Classifications

• • 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
  • G03G9/13—Developers with toner particles in liquid developer mixtures characterised by polymer components
  • G03G9/132—Developers with toner particles in liquid developer mixtures characterised by polymer components obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
  • Y10S430/105—Polymer in developer

Definitions

• a liquid developer for latent electrostatic images is disclosed wherein the clumping together of pigment particles from larger aggregates is avoided by including a resin that is soluble in the carrier liquid and is selected to be a wetting agent for the pigment particles which thereby coats said particles.
• T his invention relates to an improved liquid developer for electrostatic images.
• a fixing medium for such toner particles such for instance as a resin or similar material which is in a dissolved or softened state and which deposits with the toner particles or as a coating on the toner particles to fix the image on evaporation of the carrier liquid.
• the objects have been achieved according to our invention by suspending pigment particles in the developer carrier liquid and to also carry in this developer liquid a resin which is so selected that there is only a very low attraction between the developer particles and the resin, with the result that only a thin coating of resin can adhere to the developer particles, the bulk of the resin remaining in solution in the carrier liquid and acting as a means to cause the particles to remain in an isolated condition without undue tendency of sedimentation or agglomeration.
• the invention thus consists of a liquid developer of the type utilizing pigment particles suspended in a carrier liquid having relatively high electrical insulating properties, which carrier liquid also supports a resin, characterized in that the particles have a diameter of not greater than one micron and are insoluble in the carrier liquid, and in that the resin is soluble in the carrier liquid and is selected to be a wetting agent for the particles which, however, coats the particles so thinly that the normal particle charge in the carrier liquid is substantially unaltered, and in that the resin is present in such a quantity in relation to the particles that there are approximately six parts of resin to one part by weight of pigment but wherein only about two percent of the said resin in relation to the weight of the pigment is capable of being held on to the pigment. Because of this the pigment particles are forced apart to deposit independently when subjected to an electrostatic field.
• the resin acts as a dispersing agent which enables the pigment particles to remain in suspension for long periods without settlement or change of physical properties.
• the quantity of the resin must be suflicient to satisfy the surface of the toner particles but to leave most of it in solution in the carrier liquid, the amount of resin which is over in relation to the carrier liquid serving in part to provide more adequate fixing and in part to control the sensitivity and speed of the developer because normally the resin will have a lower volume resistivity than the carrier liquid, so that when more free resin is present in the solution the overall resistivity of the liquid component of the developer will be lowered with consequent faster destruction of the electrostatic image and thus with a change in the contrast of the image which is developed.
• Irgalite is the trade mark of Geige for a phthalocyanine blue pigment.
• Shellite is the trade mark of the Shell Company for a hydro-carbon solvent of relatively high electrical resistivity.
• the developer has an ionization current of 1.9 microamperes at 10 kv. which is equal to 0.076 microamperes per square centimetre at 4 kv. per centimetre.
• EXAMPLE II 10 grams of Irgalite Fast Brilliant Blue was mixed with 60 grams of Paralac 10 in the presence of 40 grams of xylol and the concentrate was bar milled and then dispersed by placing 2 grams of the concentrate into 250 grams of mineral turpentine.
• Paralac 10 is the trade mark of Imperial Chemical Industries for a long oil linseed oil modified alkyd resin, oil length 72%.
• This developer again had a positive polarity with good stability and fixing properties and excellent fill-in.
• the ionization current was found to be 0.51 microamperes at 10 kv. and the ionization current density is 0.0204 microamperes per centimetre at 4 kv. per centimetre field.
• the ionization current was found to be 2.1 microamperes at 10 kv. which equals an ionization current density of 0.084 microamperes per square centimetre at a field of 4 kv. per cubic centimetre.
• An improved liquid developer consisting essentially of pigment particles and a carrier liquid, said pigment particles being suspended in said carrier liquid, said liquid having relatively high electrical insulating properties, and a resin in said carrier liquid and having an oil length of not less than about and being substantially fully polymerized, the pigment particles having a di ameter of not greater than one micron and being insoluble in the carrier liquid, the resin being soluble in the carrier liquid, there being approximately six parts of resin to one part of pigment by weight, the said resin being a wetting agent for the pigment particles and being such that only about two percent of the said resin in relation to the weight of the pigment is held to the pigment, whereby the pigment particles are forced apart to deposit independently when subjected to an electrostatic field.
• a method for preparing an improved liquid developer comprising mixing about 10 grams of pigment with about 40 to 60 grams of a modified alkyd resin having an oil length of not less than about 60% and adding suf ficient solvent to allow milling to form a concentrate, effecting said milling to form said concentrate, and suspending two parts of the said concentrate in about grams of an electrically insulating hydrocarbon carrier liquid which is also a solvent for the resin.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Liquid Developers In Electrophotography (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=3709301

Family Applications (1)

Country Status (5)

Cited By (2)

Citations (2)

• 0
  • NL NL295272D patent/NL295272A/xx unknown
  • GB GB1054554D patent/GB1054554A/en active Active
  • BE BE634860D patent/BE634860A/xx unknown
• 1963
  • 1963-07-05 DE DE19631472912 patent/DE1472912B2/de active Pending
  • 1963-07-09 US US293853A patent/US3516934A/en not_active Expired - Lifetime

Patent Citations (2)

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