Classifications

• • 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
  • G03G13/08—Developing using a solid developer, e.g. powder developer
• • 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
  • G03G9/10—Developers with toner particles characterised by carrier particles
  • G03G9/103—Glass particles
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2991—Coated
  • Y10T428/2993—Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
  • Y10T428/2996—Glass particles or spheres
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2991—Coated
  • Y10T428/2998—Coated including synthetic resin or polymer

Definitions

• a xerographic carrier bead material for use in developing electrostatic latent images comprising a glass composition of from about 10 to about 40 parts oxides of silicon, from about 5 to about 50 parts oxides of barium, and oxides of metals selected from the group consisting of titanium, lead and mixtures thereof, all parts being based on a total of 100 parts by weight of the glass composition.
• This invention relates in general to an imaging system and, more particularly, to an electrostatographic material.
• Electrostatography is best exemplified by the process of xerography as first described in U.S. Pat. 2,297,691 to C. F. Carlson.
• a photoconductor is first provided with a uniform electrostatic charge over its surface and is then exposed to an image of activating electromagnetic radiation which selectively dissipates the charge in illuminated areas of the photoconductor while the charge in the non-illuminated areas is retained thereby forming a latent electrostatic image.
• This latent electrostatic latent image is then developed or made visible by the deposition of finely-divided electroscopic marking particles referred to in the art as toner.
• the toner will normally be attracted to those areas of the layer which retain a charge, thereby forming a toner image corresponding to the latent electroscopic image.
• This powdered image may then be transferred to a support surface such as paper.
• the transferred image may subsequently be permanently affixed to the support surface as by fusing.
• an image may be formed by directly charging the layer or an insulating member in image configuration.
• the powder image may be fixed to the imaging layer if elimination of the powder image transfer step is desired.
• Other suitable means such as solvent or overcoating treatment may be substituted for the foregoing heat fixing steps.
• the toner particles are electrostatically deposited and secured to the charged portion of a latent image and are not deposited on the uncharged or background portion of the image. Most of the toner particles accidentally deposited in the background areas are removed by the rolling carrier, due apparently to the greater electrostatic attraction between the toner and cairicr than between the toner and the discharged background. The carrier and excess toner are then recycled.
• the cascade technique is carried out in automatic machines.
• small buckets on an endless belt conveyor scoop the developer mixture comprising relatively large carrier beads and smaller toner particles and convey it to a point above an electrostatic image bearing surface where the developer mixture is allowed to fall and roll by gravity across the image bearing surface.
• the carrier beads along with any unused toner particles are then returned to the sump for recycling through the developing system.
• Small quantities of toner material are periodically added to the developer mixture to compensate for the toner depleted during the development process. This process is repeated for each copy produced in the machine and is ordinarily repeated many thousands of times during the usable life of the developer mixture.
• Coated carrier beads are subject to deterioration or degradation characterized by the separation of portions of or the entire carrier coating from the carrier core.
• the separation may be in the form of chips, flakes, or entire layers and is primarily caused by poorly adhering coating materials which fail upon impact and abrasive con tact with machine parts and other carrier particles.
• Carriers having coatings tend to chip and otherwise separate from the carrier core and must be frequently replaced, thereby increasing expense and consuming time.
• Print deletion and poor print quality occur when carrier particles having damaged coatings are not replaced. Fines and grit formed by the carrier coating disintegration tend to drift and form unwanted deposits on critical machine parts.
• the triboelectric properties of the carrier material varies with deterioration of the coating resulting in poor print quality.
• Uncoated carrier beads on the other hand have three main deficiencies. First, often they lack the weight required to insure against adherence of the granular carrier material to the charged plate. Desirably, the specific gravity of the carrier material should be between about 3 and about 8. Heavier carrier bead materials cause impact damage to the surface of the image bearing layer. Secondly, the prior art uncoated carrier materials lacked the triboelectric qualities required of an electrostatographic material. Problems encountered when carrier materials lack these properties are set out in the following discussion.
• the image density described in the immediately preceding sentence may be improved by increasing the toner concentration in the developer mixture, undesir- 3 ably high background toner deposition as well as increased toner impaction and agglomeration is encountered when the developer mixture is overtoned.
• the initial electrostatographic plate charge may be increased to improve the density of the deposited powdered image but the plate charge would ordinarily have to be excessively high in order to attract the electroscopic powder away from the carrier particle.
• Excessively high electrostatographic plate charges are not only undesirable because of the high power consumption necessary to maintain the electrostatographic plate at high potentials but also because a high potential causes the carrier particles to adhere to the electrostatographic plate surface rather than merely roll across and off the electrostatographic plate surface.
• the triboelectric value of a carrier material should not be significantly affected by ambient humidity conditions since such affect would destroy print quality at higher humidities and complicate machine design and operation, prior art uncoated glass materials were never commercially successful because of their great humidity sensitivity.
• an electrostatic latent image developing system wherein an electrostatic latent image is formed on an imaging surface and the electrostatic image is then contacted with a developer mixture comprising finely-divided particles of toner electrostatically adhering to the surface of uncoated glass carrier beads.
• the carrier beads in general, are a homogeneous mixture of a glass composition comprising from about 10 to about 40 parts oxides of silicon, from about 5 to about 50 parts oxides of barium, and oxides of metals selected from the group consisting of titanium, lead and mixtures thereof, all parts being based on a total of 100 parts by weight of the glass composition.
• a portion of the toner particles are attracted to and held on the surface of the image bearing member in accordance with the electrostatic latent image forming a visible image.
• the preferred composition comprises about 16 to 20 parts oxides of titanium, 4 to 6 parts oxides of barium, to 32 parts oxides of silicon, to 44 parts oxides of lead, and about 2 to 4 parts oxides of zirconium.
• the preferred composition comprises about 34 to 37 parts oxides of titanium, 43 to 48 parts oxides of barium, 11 to 13 parts oxides of silicon, and 3.5 to 4.5 parts oxides of calcium.
• the uncoated carrier beads of this invention have a specific gravity of from about 3.0 to about 6.0 and produce high quality images over a Wide range of ambient humidity conditions.
• a carrier bead diameter of from about 30 microns to about 1,000 microns is preferred for electrostatographic use because the bead then possesses sufficient inertia to avoid adherence to the latent electrostatic images.
• any suitable pigmented or dyed electroscopic toner material may be employed with the uncoated carriers of this invention.
• Typical toner materials include: gum copal; gum sandarac; rosin; cumaromeindene resin; asphaltum; uintaite; phenol formaldehyde resins; rosin modified phenol formaldehyde resins; methacrylic resins; polystyrene resins; polypropylene resins; epoxy resins; polyethylene resins and mixtures thereof.
• the particular toner material to be employed depends upon the separation of the toner particles from the treated carrier beads in the triboelectric series and whether a negatively or positively charged image is to be developed.
• the triboelectric values are determined as follows: The relative triboelectric values generated by contact of carrier beads with toner particles are measured by means of a Faraday cage.
• the device comprises a brass cylinder having a diameter of 1 inch and a length of 1 inch. A 100 mesh screen is positioned at each end of the cylinder. The cylinder is weighed, charged with 2 grams of a mixture of carrier and tofier particles and connected to ground through a capacitor and an electrometer connected in parallel. Dry compressed air is then blown through the brass cylinder to drive all the toner from the carrier. The charge on the capacitor is then read on the electrometer. Next, the chamber is reweighed to determine the weight loss.
• a toner comprising a styrene n-butyl methacrylate copolymer, polyvinylbutyral and carbon black produced by the method disclosed by M. A. Insalaco in Example I of US. Pat. 3,079,342 is used as a contact triboelectrification standard and as toner in all of the samples.
• suitable toners such as those listed above may be substituted for the toner used in the examples.
• a developer mixture is produced by mixing one part colored styrene copolymer toner particles having an average particle size of about to about microns with about 100 parts glass carrier bead particles having an average particle size of about 600 microns.
• the glass bead composition comprises about 71% SiO about 2% A1 0 about 13% CaO and about 14% Na O and has a specific gravity of about 2.4
• the following tests are run at an ambient temperature of about 70 F. and an ambient relative humidity of about
• the relative triboelectric value of the carrier measured by means of a Faraday cage is about 9 micro-coulombs per gram of toner.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred by electrostatic means to a sheet of paper whereon it is fused by heat.
• the resulting image is dense and substantially free of background toner deposits.
• EXAMPLE II The experiment of Example I is repeated except that the tests are performed in the presence of an ambient temperature of about 70 F. and an ambient relative.
• Example I The resulting fused image prepared as in Example I is characterized by a faded, washed out appearance and has high background toner deposits.
• EXAMPLE III A developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about 100 parts glass carrier bead particles having an average particle size of about 600 microns.
• the glass bead composition comprises about 71% SiO about 10% Na O, about 7% K 0, and about 12% PhD and has a specific gravity of about 2.8.
• the relative triboelectric value of the carrier measured by means of a Faraday cage is about 10 micro-coulombs per gram of toner.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred by electrostatic means to a sheet of paper whereon it is fused by heat.
• the resulting image is dense and is substantially free of background toner deposits.
• Example IV The experiment of Example III is repeated except that the tests are performed in the presence of an ambient temperature of about 70 F. and an ambient relative humidity of about
• the relative triboelectric value of carrier measured by means of a Faraday cage is about 4 micro-coulombs per gram of toner.
• the resulting fused image prepared as in Example II is dense but possesses a relatively high background toner deposition.
• EXAMPLE V A developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about 75 parts glass carrier bead particles having an average particle size of about 600 microns.
• the glass bead composition comprises about 50% SiO about 13% Na O, about 30% BaO and about 7% TiO and has a specific gravity of about 3.5.
• the relative triboelectric value of the carrier measured by means of a Faraday cage is about 4.8 micro-coulombs per gram of toner.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred to a sheet of paper whereon it is fused by heat.
• the resulting fused image is characterized by very high background and poor resolution.
• Example VI The experiment of Example V is repeated except that the tests fare performed in the presence of an ambient temperature of about 80 F. and an ambient relative humidity of about The resulting fused image prepared as in Example V is characterized by extremely poor resolution and very high background.
• EXAMPLE VII A developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about 150 parts glass carrier bead particles having an average particle size of about 400 microns.
• the glass bead composition comprises about 12% SiO about 1% NaO, about 4% CaO, about 1% B 0 about 45.5% BaO, and about 36.5% TiO and having a specific gravity of about 4.2.
• the relative triboelectric value of the carrier measured by means of a Faraday cage is about 19.2 micro-coulombs per gram of toner.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred to a sheet of paper whereon it is fused by heat.
• the resulting fused image has excellent resolution, excellent density and substantially no background.
• Example VIII The experiment of Example VII is repeated except that the images are produced in the presence of an ambient temperature of about 80 F. and an ambient relative humidity of about 85%.
• the resulting fused image prepared as in Example VII has excellent resolution, good density and substantially no background.
• EXAMPLE IX A developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about parts glass carrier bead particles having an average particle size of about 400 microns.
• the glass bead composition comprises about 46% BaO, about 20% TiO and about 34% SiO and has a specific gravity of about 4.5.
• the relative triboelectric value of the carrier measured by means of a Faraday cage is about 10.1 micro-coulombs per gram of toner.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred by electrostatic means to a sheet of paper whereon it is fused by heat.
• the resulting fused image is dense, has good resolution and substantially no background.
• Example IX The experiment of Example IX is repeated except that images are produced in the presence of an ambient temperature of about 80 F. and an ambient relative humidity of about 85%.
• the resulting fused image prepared as in Example IX is dense, has good resolution and substantially no background.
• EXAMPLE XI A developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about 100 parts glass carrier bead particles having an average particle size of about 400 microns.
• the glass bead composition comprises about 46% BaO, about 14% SiO about 33% Ti and about 7% ZrO and has a specific gravity of about 3.7.
• the following images are produced in the presence of an ambient temperature of about 70 F. and an ambient relative humidity of about 50%.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred by electrostatic means to a sheet of paper whereon it is fused by heat.
• the resulting fused image is dense, has good resolution and substantially no background.
• Example XII The experiment of Example XI is repeated except that images are produced in the presence of an ambient temperature of about 70 F. and an ambient relative humidity of about 85%.
• the resulting fused image prepared as in Example XI is dense, has good resolution and substantially no background.
• EXAMPLE XIII A developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about 60 parts glass carrier bead particles having an average particle size of about 600 microns.
• the glass bead composition comprises about 50% BaO, about SiO and about 25% TiO and has a specific gravity of about 4.3.
• the following images are produced in the presence of an ambient temperature of about 70 F. and an ambient relative humidity of about 50%.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred by electrostatic means to a sheet of paper whereon it is fused by heat.
• the resulting fused image is dense, has good resolution and substantially no background.
• Example XIV The experiment of Example XlIl is repeated except that the images are produced in the presence of an ambient temperature of about 70 F. and an ambient relative humidity of about 85%.
• the resulting fused image prepared as in Example XIII is dense, has good resolution and substantially no background.
• EXAMPLE XV A developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about 150 parts glass carrier bead particles having an average particle size of about 250 microns.
• the glass bead composition comprises about 32% SiO about 42% PbO, about 6% BaO, about 18% TiO and about 2% ZrO and has a specific gravity of about 5.2.
• the relative triboelectric value of the carrier measured by means of a Faraday cage is about 23.5 micro-coulombs per gram of toner.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred by electrostatic means to a sheet of paper whereon it is fused by heat.
• the resulting fused image is dense, has excellent resolution and substantially no background.
• Example XVI The experiment of Example XV is repeated except that images are produced in the presence of an ambient temperature of about 70 F. and an ambient relative humidity of about 85%.
• the resulting fused image prepared as in Example XV is dense, has excellent resolution and substantially no background.
• a developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about 100 parts glass carrier bead particles having an average particle size of about 400 microns.
• the glass bead composition comprises about 12% SiO about 45% PbO, about 25% BaO, and about 18% TiO and has a specific gravity of about 5.0.
• the following images are produced in the presence of an ambient temperature of about 70 F. and an ambient relative humidity of about
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferred by electrostatic means to a sheet of paper whereon it is fused by heat.
• the resulting fused image is dense, has good resolution and substantially no background.
• Example XVII The experiment of Example XVII is repeated except that images are produced in the presence of an ambient temperature of about F. and an ambient relative humidity of about
• the resulting fused image prepared as in Example XVII is dense, has good resolution and substantially no background.
• EXAMPLE XIX A developer mixture is produced by mixing one part colored styrene copolymer toner particles described in Example I with about parts glass carrier bead particles having an average particle size of about 400 microns.
• the glass bead composition comprises about 11% SiO about 0.5% NaO, about 3.5% CaO, about 48% BaO, about 36% TiO and about 1% B 0 and having a specific gravity of about 4.2.
• the relative triboelectric value of the carrier measured by means of a Faraday cage is about 19 micro-coulombs per gram of toner.
• the developer mixture is cascaded across an imaging surface bearing a positively charged electrostatic image.
• the resulting developed image is transferrd to a sheet of paper whereon it is fused by heat.
• the resulting fused image has good resolution, good density and substantially no background.
• Example XIX The experiment of Example XIX is repeated except that the images are produced in the presence of an ambient temperature of about 70 F. and an ambient relative humidity of about 85%.
• the resulting fused image prepared as in Example XIX has good resolution, good density and substantially no background.
• Example XIX The experiment of Example XIX is repeated except that the images are produced in the presence of an ambient temperature of about 90 F. and an ambient relative humidity of about 85%.
• the resulting fused image prepared as in vExample XIX has good resolution, good density and substantially no background.
• An electrostatographic developer mixture comprising finely-divided electroscopic toner particles having an average particle size less than about 30 microns electro statically adhering to the surface of substantially homogeneous glass carrier particles having an average particle size between about 30 microns and about 1000 microns, each of said toner particles comprising a resin and a colorant selected from the group consisting of dyes and pigments and each of said homogenous glass carrier particles having a specific gravity between about 3 and about 6 and consisting essentially of from about 10 percent to about 40 percent by weight of oxides of silicon, from about 4 percent to about 50 percent by weight of oxides of barium, from about 15 percent to about 40 percent by weight of oxides of titanium, less than about 45 percent by weight of oxides of lead, less than about 4.5 percent by weight of oxides of calcium and less than about 5 percent by weight of oxides of metals selected from the group consisting of sodium, potassium, lithium and mixtures thereof.
• glass carrier particles comprise from about 11 percent to about 13 percent by weight of oxides of silicon, from about 43 percent to about 48 percent by weight of oxides of barium, from about 34 percent to about 37 percent by weight of oxides of titanium, less than about 45 percent by Weight of oxides of lead, less than about 4.5 percent by weight of oxides of calcium, from about 0.5 percent to about 1.5 percent by weight of oxides of boron and less than about 5 percent by weight of oxides of metals selected from the group consisting of sodium, potassium, lithium and mixtures thereof.
• glass carrier particles comprise from about 30 percent to about 32 percent by Weight of oxides of silicon, from about 4 percent to about 6 percent by weight of oxides of barium, from about 16 percent to about 20 percent by weight of oxides of titanium, less than about 45 percent by weight of oxides of calcium, from about 2 percent from about 4 percent by weight of oxides of zirconium and less than about 5 percent by weight of oxides of metals selected from the group consisting of sodium, potassium, lithium and mixtures thereof.

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• Developing Agents For Electrophotography (AREA)

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• 1967
  • 1967-04-17 US US631192A patent/US3591503A/en not_active Expired - Lifetime
• 1968
  • 1968-04-16 LU LU55904D patent/LU55904A1/xx unknown
  • 1968-04-16 FR FR1560849D patent/FR1560849A/fr not_active Expired
  • 1968-04-16 NL NL6805319A patent/NL6805319A/xx unknown
  • 1968-04-16 DE DE19681772220 patent/DE1772220A1/de active Pending
  • 1968-04-16 CH CH556068A patent/CH508903A/de not_active IP Right Cessation
  • 1968-04-16 BE BE713751D patent/BE713751A/xx unknown
  • 1968-04-16 GB GB1225980D patent/GB1225980A/en not_active Expired
• 1970
  • 1970-11-30 US US00093847A patent/US3713819A/en not_active Expired - Lifetime

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