Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-11-23
2004-08-17
Shosho, Callie (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S404000, C524S548000, C524S555000, C524S567000
Reexamination Certificate
active
06777462
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to aqueous ink compositions. More specifically, the present invention is directed to inks particularly suitable for use in ink jet printing processes. One embodiment of the present invention is directed to an ink composition comprising water, a colorant, and sodium tetraphenylboride. Another embodiment of the present invention is directed to a set of inks for printing multicolor images in an ink jet printer, said ink set comprising (1) a first ink having a first color and comprising water, a first colorant, and at least one of (a) a cationic polymer, (b) a cationic surfactant, or (c) an inorganic salt the cation of which has a tetraphenylboride salt that is substantially insoluble in water; and (2) a second ink having a second color different from the first color and comprising water, a second colorant, and sodium tetraphenylboride, wherein intercolor bleed between the first ink and the second ink is reduced when the second ink is printed adjacent to, on top of, or underneath the first ink on a print substrate. In a specific embodiment, the first ink comprises water, an anionic dye, and a polyquaternary amine compound. In another specific embodiment, the first ink comprises water and a colorant comprising an anionic dye complexed with a polyquaternary amine compound. Yet another embodiment of the present invention is directed to a multicolor ink jet printing process which comprises: (1) incorporating into an ink jet printer a first ink having a first color and comprising water, a first colorant, and at least one of (a) a cationic polymer, (b) a cationic surfactant, or (c) an inorganic salt the cation of which has a tetraphenylboride salt that is substantially insoluble in water; (2) incorporating into the ink jet printer a second ink having a second color different from the first color and comprising water, a second colorant, and sodium tetraphenylboride; (3) causing droplets of the first ink to be ejected in an imagewise pattern onto a substrate; and (4) causing droplets of the second ink to be ejected in an imagewise pattern onto the substrate, wherein intercolor bleed between the first ink and the second ink is reduced when the second ink is printed adjacent to, on top of, or underneath the first ink on the substrate.
Ink jet printing systems generally are of two types: continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is emitted in a continuous stream under pressure through at least one orifice or nozzle. The stream is perturbed, causing it to break up into droplets at a fixed distance from the orifice. At the break-up point, the droplets are charged in accordance with digital data signals and passed through an electrostatic field which adjusts the trajectory of each droplet in order to direct it to a gutter for recirculation or a specific location on a recording medium. In drop-on-demand systems, a droplet is expelled from an orifice directly to a position on a recording medium in accordance with digital data signals. A droplet is not formed or expelled unless it is to be placed on the recording medium.
Since drop-on-demand systems require no ink recovery, charging, or deflection, the system is much simpler than the continuous stream type. There are two types of drop-on-demand ink jet systems. One type of drop-on-demand system has as its major components an ink filled channel or passageway having a nozzle on one end and a piezoelectric transducer near the other end to produce pressure pulses. The relatively large size of the transducer prevents close spacing of the nozzles, and physical limitations of the transducer result in low ink drop velocity, Low drop velocity seriously diminishes tolerances for drop velocity variation and directionality, thus impacting the system's ability to produce high quality copies. Drop-on-demand systems which use piezoelectric devices to expel the droplets also suffer the disadvantage of a slow printing speed.
Another type of drop-on-demand system is known as thermal ink jet, or bubble jet, and produces high velocity droplets and allows very close spacing of nozzles. The major components of this type of drop-on-demand system are an ink filled channel having a nozzle on one end and a heat generating resistor near the nozzle. Printing signals representing digital information originate an electric current pulse in a resistive layer within each ink passageway near the orifice or nozzle, causing the ink in the immediate vicinity to evaporate almost instantaneously and create a bubble. The ink at the orifice is forced out as a propelled droplet as the bubble expands. When the hydrodynamic motion of the ink stops, the process is ready to start all over again. With the introduction of a droplet ejection system based upon thermally generated bubbles, commonly referred to as the “bubble jet” system, the drop-on-demand ink jet printers provide simpler, lower cost devices than their continuous stream counterparts, and yet have substantially the same high speed printing capability.
The operating sequence of the bubble jet system begins with a current pulse through the resistive layer in the ink filled channel, the resistive layer being in close proximity to the orifice or nozzle for that channel. Heat is transferred from the resistor to the ink. The ink becomes superheated for above its normal boiling point, and for water based ink, finally reaches the critical temperature for bubble formation or nucleation of around 280° C. Once nucleated, the bubble or water vapor thermally isolates the ink from the heater and no further heat can be applied to the ink. This bubble expands until all the heat stored in the ink in excess of the normal boiling point diffuses away or is used to convert liquid to vapor, which removes heat due to heat of vaporization. The expansion of the bubble forces a droplet of ink out of the nozzle, and once the excess heat is removed, the bubble collapses on the resistor. At this point, the resistor is no longer being heated because the current pulse has passed and, concurrently with the bubble collapse, the droplet is propelled at a high rate of speed in a direction towards a recording medium. The resistive layer encounters a severe cavitational force by the collapse of the bubble, which tends to erode it. Subsequently, the ink channel refills by capillary action. This entire bubble formation and collapse sequence occurs in about 10 microseconds. The channel can be refired after 100 to 500 microseconds minimum dwell time to enable the channel to be refilled and to enable the dynamic refilling factors to become somewhat dampened. Thermal ink jet processes are well known and are described in, for example, U.S. Pat. Nos. 4,601,777, 4,251,824, 4,410,899, 4,412,224, and 4,532,530, the disclosures of each of which are totally incorporated herein by reference.
Acoustic ink jet printing processes are also known. As is known, an acoustic beam exerts a radiation pressure against objects upon which it impinges. Thus, when an acoustic beam impinges on a free surface (i.e., liquid/air interface) of a pool of liquid from beneath, the radiation pressure which it exerts against the surface of the pool may reach a sufficiently high level to release individual droplets of liquid from the pool, despite the restraining force of surface tension. Focusing the beam on or near the surface of the pool intensifies the radiation pressure it exerts for a given amount of input power. These principles have been applied to prior ink jet and acoustic printing proposals. For example, K. A. Krause, “Focusing Ink Jet Head,”
IBM Technical Disclosure Bulletin
, Vol. 16, No. 4 September 1973, pp. 1168-1170, the disclosure of which is totally incorporated herein by reference, describes an ink jet in which an acoustic beam emanating from a concave surface and confined by a conical aperture was used to propel ink droplets out through a small ejection orifice. Acoustic ink printers typically comprise one or more acoustic radiators for illuminating the free surface of a pool of li
Colt Richard L.
Ly Hiep
McGrane Kathleen M.
Smith Thomas W.
Byorick Judith L.
Shosho Callie
Xerox Corporation
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