EP1725912A2 - Particules de toner et procede et installation de production desdites particules - Google Patents

Particules de toner et procede et installation de production desdites particules

Info

Publication number
EP1725912A2
EP1725912A2 EP05701239A EP05701239A EP1725912A2 EP 1725912 A2 EP1725912 A2 EP 1725912A2 EP 05701239 A EP05701239 A EP 05701239A EP 05701239 A EP05701239 A EP 05701239A EP 1725912 A2 EP1725912 A2 EP 1725912A2
Authority
EP
European Patent Office
Prior art keywords
droplets
dispersion
toner particles
liquid phase
polymer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05701239A
Other languages
German (de)
English (en)
Inventor
Hans Paffhausen
Ulrich Morf
Joachim Kretschmer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pelikan Hardcopy Production AG
Original Assignee
Pelikan Hardcopy Production AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE102004004554A external-priority patent/DE102004004554B4/de
Application filed by Pelikan Hardcopy Production AG filed Critical Pelikan Hardcopy Production AG
Publication of EP1725912A2 publication Critical patent/EP1725912A2/fr
Withdrawn legal-status Critical Current

Links

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
    • G03G9/0802—Preparation methods
    • G03G9/0804—Preparation methods whereby the components are brought together in a liquid dispersing medium
    • G03G9/0806—Preparation methods whereby the components are brought together in a liquid dispersing medium whereby chemical synthesis of at least one of the toner components takes place
    • 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
    • G03G9/0802—Preparation methods
    • G03G9/0815—Post-treatment
    • 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
    • G03G9/08775—Natural macromolecular compounds or derivatives thereof
    • G03G9/08782—Waxes
    • 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
    • G03G9/08793—Crosslinked polymers
    • 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
    • G03G9/087—Binders for toner particles
    • G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
    • G03G9/08797—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature

Definitions

  • the invention relates to the field of laser printing and copying technology. It relates in particular to toner particles as well as a method and a plant for their production according to the preamble of the independent claims.
  • Toners have long been known in various technical copying areas. For example, they are used in conventional copying processes (roller transfer) or are used in laser printers.
  • the toner is provided as a toner powder, which consists of the smallest toner particles, which usually have a particle size of 5 to 10 ⁇ m. Furthermore, the toner particles should have good melting properties, a minimal fixing temperature and a low gloss, good mechanical properties with regard to pulverizability, a low tendency towards so-called “housing stability", sufficient strength on the paper and good pigment compatibility.
  • the individual toner particles are essentially structured as follows: in addition to the colorant or the colorants, in particular a pigment or pigments, one or more additives are usually incorporated into the polymeric materials: these are, for example, resins, charge control substances, surface-active additives and other, substances controlling the properties.
  • additives are usually incorporated into the polymeric materials: these are, for example, resins, charge control substances, surface-active additives and other, substances controlling the properties.
  • Typical polymeric materials, which serve as a binder matrix in the individual toner particles are based on monomers or oligomers, which form a polymer matrix by polymerization, in which the colorants are incorporated.
  • the polymers formed usually have a glass transition temperature of about 50 to 70 ° C.
  • monomers or oligomers are used which are based in particular on styrene, acrylates, methacrylates and / or butadiene. In individual cases it is also advantageous to use the starting monomers or oligomers of polyester.
  • the polymeric materials serve as carrier substances for the pigments and the additives and give the individual toner particles a comparatively defined shape and size.
  • Waxes can be incorporated into the toner particles as further additives, this being understood to mean a material which is kneadable at 20 ° C, solid to brittle, hard, coarse to fine crystalline, translucent to opaque, but not glassy, and as a rule about 50 to 90 ° C, in exceptional cases also up to about 200 ° C, in the meltable, low-viscosity state without decomposition and is relatively low viscosity and not stringy just above the melting point.
  • waxes it is also possible to use substances which have appropriate physical properties or are “wax-like”.
  • waxes which can replace silicone oils
  • the introduction of waxes, which can replace silicone oils, is intended, for example, to enable the toner particles to be released from the printing roller in the customary copying processes have a significantly lower temperature during melting than the polymers forming the matrix of the toner particles and also show a different temperature-viscosity relationship.
  • the charge control substances serve to set the required charge level in the individual toner particles. This makes it possible to specifically attract the individual toner particles during the printing or copying process from the corresponding printing devices, such as the printing roller.
  • Charge control substances of this type have a predefined charge capacity, so that the toner particles are charged in a defined manner in accordance with the amount added or are attracted by a charge carrier, for example a printing roller which is charged differently on the surface in accordance with the image to be printed.
  • a charge carrier for example a printing roller which is charged differently on the surface in accordance with the image to be printed.
  • iron oxides are used as charge control substances.
  • the surface-active additives are said to impart the desirable physical property to the surface of the toner particles, in particular to promote the toner flow and the adhesion when used in copying and printing devices.
  • These are in particular silicas, titanium oxide compounds and organometallic salts. Fumed silicas, which are of particular advantage, generally have an average particle size of about 7 to 40 nm (300 to 50 m 2 / g surface area according to BET), good initial flow and low adhesion properties.
  • Pigments are preferably used as colorants. In this context, pigments are understood to mean colorants which are insoluble in aqueous media. Instead of or in addition to pigments, soluble dyes can be used.
  • the pigments contained in the toner particles preferably have a diameter of approximately 0.015 to 0.5 ⁇ m.
  • the toner particles can contain magnetic materials, such as magnetite.
  • magnetic materials such as magnetite.
  • the toner particles are used mixed with powdery magnetic material (two-component toner) as well as toners that do without iron oxide (one-component Toner).
  • the toners are produced by various and in some cases relatively complex processes:
  • the colorant in particular a pigment, such as carbon black
  • a magnetic material for example magnetite polymeric materials are extruded into a strand at an elevated temperature in an extruder. This material is then cooled. Then it is ground up in a complex process. This is followed by an aerodynamic classification with regard to the desirable particle size.
  • the toner particles are generally subjected to a further surface treatment in order to set the desired properties.
  • a disadvantage of the process just described is first of all the great energy expenditure which is required for the extrusion and grinding, and also that an exact adjustment of the toner particle size is not possible. Rather, toner particles are formed with a widely scattered particle size distribution, so that the toner particles produced have to be subjected to complex classification after they have been produced. Due to the imprecise setting options for the toner particle size, the proportion of toner particles separated or sorted out by classification, which are not suitable for further use due to their particle diameter being too small or too large, is comparatively large, so that the amount of rejects toner is high. The scrap is either returned to the manufacturing process or disposed of as hazardous waste.
  • a precise setting of the desired toner particle size should be made possible with comparatively little technical and economic effort.
  • variant A droplets, partially solidified toner particles or the solid toner particles are deposited on one another. Moving conveyor belt steered on which the polymerization reaction takes place, continued or is completed. Variant B takes up this idea in an abstract form.
  • the above object is achieved by a method according to variant A for the production of toner powder, in which the individual toner particles of the toner powder contain colorants, in particular pigments, embedded in at least one polymer, and that characterized in that a liquid phase based on a monomer and / or oligomer is provided as the starting material for the polymer, the colorants in this liquid .
  • Dispersed phase finest droplets, in particular with a predetermined droplet size, are generated from the dispersion and by irradiating the droplets with electromagnetic waves or electrons in the individual droplets, a particularly defined polymerization reaction of the monomers and / or oligomers to form the polymer is effected, the polymerized droplets that form the toner particles of the toner powder.
  • the above object is achieved by toner powder with toner particles, obtainable by the method described above.
  • part of the solution to the above object is also a plant for the production of toner powder, in which the individual toner particles of the toner powder contain pigments bound in at least one polymer, this plant being characterized by a storage container for a dispersion of colorants, in particular pigments, in a liquid phase on the basis of monomers and / or oligomers, which serve as starting materials for the polymer of the toner particles, a droplet generator connected to the storage container with a plurality of nozzles for producing the finest dispersion droplets with a particularly defined droplet size and a radiation device for irradiating the dispersion droplets produced by the droplet generator with electromagnetic Waves or electrons.
  • polymerization is the generic term for the conversion of some kind of low molecular weight compounds, namely monomers and / or oligomers, into high molecular weight compounds, ie polymers, macromolecules or polymers.
  • Polymerization can also be understood to mean a "polyreaction" with the sub-terms of polyaddition and polycondensation.
  • polymer is used for polyadducts (polyaddition products) or polycondensates. The addition reactions take place without elimination of low molecular weight compounds, often with a shift of hydrogen atoms.
  • the polyaddition products include in particular those products which are based on monomers and / or oligomers with unsaturated compounds, in particular special double bond decrease. These are, for example, monomers and / or oligomers based on acrylate, methacrylate, styrene and / or butadiene. However, there are also addition reactions in which such double bonds are not present, but rather cyclic starting monomers expand to an oligomer and later to a polymer in the course of a ring opening. Polyurethanes are to be given here as an example.
  • the polycondensation products which are less preferred as “polymers” in the context of the invention are based on a polyreaction in which condensation takes place between bi- or higher-functional monomers.
  • Important polymers that include this include polyamides, polyimides, polyesters, polycarbonates, amino plastics and phenoplasts.
  • the low-molecular compounds formed and excreted by the polycondensation must be easy to remove. In most cases it is water. Therefore, the temperature at which the hot droplets are generated must be relatively high and must remain at a comparatively high temperature in order to remove the water.
  • Oligomers are compounds in whose molecule only a few atoms or atom groups (constitutional units) of the same or different types are repeatedly linked to one another and whose physical properties change significantly when the molecular size is changed by adding or removing one or more of the constitutional units. Oligomers are deliberately obtained either by polyreactions (oligopolymerization) from one monomer or mixtures of different monomers or by degradation of polymers.
  • oligomers are already used for the generation of the droplets in the context of the invention, then care must be taken that the degree of polymerization is not too high (at elevated temperature).
  • An excessively high degree of polymerization leads to an excessively high viscosity within the droplets produced, which has an adverse influence on the droplet size and thus also on the size of the toner particles and also on their shape.
  • a high viscosity sometimes leads to the toner particles not having the desirable spherical shape.
  • An essential idea on which the invention is based is the formation of a polymer matrix, the starting monomers or oligomers being present in the liquid phase or else as the liquid phase before the polymerization, so that the colorants, in particular pigments, and, if appropriate further additives, such as charge control substances, can on the one hand be uniformly mixed with the monomers or oligomers, while on the other hand the viscosity of the liquid phase can be adjusted in such a way that suitable processes, such as the inkjet process or the bubble jet process, result from the resulting dispersion. Processes that can produce droplets with a defined droplet size.
  • a volatile liquid in particular a slightly volatile liquid
  • the share of this volatile solvent is preferably less than 15 wt .-%, in particular less than 10 wt .-%.
  • These are preferably inert liquids which have no negative influence on the desired chemical reactions.
  • These solvents are able to at least partially dissolve the monomeric and / or oligomeric starting materials and also the polymer already formed therefrom. The solvent is at least partially evaporated during curing, which accelerates the polymerization.
  • the evaporation is preferably carried out with the supply of energy, in particular thermal energy, but can also take place by itself or can be accelerated by a vacuum or a blower.
  • a solvent also promotes mixing of the monomeric and / or oligomers with the colorant (s) and the additives, so that a selection of the starting materials is less critical and mixing can take place more quickly and more cost-effectively. It is particularly advantageous if a mixture of water and a low-boiling alcohol, such as in particular isopropyl alcohol and / or isobutanol, is used as the volatile solvent.
  • ketones in particular acetone and methyl ethyl ketone, are also suitable, for example.
  • the boiling point of these inert solvents which are optionally additionally used is preferably below 125 ° C., in particular below 100 ° C.
  • Another essential idea of the invention is based on a targeted and defined polymerization reaction of the monomers and / or oligomers in the dispersion by irradiation with electromagnetic waves, such as UV rays, or electrons cause.
  • electromagnetic waves such as UV rays, or electrons cause.
  • the dose for the UV rays is preferably in the range from 0.5 to 3.5 J / cm 2 , in particular from 1.0 to 2.0 J / cm 2 .
  • the radiation dose is preferably in the range from 5 to 500 kJ / m 2 , in particular from 10 to 300 kJ / m 2 .
  • Initiators are related to the polymerization in the sense of the invention in order to start (initiate) chemical reactions and to be consumed during the initiation step, partly with incorporation of the initiators (fragments) into the resulting compounds. They are widely used in polymerization reactions.
  • an active species is generated from the initiator by chemical, thermal or photochemical reaction, which reacts with a monomer molecule to form a product to which a large number of other monomer molecules are attached.
  • the initiators include, for example, azo compounds, peroxides, hydroperoxides and peresters, furthermore so-called redox initiators, systems composed of oxidizing and reducing components, for example hydrogen peroxide / iron (II ions), in the course of which radicals are generated. Since many monomers can polymerize spontaneously without the addition of an initiator, for example also by treatment with electromagnetic waves In this case, initiators only have an accelerating effect, they are often referred to as accelerators.
  • the individual toner particles with suitable additives, such as charge control agents, crosslinking aids, chain transfer agents based on monomers and / or oligomers, so that these can be incorporated into the poly merized toner particles are incorporated. It is also possible to apply some of these additives to the surfaces of the toner particles only after the toner particles have hardened, for example by mixing or spraying. Furthermore, additional dyes can be added to the dispersion of monomers and / or oligomers and pigments in order to increase the brilliance of the toner particles, which are likewise incorporated into the polymer matrix of the toner particles.
  • suitable additives such as charge control agents, crosslinking aids, chain transfer agents based on monomers and / or oligomers
  • the present invention is not subject to any relevant restriction.
  • Dyes can also be used.
  • the colorants can be organic pigments and / or inorganic pigments.
  • suitable inorganic pigments are titanium dioxide, zinc sulfide, iron oxides, chromium oxides, nickel or chromium antimony titanium oxides, cobalt oxides and bismuth vanadates.
  • dyes which may be used, can be used for fine adjustment with regard to the desired color tones. In principle, a distinction is made between the color pigments, the inorganic color pigments, the organic color pigments and the effect pigments.
  • organic color pigments Ca-Iaked Azo, Quinacridone are preferably used for the magenta pigments, phthalocyanines are used for the cyan pigments and diarylide, monoazo and isoindoline, benzimidazolone and azo condensation product and naphthol red for the yellow pigments.
  • Organic color pigments can also be broken down according to the main main classes as follows: azo pigments, polycyclic pigments and pigments based on phthalocyanine.
  • the dyes can also be differentiated according to natural and synthetic dyes.
  • the best-known synthetic dyes include: phthalocyanines, triphenylmethanes, anthraquinones (cyan / blue), monoazo / disazo (magenta / red), Tartrazine (yellow), xanthene, disazo / polyazo, azo / metal complexes
  • the colorants used, in particular pigments, should be as finely divided as possible, 95% and in particular 99% of the colorant particles preferably having a particle size of 500 nm or less.
  • the average particle size is preferably less than 200 nm.
  • the morphology of the colorants or pigment particles can differ greatly.
  • the particles should preferably have a spherical shape.
  • the viscosity When compiling the starting materials for the dispersion of very fine droplets, which are produced in the course of the method according to the invention and are converted into the toner particles, it is advantageous to place the viscosity in an optimal range.
  • the viscosity is generally between about 1 and 50 mPas, in particular between 5 and 30 mPas.
  • This viscosity range favors a variety of processes. If the viscosity is too high, this means a higher technical effort.
  • compliance with this viscosity range means that the process product is formed in an advantageous form, for example the finished toner particles have the desired size, shape and uniformity.
  • the advantageous viscosity control can be carried out by including a low-boiling liquid.
  • droplets with high repeatability and defined droplet size can be generated from the dispersion before the polymerization, while a polymerization reaction of the monomers and oligomers in the droplets produced is triggered by the irradiation immediately after they have emerged from a corresponding droplet generator and the droplets are "frozen” in their droplet shape, so that each hardened droplet forms a toner particle of the toner powder.
  • the toner particles produced according to the invention are characterized in particular by a constant and constant particle size. Furthermore, the cured toner particles have an at least approximately uniform spherical shape, since the droplets before the polymerization reaction are at least approximately spherical in shape due to the surface tension of the dispersion, and the droplets are frozen in this spherical shape by the polymerization reaction brought about from the outside, with a particularly smooth surface on the finished toner particles.
  • the polymerization in the context of the invention is controlled taking into account all relevant parameters, for example the irradiation time and irradiance, such that the number-average molecular weight of the polymerization product obtained is preferably 3,000 to 500,000, while the weight-average molecular weight is preferably between about 5,000 and 2,000,000 lies.
  • the invention is based in particular on the idea of producing the finest droplets that are as uniform as possible and with a defined droplet size in a short time.
  • a droplet generator which has a large number of nozzles for producing the dispersion droplets, each of which is assigned a thermoelectric or piezoelectric transducer on the principle of an inkjet print head.
  • the nozzle channel of the respective nozzle is briefly contracted so strongly with the aid of the piezoelectric transducer that a dispersion droplet is expelled from the nozzle.
  • thermoelectric converter is used to disperse the dispersion contained in a nozzle channel assigned to the respective nozzle heated to the extent that a gas bubble suddenly forms in the dispersion, which leads to the ejection of a dispersion droplet from the nozzle.
  • thermoelectric or piezoelectric transducers which are used, for example, in inkjet printers, are distinguished by an extremely precise adjustment of the droplet size with a very high repeatability rate, so that finest droplets of defined droplet size from the droplet generator over a long period of time. producers can be expelled.
  • these transducers are electrically controlled to eject the droplets while the dispersion is being fed to the nozzles from a dispersion reservoir.
  • a piezo inkjet print head which is used, for example, for producing large-area printouts, is particularly suitable as a droplet generator.
  • the piezo inkjet print head is permanently installed in a holder, connected to a dispersion reservoir and sprays the droplets onto a correspondingly provided collecting device, for example a conveyor belt.
  • the droplet size of the finest droplets ejected is preferably controlled by modulating the power supply to the transducers: the droplet output of the droplet generator per second and nozzle is in the range from 1,000 to 50,000 Hz, so that a sufficient amount of droplets can be generated.
  • the trajectory of the droplets can be extended in a targeted manner so that the droplets are separated from one another for as long as possible and are evenly surrounded by the atmosphere prevailing in the room into which they are ejected. In this way, at least an initial hardening or solidification of the toner particles formed from the droplets is achieved before they collect after ejection.
  • the droplets are pre- preferably irradiated with UV rays or with electron beams.
  • irradiating the droplets with UV rays has the advantage that the polymerization reactions between the monomers and / or oligomers can be set and influenced in a targeted manner by setting a specific wavelength or a specific wavelength range and the intensity of the UV rays, so that a defined one Degree of crosslinking in the polymer of the finished toner particle is predetermined during its production and the individual toner particle can be specifically adapted to its desired area of use.
  • the finest droplets ejected electrostatically so that they repel each other through their charges.
  • the electrostatic charging is preferably carried out by applying an electric field to the outlet opening of the droplet generator, through which the droplets fly when ejected.
  • the droplets can also be electrostatically charged immediately when they are generated. If agglomerates do occur in individual cases, they can easily be destroyed by mechanical action, for example by simple grinding.
  • the droplets, the already partially solidified toner particles or the solid toner particles be directed onto a conveyor belt which preferably moves at high speed, on which they are distributed over a large area in order to carry out the solidification process or complete.
  • the solidified toner particles are then swept or smeared off the conveyor belt and then fed for further processing.
  • the conveyor belt in the case of electrostatically charged toner particles or electrostatically charged droplets with opposite polarity.
  • the droplets ejected are deposited uniformly on the conveyor belt.
  • a more heavily loaded collector for example a loaded drum
  • the droplet size of the finest droplets ejected from the droplet generator is preferably set such that the particle size of the toner particles obtained is between approximately 2 and 9 ⁇ m, in particular between approximately 4 and 7 ⁇ m.
  • the exact setting of the droplet size described above makes it possible to set the particle size of the finished toner particles in such a way that the production of toner powder with toner particles is possible, in which almost all toner particles have at least approximately the same particle size. As a result, not only can the classification of the toner particles previously required in the known methods be eliminated.
  • the reject quantity of toner particles with too small or too large a particle size tends to zero, as a result of which the production method according to the invention offers a far-reaching economic advantage over the previously known methods.
  • the use of energy is significantly lower in the process according to the invention, which makes its high economic efficiency a further significant advantage, especially in the large-scale production of toner powder offers.
  • the invention relates to a system according to claim 20 for producing toner powder, in which the individual toner particles of the toner powder are formed from pigments incorporated in at least one polymer.
  • the system according to the invention has a storage container for a dispersion of colorants, in particular pigments, in a liquid phase of monomers and / or oligomers which serve as starting materials for the polymer of the toner particles, a droplet generator connected to the storage container and having a large number of nozzles to produce the finest dispersion droplets of largely defined droplets large and an irradiation device, which serves to irradiate the dispersion droplets generated by the droplet generator with electromagnetic waves or electrons, preferably for irradiation with UV light or electron beams.
  • each nozzle of the droplet generator is assigned a piezoelectric or a thermoelectric converter, with which a pressure pulse is generated in a nozzle channel assigned to the respective nozzle by contraction or heating, by means of which a droplet of a defined size is expelled from the nozzle.
  • the transducers in order to ensure uniform droplet formation, they are combined, at least in groups, with an electrical control. With the aid of the control, voltage pulses for actuating the transducers are generated, the droplet size being set in a defined manner by changing the voltage amplitude, and the number of droplets per time unit being predefined by changing the number of pulses per unit time.
  • the use of a conventional inkjet print head as a droplet generator has proven to be particularly advantageous for droplet generation. Such inkjet print heads are characterized by a very long service life and very high repeatability. Furthermore, the droplet size can be set very precisely.
  • a mixing device for dispersing the pigments in the liquid phase based on monomers and / or oligomers into the system.
  • This mixing device can either be provided as a separate unit in which the dispersion is mixed separately from the droplet generation. Or the mixing device is connected to the reservoir of the droplet generator. It is also conceivable here for several storage containers to be supplied by several droplet generators at the same time from a common mixing device.
  • the droplets are sprayed onto a conveyor belt which preferably moves past the nozzles at high speed.
  • a conveyor belt has the advantage that the polymerization of the monomers and / or oligomers in the droplets can be decoupled in time from being ejected from the nozzles by transporting the droplets adhering to the conveyor belt away from the location of the droplet generator.
  • the irradiation device directly downstream of the droplet generator, so that the dispersion droplets can be irradiated as soon as they emerge from the droplet generator and excited for polymerization.
  • a conveyor belt it is also possible to eject the droplets into a closed irradiation room into which the irradiation device irradiates. This is advantageous, for example, if the manufacturing process is to be encapsulated from the outside.
  • the invention relates to toner powder with toner particles which have been produced by the method according to the invention.
  • FIG. 1 is a schematic representation of a system according to the invention for the production of toner powder
  • FIG. 2 shows a schematic sectional view through a nozzle body of an inkjet print head used in the system
  • Fig. 3 is a schematic sectional view of the nozzle body immediately before the dispersion droplet is ejected
  • Fig. 4 is a schematic sectional view of the nozzle body when ejecting a dispersion droplet
  • Fig. 5 is a schematic representation of a modified embodiment of the system according to the invention for the production of toner powder shown in Fig. 1.
  • FIG. 1 shows a schematic representation of a system 10 according to the invention for producing toner powder.
  • the system 10 has a storage container 12, in which a dispersion 16 is contained, which consists of the starting materials for the individual toner particles 14, the same monomers and / or oligomers, in the liquid phase, with pigments and optionally other dyes, surface-active additives, charge control agents and similar substances is formed.
  • a mixing device not shown.
  • An outlet 18 is provided near the bottom of the storage container 12 which is connected via a line system 20 to an inkjet print head 22 which serves as a droplet generator.
  • the construction and the mode of operation of the inkjet print head 22 will be briefly explained below with reference to FIGS. 2 to 4.
  • the inkjet print head 22 has a nozzle body 24 made of a piezo material, in which a multiplicity of nozzle channels 26 running parallel to one another are formed, which are in flow connection with the outlet 18 of the storage container 14 via a distributor (not shown) stand.
  • a nozzle plate 28 is attached to the end face of the nozzle body 24, in which nozzle openings 30 are provided for every second nozzle channel 26.
  • Two four electrodes 32 are assigned to each nozzle channel 26. The electrodes 32 are connected to a controller, not shown.
  • the nozzle channels 26 run parallel to one another. If a voltage is now applied to the electrodes 32 of a nozzle channel 26, the voltage causes a deformation of those which limit the nozzle channel 26 3, which leads to an increase in volume of the nozzle channel 26, so that a small amount of additional dispersion can flow from the outlet 20 into the nozzle channel 26. If the voltage applied to the electrodes 32 is switched off, the walls 34 return to their original starting position, as shown in FIG. 4, as a result of which the volume of the nozzle channel 26 is reduced again. A dispersion droplet 36 is ejected from the open nozzle opening 30.
  • the droplet size of the dispersion droplet 36 and the number of dispersion droplets 36 to be generated can be set and predefined in a very simple and very precise manner.
  • the dispersion droplets 36 emerging from the inkjet print head 22 hit a conveyor belt 38 that moves past the print head 22 at high speed.
  • the speed of the conveyor belt 38 is adapted to the emerging amount of dispersion droplets 36 in such a way that the droplets lie side by side and one behind the other on the surface of the conveyor belt 38.
  • an irradiation device 40 which irradiates the dispersion droplets 36 lying on the conveyor belt 38 with UV light of a predetermined, defined wavelength range and a defined radiation intensity.
  • a polymerization reaction is triggered between the monomers and / or oligomers in the dispersion droplets 36, the degree of crosslinking of the cured polymer being able to be defined in a defined manner by means of the wavelength range set and the radiation intensity of the UV light.
  • the cured dispersion droplets 36 form the toner particles 12 of the toner powder.
  • a collecting device 42 Arranged at the end of the conveyor belt 38 is a collecting device 42 which picks up the individual toner particles 12 from the conveyor belt 38 and guides them into a collecting container 44.
  • FIG. 5 shows a modified embodiment of the system 10 shown in FIG. 1, which differs from it only in that the irradiation means direction 40 is arranged downstream of the inkjet print head 22, so that the dispersion droplets 36 emerging from the inkjet print head 22 are irradiated with UV light immediately after they have been generated and begin to polymerize in flight.
  • the dispersion droplets 36, which polymerize in flight, then fall onto the conveyor belt 38 and are transported away from the inkjet print head 22 by this.
  • the system 10 shown and its modification represent only one possible embodiment of the system according to the invention for the production of toner powder.
  • a so-called bubble jet print head instead of the described inkjet print head 22.
  • the irradiation device 40 for irradiating the conveyor belt 38 with electron beams. In this case, the radiation area would have to be sealed off from the outside.
  • the dispersion droplets can float after exiting the printhead, so that they can be irradiated in the floating state and begin to cure.
  • the individual toner particles of which contain at least one colorant, in particular at least one pigment, which is incorporated in at least one polymer a liquid phase based on a monomer and / or oligomer is provided as the starting material for the polymer at least one colorant is dispersed in this liquid phase, the dispersion is applied to a surface, cured thereon by means of polymerization and then removed from the surface.
  • any additives required for the production of the toner powder are preferably added to the liquid phase, preferably before the colorant is dispersed therein.
  • the term dispersion is to be interpreted broadly in the present context. It can be a heterogeneous mixture between a solid or liquid colorant and the liquid phase. In general, however, there will be a homogeneous mixture in which the colorant dissolves or disperses in the liquid phase.
  • Toner powder can thus be produced particularly inexpensively.
  • the dispersion contains a solvent which is preferably able to dissolve the polymer formed or to be a solvent for the monomers and / or oligomers still present.
  • the solvent is at least partially evaporated during curing, which accelerates the polymerization.
  • the evaporation is preferably carried out with the supply of energy, in particular thermal energy, but can also take place by itself or can be accelerated by a vacuum or a blower.
  • a solvent also promotes mixing of the monomers and / or oligomers with the colorant (s) and the additives, so that selection of the starting materials is less critical and mixing can take place more quickly and more cost-effectively.
  • the monomer and / or oligomer advantageously also has solvent properties in order to facilitate or improve dispersion of the colorant and / or the additives.
  • the solvent is therefore to be understood as meaning a solvent added in addition to the monomer and / or oligomer, which can be evaporated independently of the monomer and / or oligomer.
  • the dispersion is applied to the surface with an application thickness which corresponds at least approximately to a diameter of the toner particles to be produced. It is preferably taken into account whether the dispersion shrinks or expands during curing, and depending on the thickness of the applied layer, which is larger or smaller than the diameter of the toner particles to be produced.
  • the dispersion is preferably applied over the entire surface to the surface and, after removal, is comminuted, preferably ground.
  • “essentially full-area” is to be understood to mean that a predominant part of the surface, preferably more than 80 percent, is covered with the dispersion.
  • a comprehensive, gap-free application is not absolutely necessary.
  • a flat intermediate product is formed, the dimensions of which in one direction already correspond to those of the toner particles to be produced.
  • This flat intermediate product is comminuted in a further process step in order to obtain toner particles with the desired diameter. This is preferably done by grinding Already correct dimensions in one direction, the comminution can take place with far less energy and machine wear than would be the case with a complete comminution of a voluminous intermediate product, as is the case with a conventional method falls.
  • the dispersion is applied to the surface in the form of isolated droplets.
  • An average droplet diameter is chosen so that it corresponds at least approximately to a particle diameter of the toner particles to be produced.
  • preference is given to whether the dispersion is cured shrinks or expands, and depending on whether the mean droplet diameter is larger or smaller than the diameter of the toner particles to be produced, so that the toner particles of the desired size are preferably formed after curing. This procedure completely eliminates the need for the grinding process, so that the toner powder can be produced particularly efficiently and inexpensively.
  • a droplet generator which has a large number of nozzles for producing the dispersion droplets, each of which has a piezoelectric or thermoelectric nozzle based on the principle of an inkjet print head Converter is assigned.
  • the nozzle channel of the respective nozzle is briefly contracted so strongly with the aid of the piezoelectric transducer that a dispersion droplet is expelled from the nozzle.
  • the dispersion contained in a nozzle channel assigned to the respective nozzle is heated with the help of the thermoelectric converter to such an extent that a gas bubble suddenly forms in the dispersion, which leads to the ejection of a dispersion droplet from the nozzle.
  • thermoelectric or piezoelectric transducers which are used, for example, in inkjet printers, are distinguished by an extremely precise adjustment of the droplet size with very high repeatability, so that the finest droplets of defined droplet size can be ejected from the droplet generator over a long period of time.
  • these transducers are electrically controlled to eject the droplets while the dispersion is being fed to the nozzles from a dispersion reservoir.
  • a piezo inkjet print head is particularly suitable as a droplet generator, which is used, for example, for producing large-area printouts.
  • the piezo inkjet print head is permanently installed in a holder, connected to a dispersion reservoir and injects the Droplets on the surface, for example the surface of a conveyor belt.
  • the droplet size of the finest droplets ejected is preferably controlled by an electrical voltage curve at the converter.
  • the droplet output of the droplet generator per second and nozzle is in the range of 1,000 to 50,000 Hz so that a sufficient amount of droplets can be generated.
  • the surface in the case of electrostatically charged toner particles or electrostatically charged droplets with opposite polarity.
  • the droplets ejected are deposited uniformly on the surface.
  • a more highly charged collector for example a charged drum, it is also possible to detach the toner particles adhering to the surface from the surface after solidification and to further process them.
  • the droplet size of the finest droplets ejected from the droplet generator is adjusted so that the particle size of the toner particles obtained is between approximately 2 and 9 ⁇ m, in particular between approximately 4 and 7 ⁇ m.
  • the exact setting of the droplet size described above makes it possible to set the particle size of the finished toner particles in such a way that the production of toner powder with toner particles is possible, in which almost all toner particles have at least approximately the same particle size.
  • the reject quantity of toner particles increases or decreases too little large particle size towards zero, whereby the manufacturing method according to the invention offers a far-reaching economic advantage over the previously known methods.
  • Another essential idea of the invention according to variant B is based on bringing about a targeted and defined polymerization reaction of the monomers and / or oligomers in the dispersion applied to the surface by supplying energy, preferably by irradiation with electromagnetic waves, such as UV rays, or electrons.
  • electromagnetic waves such as UV rays, or electrons.
  • the method according to variant B has a broad agreement with the invention according to variant A with regard to the essential features.
  • the droplet size of the finest droplets, for the polymerization including all detailed details, for the additives in the polymerization, such as charge control agents and the like, for the type of colorants in the form of the dyes and pigments, for all details of the dispersion used , for setting the appropriate viscosity, for the advantages that result from the procedure according to Set variant A, for example the repetition accuracy, the type of irradiation, including the particular explanations regarding the irradiance, the molecular weights of the polymer obtained, all details of the respective section in which the mentioned feature is explained apply equally to the person skilled in the art should.
  • the features and measures that have been described above in connection with variant A should not apply to variant B if they clearly differ from the main idea.
  • part of the solution to the above object is a system for producing toner powder, in which the individual toner particles of the toner powder contain colorants, in particular pigments, incorporated in at least one polymer, this system being characterized by a storage container for a dispersion of colorants in a liquid phase Basis of monomers and / or oligomers, which serve as starting materials for the polymer of the toner particles, a droplet generator connected to the storage container with a plurality of nozzles for producing the finest dispersion droplets of defined droplet size and an irradiation device for irradiating the dispersion droplets generated by the droplet generator with electromagnetic waves or electrons ,
  • the invention relates to a system for producing toner powder, in which the individual toner particles of the toner powder are formed from pigments incorporated in at least one polymer.
  • the system according to the invention has a storage container for a dispersion of colorants, in particular pigments, in a liquid phase based on monomers and / or oligomers, which serve as starting materials for the polymer of the toner particles; a surface to which the dispersion can be applied for hardening; Means for applying the dispersion to the surface, which are connected to the reservoir and means for removing the cured dispersion from the surface.
  • Fig. 8 shows a further preferred embodiment of the system according to the invention.
  • a storage container 1 contains a dispersion formed from starting materials for the production of toner particles, namely from monomers and / or oligomers in the liquid phase, pigments and optionally solvents, further dyes, surface-active additives, charge control substances and similar substances.
  • starting materials for the production of toner particles namely from monomers and / or oligomers in the liquid phase
  • pigments and optionally solvents further dyes, surface-active additives, charge control substances and similar substances.
  • the monomers and / or oligomers, the pigments and the further constituents were mixed with one another using a mixing device (not shown).
  • a connection for a line system is provided near the bottom of the storage container 1, via which the dispersion 21 is applied to a surface 31 of a rotating drum 3.
  • a thickness of the applied dispersion layer can be adjusted to a desired value by means of a roller 4 which can be adjusted radially to the drum.
  • An energy supply device 5 serves to supply energy to the dispersion layer. This can be, for example, a warm air blower or an optical heater that supplies energy in the form of electromagnetic waves. If the dispersion 21 contains a solvent, it is sinuous if the energy supply device 5 can supply the energy primarily in the form of heat. If the dispersion 21 contains such monomers and / or oligomers in which a polymerization reaction can be triggered by irradiation, an energy supply device 5 is preferably used which can supply the energy primarily in the form of electromagnetic waves, in particular in the UV range.
  • a rotational speed of the drum 3 and the heating device 5 are preferably matched to one another and to a polymerization behavior of the dispersion 21 in such a way that the dispersion layer has completely hardened after passing through a region of the surface 31 which is covered by the heating device 5.
  • a scraper 4 scrapes the hardened dispersion layer off the surface 31. Fragments resulting from scraping are collected in a collecting container 6. The fragments are then ground in a grinder, not shown. 7 shows a preferred embodiment of the system according to the invention.
  • an ink jet print head 6 is provided for spraying the dispersion 21 in the form of isolated droplets 23 onto the surface 31 of the drum 3.
  • Appropriate control of the inkjet print head 5 enables toner particles to be produced directly in the desired size. This eliminates the need for a grinding process. Otherwise, the system functions in the same way as the system from FIG. 6 described above.
  • FIG. 8 shows a further preferred embodiment of the system according to the invention.
  • the energy is supplied by means of a combination of a hot air blower 51 and a UV lamp 52.
  • This embodiment is particularly advantageous if toner powder is to be produced from a dispersion 23 which contains both a solvent and monomers and / or oligomers which can trigger a polymerization reaction by irradiation.
  • a conveyor belt can advantageously be used, on the surface of which the dispersion 21 is applied.
  • the surface of the drum 3 or conveyor belt can advantageously also be heated from the inside, either instead of or in addition to an energy supply by the heating device 5.
  • the surface is preferably such that the hardened dispersion adheres to it as little as possible.
  • cured dispersion can be scraped off more easily or, if appropriate, detaches itself from the surface under the action of gravity, or can advantageously also be suctioned off.
  • a corresponding surface can advantageously be created by coating the drum 3 or the conveyor belt, for example with Teflon or silicone.

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

Abstract

Poudre toner dans laquelle les particules individuelles de la poudre toner contiennent des colorants incorporés dans au moins un polymère, en particulier des pigments. La matière de départ du polymère est constituée d'une phase liquide à base d'un monomère et / ou d'un oligomère. Les colorants, en particulier les pigments, sont ensuite dispersés dans cette phase liquide. Des gouttelettes extrêmement fines ayant une grosseur prédéterminée sont produites à partir de la dispersion. Une réaction de polymérisation des monomères et / ou des oligomères pour former le polymère est alors provoquée dans les gouttelettes individuelles par exposition des gouttelettes à des ondes électromagnétiques ou à des électrons, les gouttelettes polymérisées formant les particules de la poudre toner. La présente invention concerne en outre une installation de production de la poudre toner, ainsi que la poudre toner ainsi obtenue. Dans un autre mode de réalisation, la présente invention concerne un procédé de production de poudre toner dont les particules individuelles contiennent au moins un colorant incorporé dans au moins un polymère, qui comporte les étapes suivantes : une phase liquide à base d'au moins un monomère et / ou un oligomère est préparée en tant que matière de départ du polymère, au moins un colorant est dispersé dans la phase liquide et la dispersion est déposée sur une surface et durcie sur ladite surface par polymérisation des monomères et / ou des oligomères. Ensuite, le produit obtenu selon ledit procédé est détaché de la surface et broyé, en particulier moulu. La présente invention permet un ajustement précis de la taille souhaitée des particules de la poudre toner, avec un investissement technique et économique relativement minime.
EP05701239A 2004-01-29 2005-01-28 Particules de toner et procede et installation de production desdites particules Withdrawn EP1725912A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102004004554A DE102004004554B4 (de) 2004-01-29 2004-01-29 Ein Verfahren und eine Anlage zur Herstellung von Tonerpartikeln
CH02078/04A CH697051A5 (de) 2004-01-29 2004-12-15 Tonerpartikel sowie ein Verfahren und eine Anlage zu deren Herstellung.
PCT/EP2005/000857 WO2005073815A2 (fr) 2004-01-29 2005-01-28 Particules de toner et procede et installation de production desdites particules

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EP1725912A2 true EP1725912A2 (fr) 2006-11-29

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JP4607029B2 (ja) 2005-03-17 2011-01-05 株式会社リコー トナー製造方法、トナー、及びトナー製造装置
JP4209405B2 (ja) 2005-04-22 2009-01-14 株式会社リコー トナー、トナーの製造方法、及びトナーの製造装置

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CN2658786Y (zh) * 2002-06-10 2004-11-24 精工爱普生株式会社 调色剂制造装置

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