US3639245A - Developer power of thermoplastic special particles having conductive particles radially dispersed therein - Google Patents

Developer power of thermoplastic special particles having conductive particles radially dispersed therein Download PDF

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Publication number
US3639245A
US3639245A US746691A US3639245DA US3639245A US 3639245 A US3639245 A US 3639245A US 746691 A US746691 A US 746691A US 3639245D A US3639245D A US 3639245DA US 3639245 A US3639245 A US 3639245A
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United States
Prior art keywords
particles
powder
conductivity
mho
developer
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US746691A
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English (en)
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Robert B Nelson
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3M Co
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Minnesota Mining and Manufacturing Co
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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
    • G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
    • 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
    • G03G9/0802—Preparation methods
    • G03G9/0808—Preparation methods by dry mixing the toner components in solid or softened state
    • 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
    • G03G9/0821—Developers with toner particles characterised by physical parameters
    • G03G9/0823—Electric parameters
    • 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
    • G03G9/0825—Developers with toner particles characterised by their structure; characterised by non-homogenuous distribution of components
    • 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
    • G03G9/0827—Developers with toner particles characterised by their shape, e.g. degree of sphericity
    • 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
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/104—One component toner

Definitions

  • ABSTRACT Flowable, heat fusible, dry powder suitable for use as a developer powder in electrographic recording which comprises thermoplastic, essentially spherical particles, the thermoplastic material of which has a conductivity of at most 10' mho/cm., in which are essentially completely embedded electrically conductive particles forming a radially disposed zone, said essentially spherical particles having:
  • This invention relates to a dry ink powder suitable for use in electrographic recording and a process for making such powder.
  • this invention relates to a developer powder having a good electrical conductivity in the presence of a relatively large impressed electric field, and low electrical conductivity (and hence good charge retention characteristics for the charge remaining on it) in the absence of this high impressed field.
  • this invention relates to dry developer particles for electrophotography which are magnetizable.
  • this invention relates to a developer powder which has a pressure dependent conductivity, being more conductive under the influence of an impressed magnetic field during development, and less conductive (and hence having better individual charge retention characteristics) in the absence of this impressed magnetic field.
  • Electrostatic electrophotography originally employed two component dry ink powders, often called triboelectric mixtures," for charge development of the electrostatic image. Recently dry powders in which all of the particles are of the same composition have been described.
  • the relatively conductive dry inks of U.S. Pat. No. 3,116,510 (Jan. 19, 1965; Charles P. West and Jacques Benveniste) contain thermoplastic resin particles in which about 35 to 55 percent of the total particle weight is carbon black dispersed throughout the resin particles.
  • U.S. Pat. No. 3,196,032 (July 20, 1965; David W. Seymour) an electrostatic printing ink having carbon powder partially embedded in or adhered to the surface of resin particles is prepared in a fluid bed reactor.
  • an exposed photoconductive sheet is contacted with conductive developer powder applied from a conductive surface, to which it is adhered, while creating a differential electrical field between the photoconductive sheet (i.e., field electrode) and the conductive surface containing the developer powder.
  • the developer powder is transferred selectively to the photoconductive sheet in the nonexposed areas. Separation of the photoconductive sheet from the source of supply of developer powder is made while still maintaining the influence of the electrical field, and provision can be made for continuing the attraction of the developer powder to the surface of the photoconductive sheet after such separation.
  • the developer powder in this process is electronically conductive, usually having a conductivity of at least l mho per centimeter (ohm"cm.' preferably to 10' mho per centimeter, at the applied electrical field (preferably at least 1,000 DC volts per centimeter).
  • Conductivity measurements are made with the developer powder compressed into a 1-centimeter cube between brass electrodes fitted in a rigid chamber, a pressure of 86 pounds per square inch (6.05 kg. per cm?) being applied across the sample before and during the measurement of conductance. If the developer powder is subsequently to be transferred from the photoconductive sheet to a receptor surface, it should also have electrical charge retention capability, to retain the electrical charge imparted to the developer particles by the applied electrical field during the development of the pattern on the field electrode.
  • the high conductivity of the developer particles desired to minimize voltage drop across them when they are in the electrical field, and the ability ofthe developer particles to retain the electrical charge, which characterizes high resistivity particles, are difficult to achieve satisfactorily, since one desirable characteristic is generally sacrificed to obtain the other.
  • the FIGURE is a plot of electrical conductivity vs. DC ap- I plied electrical field for developer particles of this invention.
  • the developer powders of this invention comprise thermoplastic, essentially spherical particles (i.e., spherules), the thermoplastic material of which has a conductivity of at most 10-" mho/cm, preferably at most 10" mho/cm, in which are essentially completely embedded electrically conductive particles forming a radially disposed layer or zone, said essentially spherical particleshaving an electronic conductivity which ranges monatonically without decreasing from between about 10' and about 10" mho/cm. (preferably between 10' and 10 mho/cm.) in a 100 v./cm. DC electrical field to between 10 and about 10' mho/cm.
  • dry ink powders are flowable to such an extent that they have a flowability angle of repose ranging from about to 125 and preferably from 1 10 to 125.
  • flowability is measured by feeding a thin stream of powder to the upper flat surface of a 3-inch diameter circular pedestal from a vibrating funnel, thereby creating a conical deposit of powder on the pedestal.
  • the angle of repose is defined by the angle measured between opposite sides of the conical deposit, i.e., the apex angle of the cone, at 25 C.
  • the dry ink powders of this invention and the thermoplastic materials used therein are preferably heat fusible in the range of 80 to 1 15 C., preferably from to 105 C.
  • the Durrans Mercury method as reported in SMS] 14 is employed.
  • Any heat fusible thermoplastic material having a conductivity of at most 10' mho/cm. may be used to form the spherules, although thermoplastic organic polymers are preferred.
  • suitable resins include B-stage (i.e., partially cured) phenol aldehyde polymers, polyvinyl acetate, epoxy resins, etc.
  • any highly electrically conductive material i.e., a material having a conductivity of at least 10 mho/cm., such as conductive carbon, metal, etc.
  • a material having a conductivity of at least 10 mho/cm. such as conductive carbon, metal, etc.
  • the electrically conductive particles may be used in powdered form as the electrically conductive particles forming the conductive zone of the dry ink particles, provided the resulting electrically conductive particles have an average diameter below millimicrons, preferably under 40 millimicrons.
  • Conductive carbon particles e.g., those available under the trade name Vulcan XC-72R, sold by Cabot-Corporation are preferred.
  • the amount of conductive material in the embeddedzone of the dry ink particle, the type of conductive material used, the particle size of the embedded conductive particles, and the location of the embedded zone can influence the conductivity of the dry ink powder.
  • the volume ratio of electrically conductive material to the total particle volume in the ink powder can be in the range of 001/100 to 4.0/100, although 0.1/100 to 1.5/100 is preferred.
  • the embedded zone of conductive particles is normally quite close to the surface of the ink particle and is preferably not thicker than one-tenth the radius of the essentially spherical developer particle. Although essentially all of the conductive particles are embedded, an occasional particle may protrude from the surface.
  • the conductivity of these developer particles is field dependent," i.e., the conductivity under high electrical fields differs from the conductivity under low electrical fields.
  • the electrical conductivity of the developer particles is a monatonically, nondecreasing function of the applied DC electrical field. It is preferred that the slope of the conductivity vs. applied electrical field curve also increases monatonically with the applied electrical field. This has been found to be extremely valuable for developer powders used in the process of French Pat. No.
  • Example E used the resin of Example A.
  • the resin of Example E was Epon 1002" (epichlorohy rin/blsphcnol A solid epoxy resin, melting olnt 75-85/C., cpoxlde equivalent 01600400, molecular weight of 1060, a trademarked product of Shell Chemica Company). 1
  • the size distribution data are percent by number greater than indicated sizes, which are in microns. For example in sample A, 96% of all the particles are larger than 3.7 50% are greater than 6.4 and 6% are greater than 12.6
  • CAB-O-SIL a trademarked product of Cabot Corporation.
  • Various other materials may be usefully incorporated in or on the developer particles of this invention, c.g., plasticizers, dyestuffs, pigments, magnetically permeable particles, etc.
  • Magnetically permeable particles having an average diameter of 1 micron or less are particularly preferred, including magnctite, barium ferrite, nickel zinc ferrite, chromium oxide, nickel oxide, etc.
  • a magnetically permeable core may also be used.
  • Powdered flow agents may also be added to the dry particles to improve their flow characteristics.
  • the conductivity of these dry ink powders is related to the applied electric field across the powder particles, and measurement of conductivity is therefore made under standard conditions of sample size, sample compression and applied electric field. The following test procedure is used for the conductivity measurements presented herein.
  • the sample of ink is placed in a test cell between two brass electrodes of circular cross section, each with a cross-scctional area of about 0.073 cm.”
  • An insulating cylindrical sleeve of polytetrafluoroethylene surrounds the ink and electrodes such that the ink sample is constrained to the shape ofa small pill box.
  • At least one of the electrodes is free to move like a piston in the insulating sleeve to provide a predetermined comprcssion on the sample.
  • the compression is obtained by placing a known weight on the movable electrode,
  • the voltage cannot be applied to the sample for longer than a fraction of a second or so, before considerable heat develops in the sample, changing its characteristics, or causing it to break down" entirely.
  • the applied voltage is rapidly in- 25 creased from about 0 to 2,000 v. or more (corresponding to 3 cial, high voltage ramp (or sweep) generator.
  • the current meter described earlier is replaced by a current-sampling resistor, typically of about 10,000 ohms. The voltage across this sampling resistor, as monitored by an oscilloscope,
  • the dry ink powder conductivity should be such that at high applied electric fields, it permits a relatively large current flow the development electrode to the intermediate photoconductivc imagcable surface during the development step, which is carried out with a relatively large series voltage impressed.
  • the powder should not be so conductive that after one layer is deposited on the intermediate photoconductive imageable surface it thereafter electrically shiclds subsequent layers of powder from the intermediate surface, accepting their charge but preventing their deposition as would happen with a highly conductive powder.
  • the conductivity should be considerably smaller so the powder which was deposited on the intermediate photoconductive imagcable surface retains its charge for a time period sufficient to permit transfer of the powder from the intermediate surface to a receptor sheet.
  • the electric field holding the powder to the intermediate surface in areas where it is deposited is still relatively strong, but the nature of the interface in these areas is insulating enough to prevent the charge to flow from the powder into the intermediate itself.
  • the lateral electric field from particle to particle is very small or zero, so the charge on the deposited particles does not leak laterally to the more conductive areas on the intermediate surrounding the deposited powder.
  • the electric field from layer to layer of deposited powder is smallaftcrdcvclopment, so the charge do es not readily leak from layers more rcmotcfrom thc intermediate surface to the' layers more adjacent to said surface. Thus all deposited particles remain strongly bound to the intermediate and retain their charge for a time.
  • a dry-powdered blend of appropriate composition is first obtained by any of several standard means, for example, by melting a resin, stirring in the solid filler, if any, allowing the mixture to cool, then grinding and classifying to the appropriate particle size range of approximately 1 to microns diameter.
  • This powder which is pseudocubical in shape is then spheroidized" by the following method: the powder is aspirated into a moving gas stream, preferably air, thus creating an aerosol.
  • This aerosol is directed at about 90 (:5") through a stream of hot air, which has been heated to about 900-1,l00 F., into a cooling chamber, where the powder is then allowed to settle by gravity while it cools.
  • the resulting powder is now made up of substantially spherical particles. It is then dry blended with conductive powder, such as conductive carbon black, and the mixture is directed at about 90 (i5) through a stream of gas, preferably air, heated to a temperature (e.g., 700800 F.) which can at least soften and desirably melt the thermoplastic resin in the particles and maintain that softened or melted condition for a period of time sufficient to permit the conductive powder to become essentially completely embedded, due to the effects of surface tension.
  • the particles are then collected, such as by cyclone separation, and are preferably blended with a flow agent, such as CAB-O-SIL (finely divided silica, a trademarked product of Cabot Corporation) to insure that it will be free flowing.
  • a flow agent such as CAB-O-SIL (finely divided silica, a trademarked product of Cabot Corporation) to insure that it will be free flowing.
  • the conductive material may be deposited, as a powder or as a continuous film, on the surface of the essentially spherical particles, and a thin film ofinsulative material, e.g., a resin, may be superimposed or deposited thereon to ef fectively embed the conductive material as a zone in the parti+ cles.
  • a thin film ofinsulative material e.g., a resin
  • the following procedure represents a preferred method for manufacturing the dry ink powder.
  • EXAMPLE A Four parts by weight of Epon 1004" (epichlorohydrin/bi sphenol A solid epoxy resin, melting point 95-105 C., epoxide equivalent of ENS-1,025, molecular weight of 1,400, a trademarked product of Shell Chemical Company) and 6 parts by weight of magnetite were blended thoroughly on a conventional heated-roll rubber mill. The resulting material was pulverized in an attrition-type grinder and was then classified in a standard air-centrifugal-type machine, the yield from which was about percent by weight in the desired particle size distribution range. Particle size analysis of the product showed it to be about 95% 1 .3u, 50% 4.1,u, 5% l2.6 .1r% (by number).
  • the final step in the process was to blend 0.1 percent by weight of a small particle size SiO flow agent to cause the powder to become sufficiently free flowing for use in the electropowder process.
  • This ink was coded A, and the conductivity vs. applied electrical field curve is shown in the FIGURE.
  • Table I shows the properties obtained when several other formulations (B-F) were prepared by the method given in the above example, and the conductivity vs. applied electrical field curves are presented in the FIGURE.
  • the two dotted lines in the FIGURE represented the upper and lower limits of conductivity over the range of applied DC electrical fields, as mentioned earlier.
  • thermoplastic, essentially spherical particles suitable for use as a developer powder in electrographic recording which comprises thermoplastic, essentially spherical particles, the thermoplastic material of which has a conductivity of at most 10 mho/cm., in which are essentially completely embedded electrically conductive particles having a conductivity of at least 10 mho/cm. and an average diameter below about 100 millimicrons forming a radially disposed zone, said essentially spherical particles having:
  • thermoplastic material is an organic resin

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Developing Agents For Electrophotography (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)
US746691A 1968-07-22 1968-07-22 Developer power of thermoplastic special particles having conductive particles radially dispersed therein Expired - Lifetime US3639245A (en)

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JP (1) JPS5840182B1 (nl)
AT (1) AT307871B (nl)
BE (1) BE736353A (nl)
BR (1) BR6910891D0 (nl)
CH (1) CH526136A (nl)
DE (1) DE1937651C3 (nl)
DK (1) DK130938B (nl)
ES (1) ES369454A1 (nl)
FR (1) FR2013449A1 (nl)
GB (1) GB1282017A (nl)
NL (2) NL159795B (nl)
SE (1) SE346632B (nl)

Cited By (86)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2313132A1 (de) * 1972-03-16 1973-09-20 Oce Van Der Grinten Nv Elektrofotografisches verfahren
JPS4917739A (nl) * 1972-04-10 1974-02-16
FR2235404A1 (nl) * 1973-06-29 1975-01-24 Minnesota Mining & Mfg
JPS5020729A (nl) * 1973-06-22 1975-03-05
US3909258A (en) * 1972-03-15 1975-09-30 Minnesota Mining & Mfg Electrographic development process
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US5032485A (en) * 1978-07-28 1991-07-16 Canon Kabushiki Kaisha Developing method for one-component developer
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US5153616A (en) * 1990-03-08 1992-10-06 Hitachi Metals, Ltd. Method for recording images
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US5202211A (en) * 1990-02-05 1993-04-13 Oce-Nederland B.V. Toner powder comprising particles having a coating of fluorine-doped tin oxide particles
US5350659A (en) * 1993-03-31 1994-09-27 Xerox Corporation Preparation of conductive toners using fluidized bed processing equipment
US5358811A (en) * 1988-12-27 1994-10-25 Canon Kabushiki Kaisha Electrophotographic method using an amorphous silicon light receiving member with a latent image support layer and a developed image support layer and insulating toner having a volume average particle size of 4.5 to 9.0 micron
US5385768A (en) * 1990-06-14 1995-01-31 Diafoil Company, Limited Electrically conductive film
US5457001A (en) * 1993-07-26 1995-10-10 Oce'-Nederland, B.V. Electrically conductive toner powder
US6594462B2 (en) * 2000-03-15 2003-07-15 Canon Kabushiki Kaisha Developing apparatus using toner with conductive particles
US10571832B2 (en) * 2017-03-17 2020-02-25 Ricoh Company, Ltd. Intermediate transferor, method of making the same, and image forming apparatus using the same

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JPS5359430A (en) * 1976-06-09 1978-05-29 Konishiroku Photo Ind Co Ltd Electrostatic latent image developer
JPS5443029A (en) * 1977-09-10 1979-04-05 Ricoh Co Ltd Pressure fixing toner
JPS54139545A (en) * 1978-04-10 1979-10-30 Hitachi Metals Ltd Magnetic toner
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JPS5585426A (en) * 1978-12-21 1980-06-27 Tdk Corp Magnetic powder for toner or ink and production thereof
GB2088076A (en) * 1980-10-13 1982-06-03 Ricoh Kk Electrophotographic Developing and Transfer Process
JP2612568B2 (ja) * 1986-03-07 1997-05-21 東洋インキ製造株式会社 電子写真用トナー
JPS6319663A (ja) * 1986-07-14 1988-01-27 Kao Corp 球状トナ−粒子
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JPS4917739A (nl) * 1972-04-10 1974-02-16
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JPS5321656B2 (nl) * 1973-06-22 1978-07-04
JPS5020729A (nl) * 1973-06-22 1975-03-05
FR2235404A1 (nl) * 1973-06-29 1975-01-24 Minnesota Mining & Mfg
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JPS5140137A (nl) * 1974-10-01 1976-04-03 Mita Industrial Co Ltd
JPS5823622B2 (ja) * 1974-10-01 1983-05-16 京セラミタ株式会社 静電写真用磁性トナ−の製法
JPS5180235A (nl) * 1975-01-09 1976-07-13 Ricoh Kk
JPS5196331A (nl) * 1975-02-21 1976-08-24
JPS5347172B2 (nl) * 1975-02-21 1978-12-19
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JPS5347178B2 (nl) * 1976-02-16 1978-12-19
JPS5298530A (en) * 1976-02-16 1977-08-18 Hitachi Metals Ltd Magnetic toner
JPS5857103B2 (ja) * 1976-02-28 1983-12-19 株式会社リコー 乾式現像剤粉末
JPS52104929A (en) * 1976-02-28 1977-09-02 Ricoh Co Ltd Dry developing agent powder
JPS5438505B2 (nl) * 1976-05-24 1979-11-21
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US4265992A (en) * 1977-08-05 1981-05-05 Mita Industrial Company Limited Coated magnetic developer particles for electrophotography containing vinyl and olefin resins
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US5032485A (en) * 1978-07-28 1991-07-16 Canon Kabushiki Kaisha Developing method for one-component developer
US5096798A (en) * 1978-07-28 1992-03-17 Canon Kabushiki Kaisha Developing method for one-component developer
US5194359A (en) * 1978-07-28 1993-03-16 Canon Kabushiki Kaisha Developing method for one component developer
US4514484A (en) * 1978-09-12 1985-04-30 Compagnie Internationale Pour L'informatique Cii/Honeywell Bull (Societe Anonyme) Powder for developing latent images and a method of producing the powder
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US5202211A (en) * 1990-02-05 1993-04-13 Oce-Nederland B.V. Toner powder comprising particles having a coating of fluorine-doped tin oxide particles
US5153616A (en) * 1990-03-08 1992-10-06 Hitachi Metals, Ltd. Method for recording images
US5385768A (en) * 1990-06-14 1995-01-31 Diafoil Company, Limited Electrically conductive film
US5350659A (en) * 1993-03-31 1994-09-27 Xerox Corporation Preparation of conductive toners using fluidized bed processing equipment
US5457001A (en) * 1993-07-26 1995-10-10 Oce'-Nederland, B.V. Electrically conductive toner powder
US6594462B2 (en) * 2000-03-15 2003-07-15 Canon Kabushiki Kaisha Developing apparatus using toner with conductive particles
US10571832B2 (en) * 2017-03-17 2020-02-25 Ricoh Company, Ltd. Intermediate transferor, method of making the same, and image forming apparatus using the same

Also Published As

Publication number Publication date
BE736353A (nl) 1970-01-22
DE1937651A1 (de) 1970-02-19
CH526136A (de) 1972-07-31
JPS5840182B1 (nl) 1983-09-03
DE1937651C3 (de) 1981-04-30
SE346632B (nl) 1972-07-10
NL159795C (nl)
FR2013449A1 (nl) 1970-04-03
NL6910676A (nl) 1970-01-26
DK130938B (da) 1975-05-05
ES369454A1 (es) 1971-06-01
BR6910891D0 (pt) 1973-01-25
DK130938C (nl) 1975-10-06
GB1282017A (en) 1972-07-19
NL159795B (nl) 1979-03-15
DE1937651B2 (de) 1971-10-14
AT307871B (de) 1973-06-12

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