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
  • G03G9/125—Developers with toner particles in liquid developer mixtures characterised by the liquid
• • 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
  • G03G9/131—Developers with toner particles in liquid developer mixtures characterised by polymer components obtained by reactions only involving carbon-to-carbon unsaturated bonds

Definitions

• This invention relates to the production of copy by an electrostatic copy process and it relates more particularly to a liquid toner for use in the development of a latent electrostatic image.
• Liquid toners for use in the development of latent electrostatic images have been described in the issued Metcalfe et a1.
• patents No. 2,907,674 and No. 3,058,914 and in the copending application of Metropoulos et al., Ser. No. 205,690, filed June 27, 1962, now abandoned, and entitled Composition and Method for Developing Electrostatic Images.
• Such liquid toners have been found to be suitable for use in the development of latent electrostatic images formed by various means, such as by the Xerox process described by Dr. Carlson in Patent No.
• the liquid developer is formulated of a group of compatible materials which combine to form a liquid developing mixture and which may be subdivided into 1) a compatible carrier system formulated of the materials making up the toner in the absence of pigment for dilution of the pigment concentration in the developing liquid without noticeable effect on the viscosity, flow, stability or other characteristics of the liquid and (2) a compatible concentrate formulated of a high concentration of pigment for addition to the developing liquid to increase the pigment concentration without undesirable effect on the stability, viscosity, flow, or other desirable characteristics of the liquid thereby to provide a compatible system of components which can readily be adapted to meet the many variables within the copy process.
• the invention will be described first with reference to the formulation of the developing composition per se and thereafter with reference to the carrier composition and concentrate for preparation of the liquid developing composition and/or for the adjustment thereof to increase or decrease the pigment concentration and the like.
• the following example of the developing composition is given by way of illustration, but not by way of limitation:
• EXAMPLE 1 Grams Polystyrene resin (Piccolastic C125) 2 Aromatic solvent (aromatic petroleum fraction having a boiling point of 284-325 F., flash point F.) (Napoleon -AKerr McGee Oil Co.
• the nigrosine dye is ball milled in the second increment of the aliphatic solvent to reduce the pigment to a small particle size, such as to about 1-5 microns, and then the grind is dispersed in the solution containing polystyrene producing a relatively stable liquid developer.
• the nigrosine pigment particles Will assume a positive charge within the liquid and will thus be attracted to a latent electrostatic image having a negative electrostatic charge to provide a clean and precise development of copy.
• Polystyrene with or without plasticizers such as hydrogenated abietate, resinates, etc., is preferred as the resinous binder in the developing composition since polystyrene is characterized by extremely low solution viscosity such that wide variations in concentration can be effected without material change in the viscosity level and it imparts the desired charge to the particles.
• the polystyrene serves as a film former and binder to anchor the pigment particles to the copy sheet upon drying thereby to fix the image without the necessity for making use of heat, sola KB number of 39) 22.5
• the polystyrene is also a good film former to provide a protective coating over the face of the copy sheet and the image fixed thereon.
• polystyrene is present in an amount at least as great as 0.5 percent by weight in the developing composition but it is undesirable to exceed a concentration greater than 5 percent by weight and best results are secured when the polystyrene is present in an amount within the range of 1-3 percent by weight of the composition.
• the nigrosine is employed in the final liquid developer in an amount within the range of 0.05 to 0.6 percent by weight of the composition and preferably in an amount within the range of 0.2 to 0.5 percent by weight.
• Nigrosine is only representative of the various dyestuffs which may be employed since other dispersible dyestuffs which are insoluble in aliphatic or aromatic solvents can be employed in equivalent amounts.
• the coloring agent comprises a pigment formed of a dyestuif in a resinous base, the pigment may be as high as 5 percent by weight.
• EXAMPLE 2 Carrier Grams Polystyrene resin (Piccolastic C125) 1.5 Aromatic solvent (Napoleon 100-A) 27 Aliphatic solvent (Solvent No. 429) 18 Trichlorotrifiuoroethane 18 Trichloromonofluoromethane 36 Procedure Again, the resin is first dissolved in the aromatic solvent and then the remainder of the ingredients are added to form a pigmentless fluid which still contains the fixing resin so that dilution of the liquid developer with the carrier liquid to reduce the concentration of pigment or dyestuif will not operate correspondingly to reduce or dilute the amount of fixing resin or film former. As in the liquid developer or toner, the amount of resin in the carrier can be varied to within the range of 0.5 to 5 percent by weight and preferably within the range of 1-3 percent by weight.
• the nigrosine dye is first ground with the aliphatic solvent to a particle size of 1-5 microns.
• the polystyrene resin is separately dissolved in the aromatic solvent and the Freon and the two compositions are mixed together and given a final dispersion to form the concentrate.
• the nigrosine concentration is the important component in the concentrate and,
• nigrosine or other dispersible dyestuffs in an amount more than three times the pigment concentration in the liquid toner or more preferably an amount Within the range of 3-15 percent by weight of the concentrate composition.
• fiuorinated hydrocarbon solvents such as the Freons
• the fiuorinated hydrocarbon solvents are employed primarily for the purpose and in an amount sufficient to elevate the flash point of the composition to well over F. and to facilitate drying of the copy.
• fiuorinate-d or fiuorinated chlorinated hydrocarbons other than those set forth in the specific examples, may be employed and the amount can be varied in the solvent system-depending upon the fluorinated or fiuorinated chlorinated hydrocarbon, to give the desired increase in flash point and control in drying rate.
• aliphatic and aromatic hydrocarbon solvents can be freely substituted by other conventionally well known aliphatic and aromatic hydrocarbon solvents with boiling point ranges selected to achieve desired evaporation rates.
• Both the carrier and the concentrate are completely compatible one with the other in any desirable ratio with the liquid developer so that the dye concentration in the liquid developer can be easily adjusted or varied to raise the dye concentration by addition of concentrate orto lower the concentration by addition of carrier to provide optimum development conditions and to maintain the liquid developer at optimum dye concentration.
• Such additions of concentrate or carrier can be effected without noticeable change in the viscosity of the developer liquid to permit high loading at low viscosity.
• the optimum concentration of dyestufi in the liquid developer can be maintained by measured or substantially continuous additions of concentrate.
• loss of diluent by reason of slow or a low rate of development can be compensated without undesirable increase in dye concentration by measured or substantially continuous additions of carrier.
• a liquid developer composition for latent electrostatic images consisting essentially of a liquid solvent, a polystyrene resin present in the dissolved state in the liquid solvent in an amount within the range of 0.5 to 5.0 percent by weight of the composition, and a dye or pigment suspended in finely divided form in the polystyrene solution in an amount within the range of 0.05 to 0.6 percent by weight of the composition, and in which the liquid solvent consists essentially of substantial proportions each of an aliphatic petroleum solvent, an aromatic hydrocarbon solvent present in an amount sulficient to maintain the polystyrene in solution and a chlorinated-fiuorinated hydrocarbon solvent present in an amount suflicient to raise the flash point of the liquid solvent to above 100 F. and in which the aliphatic petroleum solvent and aromatic hydrocarbon solvent have boiling points which do not exceed about 349 F. and in which the liquid solvent has a flash point above 100 F.

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

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

Country Status (5)

Cited By (6)

Families Citing this family (1)

Citations (4)

• 1964
  • 1964-02-13 US US344555A patent/US3296140A/en not_active Expired - Lifetime
• 1965
  • 1965-02-08 FR FR4678A patent/FR1424154A/fr not_active Expired
  • 1965-02-09 BE BE659473A patent/BE659473A/xx unknown
  • 1965-02-12 NL NL6501756A patent/NL6501756A/xx unknown
  • 1965-02-15 GB GB6464/65A patent/GB1067303A/en not_active Expired

Patent Citations (4)

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