Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-06-07
2002-02-26
Jagannathan, Vasu (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S211000, C524S213000
Reexamination Certificate
active
06350795
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to ink compositions and, more specifically, the present invention relates to conductive inks which have the power or quality of transmitting electrical signals generated by electric field assisted acoustic ink jet printing processes and apparatuses, resulting in controlled ink jettability which in turn improves the edge raggedness of the images. The conductivity of a material can be measured in terms of reciprocal of resistivity, which is the capacity for electrical resistance. The conductivity values of the invention inks expressed as log(pico.mho/cm) and recited herein were measured under melt conditions at 150° C. by placing an aluminum electrode in the molten ink and reading the resistivity output on a GenRad 1689 precision RLC Digibridge at a frequency of 1 K.Hz. Conductivity expressed in terms of [log(pico.mho/cm)] is calculated from the reciprocal of resistivity. Generally, the invention inks possess conductivity values in the range of from about 2 to about 8.5 log(picomho/cm), and preferably in the range of from about 6 to about 8.5 log(picomho/cm), with a melting point of between about 60° C. and about 150° C., and preferably between about 70° C. to about 90° C., and such inks are especially useful for electric field assisted acoustic ink jet printing with enhanced jettability, processes and apparatuses, reference, for example, U.S. Pat. No. 5,121,141, U.S. Pat. No. 5,111,220, and U.S. Pat. No. 5,371,531, the disclosures of which are totally incorporated herein by reference, including especially acoustic ink processes as illustrated in some of the aforementioned copending applications and patents, such as an acoustic ink printer for printing images on a record medium.
The inks of the present invention in embodiments thereof can be considered a phase change ink, that is, for example, an ink that changes, for example, the crystal structure of the entire ink components so it is a physico-chemical process that is, for example, more physical rather than chemical, from a liquid state to solid state in a suitable period of time, for example, from about 1 to about 100 milliseconds, and preferably in less than about 10, such as from about 2 to about 7 milliseconds; (1) a conductive mixture of a urea or a thiourea compound and an oxyalkylene compound having a melting point of lower than about 120° C., and preferably between about 75° C. to about 100° C., that, for example, can fill the pores of the paper and with a low acoustic loss value of below about 100 dB/mm; (2) a polymeric binder having a melting point of between about 60° C. to about 120° C., and preferable between about 80° C. to about 100° C., that can improve the adhesion of ink to paper; (3) a lightfast UV absorber; (4) a lightfast antioxidant; (5) and a colorant such as a dye, a pigment or mixtures thereof.
More specifically, the present invention is directed to phase-change acoustic ink compositions comprised of (1) a conductive mixture of an organic compound such as urea, thiourea, and their derivatives and an oxyalkylene compound such as oxyalkylene bisamides such as N,N′-propyleneoxy-propyleneoxy-propylene)-bis-stearamide; N, N′-propyleneoxy-propyleneoxy-propylene oxy-propylene-)-bis-stearamide; poly(alkyleneoxide) alkylates such as N,N′-(ethyleneoxy-ethyleneoxy-ethyleneoxy-ethyleneoxy-ethylene)-stearate; polyoxa-alkanedioate diester such as distearyl-3,6,9-trioxaundecanedioate, having a melting point of between about 75 and about 100° C., and having low acoustic loss and which acoustic loss is below about 100 dB/mm, and preferably in the range of between 25 to about 80 dB/mm; (2) a polymeric binder with, for example, a melting point of between 60 about to about 120° C., and preferably between about 80° C. to about 100° C. enables, for example, adhesion of ink to paper; (3) a UV absorber such as 2,2,6,6-tetramethyl-4-piperidinyl/&bgr;,&bgr;,&bgr;′,&bgr;′-tetramethyl-3,9-(2,4,8,10-tetraoxospiro(5,5)-undecane) diethyl]-1,2,3,4-butane tetracarboxylate; (4) an antioxidant such as antimony dialkyl phosphorodithioate; (5) a colorant, and wherein there can be generated with such inks excellent developed images on plain and coated papers with acceptable image permanence, excellent projection efficiency on transparencies without a post fusing step, and excellent crease resistance, and wherein the inks possess acceptable, and in embodiments superior lightfast, between about 90 to about 100 percent and superior waterfast between about 95 to about 100 percent values. Moreover, in embodiments of the present invention there is enabled the elimination, or minimization of undesirable paper curl since water need not be present, or minimum amounts less than about 1 percent of water may be selected in embodiments in the invention inks, and it is preferred that there be an absence of water. When water is not present in the inks, a dryer can be avoided thereby minimizing the cost of the acoustic ink jet apparatus and process.
PRIOR ART
U.S. Pat. No. 5,286,288 discloses a hot melt ink composition for use in continuous ink jet printing comprising an electrolyte, an electrolyte-solvating and dissociating compound and an image-forming agent, said ink being solid at about 25° C., said ink liquefying at a temperature between 75° C. and 175° C., and said ink in the liquid stage having a conductivity of greater than about 100 microsiemens/cm 8[log(pico.mho/cm)].
The use of quaternary ammonium compounds as conductivity enhancing agents is known, reference, for example, U.S. Pat. No. 3,985,663 which discloses conductive inks containing quaternary ammonium compounds. The liquid developer has a viscosity suitable for convenient application to an imaged surface in the development of latent electrostatic images and has improved conductivity resulting from incorporating conductivity control agents in the form of quaternary ammonium compounds which are soluble in the carrier of the ink composition. The conductive ink composition can comprise a coloring agent, optionally a binder and a dispersing agent, a carrier and a quaternary ammonium compound soluble in the liquid carrier.
U.S. Pat. No. 5,382,492 discloses quaternary ammonium compounds as charge adjuvants for positive electrostatic liquid developers consisting essentially of (A) a nonpolar liquid having a Kauri-butanol value of less than 30, present in a major amount; (B) thermoplastic resin particles having dispersed therein a quaternary ammonium compound which is substantially insoluble in the nonpolar liquid; (C) a nonpolar liquid soluble ionic or zwitterionic charge director compound. The process of preparation of the electrostatic liquid developer is described. The liquid developers are useful in copying, color proofing including digital color proofing, lithographic printing plates and resists. The conductive inks of this prior art contain thermoplastic resins which can increase the viscosity of inks above, for example, 20 cps at the jetting temperatures of acoustic ink jet printing. The inks of the present invention possesses conductivity of, for example, in the range of 6.4 to about 7.0 [log(pico.mho/cm)] and are less conductive than those of U.S. Pat. No. 5,382,492 but have lower viscosities in the range of, for example, from about 5 to about 6 cps at a temperature of between about 120° C. to about 150° C. as required for acoustic ink jet printing.
The use of mineral acid salts or organic acid salts in aqueous polar inks are known, reference, for example, U.S. Pat. No. 5,518,534 which discloses an ink set and process for alleviating bleed in printed elements employing a first ink and a second ink, each containing an aqueous carrier medium and a colorant; the colorant in the first ink being a pigment dispersion and the second ink containing a salt of an organic acid or mineral acid having a solubility of at least 10 percent in 100 percent of water at 25° C.
U.S. Pat. No. 5,531,818 discloses a thermal ink jet printing process which comprises (a) incorporating in
Boils Danielle C.
Breton Marcel P.
Malhotra Shadi L.
Wong Raymond W.
Jagannathan Vasu
Palazzo E. O.
Shosho Callie E.
Xerox Corporation
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