Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2001-09-04
2003-11-18
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031490, C106S031510, C106S031580
Reexamination Certificate
active
06648951
ABSTRACT:
FIELD OF THE INVENTION
The present invention is drawn to ink-jet ink compositions that are environmentally friendly, reliable, fast drying, and waterfast for use in ink-jet printers, particularly thermal ink-jet printers used for point-of-sale (POS) applications.
BACKGROUND OF THE INVENTION
Thermal ink-jet printers provide an effective means of propelling ink-jet inks onto various media including paper. These printers accomplish this task by using resistive heater elements for heating the ink to a boil, and propelling the ink through an overlying orifice plate. Such printers are desirable for use for several reasons. For example, thermal ink-jet printers have a relatively fast throughput while being relatively inexpensive to run. Additionally, these printers are relatively easy to use, and the ink is easily replaced. Alternatively, piezo ink-jet printers can similarly be used effectively.
When formulating inks for use with point-of-sale (POS) applications, special challenges exist. Typical point-of-sale machines, including cash registers, credit card receipt printers, printers for checks, etc., print images that are often handled by clerks and customers immediately after printing. For example, after the printing of a receipt, a cash register worker must be able to grasp the receipt and hand it to the customer immediately. To accommodate immediate handling of such print jobs, some of the typical print technologies used for POS applications have included dot matrix impact printing and direct thermal printing. Though these technologies are functional, each has certain limitations. For example, dot matrix printing is often quite noisy, and direct thermal printing can require special paper and lacks permanence upon exposure to water, heat, or light. Additionally, neither technology currently provides the ability to efficiently print in multiple colors. Ink-jet printing would avoid these limitations, but in order to be effective, very fast drying inks must be used. In fact, due to the need to immediately handle printed papers as described previously, even inks that may otherwise be considered fast drying or waterfast may not be fast enough for POS applications.
There are several properties that one can consider when determining whether an ink is a good candidate for POS applications. Some of these include rapid printing capability, low toxicity, infrequent changing of ink cartridge, good decap, fast drying, at least equal in print quality to other technologies in the field, and adequate optical density. Of these properties, rapid printing capability, low toxicity, and fast drying properties are particularly important. Rapid print capabilities are accomplished by high frequency printing. For example, about 1.5 kHz can implemented, or even up to 3 kHz or greater can be effective for point-of-sale applications. With respect to low toxicity, ink compositions that are environmentally benign or have low toxicity are desired. This is because point-of-sale prints will likely be handled extensively, both by clerks and customers. Additionally, when discussing fast drying, what is meant is the ability of an ink to dry in a fraction of a second. In POS applications, the ink-jet ink should dry nearly instantaneously, since upon completion of printing a receipt, it will likely be immediately handled as described. Additionally, prior to handling, the receipt generally touches a tear bar on the printer above the print zone. Typically, this occurs approximately 300 msecs after printing a swath, and if the ink is not substantially dry, the tear bar can also smear the ink. Thus, to avoid smudges on the receipt and ink stains on the hands of the clerk or the customer, the receipt must be essentially dry prior to any opportunity for a person to handle the receipt, and preferably prior to the receipt touching the tear bar of the printing machine. With this in mind, it would be desirable to provide various ink-jet ink compositions that are environmentally friendly and can be used with POS apparatuses, taking in to account the challenges associated with POS applications.
SUMMARY OF THE INVENTION
A waterfast, environmentally friendly ink-jet ink, is disclosed comprising from 1% to 90% by weight of a first humectant selected from the group consisting of glycerol, propanediol, and combinations thereof; from 1% to 25% by weight of a second humectant selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and combinations thereof; from 1% to 20% by weight of a drying agent selected from the group consisting of 1,2-hexanediol, 1,2-pentanediol, and combinations thereof; from 0% to 20% by weight of 2-pyrrolidone; from 0.05% to 10.0% by weight of a waterfastness control dye selected from the group consisting of azo-containing dyes and phthalocyanine-containing dyes; and at least one additional dye present at from about 1.0% to 10.0% by weight. If the waterfastness control dye is an azo-containing dye, such dyes can include Direct Red 227, Direct Red 254, Direct Yellow 86, and Acid Orange 7. Alternatively, if the waterfastness control dye is a phthalocyanine-containing dye, then nickel, copper, and/or aluminum phthalocyanines can be used.
In one embodiment, the first humectant, the second humectant, and the 2-pyrrolidone of the above composition can be present such that a total weight percentage of these three components is from 30% to 90% by weight. In an alternative embodiment, when the total weight percentage of these three components, i.e., first humectant, second humectant, and 2-pyrrolidone, is greater than about 30%, only one dye is required to be present.
Additionally, a fast drying, environmentally friendly ink-jet ink composition for POS applications is disclosed having a dye load comprising from 0.05% to 1.0% by weight of a waterfastness control dye selected from the group consisting of azo-containing dyes and phthalocyanine-containing dyes; and at least one additional dye present at from about 1.0% to 10.0% by weight, with the proviso that the total dye load be at least 2% by weight, and wherein the ink-jet ink is substantially non-toxic.
A point-of-sale printing system is also disclosed, comprising a non-toxic ink-jet ink; a point-of-sale (POS) paper configured for accepting printed ink-jet ink; and an ink-jet pen configured for rapid printing of the ink-jet ink onto the paper, wherein the ink-jet ink printed on the paper has a drytime of less than 300 msec, and wherein the ink-jet ink exhibits good long-term decap performance, i.e., on the order of multiple weeks.
DETAILED DESCRIPTION OF THE INVENTION
Before the present invention is disclosed and described, it is to be understood that this invention is not limited to the particular process steps and materials disclosed herein because such process steps and materials may vary somewhat. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only. The terms are not intended to be limiting because the scope of the present invention is intended to be limited only by the appended claims and equivalents thereof.
The singular forms “a,” “an,” and, “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an ink” includes reference to one or more of such inks.
As used herein, “effective amount” refers to the minimal amount of a substance or agent, which is sufficient to achieve a desire effect. For example, an effective amount of an “ink vehicle” is the minimum amount required in order to create ink, which will meet functional performance and characteristic standards set forth herein.
As used herein, “ink vehicle,” refers to the vehicle in which dyes are placed to form an ink. Ink vehicles are well known in the art, and a wide variety of ink vehicles may be used with the ink composition of the present invention. Such ink vehicles may include a mixture of a variety of different agents, including without limitation, surfactants, solvents, co-solvents, buffers, biocides, viscosity modifiers, surface-active age
Chen Xiaohe
Sarkisian George M.
Tyvoll David
Hewlett--Packard Development Company, L.P.
Klemanski Helene
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