Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F292/00—Macromolecular compounds obtained by polymerising monomers on to inorganic materials
• • 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
  • G03G9/133—Graft-or block polymers

Definitions

• ABSTRACT A liquid developer for use in electrophotography, comprising 30] Foreign A li ti Priority Data a copolymerically grafted pigment toner dispersed in a carrier liquid consisting of a paraffinic or an isoparaffinic hydrocar- May 15, Japan bon having a high-elec[ ic resistance and a w-dielec[ric onstant, said toner being prepared by subjecting the particles of [52] US. Cl...
• the present invention is concerned with a liquid developer which is used in the wet development of electrophotographs.
• a liquid developer for use in electrophotography is prepared by first kneading a mixture of particles of a pigment, a resin, a fat, a surface active agent, a stabilizer or like materials which, individually, are capable of either regulating the polarity of the particles of the pigment, dispersing the particles uniformly in a solvent or imparting to the particles the property of adhering to the electrophotographic copying papers, and then dispersing the kneaded mixture in an or ganic solvent.
• the liquid developer is operative in sucha way, in practice, that the polarity of the particles of the pigment contained in the developer is kept under a regulated state, by being impressed with either a positive or a negative charge.
• Such a liquid developer for use in electrophotography as described above is required to possess the following properties:
• the particles of pigment must be satisfactorily dispersed in the carrier liquid
• the particles must have an interfacial potential which is sufficient for generating electrophoresis
• Such a liquid developer of the prior art showed, for some time after it was manufactured, a satisfactory dispersion of pigment particles and also a distinct polarity of the particles, because, during this initial period, the polarity regulating agent as well as other agents were maintained in their state of being relatively firmly absorbed onto the surfaces of the pigment particles. With the passage of time, however, these agents which had been absorbed onto the surfaces of the pigment particles gradually became released therefrom, causing deterioration of the dispersability of the particles and the property of effecting a satisfactory polarity regulation of these particles. For this reason, it was extremely difficult to preserve, for an extended period of time, as excellent developability of the liquid developer which it possessed at the time the developer was manufactured.
• This liquid developer was prepared by dispersing, in an organic carrier liquid, a toner obtained from a graft copolymerization of two kinds of unsaturated compounds performed on the pigment particles. More particularly, this liquid developer is prepared by dispersing, in an organic solvent either directly or together with a surface active agent, a toner which is made by subjecting the particles of one kind of pigment to a graft copolymerization with two kinds of unsaturated compounds.
• the present invention has been discovered as a result of further research we conducted on the aforesaid improved liquid developer.
• a novel liquid developer for use in electrophotography which has, in particular, an ability to keep a stable polarity for an extended period of time and also an ability to cause a spectacular adhesion of the pigment particles onto the surface of the copying paper when the latter is developed, and which further permits the user to freely perform the regulation of the polarity of the pigment particles contained in the carrier liquid and to freely control the color tone of the copied image which is developed.
• the liquid developer is prepared by dispersing in 1. a dispersing medium consisting of either a paraffinic or an isoparaffinic hydrocarbon having a relatively high electric resistance and a relatively low dielectric constant,
• a toner consisting of the particles ofa multiple-copolymer which is obtained from a graft copolymerization of at least three kinds of unsaturated polymeric compounds which are expressed by the general formula (a) and also by the general formula (b) as mentioned below and the particles of at least two kinds of pigments.
• a toner consisting of a so-called graft copolymer which is obtained from the graft copolymerization of the following materials,
• the polar radical represented by X in the aforesaid general formulas (a) and (b) by which the unsaturated compounds used in the present invention are expressed works very effectively on the particles of the toner in the liquid developer to regulate the polarity of the particles.
• the polar radical represented by Y is selected from those having an increased affinity toward the particle-dispersing medium consisting of a paraffinic or an isoparaffinic hydrocarbon. Therefore, the object of obtaining uniform dispersion of the toner in the dispersing medium is attained.
• These polar radicals which are represented by X and Y serve to enhance the adhesion of the toner onto the copying papers used.
• the toner contain both types of the compounds which are expressed by the aforesaid general formulas (a) and (b) and that at least three kinds of these compounds be copolymerically grafted onto the particles of the pigments.
• the desirable range of proportions of the amount of the unsaturated compounds to the amount of the pigments to which the compounds are to be united is from 0.5 to 5 parts by weight of the compounds to 1 part by weight of the pigments.
• a liquid developer in which i. a toner, which is prepared by having the particles of at least two kinds of pigments which have been so arranged to produce a desired color tone of the copied image graftcopolymerized directly, by a chemical procedure, with unsaturated compounds which are capable of contributing to the stable regulation of the polarity of the particles of the pigments, the uniform dispersion of the particles and the good adhesion of the particles onto the copying papers, is dispersed in 2 a carrier liquid consisting of a paraffinic or an isoparaffinic hydrocarbon.
• the liquid developer of the present invention preserves a good and satisfactory developing ability for a long time.
• the toner thus obtained was added to an isoparaffinic hydrocarbon (ISOPAR-H, a product of ESSO Standard Oil, inc.) and the mixture was kneaded in a ball mill for 3 hours. Then, l gram of the kneaded mixture was dispersed in 500 cc. of lSOPAR-H, and as a result, a liquid developer for use in electrophotography having a toner with a polarity regulated to be positive was obtained.
• ISOPAR-H isoparaffinic hydrocarbon
• an electrophotographic copying paper which had been impressed with a negative charge by corona discharge was exposed to light through a positive original laid thereon to form an electrostatic latent image (meaning that the areas of the photoconductive layer of the copying paper corresponding to the original image were impressed with a negative charge).
• This copying paper carrying a latent image was immersed in the liquid developer of the present invention obtained according to the procedure described above, with the result that a very clear positive copy of the image was obtained. Also, the same liquid developer was used repeatedly over an extended period of time, but no deterioration of the developing ability was noted.
• the copied image obtained by the use of the liquid developer of the present invention has a markedly increased initial density of the image and the image showed a negligible fading of the color at the end of storage for a long time.
• EXAMPLE 2 Eighteen moles of octyl methacrylate, 1 mole of dimethylaminoethyl methacrylate, 3 moles of hydroxyethyl methacrylate and 0.005 mole of azobisisobutylonitrile were dissolved in 6.5 moles of toluene. into this mixture were added Carbon Black (Condatex SC, a product of Columbia Carbon Black Company of U.S.A.) in an amount of one-third of the total amount by weight of the aforesaid unsaturated compounds and also Aniline Black in an amount of one-fifth of the total amount by weight of the unsaturated compounds. The resulting mixture was subjected to a reaction at 90 C.
• Carbon Black Condatex SC, a product of Columbia Carbon Black Company of U.S.A.
• EXAMPLE 3 Eighteen moles of lauryl methacrylate, 2 moles of dimethylaminoethyl methacrylate, 1 mole of acrylonitrile and 0.004 mole of azobisisobutylonitrile were dissolved in 6.0 moles of toluene. lnto this mixture were added Carbon Black (Mogul A, a product of Cabot, Company of U.S.A.) in an amount of one-third of the total amount by weight of the aforesaid unsaturated compounds and also Dry Alkali Blue in an amount of one-tenth of the total amount by weight of said unsaturated compounds. The resulting mixture was allowed to react at 80 C.
• Carbon Black Mogul A, a product of Cabot, Company of U.S.A.
• the toner thus prepared was added to an equal amount of ISOPAR-H, and the mixture was kneaded in a ball mill for 3 hours. then, 1 gram ofthis kneaded mixture was dispersed in 500 cc. of ISOPAR-H, and thus a liquid developer containing a toner with its polarity having been regulated to be negative was obtained.
• a liquid developer for electrophotography comprising a toner made by graft-polymerizing a reaction mixture comprismg 1.
• two pigment materials each pigment material selected from the group consisting of Carbon Black (C.l. No. 77266), Aniline Black (C.l. No. 50440), Alkaline Blue (C.l. No. 42563), Spirit Black (C.l. No. 50415), Phthalo cyanine Dyes (C.l. No. 74250), Violet R (Cl. No.
• R is selected from the group consisting of o en. anqfitflyt iw a x ad sah whsrsin rn said toner being dispersed incarrier liquid having a high electric resistance and a low dielectric constant, said carrier liquid being selected from the group consisting of parafi'inic hydrocarbons and isoparaffinic hydrocarbons.

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• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Materials Engineering (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Liquid Developers In Electrophotography (AREA)

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Publications (1)

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Cited By (12)

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Citations (4)

• 1968
  • 1968-05-08 US US727651A patent/US3639244A/en not_active Expired - Lifetime
  • 1968-05-14 BE BE715106D patent/BE715106A/xx unknown
  • 1968-05-15 DE DE19681772439 patent/DE1772439B2/de active Granted

Patent Citations (4)

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