EP0479875B1 - Composition de toner electrostatographique sec - Google Patents

Composition de toner electrostatographique sec Download PDF

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Publication number
EP0479875B1
EP0479875B1 EP90910656A EP90910656A EP0479875B1 EP 0479875 B1 EP0479875 B1 EP 0479875B1 EP 90910656 A EP90910656 A EP 90910656A EP 90910656 A EP90910656 A EP 90910656A EP 0479875 B1 EP0479875 B1 EP 0479875B1
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EP
European Patent Office
Prior art keywords
toner particles
toner
particle size
volume
percent
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EP90910656A
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German (de)
English (en)
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EP0479875A1 (fr
Inventor
Serge Martin Tavernier
Robert Frans Janssens
Leo Bernard Alaerts
Hans Karl Van Cauwenberghe
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Agfa Gevaert NV
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Agfa Gevaert NV
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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
    • G03G9/0821—Developers with toner particles characterised by physical parameters
    • 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
    • G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
    • 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
    • G03G9/097—Plasticisers; Charge controlling agents
    • 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
    • G03G9/097—Plasticisers; Charge controlling agents
    • G03G9/09708—Inorganic compounds
    • G03G9/09716—Inorganic compounds treated with organic compounds

Definitions

  • the present invention relates to a toner composition consisting of fusible electrostatically attractable toner particles suitable for development of electrostatic charge patterns.
  • electrostatic latent image corresponding to either the original to be copied, or corresponding to the digitized data describing an electronically available image, on a photoconductive member.
  • the electrostatic latent image is formed by imagewise discharge over styli towards a dielectric substrate.
  • the xeroprinting process such as disclosed e.g. in European Patent Application 0 243 934 involves imagewise exposing a photopolymer master, charging on a conductive support, toning with dry or liquid toner and transferring to another substrate.
  • Electrostatic latent images can be developed using a liquid developer consisting of a colloidal system of charged colloidal particles in an insulating liquid.
  • the latent image is developed with a finely divided developing material or toner to form a powder image which is then transferred onto a support sheet such as paper.
  • the support sheet bearing the toner powder image is subsequently passed through a fusing apparatus and is thereafter discharged out of the copying resp. printing machine as a final copy, resp. final print.
  • a latent electrostatographic image is formed on a suitable member, e.g. a photoconductive drum, secondly this latent image is developed to form a visually discernible image and transferred in a transfer station to a final hard copy.
  • a suitable member e.g. a photoconductive drum
  • One of the objectives set forth for the overall electrostatographic process is to provide an image on the final copy, resp. final print with the best possible quality.
  • Quality consequently comprises features such as uniform darkness of the image areas, background quality, clear delineation of lines, as well as overall resolution of the image.
  • the 'quality' and more in particular the resolution of the latent electrostatographic image is determined by the accuracy of each of the following steps : first the conversion of the digitized data describing the electronically available image to an appropriate illumination pattern, secondly the illumination of the photoconductive drum by the laser or light emitting diode system; thirdly the resolving power of the photoconductive process present on the photoconductive drum.
  • the quality of the latent electrostatic image is determined by the contact exposure step.
  • the 'quality' of the latent electrostatographic image is predominantly determined by the accuracy of illumination of the photoconductive drum by the electro-optical system, whereby the optical quality of the mirrors, lenses, optical fibres, etc. used, as well as the solidity, sturdiness and lack of vibrations of the construction play a vital role.
  • the first stage of the overall electrostatographic process i.e. the illumination of the photoconductive drum
  • the first stage of the overall electrostatographic process is in most cases, where the necessary care has been taken in respect of overall construction of the device, not a limiting factor in respect of the overall attainable resolution of the xerographic print.
  • the critical factor in respect of the overall image quality is the second stage of the electrophotographic process, i.e. the conversion of the latent image into a visually discernible image.
  • the overall accuracy by which the latent electrostatographic image, formed in either an electronic printing or copying apparatus, is developed into a visually discernable copy is predominantly determined by the characteristics of the developer used.
  • toner materials are claimed with a particle size distribution wherein less than about 30 % percent by number of the toner particles have an average particle size diameter of less than about 5 microns, about 25 % by number of the particles have a diameter between about 8 microns and about 12 microns, and less than about 5 % by number of the toner particles have an average particle diameter greater than about 20 microns.
  • less than about 10 % by number of the toner particles have an average particle diameter of less than about 5 microns, about 60 % by number of the toner particles have an average particle diameter of between about 8 and about 12 microns, and less than about 5 % by number of the toner particles have an average particle diameter greater than about 20 microns.
  • toner particles are claimed according to a size distribution wherein less than 15% by weight are greater than 16 microns, between 7 and 15 % by weight are less than 5 microns, the remainder being from 5 to 16 microns and wherein the median particle size by weight is from 8 to 12 microns.
  • liquid developer compositions with toner particles having average or median particle sizes as fine as 0.25 microns are known for producing very high resolution electrostatic prints.
  • flocculation can be prevented by optimizing the colloidal forces.
  • Liquid developer compositions suitable for use in developing electrostatic charge patterns are disclosed e.g. in U.S. Patents 4,123,374 and 4,138,351 both assigned to Agfa-Gevaert N.V., Mortsel, Belgium.
  • Liquid developers however exhibit an important drawback : the dielectric solvent carried along with the toner and simultaneously deposited to the electrostatographic print should be evaporated and consequently recycled or disposed of in the atmosphere so as to obtain a dry final print.
  • an electrostatographic apparatus employing a liquid developer consequently entails much inconvenience for the customer.
  • U.K. Patent Application GB 2,180,94B discloses the use of toner particles of size not more than 5 microns. By the use of such small toner particles the resolution of the image has been 10 lines/mm while it is 5 lines/mm when the particle size of the toner is approximately 10 microns.
  • a lubricant e.g. zinc stearate, should be added in an amount of at least 0.5 wt%.
  • European Patent 0 255 716 discloses a process for the manufacture of fine toner particles having a uniform spherical particle form. According to said application the volume average particle size by a Coulter Counter method is from 1.0 to 7.0 micron and the number average particle size is from 1.0 to 5.0 micron.
  • toner particles are manufactured according to a complex suspension polymerization process.
  • United States Patent 4,737,433 discloses an electrostatographic process wherein toner particles having an average diameter less than 10 micron are used. In this application it is said that fundamental difficulties arise when trying to transfer toner particles having an average diameter less than 10 micron from the image bearing member to the paper support in the electrostatographic transfer station, and suitable remedies are proposed.
  • electrostatographic toner particles comprising classified toner particles having a particle size distribution wherein
  • more than 90 % by volume of the toner particles have equivalent particle size diameters larger than 0.5 micron and less than 6 micron, and more than about 50 percent by volume of the toner particles have equivalent particle size diameters of less than about 4 microns.
  • more than 90 % by volume of the toner particles have equivalent particle size diameters larger than 0.5 micron and less than 5 micron, and more than about 50 percent by volume of the toner particles have equivalent particle size diameters of less than about 3 microns.
  • the toner particles are admixed with fine inorganic microparticles, which are coated with hydrophobic groups containing entities, resulting in a methanol value larger than 20.
  • a preferred embodiment comprises toner with admixed fine inorganic microparticles, having a specific surface no larger than 150 m 2/g.
  • the toner compositions suitable for use in accordance with the present invention should be prepared by selecting and modifying some of the known toner mixing and comminution techniques. As is generally known toner is prepared by subsequently blending and mixing the components in the molten state and after cooling, milling and micropulverizing the resulting mixture. Thereafter so as to obtain toner particles corresponding to predetermined particle-sizes, a suitable particle classification method is employed. Typical particle classification methods include air classification, screening, cyclone separation, elutriation, centrifugation and combinations thereof.
  • the preferred method of obtaining the very fine toner particles of our invention is by centrifugal air classification.
  • Suitable milling and air classification results may be obtained when employing a combination apparatus such as the A.F.G. (Alpine Fliessbeth-Gegenstrahlmühle) type 100 as milling means, equipped with an A.T.P. (Alpine Turboplex windsichter) type 50 G.S., as air classification means, the model being available from Alpine Process Technology Ltd., Rivington Road, Whitehouse, Industrial Estate, Runcorn, Cheshire, U.K. Further air classification can be realised using an A 100 MZR (Alpine Multiplex Labor Zick-zack sichter) as additional classification apparatus, the latter model being also available from Alpine Process Technology Ltd.
  • A.F.G. Alpha Fliessbeth-Gegenstrahlmühle
  • A.T.P. Alpha Turboplex windsichter
  • a 100 MZR Alpha Multiplex Labor Zick-zack sichter
  • the size distribution of the so obtained toner particles can be determined in a conventional manner by employing a Coulter Counter type TA II/PCA1, model available from the Coulter Electronics Corp., Northwell Drive, Luton, Bedfordshire, LV 33 R4, United Kingdom.
  • air or some other gas is used as transport medium and particles contained in the fluidum are exposed to two antagonistic forces, viz., to the inwardly directed tractive force of the fluidum, and to the outwardly directed centrifugal force of the particle.
  • both forces are in equilibrium. Larger (heavier) particles are dominated by the mass-dependent centrifugal force and the smaller (lighter) particles by the frictional force proportional to the particle diameter. Consequently, the larger or heavier particles fly outwards as coarse fraction, while the smaller or lighter ones are carried inwards by the air as fine fraction.
  • the "cut size" usually depends upon the geometrical as well as operational parameters (dimensions of classification, rotor, rotational velocity, etc.). Adjustment of the cut size may be effected through variation of the above mentioned parameters.
  • toner particles may be prepared which are in accordance with the aforementioned size distribution as claimed, these toner particles as such exhibit problems when used in electrostatographic copying or printing apparatus as their flowability and hence forth overall performance in the electrostatographic process is insufficient.
  • the toner particles may be admixed with flow enhancing additives.
  • These additives mostly are extremely fine inorganic materials. Widely used in this context are fumed inorganics such as silica, alumina or zirconium oxide or titanium oxide. The use of silica as flow improving agent for toner compositions is described in the United Kingdom Patent Specification No. 1,438,110.
  • the fumed silica particles used in the toner composition of the present invention are essentially spherical, and have a surface coated with hydrophobic layer such as obtained by reaction between silanol groups of the silica-type micro-particles and silanes of different types and volumes, whereby reference is made to EP 0234009 (of Toray Silicone Co.).
  • Other microparticles may also be used showing comparable properties and preparation-procedures.
  • fysically absorbed coatings also fullfill the conditions of the present invention, showing on long term developing processes with the potential drawback of filming on the image bearing member and other machineparts.
  • Fumed silica particles with surface area larger than 150m 2/g and methanol values larger than 20 are commercially available under the Trade Marks Aerosil and CAB-O-SIL marketed by Degussa, Frankfurt (M), W.Germany and Cabot Corp. Oxides Division, Boston, Mass., U.S.A. respectively.
  • AEROSIL R972 is a typical example of fumed hydrophobic silica having a specific surface area of 110 sq.m/g and a methanol value of 40.
  • the specific surface area can be measured by a method described by Nelsen and Eggertsen in "Determination of Surface Area Adsorption Measurements by continuous Flow Method", Analytical Chemistry, Vol. 30, No. 8 (1958) 1387-1390.
  • the preferred proportions of fumed silica to toner material are in the range of 0.5 to 3 % by weight.
  • the toner compositions used in accordance with the present invention may comprise conventional resin binders such as those disclosed e.g. in European Patents 0 128 569 and 0 170 421, and European application no.89200192.6.
  • European patent 0 279 960 being copolymers of
  • the toner properties may be used for further optimizing the toner properties.
  • additional release agent assisting in the release of the toner melt from the fuser roller, should advantageously be incorporated in the toner composition.
  • Particularly suited release agents are abhesion promoting compounds, e.g. talcum, silicones, fluor containing polymers and natural or synthetic waxes.
  • Suitable fluor-containing vinyl polymers having a particularly low friction coefficient (static friction coefficient with respect to steel below 0.2) for preventing toner offsetting on the fuser roll are described in US-A-4,059,768.
  • waxy polyalkylene resins More particularly an isotactic polypropylene having an average molecular weight lower than 15,000.
  • the coloring substance used in the toner particles may be any inorganic pigment (including carbon) or solid organic pigments or dyes, or mixtures thereof commonly employed in dry electrostatic toner compositions.
  • inorganic pigment including carbon
  • solid organic pigments or dyes or mixtures thereof commonly employed in dry electrostatic toner compositions.
  • use can be made e.g. of carbon black and analogous forms thereof, such as lamp black, channel black, and furnace black e.g. SPEZIALSCHWARZ IV (trade-name of Degussa Frankfurt/M, W.Germany) and CABOT REGAL 400 (trade name of Cabot Corp. High Street 125, boston, U.S.A.).
  • the addition of colorants may also influence the melt viscosity of the toner and if desired, the addition of colorants may be considered that bring the melt viscosity of the toner in the desired range.
  • the colorants can be added and mixed with the molten toner composition that on cooling is crushed and ground to obtain the desired particle size.
  • viscosity regulating pigments can be considered.
  • the present invention includes toners wherein one or more coloring substances are present.
  • the typical solid organic dyestuffs used in electrophotographic toners are the so-called pigment dyes, which include phthalocyanine dyes, e.g. copper phthalocyanines, metal-free phthalocyanines, azo dyes, and metal complexes of azo dyes.
  • pigment dyes include phthalocyanine dyes, e.g. copper phthalocyanines, metal-free phthalocyanines, azo dyes, and metal complexes of azo dyes.
  • FANALROSA B Supra Pulver (trade name of BASF AG, Ludwigshafen, Western Germany), HELIOGENBLAU LG (trade name of BASF for a metal-free phthalcyanine blue pigment), MONASTRAL BLUE (a copper phthalocyanine pigment, C.I. 74,160).
  • HELIOGENBLAU B Pulver (trade name of BASF)
  • HELIOECHTBLAU HG (trade name of Bayer AG, Leverkusen, Western Germany, for a copper phthalocyanine C.I. 74,160
  • BRILLIANT CARMINE 6B (C.I. 18,850)
  • VIOLET FANAL R (trade name of BASF, C.I. 42,535).
  • the typical inorganic pigments used in electrophotography include carbon black, black iron (III) oxide and mixed copper(II) oxide/chromium(III) oxide/iron(III)oxide powder, milori blue, ultramarine cobalt blue, and barium permanganate. Further can be mentioned : the pigments described in the French Patent Specifications 1,394,061 filed December 23, 1963 by Kodak Ltd. and 1,439,323 filed April 27, 1965 by Harris Intertype Corporation.
  • the coloring substance is normally used in a concentration range from 5 to 20 % by weight, calculated with respect to the total weight of the toner.
  • insoluble coloring substances Apart from insoluble coloring substances the use of soluble coloring substances can also be considered.
  • charge control agent(s) is (are) added to the toner particle composition as described e.g. in the published German patent application (DE-OS) 3,022,333 for yielding negatively chargeable toner particles or as described e.g. in the published German Patent application (DE-OS) 2,362,410 and the United States Patent Specifications 4,263,389 and 4,264,702 for yielding positively chargeable toner particles.
  • a very useful charge control agent for offering positive charge polarity is BONTRON N04 (trade name of Oriental Chemical Industries - Japan) being a resin acid modified nigrosine dye which may be used e.g. in an amount up to 5 % by weight with respect to the toner particle composition.
  • a very useful charge control agent for offering negative charge polarity is BONTRON S36 (trade name of Oriental Chemical Industries - Japan) being a metal complex dye which may be used e.g. in an amount up to 5 % by weight with respect to the toner particle composition.
  • the coloring material and other additives are added to the molten resin and are subjected to kneading until a homogeneous mixture is obtained. After cooling, the solid mass obtained is crushed and ground e.g. in a hammer mill followed by a jet-mill. After this operation, air classification was effected.
  • the maximum development density attainable with toner particles of a given size is determined by the charge/toner particle mass ratio, which is determined substantially by the triboelectric charge obtained by friction contact with carrier particles in case of a two-component developer.
  • the toner compositions of the present invention preferably should be used in combination with carrier particles.
  • the development may proceed by so-called cascading the toner particles over the imaging surface containing the electrostatic charge pattern or with magnetic brush.
  • the carrier particles may be electrically conductive, insulating, magnetic or non-magnetic (for magnetic brush development they must be magnetic), as long as the carrier particles are capable of triboelectrically obtaining a charge of opposite polarity to that of the toner particles so that the toner particles adhere to and surround the carrier particles.
  • the carrier particle composition and/or toner particle composition is selected so that the toner particles acquire a charge having a polarity opposite to that of the electrostatic latent image so that toner deposition occurs in image areas.
  • the carrier particle composition and toner particle composition is selected so that the toner particles acquire a charge having the same polarity as that of the electrostatic latent image resulting in toner deposition in the non-image areas.
  • Useful carrier materials for cascade development include sodium chloride, ammonium chloride, aluminium potassium chloride, Rochelle salt, sodium nitrate, aluminium nitrate, potassium chlorate, granular zircon, granular silicon, silica, methyl methacrylate, glass.
  • Useful carrier materials for magnetic brush development include, steel, nickel, iron, ferrites, ferromagnetic materials, e.g. magnetite, whether or not coated with a polymer skin.
  • Other suitable carrier particles include magnetic or magnetizable materials dispersed in powder form in a binder as described e.g. in US-A-4,600,675.
  • Oxide coated iron powder carrier particles are described e.g. in U.S.Patent 3,767,477.
  • the U.S.Patents 3,847,604 and 3,767,578 relate to carrier beads on the basis of nickel.
  • An ultimate coated carrier particle diameter between about 30 microns to about 1000 microns is preferred.
  • the carrier particles possess then sufficient inertia to avoid adherence to the electrostatic images during the cascade development process and withstand loss by centrifugal forces operating in magnetic brush devleopment.
  • the carrier may be employed with the toner composition in any suitable combination, generally satisfactory results have been obtained when about 1 part of toner is used with about 5 to about 200 parts by weight of carrier.
  • the toner compositions of the present invention may be used to develop electrostatic latent images on any suitable electrostatic surface capable of retaining charge, particularly photoconductive layers known in the art including conventional photoconductors.
  • Hot roll fusing of toners is described e.g. in Journal of Imaging Technology, Vol. 11, No. 6, Dec. 1985, p. 261-279 and the heated roller fusing process as well as an electrostatographic apparatus for implementing this process is set forth in detail in the already cited European patent 0 279 960, whereas infra-red fusing is described in U.S. Patent 4,525,455.
  • ATLAC T500 (trade name of Atlas Chemical Industries Inc., Wilmington, Del., USA) being a propoxylated bisphenol A fumarate polyester with a glass transition temperature of 51°C, a melting point in the range of 65° to 85°C, an acid number of 13.9, and an intrinsic viscosity measured at 25°C in a mixture of phenol/ortho dichlorobenzene (60/40 by weight) of 0.175
  • 10 parts of Cabot Regal 400 (trade name of Cabot Corp., Boston, Mass., USA) being a carbon black, were introduced in a kneader and heated at 120°C to form a melt, upon which the kneading process was started.
  • the size distribution of the toner was then determined in a Coulter Multisizer apparatus with a measuring tube of 30 micron, the results of which are seth forth hereunder in Table no. 1.
  • the selected toner particles were introduced in a mixing apparatus and Aerosil R812 (a trade name of Degussa AG, Germany), being a fumed hydrophobic silica with a specific surface of 260 m 2/g and methanol value 56 and an average particle diameter of 7 nm, was admixed to the toner as follows.
  • Aerosil R812 a trade name of Degussa AG, Germany
  • toner particles To 100 g of toner particles, 0.5 g of fumed silica particles were added in a metal box (with a diameter of 10 cm) containing 100 ceramic balls with average diameter of 9 mm, and density of 2.4 g/cm3. This mixture was then rotated at a speed of 300 rpm, for a period of 30 minutes (this method is referred to in table 2 as method A).
  • An electrostatic image formed on an electrophotographic recording element i.e. an As2Se3 coated conductive drum, which was positively charged and image-wise exposed to light
  • an electrophotographic recording element i.e. an As2Se3 coated conductive drum, which was positively charged and image-wise exposed to light
  • a magnetic brush which was built up with a developer obtained by mixing the obtained toner with a typical carrier such a ferrite carrier (Ni-Zn type), with a magnetisation of 50 EMU/g.
  • the average carrier particle diameter was on or about 65 micron.
  • the developer After addition of the toner particles to the carrier in an amount of 2,5 % by weight with respect to the carrier, the developer is activated by rolling in a metal box with a diameter of 6 cm, at 300 revolutions per minute, during a period of 30 minutes, with an apparant degree of filling of 30 %.
  • the amount of toner as percent to the weight of the carrier should be larger; this implies that in both cases the amount in terms of surface coverage of toner to the carrier remains equal.
  • the transfer of the electrostatically deposited toner proceeded by applying a positive voltage of 3 kV to a metal roll, which was kept in close ohmic contact with the rear side of a paper sheet acting as receiving material whose front side was therefore kept in close contact with the toner image on the photoconductor.
  • the image-wise transferred toner particles were fed to a radiation fusing device operating with an infra-red light fusing element such as described in the text of Example 8 of US Patent 4,525,445.
  • toner particles with a conventional size distribution e.g. characterised by an average particle size diameter of 10 to 15 microns
  • the resolution of the overall electrostatographic process in a conventional copier is limited to lines of about 35 microns; this means that a line pair structure whereby the distance between successive black lines is less than 35 microns cannot be faithfully reproduced by the overall electrostatographic process.
  • lines with a thickness down to 25 microns were faithfully reproduced from the original on to the final copy.
  • Said wedge exhibits figures consisting of concentric circles with increasing resolution.
  • the bulk density of the toner particles is measured in accordance with conventional techniques in an apparatus such as the Beckmann Air Comparimeter, model available from Beckmann Instruments, Chemin des Bourdon nr. 52-54, 93220 Gagny, France.
  • the apparent density of the toner particles is determined according to the following procedure.
  • 100 g of toner particles are shaken for a few minutes in a bottle with a volume of approximately 500 ml and are thereafter put on a vibrating seive with a diameter of 7 cm, a mesh size of 1 mm, vibrating at a frequency of 50 Hz and an amplitude of 1 mm.
  • the agitated toner particles are fed through the seive to a flat cylindrical recipient with a height of 1.7 cm and a diameter of 7 cm. After equilibration for 2 minutes the toner particles exceeding the height of the recipient are scraped off and the weight of the toner particles contained in the recipient is determined.
  • the resolution attainable with the toner according to the present invention is up to 8 microns.
  • the particle size distribution of the toner with reference number 2 in the above Table 2 is set forth hereinafter.
  • This toner was prepared according to the same procedure as set forth above but a different size distribution was obtained due to different milling and classification settings of the A.F.G./A.T.P. Alpine combination apparatus described above.
  • the columns two and three have the same meaning as the corresponding columns of Table 1.
  • Analysis of the size distribution shows the following results : percentage of particles by volume larger than 3 micron : 88 % percentage of particles by volume larger than 4 micron : 58 % percentage of particles by volume larger than 5 micron : 15 %
  • the particle size distribution of the toner with reference number 13 in the above Table 4 is set forth hereinafter.
  • the columns two and three have the same meaning as the corresponding columns of Table 1.
  • Analysis of the size distribution shows the following results : percentage of particles by volume larger than 3 micron : 38 % percentage of particles by volume larger than 4 micron : 5 % percentage of particles by volume larger than 5 micron : 1 %
  • the following aspects were evaluated : cleaning problems of the photoconductive drum, caused by strongly adhering toner particles thereto, transfer efficiency of toner particles from the photoconductive drum to the paper substrate in the transfer station, fog on the paper substrate, quality of the magnetic brush, and overall fluidity and supply of the toner to the development station.
  • the toners with ref. number 7, 8, 9 and 13 showed overall good performance in respect of the abovementioned process characteristics.
  • the toner particles with ref. numbers 10 and 11 showed insufficient performance for all of the above process characteristics whereas the toner composition with ref. number 12 exhibited bad performance in respect of toner fluidity, fog, cleaning, and medium performance in respect of quality of the magnetic brush, and transfer efficiency.

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  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Developing Agents For Electrophotography (AREA)

Abstract

L'invention concerne une composition de toner, composée de particules de toner fusibles pouvant être attirées électrostatiquement, adaptées pour le développement de configurations de charges électrostatiques. Selon l'invention, on a produit des particules de toner électrostatographiques adaptées pour être utilisées dans le développement d'une configuration de charges électrostatiques, caractérisées en ce que lesdites particules de toner présentent une distribution granulométrique classifiée dans laquelle plus de 90 % en volume des particules de toner présentent des diamètres de grosseur de particules équivalents supérieurs à 0,5 microns, et inférieurs à 7 microns, et plus d'environ 50 % en volume des particules de toner présentent des diamètres granulométriques équivalents inférieurs à environ 5 microns. Lesdites particules de toner présentent sur leur surface un additif améliorant l'écoulement, dont la concentration est d'au moins 0,1 % en poids et au plus 5 % en poids, ledit additif améliorant l'écoulement étant caractérisé par un produit d'une surface spécifique (A m2/g) multipliée par une valeur de méthanol (B % V/V) satisfaisant à la relation A x B > 10.000, le rapport entre la densité apparente et la densité volumique des particules de toner satisfaisant à l'équation suivante: app/bulk > 0,2. Selon les modes de réalisation préférés, plus de 50 % en volume des particules de toner ont des diamètres granulométriques équivalents inférieurs à 4, respectivement 3 microns.

Claims (10)

  1. Des particules de toner électrostatographique sec pour le développement d'une image électrostatique de charge, ces particules de toner présentant une répartition granulométrique des particules classées caractérisée en ce que :
    - plus de 90 % en volume des particules de toner présentent des diamètres de grosseurs de particule équivalents supérieurs à 0,5 µm et inférieurs à 7 µm, et
    - plus d'environ 50 % en volume des particules de toner présentent des diamètres de grosseurs de particule équivalents inférieurs à environ 5 µm, et
    - où ces particules de toner présentent sur leur surface des microparticules inorganiques fines servant d'adjuvants améliorant l'écoulement dans une concentration d'au moins 0,1 % en poids et de 5 % en poids tout au plus, ces microparticules inorganiques fines étant caractérisées par un produit de surface spécifique A (m²/g) par valeur méthanol B (% en volume) correspondant à la relation suivante A x B > 10 000
    Figure imgb0017
     et où le rapport entre la masse volumique apparente et la masse volumique non tassée des particules de toner satisfait à la relation suivante :
    ρ app ρ non tassée > 0,2
    Figure imgb0018
  2. Des particules de toner électrostatographique sec suivant la revendication 1, caractérisées en ce que plus de 90 % en volume des particules de toner présentent des diamètres de grosseurs de particule équivalents supérieurs à 0,5 µm et inférieurs à 6 µm, et plus d'environ 50 % en volume des particules de toner présentent des diamètres de grosseurs de particule équivalents inférieurs à environ 4 µm.
  3. Des particules de toner électrostatographique sec suivant la revendication 1, caractérisées en ce que plus de 90 % en volume des particules de toner présentent des diamètres de grosseurs de particule équivalents supérieurs à 0,5 µm et inférieurs à 5 µm, et plus d'environ 50 % en volume des particules de toner présentent des diamètres de grosseurs de particule équivalents inférieurs à environ 3 µm.
  4. Des particules de toner électrostatographique sec suivant la revendication 1, caractérisées en ce que les microparticules inorganiques fines sont enrobées d'unités contenant des groupements hydrophobes ayant pour conséquence une valeur méthanol supérieure à 20.
  5. Des particules de toner électrostatographique sec suivant la revendication 1, caractérisées en ce que les microparticules inorganiques fines présentent une surface spécifique supérieure à 150 m²/g.
  6. Des particules de toner électrostatographique sec suivant l'une quelconque des revendications précédentes, caractérisées en ce que les microparticules inorganiques fines sont une matière inorganique pyrogénée (fabriquée suivant le procéde d'hydrolyse à haute température dans une flamme oxhydrique, en Anglais : fumed).
  7. Des particules de toner électrostatographique sec suivant la revendication 6, caractérisées en ce que la matière inorganique pyrogénée est de la silice pyrogénée qui est contenue en une quantité d'au moins 0,5 % en poids par rapport au poids du toner.
  8. Des particules de toner électrostatographique sec suivant l'une quelconque des revendications précédentes comprenant un colorant dispersé ou dissout dans la résine liante du toner.
  9. Des particules de toner électrostatographique sec suivant l'une quelconque des revendications précédentes, caractérisées en ce que les particules de toner contiennent un agent de réglage de charge négative ou positive.
  10. Des particules de toner électrostatographique sec suivant l'une quelconque des revendications précédentes, caractérisées en ce que les particules de toner et un support granuleux sont mélangés pour le développement en cascade ou le développement à la brosse magnétique d'images électrostatiques de charge.
EP90910656A 1989-06-28 1990-06-25 Composition de toner electrostatographique sec Expired - Lifetime EP0479875B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP89201695 1989-06-28
EP89201695 1989-06-28
PCT/EP1990/001027 WO1991000548A1 (fr) 1989-06-28 1990-06-25 Composition de toner electrostatographique sec

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EP0479875A1 EP0479875A1 (fr) 1992-04-15
EP0479875B1 true EP0479875B1 (fr) 1995-09-27

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0578695B1 (fr) * 1991-04-11 1997-01-08 Agfa-Gevaert N.V. Composition revelatrice electrophotographique
JP2735096B2 (ja) * 1994-06-03 1998-04-02 富士通株式会社 画像形成方法および装置
US5805969A (en) * 1995-08-10 1998-09-08 Xeikon N.V. Electrostatographic printer for imparting a modified finish to a toner image
EP0775948A1 (fr) 1995-11-24 1997-05-28 Xeikon Nv Imprimante électrostatographique à plusieurs couleurs à une seule passe
KR970028908A (ko) * 1995-11-24 1997-06-24 엘 드 샴펠라에레 싱글 패스 다색 정전 사진 프린터
PL399250A1 (pl) 2012-05-21 2013-11-25 Zaklad Mechaniczny Marpo Spólka Jawna M. Przygodzki I Wspólnicy Sposób i urzadzenie do prowadzenia recyklingu odpadów organicznych, a szczególnie zuzytych opon, przy wykorzystaniu techniki mikrofalowej

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60238847A (ja) * 1984-05-11 1985-11-27 Konishiroku Photo Ind Co Ltd 画像形成方法
US4652509A (en) * 1984-05-11 1987-03-24 Konishiroku Photo Industry Co., Ltd. Toner for developing electrostatic latent image
JPS61241766A (ja) * 1985-04-19 1986-10-28 Canon Inc 静電荷像現像用トナ−
US4702986A (en) * 1984-08-30 1987-10-27 Canon Kabushiki Kaisha Electrophotographic method uses toner of polyalkylene and non-magnetic inorganic fine powder
JPS6247651A (ja) * 1985-08-27 1987-03-02 Canon Inc 画像形成方法
JPS6252567A (ja) * 1985-08-30 1987-03-07 Konishiroku Photo Ind Co Ltd 現像方法
JPH083659B2 (ja) * 1986-05-16 1996-01-17 キヤノン株式会社 静電荷像現像用トナー及び現像方法
JPS62293253A (ja) * 1986-06-13 1987-12-19 Konica Corp 画像形成方法
US4737433A (en) * 1986-11-03 1988-04-12 Eastman Kodak Company Electrostatographic method of making images
JPH07113783B2 (ja) * 1986-12-01 1995-12-06 キヤノン株式会社 負荷電性の電子写真用現像剤

Also Published As

Publication number Publication date
WO1991000548A1 (fr) 1991-01-10
JPH04506420A (ja) 1992-11-05
JP2835650B2 (ja) 1998-12-14
DE69022728D1 (de) 1995-11-02
DE69022728T2 (de) 1996-05-02
EP0479875A1 (fr) 1992-04-15

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