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
  • G03G9/12—Developers with toner particles in liquid developer mixtures
  • G03G9/125—Developers with toner particles in liquid developer mixtures characterised by the liquid
• • 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
  • G03G9/12—Developers with toner particles in liquid developer mixtures
  • G03G9/13—Developers with toner particles in liquid developer mixtures characterised by polymer components
  • G03G9/131—Developers with toner particles in liquid developer mixtures characterised by polymer components obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/16—Developers not provided for in groups G03G9/06 - G03G9/135, e.g. solutions, aerosols
  • G03G9/18—Differentially wetting liquid developers

Definitions

• a potential image carrier e.g. a photoconductor to generate potential images (charge images) depending on the image, to color them in a developer station (inking station) and to print the image thus developed onto the recording medium.
• Either dry toner or liquid developer can be used to develop the potential images.
• a method for electrophoretic liquid development (electrographic development) in digital printing systems is known, for example, from EP 0 756 213 Bl or EP 0 727 720 Bl.
• the process described there is also known under the name HVT (High Viscosity Technology).
• a carrier liquid containing silicone oil with color particles (toner particles) dispersed therein is used as the developer liquid.
• the color particles typically have a particle size of less than 1 micron. Further details can be found in EP 0 756 213 B1 or EP 0 727 720 B1, which form part of the disclosure of the present application.
• Dry toner printing Thick layers of toner are used here, therefore high fixing energy is required with heavy paper use during heat or heat / pressure fixing; the abrasion of fixed dry toner layers in the printer and in post-processing is often problematic.
• Liquid toner based on volatile carrier liquids The carrier liquid has an odor and is flammable, residues of carrier liquid remain on the recording medium, the evaporation time is in the range of several seconds or minutes, there is a tendency to smear.
• Liquid toner, water based There is a risk of discharge of an electrostatic charge in contact with the conductive liquid (US 5943535), evaporation of the residual water on the recording medium is not possible in very short times at not too high temperatures, the optimization with regard to complete transmission is problematic. 4.) Liquid toner silicone oil based: Fixing on non-porous or non-silicone oil absorbing substrates is problematic. 5.) Conventional printing process: No variable printing form is possible, the edition 1 or low edition height is uneconomical.
• the problem to be solved by the invention consists in specifying a method with which a fast-drying, highly abrasion-resistant printing of variable data or of small and medium-volume editions is possible on the basis of a potential image. This problem is solved according to the features of claim 1.
• the invention solves the specified technical problem by using liquid UV-curable colorants which form a very thin dye film and which operate in principle according to electrophoretic processes, with charged dye particles being deposited imagewise in a photopolymerizable liquid by the action of an electrostatic potential image and the dye image is cured on the recording medium with a residual portion of the UV-curable liquid by UV radiation.
• the photopolymerizable liquid is called the carrier liquid.
• a high - resistance photopolymerizable carrier liquid for example acrylic ester
• colored pigments, coated colored pigments or toner particles with colored pigments or. Dyes are suspended (hereinafter referred to as solid particles).
• other substances can be added to the photopolymerizable liquid, such as charge control agents which charge the suspended particles in a targeted manner, initiators which accelerate the photopolymerization of the carrier liquid and agents which influence the surface tension and which control viscosity.
• a high solids content of over 10% is preferably used.
• the composition of the carrier liquid and the solid particles suspended therein is adjusted in such a way that the solid particles in the carrier liquid become charged with a preferred polarity.
• the carrier liquid is called FPFE (photopolymerizable liquid developer) in the following.
• FPFE photopolymerizable liquid developer
• an inking station developer station
• the FPFE is prepared in such a way that a constant amount of carrier liquid is available on an applicator roller per time and per area.
• the FPFE is conveyed into the area of effect of a potential pattern on the potential image carrier, for example a photoconductor.
• the potential pattern was previously generated on the potential image carrier by suitable means; eg by a common electrophotographic process.
• a bias voltage can be applied to the applicator roller in such a way that there is a potential contrast between the image points of the potential pattern on the potential image carrier and the bias voltage.
• the bias voltage can contain both DC and AC components.
• a uniform FPFE film can be located in a contact zone between the applicator roller and the potential image carrier.
• the solid particles are deposited on the potential image carrier in accordance with their preferred charge.
• the solid particles forming the image to be printed are located in the area of the image areas to be colored in the immediate vicinity of the surface of the potential image carrier. In the areas that are not to be colored, the solid particles are located at a greater distance from the potential image carrier surface, preferably in the vicinity of the surface of the applicator roller.
• the liquid layer adhering to the potential image carrier thus consists of a thin transparent photopolymerizable layer containing an image made of solid particles.
• the liquid layer which contains the color image consisting of solid particles is referred to below as the image film.
• the color image can preferably be transferred from the potential image carrier to a recording medium (printing material) with the support of an electrical field.
• the image film is again separated in the same way as described above for the separation process at the end of the development process. This means that the solid particles are completely or almost completely and the transparent photopolymerizable layer is only partially (approx. 50%) transferred to the recording medium.
• the same electrostatically assisted method can be used here as has been described above for the transfer from the potential image carrier to a recording medium.
• the liquid content in the image film can be reduced, for example, on the potential image carrier, on an intermediate image carrier or on the recording medium.
• This can be done, for example, by a take-off roller, which is brought into direct contact with the image film, whereby an electrical auxiliary field can be created in such a way that the solid particles with the correct preferred charge move away from the take-up roller and any incorrectly charged solid particles that are present move to the take-up roller become.
• a liquid film can result on the take-off roller has approximately 50% of the liquid film thickness of the image film before contact with the take-off roller and predominantly contains only a few incorrectly charged solid particles. This frees part of the carrier liquid from the image film on the one hand, and on the other hand from any incorrectly charged solid particles which would otherwise lead to background impairments on the image-free surfaces on the recording medium.
• the different color image separations can be generated one after the other on the potential image carrier and successively transferred either to an intermediate image carrier or to the recording medium.
• the color image extracts can also be collected directly on the potential image carrier and then transferred together to the record carrier, or they can be transferred individually from the potential image carrier to the intermediate carrier and collected there and then transferred to the record carrier.
• the printed image is fixed on the recording medium by irradiation with UV light.
• the solid particles are embedded in a solid polymer matrix on the one hand, and on the other hand, the carrier liquid firmly bonds to the recording medium.
• the carrier liquid in the non-image areas is solidified into a thin transparent film.
• the transparent photopolymerizable liquid can penetrate into the recording media. With UV radiation, it is then solidified in the recording medium.
• the coordination of chemical processes, spectral distribution and power density of the irradiation must be observed:
• the process of UV curing can be optimized by the correct spectral distribution and the correct power density of the radiation.
• a radiation source can be used, which is a combination of ultraviolet light (wavelength: 200 to 400 nm, abbreviation: UV), visible light (wavelength: 400 to 700 nm, abbreviation: VIS) and infrared heat radiation (wavelength: 700 nm to 10 ⁇ m, abbreviation: IR).
• UV ultraviolet light
• VIS visible light
• IR infrared heat radiation
• the relative proportion of these spectral ranges is selected so that the IR / VIS components are used for the activation of the bonds required for photopolymerization (heating) and the UV component is used to harden the photopolymerizable carrier liquid to adapt to the chemical composition of the photopolymerizable carrier liquid becomes.
• Both the relative proportions of the spectral ranges and the absolute power density of the radiation must be adapted to the chemical properties of the substances involved, to the thickness of the layer to be polymerized and to the process speed of the printing and fixing process.
• the fixing quality, the gloss and the abrasion resistance of the printed image can be adapted in accordance with the desired properties of the printed image and the load on the printed image to be expected in a certain post-processing line.
• the UV-A radiation (wavelength: 320 to 400 nm) has a greater penetration depth and has a stronger volume effect, ie a polymerization of the entire layer volume.
• the UV-B radiation (wavelength: 280 to 320 nm) causes a stronger hardening of the material on the surface than inside the recording medium.
• the UV-C radiation (wavelength: 200 to 280 nm) is used for surface hardening.
• protective gas e.g. nitrogen
• Corona radiation before and / or during UV curing leads to reduced surface polymerization of the recording medium, which e.g. can be used to avoid excessive brittleness of the surface and better elasticity in post-processing.
• a good flow of the image film and a good connection with the surface of the recording medium can be achieved with a high surface gloss. This may be necessary in particular in the case of non-porous recording media such as smooth polymer films or metal films. If a hard surface is required, UV-C radiation can be used to fix the surface.
• a printed color separation can be fixed immediately, ie before the next color separation is transferred to the recording medium, as required.
• the overall image which consists of several color separations, can also be fixed in a closed manner. It is also possible to produce individual color separations with special gloss or abrasion properties by subjecting these color separations to a separate fixing treatment and / or a specific corona pretreatment.
• UV pre-fixing of reduced power density with subsequent roller embossing with a certain surface roughness and final fixing to achieve sufficient strength and hardness are possible.
• UV radiation can also be used to increase the viscosity of the image film in any stages of the printing process when using reduced radiation power.
• an intermediate image carrier with low surface energy e.g Teflon
• Record carriers e.g. thick cardboard, wood or the like
• Such a process can be optimized by using a corona pretreatment in combination with UV-A curing, which creates a volume-related image film with a sticky surface, which leads to a closed transfer of the image film with adhesive effect on the recording medium.
• FIG. 1 shows a basic illustration of a printing or copying device with which the method can be carried out
• Fig. 2 shows the fixation in principle.
• FIG. 1 shows a basic illustration of an electrographic printing device.
• a potential image carrier 101 e.g. a photoconductor drum exposed to an erase exposure 102.
• the potential image carrier is then charged in the station 103.
• Potential images of images to be printed are generated on the potential image carrier 101 by imagewise exposure in the station 104.
• These potential images are developed in a developer station 200 by a liquid developer with the properties mentioned above.
• liquid developer is taken from a developer supply 203 and fed to an applicator roller 201 via an application roller 202.
• the applicator roller 201 conveys the liquid developer to the potential image carrier 101.
• the applicator roller 201 is then cleaned in the cleaning station 204.
• carrier liquid with solid particles is transferred to the potential image carrier 101 and is deposited there, in the non-image regions carrier liquid is transferred to the potential image carrier 101.
• a film is thus formed on the potential image carrier 101 which contains carrier liquid with solid particles in the image regions and carrier liquid in the non-image regions.
• the film is transferred to a recording medium 402 in a transfer printing station with an intermediate carrier 301.
• a back pressure roller 401 is also used for this.
• the intermediate carrier 301 can also be cleaned with the aid of an intermediate carrier cleaning 302.
• the record carrier 402 is finally fed to a fixing station 500, in which the fixing takes place according to the method described above. 2 shows the course of the fixation.
• the fixing station 500 has a radiation source 501, which emits the UV radiation 502 described above.
• the radiation 502 is directed onto the recording medium 402 and strikes the film 503 which contains the printed images there.
• the film has the solid particles 504 and the carrier liquid 505.
• the radiation 502 connects the film 503 to the recording medium 402 using the method described above.
• excess carrier liquid on the recording medium 402 or an intermediate medium 301 is to be removed, this can e.g. in the following manner: by means of a pickup roller which is in contact with an intermediate carrier and / or recording medium, by means of a pickup roller • which has a potential such that the charged solid particles are repelled by this pickup roller and only the carrier liquid is split up; the carrier liquid transferred on a non-absorbent pickup roller can e.g. removed by a squeegee;
• the transferred carrier liquid z. B. be removed by a squeeze bar.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Wet Developing In Electrophotography (AREA)
• Liquid Developers In Electrophotography (AREA)
• Color Electrophotography (AREA)
• Fixing For Electrophotography (AREA)
• Electrostatic Charge, Transfer And Separation In Electrography (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34894906

Family Applications (1)

Country Status (8)

Cited By (4)

Families Citing this family (5)

Citations (2)

Family Cites Families (9)

• 2004
  • 2004-03-01 DE DE102004009987A patent/DE102004009987B3/de not_active Expired - Fee Related
• 2005
  • 2005-02-24 WO PCT/EP2005/001964 patent/WO2005083528A1/de not_active Ceased
  • 2005-02-24 JP JP2007501178A patent/JP5156370B2/ja not_active Expired - Fee Related
  • 2005-02-24 CA CA002557041A patent/CA2557041A1/en not_active Abandoned
  • 2005-02-24 US US10/590,161 patent/US7974554B2/en not_active Expired - Fee Related
  • 2005-02-24 CN CNA2005800068111A patent/CN1926475A/zh active Pending
  • 2005-02-24 EP EP05733672A patent/EP1721221A1/de not_active Withdrawn
  • 2005-02-24 AU AU2005217730A patent/AU2005217730B2/en not_active Ceased

Patent Citations (2)

Non-Patent Citations (1)

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