DE102005034407A1 - Toner powder e.g. black toner powder, manufacturing method for e.g. laser printer, involves dissolving or dispersing polymer material and colorant in liquid medium, and hardening component in solution or dispersion by evaporating medium - Google Patents

Abstract

The method involves dissolving or dispersing a polymer material and a colorant together with an additive in a liquid medium. A solution or the dispersion (16) is extensively applied on a surface in the form of isolated droplets that are produced by a rotary silk-screen printing process. A component e.g. nozzle body (24), contained in the solution or the dispersion is hardened by partial evaporation of the liquid medium, and subsequently removed from the surface, where the evaporation takes places under supply of heat energy. Independent claims are also included for the following: (1) a system for manufacturing a toner powder, comprising a storage container (2) a toner powder comprising toner particles.

Description

The The present invention relates to the field of laser printing and copying technology. It particularly relates to toner particles and a method and a plant for their production. Toners have long been in different known technical copy areas. This is how they become, for example at conventional Copy process (roll transfer) used or used in laser printers. The toner is provided as toner powder consisting of minute toner particles which is usually a particle size of 5 up to 10 μm exhibit. Furthermore, the toner particles should have good melting properties, a minimum fixing temperature and a low gloss, good mechanical Properties with regard to pulverizability, a small one Tendency to the so-called "Housing Stability ", one sufficient strength on the paper and good pigment compatibility exhibit.

The individual toner particles are composed essentially as follows: in addition to the colorant or colorants, in particular a pigment or Pigments are usually one or more in the polymeric materials Additives involved: These are for example Resins, charge control agents, surfactants and additives further properties controlling substances. Typical polymeric materials, which serve as a binder matrix in the individual toner particles, start from monomers or oligomers, which by polymerization form a polymeric matrix in which the colorants incorporated become. Usually the polymers formed have a glass transition temperature of about 50 to 70 ° C. For the preparation of the polymer matrix are monomers or oligomers used, in particular based on styrene, acrylates, Methacrylates and / or butadiene based. In individual cases is it is also advantageous to use the starting monomers or oligomers of polyesters consulted.

The polymeric materials serve as vehicles for the pigments and the additives and give the individual toner particles one comparatively defined shape and size.

When other additives can be incorporated into the toner particles waxes, including a material is understood that at 20 ° C kneadable, firm to brittle, hard, coarse to fine crystalline, translucent to opaque, however is not glassy and usually at about 50 to 90 ° C, in exceptional cases, too up to about 20 ° C, in the meltable, low viscous state passes without decomposition and already slightly above the melting point relatively low viscosity and not stringy. In place of waxing can also such substances are used, the corresponding physical Possess properties or are "wax-like" are the introduction of waxes, the silicone oils can replace should, for example, the release of the toner particles from the pressure roller at the usual Enable copying. Waxes have a much lower temperature when melting than the polymers forming the matrix of the toner particles. they show also a different temperature-viscosity relation.

The Charge control fabrics serve to adjust the required Charge levels in the individual toner particles. This makes it possible, the individual toner particles during printing or copying of the corresponding Pressure devices, such as the pressure roller to tighten targeted. such Charge control materials have a predetermined charge capacity, so that defines the toner particles according to the amount added charged or by a charge carrier, for example a corresponding the image to be printed on the surface differently charged Pressure roller, be attracted. As charge control materials For example, iron oxides used.

The surface-active additives are said to impart the desirable physical property to the surface of the toner particles, particularly favoring toner flow and adhesion when used in copying and printing equipment. These are, in particular, silicic acids, titanium oxide compounds and organometallic salts. Pyrogenic silicas, which are of particular advantage, generally have an average particle size of about 7 to 40 nm (300 to 50 m ² / g BET surface area), good initial flow and low adhesion properties.

When Colorants are preferably used pigments. As pigments become in this connection in aqueous media insoluble colorants Understood.

Instead of from or in addition to pigments soluble Dyes are used. Those contained in the toner particles Pigments preferably have a diameter of about 0.015 to 0.5 μm.

Further, in the case of the single-tone toner, the toner particles may contain magnetic materials such as magnetite. There are applications in which the magnetic material is not directly contained in the toner particles but the toner particles are mixedly used in use with powdery magnetic material (two-component toner) as well as To ner, which do without iron oxide (one-component toner).

The toners are produced by different and sometimes relatively expensive processes:
In the most widely used process, the colorant, especially a pigment such as carbon black, is extruded into a strand together with charge controlling agents, wax or a magnetic material such as magnetite with polymeric materials at elevated temperature in an extruder. This material is then cooled. Thereafter, it is crushed consuming in a grinding process. This is followed by aerodynamic classification with regard to the desirable particle size. Thereafter, the toner particles are generally subjected to a further surface treatment to set the desired properties.

adversely in the described method, first of all the great expenditure of energy, the for requires extruding and grinding becomes.

adversely in the described method is also that a precise setting the toner particle size is not possible is. Rather, toner particles with a widely scattered arise particle size distribution, so that the toner particles produced after their preparation a must undergo elaborate classifications. Due to the inaccurate settings the toner particle size is the Proportion of toner particles deposited or sorted by classifying, due to their too small or too large particle diameter for the further Use are not suitable, comparatively large, so that the amount of rejects is high. The committee will either be in recycled or the manufacturing process as hazardous waste disposed of expensively.

One Another disadvantage of the known method, in which from a Extruded base by crushing and grinding toner particles be created, is that the toner particles on the one hand a rough surface and therefore tend to cake together. To the others are formed especially when crushing and grinding the matrix finest dusts, which to avoid health problems of the employees and elaborately filtered out to prevent dust explosions must be, so that usually in the big industrial scale conducted Production of the toner is very expensive and expensive.

It It is therefore an object of the invention to provide a method and a system, the economical production of high-quality toner powder enable. Furthermore, a correspondingly produced toner powder is specified become.

The above-mentioned object is achieved by a method according to claim 1 and by a system according to claim 13 solved. With respect to the toner powder, the object is achieved by the object of claim 16 solved.

at the method according to the invention for producing toner powder whose individual toner particles are at least Contain colorant which is incorporated in at least one polymer is a polymer material and the at least one colorant, especially together with additives, in a liquid medium solved or dispersed, the solution or the dispersion is applied to a surface which is in the solution or the dispersion contained ingredients by at least partial evaporation of the liquid Hardened medium and subsequently from the surface ablated.

Out the older, subsequently published Application with file number PCT / EP 2005/000 857 is a procedure for producing toner powder, which is based on that as starting material a liquid Phase provided based on at least one monomer and / or oligomer and the colorant is dispersed in this liquid phase. The curing the dispersion is carried out by polymerization of the monomer and / or Oligomer.

Of the Difference to this method is that in the inventive method the curing not by a chemical reaction (polymerization), but by a physical process, namely by evaporation of the liquid Medium takes place, so that in the solution or in the dispersion cure contained ingredients.

For the preparation of the toner powder optionally required additives such as resins, charge control agents, surface-active additives, waxes, magnetic materials and other properties controlling substances are preferably the liquid medium, admixed, preferably before the colorant is dissolved or dispersed. The term dispersion is to be interpreted broadly in this context. It may be a heterogeneous mixture (mixture) between a solid or liquid colorant and the liquid phase. In general, however, a homogeneous mixture (solution) will be present, in which the solid or liquid colorant has dissolved in the liquid phase, be it by physical solution, which may be ver with a phase transition or by a chemical solution in conjunction with ionization or chemical reaction. The term polymeric material is also to be understood broadly and includes one or more different polymers.

There the process of one, preferably at room temperature, liquid medium starting, which is the polymer material and the at least one colorant solved or is dispersed, which eliminates the Energy- and machine-consuming extrusion, the conventional Method according to the prior art is necessary. Thus, toner powder can be especially economical getting produced. The evaporation of the liquid medium is preferably carried out under supply of energy, in particular heat energy, but can also take place by itself or accelerated by negative pressure or a blower become.

In a preferred development of the method according to the invention becomes the solution or dispersion applied to the surface with an application thickness, the least approximate corresponds to a diameter of the toner particles to be produced. in the Case of the dispersion is preferably taken into account whether it shrinks during curing or expanding and working with a job thickness, the larger or smaller than the diameter of the toner particles to be produced.

Preferably becomes the solution or the dispersion is applied substantially over the entire surface of the surface and crushed after removal, preferably crush. Under "essentially Full surface "is in the present Understand that a majority of the surface, preferably more than 80 percent, with the solution or the dispersion is covered. A nationwide, gapless However, application is not essential. Due to the Application thickness arises after detachment from the surface flat Intermediate whose dimensions in one direction already those correspond to the produced toner particles. This flat intermediate is comminuted in a further process step to toner particles with the desired To get diameter. This is preferably done by grinding. Due to the already correct dimensions in one direction can comminution takes place with much less energy input and machine wear, than this when complete Crushing a voluminous intermediate the case would be as is the case with a conventional one Method arises.

In a particularly preferred further development of the method according to the invention becomes the solution or the dispersion is applied to the surface in the form of isolated droplets. This will be a mean droplet diameter chosen so that he at least approximately corresponds to a particle diameter of the toner particles to be produced. Preferably, it is also considered here whether the dispersion during curing shrinks or expands and, as the case may be, with a mean droplet diameter worked, the larger or smaller is the diameter of the toner particles to be produced, so that preferably after curing the toner particles in the desired Size arise. This procedure is omitted the need for the milling process completely, leaving the toner powder particularly efficient and cost-effective can be produced.

there is it to produce as possible even, finest droplet with defined droplet size in a short time Time particularly advantageous to use a droplet generator, which is used to generate the solution or dispersion droplets a variety of nozzles having, according to the principle of an inkjet printhead each associated with a piezoelectric or thermoelectric converter is. This is how the piezo inkjet

method with the help of the piezoelectric transducer, the nozzle channel of the respective nozzle for a short time contracted so much that a droplet is expelled from the nozzle. In the so-called bubble inkjet process is using the thermoelectric converter associated in one of the respective nozzle nozzle channel contained solution or Dispersion so far heated, that suddenly a gas bubble is formed in the dispersion or the solution, which to an ejection of a droplet the nozzle leads.

such thermoelectric or piezoelectric transducers, for example are used in inkjet printers are characterized by a very precise setting the droplet size with a lot high repeat accuracy, so that over a long period finest droplet defined droplet size from the droplet generator pushed out can be. To set the solution or the amount of dispersion per droplet to be generated become these transducers electrically driven to expel the droplets while the solution or the dispersion of the nozzles fed to a reservoir becomes.

It has been shown that a droplet generator is particularly well suited to a piezo inkjet printhead which is used, for example, for producing large-area prints. The piezo inkjet printhead is for this purpose permanently installed in a holder, connected to a reservoir or a storage container and injects the droplets onto the surface, for example the surface of a conveyor belt. The Droplet size of the ejected finest droplets is preferably controlled by an electrical voltage waveform at the transducer. The drop ejection of the droplet generator per second and nozzle is in a range of 1,000 to 50,000 Hz to allow a sufficient amount of droplets to be produced.

Around will prevent agglomeration of the droplets produced proposed in a variant of the method according to the invention, the ejected ones finest droplets to charge electrostatic so that they pass each other through repel their charges. The electrostatic charging is preferably carried out by applying an electric field at the exit opening of the droplet generator, through that the droplets when ejecting fly through. Furthermore, can the droplets be charged electronically as soon as they are generated.

Of Further, it is proposed that the surface in the case of electrostatic charged toner particles or electrostatically charged droplets against these opposite polarity charge. By loading the conveyor belt is achieved that the rejected ones droplet on the surface precipitate evenly. By reversing the charge polarity of the surface or by passing the surface at a stronger it is charged collector, such as a charged drum furthermore possible, the on the surface to dissolve adhering toner particles after solidification of the surface and for further processing.

alternative It is suggested that the droplets during their Flight, for example in free fall, to the extent that they harden, i. the liquid ones Vaporizing ingredients that they already have at least partially cured on the surface incident.

alternative for using nozzles, which work on the principle of an inkjet printhead, the isolated droplets by a screen printing method, in particular by a rotary screen printing method, be generated. This embodiment the invention is particularly economical. The can in the context of droplet production through nozzles measures described to prevent the agglomeration of the droplets produced, in particular by electrostatic charging, even in the production of isolated droplet be used by the screen printing process.

It has proved to be useful if the liquid Medium methyl ethyl ketone, especially 80% methyl ethyl ketone and 20% toluene.

The relationship of the liquid Medium to the rest Ingredients can range from 70:30 to 99: 1 and especially 90:10. The choice of a suitable ratio depends on the particular application parameters, in particular the required viscosity the solution or of the dispersion and is made accordingly by the person skilled in the art. The range limits can also be vary, with a lower proportion than the above lower limit of 70% possible and by the for limits the processing required viscosity of the solution or the dispersion is. The upper limit of 99% is in terms of economy of the process can be seen and still technically further increased be, though

costs the economy. A particularly convenient ratio between the liquid medium and the rest Ingredients is 90:10.

The Colorant may be carbon black, i. Carbon black, especially for black Toner powder, pigments, in particular for colored toner powder and magnetite, especially for black magnetic toner powder. The polymer material may be polyester resin, in particular partially crosslinked polyester resin and / or a styrene-acrylic copolymer, in particular a partial one crosslinked styrene-acrylic polymer. The additives can be Wax material, in particular polypropylene wax and / or polyethylene wax and / or polyamide wax, and / or a charge control substance, in particular Chromium complexes and / or iron complexes for negatively charged toner powders, quaternary Ammonium salt for positively charged toner powders and zinc complexes.

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 about 2 and 9 μm, in particular between about 4 and 7 μm. As has been shown, by the exact droplet size adjustment described above, it is possible to adjust the particle size of the finished toner particles to allow the production of toner powder with toner particles in which nearly all toner particles have at least approximately the same particle size. This not only eliminates the need to classify the toner particles previously required in the known methods. In addition, the rejects amount of toner particles with too small or too large particle size to zero, whereby the manufacturing method of the invention offers a far-reaching economic advantage over the previously known methods. Furthermore, the energy input compared to the known methods, in particular the very energy-intensive, previously be described extruding polymer granules and grinding the polymer granules to toner particles, in the inventive method significantly lower, whereby its high efficiency, especially in the large-scale production of toner powder offers a further significant advantage.

Of others can the solution or the dispersion of polymeric material and colorant additional Dyes are added to the brilliance of the toner particles to increase, which are also incorporated into the polymer matrix of the toner particles.

Regarding the The pigments used are not subject to the present invention relevant restriction. These may be organic pigments and / or inorganic Pigments act. As inorganic pigments come, for example Titanium dioxides, zinc sulphide, iron oxides, nickel or chromium antimony titanium oxides, Cobalt oxides and bismuth vanadates into consideration. As organic pigments can For example, phthalocyanine pigments or carbon black are used.

The used pigments should be finely divided preferably 95% and in particular 99% of the pigment particles a particle size of the same or less than 500 nm. The mean particle size is preferably at a value of less than 200 nm. Dependent Of the particular pigment used, the morphology of the Pigment particles very different. To a cheap one viscosity behavior to obtain the addressed dispersion, the particles should preferably spherical Own shape.

at the composition of the starting materials for the solution or dispersion, the in the context of the method according to the invention generated and on the surface is applied, it is advantageous to the viscosity in one optimal setting, especially if the solution or the dispersion is applied to the surface in the form of isolated droplets becomes. The viscosity is dependent the temperature at which the finest droplets impact the surface generally between about 1 and 50 mPa s, in particular between 5 and 30 mPa s. This viscosity range favors a variety of processes. is the viscosity Too high, then it means a higher technical effort. On the other hand, compliance with this viscosity framework means that the process product is advantageously formed, For example, the finished toner particles have the desirable size, shape and have unity. An adjustment of the viscosity can thereby for example, advantageously by a corresponding change the solvent content respectively.

The inventive plant for the production of toner powder in which the individual toner particles of the toner powder at least one incorporated in at least one polymer Containing colorant is essentially due to the fact that a reservoir for a liquid

medium is provided in the polymer material and the at least one colorant, in particular together with additives, dissolved or dispersed. Further is a surface provided on which the solution or dispersion can be applied, and connected to the reservoir Means for applying the solution or the dispersion on the surface. For the purpose of curing the in the solution or components contained in the dispersion has the facility a means for at least partially vaporizing the liquid medium , wherein the means for at least partially evaporating the liquid medium is designed to cure one in the solution or in the dispersion components by evaporation sufficient Energy is provided. Furthermore is a means of removing the hardened components from the surface intended.

These inventive plant is especially for the implementation the method according to the invention suitable and has those described in connection with the method Advantages.

The Polymer material and the colorant may also be present in a feed line to the surface or before entering the supply line, at least before application on the surface, be brought together. It is essential that the starting materials in solution or dispersion applied to a surface and partially Evaporation of the liquid Hardened medium becomes.

Preferably include the means for applying the solution or dispersion the surface a variety of nozzles for producing the finest droplets, preferably predetermined size. By Setting the nozzle parameters can target the droplet size be controlled so that this embodiment of the invention a particularly flexible production of the droplets allowed.

The Means for applying the solution or dispersion on the surface may alternatively comprise a screen printing device, in particular a rotary screen printing apparatus, whereby a particularly economical production of the droplets is made possible.

The invention will be described below with reference to exemplary embodiments with reference to the attached FIGS th schematic drawings with further details.

It demonstrate:

1 a schematic representation of an embodiment of a plant according to the invention for the production of toner powder,

2 a schematic section through a nozzle body of an inkjet printing head used in the system;

3 a schematic section of the nozzle body immediately before the ejection of the dispersion droplet;

4 a schematic section of the nozzle body during the ejection of a dispersion droplet;

5 a schematic representation of a modified embodiment of in 1 illustrated inventive plant for the production of toner powder;

6 a schematic representation of another embodiment of a system according to the invention; and

7 a schematic representation of a modified embodiment of the system according to 6 ,

1 shows a schematic representation of a plant according to the invention 10 for the production of toner powder. The attachment 10 has a reservoir 12 in which a solution or a dispersion 16 which contains the starting materials for the individual toner particles 14 , Polymer material, pigments and optionally further dyes, surface-active additives, charge control substances and similar substances, as well as from a liquid medium is formed, in which the aforementioned components are dissolved or dispersed. In order to achieve the most uniform possible mixing of the resulting solution or dispersion 16 To achieve the polymer material, the pigments and the additives are mixed together with a mixing device, not shown.

Near the bottom of the storage tank 12 that is an outlet 18 provided by a pipe system 20 with an inkjet printhead serving as a droplet generator 22 communicates. The structure and operation of the inkjet printhead 22 is described below with reference to the 2 to 4 briefly explained.

As the 2 to 4 show, has the inkjet printhead 22 a nozzle body made of a piezomaterial 24 , in which a plurality of parallel juxtaposed nozzle channels 26 is formed, which with the outlet 18 of the storage container 14 be in fluid communication via a distributor, not shown. At the front of the nozzle body 24 is a nozzle plate 28 fixed, in which nozzle openings 30 for every second nozzle channel 26 are provided. Every nozzle channel 26 each are two four electrodes 32 assigned. The electrodes 32 are connected to a controller, not shown.

At rest, as he is in 2 is shown, run the nozzle channels 26 parallel to each other. Will now to the electrodes 32 a nozzle channel 26 applied a voltage, the voltage causes a deformation of the nozzle channel 26 bounding walls 34 like it 3 shows, leading to an increase in volume of the nozzle channel 26 leads, leaving a small amount of additional dispersion from the outlet 20 in the nozzle channel 26 can flow in.

Will that be on the electrodes 32 switched off voltage, take the walls 34 again their original starting position, like 4 shows, reducing the volume of the nozzle channel 26 is diminished again. This is from the open nozzle opening 30 a dispersion droplet 36 pushed out. By adjusting and modulating the voltage at the electrodes 32 For example, changing the voltage amplitude of the voltage pulses or the number of pulses per unit time, in a very simple and very accurate way, the droplet size of the dispersion droplet 36 and the number of dispersion droplets to be generated 36 be set and specified.

As 1 further shows that hit the inkjet printhead 22 exiting dispersion droplets 36 on a high speed printhead 22 moving conveyor belt 38 on. The speed of the conveyor belt 38 is thus the exiting amount of dispersion droplets 36 adapted so that the droplets in a surface next to each other and one behind the other on the surface of the conveyor belt 38 rest.

In the transport direction T of the conveyor belt 38 is a print head 22 downstream heat source 40 intended. Through the heat source 40 be on the conveyor belt 38 arranged droplets 36 heated in such a way that the evaporation temperature of the liquid medium is achieved. As a result of the subsequent evaporation of the liquid medium, the constituents contained in the solution or in the dispersion, ie in particular the polymer material and the colorant, cure so that after evaporation the hardened droplets 36 the toner particles 12 of the toner powder. The curing thus takes place in the context of this process or the system by a physical process.

At the end of the conveyor belt 38 is a collection facility 42 arranged, which are the individual toner particles 12 from the conveyor belt 38 picks up and into a collection container 44 passes.

The heat source 40 , So the means for at least partially evaporating the liquid medium comprises an in 1 Control device, not shown, which enables control or regulation of the energy input into the droplets in dependence on the evaporation temperature of the respectively selected liquid medium.

The heat source 40 , ie the means for at least partial evaporation of the liquid medium, is designed with respect to its performance so that sufficient for evaporating the liquid medium energy of the applied to the surface of the conveyor belt or the drum solution or dispersion layer can be supplied. It should be noted that the size of the energy input is determined by the fact that it is a physical process during the curing of the components contained in the solution or in the dispersion, in which the liquid medium contained in the solution or in the dispersion is evaporated. The power of the heat source is thus determined by the particular evaporation temperature of the liquid medium and the geometry of the surface exposed to the heat source.

It is possible, too, The conveyor belt even as a heat source form, in such a way that the surface of the conveyor belt is heated on the droplets incident. This can for example be arranged below the surface Heating coils done. Instead of the conveyor belt can also be heated Substrate used werdwen.

In 5 is a modified embodiment of the in 1 illustrated plant 10 shown, which differs from this only in that the heat source 40 the inkjet printhead 22 is directly downstream, so that from the inkjet printhead 22 exiting dispersion droplets 36 Immediately after their production, that is before they hit the conveyor belt 38 to be warmed up and begin to cure already in flight. The at least partially cured dispersion droplets in flight 36 then fall onto the conveyor belt 38 and are by this from the inkjet printhead 22 transported away.

The illustrated plant 10 as well as their modification represent only one possible embodiment of the inventive plant for the production of toner powder. So it is conceivable, for example, instead of the described inkjet printhead 22 to use a so-called Bubblejet printhead. Furthermore, by static charging of the dispersion droplets during their generation and by applying an electric field in the region of the printhead, a suspension of the dispersion droplets after exiting the printhead can be achieved, so that a percentage of the droplets can be pre-dried in the suspended state. The final drying or drying of the majority of the droplets takes place after the particles have hit the heated surface. For the purposes of the invention, therefore, at least a portion of the liquid medium is applied to the conveyor belt or to the surface of the substrate and there carried out the evaporation of the solvent.

6 shows a further example of a system according to the invention for carrying out the method according to the invention.

A storage container 1 contains, as related to 1 describes a solution or dispersion formed from the starting materials for the production of toner particles, whose components are mixed together or mixed with a mixing device, not shown.

Near the bottom of the storage tank 1 a connection for a line system is provided, via which the solution or the dispersion 21 on a surface 31 a rotating drum 3 is applied. By means of a radially adjustable drum to the drum 4 For example, a thickness of the applied dispersion layer can be adjusted to a desired value.

A power supply device 5 , in particular a heat source, serves to supply energy to the dispersion layer. This may be, for example, a hot air blower or a radiant heater. With regard to the design of the power, the statements in connection with the system also apply to this heat source 1 to 5 ,

The rotational speed of the drum 3 and the heater 5 are preferably so on each other and on the curing behavior of the dispersion 21 Tuned that the dispersion layer after passing one of the heater 5 covered area of the surface 31 completely cured.

A scraper 4 Finally, scrap the cured dispersion layer from the surface 31 from. Fragments resulting from the scraping are stored in a container 6 collected. Subsequently, the fragments are ground in a grinder, not shown.

7 shows a modified form of the plant after 6 , In this embodiment, an ink jet print head 6 for spraying the solution or dispersion 21 in the form of isolated droplets 23 on the surface 31 the drum 3 intended. By suitable control of the inkjet printhead 5 So toner particles can be made directly in the desired size. The necessity of a milling process is thus eliminated. Otherwise, the system works like the system described above 6 ,

In all of the described embodiments, instead of the rotating drum 3 Also, a conveyor belt may be used, on the surface of which the solution or dispersion 21 is applied. The surface of the drum 3 or the conveyor belt can advantageously also be heated from the inside, either instead of or in addition to a power supply by the heater 5 , Preferably, the surface is such that the cured dispersion adheres to this as little as possible. As a result, the cured dispersion can be scraped off more easily or optionally dissolves under the action of gravity alone from the surface, or can advantageously also be filtered off with suction. A corresponding surface can be advantageously by coating the drum 3 or the conveyor belt, for example with Teflon or silicone create.

Of the Basic construction of a toner formulation suitable for use with the invention includes the following components.

When Main component is a so-called "toner resin" (toner resin), in particular a thermoplastic with a glass transition temperature between 50 ° C up to 80 ° C and a softening range depending on the fixing temperature of the printer from about 140 to 220 ° C, typically 180 ° C. The proportion of toner resin is preferably over 90%. The use of toner with fillers, partly with functional Properties such as magnetic iron oxide is also possible.

The Toner resin satisfied the function of a binder.

When another component is an additive in the form of a wax used and in concentrations up to about 5%. In addition to the already mentioned waxes can also syntethical oligopolymers with melting points from 90 ° C to 150 ° C (PE and PP) be used. Such additives serve as release agents or Anti-offset agent. This means that when the toner melts the wax "sweats out" and a separating layer forms between the heated fuser roll and the softened toner, which is rolled on the paper.

A another component of a typical toner formulation is the charge control material, which is usually in the form of organic metal complexes, and proportionally in an amount of 1 to 4%, typically 2%. The charge control substance has the function, the triboelectric charging of the particles in terms of level and consistency to transfer the toner particles from the storage tank eventually to control the paper.

Finally includes the toner formulation is a colorant, e.g. Black carbon black, and copper phthalocyanine in cyan as a coloring substance.

Without to exclude the addition of other substances, the above explained Base formulation preferably only from these ingredients. this has the advantage that due to the relatively small number of components possibly undesirable Interactions are kept low.

By so-called Post Additive Blendings, of which one is a mechanical one Subsets and adherence of functional substances on the toner particle surface, such as z. B. flow aids, in particular fumed silica (Aerosile), understands the flow characteristics, the charge, compacting during storage, moisture absorption, abrasion, the lubricating effect, etc. controlled.

in the Within the scope of the invention it is also possible to discrete particles over a to produce so-called "emulsion path". there The toner raw materials are dispersed in a solvent, wherein this term is to be evaluated comprehensively. A solution then also includes a Molecular dispersion. The toner raw materials are in the solvent z. T. also solved, wherein the dispersion is in a different solvent with the former has a larger miscibility gap, is dispersed or emulsified. By coating this emulsion in the manner described above discrete particles with the solvents Toluene and water are generated.

It is also conceivable that post additives in solvents z. B. in toluene or water and to bring them during the drying process, at least for partial "salting out" (when added to toluene) or "drying" (when added to water) on the toner particle surface. The conventional mechanical post additive blending as the last production step could then also ent fall.

1

reservoir

3

drum

31

surface

4

roller

5

The power supply apparatus

6

receptacle

7

Inkjet printhead

8th

scraper

10

investment

12

toner particles

14

Mixer reservoir

16

Solution or dispersion

18

RühreinrichtungAuslaß

20

outlet pipe

22

Inkjet printhead

24

nozzle body

26

nozzle channels

28

nozzle plate

30

orifices

32

electrodes

34

walls

36

dispersion droplets

38

conveyor belt

40

irradiation device

42

collecting device

44

Clippings

51

Heat Guns

52

UV lamp

T

transport direction

Claims (16)

Process for the preparation of toner powder, the individual toner particles at least one, in at least one polymer Included colorant and which following steps includes: - one Polymer material and the at least one colorant are, in particular together with additives, dissolved in a liquid medium or dispersed, - the solution or the dispersion is applied to a surface, - in the the solution or component contained in the dispersion are characterized by at least partial evaporation of the liquid Solidified medium and then - of the surface ablated. Method according to claim 1, characterized in that that a job thickness of the solution or the dispersion of the order of magnitude a particle diameter of the toner powder to be produced is selected, wherein preferably the application thickness is less than twice Particle diameter. Method according to claim 1 or 2, characterized that - the solution or the dispersion is applied to the surface essentially completely becomes - and after removal from the surface a comminution, preferably by grinding, takes place. Method according to claim 1 or 2, characterized that the solution or the dispersion substantially in the form of isolated droplets the surface is applied, wherein an average droplet diameter on the order of a Particle diameter of the produced toner powder is selected, preferably smaller than twice the particle diameter. Method according to at least one of the preceding Claims, characterized in that the isolated droplets are ejected from nozzles, which according to the principle of an ink jet print head, preferably based on piezo or thermoelectric transducers, work. Method according to at least one of claims 1 to 4, characterized in that the isolated droplets a screen printing method, in particular by a rotary screen printing method, be generated. Method according to at least one of the preceding Claims, characterized in that the liquid medium is methyl ethyl ketone, especially 80% methyl ethyl ketone and 20% toluene. Method according to at least one of the preceding Claims, characterized in that the ratio of the liquid medium to the rest Ingredients in a range of 70:30 to 99: 1 and in particular 90:10. Method according to at least one of the preceding Claims, characterized in that the colorant carbon black, in particular for black Toner powder, pigments, in particular for colored toner powder, and Magnetite, especially for black magnetic toner powder. Method according to at least one of the preceding Claims, characterized in that the polymer material is polyester resin, especially partially crosslinked polyester resin. Method according to at least one of the preceding Claims, characterized in that the polymer material is a styrene-acrylic copolymer, in particular a partially crosslinked styrene-acrylic copolymer. Method according to at least one of the preceding according to claims, characterized in that the additives comprise a wax material, in particular polymer wax and / or polyethylene wax and / or polyamide wax, and / or a charge control material, in particular chromium complexes and / or iron complexes for negatively charged toner powder, quaternary nitrogen salt for positively charged toner powder and zinc complexes. Plant for the production of toner powder, in which the individual toner particles of the toner powder contain at least one colorant incorporated in at least one polymer, comprising a reservoir for a liquid medium in which polymer material and the at least one colorant, in particular together with additives, are dissolved or dispersed are, - a surface ( 13 ) on which the solution or dispersion ( 21 . 22 ) can be applied, - with the reservoir ( 1 associated funds ( 61 . 62 ) for applying the solution or dispersion ( 21 . 22 ) on the surface ( 31 ), Means for at least partially vaporizing the liquid medium for the purpose of curing in the solution or in the dispersion ( 21 . 22 ) contained ingredients ( 23 . 24 wherein the means for at least partially vaporizing the liquid medium is adapted to provide sufficient energy to evaporate the components contained in the solution or in the dispersion, and 8th ) for removing the hardened components ( 23 . 24 ) from the surface ( 31 ). Plant according to claim 13, characterized in that the means ( 61 . 62 ) for applying the solution or the dispersion to the surface ( 13 ) comprise a plurality of nozzles for producing very fine droplets, preferably of predetermined size. Plant according to claim 13, characterized in that the means ( 61 . 62 ) for applying the solution or the dispersion to the surface ( 13 ) comprise a screen printing device, in particular a rotary screen printing device. Toner powder with toner particles, available after a method according to a of claims 1 until 12.