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
  • G03G9/09—Colouring agents for toner particles
  • G03G9/0906—Organic dyes
  • G03G9/091—Azo dyes

Definitions

• This specification describes an invention relating to a toner resin composition and a toner composition, containing a cobalt- complex of an azo dye as a charge control agent (CCA), suitable for use in electro-reprographic processes.
• CCA charge control agent
• 2:1 chromium complexes of azo dyes are the most important class of metal complex dyes (see The Chemistry of Synthetic Dyes (Venkataraman), Vol III, Chap VII, "The Chemistry of Metal Complex Dyes” by R.Price & The Colours Index, 3rd Edition), one of the main reasons for their importance being their high stability compared with analogous complexes of azo dyes with other metals, such as cobalt.
• Typical commercial charge control agents of this type are CI Acid Black 63 (the 2:1 complex of chromium with 1-(2-hydroxy-4-nitrophenylazo)-2-hydroxy-naphthalene), the 2:1 complex of chromium with 1-(2-hydroxy-5-sulphonamidophenylazo)-2-hydroxynaphthalene and the 2:1 complex of chromium with 1-(2-hydroxy-5-chlorophenylazo)-2-hydroxynaphthalene.
• a toner resin composition comprising a toner resin and a cobalt complex azo compound of the formula: wherein M (+) is a cation
• the cation, M (+) may be any suitable monovalent cation, such as an alkali metal, e.g. lithium, sodium or potassium, or an optionally substituted ammonium ion, e.g. NH 4 + , (CH 3 ) 3 NH + or (CH 3 ) 4 N + but is preferably a proton, H + .
• an alkali metal e.g. lithium, sodium or potassium
• an optionally substituted ammonium ion e.g. NH 4 + , (CH 3 ) 3 NH + or (CH 3 ) 4 N + but is preferably a proton, H + .
• the halo group represented by X or Y is preferably chloro.
• the alkyl, alkoxy, alkenyl or phenyl group represented by X, Y, Z, R or R 1 is preferably unsubstituted but the phenyl group may carry one or more non-ionic substituents, such as C 1-4 -alkyl, C 1-4 -alkoxy, halo or cyano.
• the group represented by Y is preferably in one of the two positions between X and and the oxy group attached to the cobalt, i.e. in the meta or para position relative to the azo link but, more preferably, Y is meta with respect to X and with respect to the azo link.
• X is chloro or -SO 2 NH 2 and Y is H or chloro.
• the toner resin is a thermoplastic resin suitable for use in the preparation of toner compositions, a preferred resin being a styrene or substituted styrene polymer or co-polymer, especially a styrene-acrylic co-polymer, such as polystyrene and styrene-butadiene or styrene-butyl methacrylate co-polymers.
• Other suitable resins are polyesters, especially propoxylated bis-phenol-based polyester resins, polyvinyl acetate, polyalkenes, poly(vinyl) chloride, polyurethanes, polyamides, silicones, epoxy resins, phenolics etc. Further examples of these and other resins are given in the book "Electrophotography" by R.M.Schaffert (Focal Press), UK 2,090,008A, USP 4,206,064 and USP 4,407,924.
• the toner resin.composition may contain, as charge control agent (CCA), more than one compound of Formula I, for example, the CCA may comprise a mixture of the compounds of Formula I in which M & Y are H & X is -S0 2 NH 2 and M & Y are H and X is chloro.
• CCA charge control agent
• the composition desirably contains, in total, from 0.1% to 12%, preferably from 0.5% to 10% and conveniently around 2.5%, by weight, of CCA.
• the toner resin composition is conveniently prepared by known methods, i.e. by kneading the molten resin with the CCA, at a temperature of 100°C or above, generally 150-200°C for several hours so that the latter becomes dispersed throughout the resin.
• a toner composition comprising a resin composition as hereinbefore defined and a colorant.
• the colorant is preferably a pigment which is dispersed evenly throughout the resin phase.
• suitable colorants are carbon black, phthalocyanines, metallised lakes & toners, and various azo and anthraquinone pigments.
• the toner composition preferably contains not more than 20% by weight, and more preferably from 3% to 10%, of colorant.
• the toner composition may be prepared by dispersing the finely-divided colorant into a dispersion of the CCA in the resin by kneading above the melting point of the resin, conveniently around 150°C for several hours so that the pigment becomes distributed throughout the resin.
• the toner resin may be mixed with the CCA and the colorant and the three components kneaded together for several hours as before. The resin is then cooled, crushed and micronised until the mean diameter of resin particles is below 20 ⁇ m and, for high resolution printing, more preferably from 1 to 10 ⁇ m.
• the CCA may be conveniently prepared by (i) diazotising an amine of the formula: wherein X and Y are as hereinbefore defined.
• the resin and toner compositions in accordance with the present invention have particularly well adapted for use in electro-reprographic processes on account of the good dispersibility of the CCA and the high charge capacity of the toner composition.
• the superior qualities of the compositions give rise to improved copy quality.
• a resin composition was prepared by kneading at 150°C for 30 minutes a mixture of 20g of a styrene-acrylic resin (HIMER TB1000) and 0.5g parts of CCA A. The resin composition was then cooled to room temperature. This resin composition is hereinafter referred to as RC 1.
• Resin compositions were prepared by the method of Example 1 using each of CCA B to CCA G described above, the Example numbers following the alphabetical order of the CCA. These compositions are hereinafter referred to as RC 2 to 7 respectively.
• the resin composition of Example 1 was converted into a toner composition by kneading 93 parts of the resin composition with 7 parts of carbon black, (ELFTEX 415) at 160°C or 3 hours, cooling and grinding the composition until the mean diameter of the particles was ⁇ 20 ⁇ m.
• This toner composition is hereinafter referred to as TC 7.
• Toner compositions were prepared by the method of Example 8 using the resin compositions described in Examples 2 to 7. These toner compositions are hereinafter referred to as TC 9 to 14 respectively.
• each of RC 1, RC 2 and RC 3 weas melted by heating to 150°C and a thin layer formed on a microscope slide. On cooling to room temperature the slide was examined under a microscope at a magnification of 200x.
• the particles of CCa were evenly distributed throughout the resin in the form of small spheres having a mean diameter of 3 - 5 ⁇ m, with no particles or aggregates greater than 10 ⁇ m.

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• General Physics & Mathematics (AREA)
• Developing Agents For Electrophotography (AREA)

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Citations (2)

• 1985
  • 1985-05-08 EP EP85303263A patent/EP0162632A3/fr not_active Withdrawn

Patent Citations (2)

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