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
  • G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/0821—Developers with toner particles characterised by physical parameters
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/087—Binders for toner particles
  • G03G9/08742—Binders for toner particles comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • G03G9/08755—Polyesters
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/09—Colouring agents for toner particles
  • G03G9/0902—Inorganic compounds
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/09—Colouring agents for toner particles
  • G03G9/0902—Inorganic compounds
  • G03G9/0904—Carbon black
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/097—Plasticisers; Charge controlling agents
  • G03G9/09708—Inorganic compounds
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/097—Plasticisers; Charge controlling agents
  • G03G9/09708—Inorganic compounds
  • G03G9/09725—Silicon-oxides; Silicates

Definitions

• the present invention relates to toner compositions for electrophotography, especially the compositions of black toner, which improved Enable toner transfer from a transfer element to a substrate.
• a dry, electrographic image such as becomes an electrophotographic image usually created by first creating an electrostatic latent image on a primary imaging element is created.
• This picture can e.g. generated by it be that first a photoconductor that is in a primary, imaging Element is arranged, is charged and then selected parts of this element using optical exposure or using an electronic exposure means, e.g. a laser scanner or an LED array is discharged.
• the resulting Electrostatic latent image on the photoconductor is developed by placing it close a suitable developer, the marking or toner particles includes that are applied to the latent image to make it a visible image convert.
• the resulting visible image is then based on a variety of Techniques, e.g.
• Color images are usually created by first creating electrostatic, latent images are generated according to the primary color separations of the image. For example to produce a four-color image, color separations in cyan, magenta, yellow and black created, preferably on separate sections of the primary imaging Elements. A single section can be used for all color separations; in this In this case, it is advisable to add each part color image individually after development Transfer substrate. It is possible, but less recommendable, all pictures sequentially at the same location on the primary imaging element then develop the entire image in one step towards the substrate transfer. The individual visible partial color images must be registered on the Substrate to be transferred.
• the intermediate transfer element can either be a drum or a web comprise, and is preferably a conventional resilient member.
• the developer includes marker or toner particles, and preferably the further magnetic carrier particles in a so-called two-component developer substance, usually in connection with the known magnetic brush is used.
• the developer substance may comprise a third component which consists of particulate additional material, the size of which is in the submicron range lies, e.g. Silicon compounds, strontium titanate, barium titanate, titanium dioxide, several Polymer particles. These additives are commonly used to increase the flow rate control, improve the transfer and the charge-mass ratio of the toner too Taxes.
• the developer substance can also be other substances, e.g. Charging agents included.
• the toner charge-mass ratio In electrophotographic development, it is important that the toner be electrical is insulating. If this is not the case, the absolute value of the charge-mass ratio can be the toner, hereinafter referred to as the "toner charge-mass ratio", become so low that the mechanical movement at the developer station reduces the toner caused to separate from the developer as a cloud of dust, its deposition on the primary imaging element to an unacceptable background in the finished print leads.
• the airborne toner may also build up other surfaces, such as that of the loading device, and thus a Cause contamination that adversely affects the operations of the device affects, and productivity loss and possibly a costly Repair of the device leads.
• the electrostatic transfer field to transfer the toner image to either Intermediate transfer element or the printing substrate can be made in several known ways done, mostly by using a pretensioned roller or a corona charger.
• a resilient intermediate transfer element can be one under Include pre-tensioned roller.
• the toner To prevent the toner from discharging, the toner must be electrically insulating, and there must be no electrically conductive components on the surface of the toner particles are where they are electrically during the transfer process with a second conductive material, e.g. Paper, textile materials, metals etc., could come into contact. If this happens, the charge can be affected by an electric field from a conductive component on the toner surface onto the second conductive material pass, whereby the toner has the same potential as the second material, e.g. the Paper substrate reached. Under normal relative humidity conditions Paper is relatively good electrical conductor. Toner would get on the paper and ultimately reach the tension of the paper. In this circumstance, the toner becomes more of that Transfer element as attracted to the substrate, which is the toner transfer prevented. The toner could also be in the developer station by touching Carrier or other toner particles or metallic components of the station charge to lose.
• a second conductive material e.g. Paper, textile materials, metals etc.
• the polymeric binder that the toner comprises is insulating electrically conductive agents, e.g. electrically conductive pigments such as carbon are often used in the Toner particles inserted. Carbon is a preferred pigment for black toner, because it is inexpensive and does not fade; however, it is also electrically conductive.
• This Conductivity of carbon is usually not a problem when in one has dispersed molten polymer binder to form a solid block of To form pigment binder from which by grinding and classifying toner particles be generated.
• grinding and classification techniques are disadvantageous for the production of toner particles of uniform size distribution and small diameter, e.g. an average diameter smaller than 8 ⁇ m, which can be determined using devices such as e.g.
• LC colloidally stabilized limited coalescence
• Suspension processes useful which dissolve either the polymer-containing Toner binder ("polymer suspension”) or the monomers that combine to form the polymeric binders (“suspension polymerization") in an organic solvent form, bring with it and dispersing reasonable additional Toner components such as the pigment particles in the solution.
• Colloidally stabilized Suspension processes that are useful in the practice of the invention e.g. in US 4,833,060, US 4,835,084 and US 4,965,131 and US 5,133,922 to which all reference is made here.
• colloidal stabilized suspension processes which are in a mixture of water and a hydrophobic organic phase can prevent fine hydrophobic Particles, e.g. Silicon compounds, titanium compounds, various grids, etc., the Formation and segregation of macroscopic hydrophilic and hydrophobic phases.
• the particles that limit coalescence can be processed by processes such as Dissolve in concentrated alkalis / alkalis etc. to be removed.
• Toner created by dispersion of pigments and hydrophobic solutions of polymers and monomers generated in water are referred to as LC toners. While on this Articulated LC toners that are usually easily rechargeable are black LC toners that are considered LC toners with carbon defined as pigment are not well chargeable.
• Black LC toner in particular, tend to have an undesirably low charge-to-mass ratio to have. Therefore, the force exerted on the toner can cause it to detach itself from the Push the transfer element away, too small to the forces that the toner on the Keep element to overcome.
• the transmission with increasing transmission voltage up to reaching the Breakdown voltage would improve transmission at low voltages surprisingly enough, an undesirably low maximum reach before it decreases with increasing transmission voltage.
• compositions for toners in particular Compositions of black toner that have high transfer efficiency have, in particular from the intermediate transfer element of an electrophotographic Apparatus on a paper substrate. This need is met by the toner composition according to the invention and the inventive method met.
• the present invention relates to a composition for black toner which dried colored LC toner particles with a thermoplastic polymer and Includes carbon pigment, whose BET value is up to about 140, as well particulate additional material, the size of which is in the submicron range and which is arranged on the surface of the colored LC toner particles.
• a process according to the invention for producing a Composition for black toner the following steps: Make the colored one LC toner particles with a thermoplastic polymer and a carbon pigment with a BET value of up to about 140, drying the colored LC toner particles and mixing the dried colored LC toner particles with particulate additional material, the size of which is in the submicron range.
• a high transmission efficiency, especially of an intermediate transfer element electrophotographic apparatus on a substrate made of paper, is based on achieved compositions of black toner according to the invention, the dried dyed LC toner particles that contain a thermoplastic polymer and carbon a BET value of up to about 140, preferably up to 90, in particular preferably comprise up to 50.
• the composition also includes particulate additional material, the size of which is in the submicron range and which is arranged on the surface of the dried, colored LC toner particles.
• Hydrophilic carbon particles which can be found in the LC toner pigment also flocculate on the organic water-like Solvent interface to the Gibb free energy of the system minimize.
• carbon is in contrast to the solvent particles that the Limit coalescence, electrically conductive. If the carbon on the The toner particle surface comes into contact with an electrically conductive material Charge exchange likely, especially if in addition to the charge on the An electrostatic field has been applied to the particles, which the toner particles onto the Guide element to push.
• This problem is in US 5,118,588 and US 5,262,269 both propose the use of a surface modifier, to cause internal dispersion of the pigment within the toner particle.
• Cabot's 300 carbon shelf with a BET of 80 is the Pigment carbon used in these patents referred to in this document is taken.
• the amount of free energy reduction that occurs in the flocculation of the Carbon particles formed depends on the surface of the particles concerned. Accordingly, the measured BET value of the added carbon is that thereof Surface conforms, an important parameter. The lower the BET value of the Carbon particles is, the less likely it is that they are attached to the organic water Interface will flocculate and the more likely it is that they will will be surrounded by an electrically insulating polymer layer which is undesirable electrical discharge of the toner particles due to contact with an electrical prevents conductive material.
• the LC toner particles have an average diameter of less than 8 microns, preferably of about 3 ⁇ m to about 7 ⁇ m, and preferably comprise about 1% by weight about 20% by weight, more preferably about 3% by weight to about 10% by weight, and more preferably about 5% to about 8% by weight of the carbon pigment.
• the thermoplastic polymer that contains the pigmented particles is selected from a group of polyolefins, styrene resins, acrylic resins, polyesters, Polyurethanes, polyamides, polycarbonates and mixtures of these are selected. Of the polyesters are preferred.
• the toner composition of the present invention also preferably comprises approximately 0.1 weight% to about 10 weight%, more preferably about 0.5 weight% to about 5% by weight, and particularly preferably about 1% by weight to about 2.5% by weight of the particulate additive material on the surface of the LC toner particles.
• the particulate additive has an average diameter of preferably about 10 nm to about 0.3 ⁇ m, more preferably about 20 nm to about 100 nm.
• Suitable particulate additives include Silicon compounds, titanium compounds, barium titanate, strontium titanate, colloidal Polymer lattice, and mixtures of these. Of these, silicon is preferred.
• the electrostatic field associated with the transmission can be generated from a variety of known means.
• the preferred means is to bring the printing sheet into contact with a semiconductor roller.
• the specific resistance of the roller is usually between 10 7 and 10 12 ⁇ • cm, preferably between 10 8 and 10 10 ⁇ • cm.
• This roller usually comprises an elastomeric element, such as polyurethane on a guide body, such as aluminum.
• a roller with an elastomer layer with a low specific resistance can also be used.
• the resistivity is between 10 5 and 10 7 ⁇ • cm and the voltage applied to the lead body is accordingly lower, usually between 500 and 1,000 volts.
• the charge can be transferred directly to the back of the printing material using a suitable device, for example a corona charger.
• the electrostatic latent image is based on a number of electrographic Techniques can be generated, the image is preferably generated electrophotographically, using a primary imaging element with a photoconductor.
• the photoconductor is first made using a suitable known charging device, e.g. one Corona charger or a roller loading device to the desired voltage, and the electrostatic latent image is formed by parts of the charged photoconductor be exposed.
• the exposure can be done using either optical or electronic means, e.g. a laser scanner or an LED arrangement.
• the electrostatic latent image is made visible by the electrostatic latent Image in the vicinity of a developer material with black toner particles according to the invention brought.
• the developer substance can be a one-component insulating developer substance or, preferably, a two-component developer substance, the toner particles and has magnetic carrier particles, preferably ferrite carrier particles.
• appropriate Means for applying toner to the electrostatic latent image can be used is preferably a magnetic developer brush, more preferably one Developer brush for small particles (SPD).
• the developed image which is produced using a black toner according to the invention can be directly onto the substrate or from the primary imaging element preferably on an intermediate transfer element, preferably a compliant one Intermediate transfer element, by using a suitable electrostatic field be transmitted.
• the electrostatic field is determined by a suitable voltage of appropriate height generated, so that it is large enough to attract the field, that pulls the toner onto the substrate.
• the Stress on the intermediate transfer element can be reduced, or preferably the conductive layer of the intermediate transfer element is grounded and a suitable voltage, using known means, e.g. a pretensioned roller or plate, one Corona charger, etc., are applied to the substrate.
• the toner particles are prepared by using a Kao C polymer, a polyester binder available from Kao Corporation is dissolved in ethyl acetate and the resulting solution is commercially available available carbon particles with different BET numbers are added, the Values are given by the manufacturers of the particles.
• the organic phase then mixed with the aqueous phase, the pH 4 buffer with Nalco® 1060, poly (adipic acid-co-methylaminethanol) and has solvents from silicon compounds, as in the US 4,833,060.
• the mixture is made using a Polytron clipper Brinkman subjected to a very high shear and then another Sheared with a microfluidic agent.
• the solvent is from the Particles separated, which have formed by in overnight at room temperature stirred in an open container.
• the particles are covered with a Potassium hydroxide solution and then washed with water to remove the dispersant Remove silicon compounds, and then dried.
• the dried toner particles become dry with R972 silicon compounds available from DeGussa mixed, the amount of silicon compounds added covering approx. 1.5% by weight for a toner particle with a diameter of 6 ⁇ m. On in this way the surface concentration of the silicon is kept approximately constant.
• the developer is then prepared by placing the toner on a ferrite carrier is mixed to a developer with a 6% by weight toner concentration produce.
• Images are created by using a commercially available organic, photoconductive primary imaging element is charged and then using a transparent Step filter is optically exposed.
• the electrostatic latent image generated in the process becomes then developed by using the developer substance contained in an SPD developer station is brought close to the photoconductor.
• the developed image is transmitted by voltage is applied to the guide body of a resilient intermediate transfer element.
• the transfer of the image from the intermediate element to a paper substrate, which is attached to a grounded metal plate is done by applying an appropriate voltage is applied to the guide body of the flexible intermediate transfer element to the Press the toner image onto the paper substrate.
• Measurements regarding the transfer efficiency from the intermediate transfer element to the paper substrate are carried out with the aid of a transmission densitometer. After the density of the paper not covered with toner is set to zero, the density of the image on the paper substrate is determined. Toner residues which have not been transferred are removed from the intermediate transfer element by means of a transparent adhesive tape and their transmission density is measured by the transparent adhesive tape after the density of the tape has been set to zero. The toner transfer efficiency from the intermediate transfer member to the paper substrate, averaged over initial densities between 0.1 and 1.0 on the primary imaging member, is determined as a function of the transfer voltage.
• Example 1 which contains Regal 330 carbon (BET 89) and 1.94% by weight of surface silicon compounds has a particle diameter of only 4.8 ⁇ m, which could be expected to inhibit transmission could. With a voltage of 1000 volts, on the other hand, it becomes quite a good one 69% paper transfer efficiency achieved.
• the toner used in Example 2 containing Black Pearls 6100 carbon (BET 88) and 1.17% by weight surface silicon compounds has one Particle diameter of 6.2 ⁇ m, slightly larger than that in Example 1. At a tension 1500 volts, a high transfer efficiency on paper of 85% is achieved.
• Example 3 which contains Mogul L-carbon (BET 138) and 1.54% by weight of surface silicon compounds has a particle diameter of 5.4 ⁇ m. At a voltage of 1000 volts, the transmission efficiency is quite good achieved on paper of 75%.
• the toner used in Comparative Example 4 containing Monarch 1000 carbon (BET 343) and 1.54% by weight surface silicon compounds has one Particle diameter of only 5.4 ⁇ m.
• the BET value for Monarch 1000 is outside of BET value according to the invention and at a voltage of 1000 volts becomes a low one Paper transfer efficiency of 50% achieved.
• the toner used in Comparative Example 5 containing Raven 5750 carbon (BET 575) and 1.54% by weight of surface silicon compounds has one Particle diameter of 5.4 ⁇ m.
• the BET value for Raven 5750 is far outside of BET value according to the invention and at a voltage of 1000 volts is only one very low transfer efficiency on paper of 29% achieved.
• Example 6 which contains Sterling R-carbon (BET 25) and 1.06% by weight of surface silicon compounds has a particle diameter of 6.5 ⁇ m. At a voltage of 1500 volts, a high transmission efficiency is shown Paper reached 89%.
• Example 7 The toner used in Example 7 containing Black Pearls 280 carbon (BET 42) and 2.30% by weight of surface silicon compounds has a very small one Particle diameter of only 4.4 ⁇ m. Nevertheless, this toner shows at a voltage of 1500 volts a very high transfer efficiency on paper of 89%.

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

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• 2001
  • 2001-01-30 EP EP01101677A patent/EP1130479A3/fr not_active Withdrawn
  • 2001-02-02 JP JP2001027337A patent/JP2001249499A/ja active Pending
  • 2001-07-12 US US09/904,417 patent/US20010055722A1/en not_active Abandoned

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