Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2001-11-15
2003-05-27
Hess, Bruce H. (Department: 1715)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C347S105000, C428S447000
Reexamination Certificate
active
06569511
ABSTRACT:
Copending Application U.S. Ser. No. 10/001,572, filed concurrently herewith, entitled “Photoprotective and Lightfastness-Enhancing Siloxanes,” with the named inventors Thomas W. Smith and Kathleen M. McGrane, the disclosure of which is totally incorporated herein by reference, discloses a compound of one of the formulae
wherein R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
, R
8
, R
9
, and R
10
each, independently of the others, is an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, R
11
and R
12
each, independently of the others, is an alkylene group, an arylene group, an arylalkylene group, or an alkylarylene group, G is a cationic moiety, A is an anionic moiety, n is an integer representing the number of repeat —OSi(R
7
)(R
8
)— monomer units, a is an integer representing the number of repeat —OSi(R
10
)(R
12
-lightfastness moiety)— monomer units, and c is an integer representing the number of repeat —OSi(R
9
)(R
11
-hydrophilic moiety)— monomer units.
Copending Application U.S. Ser. No. 10/001,741, filed concurrently herewith, entitled “Aqueous Inks Containing Lightfastness-Enhancing Siloxanes,” with the named inventors Thomas W. Smith and Kathleen M. McGrane, the disclosure of which is totally incorporated herein by reference, discloses an ink composition which comprises water, a colorant, and a lightfastness agent which is a polysiloxane having thereon a hydrophilic moiety and a lightfastness moiety. Also disclosed are printing processes using the ink.
BACKGROUND OF THE INVENTION
The present invention is directed to recording sheets suitable for receiving images of an aqueous ink. More specifically, the present invention is directed to recording sheets which enhance the lightfastness of images generated thereon. One embodiment of the present invention is directed to a recording sheet which comprises a substrate and an image-receiving coating situated on at least one surface of the substrate, said image-receiving coating being suitable for receiving images of an aqueous ink, said image-receiving coating comprising a lightfastness agent of one of the formulae
wherein R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
, R
8
, R
9
, and R
10
each, independently of the others, is an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, R
11
and R
12
each, independently of the others, is an alkylene group, an arylene group, an arylalkylene group, or an alkylarylene group, G is a cationic moiety, A is an anionic moiety, n is an integer representing the number of repeat —OSi(R
7
)(R
8
)— monomer units, a is an integer representing the number of repeat —OSi(R
10
)(R
12
-lightfastness moiety)— monomer units, and c is an integer representing the number of repeat —OSi(R
9
)(R
11
-hydrophilic moiety)— monomer units.
Compositions for imparting lightfastness to recording substrates containing images are known, including block or graft copolymers of dialkylsiloxanes and polar, hydrophilic monomers capable of interacting with an ink colorant to cause the colorant to become complexed, laked, or mordanted; organopolysiloxane copolymers having functional side groups capable of interacting with an ink colorant to cause the colorant to become complexed, laked, or mordanted; perfluorinated polyalkoxy polymers; perfluoroalkyl surfactants having thereon at least one group capable of interacting with an ink colorant to cause the colorant to become complexed, laked, or mordanted; and the like.
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 far 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. No. 4,601,777, U.S. Pat. No. 4,251,824, U.S. Pat. No. 4,410,899, U.S. Pat. No. 4,412,224, and U.S. Pat. No. 4,532,530, the disclosures of each of which are totally incorporated herein by reference.
Acoustic i
McGrane Kathleen M.
Smith Thomas W.
Byorick Judith L.
Grendzynski Michael E.
Hess Bruce H.
Xerox Corporation
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