from gases or liquid vehicles. It is now well known to develop electrostatic images by subjecting them to a body of gas or liquid containing suspended particles and to cause the particles to be attracted to the surface of the receiving sheet in image form.
  • Electrostatic images produced by X-ray or gamma ray means require continuous tone development while at the same time they require high contrast and sharp delineation of line images. These requirements are conflicting and require special development.
  • One object of the present invention therefore is to produce a developer which operates so as to give high contrast images where there are sharp changes of X-ray intensity such as occur for a sudden change of thickness, and also simultaneously give a very low contrast for slow changes of X-ray intensity.
  • a further object of the invention therefore is to allow control of development to allow this uniform development to take place if this is required.
  • Another object of the present invention is to prevent deposition of developer in background non-image areas.
  • chain forming particles may be used which comprise pigment-resin aggregates made by precipitating resins or the like in solvents of low solvent power for these resins and comprising particles of a range of particle sizes.
  • the aggregate size is controlled by the addition of a dispersant or solnbilizing substance which is more soluble than the first resin in said solvent of low solvent power and is designed to increase or reduce the size of the aggregates of the first resin because of its solubility for the first resin and its miscibility with the solvent or because of its wettability for the particles of the first resin.
  • FIG. 1 illustrates a series of tests made with both insulating and conductive materials and compound insulatorconductor materials when suspended in an insulating fluid and subjected to a unidirectional field
  • FIG. 2 shows diagrammatically how a sheet of photoconductive material bearing a latent electrostatic image can be developed to give for instance an edge effect
  • FIG. 3 shows a particle of developer showing how it can be coated to control the required action.
  • the particle could be conductive and the coating insulating, or vice versa.
  • an insulating liquid 1 was prepared which comprised a mixture of Freon 113 and Isopar H.
  • a piece of insulating material 2 was suspended between a pair of electrodes 3 and 4 so that it floated in the liquid.
  • An electric field in the range 1000 volts per inch to 10,000 volts per inch was applied and it was noted that the insulating piece migrated to one electrode and remained there as shown in A of FIG. 1.
  • a conductive piece 6 or a semiconductor piece In the second test we used a conductive piece 6 or a semiconductor piece and also we used insulating material coated over its whole surface with a layer of conductive material such as graphite, or wetted with a relatively conductive material such as water or glycerol triacetate.
  • a conductive piece will migrate to the electrode nearest to it at the time of application of the field and then dissipate its charge and then acquire the same polarity of charge as the electrode and be repelled by this electrode and will oscillate between the electrodes. This is shown in B of FIG. 1.
  • the insulating piece 7 is coated with conductive material on one side only and it is found that the piece will migrate to the nearest electrode with the conductive of high dielectric constant side turning to a foremost position. Contact of the conductive end with the electrode results in repulsion of the piece which then migrates to the op posite electrode, again turning over, and the process is repeated.
  • the period of oscillation in the case of pieces B and C of FIG. 1 can be varied by either insulating the particle or the electrode, the thickness of the insulation controlling the time it takes to reverse the charge on the insulator.
  • a thin insulator increases the speed of reversal of direction of migration of the particle and thus where normally a conductive piece would oscillate, it is found that by inserting a thin insulating film between it and the electrode which it is approaching, results in delay in sharing of charge with the electrode and consequently, delay in repulsion.
  • a similar insulating piece coated with a layer of semiconductive material migrates backwards and forwards in a similar way to the conductive piece but is characterized in that it pauses in oscillation after arrival at each electrode as if an insulating barrier existed on the electrode.
  • insulator particles can be more readily retained on a charged surface and will continue to build up according to charge level. Conductive particles will however migrate onto and then off the surface but the rate can be controlled by an insulating film.
  • Such an insulator film could be built up on the image by fine insulator particles in the developer to then allow large conductive or semiconductive particles to be retained due to these particles then being prevented from rapidly transferring charges they have acquired.
  • Conductive particles are more strongly attracted to a field of sutficient intensity but have a quicker charge transfer and leave the area quicker if the field strength is increased.
  • Non-conductive particles move slower in the field but when they deposit, provided the field is strong enough, they are held in place.
  • ions or migrating particles of substantially different size and polarizability are injected into the system, for example by adding iodine, metal naphthenates or other chain forming compounds which constrict the field, there is a signicant change in the type and velocity of migration of the particles or pieces, conductive pieces tend to remain stationary, insulating pieces tend to migrate to one electrode and stay there, pieces with regularly arranged surface spots of conductive coating also tend to remain stationary whereas pieces with conductive coatings predominantly on one end rotate in a stationary position. This is shown in D in FIG. 1.
  • the aggregate is obtained by precipitating a resin from solution in a good solvent by putting this solution into a poor solvent.
  • a resin for example if the resin is dissolved in an aromatic hydrocarbon, precipitation is obtained by injecting the solution into an aliphatic hydrocarbon containing various percentages of aromatic hydrocarbon for example from zero to 50% and it is found that the aggregate size increases with lower aromatic content until total precipitation occurs, depending on the type of resin.
  • the solubility of the solvent for the resin and hence the aggregate size may be refined by means of other resins and solubilizing agents which have an aflinity for both the final resin and also the solvent.
  • Pigmentation or coloration of the aggregates is achieved by incorporating a pigment or dye in the original resin solution prior to precipitation.
  • the fine material necessary for development of small charges or fields is obtained either by parting of particles from aggregates or clusters or by separate additions to the concentrated developer of fine particle size material.
  • a developer concentrate is prepared by first dissolving a relatively soluble resin such as Solprene 1205 in an aromatic hydrocarbon solvent such as Esso and also a relatively insoluble resin such as V.T.A.C. (vinyl toluene acrylic copolymer) in a similar solvent and milling these together with a colorant such as Microlith Black CT and a small proportion of Microlith Blue.
  • the proportions of the Solprene 1205 in relation to the V.T.A.C. may for example be 3 parts of Solprene to 2 parts of V.T.A.C. by weight, and the proportions of pigment to those of the total resin may for example be 1 part of pigment to 1 part of resin by weight.
  • a typical formulation is as follows:
  • the developer concentrate made in this way is then dispersed in an aliphatic hydrocarbon solvent such as Isopar G with vigorous stirring to form aggregates of particles in the proportions of 1 gram in 100 milliliters. It will be clear that as the amount of concentrate is increased in initial proportion to the carrier liquid that changes will occur in aggregate size because of increasing solvent power of the total liquid.
  • the preferred range is 0.5 to 2 grams per 100 milliliters.
  • the styrene butadiene resin is a solvent for the V.T.A.C. resin and these-co-deposit in the Esso solvent as a fine developer of insulating particles.
  • the Microlith Black pigment has relatively conductive particles and the Microlith Blue somewhat poorer conductive particles.
  • the insulating resin particles do not Wet the conductive particles but co-exist in the insulating carrier liquid so that the conditions illustrated in MG. 2 are present and short term development of a latent image tends to accentuate edgeeifects as the larger conductive particles tend to build up quicker in the stronger edge fields but as development continues the conductive particles deposited on the insulator particles at the originally weaker field give lateral spread to develop more on the basis of the voltage gradient shown.
  • a vessel 8 has in it the insulating carrier liquid 9 and a photoconductive sheet is shown on which is a latent image indicated by the voltage gradient line 11.
  • the fieldgradient is shown by the dotted line 12.
  • the particle of FIG. 3 is designated 13, and has on it a film 14.
  • Elvacite 2010 resin 4 The Solprene resin is the solvent for the Elvacite resin.
  • Both of these are relatively conductive but are lightly coated and thus are partly insulated.
  • EXAMPLE 3 A developer concentrate is prepared as in Example 1 but the pigment is replaced by Coates Hydrocarbon dispersible flake black. This pigment is more conductive than the pigments of Example 1.
  • EXAMPLE 4 A developer concentrate is prepared as in Example 2 but the Elvacite (methyl methacrylate) resin is replaced by a Melamine resin. This is even more insoluble than the Elvacite resin and thus results in coarser insulating particles.
  • EXAMPLE 5 A developer concentrate is prepared as in Example 1 but the Solprene 1205 resin is replaced'by Pliolite SSD (Goodyear Corp., U.S.A.). This again results in grain coarseningbecause it is a poorer solvent for the other resin.
  • EXAMPLE 6 i A developer concentrate suitable for use in Isopar G or E carrier liquidsis prepared from the following materials:
  • IDENTIFICATION OF TRADEMARKS AND TRADE NAMES Solprene 1205 is a block copolymer of butadiene and styrene in the ratio of 75/25 manufactured by a solution of polymerization process by Phillips Corp., U.S.A., A.S.T.M. No. 1205, characterized in that the majority of the styrene molecules are added as polystyrene at the end of a long chain of butadiene units.
  • Pliolite VT Resin is a styrene/butadiene type copolymer rubber made by the Goodyear Corp., U.S.A. and prepared by the G.R.S. method in which the butadiene polymerizes in the main by a 1,4-addition.
  • Pliolite VT is a vinyl toluene/butadiene random copolymer rubber, soluble in mineral spirits.
  • Pliolite SSD is a styrene/butadiene copolymer, KB value 60, manufactured by Goodyear Corp., U.S.A.
  • Pliolite V.T.A.C. is a vinyl toluene/acrylate copolymer, KB value 36.
  • Esso 100 Solvent is a hydrocarbon solvent supplied by Esso Chemicals Australia Limited, having an aromatic content of 98%, flash point of 108 F., and distillation range 159182 C.
  • Microlith Pigments comprise a pigment and a resinous carrier.
  • Microlith Black pigment contains pure neutral carbon black together with a toluene soluble carrier resin such as Stabilite Ester 10 of the Hercules Powder C0., U.S.A.
  • Microlith Blue 4GT comprises a stable phthalocyanine blue pigment with a greenish cast together with Stabilite Ester 10 resin.
  • Microlith Green GT comprises a medium shade of phthalocyanine green together with Stabilite Ester l0 resin, the microlith pigments are manufactured by Ciba C0., Switzerland.
  • Microlith Blue-Color Index No. 74160 Microlith Green-Color Index No. 72455 Elvacite Resin referred to in Examples 2 and 4 is an acrylic resin manufactured by Du Pont, Delaware, U.S.A.
  • Coates hydrocarbon dispersible flake black comprises pure carbon black together with ethyl hydroxy cellulose resin.
  • a developer for developing electrostatic images on a surface comprising a carrier liquid medium having an electrical resistivity sutficiently high to prevent destruction of a latent electrostatic image during development, developer particles suspended in said carrier liquid medium and including at least two types of particles, the first of said two types being insulator particles and having an inherent charge but being electrical insulators unable to exchange charges with the surface during development and the second of said type types being relatively more conductive polar particles whereby charges can be exchanged with a latent image bearing surface, the insulator particles adhering to a surface having an appropriate image field polarity without repulsion because of the inability to transfer charges, the relatively more conductive polar particles acquiring the image field polarity and exchanging charges with the surface to accept the surface image charged to be repulsed thereby by acquired similar charge characteristics unless insulated from the surface by attracted insulator particles, said insulator particles being smaller than the more conductive polar particles whereby the insulator particles tend to deposit on lower image charge areas, the more conductive polar particles tending to deposit with
  • a developer according to claim 1 including ions or migrating particles of substantially different size and polarizability selected from the group consisting of iodine, metal naphthanates and metal octoates in the developer to reduce the velocity of migration of the developer particles.
  • a developer according to claim 1 including added insulating particles, having one side conductive comprising aggregated resin which has been initially dissolved in a polar or relatively conductive solvent, and including ions or migrating particles of substantially dilferent size and polarizability selected from the group consisting of iodine, metal naphthanates and metal octoates in the de- 8 veloper to cause the added insulating particles to rotate within the developer carrier fluid.
  • the insulator particles comprise pigment particles coated with a block copolymer of butadiene and styrene in the ratio of about percent butadiene and 25 percent styrene, the styrene molecules being in the form of polystyrene at the end of long chain butadiene units.
  • a developer according to claim 1 wherein the insulator particles comprise pigment particles coated with a styrene/butadiene copolymer.
  • a developer according to claim 1 wherein the insulator particles comprise pigment particles coated with a vinyl toluene/acrylate copolymer.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Liquid Developers In Electrophotography (AREA)
US00209858A 1968-12-30 1971-12-20 Edge and latitude developer Expired - Lifetime US3766072A (en)

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Application Number Priority Date Filing Date Title
AU48482/68A AU425595B2 (en) 1968-12-30 1968-12-30 Edge and latitude developer

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US3766072A true US3766072A (en) 1973-10-16

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US (1) US3766072A (fr)
AU (1) AU425595B2 (fr)
BE (1) BE743883A (fr)
CA (1) CA918985A (fr)
DE (1) DE1965362C3 (fr)
FR (1) FR2027343A1 (fr)
GB (1) GB1296999A (fr)
NL (1) NL6919431A (fr)
SE (1) SE359174B (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3915874A (en) * 1972-07-27 1975-10-28 Ricoh Kk Liquid developer for use in electrophotographic transfer process
US3998746A (en) * 1973-11-05 1976-12-21 Canon Kabushiki Kaisha Liquid developer comprising heat treated rubber for use in development of an electrostatic latent image and method of making developer
US4049446A (en) * 1972-10-04 1977-09-20 Metcalfe Kenneth A Energized liquid developers for developing electrostatic images
DE3231687A1 (de) * 1981-09-01 1983-03-17 Savin Corp., 10595 Valhalla, N.Y. Entwickler fuer latente ladungsbilder
US4469770A (en) * 1982-12-27 1984-09-04 Xerox Corporation Styrene butadiene plasticizer toner composition blends
US4582774A (en) * 1981-04-03 1986-04-15 Savin Corporation Liquid developing latent electrostatic images and gap transfer
US4789616A (en) * 1987-11-09 1988-12-06 Xerox Corporation Processes for liquid developer compositions with high transfer efficiencies
US4797341A (en) * 1985-09-10 1989-01-10 Ricoh Co., Ltd. Liquid developer for electrophotography
WO1997012288A1 (fr) * 1995-09-29 1997-04-03 Minnesota Mining And Manufacturing Company Procede de production d'images multicolores dans un systeme electrophotographique et appareil correspondant
WO2021022024A1 (fr) * 2019-08-01 2021-02-04 University Of Massachusetts Mélange imprimable, fabrication et utilisation

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5414926B2 (fr) * 1972-03-11 1979-06-11
CA1000099A (en) * 1972-10-04 1976-11-23 Denton Field Energised liquid developers for developing electrostatic images
DE2642826C3 (de) * 1976-09-23 1982-03-11 Philip A. Hunt Chemical Corp., Palisades Park, N.J. Elektrostatographischer Suspensionsentwickler
US4830945A (en) * 1988-05-23 1989-05-16 Xerox Corporation Liquid electrophotographic developer comprising oppositely charged toner particles and dyes of different colors
US4877698A (en) * 1988-05-23 1989-10-31 Xerox Corporation Electrophotographic process for generating two-color images using liquid developer

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3915874A (en) * 1972-07-27 1975-10-28 Ricoh Kk Liquid developer for use in electrophotographic transfer process
US4049446A (en) * 1972-10-04 1977-09-20 Metcalfe Kenneth A Energized liquid developers for developing electrostatic images
US3998746A (en) * 1973-11-05 1976-12-21 Canon Kabushiki Kaisha Liquid developer comprising heat treated rubber for use in development of an electrostatic latent image and method of making developer
US4582774A (en) * 1981-04-03 1986-04-15 Savin Corporation Liquid developing latent electrostatic images and gap transfer
DE3231687A1 (de) * 1981-09-01 1983-03-17 Savin Corp., 10595 Valhalla, N.Y. Entwickler fuer latente ladungsbilder
US4413048A (en) * 1981-09-01 1983-11-01 Savin Corporation Developing composition for a latent electrostatic image for transfer of the developed image across a gap to a carrier sheet
US4469770A (en) * 1982-12-27 1984-09-04 Xerox Corporation Styrene butadiene plasticizer toner composition blends
US4797341A (en) * 1985-09-10 1989-01-10 Ricoh Co., Ltd. Liquid developer for electrophotography
US4789616A (en) * 1987-11-09 1988-12-06 Xerox Corporation Processes for liquid developer compositions with high transfer efficiencies
WO1997012288A1 (fr) * 1995-09-29 1997-04-03 Minnesota Mining And Manufacturing Company Procede de production d'images multicolores dans un systeme electrophotographique et appareil correspondant
US5916718A (en) * 1995-09-29 1999-06-29 Imation Corp. Method and apparatus for producing a multi-colored image in an electrophotographic system
WO2021022024A1 (fr) * 2019-08-01 2021-02-04 University Of Massachusetts Mélange imprimable, fabrication et utilisation

Also Published As

Publication number Publication date
NL6919431A (fr) 1970-07-02
CA918985A (en) 1973-01-16
AU4848268A (en) 1971-06-17
AU425595B2 (en) 1972-06-29
BE743883A (fr) 1970-05-28
DE1965362C3 (de) 1979-03-01
FR2027343A1 (fr) 1970-09-25
DE1965362A1 (de) 1970-07-16
GB1296999A (fr) 1972-11-22
DE1965362B2 (de) 1978-06-22
SE359174B (fr) 1973-08-20

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