| Radiofrequency activated inkjet inks and apparatus for inkjet printing -> Monitor Keywords |
|
|
  Radiofrequency activated inkjet inks and apparatus for inkjet printingUSPTO Application #: 20060109327Title: Radiofrequency activated inkjet inks and apparatus for inkjet printing Abstract: This invention relates to fast-drying RF inkjet composition and apparatus for inkjet printing RF inkjet compositions. The compositions and apparatus are useful for inkjet printing onto a variety of media including both porous and non-porous substrates. The RF inkjet composition desirably includes RF susceptors combined with polar carriers which may be activated by RF energy to generate heat within the RF inkjet composition, resulting in enhanced evaporative drying. (end of abstract) Agent: Johnson Polymer, Inc. - Sturtevant, WI, US Inventors: Arthur S. Diamond, Jonathan M. Gorbold, Timothy D. Gorbold, Brian L. Teachout, David E. Brotton, J. David Campbell, Richard W. Chylla, Michael A. Dalton, Jon A. Debling USPTO Applicaton #: 20060109327 - Class: 347102000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20060109327. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention provides radiofrequency (RF) activatable inkjet inks, methods for printing the inks and apparatus for inkjet printing using RF inkjet compositions. BACKGROUND OF THE INVENTION [0002] Most inkjet inks currently available are low viscosity liquids which contain large amounts of water, often 90 weight percent or greater. The use of water as a solvent in these inks is advantageous because it is inexpensive, environmentally friendly and non-toxic. Unfortunately, water also has a relatively high boiling point and a high latent heat of evaporation. For this reason, inkjet inks which contain large amounts of water tend to be slow-drying. Slow-drying inks are disfavored for many printing applications because they lead to slow printing rates. [0003] To speed up the printing rate of water-based inkjet inks, printing equipment may employ external heating devices to speed up the evaporation of water from the inks. Inkjet drying techniques include passing media with wet ink images against or near heated rollers or platens. Another approach to increasing the drying rate of water-based inkjet inks is to generate heat internally within the inks by coupling energy into the water or incorporating radiation susceptors into the ink formulations. The heating of water or susceptors is achieved by exposing the ink to radiation of a suitable frequency, causing heat to be generated within the ink and speeding up the evaporation of water and other volatile solvents. Most of these susceptors are microwave activated inorganic salts and the use of microwaves to heat and dry the water is slow and relatively inefficient. The use of external heating devices entails several complications. For example, contact of heating devices with wet ink image can produce smudging or smearing. Also, application of heat and subsequent drying of media while in contact with rollers can produce undesirable buckling or curvature of the output. This may require additional steps to flatten the media after printing and drying. [0004] Therefore, a need exists for an improved, fast drying inkjet compositions and apparatus for inkjet printing using these compositions. SUMMARY OF THE INVENTION [0005] One aspect of the present invention provides fast-drying RF inkjet compositions. The RF inkjet compositions include at least one RF susceptor, a colorant and at least one polar carrier. It is believed that the RF inkjet composition generates heat when exposed to radiofrequency energies from ionic conduction caused by the movement of dissociated ions. This internally-generated heat enhances evaporation of volatile liquids from the ink compositions and results in shorter drying times. In some instances, the inkjet compositions provided herein, may be dried at a rate fast enough to allow for a printing speed of one page per second, or even faster, without any smearing of the inks. [0006] In one embodiment of the RF inkjet composition, RF energy is used to cause a chemical reaction in the ink during drying. This produces images with improved resistance properties due to crosslinking. However the wet inks retain resolubility during printing as drying and crosslinking occur upon RF activation. Accordingly these inks cause reduced clogging of the inkjet heads. [0007] Another embodiment of the inkjet inks provides RF inkjet compositions wherein chemical reactions are used for binding of inks to media. In one aspect of this invention, media containing reactive groups for reaction with the RF activated inkjet inks are used. Reaction between inks and media occur upon exposure to RF energy. This allows printing on non-porous media such as plastic films or modified paper substrates with improved resistance properties of images produced. [0008] In still another embodiment of the inkjet inks, exposure of the inks to RF energy causes reaction of a polar carrier in the ink with ionomers or other components present in the inks. This produces images with improved resistance properties due to consumption or reduction in the amount of polar carrier. Another advantage of these inks is their reduced sensitivity to RF energy as the heating progresses so that these inks are self limiting and show controlled increase in temperature. [0009] In some embodiments, the RF inkjet compositions are sublimation inks. These inks include RF susceptors and sublimation colorants in inkjet ink. In a preferred variation of this embodiment, the RF susceptor provides a polymeric binder for the sublimation colorants. The binders are used to support the colorants prior to sublimation in a transfer sublimation printing process. In one exemplary embodiment, the RF-activatable binder is an RF-activatable ionomer and the sublimation colorant is a sublimation dye. The sublimation inks may initially be provided in the form of a dispersion that is applied to a transfer substrate. Application of RF energy to the transfer substrate results in sublimation of the sublimation colorants and subsequent deposition of the colorants onto a suitable media to produce an inkjet image. The use of RF-activatable binders provides improved rate of ink transfer to the media. [0010] In another embodiment of the invention, RF-activitable sublimation inks including RF susceptors and sublimation colorants are used for direct printing to a media such as textile or paper. RF activation is used for sublimation of dyes onto the media. This RF activation also results in heating of the media, making the media receptive to dye. The use of RF inkjet compositions results in printing with little or no distortion of the media in comparison with a thermal process that does not use RF activatable inks. [0011] The present invention also provides RF-activatable solid hot melt inkjet inks for printing. These inks allow rapid heating of the hot melt and ejection on to the media used for printing. Examples of RF-activatable hot melts include those based on ionomers such as those from acrylic copolymers with polar carriers such as glycerol. These hot melt inks contain no or reduced amount of solvents. [0012] In addition to inkjet inks, the present invention provides compositions for RF-activatable protective water-borne coatings, such as an overprint varnishes for application over previously applied inkjet images. The protective water-borne coatings contain ionomers and a polar carrier so that the composition can be activated by RF energy. The heating and drying of the protective coating provides a high gloss, protective barrier for the inkjet images. Similarly, the RF-activatable coatings may be applied to media prior to inkjet printing. The media so coated may then be heated using RF energy, such that the rate of drying for an ink subsequently printed onto the media is increased. This aspect allows high gloss printing applications which require coatings of higher thickness. RF-activitable inks and overprint varnishes can dry faster than those by IR or forced drying means. [0013] A second aspect of the invention provides an inkjet printer and a method for impulse or drop on demand inkjet printing using RF energy to superheat a droplet of ink for deposition on a media. Although the RF inkjet compositions described herein are well-suited for use with the printers, other RF inkjet compositions may also be employed. The printers use an RF emitter coupled to a printing nozzle to rapidly heat an RF inkjet composition in the nozzle which generates a pressure pulse. The pressure pulse results in the ejection of an ink drop from the nozzle. The use of RF heating to create a pressure pulse has advantages over piezoelectric and thermal resistive heating-based impulse printing methods because RF heating does not require contact with the ink droplet. Therefore the RF emitter does not require changing upon changing the ink such as an ink of different color. Moreover RF heating provides a more uniform heating of the ink droplets in comparison with thermal resistive heating, resulting in less clogging of the inkjet heads. Examples of RF inkjet composition useful for this purpose include inks containing at least one RF susceptor, a colorant and a polar carrier described above. [0014] A third aspect of the invention provides apparatus for the delivery of RF energy in inkjet printers for the purposes of drying and/or crosslinking RF inkjet inks and coatings. Although the present RF inkjet compositions and coatings are well-suited for use with these apparatus, other RF inkjet compositions and coatings may also be employed. One apparatus in accordance with the present invention provides an inkjet printer for drop on demand and continuous inkjet systems wherein one or more transistor RF modules are used to drive a low-power applicator system for inks. In some embodiments, the applicator system couples RF energy into the ink stream before its contact with the media onto which it is ultimately printed. A part of the volatile components such as water and/or other solvents are removed as a result of RF activation. The resulting inks therefore dry faster, produce less ink bleeding and higher gloss. In one embodiment of this invention the inks dry in less than one second after application on the media. Another aspect of this invention provides an inkjet printer for color printing wherein each colored cartridge is provided with separate RF modules to drive the applicator system for inks. In one embodiment of this invention, the RF module is incorporated into the ink cartridge. In another embodiment of this invention, the RF module is mounted separately on a carriage for the ink cartridge. [0015] Another exemplary apparatus provides an RF module to couple RF energy into an image or a portion of the image immediately after printing on media. This results in volatilization of water and/or other solvents and faster drying of the RF inkjet compositions. In one embodiment of this invention the inks dry in less than one second after application on the media. In one embodiment of this invention, one or more transistor RF modules drive a low-power applicator system to couple the RF energy into the image or a portion of the image immediately after printing. In one aspect of this invention, the applicator is incorporated into the ink cartridge by utilizing the traces on the flexible printed circuit of the cartridge. Another embodiment of this invention mounts the RF applicator on the print carrier separately from the ink cartridge. Two RF applicators are desirable to provide heating of the RF activitable ink when used with multidirectional printing. [0016] Another apparatus provides a RF power source to drive an applicator system incorporated into the roller drive used to move media through a printing zone in an inkjet printer. This apparatus couples RF energy generated in the roller of the roller drive into the image printed on the media. This produces faster drying inks due to application of RF energy shortly after printing of the media and volatilization of water and/or other solvents. In one embodiment of this invention the inks dry in less than one second after application on the media. One example of this invention includes a RF power source mounted inside the roller used for moving media. In another embodiment, the RF power source is mounted separately on the printer chassis. An interdigitated probe (IDP) system utilizing a series of alternating electrodes may be used as the RF emitter to achieve uniform drying of inks using stray field energy. In another embodiment the media passes between two electrodes after printing and drying is achieved in the through field. [0017] Yet another apparatus provided by this invention includes a RF power source which drives an interdigitated radiofrequency applicator system. After printing with the RF inkjet composition, the media is passed over the applicator so as to couple the RF energy with the image present on the media. This causes faster drying of the image. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 shows a block diagram of a suitable heating system that is capable of generating an electromagnetic field for activating the inks of the present invention. [0019] FIG. 2 shows an interdigitated probe system for generating RF energy. [0020] FIG. 3 shows an RF applicator that includes interdigitated probes embedded into the substrate roller of an inkjet printer. Continue reading... Full patent description for Radiofrequency activated inkjet inks and apparatus for inkjet printing Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Radiofrequency activated inkjet inks and apparatus for inkjet printing patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Radiofrequency activated inkjet inks and apparatus for inkjet printing or other areas of interest. ### Previous Patent Application: Printer with a paper treatment system Next Patent Application: Printer with a reel for supplying an endless web of a recording medium Industry Class: Incremental printing of symbolic information ### FreshPatents.com Support Thank you for viewing the Radiofrequency activated inkjet inks and apparatus for inkjet printing patent info. IP-related news and info Results in 4.09346 seconds Other interesting Feshpatents.com categories: Medical: Surgery , Surgery(2) , Surgery(3) , Drug , Drug(2) , Prosthesis , Dentistry |
||
