Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
  • G03G7/0006—Cover layers for image-receiving members; Strippable coversheets
  • G03G7/002—Organic components thereof
• • 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
  • G03G9/087—Binders for toner particles
  • G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
  • G03G9/08791—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by the presence of specified groups or side chains
• • 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
  • G03G9/087—Binders for toner particles
  • G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
  • G03G9/08795—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by their chemical properties, e.g. acidity, molecular weight, sensitivity to reactants
• • 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
  • G03G9/0926—Colouring agents for toner particles characterised by physical or chemical properties
• • 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
  • G03G9/09733—Organic compounds
  • G03G9/09758—Organic compounds comprising a heterocyclic ring
• • 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
  • G03G9/09733—Organic compounds
  • G03G9/09775—Organic compounds containing atoms other than carbon, hydrogen or oxygen

Definitions

• the present invention relates to a method for producing toner images, wherein the toner images are strongly attached to the substrate and are highly resistant to wear.
• a latent image is formed that is developed by attraction of so called toner particles. Afterwards the developed latent image (toner image) is transferred to a final substrate and fused to this substrate. In DEP the so called toner particles are imagewise deposited directly on a final substrate and fused to this substrate.
• Toner particles are basically polymeric particles comprising a polymeric resin as main component and various ingredients mixed with said toner resin. Apart from colourless toners, which are used e.g. for finishing function, the toner particles comprise at least one black and/or colouring substances, e.g., coloured pigment.
• the toner particles can be present in a liquid or in a dry developer composition.
• a capsule toner having a core comprising a polymerisable compound, a polymerization initiator and other normal toner ingredients.
• the core is surrounded by a hard shell that breaks during the fixing step.
• the polymerisable compound is polymerized, in this particular disclosure, by low energy visible light.
• the objects of this invention are realized in a first embodiment of this invention by providing a method for forming a toner image on a substrate comprising the steps of :
• the objects of this invention are realized in a second embodiment of this invention by providing a method for forming a toner image on a substrate comprising the steps of :
• a so called “cross-linker” or “hardening” agent comprising reactive groups RGB
• RGA reactive groups contained in the toner particles.
• An "image on a substrate” is, in the context of this invention, meant to include a substrate carrying human readable or/and machine readable text, a substrate carrying figures, a substrate carrying pictures (both coloured and monochromatic) as well as a substrate carrying a combination of at least two of the above.
• a specific chemical interaction between the toner particles and a substrate is used to enhance the mechanical strength of a toner image and/or of the binding between toner image and substrate.
• Both said reactive groups RGA and said reactive groups RGB are preferably members selected from the group consisting of epoxy groups, aldehyde groups, hydroxyl groups, carboxyl groups, mercapto groups, amino groups and amide groups.
• the reactive groups RGA and RGB are preferably chosen such as to form a reaction pair that reacts easily (i.e. fast, at relatively low temperature) together.
• Both reactive groups (RGA and RGB) can be part of a polymeric, oligomeric or low molecular weight (molecular weight lower than 2000) molecule.
• the molecule carrying reactive groups RGA and reactive groups RGB can carry one or more of these reactive groups.
• the toner particles and/or the substrate can comprise, if so desired, a mixture of compounds carrying reactive groups. E.g.
• the toner particles can comprise a compound comprising hydroxyl groups together with a compound comprising epoxy groups.
• different compounds carrying reactive groups can be present, it can e.g. be useful to mix in the substrate a polymeric compound comprising reactive groups with a low molecular weight molecule comprising reactive groups.
• the reaction between the reactive groups results in cross-linking of the toner particles, in chemically fixing the toner particles to the substrate or in both cross-linking the toner particles and chemically fixing them to the substrate.
• the reactive groups RGA in the toner particles are comprised in a polymeric compound and the reactive groups RGB in the substrate in a low molecular weight molecule carrying e.g. two reactive groups RGB, then, during fusing of the toner particles to the substrate, the low molecular weight molecule can migrate from the substrate and cross-link two polymeric compounds, carrying reactive groups RGA, present in the toner particles.
• the reactive groups RGA and RGB are contained in polymeric compounds, then during fusing the reaction between RGA and RGB will rather result in a chemical fixing of the (fused) toner particles to the substrate.
• the ratio between the cross-linking and chemical fixing reaction can be adapted to the needed hardness of the toner layer and to the needed strength of fixing of the fused toner particles to the substrate.
• Typical reaction pairs, comprising reactive groups RGA or RGB, and very useful in the present invention are e.g. :
• the compounds comprising reactive groups RGA are preferably solids that do not deteriorate the mechanical strength of the toner particles in which they are incorporated.
• said reactive groups RGA are part of a polymer used as toner resin (either alone or in mixture with other known toner resins) and said resin carrying reactive groups RGA has preferably a Tg ⁇ 35 °C, preferably larger than 40 °C.
• the polymeric compounds carrying reactive groups are preferably incorporated in the toner particles.
• Very suitable polymers having an acid value > 2.5 mg KOH/g and/or a hydroxyl value > 2.5 mg KOH/g, for use in toner particles used in the method of this invention, can be polycondensation polymers as well as addition polymers, typical examples are tabulated in table 1.
• the reactive groups RGA can also be part of an epoxy-resin that is incorporated in or is the toner resin of the toner particles. Typical examples of useful epoxy resins (polymers) are e.g.
• ARALDITE GT 7203 (trade name for an epoxy resin of Ciba-Geigy of Switserland) and EPIKOTE 1004 (trade name of Shell Company, UK).
• the compound carrying reactive groups RGA and incorporated in the toner particles can also be a polyamide resin or a polyester/polyamide copolymer.
• Chemical structure AV HV Tg °C Mn Mw 1. Polyester resin of terephthalic acid, ethyleneglycol and DIANOL 22 3 31.1 62 3.6 10 2. Polyester resin of fumaric acid and DIANOL 33 17 5.2 55 4.4 12 3. Polyester resin of terephthalic acid, isophthalic acid and DIANOL 22 and ethyleneglycol 18 20.9 60 4 18 4.
• Copoly(styrene-butylacrylate-butylmethacrylate-stearylmethacrylate-methacrylic acid) (65/5/21/5/4) 12 0 58 6 108 5.
• Copoly(styrene-butylmethacrylate-acrylic acid) (80/15/5) 5 0 63 5.5 180 6.
• DIANOL 22 is a trade name of AKZO CHEMIE of the Netherlands for bis-ethoxylated 2,2-bis(4-hydroxyphenyl)propane.
• DIANOL 33 is a trade name of AKZO CHEMIE of the Netherlands for bis-propoxylated 2,2-bis(4-hydroxyphenyl)propane.
• the chemical compound (polymeric, oligomeric or single molecule) carrying reactive groups RGA can be present in the bulk of the toner particles, on the surface of the toner particles or both in the bulk and on the surface of the toner particles.
• Toner particles comprising compounds with reactive groups RGA in the bulk of the particle can be prepared by melt kneading the toner ingredients (e.g. toner resin, charge control agent, pigment, etc) and said compounds with reactive groups RGA. After the melt kneading the mixture is cooled and the solidified mass is pulverized and milled and the resulting particles classified. Also the "emulsion polymerisation” and “polymer emulsion” techniques for toner preparation can be used to prepare toner particles wherein compounds with reactive groups RGA are incorporated in the bulk of the toner particles.
• toner ingredients e.g. toner resin, charge control agent, pigment, etc
• emulsion polymerization a water-immiscible polymerizable liquid is sheared to form small droplets emulsified in an aqueous solution, and the polymerization of the monomer droplets takes place in the presence of an emulsifying agent; such a technique is described e.g. in US P 2,932,629, US P 4,148,741, US P 4,314,932 and EP-A 255 716.
• polymer emulsion a preformed polymer is dissolved in an appropriate organic solvent that is immiscible with water, the resulting solution is dispersed in an aqueous medium that contains a stabilizer, the organic solvent is evaporated and the resulting particles are dried; such a technique is described in, e.g., US P 4,833,060.
• Toner particles having compounds carrying reactive groups at the surface can be prepared as described in EP-A 725 317.
• a method for producing toner particles comprising the steps of :
• preferred stabilizer (co)polymers are being copolymers of vinyl acetate and crotonic acid (90/10 by weight) having a total acid number of 50 to 300, and copolymers of styrene and maleic acid anhydride having a total acid number of 250 to 500, both said copolymers being used, at least partially, transformed into their ammonium salt form.
• the water-soluble stabilizing (co)polymer is precipitated on to the particles, produced by the method according to this invention, by chemical reaction, e.g. acidification of the aqueous medium, the water-soluble (co)polymer adhering to the dispersed polymer particles can be transformed into a water-insoluble species that precipitates on the particles. By doing so carboxylic acid groups are present at the surface of the toner particles.
• the hardening reaction proceeds easily when the interpenetration between toner particles and substrate is quite high.
• This interpenetration is reached by heating the toner particles on the substrate (during fixing or after fixing in an additional heating step) to a temperature that preferably is at most 150 °, most preferably at most 120 °C. Therefore it is preferred to use toner particles, comprising compounds carrying reactive groups RGA, that have a meltviscosity at 120 °C between 50 and 2000 Pas, preferably between 100 and 1000 Pas. All melt viscosities mentioned herein are measured in a RHEOMETRICS dynamic rheometer, RVEM-200 (One Possumtown Road, Piscataway, NJ 08854 USA).
• the viscosity measurement is carried out at a sample temperature of 120 °C.
• the sample having a weight of 0.75 g is applied in the measuring gap (about 1.5 mm) between two parallel plates of 20 mm diameter one of which is oscillating about its vertical axis at 100 rad/sec and amplitude of 10 -3 radians.
• the reaction between reactive groups RGA and RGB can beneficially be speeded up by providing catalysers for this reaction.
• Said catalysers are preferably acids (organic or anorganic) or tertiary amines. Typical examples of suitable catalysers are p-toluenesulfonic acid, trimethylamine and triethylamine.
• the catalyser or catalysers can, within the scope of the present invention, be incorporated in the toner particles, the substrate or both in the toner particles and the substrate.
• the catalyser or catalysers can be incorporated in the toner particles, as long as the incorporation of it does not result in a weakening of the mechanical resistance of the toner particles, i.e. when the Tg stays equal to or higher than 35 °C.
• the toner particles not only comprise reactive groups RGA, e.g., a member selected from the group consisting of epoxy groups, aldehyde groups, hydroxyl groups, carboxyl groups, mercapto groups, amino groups and amide groups, but comprise further a compound or mixture of compounds carrying radiation curable groups.
• RGA reactive groups
• the present invention includes also a method for forming toner images on a substrate comprising the steps of :
• the radiation curing can proceed off-line in a separate apparatus wherein the fused layer of toner particles is heated again and irradiated with curing rays.
• the compounds, carrying a radiation curable group, to be incorporated in toner particles for use according to this invention is already an oligomeric or polymeric compound instead of a monomer.
• a monomeric compound may be present in the mixture of radiation curable compounds, as long as the mixture of radiation curable compounds itself has a Tg ⁇ 35 °C.
• electron beam curable groups can be used in the present invention, the radiation curable groups are preferably curable by UV-light.
• Very useful radiation curable polymeric compounds, in toner particles for use in the present invention are UV curable solid epoxy resins with Tg ⁇ 35 °C as disclosed in EP-A 667 381. In this application solid compositions (I) are described containing
• Photoinitiator For the UV curing to proceed it is necessary that a photoinitiator is present.
• Very useful initiators are sulphonium salts as e.g. triarylsulphonium salts, triarylsulphoniumhexafluorophosphate, benzophenones, etc.
• Typical very useful photoinitiators in the context of this invention are, e.g., 2-hydroxy-2-methyl-1-phenylpropan-1-one, compound I, a mixture of compound I and compound II and compound III :
• the initiator can be incorporated in the toner particles together with the UV curable system or can be incorporated in the substrate.
• This embodiment has the advantage that the resins comprised in the fused image are cross-linked (by UV-curing) and attached to the substrate by chemical bonds.
• UV-curable or radiation curable compounds are used in the first embodiment of the present invention, it is possible to do so in various combinations :
• a substrate useful in the first embodiment of the invention comprises reactive groups RGB.
• This reactive groups (RGB) in the substrate, useful in the present invention are in principle a member of the same group of reactive groups as the reactive groups RGA present in the toner particles, i.e. the reactive groups RGB are preferably members selected from the group consisting of epoxy groups, aldehyde groups, hydroxyl groups, carboxyl groups, mercapto groups, amino groups and amide groups.
• the reactive groups RGB can be part of a polymeric, oligomeric or low molecular weight (molecular weight lower than 2000) molecule.
• the molecule carrying reactive groups RGB can carry one or more of these reactive groups.
• the reactive groups RGB are chosen in such a way that they are capable to react with one or more reactive groups RGA present in the toner particles.
• the substrate comprises reactive groups capable of an easy reaction with said hydroxyl and/or carboxyl groups.
• Typical examples of such reactive groups are epoxy groups, aldehyde groups, polyaziridine groups, etc.
• the substrate preferably comprises as reactive group RGB either a hydroxyl, carboxyl, amide or amino group.
• reaction pairs as described above it is preferred to incorporate the low molecular weight compounds or the oligomeric or polymeric compounds having a Tg ⁇ 35 °C in the substrate.
• very suitable compounds carrying reactive groups RGB for incorporation in the substrate are e.g. polyaziridines, polyamidoamine resins, highly methylated melamine resins, hydroxyl group containing epoxy hardening agents, e.g.
• R is alkyl group.
• Further useful epoxy hardening agents are exemplified in e.g. EP-A 495 314 on page 23 to 26. Also epoxy hardening agents represented by formulas A-1 to A-6 can be used in the present invention.
• the compounds with reactive groups can be comprised in a toner receptive layer applied to the substrate.
• the substrate can be paper, cardboard, plastic film, etc.
• Said toner receptive layer can comprise a binder and the compounds with reactive groups RGB can be embedded in said binder.
• the reactive groups RGB can form part of said binder.
• Useful binders, carrying reactive groups RGB are e.g. the same binders as already described herein above as useful binders for the toner particles, i.e. polymers having an acid value > 2.5 mg KOH/g and/or a hydroxyl value > 2.5 mg KOH/g (examples of such polymers are found in table 1) and epoxy polymers. E.g.
• polymers useful as binder in a substrate to be used according to this invention and capable of reacting with a hydroxyl or carboxyl group are epoxy polymers, polymers carrying aldehyde groups, polyaziridines, etc.
• the binder in the image receiving layer of the substrate for use in this invention will preferably comprise hydroxyl, carboxyl and/or amino groups.
• Typical useful binders are gelatin, polyvynilalcohol, etc.
• the binder can also comprise further resinous compounds : e.g. polyamides, carboxyl or sulphonyl group containing polyesters in latex form, etc.
• the substrate can comprise initiators for radiation curing.
• the substrate within the scope of this invention, may further comprise a radiation curable compound and/or a photoinitiator as describe above. It is possible that the substrate comprises said radiation curable compound and that toner particles comprise an initiator for radiation curing as described above.
• the hardening reaction proceeds easily when the interpenetration between toner particles and substrate is quite high.
• This interpenetration is reached by heating the toner particles on the substrate (during fixing or after fixing in an additional heating step) to a temperature that preferably is at most 150 °, most preferably 120 °C.
• the toner receiving layer on the substrate may comprise waxes or "heat solvents” also called “thermal solvents” or “thermosolvents” improving the penetration of the reagents RGA and RGB and thereby the reaction speed of hardening reaction at elevated temperature.
• heat solvent in this invention is meant a non-hydrolyzable organic material which is in solid state at temperatures below 50 °C but becomes on heating above that temperature a plasticizer for the binder of the layer wherein they are incorporated.
• plasticizer for the binder of the layer wherein they are incorporated.
• Useful for that purpose are a polyethylene glycol having a mean molecular weight in the range of 1,500 to 20,000 described in US-P 3,347,675.
• Said toner receiving layer may comprise, apart from a compound comprising reactive groups RGB or mixtures thereof and a binding agent or mixture of binding agents, also stabilizers, toning agents, antistatic agents, spacing particles (both polymeric or anorganic).
• the toner receiving layer may contain other additives such as free fatty acids, antistatic agents, e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H, ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments, and/or optical brightening agents.
• antistatic agents e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
• ultraviolet light absorbing compounds e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
• white light reflecting and/or ultraviolet radiation reflecting pigments e.g. in UV light absorbing compounds
• optical brightening agents e.g., a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
• This first embodiment of the invention encompasses also an apparatus for forming an image comprising hardened toner particles comprising :
• the first embodiment of the invention comprises further an apparatus for forming an image comprising hardened toner particles comprising :
• the toner particles further comprise a UV curable compound
• said means for fusing said toner images emit infrared radiation and said means for UV curing (e.g. one or more UV emitting lamps) are installed immediately after said fusing means so that the UV curing proceed on the still molten toner image.
• the reactive groups RGB are applied on top of the toner image.
• the same toner particles can be used as those used in the first embodiment of the invention and having been described above.
• the substrate used in this second embodiment can be any substrate known in the art, e.g. plastic film, paper, cardboard, etc. It can also be a substrate comprising reactive groups RGB as described above under the first embodiment of the present invention.
• the reactive compound that is applied on top of the image-wise deposited toner particles is a compound comprising reactive groups RGB that can react with the toner particles.
• the compounds carrying reactive groups RGB are applied to the image in an amount between 1 and 10 g/m 2 , preferably between 2 and 8 g/m 2 .
• Typical couples of compounds, comprising reactive groups RGA or RGB, and very useful in the present invention are the same as those exemplified above.
• the toner particles comprise resins with Tg ⁇ 35 °C containing reactive groups RGA.
• the compounds carrying reactive groups RGB can, in the second embodiment of the invention, be applied to the toner image either before or after fusing of the toner particles to the substrate.
• spray coating techniques it is preferred to use spray coating techniques to apply said compounds.
• These compounds may be applied as such, as a solution or as a dispersion, depending on the physical nature of the compound carrying reactive groups RGB.
• the toner image by an non-image-wise applied layer of clear toner particles wherein said clear toner particles comprise reactive groups RGB and wherein the compounds carrying reactive groups RGB have a Tg ⁇ 35 °C.
• the word "clear” means herein not giving, in a wavelength range extending from 400 to 700 nm, a visible diffuse density, said visible diffuse density being defined as less than 15 % light reduction integrated over that wavelength range. In this case said toner particles are applied onto the toner image before fusing.
• toner image it is also possible to cover the toner image with a layer of clear toner particles that do not comprises reactive groups RGB capable of reacting with the reactive groups RGA contained in the image forming toner particles, but comprising reactive groups RGA.
• This layer of clear toner particles is then covered with a compound comprising reactive groups RGB. Afterwards, both reactive groups are made to react together to harden the outermost toner layer in the toner image.
• a layer of clear toner particles is applied to toner images made up by the overlay of several layers of different types of toner particles (e.g.
• the present invention includes also an apparatus for forming an image comprising hardened toner particles comprising :
• Said means for applying said compound carrying reactive groups RGB can be rollers, wicks, sprays, etc.
• said means for applying compound carrying reactive groups RGB are rollers, it may be split rollers, e.g. when 5 g/m 2 of compound carrying reactive groups RGB has to be applied, there may be provided four application rollers, the first two applying together 2 g/m 2 of compound carrying reactive groups RGB and the following rollers applying the remaining 3 g/m 2 .
• Preferred means for applying said compound carrying reactive groups RGB are supply rollers with a surface in NOMEX-felt (NOMEX is a trade name of Du Pont de Nemours, Wilmington, US) as described in article titled "Innovative Release Agent Delivery Systems" by R. Bucher et al.
• the compound carrying reactive groups RGB can be delivered to the image directly by supply rollers as described above, or over an intermediate roller, which distributes the compound even more evenly over the image.
• Said means for applying a compound comprising reactive groups RGB on top of a toner image may be installed before said means for fusing said toner particles or after said means for fusing said toner particles to said substrate.
• the apparatus comprises preferably also special means for reacting said reactive groups RGA and RGB so as to harden said fused toner image.
• These special means are heating means, that may be the same means as those used as fusing means.
• these means for applying the compounds with reactive groups RGB are preferably means for non-contact application, e.g. spraying means and no special means for reacting said reactive groups RGA and RGB so as to harden said fused toner image are necessary since the reaction of reactive groups RGA and RGB proceeds during the fusing step.
• the second embodiment of the invention includes a method for forming toner images on a substrate comprising the steps of :
• the step of UV curing can proceed on line, e.g, in the fusing station itself of an electrostatographic apparatus or in a station immediately adjacent to said fusing station.
• the radiation curing can proceed off-line in a separate apparatus wherein the fused layer of toner particles is heated again and irradiated with curing rays.
• an apparatus for forming an image comprising hardened toner particles comprising :
• the means for fusing and the means for UV curing can be the same as described above under the first embodiment of the present invention.
• the present invention can be practised in any electrographic or magnetographic imaging method. It can be useful in classical electrophotography, in ionography, in direct electrostatic printing (DEP), etc.
• the present invention is useful for mono-chromatic toner images as well as for multi-chromatic and full colour toner images.
• the means for image-wise depositing toner particles can be direct electrostatic printing means, wherein charged toner particles are attracted to the substrate by an electrical field and the toner flow modulated by a printhead structure comprising printing apertures and control electrodes.
• Said means for image-wise depositing toner particles can also be toner depositing means wherein first a latent image is formed.
• said means for image-wise depositing toner particles) comprise :
• Said latent image may be a magnetic latent image that is developed by magnetic toner particles (magnetography) or, preferably, an electrostatic latent image.
• an electrostatic latent image is preferably an electrophotographic latent image and the means for producing a latent image are in this invention preferably light emitting means, e.g., light emitting diodes or lasers and said latent image bearing member comprises preferably a photoconductor.
• Toner particles useful in both embodiments of this invention can have an average volume diameter between 1 and 50 ⁇ m, preferably between 3 and 20 ⁇ m. When the toner particles are intended for use in colour imaging, it is preferred that the volume average diameter is between 3 and 10 ⁇ m, most preferred between 3 and 8 ⁇ m.
• the particle size distribution of said toner particles can be of any type. It is however preferred to have an essentially (some negative or positive skewness can be tolerated, although a positive skewness, giving less smaller particles than an unskewed distribution, is preferred) Gaussian or normal particle size distribution, either by number or volume, with a coefficient of variability (standard deviation divided by the average) ( ⁇ ) smaller than 0.5, more preferably of 0.3.
• Toner particles useful in the first embodiment of this invention, can comprise any normal toner ingredient e.g. charge control agents, pigments both coloured and black, anorganic fillers, etc.
• charge control agents, pigments and other additives useful in toner particles, to be used in a toner composition according to the present invention can be found in e.g. EP-A 601 235.
• the toner particles can be used as mono-component developers, both as a magnetic and as a non-magnetic mono-component developer.
• the toner particles can be used in a multi-component developer wherein both magnetic carrier particles and toner particles are present.
• the toner particles can be negatively charged as well as positively charged.
• the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
• the average particle size of the separated toner was measured by Coulter Counter model Multisizer (tradename) was found to be 8.0 ⁇ m by volume.
• Printing proceeded in an AGFA XC305 colour copier.
• the image was printed both on the part of the paper having a receiving layer and the part not having a receiving layer.
• the resistance of the image against solvents was tested by rubbing the image 10 consecutive times with a cloth soaked with MEK (methylethyleketone).
• MEK methylethyleketone
• the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
• the average particle size of the separated toner was measured by Coulter Counter model Multisizer (tradename) was found to be 8.0 ⁇ m by volume.
• the toner particles were mixed with 0.5 % of hydrophobic colloidal silica particles (BET-value 130 m 2 /g).
• the preparation of the Yellow toner was repeated, but instead of 2 parts SICOECHTGELB PY13, 2 parts of CABOT REGAL 400 (carbon black, trade name of the Cabot Corp. High Street 125, Boston, U.S.A.) were used.
• the four toners, Y, M, C and K had a meltviscosity at 120 ° C of 500 Pas.
• Clear toner 100 parts of an epoxy resin EPIKOTE 1004 (trade mark of the Shell Chemical Co) were melt-blended for 30 minutes at 110 °C in a laboratory kneader.
• the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
• the average particle size of the separated toner was measured by Coulter Counter model Multisizer (tradename) was found to be 8.0 ⁇ m by volume.
• the clear toner CT had a meltviscosity at 120 °C of 150 Pas.
• the toner particles were mixed with 0.5 % of hydrophobic colloidal silica particles (BET-value 130 m 2 /g).
• Each of the above prepared toners were used to form carrier-toner developers by mixing said mixture of toner particles and colloidal silica in a 4 % ratio with silicone-coated Cu-Zn ferrite carrier particles having an average diameter of 55 ⁇ m.
• Full colour toner images were produced using a commercial CHROMAPRESS (a trade name of Agfa-Gevaert NV, Mortsel, Belgium). The images were covered with a layer of clear toner such that 0.9 mg/cm 2 clear toner was present. The fusing took place with radiant heat. On top of the layer of clear toner a solution of 20 g of a polyaminoamide resin (UNIREZ 1307 trade name) with amino value between 370 and 410 mg KOH/g and 1.6 g of a catalyser (XB 3130 trade name of Ciba Geigy, Switserland) was applied at a wet thickness of 4 ⁇ m (i.e. 4 g of polyaminoamide resin per m 2 ).
• a polyaminoamide resin UNIREZ 1307 trade name
• the image was kept for 1 minute at 125 °C. After cooling the image, the resistance of the image against solvents was tested by rubbing the image 10 consecutive times with a cloth soaked with MEK (methylethyleketone).
• MEK methylethyleketone

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• 1997
  • 1997-06-21 EP EP97201900A patent/EP0821280A1/fr not_active Withdrawn

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