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
  • G03G9/09—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
  • G03G9/0926—Colouring agents for toner particles characterised by physical or chemical properties

Definitions

• the present application relates to an electrophotographic Dry toner for laser printing. It also relates to a procedure for Production of images by electrophotography Using the dry toner.
• Dry toners for developing electrostatic charge images are known and have been described in many cases (for example by H.-T. Macholtin in "Organic Pigments for Photocopiers and Laser Printers” in Chemistry in Our Time , 24 [1990] 176-181
• They generally comprise binders, pigments, charge directors, and possibly also charge adjuvants, which cause the toner to charge positively or negatively and to adhere to the carrier particles, which are much larger than the toner particles
• the diameter of the carrier particles is 50 to 100 ⁇ m.
• the grain size of the toner particles is generally in the range of 2 to 15 ⁇ m, the mean grain size is approximately 5 to 10 ⁇ m.
• the carrier often consists of iron oxide / magnetite or surface-oxidized iron powder , but can also be made of sodium chloride, sodium nitrate, aluminum nitrate, ammonium chloride, polymethyl methacrylate: silicon dioxide, glass, steel or nickel.
• the type of carrier depends, among other things, on the polarity of the toner. With a positively chargeable toner, the carrier must assume negative polarity so that the toner adheres to the carrier.
• the weight ratio of toner to carrier is generally 1:10 to 1: 200. When mixed with the carrier, the toner particles are charged trioelectrically.
• the carrier is only a tool with which the toner is transferred in the photocopier or laser printer.
• the core element in laser printers as well as photocopiers is the so-called Photoconductor.
• This is generally a roller or drum made from one electrically conductive material on which there is a thin photoconductive Layer.
• the photoconductor becomes electrostatic in the dark charged and then exposed imagewise. Serves as the light source An electronically modulated laser beam.
• the electrical Charge only flows from the surface of the in the exposed areas Photoconductor, creating a latent electrostatic charge image arises. This is then charged with appropriately charged toner particles made visible.
• Laser printers generally work in reverse.
• the photoconductor and toner particles are then charged in the same direction (In contrast, photoconductors and toner particles are common in photocopiers charged electrostatically opposite).
• Targeted Voltage causes the toner particles to be affected by the action of the Skipping laser beam discharged areas of the photoconductor. there the toner particles detach from the carrier particles. The carrier itself stays on the magnetic roller.
• the toner is then by applying a counter voltage from the photoconductor to the paper or another receiving material (for example a plastic film) transfer.
• the toner image is fixed by fusing with itself and with the receiving material.
• color copiers or color laser printers multicolored copies or prints can now also be produced, some of which are of such high quality that they differ from the templates can hardly be distinguished. In this way you can also largely counterfeit-proof templates (banknotes, colored designs Reproduce documents of all kinds and accordingly also forge them.
• Pigments with such a changing color come for example for newer banknotes from the U.S. Federal Reserve. This Banknotes are rotogravured using pasty, solvent-based printing inks. A design change is always with a lot of time and money involved. For short runs this technique is therefore unsuitable.
• the angle-dependent one contains platelet-shaped pigments and can easily be found in laser printers can be used.
• the present invention accordingly relates to an electrophotographic Dry toner for laser printing that is at least one contains angle-dependent platelet-shaped gloss pigment.
• the angle-dependent platelet-shaped gloss pigment is a pearlescent pigment.
• the proportion of angle-dependent pigment depends on the requirements selected. It is expediently 10 to 99% by weight, preferably 20 up to 95% by weight, based on the total weight of the toner. On in any case, the proportion of angle-dependent pigments may only be so high be that the toner image can still be fixed securely. The proportion depends thus also on the type and amount of the binder and the other toner components from.
• the angle-dependent pigments can be the only color pigments in an otherwise colorless toner.
• the toner preferably contains however, besides the angle-dependent gloss pigments, there are others Pigments without interference. Black pigments (in particular Carbon black pigments) or colored pigments. These others Pigments provide a - preferably black or dark - background for the viewing angle-dependent gloss effect. Through the combination of color pigments without interference effect with angle-dependent gloss pigments particularly appealing color effects can be achieved.
• the toner according to the invention can be produced, for example, by a known, especially black, toner with a corresponding Amount of pearlescent pigments depending on the viewing angle is mixed. Such toners are commercially available, for example for use in office laser printers.
• Angle-dependent gloss and pearlescent pigments and processes for their preparation are known and are described, for example, in DE-A 196 18 568 and 198 17 286, EP-A 0 753 545, 0 768 343, 0 823 928, 0 892 832 and 0 940 451 as well as WO 96/34917 and 97/39066.
• They generally consist of platelet-shaped substrates that are coated with several very thin layers.
• the substrate can be transparent, semi-transparent or opaque.
• the thickness of the platelet-shaped substrates is generally 10 to 1,000 nm, preferably 40 to 500 nm. In contrast, the length and width of the substrates are significantly larger. It is generally 2 to 200 ⁇ m, preferably 5 to 50 ⁇ m.
• the layers applied to the substrate are inherently homogeneous and moreover have a very uniform thickness, which is preferably about 2 to 800 nm, particularly preferably about 5 to 600 nm. Their thickness is also determined by the refractive index of the layer material. It is particularly favorable if layers with a high refractive index and those with a lower refractive index follow one another. The difference in the refractive indices is then generally at least 0.1, preferably at least 0.2.
• the layers with a high refractive index preferably consist of a metal or metal oxide, such as nickel, aluminum, TiO 2 , ZrO 2 , Fe 2 O 3 , Fe 3 O 4 , Cr 2 O 3 and / or ZnO.
• the layers with a lower refractive index preferably consist of Al 2 O 3 and / or SiO 2 / MgF.
• the thickness of the layers made of the metal oxide with a high refractive index is generally 10 to 300 nm, preferably 20 to 200 nm, the thickness of the metal layers is about 5 to 35 nm.
• the thickness of the layers consisting of the metal oxide with a lower refractive index is generally 2 to 800 nm, preferably 200 to 600 nm. A pronounced color flop is then observed.
• a platelet-shaped substrate which is surrounded by a first layer of a metal oxide with a high refractive index or of a metal, a second layer of a metal oxide with a low refractive index and a third layer of a metal oxide or of a metal, the Difference in the refractive indices of the layers mentioned is at least 0.1.
• the pearlescent effect occurs when the substrate is made up of multiple layers a material with high refractive index and the thickness of each Layers is smaller than the wavelength of the incident light.
• the 115 nm thick layer of titanium dioxide with a refractive index of 1.94 an optical thickness of 115 nm.194 223 nm.
• Light with a wavelength of 2 x 223 nm 446 nm, i.e. blue light, is weakened in the reflection so that it appears yellow.
• layer thicknesses can also be a special one strong variation in color depending on the viewing angle be achieved, i.e. a strong color flop is formed.
• the coating can optionally be the same or a similar material as the polymeric binder in Toner. This allows a particularly good mixing of all Toner components and a good fixation on the image receiving material (usually paper).
• the triboelectric Properties of the angle-dependent gloss pigments with those of the bring conventional toner pigments into line so far let the mixture give a usable dry toner. It is also surprising that the angle-dependent Color flop caused by pigments by adding the conventional toner pigments reduced little or not at all.
• the optimal size of the glossy pigment particles can be determined by simple Easily determine preliminary tests. On the one hand, the particles should not be too small be so that the visual impression does not appear washed out. Very small platelet-shaped particles are no longer essentially parallel to the Surface of the substrate, but in more or less random resulting angles. This leads to a higher proportion of stray light. On the other hand, the platelet-shaped particles must not be too large be otherwise miscibility with the other toner pigments may be affected.
• the toner according to the invention also contains binders and Charge control substances, optionally also charge auxiliaries.
• suitable Charge control agents as well as binders with a suitable glass transition temperature are known to the person skilled in the art.
• preferred Binders are styrene / alkyl (meth) acrylate copolymers, polyester and Epoxy resins.
• the proportion of the binders is generally 1 to 80% by weight, preferably 2 to 50% by weight, particularly preferably 3 to 30% by weight, in each case based on the total weight of the toner according to the invention.
• the dry toner according to the invention is used in particular in Security and security printing, for example in the production of Checks or bills of exchange, certificates or other counterfeit-proof Paper documents.
• the color change effect has not yet been reproduced.
• the with the invention Prints made from toners are therefore immediately original recognizable.
• the present invention thus also relates to a method for Production of images by electrophotographic means, thereby is characterized in that the dry toner according to the invention is used.
• images means images of all kinds, including text and graphics.
• a mixture was made from 45 g angle dependent Pearlescent pigment (turquoise / purple color effect) and 5 g of a conventional one Toners (®Ultra Magnefine dry toner from Panasonic). The mixture was then made using an office laser printer (Brother HL-8-e) on standard copy paper printed. There were no problems with printing or Interference on. The printed image showed a pronounced turquoise / purple color flop against a black background.

Landscapes

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=7685538

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (22)

Citations (4)

Family Cites Families (1)

• 2001
  • 2001-05-18 DE DE10124657A patent/DE10124657A1/de not_active Withdrawn
• 2002
  • 2002-04-19 EP EP02008788A patent/EP1258782A1/de not_active Withdrawn
  • 2002-05-20 US US10/147,922 patent/US20020192585A1/en not_active Abandoned
  • 2002-05-20 JP JP2002144968A patent/JP2002351144A/ja active Pending

Patent Citations (4)

Also Published As

Similar Documents

Legal Events