Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1999-11-29
2001-08-07
Dawson, Robert (Department: 1712)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031130, C106S031290, C106S031570, C106S031610, C106S287100, C106S311000, C523S161000, C524S588000, C525S474000
Reexamination Certificate
active
06270561
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to hot melt ink compositions for two- and three-dimensional inkjet printing applications. More particularly, this invention relates to hot melt ink compositions comprising materials that contain silsesquioxane compounds and reactive moieties such as aniline, pyrrole and thiophene.
This invention also relates to optional post printing treatment processes to increase mechanical properties, optical density, electrical conductivity and dryness of the printed images and objects.
BACKGROUND OF THE INVENTION
Hot melt inks for inkjet printing are characterized by being solid at ambient temperature and liquid at printer operating temperature. Hot melt inks are advantageous over liquid ink because transportation is easier, solvent evaporation and viscosity changes are of no concern. Hot melt inks provide better print quality and resolution since the inks solidify and dry more quickly without wicking into the substrate.
Thus, solid hot melt inks are loaded in a printer capable of melting the ink in the inkjet printer head, ejecting the liquid ink which quickly resolidifies upon impacting a substrate. Conventional hot melt inkjet printers operate with a printing head and inkjet temperature of about 120 to about 150 C. At those temperatures, the solid ink is melted to a low viscosity liquid, generally about 8 to 25 cP when measured at jetting temperature. To form a three-dimensional solid object, the ink jet operation is repeated over several passes so that an object is formed layer by layer.
Hot melt inks generally comprise colorant inks such as dyes and pigments along with base materials commonly referred to as ink vehicles. Conventional ink vehicles generally include various proportions of resins, plasticizers, tackifiers, viscosity modifiers and antioxidants.
PCT patent application WO 9414902 describes hot melt inks for inkjet printing which comprise colorants and urethane oligomers as ink vehicles and which were obtained by reacting diisocyanate compounds with various aliphatic alcohol.
PCT patent application WO 9712003 describes hot melt inks for inkjet printing which comprise colorants and ink vehicle and which were obtained by reacting a mono- or diisocyanate with one or more functional amide materials.
U.S. Pat. No. 4,889,560 teaches the preparation of hot melt inks comprising colorants and an ink vehicle. The ink vehicle is described as containing fatty mono-amide and tetra-amide compounds. The ratio of tetra-amide to mono-amide varies between 2 to 1 and 1 to 10.
U.S. Pat. No. 5,597,856 teaches the preparation of hot melt inks comprising colorants and an ink vehicle. The ink vehicle is described as containing a mixture of mono-amide, unsaturated amide and tetra-amide compounds.
U.S. Pat. Nos. 5,750,604; 5,780,528; and 5,783,658 teach the preparation of hot melt inks for inkjet printing which comprise colorants and ink vehicles containing urethane-urea and urea-urea compounds.
U.S. Pat. No. 5,902,841 teaches the preparation of hot melt inks comprising colorants and an ink vehicle. The ink vehicle is described as containing hydroxy functional fatty amide compounds.
U.S. Pat. Nos. 5,777,023 and 5,881,648 teach the preparation of hot melt inks comprising colorants and an ink vehicle. The ink vehicle is described as containing diamidediurethane compounds obtained by reacting monoamine and diisocyanate or diamine and isocyanate.
Although meritorious, the hot melt inks for inkjet printing processes taught in the prior art suffer multiple drawbacks and disadvantages once jetted on a substrate, such as poor mechanical properties and tackiness upon touch.
Furthermore, none of the prior art hot melt inks contain silicon-based materials such as the polyhedral silsesquioxanes described in the present invention.
As a result, there remains an important need for new hot melt ink compositions with improved dryness to touch and improved mechanical properties. Also needed are novel hot melt ink jet compositions allowing for post printing treatment processes to further increase mechanical durability, optical density, electrical conductivity and dryness.
SUMMARY OF THE INVENTION
This invention relates hot melt ink compositions for two- and three-dimensional inkjet printing applications. The hot melt ink compositions of this invention comprise colorants and ink vehicle.
The first aspect of this invention is related to the ink vehicle for the hot melt ink compositions comprising silsesquioxanes to provide excellent mechanical properties as well as dry, non-tacky printed images and objects. Thus, there is provided a hot melt ink comprising a colorant ink and an ink vehicle wherein the ink vehicle comprises at least one polyhedral silsesquioxane compound present in a proportion of about 0.1 to 30 wt % based on the total weight of the hot melt ink composition.
Another aspect of this invention is also related to the ink vehicle for the hot melt compositions. The ink vehicle comprises, in addition to silsesquioxane compounds, molecular, oligomeric or polymeric materials, which contain reactive moieties, such as aniline, diphenylamine, pyrrole, thiophene and their substituted derivatives. These reactive moieties allow the printing images and objects to undergo crosslinking reactions and polymerization via post treatment processes to increase further mechanical properties, optical density, electrical conductivity and dryness.
Another aspect of this invention is related to the post treatment processes of the printing images or objects. The post treatment processes can be achieved by contacting the printing images or objects with aqueous or organic solutions containing oxidizing agents such as ammonium persulfate, iron chloride and copper perchlorate or other suitable oxidizing agents. Furthermore, the post treatment process can be employed to deposit a thin layer of copper, silver, tin or other metals on the printed ink images or objects by electroless deposition techniques.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates hot melt ink compositions for two- and three-dimensional inkjet printing applications. The hot melt ink compositions of this invention comprise colorants and ink vehicle.
Hot melt inks generally comprise colorant inks such as dyes and pigments along with base materials commonly referred to as ink vehicles. Conventional ink vehicles generally include various proportions of resins, plasticizers, tackifiers, viscosity modifiers and antioxidants.
It is of course to be understood that a variety of known compounds could be used as resins, plasticizers, tackifiers, viscosity modifiers or antioxidants. Viscosity modifiers are generally low viscosity compounds, preferably less than 5 Cp which help lower the overall viscosity of the ink vehicle. Of course, some compounds used in the ink vehicle can play more than one role, for example a commercially available tackifier such as Cellolyn 21 (available from RHO Chemicals) can play a dual role of plasticizer and tackifier.
The first aspect of this invention is related to the ink vehicle for the hot melt ink compositions comprising silsesquioxanes or oligomers and polymers that contain silsesquioxane moieties. The presence of silsesquioxanes in the ink vehicle provides excellent mechanical properties and non-tacky printed images and objects.
Silsesquioxanes are polyhedral siloxane cage (commonly called POSS) that are generally characterized by the formula [RSiO
3/2
]
n
, where n is an even number greater than 4 and R may be hydrogen as well as inorganic or organic substitutents. Silsesquioxanes are generally obtained via hydrolysis of trichlorosilanes or trialkoxysilanes. A comprehensive review of the synthesis and properties of silsesquioxanes was published by R. Baney, M. Ito, A. Sakasibara and T. Suzuki in Chemical Review, 1995, 95, 1409-1430.
Preferred silsesquioxanes, oligomers and polymers containing silsesquioxane moieties of this invention are waxy or solid powder having a melting point between 30 and 140° C. Examples of preferred silsesquioxanes of this invention are:
1,3,5,7,9,1
American Dye Source, Inc.
Dawson Robert
Dubuc Goudreau Gage
Robertson Jeffrey B.
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